600M.W.Plant C&I course

7/28/2019 600M.W.Plant C&I course

1/91

N Company Thermal Application Training Material

Training Material for Indian N Company

Thermal Equipment and Application


2/91


CONTENT

CHAPTER 1 OVERVIEW OF THERMAL PROCESS AUTOMATION OF POWER PLANT

1.OVERVIEW .....................................................................................................1.1 Automatic Detection .................................................................................. 1.2 Automatic Adjustment................................................................................ 1.3 Automatic Protection ................................................................................................................ 4

1.4 Sequence Control System (SCS) ............................................................................................... 4

2.BASIC CONCEPTS OREQUIPMENT.............................................................................................. 43.THERMAL DETECTION AND CONTROL EQUIPMENT........................................................... 6

3.1 Instrumentation (Or Detecting Elements) ..................................................................... 6

3.2 Transducer.................................................................................................................................. 6

3.3 Display Instrument.................................................................................................................... 6

3.4 Regula tor.................................................................................................................................... 7

3.5 Actuator...................................................................................................................................... 7

4.AUTOMATIC FUNCTION CLASSIFICATION AND INTERLOCKPROTECTION TEST RULES FOR

LARGE THERMAL POWERUNITS .................................................................4.1 Classification, purpose and task distribution of interlock protection 4.2 Test methods for interlock protection ...................................................................................... 8

4.3 Confirmation of the test result of interlock protection ........................ CHAPTER 2 DISTRIBUTED CONTROL SYSTEMS (DCS) ............................10


3/91


1 PIDFIGURE ..................................................................................................................................... 70

2SAMAFIGURE .................................................................................................................................. 77


4/91


Chapter 1 Overview of Thermal Process Automation of Power Plant

1. Overview:

Thermal process automation of power plant includes the following items:

1. 1 Automatic Detection

Automatic inspection, measurement and supervision of various physical & chemical quantities which reflect

operation conditions in the process of production and the working condition of production equipment are referred to

as automatic detection. The purpose of automatic detection is to supervise the production process and inspect the

operation effect.

The detection parameters of thermal power units include thermal parameters such as temperature, pressure,

differential pressure, flow, water level, flue gas oxygen content and mechanical parameters such as rotating speed,

axial displacement and vibration. The thermal parameters and mechanical parameters to be detected will be

transformed into their corresponding electric quantities. These electric quantities will be delivered to display

instruments so as to show the corresponding detected parameters. The common display instruments include all

kinds of indicators, recorders and data loggers, etc. The display modes include pointer display, digital display,

recording c r e and totali er etc In recent ears large and medi m si ed thermal po er nits adopt distrib ted


5/91


(2) Discharge the stored energy automatically, e.g. open the boiler safety valves and the coal pulverized

explosion door.

(3) Limit the open degree of various regulating valves and dampers.

(4) Interlock: it is a protection procedure when abnormal situations or incorrect operation occur. For example,

when some equipment fails, the interlock system will make the relevant equipment out of service in preset order. If

the order is wrong or some equipment is missed, further accident or equipment destruction will happen.

Automatic protection of the boiler mainly includes the following items: flameout protection in furnace,

automatic protection of high & low water level and of overtemperature & overpressure, and interlock

protection under accident condit ions, etc. Automatic protec tion of the turbine mainly includes the following

items: overspeed protection, oil failure trip, low vacuum protection, axial displacement protection, differential

expansion protection and vibration protection, etc.

1.4 Sequence Control System (SCS)

Sequence control system is a series of automatic operations on the production equipment and process

according to the preset steps and conditions, with no human interference for the switch among different

operating steps. Sequence control system is a lso referred to as program control.Sequence control system of the boiler mainly includes the following items: boiler ignition, boiler

soot-blowing, start-stop of FD fan, ID fan and milling system, and operation of water treatment equipment, etc.

Sequence control system of the turbine is mainly refers to its automatic start-up and stop.

2. Basic Concepts or Equipment

Analogue value: it is a physical quantity that changes continuously with time. Its characteristics can be


6/91


includes CRT, keyboard and application software, etc.

Thermal Resistance (RTO): it is mainly applied in coil temperature in generator and the main important

auxiliary motor and the temperature measuring points of low temperature range. According to different structure,

thermal resistances can be classified into assembled thermal resistance and armoured thermal resistance. Thermal

resistances are common temperature elements with measured temperature less than 150 in general. They are

temperature sensing elements made of metallic conductors or semiconductors whose resistance has a certain

functional relationship with temperature. The common thermal resistances are copper thermoresistances such as

CU50 and platinum thermoresistances such as Pt100. DC or AC balanced or unbalanced bridge system is the most

common circuit to convert and output the thermal resistance signals. There are two types of resistance connection:

doublewire connection and three-wire connection. In order to reduce the influence of ambient temperature on

measurement, three-wire connection is adopted in the thermal resistance in units of Project . Or in other words,

the thermal resistance has three lead-out wires among which one is separately connected with bridge source,

therefore, the measuring errors resulted from wire resistance changes between the thermocouple wire holder and the

temperature measurement channel under changing ambient temperature can be greatly reduced.

Thermocouple (T/C): according to temperature measuring range and graduation mark, thermocouples are

mainly classified into two types, i.e., E type and K type. They can also be mainly classified into the first-class and

the second-class thermocouples according to thermocouple classes. The thermocouples mainly used for measuring

th i i t t t t t d bl th l ( h th t l ll t t )


7/91


parameters of the mainframe and its important auxiliaries so as to ensure safe operation of the unit. The output of

TSI will simultaneously be sent to the recorders for recording and to DCS for real-time status monitoring. Some

signals such as horizontal & vertical vibration and axial displacement of the mainframes #1~#10 bearings are

involved in the trip protection of the main turbine.

Instrument precision: the main important transducer is generally required of a precision class of 0.5, namely,

0.5%. For example, when the measuring range of the main steam temperature is 0 ~ 600 , precision class of 0.5

means that the absolute error is 600 0.5% =3 .

3. Thermal Detection and Control Equipment

3.1 Instrumentation (Or Detecting Elements)

Instrumentation is directly connected to the tested objects so as to feel the change of the parameters to be

tested and transform the tested parameters into the corresponding signals for output. For example,

thermocouples or thermoresistances will transform temperature into the corresponding electricity, potential or

resistance; throttling devices will transform flow rate into differential pressure; double-chamber balancing

vessels will transform the drum water level into differential pressure.

3.2 Transducer

The temperature transducer will transform the potential or resistance that reflects temperature into the

corresponding electricity signals. The pressure- or differential pressure-transducer will transform pressure or

diff ti l (i l di diff ti l i l f fl t d t l l) i t DC t i l


8/91


3.5 Actuator

Actuators will accept the output signals from regulators and transform them into angular displacement or

linear displacement to drive the regulating mechanism, and alter the open degree of regulating valves ordampers to control regulating variable so as to make the production process meet the requirements. Like human

hands and feet, actuators will act to replace human operation.

According to different kinds of energy used, actuators can be classified into pneumatic actuators, electric

actuators and hydraulic actuators. The three types of actuators have their own advantages and disadvantages.

Electric actuators are more commonly used. In recent years, thermal power units of 300MW and above mostly

adopt the imported actuators of excellent performance such as the Rotork electric actuators manufactured by

England Rotork Controls Co., Ltd. and the RHA electric actuators manufactured by German Hartmann & Braun

Company.

4. Automatic Function Classification and Interlock Protection Test Rules for Large Thermal

Power Units

The control system of thermal power units mainly includes data acquisition system (DAS), unit coordinate

control system (CCS), boiler furnace safeguard supervision system (FSSS), auxiliary sequential control system(SCS), turbine digital electro hydraulic control system (DEH), turbine bypass control system (BPCS ), Micro

electro-hydraulic control system(MEH), turbine supervision instrument(TSI), deashing and deslagging control

system, sootblowing control system, water treatment control system, and so on.

4. 1 Classification, purpose and task distribution of interlock protection


9/91


source to protect signals. For example, the methods of water feeding and water drain shall be adopted to

protect the boi ler stea m drum water level, and the simulation method of shortening signals is prohib ited;

field water feeding shall be adopted for protection of HP heater water level; heating, pressurizing, waterinjection, water discharge and oil drainage shall be adopted to protect the oil pump stopped due to low

pressure of steam turbine lubricat ing oil. When it is difficult to adopt phys ical test methods on site, the test

conditions of measuring equipment can be simulated on site only after the measuring equipment is

precisely cal ibra ted.

For switching signals passing through DCS transformed by analog value, when it is difficult to adopt

phys ical test methods on site, it shall, in principle, be simulated by signal generator around the on-site

transducers. If it is still difficult, it can be simulated according to the following means: adding analog

signals to electric room or engineer station and inspecting through OPR the action status of switching value

and the set value of the corresponding analog value.

The switching signals sent directly by the on-site signal switches can be simulated by shortening the

on-site signal switches.

Transmission Test

Remotely manual breaking-closing operation of test equipment shall be finished (through OPR) and

confirmed before the test.

For transmission test of electrical equipment of 6kV, the switch shall be positioned at test.

For transmission test of electrical equipment of 380V, if the switches are arranged with test position,

they shall be positioned at test, otherwise they shall be positioned at work to put equipment into


10/91


3) The startup condition without prohibition shall be checked through OPR.

4)The test equipment shall be put into service as required by operating personnel.

5) The interlock protection signals shall be simulated as required by thermal workers; the signals shall besent by local test devices, if any.

6) For the same equipment, at least one transmission test to the primary elements such as electric switches

shall be conducted; protection of other equipment can be finished by inspecting the relevant protection

action signals shown on OPR and judged according to the printed record.

7) After finishing one protection signal simulation test, the next signal simulation test cannot be continued

until the signal is timely restored and the signal on OPR and in printed record is confirmed.

Interlock and Switch Test of Equipment

1) If the equipment involved in the test is required to be in actual running status, the inspection prior to the

test shall be performed according to the relevant requirements for normal startup and stop.

2) The main equipment shall be put into service through OPR as required and the standby equipment shall be

confirmed to be in normal standby status.

3) The equipment interlock shall be switched to automatic mode through OPR.

4) The main operation equipment shall be out of service, the self-starting condition of standby equipment

shall be inspected, and the flashed yellow light at the control window of OPR operation equipment and the

alarm condition of the luminescent letters shall be checked.

5) The simulation of thermal interlock signals and the self-starting examination of standby equipment shall

be carr ied out by thermal workers.


11/91


Chapter 2 Distributed Control Systems (DCS)

Distributed control system is total distributed control system based on microprocessor. It is known as total

distributed control system, and also known as distributed computer control system. In its early stage,

distributed control system is chiefly to achieve distributed control; therefore, it is called distributed control

system (DCS for short) by foreign countries. Its main features are centralized management and distributed

control.

2.1 Hardware Structure of DCS

. The Layer Structure of DCS

According to longitudinal distribution, DCS structure can be divided into four classes with typical

functions, namely, process control class, process management class, production management class and

administration & management class. Please refer to the following figures.


12/91


maintenance.

3. Production Management Class

The management computer at this class will programme product structure & scale for each unit according

to user's order, inventory situation and energy conditions. Besides, it will optimize control, dispatch production

plans and coordinate various departments.

4. Administration and Management Class

Located in the highest layer among the plant automation system, administration and management class is

responsible for administrating the whole plant, including engineering, economy, business affairs, operating

activities, personnel management, and so on.

Not all the DCS is required of the above four functional layers. For the applicat ion of specific DCS, the

majority DCS of medium and small scale only possesses the first layer and the second layer, with the third

layer rarely applied. The complete four layers will only be applied in control system of large scale.

2.2 The Basic Structure of DCS

As introduced above, the DCS structure can be divided into four classes of function according to

longitudinal distribution. Analyzed from the perspective of system structure, DCS of medium and small scalethat generally possessing the first and the second class of function are generally composed of four basic parts,

i.e., process control unit, operation station, engineer station and communication network. The basic structure

of typical DCS is shown in Figure 2-2.


13/91


power supply, I/O card, communication connecting card and controller. General ly speaking, no CRT display or

operating-keyboard is arranged in process control unit.

Process control unit is connected with operator station and engineer station through network.

The I/O card of process control unit includes analog signal I/O card, switch (or digital) I/O card and pulse

input card.

Several process control units can be arranged according to the number of process variables collected

during production and the number of process control circuit.

2. Operator Station

Operator station is operator workstation that serves as man-machine interface of DCS and as network

nodal points with the function of man-machine interface to handle all operation affairs.

DCS can be arranged with one or more operator stations. Each operator station serves as a station (or

nodal point) of communication networks. Operator stations shall be connected with engineer stations and

process control units through networks.

Operator station consists of one mainframe, one or more CRT display, one set of operating-keyboard,

printing equipment and storage device.

3. Engineer StationEngineer station is the most important equipment for DCS development & debugging and interface

maintenance. It is tool-like equipment based on personal computer. Meanwhile, it is also one of the important

nodal points of DCS internal communication networks and is capable of directly or remotely visiting all nodal

points of the DCS.

Engineer station serves as network nodal points for DCS off-line allocation and configuration and on-line

supervision, control and maintenance. It will provide the DCS with tool software for configuration and


14/91


Chapter 3 Furnace Safeguard Supervision System (FSSS)

3.1 The System Composition of FSSS

FSSS control logic can be classified into common control logic, fuel control logic and coal-fired control

logic.

Common control logic includes the entire boiler protection, i.e. oil leakage test, furnace purge, main fuel

tripping (MFT), oil fuel tripping (OFT), first-out cause memory, ignition condition and RB, etc.

Common control logic also includes control of utility devices such as fire detector cooling fan and sealingfan.

Fuel control logic includes switch control and layered switch control of oil burners.

3.2 Main Functions

Burner management system (BMS) is designed to control the start-up, operation and cutting of fuel

burning equipment and to ensure safe operat ion of boilers by providing interlock control and sequence control,


15/91


Common logic refers to overall protection of furnace combustion such as oil leakage test, furnace purge,

main fuel tripping (MFT) & oil fuel tripping (OFT), first-out cause memory, ignition condition and RB.

2.1.1 Main Fuel Tripping (MFT) (P10 FS031)

Tripping conditions:

1. Air preheater completely stopped (no running signal) (60S delay) (P11 FS032)

2. FDF completely tripped (without delay) (P13 FS034)

3. IDF completely tripped (without delay) (P13 FS034)

4. Furnace pressure is HH (2/3 delay 0s) (P12 FS033)

5. Furnace pressure is LL (2/3 delay 0s) (P12 FS033)

6. Operator manual emergency shutdown (2 push-buttons) (P16 FS037)

7. The loss of fire detection cooling air (2/3 switch, 1s delay) (P16 FS037)

8. Total boiler airflow is too low (total airflow 30%, without delay)(P11

FS032)

9. The total loss of fuel (P14 FS035)

(All oil angle valves shall be closed or oil inlet fast valve shall be completely closed), (fuel memory has

been put into service) and (a ll mills are out of service)10. The whole furnace is flameout (any mill is running; no 3/4 coal fire detection for any coal layer; and

no 3/4 oil angle of any oil layer has been put into service.) (P15 FS036)

11. All PAF are stopped and mills of for any layer have been put into operation (P13 FS034)

12. All feed pumps are stopped (no feedback from any feed pumps, 2s delay) (P17 FS038)

13. Steam turbine tripping (when load is more than 25%) (2s delay) is r equired to sample signal from DEH.

(P17 FS038)


16/91


3.1.2 Furnace Ignition and Purge (P1 FS010)

Purge conditions:

1. No condition exists for MFT.

2. No flame in furnace.

3. At least one FDF and one IDF are running.

4. The drum water level is normal.

5. Air preheaters are running.

6. All PAF are stopped.

7. The fast valve of fuel oil has been closed.

8. All oil angle valves of oil burners are closed.

9. All mills and coal feeders are stopped.

10. Total airflow is more than 25%.

11. Oil leakage test are finished (or bypass arranged).

12. Fire detection cooling air is normal (the 3 LL signals will not be sent).

When conditions are met, it shall be turned to purge position: open the secondary air damper to purge

position, c lose SOFA damper, set burners in hor izontal position and switch the secondary air damper to manualmode when the air damper reaches its largest open degree.

When all purge conditions are met, press the button of start purge to send purge position instruction.

Start 5-minute timing when purge position are met. During these 5 minutes, if MFT occurs, it will be

considered as interrupted purge, and the timing shall be returned to zero. If no MFT occurs, the purge will be

finished after 5 minutes, and MFT will automatically reset.

3.1.3 Oil Leakage Test (PS FS021)


17/91


2. Primary air pressure is normal (with signal from MCS).

3. Boiler air flow is more than 25%.

3.2.3.2 Oil System Ignition Permits (P48 FS099)

1. No MFT/OFT

2. The fast valve of oil supply has been opened.

3. Oil pressure is normal.

4. Pressure at the outlet of cooling fan is not low.

5. Airflow is more than 30% and purge is successful with 10M delay or all branch oil valves are not completely

closed.

3.2.3.3 The permissive ignition conditions for mills A-F

1. Ignition permission for mill A

Mill B has been put into operation and boiler load is more than 30%, or oil layer AB has been put into

operation.

2. Ignition permission for mill B

Mill A or C has been put into operation and boiler load is more than 30%, or mill C and oil layer BC or AB

have been put into operation, or plasma has been put into service and mill A feeds more than 50%.

3. Ignition permission for mill C

Mill B d il l AB h b i i ill B D h b i i d b il


18/91


l Pulse of failed oil leakage test.3.2.4.2 Motorized Valves for Return Oil (P52 FS103)

Open permit:

l All ignition oil angle valves are closed.Interlock close:

l MFT/OFT pulse.l The pressure in main oil pipe is abnormal (with 2S delay).l Pulse of failed oil leakage test.l Leakage test has been closed.

3.2.4.3 Motorized Valves for Supply of Fuel Oil (P56 FS107)

Open permit:

l No MFT/OFT.Interlock close:

l MFT/OFT pulse.l Pulse of failed oil leakage test.

3.2.4.4 Oil Fuel Trip (OFT) (P50 FS101)

OFT conditions:

l MFT


19/91


Stop permit: 1 remains

Interlock start:

l Interlock start air fan A when interlock has been put into service and air fan B is out of service.Interlock stop:

l Any axle temperature is more than 75 (alarm only )l The two PAF are stopped with 15S delay.

3.2.6.1 Sealing fan outlet isolating damper (P25 FS052)

Open permit: 1 remains

Stop permit: 1 remains

Interlock open:

l Interlock has been put into service and the air fan at this side is in use with 2S delay.Interlock close:

l Interlock has been put into service and the air fan at this side is out of service.3.3 Oil System Logic

3.3.1 Ignition Permit for Oil Angle (P62 FSAB11)

--as oil angle program-controlled start-up and oil angle valve manual open permit, 1 shall be remained

during ignition.

l Oil system ignition conditions are met.l The power supply for ignition cabinet is normal (P65 FSAB14).l Ignition cabinet is under program control (P65 FSAB14).l N i i i f il


20/91


Ignition(30S at most)

(Ignition begun and purge valves closed)

Open oil angle valves

l Oil angle program-controlled stop:* Program-controlled stop permit: no conditions for oil angle tripping (refers to Item 3.2.2)

* The process for program-controlled stop:

Close oil angle valves

(All oil angle valves closed and oil guns inserted completely)

Insert ignition guns

(All ignition guns inserted completely)(Ignition guns inserted/oil angle valves closed/oil guns inserted)

Ignition (30S at most) Open purge valves

(After 60S) (after 60S and oil angle valves closed)

Remove oil guns Close purge valves

3.3.4 Program-Controlled Start/Stop for Oil Layer: (P61 FSAB01)

l Oil layer program-controlled start:* The process for program-controlled start: e.g. firstly, to start angle 1 and 3 through 2S pulse program control;

and 30S later, to start angle 2 and 4 through 2S pulse program control.

l Oil layer program-controlled stop:* The process for program-controlled stop: e.g. firstly, to stop angle 1 and 3 through 2S pulse program control;

and 30S later, to stop angle 2 and 4 through 2S pulse program control.

3.4 Coal System Logic

3.4.1 Permissive Conditions for Mill Startup (P190 FSA10)


21/91


7. All the mill outlet valves are closed (the mill is running and 3/4 of the outlet valves are closed, with

feedback)

8. The coal feeder is stopped with 900S delay.

9. RUNBACK (Applied only to mill)

3.4.3.1 The Oil Pump Motor of Mill Lubrication Station (P215 FSA36)

1. Start permit: the oil temperature in oil tank is more than 15, the liquid level in oil tank of mill lubrication

station is not low, and the signal of remote operation of lubrication station exists.

2. Stop permit: 1 remains

3. Interlock start: the outlet pressure of lube oil pump of the mill is low, with 2S delay.

4. Interlock stop: none

3.4.3.2 Heaters in the Lubrication Station of the Mill (P216 FSA37)

1. Start permit: the oil temperature in oil tank is less than 35 and the liquid level in oil tank of mill

lubrication station is not low.


3. Interlock start: none

4. Interlock stop: the oil temperature in oil tank is more than 40 .

3.4.3.3 Heating belt in the Lubrication Station of the Mill (P217 FSA38)

1. Start permit: 1 remains


3. Interlock start: the outlet temperature of mill lube oil pump is less than 45.

4. Interlock stop: the outlet temperature of mill lube oil pump is more than 49 .

3.4.4 Fast Air Dampers at the Inlet of the Mill (P194 FSA14)


22/91





4. Interlock stop: the mill is stopped with 3S delay or the coal layer has tripped.

3.4.9 Pulverized Coal Cut-off Valves at the Outlet of the Mill (P204 FSA24)




4. Interlock stop: the mill is stopped with 3S delay or the coal layer has tripped.

3.4.10 Fire Control Steam Valves of the Mill (P218 FSA39) (Manual operation is proposed.)



3. Interlock start: the outlet temperature of the coal pulverizer separator is more than 120 or the coal layer

has tripped or the CO content at the outlet of the coal pulverizer is high.

4. Interlock stop: it shall be with 3M delay if there is no instruction for opening.

3.5.1 Coal Feeder Logic (P231 FSA52)1. Start permit: (P230 FSA51)

l All conditions for mill start permit are met.l The mills are running.l The outlet valves of coal feeders have been opened.l Coal feeders are remotely controlled with no alarm.l No over-temperature exists inside coal feeders.


23/91


damper of the mill is manually stopped and the mill has been stopped.

3.5.5 The Motorized Valves for Emergency Coal Discharging Pipes of the Coal Feeder (P236 FSA57)




4. Interlock stop: the coal feeder is stopped with 3S delay or the coal layer has tripped.

Chapter 4 MCS Control

4.1 Coordinated Control of Boiler-Turbine

1. Working Mode:

Generally speaking, the main coordinate control system has 4 types of operation modes, i.e., the basic mode

(manual), boiler follow, turbine follow and coordinate control system. Besides, there are also three auxiliary

control modes such as ADS remote control mode, constant pressure control mode and sliding pressure control

mode.


24/91


1) When both the turbine system and the boiler combustion system are under normal condition, and when the

turbine main control and the boiler main control can be switched to automatic mode, it can operate under

CCS.

2) Under CCS, the turbine main control switched to manual mode as a result of manual interlock will switch the

operating mode to BF.

3) Under CCS, the boiler main control switched to manual mode as a result of manual interlock will switch the

operating mode to TF.

4) Under BF, the boiler main control switched to manual mode as a result of manual interlock will switch the

operating mode to the basic mode.

5) Under TF, the turbine main control switched to manual mode as a result of manual interlock will switch the

operating mode to the basic mode.

6) The switch from the basic mode to TF mode or BF mode and then to CCS is to be achieved by switching the

turbine main control and/or boiler main control to automatic mode when switching conditions are met and

when the turbine and/or boiler system is under normal condition.

3. The Set Value of Boiler Load

The load can be set through network regulation ADS and through the unit itself.

The main control system shall be able to adjust the units output according to the actual capacity of the main

auxiliary unit. When partial failure occurs during the unit operation or when load demand exceeds the actual


25/91


through the function generator and the opening degree of the turbine governing valve. Meanwhile, the set value of

the main steam pressure is limited by its maximum value.

5. Constant pressure/slide pressure operating mode

Selecting slide pressure: enter slide pressure mode upon manual request under CCS. The slide pressure mode can

only be used under CCS or boiler follow modes.

Quit slide pressure: manual request or

Enter basic mode or

RUNBACK state or

Start bypass or

Enter turbine follow mode or

The load is over 85%

Under slide pressure mode, the valve opening is fixed with 10% regulating range.

The manual request, constant pressure operation and the deviation of the main steam pressure set value from

the target value will result in the climbing of the main steam pressure set value.

The climbing of the main steam pressure set value shall be maintained:

Manual request or

Slide pressure operation or

The main steam pressure set value does not deviate from the target value or


26/91


ADS remote control method can be devoted.

4.2 Furnace Draft Control

(1) The feedback signal is taken through the averaging of the two furnace pressures on side A, the averaging

of the two pressures on side B and then the averaging the side A and side B.

(2) When the deviation between the actual furnace draft and the set value is oversize, modify the control

deviation additionally, enlarge the deviation, accelerate the actions of the actuator and adjust the deviation to the

normal range rapidly.

(3) The blow-down command is used as feedforward signal. And the feedforward effect can not be too big

generally.

(4) The lock increase, lock decrease, increase priority and decrease priority operations are set in control

circuit.

(5) When the furnace pressure is at Level-one Low, the rising-forbidden signal is formed to restrict the further

opening of the induced draft fan damper, and it can only be turned down; meanwhile, lead the Level-one Low signal

of the furnace pressure to the forced draft fan system, lock the turning down of the forced draft fan rotor blade, and

it can only be turned up. Turn down the induced draft fan damper compulsorily on the SCS strong decrease signal.

(6) When the furnace pressure is at Level-one High, the declining-forbidden signal is formed to restrict the


27/91


4.3 Other Controls on Furnace Side

I Furnace oxygen control

The average value of the flue gas oxygen content at the entrances of #A and #B air pre-heaters is taken as the

attribute of the flue gas oxygen content in the furnace. The oxygen fixed value is the function of the set load

demand and obeys the principle of low load high oxygen content and high load low oxygen content. The operators

can slightly adjust the oxygen fixed value through adjusting the bias of the oxygen content set.

The output of the oxygen regulator is a fine coefficient between 0.85~1.15, which is sent to front/rear wall fire

air control loop and the secondary air control loop respectively to modify the air flow set value so as to maintain the

oxygen content in the furnace within a rational range.

II Secondary air pressure control

Adjust the secondary air connecting main pressure through the rotor blades of the #1 and #2 forced draft fans,

the secondary air pressure is regarded as the regulated variable of the control loop, the fixed value of the secondary

air pressure is the function of the boiler master, and the operators can slightly adjust the fixed value through the bias.

When the loop is operated manually, calculate the bias automatically to make the fixed value track the regulated

variable so as to realize the undisturbed switch between the manual and automatic.

III Over-fired air

(1) The fire air control is divided into front wall fire air control and rear wall fire air control. The fire air is

sent into the upper parts of front and rear walls so as to reduce the great amount of NOx generated by the high


28/91


make the load demand decrease slowly.

V Fuel control

(1) Calculation of total fuel quantitySummarize the set coal feeding signals and fuel flow signals of the coal mills respectively together.

(2) The fuel command is regarded as the set value of the coal feeder main controller after the dynamic

modification.

(3) The coal feeder main controller output is sent to the M/A stations of the coal feeders through the

balancing algorithm.

(4) Turn down the coal feeder rotating speed compulsorily during MFT.

(5) When the coal feeder main controller instructions have achieved the maximum and the fuel volume is

much less than the set value, the RUNDOWN signal will be generated by the logic loop and sent to LDC load

demand loop to make the load demand decrease slowly.

(6) The coal feeders are operated manually, and the bad quality of any coal transducers, big deviation between

the progress volume and set value of the coal feeder main regulator, manual operation of the forced draft fan and

MFT will all result in the manual switching signals of the coal feeder main controller. The outage of the coal mills

corresponding to the coal feeders or the manual operation of the hot air damper of the coal mills or the manual

operation of the cold air damper of the coal mills or MFT or the compulsory signals sent by FSSS will all result in

the switching to the manual operation of the coal feeder M/A stations.


29/91


measuring points. The purpose to select the biggest is to avoid the temperature excess of the powder

temperature at the exit of the mill.

(3) During the regular operation of the coal pulverizing system, the set value of the powder temperature is setby the operators; during the startup/stop of the milling, the powder temperature fixed value is switched to

the temperature fixed value during the startup/stop of the milling smoothly through the rate limiting

module.

3. Secondary air flow control(1) The secondary air set value of the mill is obtained through the total air flow fixed value of the mill

detracting the primary air flow fixed value of the mill. After the startup of the coal feeder, the secondary air

flow fixed value of the mill is given after the limitation of the rate limiter and the modification of the

oxygen fine coefficient, and it shall be no less than the minimum limit value of the secondary air flow.

(2) The total secondary air flow is obtained through the summation of the secondary air flows on right and leftsides after the calibration of the related secondary air flow temperature.

(3) When the secondary air dampers laterally are operated manually, the regulator tracks the average value ofthe damper demands on both sides, at the same time, the damper output loop on each side memorizes the

deviation between the output of the side and the regulator output in order to guarantee the no disturbance

during the auto on of the damper on each side. When the dampers on both sides are put in the automatic

state, adjust the lateral deviation manually when the total output is guaranteed to be the same so as to make


30/91


main control instructions and boiler design parameters, and the design enthalpy gain of unit working substance

is obtained by the subtraction of the two. The design steam flow and the desuperheating spray flow under

related boiler load are calculated according to the boiler main control instructions and boiler design parameters,

and the design feed water flow demand is obtained by the subtraction of the two. The arithmetic product of the

design enthalpy gain of unit working substance and the design feed water flow demand is the design total

enthalpy gain. The above calculations shall consider the delay time of heat storage.

The heat amount absorbed by the metal parts is calculated by the saturation temperature change rate

multiplying the heat capacity of the metal quality in water wall tube, and the design valid enthalpy gain is

obtained through the design total enthalpy gain subtracting the heat amount absorbed by the metal parts.

(2) Calculation of enthalpy gain in unit working substanceThe design enthalpy gain of unit working substance at the exit of the separator is calculated according to

the boiler main control instructions and boiler design parameters, and considering the increase or decrease of

the steam enthalpy at the exit of the separator required by primary desuperheater, the steam enthalpy fixedvalue at the exit of the separator is obtained through T controller. The set value ofT controller is the

temperature before the primary desuperheater calculated according to the temperature at the exit of the primary

desuperheater and the design temperature drop (the principle is similar to the generation of the set value of the

main loop of the primary desuperheater), the measured value is the actual temperature before the primary

desuperheater, and if the set value is bigger than the actual measured value, the temperature before the primary


31/91


2. Control on feed water flowDuring the low load, adjust the opening of the feed startup regulating valve to control the feed water flow

and adjust the rotating speed of the electric feed water pump so as to maintain the pressure difference on both

ends of the starting valve at a fixed value (around 0.5~0.9MPa). When the feed startup regulating valve is

opened to more than 75% and the load exceeds the regulated load, the valve is switched to the main feed water

progressively, and after the completion of the switch, the feed water flow is controlled through adjusting the

rotating speed of the electric feed water pump.

During the regular operation, the feed water flow is controlled through controlling the rotating speed of the

two steam feed water pumps with the electric feed water pump as standby, and the scoop is opened to the trace

bit.

3. Control on recirculating valve of the feed water pumpThe recycle valve control of the feed water pump guarantees that the inlet flow of the feed water pump is no

lower than the allowed minimum flow so as to avoid the cavitation. The fixed value of the minimum flow is

obtained from the characteristics curve of the feed water pump. Under certain rotating speed of the feed water pump,

the allowable minimum inlet flow is corresponded, and the operating safety of the feed water pump is enhanced

with certain forward bias. The two flow measuring points after the means algorithm are adopted as the regulated

variable of the control loop.


32/91


temperature at the exit of secondary desuperheater is adopt in the control loop to analog the temperature alternation

process from the exit of the secondary desuperheater to the exit of the final stage superheater through three-order

inertial element (inertia time constant is of the boiler load).

(2) Boiler load alternationThe boiler load feedforward signal is a restricted signal with differentiated pulse and proper proportion. More

steam is generated for the increase of the load and more cooling is required, and the temperature fixed value at the

exit of the desuperheater is reduced through the load feedforward signal so as to increase the spray volume.

(3)Influence of the temperature alternations at the exit of secondary desuperheater on the temperature at the

exit of final stage superheater

Due to the alternations of the steam enthalpy and specific heat caused by the increase of the operation pressure,

a rather small change is needed on the entrance temperature of the final stage superheater so as to give a same

temperature alternation on the exit of final stage superheater. Utilizing such principle, modify the temperature

deviation at the exit of final stage superheater according to the exit pressure of the final stage superheater andconvert it to the temperature variation at the exit of the desuperheater.

(4) Saturation temperature restrictionCalculate the exit saturation temperature of the final stage superheater according to the exit pressure of the

final stage superheater and add a margin relating to the exit pressure of the final stage superheater as the minimum

limit value of the temperature at the exit of secondary desuperheater.


33/91


(2) The adjusting principle of the reheated steam temperature is rough adjustment for flue gas damper and slight

adjustment for spray regulation. The adjusting dead band is set in the flue gas damper adjustment.

(3) In order to guarantee that the reheated steam temperature has certain degree of superheat, the set value of the

secondary regulator is formed through selecting the higher one among the output of the main regulator in the

spray adjustment and the reheated temperature which is certain higher than the saturation temperature.

(4) The total air flow and the main steam flow are introduced as feedforward signals.

(5) The commands of MFT, turbine trip, low load, generator failure and the spray valve position are small

enough to form the commands to shutdown the spray isolation valve.

(6) The commands of MFT, turbine trip, low load, shutdown of spray isolation valve and spray valve position

are small enough to form the commands to turn down the spray valve compulsorily.

II The deaerator Pressure Control1 The deaerator pressure control1 At the initial stage of unit startup, the steam for the deaerator is supplied by the auxiliary

steam system while the PCV (pressure control valve) is keeping the deaerator running under fixed

pressure. When the unit loads rise, the PCV will be completely closed after switching to the

four-pumping steam supply system. And the deaerator will run under sliding pressure. While the

deaerator is running under fixed pressure, the setting value of the deaerator pressure is always at Pmin. If

the deaerator pressure at the initial stage is lower than Pmin which is set as the minimum allowable


34/91


2 The Feedwater flow rate is regarded as the feed-forward signal of the deaerator water level three-element

regulation. Condensate flow rate will be regarded as the process quantity of the secondary three-element

regulator.

3 The deaerator auxiliary water valve will be forced closing when the deaerator water level is high.

4 Both the deviations of regulator PV and SP and the position deviations of regulating valve will make the

M/A station of the regulator switch to the manual operation.

2. Deaerator overflowing water discharge controlThis belongs to single-loop regulation. The deaerator water level is controlled not to be too high by regulating

the deaerator overflowing water discharge valve.

IV The Water Level Control of HP (high-pressure) Feedwater Heater

1 The setting value is set manually.

2 During the normal running process, the water level of HP feedwater heater is controlled by regulating the

jaw opening of the water level control valve for HP feedwater heater. When the water level of HP feedwater

heater is too high, it will be controlled by regulating the jaw opening of the emergency water discharge

valve for HP feedwater heater at the same time. When the control loop is under the manual operation, the

setting value of the water level will follow the actual level. After the control loop switches to the automatic

operation, it can be set by the operator. The regulator setting value of the emergency water discharge valve

for HP feedwater heater is higher than the setting value of the normal water level.


35/91


VI The Condensate Water System

1. The hot well water level control of the steam condenserThe hot well water level of the steam condenser B is controlled by controlling the two parallel pneumatic

control valves (No.1 feedwater control valve and No.2 feedwater control valve). The hot well water level of

the steam condenser A doesnt need to be considered.

2. The entrance control valve of the condensate storage water tank, it is controlled by open-loop.3. The water level control of the condensate water storage tank

The water level of the supplementary condensate water tank is controlled by regulating the control valve on the

feeding process from water treatment to supplementary water tank. This belongs to single-loop regulation.

There are two control valves, each of which has its own regulator.

4 The minimum flow control of the condensate waterThe minimum flow control of the condensate water is controlled by regulating the recirculating flow control

valve of the condensate water. This belongs to single-loop regulation.

5 The seal water pressure control of the condensate pumpThe seal water pressure of the condensate pump is controlled by regulating the seal water control valve of the

condensate water. This belongs to single-loop regulation.


36/91


Chapter 5 SCS Control

Functions of SCS (sequence control section): It contains the device level operations. It has the protection and

interlocking functions. The operator can make a single operation to each of all the devices through a CRT so that

each device can be started or stopped (opened or shut) singly. When there is failure situation, the device will bestarted or stopped (opened or shut) automatically. Interlocking refers to the linkage among several devices.

The operations without any special instructions should be manually operated by the operator according to the

specific cases.

Both the permissive conditions and all the conditions should be realized simultaneously. But either the

interlocking conditions or all the conditions being realized is available. After sending the instructions in every step

of the sequence control, the instruction in the next step will not be sent until the feedback signal in the last step

arrives at regular intervals, or else the sequence control will fail.

5.1 Boiler breathing air system

Boiler breathing air system Control logicIncluding air preheater, suction fan, blower, a blower and related


37/91


(3) PDF A has stopped

controlled step-by-step sequence

Step one: close air preheater A gas import valve

Step two: close air preheater A primary air and secondary air exports tailgate

Step three: Stop air preheater A main motor

3) IDF A group voted to use sequential control logic is as follows: (A / B side of the same)


Step one: Start selected # 1, # 2 cooling fans

Step two: Close Electrostatic precipitator A export gas baffle

Open IDF A exports tailgate

Purchase Induced Draft Fan A guide vane for the 0%

Step three: start Induced Draft Fan

Step four: Open electrostatic precipitator A export gas baffle


38/91


Step Two: Stop FDF A

Step Three: Close FDF A exports tailgate

7) PDF A group voted to use sequential control logic is as follows: (A / B side of the same)


Step one: Start a fan A petrol filling sta tions

Step two: open air preheater exports A primary air baffle;

The third step: PDF A customs export baffle;

Purchase PDF A guide vane for the 0%

Step four: Start PDF A

Step five: Open PDF A export baffle

8) Primary Fan A group sequential control logic is as follows: (A / B side of the same)


Step one: Purchase PDF A guide vane for the 0%

Step two: Stop PDF A


39/91


(10) No FDF A motor bearing temperature high

(11) No FDF A motor coil temperature high

(12) FDF A in the far-controlled manner

(13)No electrical failure on FDF A

Start conditions:

(1) FDF A group voted to use sequential control;

(1) FDF A group voted to stop sequential control;

Trip conditions:

(1) Air Preheater A stopped, and FDF A runs;

(2) IDF A stopped, and FDF A running;

(3) Any bearings vibration of FDF is HH, and then 10 seconds delay;

(4) Any bearings temperature of FDFs motor is HH;

(5) Any coils temperature of FDFs motor is HH;

(6) Any bearings temperature of FDF is HH;

(7) FDF A stalls;

(8) FDF A has running for 60 seconds, and outlet damper is closed;


40/91


(2) Level of oil tank is not low;

(3) No operation inhibit for heater of FDF A;

Interlock start permit (interlock in use)

(1) Temperature of oil tank is L;

(2) Oil pump 1 or 2 of FDF A is running;

Interlock stop permit (interlock in use)

(1) Temperature of oil tank is HH;

4) No.1 oil pump of FDF A:

Start permit:

(2) Level of oil tank is not low;

(2) Oil station is remote control;

(3) No operation inhibits;

Interlock start:

(1) Interlock of oil pump is in use, and FDF A is running, and oil stations pressure is L;

(2) Interlock of oil pump is in use, and FDF A is running, and No.2 oil pump is failed;

(3) Choose pump A, and sequence start command is on;


41/91


Interlock open:

(1) Both FDF A and B are stopped;

Interlock close:

(1) FDF B is running and Air preheater A is stopped;

(2) FDF A is running and Air preheater B is stopped;

(3) FDF A has stopped for 65 seconds, outlet damper and inlet vane are closed, and FDF B is running;

(4) FDF B has stopped for 65 seconds, outlet damper and inlet vane are closed, and FDF A is running;

7) ID FAN A

Start permit:

(1) Cooling Fan A or B is running

(2) No interlock stop of ID Fan A

(3) Static vane of IDF A is closed, and outlet damper is open ,and inlet damper is closed, and IDF A is

stopped

(4) Air preheater A is running ,and inlet damper of Air preheater A is open

(5) No IDF A bearing temperature high

(6) No motor bearing temperature high

(7) No coil of motor bearing temperature high


42/91


(9) All IDFs are running, but FDF A is stopped, 1 second delay;

(10) Both FDF A and B are stopped;

(11) IDF A stall, and 10 seconds delay;

(12) No operation inhibits, no electric fault, remote control;

Start permit:

(1) IDF A group voted to use sequential control;

Stop permit:

(1) IDF A group voted to stop sequential control;

8) Outlet damper of Cottrell A:

Interlock open:

(1) IDF A is running, and 30 seconds delay;

(2)Both IDF A and B are stopped, and 135 seconds delay;

(3) Command from IDF A sequence start;

Close permit:

(1) IDF A is stopped;

Interlock close:


43/91



tart permit :

(1)Choose No.1, and IDF A group voted to use sequential control;

Interlock start:

(1)Choose No.1, and command form IDF A sequence start;

(2)Interlock button is on, and No.2 cooling fan of IDF A failed;

(3)Interlock button is on, and bearing temperature of IDF A is H;

Stop permit:

(1)IDF A is stopped, or No.2 cooling fan of IDF A is running;

11) No.2 cooling fan of IDF A:

Start permit:


Start permit:

(1)Choose NO.2, and IDF A group voted to use sequential control;

Interlock start:

(1)Choose No.2, and command form IDF A sequence start;


44/91


(3)IDF A is stopped;

(4)PAF A is stopped;

(5)Inlet damper of air preheater A is closed;

Interlock stop:

(1)Pilot motor of air preheater A is running, and 10 seconds delay;

(2)Air preheater has stopped for 10 seconds, when main motor of air preheater A is running;

(3)Steady bearing temperature of air preheater is HH;

(4)Spigot bearing temperature of air preheater is HH;

(5)Air preheater A group voted to stop sequential control;

13) Pilot motor of air preheater A:

Start permit:

(1)Steady and spigot bearing temperature of air preheater A is not H;

(2)Remote control, no operation inhibit, no failed;

(3) Steady and spigot bearing pump are running;

(4) No total failed;

(5) Power of air preheater As pilot motor is on;


45/91


Interlock open:

(1)Both air preheater A and B are stopped, and then 15 seconds delay;

(2)Air preheater A is running;

(3)Command from air preheater A sequence start;

Interlock close:

(1)20 seconds after air prehater has stopped, and one of IDFs is running;

(2)Command from air preheater A sequence stop;

15) Outlet damper of air preheater A:

Interlock open:

(1)Both air preheater A and B is stopped for 15 seconds;

(2)Air prehater A is running;

(3) Command from air preheater A sequence start;

Interlock close:

(1) 5 seconds after IDF A has running, and air preheater is stopped;

16) Secondary damper of air preheater A :

Interlock open:


46/91


Stop permit:

(1) No operation inhibits, remote control, no electric fault;

Interlock start:

(1) Air preheater is running, and spigot bearing temperature is great than 60 degree;

(2) Command from air preheater A sequence start;

Interlock stop:

(1) Spigot bearing temperature is less than 50 degree;

19) PAF A :

Start permit:

(1) IDF A or B is running;

(2) FDF A or B is running;

(3) No protective stop condition of PAF A;

(4) Inlet vane of PAF A is closed, and outlet valve is closed, and PAF A is stopped;

(5) Primary hot-air damper of air preheater A is closed;

(6) No MFT;

(7) No bearing temperature is H, and no motors bearing temperature is H, and no motors coil temperature

is H;


47/91


(1) PAF A is running;

(2) Both PAF A and B are stopped;

(3) Command from PAF A sequence start;

Close permit:

(1) PAF A is stopped;

Interlock close:

(1) Both PAF A and B are stopped, and outlet damper of PAF B is not closed;

(2) Command from PAF A sequence start;

(3) Command from PAF A sequence stop;

21) Oil station of PAF A:

Start permit:

(1) Remote control;

(2) Operation permit;

(3) No fault of oil station;


Interlock start:


48/91


Drain valve 1-4 of rear shaft's ring collecting header (manually operated)

Drain valve 1-2 of recuperative reheater's inlet collecting header (manually operated)

6) Boiler feedwater valve

Interlock open:

(1)Feedwater flow is more than 25%;

Interlock close:

(1)Feedwater flow is not more than 25%;

(2) Front motor-operated valve of boiler bypass feedwater adjustable valve is open;

(3) Rear motor-operated valve of boiler bypass feedwater adjustable valve is open;

7) Rear motor-operated valve of boiler drain valve(manually operated)

8) Front drain valve of boiler feedwater valve (manually operated)

9) Front drain valve of boiler feedwater valve (manually operated)

10) Front motor-operated valve of boiler bypass feedwater adjustable valve (manually operated)

11) Rear motor-operated valve of boiler bypass feedwater adjustable valve (manually operated)

12) Exhaust valve 1/2 for superheater start (manually operated)

(2 open first, and then open 1; 1 close first, and then close2)


49/91


16) B side desuperheating water valve of reheater

Interlock open:

(1) B side desuperheating water adjustable valve of reheater position > 5%;

Interlock close:

(1)Boiler load is less than 20%;

(2)MFT;

(3) B side desuperheating water adjustable valve of reheater position < 5%;

17) Emergency desuperheating water valve of reheater

Interlock open:

(1) Emergency desuperheating water adjustable valve of reheater position > 5%;

Interlock close:


(2)MFT;

(3) Emergency desuperheating water adjustable valve of reheater position < 5%;

18) First desuperheating water valve of superheater


50/91


Interlock close:


(2)MFT;

(3) B side secondary desuperheating water adjustable valve of superheater position < 5%;

21) A side third desuperheating water valve of superheater

Interlock open:

(1) A side third desuperheating water adjustable valve of superheater position > 5%;

Interlock close:


(2)MFT;

(3) A side third desuperheating water adjustable valve of superheater position < 5%;

22) B side third desuperheating water valve of superheater

Interlock open:

(1) B side third desuperheating water adjustable valve of superheater position > 5%;

Interlock close:



51/91


Interlock open:

(1)Command from periodic blowdown valves sequence open;

Close permit:

(1)No.1/2/3/4 periodic blowdown motor-operated valves of front wall are closed;

Interlock close:

(1)No.1/2/3/4 periodic blowdown motor-operated valves of front wall are closed;

(2)Command from periodic blowdown valves sequence close;

29)No.1 periodic blowdown motor-operated valve of front wall (2/3/4/5/6 same as 1)

Open permit:

(1)Main periodic blowdown motor-operated valve of front wall is open

Interlock open:


Interlock close:


30) Main periodic blowdown motor-operated valve of a side wall

Interlock open:


52/91


Close permit:

(1) No.1/2/3/4 periodic blowdown motor-operated valves of rear wall are closed;

Interlock close:

(1) No.1/2/3/4 periodic blowdown motor-operated valves of rear wall are closed;


33)No.1 periodic blowdown motor-operated valve of rear wall (2/3/4/5/6 same as 1)

Open permit:

(1)Main periodic blowdown motor-operated valve of rear wall is open;

Interlock open:


Interlock close:


34) Main periodic blowdown motor-operated valve of b side wall

Interlock open:


CLose permit:


53/91


(3) Close main periodic blowdown motor-operated valve of rear wall, and close No.1/2/3/4/5/6 periodic

blowdown motor-operated valves of a side wall;

(4) Close main periodic blowdown motor-operated valve of a side wall, and close No.1/2/3/4/5/6 periodic

blowdown motor-operated valves of b side wall;

(5) Close main periodic blowdown motor-operated valve of b side wall;

37) The System of Feedwater Pump Unit

Permissive starting conditions of the motor-driven feedwater pump:

(1)The lubricating oil pressure of the motor-driven pump is normal;

(2)The minimum flow recirculating valve position of the motor-driven feedwater pump is higher than ninety

percent;

(3)The liquid level of the deaerator is not lower than value I;

(4)The motor-driven door at the pre-pump entrance of the motor-driven feedwater pump is completely opened;

(5)The hydraulic coupler valve position of the motor-driven feedwater pump is the lowest (lower than thirty

percent) or the motor-driven pump is used under the interlocking operation;

(6)The motor winding temperature of the motor-driven feedwater pump is not high (six points);

(7)The motor bearing temperature of the motor-driven feedwater pump is not high (eighteen points);

(8)The oil temperatures at the lubricating oil cooler exit of the motor-driven feed water pump is high-high;

(9)The oil temperatures at the working oil cooler entrance of the motor-driven feedwater pump is high-high;

(10)The oil temperature at the working oil cooler exit of the motor-driven feedwater pump is not high;

(11)The entrance pressure of the motor-driven feedwater pump is normal (higher than 0.2Mpa in cold state) or


54/91


(6)Whether the temperature of any motor-driven feedwater pump and motor bearing is high-high (eighteen

points);

(7)Whether the oil temperature at the entrance of the motor-driven pumps working oil cooler is high-high.

The auxiliary lubricating oil pump for the hydraulic coupler oil system of the motor-driven feedwater pump

10LAJ10AP003

(1)Manually starting or stopping this oil pump is available.

(2)Under the interlocking operation, if one of the following conditions occurs, this auxiliary oil pump will be

started through the interlocking operation.

The lubricating oil pipe pressure of the motor -driven feedwater pump is lower than 0.15Mpa;

The motor -driven pump is stopped running.(3) In interlocking, the follows can interlock to stop this auxiliary oil pump:

electrical pump operating and electrical driven feed pump providing the lube pipe with a

pressure>0.3MPa (undetermined).

Electrical driven feed pump front inlet electrically operated door 10LAH10AA001

(1) This valve could be opened/closed manually;

(2) Closing this valve is totally forbidden, when electrical driven feed pump in operation.

Electrical driven feed pump outlet electrically operated door 10LAH10AA003


(2) Shutdown electrical pump, interlock to close this door.

Electrical driven feed pump minimum flow recycle valve (magnet valve) 10LAH10AA101


(2) Electrical driven feed pump inlet flow in a lower degree, open the adjusting valve, adjusting could be


55/91


(4) Steam pump fore pump driving end radial bearing temperature in high-high degree;

(5) Steam pump fore pump free end radial bearing temperature in high-high degree.

Steam feed pump A (B) fore pump inlet electrically operated door 10LAB11AA001 (10LAB12AA001)


(2) Fore pump in Operation, closing this valve is strictly forbidden.

Steam feed pump A (B) outlet electrically operated door 10LAB11AA003 (10LAB12AA003)


(2) Steam pumps tripping, interlock to close this door.

Steam feed pump A (B) minimum flow recycle valve (magnet valve) 10LAB11AA101 (10LAB12AA101)(1) This valve could be opened/closed manually;

(2) Steam feed pump inlet flow in low-low degree, adjusting valve shall be opened immediately; adjusting by

the adjusting valve can be conducted 8 seconds after the flow getting right.

Steam feed pump A (B) to rehearter desalt electrically operated door10LAF51AA001 (10LAF52AA001)

(1) This valve could be opened/closed manually;.

38) Small Machine Related System

Feed pump turbine A(B) lube system main oil pump AB 10MAV50AP10110MAV50AP102(10MAV60AP101

10MAV60AP102)

(1) This pump could be started/stopped manually;

(2)Main/Standby mode


56/91


Feed pump turbine A (B) sealing steam pump drain valve 10MAL13AA102 (10MAL14AA102)


(2) When interlocking in operation, small machine tripping or loading is less than 20%; interlocking to open;

(3) When interlocking in operation, loading is more than 20%; interlocking to close;

Feed pump turbine A (B) balance pipe drain valve 10MAL13AA103 (10MAL14AA103)


(2) When interlocking in operation, small machine tripping or loading is less than 20%; interlocking to open;


Feed pump turbine A (B) high pressure cylinder drain valve 10LAC10GC001

(1) This valve could be opened/closed manually;(2) When interlocking in operation, small machine tripping or loading is less than 20%; interlocking to open;


Steam feed pump fore pump thin oil station system10MAL13AA104 (10MAL14AA104)

(1) Conducted by local PLC, remote manual operation function is provided by DCS.

39) Condensate Water System

Condensate pump A (B) starting enabled conditions

(1) Condensater water level in a proper degree;

(3) Condense water pump motor winding temperature is not high (6 points);

(4)Condensate water pump and motor bearing temperature is not high (4 points);

(5) No electrical tripping, no interlocking tripping, no forbidden operation, no local control.

Condensate water pump A (B) protecting tripping conditions

(1) 15 seconds after this pump operated, the outlet door is still closed;


57/91


(2) Pump started, interlock to open outlet valve; pump stopped, interlock to close outlet door.

Condensater normal making up electrically operated door 10LCP70AA001


(2) Pump started, interlock to open outlet valve; pump stopped, interlock to close outlet door.

Condensater accident making up electrically operated door 10LCP40AA130


(2) Accident making up interlocking in operation, condensater water level in low-low degree, interlock to open

valve; water level not in low degree, interlock to close valve.

Condensater water level adjusting valve bypass electrically operated door 10LCP11AA001

(1) This valve could be opened/closed manually;(2) Condensater water level in low degree and the adjusting valve fault, interlock to open valve; condensater

water level restored, interlock to close valve.

Deaerator water level adjusting bypass electrically operated door 10LCA10AA004


(2) Deaerator water level in High II, interlock to close and open prohibited

Condensate water recirculating flow adjusting valve bypass electrically operated door 10LCA42AA001


(2) Condensate water flow in low-low degree or deaerator water level in High II, interlock to open and close

prohibited;

(2) Deaerator water level in not high I, interlock to close.

Feed pump turbine A (B) exhaust steam desalt water electrically operated door 10LCE11AA001 (10LCE11AA002)



58/91


interlock to close.

side A (B)condenser taprogge system 10PAH11GC00110PAH12GC001

(1) This equipment could be started/stopped manually;

Condenser A(B)side secondary strainer 10PAH11GC00110PAH12GC001

(1) This equipment could be started/stopped manually;

Condenser A (B) side circuit water inlet secondary strainer wash water valve10PAH41AA001 (10PAH42AA001)


Condenser A (B) side circuit water inlet electrical valve 10PAH21AA001 (10PAH22AA001)

(1) This valve could be opened/closed manually;.

Condenser A (B) side circuit water outlet electrical valve 10PAH31AA001 (10PAH32AA001)(1) This valve could be opened/closed manually;

Coal mill fire control steam gate 10LBX70AA006


40) Circuit Cooling Water System

Closed circuit cooling water pump A (B) starting enabled conditions

(1) Closed circuit cooling water expansion tank water level not in low degree;

(2) Closed circuit water-pump motor stator coil temperature not in high degree (6 points);

(3) Closed circuit water pump and motor bearing temperature not in high degree (4 points);

(4) No electrical tripping, no interlocking tripping, no restricted operation, no local control;

Closed circuit cooling water pump A (B) protecting tripping conditions

(1) 15 seconds after this pump in operation, outlet is still closed;

(2) Closed circuit cooling water expansion tank water level in low-low degree;


59/91



Closed circuit cooling water heating exchanger A(B)cooling water outlet electrically operated

door10PGA21AA002(10PGA22AA002)


Equipment room cooling water backwater electrically operated door 12 10PGA31AA00210PGA33AA001


Boiler room cooling water backwater main pipe electrically operated door 10PGA50AA001


Steam turbine oil cooler cooling backwater main pipe electrically operated door 10PGA34AA001

(1) This valve could be opened/closed manually;Feed pump turbine lube oil cooler backwater electrically operated door 10PGA31AA001


Sea water booster pump A (B) 10PCC21AP001 (10PCC22AP001)

(1) This pump could be started/stopped manually; when the following conditions fulfilled;

Open

(2) Enabled conditions: any closed circuit cooling water heating exchanger seawater side water passage cleared

and seawater booster pump inlet electrically operated door open;

(3) 15 seconds after this pump in operation, outlet is still closed or inlet electrically operated door is closed,

interlock to stop this pump.

(4) If this pump is in standby position, when operating pump stopped or outlet main pipe s pressure in low

degree, protect interlocking and start standby pump.

Seawater booster pump A (B) inlet electrically operated door 10PCB21AA001 (10PCB22AA001)


60/91


(1) This fan could be started/stopped manually;

(2) If this fan is in standby position, when operating fan in stoppage or gland sealing heater steam side pressure

in high degree, protect interlocking and start standby fan.

(3) Gland steam fan inlet electrically operated door opened, starting fan is permissible; gland steam fan inlet

electrically operated door closed, interlock to close fan.

Gland steam fan A (B) inlet electrically operated door 10LBW20AA001 (10LBW21AA001)


(2) Fan in operation, closing this door is prohibited.

High pressure steam source control station steam inlet electrically operated door 10LBW13AA001

(1) This valve could be opened/closed manually;High pressure steam source control station bypass electrically operated door X0LBW13AA003


Auxiliary steam coming steam source electrically operated door 10LBW10AA001


Reheating cold section steam source electrically operated door 10LBW11AA001


Auxiliary steam source control station steam inlet electrically operated door 10LBW12AA001


Auxiliary steam source control station bypass electrically operated door 10LBW12AA003


Overflow control station bypass electrically operated door 10LBW14AA002



61/91


operated door related.

1,2,3 steam exhausting electrically operated door 10LBQ10AA00110LBQ20AA00110LBQ30AA001

(1) Manually open/close this valve, when the following conditions fulfilled;

(2) When HPH emergency step out, turbine tripping, related HPH water level in high 3 value, any condition

above fulfilled, interlock to close this valve;

(3)Enabled conditions for opening: no condition for interlocking to close;

1,2,3 steam exhausting check valve 10LBQ10AA00210LBQ20AA00210LBQ30AA002


(3) When HPH emergency step out, turbine tripping value, any HPH water level in high 3 value, any of the

conditions above fulfilled ,interlock to close this valve;(4) Set CRT button to general control opening/closing all steam exhausting check valves;

1,2,3 Section steam exhausting electrically operated front drain valve 10LBQ10AA40110LBQ20AA401

10LBQ30AA401


(2) When turbine draining in group, turbine tripping, related steam exhausting electrically operated door closed,

and HPH water level in high 3 value, plant units loading 10% (3 sections are 20% in all) and no condition for

interlocking to close, interlock to close this valve.

1,2,3 section steam exhausting check valve rear drain valve 10LBQ10AA40210LBQ20AA40210LBQ30AA402


(2) When turbine draining in group, turbine tripping, related steam exhausting electrically operated door closed,


62/91


1,2,3 HPH normal drain valve (magnet valve) 10LCH10AA10110LCH20AA10110LCH30AA101


(2) Related previous HPH water level in high 2 value, close the adjusting valve immediately, water level not in

high 2 value for 2 seconds, adjusting valve is adjustable.

1,2,3 HPH dump drain valve 1 (magnet valve) 10LCH10AA10210LCH20AA10210LCH30AA102


(2) HPH water level related in high 2 value, open adjusting valve immediately; water level not in high 2 value

for 2 seconds, adjusting valve is adjustable.

1,2 HPH dump drain valve 2 (magnet valve) 10LCH10AA10310LCH20AA103

(1) This valve could be opened/closed manually;(2) Deaerator water level in high 2 value, close the adjusting valve immediately, water level not in high 2 value

for 2 seconds, adjusting valve is adjustable.

43) LPH Functional Group

LPH protecting

(1) LPH water level in high 3 value, close related sections steam exhausting electrically operated valve, check

valve, open front, rear drain valve, close related LPH inlet valve, outlet valve, open related LPH bypass valve;

(2) LPH water level in high 2 value, open related LPH dump drain valve, close previous LPH normal drain

valve.

5,6 exhausting electrically operated door 10LBS50AA00110LBS60AA001

(1) Manually open/close this valve, when the enabled condition fulfilled.

(2) When turbine tripping or related LPH water level in high 3 value, interlock to close this valve;

(3) Enabled condition for opening: No condition for interlocking to close.


63/91


(3) Enabled condition for opening: no condition for interlocking to close;

No.5 LPH outlet to circuit water backwater pipe electrically operated door 10LCA41AA001


No.8 LPH inlet electrically operated door 10LCA10AA006

(1) Manually open/close this valve, when enabled condition fulfilled;

(2) Any LPH water level of No.7,8 in high III value,

(3) Enabled condition for closing: No.7, 8 bypasses electrically operated door fully opened.

No.7 LPH outlet electrically operated door 10LCA20AA001

(1) Manually open/close this valve, when the enabled condition fulfilled;

(2) Any No.7, 8 LPH water level in high III value, protects interlocking and closes this valve;(3) Enabled condition for closing: No.7, 8 LPH bypass electrically operated door fully opened.

No.7, 8 LPH bypass electrically operated door 10LCA10AA005

(1) Manually open/close this valve, when the enabled condition fulfilled;

(2) Any No.7, 8 LPH water level in high III value, protects interlocking and opens this valve;

(3) Enabled condition for closing: No.7 LPH bypass outlet electrically operated door, No.8 LPH inlet

electrically operated door fully opened.

No.5 ,6, 7, 8 LPH normal drain valve (magnet valve) 10LCJ50AA10110LCJ60AA10110LCJ70AA101

10LCJ80AA101


(2) The related previous LPH water level in high II value, close the adjusting valve immediately; water level

not in high II value for 2 seconds, adjusting valve is adjustable.

No.5, 6, 7, 8 LPH dump drain valve (magnet valve) 10LCJ51AA10110LCJ61AA10110LCJ71AA101


64/91


(4) Set CRT button, be able to control the opening/closing all steam extracting check valve generally.

4 extracting 1 electrically operated door fore drain valve 10LBS40AA401


(2) Turbine draining in group, turbine tripping, 4 extracting 1 electrically operated door closed, deaerator water

level in high 2 value, plant unit loading 20% and no condition for interlocking to open, interlock to

close this valve.

4 extracting 1 check valve 2 rear drain valve 10LBS40AA402


(2) Turbine draining in group, turbine tripping, 4 extracting 1 electrically operated door closed, deaerator waterlevel in high II value, plant units loading 20% and no condition for interlocking to open, interlock to

close this valve.

4 extracting 2 check valve 10LBS41AA001


(2) When turbine tripping, two small machines in full tripping, any condition above fulfilled, interlock to close

this valve;

(4) Set CRT button, be able to control opening/closing steam extracting check valve generally.

4 extracting 2 check valve fore drain valve 10LBS41AA401


(2) When turbine draining in group, turbine tripping, 4 extracting 2 check valve closed, two small machines in

full tripping, plant units loading

7/28/2019 600M.W.Pla

600M.W.Plant C&I course

Documents