When the steam turbine is 3000 rpm, the critical safety device trips 30

If the axial displacement is not hit to the end, the axial displacement oil pressure will be low. In addition, it is a stand-alone operation, the frequency is unstable, and the speed is sometimes high and sometimes low (it is more obvious when the electrical equipment is large and starts frequently or when the equipment is suddenly loaded, and the sudden drop of speed can be directly dragged to death with the sudden drop). Or the longer the turbine runs, the axial displacement oil pressure will slowly decrease, and finally the axial displacement safety device trips, and the load is all pressed on the other machine, which can not bear the load of the two machines, and is then dragged to death.

It doesn't have to be a critical security device issue.

When I judge a problem, I usually go to the scene and make my own conclusions after seeing the scene. However, based on the information you provided, I should judge that this should be the case.

1. Caused by the power failure of the whole plant, the action of the electric security system is caused to remove the oil pressure, and the manual security guard follows the action.

2. The DCS has a separate emergency power failure system, so that the DCS system will not work after the power failure, so there is still a time record of oil pressure. After the oil is lost, the system record can only be straight line.

3. Therefore, I judge that it is not caused by speeding, but mainly caused by the power failure of your factory itself.

The above humble opinion can only be used as a reference

It may be that the 2 machine trips due to other reasons, and the direct decrease in speed can only be explained by the fact that the main valve has been closed (otherwise the speed should be increased), and at this moment it happens that the crisis safety device is malfunctioning.

It's hard to answer questions that aren't clear.

There may be several reasons: 1. The center of gravity of the eccentric wheel needs to be adjusted (that is, the physical gap between the eccentric wheel and the critical interrupter needs to be adjusted), and the adjustment nut on the eccentric wheel before the rotation damping of the small shaft of the steam turbine is adjusted, 90 degrees and 50 revolutions (different from one manufacturer to another, see the manufacturing book); 2. The problem of the critical cut-off itself, such as pin failure, tightening failure, blocking surface failure, etc.; 3. There is a problem with the installation of the small shaft in front of the steam turbine, and the disturbance is too large; 4. Check whether the DEH of the ESC is normal for all protection logics.

One is that the clearance is too small, and the other is that the spring force is too small.

Because after the action of the critical safety device, the speed of the steam turbine gradually decreases from high, and the eccentric ring or eccentric hammer of the critical safety device has not been repositioned to the original position after flying out, at this time, if the tripper is reset, it is likely that the two will collide, so that the equipment is damaged, for the sake of safety, the tripper is generally reset when the speed drops to 90% of the rated speed.

After the critical safety device is activated, it must be reset after the speed is reduced

1: Because after the action of the critical security device, when the steam turbine gradually decreases the speed from high speed, the eccentric ring or eccentric flying hammer of the critical security device is still repositioned in the original position after flying out. Resetting the tripper at this point is likely to cause the two to collide and damage the device.

So after the action of the critical security device:;

2: When the speed is reduced to less than 3000r min, the eccentric ring or eccentric hammer can be restored to the original position. For the sake of safety, it is generally reset when the speed is reduced to 2900 rpm.

Critical Security Device Introduction:

Critical security devices are also known as critical security devices, or speeding security devices. Overspeed of the turbine-generator set can make the rotor parts bear large centrifugal force, and serious overspeed can cause damage to the unit. Therefore, at the end of the steam turbine spindle, there is an emergency safety device, when the speed reaches 110% of the rated speed, the critical safety device acts, quickly closes the high and medium pressure main valve, adjusts the valve and the exhaust backstop door, cuts off all the steam sources that may enter the steam turbine, and implements emergency shutdown.

Critical security devices are divided into flying hammer type and flying ring type.

Prevent the critical security device from not being reset, and re-hanging the gate will cause collisions between them.

Since the protection of the power plant is quite complete, the protection of the engine is even more complete. When the engine trips in an accident, the main valve that supplies steam to the steam turbine will be closed immediately (the jargon is called brake), then the speed of the steam turbine will be reduced, and the speed of reduction depends on the specific steam turbine.

Because the generator trips, the main valve and adjusting valve of the steam turbine are closed, and the speed of the unit drops rapidly.

The speed is controlled by the speed regulating valve before the parallel, and the frequency of the grid is affected by the parallel back.

3000 rpm Chinese power grid frequency, 50 rpm per second, 60 seconds is 3000 rpm, the speed of the steam turbine is controlled by the speed control system before the generator is connected to the grid, after the grid connection system frequency determines the speed, the control system controls the power.

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.

When the unit suddenly throws off the load, the speed of the steam turbine will rise rapidly, which is the largest adjustment task encountered by the speed control system, and the control system should be able to keep the speed of the steam turbine below the action value of the critical safety device. Otherwise, it will cause the action of the critical safety device, cause the steam turbine to stop or reduce the rotational speed, increase the operation before re-connection, prolong the accident processing time and even lead to the expansion of the accident. A more dangerous situation is that if the emergency security device does not operate, it may cause a speeding accident.

Generally, no, because the load carried by a single unit accounts for a very low proportion of the grid, and even if the unit trips, the impact on the grid frequency is minimal.