How many blocking methods are there for the low voltage security system of steam turbines?

The low-voltage security system is equipped with three redundant blocking means: electrical, mechanical and manual.

a. Electrical shutdown.

This function is achieved by a low-pressure blocking solenoid valve and a high-voltage blocking (AST) and overspeed limiting (OPC) module. The electrical blocking itself set up in this system is redundant, once the electrical shutdown signal is accepted, the low-voltage blocking solenoid valve and the high-pressure blocking solenoid valve are charged at the same time: after the low-voltage blocking solenoid valve is electrified, the oil pressure in the chamber under the spool valve of the critical cut-off is discharged, the spool valve of the critical cut-off is dropped, and then the primary safety oil on the upper part of the diaphragm valve is discharged, the diaphragm valve is opened, the secondary safety oil and the fast-closing oil are discharged, the valves are quickly closed, and the steam inlet of the unit is blocked; At the same time, the high-pressure blocking solenoid valve and the fast-closing solenoid valve are electrified, and the secondary safety oil and fast-closing oil are discharged respectively, and the main steam valve and regulating steam valve are quickly closed.

b. Mechanical overspeed protection.

The mechanical overspeed protection consists of a two-channel critical stopper, a critical cutter lever and a critical cutter slide valve. The operating speed is 110 120% of the rated speed. When the speed reaches the set value of the critical shut-off, the impactor of the critical cut-off hits out, strikes the lever of the critical cut-off, makes the spool valve of the critical cut-off fall off, drains the primary safety oil, opens the diaphragm valve, discharges the secondary safety oil and fast-closing oil, quickly closes the main steam valve and each regulating steam valve, and cuts off the steam inlet of the unit.

c. Manual shutdown.

Manually press the button of the manual shut-off valve to make the critical shut-off spool valve act, drain the primary safety oil, open the diaphragm valve, drain the secondary safety oil and fast-closing oil, quickly close the steam inlet valve, and block the steam inlet of the unit.

In addition, the system security control box is also equipped with a critical cutter test valve group, which is used for the critical cutter to do fuel injection test and speed increase test.

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turn) system functions.

1. Blocking function.

1) Mechanical overspeed protection.

When the rotational speed reaches 110 111% n. When the critical safety device should be activated, the low-pressure safety oil should be discharged, and the high-pressure safety oil diaphragm valve should be operated to open the oil drain port of the EH oil supply system, so that the anti-fuel pressure of the EH system will be reduced, and the main steam valve and regulating steam valve will be forced to close, and the unit will be shut down urgently.

2) Manual cut-off protection.

If other faults occur in the unit, the operator thinks that it is really necessary to shut down, or under normal circumstances, the emergency shut-off handle installed on the end face of the front bearing seat can be manually hit on the spot or the button can be manually cut off in the centralized control room to drain the high and low pressure safety oil and stop the unit. (3) Fuel injection test function.

In order to test the critical interrupter in the state of not overspeeding, the method of filling oil into the lower channel of the flying hammer of the critical interrupter is adopted to establish additional oil pressure, and the flying hammer is pushed to attack until it hits the hook, and the overspeed test is simulated to check whether the critical interrupter is free of jamming and good standby.

4) Steam turbine resetting function.

By manually pulling the reset handle installed on the end face of the front bearing seat or manually resetting the button in the centralized control room, the remote control reset solenoid valve can be used to reset the critical blocking throttle. At the same time, press the manual reset button in the centralized control room, and the solenoid valve will be energized and closed. (5) Critical Cut-off Control (ETS) This protection is to release the safety oil in the system through the action of the AST electromagnetic car valve after the ETS system receives the car blocking signal of the important monitoring parameters of the steam turbine, so as to close the main valve and reheat the main valve and close the high and medium pressure regulating steam valves, so that the unit can be shut down urgently.

6) Overspeed test function.

OPC overspeed protection test (103%), ETS overspeed protection test (110%), mechanical overspeed protection test were carried out under DEH control, and the maximum speed was recorded.

Electrical shutdown is redundant and is accomplished by mechanical shutdown solenoids and high-voltage blocking components. After the electrical shutdown signal is issued, ETS makes the mechanical shutdown solenoid 3YV live, and at the same time, the main blocking solenoid valve 5YV and 6YV lose power. The mechanical shutdown solenoid 3YV trips the hook of the critical blocking device through the lever of the connecting rod of the critical blocking device, and the connecting rod of the critical blocking device makes the emergency blocking valve act, cut off the oil inlet of the high-pressure security oil and open the oil discharge port of the high-pressure security oil, drain the high-pressure security oil, and quickly close the valves.

The main blocking solenoid valve loses power, directly discharges the high-pressure security oil, and quickly closes the valves.

The metal of the rotor is expected to be proportional to the centrifugal force and the number of revolutions at high revolutions, so the rotor is too high and the rotor metal is vulnerable to damage, and even the rotor is broken, so it is necessary to protect the rotor rotation in the accident state does not exceed 12% of the rated revolution, when the rotor revolution rises beyond the rated revolution, the centrifugal force square ratio increases, there is a spring on the critical blocker, when the centrifugal force of the rotor increases beyond the spring force, the critical interrupter hammer flies out, and hits the throttle of the critical interrupter to cut off the safety oil. The main valve falls down to cut off the steam source and stops to protect the turbine rotor.

The utility model relates to the verification device of the overspeed security system of steam turbine. By frame 6, the motor 7 on the frame frame, the controller of motor 8, the main shaft 9 on the frame that is connected with motor transmission, the connecting part 10 of the critical interrupter is installed at the end of the main shaft, and the instantaneous speed sensor that corresponds with the critical interrupter and is connected with the speed gauge 11'. On the main shaft, there can be a tachometer 13 and the speed sensor 14 corresponding with it and connected with the tachometer.

This test bench can simulate the operation of the critical cut-off of the steam turbine verification overspeed security system, and can replace the existing speed dynamic check test that must be completed on the steam turbine.

A type of interrupter that can clamp the side of the frame of the closed spring at a specified set position and prevent the mechanical efficiency of the switching function from decreasing.

The blocker, also known as the emergency security device, is a steam engine overspeed protection device. There is one in the front axle box on the small steam turbine, and there are two large steam turbines, which generally adopt an eccentric spring device, which acts when the steam turbine speed is 3300 3360r min, and the eccentric force is greater than the spring force, and the throttle is blocked in case of impact, and all the inlet valves are closed by leaking control oil and safety oil to protect the safety of the steam turbine;

Overhaul and dismantle mainly to do a good job of marking and measuring the size, there are springs inside, maintenance pay attention to check burrs and internal debris, and adjust the screws to rivet during installation to prevent the screws from loosening.

Generally, there is no need for maintenance, and the flying ring can be manually performed after shutdown, which should be moved; Manually cut off the throttle in a critical situation, which should be free of jamming and can be reset.

The system includes an oil supply system, an actuator and a critical shut-off system, the function of the oil supply system is to provide high pressure fuel resistance, and it drives the servo actuator, and the actuator responds to the electrical command signal sent from DEH to adjust the opening of each steam valve of the steam turbine. The critical shut-off system is controlled by the steam turbine shut-off parameters, and when these parameters exceed its operating limit, the system closes all turbine steam inlet valves, or only the regulating steam valve.

There are high-pressure oil pumps, main oil pump pipelines, oil motors.