Problems with centrifugal compressors

Reply to 1# Tianrun Fertilizer: Please specify what kind of feed gas it is and what are its components?

There must be light-component substances inside. This results in a decrease in the density of the components, thereby reducing the amount of gas drawn in. The determination of the surge point is based on the characteristics of the compressor itself; each speed corresponds to a specific surge point. Each surge point corresponds to a minimum flow rate, and surge occurs when the flow rate falls below this minimum value! There are many reasons that can cause surge, but the end result is always that the flow rate is below the minimum allowable flow rate for that speed! There are many reasons for this. First, the suction pressure is low. Second, the suction medium has changed. Third, the discharge pressure is too high, resulting in a large pressure difference between the inlet and outlet. Fourth, when shutting down the machine, the pressure is not reduced first before reducing the speed (the pressure should be reduced first, followed by a reduction in speed). Fifth, when starting the machine, the speed is not increased first before raising the pressure. There is plenty of information on this topic available on HCBBS; you can find it by searching there. You can also try searching on Baidu for “centrifugal compressor characteristic curve”; here’s a reference link: http://bbs.hcbbs.com/viewthread.php?tid=543175

The compressor is designed based on the molecular weight characteristics of the gas to be transported; if the raw material is impure, it will inevitably lead to a deviation in molecular weight, thereby causing surging.

The intake air is impure; it is estimated that the seal integrity is relatively low, allowing more air to get in, which results in insufficient air compression and thus an inadequate amount of air being drawn in. Surge occurs

Why can’t I see the reply?

It is unlikely to occur during production. Although the higher the density of the compression medium, the lower the temperature, and the smaller the flow rate, the more likely surge will be, but the variations in density, purity, and temperature are quite limited; what matters most are the gas volume and compression ratio

Why is “This post is only visible to the author”?

When designing centrifugal compressors, the average molecular weight of the medium is taken into consideration. When the cost of the medium changes, its average molecular weight also changes, thereby deviating from the original design. So it will surge.

Reply to 1# Tianrun Fertilizer: Faxing has little to do with whether the substance is pure or not; as long as the inlet flow rate and the pressure ratio between the inlet and outlet meet the requirements, faxing generally isn’t necessary! !

Surge occurs because changes in molecular weight alter the performance curve of the compressor.