CN103694210B - A kind of method of dehydroacetic acid (DHA) of purifying - Google Patents
A kind of method of dehydroacetic acid (DHA) of purifying Download PDFInfo
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- CN103694210B CN103694210B CN201410013469.9A CN201410013469A CN103694210B CN 103694210 B CN103694210 B CN 103694210B CN 201410013469 A CN201410013469 A CN 201410013469A CN 103694210 B CN103694210 B CN 103694210B
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- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D309/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings
- C07D309/34—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
- C07D309/36—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with oxygen atoms directly attached to ring carbon atoms
Abstract
The invention discloses the production technique utilizing fusion-crystallization to prepare highly purified dehydroacetic acid (DHA), it comprises the steps: first bottom melting crystallizer external jacket, to pass into chilled brine, chilled brine is film evaporation device at crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, dehydroacetic acid (DHA) solution flows down at crystallizer inwall falling liquid film, progressively cool and crystallization, heat-transfer surface progressively grows uniform crystal layer, the concentration of crystal layer is higher than the concentration of mixture solution, and impurity is progressively enriched in mixture solution; Then regulate hot water temperature to carry out partial melting operation to crystal layer, i.e. sweating effort by interchanger, the low-melting impurities partial melting be mingled with in crystal layer is got rid of, with crystal of purifying further.Present invention process is simple, compact equipment, adopts falling liquid film form, reduces energy, reduces cost and facility investment simultaneously; The product purity utilizing this melting crystallizer to produce is high.
Description
Technical field
The present invention relates to a kind of method of purification of dehydroacetic acid (DHA), especially a kind of method of melting crystallizer purification dehydroacetic acid (DHA).
Background technology
Dehydroacetic acid (DHA) is a kind of feed anticorrosion agent of broad spectrum, can mould fungus inhibition, yeast and bacterium growth.Bacteriostatic action is not substantially by the impact of PH, but under neutrallty condition, preservative effect is best.Also be used as food preservatives, domestic regulation can be used for the anticorrosion of fermented bean curd, pickles and Normal juice tangerine sauce, maximum usage quantity 0.3g/kg, and dehydroacetic acid (DHA) is again a kind of organic synthesis intermediate, toughner simultaneously, is also the food preservatives of broad spectrum.Since within 1940, finding that it has germ resistance, successively obtain the attention of many countries, and obtained the permission for food antiseptic successively.Dehydroacetic acid (DHA), as foodstuff additive, is allowed for the beverage, beans sauce, filling class etc. of cheese, butter, oleomargarine, refreshment drink, fermented-milk and milk-acid bacteria.Generally Sodium dehydroacetate is used as foodstuff additive.These product are also for daily cosmetics, fibre product, medicine (treatment as ringworm), and dental material is anticorrosion.The equipment of large-scale production dehydroacetic acid (DHA) is general enamel reaction still both at home and abroad at present; the operation of its maturation process is roughly as follows: namely get toluene and ketene dimer under the effect of catalyzer; there is condensation reaction; finished product is obtained again through operations such as enamel still crystallisation by cooling, dehydration, drying, packagings; but overlap the bad control of cooling temperature because enamel still adds, easily make material stickness, yield rate is not high; purity is also affected greatly, and outward appearance is very secondary.Therefore the Processes and apparatus of existing this dehydroacetic acid (DHA) haves much room for improvement.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of method of melting crystallizer purification dehydroacetic acid (DHA), has good parallel reactor selectivity and security, reduces cost and facility investment; Environmentally friendly, reduce energy consumption, and dehydroacetic acid (DHA) product purity is high, stay in grade, thus overcomes deficiency of the prior art.
For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of method of dehydroacetic acid (DHA) of purifying, and its innovative point is: adopt melting crystallizer purification dehydroacetic acid (DHA);
(1) crystallization: first pass into chilled brine bottom melting crystallizer external jacket, chilled brine is film evaporation device at melting crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, dehydroacetic acid (DHA) solution flows down at melting crystallizer inwall falling liquid film, progressively cool and crystallization, heat-transfer surface progressively grows uniform crystal layer, and the concentration of crystal layer is higher than the concentration of melting crystallizer solution, and impurity is progressively enriched in solution;
(2) sweating, fusing: after chilled brine passes into 30 ~ 40min, stop feed, regulates hot water temperature to carry out partial melting operation to crystal layer by interchanger, the low-melting impurities part be mingled with got rid of, crystal of purifying further in crystal layer.
The present invention adopts melting crystallizer utilize the difference of zero pour between separate substance and realize separating substances and purification, controls mass transfer, thus reach the effect of the purity improving crystalline rate and crystal product by the transmission of adjusting energy; Improve parallel reactor selectivity; For the system using the unsafe factors such as the recrystallization of solvent can set off an explosion, burning, by melting crystallizer control inputs, maintain the optimum concn of crystallization, cold operation can improve security of system; Pass into appropriate pressurized air in crystallizer upper airway, make solution in crystallizer, form slug flow bubble and rise, cause the turbulence of melt, mass transfer enhancement and heat transfer property.
Further, described step (1) is specially: first bottom melting crystallizer external jacket, pass into chilled brine, chilled brine is film evaporation device at melting crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, pass through melting crystallizer airway with 4 ~ 7m simultaneously
3the speed of/min passes into pressurized air in dehydroacetic acid (DHA) solution, make it in crystallizer, form slug flow bubble to rise, cause the turbulence of melt, mass transfer enhancement and heat transfer property, dehydroacetic acid (DHA) solution flows down at melting crystallizer inwall falling liquid film, progressively cools and crystallization, heat-transfer surface progressively grows uniform crystal layer, the concentration of crystal layer is higher than the concentration of solution in melting crystallizer, and impurity is progressively enriched in solution.
Further, described step (2) is specially: after control chilled brine passes into time 30 ~ 40min, stop feed, and switch warm water tank and carry out partial melting to crystal layer, warm water tank water temperature is 88 ~ 92 DEG C, and it is 15 ~ 40min that warm water passes into the time; Then the low-melting impurities fusing making to be mingled with in crystal layer by switching hot-water cylinder is got rid of, and crystal of purifying further, hot-water cylinder water temperature is 90 ~ 94 DEG C, and it is 28 ~ 32min that hot water passes into the time.
Further, described melting crystallizer is a kind of falling film melt crystallization of vertical array tubular heat exchanger type.
Compared with prior art, the invention has the advantages that: simple by the technique of above-mentioned melting crystallizer purification dehydroacetic acid (DHA), it has good parallel reactor selectivity and security, adopt falling liquid film form and cold operation, the energy expenditure of unit output product significantly reduces, there is good economy, this technological process crystal forms crystal layer at heating surface simultaneously, instead of float on a liquid, this avoid the blocking of e-quipment and pipe, decrease the generation of fault in production, reduce cost and facility investment; Almost do not have in production process " three wastes ", environmentally friendly, compared with using the recrystallization of solvent, do not need dry with desolvation, energy consumption is only 10% ~ 30% of rectifying, and the dehydroacetic acid (DHA) product purity utilizing this melting crystallizer to produce is high, stay in grade, increases operation progression and purity can be made infinitely to improve, foreign matter content can be made in product from percentage composition to ppm content, thus overcomes deficiency of the prior art.
Embodiment
Below in conjunction with specific embodiment, technical scheme of the present invention is elaborated.
embodiment 1
The technique of melting crystallizer purification dehydroacetic acid (DHA) is as follows:
(1) crystallization: first pass into-8 DEG C of calcium chloride solutions bottom melting crystallizer external jacket, calcium chloride solution is film evaporation device at melting crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, pass through melting crystallizer airway with 4m simultaneously
3the speed of/min passes into pressurized air in dehydroacetic acid (DHA) solution, make it in crystallizer, form slug flow bubble to rise, cause the turbulence of melt, mass transfer enhancement and heat transfer property, dehydroacetic acid (DHA) solution flows down at crystallizer inwall falling liquid film, progressively cools and crystallization, heat-transfer surface progressively grows uniform crystal layer, the concentration of crystal layer is higher than the concentration of solution in melting crystallizer, and impurity is progressively enriched in solution;
(2) sweating, fusing: after control calcium chloride solution passes into time 30min, stop feed, switch warm water tank and carry out partial melting to crystal layer, warm water tank water temperature is 88 DEG C, and it is 15min that warm water passes into the time; Then switch the low-melting impurities fusing eliminating that hot-water cylinder makes to be mingled with in crystal layer, crystal of purifying further, hot-water cylinder water temperature is 90 DEG C, and it is 28min that hot water passes into the time, and the purity obtaining dehydroacetic acid (DHA) is 99.87%.
embodiment 2
The technique of melting crystallizer purification dehydroacetic acid (DHA) is as follows:
(1) crystallization: first pass into-6 DEG C of sodium chloride solutions bottom melting crystallizer external jacket, sodium chloride solution is film evaporation device at crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, pass through melting crystallizer airway with 5m simultaneously
3the speed of/min passes into pressurized air in dehydroacetic acid (DHA) solution, make it in crystallizer, form slug flow bubble to rise, cause the turbulence of melt, mass transfer enhancement and heat transfer property, dehydroacetic acid (DHA) solution flows down at crystallizer inwall falling liquid film, progressively cools and crystallization, heat-transfer surface progressively grows uniform crystal layer, the concentration of crystal layer is higher than the concentration of mixture solution, and impurity is progressively enriched in mixture solution;
(2) sweating, fusing: after control sodium chloride solution passes into time 35min, stop feed, switch warm water tank and carry out partial melting to crystal layer, warm water tank water temperature is 90 DEG C, and it is 30min that warm water passes into the time; Then switch the low-melting impurities fusing eliminating that hot-water cylinder makes to be mingled with in crystal layer, crystal of purifying further, hot-water cylinder water temperature is 90 DEG C, and it is 30min that hot water passes into the time, and the purity obtaining dehydroacetic acid (DHA) is 99.93%.
embodiment 3
The technique of melting crystallizer purification dehydroacetic acid (DHA) is as follows:
(1) crystallization: the calcium chloride solution first passing into-2 DEG C bottom melting crystallizer external jacket, calcium chloride solution is film evaporation device at melting crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, pass through melting crystallizer airway with 7m simultaneously
3the speed of/min passes into pressurized air in dehydroacetic acid (DHA) solution, make it in crystallizer, form slug flow bubble to rise, cause the turbulence of melt, mass transfer enhancement and heat transfer property, dehydroacetic acid (DHA) solution flows down at crystallizer inwall falling liquid film, progressively cools and crystallization, heat-transfer surface progressively grows uniform crystal layer, the concentration of crystal layer is higher than the concentration of the solution in melting crystallizer, and impurity is progressively enriched in solution;
(2) sweating, fusing: after control calcium chloride solution passes into time 40min, stop feed, switch warm water tank and carry out partial melting to crystal layer, warm water tank water temperature is 92 DEG C, and it is 40min that warm water passes into the time; Then switch the low-melting impurities fusing eliminating that hot-water cylinder makes to be mingled with in crystal layer, crystal of purifying further, hot-water cylinder water temperature is 94 DEG C, and it is 32min that hot water passes into the time, and the purity obtaining dehydroacetic acid (DHA) is 99.87%.
comparative example 1
(1) dehydroacetic acid (DHA) solution good for condensation is squeezed in crystallization kettle, toward logical 0 ~-5 DEG C of chilled brine of crystallization kettle chuck, in still during temperature drop to 15 ~ 25 DEG C, then close chilled brine valve, stop cooling, add the dehydroacetic acid (DHA) calomel mercurous chloride crystal seed of 1kg.
(2) after crystal seed adds 20 ~ 25min, open chilled brine operated pneumatic valve, continue cooling, stop cooling to 0 ~ 10 DEG C, prepare blowing, centrifuge dehydration, oven dry, the purity obtaining dehydroacetic acid (DHA) is 99.81%.
By adopt a kind of be similar to the falling film melt crystallization device of vertical array tubular interchanger after, the crystallisation process of dehydroacetic acid (DHA) becomes and more easily controls, and impurity is few, and the purity of finished product is higher, generally can reach more than 99.8%, and outward appearance is whiter and bright, and crystal is good.By the improvement of this technique, effectively raise its antiseptic property, reduce the consumption of sanitas in food, effectively raise food safety in dehydroacetic acid (DHA) finished product not or greatly reduce impurity.
It is pointed out that above-mentioned preferred embodiment is only and technical conceive of the present invention and feature are described, its object is to person skilled in the art can be understood content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalences done according to spirit of the present invention change or modify, and all should be encompassed within protection scope of the present invention.
Claims (3)
1. to purify the method for dehydroacetic acid (DHA), it is characterized in that: adopt melting crystallizer purification dehydroacetic acid (DHA), concrete steps are:
(1) crystallisation step: first pass into chilled brine bottom melting crystallizer external jacket, chilled brine is film evaporation device at melting crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, dehydroacetic acid (DHA) solution flows down at melting crystallizer inwall falling liquid film, progressively cool and crystallization, heat-transfer surface progressively grows uniform crystal layer, and the concentration of crystal layer is higher than the concentration of melting crystallizer solution, and impurity is progressively enriched in solution;
(2) sweating, fusing: after chilled brine passes into 30 ~ 40min, stop feed, regulates hot water temperature to carry out partial melting operation to crystal layer by interchanger, the low-melting impurities part be mingled with got rid of, crystal of purifying further in crystal layer;
Described crystallisation step is specially: first bottom melting crystallizer external jacket, pass into chilled brine, temperature is-10 DEG C ~-2 DEG C, chilled brine is film evaporation device at melting crystallizer outer wall uniformly, then dehydroacetic acid (DHA) solution good for condensation is put in melting crystallizer, pass through melting crystallizer airway with 4 ~ 7m simultaneously
3the speed of/min passes into pressurized air in dehydroacetic acid (DHA) solution, make it in crystallizer, form bubble to rise, cause the turbulence of melt, mass transfer enhancement and heat transfer property, dehydroacetic acid (DHA) solution flows down at melting crystallizer inwall falling liquid film, progressively cools and crystallization, heat-transfer surface progressively grows uniform crystal layer, the concentration of crystal layer is higher than the concentration of solution in melting crystallizer, and impurity is progressively enriched in solution;
Described sweating, fusing step: after control chilled brine passes into time 30 ~ 40min, stop feed, switch warm water tank and carry out partial melting to crystal layer, warm water tank water temperature is 88 ~ 92 DEG C, and it is 15 ~ 40min that warm water passes into the time; Then the low-melting impurities fusing making to be mingled with in crystal layer by switching hot-water cylinder is got rid of, and crystal of purifying further, hot-water cylinder water temperature is 90 ~ 94 DEG C, and it is 28 ~ 32min that hot water passes into the time.
2. the method for a kind of dehydroacetic acid (DHA) of purifying according to claim 1, is characterized in that: described chilled brine is calcium chloride solution or sodium chloride solution.
3. the method for a kind of dehydroacetic acid (DHA) of purifying according to claim 1, is characterized in that: described melting crystallizer is a kind of falling film melt crystallization device of vertical array tubular heat exchange type.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1050829A (en) * | 1990-11-29 | 1991-04-24 | 天津大学 | Parametric pump fractional crystallization method and pfc crystallizer |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1050829A (en) * | 1990-11-29 | 1991-04-24 | 天津大学 | Parametric pump fractional crystallization method and pfc crystallizer |
Non-Patent Citations (3)
| Title |
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| 熔融结晶技术及应用;李庆龙等;《化工生产与技术》;20130225;第20卷(第1期);第29-31页 * |
| 降膜冷冻结晶法精制对氯甲苯;陈德彬;《湖南化工》;19960130;第26卷(第1期);第44页左栏2.2.2、右栏2.3.3 * |
| 降膜结晶技术及其数值模拟研究;张建文;《中国优秀博硕士学位论文全文数据库 工程科技I辑》;20070115;第4页 * |
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