Abstract: A method is described for providing antisurge control in a system comprising a compressor having at least an upstream compressor stage, a downstream compressor stage and a side stream bringing flow into a flow passage between the upstream compressor stage and the downstream compressor stage. The method provides for estimating a temperature of a flow delivered by the upstream compressor stage using a non-dimensional performance map of the upstream compressor stage and further estimating a temperature of a flow entering the downstream compressor stage based on the mass flow and flow temperature of the flow delivered by the downstream compressor stage and the mass flow and the flow temperature of the side stream. The method further provides for performing antisurge control of the downstream compressor stage based on the temperature of the flow entering the downstream compressor stage.

Abstract: A method for anti-surge protection of a compressor under wet gas conditions is described. The compressor includes a suction side and a delivery side. An anti-surge system is arranged between the delivery side and the suction side of the compressor. The method includes: calculating a surge limit line in a compression ratio vs. corrected power diagram; determining a compressor operating point in the compression ratio vs. corrected power diagram; detecting a distance between the operating point and the surge limit line; acting on the anti-surge system of the compressor if the distance is below a minimum safety distance.

Abstract: A method for operating a compressor. The method includes: acquiring a plurality of measured data; verifying the congruence of the measured data through the calculation of the molecular weight of the compressed gas based on compressor adimensional analysis; in case of failure of a first measurement of the measured data, substituting the first measurement with an estimated value based on the last available value of the molecular weight and on the available measurements of the measured data and on compressor adimensional analysis; and determining an estimated operative point on an antisurge map based on the estimated value and on the available measurements of the measured data.

Abstract: A method for detecting rotating stall in a compressor is disclosed herein. The method comprises measuring radial vibration of the rotor relative to the stator and generating a vibration measurement signal, calculating a frequency spectrum of the vibration measurement signal, identifying a plurality of frequency bandwidths of the frequency spectrum, neglecting one first frequency bandwidth of the plurality of frequency bandwidths if the rotation frequency of the rotor falls within the first frequency bandwidth, neglecting at least one second frequency bandwidth of the plurality of frequency bandwidths if the rotation frequency of the rotor falls below the second frequency bandwidth, determining the maximum magnitude of the spectrum in each of the non-neglected frequency bandwidths, and comparing each determined maximum magnitude and a predetermined value.

Abstract: A method for regulating a turbocompressor to prevent surge, is described. The method comprises the following steps: providing at least one surge limit line of turbocompressor; continuously determining an actual value of a corrected speed of the turbocompressor; continuously determining at least a maximum admissible pressure ratio on the surge limit line, corresponding to the actual value of the corrected speed; continuously determining an actual pressure ratio; acting upon an antisurge arrangement, if the actual pressure ratio is equal to or higher than the maximum admissible pressure ratio.

Abstract: A method is described for providing antisurge control in a system comprising a compressor having at least an upstream compressor stage, a downstream compressor stage and a side stream bringing flow into a flow passage between the upstream compressor stage and the downstream compressor stage. The method provides for estimating a temperature of a flow delivered by the upstream compressor stage using a non-dimensional performance map of the upstream compressor stage and further estimating a temperature of a flow entering the downstream compressor stage based on the mass flow and flow temperature of the flow delivered by the downstream compressor stage and the mass flow and the flow temperature of the side stream. The method further provides for performing antisurge control of the downstream compressor stage based on the temperature of the flow entering the downstream compressor stage.

Abstract: A method for operating a compressor. The method includes: acquiring a plurality of measured data; verifying the congruence of the measured data through the calculation of the molecular weight of the compressed gas based on compressor adimensional analysis; in case of failure of a first measurement of the measured data, substituting the first measurement with an estimated value based on the last available value of the molecular weight and on the available measurements of the measured data and on compressor adimensional analysis; and determining an estimated operative point on an antisurge map based on the estimated value and on the available measurements of the measured data.

Abstract: Methods and devices for performing a model based anti-surge dead time compensation in systems including a compressor and an anti-surge loop are provided. A new position of an anti-surge valve on the anti-surge loop is determined by correcting for dead time a value of the anti-surge parameter calculated from field measurements, based on a predicted anti-surge parameter estimated using a deterministic model which has as variables the field measurements and a current position of the anti-surge valve.

Abstract: Methods, systems and controllers for detecting a surge event based on pattern of evolution of a discharge pressure of a compressor, and for relocating a surge margin relative to a surge parameter value recorded at the beginning of the surge event are provided. A controller has an interface configured to receive values of the discharge pressure from a compressor, and to output signals and alarms, a surge event detection unit connected to the interface and configured to detect a surge event in the compressor based on evolutions of the discharge pressure, a rate of the discharge pressure and a rate change of the rate, and a surge margin relocation unit connected to the surge event detection unit and the interface, and configured to relocate a surge margin relative to a surge parameter value recorded at a beginning of the surge event.

Abstract: Methods and devices for performing a model based anti-surge dead time compensation in systems including a compressor and an anti-surge loop are provided. A new position of an anti-surge valve on the anti-surge loop is determined by correcting for dead time a value of the anti-surge parameter calculated from field measurements, based on a predicted anti-surge parameter estimated using a deterministic model which has as variables the field measurements and a current position of the anti-surge valve.

Abstract: Methods, systems and controllers for detecting a surge event based on pattern of evolution of a discharge pressure of a compressor, and for relocating a surge margin relative to a surge parameter value recorded at the beginning of the surge event are provided. A controller has an interface configured to receive values of the discharge pressure from a compressor, and to output signals and alarms, a surge event detection unit connected to the interface and configured to detect a surge event in the compressor based on evolutions of the discharge pressure, a rate of the discharge pressure and a rate change of the rate, and a surge margin relocation unit connected to the surge event detection unit and the interface, and configured to relocate a surge margin relative to a surge parameter value recorded at a beginning of the surge event.