Regarding the compressor surge system, our factory uses a system from Comeng.
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Regarding the compressor surge system, our factory uses a system from Comeng. What happens at the operating point, between the anti-surge line and the surge line? How will the anti-surge valve operate? Is the operating point in the surge zone? Will the surge valve open fully, or at a certain degree? Our plant’s anti-surge system is always set to semi-automatic mode; what’s the use of setting it to automatic mode?
Typical control is based on pressure, with suction pressure also being involved in some cases. If there is an excess of capacity, it should be adjusted by introducing cool air, gradually closing the anti-surge valve completely – this is the most energy-efficient approach. But one must stay away from the surge zone, and this can be determined by listening to the sound. You might as well give it a try. Self-regulation mainly involves setting the self-regulating opening degree of the anti-surge valve based on pressure control.
The design institute reminds you: fully manual means completely manual operation, and it is generally used to adjust valves during shutdown. Semi-automatic means it is partially manual – the valve opening can be set manually – but if the operating point enters the surge zone, the valve will automatically open fully, providing some level of protection. Fully automatic means completely automatic. As far as I know, this is not necessarily correct: the section between the anti-surge line and the anti-surge control line is regulated by PID. However, there is also trend control; for example, when approaching the surge line rapidly, the anti-surge valve will override the PID control and open fully. Some foreign machines also have three wires: one for surge control, one for anti-surge protection, and one for control. Between the control line and the anti-surge line, PID control is used; between the anti-surge line and the surge line, the anti-surge valve is opened fully directly.
Our factory has 2 lines: one for surge control and one for anti-surge control. Where is the control line usually located?
I said that some foreign machines have three wires. In China, it uses two wires; I think the surge control is achieved through PID control between these two wires.
Anti-surge control modes: 1. Manual mode: When the operating point falls to the left of the surge line, the unit is in a dangerous area, and manually setting the valve position has no effect. 2. Semi-automatic mode: The actual output value of the anti-surge valve is the higher of the manual and automatic output values. 3. Automatic mode: When the operating point is to the left of the anti-surge line, the PID controller automatically adjusts the valve to be open; when the operating point moves to the right of the actual anti-surge line, the PID controller automatically adjusts the valve to be closed.