Cold energy and waste heat comprehensive utilization system for liquefied natural gas (LNG) transport ship

Abstract

The invention relates to a cold energy and waste heat comprehensive utilization system for a liquefied natural gas (LNG) transport ship. The cold energy and waste heat comprehensive utilization system comprises a high-pressure pump, a first heat exchanger, a second heat exchanger, a third heat exchanger, a first expansion work unit and a second expansion work unit. The first heat exchanger and the second heat exchanger are sequentially connected with an outlet pipeline of the high-pressure pump. The first expansion work unit and the second expansion work unit are connected with an outlet pipeline of the second heat exchanger in parallel. According to the cold energy and waste heat comprehensive utilization system, LNG cold energy, turbine waste steam and boiler exhaust smoke waste heat are used for vaporizing liquid-state LNG to drive an expansion turbine motor to work, and a fan on a boiler is directly driven, so that not only are the LNG cold energy, the turbine waste steam and the boiler exhaust smoke waste heat used fully and comprehensively, but also a large amount of electric energy is saved. Therefore the operating cost of the ship is reduced, and the cold energy and waste heat comprehensive utilization system has very good economic efficiency and environment-friendly performance.

Description

technical field [0001] The patent of the present invention relates to the field of energy utilization, in particular to a system for comprehensive utilization of cold energy and waste heat of an LNG carrier. Background technique [0002] LNG is the abbreviation of English liquefied natural gas (liquefied natural gas). Natural gas is a clean and efficient energy source with methane as the main component. Natural gas meets the development requirements of the world's energy strategy. At present, many countries have built many LNG receiving stations, and there are about 500 LNG transport ships in operation around the world. Domestic shipping companies It owns nearly 10 large-scale LNG carriers, and leases more than 10 LNG carriers from foreign companies. With the increase in demand for natural gas, the number of LNG carriers in operation in the next 10 years will reach about 50-70. LNG carriers have unique advantages in using LNG fuel as the energy consumption of the engine roo...

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Problems solved by technology

[0005] The LNG carrier completely fueled by LNG uses the boil-off gas (BOG) generated in the cargo hold and part of the liquid LNG that is forced to vaporize during transportation. Due to the large power of the LNG carrier (take the steam power plant as an example), it needs to consume Nearly 300m 3 LNG (calculated according to liquid volume), the BOG produced in the cargo tank is about 100 m per day 3 (converted into liquid volume), so it is necessary to vaporize 150 ~ 170m 3 -163°C liquid LNG, which requires a large amount of boiler steam heat to forcibly vaporize the liquid LNG to meet the combustion needs of the boiler. In this vaporization process, not only a large amount of boiler steam heat source is consumed, but also a large amount of cold energy of LNG is wasted

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