A system for producing liquid oxygen and liquid nitrogen by cascading LNG cold energy

Abstract

The invention belongs to the technical field of air separation of LNG cold energy utilization and low cost preparation of liquid oxygen liquid nitrogen, more specifically, relates to a system for preparing liquid oxygen liquid nitrogen through gradient utilization of LNG cold energy. According to the system, a plurality of refrigerants are reasonably utilized to cool raw material air, and the airis subjected to multistage compressed, so that the energy consumption of the air separation system is greatly reduced; and meanwhile, the use amount of the ethylene glycol aqueous solution is saved, the low-grade cold energy of the LNG and the waste nitrogen is fully utilized, and the air separation cost is reduced. For a heat exchange module, the heat exchange temperature is reasonably matched, grading heat exchange is adopted, and the overall efficiency of the heat exchanger is improved; the medium-pressure rectifying tower nitrogen is used as an intermediate heat exchange medium, the risk that the natural gas enters the air separation device is avoided, and on the other hand, the high-grade cold energy can be obtained through throttling, and the power consumption of a circulating nitrogen press is relatively small. According to the system, the problems of high air separation energy consumption and serious LNG cold energy waste can be effectively solved, a high-purity liquid productis obtained, and the system has obvious social benefits and economic benefits.

Description

technical field [0001] The invention belongs to the field of air separation technology for utilization of LNG cold energy and low-cost preparation of liquid oxygen and liquid nitrogen, and more specifically relates to a system for preparing liquid oxygen and liquid nitrogen by cascade utilization of LNG cold energy. Background technique [0002] In recent years, in the face of increasing energy demand and severe carbon emission reduction pressure, countries around the world have increased the application of green fuels and the research of carbon capture and storage (CCS) technology. As a clean and efficient fossil fuel, natural gas has received extensive attention. Oxy-fuel combustion is considered to be one of the most potential technologies for large-scale carbon emission reduction in power plants. At present, the high-concentration oxygen required in oxyfuel combustion technology mainly comes from air separation. However, the energy consumption of conventional air separa...

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Problems solved by technology

[0010] In view of the above defects or improvement needs of the prior art, the present invention provides a cascaded system for producing liquid oxygen and liquid nitrogen by using LNG cold energy air separation, which fully combines the characteristics of LNG cold energy utilization, and specifically optimizes the air separation system Carry out reasonable design, and optimize the design and parameter matching of key system structures to be suitable for actual industrial production, and accordingly obtain a cascade utilization of LNG cold energy with low energy consumption for air separation and oxygen production and high utilization efficiency of LNG cold energy A system for producing liquid oxygen and liquid nitrogen by air separation, thereby solving the technical problems of high energy consumption and serious waste of LNG cold energy in the existing air separation oxygen production

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