GE MDT Prolop "A"

PROLOP MDT Controls 10/13/2010 General Electric Mechanical Drive Turbine PROLOP controls presented byJFByrd Jr 1

PROLOP MDT Controls 10/13/2010 Prolop MDT Controls • Control Diagram • Lever diagram • Black Book GEK - 15674 The control diagram, lever diagram, and sections from the black book are used to explain the function of the feed pump controls.JFByrd Jr 2

PROLOP MDT Controls 10/13/2010 The Control Diagram is used to describe the interrelationships of the mechanics, hydraulics and instrumentation. The drawing shows many sub systems that will be discussed in separatly. The purpose of the control system is to provide a means to stop the turbine/pump if abnormal operating conditions occur provide a “governor” that will maintain constain speed operation and allow for the adjustment of the speed to meet the feedwater flow demands of the reactor Prevent the turbine from exceeding destrutive overspeed in an advent of a governor failureJFByrd Jr 3

PROLOP MDT Controls 10/13/2010 The table provides the settings for the instrumentation on the turbine along with the adjustable devices; alarming dial thermometers, limit switches, pressure switches, and pressure reducing and relief valves.JFByrd Jr 4

PROLOP MDT Controls 10/13/2010 The governor section positions the control valves to maintain set speed for constaint feed water delevery and provide a means to allow adjustment to the set speed. The lever drawing will provide more function description, but the hydraulic supply is shown here.JFByrd Jr 5

PROLOP MDT Controls 10/13/2010 The trip and reset devices that provide emergency closure of the Stop Valves (and the control valves) in the advent of an abnormal operation condition or over speedJFByrd Jr 6

PROLOP MDT Controls 10/13/2010 The lube oil system supplies hydruilic power for the turbine governor, valve actuators and controls, along with lubrication oil for the turbine and pump bearingsJFByrd Jr 7

PROLOP MDT Controls 10/13/2010 The lube oil system The system is composed of an oil storage tank, two motor -driven pumps and a shaft-driven pump for supplying the oil to the system, an oil cooler and filter for that portion of the system which is used or lubrication, pressure-regulation valves for maintaining the pressure required for the turbine controls and the turbine lubrication, and necessary piping and instrumentation.JFByrd Jr 8

PROLOP MDT Controls 10/13/2010 Adding color to show the different pressure headers Purple-HP header ~200 psig Blue_LP Header ~ 55 psig Lt Blue~ LP supply for bearings Lt Green Bearing Header ~10psig Green ~ drain / tankJFByrd Jr 9

PROLOP MDT Controls 10/13/2010 Pressure gages PG-l measures governor oil pressure HP header. PG-2 measures turbine bearing oil pressure. PG-3 measures oil pressure ahead of dual filter. PG-4 measures oil pressure after dual filter. PG-5 measures control oil pressure LP headerJFByrd Jr 10

PROLOP MDT Controls 10/13/2010 The main oil pump is a dual positive displacement gear pump driven through a gear train by the turbine shaft. It provides the oil requirements over the major portion of the turbine speed range. The high pressure section of the pump furnishes hydraulic oil pressure to the governor system’s HP header as controlled by pressure relief valve MRV-1. The low pressure section of the pump furnishes hydraulic oil pressure to the governor system’s LP header (and to the lubrication system) as controlled by pressure relief valve MRV-2.JFByrd Jr 11

PROLOP MDT Controls 10/13/2010 The auxiliary oil pump (AOP) is a motor-driven centrifugal pump with its HP header discharge pressure controlled by the pump characteristics. Oil to the governor system’s LP header and to the lubrication system is controlled by pressure relief valve PRV-3. The AOP furnishes oil for the hydraulic and lubrication systems at startup and at low speeds. The AOP pump is arranged to start automatically by means of pressure switch PS4 which senses oil pressure in the LP header. PS3 located between the pump and its discharge check valve provides for indication L3. An auto start test is performed with PB6, which energizes SV5 to lower the pressure at pressure switch PS4.JFByrd Jr 12

PROLOP MDT Controls 10/13/2010 The emergency oil pump (EOP) is a centrifugal pump of lower capacity than the AOP. Its discharge is to the lube oil header and is separated from it by a check valve. The pump supplies oil in a quantity sufficient for lubrication requirements only. The EOP pump is arranged to start automatically by means of pressure switch PS6 which senses oil pressure in the lube oil header. PS5 located between the pump and its discharge check valve provides for indication L4. An auto start test is performed with PB7, which energizes SV4 to lower the pressure at pressure switch PS6.JFByrd Jr 13

PROLOP MDT Controls 10/13/2010 LP header oil for lubrication passes through dual oil coolers with a transfer valve so that either Cooler can be operated singly. There is also the dual oil filter arranged with a bypass/transfer valve which allows one side of the filter to be opened for maintenance while the turbine is operating. The bearing header is controlled by pressure relief valve PRV3. Pressure switches. PS-8 and PS-19 are provided to give alarm and trip protection in case of low bearing oil pressure. Pressure switch PS-19 Has been replaced with 3 pressure switches to monitor bearing oil pressure and provide a trip on a 2-out-of -3 actuation of low bearing oil pressure.JFByrd Jr 14

PROLOP MDT Controls 10/13/2010 PRV3 is set to relieve the AOP into the LP header to supply 50 psig MRV1 is set to relieve the HP gear pump at 200 psig MRV2 is set to relieve the LP gear pump at 55 PRV1 is set to supply the bearing header at 10 psig This arrangement is changed with latter units, no MRV1, different location of PRV3 and 55 header same pressure on AOP or gear PS4 is set to start the AOP as the LP gear pump discharge drops with reducing turbine speed below 43 psig PS6 is set to start the EOP as the LP gear pump dischage drops OR the AOP pressure to the LP header supply is reduced below 36 psig PS8 provides alarm of low bearing oil pressure below 5 psig PS19 provides TRIP from low bearing oil pressure below 4 psigJFByrd Jr 15

PROLOP MDT Controls 10/13/2010 The trip system Shut steam flow with the SVs in the advent of abnormal operating conditions The emergency over speed trip is to limit runaway speed to less than rotor yield speed Cross trip the governor and close the CVsJFByrd Jr 16

PROLOP MDT Controls 10/13/2010 Adding color to show the different oil pressures and circits Red stop valve oil supply Lt Red trip dump circuit Lt Blue trip piston headerJFByrd Jr 17

PROLOP MDT Controls 10/13/2010 The stop valves (SV) are reset to their open position upon a buildup of pressure in the SV oil supply line. The SV hydraulic operating cylinders receive their oil through an orifice relay dump valve. When oil pressure is applied to the SV’s relay valves, they close the cylinder drains and restricts the cylinders filling rate by means of their orifices.JFByrd Jr 18

PROLOP MDT Controls 10/13/2010 Oil flow to the SVs is through the 3-way relay valve which feeds oil directly to the SVs when the 3- way relay valve is in its reset position The reset position of the 3-way relay valve piston is dependent upon the position of the trip rod relative to the latching step on its trigger. The trip circuit oil is fed to the trip dump valve through an orifice in the 3-way relay’s piston.JFByrd Jr 19

PROLOP MDT Controls 10/13/2010 When the trip rod is latched on its trigger, the trip dump valve will be moved through the connecting linkage between the trip rod and the piston to close off the oil drain ports. Oil pressure will build up in the oil line between the 3-way valve and the trip dump valve. Build up of oil pressure in this line will cause the 3-way relay valve piston to move to its reset position, opening the SV oil supply line …and the SVs open.JFByrd Jr 20

PROLOP MDT Controls 10/13/2010 The SVs are tripped shut upon a release of pressure in its supply line. When pressure oil to the SV dump relay valve is released, the valve opens, uncovers the cylinder drain, and trips the stop valve shut. The relay valve provides for quick tripping of the SV when a very small volume of oil is displaced in the pressure line to the operating cylinder.JFByrd Jr 21

PROLOP MDT Controls 10/13/2010 Oil flow from the SV is through the 3-way relay valve, which shut off the oil supply and drains the SV oil line when in its tripped position. The tripped position of the 3-way relay valve piston is dependent upon the position of the trip rod relative to the latching step on its trigger and the position of the trip and reset piston.JFByrd Jr 22

PROLOP MDT Controls 10/13/2010 When the trip rod is unlatched (trigger rotated so the rod moves off the latching step). The trip piston moves to open the trip circuit control oil to drain and oil pressure is released from the trip side of the 3-way valve piston. The resulting pressure differential across the 3 way valve piston will cause the piston to move to its closed position. This shuts off oil feed to the stop valve and at the same time, opens the stop valve oil line to drain …and the SV will close, quickly. The trip rod is unlatched and the dump valve is opened to drain when the trigger is struck by the over speed governor plunge or by the hand and/or hydraulic piston operated lever.JFByrd Jr 23

PROLOP MDT Controls 10/13/2010 In hydraulic tripping, solenoid valve SV-12 is energized. Energizing the solenoid positions its valve to close off oil to piston and opens the piston to drain and the piston moves to rotate the lever against the trigger, to unlatch the trip rod. Note that with this tripping system the trip rod cannot be latched until hydraulic pressure is established under the piston, which means SV-12 de-energized. The solenoid valve SV-12 provides for remote tripping t automatic tripping from other station components and automatic tripping due to the thrust wear device pressure switches PS-2 and PS-12 or low bearing oil pressure switch PS-19.JFByrd Jr 24

PROLOP MDT Controls 10/13/2010 The trip rod is unlatched and the dump valve is opened to drain when the trigger is struck by the over speed governor plunge or by the hand and/or hydraulic piston operated lever. In hydraulic tripping, solenoid valve SV-12 is energized. Energizing the solenoid positions its valve to close off oil to piston and opens the piston to drain and the piston moves to rotate the lever against the trigger, to unlatch the trip rod. Note that with this tripping system the trip rod cannot be latched until hydraulic pressure is established under the piston, which means SV-12 de-energized. The solenoid valve SV-12 provides for remote tripping t automatic tripping from other station components and automatic tripping due to the thrust wear device pressure switches PS-2 and PS-12 or low bearing oil pressure switch PS-19.JFByrd Jr 25

PROLOP MDT Controls 10/13/2010 Normally the lockout valve allows the trip dump valve and the relay to directly communicate. To ensure reliability, the emergency governor was made testable and the lockout allows testing of the emergency governor with out tripping the SVs. Energizing SV13 applies 55# to the lockout piston and shuttles the lands to separate the dump valve from the relay. The dump valve can be tripped without dropping the pressure to the relay piston.JFByrd Jr 26

PROLOP MDT Controls 10/13/2010 Energizing SV13 applies 55# to the lockout piston The pressure from SV13 can be relieved by energizing SV12 or by the BUOS rotating pilot valve this will return the lockout valve to normal so any electrical trip is still active and, in the case of a real over speed situation during the test, over speed protection is in effect.JFByrd Jr 27

PROLOP MDT Controls 10/13/2010 Resetting the tripping mechanism can be accomplished by manually pulling on the reset handle or energizing the solenoid valve SV -8. Oil pressure must be applied at the trip piston and the hand trip handle must be released before the mechanism can be reset. Hydraulic resetting the piston and the trip rod are brought to their reset positions by application of oil pressure at the large end of the piston by energizing the solenoid valve SV -8. The trigger rotates to its latching position. Then upon releasing the reset handle, spring will move the trip rod against the latching step on the trigger, and the trip mechanism will be in its reset position. The spring will hold the trip rod on the latching step until the trigger is again rotated out of position Limit switches LS-16 and LS-l7 with lights L-10 and L-11 indicate trip or reset position of the trip mechanism.JFByrd Jr 28

PROLOP MDT Controls 10/13/2010 Each SV has a relay valve connected to a port in the stop valve operating cylinder wall which can be opened to drain oil from the cylinder for a stop valve test. When the test relay is opened, the operating cylinder piston is displaced in the closing direction until the port in the cylinder wall is covered and the outward flow of oil is stopped.JFByrd Jr 29

PROLOP MDT Controls 10/13/2010 The LPSV only test partially close. Pushbutton PB4 is used to actuate the solenoid valve SV1. Limitswitches LSl and (LS9) indicate the LPSV position (open or closed). The HPSV test fully close when the turbine is operating on low pressure (high pressure control valve closed). Pushbutton PB5 is used to actuate the solenoid valve SV2. Limit switches LS6 indicates LPCVs are closed for indicating lamp L5 and interlock for PB5. LS2 and LS10 indicate the LPSV position (open or closed).JFByrd Jr 30

PROLOP MDT Controls 10/13/2010 The stop valve (SV) hydraulic operating cylinders receive their pressure oil through an orifice relay dump valve. When pressure oil is applied to the relay valve it closes the cylinder drain and restricts the cylinder filling rate by means of the orifice. When pressure oil to the relay valve is released, the valve opens, uncovers the cylinder drain, and trips the stop valve shut. The relay valve provides for quick tripping of the stop valve when a very small volume of oil is displaced in the pressure line to the operating cylinder.JFByrd Jr 31

PROLOP MDT Controls 10/13/2010 Pressure Reset relay To / From SV Trip Circuit Header HP Header Supply Tripped Oil flow to the stop valve is through the 3-way relay valve, which will either feed oil directly to the stop valve, when the 3-way relay valve is in its reset position, or will shut off the oil supply to the stop valve and drain the stop valve oil line when in its tripped position. The position (tripped or reset) of the 3-way relay valve piston is dependent upon the pressure in the trip circuit oil header. When latched, the trip dump valve is closed, oil pressure will build up and cause the relay valve piston to move to its reset position. This supplies oil pressure to the stop valve oil supply line and the stop valve will open. When unlatched, the trip dump opens to drain the trip circuit oil header and the resulting pressure differential across the 3 way relay piston will cause the piston to move to its trip position. This shuts off oil feed to the stop valve and at the same time, opens the stop valve oil line to drain, and the stop valve will close.JFByrd Jr 32

PROLOP MDT Controls 10/13/2010 Lockout Normal valve Locked out Normal has the left piston area to drain and the right side has constant 55# supply. With the valve to the left, the 200# oil from the relay is in communication with the dump valve (either being drained if tripped or at pressure if deadheaded when reset. Energized SV13 applies 55# (yellow) on the left side and with larger surface area, the valve moves to the right. This separated the relay oil flow from the dump valve, keeping the relay deadheaded (light red), allowing the dump valve to trip (and drain) to test the emergency governor. The orifices on the right provide hydraulic position indication using two pressure switches.JFByrd Jr 33

PROLOP MDT Controls 10/13/2010 As the piston covers the orifice, the pressure to the PS goes to 55#, but is about 30# with orifices open . The pressure settings depend on the actual pressure of the 55# header and the orifice diameters. I recently found unit where the 5/32” were actually 3/32. When the pressures indicated the lower orifice was too restricted, maintenance was performed expecting varnish buildup.JFByrd Jr 34

PROLOP MDT Controls 10/13/2010 SV12 Tripped Reset The trip solenoid valve SV-12 has two functions: 1) To control LP oil in the trip cylinder of the emergency tripping and reset mechanism, and 2) To sustain LP oil in the trip exerciser oil circuit when lockout test is being performed, or release the exerciser oil to drain on electrical trip device action when lockout is being exercised. In the normal operating position the solenoid valve SV-12 is de-energized. Oil flow to the trip piston is through solenoid operated valve SV-12 and the trip rod and trip dump valve can be reset. When energized to trip the turbine, the valve moves to cutoff supply and drains oil from the trip piston. At the same time, the valve opens the trip exerciser oil circuit to drain, thus nullifying emergency trip lockout, if being exercised, or prevent lockout test, and the emergency tripping mechanism will function to trip the turbine.JFByrd Jr 35

PROLOP MDT Controls 10/13/2010 N<BUOS N=BUOS The SV13 trip exerciser oil circuit connects to the back-up over speed (BOUS) bushing at the primary pilot valve body. If turbine speed is below the BOUS setting, the port is blocked allowing lockout valve to shuttle. If the speed exceeds BOUS, the flyweights pull the rotating pilot valve down and the BOUS port opens to drain SV13 trip exerciser oil circuit supply. The lockout valve goes normal and the emergency trip can function through the action of the emergency governor if over speed setting is reached. The back-up bushing is set to release trip exerciser oil at approximately 105% rated speed.JFByrd Jr 36

PROLOP MDT Controls 10/13/2010 EMERGENCY (OVERSPEED) GOVERNOR In the event the turbine over speeds, the emergency governor operates to actuate the emergency tripping mechanism, which trips the stop valves to shut off steam flow to the turbine. The emergency governor is an unbalance spring loaded plunger. The plunger is held against its seat by the spring. Its center of gravity is off the axis of rotation in a direction which results in centrifugal forces tending to unseat the plunger. The spring is adjusted to hold the plunger on its seat up to tripping speed. At this speed, the centrifugal forces on the plunger will overcome the spring force and unseat the plunger. When the plunger axis of rotation changes, it is throw out to its fullest extent in a small fraction of a revolution. This also means the speed at which the plunger is forced in by the spring is at a speed less than trip speed (~6%) When the plunger throws out it strikes the .emergency trip mechanism actuating trigger And trips out the turbine. For test purposes, oil controlled by a valve SV6 can be sprayed into the governor housing to unbalance the plunger and trip the turbine at approximately 750/0 rated trip speed and above. This arrangement permits the over speed trip mechanism to be tested without bringing the turbine speed up to the over speed setting.JFByrd Jr 37

PROLOP MDT Controls 10/13/2010 The trip rod and trigger is just like a gun trigger shear When reset, the trip rod is engaged with the latching step of the trigger and held in place by the trip rod spring When the trigger is struck by the EG or trip lever, the trigger rotates to disengage the latching step with the trip rod. The trip rod spring forces the trip rod to extend (to the left) To reset, the trigger has a spring rotating it towards resetting (CCW), so as the trip rod is forced back, the trigger rotated to bring the latching notch into alignment with the end of the trip rod. When the force used for resetting is relaeased, the latching step is engaged to reset, the tripping lever must in normal position the height of the step and the squareness of the engagement determines the travel required to trip the trigger. you do not want a “hair trigger”JFByrd Jr 38

PROLOP MDT Controls 10/13/2010 Dump valve is connected to the trigger. With trigger latched, the oil from the relay (light red) is dead headed. When trigger is tripped, the dump valve drains the relay oil. Notice the piston on the right. SV applies oil (yellow) to cock the triggerJFByrd Jr 39

PROLOP MDT Controls 10/13/2010 When the trip rod is latched on its trigger, the trip dump valve will be moved through the connecting linkage between the trip rod and the valve to close off the oil drain ports in its cylinder. Build up of oil pressure in this line will cause the relay valve piston to move to its reset position, to open the stop valve oil supply line to pressure and the stop valve will open. When the trip rod is unlatched (trigger rotated so the rod moves off the latching step). The trip dump valve moves to open the trip circuit control oil to drain and oil pressure is released from the trip side of the 3-way relay piston and the stop valves will close. The trip rod is unlatched when the trigger is struck by the over speed emergency governor plunger or by the hand and/or hydraulic piston operated lever. When the trigger has been rotated out of its latching position by means of the hand trip, release of the trip handle will allow the lever to rotate away from the trigger, due to the action of the return spring. Spring will then cause the trigger to rotate back toward its latching positionJFByrd Jr 40

PROLOP MDT Controls 10/13/2010 If the trigger has been unlatched by trip piston, the trip rod cannot be relatched until hydraulic pressure is established under the trip piston. Resetting the tripping mechanism can be accomplished in two ways: 1) by manually pulling on the reset" handle at the turbine, or 2) By means of the hydraulic reset oil circuit with solenoid valve SV-8. Pulling on the reset handle brings a lever against a shoulder on trip dump valve and the trip rod moves to the reset position. The trigger rotates to its latching position. Then upon releasing the reset handle, the spring will move the trip rod against the latching step on the trigger, and the trip mechanism will be in its reset position. The spring will hold the trip rod on the latching step until the trigger is again rotated out of position. In hydraulic resetting, the trip rod is brought to the reset positions by momentary application of oil pressure to the resetting piston by energizing the solenoid valve SV-8.JFByrd Jr 41

PROLOP MDT Controls 10/13/2010 The governor positions the CVs this drawing is used to show the hydraulics. The lever diagram will be used to explain the governing control functionsJFByrd Jr 42

PROLOP MDT Controls 10/13/2010 The 55# supplies a continues feed to the speed setting piston with either the MGU or MSC pilot valve controlling the pistons position. A feed to the reset relay’s pilot valve the 200# supplies an orificed feed to the secondary pilot valve the 200# orifice signal from the 3-way relay to the trip dump is also supplied to the interlock valve. With trip dump reset, the interlock is shuttled to the right and ports 200# feed to the rotating pilot valveJFByrd Jr 43

PROLOP MDT Controls 10/13/2010 When the dump valve trips, the loss of pressure to the relay also goes to the interlock. The interlock shuttles to the left, draining the 200# oil that was going to the rotating pilot valve, thus tripping the CVs the oil supplied to the speed set piston, the reset relay and the secondary cylinder is not effected by the tripJFByrd Jr 44

PROLOP MDT Controls 10/13/2010 When the dump valve is reset, the signal to the interlock is drained by the interlock dump valve. This prevents the CVs from going back to an open position when the SVs open on resetJFByrd Jr 45

PROLOP MDT Controls 10/13/2010 The demand open input to the speed setting piston is reduced to CV closed. This closes the interlock dump, allowing the pressure to build in the interlock piston and force valve to the right, restoring the 200# feed to the rotating pilot valveJFByrd Jr 46

PROLOP MDT Controls 10/13/2010 200# feed inlet port not shown (purple) the reset signal come through the orifice on lower left. With the flow of the reset signal out of the interlock dead headed, the piston forces shuttled spool to the right. This ports the 200# feed out to the rotating pilot valve. AND seals off the reset flow from exiting When the reset signal pressure drops due to dump valve tripped, the forces shuttled the spool to the left. This drains the feed from the rotating pilot valve (closing CVs) AND connects the signal flow to the interlock dump once signal is reestablished, the orifice limits the pressure build up, until the interlock dump is closedJFByrd Jr 47

PROLOP MDT Controls 10/13/2010 Reviewing the trip and cross trip logic 200# signal through relay to the dump valve dump valve latch allows signal to pressurize and shuttle relay interlock 200# feed thorough relay to SVs interlock to CVsJFByrd Jr 48

PROLOP MDT Controls 10/13/2010 Dump valve trips signal drops pressure relay drains feed to SVs interlock drains feed to CVsJFByrd Jr 49

PROLOP MDT Controls 10/13/2010 Dump valve is latched signal pressure suttles relay and SVs open signal to interlock is drained by interlock dump and CVs stay closedJFByrd Jr 50

PROLOP MDT Controls 10/13/2010 Speed setting piston is lowered to demand CVs closed and also closes interlock dump signal through interlock pressurizes and shuttles interlock to port feed to CVs CVs can now be opened by increasing speed set pistonJFByrd Jr 51

GE MDT Prolop "A"

by JosephFByrdJr

Accessibility

Categories

Upload Details

Usage Rights

1 Embed 10

Statistics

GE MDT Prolop "A" Document Transcript

GE MDT Prolop "A"

by JosephFByrdJr

Accessibility

Categories

Upload Details

Usage Rights

1 Embed 10

Statistics

GE MDT Prolop "A" Document Transcript

Let LinkedIn power your SlideShare experience

Let LinkedIn power your SlideShare experience

Customize SlideShare content based on your interests

Keep up to date when your LinkedIn contacts post on SlideShare