Fuel Oil Handling System

2X660MW NCC LimitedPynapuram village , Nellore District Andhra Pradesh

Fuel Oil Handling System

• In thermal power plant with coal fired boiler , the Fuel oil plays a vital role in initial firing of boiler and running it up to 25-30 % of it’s rated capacity.

• The fuel oil is also used as the stabilizing fuel in the pulverized fuel boiler till the coal flame stabilizes in the furnace and for the proper coal burning while the load is reduced in the boiler for shutdown.

Fuel oil system

• The fuel oil system includes the subsystems:

• LDO unloading , storage & forwarding system.• HFO unloading, storage & forwarding system• Steam & condensate system for HFO Storage tank

heating & electrical heat tracing.• Drain oil system• Oil waste water system.

Tank Details HFO Tank LDO Tank

Number of Tanks 2 1

CAPACITY 3000 M³ 500 M³

SIZE Dia-18M,Ht-13.5M Dia-10M,Ht-7.5M

TDS : Dimensional Std Specification Plates : IS2062 E250 BR ASTM A285

Pipes : ASME B 36.10 ASTM A106 GR.B

Structure : IS2062 E250Channels,flats,angles

Valves : 50& Below ASTM A105 (C.S)- Forged fittings Above 50NB ASTM A 216 Gr.WCB – Casting Flanges ANSI B 16.5 ASTM A105Bolts & Nuts IS1367

HFO

• HFO will be used to take up firing upto 30% BMCR for flame stabilization at the startups/ low load operation.

Heavy Fuel Oil Tanks-3000KL

Light Diesel Oil Tank-500KL

LDO• Light diesel oil will be used for initial startup and

lighting up the main boiler up to 10% BMCR and flushing of heavy fuel oil line. LDO will be used for firing of auxiliary boiler upto 10% BMCR.

• Light oil is used as the fuel for the igniter. light oil is also required for warming up oil gun to start up the boiler from the cold condition when steam is not available for heating the heavy fuel oil.

• Due to low viscosity LDO at ambient temperature it does not require heating and atomizing is done by air.

LDO U/N &F/W Pumps Details Type Unloading

Horizontal twin screw pump

Nos 2(1W+1S)Operation ContinuousCapacity 25m³/hrTotal Discharge Pressure

2.0kg/cm²

speed 1450RPMRelief safety valve 3.0Kg/cm²Motor kW 5.5 KWFull load current (amp)

10.46

Connection Delta

Type forwarding

Horizontal twin screw pump

Nos 3(2W+1S)

Operation Continuous

Capacity 25 m³/hr

Total Discharge Pressure

54Kg/cm²

speed 2900RPM

Relief safety valve 55.5kg/cm²

Motor KW 75KW

Full load current (amp)

121

Connection Delta

Unloading Header Area

Pumps• Pumps used are rotary type with single motor and it comes under displacement

pump called Twin screw Horizontal Pump.• Rotary pumps are used for moving of high viscosity fluids.( Grease, Asphalt HFO).• For Unloading and forwarding pumps – Twin screw pump (Horizontal Pumps)• For Drain Pumps – ( Single screw Pump ( Vertical type Pumps).

LDO –U/N F/W

HFO-U/N &F/W Pump Details Type Unloading

Horizontal twin screw pump

Nos 2(1W+1S)

Operation Continuous

Capacity 50 m³/hr

Total Discharge pressure

3.0kg/cm²

speed 1450RPM

Relief safety valve Set pressure

4.0kg/cm²

Motor KW 18.5KW

Full Load current (amp)

33

Connection Delta

Type Forwarding

Horizontal twain screw pump

Nos 3(2W+1S)

Operation Continuous

Capacity 60 m³/hr

Total Discharge pressure

27.5 Kg/cm²

speed 1450RPM

Relief Safety valve set pressure

29.0kg/cm²

Motor KW 75kW

Full Load Current(amp)

123

Connection Delta

HFO – U/N F/W

Pressure Reducing de- superheating system

PRDS-parametersOperating --Design

Steam Inlet Pressure (kg/cm²)

8--14

Steam Outlet Pressure (Kg/cm²)

3.5—4.5

Steam Inlet Temperature(Deg C

350-360

Steam Outlet Temperature(Deg C

155-160

Steam flow rate (kg/hr)

11250

Line Diagram of HFO system

Line Diagram of LDO system

Line Diagram of Steam System

Control Philosphy • The fuel oil ( Both HFO & LDO ) unloading pumps and associated equipment

should be controlled manually by local control panel.• Interlocks for unloading pumps trip (both HFO & LDO) due to suction header stand

pipe level low shell be provide.• When HFO tank level is high , motor operated valve (MOV) provided at the oil inlet

line shall close by sensing high level signal from level switch located at HFO tank to avoid overflow.

• When MOV in both the tanks at the oil inlet are closed, unloading pumps shall trip from high pressure signal from pressure switch loacted on pump discharge line.

• The fuel oil ( both LDO & HFO ) forwarding pumps shall be controlled from DCS . Auto manual operation will be possible for each pump. stand by pump will be started automatically by signal from pressure transmitter during low header pressure of the forwarding pumsp.

• During low level oil in ( Both HFO & ldo ), respective forwarding pump shall trip by getting low level signal from level switch.

Cont..• Drain oil pumps shall operate automatically by high and low level signal

from level switch in the tank.• Differential pressure indicator cum switches across each strainer for high

differential pressure alarms in LCP /DCS.• Fuel oil temperature in HFO tank shall be controlled by modulating the

steam flow in mat coil heater through temperature control valve to maintain oil temperature at desired set point.

• Fuel Oil temperature in HFO heater and suction heater shall be controlled by modulating the steam flow in temperature control valve based up on the temperature transmitter signal at the downstream equipment to maintain oil temperatures at a desired set point.

• Fuel oil forwading pumps discharge pressure shall be controlled through pressure transmitter by a recirculation control valve which shall recirculate oil back to storage tanks.

HeatersTANK HEATER( Suction Heater)

IN LINE HEATER

Nos. 2 3Heat Transfer Area

22.73m² 150.16m²

Shell Diameter 0.3m 0.73mFluid Circulated HFO STEAM HFO STEAMFluid Flow Rate 120m³/hr 1132.5kg/hr 60 m³/hr 5503kg/hrAverage Viscosity(kg.m.hr)

701 173

Temperature (In/Out) ºC 55/65 65/115

Operating Pr. Kg/cm² 1.0 27.5

Heat Exchanged Kcal/hr

Inline Heater

Oil water System

Commissioning

• Objective : A steam blowing and flushing of fuel oil lines.

• To remove debris ,scales and weld splatters and clean the internal surface of oil lines in LDO /HFO system including atomising steam lines.

• Commissioning of FO system and Oil firing• To commission FO system and make it available

for Boiler Light up and operation.

Steam Blowing Activity• Pipe connections to LDO/HFO pumps on suction & discharge side are

dismantled.• The line to be blown is charged slowly with auxiliary steam and warmed

up keeping the drains open( Firstly suction side between tank & Pump suction and then discharge side from pump discharge to ring header.

• After proper charging blow is given for 20-30 minutes.• Steam of pressure of 10-12kg/cm2 and having a super heat of at least

50*C at source used for blowing.• The line is allowed to cool for two hours and then again blown.• Blowing of drains ,vents and instrument tapping point sis done at 5kg/cm2

for 10 minutes each.• Drains / Vents of FO lines are kept open as required during steam blowing

and thereafter for draining of condensate.

Cont..

• After sufficient cooling the piping's are dried with compressed air.

• Blowing medium at exit of the pipe should be visually clean.

• All Lines are then normalized after steam blowing

Steam Blowing of oil lines

Commissioning of the system

• Air Blowing of Piping with Instrument Air

Boiler Light Up of U#1

Thank you

Miscellaneous• Strainers used before Unloading pumps are of type :

Duplex Basket Strainer .• Control Valves:Control valve is an automated valve that

can make precise adjustment to regulate and monitor flow• The most common valve body style used as a control valve

is globe valve• Control valves use signals received from instruments to

automatically make adjustments that regulate the flow• Control valves can perform many functions, typically used

to control flow rate and pressure

Cont..2

• Actuator :Automatic operator is called actuator• It uses external power supply to provide necessary force required to

operate valves• Automatic actuators use: - hydraulic or pneumatic power – to operate valves needing linear or

quarter-turn movements – We used Pneumatic Actuator in Control Valve - electric power – electric motor drives multiple turn movementsSafety Valve :• Used in steam and gas systems• When internal pressure exceeds the setting, valve opens

completely