A cooling, electricity and fresh water cogeneration system based on lng cold energy utilization

Abstract

The invention discloses a cold electricity, gas and fresh water co-production system based on LNG cold energy utilization. The system comprises a Rankine cycle power generation system, an LNG gasification expansion system, a seawater desalination system and an intermediate refrigeration cycle system. The LNG serves as a cold source to reduce the average heat release temperature of Rankine cycle, cold energy of different temperature sections is recycled while the temperature of the mixed working medium and the LNG is increased, one part of low-temperature cold energy is provided for industrialand commercial cold consumption systems, and the other part of low-temperature cold energy is used for sea water desalination. Turbines are respectively arranged in a Rankine cycle power generation system and an LNG gasification expansion power generation system to recover cold energy and pressure energy. When LNG is normally gasified into natural gas and enters a pipeline to be sent to a user, the cold energy recovery efficiency is improved, the power generation capacity is improved, meanwhile, fresh water resources can be additionally obtained, ocean cold pollution caused by direct dischargeof seawater is avoided, the energy utilization efficiency of the system is effectively improved, and the requirements for environmental protection and energy conservation are met.

Description

technical field [0001] The invention belongs to the technical field of LNG cold energy utilization and new energy polygeneration technology, and in particular relates to a cooling, electricity, and fresh water cogeneration system based on LNG cold energy utilization. Background technique [0002] Liquefied Natural Gas (LNG) is a processed product produced to meet the needs of large-scale storage and transportation of natural gas. It is generally obtained by compressing gaseous natural gas under normal pressure and cooling it to about -162°C to condense it. After liquefaction, the volume is reduced to 1 / 625 of the original, and the mass is only about 45% of the same volume of water under gauge pressure, which provides convenience for large-scale transportation and storage, and is environmentally friendly, clean, high energy density, thermal The advantages of high value provide a guarantee for the battery life of the automobile transportation industry, and the application pros...

AI Technical Summary

Problems solved by technology

Although pure air separation precooling can greatly utilize the cold energy in the LNG cryogenic zone, it still needs to provide an additional heat source to meet the gasification of liquefied natural gas, and the recovery rate of cold energy is low

Although the equipment based on LNG direct expansion power generation technology is simple and the investment cost is low, the overall thermal efficiency is not high, and the energy recovery rate is about 25%. The average heat absorption temperature and energy recovery rate are higher than those of LNG direct expansion power generation, but the use of a single working fluid will cause serious energy loss during the evaporation process. At the same time, considering that most LNG receiving stations are built on the seashore, it is difficult to provide temperature information other than seawater. Relatively stable heat source, one is that the cryogenic cold energy in the heat absorption process of the circulating working fluid has not been rationally utilized, and the other is that the average heat absorption temperature of the cycle cannot be effectively improved

The improved LNG expansion combined Rankine cycle power generation system effectively utilizes the pressure energy contained in LNG on the basis of the Rankine cycle, and can recover more energy, but it still has not overcome the Rankine cycle power generation and recovery of LNG cold energy technology At the same time, a large amount of low-temperature seawater will be produced during the direct expansion process, which will bring more ecological problems if it is not treated

[0006] As far as the current situation is concerned, domestic LNG cold energy recovery is mainly used in the air separation industry, and there are no examples of using LNG cold energy to generate electricity. The above-mentioned scheme does not consider dividing different temperature ranges to recover LNG cold energy, and only expands power generation or It is the scheme of cooling working medium as a cold source that does not maximize the utilization of LNG cold energy

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