6.2.3 Hydraulic Oil System
6.2.3.1 General
The Gas Turbine Combined Hydraulic and Lift Oil system functions to provide fluid power required for operating control components and to provide lift at the Gas Turbine and Generator bearings. The control components include the Gas Valves (hydraulically actuated servo valves) and the Inlet Guide Vanes-IGV’s (positioned by a hydraulic cylinder located on the turbine base), and on Dual Fuel Gas Turbine units.
The Liquid Fuel Valve (hydraulically actuated servo valve). The major components of the system include the pumps and motors, accumulator, filters, and valves contained in the manifold assembly as shown in Figure (6.5). This document will describe how the system normally operates.
6.2.3.2 Pump Inlet and Discharge
Pressure regulated, filtered, and cooled lubrication oil from the main lube oil header in the A160 is used as the hydraulic/lift oil, high-pressure fluid. The system is designed with two redundant parallel flow paths. Under normal operation, only one circuit on the system is in use. Isolation valves are used to isolate either of the circuits so that maintenance can be performed on or off line.
On the inlet to the system, pressure switches (63HQ-6A, 63HQ-6B) signal an alarm, which prevents the hydraulic/lift pump motors (88HQ-1, 88HQ-2) from starting should there be insufficient inlet pressure. This feature will prevent the pumps from cavitations. High-pressure fluid is then pumped to the supply manifold by one of the two pressure-compensated, variable displacement pumps (PH1-1, PH2-1).
Each pump is driven by its own AC electric motor. The turbine operator controls the lead-lag sequence on the pumps. The pumps are constant pressure, variable positive displacement axial piston pumps with built in dual pressure compensators (VPR3-1, VPR3-2). The compensators act by varying the stroke of the pistons to maintain a set pump discharge. Each pump has a high and low-pressure compensator setting. The high-pressure setting is used when lift oil supply to the rotor bearings is needed. The low pressure setting is used when actuation of the gas valves and IGV’s is required.
Each pump/motor contains a heater, (23HQ-1, 23HQ-2), which prevents condensation and freezing while the motors are not running. Air bleed valves are located immediately downstream of the pump discharge to ensure rapid pressurization of the supply fluid. Each circuit contains an oil filter (FH2-1, FH2-2) with integral differential pressure switches (63HF-1, 63HF-2). Hydraulic/lift oil supply pressure relief valves (VR21-1, VR22-1) provide pressure relief in order to prevent component failure due to over-pressurization, in the event that one of the pressure compensators fail or are inadvertently set wrong.
6.2.3.3 Lift Oil Supply
Bearing lift oil is used to raise the turbine-generator rotor onto a thin, static oil film at each journal bearing to minimize rotation friction losses the gas turbine starting means or turning gear must overcome. Lift oil supply isolation valve (20QB-1) is a solenoid-operated valve. When energized, high-pressure oil is allowed to flow to each of the turbine-generator bearings. Each bearing is equipped with a flow-regulating valve to keep lift oil supply flow rate constant.
In addition, the lift oil supply lines at the bearings contain check valves to prevent bearing feed oil from back flowing into lift oil supply lines. 20QB-1 has a manual override to be used if the solenoid fails. There is also a sensing line connected from downstream of the solenoid to the compensator block.
When the solenoid is open, the sensing line is pressurized, thus selecting the high-pressure setting. Bearing Lift Oil Supply Pressure Switch (63QB-1) provides an alarm in the turbine control system if lift oil supply pressure is low, and will prevent the turning gear motor from starting should there be insufficient pressure.
6.2.3.4 Hydraulic Oil Supply
Hydraulic Supply pressure is required to actuate the gas valves, IGV’s, and liquid fuel valve (for Dual Fuel units only). Each pump circuit contains a Hydraulic Oil Supply Pressure Regulating Valve (VPR4-3, VPR4-4). These pressure-regulating valves maintain hydraulic pressure to hydraulic actuated components during normal operation, regardless of whether the pump is operating at lift pressure or hydraulic pressure.
Hydraulic Discharge Oil Supply Pressure Switches (63HQ-1A, 63HQ-1B) are used to indicate if the lead pump is not supplying enough pressure to the system. Should this be the case, the lag pump will be activated. Hydraulic Supply Low Pressure Relief Valve (VR23-2) is provided to prevent over-pressurization of hydraulic supply components in the event pressure regulating valves fail or are set incorrectly.
Off of the hydraulic oil supply header is a single Accumulator (AH1-1) that stores hydraulic fluid for use in transient's condition (e.g. valve actuation). The accumulator is in-service regardless of which pump is in operation. The accumulator contains an isolation valve and flow control valve to control recharge rate as shown in Figure (6.6). A Manual Bypass Valve allows the operator to quickly depressurize and drain hydraulic oil supply header. This is useful when resetting pump compensators, relief valves, or pressure regulators. The bypass valve also serves as an accumulator drain valve.
6.2.3.1 General
The Gas Turbine Combined Hydraulic and Lift Oil system functions to provide fluid power required for operating control components and to provide lift at the Gas Turbine and Generator bearings. The control components include the Gas Valves (hydraulically actuated servo valves) and the Inlet Guide Vanes-IGV’s (positioned by a hydraulic cylinder located on the turbine base), and on Dual Fuel Gas Turbine units.
The Liquid Fuel Valve (hydraulically actuated servo valve). The major components of the system include the pumps and motors, accumulator, filters, and valves contained in the manifold assembly as shown in Figure (6.5). This document will describe how the system normally operates.
6.2.3.2 Pump Inlet and Discharge
Pressure regulated, filtered, and cooled lubrication oil from the main lube oil header in the A160 is used as the hydraulic/lift oil, high-pressure fluid. The system is designed with two redundant parallel flow paths. Under normal operation, only one circuit on the system is in use. Isolation valves are used to isolate either of the circuits so that maintenance can be performed on or off line.
On the inlet to the system, pressure switches (63HQ-6A, 63HQ-6B) signal an alarm, which prevents the hydraulic/lift pump motors (88HQ-1, 88HQ-2) from starting should there be insufficient inlet pressure. This feature will prevent the pumps from cavitations. High-pressure fluid is then pumped to the supply manifold by one of the two pressure-compensated, variable displacement pumps (PH1-1, PH2-1).
Each pump is driven by its own AC electric motor. The turbine operator controls the lead-lag sequence on the pumps. The pumps are constant pressure, variable positive displacement axial piston pumps with built in dual pressure compensators (VPR3-1, VPR3-2). The compensators act by varying the stroke of the pistons to maintain a set pump discharge. Each pump has a high and low-pressure compensator setting. The high-pressure setting is used when lift oil supply to the rotor bearings is needed. The low pressure setting is used when actuation of the gas valves and IGV’s is required.
Each pump/motor contains a heater, (23HQ-1, 23HQ-2), which prevents condensation and freezing while the motors are not running. Air bleed valves are located immediately downstream of the pump discharge to ensure rapid pressurization of the supply fluid. Each circuit contains an oil filter (FH2-1, FH2-2) with integral differential pressure switches (63HF-1, 63HF-2). Hydraulic/lift oil supply pressure relief valves (VR21-1, VR22-1) provide pressure relief in order to prevent component failure due to over-pressurization, in the event that one of the pressure compensators fail or are inadvertently set wrong.
6.2.3.3 Lift Oil Supply
Bearing lift oil is used to raise the turbine-generator rotor onto a thin, static oil film at each journal bearing to minimize rotation friction losses the gas turbine starting means or turning gear must overcome. Lift oil supply isolation valve (20QB-1) is a solenoid-operated valve. When energized, high-pressure oil is allowed to flow to each of the turbine-generator bearings. Each bearing is equipped with a flow-regulating valve to keep lift oil supply flow rate constant.
In addition, the lift oil supply lines at the bearings contain check valves to prevent bearing feed oil from back flowing into lift oil supply lines. 20QB-1 has a manual override to be used if the solenoid fails. There is also a sensing line connected from downstream of the solenoid to the compensator block.
When the solenoid is open, the sensing line is pressurized, thus selecting the high-pressure setting. Bearing Lift Oil Supply Pressure Switch (63QB-1) provides an alarm in the turbine control system if lift oil supply pressure is low, and will prevent the turning gear motor from starting should there be insufficient pressure.
6.2.3.4 Hydraulic Oil Supply
Hydraulic Supply pressure is required to actuate the gas valves, IGV’s, and liquid fuel valve (for Dual Fuel units only). Each pump circuit contains a Hydraulic Oil Supply Pressure Regulating Valve (VPR4-3, VPR4-4). These pressure-regulating valves maintain hydraulic pressure to hydraulic actuated components during normal operation, regardless of whether the pump is operating at lift pressure or hydraulic pressure.
Hydraulic Discharge Oil Supply Pressure Switches (63HQ-1A, 63HQ-1B) are used to indicate if the lead pump is not supplying enough pressure to the system. Should this be the case, the lag pump will be activated. Hydraulic Supply Low Pressure Relief Valve (VR23-2) is provided to prevent over-pressurization of hydraulic supply components in the event pressure regulating valves fail or are set incorrectly.
Off of the hydraulic oil supply header is a single Accumulator (AH1-1) that stores hydraulic fluid for use in transient's condition (e.g. valve actuation). The accumulator is in-service regardless of which pump is in operation. The accumulator contains an isolation valve and flow control valve to control recharge rate as shown in Figure (6.6). A Manual Bypass Valve allows the operator to quickly depressurize and drain hydraulic oil supply header. This is useful when resetting pump compensators, relief valves, or pressure regulators. The bypass valve also serves as an accumulator drain valve.
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