Industrial waste heat type low-temperature multi-effect sea water desaltation system and sea water desaltation method thereof

Abstract

The invention discloses an industrial waste heat type low-temperature multi-effect sea water desaltation system and a sea water desaltation method. The system comprises a flue gas waste heat recovery device used for preparing heat source steam and preheating seawater and a low-temperature multi-effect sea water desaltation device which utilizes the heat source steam to realize sea water desaltation treatment; the low-temperature multi-effect sea water desaltation device comprises a first-effect evaporator, a plurality of intermediate-effect evaporator, a final-effect evaporator and a condenser; the condenser is connected with a vacuum-pumping device; the first-effect evaporator is connected with a feeding seawater pipe on which a plurality of preheaters are serially arranged; a fresh water pipe between every two adjacent evaporators penetrates the preheaters. According to the invention, in-order water supply is adopted, so that the scaling and corrosion problems are solved, equipment cleaning and maintenance are reduced, and therefore the sea water desaltation cost is low; the low-temperature multi-effect sea water desaltation device is combined with exhaust heat utilization, so that comprehensive resource utilization is realized, the flue gas discharge temperature is lowered, the desulphurization efficiency is favorably improved and emission of pollutants is reduced.

Description

technical field [0001] The invention relates to the technical field of seawater desalination treatment, in particular to an industrial waste heat type low-temperature multi-effect seawater desalination system and a seawater desalination method thereof. Background technique [0002] Seawater desalination is the use of seawater desalination to produce fresh water. It is an open source and incremental technology to realize the utilization of water resources. It can increase the total amount of fresh water and is not affected by time, space and climate. It can ensure the stable water supply needs of coastal residents for drinking water and industrial boiler replenishment. The coastal area is mainly saline-alkali land, and the groundwater is all brine. At present, residents mainly rely on long-distance water supply from other places. With the rapid development of coastal areas, fresh water resources will become increasingly scarce, and the promotion of seawater desalination is an...

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Problems solved by technology

[0004] The current low-temperature multi-effect distillation seawater desalination technology mostly adopts the horizontal tube falling-film evaporator imported from abroad, and there is a transfer valve between each adjacent two-effect evaporator for transferring seawater from the low-temperature effect evaporator to the high-temperature effect evaporator. The material pump, that is, the feed seawater first enters the final effect evaporator, passes through the intermediate effect evaporator step by step through the transfer pump, and finally enters the first effect evaporator. It adopts the reverse water supply method, and the existing problems are: on the one hand , since the feed seawater is from the final effect evaporator to the first effect evaporator, it must be transferred by the material transfer pump. The setting of the material transfer pump will increase the cost of the entire seawater desalination equipment; From the low temperature effect to the high temperature effect, the seawater temperature gradually rises, it is easy to cause scaling and corrosion in the high temperature effect, the cleaning and maintenance are cumbersome, and the service life of the equipment is affected

[0005] In addition, the heat source steam used in the current low-temperature multi-effect distillation seawater desalination technology is usually commercial steam, which is expensive, resulting in high cost of seawater desalination. The applicant company is engaged in the production of calcined petroleum coke, which produces 1,000 The high-temperature flue gas around ℃, after the waste heat is recovered by the flue gas waste heat boiler, the temperature of the exhausted flue gas is still as high as 200°C-220°C, which still contains considerable recoverable waste heat, and the flue gas itself needs to be desulfurized before the flue gas desulfurization Cooling; therefore, it is necessary to fully recycle this part of the recyclable waste heat to produce the heat source steam required for seawater desalination treatment and preheat the feed seawater, which can not only reduce the cost of seawater desalination, but also achieve the goal of flue gas desulfurization. The purpose of cooling

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