Single-stage mixed refrigerant natural gas liquefaction flow operation regulation system and method

Abstract

The invention discloses a single-stage mixed refrigerant natural gas liquefaction flow operation regulation system and method. The system is mainly composed of a compressor, condensation coolers, a multi-stream heat recover exchanger, a throttle mechanism, a controllable passageway gas phase component adjusting unit, a liquid phase component adjusting unit, a control unit and the like. The system does not need a variable frequency compressor, and the capability of dealing with external changes by the system is extremely improved. When the environment temperature changes, the opening degree of a middle throttling valve is controlled so that the working medium circulation component ratio of the system can be changed and the system can adapt to the environment changes without change of the rotating speed of a refrigerant pump; especially, when the environment temperature decreases, cold energy of the environment can be fully utilized through adjustment, and stable energy-saving operation of the system can be achieved; when raw material gas load change happens to the system, the purpose of adjusting high and low pressure and working medium flow of the system can be achieved through the controllable passageway gas phase component adjusting unit; therefore, the system can rapidly respond so as to deal with the raw material gas load change, and safe and stable operation of the system can be achieved.

Description

technical field [0001] The invention relates to the subject field of engineering thermophysics and energy utilization, in particular to a single-stage mixed refrigerant natural gas liquefaction process operation regulation system and method. Background technique [0002] The single-stage mixed refrigerant natural gas liquefaction process is widely used in small and medium-sized natural gas liquefaction stations because of its advantages such as high efficiency, simple structure, low investment cost, and convenient refrigerant replenishment. The process generally adopts multi-stage compression, and the five-component mixed working medium N2 / CH4 / C2H4 / C3H8 / iC5H12 is used for refrigeration. Like all refrigeration systems using mixed refrigerants, the performance of this process is deeply affected by the ratio of the mixed refrigerant cycle, and the actual operation is very complicated. [0003] But in fact, the single-stage mixed refrigerant natural gas liquefaction process is ...

AI Technical Summary

Problems solved by technology

When the raw material gas load decreases, if the refrigerant flow rate of the system does not decrease, the cooling capacity will be excessive, and the refrigerant temperature at the outlet of the recuperator heat exchanger will drop, which will easily reach the dew point temperature of the refrigerant cycle components, resulting in compressor humidity. Compression; when the raw gas load increases, if the refrigerant flow rate of the liquefaction system does not increase, the cooling capacity will be insufficient, so that the natural gas cannot be lowered to the required temperature

When the feed gas load changes, usually, the operator who runs the process tries to adjust the opening of the low-temperature throttle valve to change the flow of the system, but when this measure changes the flow of the system, the circulating ratio of the refrigerant components will change, since the condensing temperature has not changed at this time, we do not want the ratio of refrigerant to change

Therefore, this adjustment method that changes the circulating ratio of refrigerant components increases the difficulty and instability of system operation

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