Abstract: A method and apparatus are disclosed for protecting gas turbines (two- and three-shaft) from damage or destruction during dangerous transients. In this situation, fuel flow must be reduced, as needed, to keep the exhaust gas temperature below a maximum limit, thereby avoiding damage to blading in the turbine's first-stage. The dynamic action of the temperature downstream of the combustion chamber may be estimated and then used to correct the temperature measured by thermocouples. For this approach, the turbine is instrumented with an inlet pressure transmitter and an outlet temperature transmitter. The method dynamically estimates temperatures downstream of the combustion chamber and reduces the fuel flow rate if the estimated temperature approaches the temperature limit. Existing thermocouple measurements (EGT) are used as well as the pressure of air exiting the compressor (CDP) upstream of the combustion chamber.

Abstract: A method and apparatus for maintaining a main process gas parameter such as suction pressure discharge pressure, discharge flow, etc. of a compressor station with multiple dynamic compressors, which enables a station controller controlling the main process gas parameter to increase or decrease the total station performance to restore the main process gas parameter to a required level, first by simultaneous change of performances of all individual compressors, for example, by decreasing their speeds, and then after operating points of all machines reach their respective surge control lines, by simultaneous opening of individual antisurge valves. In the proposed load-sharing scheme, one compressor is automatically selected as a leading machine. For parallel operation, the compressor which is selected as the leader is the one having the largest distance to its surge control line.

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.

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 of control and control apparatus 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.