Abstract: Method for controlling a plural stage compressor comprising at least a first stage (10), a second stage (20) and a first inter-stage line (12) between the first stage (10) and the second stage (20), comprising the steps of: a—measuring the temperature at the inlet of the compressor, b—measuring the ratio between the outlet pressure (Pout) and the inlet pressure (Pin) of the first stage (10) of the compressor, c—calculating a coefficient (?) based at least on the value of the inlet temperature (Tin) and on the measured pressure ratio (Pout/Pin), d—if the calculated coefficient (?) is in a predetermined range, acting on a control valve (70; 76; 92) mounted in a line (4; 8) supplying the inlet of the first stage (10) of the compressor or in a gas recycle line (74) which opens into the first inter-stage line (12).

Abstract: Method for controlling a compressor comprising a last stage (40) and a compressor load controller (90), a set point outlet pressure corresponding to the consumer needed pressure, being given in the load controller (90) comprising the steps of: a—measuring the temperature at the inlet of the last stage (40), b—measuring the ratio between the outlet and inlet pressure of the last stage (40), c—computing a coefficient (?) based on the value of the inlet temperature (Tin) and on the pressure ratio (Pout/Pin), d—if the coefficient (?) is in a predetermined range, changing the set point outlet pressure by a new greater set point outlet pressure until the coefficient (?) computed with the new set point outlet pressure goes out of the predetermined range, and e—adapting the pressure of the fluid coming out of the compressor in a pressure regulator (100) to the consumer needed pressure.

Abstract: Method for controlling a plural stage compressor comprising at least a first stage (10), a second stage (20) and a first inter-stage line (12) between the first stage (10) and the second stage (20), comprising the steps of: a—measuring the temperature at the inlet of the compressor, b—measuring the ratio between the outlet pressure (Pout) and the inlet pressure (Pin) of the first stage (10) of the compressor, c—calculating a coefficient (?) based at least on the value of the inlet temperature (Tin) and on the measured pressure ratio (Pout/Pin), d—if the calculated coefficient (?)is in a predetermined range, acting on a control valve (70; 76; 92) mounted in a line (4; 8) supplying the inlet of the first stage (10) of the compressor or in a gas recycle line (74) which opens into the first inter-stage line (12).

Abstract: Method for controlling a compressor comprising a last stage (40) and a compressor load controller (90), a set point outlet pressure corresponding to the consumer needed pressure, being given in the load controller (90) comprising the steps of: a—measuring the temperature at the inlet of the last stage (40), b—measuring the ratio between the outlet and inlet pressure of the last stage (40), c—computing a coefficient (?) based on the value of the inlet temperature (Tin) and on the pressure ratio (Pout/Pin), d—if the coefficient (?) is in a predetermined range, changing the set point outlet pressure by a new greater set point outlet pressure until the coefficient (?) computed with the new set point outlet pressure goes out of the predetermined range, and e—adapting the pressure of the fluid coming out of the compressor in a pressure regulator (100) to the consumer needed pressure.