초록 ▼

A computer-based system and method detects and specifies valve and ring leaks in reciprocating compressors of the type used in natural gas transmission networks. The system employs a method comprising the following steps. The cylinder pressure is measured as a function of cylinder volume to obtain a

A computer-based system and method detects and specifies valve and ring leaks in reciprocating compressors of the type used in natural gas transmission networks. The system employs a method comprising the following steps. The cylinder pressure is measured as a function of cylinder volume to obtain a measured PV card. A predictive model then calculates a predicted PV card for the subject compressor cylinder without including effects of simulated leaks. The predicted PV card is them compared to the measured PV card. The nature and character of the differences between the measured and predicted PV cards indicates whether a leak in the subject compressor cylinder is a suction valve leak, a discharge valve leak, or a piston ring leak. The predictive model is then iterated with simulations of the indicated leak included until the resulting predicted PV card matches the actual measured PV card for the compressor cylinder. The final value of the leak parameters in the model required for the match indicate the nature and magnitude of a corresponding actual leak in the compressor cylinder. Other useful information such as the efficiency of the compressor system with and without the leak and the economic impact of the leak are also derived from the iterative match process.

대표청구항 ▼

A computer based method of detecting and specifying leaks in a reciprocating compressor cylinder having a suction valve, a discharge valve, a reciprocating piston, and piston rings, said method comprising the steps of: (a) operating the compressor cylinder to generate time varying pressure as a func

A computer based method of detecting and specifying leaks in a reciprocating compressor cylinder having a suction valve, a discharge valve, a reciprocating piston, and piston rings, said method comprising the steps of: (a) operating the compressor cylinder to generate time varying pressure as a function of cylinder volume within the cylinder; (b) sensing the pressure within the operating cylinder at predetermined intervals of cylinder volume and generating signals indicative of the sensed pressures; (c) converting the generated signals to digital data representing the characteristic measured pressure versus volume function for the operating compressor; (d) conveying the digital data to a computer-based control means; (e) in the computer-based control means, simulating operation of the compressor cylinder with a predictive analytical model that includes simulations of the effects of leaks in the compressor elements to produce a predicted pressure versus volume function for the compressor, the measured and predicted pressure versus volume functions each exhibiting a compression line and a re-expansion line with a region of difference being defined between the re-expansion lines of the measured and predicted functions and between the compressor lines of the measured and predicted functions; (f) subdividing in pressure/volume space the region of difference between the re-expansion lines of the measured and predicted functions into subregions S1 and S2, subregion S1 being bounded by the measured and predicted re-expansion lines, by a constant volume line at the volume where maximum pressure on the measured re-expansion line occurs, and by a constant volume line at the volume where measured pressure is midway between the minimun and maximum pressure on the measured re-expansion line, subregion S2 being bounded by the measured and predicted re-expansion lines, by a constant volume line at the volume where measured pressure is midway between the minimum and maximum pressure on the measured re-expansion line, and by a constant volume line at the volume where minimum pressure occurs on the measured re-expansion line, and subdividing the region of difference between the compression lines of the measured and predicted functions into subregions S5 and S6, subregion S5 being bounded by the measured and predicted compression lines, by a constant volume line at the volume where minimum pressure occurs on the measured compression line, and by a constant volume line at the volume where measured pressure is midway between the minimum and maximum pressure on the measured compression line, subregion S6 being bounded by the measured and predicted compression lines, by a constant volume line at the volume where measured pressure is midway between the minimum and maximum pressure on the measured pressure line, and by a constant volume line at the volume where maximum pressure occurs on the measured compression line, the areas of each of the subregions S1, S2, S5, and S6 being positive if measured pressure is greater than predicted pressure in the subregion and negative if measured pressure is less than predicted pressure in the subregion. (g) analyzing the areas of subregions S1, S2, S5, and S6; (h) determining based on the results of step (g) the nature of changes in simulated leaks within the predictive analytical model that likely would cause a desired change in the areas of and relationships between the subregions S1, S2, S5, and S6; (i) changing the simulated leaks within the predictive analytical model according to the determination of step (h); (j) repeating steps (e) through (i) until, in step (d), the areas of and relationships between subregions S1, S2, S5, and S6 meet a predetermined criteria; (k) analyzing the final valves of the simulated leaks to predict and specify the nature of probable actual leaks present in the compressor cylinder; and (l) determining a course of remedial repairs to be performed on the compressor cylinder based upon the predictions and specifications of step (k).