Method of intermediate cooling of compressed gases

In a multi-stage intercooled compressor system having a plurality of compression stages connected in series with a cooling unit controlled by adjustment means between each stage, an improved method of cooling compressed gases intermediate the stages without forming condensate comprising:

• measuring the absolute humidity of the gases to be compressed at the suction side of a first compression stage which corresponds to a dew point .tau. of the gases at the suction side of the first compression stage;
• measuring the temperature and pressure of the compressed gases at the suction side of a successive compression stage designated i;
• generating a set point temperature signal on the basis of the linear equation
• T.sub.i =a.sub.i .multidot..tau..sub.a +b.sub.i .multidot.P.sub.i +c.sub.i
• where P.sub.i is the pressure of the compressed gases at the suction side of the successive compression stage designated i, and a.sub.i, b.sub.1 and C.sub.i are constants;
• generating a control signal for controlling the cooling of the gases upstream of the compression stage designated i as a function of the set point temperature signal and the actual temperature of the compressed gases at the suction side of the compression stage designated i;
• and
• using the control signal to control the adjustment signal to control the adjustment means of the cooling unit which is upstream of the compression stage designated i.