CN103483184A - Method for producing anhydrous citric acid crystals - Google Patents
Method for producing anhydrous citric acid crystals Download PDFInfo
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- CN103483184A CN103483184A CN201310462436.8A CN201310462436A CN103483184A CN 103483184 A CN103483184 A CN 103483184A CN 201310462436 A CN201310462436 A CN 201310462436A CN 103483184 A CN103483184 A CN 103483184A
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- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 title claims abstract description 324
- 239000013078 crystal Substances 0.000 title claims abstract description 153
- 229960004543 anhydrous citric acid Drugs 0.000 title claims abstract description 69
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 239000007788 liquid Substances 0.000 claims abstract description 127
- 238000000034 method Methods 0.000 claims abstract description 74
- 238000002425 crystallisation Methods 0.000 claims abstract description 66
- 230000008025 crystallization Effects 0.000 claims abstract description 63
- 229960004106 citric acid Drugs 0.000 claims abstract description 62
- 238000001816 cooling Methods 0.000 claims abstract description 31
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 238000003756 stirring Methods 0.000 claims abstract description 12
- 230000008859 change Effects 0.000 claims description 6
- 239000000126 substance Substances 0.000 abstract description 21
- 230000008439 repair process Effects 0.000 abstract description 8
- 230000008569 process Effects 0.000 abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 6
- 239000002002 slurry Substances 0.000 abstract 8
- 239000000243 solution Substances 0.000 description 35
- 239000000843 powder Substances 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 14
- 239000012452 mother liquor Substances 0.000 description 10
- 238000002834 transmittance Methods 0.000 description 10
- 238000001035 drying Methods 0.000 description 8
- 238000000926 separation method Methods 0.000 description 8
- 238000007493 shaping process Methods 0.000 description 8
- 238000001704 evaporation Methods 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 6
- 238000005119 centrifugation Methods 0.000 description 5
- 230000009467 reduction Effects 0.000 description 4
- 238000007664 blowing Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 244000061456 Solanum tuberosum Species 0.000 description 2
- 235000002595 Solanum tuberosum Nutrition 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000000855 fermentation Methods 0.000 description 2
- 230000004151 fermentation Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 241000228245 Aspergillus niger Species 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 206010013786 Dry skin Diseases 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 240000003183 Manihot esculenta Species 0.000 description 1
- 235000016735 Manihot esculenta subsp esculenta Nutrition 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000010413 mother solution Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000003828 vacuum filtration Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
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- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for producing anhydrous citric acid crystals. The method comprises the following steps: crystallizing a citric acid solution under the circulating stirring condition to obtain a crystal slurry solution; changing the initial temperature of the crystal slurry solution to repair crystals in the crystal slurry solution, and obtaining a solution containing the anhydrous citric acid crystals, wherein the process of changing the initial temperature of the crystal slurry solution comprises the following steps: (1) heating the crystal slurry solution to 2-20 DEG C after crystallization; (2) cooling the crystal slurry solution to 1-10 DEG C after crystallization; or (3) heating the crystal slurry solution to 2-20 DEG C at first after crystallization and then cooling the heated crystal slurry solution to 2-25 DEG C. Through the technical scheme, recesses in crystal surfaces can be effectively removed, and residues in mother liquid in the crystals are reduced, so that the content of water in the crystals is reduced; moreover, anhydrous citric acid molecules on the crystal surfaces are rearranged in a repair process, so that the quality is effectively improved and readily carbonizable substances are reduced.
Description
Technical field
The present invention relates to a kind of production method of anhydrous citric acid crystal.
Background technology
The continuous production method of current industrial Citric Acid, usp, Anhydrous Powder comprises: first citric acid fermentation broth is obtained to the citric acid clear liquid through solid-liquid separation, then the citric acid clear liquid is extracted through hydrogen calcium method or calcium salt method, acidolysis decolouring obtain the citric acid solution of purifying, again that the citric acid solution heating of purifying is concentrated, the above-mentioned citric acid solution concentrated is injected to crystallizer continuously, by evaporation, make the citric acid concentrated solution reach hypersaturated state, solution nature graining, then the evaporation limit crystallization of citric acid solution limit is added on limit, when solids content (anhydrous citric acid crystal) reaches the gross weight of mixture of citric acid solution and solid to a certain degree the time, start the magma liquid that the continuous and quantitative discharge contains anhydrous citric acid crystal, and the continuous operation of keeping system.Again the magma liquid of advantages of good crystallization is carried out to centrifugation and obtain the wet crystal of Citric Acid, usp, Anhydrous Powder and crystalline mother solution, and the crystal oven dry of wetting obtains dry anhydrous citric acid crystal.
But adopt the shortcoming of aforesaid method to be: the wet crystal entrainment mother liquor of the Citric Acid, usp, Anhydrous Powder of gained is many, and the dry crystal mass obtained after oven dry is poor, and readily carbonizable substance and moisture content are higher.
Summary of the invention
The objective of the invention is to overcome prior art, to obtain the wet crystal entrainment mother liquor of Citric Acid, usp, Anhydrous Powder more, dry crystal mass is poor, the defect that readily carbonizable substance and moisture content are higher, provide the wet crystal entrainment mother liquor of a kind of Citric Acid, usp, Anhydrous Powder obtained few, dry crystal mass is good, the production method of the anhydrous citric acid crystal that readily carbonizable substance and moisture content are lower.
The present inventor finds, the wet crystal entrainment mother liquor of the Citric Acid, usp, Anhydrous Powder that prior art obtains is more, dry crystal mass is poor, the reason that readily carbonizable substance and moisture content are higher is: in the process of Citric Acid, usp, Anhydrous Powder evaporative crystallization, must constantly just can make it mix the citric acid solution circulation, yet the fast rotational of the recycle pump blade of crystal system (general rotating speed be 650-800rpm) can make the Citric Acid, usp, Anhydrous Powder of separating out can't be by normal sequential aggradation to plane of crystal, thereby cause plane of crystal depression to occur, the depression position can make mother liquor residual in a large number.Therefore, make the crystal moisture content higher, easily caking; And the anhydrous citric acid crystal obtained not according to the normal crystallization order of crystallization is second-rate, and readily carbonizable substance is higher.
The present inventor finds unexpectedly, by the magma liquid that obtains after the citric acid solution condensing crystal with 1) by the magma liquid intensification 2-20 ℃ obtained after crystallization; 2) by the magma liquid cooling 1-10 ℃ obtained after crystallization; 3) first by the magma liquid intensification 2-20 ℃ obtained after crystallization, then any one method reparation in 2-25 ℃ of the cooling of the magma liquid after heating up can be reduced to the residual of mother liquor in crystal effectively, make its moisture content obtain reduction; And the crystal arrangement finally obtained is rule comparatively, make its quality obtain effectively improving, and reduced readily carbonizable substance.
Based on above discovery, the invention provides a kind of production method of anhydrous citric acid crystal, the method comprises, under the condition of circulation stirring, citric acid solution is carried out to crystallization, obtain magma liquid, wherein, the method also comprises that the initial temperature that changes magma liquid is repaired with the crystal in magma liquid, obtains the feed liquid that contains anhydrous citric acid crystal; The method of described change magma liquid initial temperature comprises:
1) by the magma liquid intensification 2-20 ℃ obtained after crystallization,
2) by the magma liquid cooling 1-10 ℃ obtained after crystallization, or
3) first by the magma liquid intensification 2-20 ℃ obtained after crystallization, then the cooling of the magma liquid after heating up 2-25 ℃.
Preferably, method 1) and 3) in, the speed that the magma liquid obtained after crystallization is heated up is 1-10 ℃/h; Method 2) and 3) in, by the cooling of the magma liquid that obtains after crystallization or be 1-8 ℃/h by the speed of the magma liquid cooling after heating up again.
Preferably, method 3) in, maximum low 5 ℃ than the initial temperature of magma liquid of the temperature of the magma liquid obtained after the magma liquid after heating up is lowered the temperature.
Preferably, described reparation is carried out under the condition stirred, and the speed of described stirring is 20-30rpm.
Crystal in magma liquid crystallization obtained by technique scheme is repaired, and can effectively eliminate the depression of plane of crystal, thereby can reduce the residual of mother liquor in crystal, has reduced the moisture content in the crystal.And in the process of repairing, the Citric Acid, usp, Anhydrous Powder molecule of plane of crystal is reset, and makes its quality obtain effective raising, and has reduced readily carbonizable substance.And carry out the reparation of anhydrous citric acid crystal under above-mentioned preferred condition, make the residue of mother of anhydrous citric acid crystal further reduce, moisture content and the readily carbonizable substance of crystal further reduce, and the crystal outward appearance is more regular.
Other features and advantages of the present invention will partly be described in detail in embodiment subsequently.
The accompanying drawing explanation
Accompanying drawing is to be used to provide a further understanding of the present invention, and forms the part of specification sheets, is used from explanation the present invention with following embodiment one, but is not construed as limiting the invention.In the accompanying drawings:
Fig. 1 is the MIcrosope image of the anhydrous citric acid crystal that obtains of the method according to embodiment 1, and magnification is 60 times;
Fig. 2 is the MIcrosope image of the anhydrous citric acid crystal that obtains of the method according to Comparative Examples 1, and magnification is 60 times.
Embodiment
Below the specific embodiment of the present invention is elaborated.Should be understood that, embodiment described herein only, for description and interpretation the present invention, is not limited to the present invention.
The invention provides a kind of production method of anhydrous citric acid crystal, the method comprises, under the condition of circulation stirring, citric acid solution is carried out to crystallization, obtain magma liquid, wherein, the method also comprises that the initial temperature that changes magma liquid is repaired with the crystal in magma liquid, obtains the feed liquid that contains anhydrous citric acid crystal; The method of described change magma liquid initial temperature comprises:
1) by the magma liquid intensification 2-20 ℃ obtained after crystallization,
2) by the magma liquid cooling 1-10 ℃ obtained after crystallization, or
3) first by the magma liquid intensification 2-20 ℃ obtained after crystallization, then the cooling of the magma liquid after heating up 2-25 ℃.
Preferably, method 1) in, by the magma liquid intensification 5-15 ℃ obtained after crystallization; Method 2) in, by the magma liquid cooling 2-8 ℃ obtained after crystallization; Method 3) in, first by the magma liquid intensification 5-15 ℃ obtained after crystallization, then the cooling of the magma liquid after heating up 5-20 ℃.Can further effectively repair the surface of crystal.
According to the present invention, the time that crystal is repaired has no particular limits, and those skilled in the art can be adjusted according to actual reparation situation.Preferably, consider repairing effect and consumption while repairing, method 1) in time of repairing be 10-30 minute; The time of repairing method 2) is 10-30 minute; Method 3) in, be 10-20 minute the repair time of temperature-rise period, then be 10-20 minute the repair time of temperature-fall period.
It should be noted that herein and all refer to change temperature to steady temperature above-mentioned repair time, and the time kept under this steady temperature.
In above-mentioned 3 kinds of methods that change the magma liquid temps of the present invention, the present inventor finds, the temperature by slow intensification or cooling to magma liquid is changed, and can further improve the quality of final crystal product.For example, in method 1) in, the speed of intensification can be 1-10 ℃/h, is preferably 3-8 ℃/h; Method 2), in, the speed of cooling can be 1-8 ℃/h, is preferably 2-6 ℃/h; Method 3) in, the heat-up rate first heated up can be 1-10 ℃/h, is preferably 3-8 ℃/h, then the speed of cooling can be 1-8 ℃/h, is preferably 2-6 ℃/h, and the quality of final gained crystal can further improve.And in method 3) in, the temperature of the magma liquid preferably obtained after cooling can further improve the quality of crystal while than the initial temperature of magma liquid is maximum, hanging down 5 ℃.
After magma liquid heats up, the concave face of crystal can dissolve, the citric acid molecule on the anhydrous citric acid crystal surface that then promotion is separated out in the process of slow cooling is reset, and then can eliminate the depression of plane of crystal, then by cooling, make the citric acid molecule of dissolving again separate out more regularly the surface at already present crystal under gentle condition.Therefore, in the situation that take into account crystal mass and percent crystallization in massecuite, the present invention preferably adopts method 3) change the initial temperature of magma liquid so that crystal is repaired.
In the present invention, the temperature of the magma liquid of gained when the initial temperature of described magma liquid refers to citric acid solution evaporative crystallization terminal, and generally, the temperature of the magma liquid obtained during the evaporative crystallization terminal, be also that initial temperature is 50-70 ℃.
The present inventor is surprised to find, in cooling rate, be 1-8 ℃/h, be preferably under the condition of 2-6 ℃/h, the speed of the speed that the Citric Acid, usp, Anhydrous Powder molecule is separated out and crystal growth the more regular outward appearance of formation can reach good coordination, thereby it is more regular that anhydrous citric acid crystal is arranged, thereby crystal is had to good reparation, significantly reduce the probability of crystal entrainment mother liquor, the quality of the anhydrous citric acid crystal obtained can further be promoted.
In the present invention, the method that citric acid magma liquid is lowered the temperature can adopt the conventional cool-down method used in this area, for example, and the method that can adopt heat-eliminating medium to be lowered the temperature.Heat-eliminating medium can be the various materials that can realize the cooling down effect well known by persons skilled in the art, for example water coolant or cooling air.The preferred heat-eliminating medium of the present invention is water coolant.
According to the present invention, in order to make anhydrous citric acid crystal more even dispersedly, thereby make heat up and/or the process of cooling in temperature variation more consistent, and the Citric Acid, usp, Anhydrous Powder molecule of separating out can adhere to into brilliantly faster, the process of described intensification or cooling is carried out under the condition stirred.Optional a wider range of the speed of described stirring, only otherwise the outward appearance of separating out and not making crystal formation depression etc. affect crystal that affects crystal gets final product.Preferably, the speed of described stirring is 20-30rpm, more preferably 22-26rpm.
Well known to a person skilled in the art to be, by the citric acid solution evaporative crystallization, and the temperature that guarantees the citric acid concentrated solution is higher than 36.6 ℃, and what crystallization generated is anhydrous citric acid crystal.Wherein, the described method that citric acid solution is carried out to evaporative crystallization is conventionally known to one of skill in the art, for example, Citric Acid, usp, Anhydrous Powder generally adopts evaporative crystallization, first certain density citric acid feed liquid is evaporated, be evaporated to a certain degree natural graining, the magma liquid after graining continues evaporation, and crystal stops crystallization while growing into the about 45-55 % by weight of crystalline content.
In the present invention, while being repaired, the content of anhydrous citric acid crystal in magma liquid is not had to special requirement, but, in order to improve the crystal yield of final gained, in preferred described magma liquid, the content of anhydrous citric acid crystal is the 45-55 % by weight.
Described citric acid solution can be that the various solution that contains citric acid (usual solvents is water) is through removing the comparatively pure citric acid solution that various impurity obtains, in described citric acid solution, the content of citric acid can be chosen in a big way, from industrial production and economical point, in preferred described citric acid solution, the content of citric acid is the 55-65 % by weight.Described citric acid solution can be the raw materials such as potato dry powder, Tapioca Starch, Semen Maydis powder, potato powder, starch and glucose mother liquid, through the citric acid solution of fermented liquid after press filtration, neutralization, acidolysis, decolouring are processed of the microorganisms such as aspergillus niger fermentation.
In the present invention, the method also comprises, the feed liquid that obtains containing anhydrous citric acid crystal after repairing is carried out to solid-liquid separation, and the method for described solid-liquid separation can adopt and well known to a person skilled in the art the whole bag of tricks, methods such as vacuum filtration, settlement separate and centrifugation.In the preferred situation of the present invention, adopt the method for centrifugation, the rotating speed of centrifugation can be 60-800rpm, concrete to control rotating speed as follows: during to the magma liquid that adds in the rotary drum of whizzer after reparation, the rotating speed that maintains whizzer is 400-600rpm, does not add materials and while only being dewatered, the rotating speed that maintains whizzer is 600-800rpm, during discharging, the rotating speed that maintains whizzer is 60-100rpm.
According to the present invention, after carrying out solid-liquid separation, after can removing free-water by drying, the wet crystal of gained Citric Acid, usp, Anhydrous Powder obtains the anhydrous citric acid crystal product; Gained liquid can recycle, so that raw material is fully applied.Method and condition that described drying is removed free-water can adopt the whole bag of tricks known in the art and condition.For example, dry mode can be the drying mode of the various routines such as forced air drying, vacuum-drying, fluidized drying, preferably fluidized-bed fluidized drying mode; Preferably drying temperature is: hot blast 25-35 ℃, and cold wind is 5-20 ℃, be 10-30 minute time of drying.
Below will describe the present invention by embodiment.
In following examples and Comparative Examples:
Adopt the GB1987-2007 national standard method to measure the readily carbonizable substance in final gained anhydrous citric acid crystal;
In anhydrous citric acid crystal moisture determination adopt full-automatic karl Fischer moisture titration apparatus (purchased from Mei Tele company, model: DL55) measure;
The measuring method of anhydrous citric acid crystal content in magma liquid: take 1kg Citric Acid, usp, Anhydrous Powder magma liquid, after its centrifugation is dried, the amount of gained crystal and the ratio of 1kg magma liquid are crystalline content;
The method of the magma liquid after repairing being carried out to solid-liquid separation is: whizzer is purchased from Liaoyang friend's letter pharmaceutical machine Science and Technology Ltd., model is PGZ1600, concrete control rotating speed is as follows: while toward the rotary drum of whizzer is interior, adding the magma liquid obtained after reparation, the rotating speed that maintains whizzer is 500rpm, do not add materials and while only being dewatered, the rotating speed that maintains whizzer is 800rpm, and during discharging, the rotating speed that maintains whizzer is 60rpm.
Embodiment 1
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
(1) evaporative crystallization of citric acid solution
By 10m
3it is 15m that the citric acid solution that citric acid content is 60 % by weight injects effective volume
3crystallisation vessel in carry out evaporative crystallization, input speed is controlled as charging 4m per hour
3, the evaporation of charging limit, limit, the crystallization control temperature is 70 ℃, the stirring velocity of recycle pump is 750rpm.The time of crystallization control makes the content of anhydrous citric acid crystal in magma liquid reach 55 % by weight.
(2) to the reparation of crystal in magma liquid
The magma liquid of gained in step (1) is injected in dashpot, under the condition always stirred at 22rpm, with the speed of 3 ℃/hs, the temperature of magma liquid is risen to 75 ℃, and maintain 20 minutes, obtain the feed liquid that contains anhydrous citric acid crystal.The feed liquid that then with the speed of 2 ℃/hs, will contain anhydrous citric acid crystal is lowered the temperature, and is cooled to 70 ℃ and keep 10 minutes, starts blowing.And by centrifugal, magma liquid after repairing is carried out to solid-liquid separation and dry (25 ℃ of hot blasts, 10 ℃ of dryings of cold wind 30 minutes) obtain dry anhydrous citric acid crystal.After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The microscope picture of gained crystal as shown in Figure 1.
Embodiment 2
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
(1) evaporative crystallization of citric acid solution
By 9.2m
3it is 15m that the citric acid solution that citric acid content is 65 % by weight injects effective volume
3crystallisation vessel in carry out evaporative crystallization, input speed is controlled as charging 4.3m per hour
3, the evaporation of charging limit, limit, the crystallization control temperature is 50 ℃, the stirring velocity of recycle pump is 800rpm.The time of crystallization control makes the content of anhydrous citric acid crystal in magma liquid reach 45 % by weight.
(2) to the reparation of crystal in magma liquid
The magma liquid of gained in step (1) is injected in dashpot, under the condition always stirred at 26rpm, with the speed of 8 ℃/hs, the temperature of magma liquid is risen to 65 ℃, and maintain 10 minutes, obtain the feed liquid that contains anhydrous citric acid crystal.The feed liquid that then with the speed of 6 ℃/hs, will contain anhydrous citric acid crystal is lowered the temperature, and is cooled to 45 ℃ and maintain 20 minutes, starts blowing.And carry out solid-liquid separation and dry (35 ℃ of hot blasts, 20 ℃, cold wind, dry 20 minutes) obtain dry anhydrous citric acid crystal by the magma liquid to after repairing.After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The face shaping of gained crystal is similar to Example 1.
Embodiment 3
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
(1) evaporative crystallization of citric acid solution
By 11m
3it is 15m that the citric acid solution that citric acid content is 55 % by weight injects volume
3crystallisation vessel in carry out evaporative crystallization, input speed is controlled as charging 4.1m per hour
3, the evaporation of charging limit, limit, the crystallization control temperature is 58 ℃, the stirring velocity of recycle pump is 650rpm.The time of crystallization control makes the content of anhydrous citric acid crystal in magma liquid reach 50 % by weight.
(2) to the reparation of crystal in magma liquid
The magma liquid of gained in step (1) is injected in dashpot, under the condition always stirred at 24rpm, with the speed of 6 ℃/hs, the temperature of magma liquid is risen to 68 ℃, and maintain 15 minutes, obtain the feed liquid that contains anhydrous citric acid crystal.The feed liquid that then with the speed of 4 ℃/hs, will contain anhydrous citric acid crystal is lowered the temperature, and is cooled to 56 ℃ and maintain 15 minutes, starts blowing.And logical magma liquid after repairing is carried out to solid-liquid separation and dry (30 ℃ of hot blasts, 12 ℃, cold wind, dry 10 minutes) obtain dry anhydrous citric acid crystal.After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The face shaping of gained crystal is similar to Example 1.
Embodiment 4-5
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
Method according to embodiment 1 is carried out evaporative crystallization to citric acid solution and the crystal in the magma liquid obtained is repaired.Different, in embodiment 4 steps (2), the temperature of magma liquid is increased to 90 ℃ (having raise 20 ℃), then continues to be cooled to 75 ℃ (having reduced by 25 ℃); In embodiment 5 steps (2), the temperature of magma liquid is increased to 72 ℃ (having raise 2 ℃), then continues to be cooled to 70 ℃ (having reduced by 2 ℃).After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The face shaping of embodiment 4 and embodiment 5 gained crystal is poorer than embodiment 1, but is better than Comparative Examples 1.
Embodiment 6
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
Method according to embodiment 1 is carried out evaporative crystallization to citric acid solution and the crystal in the magma liquid obtained is repaired.Different, in step (2), with the speed of 10 ℃/hs, first magma liquid is heated up, and then lowered the temperature with the feed liquid that the speed of 8 ℃/hs will contain anhydrous citric acid crystal.After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The face shaping of gained crystal is poorer than embodiment 1, but is better than Comparative Examples 1.
Embodiment 7
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
Method according to embodiment 1 is carried out evaporative crystallization to citric acid solution and the crystal in the magma liquid obtained is repaired.Different, in step (2), in temperature-fall period, mixing speed is 30rpm.After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The face shaping of gained crystal is poorer than embodiment 1, but is better than Comparative Examples 1.
Embodiment 8
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
Method according to embodiment 1 is carried out evaporative crystallization to citric acid solution and the crystal in the magma liquid obtained is repaired.Different, in step (2), in temperature-fall period, mixing speed is 20rpm.After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The face shaping of gained crystal is poorer than embodiment 1, but is better than Comparative Examples 1.
Embodiment 9
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
Method according to embodiment 1 is carried out evaporative crystallization to citric acid solution and the crystal in the magma liquid obtained is repaired.Different, in step (2), magma liquid only to be heated up and do not lower the temperature, repair time is identical with the reparation total time in embodiment.The face shaping of gained crystal is poorer than embodiment 1, but is better than Comparative Examples 1.
Embodiment 10
The present embodiment is for illustrating the production method of anhydrous citric acid crystal provided by the invention.
Method according to embodiment 1 is carried out evaporative crystallization to citric acid solution and the crystal in the magma liquid obtained is repaired.Different, in step (2), to the processing of directly lowering the temperature of magma liquid, the temperature of reduction is 5 ℃, and repair time is identical with the reparation total time in embodiment.The face shaping of gained crystal is poorer than embodiment 1, but is better than Comparative Examples 1.
Comparative Examples 1
This Comparative Examples is for illustrating the production method of the anhydrous citric acid crystal that prior art provides.
Method evaporative crystallization from citric acid solution according to embodiment 1 obtains anhydrous citric acid crystal, different, and it is centrifugal, also dry that step (1) is directly carried out gained magma liquid after finishing, and obtains dry anhydrous citric acid crystal.After dry, readily carbonizable substance, moisture content and the transmittance of anhydrous citric acid crystal are in Table 1.The microscope picture of gained crystal as shown in Figure 2.
Table 1
| Embodiment/Comparative Examples numbering | Readily carbonizable substance | Moisture content (% by weight) | Transmittance (%) |
| Embodiment 1 | 0.31 | 0.05 | 99.9 |
| Embodiment 2 | 0.3 | 0.06 | 99.9 |
| Embodiment 3 | 0.31 | 0.06 | 99.9 |
| Embodiment 4 | 0.4 | 0.07 | 99.3 |
| Embodiment 5 | 0.4 | 0.07 | 98.7 |
| Embodiment 6 | 0.45 | 0.09 | 99.1 |
| Embodiment 7 | 0.42 | 0.08 | 99.2 |
| Embodiment 8 | 0.45 | 0.09 | 99.0 |
| Embodiment 9 | 0.4 | 0.07 | 99.3 |
| Embodiment 10 | 0.4 | 0.07 | 99.1 |
| Comparative Examples 1 | 0.9 | 0.18 | 97.2 |
From in table, embodiment 1-10 and Comparative Examples 1 are compared and can find out, the readily carbonizable substance of the anhydrous citric acid crystal that adopts method of the present invention to obtain and moisture content have obtained the reduction of significance.Embodiment 1 and embodiment 4-8 are compared and can find out, the speed of the temperature of the temperature of rising, reduction, intensification and cooling and mixing speed are controlled in the preferred scope of the present invention, the quality of gained anhydrous citric acid crystal has obtained further improvement.And, embodiment 1 and embodiment 9 and 10 relatively can be found out, the present invention adopts first the heat up mode of rear cooling of magma liquid is repaired crystal, and effect is better.Therefore, method provided by the invention can reduce carrying secretly of wet crystal mother liquor effectively, reduces readily carbonizable substance and moisture content, improves the transmittance of crystal.
The crystal picture of Fig. 2 by the Fig. 1 by embodiment 1 and Comparative Examples 1 compares to be found out, the crystal outward appearance that adopts method of the present invention to obtain is more neat, and depression, therefore, can not solve the residue problem of crystal depression position mother liquor.
More than describe the preferred embodiment of the present invention in detail; but the present invention is not limited to the detail in above-mentioned embodiment, in technical conceive scope of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.
It should be noted that in addition each the concrete technical characterictic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode.For fear of unnecessary repetition, the present invention is to the explanation no longer separately of various possible array modes.
In addition, between various embodiment of the present invention, also can carry out arbitrary combination, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.
Claims (9)
1. the production method of an anhydrous citric acid crystal, the method comprises, under the condition of circulation stirring, citric acid solution is carried out to crystallization, obtain magma liquid, it is characterized in that, the method also comprises that the initial temperature that changes magma liquid is repaired with the crystal in magma liquid, obtains the feed liquid that contains anhydrous citric acid crystal; The method of described change magma liquid initial temperature comprises:
1) by the magma liquid intensification 2-20 ℃ obtained after crystallization,
2) by the magma liquid cooling 1-10 ℃ obtained after crystallization, or
3) first by the magma liquid intensification 2-20 ℃ obtained after crystallization, then the cooling of the magma liquid after heating up 2-25 ℃.
2. method according to claim 1, wherein, method 1) in, by the magma liquid intensification 5-15 ℃ obtained after crystallization; Method 2) in, by the magma liquid cooling 2-8 ℃ obtained after crystallization; Method 3) in, first by the magma liquid intensification 5-15 ℃ obtained after crystallization, then the cooling of the magma liquid after heating up 5-20 ℃.
3. method according to claim 1 and 2, wherein, method 1) and 3) in, the speed that the magma liquid obtained after crystallization is heated up is 1-10 ℃/h, is preferably 3-8 ℃/h.
4. method according to claim 1 and 2, wherein, method 2) and 3) in, by the magma liquid cooling that obtains after crystallization or be 1-8 ℃/h by the speed of the magma liquid cooling after heating up again, be preferably 2-6 ℃/h.
5. according to the described method of any one in claim 1-4, wherein, described crystallization is evaporative crystallization, and the initial temperature of described magma liquid is 50-70 ℃.
6., according to the described method of any one in claim 1-5, wherein, method 3), the temperature of the magma liquid that obtains after the magma liquid cooling after heating up is hanged down to 5 ℃ than the initial temperature of magma liquid is maximum.
7. method according to claim 6, wherein, described reparation is carried out under the condition stirred, and the speed of described stirring is 20-30rpm.
8. method according to claim 7, wherein, the speed of described stirring is 22-26rpm.
9. method according to claim 1, wherein, in described magma liquid, the content of anhydrous citric acid crystal is the 45-55 % by weight.
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| CN111675610A (en) * | 2020-06-18 | 2020-09-18 | 湖南新绿方药业有限公司 | Refining method for preparing high-purity non-caking fine-particle citric acid crystal |
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| US20060247468A1 (en) * | 2003-03-31 | 2006-11-02 | A.E. Staley Manufacturing Company | Process for the recovery of citric acid |
| CN102964242A (en) * | 2012-12-07 | 2013-03-13 | 中粮生物化学（安徽）股份有限公司 | Citric acid crystal and production method thereof |
| CN102976925A (en) * | 2012-12-06 | 2013-03-20 | 中粮生物化学（安徽）股份有限公司 | Anhydrous citric acid crystal and production method thereof |
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| US20060247468A1 (en) * | 2003-03-31 | 2006-11-02 | A.E. Staley Manufacturing Company | Process for the recovery of citric acid |
| CN102976925A (en) * | 2012-12-06 | 2013-03-20 | 中粮生物化学（安徽）股份有限公司 | Anhydrous citric acid crystal and production method thereof |
| CN102964242A (en) * | 2012-12-07 | 2013-03-13 | 中粮生物化学（安徽）股份有限公司 | Citric acid crystal and production method thereof |
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| CN111675610A (en) * | 2020-06-18 | 2020-09-18 | 湖南新绿方药业有限公司 | Refining method for preparing high-purity non-caking fine-particle citric acid crystal |
| CN111675610B (en) * | 2020-06-18 | 2023-08-29 | 湖南新绿方药业有限公司 | Refining method for preparing high-purity non-caking fine-particle citric acid crystals |
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