Seawater freezing and desalting system based on liquefied natural gas cold energy and desalting method thereof

Abstract

The invention discloses a seawater freezing and desalting system based on liquefied natural gas cold energy. The system is mainly composed of an LNG (Liquefied Natural Gas) vaporizer, a refrigerant storing pot, an ice-making device, an ice-water separator, an ice slurry generator and an ice melting heat exchanger. After seawater is pre-cooled by the ice melting heat exchanger, one part of seawater enters a water-spraying type vacuum pump to supply needed negative pressure to the ice-water separator and the other part of seawater is used as raw material seawater and enters the ice-making device; a refrigerant is cooled by the LNG vaporizer and then is sprayed into the ice-making device to finish direct contact type heat exchange with the seawater; after the heat exchange, the refrigerant is pumped into the LNG vaporizer again through a refrigerant outlet; ice slurry generated after the seawater is frozen enters the ice-water separator form an ice slurry outlet and separated ice crystals enter the ice melting heat exchanger via the ice slurry generator; and finally are heated and melted into fresh water by the seawater. The seawater freezing and desalting system based on the liquefied natural gas cold energy, disclosed by the invention, can sufficiently utilize the cold energy of the LNG in the vaporizing process to freeze and desalt the seawater, so that the utilization rate ofthe cold energy of the LNG is improved and the economic and environmental benefits of seawater desalting can also be improved.

Description

technical field [0001] The invention relates to a water treatment and desalination technology, in particular to a seawater freezing and desalination system and a desalination method utilizing the cold energy of liquefied natural gas. Background technique [0002] With the increasing awareness of environmental protection in various countries, the world's energy structure has gradually changed, and natural gas has become one of the clean energy sources that human beings focus on developing and utilizing. In order to meet energy demand, countries have successively built a number of liquefied natural gas (LNG) receiving stations in their coastal cities to complete LNG storage, distribution, gasification, transmission, peak shaving and other processes. In the process of LNG transmission, the receiving station generally needs to use seawater to heat and evaporate LNG into gaseous natural gas through a vaporizer, and then transport it through pipelines for users. LNG will release ...

AI Technical Summary

Problems solved by technology

LNG will release a large amount of cold energy (about 830kJ / kg) during the gasification process. This part of cold energy is usually discarded directly with the discharge of seawater, which not only causes waste of LNG cold energy, but also causes low temperature discharge. Sea water will also have certain environmental impacts on surrounding sea areas

[0003] At the same time, with the development of my country's economy and the improvement of people's living standards, the demand for fresh water is increasing, and the requirements for water quality are also getting higher and higher. Exploitation, unrestrained waste and random discharge of pollution have exacerbated the already tense contradiction between supply and demand of water resources. The lack of fresh water resources has become a bottleneck restricting my country's economic development and social progress.

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