What is the purpose of test valve on steam turbine?

This is what it does, but I’ve never used it before. I’ll send you some photos so that everyone knows how to use it.

Each quick-closing valve on the turbine has an experimental circuit. Because under normal circumstances, the continuous operation time of the steam turbine is very long. Normally, our unit operates continuously for one maintenance cycle, that is, 2-3 years. The quick-closing valve will not operate for such a long period of time. This will cause some problems, such as rust, scaling, etc. Once these conditions occur, when the quick-closing valve action is required for protection, it may become stuck or unable to close, causing an accident. In view of the above reasons, each quick-closing valve is equipped with an experimental circuit to conduct regular or irregular valve stem flexibility experiments to ensure that the quick-closing valve can function when needed. The experimental loop is tested when the turbine is running normally. Due to the limited position, the experimental action is very short and will not cause malfunction of the valve in terms of the action principle.

5 is the on-site gate opening handle, please ask the 3rd floor 1.2.3.4 name.usage

There are a few words posted above, sorry. I have operated the experimental valve during trial operation these days, and it was fine. The valve stem formed about 1cm. When the experimental handle is turned, the valve stem moves slightly inward, and when released, the valve stem returns to its original position. Those who have never done it must be mentally burdened and afraid of the consequences. Steam turbines usually have a long operating cycle, so there are not many opportunities to get started. You must seize the opportunity to touch it during trial operation to gain direct experience. Once it is started, there will be no chance to move it. I am the team leader for this trial, and this opportunity is rare, so I will have more experience. Let’s communicate more.

The picture above is so old, you can tell from the picture that it was assembled a long time ago. Generally, current assemblies have two valves with handles, one for experimental use and one for emergency gate opening (the handle has a limiting mechanism to prevent accidental contact). The two are easy to distinguish. There are three electromagnetic reversing valves (with signal wiring on the valve body). One is an electro-hydraulic converter, which converts the electronic speed signal output by the control system into the corresponding hydraulic signal (between 0.15--0.2MPa). This volume is larger. ； The other two are electronic trip reversing valves that accept trip signals from indoors to trigger on-site quick closing valves. The above five valves are easy to distinguish based on their shapes and whether they have signal lines.

1. The poster’s picture is Hangzhou Automobile’s oil circuit control and adjustment system BLOCK 2. These buttons are starting oil pressure, quick closing oil pressure, and those with cables are electro-hydraulic converters, emergency parking handles, etc. 3. The test oil pressure enters from the rear of the quick closing valve cylinder. (The picture I sent is a Siemens II type quick closing valve. It is an old-fashioned drawing. Please give us new drawings. Updated, there is no test oil pipe and test disk) Because there are step restrictions in the test disk and piston cylinder, it can only move forward 10-20mm. In this way, the quick-closing valve is closed a little, so it does not affect the steam intake of the turbine, and the test button can be operated at any time during normal operation.

I judge that the experimental valve should be 4. Which company are you from? ?

There are many experts there. It’s an honor to have more exchanges.

The old system can only rely on experience to judge, and it is difficult to say whether it is right or wrong.

The structural diagram of the quick-closing valve on the 8th floor is a bit old. There is now an experimental piston on the right side of the piston.

There are two experimental institutions: One is the stroke test of the quick-closing valve. It is completed using handle 4, which can move the piston of the quick-closing valve by about 8 mm. It is carried out during the operation of the turbine to prevent the piston from jamming. The other is an experiment on the overspeed trip component. It is completed using handle 1 and cocks 2 and 3. The operation steps are a bit more complicated. First, press handle 1 and do not release it during the entire experiment. Its function is to connect the trip oil. Through the cooperation of knobs 2 and 3, remove the control oil leading to the overspeed trip component to simulate overspeed trip and prevent the overspeed trip component from jamming. Then restore the control oil and restore handle 1. Handle 5 is the gate handle and is not used for experiments.

The function of the test valve is to regularly move the quick-closing valve stem during normal operation of the steam turbine to prevent the quick-closing valve from forming salt. When the quick-closing valve needs to be closed, the quick-closing valve does not move or moves slowly, causing unit accidents.

Compared with imported turbines, it feels messy and hard to start.

I don’t dare to use it even though I know how to use it! Because we are afraid of what may happen. Think about it, everyone is relatively relaxed at this time when everything is running smoothly. If something goes wrong during the test, in a state-owned enterprise, do you think it is the fault of the managers or the operators? It seems that the operator's arm cannot twist the thigh. It is human nature to retreat ten thousand steps and abandon the pawn to save the car. The tests on industrial steam turbines are not as strict as those on power generation steam turbines. On the one hand, the working conditions of industrial steam turbines change frequently, the operating conditions are harsh, and the stability is not as good as that of power generation steam turbines; on the other hand, the quality of the personnel.

The thoughts above are understandable, they are all from state-owned enterprises.

The main purpose of testing the valve is to see if the valve stem is scaled? The test is carried out at any time when the quick-closing valve is fully open. Record the comparison between the test gauge pressure P2 and the nominal pressure of the quick-closing oil (this needs to be calculated). When P2>P1, it is normal. Otherwise, the valve stem is scaled. Arrange maintenance at the appropriate time.