Two-effect scale-preventing evaporating and crystallizing device used for evaporating sodium chloride solution and operation method

Abstract

The invention provides a two-effect scale-preventing evaporating and crystallizing device used for evaporating and crystallizing sodium chloride solution, comprising a two-effect multiphase flow evaporator, a vacuum system and a connecting pipeline, wherein a first effect is a natural circular evaporator, a second effect is a natural circular evaporating crystallizer; a material delivering device is arranged between two effects; and the second effect is provided with a grain circulating device. Specially-made aluminum oxide and polytetrafluoroethylene composite material grains are added in the two-effect evaporating and crystallizing device; the grain density is 1200-3000kg / m3, the grain diameter is 0.32-3.8 mm, and the specific heat is 0.5-1.5kJ / kg.K. The sodium chloride crystal is prevented from attaching on the wall face of the heating pipe in the process of evaporating, simultaneously, the heat transmission is enhanced. The two-effect scale-preventing evaporating and crystallizing device has the characteristics of being simple in structure, likely to operate, capable of running continuously and preventing scaling; the two-effect scale-preventing evaporating and crystallizing device can be used for evaporating and crystallizing the sodium chloride solution and the sodium chloride waste liquid in chemical industry, medicine, sea water chemical industry and the other fields.

Description

technical field [0001] The invention relates to an evaporation crystallization technology, in particular to a two-effect anti-scaling evaporation crystallization device for evaporating sodium chloride solution and an operation method thereof, belonging to the field of evaporation crystallization. Background technique [0002] During the evaporation and crystallization process of sodium chloride solution, the crystals produced after the sodium chloride solution is concentrated are easy to adhere to the inner wall of the heating tube to form scaling, which seriously affects the heat transfer and evaporation effects. In order to prevent the scaling of sodium chloride in the heat exchange tubes, multi-effect forced circulation evaporators, reverse circulation evaporators, etc. are widely used at present, but scaling is still inevitable, and frequent cleaning is required, and the cleaning cycle even reaches once or several times a week . [0003] The patent "on-line high-efficie...

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Problems solved by technology

The patent "Ebullating Evaporator with Enhanced Heat Transfer and Anti-fouling Performance and Operation Method" (ZL96120008.1) provides a forced circulation ebullient evaporation device with two separation chambers for two-effect and three-effect operation The structure is complex and the operation is difficult to control

Both of the above two patents mentioned that in the anti-scaling process, the method of adding inert solid particles can be used to operate, but the physical properties of the solid particles used are not clear, and the particles may be corroded by the feed liquid. The application range is not wide, and it is not suitable for chlorine-containing During the evaporation and crystallization process of sodium chloride solution, there is no in-depth study on the problem of blocking the feeding device by particles or larger scale pieces that may be generated during the two-effect operation

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