Process for producing biurea through optimized urea method

A technology of biurea and urea, applied in the field of biurea, can solve the problems of increasing the consumption of caustic soda, and achieve the effects of low cost, low consumption of raw materials and energy, and high yield in a single kettle

Inactive Publication Date: 2015-09-09
HANGZHOU HI TECH FINE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this evaporation process, 0.3-0.5 tons of caustic soda of biurea must be added to evaporate the hydrazine hydrate in the crude solution (the effect of adding caustic soda is that the caustic soda in the evaporator reac

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] (1) Mix sodium hypochlorite and urea solution (catalyst has been added) and send it into the hydrazine hydrate reactor, heat it to 125°C with steam, and obtain a crude solution containing about 46g / L hydrazine hydrate after the reaction, and send this solution directly to Into the evaporator, evaporate and concentrate under vacuum conditions to a crude solution containing 85g / L hydrazine hydrate, the concentration ratio is 1:0.58, and the concentrated and separated sodium chloride is sent to a centrifuge to separate the sodium chloride. The evaporated steam containing a small amount of hydrazine hydrate enters the rectification tower and is concentrated to 10-15% hydrazine hydrate.

[0030] (2) The crude solution obtained from (1) is extracted from the evaporator, sent to the pre-cooling tank and cooled to 35-45°C with circulating water under stirring, and then sent to the crystallization kettle to be cooled to 0°C with frozen brine , separate out the sodium carbonate d...

Embodiment 2

[0037] (1) The crude solution containing 46g / L hydrazine hydrate that is 125°C from the hydrazine hydrate reactor is sent into the crystallization kettle after pre-cooling and cooled to 0°C with frozen brine, and the separated out Sodium carbonate decahydrate is sent to Centrifuge separates sodium carbonate decahydrate crystal, obtains the essence hydrazine liquid containing 53g / L hydrazine hydrate.

[0038] (2) The hydrazine solution obtained in (1) is preheated and sent to the evaporator, and evaporated and concentrated to a crude solution containing 85g / L hydrazine hydrate under vacuum conditions, the concentration ratio is 1:0.65, and the separated out Sodium chloride is sent to centrifuge to separate solid sodium chloride. The evaporated steam containing a small amount of hydrazine hydrate enters the rectification tower and is concentrated to 10-15% hydrazine hydrate.

[0039] (3) After the crude solution obtained from (2) is pre-cooled to 35-45°C, it is sent to the crys...

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Abstract

The present invention discloses a process for producing biurea through an optimized urea method. The process comprises that: during the biurea preparing, the crude solution of hydrazine hydrate produced through the urea method is adopted as a raw material and is subjected to repeated evaporation concentration and freezing crystallization for a plurality of times to respectively separate out sodium chloride and sodium carbonate so as to obtain a fine hydrazine solution of the hydrazine hydrate; the sodium chloride is separated at the evaporation section and the sodium carbonate decahydrate is separated at the freezing crystallization section during each evaporation, a salt extracting pump is used to extract, and the solid sodium chloride is separated out by a salt separation centrifuge; and the liquid is subjected to freezing crystallization, is separated, and then returns to the cold hydrazine solution at the evaporation section, pre-cooling is performed, and then the obtained material is conveyed to the crystallization kettle. The process of the present invention has the following beneficial effects that: the hydrazine hydrate-containing crude solution produced through the urea method is adopted as the raw material, alkali removing through freezing is performed while the cold energy and the heat energy are recovered, the repeated circulating method is used, the hydrazine hydrate concentration is improved in the low cost manner, and the process has characteristics of less raw material consumption, less energy source consumption, low cost, and high single-kettle yield during condensation.

Description

technical field [0001] The invention relates to the technical field of biurea, in particular to a process for optimizing the production of biurea by a urea method. Background technique [0002] Biurea is white solid or powder, molecular formula: C 2 h 6 N 4 o 2 , Molecular weight: 118, insoluble in water, melting point 247-250°C, biurea is mainly used in the production of ADC foaming agent. [0003] The conventional urea method to produce biurea is divided into two types: acid method and pure hydrazine method. [0004] The conventional acid method mainly adopts the crude solution containing <70g / L hydrazine hydrate produced by the urea method to separate part of the sodium carbonate decahydrate through freezing and crystallization to obtain a dilute hydrazine solution whose concentration of hydrazine hydrate is increased to less than about 10%, adding sulfuric acid or Hydrochloric acid is neutralized and then reacted with urea at a temperature of >100°C to form bi...

Claims

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Application Information

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IPC IPC(8): C07C281/06
CPCY02P20/10
Inventor 陈海贤付永宽施光明魏增
Owner HANGZHOU HI TECH FINE CHEM
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