CN109289234B - Device for evaporative crystallization and crystallization method of vitamin B6 - Google Patents
Device for evaporative crystallization and crystallization method of vitamin B6 Download PDFInfo
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- CN109289234B CN109289234B CN201811289985.9A CN201811289985A CN109289234B CN 109289234 B CN109289234 B CN 109289234B CN 201811289985 A CN201811289985 A CN 201811289985A CN 109289234 B CN109289234 B CN 109289234B
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- 238000002425 crystallisation Methods 0.000 title claims abstract description 196
- 230000008025 crystallization Effects 0.000 title claims abstract description 178
- LXNHXLLTXMVWPM-UHFFFAOYSA-N pyridoxine Chemical compound CC1=NC=C(CO)C(CO)=C1O LXNHXLLTXMVWPM-UHFFFAOYSA-N 0.000 title claims abstract description 142
- RADKZDMFGJYCBB-UHFFFAOYSA-N pyridoxal hydrochloride Natural products CC1=NC=C(CO)C(C=O)=C1O RADKZDMFGJYCBB-UHFFFAOYSA-N 0.000 title claims abstract description 71
- 239000011726 vitamin B6 Substances 0.000 title claims abstract description 71
- 235000019158 vitamin B6 Nutrition 0.000 title claims abstract description 71
- 229940011671 vitamin b6 Drugs 0.000 title claims abstract description 71
- 239000013078 crystal Substances 0.000 claims abstract description 154
- 239000002245 particle Substances 0.000 claims abstract description 115
- 238000001704 evaporation Methods 0.000 claims abstract description 107
- 230000008020 evaporation Effects 0.000 claims abstract description 99
- 238000000034 method Methods 0.000 claims abstract description 27
- 230000001939 inductive effect Effects 0.000 claims abstract description 5
- 239000007788 liquid Substances 0.000 claims description 122
- 239000002994 raw material Substances 0.000 claims description 92
- 239000012452 mother liquor Substances 0.000 claims description 47
- 239000002002 slurry Substances 0.000 claims description 32
- 239000000463 material Substances 0.000 claims description 22
- 230000008569 process Effects 0.000 claims description 18
- 239000002904 solvent Substances 0.000 claims description 18
- 238000007599 discharging Methods 0.000 claims description 11
- 238000005086 pumping Methods 0.000 claims description 2
- 239000008187 granular material Substances 0.000 claims 1
- 238000009834 vaporization Methods 0.000 abstract 1
- 230000008016 vaporization Effects 0.000 abstract 1
- 239000000047 product Substances 0.000 description 17
- 239000012065 filter cake Substances 0.000 description 14
- 238000004128 high performance liquid chromatography Methods 0.000 description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 238000001035 drying Methods 0.000 description 12
- 239000000243 solution Substances 0.000 description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 8
- 238000001914 filtration Methods 0.000 description 8
- 239000012043 crude product Substances 0.000 description 7
- 239000007787 solid Substances 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 239000000706 filtrate Substances 0.000 description 4
- 101000748157 Homo sapiens Ubiquitin carboxyl-terminal hydrolase 33 Proteins 0.000 description 3
- 102100040047 Ubiquitin carboxyl-terminal hydrolase 33 Human genes 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
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- 239000012530 fluid Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 208000003056 Vitamin B6 deficiency Diseases 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000003674 animal food additive Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000002778 food additive Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000008213 purified water Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000000935 solvent evaporation Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229940088594 vitamin Drugs 0.000 description 1
- 229930003231 vitamin Natural products 0.000 description 1
- 235000013343 vitamin Nutrition 0.000 description 1
- 239000011782 vitamin Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0018—Evaporation of components of the mixture to be separated
- B01D9/0031—Evaporation of components of the mixture to be separated by heating
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/62—Oxygen or sulfur atoms
- C07D213/63—One oxygen atom
- C07D213/65—One oxygen atom attached in position 3 or 5
- C07D213/66—One oxygen atom attached in position 3 or 5 having in position 3 an oxygen atom and in each of the positions 4 and 5 a carbon atom bound to an oxygen, sulphur, or nitrogen atom, e.g. pyridoxal
- C07D213/67—2-Methyl-3-hydroxy-4,5-bis(hydroxy-methyl)pyridine, i.e. pyridoxine
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Peptides Or Proteins (AREA)
Abstract
The invention provides a device for evaporative crystallization, which comprises an evaporation container and a crystallization container, and further comprises a first circulation unit and a second circulation unit, wherein the first circulation unit comprises a first branch pipe, a first circulation pump and a first circulation inlet pipe which are sequentially connected; the second circulation unit comprises a second branch pipe, a second circulation pump, a heater and a second circulation inlet pipe which are sequentially connected, and the first circulation inlet pipe and the second circulation inlet pipe are connected to the evaporation container. The invention also provides a crystallization method of the vitamin B6. The method provides an additional first circulation loop to reintroduce the first fine crystals into the vaporization vessel as nuclei for growing larger second particles and inducing more and more uniform second particles.
Description
Technical Field
The invention relates to the field of chemical process improvement, in particular to a device for evaporative crystallization and a crystallization method of vitamin B6.
Background
Vitamin B6 is one of essential vitamins for human body, is mainly used for vitamin B6 deficiency in clinic, is widely used as food and feed additives, and has large market demand.
At present, the vitamin B6 crystallization mainly adopts the following methods:
a) the general method (journal of Chinese medicine industry, 2004,35(1):1-2) is: dissolving the vitamin B6 crude product in purified water, adding activated carbon for decoloring twice, concentrating the filtrate, cooling and crystallizing to obtain first crystals. And then dissolving the primary crystals in water again, adding active carbon for decoloring, concentrating the filtrate after the third decoloring, cooling for crystallization, filtering and drying to obtain the product. The product prepared by the process has poor crystal form and large particles, the 40-mesh passing rate is less than 40 percent, and the product needs to be crushed. And the crushed product has irregular crystals and poor fluidity and is difficult to meet the requirements of customers.
b) Chinese patent application CN102295598A discloses a crystallization method of vitamin B6, which comprises the steps of firstly dissolving 100g of vitamin B6 crude product in water, adding 300-600 mL of ethanol into filtrate after decoloring by active carbon, crystallizing, filtering, washing filter cakes by ethanol, and drying to obtain the product. Although the method can obtain crystals with small particles and uniform granularity, the crystallization uses a large amount of ethanol, and the cost for industrially recovering the ethanol is high, so the method is not suitable for industrial mass production.
c) The chinese invention application CN104710352A discloses a crystallization method of vitamin B6, which specifically comprises the following steps: dissolving the vitamin B6 crude product in water, decoloring, concentrating the filtrate, heating the concentrated solution to 50-100 ℃ for dissolving, dripping the dissolved concentrated solution into a vitamin B6 refined saturated aqueous solution at 0-40 ℃, and stirring for crystallization to obtain the product. Although crystals with smaller particles and good fluidity can be obtained by the method, hot concentrated solution is dripped into cold saturated solution, and due to sudden temperature drop, the growth of the crystals cannot keep up with the increase of supersaturation, so that the supersaturation in the solution is accumulated, crystal nuclei are generated too fast, the crystals wrap impurities, and the quality of the crystals is influenced. On the other hand, each crystallization of the method needs to consume 10-50% of the refined product, the refining total yield is low (the crystallization yield is lower than 60% after the refined product is consumed), and the economic cost is high.
In summary, the vitamin B6 crystallization production currently mostly adopts an intermittent operation mode, such as evaporative crystallization, cooling crystallization, elution crystallization and the like, the equipment demand is large, the investment is large, the production efficiency is low, the crystal particle size is difficult to control, the crushing treatment is needed, the crushed crystal has poor fluidity and is easy to agglomerate, and the processing requirement cannot be met. Batch crystallization operations also suffer from large variations in product quality from batch to batch.
Disclosure of Invention
In view of the above problems, the present invention provides a crystallization method capable of directly obtaining vitamin B6 with high purity, uniform and regular crystal grains and controllable size, and an apparatus for evaporative crystallization.
The present invention provides an apparatus for evaporative crystallization for crystallization, comprising:
the evaporation container is used for evaporating the solvent, a flow guide pipe is arranged at the bottom of the evaporation container, and an evaporation gas outlet is also arranged at the top of the evaporation container;
the crystallization container is used for crystallization, the crystallization container is positioned below the evaporation container, the flow guide pipe extends into the crystallization container and is communicated with the crystallization container, and a crystal slurry discharge port is arranged at the bottom of the crystallization container; wherein,
a circulating material outlet pipe is connected to the side wall of the crystallization container and is branched into a first branch pipe and a second branch pipe;
the device for evaporative crystallization further comprises a first circulating unit and a second circulating unit, wherein the first circulating unit comprises a first branch pipe, a first circulating pump and a first circulating inlet pipe, and the first branch pipe is connected with the first circulating pump; the first circulation inlet pipe is provided with a first end and a second end, the first end of the first circulation inlet pipe is connected with the first circulation pump, and the second end of the first circulation inlet pipe is connected with the evaporation container;
the second circulation unit comprises a second branch pipe, a second circulation pump, a heater and a second circulation inlet pipe, the second branch pipe is sequentially connected with the second circulation pump and the heater, the second circulation inlet pipe is provided with a third end and a fourth end, the third end of the second circulation inlet pipe is connected with the heater, and the fourth end of the second circulation inlet pipe is connected with the evaporation container;
the device for evaporative crystallization further comprises a raw material liquid inlet pipe, wherein the raw material liquid inlet pipe is connected to the second branch pipe and is used for pumping the raw material liquid to the heater through a second circulating pump.
The invention also provides a crystallization method of vitamin B6, which comprises the following steps:
(1) providing the above apparatus for evaporative crystallization;
(2) continuously injecting a raw material liquid into the raw material liquid inlet pipe, wherein the mass fraction of vitamin B6 in the raw material liquid is 10-50%, and the temperature of the raw material liquid is 20-80 ℃;
(3) and (3) evaporation: the raw material liquid enters the evaporation container through a second branch pipe, a second circulating pump, a heater and a second circulating inlet pipe, the vacuum degree of the evaporation container is controlled to be 0.08-0.097 MPa, and a solvent in the raw material liquid is evaporated to obtain an evaporation treatment liquid;
(4) and (3) crystallization: the evaporation treatment liquid enters a crystallization container through the flow guide pipe, and crystallization is carried out in the crystallization container to obtain crystallization particles and mother liquid, wherein the crystallization particles comprise first particles with larger particle size and fine crystal particles with smaller particle size;
(5) shunting: when the overall height of the crystallization particles and the mother liquor reaches or exceeds the circulating material outlet pipe, the fine crystal particles and the mother liquor enter the circulating material outlet pipe and are branched, wherein the mother liquor is branched into a first mother liquor and a second mother liquor, the fine crystal particles are branched into a first fine crystal and a second fine crystal, the first fine crystal and the first mother liquor flow into a first branch pipe, the second fine crystal and the second mother liquor flow into a second branch pipe, and the first particles are settled at the bottom of a crystallization container;
(6) the second fine crystals and the second mother liquor flowing into the second branch pipe continue to carry out crystallization in the next period, namely evaporation in the step (3), crystallization in the step (4) and flow division in the step (5);
(7) the first fine crystals and the first mother liquor flowing into the first branch pipe enter the evaporation container through the first circulating pump and the first circulating inlet pipe, and the next period of crystallization, namely the evaporation in the step (3), the crystallization in the step (4) and the diversion in the step (5) are carried out continuously, wherein the first fine crystals are used as crystal nuclei for inducing to obtain second particles with larger particle sizes and are settled to the bottom of the crystallization container;
(8) and (3) discharging the crystal mush containing the first particles and the second particles from a crystal mush discharge port to obtain a finished product of vitamin B6. (ii) a
The device for evaporative crystallization has the following advantages:
because of the action of multi-strand acting force (fluid acting force from the evaporation container, acting force brought by discharging, acting force brought by the first circulating pump and the second circulating pump), the crystallization liquid in the crystallization container is in a turbulent flow state, the occurrence of crystal agglomeration can be effectively avoided, and the size of precipitated crystal particles can be controlled; meanwhile, the turbulent flow state further promotes the separation of large and small crystals, and the fine crystal grains in the crystals are circularly led into the heater and the evaporation container under the action of the first circulating pump and the second circulating pump. The first fine crystals circulated directly into the evaporation vessel serve as nuclei for recrystallization in the next cycle, so that the second particles are precipitated more rapidly and are formed into second particles of more uniform size.
The second branch pipe is internally provided with a heater which can give heat to the raw material liquid or the second mother liquid conveyed by the second circulation unit so as to promote the raw material liquid or the second mother liquid to evaporate part of the solvent in the evaporation container, and the crystallization of the raw material liquid or the second mother liquid in the crystallization container is more facilitated. The device can realize continuous formation of vitamin B6 finished products, has high crystallization efficiency, and is suitable for industrial production.
Further, when the crystallization container is internally provided with the rectification classifier, the rectification classifier can comb disordered flow field distribution in the crystallization container (without the rectification classifier), so that the flow path lengths of liquid flows below the rectification classifier tend to be consistent, the flow velocities of all liquid flows tend to be consistent, the flow field distribution is regular and ordered, and more uniform precipitation of crystal particles is promoted. Meanwhile, a flow speed difference is formed between the inside of the passage of the rectifying classifier and the lower part of the rectifying classifier, and because the lower flow speed below the rectifying classifier is powerless to continuously entrain the larger first particles, the larger first particles are precipitated in the entrainment process of the low-flow-speed fluid below the rectifying classifier, and the fine particles entrained to the vicinity of the passage of the rectifying classifier by the liquid flow below the rectifying classifier are entrained by the high-flow-speed liquid flow in the passage of the rectifying classifier, are circularly guided into the heater to be reheated and dissolved, and are circularly guided into the evaporation container to be used as crystal nuclei. The whole process can achieve the effects of screening and separating crystallized particles by adjusting the aperture ratio of the channel and the size ratio of the channel, so that the first particles and the second particles with more uniform and controllable particle sizes are finally obtained.
The crystallization method of vitamin B6 has the following advantages:
crystallizing the raw material liquid to obtain vitamin B6 crystal particles, by shunting fine crystal particles contained in the crystal particles, directly reintroducing the first fine crystals into the evaporation container and introducing the first fine crystals into the crystallization container along with the evaporation treatment liquid to serve as crystal nuclei for crystallization in the next period, and finally slowly growing the crystal nuclei to obtain second particles with target sizes and inducing more second particles to be separated out more quickly. The method is provided with an additional first circulation loop, and the first fine crystals are reintroduced into the evaporation container to be used as crystal nuclei, so that more second particles with more uniform particle size distribution are finally obtained. The crystallization yield of the method reaches more than 85 percent, the HPLC purity is more than 99.8 percent, the obtained product has smooth crystal face, good fluidity and uniform particle size, and the 40-mesh passing rate is more than 99 percent.
Furthermore, when the crystallization container is internally provided with the rectification classifier, the rectification classifier can comb out disordered flow field distribution in the crystallization container (without the rectification classifier), so that the flow path lengths of liquid flows below the rectification classifier tend to be consistent, the flow velocities of all liquid flows tend to be consistent, the flow field distribution is regular and ordered, and more uniform precipitation of crystal particles is promoted. Meanwhile, a flow speed difference is formed between the inside of the passage of the rectification classifier and the lower part of the rectification classifier, and because the lower flow speed below the rectification classifier is powerless to continuously entrain larger crystal particles, the larger first particles are precipitated in the entrainment process of the low-flow-speed fluid below the rectification classifier, and the fine crystal particles which are entrained to the vicinity of the passage of the rectification classifier by the liquid flow below the rectification classifier are entrained by the high-flow-speed liquid flow in the passage of the rectification classifier, are circularly guided into the heater to be reheated and dissolved, and are circularly guided into the evaporation container to be used as crystal nuclei. The whole process can achieve the functions of screening and separating crystallized particles by adjusting the aperture ratio of the channel and the size ratio of the channel, so that a product with more uniform and controllable particle size is finally obtained.
Further, the ratio of the evaporation speed of the solvent in the raw material liquid to the feeding speed of the raw material liquid is set to be 0.1-0.9, and the ratio of the discharging speed of the crystal slurry to the feeding speed of the raw material liquid is set to be 0.1-0.9, so that the supersaturation degree of the mother liquid is maintained, and the crystallization process can be continuous.
Further, by setting the ratio of the flow rate of the first stream to the flow rate of the second stream to 1: 100-10: 1, obtaining products with uniform particle size, and carrying out large-scale industrial production by the method.
Drawings
FIG. 1 is a schematic diagram of the structure and flow of an apparatus for evaporative crystallization according to embodiment 1 of the present invention.
FIG. 2 is a schematic diagram of the structure and flow of an apparatus for evaporative crystallization according to embodiment 2 of the present invention.
FIG. 3 is a schematic view of a rectifying classifier in the apparatus for evaporative crystallization of FIG. 2.
Wherein, 1, raw material liquid enters a pipe; 2a, a first branch pipe; 2b, second branch pipes; 3. a second circulation pump; 4. a heater; 5. a second circulation inlet pipe; 6. an evaporation vessel; 7. a flow guide pipe; 8. a crystallization vessel; 9. a defoaming and defoaming device; 10. an evaporation gas outlet; 11. a balance tube; 12. a circulating material outlet pipe; 13. a first circulation pump; 14. a first circulation inlet pipe; 15. discharging the crystal slurry; 16. a centrifuge; 17. a rectification classifier; 18. a channel.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Referring to fig. 1, an apparatus for evaporative crystallization is provided in embodiment 1 of the present invention. The device for evaporative crystallization comprises an evaporation container 6, a crystallization container 8, the crystallization container 8 is located below the evaporation container 6, the evaporation container 6 is used for evaporating a solvent, the crystallization container 8 is used for crystallization, an evaporation gas outlet 10 is arranged at the top of the evaporation container 6, a flow guide pipe 7 is arranged at the bottom of the evaporation container 6, the flow guide pipe 7 extends into the crystallization container 8 and is communicated with the crystallization container 8, a circulating material outlet pipe 12 is connected to the side wall of the crystallization container 8, and the circulating material outlet pipe 12 is branched into a first branch pipe 2a and a second branch pipe 2 b.
The evaporator for evaporative crystallization further comprises a first circulation unit and a second circulation unit, wherein the first circulation unit comprises a first branch pipe 2a, a first circulation pump 13 and a first circulation inlet pipe 14, the first branch pipe 2a is connected with the first circulation pump 13, the first circulation inlet pipe 14 is provided with a first end and a second end, the first end of the first circulation inlet pipe 14 is connected with the first circulation pump 13, and the second end of the first circulation inlet pipe 14 is connected with the evaporation container 6.
The second circulation unit includes that the second divides pipe 2b, second circulating pump 3, heater 4 and second circulation to advance pipe 5, and second divides pipe 2b to be connected with second circulating pump 3, heater 4 in proper order, and the second circulation advances pipe 5 and has third end and fourth end, the second circulation advance the third end of pipe 5 with heater 4 links to each other, and the fourth end that the pipe 5 was advanced in the second circulation is connected to evaporating vessel 6.
The apparatus for evaporative crystallization further comprises a raw material liquid inlet pipe 1, and the raw material liquid inlet pipe 1 is connected to the second branch pipe 2b and is used for sending the raw material liquid to the heater 4 by the second circulation pump 3.
There are two circulation loops outside the crystallization vessel 8 and the evaporation vessel 6. The first circulation loop (corresponding to the first circulation unit) is: a crystallization container 8, a circulating material outlet pipe 12, a first branch pipe 2a, a first circulating pump 13, a first circulating inlet pipe 14 and an evaporation container 6; the second circulation loop (corresponding to the second circulation unit) is: crystallization container 8, circulating material outlet pipe 12, second branch pipe 2b, second circulating pump 3, heater 4, second circulation inlet pipe 5 and evaporation container 6. The second branch pipe 2b also serves to continuously introduce the raw material liquid into the second circulation circuit by being connected to the raw material liquid inlet pipe 1.
The first circulation loop is used to introduce a portion of the mother liquor (defined as first mother liquor) in the crystallization vessel 8 and a portion of the fine crystal grains resulting from the crystallization (defined as first fine crystals) directly to the evaporation vessel 6, which portion of the fine crystal grains can serve as crystallization nuclei for the next cycle, thereby inducing more uniform crystallization grains. It should be noted that the first fine crystals continue to grow to produce larger and more uniform second grains, and that the re-entry of the first fine crystals into the crystallization vessel 8 also induces the formation of more second grains in an orderly manner, i.e. the effect of the first circulation loop is divided into two aspects: one is to allow a greater number of second particles to form; secondly, the first fine crystal is grown into uniform second particles.
The second circulation loop is used for feeding another part of mother liquor (defined as second mother liquor) in the crystallization vessel 8 and another part of fine crystal grains (defined as second fine crystals) obtained by crystallization into the evaporation vessel 6 by the action of the heater 4, and the solvent is evaporated and then fed into the crystallization vessel 8 for crystallization in the next cycle.
The evaporation vessel 6 usually needs no additional heating, and the temperature of the raw material liquid or the second mother liquid flowing in from the second circulation inlet pipe 5 rises after being heated by the heater 4, so that the raw material liquid or the second mother liquid can evaporate part of the solvent in the evaporation vessel 6. In order to avoid the yield loss caused by the entrainment of part of the product by the foam generated in the solvent evaporation process, a defoaming and defoaming device 9 is arranged in the evaporation container 6 near the evaporation gas outlet 10, and the defoaming and defoaming device 9 can be a screen structure or other types of defoaming and defoaming devices.
The side wall of the evaporation container 6 and the side wall of the crystallization container 8 are also provided with balance pipes 11, and the balance pipes 11 are communicated with the evaporation container 6 and the crystallization container 8.
And a crystal slurry discharge port 15 is arranged at the bottom of the crystallization container 8.
Referring to fig. 2, an apparatus for evaporative crystallization is provided in embodiment 2 of the present invention. The apparatus for evaporative crystallization has substantially the same structure as that of the apparatus for evaporative crystallization of example 1 except that: a rectifying and classifying device 17 is provided in the crystallization vessel 8. Referring to fig. 3, the rectifier classifier 17 includes a plurality of channels 18. The role of the rectifying classifier 17 is to obtain more uniform crystalline particles.
The dimensions of the lower end of the channel 18 are greater than the dimensions of the upper end of the channel 18, which is a design goal in two respects: (1) the occurrence of the phenomenon of particle back mixing is prevented; (2) the possibility of clogging the channels 18 is avoided.
The ratio of the size of the lower end of the channel 18 to the size of the upper end of the channel 18 is 1.1:1 to 10:1, and preferably, the ratio of the size of the lower end of the channel 18 to the size of the upper end of the channel 18 is 1.5:1 to 5: 1.
The upper end of the channel 18 has a dimension of 3 mm to 100 mm, preferably 5 mm to 50 mm.
The open area ratio (i.e., the sum of the areas of the upper ends of the channels as a percentage of the area of the upper surface of the rectifying classifier) of the plurality of channels 18 is 5% to 50%, preferably 10% to 30%.
The device for evaporative crystallization has the following advantages:
the evaporation container 6 is used for evaporating the solvent in the raw material liquid, the crystallization container 8 is used for crystallization, and the circulating material outlet pipe 12 is branched into the first branch pipe 2a and the second branch pipe 2b, the first branch pipe 2a is used for guiding first fine grains formed by crystallization of the raw material liquid into the evaporation container 6 again, the first fine grains can be used as crystal nuclei for crystallization in the next period, so that second grains are grown, and more uniform second grains are induced to be formed; the second branch pipe 2b is provided with a heater 4 for giving heat to the raw material liquid or the second mother liquid to partially evaporate the solvent in the evaporation vessel 6, which is more advantageous for the crystallization of the raw material liquid or the second mother liquid in the crystallization vessel 8.
The invention also provides a crystallization method of the vitamin B6. The crystallization method comprises the following steps:
(1) providing a device for evaporative crystallization;
(2) continuously injecting a raw material liquid into the raw material liquid inlet pipe 1, wherein the mass fraction of vitamin B6 in the raw material liquid is 10-50%, and the temperature of the raw material liquid is 20-80 ℃;
(3) and (3) evaporation: the raw material liquid enters the evaporation container 6 through a second branch pipe 2b, a second circulating pump 3, a heater 4 and a second circulating inlet pipe 5, the vacuum degree of the evaporation container is controlled to be 0.08 MPa-0.097 MPa, and a solvent in the raw material liquid is evaporated to obtain an evaporation treatment liquid;
(4) and (3) crystallization: the evaporation treatment liquid enters a crystallization container 8 through the draft tube 7, and crystallization is carried out in the crystallization container 8 to obtain crystallization particles and mother liquid, wherein the crystallization particles comprise first particles with larger particle size and fine crystal particles with smaller particle size;
(5) shunting: when the overall height of the crystallization particles and the mother liquor reaches or exceeds the circulating material outlet pipe 12, fine crystal particles in the crystallization particles and the mother liquor enter the circulating material outlet pipe 12 and branch off, wherein the mother liquor branches off into a first mother liquor and a second mother liquor, the fine crystal particles branch off into a first fine crystal and a second fine crystal, the first fine crystal and the first mother liquor flow into a first branch pipe 2a, the second fine crystal and the second mother liquor flow into a second branch pipe 2b, and the first particles settle at the bottom of the crystallization container;
(6) the second fine crystals and the second mother liquor flowing into the second branch pipe 2b continue to be crystallized in the next period, namely, the evaporation in the step (3), the crystallization in the step (4) and the diversion in the step (5);
(7) the first fine crystals and the first mother liquor flowing into the first branch pipe 2a enter the evaporation container 6 through the first circulating pump 13 and the first circulating inlet pipe 14, and continue to perform the next period of crystallization, namely evaporation in step (3), crystallization in step (4) and diversion in step (5), wherein the first fine crystals are used as crystal nuclei to induce second particles with larger particle size to settle to the bottom of the crystallization container;
(8) and (3) discharging the crystal mush containing the first particles and the second particles from a crystal mush discharge port 15 to obtain a finished product of vitamin B6.
Wherein the mass fraction of the vitamin B6 in the raw material liquid in the step (2) is preferably 20-35%, and the temperature of the raw material liquid is 40-70 ℃.
And (2) injecting the raw material liquid from the raw material liquid inlet pipe 1 to the step (8) of leading out the crystal slurry from the crystal slurry discharge hole 15 for the first time for 1-8 hours. The ratio of the evaporation rate of the solvent in the raw material liquid to the feeding rate of the raw material liquid is 0.1-0.9, preferably 0.35-0.75. This is because more feed solution is injected for the first crystallization to provide sufficient vitamin B6 in the crystallization vessel 8 to achieve the proper supersaturation and residence time. The timing of discharging the crystal slurry may be determined based on the solid content of the crystal particles (including the first particles and the second particles) in the crystallization vessel 8. For example, when the solid content is greater than 53%, the discharge port 15 of the slurry may be opened to discharge the slurry. Of course, in the subsequent flow, the raw material liquid is continuously injected from the raw material liquid inlet pipe 1, and the slurry can be continuously obtained at the slurry outlet 15.
Defining the sum of the first fine crystals and the first mother liquor as a first stream and the sum of the second fine crystals and the second mother liquor as a second stream. In the case that the total amount of the mother liquor and the fine crystal grains is constant and the fine crystal grains are uniformly distributed, it can be considered that the ratio of the first fine crystal to the second fine crystal is equal to the ratio of the flow rate of the first stream to the flow rate of the second stream. In the invention, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 1: 100-10: 1, so that the ratio of the first fine crystals can be controlled, and the ratio of the crystal nuclei circulating back to the evaporation container 6 can be controlled. Preferably, the ratio of the flow rate of the first stream to the flow rate of the second stream is 1: 10-4: 5.
In the evaporation process of the step (3), the temperature of the raw material liquid or the second mother liquid flowing into the second branch pipe 2b is increased to 30 to 90 ℃ after passing through the heater 4. Preferably, the temperature of the raw material liquid or the second mother liquid flowing into the second branch pipe 2b is increased to 50 to 70 ℃ after passing through the heater 4.
In the evaporation process in the step (3), the vacuum degree of the evaporation container 6 is preferably 0.085 to 0.097 MPa.
During the diversion in the step (5), a rectification classifier 17 can be arranged in the crystallization vessel 8. When the total height of the crystallized particles and the mother liquor reaches or exceeds the position where the circulating material outlet pipe 12 is connected to the crystallization vessel 8, the fine-grained particles and the mother liquor enter the circulating material outlet pipe 12 through the rectification classifier 17. The role of the classifier 17 is to make the fine-grained particles enter the recycled material outlet pipe 12, while the first larger-grained particles remain in the crystallization vessel 8, and finally to achieve a uniform product grain. It will be appreciated that the bottom of the crystallization vessel 8 may be provided with a tapered region to facilitate classification of the crystal particles and more convenient discharge.
And (3) injecting the raw material liquid from the raw material liquid inlet pipe to the step (8) of leading out the crystal slurry from the crystal slurry discharge hole for the first time for 1-8 hours. After the first time of discharging the crystal slurry from the crystal slurry discharging port 15, the ratio of the evaporation rate of the solvent in the raw material liquid to the feeding rate of the raw material liquid is adjusted to be small. And (3) adjusting the ratio of the discharging speed of the crystal slurry in the step (8) to the feeding speed of the raw material liquid in the step (2) to be 0.1-0.9. The material residence time can be calculated by dividing the total amount of material in steady state operation of the evaporative crystallization apparatus of the present invention by the discharge rate. Preferably, in order to maintain a suitable supersaturation degree and residence time and thus ensure uniform particle size distribution of the final crystal particles, the ratio of the discharge speed of the crystal slurry in step (8) to the feed speed of the raw material liquid in step (2) is 0.25 to 0.65.
After the step (8), the slurry containing the first particles and the second particles is discharged through the slurry discharge port 15, centrifuged by the centrifuge 16 to obtain a cake and a mother liquor obtained by centrifugation, and the mother liquor obtained by centrifugation is recovered and circulated to the raw material liquid inlet pipe 1.
The crystallization method of vitamin B6 has the following advantages:
the raw material liquid is crystallized to obtain vitamin B6 crystal particles, and the first fine crystals are directly reintroduced into the evaporation vessel 6 and enter the crystallization vessel 8 along with the evaporation treatment liquid by shunting the fine crystal particles contained therein, so as to be used as crystal nuclei for the crystallization in the next period, and finally, the crystal nuclei are slowly grown to obtain more second particles with more uniform crystal grains.
The crystallization process of vitamin B6 according to the present invention will be further illustrated by the following examples.
The purity range of the vitamin B6 crude product in the embodiment is selected to be 98-99%.
The data and effects in the embodiments of the present invention do not limit the practical application range of the technology of the present invention.
Example 1
In this example, the crystallization operation was carried out using the apparatus for evaporative crystallization shown in FIG. 1, and specifically, the following steps were carried out:
(1) dissolving a vitamin B6 crude product with HPLC purity of 98% in water, decoloring and filtering to obtain a raw material solution of vitamin B6 with mass percent concentration of 23%, wherein the temperature is 40 ℃.
(2) The heater 4 is started, raw material liquid of vitamin B6 is pumped from the raw material liquid inlet pipe 1 and is conveyed to the heater 4 through the second circulating pump 3, and the temperature of the raw material liquid is raised to 55 ℃. The heated raw material liquid was continuously fed into the evaporation vessel 6 at a rate of 220 kg/h.
(3) Controlling the vacuum degree of the evaporation container 6 to be 0.095MPa, leading the raw material liquid to reach a boiling state after entering the evaporation container 6, keeping the evaporation speed of water at 141kg/h, evaporating a large amount of solvent, and leading the concentrated solution to enter the crystallization container 8 through the draft tube 7. When the liquid level in the crystallization container 8 reaches the circulating material outlet pipe 12 and can realize circulating flow, the feeding speed of the raw material liquid is reduced to 141kg/h, the flow rate of the second circulating pump 3 is controlled at 1200kg/h, the flow rate of the first circulating pump 13 is controlled at 318kg/h, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled at 0.3, and the stability is maintained for 3 hours.
(4) When the solid content of the conical settling zone at the bottom of the crystallization container 8 reaches 55%, a valve of a crystal slurry discharge port 15 at the bottom of the crystallization container 8 is opened, the crystal slurry in the crystallization container 8 enters a continuous centrifuge 16 at the flow rate of 79kg/h for filtration, a filter cake is washed by process water and then continuously discharged, and filtered mother liquor can be circulated to a raw material liquor inlet pipe 1 after concentration and decoloration treatment.
(5) After the discharge of the crystal slurry in the crystallization vessel 8 was started, the feed rate of the raw material liquid was adjusted to 220kg/h, the flow rate of the first circulation pump 13 was controlled to 294kg/h, and the ratio of the flow rate of the first stream to the flow rate of the second stream was controlled to 0.3.
(6) And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.96 percent based on the feed amount, the crystallization yield is 89.10 percent, the 40-mesh passing rate of the vitamin B6 crystal particles is 100 percent, the 60-mesh passing rate is 60 percent, and the 100-mesh passing rate is 4 percent, and the requirements of CP2015, EP8.0 and USP33 are met.
Example 2
In this example, the crystallization operation was carried out using the apparatus for evaporative crystallization shown in FIG. 2, and specifically, the following steps were carried out: (1) dissolving a vitamin B6 crude product with HPLC purity of 98% in water, decoloring and filtering to obtain a raw material solution of vitamin B6 with mass percent concentration of 23%, wherein the temperature is 40 ℃.
(2) The heater 4 is started, raw material liquid of vitamin B6 is pumped from the raw material liquid inlet pipe 1 and is conveyed to the heater 4 through the second circulating pump 3, and the temperature of the raw material liquid is raised to 55 ℃. The heated raw material liquid was continuously fed into the evaporation vessel 6 at a rate of 220 kg/h. The diameter of the upper end of the channel 18 was 30 mm, the ratio of the diameter of the lower end of the channel 18 to the diameter of the upper end of the channel 18 was 2:1, and the open porosity of the channel was 20%.
(3) Controlling the vacuum degree of the evaporation container 6 to be 0.095MPa, leading the raw material liquid to reach a boiling state after entering the evaporation container 6, keeping the evaporation speed of water at 141kg/h, evaporating a large amount of solvent, and leading the concentrated solution to enter the crystallization container 8 through the draft tube 7. When the liquid level in the crystallization container 8 reaches the circulating material outlet pipe 12 and can realize circulating flow, the feeding speed of the raw material liquid is reduced to 141kg/h, the flow rate of the second circulating pump 3 is controlled at 1200kg/h, the flow rate of the first circulating pump 13 is controlled at 318kg/h, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled at 0.3, and the stability is maintained for 3 hours.
(4) When the solid content of the conical settling zone at the bottom of the crystallization container 8 reaches 55%, a valve of a crystal slurry discharge port 15 at the bottom is opened, the crystal slurry in the crystallization container 8 enters a continuous centrifuge 16 at the flow rate of 79kg/h for filtration, a filter cake is washed by process water and then continuously discharged, and filtered mother liquor can be circulated to a raw material liquid inlet pipe 1 after concentration and decoloration treatment.
(5) After the crystal slurry in the crystallizer starts to be discharged, the feeding speed of the raw material liquid is adjusted to 220kg/h, the flow rate of the first circulating pump 13 is controlled to be 294kg/h, and the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 0.3.
(6) And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.93%, and the crystallization yield is 88.70% in terms of the feed amount, wherein the 40-mesh passing rate of the vitamin B6 crystal particles is 100%, the 60-mesh passing rate is 44%, and the 100-mesh passing rate is 0.2%, and the requirements of CP2015, EP8.0 and USP33 are met.
Example 3
On the basis of the example 2, the flow rate of the first circulating pump 13 in the step (3) is set to 423kg/h, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 0.4, the flow rate of the first circulating pump 13 in the step (5) is controlled to be 392kg/h, and the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 0.4; the other conditions were the same as in example 2. And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.90%, and the crystal yield is 89.03% in terms of the feed amount, and the 40-mesh passing rate, the 60-mesh passing rate and the 100-mesh passing rate of the vitamin B6 crystal particles are 100%, 80% and 8%.
Example 4
On the basis of the example 2, the flow rate of the first circulating pump 13 in the step (3) is set to be 212kg/h, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 0.2, the flow rate of the first circulating pump 13 in the step (5) is controlled to be 196kg/h, and the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 0.2; the other conditions were the same as in example 2. And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.95%, and the crystal yield is 89.00% in terms of the feed amount, and the 40-mesh passing rate, the 60-mesh passing rate and the 100-mesh passing rate of the vitamin B6 crystal particles are 99.5%, 50% and 0.5%, respectively.
Example 5
On the basis of example 2, the flow rate of the first circulating pump 13 in step (3) is set to be 53kg/h, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 0.05, the solid content in the conical settling zone in step (4) reaches 54%, the flow rate of the first circulating pump 13 in step (5) is controlled to be 49kg/h, and the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 0.05; the other conditions were the same as in example 2. And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.88%, and the crystal yield is 86.60% in terms of the feed amount, and the 40-mesh passing rate, the 60-mesh passing rate and the 100-mesh passing rate of the vitamin B6 crystal particles are 100%, 83% and 14%.
Example 6
On the basis of example 2, the flow rate of the first circulating pump 13 in step (3) is set to 1059kg/h, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 1, the solid content in the conical settling area in step (4) reaches 53%, the flow rate of the first circulating pump 13 in step (5) is controlled to be 980kg/h, and the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to be 1; the other conditions were the same as in example 2. And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.85%, and the crystal yield is 85.50% in terms of the feed amount, and the 40-mesh passing rate, the 60-mesh passing rate and the 100-mesh passing rate of the vitamin B6 crystal particles are 100%, 84% and 16%.
Example 7
In this example, the crystallization operation was carried out using the apparatus for evaporative crystallization shown in FIG. 2, and specifically, the following steps were carried out:
(1) dissolving a vitamin B6 crude product with HPLC purity of 98% in water, decoloring and filtering to obtain a raw material solution of vitamin B6 with the mass percentage concentration of 30%, wherein the temperature is 60 ℃.
(2) The heater 4 is started, raw material liquid of vitamin B6 is pumped from the raw material liquid inlet pipe 1 and is conveyed to the heater 4 through the second circulating pump 3, and the temperature of the raw material liquid is increased to 66 ℃. The heated raw material liquid was continuously fed into the evaporation vessel 6 at a rate of 300 kg/h. The diameter of the upper end of the channel 18 was 30 mm, the ratio of the diameter of the lower end of the channel 18 to the diameter of the upper end of the channel 18 was 2:1, and the open porosity of the channel was 20%.
(3) Controlling the vacuum degree of the evaporation container 6 to be 0.085MPa, leading the raw material liquid to reach a boiling state after entering the evaporation container 6, keeping the evaporation speed of water at 157kg/h, evaporating a large amount of solvent, and leading the concentrated solution to enter a crystallization container 8 through a draft tube 7. When the liquid level in the crystallization container 8 reaches the circulating material outlet pipe 12 and can realize circulating flow, the feeding speed of the raw material liquid is reduced to 157kg/h, the flow rate of the second circulating pump 3 is controlled at 1500kg/h, the flow rate of the first circulating pump 13 is controlled at 268kg/h, the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled at 0.2, and the stability is maintained for 3 hours.
(4) When the solid content of the conical settling zone at the bottom of the crystallization container 8 reaches 54 percent, a valve of a crystal slurry discharge port 15 at the bottom is opened, the crystal slurry in the crystallization container 8 enters a continuous centrifuge 16 at the flow rate of 143kg/h for filtration, a filter cake is washed by process water and then continuously discharged, and filtered mother liquor can be recycled to a raw material liquid inlet pipe 1 after concentration and decoloration treatment.
(5) After the crystal slurry in the crystallizer starts to be discharged, the feeding speed of the raw material liquid is adjusted to 300kg/h, the flow rate of the first circulating pump 13 is controlled to 240kg/h, and the ratio of the flow rate of the first stream to the flow rate of the second stream is controlled to 0.2.
(6) And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.96%, and the crystallization yield is 88.80% in terms of the feed amount, wherein the 40-mesh passing rate of the vitamin B6 crystal particles is 99%, the 60-mesh passing rate is 40%, and the 100-mesh passing rate is 0.3%, and the requirements of CP2015, EP8.0 and USP33 are met.
Example 8
On the basis of example 7, the diameter of the upper end of the channel 18 in the step (2) is 50 mm, the ratio of the diameter of the lower end of the channel 18 to the diameter of the upper end of the channel 18 is 1.5:1, and the opening rate of the channel is 20%; the other conditions were the same as in example 7. And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.94%, and the crystal yield is 88.40% in terms of the feed amount, and the 40-mesh passing rate, the 60-mesh passing rate and the 100-mesh passing rate of the vitamin B6 crystal particles are 99.5%, 50% and 5%.
Example 9
On the basis of example 7, the diameter of the upper end of the channel 18 in the step (2) is 5 mm, the ratio of the diameter of the lower end of the channel 18 to the diameter of the upper end of the channel 18 is 5:1, and the opening rate of the channel is 20%; the other conditions were the same as in example 7. And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.96%, and the crystal yield is 87.80% in terms of the feed amount, and the 40-mesh passing rate, the 60-mesh passing rate and the 100-mesh passing rate of the vitamin B6 crystal particles are 100%, 54% and 3%.
Example 10
On the basis of example 7, the diameter of the upper end of the channel 18 in the step (2) is 50 mm, the ratio of the diameter of the lower end of the channel 18 to the diameter of the upper end of the channel 18 is 1.5:1, and the opening rate of the channel is 40%; the other conditions were the same as in example 7. And drying the obtained filter cake to obtain white vitamin B6 crystal particles, wherein the HPLC purity is 99.89%, and the crystal yield is 88.00% in terms of the feed amount, and the 40-mesh passing rate, the 60-mesh passing rate and the 100-mesh passing rate of the vitamin B6 crystal particles are 99.5%, 49% and 8%.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A crystallization method of vitamin B6, which is characterized by comprising the following steps:
(1) providing an apparatus for evaporative crystallization, said apparatus for evaporative crystallization comprising:
the evaporation container is used for evaporating the solvent, a flow guide pipe is arranged at the bottom of the evaporation container, and an evaporation gas outlet is also arranged at the top of the evaporation container;
the crystallization container is used for crystallization, the crystallization container is positioned below the evaporation container, the flow guide pipe extends into the crystallization container and is communicated with the crystallization container, and a crystal slurry discharge port is arranged at the bottom of the crystallization container; wherein,
a circulating material outlet pipe is connected to the side wall of the crystallization container and is branched into a first branch pipe and a second branch pipe;
the device for evaporative crystallization further comprises a first circulating unit and a second circulating unit, wherein the first circulating unit comprises a first circulating pump, a first circulating inlet pipe and a first branch pipe, and the first branch pipe is connected with the first circulating pump; the first circulation inlet pipe is provided with a first end and a second end, the first end of the first circulation inlet pipe is connected with the first circulation pump, and the second end of the first circulation inlet pipe is connected with the evaporation container;
the second circulation unit comprises a second circulation pump, a heater, a second circulation inlet pipe and a second branch pipe, the second branch pipe is sequentially connected with the second circulation pump and the heater, the second circulation inlet pipe is provided with a third end and a fourth end, the third end of the second circulation inlet pipe is connected with the heater, and the fourth end of the second circulation inlet pipe is connected with the evaporation container;
the device for evaporative crystallization further comprises a raw material liquid inlet pipe, wherein the raw material liquid inlet pipe is connected to the second branch pipe and is used for pumping the raw material liquid to the heater through a second circulating pump;
(2) continuously injecting a raw material liquid into the raw material liquid inlet pipe, wherein the mass fraction of vitamin B6 in the raw material liquid is 10-50%, and the temperature of the raw material liquid is 20-80 ℃;
(3) and (3) evaporation: the raw material liquid enters the evaporation container through a second branch pipe, a second circulating pump, a heater and a second circulating inlet pipe, the vacuum degree of the evaporation container is controlled to be 0.08-0.097 MPa, and a solvent in the raw material liquid is evaporated to obtain an evaporation treatment liquid;
(4) and (3) crystallization: the evaporation treatment liquid enters a crystallization container through the flow guide pipe, and crystallization is carried out in the crystallization container to obtain crystallization particles and mother liquid, wherein the crystallization particles comprise first particles with larger particle size and fine crystal particles with smaller particle size;
(5) shunting: when the overall height of the crystallization particles and the mother liquor reaches or exceeds the circulating material outlet pipe, the fine crystal particles and the mother liquor enter the circulating material outlet pipe and are branched, wherein the mother liquor is branched into a first mother liquor and a second mother liquor, the fine crystal particles are branched into a first fine crystal and a second fine crystal, the first fine crystal and the first mother liquor flow into a first branch pipe, the second fine crystal and the second mother liquor flow into a second branch pipe, and the first particles are settled at the bottom of a crystallization container;
(6) the second fine crystals and the second mother liquor flowing into the second branch pipe continue to carry out crystallization in the next period, namely evaporation in the step (3), crystallization in the step (4) and flow division in the step (5);
(7) the first fine crystals and the first mother liquor flowing into the first branch pipe enter the evaporation container through the first circulating pump and the first circulating inlet pipe, and the next period of crystallization, namely the evaporation in the step (3), the crystallization in the step (4) and the diversion in the step (5) are carried out continuously, wherein the first fine crystals are used as crystal nuclei for inducing to obtain second particles with larger particle sizes and are settled to the bottom of the crystallization container;
(8) and (3) discharging the crystal mush containing the first particles and the second particles from a crystal mush discharge port to obtain a finished product of vitamin B6.
2. The crystallization method of vitamin B6, according to claim 1, wherein a rectifying classifier is further provided in the crystallization vessel, the rectifying classifier comprises a plurality of channels, and the ratio of the size of the lower end of each channel to the size of the upper end of each channel is 1.1: 1-10: 1.
3. The crystallization method of vitamin B6, according to claim 2, wherein the size of the upper end of the channel is 3 mm to 100 mm.
4. The crystallization method of vitamin B6, according to claim 2, wherein the open porosity of the channels is 5% to 50%.
5. The process for the crystallization of vitamin B6, according to claim 1, wherein the evaporation vessel has a defoaming and defoaming device inside near the evaporation gas outlet.
6. The crystallization method of vitamin B6, wherein the side wall of the evaporation container and the side wall of the crystallization container are further provided with an equalizing pipe, and the equalizing pipe is communicated with the evaporation container and the crystallization container.
7. The process for crystallizing vitamin B6, according to claim 1, wherein the ratio of the evaporation rate of the solvent in the raw material liquid to the feed rate of the raw material liquid in step (2) is 0.1 to 0.9,
the ratio of the discharging speed of the crystal slurry in the step (8) to the feeding speed of the raw material liquid in the step (2) is 0.1-0.9.
8. The process for the crystallization of vitamin B6, according to claim 1, wherein during the diversion in step (5), a rectification classifier is further provided in the crystallization vessel, and when the total height of the crystallized particles and the mother liquor reaches or exceeds the position where the recycle stream pipe is connected to the crystallization vessel, the fine-grained particles and the mother liquor are introduced into the recycle stream pipe through the rectification classifier.
9. The process for the crystallization of vitamin B6, according to claim 1, wherein the temperature of the raw material liquid or the second mother liquid flowing into the second branch pipe is increased to 30 to 90 ℃ after passing through the heater during the evaporation in step (3).
10. The crystallization method of vitamin B6, according to claim 1, wherein the first fine crystals and the first mother liquor flowing into the first branch pipe in the step (5) are defined as a first stream, the second fine crystals and the second mother liquor flowing into the second branch pipe are defined as a second stream, and the ratio of the flow rate of the first stream to the flow rate of the second stream is 1: 100-10: 1.
11. The process for the crystallization of vitamin B6, according to claim 1, wherein after step (8), the slurry containing the first and second granules is discharged through a slurry outlet, centrifuged to obtain a cake and a mother liquor, and the centrifuged mother liquor is recovered and recycled to the raw liquor inlet pipe.
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