Discussion on pipe warming experience

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The warming rate of steam turbines is usually 50 degrees per hour, in order to prevent excessive thermal stress. The drain valve for medium-pressure steam during turbine pipe warming must be opened. But as for how to effectively control low emissions, people may have different ideas on this. Here’s how I do the pipe warming process: First, I make sure that the low-pressure discharge valve is fully open. Then I slowly open the isolation valve a little at a time. Once water starts to flow out from the low-pressure discharge, and if no more water appears but steam can be seen coming out, I check the temperature gauge and open the valve a bit more. At this point, there should be some sound, and it’s likely that many small droplets of water are forming. I then wait until the temperature stops rising; at that point, when only a small amount of white dry gas can be seen coming out, I slightly close the low-pressure discharge valve for the medium-pressure steam. Generally, the temperature of the pipes will rise at this point, as closing the low-pressure discharge valve causes the pressure inside the pipes to increase slightly, reducing the amount of gas flowing out and thus lowering its flow rate while increasing the pressure. This is the principle taught in high school: high speed, low pressure, and it applies to both liquids and gases. At this time, the corresponding temperature will also rise. Turning down the low-pressure exhaust has two advantages: at this point, it’s possible to slightly open the heating pipe valve, and then turn the low-pressure exhaust down again once there is white dry gas flowing below. This helps to reduce noise, as well as prevent excessive air flow from causing stress on the pipes. This continues until the pipe warming process is complete; the valves connected to the lower section cannot be closed until the speed-up unit starts operating properly. Once it is running normally, all of the valves can be closed. I remember the first time I tried to do warm-up exercises; one of the instructors wasn’t in favor of me doing it that way. But I went ahead and did it despite the noise, and the results were very noticeable. Because the temperature didn’t rise for half an hour straight; the medium-pressure steam isolation valve was fully open, and there was a lot of noise, with no increase in temperature. The first time I closed it a little, the temperature showed a significant change.