CONTROL & INSTRUMENT INDEX SYSTEMS UNDER C&I DEPARTMENT DISTRIBUTED CONTROL SYSTEM (DCS) SYMPHONY HARMONY INFI 90 SYSTEM COMPOSER™ SYSTEM EMERGENCY TRIP SYSTEM (ETS) FURNACE SAFEGUARD SUPERVISORY SYSTEM (FSSS) LOCAL IGNITION CONTROL SYSTEM UPS GENERAL DESCRIPTION MULTI FLAME DETECTOR CONTROL UNIT & FLAME SCANNER DEH SYSTEM HART SYSTEM MACHINE MONITORING SYSTEM (MMS) TURBINE SUPERVISORY INSTRUMENTATION (TSI) HPLP BYPASS CCTV SYSTEM RUNBACK MIS SYSTEM (PGIM) ENTERPRISE ASSET MAINTENANCE (MAXIMO) GPS SYSTEM CMS BOILER TUBE LEAKAGE DETECTION SYSTEM
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CONTROL & INSTRUMENT INDEX SYSTEMS UNDER C&I DEPARTMENT DISTRIBUTED CONTROL SYSTEM (DCS) SYMPHONY HARMONY INFI 90 SYSTEM COMPOSER™ SYSTEM EMERGENCY TRIP SYSTEM (ETS) FURNACE SAFEGUARD SUPERVISORY SYSTEM (FSSS) LOCAL IGNITION CONTROL SYSTEM UPS GENERAL DESCRIPTION MULTI FLAME DETECTOR CONTROL UNIT & FLAME
SCANNER DEH SYSTEM HART SYSTEM MACHINE MONITORING SYSTEM (MMS) TURBINE SUPERVISORY INSTRUMENTATION (TSI) HPLP BYPASS CCTV SYSTEM RUNBACK MIS SYSTEM (PGIM)
ENTERPRISE ASSET MAINTENANCE (MAXIMO)
GPS SYSTEM
CMS
BOILER TUBE LEAKAGE DETECTION SYSTEM
Systems Under C&I department, SgTPP
IPH SYSTEMS
C&I department is entrusted for maintaining System Automation at all areas of
Power Plant except CHP. The areas under their scope is as following:
1. Distributed Control System (Symphony Harmony 50 System, Make-ABB) with
its panels, Controllers, Modules, power supply, network & HMI
4 MENU KEYPAD Allow to brows the MFD option and program the
operating parameters
5 DB9
CONNECTOR
“COM”
RS232 isolated serial output
When “NET” LED (8) is on the RS232 is accessing
the network
6 SET UP MODE
TOGGLE
Enabled/disabled set up function. When LED is
flickering set-up is enabled
7 SAFE LED When on it indicates the MFD has no failure and the
relevant Watch Dog relay is energized
2 UVISOR FLAME SCANNERS UR600
Scanner UR 600 is in explosion proof construction, CESI certificate No. AD 83.062
ext. 02/89 EExd, according to CENELEC Standards EN 50.014-1977 (CEI 31/8/78)
and EN 50.018-1977 (CEI 31/1/78), FM and CSA. The case has an IP66 (NEMA 4X)
degree of protection in accordance with IEC standards 144-1963.
The Scanner UR 600 IR houses a glass lens, a PbS photoresistor sensing element
and a signal conditioning / pre-amplification PCB. Terminals to the control unit are
screw type.
The Scanner UR 600 is also available in special versions with rigid or flexible probe
capable to collect signals in the nearest of the flame inside the combustion chamber,
and suitable for installation in corner-fired application.
• SCANNER UR 600
In both the direct view and extended version, the flame detection and discrimination
is bases on the capability of the scanner UR 600 Model IR to sense the IR
wavelength.
The PbS photo resistor sensitive element reacts to the dynamic characteristics of the
intensity of IR radiations issued mainly by the flame in the zone where primary
combustion takes place (flame root).
The pre-amplification circuit, hosed in the scanner head, conditions the electrical
signal to be transferred to a remote location where the control unit MFD.SA is
installed.
• SELF-CHECKING
The MFD.SA control unit cyclically executes a self-checking task. In case an error is
detected the watchdog is reset and a message appears. The IR PbS photo resistor is
an intrinsically fail-safe device; it reacts to the flame presence only, providing an AC
signal (flickering) to the MFD.SA, which energizes the flame relay.
The MFD.SA performs the self-check removing the bias voltage from the sensor
element. No electromechanical shutter is involved.
The following checks are made:
- Self-checking loop integrity.
- Ripple detection.
During self-check an error message IRSC is generated if the flame signal does not
go to zero within a selected time, while the error message IRBL is generated in case
of short circuit on the self-checking loop.
During self-check an error message IRSC is generated if the flame signal does not
go to zero within a selected time, while the error message IRBL is generated in case
of short circuit on the self-checking loop.
Self-check continues testing the programmable cut-off filters.
Four combinations of pass-band are set and for each one of them the filter behaviour
is checked.
In case of fault a specific error message appears and the Flame signal is forced OFF.
Also in this case, the control is repeated cyclically and the normal situation is
restored in case of Flame detected and successful tests.
DEH System With the progress of computer technology, the Distributed Computer System (DSC)
control based on microprocessors is more and more widely used. The emergence of
digital electro-hyraulic (DEH) control systems has broken the fact that the adjustment
of steam turbine could only be finished by the special steam turbine maintainers who
were heat engineers more often than not. Meanwhile, for turbine operators, besides
the technological process of the control system, computer knowledge is also very
important. Aiming at the new generation 300MW DEH control system that is jointly
developed by Dongfang Steam Turbine Works (DFSTW) and ABB SYMPHONY, this
instruction book presents the basic concepts of steam turbine control system, the
configuration of DEH, and the primary functions, operation specifications, and
installation and debugging methods of a control system.
Control System Principle
For our D300N steam turbine generator unit, the high-pressure (hereafter referred to
as HP) steam admission is controlled by 2 HP stop valves (hereafter referred to as
MSV) and 4 HP control valves (hereafter referred to as CV), and the intermidiate-
pressure (hereafter referred to as IP) steam admission is controlled by 2 IP stop
valves (hereafter referred to as RSV) and 2 IP control valves (hereafter referred to as
ICV). All the above 6 admission control valves are driven by hydraulic actuators to
meet the requirements of short action time and high positioning accuracy.
Normally the working rotation speed of the steam turbine is 3000r/min; however,
when the load in the grid varies, the actual rotation speed will change with it. The
speed measurement part of the steam turbine control system will measure the actual
speed and compare it with the rated speed 3000r/min, and then, through frequency
difference amplification and regulator servo control, control the opening extent of CVs
and ICVs to form a negative feedback of rotation speed, which will keep the rotation
speed within a preset range.
All the above-mentioned 10 admission valves are driven by oil servo motors that
adopt HP fire-resistant oil as working medium. Except the six control valves (CVs and
ICVs) that are controlled continuously by using servo valves and microcomputer
interface of DEH, the rest two RSVs and two MSVs are controlled by solenoid valves
and DEH interface in a two-digit way.
In order to guarantee a safe operation, several redundant protection sleeves are
available in the hydraulic system:
Emergency tripping devices and testing solenoid valves;
HP and LP stop solenoid valves;
Overspeed restriction solenoid valve.
For the oil sources of HP fire-resistant oil, 2 redundant pressure oil pumps are also
available to guarantee a continuous oil supply. For detail, see the specifications for
hydraulic system.
The combined start by HP and IP cylinders is a traditional mode. With this method,
the steam simultaneously enters into HP cylinder (intermediate pressure cylinder) by
way of CV (ICV) from superheater (intermediate superheater) and finally brings the
steam turbine to a rated operating state. During the start, in order to reduce the
throttling loss from ICV, the influence resulting from intermediate superheater needs
to be reduced. Under their respective working pressures, the ratio of the flow
capacity of CV to that of ICV is 1:3.
During the start, in general a full-admission method (throttle regulation) will be
adopted for the HP cylinder, so that the heat exposure will be uniform and thus the
heat stress will be reduced to the minimum. Under normal operation, because the
temperature field in the cylinder is roughly stable, a partial admission method (nozzle
regulation) will be adopted for the HP cylinder, so that the throttling loss can be
reduced and the efficiency can be improved.
During the start, because the physical dimensions of rotor and cylinder are very large
and the temperature of the heating surface builds up quickly, staying at certain points
during speed raising and load up is required to reduce the heat stress of steam
turbine. This is called warm-up of turbine.
A rotor has its inherent natural frequency of vibration. During the rotating of a rotor,
when the exciting frequency resulting from the eccentric mass occurring prior to
reaching equilibrium is in agreement with the natural frequency of vibration,
resonance will occur; at this point the rotation speed is called critical speed of
rotation. The resonance amplitude will increase with time, and too large a amplitude
will destroy the steam turbine generator unit; therefore, it is required that the steam
turbine shall rush through the zone in which critical speed of rotation occurs.
In general a steam turbine generator unit is required to operate in a grid.
Synchronous grid-connection means a process in which a steam turbine generator
unit is connected to an electric grid after it reaches its running rotation speed. The
conditions for synchronous grid-connection are that the switch is closed and the
potential difference of phase between both sides (generator, electric grid) of oil switch
is equal to zero, that is, both sides have the same phase sequence, voltage,
frequency, and phase.
The EHC adopts ABB’s advanced open industrial control system,
SYMPHONY ,which includes 1 printer, 1 application operating station (with the
functions of operator station (hereafter referred to as OIS) and engineering work
station (hereafter referred to as EWS)).
OIS is a major device used to conduct a human-computer dialogue between power
plant operators and steam turbine control systems.
The printer is used to record all kinds of inportant data and keep them in the archives
when necessary.
EWSs facilitate the design, debugging, and revising of control logic.
The DEH adopts two-circuit AC 240VAC UPS for power supply and has redundancy
design in the interior. The internal power supply of SYMPHON is realized by Industry
Power Module (hereafter referred to as IPM). One advantage is that the failure of one
power supply module will not affect the whole power supply; and the design is also
featured by good heat dispersion, simpleness, flexibility, safety, and high quality.
Every card has a power supply with both master and auxiliary IPMs.
Based on a design concept of decentralized control, the control system exercises its
automatic control by using a hydraulic servo system with SYMPHONY function
module configurations. The package unit consists of serialized standard hardware
modules, each of which can complete its respective functions independently and can
communicate with each other.
Major functions of the control system are as follows:
Automatic setting of static relation of servo system;
Remote latching-on prior to start;
Automatic thermal condition judgement;
HIP CV start mode
Full-range automatic closed-loop control of rotation speed from hand-turning speed
to rated speed;
Overspeed control and overspeed protection functions available;
Able to realize rapid synchronous grid-connection with the interface of automatic
synchronization installation;
Flexible selection between power control and valve position control and free
switching;
Valve management functions available;
On-line HIP SV and HIP CV activity tests available;
Able to realize remote spray oil testing and automatic latching-on after testing;
On-line HP tripping solenoid valve testing available;
Mechanical and electric overspeed testing available;
Throttle Pressure Control (TPC), load control, and valve position control functions
availale;
DEH-controlled SV and CV leak testing available
Cooperating with CCS to realize RUNBACK functions;
Cooperating with CCS to finish unit-boiler coordination control;
Sound parameter monitoring functions available;
ATC control available.
1 Automatic setting of static relation of servo system
Prior to the start of a unit, the static relation setting for servo valves, LVDTs, and
servoboards must be completed to guarantee the control accuracy and linearity of all
servoactuators so that the unit's requirement for the static relation of the servo system
can be met. Such valves as CV, ICV, and MSV can be checked simultaneously or
respectively. The process goes on at the OIS display.
1 The setting of static relation for a servo system prior to the start of a unit must fulfill
the following conditions:
Latching-on is available for the steam turbine.
All valves have been closed.
No steam is allowed in front of a SV; otherwise, when the valve is under check and
the rotation speed of the unit is greater than 100r/min, DEH will conduct tripping
automatically. In other words, the rotation speed of the steam turbine must be less
than 100r/min.
2 Calibration procedures
a) Enter into OIS "STEAM TURBINE VALVE CALIBRATION" picture, and select
"SINGLE CALIBRATION PERMIT" or "DOUBLE CALIBRATION PERMIT" (Both can be
selected simultaneously for off-line calibration, but only one of them can be selected for
on-line calibration).
b) When "SINGLE CALIBRATION PERMIT" is lit, only the valves of odd number can be
selected for calibration; when "DOUBLE CALIBRATION PERMIT" is lit, only the valves
of even number can be selected for calibration. Select the valve to be checked, the
corresponding key is lit.
c) After selecting the valve for check, begin to check the corresponding servoboard, and
at this time the "CHK" light on the servoboard begin to flicker (down flicker frequency is
slow but up flicker frequency is fast), meanwhile the "VALVE CALIBRATION IN
PROGRESS" light also begin to flicker (the same flicker frequency with that of "CHK"
light).
d) When "CHK" light and "VALVE CALIBRATION IN PROGRESS" light are normally on,
the check is over.
e) Again click the "single CALIBRATION" or "double CALIBRATION" buttons to quit from
the check mode, and at this time the "CHK" light is off and the "VALVE CALIBRATION
IN PROGRESS" light turns grey.
f) After finishing the check, inspect the static relation. Through the OIS station send out
a valve opening instruction, then check whether the opening instructions and the actual
valve opening meet the static relation's requirements; if not, conduct setting again
according to the above steps.
2 Automatic thermal condition judgement
A steam turbine's start process is also a heating process for both the steam turbine and
its rotor. In order to reduce the heat stress resulting from start, for different initial
temperature, different start curve shall be adopted.
Every time when latching-on is conducted for DEH, the thermal state of the turbine is
automatically determined based on the temperature of the inner upper wall of the HP
inner casing at the control stage of the unit. If the temperature signal from the upper wall
fails, it wall be replaced by that of the lower wall automatically.
T≤150°C Cold state;
150°C<T<300°C Mild state;
300°C≤T<400°C Hot state;
400°C≤T Extremely hot state.
3 Automatic remote latching-on prior to start
Prior to start, first generate an latching-on instruction through OIS; then reset the testing
valve block to make the emergency tripping device engaged. After latching-on, a HP
safe oil pressure is established, and all SVs and CVs are in a close state.
Permissive conditions for latching-on:
Tripping of steam turbine;
All valves in a full close state.
Push the "RESET" button in the OIS "AUTOMATIC CONTROL" menu, then the HP
tripping solenoid valve acts, the oil pressure in the upper chamber of the slide valve on
the emergency governor gear is established, and HP security oil is established; at this
time the OIS "AUTOMATIC CONTROL" menu displays the "RESET" status of the steam
turbine.
4 Startup and operating mode
1 Prewarming of HP cylinder
Prior to start, prewarming can be conducted through introducing HP by-pass steam to
the HP cylinder by way of RFV prewarming valve and HP cylinder's steam outlet.
Drivers send out a prewarming instruction to open the prewarming valve RFV, close the
vacuum valve VV, and close the HP exhaust check valve. When the temperature of the
HP cylinder reaches the specified value, keep warming for an hour, and close RFV, so
the prewarming of HP cylinder is completed.
2 HP SV (HP stop valve) prewarming
Operators send out a prewarming instruction to open 10% of the HP SV in one side and
introduce main steam into the two SVs; when the temperature of the valve bodies
reaches the specified value, the prewarming is over and the HP SV shall be closed.
3 Startup mode
3.1 Intermediate pressure (IP) cylinder start
After the prewarming is completed and the start condition is available, open VV. Select
the "STARTUP MODE" button in OIS, and then select the "IP CYLINDER STARTUP"
mode. The IP control valve will be open gradually and the speed of the unit will be
raised to 3000r/min. After grid connection, the unit has an initial load. Set up the target
load and load rate. Push the "PROCEEDING/HOLD" button. At this time a
"PROCEEDING" status displays on the menu and the unit begin to raise its load. In
order to keep the reheating pressure constant, the lower by-pass system begins to
close gradually; when the lower by-pass system is fully closed, HP and IP cylinder
switching can be conducted. Push the "CYLINDER SWITCHING" button, the switching
of HP and IP cylinder begins, that is, the IP control valve opens gradually. In order to
keep the throttle pressure constant, the higher by-pass system begins to close. When
the steam admission ratio of HP cylinder to IP cylinder reaches 1:3, it is thought that the
switch is over. HP and IP control valves participate in control simultaneously. When the
cylinder switching is in progress, the load control will be cancelled and the VV will be
closed.
3.2 Combined start by HP and IP cylinders
When the by-pass system has performance problems or hot state and extremely hot
state are used for start, a combined start mode by adopting HP and IP cylinders can be
adopted; at this point HP and IP control valves are opened simultaneously.
5 Speed control
Prior to the grid-connection of steam turbine generator unit, DEH is a rotation-speed
closed-loop isochronous control system. Its set point is the setting rotation speed.
Through the calculation of PID regulator, the servo system uses the difference of setting
speed and actual speed to control the opening of the oil servo motor, making the actual
speed vary with the setting speed. As per different start modes, the oil servo motor is
ICV or CV and ICV.
After a target speed is set, the setting speed automatically approaches the target speed
with a setting acceleration rate. When the speed reaches the critical speed zone, the
acceleration rate will be automatically changed into 400r/min/min. During speed raising,
often the steam turbine needs to be heated in medium or high speed to reduce heat
stress.
1 Target rotation speed
Except the target rotation speed set up by operators through OIS, under the following
conditions, DEH automatically set up the target speed:
When the steam turbine is just engaged, the target is the current rotation speed;
When the oil switch is just disconnected, the target is 3000r/min;
In a manual state, the target is the current rotation speed;
When the turbine has tripped, the target is zero.
When the target exceeds the upper limit, it has been changed into 3060 or 3360r/min;
In a self-start mode, the target depends on ATC;
In synchronization, the target varies with the change of the synchronous fluctuation
signals (rate of change 60r/min/min).
When the target is set in the critical range by mistake, it has been changed to a specific
critical value.
2 Acceleration rate
Set by operator, within (0~400) r/min/min;
Under a self-stardup mode, 120, 180, 360r/min/min;
Within the critical speed range, 400r/min/min.
3 Critical speed of rotation
The calculated values of combined critical speed are:
First-order: 1399r/min electric machine rotor first order
Second-order: 1679r/min HIP rotor first order
Third-order: 1753r/min LP rotor first order
Fourth-order: 3465r/min electric machine rotor second order
In order to avoid the critical speed of rotation, DEH sets up two critical speed zones, the
range of which is about ±50r/min different from the calculated values of the critical
speed. If the measured critical speed is greatly deviated from the calculated value, the
critical speed zone value and the critical speed plateau value must be revised.
Warm-up of turbine
The warm-up rotation speed depends on the specific unit, and each unit has its own
warm-up speed. When the target rotation speed is reached, the speed raising can be
ceased for warm-up. If intermitting is required during speed raising, the following
operations can be conducted:
When not in an ATC mode, the operator sends out a "HOLD" instruction;
When in an ATC mode, the operator sends out a "HOLD" instruction after the system
quits from the ATC mode.
Within the critical speed zone, the hold instruction is invalid, and only the target rotation
speed can be modified.
Note: during the warm-up, the resonant frequency with rotor and blades must be
avoided.
4 3000r/min constant speed
When the steam turbine's speed is stabilized above 3000±2r/min, all systems conduct
an inspection for grid connection. A pseudo grid connection test is conducted for the
generator to check the reliability of the automatic synchronous system and the accuracy
of adjustment. During the test period, the isolating switch on the side of generator power
grid is disconnected and a pseudo grid connection test signal is sent out. As the normal
condition, the automatic synchronous system changes the frequency and voltage of
generator through DEH and generator excited system. When the synchronization
condition is met, the oil switch is closed. Because the isolating switch is disconnected,
actually the generator is not grid-connected.
As a result, during the pseudo synchronization testing, when DEH receives the pseudo
grid connection test signals and the oil switch is closed, it does not judge that the
generator is grid-connected. In this way, an initial load resulting from grid connection
and the resultant speed rising can be avoided.
During speed rising, warm-up is required. Push down the "HOLD" button in the
"AUTOMATIC CONTROL" menu of OIS. At this point, the OIS menu displays a "HOLD"
status, and the rotation speed keeps constant for warm-up. If the unit is stepping across
the critical zone, the operation of clicking "HOLD" button will be invalid.
Attention: in some works, for no DI signal of pseudo grid connection is sent to DEH,
during the test no grid connection signals can be sent to DEH; otherwise, DEH will think
that the unit has been grid-connected and thus turn up the control valve with an initial
load, which will result in considerable rise of rotation speed.
6 Synchronous grid-connection control
When the rotation speed of steam turbine is about 3000r/min, if DEH receives the
synchronous request signals from an automatic synchronization installation, automatic
synchronization functions can be input through OIS; at this point DEH can receive the
rotation speed increase or decrease instructions of the automatic synchronization
installation, control the rotation speed, make it in agreement with the grid frequency.
The speed rate is 60r/min/min. At this point, the generator voltage (including amplitude
and phase) is controlled by the exciter control system. When the grid connection
condition is available, the generator will be grid-connected.
In case of one of the following instances, the synchronization mode will be cancelled.
Rotation speed: less than 2985 r/min or greater than 3015 r/min;
Manual status;
Rotation speed failure;
Have been grid-connected;
Tripping of turbine.
7 Control after grid connection (non CCS mode)
When a steam turbine generator unit is just grid-connected, DEH will immediately
increase the setting value, which will make the generator carry an initial load and thus
avoid the occurrence of reverse power. At the beginning of grid connection, DEH will
use the throttle pressure to correct the increased setting value, instead of inputting load
feedback.
Setting value = original value +3+f (p0).
At the beginning of grid connection, the target is also equal to the setting value.
1 Load up
After the steam turbine generator unit is grid-connected, in order to realize the primary
frequency adjustment, rotation speed feedback is available for the control system.
During testing or with a base load, load control can also be input. During inputting load
control, the target and setting value find expression in the form of MW. After the power
control is cancelled, the target and setting value find expression in the percentage of the
total flow under the rated pressure.
After the target is set, the setting value will approach the target value with a set change
rate, and along with it the generator power or throttle pressure will change gradually.
During the load up, often the steam turbine needs to be heated to reduce heat stress.
2 Target
Except the target set up by operators through OIS, under the following conditions,
DEH automatically set up the target:
When the power control is just input, the target is the current load (MW);
When the generator is just grid-connected, the target is the setting value for initial
load (%);
In a manual state, the target is the reference quantity (%) (valve total flow
instruction);
When the control is just cancelled, the target is the reference quantity (%);
When the turbine has tripped, the target is zero;
Under the mode of control of CCS, the target is CCS setting (%);
When the target is too large, it shall be replaced by the upper limit value.
3 Load rate
Set by operator, within (0~100) MW/min;
During Single / Sequential
Valve switching, 5.0MW/min.
4 Warm-up of turbine
During the load up of steam turbine, in view of such factors as heat stress and
expansion difference, in general warm-up is required. If the load up is required to pause,
the following operations can be conducted:
When not in a CCS mode, the operator sends out a "HOLD" instruction;
When in a CCS mode, the operator sends out a "HOLD" instruction after quitting it from
the CCS mode.
5 Power control
The power controller is a PI controller, used to compare the setting value and the actual
power and output CV and ICV instructions after calculation.
Power control input conditions:
With a grid-connected unit, the load varying between 6.0MW~310MW;
Normal power signal;
No CCS control input
No TPC action;
No quick release action;
No primary frequency adjustment action;
No high load restriction action;
No low load restriction;
The system in an automatic mode
When all the above conditions are met, click the “IN” button in the "AUTOMATIC
CONTROL" menu of the OIS to input power control.
Power control canceling conditions:
Operators clicking the "OUT" button in the "AUTOMATIC CONTROL" menu of OIS;
Load less than 6.0MW or greater than 310MW
Abnormal power signal; Tripping of steam turbine; Change to a manual mode; High load restriction action; Low load restriction; Quick release action; When reaching the sliding pressure point; TPC action; Primary frequency adjustment action; Tripping of oil switch; CCS control input. When there is power control input, the set point is denoted as MW. When PI isochronous control is adopted, the steady-state load is equal to the set value. 6 Primary frequency adjustment When a steam turbine generator unit is grid-connected, in order to ensure that the power supply quality meets the requirement of the grid frequency, in general primary frequency adjustment functions is required to input. When the rotation speed of the unit is within the dead zone, the frequency adjustment setting is zero, and the primary frequency adjustment fails to actuate. When the rotation speed is beyond the dead zone, the primary frequency adjustment acts and the frequency adjustment setting changes with the speed variation as per the diversity factor. The diversity factor of primary frequency adjustment is adjustable within a range of 3%~6%. Its factory set value is 4.5%. The adjustment dead zone is adjustable within a range of 0~30r/min. The factory set value for frequency dead zone is ± 10/min. When controlled by CCS, the frequency adjustment dead zone changes itself into ± 30r/min. The diversity factor and frequency adjustment dead zone of primary frequency adjustment can be displayed in the "AUTOMATIC RESTRICTION" menu of OIS. Primary frequency adjustment function input condition: The system being in a automatic state;
After the load greater than 10% of the rated load for the first time.
8 CCS control
DEH can cooperate with CCS to complete the coordination control of unit and boiler.
Under the CCS control mode, DEH is one of actuator of CCS. DEH automatically
cancels the power control and, according to the instructions given by CCS, control the
opening of all valves. DEH can give a proper judgment or restriction to CCS instructions
in terms of higher limit, lower limit, and rate of change. The signal transmission between
DEH and CCS is tabled as below:
No. Signal name Signal
direction
Signal category
1 CCS control request CCS→DEH Digital signal
2 CCS instruction CCS→DEH 4∽20mA Analog
signal
3 CCS control input DEH→CCS Digital signal
4 Valve position of steam
turbine
DEH→CCS 4∽20mA Analog
signal
Here, it is required that during CCS input the "CCS CONTROL REQUEST" signal shall
be normally available; otherwise, DEH decides that CCS proper has canceled it and as
a result DEH changes from a CCS control mode to a valve position control mode.
When DEH receives the "CCS CONTROL REQUEST" signals, we can click the "CCS
INPUT" button in the "AUTOMATIC CONTROL" menu of OIS, and the menu will display
"CCS INPUT". Under the CCS control mode, the DEH target is equal to the CCS setting
value. At this point, the target follows the increase and decrease of CCS setting signals
and the actual load also changes accordingly. Under the following conditions, cancel
CCS:
Operators clicking the "OUT" button in the "AUTOMATIC CONTROL" menu of OIS;
TPC action;;
Manual mode;
Tripping of oil switch;;
Without "CCS CONTROL REQUEST" signals;
Runback action.
All signals between DEH and CCS connected with hard wires.
9 Valve management
The philosophy for valve management is to require that within its whole range of operation a
steam turbine can select its mode of regulation as desired and realize a undisturbed switch
between throttle control (corresponding to single valve operating mode) and nozzle control
(corresponding to sequence valve operating mode). When a throttle steam distribution mode is
adopted, the rapid start-stop and varying duty of steam turbine will not go so far as to produce
oversized heat stress, so that the unit life loss can be reduced; however, within a normal load
range when a nozzle governing variable-pressure operation mode is adopted, the unit has the
best economical efficiency and operational flexibility.
During the start, speed raising, grid connection, and with low load phases, in general
the throttle control mode, i.e., the "single valve" control mode, is adopted. With this
mode, the steam flow enters into the HP control stage in a full circle, which makes the
cylinder and rotor be heated and expanded uniformly, and as a result the heat stress
resulting from start and the mechanical stress resulting from rotor blade regulation can
be effectively lowered.
Under a normal power, a nozzle control mode, i.e., the "sequence valve" control
mode, is adopted to acquire relatively high thermal efficiency.
DEH has valve management functions, that is, it can realize the undisturbed switch
between throttle control and nozzle control. Operators are able to select the steam
distribution mode of a steam turbine's control valves, and the concrete steam
distribution mode depends on the start operation mode of the steam turbine.
When the unit's load rises to a certain degree, input power control, and click the
"SEQUENCE VALVE" button in the "AUTOMATIC CONTROL" menu of OIS to display
"SINGLE / SEQUENTIAL VALVE SWITCHING". About 10 minutes later, the switching is
over. After the switching, the load shall be stable. Then switch back to the single valve
control mode. The load shall be stable. If input pressure control, and repeat the above
process, then after the switching process is over the load shall be stable. If the start is
conducted at a hot state or extremely hot state, the sequential valve mode will be
adopted forcefully. After the unit throw off the load, it will automatically set the operation
mode as sequential valve mode. If at this point you want to switch back to the single
valve mode, grid connection with an initial load is required before the switching between
single / sequential valves.
10 Overspeeds
Overspeed control and overspeed protection are available for DEH.
1 Overspeed control
1.1 Load rejection
For the time constant of the rotor of a high-capacity steam turbine is commonly very
small, the time constant of the cylinder volume is often very large. When load rejection
occurs, the rotation speed rises very quickly. If the control only relies on the system
itself, the maximum speed may exceed the action speed of the protection system and
as a result bring about steam turbine intercepting. For this reason a set of load rejection
overspeed limit logic must be set up.
If the oil switch is disconnected and load rejection occurs, both DEH hardware and
software circuits act simultaneously. The overspeed limit integrated package and the
fast solenoid valves of all oil servo motors will act quickly to close CVs and ICVs;
meanwhile the target rotation speed and setting rotation speed are changed into
3000r/min. 2 seconds later, all solenoid valves are reset, and the control valves are
restored to be under the control of servo valves, and the control turns back to normal
speed circuit control. Finally, the rotation speed of steam turbine is stabilized at
3000r/min, so that a rapid grid connection is available after the emergency disappears.
1.2 103% Overspeed
Overspeed has a large influence on the life of a steam turbine. Except in the overspeed
test, at no time the rotation speed is allowed to exceed 103% (for the max. grid
frequency is 50.5Hz, that is, 101%)
Under the condition of no overspeed test, once the rotation speed exceeds 103%, the
overspeed limit integrated package and the fast solenoid valves of all oil servo motors
will act quickly to close CVs and ICVs. When the rotation speed is lower than 103%, all
solenoid valves are reset, the control valves are restored to be under the control of
servo valves, and the control turns back to the normal speed circuit control.
1.3 Acceleration limit
In DEH there also sets up a acceleration limit circuit. When the rotation speeds of two
consecutive cycles show a difference of 10r/min, the circuit will close both CV and ICV
quickly; when the rotation speed difference is <10r/min, all solenoid valves are reset.
2 Overspeed protection
If a steam turbine's rotation speed is too high, the steam turbine will be damaged due to
the action of centrifugal stress. Although overspeed limit functions are available for DEH
to avoid steam turbine overspeed, in the event of a failure of speed restriction,
exceeding the preset speed will result in tripping, and all the stop valves and control
valves will be closed as quickly as possible
For the purpose of safe operation, there set up several layers of overspeed protection in the
system:
DEH electric overspeed protection 110%;
Mechanical overspeed protection
In addition, the following tripping functions are also available for DEH:
Mannual tripping by operator;
Sending out tripping signals by emergency stop cabinet ETS.
3 Overspeed test
Operators conduct test operation on the "OVERSPEED TEST" menu of OIS.
3.1 Mechanical overspeed test
First shift the overspeed test switch on the "OVERSPEED TEST" menu of OIS from
"NORMAL" to "MECHANICAL", then click the " MECHANICAL OVERSPEED TEST" button,
and a "TEST PROCEEDING" status will be displayed. Set the target rotation speed as
3360r/min and the speed rate as 100r/min/min for speed raising. When the speed rises so far
as to result in tripping, intercept the unit and display both the intercept speed and top speed.
After the test is over, reset the top speed, shift the overspeed test switch from the
"MECHANICAL" to "NORMAL" to quit the unit from the mechanical overspeed test.
3.2 Electric overspeed test
Shift the overspeed test switch on the "OVERSPEED TEST" menu of OIS from "NORMAL" to
"ELECTRIC", then click the "ELECTRIC OVERSPEED TEST" button, and a "TEST
PROCEEDING" status will be displayed. Set the target rotation speed as 3310r/min and the
speed rate as 100r/min/min for speed raising. When the rotation speed rises to exceed 110%,
the overspeed protection system acts, intercepting the unit and displaying the intercept
rotation speed and top speed. After the test is over, reset the top speed, shift the overspeed
test switch from the "ELECTRIC" to "NORMAL" to quit the unit from the Electric overspeed
test.
11 Valve activity test
When a unit is in normal operation, activity tests to check MSVs, RSVs, CVs, and ICVs can
be conducted regularly to avoid jamming of these admission valves. Activity tests can be
conducted for CVs and SVs respectively.
Permissive conditions for valve activity test:
All SVs are full open;
Non CCS mode;
Automatic mode.
On the OIS menu, enter into the "VALVE TESTING" menu, shift the test switch from
"TESTING PERMIT" to "TESTING", click the button of the valve for activity test and begin the
valve activity test. At this point the valve begins to be closed with a certain speed rate. When
the closing reaches 85% opening extent, the valve reopens the position prior to testing. The
test is over.
After the activity test is over, shift the test switch from "TESTING PERMIT" to "NORMAL".
12 Spray oil testing
When the rotation speed is in the order of 3000r/min, DEH can complete the spray oil
extruding test for the centrifugal stop ring of emergency overspeed governor through resetting
testing valve combinations, so as to prevent the centrifugal stop ring from jamming due to
long-term motionlessness.
When an injection test is conducted, first the isolated solenoid valve in an intercepting
isolation valve block is powered up, which isolates the emergency tripping device from the
system. Then the spray oil solenoid valve of the emergency overspeed governor is powered
up, which makes the emergency tripping valve trip. Because the stop valve has been isolated
from the system, the unit will not trip. After the emergency tripping device trips successfully,
DEH engage it through resetting the solenoid valve. After the latching-on is available, the
isolation solenoid valve loses electricity, so the isolation is canceled, the system is restored to
normal, and the spray oil test is over.
Permissive conditions for spray oil testing: the rotation speed shall be within
2985r/min~3015r/min and all the indicators of the unit are within the testing allowed range.
First in the "SPRAY OIL TESTING" menu of OIS change the test switch from "TESTING
PERMIT" to "TESTING", and then click the "SPRAY OIL TESTING" button to input spray oil
testing. The screen displays that the spray oil testing is in progress: isolation solenoid valve
4YV is electrified; after ZS4 enters into the testing position, it sends out messages; after DEH
receives the signals, spray oil solenoid valve 2YV is electrified, injects oil, and flies the
centrifugal stop ring; when DEH receives the intercepting signals of ZS2, it judges that the
spray oil testing is successful; then spray oil solenoid valve 2YV losses its electricity, the
steam turbine generator unit is reset, isolation solenoid valve 4YV losses its electricity, ZS5
returns to normal, and the spray oil testing is over.
13 HP tripping solenoid valve testing
The HP tripping solenoid valves consist of four solenoid valves, of which two valves are connected in series
and the other two valves are connected in parallel. The design is based on a principle of stop for electricity
failure, that is, the sole electricity failure of any solenoid valve will not result in the intercept of the unit;
therefore, HP tripping solenoid valves can be tested on-line one by one. The test results can be reflected by
the action of two pressure switches PS4 or PS5. When a test for 6YV or 8YV is conducted, the middle oil
pressure will be lowered, at this point the pressure switch PS4 will send out a message to show that the
solenoid valve under testing has valid action; when a test for 7YV or 9YV is conducted, the middle oil
pressure will increase, at this point pressure switch PS5 will send out a message to show that the solenoid
valve under testing has valid action.
After the latching-on for the unit is conducted, a HP tripping solenoid valve test can be
conducted.
Enter into the "TRIPPING SOLENOID VALVE TESTING" menu in the OIS, and change the
test switch from "TESTING PERMIT" to "TESTING". Press the "HP INTERCEPT TESTING"
button, and then select solenoid valves 6YV, 7YV, 8YV, or 9YV for testing. The positions of the
corresponding solenoid valve in the menu will turn red. After the test is over, the red color will
disappear. If the testing succeeds, a "SUCCESS" message will display; if the testing fails, a
"FAILURE" message will display.
14 Valve leak test
When the steam turbine runs idle at the rated speed of rotation and the steam pressure of
boiler meet some specific conditions, DEH can control the unit for SV leak testing and CV leak
testing.
When a SV leak test is conducted, all RSVs and MSVs shall be fully closed and the steam
turbine's rotation speed shall be lowered quickly. DEH works out an acceptable rotation speed
according to the current main stream pressure and confirms that the rotation speed of the unit
can be lowered below the above acceptable rotation speed, by means of which it decides
whether the SV is tightly closed.
When a CV leak test is conducted, all CVs and ICVs shall be fully closed and the steam
turbine's rotation speed shall be lowered quickly. DEH works out an acceptable rotation speed
according to the current main stream pressure and confirms that the rotation speed of the unit
can be lowered below the above acceptable rotation speed, by means of which it decides
whether the CV is tightly closed.
Permissive conditions for valve leak testing: automatic mode; latching-on available for the
steam turbine; rotation speed within 2985r/min~ 3015r/min; tripping of oil switch; in the "LEAK
TEST" menu in the OIS the test switch is in the "TESTING" position instead of "TESTING
PERMIT" position.
1 SV leak test
The turbine speed is stabilized at 3000r/min. In the "LEAK TEST" menu in the OIS, click the
"SV TESTING" button, and the button displays "TESTING PROCEEDING" and the color is
red. The control mode changes from "AUTOMATIC" to "MANUAL", all SVs are closed, and the
rpm drops. Display the steam turbine race time record.
2 CV leak test
The turbine speed is stabilized at 3000r/min.. In the "LEAK TEST" menu in the OIS, click the
"CV TESTING" button, and the button displays "TESTING PROCEEDING" and the color is
red. The control mode changes from "AUTOMATIC" to "MANUAL", all CVs are closed, and
the rpm drops. Display the steam turbine race time record.
3 When the rotation speed reaches the acceptable value, click the "OFF TEST" button to
terminate the leak test. After the test is over, the unit trips for shutdown and restart is required.
15 Automatic limit functions
DEH is featured by automatic limit function, which is used to keep the power, throttle pressure
or valve position within certain limits.
DEH can set up the maximum and minimum load limits to limit the generator's developed
power. The value is given by the operator in the OIS.
When the difference between the measured power and given power exceeds the predeterined
value, DEH automatically cancels the power control loop and changes into a valve position
control mode to ensure the safety of the unit.
DEH also has low throttle pressure protection control function (TPC function). When the
throttle pressure drops to the set value (set by operator throught OIS), the throttle pressure
limit loop is brought into operation, outputting instructions to reduce steam valve opening so
as to limit load and help the boiler to restore its throttle pressure as quickly as possible. At this
point, the power control circuit is automatically cancelled.
DEH can also set up a maximum valve position limit to restrict the steam turbine's valve
position within a certain range. The value is set by the operator in the OIS.
1 High load limit
Operators can set up the high load limit in the "AUTOMATIC LIMIT" menu in the OIS (20~
330MW) to ensure that the DEH setting value is always smaller than the limit. After the
system is powered on, the high load limit is automatically set up as 330MW. If at this point the
load is higher than the limit, it will be automatically reduced to the limit.
2 Low load limit
Operators can set up the low load limit in the "AUTOMATIC LIMIT" menu in the OIS (0~
20MW) to ensure that the DEH load is always greater than the limit. After the system is
powered on, the low load limit is automatically set up as 3MW.
3 Valve position limit
Operators can set up the valve position limit in the "AUTOMATIC LIMIT" menu in the OIS
within (0~120)%, and after the system is powered on, the limit will be automatically set up as
120%.
Additional tripping through DEH:
Some additional tripping have been incorporated through DEH system which DEH can
generate alone by sensing data directly to it. The tripping are as follows:
1. Any turbine bearing metal temperature trip which is > 115°C
2. Any thrust bearing temperature high trip > 110°C
3. Turbine Over speed trip > 3300rpm
4. Main Steam temperature low trip < 430°C
5. EH safe oil pressure low
6. Manual trip push button
7. EHG failure trip (it includes any malfunction in turbine main steam valves operation or any
power supply failure to DEH system like 48V DC) 8. Any ATR trip Which includes:
a) any brg metal temp trip
b) Any thrust brg temp trip
c) Any brg drain oil temp trip > 75°C
d) Rotor position trip +1.2 / -1.65
HART System HART stands for Highway Addressable Remote Transducer. It is an open protocol
developed in the late 1980's to facilitate communication with Smart field devices. HART
communication occurs between two HART-enabled devices, typically a field device and
a control or monitoring system. Communication occurs using standard instrumentation
grade wire and using standard wiring and termination practices.
HART provides two simultaneous communication channels: the 4-20mA analog signal
and a digital signal. The 4-20mA signal communicates the primary measured value (in
the case of a field instrument) using the 4-20mA current loop - the fastest and most
reliable industry standard.
MACHINE MONITORING SYSTEM(MMS)
Beijing ENVADA’s EN9000 device is an online vibration monitoring and protection
system for rotating machinery. It takes vibration and keyphasor data from PA fan, FD
fan, ID fan, CEP, BFP, CWP, ACWP and all mills and generates annunciation for all
vibration risk limit. MMS produces tripping signals equipment safety. The system
continuously measures and monitors the main mechanical safety parameters of the
device.
2. EN9000 Characteristics
The EN9000 uses the latest microelectronic technologies to ensure a highly
integrated, strong anti-interference capability with high reliability and ease of
installation.
The doubly redundant power supply guarantees the normal working of the system
at any time so long as commercial electric power is available.
Each module supports hot plug & pull operation. Maintenance is achieved by
module convenient replacement.
Each module is provided with a built-in microprocessor. The modules are
independent and cause no interference to other modules.
The system integrates the vibration monitoring protection and fault diagnosis
functions. All settings can be defined remotely and transferred by software download but
each channel can be set and adjusted directly on the machine. The software provides
rich functionality, with user definable display area, sensor sensitivity, alarm values,
alarm delays, alarm logic and zero point definition. The delayed access and password
protection are built in to prevent faulty operation and protect the fixed values from
unauthorized operation.
The values and development trends of each channel can be observed on the host
machine screen. Waveform and frequency analysis is provided to automatically
diagnose common rotating machinery problems, including unbalance, rotor/stator
rubbing, uneven expansion, abnormal axial position, oil whirl/whip, etc.
The common system computer vibration analysis and fault diagnosis software
provides flexible data management, real-time status monitoring, complete signal
analysis, detailed fault diagnosis and dynamic balancing.
Classification of EN9000 system modules
EN9000 system is of modular design that meets a wide range of needs. The
system is expandable. The EN9000 modules are as follows:
EN9000/RX unit
EN9000/1X power supply module
EN9000/40 vibration and displacement module
EN9000/30 rotational speed module
EN9000/20 keyphase module
EN9000/50 8-channel process module
EN9000/60 20-channel process module
Power Supply Module: Each EN9000 power supply module is a
half-height module and must be installed into the special
purpose slot on the left side of the chassis. Two identical power
supply modules are installed inside EN9000 chassis to provide
a two-way redundant supply.
The power supply module is installed at the lower left
corner of EN9000 chassis, and it converts
the AC voltage provided from the terminal
board on the back of the chassis to the
DC voltage ( +5V DC, +15V DC, - 24V
DC) required for the normal working of
other EN9000 modules. The external AC
supply voltage should be specified at the
time of order may be 115V AC±15% or
230V AC±15%.
Vibration sensing module: The 4-channel vibration and displacement module is
numbered as EN9000/40 (it corresponds to i/o module: EN9000/04) and is able to
monitor the radial vibration, radial clearances and axial displacement of rotating
machinery in real time. It can be used on all sizes of rotating machinery and can be
installed into EN9000 chassis to be used together with the power module and Host
Machine Module.
The 4-channel vibration and displacement module monitors the input signals from 4
sensors. It performs the following functions:
- It buffers the voltage output from the sensor signals
- It records the 4- 20mA transducer current output from the sensor signals
- It displays the status of the sensor and its channel through the LED on the
front panel
- It transmits the monitored values and set values of the 4 channels to the
central LCD.
What is critical is that the relay will trip the protection switch to shut down the
rotating machinery when the warning criteria are exceeded.
Important signal out from MMS panel:
Alarm signals of different Equipment:
1. All ID fan, FD fan, PA fan radial bearing, thrust bearing, motor drive bearing, non-
drive bearing alarms are set at 7.1mm/sec.
2. All ID fan, FD fan, PA fan radial bearing, thrust bearing, motor drive bearing, non-
drive bearing tripping are set at 10mm/sec.
3. All BFP, CEP motor drive ,motor non-drive, pump drive and non-drive bearings
alarm has been set at 80 microns.
4. All BFP, CEP motor drive ,motor non-drive, pump drive and non-drive bearings
tripping has been set at 150 microns.
5.All mills Reductor vibration alarms set at 5.6 mm/s.
TURBINE SUPERVISORY INSTRUMENTATION(TSI)
TURBINE SUPERVISORY INSTRUMENTATION is abbreviated to TSI. As the turbine capacity and
the turbine capacity keep creasing, and the thermal system becomes more and more complicated,
smaller stage clearance and the gland clearance are chosen in order to higher the thermal economy
of unit. Since the speed of turbine is quite fast, the rotating parts and the static parts are possibly
scrap without right operation or control, which may result in serious accidents like blade cracking,
shaft bending, thrust pads burning, etc.. In normal operation, the mechanical parameters of the axial
displacement, the thermal expansion, the differential expansion, the rotating speed, the libration, the
main bearing eccentricity and etc., should be monitored and be protected. The main valve will close
automatically to stop the unit when the monitored parameters over the limit.
3500 series: SgTPP is using 3500 series Bently Nevada vibration monitoring
system. This comes with rack configuration system. One dedicated rack is there for
analyzing all turbine shaft vibration.
Designed using the latest in proven microprocessor technology, the 3500 is a full-
feature monitoring system. In addition to
meeting the above stated criteria, the 3500 adds benefit in the following areas:
• Enhanced Operator Information
• Improved integration to plant control computer
• Reduced installation and maintenance cost
• Improved reliability
• Intrinsic Safety option
Enhanced Operator Information: The 3500 was designed to both enhance
the operator's information and present it in a way that is easy for the operator
to interpret. These features include:
• Improved Data Set
- Overall Amplitude
- Probe Gap Voltage
- 1X Amplitude and Phase
- 2X Amplitude and Phase
- Not 1X Amplitude
• Windows® Based Operator Display Software(System1 software)
Improved integration to plant control computer:
• Communication Gateways supporting multiple protocols
Reduced installation and maintenance cost:
• Reduced cabling costs
• Improved space utilization
• Easier configuration
• Reduced spare parts
Improved reliability:
• Redundant power supplies available
• Triple Modular Redundant (TMR) monitors and relay cards available
• Redundant Gateway and Display Modules permitted
The following modules may be installed in the 3500 rack:
Power Supply: The Power Supply is a half-height module available in AC and DC
versions. One or two power supplies can be installed in the rack. Each power supply
has the capacity to power a fully loaded rack. When two power supplies are installed in
a rack, the supply in the lower slot acts as the primary supply and the supply in the
upper slot acts as the backup supply. If the primary supply fails, the backup supply will
provide power to the rack without interrupting rack operation. Any combination of power
supply types is allowed. Overspeed Detection and TMR Monitors require dual power
supplies.
Rack Interface Module: The Rack Interface Module is a full-height module that
communicates with the host (computer), a Bently Nevada Communication Processor,
and with the other modules in the rack. The Rack Interface Module also maintains the
System Event List and the Alarm Event List. This module can be daisy chained to the
Rack Interface Module in other racks and to the Data Acquisition / DDE Server
Software. The 3500 Monitoring System Computer Hardware and Software Manual
shows how to daisy chain the Rack Interface Modules together. Rack Interface Modules
are available in Standard, Triple Modular Redundant and Transient
Data Interface versions.
Communication Gateway Module: The Communication Gateway Modules are full-
height modules that allow external devices (such as a DCS or a PLC) to retrieve
information from the rack and to set up portions of the rack configuration. More than one
Communication Gateway Module can be installed in the same rack. Communication
Gateway Modules are available
for a variety of network protocols.
Relay Module: Relay Modules offer relays that can be configured to close or open
based on channel statuses from other monitors in the 3500 rack. Relay modules are
available in 4 channel, 16 channel, and 4 channel Triple Modular Redundant The TMR
Relay Module is a half-height 4-channel module that operates in a Triple Module
Redundant (TMR) system. Two half-height TMR Relay Modules must operate in the
same slot. If the upper or lower Relay Module is removed or declared as not OK, then
the other Relay Module will control the Relay I/O Module.
Keyphasor Module: The Keyphasor Module is a half-height module that provides
power for the Keyphasor transducers, conditions the Keyphasor signals, and sends the
signals to the other modules in the rack. The Keyphasor Module also calculates the rpm
values sent to the host (computer) and external devices (DCS or PLC) and provides
buffered Keyphasor outputs. Each Keyphasor Module supports two channels and two
Keyphasor Modules may be placed in a 3500 rack (four channels maximum). If two
Keyphasor Modules are used, they must be placed in the same full-height slot and will
share a common I/O module.
3500/22M Transient Data Interface
The 3500 Transient Data Interface (TDI) is the interface between the 3500 monitoring
system and Bently Nevada’s System 1® machinery management software. The TDI
combines the capability of a 3500/20 Rack Interface Module with the data collection
capability of a communication processor such as TDXnet.
TDI operates in the RIM slot of a 3500 rack in conjunction with the M series monitors
(3500/40M, 3500/42M, etc.) to continuously collect steady state and transient waveform
data and pass this data through an Ethernet link to the host software. Static data
capture is standard with the TDI, however using an optional Channel Enabling Disk will
allow dynamic or transient data to be captured as well. TDI has made improvements in
several areas over previous communication processors in addition to incorporating the
Communication Processor function within the 3500 rack.
TDI provides certain functions common to the entire rack, however the TDI is not part of
the critical monitoring path and has no effect on the proper, normal operation of the
overall monitor system. One TDI or RIM is required per rack. The TDI occupies only a
single slot in the rack and is always located in Slot 1 (next to the power supplies).
For Triple Modular Redundant (TMR) applications, the 3500 System requires a TMR
version of the TDI. In addition to all the standard TDI functions, the TMR TDI also
performs “monitor channel comparison”. The 3500 TMR configuration executes
monitoring voting using the setup specified in the monitor options. Using this method,
the TMR TDI continually compares the outputs from three (3) redundant monitors. If the
TMR detects that the information from one of those monitors is no longer equivalent
(within a configured percent) to the remaining two, it will flag the monitor as being in
error and place an event in the System Event List.
Rack Configuration Software
Rack configuration soft ware is a Windows based easy to install to the racks of 3500
system host software. All the racks like power module, RIM, Transient Data Interface ,
keyphasor module, vibration module etc can be configured remotely through RS232 or
10/100 T base Ethernet port.
For all the shaft vibration, bearing vibration, differential expansion, keyphasor,
eccentricity range is defined through this Software.
Alarm values and danger limit is defined to trigger relay attached to individual back pne
module.
TMR Relay module can be configured to incorporate more than one parameter to have
different alarm and trip events.
Type of Racks used and signals out
1. Speed module: It is a two channel speed module which senses speed of turbine and
relay out the zero speed of turbine to auto start of Turning gear.
2. Over speed module: There are three nos of 3500/53 overspeed module. They are
single channeled. Each module is configured to have a high limit relay out of 110% of
normal turbine speed i.e. 3300rpm. Three nos of output goes to ETS to trip turbine if
speed exceeds the high value.
3. Rotor position monitoring module: This is a 4 channel proximity monitoring module
which measures the rotor position. The danger limit is set as (≥ 1.2mm or ≤ -1.65mm).
The trip signal is generated through relay module.
4. Differential Expansion Module: This is a 4 channel position monitoring module which
measures HIP differential expansion & LP differential expansion & two nos of casing
expansion. Turbine trip due to differential expansion high is clubbed together and
programmed in relay module.
5. Vibration monitoring module : There are 6 nos of 3500/42 proximity module for
measuring X and Y direction vibration of each turbine shaft and bearing. The 4-20 mA
signal out is taken to DCS and turbine trip due to high shaft vibration logic is built using
Composer.
6. Eccentricity measurement: This is also a proximity module whose corresponding
sensor is mounted on front pedestal of turbine.
HPLP Bypass
HP bypass controller
The Sulzer HP bypass controller is an integrated system with the functions signal
conditioning, control and valve positioning (Figure 1). The type of operator interface can
be tailored to the needs of the individual plant. The below described functions for start
up as well as for shut down are fully automated.
With a few standardized interface signals the Sulzer bypass controller can be tied easily
into an overall plant automation. The duty of the HP bypass controller can be
summarized for the different operating conditions as follows:
Boiler start up
The controller has to control and increase the boiler steam pressure according to the
steam production of the boiler. The bypass has to divert the steam flow to the reheater,
thus ensuring a proper steam flow through superheater and reheater. The bypass
controller has to control the temperature of the steam to the reheater whenever steam is
flowing through the bypass.
Turbine start up
The HP bypass controller has to control the steam pressure until the boiler master
controller can take over the pressure control.
Load operation
The bypass is closed but the controller is ready to prevent excessive live steam
pressure or excessive pressure gradients.
Turbine load rejection/trip
The controller opens the bypass valves, if necessary with the help of the quick opening
devices, in order to prevent excessive live steam pressure and controls the pressure
until the turbine picks up load again.
Safety Function
Regulations of various countries allow the use of the HP Bypass valves as safety valves
for the HP part of the boiler without any additional conventional safety valves on the HP
side. for this the HP Bypass has to be equipped with a hardwarewise fully independent
safety system. Functionally this system is fully integrated into the bypass controller to
ensure smooth transients between safety and control function.
Figure 2 shows the main elements of a two line HP bypass with the main control
functions:
Pressure controller temperature controller injection water isolation valve control safety
function
1.2.1 Pressure control
Figure 3 shows in more detail the structure of the pressure controller and the pressure
setpoint generator. The different functions and operating modes of the pressure
controller are represented again in the start up diagram of Figure 4.
At the begin of a cold start the minimum opening (Ymin) is active. It ensures
immediately after ignition an open path and therefore a steam flow through the
superheater and reheater.
When there is enough steam production to reach a predetermined minimum pressure
(pmin) the controller begins to control the live steam pressure by opening the bypass
valves.
When the valve positions reach a predetermined value Ym (determined by the desired
steam flow during boiler start up) the setpoint generator begins to increase the pressure
setpoint in accordance with the steam production of the boiler, but with a limited
maximum gradient.
Once the target pressure for starting the turbine (psynch) is reached, the setpoint
generator switches to (fixed) pressure control. As the turbine starts to accept steam the
bypass will start to close until the turbine consumes all the steam produced by the boiler
and the bypass is fully closed.
As soon as the bypass is closed the pressure setpoint tracks the actual pressure plus a
threshold dp which keeps the bypass closed (follow mode). The maximum gradient of
the pressure setpoint is still limited. If the life steam pressure exceeds this gradient, the
bypass will start to open and the controller returns to pressure control mode. The
pressure is controlled by the bypass until normal operation has been restored and the
bypass is closed again.
1.2.2 Temperature control
Regarding temperature control it should be mentioned here only that accurate control of
the steam temperature under all operating conditions requires a controller well matched
to the wide range of operating conditions of a HP bypass (low load, quick opening at full
load, etc.). Accurate control of the temperature under all this operating conditions is an
important life conserving factor for the heavily stressed walls of the valves and piping.
1.3 LP bypass controller
The Sulzer LP bypass controller is an integrated system with the functions signal
conditioning, control and valve positioning (Figure 5). The type of operator interface can
be tailored to the needs of the individual plant. With a few standardized interface signals
the Sulzer bypass controller can be tied easily into an overall plant automation.
Although independent in operation from the HP bypass controller the LP bypass
controller must operate in conjunction with the HP Bypass system and allow the excess
steam flow which is not admitted to the turbine to pass to the condenser.
1.3.1 Pressure Control
The duty of the LP bypass pressure controller for the different operating modes can be
summarized as follows:
Boiler start up
The controller has to control the steam pressure in the reheater system. The injection
controller has, when ever the LP bypass is open, to control the desuperheating of the
steam so that it can be accepted by the condenser.
Load operation
The bypass is closed but the controller monitors the reheat steam pressure in order to
open and control the pressure whenever an unacceptable pressure increase is
monitored.
Condenser protection
Whenever the condenser is not able to accept the steam or the injection water system is
unavailable, the controller has to close the bypass through a separate safe channel in
order to protect the condenser.
During load operation the first stage pressure of the turbine serves as load signal for the
setpoint generator which generates a load dependent (sliding) pressure setpoint.
With large bypass valves, their flow capacity at high reheater pressure can exceed the
absorption capacity of the condenser. For such cases the steam flow to the condenser
must be limited by the bypass controller.
If power operated reheater safety valves are provided (e.g. Sulzer MSV valves),
coordinated operation of the reheater safety valves with the LP bypass can further
improve plant operation for the case of turbine trip or load rejection at high load. The
Sulzer LP bypass controller can provide the necessary signals for operation of the
reheater safety valves.
1.3.2 Injection water control
Because the steam conditions after the LP bypass de superheater are usually near or at
saturation condition, the temperature after the de superheater cannot be used as control
signal. The necessary injection water flow and valve position of the injection valve must
therefore be calculated from the steam flow and steam conditions. The steam flow is in
turn a function of the steam conditions and the valve position of the bypass valve. The
LP bypass controller provides the necessary computing functions to perform this
calculations and uses the calculated injection water demand as setpoint for the water
flow controller.
Software description (Version 2.5)
The parametrization software „PASO“ is used for adjustments and diagnosis of the
positioner PVRxx. PASO is a comfortable user environment for easy adjustments, which
can be done by keyboard or mouse. The communication with the positioner PVRxx is
done by a serial interface RS232.
The PASO can be used only in conjunction with the positioner PVRxx. The software
description of the positioner PVRxx must be studied precisely in beforehand, and its
instructions must be followed.
2.4 Connection to the P-card
The connection between the PC, the installed PASO and the positioner PVRxx is done
with the serial interface RS 232. For this, you must connect the enclosed cable into the
desired port on your PC and into the RS 232 connector on the positioner PVRxx. If
necessary the comunication port (COM1, 2) can be changed in the dialogue box
“Configuration”.
Local control and monitoring for hydraulic supply unit
SHV200/350/450AS
3.1 Application
The hydraulic supply units HV200AS, HV350AS and HV450AS provides pressurized
oil for the operation of hydraulic actuators. The hydraulic supply units are each
equipped with two main pumps, a pump for the filter circuit and a cooling fan. The
controller is installed in a local control cabinet on the hydraulic supply unit.
The controller monitors the hydraulic supply unit by pressure transmitter,
temperature transmitter and level transmitter. The controller activate the control
devices as accumulator charging valves, main-pump motors, filter-pump motor, and
cooling-fan motor and the heater (optional). The operation and display elements on
the control cabinet are necessary for the commissioning and are indicating detail
faulty operation on hydraulic supply unit.
The control cabinet is fully wired and tested at factory. The customer has only to
connect electric supply and I/O signals.
Optionally one regeneration station can be connected to the control cabinet. One
powered and fused output to the regeneration station (optional) is available at the
control cabinet.
3.2 Signals
3.2.1 Operating and display elements
Operational and fault conditions are displayed on the display elements in the cabinet
door. Fault messages are always stored. When the fault is cleared the hydraulic
supply unit will start operation automatically again. The fault message will be kept
stored until the operator has checked locally the hydraulic supply unit and reset the
fault message with the pushbutton (Reset).
Fig. 1 Control cabinet operating and display elements
Tag Operation and display Operation /
alarm
Inscription
on Display
Color
S411 Local operation key switch Man/Auto
S412 Lamp check pushbutton Lampcheck
S413 Alarm reset pushbutton Reset
S414/H471 Pump 1 on/off pushbutton Pump 1 run Pump 1 green
S415/H472 Pump 2 on/off pushbutton Pump 2 run Pump 2 Green
S416/H473 Filter pump on/off
pushbutton
Filter pump
run
Filterpump green
S417/H474 Cooling fan on/off
pushbutton
Cooling fan
run
Fan green
S418/H475 Heater on/off pushbutton Heater on Heater Green
H451 Protective switch tripped or Alarm MCC Red
supply fault
H452 Pressure too low, more than
2 minutes
Alarm P << red
H453 Pump changed after fault Alarm P1 <> P2 red
H454 Level low in tank Alarm L < red
H455 Pressure high Alarm P > Red
H456 Temperature too high Alarm T >> Red
H478 Nitrogen pressure low in
accumulator
Alarm N2
pressure
red
H457 Hydraulic supply unit in
operation
HV auto HV auto green
H = Lamp; S = Switch
3.2.2 I/O Signal
Following signals are available at control cabinet output terminals:
Tag Signal Contacts Abreviatio
n
Remark
K457 HV collective
alarm
SPDT HV fault Alarm
K461 HV automatic
operation
SPDT HV auto Message
K462 Pressure too low SPDT P too low Alarm
K463 Pressure too low 8xSPST
(NO)
P too low block the positioners
Signal (HV collective fault) is set when one of the following faults occur:
Protective switch tripped or supply fault (MCC)
Pressure too low, more than 2 minutes (P<<)
Pump change after fault (P1<>P2)
Level low in tank (L<)
Pressure high (P>)
Temperature too high (T>>)
Nitrogen pressure low in accumulator (N2 pressure)
Transmitter fault
1 Controller
The controller is switched to automatic mode (HV auto) as soon as the power supply is
switched on. The controller monitors and controls the hydraulic supply unit.
By remote control inputs the controller can be switched off (HV off impulse) and on
(HV on impulse). Only when signal off (HV off) is present continuous, the controller is
blocked in the off condition, also after a restart of the controller due to reset of power
supply
2 Main pumps
The main pumps supply the hydraulic oil from the tank to the accumulator. Running of
the main pumps are displayed on control panel (Pump1) (Pump2).
As soon as the controller is switched to automatic mode (HV auto) both pumps are
started, in order to reach the operating pressure as quickly as possible. The start up
of the second pump is delayed by 3 seconds. After the monitor “Press auxiliary pump
off” is crossed the standby main pump is switched off. The selected main pump
remains running.
If the pressure falls below “Press auxiliary pump on”, the standby main pump will be
switched on again, to increase the pressure again as quick as possible. The standby
pump is switched off again once the monitor “Press auxiliary pump off” has been
exceeded. If the pressure falls below “Press auxiliary pump on” three times in a row
without attending monitor “Press valve up”, a pump change is carried out and the fault
message (P1<>P2) is displayed.
If there is a fault on the selected main pump, automatic switch-over to the standby
pump takes place and the fault message (P1<>P2) is displayed.
If pressure drops below “Pressure too low” with 2 pumps running and does not recover
within 2 minutes, both pumps will be switched off and the fault message (P<<) is
displayed.
A similar sequence takes place when starting from the zero pressure condition. If the
“Pressure too low” is not crossed within two minutes both pumps will be switched off
and the fault message (P<<) is displayed.
For safety and protection reasons the main pumps are always switched off at
following fault conditions:
Level low in tank (L<)
Temperature too high (T>>)
Pressure high (P>)
When above fault conditions are cleared the main pump are switched on again. At
fault (P>) the main pump is switched-over in addition and the fault message is
(P1<>P2) is displayed.
To check, if both pumps are ready for operation, the main pumps are switched over
automatically each 3 days.
3 Accumulator charging valves
The accumulator charging valves control the accumulator pressure of hydraulic supply
unit.
As soon as the main pump is started, the corresponding accumulator charging valve is
activated. When the pressure reach “Press valve up” the accumulator charging valve is
de energized and the oil from the main pump flows back to the tank. If the pressure in
the accumulator falls below “Press valve down” the accumulator charging valve is
energized again and the oil from the main pump is charging the accumulator.
If accumulator charging is shorter than 12 second three times in a row the fault
message (N2pressure) is displayed. Remark: The nitrogen must be filled in at
depressurized accumulator. Please see instructions.
4 Filter pump
In controller automatic mode (HV auto) the filter pump is continuous in operation.
Running of the filter pump is displayed on control panel (Filter pump). The filter pump is
switched off at fault level low in tank (L<).
5 Cooling fan
The cooling fan is switched on when the oil temperature exceed “Temperature high”.
As soon the temperature falls below the threshold the cooling fan is switched off
again. Running of the cooling fan running is displayed on control panel (Fan).
6 Heater (Optional)
For low ambient temperatures the hydraulic supply unit can be optionally fitted with a
heater. The heater is switched on if the oil temperature falls below “Temperature low”.
Running of the heater is displayed on control panel (Heater).
For safety and protection reasons the heater will be switched off at following fault
conditions:
Level low in tank (L<)
Temperature too high (T>>)
When above fault conditions are cleared the heater is switched on again.
4 Power supply cabinet PVN10
Application
The power supply cabinet PVN10 is used as central supply for several local positioners
for hydraulic actuators with proportional valve.
The power supply cabinet contains one or two power supplies depending, if the
infeeding voltages is designed redundant or non redundant. The power supply cabinet
contains for each power supply one primary circuit breaker and eight output circuit
breaker for power supplying of the positioners.
Function
Each primary power supply is feed to AC-DC converters.
The outputs are short-circuit protected via circuit-breaker and can be interrupted
individually.
The output voltage of the power supply cabinet is monitored for total loss of power and
in addition for redundancy failure by redundant power supply. The failures are indicated
on the alarm relay with potential-free SPDT contacts. The alarm relay drops by any of
the above mentioned failures.
Technical Data
Electronics
Input voltage
Alternate current (AC) 85...264 VAC
Direct current (DC) 90...350 VDC
Input frequency
AC-supply 45...65 Hz
Input fusing primary 16 AT
Device fusing 12 AT
Rated power 480 W
Operating temperature -25...+50°C
Storage temperature -40...+85°C
Output voltage Vout VDC
Internal adjustable +22,5...+28,5 VDC
Output fusing
AC/DC type 8AT (each output)
Output current limitation 102 %
Derating power at >60°C 2,5% / °C
Application note
Attention: The cabinet must not be placed in direct sunlight, in order that the internal
temperature in the cabinet does not exceed the maximum permitted.
If the reference ground „M“ of the PVR10 cabinet is galvanically isolated from the
master process controller, the reference ground „M“ of PVN10 power supply cabinet has
to be connected with protection earth PE, otherwise that connection must be removed.
CCTV SYSTEM
Closed circuit television system for Sagardighi (2×300MW) power plant is designed
with full digital plan. The project is for 2×300MW subcritical burning-coal steam turbine
power unit. The closed circuit television system is installed to monitor and control #1
unit area, #2 unit area and common system area. The system is composed of the
following units: front camera unit, transmission unit, network unit, as well as the unit for
system center management, control, video record and display.
Closed circuit television system is composed of four units: 55 cameras, network transmission unit, control unit, display and record unit. Each unit includes more concrete equipments or parts. System structure schematics is as following:
Video Streamers
COLOR DOME
Control Center
`
deco
der
Video
Streamers
Switch
Color CCD Camera
Video
Manager
NetWork Record Server
CLIENT 2
To 2# lvs
CLIENT 1
To 1# lvs
1#Unit 2#Unit Common System
All functions are designed with modular. User can modify and expand its functions
according to actual demand. The system can set up different user levels, provide simple
and practical man-machine interface with graphic window, which is extremely
convenient for system administrator's operation. At the same time, using customer -
service network topology structure, the system administrator can easily add or subtract
the actual number of motoring places, and can conveniently change the definite position
of central monitoring workstation, which enhances the system utilize efficiency, and
enable the whole closed circuit television system serve the power plant with high effect
and great flexibility.
Camera
Camera part is the front part of the TV monitoring system and “eyes “of the whole
system. Its function is as follows:
Camera is selected to suit to the indoor environments and
agree with industry standard.
The selected cameras have backlight compensation function
according to the size and contrast ratio of the subject in the
whole image, the compensation electrical level needed is
calculated automatically. Even at some positions of
monitoring point the backlight phenomenon is difficult to be
avoided, the compensation function of a poor light of camera
can enable the system to produce the satisfied image, too. When the camera is shot by
strong light, the camera can not be damaged or focus light, and the image is neither
lost. By selecting the camera with the low intensity of illumination, and the super strongly
dynamic CCD can also take relatively clear pictures in the area of faint light source.
The built-in synchronizer of the camera can select the synchronous way or outer
synchronous way according to the conditions, and under any circumstance the image
scroll won’t take place in order to keep the video signal vertical and in same phase.
Specification of System Equipments
The camera of this system design selects 11 integrative and intelligent high-speed
dome type cameras (ENVD2450M is Day/Night, Color &B/W versions) and 44 color
CCD cameras (LTC0455/51 is Day/Night, Color &B/W versions) of BOSCH, which
guarantees high performance, high sensitivity effect and high quality pictures. The
cameras with Pan/Tilt and zoom lens were selected to achieve a broad field-of-view
angle and basically have no dead angle in main workshop area and other system areas.
Thus we can monitor a long distance object, and save the number of cameras. Under a
bad environment for monitoring, the outdoor camera housing (PT5723-3) with sun
shroud, thermostatic fan & heater and wiper functions was used against adverse
circumstance.
There are three cables for dome type camera (ENVD2450M), which includes power
cable (AC24V), video cable (SYV 75-3) and RS485 control cable. An outdoor dome can
be assembled for the dome type camera, which can be installed in wall-installation way
or in hanging installation way with corresponding support. The video signal of camera
and the RS485 control signal of decoder are directly sent to the video Streamer (VIP
X1). The camera power source AC240V of unit control room is transported to monitoring
spots, then is transformed to AC24V as power source of equipments.
The color CCD camera (LTC0455/50) with electric zoom lens (LTC 3384/21) is
installed in outdoor camera housing or indoor full function camera housing. The camera
housing is installed on electric Pan/Tilt (LTC9420/11). The decoder (LTC8566/50)
provides power source for camera, lens control and Pan/Tilt control. The camera video
signal and RS485 control signal of decoder are directly sent to the video Streamer (VIP
X1). The camera power source AC240V of unit control room is transported to decoder
which will provide power source for front equipments.
RUNBACK ( RB )
Runback function principle. RB is the short form of Runback which means the main auxiliary fault-trip due to unit’s actual power limitation. Control system still force to decrease the unit target load rate. This function called auxiliary unit fault load reduction. The perfect RB control strategy is established on the basis of coordinated control system. Every system must be internally coordinated (coordinated control system) and such ensure the balanced transition of the operation condition. The external coordinated control system such as FSSS, SCS, DEH, works very fast to stable the load to be decreased to unit output for premises of scope. The condition to Runback-
I. Unit is on coordinate mode.
II. Power load < 180 MW.
III. Runback push button is put into service. Runback items running condition. The unit designs have 6 kinds of items:
a) Load < 180 MW, two ID fans in operation, and one ID fan trip.
b) Load < 180 MW, two FD fans in operation, and one FD fan trip.
c) Load < 180 MW, two PA fans in operation, and one PA fan trip. d) Load < 270 MW, 4 Mills in operation, and 1 mill trip. e) Load < 220 MW, 3 Mills in operation, and 1 mill trip. f) Load < 180 MW, 2 Feed water pump in operation, 1 Feed water pump trip.
When these conditions are fully qualified and any auxiliary trips then Runback happen.
i. The process after the Runback happened.
The unit is in coordinate mode & operation is in constant pressure mode, boiler adjusts power, turbine adjust main steam pressure. According to normal working condition the target load of boiler [ 4 mill for 230MW, 3 mill for 180MW, feed water pump RB for 150MW, PA fan RB for 160MW, FD/ID fan RB for 180MW] corresponding coal feeding flow works as reducing fastly the load order of the boiler load. And according to the turbine pressure the governing pressure valve is to be set up.
ii. After RB happened automatically shut down all the super heater and reheater attemperating water, motor valve & governing valve (4 mills except RB).
iii. After RB happen when 2 mills are running in every 10 seconds 1 mill automatically trip. Trip
mill sequence will be F,E,D,A,B,C. if the B or C flow mill is running then BC flow light-heavy oil gun automatically put into service.
iv. When load reduced to target value then automatically reset RB. Or after the load getting
stable – manually reset mode is closed. At this time the unit coordinate control & stable pressure mode , turbine adjust unit power mode .
Interlock protection
ID fan trip, at the same time FD fan. PA fan trip together close A/B fan interconnecting damper. FD fan trip, together open A/B fan interconnecting damper (except APH trip by same side)
Commissioning range Commissioning range including auxiliary unit systems:
a) Mill RB b) PA fan RB c) FD fan RB d) ID fan RB e) Feed water pump RB
Provided condition before commissioning
Condition before static test
Runback function control logic configuration complete. Unit is in stop state A/B ID Fan, A/B FD fan, A/B PA fan, A-F mill, A/B air heater main motor, A/B/C feed water
pump at testing start up position.
Condition before dynamic testing put into service
DCS , DEH, BPS, PRP systems are in normal working position, main power supply and the backup power supply are safe & reliable.
Boiler side main protection(MFT) turbine side protection(ETS) and generator main
protection are already input, moreover the functions are correct & reliable. RB function control logic configuration complete, moreover passes through static test
and confirm the corrections, and finished the 1st set up of all data.
During dynamic test the unit is operating with the rated load over 270 MW. Analog variable governing system all are under normal operation, control quality fulfills
the requirement.
Analog variable load disturbance test already finished. House power changeover test finished. Take the trend group of self-providing recording parameters on the DCS .
Testing parameters record: During testing must keep record of the following parameters. Unit target load, unit actual load, order unit actual power, main steam temperature, main steam pressure target value, main steam pressure actual value, reheat steam temperature, drum water level, furnace pressure, flue gas dust oxygen %, deareator pressure, deaerator water level, FD flow quantity, primary air pressure, boiler main control order, total air content, total coal feeding content, feed water content, main steam flow etc.
Commissioning sequence RB function test program divided into 2 parts, one is dynamic test & other is static functions inspection. The most important objective of static test are as follows:- after the RB function, must check the relating of the equipments, transfer of control mode, parameter change whether correct or not. Finding out these problems is the basic steps towards dynamic test. The target of dynamic test is actually finding out that after RB, checking RB function is either reasonable or not, and every parameter is either appropriate or not, through such tests these will be further optional. And these
things ensure the safe & stable operation of the unit.
Static Test When unit is shutdown, then talking turns of simulation runback condition , check
operation load loop, moreover initially set up the load order change velocity according to the design data.
After checking the runback working condition and other control system such s FSSS
interlock system device, confirm the correction of the logic
Runback function process Passing through one kind of malfunction like simulating the control system status automatic reduction (runback) condition, except running one auxiliary unit. RB logical signal send by the main control system, FD fan, Boiler main control ,FSSS system. FSSS system requires to cut off mill and put into oil gun. RB load order repairs boiler load order. Passing through the firing rate control system, the boiler output reduce very fast , which is corresponding to the RB target value. During load reducing process the main steam pressure control system of turbine main control and the main parameter control system coordinate of MCS , these are the main parametrer of the unit, must be restored internally, and not endanger to the safe running of unit.
Dynamic operation test a) 4 mill RB test
4 mill running, the unit load stable at 270-300 MW. Turbine, boiler main control, burner, feed water pump, steam temperature and other
auxiliary control system put into service automatically. Any 1 mill stops by manual. Unit is on coordinate mode, load order automatically decrease 230MW, and decrease load
rate is 80 MW / min. Observe unit running condition, record every system curve. After unit operation getting stable , restart the stopped mill. During the test parameters must monitor- FD fan current, ID fan current , furnace
pressure , drum water level, burner condition, main steam temperature, reheat steam temperature.
Important things to remember:
i. Attentively monitoring boiler burner condition. If the boiler pressure deteriorate then must intervene MFT manually.
ii. Monitoring drum water level and steam temperature. For unit’s maintenance operation if
necessary then intervene MFT manually.
iii. If main steam pressure unable to maintain then further decrease target load by manual.
b) 3 mill RB test:
3 mills in operation. Unit load stable at above 220MW. Unit, boiler main control, burners, feed water pump, steam temperature and other auxiliary
control system function all are put into service. Stop one mill by manual. Alarm display “full RB”. When unit is on coordinate mode, the load order automatically decrease to 180MW. The load
rate is 80 MW /min. Automatically close every superheater, reheater, desuperheating water motor operated valve
and governing valve. Moreover BC &DD light-heavy oil gun automatically put into service.(If
light-heavy oil gun automatically put into service during the operation of B & C mill, then DD light-heavy oil gun automatically put into service )
Observe unit running condition, record every system curve, After unit operation is stable, restart the stopped mill. During the test parameters must monitor-- FD fan current, ID fan current
furnace pressure, drum water level, burner condition, main steam temperature, reheat steam temperature. Important things to remember:
i. Attentively monitoring boiler burner condition. If the boiler pressure deteriorate then must
intervene MFT manually . ii. Monitoring drum water level and steam temperature. For unit’s maintenance operation if
necessary then intervene MFT manually. iii. If main steam pressure unable to maintain then further decrease target load by manual.
FD fan RB test Unit load stable between180-300MW Unit, boiler main control, burners, feed water pump, steam temperature and other
auxiliary control system function all are put into service. Until the load and steam pressure getting stable manually trip one FD fan. Alarm display “FD fan RB”. No. 1 mill automatically trip, after 10 seconds no.2 mill also trip, only left 3
rd mill for
operation. When unit is on coordinate mode , the load order automatically decrease to 180MW.
The load rate is 150 MW /min. Automatically close every superheater, reheater, desuperheating water motor
operated valve and governing valve. Moreover BC &DD light-heavy oil gun automatically put into service.(If light-heavy oil gun automatically put into service during the operation of B & C mill, then DD light-heavy oil gun automatically put into service )
MIS SYSTEM (PGIM)
1. MIS overview
A plant wide Fiber-optic 1 GBPS (minimum) high speed backbone Network & workgroups is realized in the power plant. This network is used by different users of the plant for over viewing selective Plant Graphics & data on real time basis, historical data & trends and MIS reports such as Plant Generation, Unit Heat rate, Auxiliary Power consumption, DM make up water consumption, Coal / Oil stock & consumption etc. and other day to day online maintenance, Inventory & purchase related functions.
By ABB understanding, MIS can be divided to 6 parts in this project:
Plant network
MIS-DCS interface(special for customer care)
Process monitor system
Performance calculation
Boiler life calculation
Maintenance & Inventory Management system
The following is for detail.
2. Plant network
In this project, ABB provides a typical 2 level ,star style, switch network. The first level is second level switch to core switch, this is backbone network with 1GBPS bandwidth. The second level is terminal PC to second level switch, each second level switch has 24 100M ports for user.
The plant network consists of:
1 core switch – WS-3750-24 + WS-3750-12G, from CISCO.
7 second level switches – WS-2950G-24-EI, from CISCO
Servers – Real Time Server, 2 Performance and life Server, CMMS Server – IBM
X346, from IBM
21 terminal PC(IBM) with UPS(APC), Printers(HP)
2 gateway PC(Advanced)
3 Firewalls(CISCO)
The 7 second level switches will be located in different building. They will connect to
core switch with 1G bandwidth as main network. 1 terminal PC will be used as shift in charge PC to show analysis data to operator. The other terminal PC will connect to second level switch in their building. 1 Firewall will be used to connect internet, it’s in Maintenance department. The 2 gateway PC will connect to DCS network with firewall isolation.
The PGIM database will be installed in RealTime Server(MIS Server) for process data management and store.
The Performance and life Server is for performance and life calculation. The input data
required for the calculation are read out from the PGIM database, calculated within the “Technical Calculation”, and then the results are written back into the PGIM real-time database.
3. MIS-DCS interface
For MIS-DCS interface, ABB provides 2 gateways for 2 units, the OPC protocol will
be used for connection between DCS and MIS. The 3 network adapters will be installed
in the gateway, 2 connect to DCS SW for redundant configuration, 1 connects to core
switch of MIS.
In the gateway, the OPC Scanner will be installed and configured to communicate
with PGP OPC Server (DCS side) as OPC Client; it gets process data and transfer data
to PGIM database. Firewall will be used to isolate MIS from DCS for preventing illegal
network access.
4. System protection
In the plant network, there is a very import task for network design – system protection.
Virus, illegal network access, etc., many things will menace to network system. We will use 3 security technology- Network firewall, Virus firewall and VLAN to protect network, servers and terminals. Network firewall
Network firewall is be used to isolate different part in network to prevent illegal network access. It
has 2 Ethernet ports, which have different security level. According security access rule, the data flow through the firewall can be just transferred from high security port to low security port. In fact, We’ll define DCS is high security system, MIS is low security system, so data can be just transferred from DCS to MIS, and cannot be transferred from MIS to DCS, so the DCS is safe. This philosophy realizes data protection for DCS.
There is also NAT technology in the network firewall, internal network use NAT to hide network
address from external network.. In this project, internet will not know MIS network address in power plant, and MIS will not know DCS network address, so, the vicious network attack will be disable due to there no object - object address is invisible.
Virus firewall
Virus firewall is to prevent virus. This is software with C/S structure, it will be installed across all network. The server of virus firewall will be updated automatically from internet, other terminal in the plant network will get the newest virus library from the server. In this way, network will keep away from virus. VLAN
VLAN technology is realized in switch, it like a independent network. In the network, we will define all Sever in special VLAN; access to these servers will be controlled by Access List in third level of switch. Whatever IP, other VLAN, who is not authorized, cannot access these server. Using VLAN, Virus firewall (mentioned above), these servers is safe surely.
5. Process monitor system
ABB will realize a process monitor system in MIS of this project for users to over view important, selective Plant Graphics & data on real time basis, historical data & trends, and results of calculation. The product is PGIM; it includes scanner, server and client.
Process data acquisition (scanner)
Scanners to acquire data from a number of different distributed control systems. In addition to this on-line data transfer, manual inputs into the system (for example for laboratory data) are also possible.
The scanners permit a preprocessing of process data. Based on the incoming values, it is possible to derive events (messages) or to sum quantities using limit value checks. Counters can be implemented which will integrate, for instance, the operating hours or determine a switching frequency. This occurs when the status of binary values change. This preprocessing can be extended at any time by linking with DLL modules (Dynamic Link Library).
Process Data Management (Server)
PGIM includes a process data server to store:
• Signal descriptions.
• Current process data (real-time data).
• Historical process data (long-term storage).
Process data includes these stored values:
• The time of acquisition.
• The physical value.
• Detailed status information (for example measured value disturbed).
This data is retrieved from the lower-level distributed control systems and generated in PGIM. The process data server is the central element of PGIM, from which all the other functions obtain their data. It provides a high degree of safety and processing speed.
Data can be compressed for long-term storage using, for example:
• Average value.
• Minimum value.
• Maximum value.
• Last value.
• Tolerance band methods.
The tolerance band procedure is the default method of compression.
With interface functions (API), the databases can be opened for read and write access from software applications. Common interfaces (such as OLE, SQL) ensure compatibility with the usual office environment, and common Microsoft-Office products.
Process Data Evaluation (Clients)
Networked computer systems are required for the management of process data on process data servers. They are also required for the distribution of data to the respective technical departments. Commercial PC’s can be used as client workstations for data evaluation, operation and configuration.
The interconnected client-server structure minimizes the data flow in the network. Various specialized clients (software applications) provide fast and individual services for the specific tasks of plant management.
6. Performance calculation
ABB provides “PGIM Technical performance Calculation” for performance calculation
in power plant to cover customer requirements.
The program “Technical performance Calculation” is used to determine online characteristic parameters of the essential plant components in energy supply plants and to compare these parameters with set points in order to achieve an improved operation of the plant. Variables such as efficiency, contamination factors, warming up ranges, etc. are calculated cyclically and compared to time-variant set points.
The calculation modules provided by ABB Utilities are implemented as C-functions and combined in a Dynamic Link Library (DLL). In addition to this, own modules can be generated by the user and included as a DLL. MS-Excel, which has access to the C-functions, is used as configuration surface.
The input data required for the calculation are read out from the Information Management System (PGIM), calculated within the “Technical Calculation”, and then the results are written back into the PGIM real-time database. The representation of the results is effected in the PGIM either in process displays or in line diagrams. Configuration of the Calculation Server (CalcServer) is effected via Excel. Subsequently, the finished configuration is transferred as a file to the CalcServer. Then there will be no feedback from the CalcServer to Excel until, e.g., the configuration is balanced or the calculations of the CalcServer are stopped. Thus, the CalcServer continues to be controlled via MS-Excel. However, Excel has not to be opened during the whole operating time of the CalcServer, but it can be quitted after configuration.
The scope of the performance calculation:
Class (I) - Equipment protection calculations (software generated alarms);
Class (II) - Plant/equipment efficiency, Heat rate calculations;
Class (III) – Others calculations.
The detail follows customer requirements in the part of technical protocol.
7. Boiler life calculation
ABB provides “OPTIMAX Boiler Life” for calculation of life of boiler. The “OPTIMAX Boiler Life” application is a product in the OPTIMAX product family. It
is used to calculate the total degree of exhaustion of thick-walled steam-generating components which are subject to pressure and temperature. The graphic Windows surface allows quick access to the results data of the individual components and thus allows an evaluation of the general state of the steam-generating plant.
The calculations are made under consideration of the preset parameters in TRD 301 and TRD 508 plants. The data required for the calculations such as pressure, temperature, wall temperature differential, are determined as a function of time and organized into classified data prior to further processing. Based on these calculations, maintenance intervals, for example, may be increased in an optimum fashion.
Scope of the Boiler Life calculation: • Drum (sphere, Cylinder) • Superheater header (inlet and outlet) • Reheater header (inlet and outlet)
Enterprise Asset Maintenance (MAXIMO)
Driven by the demanding and changing business practices requiring advance
technological solutions and the worsening situation caused by the limitations of old
technology and design concept, Sargardighi Thermal Power Plant had been reviewing
various solutions to meet business requirements and gain competitive advantages by
harvesting the technological advances. MRO SOFTWARE is offering a system blueprint
for the next generation Enterprise Asset Maintenance (EAM) System taking future
business and technological changes into consideration.
The proposed system acts as an operational system with management decision support
facilities. It meets the objective of providing timely and integrated information to
Engineering management and engineers to make sound decisions on strategic issues.
On the technical side, the system environment is flexible enough to take advantages of
technical advances to enables users to respond quickly to sudden and rapid changes of
business environments.
MAXIMO
Maximo is a computerized asset maintenance system that provides asset management,
work management, materials management, and purchasing capabilities to help
companies maximize productivity and extend the life of their revenue-generating assets.
Maximo allows your company to create a strategy for maintenance, repair,and
operations related to both Enterprise Asset Management (EAM) and Information
Technology Asset Management (ITAM).
Maximo stores and maintains data about your company’s assets, facilities, and
inventory. You can use this information to help you schedule maintenance work, track
asset status, manage inventory and resources, and analyze costs.
Maximo.s software suite can be configured to meet the needs of a variety of
different businesses, including:
Manufacturing and utilities production
Hotels, universities, and other facilities
Buses, trains, aircraft, and other fleet vehicles
Information technology (IT) assets
Maximo helps companies to improve the availability and performance of their
revenue-generating assets while decreasing operating costs, without
increasing safety issues. Maximo lets you:
Record service requests and all related records and communications from
the initial request to problem resolution. Track work orders and failures to better schedule preventive maintenance.
Track information technology (IT) assets and their configurations across a network.
Track inventory use to find optimum stock levels. The goal is to maximize availability
of items for upcoming work, while also reducing unnecessary inventory and
associated carrying costs.
Track purchasing of inventory stores and materials for work orders. To assist in
creating budgets, you can use Maximo to track costs for labor, materials, services,
assets, and tools used to complete work orders.
Reduce on-the-job injuries and accidents by identifying hazards in the workplace
and precautions needed to increase safety.
Maximo can automate processes that are repetitive or happen on regular intervals, for
example, preventive maintenance, periodic inspections, or reordering inventory items.
Maximo.s applications are grouped into modules. The applications in a module have
similar purposes, for example, applications related to purchasing are grouped together.
Some applications, such as Work Order Tracking, function individually, while others,
such as Precautions, create records designed to be used in conjunction with records
created in other applications. Depending on your job description and security
permissions, you may have access to some or all of the Maximo modules and
applications. Chapters that appear later in this guide describe the main modules and
applications in more detail.
2. Asset Management
As utilities refocus on the fundamentals, many are increasing their investment in work
management systems. The scope of work management projects is growing to include
supply chain management, condition-based maintenance, advanced planning and
scheduling for spare parts, automated workforce scheduling/optimization, and mobile
computing. All help to drive operational efficiency and raise the return on assets. Best
practices are being introduced and becoming integral to more efficient work
management in a number of ways. Best practices build integrity-based checks and
balances into the system. Standardizing processes throughout the enterprise improves
not only the asset performance but also worker productivity and safety.
Because power plant is an asset-intensive enterprise, asset performance is the basic
and key factor to ensure the successful management of a cetain enterprise. So how to
improve the asset management of a power plant is very important and the first task to
an excellent management.
Function Design
Track asset, associated costs, histories, and failures of a serialized piece of
asset as it moves throughout a plant or facility.
Build the asset hierarchy, an arrangement of buildings, departments, asset, and
subassemblies. It provides a convenient way to roll up maintenance costs so
that you can check accumulated costs at any level, at any time. It also makes it
easy to find a particular asset number.
Use the Drilldown to view location or asset information. You can locate and
select any piece of asset by scrolling down through a location hierarchy to a
particular location and then viewing the asset there, or by scrolling down through
an asset hierarchy.
Use Asset Modeling to determine relationships between a piece of asset, its
physical location and the systems with which it may be associated.
Create hierarchies identifying operating locations as part of multiple systems.
Asset can be used in more than one location.
Associate subassemblies (child asset) and/or spare parts (inventory items) with
the current asset record, thereby building the asset hierarchy.
View PMs (Preventative Maintenance’s) and service information for the selected
asset number.
Build failure code hierarchies to record asset problems for analysis. Set
measurement points, perform trending and defect analysis through Condition
Monitoring. This can display all the measurement points for the
selected asset, including: high and low warning and action values; value and
date of the last reading; date of the last work order generated in response to an
unacceptable reading. Readings that fall between the lower and upper warning
limits can be considered safe.
MAXIMO allows you to report actual meter values for multiple meters on the
current piece of asset. You can give meters more or less importance (weight) so
that it has a greater or lesser effect on the average units per day that MAXIMO
calculates. You can specify whether or not a meter should get updated when the
meter on the asset’s parent is updated.
MAXIMO provide Routes in the following ways: apply the route to a preventive
maintenance record to generate inspection-type work orders for all work assets
listed as stops on the route; apply the route to a work order, and generate child
work orders for each work asset listed as a stop on the route; create a route on
which you specify that child work orders generated for the route stops are
treated as "details" on the parent work order. When you print the parent work
order, you see the detail-type work orders as work order operations on the
parent work order. You can also associate job plan with route.
Use the Specification of asset to associate the selected asset to a specification
template, it helps classify assets into a hierarchy of up to five levels, making it
easier to locate asset.
Assign stores, repair shops, and vendors as location records to facilitate
continual tracking of asset as it is moved.
Analyze the potential for failure based on a piece of asset’s location and the
possible effects on systems with which it is associated. You can setup your own
failure code system for tracing and analysis.
Enquiry associate asset information, include cost, warranty, running status,
calculate total down time for a piece of asset.
Apply calendar to any asset, so you can estimate run time and planned down
time and idle time.
Interface and Field Design
You use the Assets application to create and store asset numbers and corresponding information, such as parent, location, vendor, up/down status, and maintenance costs for each asset.
Tabs in the Assets application let you build the asset hierarchy, an arrangement of buildings, departments, assets, and subassemblies. The asset hierarchy provides a convenient way to roll up maintenance costs so that you can check accumulated costs at any level, at any time. It also makes it easy to find a particular asset number.
The Assets application contains the following tabs:
Basic Principles The G-CEM1000 uses an in-situ probe set into a duct to measure CO concentration in the flue gases. The probe includes a section that allows the diffusion of flue gases into the measurement zone or the dispersion of zero/purge air out of the tube and into the duct. The analyser uses infrared gas cell correlation technology to determine the CO levels in the flue gases as they diffuse into the measurement chamber. The diffusion cell enables accurate measurements to be made in high flue gas dust levels exceeding several gram/m3. As with conventional cross-duct analysers, this probe configuration does not require the extraction of a sample from the gas stream and makes its measurement by analysing the way in which infrared radiation, transmitted through the measurement section of the probe, is modified by the gases present. The transceiver unit containing the infrared source and detector system, required to measure the received light energy after its passage through the gas, is totally isolated from the flue gas. There is, therefore, no contact between the analyser electronics and the flue gas. Correctly installed and commissioned, this provides the opportunity to achieve very low maintenance factors and totally eliminates any possibility of altering the composition of the flue gases to be measured. The probe is inclined downward at an angle of 5o to encourage condensation to gather at the lower end and then dissipate in the stack. For smaller duct sizes, the G-CEM1000 may be supplied with a shorter probe and in this case, as build-up of condensate should be less, the probe may be mounted horizontally. The general arrangement of the G-CEM1000 monitor is illustrated below in Figure 1.
The remaining components of the G-CEM1000 are :
A Power Supply Unit (PSU) to accept mains input voltages and provide 48V supply for the analyser. A Data Display Unit (DDU) into which is routed the cabling from the PSU & junction box. The unit incorporates a LCD and may be mounted local to the analyser or remotely. A Junction Box through which is routed the cabling from the analyser & DDU. The unit should be mounted local to the analyser. Although G-CEM1000 monitors can be used for process gas analysis, they have been primarily designed to monitor pollutant emissions from industrial stacks. Legislation governing such emissions usually requires data to be reported in very specific formats. G-CEM1000 analysers are therefore designed to fulfil this requirement without the need for external data manipulation. Although differing in detail from country to country, the essential demands of legislation are common world-wide. 2. Analogue and Logic Outputs The DDU is equipped with two 0/4-20mA analogue outputs, fully configurable from the keypad. Volt-free SPCO contact outputs (50V/1A) are provided for data valid and measurement alarm levels. 3. Analyser Protection G-CEM1000 monitors are designed for outdoor installation and all units are constructed to IP68 standards, designed for ambient temperatures from -20o to +60oC. For outdoor installation, an optional weather shield is recommended for the transceiver.
Measurement Principles CO absorbs infrared energy. The spectrum has the typical characteristics of a diatomic gas and comprises a number of fine absorption bands. The CO spectrum is centred on a wavelength of 4.7μm. This type of spectrum allows the principle of gas cell correlation to be employed in the spectrographic analysis to determine the concentration of gas present. If a sample of a high concentration of CO is inserted into an infrared beam, the fine absorption bands in the CO spectrum will reach a saturation point where they are capable of absorbing all the energy in the beam corresponding to those wavelengths. The presence of further amounts of gas will not result in any further absorption and thus attenuation of the infrared beam, whereas without the high concentration sample, even small amounts of CO would produce an attenuation of the beam. By taking a ratio of measurements of the attenuation of an infrared beam with and without a high concentration sample of the gas being measured, a function can be derived which is dependent solely upon the concentration of the gas to be measured.
Because the technique uses a sample of the gas itself as a highly specific filter, the measurement has extremely high immunity to other interfering gases. 2.1. Measurement Elements An infrared beam is generated from a small, black-body emitter. Radiation from this source is focussed by a lens onto a mirror. The reflected energy is received and focussed by a second lens onto a highly sensitive infrared detector. Immediately in front of the detector is a ‘band-pass’ filter for CO. Immediately in front of this filter is a wheel that generates two optical paths; one has a sealed gas cell containing 100% pure CO; the other optical path is clear. The wheel is rotated by a stepper motor at a constant speed of 1Hz, under the control of a supervisory processor. As each of the two channels sweeps across the infrared beam the processor digitises the detector output to produce two detector signals, D1 measurement and D2 reference. These values are used to compute parameters YCO that are unique functions of CO. Detector Operation The detector is a two-stage Peltier-cooled lead selenide element. Lead selenide has a very high sensitivity to infrared energy. However, in order to obtain the necessary response for the CO measurement at a wavelength of 4.7μm, the element must be cooled to a temperature of approximately -20oC. This is achieved by the encapsulated thermoelectric Peltier cooler. The detector element temperature is monitored by an integral thermistor. The thermistor resistance is monitored by the supervisory processor and is used to control the current, and hence the power, applied to the Peltier cooler to achieve a stable detector temperature at around -20oC. The detector itself is a photo-conductive device. A series of pre-amplifiers mounted within a shielded metal enclosure ensures a stable, fast response output suitable for digitisation by the processor. Stepper Motor Control The supervisory processor develops a frequency signal which is used to drive the stepper motor. Accurate timing of this signal ensures that the gas cell wheel operates at exactly 1Hz. By counting the pulses in the frequency drive to the motor the processor knows exactly when to digitise the detector output signal in order to obtain the two signals necessary for the calculation of CO concentration. Once each revolution, a small pin on the gas wheel interrupts an optical switch to act as a reference point for the processor to begin counting pulses for the next revolution of the wheel. Diagnostic Data Each second, detector values D1 measured and D2 reference, are measured and smoothed to maximise signal-to-noise ratio. From the smoothed values the following parameter is calculated : YCO = 80000 – SCCO . D1 measured/D2 reference where SCCO is a calibration constant.
This parameter is a unique function of CO and from it the processor computes the concentration level of CO in ppm in the measurement path.
G-CEM 4000 Multi-Gas Analyser G-CEM4000 Basic Principles The G-CEM4000 analyser uses an in-situ probe set into a duct to measure the concentration of gases of interest. Figure 2 illustrates the arrangement. The in-situ tube includes a section that allows the diffusion of flue gases into the measurement zone or the dispersion of purge or calibration gas out of the tube and into the duct. This section of the tube is the analysers’ measurement cell. The analyser is capable of simultaneous measurement of up to six different gases (plus water vapour as a seventh measurement if required). As with conventional cross-duct analysers, this probe configuration does not require the extraction of a sample from the gas stream and makes its measurement by analysing the way in which infrared radiation, transmitted through the measurement section of the probe, is modified by the gases present.
The transceiver unit containing the infrared source and detector system, required to measure the received light energy after its passage through the gas, is totally isolated from the flue gas. There is, therefore, no contact between the analyser electronics and the flue gas. Correctly installed and commissioned, this provides the opportunity to achieve very low maintenance factors and totally eliminates any possibility of altering the composition of the flue gases to be measured. The remaining components of a G-CEM4000 analyser are :
• The Gas Control Unit (GCU) that controls the input of zero and span calibration gases into the analyser. It contains the necessary compressed air filtration and drying
equipment to ensure high quality air supply for the zero calibration and probe purge functions. The analyser power supply and Station Control Unit (SCU) are also housed within the GCU. The function of the SCU is as an emissions data processing unit, communications centre for the monitor and controller of the zero and span calibration functions. The SCU also acts as a data logging device in which hours emission and diagnostic data is stored for retrieval in the case of loss of main data logging in the remote pc or DCS system.
• A Junction Box through which is routed the cabling from the transceiver and the
temperature, pressure and oxygen sensors and the cable to the GCU. The unit should be mounted local to the analyser.
• The Central Data Controller (CDC) that accepts data from 1 to 16 SCUs and
processes the data for onward transmission to a remote pc or SCADA system.
Normalisation Emission limits are always defined under standard conditions of temperature, pressure and air dilution (air dilution is defined using the waste gas CO
2 or O
2 concentration). Most
legislation also requires concentrations to be reported on a dry basis; i.e. water vapour in the flue gas is not permitted to dilute the measurement. The correction of the measurement from ‘as measured conditions’ to ‘standard’ conditions is known as ‘normalisation’. Like all cross-duct analysers, G-CEM4000 analysers measure concentrations of pollutant ppm (parts per million by volume) or %, under the conditions at the measurement position. This basic ppm measurement is always corrected for the duct pressure and presented as vpm by the analyser. G-CEM4000 analysers have the capability for the outputs and display
to be configured in vpm (or %) or mg/m3
(which is a mathematical conversion depending on the molecular weight of the gas being measured and the flue gas temperature), or in
mg/Nm3
(i.e. ’normalised’ to the required standard conditions). When the outputs are required to be normalised to a pre-defined O
2 concentration as
opposed to a CO2
level, then an external O2
4-20mA signal representing Oxygen levels can
be input into the G-CEM4000. All other normalising parameters i.e. pressure, temperature, and CO
2 are measured as standard by the G-CEM4000
D-CEM2000 Dust Monitor
Introduction Dust and smoke emissions have for a long time been recognised as major atmosphere pollutants, particularly since such emissions from stacks are clearly visible to an observer. There has been a requirement for monitoring, and quantifying these emissions, for some time and a variety of instruments have been marketed throughout the world for this purpose. Instruments in the past have, however, generally proved to be unreliable, falling rapidly into disuse or to be so expensive and complex as to be affordable only by the very large users, such as power stations. The CODEL D-CEM2000 seeks to overcome these
problems by providing a reliable, simple to use instrument with low maintenance requirements.
2.2. Transceiver Units Two identical transceivers are mounted on opposite sides of the stack. The transceivers each contain a sensing head comprising a light source, a detector and associated optical assembly; a calibration mirror and rotary valve and the electronics associated with control and measurement. Should the power fail, integral power-packs return the valves to a closed position to protect the sensing heads. 2.3. Signal Processor Unit (SPU) The D-CEM2000 SPU receives its 48V DC power from the SCU via the 4-core SmartBUS serial data link. Signals from the two transceivers are processed to derive the transmissivity values and compute the opacity output. Diagnostic communication is provided via the SCU and a laptop computer operating SmartCOM software. Gain adjustments for the transducer detector signals are provided by trim potentiometers in this processor. Details for adjustment can be found in Section 7. Commissioning. 2.4. Station Control Unit (SCU) The SCU provides 48V DC power for the analysers on its local data bus. Power input to the SCU is 86 to 264V AC maximum. The power supply is housed in one side of the SCU and the 48V DC power rail is fed through internally into the processor section of the device. The SCU is linked to the analyser by means of a 4-wire data bus (local data bus). This bus carries 48V power to the analyser as well as two serial communication lines referred to as MOSI (Master Out/Slave In) and MISO (Master In/Slave Out). On this data bus the SCU acts as the Master Device and the analyser as a Slave device.
Measurement Principle
Consider the two identical transceiver units positioned at either side of the flue (or duct), unit 1 and unit 2. The transmissivity of light from unit 1 to unit 2 (unit 1 transmitting) can be represented by the equation :
12 = K1 (D21/D11) where : K1 = gain constant to produce
= 1 (100% transmissivity, clean air condition) D11 = the detector output at unit 1 (internal reference level) D21 = the detector output at unit 2 The transmissivity of light from unit 2 to unit 1 (unit 2 transmitting) can also be represented by the equation :
21 = K2 (D12/D22) where :
K2 = gain constant to produce = 1 D12 = the detector output at unit 1 D22 = the detector output at unit 2 (internal reference level) This is demonstrated schematically in Figure 3.
Overall transmissivity of the system () can, therefore, be represented as:
= 12 . 21
= K1 (D21/D11) . K2 (D12/D22) which can be rewritten as :
= K1K2 (D21/D22) . (D12/D11) As the two bracketed terms above are measured from only one of the transceiver units, the output of the instrument is independent of drift of either detector.
V-CEM5000 Flow Monitor
Introduction
Correcting measurements to standard temperature, oxygen levels, etc., allows the density of emissions to be normalised (e.g. mg/Nm3), but in order to obtain a measurement of total emissions for pollution monitoring (e.g. kg/hr), it is necessary to measure flow. Many methods require direct contact with the hot dirty gases resulting in high maintenance costs and potential unreliability. The CODEL Model V-CEM5000 Gas Velocity Monitor utilises an infrared cross-correlation technique that requires no contact with the flue gases. The method used resembles flow measurement with chemical dye or radioactive tracers, where the velocity is derived from the transport time of the tracer between two measuring points a known distance apart. However, instead of an artificial tracer being added, the naturally occurring fluctuations of the infrared energy in the gas stream are used as the tracer. Fully purged transducers with no moving components make the system highly reliable and minimise maintenance requirements. The instrument is ideally suited to monitoring the flow rate of hot, dirty gases.
2.2. Transducer Units Each transducer unit consists of a broad band infrared detector, a lens to focus the radiation received on the detector and a pre-amplification circuit board, all housed within a fully sealed, epoxy-coated aluminium enclosure. The transducers are supplied with air purge units to maintain the cleanliness of the transducer windows.
2.3. Signal Processor Unit (SPU) The V-CEM5000 signal processor receives its 48V DC power from the SCU via the 4-core Smartbus serial datalink. Signals from the two transducers are processed and correlated to derive the transmission time of the gas flow from the first transducer to the second and thus compute the gas velocity. Diagnostic communication is provided via the SCU and a laptop computer operating SmartCom software.
3. Measurement Principle Gas flow is rarely laminar. Turbulence in the flow produces a series of swirling eddies and vortices that are transported with the bulk flow. Infrared radiation, emitted by a hot gas system, is characterised by a flickering signal resulting from the swirling effect of these vortices. Two infrared detectors, placed a small distance apart, will produce very similar flickering signals, but with a displacement in time equivalent to the time taken for the bulk gas flow to carry the vortices from the first detector to the second. The V-CEM5000 uses a cross-correlation technique to measure this time displacement and hence the flow. The two signals from the infrared transducer units are defined as A(t) and B(t) as shown below.
The time-of-flight (and hence the flow velocity) of the naturally occurring turbulent eddies within the flow stream can be determined by cross-correlating the two signals as shown in the following equation :
where is a variable time delay imposed on the signal A(t). Using this function a correlogram can be computed which has a maximum when the time-of-flight and ‘t’ are equal.