A system for multi-stage recovery and comprehensive utilization of LNG cold energy and its application method

Abstract

The invention discloses a multi-level recovering and comprehensive utilization system of liquefied nature gas (LNG) cold energy and a using method thereof. The system comprises an LNG vaporization warming expansion main circuit, a primary rankine cycle power generation unit, a secondary rankine cycle power generation unit, a low-temperature ice-storage cooling unit, an LNG heating low-temperature heating unit and an expansion power generation unit. The LNG vaporization warming expansion main circuit is composed of an LNG storage tank (1), a pressurizing pump (2), a first condenser (3), a second condenser (8), a first heat exchanger (13), a second heat exchanger (16) and a third expansion turbine motor (19); the primary rankine cycle power generation unit is composed of the first condenser (3), a first compressor (4), a first evaporator (5), a first expansion turbine motor (6) and a first power generator (7); the secondary rankine cycle power generation unit is composed of the second condenser (8), a second compressor (9), a second evaporator (10), a second expansion turbine motor (11) and a second power generator (12); the low-temperature ice-storage cooling unit is composed of the first heat exchanger (13), a first circulation pump (14) and an ice storage tank (15); the LNG heating low-temperature heating unit is composed of the second heat exchanger (16), a second circulation pump (17) and a water heater (18); and the expansion power generation unit is composed of the third expansion turbine motor (19) and a third power generator (20).

Description

technical field [0001] The invention relates to the field of energy conversion and utilization, in particular to an LNG (liquefied natural gas) cold energy multi-stage recovery and comprehensive utilization system and a use method thereof. According to the vaporization characteristic curve of LNG, the system adopts a multi-stage recovery and comprehensive utilization method for LNG cold energy, which improves the recovery rate of LNG cold energy. Background technique [0002] With the country's increasing requirements for reducing carbon emissions and improving energy efficiency, my country's energy consumption structure will rely more on natural gas. In the future supply of natural gas, LNG from overseas will account for a large proportion. Whether it is LNG imported from overseas or LNG produced in my country, a large amount of cold energy is released during vaporization, generally 830-860kJ / kg. All countries in the world are trying to explore ways and methods to improve...

AI Technical Summary

Problems solved by technology

Due to the large release temperature span of LNG cold energy and the large difference in heat transfer temperature, the loss of cold energy is large, and it is difficult to improve the utilization efficiency of LNG cold energy. Generally, the utilization rate of LNG cold energy is only about 30%.

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