阅读说明：本技术 一种立式熔融结晶器 (Vertical melt crystallizer ) 是由 尹良友 刘兴然 张华� 陈宇 李炳亮 宋钊 黄海洋 于 2020-12-23 设计创作，主要内容包括：本发明公开了一种立式熔融结晶器,包括至少三个上下串联的结晶器单元,所述结晶器单元结构型式类似固管管板式换热器,物料在管内结晶,冷媒或热媒在壳程流动；所述结晶器单元之间通过管道连接,上一级母液自流进入下一级结晶器内,融晶液经中转罐,用泵送入上一级结晶器,能实现多级逆流结晶,以三级结晶器为例,原料液进入二级结晶器,三级结晶器为母液结晶,一级结晶器为重结晶,母液结晶保证了结晶收率,重结晶保证了最终产品的高纯度；本发明提供的一种立式熔融结晶器为多级结构,可以省去多级结晶器之间的中转料罐和中转泵,减小了结晶器整体体积,减小了占地面积,保证了最终产品的高纯度,又保证了结晶收率。(The invention discloses a vertical melt crystallizer, which comprises at least three crystallizer units which are connected in series up and down, wherein the structural form of the crystallizer units is similar to a fixed tube-plate heat exchanger, materials are crystallized in a tube, and a refrigerant or a heating medium flows in a shell pass; the crystallizer units are connected through a pipeline, the previous-stage mother liquor automatically flows into the next-stage crystallizer, the molten crystal liquid is conveyed into the previous-stage crystallizer through a transfer tank by a pump, multistage countercurrent crystallization can be realized, taking the third-stage crystallizer as an example, the raw material liquid enters the second-stage crystallizer, the third-stage crystallizer is used for mother liquor crystallization, the first-stage crystallizer is used for recrystallization, the mother liquor crystallization ensures the crystallization yield, and the recrystallization ensures the high purity of the final product; the vertical type melting crystallizer provided by the invention is of a multi-stage structure, a transfer material tank and a transfer pump between the multi-stage crystallizers can be omitted, the overall volume of the crystallizer is reduced, the occupied area is reduced, the high purity of a final product is ensured, and the crystallization yield is also ensured.)

1. A vertical melt crystallizer, characterized by: the crystallizer comprises at least three crystallizer units which are connected in series up and down, wherein the crystallizer units are connected up and down through a shell (4); a material inlet (511), a cold and heat medium outlet (512), a cold and heat medium inlet (513) and an inert gas inlet (514) are arranged on the cylinder body (5) of each stage of crystallizer unit, and a mother liquid, sweat and molten crystal liquid outlet is arranged on the lower end enclosure (6) of each stage of crystallizer unit; the material outlets and the material inlets (511) of all the crystallizer units are connected in series in sequence through pipelines to form multi-stage countercurrent crystallization.

2. A vertical melt crystallizer as defined in claim 1, wherein: the vertical crystallizer comprises three crystallizer units which are connected in series up and down, and a first crystallizer (1), a second crystallizer (2) and a third crystallizer (3) are respectively arranged from top to bottom;

the first crystallizer (1) comprises an upper end enclosure, a cylinder body (5), an upper tube plate (7), a heat exchange tube (8), a lower tube plate (9) and a lower end enclosure (6), wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder body (5); the outer wall of a cylinder body (5) of the first crystallizer is provided with a material inlet (511), a cold and hot medium inlet (512), a cold and hot medium outlet (513) and an inert gas inlet (514), the bottom of the lower seal head is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a first three-way valve (14), and different feed liquids can flow to different places through the three-way valve in a switching way.

3. A vertical melt crystallizer as defined in claim 2, wherein: the second crystallizer (2) comprises a cylinder (5), an upper tube plate (7), a heat exchange tube (8), a lower tube plate (9) and a lower end enclosure (6), wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder (5); the outer wall of the cylinder body (5) of the first crystallizer is provided with a material inlet (511), a cold and hot medium inlet (512), a cold and hot medium outlet (513) and an inert gas inlet (514), the bottom of the lower seal head is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a second three-way valve (24), and different feed liquids can flow to different places through the three-way valve in a switching way.

4. A vertical melt crystallizer as defined in claim 2, wherein: the third crystallizer (3) comprises a cylinder (5), an upper tube plate (7), a heat exchange tube (8), a lower tube plate (9) and a lower end enclosure (6), wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder (5); the outer wall of the cylinder body (5) of the first crystallizer is provided with a material inlet (511), a cold and hot medium inlet (512), a cold and hot medium outlet (513) and an inert gas inlet (514), the bottom of the lower seal head is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a third three-way valve (34), and different feed liquids can flow to different places through the three-way valve in a switching way.

5. A vertical melt crystallizer as defined in claim 1, wherein: the second crystallizer (2) is provided with a first molten crystal liquid transfer tank (100) and a first material transfer pump, the third crystallizer (3) is provided with a second molten crystal liquid transfer tank (200) and a second material transfer pump, and the bottom of the tower is provided with a mother liquid conveying pump.

6. A vertical melt crystallizer as defined in claim 1, wherein: the bottom of the crystallizer unit is provided with thermometers, namely a first thermometer arranged at the bottom of the first crystallizer (1), a second thermometer arranged at the bottom of the second crystallizer (2) and a third thermometer arranged at the bottom of the third crystallizer (3).

Technical Field

The invention belongs to the technical field of organic chemical separation, and particularly relates to a vertical melt crystallizer.

Background

In the prior art, the purification method of the lactide is the most commonly used melt crystallization process, because the crystallization process has low energy consumption and ensures the purity compared with the rectification.

In 2011, chinese patent CN202237354U discloses a melt crystallizer, which 1 comprises a cylindrical outer shell 2, a falling film crystallization tube 5 and a cooling medium distribution tray 10 vertically installed in the outer shell 2; the shell 2 is sealed at the opposite ends through the top plate 3 and the lower end enclosure 15, the upper part of the shell 2 is provided with a cooling medium inlet 17, a material inlet 6 and a material overflow port 7, the lower part of the shell is provided with a cooling medium outlet 13, and the lower end enclosure 15 of the crystallizer is provided with a material outlet 14; the falling film crystallization tube 5 is fixed through an upper tube plate 8 and a lower tube plate 9, the falling film crystallization tube 5 is inserted with a flow guide tube 4, the upper part of the flow guide tube 4 is provided with an exhaust hole 20, and the lower end is provided with a flow guide assembly 21; the cooling medium distribution tray 10 is provided with cooling medium diversion holes 16, overflow weirs 11, downcomers 12 and cooling medium diversion components 19 corresponding to the arrangement positions of the crystallization tubes, and the falling film crystallization tubes 5 pass through the diversion holes 16. Due to the adoption of the technical scheme, the crystallizer can select various cooling media according to the characteristics of separated materials, for example, water can be selected as the cooling medium in the dichlorobenzene crystallization process, the mixture of ethylene glycol and water can be selected as the cooling medium in the xylene crystallization process, the crystallizer can be processed and designed according to a normal-pressure container, the corrosion of the cooling medium to equipment is low, and the manufacturing cost and the maintenance cost of the equipment are effectively reduced; the cooling medium forms a thin liquid film on the outer wall of the crystallization tube, the crystallizer is not required to be filled with the cooling medium, the cooling medium is saved, the weight of the equipment during operation is reduced, and the large-scale equipment is facilitated; the cooling medium and the material realize cocurrent and cocurrent heat transfer, and the temperature difference between the separated material and the cooling medium is reduced due to cocurrent and cocurrent heat transfer, so that the supersaturation is reduced, the growth speed of the crystal is reduced, the occlusion of impurities in the crystal is reduced, and the crystallization process is more facilitated.

However, the existing crystallization equipment has a problem that most of the existing crystallization equipment only has a single crystallization process, the lactide purity is low, the yield is low, namely the lactide content in the discharged mother liquor and sweat is high, most importantly, the mother liquor completely flows back to a crystallizer system, impurities contained in the mother liquor cannot be discharged out of the system, the impurities can be enriched due to long-term operation, the product quality is finally unqualified, and the system cannot operate. The invention provides a vertical melt crystallizer, aiming at solving the problems that the product obtained by primary crystallization of lactide has low purity and low yield, impurities cannot be discharged out of a system and the like.

Disclosure of Invention

The present invention is directed to a vertical melt crystallizer to solve the problems set forth in the background art.

The invention provides a vertical melt crystallizer, which comprises at least three crystallizer units connected in series up and down, wherein the crystallizer units are connected up and down through a shell; a material inlet, a cold and hot medium outlet, a cold and hot medium inlet and an inert gas inlet are formed in the cylinder body of each stage of crystallizer unit, and a mother liquid, sweat and molten crystal liquid outlet is formed in the lower end enclosure of each stage of crystallizer unit; the material outlets and the material inlets of all the crystallizer units are connected in series in sequence through pipelines to form multi-stage countercurrent crystallization.

Preferably, the vertical crystallizer comprises three crystallizer units connected in series up and down, namely a first crystallizer, a second crystallizer and a third crystallizer from top to bottom;

the first crystallizer comprises an upper end enclosure, a cylinder, an upper tube plate, a heat exchange tube, a lower tube plate and a lower end enclosure, wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder; the outer wall of the cylinder body of the first crystallizer is provided with a material inlet, a cold and hot medium outlet and an inert gas inlet, the bottom of the lower end enclosure is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a first three-way valve, and different feed liquids can be switched to flow to different places through the three-way valve.

Preferably, the second crystallizer comprises a cylinder, an upper tube plate, a heat exchange tube, a lower tube plate and a lower end enclosure, wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder; the outer wall of the cylinder body of the first crystallizer is provided with a material inlet, a cold and hot medium outlet and an inert gas inlet, the bottom of the lower end enclosure is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a second through valve, and different feed liquids can flow to different places by switching the three-way valve.

Preferably, the third crystallizer comprises a cylinder, an upper tube plate, a heat exchange tube, a lower tube plate and a lower end enclosure, wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder; the outer wall of the cylinder body of the first crystallizer is provided with a material inlet, a cold and hot medium outlet and an inert gas inlet, the bottom of the lower seal head is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a third three-way valve, and different feed liquids can be switched to flow to different places through the three-way valve.

Preferably, in order to realize material turnover, the second crystallizer is provided with a first molten crystal liquid transfer tank and a first transfer pump, the third crystallizer is provided with a second molten crystal liquid transfer tank and a second transfer pump, and the bottom of the tower is provided with a mother liquid conveying pump.

Preferably, thermometers are arranged at the bottom of the crystallizer unit, and are respectively a first thermometer arranged at the bottom of the first crystallizer, a second thermometer arranged at the bottom of the second crystallizer, and a third thermometer arranged at the bottom of the third crystallizer.

Has the advantages that:

1. compared with the existing crystallizer, the vertical melting crystallizer provided by the invention is of a multilayer structure, each stage of crystallizer unit comprises a cylinder, and a material outlet and a material inlet which are arranged on the cylinder, and the material outlet and the material inlet of each stage of crystallizer unit are sequentially connected in series through a pipeline; a material storage tank and a pump which are arranged between the multi-stage tanks with the existing structure are omitted, so that the overall volume of the crystallizer is reduced, and the occupied area is also reduced;

2. the structure of the multistage crystallizer which is overlapped up and down is adopted, so that the mother liquor of the previous stage crystallizer automatically flows into the next stage crystallizer, a transfer tank and a transfer pump are omitted, and the investment and the operating cost are saved.

3. In the invention, crystallization mother liquor and sweat are crystallized for multiple times, taking 3 crystallizer units which are connected in series up and down as an example in the embodiment, and taking primary crystallization (namely secondary crystallization) as a basis, primary crystallization (namely primary crystallization and tertiary crystallization) is added in front and back respectively to form tertiary crystallization in a conformal manner, raw material liquid enters a second crystallization tower 2, and mother liquor 2 and melt crystal liquid 2 are obtained after crystallization is finished; the molten crystal 2 enters a first crystallization tower 1, and mother liquor 1 and the molten crystal 1 are obtained after crystallization is completed; the mother liquor 1 flows into the second crystallization tower 2, the mother liquor 2 discharged from the second crystallization tower 2 enters the third crystallization tower 3, the mother liquor 3 and the molten crystal liquid 3 are obtained after the crystallization of the third crystallization tower 3 is finished, the molten crystal liquid 3 returns to the second crystallization tower 2 again, the molten crystal liquid moves upwards in the whole system, the mother liquor moves downwards, and finally the high-purity lactide moves out of the system.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the structure of the crystallizer of the present invention.

Description of the drawings: the device comprises a first crystallizer 1, a first molten crystal liquid transfer tank 100, a second crystallizer 2, a second molten crystal liquid transfer tank 200, a third crystallizer 3, a shell 4, a cylinder 5, a material inlet 511, a cooling and heating medium inlet 512, a cooling and heating medium outlet 513, an inert gas inlet 514, a lower end enclosure 6, an upper tube plate 7, a heat exchange tube 8 and a lower tube plate 9.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Examples

As shown in fig. 1-2, the present embodiment provides a vertical melt crystallizer, which comprises at least three crystallizer units connected in series, and for convenience of description, 3 crystallizer units are used below to illustrate the problem; the crystallizer units are connected up and down through a shell 4; the crystallizer unit is similar to a fixed tube plate heat exchanger in structural style, materials are crystallized and melted in a tube pass, and a refrigerant heat medium flows in a shell pass to transfer heat; the cylinder 5 of each stage of crystallizer unit is provided with a material inlet 511, a cold and heat medium outlet 512, a cold and heat medium inlet 513 and an inert gas inlet 514, and the lower end enclosure 6 of each stage of crystallizer unit is provided with a mother liquid, sweat and molten crystal liquid outlet; the material outlets and the material inlets 511 of the crystallizer units of each stage are sequentially connected in series through pipelines to form multi-stage countercurrent crystallization.

Further, the vertical crystallizer comprises three crystallizer units which are connected in series up and down, namely a first crystallizer 1, a second crystallizer 2 and a third crystallizer 3 from top to bottom;

the first crystallizer 1 comprises an upper end enclosure, a cylinder 5, an upper tube plate 7, a heat exchange tube 8, a lower tube plate 9 and a lower end enclosure 6, wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder 5; the outer wall of the cylinder 5 of the first crystallizer is provided with a material inlet 511, a cooling and heating medium inlet 512, a cooling and heating medium outlet 513 and an inert gas inlet 514, the bottom of the lower seal head is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a first three-way valve 14, and different feed liquids can flow to different places through the three-way valve in a switching way.

Further, the second crystallizer 2 comprises a cylinder 5, an upper tube plate 7, a heat exchange tube 8, a lower tube plate 9 and a lower end enclosure 6, wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into the hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder 5; the outer wall of the cylinder 5 of the first crystallizer is provided with a material inlet 511, a cooling and heating medium inlet 512, a cooling and heating medium outlet 513 and an inert gas inlet 514, the bottom of the lower seal head is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a second three-way valve 24, and different feed liquids can flow to different places through the three-way valve in a switching way.

Further, the third crystallizer 3 comprises a cylinder 5, an upper tube plate 7, a heat exchange tube 8, a lower tube plate 9 and a lower end enclosure 6, wherein after the upper tube plate and the lower tube plate are drilled, the heat exchange tube penetrates into a hole, two ends of the heat exchange tube are respectively welded with the tube plates, and the upper tube plate and the lower tube plate are welded with the cylinder 5; the outer wall of the cylinder 5 of the first crystallizer is provided with a material inlet 511, a cooling and heating medium inlet 512, a cooling and heating medium outlet 513 and an inert gas inlet 514, the bottom of the lower seal head is provided with a discharge port for mother liquor, sweat and molten crystal liquid, the discharge port is connected with a third three-way valve 34, and different feed liquids can flow to different places through the three-way valve in a switching way.

Further, in order to realize material turnover, the second crystallizer 2 is provided with a first molten crystal liquid transfer tank 100 and a first transfer pump, the third crystallizer 3 is provided with a second molten crystal liquid transfer tank 200 and a second transfer pump, and the bottom of the tower is provided with a mother liquid conveying pump;

the raw material liquid enters the crystallizer from a material inlet 511 of the second crystallizer 2, after cooling and crystallization, mother liquid and sweat are discharged into a third crystallizer 3, the molten crystal liquid is discharged into a first molten crystal liquid transfer tank 100, and the raw material liquid is sent into the first crystallizer 1 through a first transfer pump;

after the first crystallizer 1 is cooled and crystallized, mother liquor and sweat are discharged into a second crystallizer 2, and molten crystal liquid is discharged into a pure product storage tank of the next procedure;

after the materials in the third crystallizer 3 are cooled and crystallized, mother liquor and sweat are discharged into a tower kettle at the bottom of the crystallizer, molten crystal liquid is discharged into a second molten crystal liquid transfer tank 200, and the feed liquid is sent into a second crystallizer 2 through a second transfer pump;

for the whole multistage crystallizer, the molten crystal liquid moves upwards, the mother liquid and sweat move downwards, the purity of the molten crystal liquid is higher the more the molten crystal liquid moves upwards, the impurity content of the materials is higher the more the molten crystal liquid moves downwards, and a multistage countercurrent crystallization process is formed.

Further, thermometers are arranged at the bottom of the crystallizer unit, namely a first thermometer arranged at the bottom of the first crystallizer 1, a second thermometer arranged at the bottom of the second crystallizer 2 and a third thermometer arranged at the bottom of the third crystallizer 3.

The working principle is as follows: in the embodiment, primary crystallization (i.e. secondary crystallization) is used as a basis, primary crystallization (i.e. primary crystallization and tertiary crystallization) is added in front of and behind the primary crystallization, three-level crystallization is formed by the primary crystallization and the secondary crystallization, the raw material liquid enters a second crystallization tower 2, and a mother liquid 2 and a molten crystal liquid 2 are obtained after the crystallization is completed; the molten crystal 2 enters a first crystallization tower 1, and mother liquor 1 and the molten crystal 1 are obtained after crystallization is completed; the mother liquor 1 flows into the second crystallization tower 2, the mother liquor 2 discharged from the second crystallization tower 2 enters the third crystallization tower 3, the mother liquor 3 and the molten crystal liquid 3 are obtained after the crystallization of the third crystallization tower 3 is completed, the molten crystal liquid 3 returns to the second crystallization tower 2 again, in the whole system, the molten crystal liquid moves leftwards, the mother liquor moves rightwards, and finally pure lactide moves out of the system.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

The present invention is not limited to the above description of the embodiments, and those skilled in the art should, in light of the present disclosure, appreciate that many changes and modifications can be made without departing from the spirit and scope of the invention.