How is the anti-surge control of the main fan?
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How is the anti-surge control of the main fan?
The anti-surge valve of the main fan is not used during normal operation; it is employed only during startup/shutdown or when the main fan experiences surge.
(1) Keep the fan operating in the stable range. Therefore, fans with a p-Q characteristic curve that lacks a hump should be selected for use in the pipelines ； If the performance curve of the fan has a hump, it should be kept operating in the stable region (i.e., the descending part of the p-Q curve). (2) Recirculation is used. Some of the exhaust gas is directed back to the fan inlet, preventing the fan flow from becoming too low and causing it to operate in an unstable range. (3) Install a vent valve. When the flow rate is less than or close to the critical flow rate for surge, the vent valve is opened to release some gas, thereby reducing the pressure in the pipeline and preventing end vibration.
Semi-automatic control is generally used; when the surge point is reached, manual adjustment of the venting can be carried out to ensure the safe operation of the main fan