Method for producing anhydrous citric acid crystal

A technology of anhydrous citric acid and citric acid solution, applied in the separation/purification of carboxylic acid compounds, organic chemistry, etc., can solve the problem of difficult balance between evaporation and incoming and outgoing materials, unsatisfactory crystal particle size control, and small evaporation on the wall And other issues

Inactive Publication Date: 2012-03-28
COFCO BIOTECHNOLOGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Disadvantages of batch crystallization process: Compared with continuous crystallization, due to the limited volume of the tank, the heat exchange area is small, the evaporation in the wall is small, and the production capacity is low, so it is not suitable for large-scale production
[0005] Disadvantages of the multi-effect continuous evaporation crystallization process: due to the continuous feeding and discharging, if the concentration, speed and output of the feeding material are not well controlled, it is difficult to achieve a balance between the evaporation amount in the whole system and the feeding and discharging material, and the control of the particle size of the crystal is not ideal. , even in a crystallizer with grading effect, it is more difficult to obtain the ideal crystal size

Method used

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  • Method for producing anhydrous citric acid crystal
  • Method for producing anhydrous citric acid crystal
  • Method for producing anhydrous citric acid crystal

Examples

Experimental program
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Effect test

Embodiment 1

[0028] (1) will be 12.58m 3 The density is 1158kg / m 3 , The content of citric acid is the citric acid solution of 42% by weight, and the vacuum degree is -60kPa, and the citric acid solution temperature is 78 ℃ and concentrates to 5.9m 3The content of citric acid is the citric acid solution of 75.9% by weight, and the concentrated citric acid solution is introduced into the crystallizer and maintained at a temperature of 58-63°C (equivalent to a degree of supersaturation of 1.05-1.12). 7 kg of anhydrous citric acid seed crystals with a particle size of 150 μm were added to the solution and maintained for 1 hour.

[0029] (2) Under the condition that the vacuum in the crystallizer is -91kPa and the temperature is 58-63°C, the mixture obtained in step (1) is evaporated and crystallized. 3 The citric acid solution that citric acid content is 60% by weight is supplemented at the flow rate of / hour, and this flow rate makes the citric acid solution that contains anhydrous citric...

Embodiment 2

[0033] (1) will 10.5m 3 The density is 1202kg / m 3 , The content of citric acid is the citric acid solution of 50% by weight, and the vacuum degree is -50kPa, and the citric acid solution temperature is 85 ℃ and concentrates to 6.04m 3 The content of citric acid is the citric acid solution of 76.2% by weight, and the concentrated citric acid solution is introduced into the crystallizer and maintained at a temperature of 60-65°C (equivalent to a degree of supersaturation of 1.07-1.11). 31.5 kg of anhydrous citric acid seed crystals with a particle size of 180 microns were added to the solution and maintained for 1.5 hours.

[0034] (2) Under the conditions that the vacuum in the crystallizer is -90kPa and the temperature is 60-65°C, the mixture obtained in step (1) is evaporated and crystallized. 3 The flow rate of / hour supplements the citric acid solution that citric acid content is 50% by weight, and this flow rate makes the citric acid solution that contains anhydrous cit...

Embodiment 3

[0037] (1) will 20m 3 The density is 1095kg / m 3 , The content of citric acid is 30% by weight of citric acid solution, the vacuum is -50kPa, the temperature of citric acid solution is 85 ℃ and concentrated to 6.4m 3 The content of citric acid is the citric acid solution of 75.5% by weight, and the concentrated citric acid solution is introduced into the crystallizer and maintained at a temperature of 57-60° C. (equivalent to a degree of supersaturation of 1.07-1.12), and the 12.6 kg of anhydrous citric acid seed crystals with a particle size of 150 microns were added to the solution and maintained for 1.5 hours.

[0038] (2) Under the condition that the vacuum in the crystallizer is -93kPa and the temperature is 57-60°C, the mixture obtained in step (1) is evaporated and crystallized. 3 The citric acid solution that citric acid content is 65% by weight is supplemented at the flow rate of / hour, and this flow rate makes the citric acid solution that contains anhydrous citric...

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Abstract

The invention provides a method for producing an anhydrous citric acid crystal. The method comprises the following steps of: concentrating citric acid solution until the degree of supersaturation is between 1.02 and 1.15 at temperature of above 36.6 DEG C, and adding an anhydrous citric acid seed crystal. In the method for producing the anhydrous citric acid crystal, the anhydrous citric acid seed crystal is added within the range of between 1.02 and 1.15 of the degree of supersaturation of the citric acid solution, the content of the anhydrous citric acid crystal in a mixture of the citric acid solution and the anhydrous citric acid crystal in the crystallization process is controlled to be between 20 and 50 weight percent, so that nucleation caused by crystal explosion during the earlier stage of crystallization and nonuniformity of crystal granules due to less crystal nucleus yield in the crystallization process are avoided, the number of the crystal granules is controlled stably and effectively, and thus the production of the anhydrous citric acid crystal is controllable, and the method is easy and convenient to operate. The anhydrous citric acid crystal produced according to the method is uniform in size distribution and attractive in appearance of products.

Description

technical field [0001] The invention relates to a production method of anhydrous citric acid crystals. Background technique [0002] Anhydrous citric acid is a very important organic acid, which is widely used in food, medicine, daily chemical industry, textile and other industries. my country is a big producer of anhydrous citric acid, and now the annual output of anhydrous citric acid has exceeded 800,000 tons. In recent years, with the changes in the international and domestic markets, the demand for anhydrous citric acid has been increasing, and customers have stricter requirements for product quality and appearance. [0003] At present, anhydrous citric acid is mostly produced by crystallization methods, mainly including batch crystallization, multi-effect continuous evaporation crystallization and other crystallization processes. [0004] Disadvantages of batch crystallization process: Compared with continuous crystallization, due to the limited volume of the tank, t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C59/265C07C51/43
Inventor 陈修周勇周维英满云许贵珍
Owner COFCO BIOTECHNOLOGY CO LTD
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