FUEL SUPPLY SYSTEM
TRAINING SYSTEM DESCRIPTION (EWB-GT04-24A-SD)
E.W. BROWN
March 11, 2003
E.W. Brown Power Plant Fuel Supply System
EWB-GT04-24A-SD
PREFACE
This System Description has been designed to assist you in meeting the requirements of Module (EWB-GT04) of the Plant Operator Training Program. It contains information about the E.W. Brown 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 (EWB-GT04-24A-SOP), covers detailed operation of the E.W. Brown 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 E.W. Brown Spill and Counter Measure Plan.
FUEL SUPPLY SYSTEM DESCRIPTION
TABLE OF CONTENTS
1.0Introduction
1.1Purpose
1.2Basic System Description
1.2.1System Parameters
1.3System Flowpaths
2.0System Major Components
2.1Fuel Gas System and Burner Supply Systems
2.1.1Fuel Gas Supply
2.1.1Fuel Gas Building Equipment
2.1.2Fuel Gas Control Block
2.1.2.1EV Combustor Fuel Gas Supply to Burners
2.1.2.2EV Combustor Fuel Gas Supply to Burners Controls
2.1.2.3SEV Combustor Fuel Gas Supply to Burners
2.1.2.4SEV Combustor Fuel Gas Control
2.2Fuel Oil System
2.2.1Fuel Oil Block
2.2.2Fuel Oil Control Block
3.0System Operation
3.1System Startup
3.2Normal Operation
3.3System Shutdown
4.0References
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
Figure 6 – Fuel Oil Control Block
List of Drawings
Drawing 1 – Fuel Gas System Simplified Diagram
Drawing 2 – Fuel Oil Building Simplified Diagram
Drawing 3 – Fuel Oil Supply Simplified Diagram
1.0Introduction
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.
1.1Purpose
The purpose of the E.W. Brown 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.
1.2Basic 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 E.W.Brown Burgin 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 E.W.Brown Burgin Plant location acts as the secondary fuel source for firing the EV and SEV Combustors.
1.2.1System Parameters
Number Of Fuel Oil TanksTwo (2)
Fuel Oil Tank Capacity Each1.1 million gallons
Fuel Oil Pump discharge pressure 133 Bar
Minimum Fuel Gas Supply Pressure650 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
1.3System 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 E.W.Brown Burgin 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 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).
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.
2.0System 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 E.W. Brown GT24A Fuel Supply System (as found on Units 6 and 7) consists of the following major components:
- 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
- Fuel Oil Supply System
- Fuel Oil Block
- Fuel Oil Control Block
Figure 1 – Fuel Gas Twin Filter Arrangement
2.1Fuel 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.
2.1.1Fuel Gas Supply
Fuel Gas for the Units 6 and 7 Combustion Turbines is supplied from Texas Eastern and Tennessee Supply lines to the E.W.Brown Burgin 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 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.
2.1.1Fuel 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.
Figure 2 – Fuel Gas Control Block
2.1.2Fuel 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.
2.1.2.1EV 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 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 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).
2.1.2.2EV 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.