Low temperature multiple-effect seawater desalination evaporator and working method thereof

Abstract

The invention relates to a low temperature multiple effect seawater desalination evaporator, which is characterized in that the evaporator comprises a shell, a water distribution system, a first steam-generating bank, a second steam-generating bank, a tube plate, a mist eliminator, a fresh-water bank and a concentrated water bank; the working procedure thereof is as follows: (1) steam enters intothe first steam-generating bank, and then enters into the second steam-generating bank from the first steam-generating bank; (2) seawater enters into the shell pass of the shell of the evaporator from the water distribution system and sprays an evaporating pipe from top to bottom; (3) steam in the evaporating pipe is condensed into fresh water which is collected into the fresh-water bank; (4) seawater outside of the evaporating pipe of the first steam-generating bank evaporates to generate second steam and enters into the tube pass after passing the mist eliminator; (5) unevaporated seawater is collected into the concentrated water bank and is discharged after being preheated. The evaporator reduces the cost of the device as well as reducing rusty and aging, thus causing the room in the shell of the evaporator to be more fully used.

Description

(1) Technical field: [0001] The invention relates to the field of seawater desalination, in particular to a low-temperature multi-effect seawater desalination evaporator and a working method thereof. (two) background technology: [0002] Seawater desalination, also known as seawater desalination, is the technology and process of separating salt and water in seawater. Distillation, that is, thermal method, is the earliest seawater desalination technology and the most important method for seawater desalination. Seawater desalination by distillation is the process of heating and evaporating seawater, and then condensing the steam to obtain fresh water. [0003] Multi-effect evaporation is to evaporate the heated seawater in multiple evaporators in series. The steam evaporated from the previous evaporator is used as the heat source of the next evaporator and condensed into fresh water. This evaporation and condensation process follows a series of evaporators. The effects of th...

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Problems solved by technology

[0006] 1. The diameter of the LT-MED seawater desalination evaporator is generally relatively large. If the evaporation tube bundle is arranged in a long rectangle, the water distribution area is relatively small, and the amount of seawater sprayed on the top and base heat exchange tubes is large, forming a thick liquid film. Heat transfer and evaporation are unfavorable, and heat energy cannot be fully utilized;

[0007] 2. Due to the long spraying process of seawater from top to bottom, and the seawater is still evaporating while flowing down, the amount of seawater flowing to the bottom evaporation tube is gradually reduced, and the distribution is not easy to be uniform, resulting in the heat exchange tube at the bottom is prone to Dry wall phenomenon, easy to cause aging of heat exchange tubes;

[0008] 3. Since the heat exchange tubes at the bottom of the evaporator tube bundle are often in a dry burning state, the heat exchange area is wasted and the design capacity of the equipment cannot be reached;

[0009] 4. Since the cross-section of the evaporator shell is designed to be circular, while the tube sheet is long and rectangular, there is a lot of space inside the shell, which causes waste and increases the device cost and manufacturing cost;

[0010] 5. Since the evaporator shell is designed with a circular section, the total height of the large-scale seawater desalination device is too high, and the requirements for the bottom support and plant design are relatively high, and the infrastructure cost and installation cost are relatively high

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