Hot-membrane co-production sea water desalination method

Abstract

The invention relates to a method for desalination of seawater by thermal membrane cogeneration, which comprises a power plant seawater cooling system, a power plant seawater desulfurization system, a power plant flue gas waste heat system, and a seawater desalination system, using the power plant flue gas waste heat to preheat seawater, and then enter the desalination system The system is used for desalination. The desalination system adopts thermal desalination system and membrane desalination system in parallel, which overcomes the shortcomings of thermal method and membrane method alone, makes full use of the waste heat of exhaust gas, meets the water demand of different regions and seasons, and reduces the fresh water consumption. Cost, reducing environmental heat pollution, the salinity of concentrated seawater after desalination is 3.5-4%, the salt production can be increased by more than 30% compared with ordinary seawater, and the cost of producing bromine is about 50% lower than that of ordinary seawater.

Description

technical field [0001] The invention belongs to the technical field of desalination of seawater, and in particular relates to a method for desalination of seawater by thermal film cogeneration, that is, a combination of thermal method and membrane method, which meets different water demands and reduces the cost of fresh water. Background technique [0002] Water is the source of life, the lifeblood of social and economic development, and a precious and irreplaceable natural resource for human beings. According to statistics, the total amount of fresh water resources in my country is more than 2.8 trillion m 3 , ranking sixth in the world, but the per capita occupancy is only 2200 m 3 , only 1 / 4 of the world average. At present, my country's water resources are facing a very severe situation. Problems such as water resource shortage, serious water pollution, and water ecological environment deterioration have become increasingly prominent, and have become the main bottlenec...

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Problems solved by technology

[0003] Seawater desalination is a high-tech that is being studied in the world today, and it is an effective way to solve the shortage of fresh water resources. Currently, the seawater desalination methods on the market mainly include thermal method and membrane method. The thermal method is to heat and evaporate seawater, and then condense the steam to obtain fresh water. The process is simple to operate, but the cost is high and the energy consumption is large

Membrane method is mainly reverse osmosis (RO) technology. Reverse osmosis method is usually called ultrafiltration method. It uses semi-permeable membrane to allow water to pass through under pressure to intercept salt and impurities. Although reverse osmosis method is energy-consuming It is 10% to 20% lower than the thermal method, but because of the large membrane resistance, a high-pressure pump is required during operation, and the membrane is expensive, has a short life, and has a 50% attenuation every year; secondly, the reverse osmosis method is related to the water quality of seawater. Whether the water quality meets the requirements directly affects the service life of the osmotic membrane; at the same time, the reverse osmosis method has high requirements for seawater pretreatment, seawater regions, and seasonal water temperature changes

[0004] In short, the high cost is currently an important factor restricting the development of domestic seawater desalination, and it is also an important reason why desalinated water cannot be promoted on a large scale

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