Device for producing hydrated lithium hydroxide on basis of MVR and production method thereof

Abstract

The invention discloses a device for producing hydrated lithium hydroxide on the basis of MVR. The device includes a raw material tank, a condensate water preheater, a vapor preheater, a forced circulation evaporator, a thickener, a centrifugal machine, a compressor and a vapor separating bag. Raw materials in the raw material tank are conveyed into the condensate water preheater through a feedingpump, and the condensate water preheater is communicated with the vapor preheater through a pipe; the raw materials in the vapor preheater are conveyed into the forced circulation evaporator througha pipe, and the forced circulation evaporator comprises a first heater, a second heater and a crystal separator. The device has the advantages that the interior of a heat exchanging pipe of a forced circulation heater is polished, the adhesive force of crystals adhering to a wall in a solution can be effectively reduced, it is ensured that the flow velocity of the solution in the heat exchanging pipe can reach 2.5 m / s or above, and meanwhile the pipe wall is flushed to further reduce the scaling frequency in the heat exchanging pipe; at the same time, the superheat degree of an outlet of the heater is lowered, flash evaporation and pipe blockage are effectively prevented from occurring in the pipes, and a pipe blockage situation caused by locally massive crystallization due to an excessively high superheat degree is reduced.

Description

technical field [0001] The invention is an MVR-based device for producing hydrated lithium hydroxide and a production method thereof. Background technique [0002] Lithium is the main element of new energy battery materials, and now the world's demand for lithium is doubling, especially in China. This has led to the massive production of hydrated lithium hydroxide. [0003] The traditional process of generating hydrated lithium hydroxide generally uses a traditional three-effect evaporation system to evaporate and crystallize lithium hydroxide solution to crystallize hydrated lithium hydroxide. Since the lithium hydroxide solution is strongly alkaline, it is easy to foam during the evaporation and crystallization process, especially in the state of traditional multi-effect high heat transfer temperature difference, the foaming is particularly serious. At the same time, the system is very easy to form blocked pipes, which affects the heat transfer of the heat exchanger, red...

AI Technical Summary

Problems solved by technology

Since the lithium hydroxide solution is strongly alkaline, it is easy to foam during the evaporation crystallization process, especially in the state of traditional multi-effect high heat transfer temperature difference, the foaming is particularly serious

At the same time, the system is very easy to form blocked pipes, which affects the heat transfer of the heat exchanger, reduces the evaporation performance of the system, and leads to energy waste.

[0004] In recent years, many manufacturers are also trying to use mechanical vapor recompression evaporation crystallization technology (MVR) to produce high-quality lithium hydroxide hydrate, but the results are not very satisfactory

The main reason is that during the evaporation process of hydrated lithium hydroxide, the secondary steam entrains a large amount of foam (containing lithium hydroxide), which cannot be effectively removed, resulting in a strong alkaline pH of the condensed water, and further recovery of lithium hydroxide in the condensed water is required

Improper selection of the evaporation temperature leads to the precipitation of hydrated lithium hydroxide attached to the wall of the heat exchange tube during the heating process of the lithium hydroxide solution in the heat exchange tube, resulting in a decrease in the heat transfer performance of the heat exchange tube, affecting production, and making it impossible to achieve long-term continuous production

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