Four-effect cross-flow evaporation system and process

Abstract

The invention discloses a four-effect cross-flow evaporation system and process. In the four-effect cross-flow evaporation system, a material outlet of a fourth-effect evaporator is respectively communicated with material inlets of a third-effect evaporator and a first-effect evaporator, and material outlets of the third-effect evaporator and the first-effect evaporator are communicated with a material inlet of a second-effect evaporator. In the four-effect cross-flow evaporation process, the flow direction of materials comprises two parts, wherein one part is reverse-flow charging evaporation from the fourth-effect evaporator to the third-effect evaporator and then to the second-effect evaporator; and the other part is cross-flow evaporation containing reverse-flow charging and parallel-flow charging from the fourth-effect evaporator to the first-effect evaporator and then to the second-effect evaporator. According to a cross-flow evaporation method, the evaporation capacity in the evaporation crystallization process can be effectively controlled, the material concentration in the evaporation crystallization process can be effectively controlled, and the too-high material concentration is prevented.

Description

technical field [0001] The invention relates to a multi-effect evaporation system and process, in particular to a four-effect cross-flow evaporation system and process for evaporating and separating by-product sodium sulfate in the production process of methionine. Background technique [0002] A method for preparing methionine includes neutralizing a sodium methionine solution under acidic conditions such as concentrated sulfuric acid, and the solution obtained after sodium methionine is neutralized by sulfuric acid mainly contains methionine and sodium sulfate. According to the solubility characteristics of methionine and sodium sulfate, under the condition of 32.4 ℃ to 120 ℃, the solubility of sodium sulfate decreases with the increase of temperature, while the solubility of methionine increases rapidly with the increase of temperature. Therefore, methionine is crystallized and extracted by gradual cooling and vacuum flash evaporation, and then sodium sulfate is recovere...

AI Technical Summary

Problems solved by technology

If the sodium sulfate solution containing methionine is heated up, evaporated and crystallized in the conventional way of gradually raising the temperature and countercurrent feeding and evaporating, the concentration of the material will be very high when it reaches the last effect evaporator, and excessive sodium sulfate will be precipitated, and the methionine in the solution will also be Some crystals will be precipitated, and they will accumulate near the outlet to block the pipe and separator, which is not conducive to the separation operation, and the excessive precipitation of sodium sulfate will easily cause methionine to be heated and carbonized and deteriorate.

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