Energy-saving low-temperature multi-effect distillation sea water desalination method

Abstract

The invention discloses an energy-saving low-temperature multi-effect distillation sea water desalination method comprising the following steps that: 2-10 effect groups are connected end to tend among effect groups, and the last evaporator 11 of the last effect group is connected with a condenser 12; raw material water is heated after entering the condenser 12 through a raw material water pump 39 and then divided into two paths, wherein one path of raw material water is discharged through a cooling water pump 40, and the other paths of raw material water is parallelly distributed into all evaporators in the last effect group through a feeding pump 46 and passes through a heater 38 before entering the first evaporator 8 in the last effect group; the strong brine evaporated by all the evaporators in the last effect group and the strong brine of the last evaporator 7 in the former effect group are gathered together and parallelly distributed into all the evaporators in the former effect group through an inter-effect pump 43 and pass through a heater 37 before entering the first evaporator 4 in the former effect group; the first effect group is operated sequentially in such a way. By using the energy-saving low-temperature multi-effect distillation sea water desalination method, the steam utilization efficiency of a low-temperature multi-effect distillation sea water desalination device can be effectively increased, the energy consumption can be reduced, and the starting time of the device can be shortened.

Description

technical field [0001] The invention belongs to the field of seawater desalination. It relates to an energy-saving low-temperature multi-effect distillation seawater desalination method. Background technique [0002] Low-temperature multi-effect distillation refers to operations performed below 70°C. Around 1981, this technology has been officially applied to industrial seawater desalination devices. It is characterized in that a series of horizontal tube falling film evaporators are connected in series, and a certain amount of steam is input through multiple evaporations and condensations. The evaporation temperature is lower than that of the previous effect, so as to obtain distilled water that is many times the amount of steam. [0003] The feed seawater is split into two streams after being preheated and degassed in the condenser. One stream is discharged back to the sea as cooling water, and the other stream becomes the feed liquid for the distillation process and is...

AI Technical Summary

Problems solved by technology

If the difference between the spraying seawater temperature and the evaporation temperature is large, the amount of secondary steam evaporated will decrease under the condition of constant heating steam, thereby reducing the efficiency of the entire desalination device, requiring a large preheating area of ​​the evaporator and high cost

The second process is equipped with a heater for each effect, so the temperature difference between the feed seawater temperature and the evaporation temperature is about 4°C for each effect, and the required evaporator preheating area is small. However, this process requires a series of flash tanks Used for flash evaporation of product water and concentrated brine, although the system efficiency is improved, but the complexity of the system is increased, and the investment cost of the equipment is very high

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