초록 ▼

A supervisory computer for a centrifugal compressor control system is disclosed which manipulates the set point of a controller for a valve in a recycle line from the compressor systems outlet to inlet. The supervisory computer manipulates the set point so as to both prevent surging and substantiall

A supervisory computer for a centrifugal compressor control system is disclosed which manipulates the set point of a controller for a valve in a recycle line from the compressor systems outlet to inlet. The supervisory computer manipulates the set point so as to both prevent surging and substantially minimize the recycling of compressed gas. The computer first determines the surge flow limit for the compressor based on prestored data from the compressors manufacture performance curves such as constant speed compressor curves, and the actual speed of the compressor. The controller then outputs a set point signal which periodically moves the control valve in incremental amounts toward the fully closed position. The periodic movement towards the closed position continues until the flow is close to the surge flow limit, or until the actual deviation of the setpoint flow and the actual process flow exceeds a desired high limit for this deviation. When the constraints are exceeded the controller periodically moves the control valve toward the fully open position until the constraints are satisfied, and then the cycle repeats.

대표청구항 ▼

A method of controlling a compressor system in which a minimum flow controller and an associated control valve manipulate gas flow in a recycle stream from the discharge outlet to the suction inlet of said compressor system, said method comprising the steps of: (a) establishing a first signal repres

A method of controlling a compressor system in which a minimum flow controller and an associated control valve manipulate gas flow in a recycle stream from the discharge outlet to the suction inlet of said compressor system, said method comprising the steps of: (a) establishing a first signal representative of an actual flow rate of compressed gas in said compressor system; (b) establishing a second signal representative of a desired minimum value for said actual flow rate represented by said first signal wherein an initial value is established for said second signal and further wherein said second signal is a periodically updated signal having a current value and then one time period later having an updated value; (c) comparing said first signal and the current value of said second signal to establish a third signal representative of the deviation of said first signal from the current value of said second signal; (d) establishing a fourth signal representative of a high limit for the deviation represented by said third signal; (e) comparing said third signal and said fourth signal to determine if a deviation constraint has been violated wherein an incremental value is added to the current value of said second signal if said third signal is greater than said fourth signal, and wherein said incremental value is subtracted from the current value of said second signal to establish the updated value of said second signal if said fourth signal is greater than said third signal; and (f) manipulating the flow rate of said recycle stream in response to said updated value of second signal.