Regarding the anti-surge curve

Surge is an abnormal operating condition specific to centrifugal compressors. Generally, large centrifugal compressors require a surge curve to be created. The surge curve is the result obtained when a centrifugal compressor experiences surge. That is: the pressure-flow curve. There is a corresponding flow rate at the corresponding pressure. When it falls below this corresponding value, the unit will surge. Therefore, when a point moves back and forth, it is actually the operating system such as PLC or DCS that determines the flow rate corresponding to the current operating pressure (as specified in the surge test); if the flow rate indicated by the flow meter is lower than this value, the surge valve opens and the unit enters a surge condition.

The anti-choke curve is usually prepared by the compressor manufacturer, and once it’s ready, it can be directly inserted into the ITCC.

May I ask the original poster, how did you see the surge line?

1. Some compressors are controlled by DCS, and accordingly, there are relevant operation interfaces on the DCS control panel. Note: This screen can only be viewed; it cannot be modified! 2. If PLC control is used, the surge curve can also be accessed from the PLC’s on-site operation menu. Note: This screen can only be viewed; it cannot be modified!

The operating point of the compressor must be within the surge line; otherwise, it may enter a state of surge

The back-and-forth movement of the surge prevention curve is related to the surge flow rate as well as the compressor’s speed and the temperature and pressure of the medium.

That point should represent the immediate operating condition of the compressor. The curve has been prepared; there is a surge line, which is shown in red here, as well as a visual warning line, which is a yellow line. Once the operating point reaches the yellow line, the surge valve will open, and when it reaches the red line, there is a risk of surge occurring. During normal operation, the inlet flow rate and pressure are constantly changing, so the state point also moves. Since the operational data are calculated by the design institute, the calculated values represent only ideal values; actual values generally fluctuate around these values. As long as the operating conditions are normal, there won’t be a significant deviation, and thus surge should not occur. Personally, I think the compressor should be designed by the design institute based on the process requirements, which are then conveyed to the compressor manufacturers for development and production. Large-scale chemical investments are indeed substantial; given the current market conditions, the return on investment isn’t very good. Our factory produces methanol from coal

The anti-surge systems for each set of units are described in detail in the accompanying documents; the original poster can refer to those documents!

This post was last edited by yelian*ang202 on 2009-5-26 22:43 ----- Generally, pressure ratio is used as the vertical axis and flow rate as the horizontal axis; when the flow rate changes, even if the pressure remains constant, the operating point will change. -----Surge control generally involves two lines: a control line and a surge line. When the operating point approaches the control line, the anti-surge valve starts to act in order to move it away from the surge line. If the operating point continues to move toward the surge line, the anti-surge valve opens further, with the aim of increasing the flow rate and reducing the pressure. -----There are only two conditions for surge to occur: low flow rate and high pressure ratio. -----Surge often occurs when the compressor is started; at that time, although the pressure ratio is low, the flow rate may be insufficient, especially in multi-stage compression. Furthermore, low inlet pressure can easily lead to surge.

Urgent: Why can’t I see the chart? What problem? Could someone with experience tell me? ? ?

Stall prevention control means that, regardless of the compressor’s compression ratio, it is necessary to ensure that the inlet flow rate to the compressor is greater than the stall flow rate; only in this way can the compressor operate stably. Currently, two types of anti-surge methods are commonly used, namely the fixed limit flow rate (or minimum flow rate) method and the variable limit flow rate method.