CN102188836A - Multi-phase crystallization method - Google Patents
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- CN102188836A CN102188836A CN2010101163667A CN201010116366A CN102188836A CN 102188836 A CN102188836 A CN 102188836A CN 2010101163667 A CN2010101163667 A CN 2010101163667A CN 201010116366 A CN201010116366 A CN 201010116366A CN 102188836 A CN102188836 A CN 102188836A
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Abstract
The invention relates to a multi-phase crystallization method which is mainly used for solving the problems that in the prior art, crystallizer scares are serious and the production capability is low. In order to solve the problems in the prior art, the technical scheme adopted by the invention is as follows: the method comprises the following steps: performing crystallization on raw materials and a diluent in a crystallizer; separating crystal mush to obtain crystal and a mixture of the a thinner and crystallizing mother liquid; washing the crystal, and feeding the washed crystal into a product jar; separating the mixture of the thinner and the crystallizing mother liquid so as to obtain the crystallizing mother liquid and the thinner, feeding the crystallizing mother liquid into a mother liquid jar, and returning the thinner to a thinner storage jar, wherein the thinner is not subjected to separation by crystallization; and the weight ratio of the thinner and raw material in the crystallizer is (0.1-50):1, and the solubility of the thinner in the raw material is less than 1 g thinner/100 g raw material. The method can be applied to industrial crystallization production.
Description
Technical field
The present invention relates to a kind of method of heterogeneous crystallization.
Background technology
The crystallisation by cooling method is a kind of method for crystallising of industrial extensive employing indirectly, compare with direct crystallisation by cooling method, salting out method, reaction-crystallization method, it need not add other material in crystalline mother solution, compare with evaporation concentration method, vacuum cooled crystallisation, and its energy consumption is lower.But indirectly the weak point of crystallisation by cooling method is that the heat transfer efficiency of indirect cooling procedure is lower, and cooling surface forms brilliant scar easily, and in a single day heat-transfer area scabs heat-transfer effect is further sharply worsened, and makes the production can be normally to carry out when serious.Reduce heat-transfer effect in order to prevent crystal from the crystallizer wall, scabbing, scraper need be installed in crystallizer, because of scraper and crystallizer wall still have certain interval, thereby can not eliminate the phenomenon that scabs fully, even a very thin layer crystal scar also can make the heat-transfer effect of crystallizer be greatly affected.Scraper in the crystallizer is generally strip, the vibration that when high speed is rotated, produces, scraper moves under low speed usually, but slow-revving scraper can not make the solid-liquid two-phase in the crystallizer evenly mix effectively, the crystal that generates easily deposits to the bottom or the bottom of crystallizer, both be unfavorable for the further growth of crystal, also be unfavorable for the smooth delivery of power of magma.Therefore, the outer circulation pump of a big flow to be set usually with the mixing in the promotion crystallizer and the suspension of crystal.In addition, thereby also easy crystal is smashed of scraper is unfavorable for follow-up Separation of Solid and Liquid process, and then influences the purity of crystal product.In order to ensure the stable rotation of scraper, the solid content in the crystallizer generally need maintain lower level, and this realizes by the circulation of a large amount of mother liquors that generally this operator scheme is the energy consumption height not only, and has reduced the production capacity of crystallizer.
Patent US4141924 and patent US3758601 all disclose a kind of method of three-phase crystallization, by adding a kind of diluent, make magma form liquid-liquid-solid three-phase with different densities, wherein diluent density is between crystalline mother solution and crystal, crystal and crystalline mother solution are separated, thereby the crystalline mother solution that reduces plane of crystal adheres to the purity of raising product crystal.The purpose of using diluent in the above-mentioned patent all is to utilize diluent to separate crystal and crystalline mother solution improving product crystal purity, thereby requires the density of diluent must be between crystal and crystalline mother solution.Patent US3758601 also points out, forms the liquid-liquid-solid three-phase for quick, and makes full use of the separation effect of diluent, also needs to utilize the centrifuge of specific pattern to carry out Separation of Solid and Liquid.Though diluent can be separated crystal and crystalline mother solution and improve product crystal purity, but can not eliminate the crystalline mother solution that plane of crystal adheres to fully, in order further to improve crystal purity, also should wash, and above-mentioned patent does not all adopt washing process crystal.
Summary of the invention
Technical problem to be solved by this invention is the problem that crystallizer scabs seriously, production capacity is low that exists in the existing method for crystallising, and a kind of method of heterogeneous crystallization is provided.This method has the crystallizer wall and does not have and scab the advantage that production capacity is high.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is as follows: a kind of method of heterogeneous crystallization, may further comprise the steps: raw material and diluent carry out crystallization in crystallizer, and magma obtains the mixture of crystal and diluent and crystalline mother solution after separating; Crystal enters the product jar after washing; Diluent obtains crystalline mother solution and diluent with the mixture of crystalline mother solution through separating, and crystalline mother solution enters mother liquor tank, and diluent returns the diluent storage tank; Wherein, diluent can not separated out in crystallization during crystallization, and the diluent in the crystallizer is 0.1～50: 1 with the ratio of the weight of raw material, and the solubility of diluent in raw material is less than 1g diluent/100g raw material.
In the technique scheme, the diluent preferred version is selected from water, ammoniacal liquor, the NaCl aqueous solution, CaCl
2The aqueous solution, (NH4)
2SO
4The aqueous solution, (NH4)
3PO
4At least a in the aqueous solution, methyl alcohol, ethanol or the ethylene glycol, raw material preferred version are selected from least a in mixed xylenes, mixed dichlorobenzene, naphthalene, terephthalic acid (TPA) or the bisphenol-A; Crystal enters the product jar after diluent or solvent or pure product fused solution washing; Crystallization temperature is-100～100 ℃, and crystallization pressure is-0.1MPa～30MPa.
In the technique scheme, raw material mixes post crystallization with diluent in crystallizer, forms the liquid-liquid-solid three-phase with different densities in crystallizer, and the existence of this third phase of diluent can prevent crystal scabbing at the crystallizer wall effectively.Diluent is different with the ratio of raw material, and the crystallization initial stage can form different liquid liquid two-phase mixed systems.When diluent is continuous phase, the crystallization raw material that forms under stirring action is dispersed in the diluent with the form of drop, because diluent can crystallization under the crystallization temperature of raw material, therefore between the heat-transfer area of crystallizer and crystallization raw material, formed a kind of isolation effect, thereby the crystal of having avoided material crystal to form is attached on the heat-transfer area the brilliant scar of formation and influences heat transfer.In addition, disperse the droplet quantity of formation can reach 10
8～10
9The order of magnitude, so interfacial area is very big, this has just further strengthened heat-transfer effect.When diluent is decentralized photo, and the density of diluent is during greater than the density of raw material, the centrifugal force that the centrifugal force that the diluent of equal in quality obtains under stirring action obtains greater than raw material, therefore the drop of diluent can be shifted to the heat-transfer area of crystallizer quickly, thereby realizes preventing scabbing of heat-transfer area.The adding of diluent can be avoided using scraper in the structure of mould design, and the crystallizer behind the cancellation scraper can be provided with guide shell and baffle plate, thereby improves the solid-liquid mixed effect in the crystallizer.And, since crystal can attached work on the heat-transfer area of crystallizer, so the inner member in the crystallizer can be designed to new heat-transfer area, thereby increases the total heat conduction area of whole crystallizer, obtains the higher crystallizer production intensity of unit.In order to improve the production capacity of crystallizer, can reduce crystallization temperature more crystal structure is separated out, the existence of diluent can make the solid content in the crystallizer still maintain reduced levels, thereby has avoided the circulation of a large amount of mother liquors, reduced energy consumption, and be convenient to magma in ducted conveying.Because adding the purpose of diluent is that the wall that prevents crystallizer scabs, therefore not the density of special requirement diluent between crystal and crystalline mother solution, therefore diluent can have more selection, in addition, can also use common solid-liquid separating equipment to separate magma, not need to make three-phase layering.Can also make diluent have different density by the composition of regulating diluent, when diluent density during greater than the density of crystal, pipeline can prevent that crystal is in ducted deposition when carrying magma.When diluent density is between crystalline mother solution and crystalline density, then can make three-phase layering, isolate the crystalline mother solution and the part diluent on upper strata earlier, separate remaining diluent and crystal again, and then use the diluent washing crystal, both utilized the barriering effect of diluent, the clean result of having utilized diluent again is to improve the purity of product crystal.Because diluent can customize according to concrete application or be composite, so the vaporization component vaporization of the heat that crystallization process produces in can diluted dose taken away, thereby temperature in the maintenance crystallizer everywhere is even, helps forming the crystal of even particle size distribution and coarsegrain.Diluent after magma separates can separate by the layering of liquid liquid with crystalline mother solution, and in the fusion-crystallization process, diluent can melt the back with crystal to be separated by the layering of liquid liquid.Utilize the diluent washing crystal, then do not need to use extra solvent or pure product fused solution to come washing crystal, particularly in the fusion-crystallization process, the higher liquid form product of serviceability temperature stops up because of recrystallization causes filtration channel when washing crystal easily, uses diluent then this situation can not occur as cleaning solution.
Heterogeneous method for crystallising of the present invention carries out Crystallization Separation to the paraxylene in the mixed xylenes, and crystallizer production capacity is improved, and is about 11.1%, and the crystallizer wall all do not have the phenomenon of scabbing, and has obtained better technical effect.
Description of drawings
Fig. 1 is the schematic flow sheet of existing method for crystallising.
Fig. 2 is the schematic flow sheet of a kind of heterogeneous method for crystallising of the present invention.
Among Fig. 1,1-head tank, 2-raw material, 3-crystallizer, 4-magma, 5-solid-liquid separator, 6-crystal, 7-product jar, 8-crystalline mother solution, 9-mother liquor tank, 10-washing agent.
As described in Figure 1, carry out crystallization from the raw material 2 of head tank 1 in crystallizer 3, magma 4 obtains crystal 6 and crystalline mother solution 8 after solid-liquid separator 5 separates; Crystal 6 enters product jar 7 after washing agent 10 washings; Crystalline mother solution 8 enters mother liquor tank 9.
Among Fig. 2,1-head tank, 2-raw material, 3-crystallizer, 4-magma, 5-solid-liquid separator, the 6-crystal, 7-product jar, 8-diluent and crystalline mother solution mixture, 9-liquid liquid/gas separator, 10-crystalline mother solution, the 11-mother liquor tank, 12-diluent, 13-diluent tank, 14-diluent, 15-washing agent.
As described in Figure 2, carry out crystallization from the raw material 2 of head tank 1 and diluent 14 from diluent storage tank 13 in crystallizer 3, magma 4 obtains the mixture 8 of crystal 6 and diluent and crystalline mother solution after solid-liquid separator 5 separates; Crystal 6 enters product jar 7 after washing agent 15 washings; Diluent separates through liquid liquid/gas separator 9 with the mixture 8 of crystalline mother solution and obtains crystalline mother solution 10 and diluent 12, and crystalline mother solution 10 enters mother liquor tank 11, and diluent 12 returns diluent storage tank 13.
The present invention is further elaborated below by embodiment.
The specific embodiment
[comparative example 1]
Existing method by the mixed xylenes separating paraxylene
As described in Figure 1, mixed xylenes raw material 2 from head tank 1 carries out crystallization in crystallizer 3, wherein the paraxylene concentration in the mixed xylenes raw material is 81% (quality), the concentration of meta-xylene is 19% (quality), the crystallizer crystallization temperature is-15 ℃, and magma 4 obtains crystal 6 and crystalline mother solution 8 after solid-liquid separator 5 separates; Crystal 6 enters product jar 7 after washing agent 10 washings, washing agent is pure paraxylene fused solution; Crystalline mother solution 8 enters mother liquor tank 9.
[embodiment 1]
Method by the mixed xylenes separating paraxylene of the present invention
As described in Figure 2, in crystallizer 3, carry out crystallization from the mixed xylenes raw material 2 of head tank 1 and diluent 14 from diluent storage tank 13, wherein the paraxylene concentration in the mixed xylenes raw material is 81% (quality), the concentration of meta-xylene is 19% (quality), diluent 14 is 0.2: 1 with the ratio of the quality of mixed xylenes raw material 2, diluent is an ammoniacal liquor, the crystallizer crystallization temperature is-15 ℃, and magma 4 obtains the mixture 8 of crystal 6 and diluent and crystalline mother solution after solid-liquid separator 5 separates; Crystal 6 enters product jar 7 after diluent 15 washings, washing agent is an ammoniacal liquor; Diluent separates through separator 9 with the mixture 8 of crystalline mother solution and obtains crystalline mother solution 10 and diluent 12, and crystalline mother solution 10 enters mother liquor tank 11, and diluent 12 returns diluent storage tank 13.
[embodiment 2]
Method by the mixed xylenes separating paraxylene of the present invention
As described in Figure 2, in crystallizer 3, carry out crystallization from the mixed xylenes raw material 2 of head tank 1 and diluent 14 from diluent storage tank 13, wherein the paraxylene concentration in the mixed xylenes raw material is 81% (quality), the concentration of meta-xylene is 19% (quality), diluent 14 is 0.5: 1 with the ratio of the quality of mixed xylenes raw material 2, diluent is an ammoniacal liquor, the crystallizer crystallization temperature is-25 ℃, and magma 4 obtains the mixture 8 of crystal 6 and diluent and crystalline mother solution after solid-liquid separator 5 separates; Crystal 6 enters product jar 7 after diluent 15 washings, washing agent is an ammoniacal liquor; Diluent separates through separator 9 with the mixture 8 of crystalline mother solution and obtains crystalline mother solution 10 and diluent 12, and crystalline mother solution 10 enters mother liquor tank 11, and diluent 12 returns diluent storage tank 13.
[embodiment 3]
Method by the mixed xylenes separating paraxylene of the present invention
As described in Figure 2, in crystallizer 3, carry out crystallization from the mixed xylenes raw material 2 of head tank 1 and diluent 14 from diluent storage tank 13, wherein the paraxylene concentration in the mixed xylenes raw material is 81% (quality), the concentration of meta-xylene is 19% (quality), diluent 14 is 0.5: 1 with the ratio of the quality of mixed xylenes raw material 2, diluent is a methyl alcohol, the crystallizer crystallization temperature is-25 ℃, and magma 4 obtains the mixture 8 of crystal 6 and diluent and crystalline mother solution after solid-liquid separator 5 separates; Crystal 6 enters product jar 7 after diluent 15 washings, washing agent is a methyl alcohol; Diluent separates through separator 9 with the mixture 8 of crystalline mother solution and obtains crystalline mother solution 10 and diluent 12, and crystalline mother solution 10 enters mother liquor tank 11, and diluent 12 returns diluent storage tank 13.
The experimental result of embodiment and comparative example is as shown in the table.
By embodiment as can be seen, adopt the method for a kind of heterogeneous crystallization of the present invention can effectively solve the problem that the crystallizer wall scabs, and crystallization process can more carry out under the low temperature, thereby can allow more crystal separate out, the rate of recovery is increased, promptly improve the production capacity of crystallizer, improved 11.1% approximately.
Claims (4)
1. the method for a heterogeneous crystallization may further comprise the steps:
Raw material and diluent carry out crystallization in crystallizer, magma obtains the mixture of crystal and diluent and crystalline mother solution after separating; Crystal enters the product jar after washing; Diluent obtains crystalline mother solution and diluent with the mixture of crystalline mother solution through separating, and crystalline mother solution enters mother liquor tank, and diluent returns the diluent storage tank; Wherein, diluent can not separated out in crystallization during crystallization, and the diluent in the crystallizer is 0.1～50: 1 with the ratio of the weight of raw material, and the solubility of diluent in raw material is less than 1g diluent/100g raw material.
2. the method for heterogeneous crystallization according to claim 1 is characterized in that diluent is selected from water, ammoniacal liquor, the NaCl aqueous solution, CaCl
2The aqueous solution, (NH4)
2SO
4The aqueous solution, (NH4)
3PO
4At least a in the aqueous solution, methyl alcohol, ethanol or the ethylene glycol, raw material are selected from least a in mixed xylenes, mixed dichlorobenzene, naphthalene, terephthalic acid (TPA) or the bisphenol-A.
3. the method for heterogeneous crystallization according to claim 1 is characterized in that crystal enters the product jar after diluent or solvent or pure product fused solution washing.
4. the method for heterogeneous crystallization according to claim 1 is characterized in that crystallization temperature is-100～100 ℃, and crystallization pressure is-0.1MPa～30MPa.
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| CN2010101163667A CN102188836A (en) | 2010-03-03 | 2010-03-03 | Multi-phase crystallization method |
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| CN2010101163667A CN102188836A (en) | 2010-03-03 | 2010-03-03 | Multi-phase crystallization method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103664491A (en) * | 2012-09-05 | 2014-03-26 | 中国石油化工股份有限公司 | Production method of p-xylene |
| CN108992965A (en) * | 2018-08-17 | 2018-12-14 | 张家港清澄纳米科技有限公司 | A kind of uniform one is hydrated sodium hypophosphite bulky grain Continuous Cooling Crystallization preparation process and device |
| CN113680095A (en) * | 2020-05-18 | 2021-11-23 | 济南新材料产业技术研究院 | Cooling crystallization device and cooling crystallization method by using non-solvent liquid medium |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3643453A (en) * | 1968-12-26 | 1972-02-22 | Shell Oil Co | Selective crystallization of paraxylene in a water-alkanol mixture |
| US3758601A (en) * | 1971-11-17 | 1973-09-11 | R Wylie | Three-phase organics separation process |
| US4141924A (en) * | 1969-01-27 | 1979-02-27 | The Dow Chemical Company | Three phase crystallization |
| CN101391967A (en) * | 2008-10-14 | 2009-03-25 | 清华大学 | Method for producing acrylic amide crystal |
-
2010
- 2010-03-03 CN CN2010101163667A patent/CN102188836A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3643453A (en) * | 1968-12-26 | 1972-02-22 | Shell Oil Co | Selective crystallization of paraxylene in a water-alkanol mixture |
| US4141924A (en) * | 1969-01-27 | 1979-02-27 | The Dow Chemical Company | Three phase crystallization |
| US3758601A (en) * | 1971-11-17 | 1973-09-11 | R Wylie | Three-phase organics separation process |
| CN101391967A (en) * | 2008-10-14 | 2009-03-25 | 清华大学 | Method for producing acrylic amide crystal |
Non-Patent Citations (1)
| Title |
|---|
| 陈亮 等: "对二甲苯结晶过程的固液相平衡研究", 《聚酯工业》, vol. 22, no. 1, 31 January 2009 (2009-01-31) * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103664491A (en) * | 2012-09-05 | 2014-03-26 | 中国石油化工股份有限公司 | Production method of p-xylene |
| CN103664491B (en) * | 2012-09-05 | 2015-07-08 | 中国石油化工股份有限公司 | Production method of p-xylene |
| CN108992965A (en) * | 2018-08-17 | 2018-12-14 | 张家港清澄纳米科技有限公司 | A kind of uniform one is hydrated sodium hypophosphite bulky grain Continuous Cooling Crystallization preparation process and device |
| CN108992965B (en) * | 2018-08-17 | 2021-07-27 | 张家港清澄纳米科技有限公司 | Continuous cooling crystallization preparation process and device for large particles of uniform sodium hypophosphite monohydrate |
| CN113680095A (en) * | 2020-05-18 | 2021-11-23 | 济南新材料产业技术研究院 | Cooling crystallization device and cooling crystallization method by using non-solvent liquid medium |
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Application publication date: 20110921 |