The basic principle of 8521-LC-MT is that when the unit is close to the wheezing condition, the anti-surge valve at the outlet of the compressor is adjusted so that the anti-surge valve is opened to a certain angle in order to increase the flow rate passing through the compressor internally and appropriately reduce the outlet pressure, so as to keep the working point away from the wheezing area. When the fan is ready to be put into operation, the Shaanxi Blower Factory conducts a fan characteristic test and a surge test on the fan, and the fan characteristic curve and the surge curve are derived from the measured inlet differential pressure (δp) as a function of the exhaust pressure p. The inlet pressure of the fan is then adjusted by adjusting the anti-surge valve at the outlet of the compressor so as to increase the flow rate through the compressor and reduce the outlet pressure appropriately.

8521-LC-MT has set three function generators for alarm, discharge and emergency air release in the computer. In order to ensure the safe operation of the fan, in practice, we will be parallel downward shift 2%, 7%, 10% of the wheeze line to obtain the same shape of the three curves as the anti-surge regulating system of the emergency air release line, the discharge line and the alarm line. The working principle of the system is: the inlet flow rate and outlet pressure are measured by the transmitter and sent to the computer, and the pv value of the anti-surge valve is calculated (i.e.: measured value).

8521-LC-MT were compared with the function generator to calculate the corresponding flow under the alarm value, discharge value, emergency air release value (i.e.: set value sp), when the pv value reaches the alarm value, the system sends out an alarm signal to remind the operator to pay attention to the change of working conditions; when the pv value reaches or exceeds the discharge value, anti-surge regulating system plays the role of regulating the discharge valve opens, so that the point of the working conditions to return to the discharge line below the operation; if the discharge valve is below the discharge line operation; If the discharge valve is below the discharge line, the system can not control the valve to prevent the surge. If the valve opens and still can’t make the working condition return to below the discharge line, the working condition continues to deteriorate, and when the value of pv reaches the value of emergency air release, the computer outputs a signal to make the electric air release valve open quickly to implement emergency air release.