Suspension crystallizer and crystallization method

Abstract

The invention discloses a suspension crystallizer and a crystallization method. The suspension crystallizer comprises a crystallizer, a refrigerant storage tank, a mother liquor storage tank and a static mixer, the crystallizer comprises a tank body, a guide cylinder is arranged in the tank body, and a disperser and a push type stirrer are arranged in the guide cylinder; the refrigerant storage tank is connected with an inlet of the static mixer through a refrigerant conveying pipeline, and the mother liquor storage tank is connected with the inlet of the static mixer through a mother liquor conveying pipeline; a refrigerant and mother liquor are mixed in the static mixer to form mixed liquid, the mixed liquid is conveyed into the guide cylinder through the mixed liquid conveying pipeline, and an outlet of the mixed liquid conveying pipeline is located above the disperser. A built-in guide cylinder is adopted, the mother liquor is cooled in a refrigerant and mother liquor mixing mode, the mass transfer effect of the solution is enhanced in a forced internal circulation mode, and the crystallization temperature and the cooling rate can be accurately controlled by controlling the temperature and the adding amount of the refrigerant, so that uniform crystallization of to-be-separated substances in the mother liquor is realized.

Description

Technical Field

[0001] This invention relates to the field of separation and purification technology, and in particular to a suspension crystallizer and crystallization method. Background Technology

[0002] Suspension crystallization is a crystallization process in a solution phase. It is a melt crystallization separation and purification technology based on the difference in solubility or melting point of substances. The core principle is to create appropriate crystallization conditions that allow solid substances to crystallize out of the mother liquor and suspend in it, followed by solid-liquid separation to obtain a target product with high purity. Creating the necessary suspension crystallization conditions is crucial. A common method for creating these conditions is to cool the raw material (molten liquid or solution) to a supersaturated state.

[0003] Existing suspension crystallizers typically use coil or tube heat exchangers for cooling (202420953214.X; 202211335728.0). Due to the limited heat exchange surface area, it is difficult to precisely control the temperature gradient in the mother liquor. While external circulation of the mother liquor or the installation of a stirring device in the crystallization zone can improve mass and heat transfer, localized temperature gradients in the mother liquor cannot be eliminated. Therefore, existing suspension crystallization technologies exhibit unsatisfactory heat and mass transfer effects, and inaccurate temperature control, resulting in uneven crystallization and affecting product purity.

[0004] In addition, due to limitations in heat and mass transfer methods, existing suspension crystallizers generally have complex structures and require significant investment. Summary of the Invention

[0005] In order to solve the problems in the prior art, the present invention provides a suspension crystallizer and a crystallization method.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A suspension crystallizer includes a crystallizer, a refrigerant storage tank, a mother liquor storage tank, and a static mixer; The crystallizer includes a tank body, inside which is a guide tube. Both the upper and lower ends of the guide tube are open, and there are gaps between the guide tube and the tank body in the vertical and circumferential directions. A stirring shaft is installed inside the guide tube, with the upper end of the stirring shaft extending out of the tank body and connected to a stirring power unit. A disperser and a propeller-type agitator are installed on the stirring shaft inside the guide tube, with the disperser located above the propeller-type agitator. The disperser and the propeller-type agitator rotate with the stirring shaft. The propeller-type agitator pushes the mixed liquid downward along the axial direction of the guide tube. After exiting the guide tube, the mixed liquid flows upward along the axial direction outside the guide tube and enters the interior of the guide tube from the top, forming an internal circulation inside the crystallizer. The refrigerant storage tank is connected to the inlet of the static mixer via a refrigerant delivery pipeline. A first heat exchanger and a refrigerant flow meter are also installed on the refrigerant delivery pipeline. The mother liquor storage tank is connected to the inlet of the static mixer via a mother liquor delivery pipeline. A mother liquor flow meter is also installed on the mother liquor delivery pipeline. The refrigerant and mother liquor are mixed in a static mixer to form a mixed liquid. The mixed liquid is then transported to the inside of the guide tube through a mixed liquid delivery pipe, and the outlet of the mixed liquid delivery pipe is located above the disperser.

[0007] Preferably, the guide tube is coaxially arranged with the tank body, and the stirring shaft is coaxially arranged with the guide tube.

[0008] Preferably, the propeller-type agitator is located at the lower part of the guide tube, and the outlet of the mixed liquid conveying pipe is located at the upper part of the guide tube.

[0009] Preferably, the disperser is a single-stage disperser or a multi-stage series disperser arranged axially along the stirring shaft.

[0010] Preferably, the refrigerant delivery pipeline is equipped with a refrigerant circulation pump; the mother liquor delivery pipeline is equipped with a mother liquor circulation pump.

[0011] Preferably, the crystallizer has an evaporation port at the top of the tank, and the evaporation port is connected to the refrigerant storage tank through a refrigerant recovery pipe. The refrigerant recovery pipe is equipped with a compressor and a second heat exchanger.

[0012] Preferably, the crystallizer has a discharge port at the bottom of the tank, which is connected to a solid-liquid separation device. The solid-liquid separation device has a solid product outlet and a liquid phase outlet, and the liquid phase outlet is connected to the inlet of a static mixer through a liquid phase outlet pipe.

[0013] Preferably, the liquid phase outlet pipe is equipped with a liquid phase flow meter and a liquid phase circulation pump.

[0014] The present invention also discloses a suspension crystallization method, based on the aforementioned suspension crystallizer, comprising the following steps: An inert solvent that does not react with the mother liquor is selected as the refrigerant. After being pumped out of the refrigerant storage tank, the refrigerant is heated to the required temperature through the first heat exchanger and its flow rate is controlled by a refrigerant flow meter before entering the static mixer. At the same time, the mother liquor in the mother liquor storage tank also enters the static mixer after its flow rate is controlled by a mother liquor flow meter. In the above process, the required refrigerant temperature and refrigerant flow rate are calculated based on the mother liquor flow rate and crystallization temperature. After the refrigerant and mother liquor are thoroughly mixed in the static mixer to form a mixed liquid, the mixed liquid is transported to the upper part of the guide tube inside the crystallizer. After passing through the disperser, the material mixing and crystal suspension state are optimized. The uniformly mixed liquid flows downward along the axis of the guide tube by the action of the propeller agitator. After exiting the guide tube, the mixed liquid flows upward along the axis outside the guide tube and enters the interior of the guide tube from the top, forming an internal circulation inside the crystallizer to achieve uniform crystallization of the substances to be separated in the mother liquor. The material that has been cooled and crystallized is transported to the solid-liquid separation device through the discharge port at the bottom of the crystallizer. The separated solid is collected through the solid product outlet, and the separated liquid phase re-enters the static mixer through the liquid phase outlet to participate in the crystallization process.

[0015] Preferably, the crystallization temperature and cooling rate are controlled by adjusting the temperature and amount of refrigerant added. The beneficial effects of this invention are: This invention employs a built-in flow guide tube to cool the mother liquor by mixing refrigerant and mother liquor. The mass transfer effect of the solution is enhanced by forced internal circulation. By controlling the temperature and amount of refrigerant added, the crystallization temperature and cooling rate can be precisely controlled, thereby achieving uniform crystallization of the substances to be separated in the mother liquor.

[0016] The suspension crystallization technology of the present invention has the advantages of simple crystallizer structure, low investment, high separation efficiency, and high product purity. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Example 1

[0020] like Figure 1 As shown, this embodiment provides a suspension crystallizer, including a crystallizer 1, a refrigerant storage tank 2, a mother liquor storage tank 3, and a static mixer 4.

[0021] The crystallizer 1 includes a tank body 11. A guide tube 12, coaxial with the tank body 11, is located at the center of the tank body 11. Both the upper and lower ends of the guide tube 12 are open, and there are gaps between the guide tube 12 and the tank body 11 in the vertical and circumferential directions. A stirring shaft 13 is coaxially installed inside the guide tube 12. The upper end of the stirring shaft 13 extends out of the tank body 11 and is connected to the stirring power unit 14.

[0022] A disperser 15 and a propeller-type agitator 16 are installed on the stirring shaft 13 inside the guide tube 12. The disperser 15 is located above the propeller-type agitator 16, and the propeller-type agitator is located at the bottom of the guide tube. The disperser 15 and the propeller-type agitator 16 rotate with the stirring shaft. The propeller-type agitator 16 pushes the mixed liquid downward along the axial direction of the guide tube 12. After exiting the guide tube 12, the mixed liquid flows upward along the axial direction outside the guide tube 12 and enters the interior of the guide tube 12 from the top, forming an internal circulation inside the crystallizer.

[0023] In this embodiment, the propeller mixer 16 and the disperser 15 are existing mature components, and their specific structures will not be described in detail.

[0024] The refrigerant storage tank 2 is connected to the inlet of the static mixer 4 via a refrigerant delivery pipeline. A refrigerant circulation pump 21, a first heat exchanger 22, and a refrigerant flow meter 23 are also sequentially installed on the refrigerant delivery pipeline. The mother liquor storage tank 3 is connected to the inlet of the static mixer 4 via a mother liquor delivery pipeline. A mother liquor circulation pump 31 and a mother liquor flow meter 32 are also sequentially installed on the mother liquor delivery pipeline.

[0025] After the refrigerant and mother liquor are fully mixed in the static mixer 4, a mixed liquid is formed. The mixed liquid is transported to the inside of the guide tube 12 through the mixed liquid transport pipe, and the outlet of the mixed liquid transport pipe is located above the disperser 15 and at the upper part of the guide tube 12.

[0026] The crystallizer 1 has a discharge port at the bottom of the tank 11, which is connected to the solid-liquid separation device 5. The solid-liquid separation device 5 has a solid product outlet and a liquid phase outlet. The liquid phase outlet is connected to the inlet of the static mixer 4 through a liquid phase outlet pipe. A liquid phase flow meter 51 and a liquid phase circulation pump 52 are installed sequentially on the liquid phase outlet pipe.

[0027] The crystallizer 1 has an evaporation port at the top of the tank 11. The evaporation port is connected to the refrigerant storage tank 2 through a refrigerant recovery pipe. The refrigerant recovery pipe is equipped with a compressor 61 and a second heat exchanger 62. The refrigerant evaporated from the top of the crystallizer 1 is compressed and cooled before entering the refrigerant storage tank 2 for recycling.

[0028] This invention employs a built-in flow guide tube to cool the mother liquor by mixing refrigerant and mother liquor, and enhances the mass transfer effect of the solution through forced internal circulation, thereby achieving uniform crystallization of the substances to be separated in the mother liquor. Example 2

[0029] The difference between this embodiment and Embodiment 1 lies in the arrangement of the disperser. Embodiment 1 uses a single-stage disperser, while this embodiment uses a multi-stage series disperser arranged along the stirring shaft axis. Example 3

[0030] This embodiment discloses a suspension crystallization method based on the suspension crystallizer of Embodiment 1 or Embodiment 2, including the following steps: An inert solvent that does not react with the mother liquor is selected as the refrigerant. After exiting the refrigerant storage tank pump 2, the refrigerant passes through the first heat exchanger 22 to exchange heat to the required temperature, and its flow rate is controlled by the refrigerant flow meter 23 before entering the static mixer 4. At the same time, the mother liquor in the mother liquor storage tank 3 also enters the static mixer 4 after its flow rate is controlled by the mother liquor flow meter 32. In the above process, the required refrigerant temperature and refrigerant flow rate are calculated based on the mother liquor flow rate and crystallization temperature.

[0031] After the refrigerant and mother liquor are fully mixed in the static mixer 4, a mixed liquid is formed. The mixed liquid is transported to the upper part of the guide tube 12 inside the crystallizer 1. After passing through the disperser 15, the material mixing and crystal suspension state are optimized. The uniformly mixed liquid flows downward along the axis of the guide tube 12 under the action of the propeller agitator 16. After exiting the guide tube 12, the mixed liquid flows upward along the axis outside the guide tube 12 and enters the interior of the guide tube 12 from the top, forming an internal circulation inside the crystallizer, enhancing the mass transfer effect, and realizing the uniform crystallization of the substances to be separated in the mother liquor.

[0032] The material that has been cooled and crystallized is transported to the solid-liquid separation device 5 through the discharge port at the bottom of the crystallizer 1. The separated solid is collected through the solid product outlet, and the separated liquid phase re-enters the static mixer 4 through the liquid phase outlet to participate in the crystallization process.

[0033] In the above crystallization method, the residence time of the material in the crystallizer is controlled by adjusting the discharge flow rate based on the feed rate.

[0034] In the above crystallization method, the crystallization temperature and cooling rate can be precisely controlled by adjusting the temperature and amount of refrigerant added.

[0035] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

[0036] If the terms "first" or "second" are used in this document to define components, those skilled in the art should know that the use of "first" or "second" is merely for the convenience of describing the invention and simplifying the description, and unless otherwise stated, the above terms have no special meaning.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A suspension crystallizer, characterized in that: Includes crystallizer, refrigerant storage tank, mother liquor storage tank and static mixer; The crystallizer includes a tank body, inside which is a guide tube. Both the upper and lower ends of the guide tube are open, and there are gaps between the guide tube and the tank body in the vertical and circumferential directions. A stirring shaft is installed inside the guide tube, with the upper end of the stirring shaft extending out of the tank body and connected to a stirring power unit. A disperser and a propeller-type agitator are installed on the stirring shaft inside the guide tube, with the disperser located above the propeller-type agitator. The disperser and the propeller-type agitator rotate with the stirring shaft. The propeller-type agitator pushes the mixed liquid downward along the axial direction of the guide tube. After exiting the guide tube, the mixed liquid flows upward along the axial direction outside the guide tube and enters the interior of the guide tube from the top, forming an internal circulation inside the crystallizer. The refrigerant storage tank is connected to the inlet of the static mixer via a refrigerant delivery pipeline. A first heat exchanger and a refrigerant flow meter are also installed on the refrigerant delivery pipeline. The mother liquor storage tank is connected to the inlet of the static mixer via a mother liquor delivery pipeline. A mother liquor flow meter is also installed on the mother liquor delivery pipeline. The refrigerant and mother liquor are mixed in a static mixer to form a mixed liquid. The mixed liquid is then transported to the inside of the guide tube through a mixed liquid delivery pipe, and the outlet of the mixed liquid delivery pipe is located above the disperser.

2. The suspension crystallizer according to claim 1, characterized in that: The guide tube is coaxially arranged with the tank body, and the stirring shaft is coaxially arranged with the guide tube.

3. The suspension crystallizer according to claim 1, characterized in that: The propulsion agitator is located at the lower part of the guide tube, and the outlet of the mixed liquid conveying pipe is located at the upper part of the guide tube.

4. The suspension crystallizer according to claim 1, characterized in that: The disperser is a single-stage disperser or a multi-stage series disperser arranged axially along the stirring shaft.

5. The suspension crystallizer according to claim 1, characterized in that: The refrigerant delivery pipeline is equipped with a refrigerant circulation pump; the mother liquor delivery pipeline is equipped with a mother liquor circulation pump.

6. The suspension crystallizer according to claim 1, characterized in that: The crystallizer has an evaporation port at the top of the tank. The evaporation port is connected to the refrigerant storage tank through a refrigerant recovery pipe. A compressor and a second heat exchanger are installed on the refrigerant recovery pipe.

7. The suspension crystallizer according to any one of claims 1-6, characterized in that: The crystallizer has a discharge port at the bottom of the tank, which is connected to a solid-liquid separation device. The solid-liquid separation device has a solid product outlet and a liquid phase outlet. The liquid phase outlet is connected to the inlet of a static mixer through a liquid phase outlet pipe.

8. The suspension crystallizer according to claim 7, characterized in that: The liquid phase outlet pipe is equipped with a liquid phase flow meter and a liquid phase circulation pump.

9. A suspension crystallization method, based on the suspension crystallizer of claim 7 or 8, characterized in that... Includes the following steps: An inert solvent that does not react with the mother liquor is selected as the refrigerant. After being pumped out of the refrigerant storage tank, the refrigerant is heated to the required temperature by the first heat exchanger and its flow is controlled by the refrigerant flow meter before entering the static mixer. At the same time, the mother liquor in the mother liquor storage tank also enters the static mixer after its flow is controlled by the mother liquor flow meter. In the above process, the required refrigerant temperature and refrigerant flow rate are calculated based on the mother liquor flow rate and crystallization temperature; After the refrigerant and mother liquor are thoroughly mixed in the static mixer to form a mixed liquid, the mixed liquid is transported to the upper part of the guide tube inside the crystallizer. After passing through the disperser, the material mixing and crystal suspension state are optimized. The uniformly mixed liquid flows downward along the axis of the guide tube by the action of the propeller agitator. After exiting the guide tube, the mixed liquid flows upward along the axis outside the guide tube and enters the interior of the guide tube from the top, forming an internal circulation inside the crystallizer to achieve uniform crystallization of the substances to be separated in the mother liquor. The material that has been cooled and crystallized is transported to the solid-liquid separation device through the discharge port at the bottom of the crystallizer. The separated solid is collected through the solid product outlet, and the separated liquid phase re-enters the static mixer through the liquid phase outlet to participate in the crystallization process.

10. The suspension crystallization method according to claim 9, characterized in that: The crystallization temperature and cooling rate are controlled by adjusting the temperature and amount of refrigerant added.

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