Durene continuous suspension crystallization system

Abstract

The durene continuous suspension crystallization system comprises a crystallizer and a first circulating unit, and the first circulating unit comprises a first circulating pump and a cooler; the crystallizer is used for storing the durene enrichment liquid and crystallizing the durene enrichment liquid cooled by the cooler; the input end of the first circulating pump is communicated with the crystallizer, and the output end is connected with the material inlet of the cooler through a material supply pipeline; and a material outlet of the cooler is connected with the crystallizer through a material discharging pipeline. The durene enrichment liquid to be cooled and crystallized in the crystallizer is conveyed into the cooler through the first circulating pump, the cooler cools the durene enrichment liquid introduced into the crystallizer, and the cooled durene enrichment liquid is conveyed back to the crystallizer to be crystallized, so that uniform distribution of crystallized materials in the crystallizer can be promoted in the cooling and crystallizing process, and the crystallization efficiency is improved. Meanwhile, the contact efficiency of the cold source and the to-be-cooled enriched liquid and the heat removal efficiency of the cooler are improved, so that the crystallization efficiency is improved, and the purity and yield of final products are improved.

Description

Technical Field

[0001] The present application belongs to the field of chemical technology, and specifically relates to a durene continuous suspension crystallization system. Background Art

[0002] Durene, also known as 1,2,4,5-tetramethylbenzene, or duren (Durene or Durol), is an important fine chemical raw material, which can be used as an important raw material for medicine, powder coating matting agent, dye, pesticide, surfactant, etc. The main use of durene is to oxidize to generate pyromellitic acid anhydride, which can be polymerized with diamine compounds to produce polyimide engineering plastics with high temperature resistance and good insulation performance. Polyimide is an important material for high-tech industries such as microelectronics, aerospace and military industry.

[0003] At present, durene is mainly produced from C 10 It is separated from aromatic hydrocarbons, and a durene-enriched liquid (durene concentration is not less than 27wt%) is extracted and separated from mixed aromatic hydrocarbons by a distillation method, and then the durene-enriched liquid is sent to a crystallization unit for purification to obtain qualified durene crystals. The crystallization process needs to be achieved through a crystallizer, which generally includes a kettle crystallizer, a columnar crystallizer, a plate crystallizer, and a shell-and-tube crystallizer.

[0004] The static crystallization process currently widely used in industry has the following problems: (1) The enriched liquid to be cooled does not flow in the crystallizer, which can easily lead to problems such as uneven material distribution during the crystallization process and large temperature gradient of the material in the crystallizer, affecting the purity and yield of the final product; (2) The crystallizer often adopts a structure in which a cooling jacket is set on the outer layer of the kettle body. The cooling jacket on the outer layer of the kettle body is used to cool the material inside the kettle body. The contact efficiency between the cold source in the outer jacket and the enriched liquid to be cooled in the kettle body is low, and the heat exchange efficiency is low. The temperature control of the material at the center of the kettle body is unstable and the cooling of the material in the kettle body is uneven, which ultimately leads to low overall crystallization efficiency and affects the purity and yield of the final product. Utility Model Content

[0005] In order to solve the technical problems in the prior art that the enriched liquid to be cooled in the crystallizer does not flow, which easily leads to uneven material distribution in the crystallization process, large temperature gradient of the material in the crystallizer, low contact efficiency between the cold source and the enriched liquid to be cooled in the crystallizer, and low heat exchange efficiency, the present application provides a continuous suspension crystallization system of tetramethylbenzene.

[0006] The present application provides a durene continuous suspension crystallization system, comprising a crystallizer and a first circulation unit, wherein the first circulation unit comprises a first circulation pump and a cooler, wherein:

[0007] The crystallizer is used to store durene-rich liquid and to crystallize the durene-rich liquid after being cooled by the cooler;

[0008] The input end of the first circulation pump is communicated with the crystallizer, and the output end is connected to the material inlet of the cooler through a material feeding pipeline, so as to transport the durene-enriched liquid to be cooled and crystallized in the crystallizer to the cooler;

[0009] The material outlet of the cooler is connected to the crystallizer through a material discharge pipeline, and is used to cool the durenyl-rich liquid introduced from the first circulation pump, and transport the cooled durenyl-rich liquid back to the crystallizer.

[0010] In some optional embodiments, the medium inlet of the cooler is connected to a medium supply pipeline, and the medium outlet of the cooler is connected to a medium discharge pipeline.

[0011] In some optional embodiments, the first circulation unit also includes a second circulation pump and a heat exchanger; the second circulation pump is arranged on the medium discharge pipeline; the material inlet of the heat exchanger is connected to the output end of the second circulation pump, and the material outlet of the heat exchanger is connected to the medium supply pipeline, which is used to melt the cooler with the heated medium.

[0012] In some optional embodiments, the medium inlet of the heat exchanger is connected to a steam pipeline, and the medium outlet of the heat exchanger is connected to a condensate pipeline.

[0013] In some optional implementations, a first pressure gauge is provided on the material supply pipeline, and a second pressure gauge is provided on the material discharge pipeline.

[0014] In some optional embodiments, a flow regulating valve is provided on the medium discharge pipeline, and the flow regulating valve is used to adjust the return flow rate of the chilled water of the cooler.

[0015] In some optional embodiments, a thermometer is provided on the medium supply pipeline.

[0016] In some optional embodiments, a second circulation unit is further included, and the second circulation unit has the same structure as the first circulation unit.

[0017] In some optional embodiments, when the cooler of the first circulation unit is melting crystals, the first circulation pump of the first circulation unit is stopped, and the first circulation pump of the second circulation unit is started, and the tetramethylbenzene-rich liquid introduced from the first circulation pump is cooled by the cooler of the second circulation unit, and the cooled tetramethylbenzene-rich liquid is transported back to the crystallizer for crystallization.

[0018] In some optional embodiments, when the cooler of the second circulation unit is melting crystals, the first circulation pump of the second circulation unit is stopped, and the first circulation pump of the first circulation unit is started, and the tetramethylbenzene-rich liquid introduced from the first circulation pump is cooled by the cooler of the first circulation unit, and the cooled tetramethylbenzene-rich liquid is transported back to the crystallizer for crystallization.

[0019] Compared with the prior art, the durene continuous suspension crystallization system provided by the utility model has the following beneficial effects:

[0020] The durene-rich liquid to be cooled and crystallized in the crystallizer is transported to the cooler by the first circulation pump, the durene-rich liquid introduced from the first circulation pump is cooled by the cooler, and the cooled durene-rich liquid is transported back to the crystallizer for crystallization. This can promote uniform distribution of crystallized materials in the crystallizer during the cooling and crystallization process, reduce the temperature gradient of the materials in the crystallizer, and improve the contact efficiency between the cold source and the rich liquid to be cooled and the heat removal efficiency of the cooler, thereby improving the crystallization efficiency and improving the purity and yield of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The schematic diagram of the structure of the durene continuous suspension crystallization system in one or more embodiments of the utility model is shown.

[0022] Explanation of the reference numerals: 1-crystallizer; 100-first circulation unit; 200-second circulation unit; 2-first circulation pump; 3-cooler; 4-second circulation pump; 5-heat exchanger; 6-material supply pipeline; 7-material discharge pipeline; 8-medium supply pipeline; 9-medium discharge pipeline; 10-steam pipeline; 11-condensate pipeline; 12-first pressure gauge; 13-second pressure gauge; 14-thermometer; 15-flow regulating valve. DETAILED DESCRIPTION

[0023] In order to make the technical personnel in the technical field to which the present application belongs to understand the present application more clearly, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0024] Please refer to Figure 1 As shown, the embodiment of the present application provides a durene continuous suspension crystallization system, comprising a crystallizer 1 and a first circulation unit 100, wherein the first circulation unit 100 comprises a first circulation pump 2 and a cooler 3, wherein:

[0025] The crystallizer 1 is used to store durene-enriched liquid and to crystallize the durene-enriched liquid after being cooled by the cooler; the crystallizer 1 may be a kettle-type crystallizer;

[0026] The input end of the first circulation pump 2 is communicated with the crystallizer 1, and the output end is connected to the material inlet of the cooler 3 through the material feeding pipeline 6, so as to transport the durene-enriched liquid to be cooled and crystallized in the crystallizer 1 to the cooler 3;

[0027] The material outlet of the cooler 3 is connected to the crystallizer 1 through a material discharge pipeline 7 , and is used to cool the durenyl-rich liquid introduced from the first circulation pump 2 , and transport the cooled durenyl-rich liquid back to the crystallizer 1 .

[0028] The durenyl continuous suspension crystallization system provided in the embodiment of the present application transports the durenyl rich liquid to be cooled and crystallized in the crystallizer 1 to the cooler 3 through the first circulation pump 2, cools the durenyl rich liquid introduced from the first circulation pump 2 through the cooler 3, and transports the cooled durenyl rich liquid back to the crystallizer 1, which can promote the uniform distribution of the crystallized material in the crystallizer 1 during the cooling crystallization process, reduce the temperature gradient of the material in the crystallizer 1, and at the same time improve the contact efficiency between the cold source and the rich liquid to be cooled and the heat removal efficiency of the cooler 3, so as to improve the crystallization efficiency and improve the purity and yield of the final product.

[0029] In some optional embodiments, the medium inlet of the cooler 3 is connected to a medium supply pipeline 8, and the medium outlet of the cooler 3 is connected to a medium discharge pipeline 9. Chilled water is provided to the medium inlet of the cooler 3 through the medium supply pipeline 8, and after passing through the cooler 3, the chilled water flows from the medium outlet to the medium discharge pipeline 9 and flows out, thereby completing the circulation supply of the refrigerant to the cooler 3.

[0030] In some optional embodiments, the first circulation unit 100 further includes a second circulation pump 4 and a heat exchanger 5; the second circulation pump 4 is disposed on the medium discharge pipeline 9; the material inlet of the heat exchanger 5 is connected to the output end of the second circulation pump 4, and the material outlet of the heat exchanger 5 is connected to the medium supply pipeline 8, which is used to melt the cooler 3 through the heated medium. The second circulation pump 4 increases the pressure of the chilled water discharged from the cooler 3 to enhance its fluidity; part of the chilled water from the cooler 3 flows out through the medium discharge pipeline 9, and part enters the heat exchanger 5. The heat exchanger 5 heats the chilled water and provides the heated chilled water to the cooler 3 from the medium inlet of the cooler 3 to melt the cooler 3, thereby preventing the inner wall of the cooling pipe of the cooler 3 from being attached by crystals and affecting the cooling effect, and improving the reliability and stability of the device.

[0031] In some optional embodiments, the medium inlet of the heat exchanger 5 is connected to a steam pipeline 10, and the medium outlet of the heat exchanger 5 is connected to a condensate pipeline 11. Low-pressure steam is transported to the medium inlet of the heat exchanger 5 through the steam pipeline 10, and the low-pressure steam is converted into low-pressure steam condensate after heat exchange with chilled water in the heat exchanger 5, and is discharged from the medium outlet of the heat exchanger 5 through the condensate pipeline 11, thereby completing the supply of heat exchange medium of the heat exchanger 5.

[0032] In some optional embodiments, a first pressure gauge 12 is provided on the material supply pipeline 6, and a second pressure gauge 13 is provided on the material discharge pipeline 7. The inlet pressure of the cooler 3 is detected by the first pressure gauge 12, and the outlet pressure of the cooler 3 is detected by the second pressure gauge 13. When the difference between the inlet pressure and the outlet pressure of the cooler 3 reaches a set value (the set value may be 0.02-0.10 MPa), it is determined that the cooling tubes of the cooler 3 are blocked, and the cooler 3 needs to be melted.

[0033] In some optional embodiments, a flow regulating valve 15 is provided on the medium discharge pipeline 9, and the flow regulating valve 15 is used to adjust the return flow rate of the chilled water of the cooler 3. There are two branches coming out of the medium discharge pipeline 9, one branch returns the chilled water, and the other branch enters the heat exchanger 5. By providing the flow regulating valve 15 on the branch of the chilled water return, the return flow rate of the chilled water of the cooler 3 is adjusted by the flow regulating valve 15, so that the chilled water flow entering the heat exchanger 5 can also be adjusted.

[0034] In some optional embodiments, a thermometer 14 is provided on the medium supply pipeline 8. By providing the thermometer 14 on the medium supply pipeline 8, the thermometer 14 measures the temperature of the chilled water, the thermometer 14 is electrically connected to the flow control valve 15, and the opening of the flow control valve 15 is controlled by the temperature measured by the thermometer 14. When the temperature measured by the thermometer 14 is lower than the required temperature, the flow control valve 15 is controlled to reduce the chilled water return flow of the cooler 3, so that the chilled water flow entering the heat exchanger 5 increases; when the temperature measured by the thermometer 14 is higher than the required temperature, the flow control valve 15 is controlled to increase the chilled water return flow of the cooler 3, so that the chilled water flow entering the heat exchanger 5 decreases.

[0035] In some optional embodiments, the durene continuous suspension crystallization system further includes a second circulation unit 200 , and the second circulation unit 200 has the same structure as the first circulation unit 100 . The second circulation unit 200 includes a cooler 3, a first circulation pump 2, a heat exchanger 5, a second circulation pump 4, a first pressure gauge 12, a second pressure gauge 13 and a thermometer 14, etc. The cooler 3, the first circulation pump 2, the heat exchanger 5 and the second circulation pump 4 of the second circulation unit 200 can be used as a backup, one for use and one for backup. When the difference between the inlet pressure and the outlet pressure of a cooler 3 reaches a set value (the set value can be 0.02-0.10MPa) or the use reaches a predetermined time (the predetermined time can be 12-72 hours), it is determined that the cooler 3 needs to be melted, the cooler 3 and the corresponding first circulation pump 2 are cut out, the branch of the chilled water return of the cooler 3 is closed, the corresponding heat exchanger 5 provides a heat source to heat the circulating water, and the circulating water is pumped to the cut-out cooler 3 through the chilled water circulation pump for melting, and another group of coolers 3 and the first circulation pump 2 are put into use to maintain the continuous operation of the crystallizer 1, which can achieve continuous production and improve production efficiency.

[0036] In some optional embodiments, when the cooler 3 of the first circulation unit 100 is melting crystals, the first circulation pump 2 of the first circulation unit 100 is stopped, and the first circulation pump 2 of the second circulation unit 200 is started, and the tetramethylbenzene-rich liquid introduced from the first circulation pump 2 is cooled by the cooler 3 of the second circulation unit 200, and the cooled tetramethylbenzene-rich liquid is transported back to the crystallizer 1 for crystallization.

[0037] In some other optional embodiments, when the cooler 3 of the second circulation unit 200 is melting crystals, the first circulation pump 2 of the second circulation unit 200 is shut down, and the first circulation pump 2 of the first circulation unit 100 is started, and the tetramethylbenzene-rich liquid introduced from the first circulation pump 2 is cooled by the cooler 3 of the first circulation unit 100, and the cooled tetramethylbenzene-rich liquid is transported back to the crystallizer 1 for crystallization.

[0038] The working principle of the durenyl continuous suspension crystallization system proposed by the utility model is as follows: the first circulating pump 2 transports the durenyl rich liquid in the crystallizer 1 to the cooler 3, the durenyl rich liquid introduced from the first circulating pump 2 is cooled by the cooler 3, and the cooled durenyl rich liquid is transported back to the crystallizer 1, which can promote the uniform distribution of the crystallized material in the crystallizer during the cooling crystallization process, and at the same time improve the contact efficiency between the cold source and the enriched liquid to be cooled and the heat removal efficiency of the cooler 3, so as to improve the crystallization efficiency and the purity and yield of the final product; the cooler 3, the first circulating pump 2, the heat exchanger 5, and the second circulating pump 4 are all one for use and one for standby, and when one group of coolers 3 needs to melt crystals and the corresponding first circulating pump 2 is shut down, the other group of coolers 3 and the first circulating pump 2 are put into use to maintain the continuous operation of the crystallizer 1, so as to realize continuous production and improve production efficiency.

[0039] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise" and "counterclockwise" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0043] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A durene continuous suspension crystallization system, characterized in that: It comprises a crystallizer and a first circulation unit, wherein the first circulation unit comprises a first circulation pump and a cooler, wherein: The crystallizer is used to store durene-rich liquid and to crystallize the durene-rich liquid after being cooled by the cooler; The input end of the first circulation pump is communicated with the crystallizer, and the output end is connected to the material inlet of the cooler through a material feeding pipeline, so as to transport the durene-enriched liquid to be cooled and crystallized in the crystallizer to the cooler; The material outlet of the cooler is connected to the crystallizer through a material discharge pipeline, and is used to cool the durenyl-rich liquid introduced from the first circulation pump, and transport the cooled durenyl-rich liquid back to the crystallizer.

2. The durene continuous suspension crystallization system according to claim 1, characterized in that: The medium inlet of the cooler is connected to a medium supply pipeline, and the medium outlet of the cooler is connected to a medium discharge pipeline.

3. The durene continuous suspension crystallization system according to claim 2, characterized in that: The first circulation unit also includes a second circulation pump and a heat exchanger; the second circulation pump is arranged on the medium discharge pipeline; the material inlet of the heat exchanger is connected to the output end of the second circulation pump, and the material outlet of the heat exchanger is connected to the medium supply pipeline, which is used to melt the cooler through the heated medium.

4. The durene continuous suspension crystallization system according to claim 3, characterized in that: The medium inlet of the heat exchanger is connected to a steam pipeline, and the medium outlet of the heat exchanger is connected to a condensate pipeline.

5. The durene continuous suspension crystallization system according to claim 4, characterized in that: The material supply pipeline is provided with a first pressure gauge, and the material discharge pipeline is provided with a second pressure gauge.

6. The durene continuous suspension crystallization system according to claim 5, characterized in that: The medium discharge pipeline is provided with a flow regulating valve, and the flow regulating valve is used to regulate the return flow of the chilled water of the cooler.

7. The durene continuous suspension crystallization system according to claim 6, characterized in that: A thermometer is arranged on the medium supply pipeline.

8. The durene continuous suspension crystallization system according to any one of claims 1 to 7, characterized in that: It also includes a second circulation unit, which has the same structure as the first circulation unit.

9. The durene continuous suspension crystallization system according to claim 8, characterized in that: When the cooler of the first circulation unit is melting crystals, the first circulation pump of the first circulation unit is stopped, and the first circulation pump of the second circulation unit is started, and the tetramethylbenzene-rich liquid introduced from the first circulation pump is cooled by the cooler of the second circulation unit, and the cooled tetramethylbenzene-rich liquid is transported back to the crystallizer for crystallization.

10. The durene continuous suspension crystallization system according to claim 8, characterized in that: When the cooler of the second circulation unit is melting crystals, the first circulation pump of the second circulation unit is stopped, and the first circulation pump of the first circulation unit is started, and the tetramethylbenzene-rich liquid introduced from the first circulation pump is cooled by the cooler of the first circulation unit, and the cooled tetramethylbenzene-rich liquid is transported back to the crystallizer for crystallization.

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