Start-up sequence for multi-stage steam jet pumps
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Dear friends: Our units are equipped with many multi-stage steam jet pumps and multi-stage steam jet vacuum pumps. The sequence in which these pumps are started is from back to front. Why is that? What are the potential risks of driving from front to back? O(∩_∩)O Thank you all for your guidance!
This post was last edited by ylb913 on 2016-11-22 at 21:51. First, where is your exit located? Start with the one at the back first, to provide an exit for the one at the front; this way, there’s no need to worry about it damaging the equipment or anything like that.
The startup sequence for a multi-stage steam jet vacuum pump is from back to front, eliminating pressure buildup and ensuring safety. LZ, you know this principle; are you trying to tease everyone?
Knowing the result, but not finding the right reason. I’ll start on level 1 first, then move to level 2 right away – will pressure build up immediately?
I still don’t understand; I’m not very smart. I’ll start with stage 1 first, then move on to stage 2 right away. Will there be pressure buildup? (There is a condenser between stage 1 and stage 2.) Is the channel for the stage 2 injection pump not sufficient?
This is determined by the principle and characteristics of steam jet pumps. Each stage of such a pump has a designed fixed compression ratio range. Typically, the exhaust pressure of the first stage is at 1 atmosphere, with a compression ratio usually within 1:10, often around 1:7. Using this compression ratio as a basis, the exhaust pressure of each subsequent stage corresponds to the inlet pressure of the previous stage. When the pumps are operated in reverse order, this can result in an excessively high compression ratio (since the shape and size of the Laval nozzles are fixedly designed, and different steam pressures are required), which can lead to extremely dangerous situations. It’s advisable to consult professional materials on how to shut down steam ejectors first
When starting a jet pump, it is generally operated by progressing stage by stage from the last stage to the earlier ones. Start with the lowest stage first; once the starting pressure for the second-to-last stage is reached, then start that stage, and so on. Because, 1) the injector ahead cannot reach the startup pressure range for that stage; even if steam is supplied to this injector, it will not serve any purpose in evacuating air, resulting in a waste of steam, and it may even cause the steam to flow back ； 2) Opening the preceding ejector in advance reduces the effective pumping capacity of the final stage (it has to pump not only the gas in the container being evacuated but also the power steam from the ejector that was opened ahead of time), thereby prolonging the startup time!
Hello, OP! Which brand of steam jet vacuum system did you purchase? I have some technical questions