Method of controlling the surge limit of turbocompressors

摘要

A method and apparatus for controlling the surge limit of a turbocompressor utilizes continuously measured pressure and temperature values at the suction and outlet sides of the compressor. A relief valve connected to the outlet side of the compressor is controlled as a function of the distance between a working point and a surge limit line or blow-off line of a characteristic graph produced by characteristic graph coordinates that are computed using the pressure and temperature values. The actual value of another operating parameter that is independent of the pressure and the temperature values, such as the speed of the turbine for the turbocompressor, for example, is used. This operating parameter defines a family of characteristic lines on the characteristic graph. A set-point value for the characteristic graph coordinates is then obtained using the characteristic line of the operating parameter which passes through the working point. If the set point value thus found does not correspond to the actual value for the operating parameter, a control signal is generated which can either be used to influence the relief valve or for generating a warning signal.