Method of continuous evaporation crystallization and production method of anhydrous citric acid crystal

Abstract

The invention provides a method of continuous evaporation crystallization and a production method of anhydrous citric acid crystal. A crystallizer used in the method comprises a cavity; the method comprises pouring materials to be crystallized into the cavity continuously; carrying out evaporation crystallization to the materials to be crystallized under an evaporation crystallization condition; and discharging mixture with crystal during the evaporation crystallization process; the method is characterized in that the materials to be crystallized are added into the cavity along the inner wall of the cavity from the position higher than the liquid level in mode of liquid membrane partially or completely. With the method of the continuous evaporation crystallization, provided by the invention, the moisture content in the crystal is reduced and the anti-caking capacity of the crystal is improved. According to the method provided by the invention, the anhydrous citric acid seed crystal is added and lasted for a certain period during the production of the anhydrous citric acid crystal, the time of a crystallization system reaching the balance state is shortened greatly, and the particle diameter of the anhydrous citric acid crystal before the crystallization system reaches the balance state is enlarged.

Description

technical field [0001] The present invention relates to a method for continuous evaporative crystallization and a method for producing anhydrous citric acid crystals using the continuous evaporative crystallization method. Background technique [0002] Anhydrous citric acid is mainly used in the food and beverage industry as a sour agent, flavoring agent, preservative, and preservative. It is also used as antioxidant, plasticizer and detergent in chemical industry, cosmetic industry and washing industry. At present, the continuous production method of anhydrous citric acid in the industry includes: first, the citric acid fermentation liquid is separated from the solid and liquid to obtain the citric acid clear liquid, and the citric acid clear liquid is purified by the calcium salt method or the hydrogen calcium method, the acid hydrolysis method, and decolorization. The solution is heated and concentrated, the temperature of the citric acid concentrate is controlled to be ...

AI Technical Summary

Problems solved by technology

[0003] There is following shortcoming in the production method of above-mentioned anhydrous citric acid crystal: add citric acid solution and feed from crystallizer middle part or bottom, due to intense evaporative crystallization, make the liquid level of the citric acid solution in the crystallizer produce splashed droplet, The droplet collides with the inner wall of the crystallizer to generate crystal scale (fine anhydrous citric acid crystal grains). As the evaporation and crystallization process proceeds, the crystal scale adheres to each other and covers a small amount of water, which increases the quality of the crystal scale. However, it falls off from the inner wall of the crystallizer, thus a large amount of crystal scale enters the citric acid solution in the crystallizer and continues to grow. The crystals generated by these crystal scales are polycrystals, resulting in wet anhydrous citric acid crystals mixed with polycrystals. , even through the subsequent drying process, the water encapsulated in the polycrystals cannot be removed, and eventually the anhydrous citric acid crystal product is easy to agglomerate

In addition, the supersaturation of the liquid level of the citric acid solution in the crystallizer is relatively large, and it is easy to produce too many crystal nuclei, so that the anhydrous citric acid crystal product particles are too small

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