CN100528861C - Process for freezing and crystallizing triformol continuouslly by sleeved crystallizer - Google Patents
Process for freezing and crystallizing triformol continuouslly by sleeved crystallizer Download PDFInfo
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- CN100528861C CN100528861C CNB200710048792XA CN200710048792A CN100528861C CN 100528861 C CN100528861 C CN 100528861C CN B200710048792X A CNB200710048792X A CN B200710048792XA CN 200710048792 A CN200710048792 A CN 200710048792A CN 100528861 C CN100528861 C CN 100528861C
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Abstract
A process for freezing and crystallizing triformol continuously by double-pipe crystallizing device is carried out by entering fresh triformol from pre-system into circulating pump I, mixing suspensoid with circulating loop with after-crystallizing device and connecting pipeline, delivering partial triformol suspensoid in after-crystallizing device to centrifuge, by conveying pump, separating triformol crystal from mother liquid, returning partial mother liquid to after-crystallizing device, returning partial mother liquid to pre-system, transferring partial triformol suspensoid in after-crystallizing device to double-pipe crystallizing-device by circulating pump II, heat exchanging with frozen water to form triformol crystal nucleus, and returning triformol suspensoid to after-crystallizing device. It has less methanal content and consumption of electricity and frozen water and better heat-exchange ability.
Description
Technical field
The invention belongs to the trioxymethylene preparation field, particularly the process for freezing and crystallizing of trioxymethylene.
Background technology
Trioxymethylene is a kind of important monomer that polyoxymethylene is produced, and for the polymerization of polyoxymethylene, the content of impurities in the monomer whose must not surpass 100PPM.Therefore, trioxymethylene need be refined to polymerization-grade purity.Process for refining about trioxymethylene mainly comprises: extraction, crystallization, variable-pressure rectification, critical extraction and membrane sepn, wherein, extracting and separating and Crystallization Separation are used more extensive.
It is reported, the continuous process for freezing and crystallizing of trioxymethylene that China introduces from Poland as shown in Figure 1, fresh trioxymethylene solution from preceding system enters recycle pump I1, the circulation loop that post crystallization device 4 and connecting pipeline are formed mixes with trioxymethylene suspension, a part of trioxymethylene suspension in the post crystallization device 4 is delivered to whizzer by transferpump 3 and is carried out separating of trioxymethylene crystal and mother liquor, part mother liquor returns post crystallization device 4, make the concentration of trioxymethylene suspension satisfy mobile requirement, another part mother liquor returns preceding system, a part of trioxymethylene suspension in the post crystallization device 4 by recycle pump II2 be delivered to tank crystallizer 6 and 7 and refrigerated water carry out heat exchange, form the trioxymethylene nucleus, the trioxymethylene suspension after the heat exchange returns post crystallization device 4 after entering trioxymethylene suspension collector 5 again.Tank crystallizer in the above-mentioned technology is provided with two in a crystallization production line.This kind technology is owing to adopt tank crystallizer as preceding crystallizer, and mainly have following shortcoming: 1, heat exchange effect is bad, and the chilled water system temperature difference is very low, needs to increase the quantity of circulating water of chilled water system, brings systemic resistance to raise simultaneously, and power consumption increases.2, crystallizer cleans frequently, will clean once in per two to three days in service.Frequent cleaning not only can increase power consumption, refrigerated water consumption and manpower consumption, and can cause system's operation fluctuation and unfavorable to environment.3, the crystallizer volume is bigger, and trioxymethylene suspension internal circulating load is less relatively, in crystallizer the residence time longer, at the driving initial stage, when heat exchanger surface is clean, can cause in the crystallizer trioxymethylene suspension condensate depression higher, generate a large amount of thin brilliant.A large amount of thin brilliant existence can be gathered into piece in trioxymethylene suspension, cause line clogging, even can make the total system paralysis; The crystal of equal in quality, thin crystalline substance is many more, and the crystalline specific surface area can increase a lot, because its adsorption in centrifugal separation processes, can cause impurity such as formaldehyde and water to increase in the adsorptive capacity of plane of crystal, thereby increase the back separating difficulty; Thin brilliant content is many, also can make the centrifugal separation system operation bad.
Summary of the invention
The objective of the invention is to overcome the deficiencies in the prior art, a kind of continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer is provided, to improve the output and the quality of trioxymethylene, reduce power consumption, refrigerated water consumption, guarantee the normal operation of freezing and crystallizing system.
Technical scheme of the present invention: preceding crystallizer is carried out preferably, replace the tank crystallizer that uses in the existing continuous process for freezing and crystallizing of trioxymethylene with extension type crystallizer.
The continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer of the present invention, its technical process is: the fresh trioxymethylene solution from preceding system enters recycle pump I, the circulation loop that post crystallization device and connecting pipeline are formed mixes with trioxymethylene suspension, a part of trioxymethylene suspension in the post crystallization device is delivered to whizzer by transferpump and is carried out separating of trioxymethylene crystal and mother liquor, part mother liquor returns the post crystallization device, make the concentration of trioxymethylene suspension meet mobile requirement, another part mother liquor returns preceding system, a part of trioxymethylene suspension in the post crystallization device is delivered to extension type crystallizer by recycle pump II and refrigerated water carries out heat exchange, form the trioxymethylene nucleus, trioxymethylene suspension after the heat exchange returns the post crystallization device, its contained trioxymethylene nucleus is grown in the post crystallization device, reaches the granularity of processing requirement.System can be arranged in parallel many crystallization production lines, can satisfy the production needs but every crystallization production line is provided with an extension type crystallizer.
The employed post crystallization device of above-mentioned technology is conventional crystallizer, mainly is made of with the agitator that is arranged in the container trough-shaped container or pot container, both can buy from market, but also consigned processing.The employed extension type crystallizer of above-mentioned technology mainly is made up of thimble assembly, the transmission rig and the motor that are connected with rotating shaft in the thimble assembly, and the quantity of thimble assembly is determined according to the throughput of system.
In order to realize goal of the invention better, the present invention has also taked following technical measures:
When 1, trioxymethylene suspension and refrigerated water carry out heat exchange, on flow path designs, make the flow direction contrary of refrigerated water and trioxymethylene suspension.
2, according to the structure of extension type crystallizer, trioxymethylene suspension both can enter from the bottom of extension type crystallizer, top output, can enter from the top of extension type crystallizer again, bottom output, the present invention selected trioxymethylene suspension by the bottom of extension type crystallizer enter, from the flow path designs of the top output of extension type crystallizer.
3, optimized processing parameter, the overall heat transfer coefficient of extension type crystallizer is 300W/m
2.K～400W/m
2.K, when trioxymethylene suspension and refrigerated water carried out heat exchange, the residence time of trioxymethylene suspension in extension type crystallizer was controlled at 1～6 minute, and the chilled water flow speed control is built in 0.1～1m/s, and the inflow temperature of refrigerated water is-10～-13 ℃.
The present invention has following beneficial effect:
1, owing to adopted extension type crystallizer as preceding crystallizer, exchange capability of heat increases substantially, and the exchange capability of heat of an extension type crystallizer has reached 1.8 times of two platform trough formula crystallizers that existing technology uses,
2, the ability of having used the device that the throughput of the continuous freezing and crystallizing device of trioxymethylene of extension type crystallizer uses than existing technology has increased by 10% (moving 7200 hours meters working time per year).
3, be example to produce 10000 tons of polyoxymethylene devices per year, adopt extension type crystallizer, a power of motor is 7.5kwh, and adopt existing tank crystallizer (introducing) from Poland, the power of motor of one platform trough formula crystallizer is 5.5kwh, therefore, and with regard to a crystallization production line, the operation power consumption that per hour can save is the power consumption of 5.5 * 2 * 1.8-7.5=12.3kwh, can save the nearly 8.856 ten thousand degree electricity (to be working time in year 7200 hours) of power consumption in 1 year.
4, the extension type crystallizer specific surface area is big, compares with existing tank crystallizer (introducing from Poland), under identical heat interchanging area, volume is littler, trioxymethylene suspension flow velocity uprises, and has reduced the condensate depression of trioxymethylene suspension in crystallizer, can effectively prevent a large amount of thin brilliant generations.
5, extension type crystallizer moves by the mode of low flow, high temperature difference, can save the watt consumption that refrigerated water is carried, and in addition, because the freezing water yield reduces, flow velocity reduces, and can promote the efficient of freezing unit.
6, extension type crystallizer just cleans once weekly, and the tank crystallizer Clean after every that uses than existing technology has increased by one times nearly, and the amount of bringing into and the water that has reduced the cleaning heat consumes, the manpower consumption, helps the stable of crystal system and chilled water system.
7, the analysis after the filter cake fusion, the product trioxymethylene content that technology of the present invention obtains improves, and formaldehyde content is compared with existing technology, has reduced approximately half.
8, because trioxymethylene suspension is low in and high out in extension type crystallizer, by the pump discharge pressure forced-flow, whole internal surface of crystallizer all is full of trioxymethylene suspension, the flow process of trioxymethylene suspension in crystallizer inside is exactly one and mixes homogenization process, help the renewal of heat exchanger surface trioxymethylene suspension, it is more even to conduct heat.
9, with respect to existing technology, article one, the crystallization production line has reduced the preceding crystallizer of a platform, and can remove trioxymethylene suspension collector, not only can reduce the investment of equipment, and flow process shortens greatly, and corresponding pipeline shortens, and the line clogging probability reduces, equipment is installed the absolute altitude reduction simultaneously, reduces the transferpump power consumption.
Description of drawings
Fig. 1 is the process flow sheet of China from the continuous process for freezing and crystallizing of trioxymethylene of Poland's introduction;
Fig. 2 is the process flow sheet of the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer of the present invention;
Fig. 3 is the structure diagram of extension type crystallizer;
Fig. 4 is the transmission rig synoptic diagram of extension type crystallizer;
Fig. 5 is the structure diagram of the thimble assembly in the extension type crystallizer.
Among the figure, pipe connected pipe, 12-chuck pipe connecting, 13-link span, 14-thimble assembly, 15-chain, 16-driven sprocket, 17-rotating shaft, 18-tightening pulley, 19-scraper component, 20-chuck in 1-recycle pump I, 2-recycle pump II, 3-transferpump, 4-post crystallization device, 5-trioxymethylene suspension collector, 6-tank crystallizer I, 7-tank crystallizer II, 8-extension type crystallizer, 9-motor, 10-transmission rig, the 11-.
Embodiment
Below in conjunction with accompanying drawing, further specify the concrete structure of the extension type crystallizer of technology of the present invention and this technology use.Following embodiment is to produce the foundation of 10000 tons of polyoxymethylene devices as equipment and processing parameter selection per year.
The technical process of present embodiment is as shown in Figure 1: enter the circulation loop that recycle pump I1, post crystallization device 4 and connecting tube form from the fresh trioxymethylene solution of preceding system and mix with trioxymethylene suspension; A part of trioxymethylene suspension in the post crystallization device 4 is delivered to extension type crystallizer 8 by ring pump II2 and carries out heat exchange with refrigerated water, form the trioxymethylene nucleus, trioxymethylene suspension after the heat exchange returns post crystallization device 4, trioxymethylene suspension is entered, is exported from the top of extension type crystallizer by the bottom of extension type crystallizer, refrigerated water is entered, is exported from the bottom of extension type crystallizer by the top of extension type crystallizer, when carrying out heat exchange, the flow direction contrary of refrigerated water and trioxymethylene suspension; A part of trioxymethylene suspension in the post crystallization device 4 is delivered to whizzer by transferpump 3 and is carried out separating of trioxymethylene crystal and mother liquor, part mother liquor returns post crystallization device 4, make the concentration of trioxymethylene suspension satisfy mobile requirement, another part mother liquor returns preceding system.During operation, the add-on of fresh trioxymethylene solution and mother liquor and the amount phase equilibrium of delivering to the trioxymethylene suspension of whizzer by transferpump 3.
As shown in Figure 1, the corollary apparatus of above-mentioned technology comprises extension type crystallizer 8, post crystallization device 4, recycle pump I1, ring pump II2 and transferpump 3, extension type crystallizer 8 horizontal installations.
Recycle pump I1, ring pump II2 select impeller pump for use, and transferpump 3 is selected spiral pump for use, is the commercial goods.
The post crystallization device mainly is made of pot container and the agitator that is arranged in the container, both can buy from market, but also consigned processing.
The structure of extension type crystallizer comprises motor 9, transmission rig 10, eight groups of thimble assemblies 14 as shown in Figure 3, Figure 4.Transmission rig 10 is a sprocket wheel chain transmission pair, as shown in Figure 4, mainly by the drive sprocket that is connected with the motor power output shaft, be installed in driven sprocket 16 in each thimble assembly rotating shaft 17 and tightening pulley 18 and chain 15 and form.The structure of thimble assembly as shown in Figure 5, comprise outer tube, be sleeved on interior pipe in the outer tube, be arranged in pipe rotating shaft 17, be installed in the scraper component 19 in the rotating shaft; The space that outer tube wall and outer wall of inner tube surround is a chuck 20, is the path of refrigerated water, and the endoporus of interior pipe is the path of trioxymethylene suspension; The chuck of each thimble assembly is communicated with by chuck pipe connecting 12, and the interior pipe of each thimble assembly is communicated with by interior pipe connected pipe 11, forms series-mode frame, and link span 13 is used for supporting sleeve, forms skeleton construction, as shown in Figure 3.The overall heat transfer coefficient of extension type crystallizer is 300W/m
2.K, the residence time of trioxymethylene suspension in extension type crystallizer 8 was controlled at 2～4 minutes, and flow is 40～50m
3/ h, the temperature of turnover extension type crystallizer is respectively 10 ℃, 7 ℃, and the chilled water flow speed control is built in 0.2～0.5m/s, and the inflow temperature of refrigerated water is-11 ℃, and leaving water temperature(LWT) is-5 ℃.
The product that present embodiment obtains is after centrifugation, and trioxymethylene content is 94.8%, and formaldehyde content is 0.58%.
The invention is not restricted to the foregoing description, the quantity of extension type crystallizer middle sleeve assembly 14, the heat interchanging area of extension type crystallizer, the residence time, chilled-water flow and the inflow temperature of trioxymethylene suspension in extension type crystallizer 8 can and be determined according to the throughput selection.
Claims (9)
1, a kind of continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer, technical process is: the fresh trioxymethylene solution from preceding system enters recycle pump I (1), the circulation loop that post crystallization device (4) and connecting pipeline are formed mixes with trioxymethylene suspension, a part of trioxymethylene suspension in the post crystallization device (4) is delivered to whizzer by transferpump (3) and is carried out separating of trioxymethylene crystal and mother liquor, part mother liquor returns post crystallization device (4), make the concentration of trioxymethylene suspension meet mobile requirement, another part mother liquor returns preceding system, it is characterized in that the interior a part of trioxymethylene suspension of post crystallization device (4) is delivered to extension type crystallizer (8) by recycle pump II (2) and carries out heat exchange with refrigerated water, form the trioxymethylene nucleus, the trioxymethylene suspension after the heat exchange returns post crystallization device (4).
2, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 1, when it is characterized in that trioxymethylene suspension and refrigerated water carry out heat exchange, the flow direction contrary of refrigerated water and trioxymethylene suspension.
3, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 1 and 2 is characterized in that trioxymethylene suspension is entered by the bottom of extension type crystallizer (8), from the top output of extension type crystallizer (8).
4, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 1 and 2 is characterized in that every crystallization production line is provided with an extension type crystallizer (8).
5, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 3 is characterized in that every crystallization production line is provided with an extension type crystallizer (8).
6, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 1 and 2, the overall heat transfer coefficient that it is characterized in that extension type crystallizer is 300～400W/ (m
2K), when trioxymethylene suspension and refrigerated water carried out heat exchange, the residence time of trioxymethylene suspension in extension type crystallizer (8) was controlled at 1～6 minute, and the chilled water flow speed control is built in 0.1～1m/s, and the inflow temperature of refrigerated water is-10～-13 ℃.
7, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 3, the overall heat transfer coefficient that it is characterized in that extension type crystallizer is 300～400W/ (m
2K), when trioxymethylene suspension and refrigerated water carried out heat exchange, the residence time of trioxymethylene suspension in extension type crystallizer (8) was controlled at 1～6 minute, and the chilled water flow speed control is built in 0.1～1m/s, and the inflow temperature of refrigerated water is-10～-13 ℃.
8, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 4, the overall heat transfer coefficient that it is characterized in that extension type crystallizer is 300～400W/ (m
2K), when trioxymethylene suspension and refrigerated water carried out heat exchange, the residence time of trioxymethylene suspension in extension type crystallizer (8) was controlled at 1～6 minute, and the chilled water flow speed control is built in 0.1～1m/s, and the inflow temperature of refrigerated water is-10～-13 ℃.
9, the continuous process for freezing and crystallizing of trioxymethylene of application of sleeve formula crystallizer according to claim 5, the overall heat transfer coefficient that it is characterized in that extension type crystallizer is 300～400W/ (m
2K), when trioxymethylene suspension and refrigerated water carried out heat exchange, the residence time of trioxymethylene suspension in extension type crystallizer (8) was controlled at 1～6 minute, and the chilled water flow speed control is built in 0.1～1m/s, and the inflow temperature of refrigerated water is-10～-13 ℃.
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| CNB200710048792XA CN100528861C (en) | 2007-04-02 | 2007-04-02 | Process for freezing and crystallizing triformol continuouslly by sleeved crystallizer |
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| CNB200710048792XA CN100528861C (en) | 2007-04-02 | 2007-04-02 | Process for freezing and crystallizing triformol continuouslly by sleeved crystallizer |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102371080B (en) * | 2010-08-23 | 2013-12-04 | 中国石油化工股份有限公司 | Crystallizing method utilizing external circulation of crystal slurry |
| CN102371082B (en) * | 2010-08-23 | 2013-08-21 | 中国石油化工股份有限公司 | Crystallization method with overflow of clear mother liquor |
| CN102851052A (en) * | 2011-06-29 | 2013-01-02 | 沈阳铝镁设计研究院有限公司 | System and method for rapidly melting asphalt |
| CN102558137B (en) * | 2012-01-04 | 2015-02-04 | 上海蓝星聚甲醛有限公司 | Processing method and processing system of trioxymethylene crystal |
| CN102718740B (en) * | 2012-06-14 | 2014-04-23 | 北京旭阳化工技术研究院有限公司 | Trioxymethylene crystallization method |
| CN109224504A (en) * | 2018-10-26 | 2019-01-18 | 江苏华伦化工有限公司 | Continuous crystallisation device and its application |
| CN112108086B (en) * | 2020-09-24 | 2022-06-21 | 上海理工大学 | Directional solidification segregation device and method for colloidal particle system |
| CN114433364B (en) * | 2022-04-07 | 2022-06-17 | 深圳人体密码基因科技有限公司 | Centrifugal equipment for adjusting radius of rotor for gene detection |
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Non-Patent Citations (2)
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| 聚甲醛合成新工艺及其应用. 王敏.山西化工，第20卷第3期. 2000 |
| 聚甲醛合成新工艺及其应用. 王敏.山西化工，第20卷第3期. 2000 * |
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Effective date of registration: 20180503 Address after: 401221 No. 3 Hua Nan Road, Changshou economic and Technological Development Zone, Chongqing Co-patentee after: Yutianhua Co., Ltd., Yunnan Patentee after: Chongqing Yuntianhua day poly New Material Co. Ltd. Address before: 657800 Yunnan, Zhaotong, Yunnan, Yunnan Patentee before: Yutianhua Co., Ltd., Yunnan |