Method for preparing cyanoacetic acid through continuous dehydration

A technology of cyanoacetic acid and chloroacetic acid, applied in the preparation of cyanide reaction, purification/separation of carboxylic acid nitrile, organic chemistry, etc., can solve the problems of low utilization rate of equipment, low yield of cyanoacetic acid, long dehydration time, etc. High utilization rate, short dehydration time and low steam consumption

Active Publication Date: 2012-02-01
WEIFANG BAILI CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, domestic manufacturers mostly use glass-lined dehydration kettles for intermittent dehydration. Intermittent dehydration is not only cumbersome to operate,

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] The mass content is 12% cyanoacetic acid aqueous solution, the mass content of sodium chloride in the described cyanoacetic acid aqueous solution is 16.5% and enters a reboiler with 500kg / h, and the reboiler with 0.2~0.5MPa steam heats, can micro Vacuumize until the pressure in the reboiler is 0.085-0.098MPa, and make the steam evaporated at 95-99°C; the obtained steam enters the second-effect reboiler, and the second-effect vacuumizes until the pressure in the second-effect reboiler is 0.058- 0.07MPa, so that the evaporated steam is at 85-90°C; the obtained steam enters the three-effect reboiler, and the three-effect vacuum is pumped until the pressure in the three-effect reboiler is 0.007-0.015MPa, so that the evaporated steam is at 40-55°C; The three-effect evaporation adopts a parallel feeding process; the evaporated liquid obtained in the first effect is desalted by centrifugal filtration, and the filtrate obtained enters the second-effect reboiler; the evaporated l...

Embodiment 2

[0022] Mass content is 12% cyanoacetic acid aqueous solution, and the mass content of sodium chloride in described cyanoacetic acid aqueous solution is 16.7% and enters an effect reboiler with 510kg / h, and an effect reboiler is heated with 0.3~0.5MPa steam, makes steaming The outlet steam is at 96-99°C; the obtained steam enters the second-effect reboiler, so that the evaporated steam is at 70-80°C; the obtained steam enters the three-effect reboiler, and the evaporated steam is at 35-45°C; the three-effect evaporation adopts Countercurrent feeding process; the evaporated liquid obtained in the first effect is desalted by tank filtration, and the obtained filtrate enters the second effect reboiler; The liquid is desalinated by tank-type filtration, and the obtained filtrate is 71% cyanoacetic acid finished product; the materials in each effect reboiler are forced to circulate with a pump, and the flow rate of the materials in the reboiler is controlled at 0.5-2m / s, and the yiel...

Embodiment 3

[0024] The mass content is 12.5% ​​cyanoacetic acid aqueous solution, the mass content of sodium chloride in the said cyanoacetic acid aqueous solution is 17.5% and enters a reboiler with 550kg / h, and the reboiler with 0.2~0.5MPa steam heats, can micro Vacuumize until the pressure in the reboiler is 0.08-0.095MPa, and make the steam evaporated at 96-99°C; the obtained steam enters the second-effect reboiler, and the second-effect vacuumizes until the pressure in the second-effect reboiler is 0.059- 0.07MPa, so that the evaporated steam is at 85-90°C; the obtained steam enters the three-effect reboiler, and the three-effect vacuum is pumped until the pressure in the three-effect reboiler is 0.007-0.015MPa, so that the evaporated steam is at 40-55°C; The three-effect evaporation adopts an advection feeding process; the evaporated liquid obtained in the first effect is desalted through microporous filtration, and the obtained filtrate enters the second-effect reboiler; The evapor...

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PUM

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Abstract

The invention discloses a method for preparing cyanoacetic acid through continuous dehydration. After chloroacetic acid is neutralized, cyanided and acidized to obtain cyanoacetic acid water solution, multi-effect evaporation and forced circulation evaporation are adopted and coupled for continuous dehydration, in addition, continuously separated sodium chloride is removed in the dehydration process for preparing the cyanoacetic acid, when the multi-effect evaporation is used for preparing the cyanoacetic acid, the steam consumption is reduced, and in addition, the sodium chloride is filtered during the proceeding of each effect, so the separated sodium chloride can be filtered and removed in time, the solid-liquid ratio is reduced, filter equipment can be more favorably selected, the operation is simple, the equipment utilization rate is high, the steam consumption is low, in addition, the dehydration time is short, and the cyanoacetic acid yield is high.

Description

technical field [0001] The invention relates to the technical field of chemical production, in particular to a method for preparing cyanoacetic acid. Background technique [0002] Cyanoacetic acid is the main raw material for preparing fine chemical products such as cyanoacetate, malonate and caffeine. The preparation of cyanoacetic acid is to use chloroacetic acid as the raw material, first neutralize with alkali such as sodium hydroxide or sodium carbonate, then add sodium cyanide for cyanation, then add hydrochloric acid for acidification, and then dehydrate to obtain different concentrations of cyanoacetic acid. At present, domestic manufacturers mostly use glass-lined dehydration kettles for intermittent dehydration. Intermittent dehydration is not only cumbersome to operate, but also has low equipment utilization and high steam consumption. Due to the long dehydration time, the yield of cyanoacetic acid is also low, generally at 95%. about. Contents of the invention...

Claims

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Application Information

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IPC IPC(8): C07C255/19C07C253/14C07C253/34
Inventor 郭希田马会楼
Owner WEIFANG BAILI CHEM
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