Abstract: A control method and apparatus for critical rotational speed avoidance in a compressor-expander set in a gas refrigeration system. By varying an opening of an antisurge or recycle valve, a shaft power used by the compressor in the compressor-expander set may be varied, thereby varying the rotational speed of the compressor-expander set to move it away from its critical speed zone. Additionally, a feedforward signal may be provided by a compressor-expander set control system to cause an antisurge valve for a recycle compressor to open upon a trip or shutdown of one compressor-expander set.
Type:
Grant
Filed:
January 17, 2013
Date of Patent:
September 24, 2013
Assignee:
Compressor Controls Corp.
Inventors:
Saul Mirsky, Wayne Jacobson, David J. Hoogerwerf
Abstract: A control method and apparatus for simultaneously protecting a compression system from driver overpowering and turbocompressor surge. When overpowering is detected, flow rate through the each compressor in the turbocompressor train is reduced by closing an inlet throttling valve at the inlet of each respective compressor stage unless a compressor operating point is sufficiently near surge. In this latter case, the inlet throttling valve is not closed. In this way, overall flow rate through the compressor train is reduced while maintaining adequate flow through compromised stages to avoid surge.
Type:
Grant
Filed:
June 23, 2008
Date of Patent:
December 4, 2012
Assignees:
Compressor Controls Corp., Conocophillips Company
Inventors:
Saul Mirsky, Jeff McWhirter, John R. Wolflick
Abstract: Many variables in processes such as those using turbocompressors and turbines must be limited or constrained. Limit control loops are provided for the purpose of limiting these variables. By using a combination of closed loop and open loop limit control schemes, excursions into unfavorable operation can be more effectively avoided. Transition between open loop and closed loop may be enhanced by testing the direction and magnitude of the rate at which the limit variable is changing. If the rate of change indicates recovery is imminent, control is passed back to the closed loop limit control function.
Abstract: A method is disclosed for efficiently protecting dynamic compressors from surge under changing inlet conditions and in response to flow disturbances of varying size and speed. An antisurge control system based on this disclosed method will compute the relative proximity of the compressor operating point to its surge limit as a multi-variable parameter which is self-compensated for changes in gas composition, inlet temperature and pressure, compressor efficiency, guide-vane position, and rotational speed. A combination of adaptive closed- and open-loop control responses is used to maintain a margin of safety between the operating point and the surge limit. Both the safety margin and the magnitude of the open-loop response are proportional to the rate at which the operating point approaches the surge limit, thus maximizing process efficiency.
Type:
Grant
Filed:
October 26, 1988
Date of Patent:
August 14, 1990
Assignee:
Compressor Controls Corp.
Inventors:
Naum Staroselsky, Saul Mirsky, Paul A. Reinke
Abstract: A method of control for load sharing between multiple compressors working in parallel and/or in series which enables all of the load-sharing compressors to carry their optimum share of the load. This load-sharing scheme follows the safest load-sharing formula and also provides for substantial energy savings. It automatically divides the load whenever a strong decoupling between process control and compressors after the compressors' operating points cross their Surge Control lines.
Abstract: A method and apparatus for protecting a dynamic compressor from surge. The method includes a first step for providing a simultaneous control of a smaller relief means and a main control member of a dynamic compressor or the driver thereof for changing the performance of the compressor. This combined action provides for the protection from surge and at the same time insures the invariability of the main control parameters of pressure, mass flow rate to the user, or the speed of rotation. The second step provides for controlling a larger relief means and provides for antisurge protection in those cases when the first step is not sufficient to protect the compressor from surge. Apparatus is also provided for automatically implementing the method.