Compressor surge

Compressor surge is an abnormal phenomenon that causes significant damage to the compressor. Since it is generally required that surging should not occur for long periods, the impact on the temperature of the rich gas and the dry gas is not significant; however, it does have a certain effect on the pressure in the fractionation tower, and the fluctuations should also be modest. The most obvious pressure fluctuation is at the compressor outlet.

There are many factors that affect compressor surge: 1. Compressor outlet pressure; 2. Absorber tower pressure; 3. If the compressor is driven by a turbine, its speed must be kept below the critical speed.

If the inlet flow rate to the compressor is low, it can also cause compressor surge, right?

There are many factors that can affect compressor surge, but the main ones include the following: Factors: 1. Low inlet flow rate (insufficient supply). 2. High outlet pressure (high resistance downstream). 3. Fluctuations in rotational speed (fluctuations in steam pressure). 4. High back pressure (in the case of back-pressure turbines). Solutions: 1. Increase the counter-rotational momentum. 2. Increase the flow rate of dry gas leaving the device to reduce the pressure in the downstream systems. 3. Stabilize the steam pressure and adjust the rotational speed promptly. 4. Reduce the steam pressure in the system. For reference only!

The main cause of compressor surge is an excessively high compression ratio, which results from low inlet flow rate, too low molecular weight at the inlet, or excessive outlet pressure. Control the temperature of the crude gasoline tank to keep it from dropping too low. Increase the rotational speed as much as possible given the allowable reaction pressure, and keep an eye on the DV value; generally, surge should not occur. Another point is that the quality of steam must be stable; in the case of back-pressure systems, attention should also be paid to the quality at 1.0.

The reasons for compressor surge have been clearly analyzed by those upstairs. The rich gas, the pressure in the fractionation tower, and the dry gas also have an impact on the compressor: a high temperature of the rich gas can lead to severe liquid entrainment in the compressor ； The pressure in the fractionation tower directly affects the inlet pressure of the compressor; a sudden drop in this pressure can cause surging in the compressor ； Dry gas pressure directly affects the pressure in the stabilization system, which in turn influences the pressure at the compressor outlet. A high dry gas pressure results in a higher pressure in the stabilization system, and this can also cause surging in the compressor. When the compressor experiences surge, the reverse flow valve should be opened promptly.

The common types of surge in compressors include: low flow rate at the inlet； High outlet pressure ； System pressure fluctuations; the opening degree of the vent at the pressure relief inlet is too large ； Steam pressure fluctuations ； The surge in the compressor caused by these reasons has little impact on distillation and subsequent processes; it can be eliminated by quickly opening the compressor outlet to the flare. Using backflow control is also an option, but in practice, it is slow to respond; moreover, sometimes backflow control cannot eliminate surge. Another scenario is that the rich gas components become too light due to a large reaction depth or poor air-cooling effects caused by high temperatures, resulting in evacuation at the compressor inlet. This situation can cause sharp fluctuations in the reactor differential pressure, and failure to address it promptly can have serious consequences. I once encountered a case where catalyst feed was interrupted due to the pump failing to create sufficient vacuum and improper handling of the reaction process. For the compressor itself, severe surging can destroy the oil film in the bearing shells, and the intense vibration and displacement cause significant damage to these bearing shells. Another situation in which there is an excess of gas along with oil can also cause surging in the compressor. Regardless of the type of surge, it will have some impact on the entire system; however, with timely and proper handling, the stability of the units and production can be maintained.

It’s very comprehensive! However, I have really never seen evacuation or what’s known as surge caused by an excessively low molecular weight in the rich gas! The pressure drop at the rear of the absorption process has a significant impact on the compressor; I recall that in one plant, an accident occurred due to the towers for absorption and reabsorption being full, which caused pressure buildup and surge in the compressor. This post was last edited by mjl25mp6 on 2008-1-10 13:28]

Features: ① Periodic fluctuations in flow rate and discharge pressure； ②Periodic roaring sounds of airflow occur ； ③The shaft vibration of the compressor rises sharply, and the vibration in the outlet pipeline behind the machine occurs. Reason: ① The actual operating flow rate of the compressor is less than the surge flow rate. Such as excessive reduction in production volume ； Insufficient inhalation air supply ； The inlet filter is clogged, increasing pipeline resistance ； Blockages in the impeller channels or airflow channels, etc. ②The compressor outlet pressure is lower than the pipeline network pressure. Such as an increase in pipeline network pressure ； Inlet pressure too low ； The intake air temperature or gas molecular weight changes too much ； The compressor speed changes too rapidly ； The voltage increase is too fast and too abrupt ； Failure of the pipeline check valve, etc. ③Limit on the feed control valve of the heating furnace or the heat exchange control valve for recycled hydrogen. Preventing surge: ① Ensure an adequate flow rate in accordance with the process requirements, so that the compressor operates within its stable operating range ； ②Adjust the speed in a timely manner according to changes in process conditions, so as to keep the compressor’s operating point away from the surge point ； ③Measures such as exporting the gas to the atmosphere or adding a bypass return path between the inlet and outlet (by opening the counterflow valve) should be taken to ensure an adequate gas flow rate at the inlet.

In addition to low inlet flow and high outlet pressure, when dealing with surge, attention must also be paid to the flow-to-pressure ratio during operation.

The brother upstairs talked a lot and very comprehensively; I learned a lot from it. I’m new to this field and don’t know much; I’m just sharing my opinion – please forgive any mistakes! I’ve looked at many surge formulas for compressors, and after comparing them all, it seems that it’s always related to the relationship between inlet pressure and flow rate. Although surge involves many parameters, none of them are used. It is also calculated using the outlet pressure, but in the end it is converted back to the inlet pressure. Could someone please pay attention to this? Thank you!

Compressors must naturally follow the relevant calculation formulas, which are generally related to the inlet and outlet pressures as well as the flow rate. It is important to note that when performing these calculations, one should not confuse them with the parameters listed on the nameplate, as those values refer to standard conditions rather than actual operating conditions; this can lead to significant calculation errors. As for the fluctuations in pressure caused by the flow rate, this is not due to evacuation, but rather to an insufficient compression ratio of the compressor – in other words, gases with a lower molecular weight are more difficult to compress. They have a larger volume

There are many factors that affect the air compressor, and automatic control can be used to address them