ANTI-SURGE METHOD AND DEVICE FOR COMPRESSOR Russian patent published in 2000 - IPC

FIELD: axial-flow and centrifugal compressors for gas-transfer units. SUBSTANCE: method involves measuring gas pressure downstream and upstream of compressor, pressure drop across contraction, rotor speed, and pressure drop across compressor; initial pressure drop across compressor, pressure drop across contraction, and rotor speed are recorded and entered in computer memory. Then current values of these variables are compared with recorded values and if the former are higher than the recorded ones, these current values are recorded and entered in memory as new values thereby updating computer memory. If current value of pressure drop across compressor is not higher than that recorded , that across contraction is lower than recorded value, and rotor speed value is not lower than that recorded, first anti-surge signal is shaped. In case of too low rotor speed, difference between its current and recorded values as well as between current and recorded values of pressure drop across contraction are continuously determined; then ratio of difference in pressure drop across contraction to difference in rotor speed is calculated. After rotor speed has reduced to threshold value, this ratio is recorded and compared later on with current value including coefficient of hydrodynamic characteristic slope at surge boundary. When current value exceeds difference function entered in memory earlier, second anti-surge signal is shaped with the result that general surge alarm signal is generated. Device implementing this method has sensors responding to gas pressure downstream and upstream of compressor, to pressure drop across contraction and rotor speed, subtraction circuit, and OR gate; newly introduced in device are four comparison circuits, OR gate, five memory items, two flip-flops, three AND gates, and computing circuit with relevant ties. EFFECT: improved reliability of surge identification and automatic determination of surge characteristic dispensing with developing unique hardware. 2 cl, 3 dwg