Crystallizer and method for crystallization of monoammonium phosphate

Abstract

The invention relates to a crystallizer a crystallization method of monoammonium phosphate. The crystallizer comprises a crystallizer container which is provided with a feed inlet and a discharge port. The internal cavity of the crystallizer container is a crystallizer cavity. The container wall of the crystallizer container is provided with a permeation cavity, which is communicated with a circulation liquid inlet tube and a circulation liquid outlet tube. A wall between the crystallizer cavity and the permeation cavity is a liquid permeating wall, which is provided with multiple liquid permeating holes. The liquid permeating holes are provided with a semi-permeable membrane. During crystallization production of a product solution, an auxiliary material can be introduced into the permeation cavity, substances in the auxiliary material pass through the semi-permeable membrane to enter the crystallizer container and form an ion enrichment region on the inner wall of the container so as to keep crystalline substances away. Therefore, crystallization fouling is avoided or minimized. When the crystallization method of monoammonium phosphate is carried out in the above crystallizer, formation of crystallization fouling on the inner wall of the crystallizer container can be avoided or minimized.

Description

technical field [0001] The invention relates to a crystallizer for industrial production and a monoammonium phosphate crystallization method using the crystallizer. Background technique [0002] Crystallization is a process in which a solute is precipitated from a solution. It can be divided into two stages: the formation of crystal nuclei in the early stage and the crystal growth in the later stage. The driving force of the two stages is the supersaturation of the solution. There are three forms of nucleation: primary homogeneous nucleation, primary heterogeneous nucleation, and secondary nucleation. [0003] Industrial crystallization basically adopts the secondary nucleation process, that is, adding solute crystals to the supersaturated solution to form crystal nuclei. For example, the DTB crystallizer is to add the mother liquor containing solute crystals to the crystallizer container already filled with the supersaturated product solution, and stir the solution to flow...

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Problems solved by technology

[0004] However, during the flow process of the above-mentioned product solution, the solution will also collide with the inner wall of the crystallizer container, and some crystal nuclei will form and grow on the inner wall surface of the crystallizer, and finally form crystal scale on the inner wall of the crystallizer. As the production progresses, Part of the crystal scale forms agglomerates and falls off, which often leads to the problem of blockage of the crystallizer outlet

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