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FUEL SUPPLY SYSTEM

TRAINING SYSTEM DESCRIPTION (GT-GT04-24A-SD)

Combustion Turbine Plant

March 11, 2003

Combustion Turbine Power Plant Fuel Supply System

CT-GT04-24A-SD

Revision 0 – March 11, 2003 Page 1

PREFACE

This System Description has been designed to assist you in meeting the requirements of Module

(CT-GT04) of the Plant Operator Training Program. It contains information about the

Combustion Turbine Fuel Supply System associated with the GT24A Combustion Turbine. This

includes system purpose, flow path, and details about major system components and operation.

The Operator(s) is/are responsible for learning the information contained in this document. The

Operator(s) is/are also responsible for obtaining any required certifications and making proper

inspections, logging/recording, reporting, minimizing wastewater and excessive emissions.

A separate document, System Operating Procedure (CT-GT04-24A-SOP), covers detailed

operation of the Combustion Turbine GT24A Fuel Supply System.

Employees need to be aware of environmental impacts involved with this system. Improper

operation of this system could cause contamination, excess wastewater and excessive emissions.

Any leak and/or spill that discharges to the floor drains or to State waters must be reported

immediately as outlined in the Spill and Counter Measure Plan.


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FUEL SUPPLY SYSTEM DESCRIPTION

TABLE OF CONTENTS

1.0 Introduction ....................................................................................................................... 4

1.1 Purpose .............................................................................................................................. 4

1.2 Basic System Description .................................................................................................. 4

1.2.1 System Parameters ............................................................................................................ 5

1.3 System Flowpaths .............................................................................................................. 5

2.0 System Major Components ............................................................................................... 8

2.1 Fuel Gas System and Burner Supply Systems .................................................................. 9

2.1.1 Fuel Gas Supply ................................................................................................................ 9

2.1.1 Fuel Gas Building Equipment ......................................................................................... 10

2.1.2 Fuel Gas Control Block ................................................................................................... 11

2.1.2.1 EV Combustor Fuel Gas Supply to Burners ................................................................... 11

2.1.2.2 EV Combustor Fuel Gas Supply to Burners Controls ..................................................... 13

2.1.2.3 SEV Combustor Fuel Gas Supply to Burners ................................................................. 14

2.1.2.4 SEV Combustor Fuel Gas Control .................................................................................. 14

2.2 Fuel Oil System ............................................................................................................... 15

2.2.1 Fuel Oil Block ................................................................................................................. 16

2.2.2 Fuel Oil Control Block .................................................................................................... 19

3.0 System Operation ............................................................................................................ 22

3.1 System Startup ................................................................................................................. 22

3.2 Normal Operation ............................................................................................................ 25

3.3 System Shutdown ............................................................................................................ 27

4.0 References ....................................................................................................................... 29


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List of Figures:

Figure 1 – Fuel Gas Twin Filter Arrangement

Figure 2 – Fuel Gas Control Block

Figure 3 – Fuel Oil Control Block

Figure 4 - Fuel Oil Sump

Figure 5 – Fuel Oil Pump


List of Drawings

Drawing 1 – Fuel Gas System Simplified Diagram

Drawing 2 – Fuel Oil Building Simplified Diagram

Drawing 3 – Fuel Oil Supply Simplified Diagram


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1.0 Introduction

Chapter Objectives:

Describe the purpose of the Fuel Supply System.

1. State, from memory, the purpose of the Fuel Supply System.

2. Draw a simplified Fuel Supply System diagram. Describe the flow path through

the device and how the Fuel Supply System performs its functions.

3. State, from memory, the names and purpose of the major Fuel Supply System

components.

4. List the normal Fuel Supply System operating parameters.

1.1 Purpose

The purpose of the Unit 6 or Unit 7 GT24A Style Fuel Supply System is to supply and control

the pressure and volume of Fuel, (Fuel Gas or No. 2 Diesel) sent to the Combustion Turbine EV

and SEV Combustors.

1.2 Basic System Description

(Refer to Drawing 1 when reading this section

The Fuel Supply System is made up of the Fuel Gas System and the Fuel Oil System.

Fuel Gas is supplied from Texas Eastern and Tennessee Supply lines to the Plant Site.

The Fuel Gas, as it pertains to the GT24A Combustion Turbine, functions as the primary fuel

source for firing the EV and SEV combustors. Additionally the Fuel Gas acts as the fuel supply

to the ignitors and pilot as well.

No. 2 Diesel Fuel supplied to the Combustion Turbine Plant location acts as the secondary fuel

source for firing the EV and SEV Combustors.


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1.2.1 System Parameters

Number Of Fuel Oil Tanks Two (2)

Fuel Oil Tank Capacity Each 1.1 million gallons

Fuel Oil Pump discharge pressure 133 Bar

Minimum Fuel Gas Supply Pressure 650 psi

Twin filter DP (Differential At Which

Fuel Oil Filters Are Swapped) . Eight (8) Bar

Pressure Limiting Valve (Located Downstream

Of The Twin Filter Arrangement Set Pressure) 25 Bar

LP Fuel Oil Pressure Limiting Valve Set Pressure 1.7 Bar

Fuel Oil Sump Level Alarms Greater than 400 mm (and)

Less than 250 mm

1.3 System Flowpaths

(Refer to Drawings 1, 2, and 3 while reading this section.)

Fuel Gas Supply

Fuel Gas, supplied from Texas Eastern and Tennessee Supply lines to the Plant Site, routes

through the associated unit’s Fuel Gas Supply line and to its associated twin filter arrangement

(MBP31 AA001). From the in-service filter, the fuel gas is directed to a tee type piping

arrangement routing to the EV and SEV Combustor Main Shutoff valves.

Main Shutoff Valve MBP31 AA001 routes fuel gas toward the EV Combustor. A header vent

valve take-off, located downstream of the main shutoff valve, is used to evacuate the fuel gas

supply header between the shutoff valve and the EV Combustor Trip/Shutoff Valve (MBP41

AA001). A dirt trap (MBP31 AT001) is located downstream of the main shutoff valve and vent

connection. Fuel Gas within the EV Combustor supply line is directed to trip/shutoff valves for

the EV Combustor Pilot, Ignitor, and to line supplying the EV Combustor. Each line is equipped

with a Trip Shutoff Valve, a throttling valve and a vent valve located between the associated

trip/shutoff valve and throttling valve arrangement. The relief/vent arrangement for each line


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allows gas trapped between the closed Trip and Throttling valves to vent to a location above the

building roof.

Main Shutoff Valve MBP31 AA001 also routes fuel gas to the SEV Combustor. Fuel Gas within

the SEV Combustor supply line is directed to a trip/shutoff valve for the SEV Combustor. This

line is equipped with a Trip Shutoff Valve, a throttling valve and a vent valve located between

the trip/shutoff valve and throttling valve arrangement. A relief/vent arrangement is provided to

allow gas trapped between the closed Trip and Throttling valve to vent to the header it shares

with the EV vent allowing vented gas to flow to a location above the building roof.

Fuel Oil Supply

The Fuel Oil Supply system is the secondary method of firing of the EV and SEV Combustors.

Fuel Oil Supply (located within the Fuel Oil Building, is routed through the Main Fuel Shutoff

Valve (MBN31 AA001). When OPEN, fuel oil passes on to the header supplying the twin filter

arrangement (MBN31 AT001). A low pressure limiting valve (MBN31 DP001) functions to

route excess supply pressure to the Fuel Oil Sump. A fuel oil sump pump (MBN35 AP001)

directs the flow of oil collected within the Fuel Oil Sump to the Fuel Oil Return. A centrifugal

type vent arrangement within the sump allows for vapors within the sump to be vented to

atmosphere, via a connection routing vapors to a location outside of the building.

Fuel oil passing through the in-service Twin-Filter, via ganged three way valves, routes to the

Fuel Oil Pump (MBN31 AP001). The Fuel Oil Pump discharges through a minimum flow valve

(or orifice arrangement) to the Fuel Oil System from fuel pump. The Fuel Oil Pump minimum

flow valve (MBN32 AA001) ensures minimum flow through the fuel oil pump, reducing the

potential for pump cavitation. Fuel oil flowing through the minimum flow valve routes through

a normally open gate type isolation valve and combines with the Sump Pump (MBN35 AP001)

discharge, routing to the fuel oil return piping. The fuel oil building is equipped with a heating

and ventilation system (MBN36 AN001) routing vapors trapped within the building to

atmosphere (outside the confines of the building).


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The Fuel Oil Supply Header routes No. 2 Diesel, pressurized by the pump, to the EV Combustor

Trip Shutoff Valve (MBN40 AA001) and to its flow control valve (MBN41 AA001). A Fuel Oil

Drain Valve (MBN50 AA001) tees from the piping downstream of the trip valve. A Shutoff

valve (MBN42 AA010), also located downstream of the EV Combustor trip valve acts to isolate

flow to the SEV Combustor. Flow to the SEV Combustor is controlled control valve

(MBNAA001). This line is also equipped with a drain valve (MBN52 AA001). Each drain

valve, when OPEN, routes flow to the fuel oil sump.


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2.0 System Major Components

Chapter Objectives:

Describe how the Fuel Supply System Components perform their functions, and how

they interface with other System components.

1. Draw from memory a diagram of the Fuel Supply System showing major

components.

2. State, from memory, the names and purposes of major Fuel Supply System

components.

3. Describe the construction of and flow paths through the major components.

The GT24A Fuel Supply System (as found on Units 6 and 7) consists of the following major

components:

1. Fuel Gas System

Fuel Gas Supply

Fuel Gas Building Equipment

Fuel Gas Control Block

EV Combustor Fuel Gas Supply to Burners

SEV Combustor Fuel Gas Supply to Burners

2. Fuel Oil Supply System

Fuel Oil Block

Fuel Oil Control Block


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Figure 1 – Fuel Gas Twin Filter Arrangement

2.1 Fuel Gas System and Burner Supply Systems

(Refer to Drawing 1 when reading this section.)

The Fuel Gas System delivers the fuel gas supplied by the gas supply system to the EV and SEV

burners at a flow rate corresponding to the power output demanded of the gas turboset and in the

condition required for operation.

2.1.1 Fuel Gas Supply

Fuel Gas for the Units 6 and 7 Combustion Turbines is supplied from Texas Eastern and

Tennessee Supply lines to the Plant Site. Fuel gas supply pressure is 650 psig. The fuel gas is

routed to the unit via a 10-inch line. The fuel gas is filtered via twin filter arrangement (MBP01

AT001). The twin filters, one filter normally in service, allows for the removal of entrained


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debris and moisture from the fuel gas supply. The Twin Filter Arrangement is illustrated on

Figure 1. The inlet and outlet valves of the twin filter arrangement are ganged together,

allowing flow to the filters to be swapped in a single action. Each filter is equipped with a vent

and drain valve arrangement. Differential pressure is measured across each filter and is indicated

locally. Increased differential pressure is indicative of filter cleanliness, indicating the need to

swap to the alternate filter. A differential pressure alarm for each filter is also is provided.

A gas flow integrator is located downstream of the twin filter arrangement. The flow integrator

is used to measure the amount of fuel gas flow to the Unit Turboset. From the integrator, the

fuel gas continues flowing through a 10-inch line and to a dual 6-inch outlet tee routing to the

Fuel Gas Building.

2.1.1 Fuel Gas Building Equipment

The 6-inch lines direct the flow of fuel gas to the EV and SEV Combustor Fuel Gas Main and

Shutoff valves. The Fuel Gas Main Shutoff Valves are motor operated valves with manual

drives, used to completely isolate the flow of fuel gas flowing through the associated 6-inch

supply line. Each Fuel Gas Main Shutoff Valve (MBP31 AA001 to the EV Combustor and

MBP32 AA001 to the SEV Combustor) is actuated by an electric motor. Each motor is equipped

with a motor heater. The motor heaters function to prevent condensation from occurring within

the motor, since this leads to premature motor failure. Main Shutoff Valve MBP31 AA001,

when OPEN routes fuel gas toward the EV Combustor. A header vent valve take-off, located

downstream of the main shutoff valve, when OPEN vents to atmosphere, any fuel gas from the

fuel gas supply header trapped between the shutoff valve and the EV Combustor Trip/Shutoff

Valve (MBP41 AA001), as well as to gas trapped between the Ignition gas shutoff valve and the

pilot gas shutoff valve. A dirt trap (MBP31 AT001) is located downstream of the main shutoff

valve and vent connection. The dirt trap is used to separate entrained debris from the Fuel Gas.


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Figure 2 – Fuel Gas Control Block

2.1.2 Fuel Gas Control Block

The fuel gas control block is equipped with trip/shutoff valves, control valves, and relief valves

serving the EV and SEV Combustor. Electro hydraulic controlled servomotors control positions

of the control valves and their associated gas flows. Control oil in the hydraulic safety system

(MBX42) and power oil to fuel gas (MBX44) operate the servomotors. The Fuel Gas Control

Block is illustrated on Figure 2.

2.1.2.1 EV Combustor Fuel Gas Supply to Burners

There are three separate fuel gas supplies to the EV Combustor. These are the ignition gas

supply, the EV Pilot supply and the EV Combustor Main Burner (PREMIX) supply. The

equipment is grouped together in the Fuel Gas Control Block.

Ignition Gas

Ignition gas is supplied to the turboset for initial light off of the ignition torches. The ignition

gas supply header takes off downstream of the Fuel Oil Building dirt trap, upstream of the EV

Combustor Trip/Shutoff Valve MPT41 AA001. Ignition gas is routed through the Trip Shut Off


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Valve MBP60 AA010, through throttle valve MBP60 AA020 to the EV Combustor ignition

torches. The ignition torch Trip/Shutoff Valve and Throttle Valve are control air to OPEN and

spring to CLOSE. A relief/vent valve (MBP60 AA030) is provided to vent the ignition header

when the trip and throttle valves are CLOSED. The relief/vent valve is CLOSED by control air

and OPENED by a spring. The relief valve, when OPEN routes fuel gas, trapped between the

Shutoff Valve and the Throttle Valve to atmosphere, at a location above the building roof.

Ignition torch temperature is measured. When the temperature exceeds its differential

temperature requirement in a preset time, an enable signal is issued for continuation of the Gas

turbine starting program.

Pilot Gas

The pilots are lit after the ignition torches and are used to light off the main EV burners. The

pilot gas supply header takes off downstream of the Fuel Oil Building dirt trap, upstream of the

EV Combustor Trip/Shutoff Valve MPT41 AA001. Pilot gas is routed through the Trip Shut Off

Valve MBP43 AA003 through throttle valve MBP43 AA002 to the EV Combustor pilots. The

pilots function to ignite the main EV burners. The pilot gas Trip/Shutoff Valve and Throttle

Valve are hydraulic (via power oil and control oil to the associated servomotor) to OPEN and

spring to CLOSE. A relief/vent valve (MBP53 AA001) is provided to vent the pilot gas header

when the trip and throttle valves are CLOSED. The vent valve is hydraulically CLOSED (via

servomotor) and OPENED by a spring. The relief valve, when OPEN routes fuel gas, trapped

between the Shutoff Valve and the Throttle Valve to atmosphere, at a location above the building

roof.

EV Combustor Burners Supply

The EV Combustor burners are enabled for light off after the pilot ignites and supply the hot

combustion gases required to rotate the HP turbine. The flames of the ignition torches light off

the EV Combustor burners. The EV Combustor Burner fuel gas supply header takes off

downstream of the Fuel Oil Building dirt trap. EV Combustor Burner fuel gas is routed through

the Trip Shut Off Valve MBP41 AA001 and then through throttle valve MBP41 AA002 to the


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EV Combustor burners. The fuel gas Trip/Shutoff Valve and Throttle Valve are hydraulic (via

power oil and control oil to the associated servomotor) to OPEN and spring to CLOSE. A

relief/vent valve (MBP51 AA001) is provided to vent the EV Combustor Main Burner fuel gas

header when the trip and throttle valves are CLOSED. The vent valve is hydraulically CLOSED

(via servomotor) and OPENED by a spring. The relief valve, when OPEN routes fuel gas,

trapped between the Shutoff Valve and the Throttle Valve to atmosphere, at a location above the

building roof.

Temperature downstream of the valve is measured. TIA MBP 41CT002 monitors and transmits

the temperature of the EV Combustor gas supply to the control room. Should the temperature

reach a preset level, an alarm actuates. TP MBP41CT001 locally measures the temperature

within the header. When OPEN it directs the flow of fuel gas to the EV Combustor Gas Flow

Control Valve (MBP41 AA002).

2.1.2.2 EV Combustor Fuel Gas Supply to Burners Controls

When the temperature differential measured at the ignition torches exceeds the requirement in a

preset time frame, the enable signal is given to continue the starting program. The main ignition

sequence is then unblocked. Control valve MBP43 AA002 for EV-Pilot gas opens to the ignition

position (gas flow for main ignition). The gas required for main ignition flows into the EV

combustor through fuel gas control MBP43 and the EV burners, where it ignites by the flame of

the ignition torches (MBM11 AV211 and AV631). When at least two (2) of the three (3)

monitors detect flame within a preset time delay after unblocking, the enable signal is given for

continuation of the starting program.

The ignition gas system and auxiliary air system are shut-off. The valves return to their “at rest”

position (trip valve and control valve closed with vent valve/relief open). Control valve MBP43

AA002 continues to open slowly. The fuel flow increases and the gas turboset is brought up to

nominal speed and is available for increased loading.


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During low load range, the EV burners are supplied by fuel gas control valve MBP43. As

nominal load is reached, fuel gas control MBP41 starts to supply fuel gas. Control Valve

MBP41 AA002 starts to open and simultaneously control valve MBP43 AA002 starts to close

until after a preset time, all gas is supplied by fuel gas control MBP41. During the changeover,

the two control valves function such that the sum of the gas supplied maintains a preset constant

loading gradient of the gas turboset. Control Valve MBP41 AA002 continues to open slowly.

The fuel flow and power output increases. When a higher preset percentage of nominal load is

reached, SEV burners start to operate.

2.1.2.3 SEV Combustor Fuel Gas Supply to Burners

Main Shutoff Valve MBP32 AA001 routes fuel gas to the SEV Combustor. HP Turbine exhaust

is also directed to the SEV Combustor. Hot flue gas from the SEV Combustor is directed to the

LP turbine. This line is equipped with a Trip Shutoff Valve (MBP42 AA001) a throttling valve

(MBP42 AA002) and a vent valve (MBP52 AA001) located between the trip/shutoff valve and

throttling valve arrangement. The relief/vent arrangement is provided to allow gas trapped

between the closed Trip and Throttling valve to vent to the header it shares with the EV vent

allowing vented gas to flow to a location above the building roof.

The SEV Combustor fuel gas Trip/Shutoff Valve and Throttle Valve are hydraulically actuated

(via power oil and control oil to the associated servomotor) to OPEN and spring to CLOSE. A

relief/vent valve (MBP52 AA001) is provided to vent the SEV Combustor Main Burner fuel gas

header when the trip and throttle valves are CLOSED. The vent valve is hydraulically CLOSED

(via servomotor) and OPENED by a spring.

2.1.2.4 SEV Combustor Fuel Gas Control

As a higher preset percentage of nominal load is reached, SEV-burners start to operate. Control

Valve MBP42 AA002 starts to open and supplies fuel gas to the SEV burners. The hot gases

exiting the HP turbine ignite the fuel gas supplied to the SEV burners. The air supplied by

burner carrier air system (MBH70) cools the SEV burners and also maintains the optimum

combustion in SEV Combustor (MBM20).


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While the gas turboset is in operation, control valves MBP41 AA002, MBP42 AA002, and

MBP43 AA002 regulate the supply of gas according to the power output demand. The

demanded power output operates as the control mode. The turbine inlet temperature is limited to

the preset maximum.

Control oil in the hydraulic safety system (MBX42 and power oil to fuel gas (MBX44) operate

the associated servomotors.

2.2 Fuel Oil System

The fuel oil system supplies the EV burners and the SEV burners at a flow rate corresponding to

the power output demanded of the gas turboset and in the conditions required for operation. Trip

valves are provided to interrupt the supply of fuel to the burners whenever an emergency trip is

initiated.

Figure 3 – Fuel Oil Block


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2.2.1 Fuel Oil Block

The Fuel Oil Block is illustrated on Figure 3. Fuel oil supply system MBN31 delivers the fuel

through main shutoff valve MBN31 AA001 and twin filter MBN31 AT001 to fuel pump MBN32

AP001 at the required pressure. The main fuel oil shutoff valve (MBN31 AA001) is motor

operated and has manual positioning available as well. Torque meter switches are included to

stop the motor at its limits of travel. A motor heater is provided to prevent condensation from

occurring within the valve actuator. The fuel oil is directed through a 4-inch line toward the twin

filter arrangement. A low pressure (LP) pressure-limiting valve (MBN31 DP001) is provided to

control the pressure supplied to the twin filter arrangement to a value of 1.7 Bar, and protecting

the fuel supply system from over pressure when the system is at a standstill. Should header

pressure be greater than the valve setting, the fuel oil is routed to the Fuel Oil Sump.

Figure 4 - Fuel Oil Sump


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Fuel Oil Sump

The Fuel Oil Sump is equipped with a Fuel Oil Sump Pump. The Fuel Oil Sump is illustrated on

Figure 4. The Fuel Oil Sump Pump is 460 VAC motor driven and equipped with a motor heater.

The motor heater is in service whenever the pump is out of service. The Fuel Oil Sump Pump

starts and stops as required, maintaining the level in the fuel oil sump. The sump pump starts

when the level in the sump reaches the level switch LS MBN35 CL001 (at greater than 400 mm).

As soon as the sump level drops below the lower level, less than 250 mm, the pump shuts down.

Level alarms are provided. MBL35 CL003, a sump high level switch functions to initiate a

second ON command to the pump and initiates an alarm in the control room. If the level in the

tank continues to rise, reaching the maximum level, level switch (MBL34 CL004) actuates and

initiates load shedding of the gas turboset.

Twin Filters

The fuel oil is filtered via twin filter arrangement (MBN31 AT001). The twin filters, one filter

normally in service, allows for the removal of entrained debris from the No. 2 Diesel fuel oil

supply. The inlet and outlet valves of the twin filter arrangement are ganged together, allowing

flow to the filters to be swapped in a single action. Each filter is equipped with a vent and drain

valve arrangement. Differential pressure is measured across each filter and is indicated locally.

Increased differential pressure is indicative of filter cleanliness, indicating the need to swap to

the alternate filter. A differential pressure alarm for each filter is also is provided, alarming at

0.8 bar. Vents and drains are provided for each filter, routing to the Fuel Oil Sump.


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Figure 5 – Fuel Oil Pump

Fuel Oil Pump

Filtered oil routes to the Fuel Oil Pump (MBN32 AP001). The Fuel Oil Pump is illustrated on

Figure 5. Pressure and temperature upstream of the pump are measured. MBN31 CP003

measures the pressure before the pump.. During startup, MBN31 CP003 prevents startup

program progress until such time as the pressure has reached its preset minimum pressure.

During turboset operation (while firing with fuel oil) if pressure drops below minimum, an alarm

is initiated in the control room. MBN 31 CP004 is provided to measure and locally indicate Fuel

Oil Pump supply pressure. The Fuel Oil Pump boosts the pressure of the fuel oil to 133 Bar for

delivery to the EV and SEV Combustors. A minimum flow valve and flow integrator are

provided. The minimum flow valve (MBN32 AA001) protects the fuel oil pump from

overheating. Until the gas turboset requires a preset fuel flow, a portion of the fuel flows

through the valve, through the fuel oil return system and back to the main fuel oil tank.


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(MBN32 CF001), is an orifice type fuel flow element. The total fuel delivered is displayed in

the control room. Pressure after the fuel pump is measured and displayed in the control room.

MBN32 CP001 and CP002 are the measuring devices. If the pressure in at least one of these

instruments drops below the low level, a control room alarm actuates. If the pressure in at least

one of these instruments drops below the low-low pressure level, turboset load shedding occurs.


2.2.2 Fuel Oil Control Block

The fuel oil from the fuel oil block routes to the fuel oil trip valve (MBN40 AA001). This is the

first valve in the Fuel Oil Control Block. The trip valve is hydraulically actuated to the open

position from its servomotor and is closed via spring pressure. The trip valve acts to isolate or

allow flow to the trip/shutoff valves and control valves supplying fuel oil to the EV and SEV

combustors.


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The following valves are equipped with servomotors and are grouped together on the Fuel Oil

Control Block:

Trip valve (MBN40 AA001)

Control valve (MBN41 AA001)

Control valve (MBN42 AA001)

The control valves are positioned via their associated servomotors, controlled by electrohydraulic

transducers MBN41 AU001 and MBN42 AU001. Power oil from the power oil system MBX44

operates the servomotors.

Additionally, the following valves are operated by control air and are grouped together on the

fuel oil control block.

Shutoff Valve to SEV Combustor (MBN42 AA010)

Fuel Oil Drain Valve (MBN50 AA001)



Pilot valves MBN41 AA101, AA201, AA301, AA401, AA501 and AA601 for the EV burners

and MBN42 AA101, AA201, AA301, AA401, AA501, and AA601 for SEV burners are

normally closed by spring force.

For deaeration of the fuel oil lines, solenoid valve MBX36 AA045 changes over. Pilot valves

MBN41 AA101 of sector 1 and MBN41 AA201 of sector two (2) OPEN. The air is blown

through these sector valves into the EV combustor. Heater MBN 36 AH010 maintains the

temperature in the fuel oil block at or above the preset value. Fan MBN36 AN001 ventilates the

fuel oil block during operation of the turboset.

Pressure limiting valve MBN31 DP001 is installed in the branch line before the fuel oil twin

filter. One of the twin filters is normally in service. Manual changeover between the two (2)

filter vessels is attained using changeover valve MBN31 AA012. The filter vessel that is not in


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service is available for cleaning is emptied through return lines using drain valve MBN31

AA005 and AA021 or MBN31 AA006 and AA022, during gas turboset operation. The

corresponding vent valve, MBN31 AA007 or AA008 has to be opened.

On refilling, during changeover, the filter vessel placed in operation must be deaerated using its

associated vent valve (MBN31 AA007 or AA008). The drain valves must be closed prior to

filling.

During normal operation all vent and drain valves of the filter are closed. Measurement of fuel

oil flow is quantified using a flow meter (MBN32 CF001), installed after the minimum flow

valve (MBN11001).

Orifice MBN35 BP005 is used for continuous deaeration of the sump pump. The uncooled air

for the air blast system (MBH72) is supplied from HP cooling air. This air flows through the EV

burners into the combustor and atomizes the fuel oil in the EV burners. The air supplied from

the burner carrier air system (MBH70) to SEV burners cools the SEV burners and also maintains

optimum combustion in the SEV combustor.

Shutoff Valve MBH70 AA001 and Purge Valve MBH70 AA002 are OPEN. Purge valve

MBH70 AA003 is CLOSED. A portion of the air from system MBH70 flows through the

shutoff and purge valves (MBH70 AA001 and AA002) before the distribution pipes into fuel gas

control MBP42. Then the air flows through fuel gas distribution and SEV burners into the SEV

combustor. This prevents hot gas from entering and coking/clogging the gas nozzles of the SEV

burners.


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3.0 System Operation

Chapter Objectives:

Describe the GT24A Fuel Supply System during:

- System Startup

- Normal Operation

- System Shutdown

NOTE: This system operation section is included for instructional purposes only,

and should not be used as an operating procedure.

3.1 System Startup

The Fuel Supply System must be available for service prior to starting the Combustion Turbine.

It is necessary to verify that all equipment clearance orders have been removed and that air

intake equipment is available for service. All confined space entry permits must be removed

with manways bolted up tight. Twin Filters must be verified as available for service. Valve

alignments must be inspected. All relay system trips must be reset. Any standing alarms must

be cleared.

Fuel Gas Supply System

When “Automatic Start Gas” is selected, startup of the turboset begins. Relief valves (MBP31

AA002, MPB51 AA001, MBP52 AA001 and MBP53 AA001) CLOSE. Main Shutoff valves

(MBP31 AA001 and MBP32 AA001) both OPEN. Gas flows to the trip valves (MBP41 AA001,

MBP42 AA001, and MBP43 AA001). These valves are CLOSED. The following message

appears “Main shutoff valves OPEN and gas relief valves CLOSED”, enabling the startup

program to continue.

The variable guide vane rows OEPN to startup position. When ignition speed is reached, trip

valves (MBP41 AA001, MBP42 AA001 and MBP43 AA001) OPEN. When MBP41 AA001

leaves the CLOSED position, the three (3) flame monitors (MBM11 CR001, CR002, and

CR003) are unblocked. Ignition with fuel gas MBP60, ignition fuel system MBQ 30, control air


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system MBX36 (auxiliary air for ignition torches) and the ignition torches (MBM11 AA211 and

AA631) are activated. The ignition fuel lights off.

When the temperature measured at the ignition torches exceeds the preset differential

requirement in a preset time frame, the enable to proceed signal is issued for continuation of the

starting program.

The main ignition sequence is unblocked. Control Valve MBP43 AA002 for EV pilot gas

OPENS to the ignition position (gas flow for main ignition). The gas required for main ignition

flows into the EV Combustor through fuel gas control MBP43 and the EV Burners, where it

ignites from the flames of the ignition torches.

The ignition gas system and auxiliary air system shut off. The valves return to their “At Rest”

position. Control Valve MBP43 AA002 continues to slowly OPEN. The fuel flow increases and

the speed of the gas turboset increases to nominal speed and is subsequently loaded.

Fuel Oil

While the gas turboset is at standstill, fuel oil pump MBN32 AP001 is out of service (standstill).

Main shutoff valves, the trip valve, and control valves are CLOSED.

After “Automatic Start Fuel Oil” is selected, the main shutoff valve (MBN31 AA001) OPENS.

Fuel oil pressure builds up as far as fuel oil pump (MBN32 AP001). After the pressure has

reached its preset level, the fuel pump starts, increasing pressure for operation up to the trip valve

(MBN40 AA001).

To protect the fuel pump from overheating, due to cavitation, minimum flow valve (MBN32

AA001), directs the minimum flow through the return system back through the return system to

its source, the fuel oil tank.


CT-GT04-24A-SD


The reverse flow opening in this valve closes automatically when the flow to the combustor is

adequate to prevent fuel oil pump overheating.

Pilot valves, oil for EV burners (MBN41 AA101, AA201, AA301, AA401, AA501, and

AA601), fuel oil drain valves (MBN50 AA001 MBN51 AA001 and MBN52 AA001) remain

CLOSED. The turboset’s variable guide vane rows OPEN to their start position. When ignition

speed is reached, trip valve (MBN40 AA001) and shutoff valve (MBN42 AA010) OPEN. Drain

valves (MBN50 AA001, MBN51 AA001 and MBN52 AA001) CLOSE.

When the trip valve leaves the CLOSED position, the three (3) flame monitors (MBM11 CR001,

CR002, and CR003) are unblocked.

Ignition fuel system (MBQ30) and Control Air System (MBX36-auxiliary air for ignition

torches) are placed in service and the ignition torches are actuated. The ignition fuel lights off.

When temperature measured at the ignition torches exceeds its temperature minimum, within a

preset time delay, the enable signal is issued for continuation of the starting program.

For quick deaeration of the fuel oil control (MBN41) solenoid valve MBX36 AA045 changes

over, control air flows to the pilot valves (MBN41 AA101 and AA201) of sectors 1 and 2 and

opens the valves. Control valve MBN41 AA001 OPENS completely for a given time frame.

The fuel oil flows in the fuel oil control and presses the air through the pilot valves (MBN41

AA101 and AA201) and the bypass orifices to pilot valves (MBN41 AA301, AA401, AA501,

and AA601) and the EV burners into the EV combustor. Control Valve MBN41 AA001

CLOSES to minimum (oil flow for main ignition). The oil for main ignition flows through the

EV burners into the EV combustor where it is atomized by the air blast system. It ignites by the

flames of the ignition torches (MBM11 AV211 and AV631).

The ignition gas system (MBQ30), the auxiliary air system (MBX36) are shut off. The valves

return to their “At Rest” position. The ignition torches (MBM11 AV211 and AV631) shut off.


CT-GT04-24A-SD


If at least two (2) of the three (3) flame monitors detect the flames, the enable signal is provided

for continuation of the starting sequence.

Control valve MBN41 AA001 continues to OPEN slowly. The fuel flow increases and the gas

turboset is brought up to nominal speed and loading.

3.2 Normal Operation

Fuel Gas

During low load operation, EV burners are supplied fuel gas via control MBP43. As TAT1

reaches a preset value, fuel gas control MBP41 starts to supply fuel gas. Control Valve MBP41

AA001 starts to OPEN and control valve MBP43 AA002 starts to simultaneously CLOSE until

all gas is supplied by MBP41. During this transition, the two (2) control valves are controlled

using the sum of the gas supplied to maintain a constant loading gradient.

Control Valve MBP41 AA0012 continues to slowly OPEN. The fuel flow and turboset power

output increase. As a higher preset TAT1 is reached, the SEV burners start to operate. Control

Valve MBP42 AA0021 starts to OPEN and supplies fuel gas to the SEV burners. The gas for the

SEV burners ignites due to the hot gases coming from the EV combustor. The air supplied by

the burner carrier air system (MBH70) cools the SEV burners and maintains optimum

combustion in the SEV combustor.

During operation, control valves (MBP41 AA002, MBP42 AA002, and MBP43 AA002) regulate

the supply of gas according to the power output demand. Turbine inlet temperature is monitored

and limited to its maximum value.

Fuel Oil

Under lower load, the EV burners are supplied by fuel oil control (MBN41) and the SEV burners

are not in operation. When a preset level for TAT1 is reached, SEV burners start to operate.

Pilot valves (MBN42 AA101, AA201, AA301, AA401, AA501, and AA601) remain CLOSED.


CT-GT04-24A-SD


Control valve MBN42 AA001 OPENS to minimum stroke. Fuel flows in the supply lines for the

SEV Burners and pressurizes the air remaining in the lines through the bypasses to pilot valves

and the SEV burners into the SEV combustor. When a preset fuel oil pressure after the control

valve is reached, indicating the supply lines are filled with fuel oil, pilot valves for SEV burners

OPEN, the fuel flows into the SEV combustor. The oil for the SEV burners ignites from the hot

gasses exiting from the EV combustor. The air supplied by burner carrier air system (MBH70)

cools the SEV burners, maintains an optimum combustion in SEV combustor (MBM20) and

prevents hot gasses from entering the fuel gas control (MBP42).

While the turboset is in operation, control valves (MBN41 AA001 and MBN42 AA001) regulate

the supply of fuel oil according to the power output demand. The turbine inlet temperature

operates as the control mode.

Should the power output drop below its preset minimum load, control valve MBN42 AA001

CLOSES and the SEV burners shut off. SEV Combustor is then out of service.

After shutdown of the SEV burners, purge valves (MBU42 AA015 and AA016) OPEN

according to the purging sequence. Water flows through the pilot valves (MBU42 AA101,

AA201, AA301, AA401, AA501, and AA601), non-return supply lines of the SEV burners and

purges the remaining oil from the lines to prevent coking of the oil lances. When the power

output increases again, the SEV combustor is returned to service.

Leakages from control valves (MBN41 AA001 and MBN42 AA001), trip valve (MBN40

AA001), shutoff valve (MBN42 AA010), and valves (MBN50 AA001, MBN51 AA001 and

MBN52 AA001) flow through fuel oil drain (MBN50) into the fuel oil sump/tank (MBN35

BB001). The centrifugal extractor (MBN35 BT001) separates fuel from the air.

Fuel samples may be taken or the leakage flow from the valves in the fuel oil control measured at

the changeover valve (MBN50 AA002).


CT-GT04-24A-SD


Leakage from the pump is sent directly to the tank (MBN35 BB001). When fuel reaches the set

upper level, the pump (MBN35 AP001) switches on and pumps the fuel from the sump tank

through the fuel return system (MBN34) into the selected Fuel Oil Storage tank.

When the fuel has dropped to its lower level, the pump switches OFF.

To avoid load shedding during emergency, fuel leakage can be drained through the shutoff valve

(MBN35 AA005).

3.3 System Shutdown

Fuel Gas Operation

During normal shutdown:

Load is removed by slowly closing control valves (MBP41 AA002 and MBP42 AA002). When

TAT1 drops below a preset level, control valve MBP42 AA002 CLOSES completely and the

SEV combustor shuts off.

When TAT1 drops further below another preset level, control valve MBP41 AA002 CLOSES

and control valve MBP43 AA002 OPENS. During this transition, the two (2) control valves are

controlled such that the sum of the gas supplied maintains a constant deloading gradient of the

turboset.

After idling for five minutes, the gas turboset is tripped and runs down. Control Valve MBP43

AA002, trip valves (MBP41 AA001, MBP42 AA001 and MBP43 AA001) CLOSE. Relief

Valves (MBP51 AA001, MBP52 AA001 and MBP53 AA001) OPEN, relieving the line pressure

between the trip and control valves.

Main Shutoff Valves (MBP31 AA001 and MBP32 AA001) CLOSE and relief valves (MBP31

AA001 and MBP32 AA002) OPEN, relieving pressure tripped between the main shutoff valves

and the trip valves.


CT-GT04-24A-SD


Fuel Oil Operation

Initially load is reduced by closing the control valves (MBN41 AA001 and MBN42 AA001).

When TAT1 drops below a preset level, control valve MBN42 AA001 CLOSES completely and

the SEV burners are shut off. After the SEV burners shutdown, purge valves (MBU42 AA015

and AA016) OPEN to purge the burners. Water flows through the pilot valves (MBU42 AA101,

AA201, AA301, AA401, AA501, and AA601) and non-return valves (MBU42 AA110, AA210,

AA310, AA410, AA510, and AA610) into the fuel oil supply line of the SEV burners, purging

the oil remaining in this line out into the combustor, to prevent coking of the oil lances.

Control valve MBN41 AA001 to the EV burners continues to CLOSE until the machine is in

idle. After five minutes on idle, the turboset trips and runs down. Control Valve MBN41

AA001, trip valve MBN40 AA001, and shutoff Valve MBN42 AA010 all CLOSE.

Shutoff Valve MBH72 AA001 of the Air Blast System (MBH72) CLOSES.

After the trip, purge valves (MBU41 AA015 and AA016) OPEN according to the purge

sequence. Purge water routes through the non-return valves MBU41 AA101 and AA110,

AA201 and AA210, AA301 and AA310, AA401 and AA410, AA501 and AA510, AA601 and

AA610), the fuel oil supply lines of the EV burners and purges the oil remaining in these lines

out of the EV combustor, to prevent coking of the oil lances.

The Fuel Pump (MBN31 AP001) shuts off and the shutoff valve (MBN31 AA001) CLOSES.

Relief Valves (MBN50 AA001, MBN51 AA001 and MBN52 AA001) OPEN, relieving the

pressure in their associated lines between the trip valve and the pilot valves into the fuel drain.


CT-GT04-24A-SD


4.0 References

ABB Gas Turbine Manual GT24A

ABB Operations Training Manual Volume I

ABB Operations Training Manual Volume II

ABB Operation/Electrical Maintenance Volume

ABB GT# 7 Protection Sheets


Dirt Trap

MBP32

AT001

Fuel Gas Supply

M M

M M

Fuel Gas To SEV Combustor

To EV Combustor Vent

MBP32

AA002 MBP31

AA002

Main Shutoff

MBP31

AA001

Main Shutoff

MBP32

AA001

Twin Filter

MBP01

AT001

Throttle Vv

MBP41

AA002

Dirt Trap

MBP31

AT001

Trip/Shutoff Vv

MBP42

AA001

Throttle Vv

MBP42

AA002

Relief/vent

Valve MBP52

AA001

Relief/Vent

Valve MBP51

AA001

Trip/Shutoff Vv

MBP41

AA001

Trip/Shutoff Vv

MBP43

AA003

Trip/Shutoff Vv

MBP60

AA010

Relief/Vent

Valve MBP53

AA001

Throttle Vv

MBP43

AA002

EV Pilot

EV Combustor

SEV Combustor

Relief/Vent

Valve MBP60

AA030

Ignition Gas

Vent Over

Roof

Drawing 1 – Fuel Gas System Simplified Diagram

Throttle Vv

MBP60

AA020


Drawing 2 - Fuel Oil Building Simplified Diagram

Fuel Oil Supply

M

M

Fuel Oil Return

Twin Filter

Vents and

Drains

Twin Filters

MBN31 AT001

Main Fuel Oil

Shut off Valve

MBN31

AA001

LP Pressure Limiting Valve

MBN31 DP001

Fuel Oil Sump

M

Fuel Oil Pump

MBN32 AP001

Minimum

Flow Orifice

MBN32 BP011

Minimum

Flow Valve

MBN32 AA001

Sump Pp

MBN35

AP001

Fuel Water

Return

M

Fuel Oil Building

Heating and Ventilation System

MBN36 AN001

Fuel Oil System

From Fuel Pump


Fuel Oil

Supply Header

Fuel Oil Sump

Trip/Shutoff Valve

MBN40 AA001

Fuel Oil Drain Valve

MBN50 AA001

Control Valve

MBN41 AA001

Shutoff Valve

MBN42 AA010

Fuel Oil

To EV Combustor

Fuel Oil To

SEV Combustor


MBN51 AA001


MBN52 AA001

Control Valve

MBN42 AA001

Drawing 3 - Fuel Oil Supply Simplified Diagram

Revision 0 – March 11, 2003

Page 33

FUEL SUPPLY SYSTEM

SYSTEM OPERATING PROCEDURE (CT-GT04-24A-SOP)

Combustion Turbine Plant

March 11, 2003

Combustion Turbine Fuel Supply System

CT-GT02-24A-SOP


PREFACE

This System Operating Procedure has been designed to assist you in meeting the requirements of

Module (CT-GT04-24A) of the Plant Operator Training Program. It contains information about

operation of the Fuel Supply System. This includes purpose, safety, environmental impact

and/or required regulations, training and responsibilities, precautions, limits and setpoints,

references, and procedures for operating the system equipment.

You should also walk down the system and identify the components and controls. Should you

have additional questions about system operation, ask your supervisor.

All activities that could result in the release of hazardous materials to the environment should be

performed with care and due regard for impact on the environment.


EWB-GT02-24A-SOP

Revision 0 - March 11, 2003 Page 2

FUEL SUPPLY

SYSTEM OPERATING PROCEDURE

TABLE OF CONTENTS

I. Purpose............................................................................................................................... 3

II. Precautions, Limitations and Setpoints .......................................................................... 3

III. Procedure ........................................................................................................................... 4

A. Normal System Startup .................................................................................................... 4

B. Fuel Supply System Normal Operation .......................................................................... 8

C. Shutdown of the Fuel Supply System ............................................................................ 12

IV. References ........................................................................................................................ 14

Appendix I Fuel Supply System Valve List .............................................................................. 15


EWB-GT02-24A-SOP


I. Purpose

A. This procedure provides information and guidance for the correct and safe operation of

the Fuel Supply System.

II. Precautions, Limitations and Setpoints

A. Verify that all maintenance work is completed and all protection orders and tags

are released and removed.

B. All confined space entry permits must be released/removed prior to startup.

C. All manways must be bolted up tight prior to startup.

D. Perform Prestartup Check list.

E. The Fuel Supply System must be available for service prior to starting the

Combustion Turbine.

F. Twin Filters must be filled and vented, with drains closed prior to startup.

G. Electrical Distribution System must be energized.

H. 125 VDC System must be in service.

I. Air Intake System must be available for service.

J. Lube Oil System must be in service.

K. Power Oil System must be in service.

L. Control Air must be available.

M. Fuel Gas Supply Pressure is controlled to a pressure no lower than 650 psi.

N. Fuel Gas Twin filter DP (Differential At Which Fuel Oil Filters Are Swapped) -

Eight (8) Bar.

O. Fuel Gas Pressure Limiting Valve (located downstream of the twin filter

arrangement set pressure) controls pressure to a pressure of 25 Bar.

P. LP Fuel Oil Pressure Limiting Valve controls pressure to a value of 1.7 Bar.

Q. Fuel Oil Sump Level Alarms - low alarm is set to actuate at less than 250 mm.

The high alarm actuates at greater than 400 mm.


EWB-GT02-24A-SOP


III. Procedure

A. Normal System Startup

Fuel Gas Firing

__1. Verify valve alignments are in startup positions

__2. Verify that all instrumentation in the Fuel Gas System is operable as

required for service.

__3. EGATROL must be available – not tripped (CJP00EW001.)

__4. Verify all relay system trips are reset.

__5. Any standing alarms must be cleared.

__6. When “Automatic Start Gas” is selected, startup of the turboset begins.

__7. Relief valves (MBP31 AA002, MPB51 AA001, MBP52 AA001 and MBP53

AA001) CLOSE.

__8. Main Shutoff valves (MBP31 AA001 and MBP32 AA001) both OPEN.

__9. Gas flows to the trip valves (MBP41 AA001, MBP42 AA001, and MBP43

AA001). These valves are CLOSED. “

__10. Main shutoff valves OPEN and gas relief valves CLOSED” message appears,

enabling the startup program to continue.

__11. The variable guide vane rows OPEN to startup position.


EWB-GT02-24A-SOP


__12. When ignition speed is reached, trip valves (MBP41 AA001, MBP42 AA001

and MBP43 AA001) OPEN.

__13. When MBP41 AA001 leaves the CLOSED position, the three (3) flame

monitors (MBM11 CR001, CR002, and CR003) are unblocked.

__14. Ignition with fuel gas MBP60, ignition fuel system MBQ 30, control air

system MBX36 (auxiliary air for ignition torches) and the ignition torches

(MBM11 AA211 and AA631) are activated.

__15. The ignition fuel lights off.

__16. When the temperature measured at the ignition torches exceeds the preset

differential requirement in a preset time frame, the enable to proceed signal is

issued for continuation of the starting program.

__17. The main ignition sequence is unblocked.

__18. Control Valve MBP43 AA002 for EV pilot gas OPENS to the ignition

position (gas flow for main ignition).

__19. The gas required for main ignition flows into the EV Combustor through fuel

gas control MBP43 and the EV Burners, where it ignites from the flames of

the ignition torches.

__20. The ignition gas system and auxiliary air system shut off.

__21. The valves return to their “At Rest” position.


EWB-GT02-24A-SOP


__22. Control Valve MBP43 AA002 continues to slowly OPEN.

__23. The fuel flow increases and the speed of the gas turboset increases to nominal

speed and is subsequently loaded.

Fuel Oil Firing

__1. After “Automatic Start Fuel Oil” is selected, the main shutoff valve (MBN31

AA001) OPENS.

__2. Fuel oil pressure builds up as far as fuel oil pump (MBN32 AP001).

__3. After the pressure has reached its preset level, the fuel pump starts, increasing

pressure for operation up to the trip valve (MBN40 AA001).

__4. To protect the fuel pump from overheating, due to cavitation, minimum flow

valve (MBN32 AA001), directs the minimum flow through the return system

back through the return system to its source, the fuel oil tank.

__5. The reverse flow opening in this valve closes automatically when the flow to

the combustor is adequate to prevent fuel oil pump overheating.

__6. Pilot valves, oil for EV burners (MBN41 AA101, AA201, AA301, AA401,

AA501, and AA601), fuel oil drain valves (MBN50 AA001 MBN51 AA001

and MBN52 AA001) remain CLOSED.

__7. The turboset’s variable guide vane rows OPEN to their start position.

__8. When ignition speed is reached, trip valve (MBN40 AA001) and shutoff valve

(MBN42 AA010) OPEN.


EWB-GT02-24A-SOP


__9. Drain valves (MBN50 AA001, MBN51 AA001 and MBN52 AA001)

CLOSE.

__10. When the trip valve leaves the CLOSED position, the three (3) flame monitors

(MBM11 CR001, CR002, and CR003) are unblocked.

__11. Ignition fuel system (MBQ30) and Control Air System (MBX36-auxiliary air

for ignition torches) are placed in service and the ignition torches are

activated. The ignition fuel lights off.

__12. When temperature measured at the ignition torches exceeds its temperature

minimum, within a preset time delay, the enable signal is issued for

continuation of the starting program.

__13. For quick deaeration of the fuel oil control (MBN41) solenoid valve MBX36

AA045 changes over.

__14. Control air flows to the pilot valves (MBN41 AA101 and AA201) of sectors 1

and 2 and opens the valves.

__15. Control valve MBN41 AA001 OPENS completely for a given time frame.

The fuel oil flows in the fuel oil control and presses the air through the pilot

valves (MBN41 AA101 and AA201) and the bypass orifices to pilot valves

(MBN41 AA301, AA401, AA501, and AA601) and the EV burners into the

EV combustor.

__16. Control Valve MBN41 AA001 CLOSES to minimum (oil flow for main

ignition).


EWB-GT02-24A-SOP


__17. The oil for main ignition flows through the EV burners into the EV

combustor.

__18. It ignites by the flames of the ignition torches (MBM11 AV211 and AV631).

__19. The ignition gas system (MBQ30), the auxiliary air system (MBX36) are shut

off. The valves return to their “At Rest” position.

__20. The ignition torches (MBM11 AV211 and AV631) shut off.

__21. If at least two (2) of the three (3) flame monitors detect the flames, the enable

signal is provided for continuation of the starting sequence.

__22. Control valve MBN41 AA001 continues to OPEN slowly. The fuel flow

increases and the gas turboset is brought up to nominal speed and loading.

B. Fuel Supply System Normal Operation

Fuel Gas Firing

__1. Monitor Filter differential pressure.

__2. Monitor Fuel Gas Header Pressure

__3. During low load operation, EV burners are supplied fuel gas via control

MBP43.

__4. At a pre-determined TAT1, fuel gas control MBP41 starts to supply fuel gas.

Control Valve MBP41 AA001 starts to OPEN and control valve MBP43

AA002 starts to simultaneously CLOSE until all gas is supplied by MBP41.


EWB-GT02-24A-SOP


__5. During this transition, the two (2) control valves are controlled using the sum

of the gas supplied to maintain a constant loading gradient.

__6. Control Valve MBP41 AA0012 continues to slowly OPEN. The fuel flow and

turboset power output increase.

__7. As TAT1 further increases, the SEV burners start to operate. Control Valve

MBP42 AA0021 starts to OPEN and supplies fuel gas to the SEV burners.

__8. The gas for the SEV burners ignites due to the hot gases coming from the EV

combustor. The air supplied by the burner carrier air system (MBH70) cools

the SEV burners and maintains optimum combustion in the SEV combustor.

__9. During operation, control valves (MBP41 AA002, MBP42 AA002, and

MBP43 AA002) regulate the supply of gas according to the power output

demand. Turbine inlet temperature is monitored and limited to its maximum

value.

Fuel Oil Firing

__1. During Fuel Oil Firing, under lower load, the EV burners are supplied by fuel

oil control valve (MBN41) and the SEV burners are not in operation.

__2. When the preset TAT1 value is reached, SEV burners start to operate.

__3. Pilot valves (MBN42 AA101, AA201, AA301, AA401, AA501, and AA601)

remain CLOSED.

__4. Control valve MBN42 AA001 OPENS to minimum stroke.


EWB-GT02-24A-SOP


__5. Fuel flows in the supply lines for the SEV Burners and pressurizes the air

remaining in the lines through the bypasses to pilot valves and the SEV burners

into the SEV combustor.

__6. When a preset fuel oil pressure after the control valve is reached, indicating the

supply lines are filled with fuel oil, pilot valves for SEV burners OPEN, and

fuel flows into the SEV combustor.

__7. The oil for the SEV burners ignites from the hot gasses exiting from the EV

combustor.

__8. The air supplied by burner carrier air system (MBH70) cools the SEV burners,

maintains an optimum combustion in SEV combustor (MBM20) and prevents

hot gasses from entering the fuel gas control (MBP42).

__9. While the turboset is in operation, control valves (MBN41 AA001 and MBN42

AA001) regulate the supply of fuel oil according to the power output demand.

__10. The turbine inlet temperature operates as the control mode.

__11. Should the TAT1 drop below a preset minimum level, control valve MBN42

AA001 CLOSES and the SEV burners shut off. The SEV Combustor is then

out of service.

__12. After shutdown of the SEV burners, purge valves (MBU42 AA015 and

AA016) OPEN according to the purging sequence.


EWB-GT02-24A-SOP


__13. Water flows through the pilot valves (MBU42 AA101, AA201, AA301,

AA401, AA501, and AA601), non-return supply lines of the SEV burners and

purges the remaining oil from the lines to prevent coking of the oil lances.

__14. When the power output increases again, the SEV combustor is returned to

service.

__15. Leakages from control valves (MBN41 AA001 and MBN42 AA001), trip

valve (MBN40 AA001), shutoff valve (MBN42 AA010), and valves (MBN50

AA001, MBN51 AA001 and MBN52 AA001) flow through fuel oil drain

(MBN50) into the fuel oil sump/tank (MBN35 BB001).

__16. The centrifugal extractor (MBN35 BT001) separates fuel from the air.

__17. Fuel samples may be taken or the leakage flow from the valves in the fuel oil

control measured at the changeover valve (MBN50 AA002).

__18. Leakage from the pump is sent directly to the tank (MBN35 BB001).

__19. When fuel reaches the set upper level, the pump (MBN35 AP001) switches on

and pumps the fuel from the sump tank through the fuel return system

(MBN34) into the selected Fuel Oil Storage tank.

__20. When the fuel has dropped to its lower level, the pump switches OFF.

__21. To avoid load shedding during emergency, fuel leakage can be drained through

the shutoff valve (MBN35 AA005).


EWB-GT02-24A-SOP


C. Shutdown of the Fuel Supply System

Fuel Gas Firing

__1. Load is removed by slowly closing control valves (MBP41 AA002 and

MBP42 AA002).

__2. When the TAT1 level drops below the higher preset value, control valve

MBP42 AA002 CLOSES completely and the SEV combustor shuts off.

__3. When the TAT1 level drops below the lower preset level, control valve

MBP41 AA002 CLOSES and control valve MBP43 AA002 OPENS. During

this transition, the two (2) control valves are controlled such that the sum of

the gas supplied maintains a constant deloading gradient of the turboset.

__4. After idling for five (5) minutes, the gas turboset is tripped and runs down.

__5. Control Valve MBP43 AA002, trip valves (MBP41 AA001, MBP42 AA001

and MBP43 AA001) CLOSE.

__6. Relief Valves (MBP51 AA001, MBP52 AA001 and MBP53 AA001) OPEN,

relieving the line pressure between the trip and control valves.

__7. Main Shutoff Valves (MBP31 AA001 and MBP32 AA001) CLOSE

__8. Relief valves (MBP31 AA001 and MBP32 AA002) OPEN, relieving pressure

tripped between the main shutoff valves and the trip valves.


EWB-GT02-24A-SOP


Fuel Oil Firing

__1. Initially load is reduced by closing the control valves (MBN41 AA001 and

MBN42 AA001).

__2. When the TAT1 drops to a preset level, control valve MBN42 AA001

CLOSES completely and the SEV burners are shut off.

__3. After the SEV burners shutdown, purge valves (MBU42 AA015 and AA016)

OPEN to purge the burners.

__4. Water flows through the pilot valves (MBU42 AA101, AA201, AA301,

AA401, AA501, and AA601) and non-return valves (MBU42 AA110,

AA210, AA310, AA410, AA510, and AA610) into the fuel oil supply line of

the SEV burners, purging the oil remaining in this line out into the combustor,

to prevent coking of the oil lances.

__5. Control valve MBN41 AA001 to the EV burners continues to CLOSE until

the machine is in idle.

__6. After a time out in idling (5 minutes), the turboset trips and runs down.

__7. Control Valve MBN41 AA001, trip valve MBN40 AA001, and shutoff Valve

MBN42 AA010 all CLOSE.

__8. After the trip, purge valves (MBU41 AA015 and AA016) OPEN according to

the purge sequence.

__9. Purge water routes through the non-return valves MBU41 AA101 and AA110,

AA201 and AA210, AA301 and AA310, AA401 and AA410, AA501 and


EWB-GT02-24A-SOP


AA510, AA601 and AA610), the fuel oil supply lines of the EV burners and

purges the oil remaining in these lines out of the EV combustor, to prevent

coking of the oil lances.

__10. The Fuel Pump (MBN31 AP001) shuts off and the shutoff valve (MBN31

AA001) CLOSES.

__11. Relief Valves (MBN50 AA001, MBN51 AA001 and MBN52 AA001) OPEN,

relieving the pressure in their associated lines between the trip valve and the

pilot valves into the fuel drain.

IV. References

ABB LG&E Burgin Operations Gas Turbine Manual GT24A

ABB LG&E Burgin Operations Training Manual Volume I

ABB LG&E Burgin Operations Training Manual Volume II

ABB LG&E Burgin Operation/Electrical Maintenance Volume

ABB LG&E Burgin GT# 7 Protection Sheets


EWB-GT02-24A-SOP


Appendix I

Fuel Supply System Valve List

Valve

Number Description Startup Normal Shutdown

FUEL GAS FIRING

MBP31

AA001

Fuel Gas Main Shutoff Valve Open Open Closed

MBP32

AA001

Fuel Gas Main Shutoff Valve Open Open Closed

MBP41

AA001

Fuel Gas Trip Valve Open Open Closed

MBP42

AA001


MBP43

AA001


MBP41

AA002

Fuel Gas Control Valve Open Open Closed

MBP42

AA002


MBP43

AA002


MBP31

AA002

Fuel Gas Relief Valve Closed Closed Open

MBP31

AA002


MBP32

AA002


MBP51

AA002


MBP52

AA002


MBP52 Fuel Gas Relief Valve Closed Closed Open


EWB-GT02-24A-SOP


Valve


AA002

FUEL OIL FIRING

MBN31

AA001

Fuel Oil Main Shutoff Valve Open Open Closed

MBN40

AA001

Fuel Oil Trip Valve Closed Open Closed

MBN42

AA010

Fuel Oil Shutoff Valve Closed Open Closed

MBN32

AA001

Fuel Pump Minimum Flow Valve Throttled Throttled Closed

MBN41

AA101

Pilot Valve for EV Burners Closed Open Closed

MBN41

AA101


MBN41

AA201


MBN41

AA301


MBN41

AA401


MBN41

AA501


MBN41

AA601


MBN50

AA001

Fuel Oil Drain Valve Closed Closed Open

MBN51

AA001


MBN52

AA001


MBN50

AA001

Drain Valve Open Closed Open


EWB-GT02-24A-SOP


Valve


MBN52

AA001

Drain Valve Open Closed Open

MBX36

AA045

Control Air Flow to Pilot Valves Closed Open Closed

MBN41

AA101

Pilot Valve Closed Open Closed

MBN41

AA201


MBN41

AA301


MBN41

AA401


MBN41

AA501


MBN41

AA601


MBN42

AA001

Fuel Oil Control Valve to SEV Combustor Closed Open Closed

MBN42

AA101

Fuel Oil Pilot Valve Supply To SEV Combustor Closed Open Closed

MBN42

AA201


MBN42

AA301


MBN42

AA401


MBN42

AA501


MBN42

AA601


MBU41 Purge Valve Closed Closed Open


EWB-GT02-24A-SOP


Valve


AA015

MBU41

AA016

Purge Valve Closed Closed Open

MBU41

AA101

Non-Return Valve (for purging) Closed Closed Open

MBU41

AA110


MBU41

AA201


MBU41

AA210


MBU41

AA301


MBU41

AA310


MBU41

AA401


MBU41

AA410


MBU41

AA501


MBU41

AA510


MBU41

AA601


MBU41

AA610


Combustion Turbine Power Plant Operator– Combustion Turbine 24A

Job Performance Measure (JPM)

Page 19

Plant Operator CT-GT04-24A-JPM

Performance Measure: Fuel Supply System

Name:

All Parts Satisfactorily Completed:

(Examiner’s signature) (Date)

Supervisor’s Comments: __________________________________________________

_______________________________________________________________________

_______________________________________________________________________

_______________________________________________________________________

References:

Training Module (CT-GT04-24A)

Materials Needed:

Pencil

System Description – Fuel Supply System (CT-GT04-24A-SD)

System Operating Procedure – Fuel Supply System (CT-GT04-24A-SOP)

Associated Operator Route Checklist

Combustion Turbine Power Station Fuel Supply System P&IDs

Safety/Environmental:

Wear hard hats, safety glasses, safety toe shoes, and ear plugs as required.

Discuss safety and environmental hazards associated with operating the system.

Discuss any unusual operating conditions associated with the system.

Note: Always observe all plant safety precautions in accordance with Plant Safety and

Health procedures, the Combustion Turbine Power Station Safety and Operating

Rules and all Federal, State and/or Local OSHA Standards.



Page 20

Part A: Location of System Components

Conduct a walk through of the Fuel Supply System, locate, identify and describe the operational

function of the major components.

1. Fuel Gas System

Fuel Gas Supply

Fuel Gas Building Equipment

Fuel Gas Control Block

EV Combustor Fuel Gas Supply to Burners

SEV Combustor Fuel Gas Supply to Burners

2. Fuel Oil Supply System

Fuel Oil Block

Fuel Oil Control Block

Fuel Oil Supply to EV Combustor

Fuel Oil Supply to SEV Combustor

Satisfactorily Completed ___________________________

Part B: Location of Valves

Conduct a walk through of the plant, locate, identify and describe the operational function of the

major valves.

Fuel Gas Supply

1. MBP31 AA001 Fuel Gas Main Shutoff Valve

2. MBP32 AA001 Fuel Gas Main Shutoff Valve

3. MBP41 AA001 Fuel Gas Trip Valve



6. MBP41 AA002 Fuel Gas Control Valve



9. MBP31 AA002 Fuel Gas Relief Valve






Continued on next page



Page 21

Part B: Continued

Fuel Oil Supply

15. MBN31 AA001 Fuel Oil Main Shutoff Valve

16. MBN40 AA001 Fuel Oil Trip Valve

17. MBN42 AA010 Fuel Oil Shutoff Valve

18. MBN32 AA001 Fuel Pump Minimum Flow Valve

19. MBN41 AA101 Pilot Valve for EV Burners







26. MBN50 AA001 Fuel Oil Drain Valve



29. MBN50 AA001 Drain Valve

30. MBN52 AA001 Drain Valve

31. MBX36 AA045 Control Air Flow to Pilot Valves

32. MBN41 AA101 Pilot Valve






38. MBN42 AA001 Fuel Oil Control Valve to SEV Combustor

39. MBN42 AA101 Fuel Oil Pilot Valve Supply To SEV Combustor






45. MBU41 AA015 Purge Valve

46. MBU41 AA016 Purge Valve

47. MBU41 AA101 Non-Return Valve (for purging)









Page 22

Part B: Continued







Satisfactorily Completed ___________________________

Part C: Preparation for Operating the Fuel Supply System

Using the following steps, demonstrate how to prepare for operating the Alstom 24A Fuel Supply

System. Explain your actions at each step.

1. Verify that all maintenance work is completed and all protection orders and tags are released

and removed.

2. All confined space entry permits must be released/removed prior to startup.

3. All manways must be bolted up tight prior to startup.

4. Perform Prestartup Check list.

5. The Fuel Supply System must be available for service prior to starting the Combustion

Turbine.

6. Twin Filters must be filled and vented, with drains closed prior to startup.

7. Electrical Distribution System must be energized.

8. 125 VDC System must be in service.

9. Air Intake System must be available for service.

10. Lube Oil System must be in service.

11. Power Oil System must be in service.

12. Control Air must be available.

13. Fuel Gas Supply Pressure is controlled at 650 psi.

14. Fuel Gas Twin filter DP (Differential At Which Fuel Oil Filters Are Swapped) - Eight (8) Bar.

15. Fuel Gas Pressure Limiting Valve (located downstream of the twin filter arrangement set

pressure) controls pressure to a value of 25 Bar.

16. LP Fuel Oil Pressure Limiting Valve controls pressure to a value of 1.7 Bar.

17. Fuel Oil Sump Level Alarms - low alarm is set to actuate at less than 250 mm. The high

alarm actuates at greater than 400 mm.

Satisfactorily Completed __________________________



Page 23

Part D: 24A Fuel Supply System Startup (Using Fuel Gas)

Perform a start up of the Fuel Supply System using Fuel Gas. Explain your actions and

observations at each step of the procedure.

Fuel Gas Firing

1. Verify valve alignments are in startup positions

2. Verify that all instrumentation in the Fuel Gas System is operable as required for service.

3. EGATROL must be available – not tripped (CJP00EW001.)

4. Verify all relay system trips are reset.

5. Any standing alarms must be cleared.

6. When “Automatic Start Gas” is selected, startup of the turboset begins.

7. Relief valves (MBP31 AA002, MPB51 AA001, MBP52 AA001 and MBP53 AA001)

CLOSE.

8. Main Shutoff valves (MBP31 AA001 and MBP32 AA001) both OPEN.

9. Gas flows to the trip valves (MBP41 AA001, MBP42 AA001, and MBP43 AA001). These

valves are CLOSED. “

10. Main shutoff valves OPEN and gas relief valves CLOSED” message appears, enabling the

startup program to continue.

11. The variable guide vane rows OPEN to startup position.

12. When ignition speed is reached, trip valves (MBP41 AA001, MBP42 AA001 and MBP43

AA001) OPEN.

13. When MBP41 AA001 leaves the CLOSED position, the three (3) flame monitors (MBM11

CR001, CR002, and CR003) are unblocked.

14. Ignition with fuel gas MBP60, ignition fuel system MBQ 30, control air system MBX36

(auxiliary air for ignition torches) and the ignition torches (MBM11 AA211 and AA631) are

activated.

15. The ignition fuel lights off.

16. When the temperature measured at the ignition torches exceeds the preset differential

requirement in a preset time frame, the enable to proceed signal is issued for continuation of

the starting program.

17. The main ignition sequence is unblocked.

18. Control Valve MBP43 AA002 for EV pilot gas OPENS to the ignition position (gas flow for

main ignition).

19. The gas required for main ignition flows into the EV Combustor through fuel gas control

MBP43 and the EV Burners, where it ignites from the flames of the ignition torches.

20. The ignition gas system and auxiliary air system shut off.

21. The valves return to their “At Rest” position

Continued on Next Page



Page 24

Part D - Continued

22. Control Valve MBP43 AA002 continues to slowly OPEN.

23. The fuel flow increases and the speed of the gas turboset increases to nominal speed and is

subsequently loaded.


Part E: 24A Fuel Supply System Startup (Using Fuel Oil)

Perform a start up of the Fuel Supply System using Fuel Oil. Explain your actions and

observations at each step of the procedure.

Fuel Oil Firing

1. After “Automatic Start Fuel Oil” is selected, the main shutoff valve (MBN31 AA001)

OPENS.

2. Uncooled air supplied by HP cooling air system (MBH40) flows through system MBH72 and

the EV burners for combustion.

3. Fuel oil pressure builds up as far as fuel oil pump (MBN32 AP001).

4. After the pressure has reached its preset level, the fuel pump starts, increasing pressure for

operation up to the trip valve (MBN40 AA001).

5. To protect the fuel pump from overheating, due to cavitation, minimum flow valve (MBN32

AA001), directs the minimum flow through the return system back through the return system

to its source, the fuel oil tank.

6. The reverse flow opening in this valve closes automatically when the flow to the combustor

is adequate to prevent fuel oil pump overheating.

7. Pilot valves, oil for EV burners (MBN41 AA101, AA201, AA301, AA401, AA501, and

AA601), fuel oil drain valves (MBN50 AA001 MBN51 AA001 and MBN52 AA001) remain

CLOSED.

8. The turboset’s variable guide vane rows OPEN to their start position.

9. When ignition speed is reached, trip valve (MBN40 AA001) and shutoff valve (MBN42

AA010) OPEN.

10. Drain valves (MBN50 AA001, MBN51 AA001 and MBN52 AA001) CLOSE.

11. When the trip valve leaves the CLOSED position, the three (3) flame monitors (MBM11

CR001, CR002, and CR003) are unblocked.

12. Ignition fuel system (MBQ30) and Control Air System (MBX36-auxiliary air for ignition

torches) are placed in service and the ignition torches are activated. The ignition fuel lights

off.

13. When temperature measured at the ignition torches exceeds its temperature minimum, within

a preset time delay, the enable signal is issued for continuation of the starting program.



Page 25

14. For quick deaeration of the fuel oil control (MBN41) solenoid valve MBX36 AA045 changes

over.

15. Control air flows to the pilot valves (MBN41 AA101 and AA201) of sectors 1 and 2 and

opens the valves.

16. Control valve MBN41 AA001 OPENS completely for a given time frame. The fuel oil flows

in the fuel oil control and presses the air through the pilot valves (MBN41 AA101 and

AA201) and the bypass orifices to pilot valves (MBN41 AA301, AA401, AA501, and

AA601) and the EV burners into the EV combustor.

17. Control Valve MBN41 AA001 CLOSES to minimum (oil flow for main ignition).

18. The oil for main ignition flows through the EV burners into the EV combustor where it is

atomized by the air blast system.

19. It ignites by the flames of the ignition torches (MBM11 AV211 and AV631).

20. The ignition gas system (MBQ30), the auxiliary air system (MBX36) are shut off. The

valves return to their “At Rest” position.

21. The ignition torches (MBM11 AV211 and AV631) shut off.

22. If at least two (2) of the three (3) flame monitors detect the flames, the enable signal is

provided for continuation of the starting sequence.

23. Control valve MBN41 AA001 continues to OPEN slowly. The fuel flow increases and the

gas turboset is brought up to nominal speed and loading.

Satisfactorily Completed ____________________________



Page 26

Part F: Fuel Supply System (Fuel Gas) Inspection (Normal Operations)

Conduct a complete system inspection of the Fuel Supply System (Gas Supply). Explain your

actions and observations as equipment is inspected.

1. Monitor Filter differential pressure.

2. Monitor Fuel Gas Header Pressure

3. During low load operation, EV burners are supplied fuel gas via control MBP43.

4. As a preset level for TAT1 is reached, fuel gas control MBP41 starts to supply fuel gas.

Control Valve MBP41 AA001 starts to OPEN and control valve MBP43 AA002 starts to

simultaneously CLOSE until all gas is supplied by MBP41.

5. During this transition, the two (2) control valves are controlled using the sum of the gas

supplied to maintain a constant loading gradient.

6. Control Valve MBP41 AA0012 continues to slowly OPEN. The fuel flow and turboset

power output increase.

7. As a higher preset TAT1 level is reached, the SEV burners start to operate. Control Valve

MBP42 AA0021 starts to OPEN and supplies fuel gas to the SEV burners.

8. The gas for the SEV burners ignites due to the hot gases coming from the EV combustor.

The air supplied by the burner carrier air system (MBH70) cools the SEV burners and

maintains optimum combustion in the SEV combustor.

9. During operation, control valves (MBP41 AA002, MBP42 AA002, and MBP43 AA002)

regulate the supply of gas according to the power output demand. Turbine inlet temperature

is monitored and limited to its maximum value.

Satisfactorily Completed ____________________________



Page 27

Part G: Fuel Oil System Inspection

Conduct a complete system inspection of the Fuel Supply System (Diesel Supply). Explain your

actions and observations as equipment is inspected.

1. During Fuel Oil Firing, under lower load, the EV burners are supplied by fuel oil control

valve (MBN41) and the SEV burners are not in operation.

2. When a preset level for TAT1 is reached, SEV burners start to operate.

3. Pilot valves (MBN42 AA101, AA201, AA301, AA401, AA501, and AA601) remain

CLOSED.

4. Control valve MBN42 AA001 OPENS to minimum stroke.

5. Fuel flows in the supply lines for the SEV Burners and pressurizes the air remaining in the

lines through the bypasses to pilot valves and the SEV burners into the SEV combustor.

6. When a preset fuel oil pressure after the control valve is reached, indicating the supply lines

are filled with fuel oil, pilot valves for SEV burners OPEN, and fuel flows into the SEV

combustor.

7. The oil for the SEV burners ignites from the hot gasses exiting from the EV combustor.

8. The air supplied by burner carrier air system (MBH70) cools the SEV burners, maintains an

optimum combustion in SEV combustor (MBM20) and prevents hot gasses from entering the

fuel gas control (MBP42).

9. While the turboset is in operation, control valves (MBN41 AA001 and MBN42 AA001)

regulate the supply of fuel oil according to the power output demand.

10. The turbine inlet temperature operates as the control mode.

11. Should the TAT1 drop below a preset level, control valve MBN42 AA001 CLOSES and the

SEV burners shut off. The SEV Combustor is then out of service.

12. After shutdown of the SEV burners, purge valves (MBU42 AA015 and AA016) OPEN

according to the purging sequence.

13. Water flows through the pilot valves (MBU42 AA101, AA201, AA301, AA401, AA501, and

AA601), non-return supply lines of the SEV burners and purges the remaining oil from the

lines to prevent coking of the oil lances.

14. When the power output increases again, the SEV combustor is returned to service.

15. Leakages from control valves (MBN41 AA001 and MBN42 AA001), trip valve (MBN40

AA001), shutoff valve (MBN42 AA010), and valves (MBN50 AA001, MBN51 AA001 and

MBN52 AA001) flow through fuel oil drain (MBN50) into the fuel oil sump/tank (MBN35

BB001).

16. The centrifugal extractor (MBN35 BT001) separates fuel from the air.

17. Fuel samples may be taken or the leakage flow from the valves in the fuel oil control

measured at the changeover valve (MBN50 AA002).

18. Leakage from the pump is sent directly to the tank (MBN35 BB001).




Page 28

Part G: Continued

19. When fuel reaches the set upper level, the pump (MBN35 AP001) switches on and pumps the

fuel from the sump tank through the fuel return system (MBN34) into the selected Fuel Oil

Storage tank.

20. When the fuel has dropped to its lower level, the pump switches OFF.

21. To avoid load shedding during emergency, fuel leakage can be drained through the shutoff

valve (MBN35 AA005).


Part H: Fuel Supply System Shutdown (Fuel Gas Operation)

Explain your actions and observations at each step of the procedure.

1. Load is removed by slowly closing control valves (MBP41 AA002 and MBP42 AA002).

2. When TAT1 drops below the higher preset level, control valve MBP42 AA002 CLOSES

completely and the SEV combustor shuts off.

3. When TAT1 drops below the lower preset level, control valve MBP41 AA002 CLOSES and

control valve MBP43 AA002 OPENS. During this transition, the two (2) control valves are

controlled such that the sum of the gas supplied maintains a constant deloading gradient of

the turboset.

4. After idling for 5 minutes, the gas turboset is tripped and runs down.

5. Control Valve MBP43 AA002, trip valves (MBP41 AA001, MBP42 AA001 and MBP43

AA001) CLOSE.

6. Relief Valves (MBP51 AA001, MBP52 AA001 and MBP53 AA001) OPEN, relieving the

line pressure between the trip and control valves.

7. Main Shutoff Valves (MBP31 AA001 and MBP32 AA001) CLOSE

8. Relief valves (MBP31 AA001 and MBP32 AA002) OPEN, relieving pressure tripped

between the main shutoff valves and the trip valves.




Page 29

Part I: Fuel Supply System Shutdown (Fuel Oil Operation)

Explain your actions and observations at each step of the procedure.

1. Initially load is reduced by closing the control valves (MBN41 AA001 and MBN42 AA001).

2. When TAT1 drops below a preset level, control valve MBN42 AA001 CLOSES completely

and the SEV burners are shut off.

3. After the SEV burners shutdown, purge valves (MBU42 AA015 and AA016) OPEN to purge

the burners.

4. Water flows through the pilot valves (MBU42 AA101, AA201, AA301, AA401, AA501, and

AA601) and non-return valves (MBU42 AA110, AA210, AA310, AA410, AA510, and

AA610) into the fuel oil supply line of the SEV burners, purging the oil remaining in this line

out into the combustor, to prevent coking of the oil lances.

5. Control valve MBN41 AA001 to the EV burners continues to CLOSE until the machine is in

idle.

6. After 5 minutes on idle, the turboset trips and runs down.

7. Control Valve MBN41 AA001, trip valve MBN40 AA001, and shutoff Valve MBN42

AA010 all CLOSE.

8. After the trip, purge valves (MBU41 AA015 and AA016) OPEN according to the purge

sequence.

9. Purge water routes through the non-return valves MBU41 AA101 and AA110, AA201 and

AA210, AA301 and AA310, AA401 and AA410, AA501 and AA510, AA601 and AA610),

the fuel oil supply lines of the EV burners and purges the oil remaining in these lines out of

the EV combustor, to prevent coking of the oil lances.

10. The Fuel Pump (MBN31 AP001) shuts off and the shutoff valve (MBN31 AA001) CLOSES.

11. Relief Valves (MBN50 AA001, MBN51 AA001 and MBN52 AA001) OPEN, relieving the

pressure in their associated lines between the trip valve and the pilot valves into the fuel

drain.




Page 30

Part J: Personnel and Equipment Safety

Verify the individual performed all aspects of the JPM using safe operating practices and

following plant safety and environmental procedures.


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