Vacuum pump calculation and puzzle solving
Thread Content
Recently, I was reading a design manual about the calculation of vacuum pumps and vacuum pipelines. There are two ideas in it to find the air pumping capacity of the vacuum pump. Should I compare these two methods and take the largest one as the basis for selection? Idea 1: Use the vacuum pipeline pressure drop to calculate. Idea 2: According to the leakage and gas production of the vacuum system. Of course, the setting conditions of these two examples are different, but if you use the second idea to calculate the first example, the two pumping volumes will be much different. Ask God to clarify my doubts.
I am not a technical person. From an intuitive perspective, your first idea is that the system continuously generates air and needs to be pumped away to maintain the system vacuum. Therefore, the pumping speed of your vacuum pump must be determined according to the pumping speed under the inlet conditions. The pump should be large. The second idea feels like pumping a sealed container. You only need to establish a vacuum and maintain it. There is no continuous air source that affects your vacuum, so you only need to consider the leakage of the sealed container, so the pump is small. If it is a reaction kettle or distillation tower that operates continuously and gas is continuously generated in the tower kettle, use the first idea. If the operation in the tower kettle is a one-kettle operation, use the second idea. I understand personally, please give me more advice.
The second method also considers the gas production of the system, 60kg/h, and adds the leakage amount on this basis.
This post was last edited by dustin0919 on 2023-3-2 13:13. The question condition in the second editing idea is "the process air extracted per hour is 60kg" which is more appropriate. At the same time, the formula (3) in step three should be 68* 8.31 * (273+30)/20/22.4=382.2m3/h. This value is the amount of gas pumped out by the vacuum pump per hour