Multi-effect seawater flash evaporation desalination system and working method thereof

Abstract

A multi-effect seawater flash evaporation desalination system includes a first-effect flash evaporator, a middle-effect flash evaporator and a last-effect flash evaporator. Seawater in the lower partof the last-effect flash evaporator is connected into the flash evaporation chamber of the first-effect flash evaporator through a first seawater circulation pump, a middle-effect flash evaporator condensing tube, a seawater preheating heat exchanger and a steam heater, the steam outlet of the flash evaporation chamber of the first-effect flash evaporator is connected to a water vapor compressor,the outlet of the water vapor compressor is connected to the condensation chamber of the first-effect flash evaporator through two paths, the freshwater tanks of the middle-effect flash evaporator andthe last-effect flash evaporator are connected to the spray tube of the condensation chamber of the first-effect flash evaporator through a first freshwater pump and a freshwater heat exchanger, andfreshwater in the lower part of the condensation chamber goes through a second freshwater pump, the seawater preheating heat exchanger and the freshwater heat exchanger, and then is connected into a freshwater box. The water vapor compressor recovers the steam heat of the first-effect flash evaporator and provides steam needed by heating of seawater in the steam heater , and the waste heat of freshwater in the multi-effect flash evaporators is recovered by the condensation chamber of the first-effect flash evaporator, so the running efficiency of the multi-effect seawater flash evaporation desalination system is increased.

Description

technical field [0001] The invention belongs to the technical field of electromechanical and seawater desalination, and in particular relates to a mechanical vapor recompression type multi-effect flash seawater desalination system and an operation control method thereof. Background technique [0002] With the rapid development of the global economy and the continuous growth of population, the use and demand of fresh water are increasing day by day. The scarcity of fresh water resources has become a serious problem that threatens the survival of human beings. The development of fresh water resources is imperative. 96.5% of the world's total water reserves are seawater, so seawater desalination technology is an important way to solve the shortage of freshwater resources. [0003] Currently commonly used desalination technologies include multiple-effect flash (MSF), multiple-effect evaporation (MED) and reverse osmosis (RO), among which MSF and MED are thermal methods. The rev...

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Problems solved by technology

[0006] The purpose of the present invention is to solve the problem of high operating energy consumption of multi-effect flash desalination devices, and provide a method that combines mechanical steam recompression and multi-effect flash evaporation, recovers waste heat of fresh water, raises the temperature of seawater inlet water of the first effect, and prepares 60 High-efficiency multi-effect flash seawater desalination system and method for ~100°C high-temperature fresh water

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