Patent ID: 8939704
Filing Date: 2015-01-27
Classification: F04D

Abstract:
1. A method for operating a multistage compressor with a monitoring means for reaching of the surge limit or a defined gap from the surge limit, comprising: measuring a first measured variable at an inlet of each stage of the compressor; providing a surge limit regulator assigned to each stage comprising an evaluation module which surge limit regulator monitors each respective stage separately for the reaching of the surge limit or a defined gap from the surge limit using a reference variable which is specific for the stage; comparing the reference variable, specific for each stage, with the stage-specific first measured variable using the surge limit regulator; and determining a state of the surging when a defined gap from the surge limit is reached, wherein the reference variable is characteristic of reaching the surge limit or the defined gap from the surge limit, measuring a rotational speed and/or the angle of attack of an inlet guide vane apparatus; determining the surge limit for each stage as at least one standardized characteristic variable which is called up from an internal memory independently of an inlet pressure and/or an inlet temperature and/or a volumetric flow and/or a mass throughput and/or a longitudinal flow; measuring the inlet pressure and/or the inlet temperature and/or the volumetric flow and/or the mass throughput and/or the mass flow; determining the surge limit for each stage and each standardized characteristic variable using the measurements for an operating point; and determining the surge limit from the standardized characteristic variable for each stage which affords the greatest operating range, and fixing the surge limit of each stage by a surge limit regulator as criterion which is closest to the current operating point.