Washing apparatus and method for crystalline products

Abstract

The present application relates to the technical field of separation and purification, and particularly relates to a washing device and a washing method for crystalline products. In the direction of material flow, the device comprises: a washer for washing the crude crystal product with washing liquid to obtain solid-phase crystals and washing filtrate; a melter comprising a melting zone for melting the solid-phase crystals and at least one clarification zone for collecting the molten liquid phase from the melting zone; wherein the outlet of the clarification zone is provided with at least three pipelines: at least one pipeline is in circulation communication with the melting zone, and each of the pipelines is provided with a heat exchanger, and the outlet of the heat exchanger is branched into at least one bypass pipeline which is in circulation communication with the inlet of the washer; at least one pipeline is in circulation communication with the inlet of the washer; and at least one pipeline is used to lead out the target product. The washing device can realize low energy consumption in the washing process, and has the advantages of simple washing method.

Description

Technical Field

[0001] This invention relates to the field of separation and purification technology, and specifically to a washing apparatus and washing method for crystalline products. Background Technology

[0002] In industries such as chemical, food, and pharmaceutical, cooling crystallization is a very common separation and purification method. Unlike solvent crystallization, which requires the addition of a third substance to change the solubility of the target product and thus achieve the precipitation of the target product from the solution by cooling, melt crystallization does not require the introduction of a third substance. It separates and purifies the components solely based on the difference in melting points. Therefore, it has the advantages of simple process steps, high product purity, and low energy consumption.

[0003] Depending on the crystal formation state, melt crystallization is divided into suspension crystallization and layered crystallization. In the former, the crystals are suspended in a granular state within the raw material, while in the latter, they adhere to the heat exchange interface and grow gradually along it. Each has its own applicable systems and fields of study. For suspension crystallization, solid-liquid separation is required through filtration or centrifugation to obtain the crystal product. Furthermore, since the crystal growth process inevitably involves the inclusion of mother liquor rich in impurities, when high purity is required, the coarse crystals after solid-liquid separation often need to be washed to obtain a qualified target product.

[0004] The washing process requires the use of a washing solution. When a substance other than the target product is used as the washing solution (such as toluene used as the washing solution in the early PX crystallization separation process), additional separation methods are needed to separate the washing solution from the crystal system for recycling, which complicates the process and increases energy consumption. Therefore, in the improved crystallization process, the molten target product is often used directly as the washing solution.

[0005] During the washing process, if the temperature of the washing solution is too high or the amount used is too large, it is easy to cause melting loss of the crystalline product; if the temperature of the washing solution is too low or the amount used is too small, it is difficult to achieve the washing effect and the product purity is low. Therefore, in order to ensure the washing effect, it is necessary to strictly control the temperature and amount of the washing solution.

[0006] CN101941882B proposes a method for separating para-xylene from mixed xylenes. In this method, the solid crystals after crystallization and solid-liquid separation are melted after heat exchange; a portion is returned as a washing liquid, and the remainder is sent to a product tank as para-xylene. However, this method requires melting all the crystals to the temperature required for the washing liquid, resulting in high energy consumption.

[0007] CN116768172A proposes a wet-process phosphoric acid suspension crystallization purification process. In this process, the phosphoric acid crystals obtained after crystallization, solid-liquid separation, and washing are completely melted in a melting tank. A portion of the crystals is first cooled and returned to the solid-liquid separator as washing liquid, while the remainder is collected as the phosphoric acid product. This process requires not only a large amount of heat to melt all the phosphoric acid crystals in the melting tank and raise its temperature above the washing liquid temperature, but also additional cooling to lower the washing liquid to the temperature required for washing the crystals, resulting in energy waste. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem of high energy consumption in the washing process of existing crystallization technologies, and to provide a washing device and method for crystallized products. This washing device achieves the advantages of low energy consumption and a simple washing method.

[0009] To achieve the above objectives, a first aspect of the present invention provides a washing apparatus for crystalline products. Along the material flow direction, the apparatus includes: a washer for washing coarse crystalline products with a washing liquid to obtain solid-phase crystals and washing filtrate; a melter comprising a melting zone for melting the solid-phase crystals and at least one clarification zone for receiving the molten liquid phase extracted from the melting zone; wherein the outlet of the clarification zone is provided with at least three pipelines: at least one pipeline is circulatedly connected to the melting zone, and each pipeline is equipped with a heat exchanger, with at least one bypass branching off from the heat exchanger outlet and circulatedly connected to the inlet of the washer; at least one pipeline is circulatedly connected to the inlet of the washer; and at least one pipeline is used to draw out the target product.

[0010] The second aspect of the present invention provides a washing method for a crystalline product, which is carried out in the apparatus described in the first aspect of the present invention. The washing method includes: (1) washing the coarse crystalline product in a washer with a washing liquid to obtain a solid crystal and a washing filtrate; (2) the solid crystal enters the melting zone of a melter, and overflows to the clarification zone of the melter after melting; wherein the molten liquid phase in the clarification zone is divided into at least three parts: at least one part of the liquid phase is heated by a heat exchanger to obtain a heated liquid phase, a portion of the heated liquid phase enters the washer through a bypass, and the remaining part is recycled back to the melting zone of the melter; at least one part of the liquid phase directly enters the washer and, together with the portion of the heated liquid phase, is returned to step (1) as a washing liquid; at least one part of the liquid phase is drawn out as the target product.

[0011] Compared with the prior art, the present invention has at least the following beneficial effects:

[0012] (1) The washing device of the present invention is connected to the melting zone through at least one pipeline, and each pipeline is provided with a heat exchanger. At least one bypass branch is branched off from the outlet of the heat exchanger and connected to the inlet of the washing device. At the same time, the connection between at least one pipeline and the inlet of the washing device can significantly reduce the heat required for solid crystal melting and heating when using the washing device of the present invention for crystallization washing. It can also reduce the energy consumption of the product pump and the heat required in the heat exchanger, that is, it can better reduce energy consumption and save costs.

[0013] (2) In the device of the present invention, at least one bypass is branched off from the heat exchanger outlet and circulated through the inlet of the scrubber to ensure the temperature of the washing liquid. The amount of washing liquid is controlled by the pipeline circulated through the inlet of the scrubber in the clarification zone. This can better ensure the washing effect of the coarse crystal product in the scrubber, and thus ensure the purity of the target product drawn out from the product melt. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the melt in a preferred embodiment of the present invention;

[0015] Figure 2 This is a schematic flowchart of a washing method in one embodiment of the present invention;

[0016] Figure 3 This is a schematic flowchart of a washing method in one embodiment of the present invention;

[0017] Figure 4 This is a schematic flowchart of the washing method in some comparative examples of the present invention;

[0018] Figure 5 This is a schematic flowchart of the washing method in some comparative examples of the present invention.

[0019] Explanation of reference numerals in the attached figures

[0020] 1. Cylinder body; 2. Baffle; 3. Molten zone solid crystal inlet.

[0021] 4. Molten liquid phase outlet; 5. Liquid level gauge port; 6. Molten zone liquid phase inlet.

[0022] I. Melting Zone II. Refining Zone II-1. First Refining Zone

[0023] II-2 Second Clarification Zone 101 Suspension Crystal Slurry 102 Crystallization Mother Liquor

[0024] 103 Washing liquid 104 Washing filtrate 105 Solid crystals

[0025] 106 Molten liquid phase 107 First part of liquid phase 108 Hydrothermal phase

[0026] 108-1 Main flow liquid phase; 108-2 Bypass liquid phase; 109 Second part liquid phase

[0027] 110 Part 3 Liquid Phase 201 Heat Exchange Medium 202 Cooling Medium

[0028] C101 Washer, P101 First Product Pump, P102 Second Product Pump

[0029] D101 Melter, E101 Heat Exchanger, E102 Cooler Detailed Implementation

[0030] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0031] The first aspect of the present invention provides a washing apparatus for crystalline products along the material flow direction. The apparatus includes: a washer for washing coarse crystalline products with a washing liquid to obtain solid crystals and washing filtrate; a melter for melting the solid crystals and at least one clarification zone for receiving the molten liquid phase extracted from the melter; wherein the outlet of the clarification zone is provided with at least three pipelines: at least one pipeline is circulatedly connected to the melter, and each pipeline is provided with a heat exchanger, and at least one bypass branch from the outlet of the heat exchanger is circulatedly connected to the inlet of the washer; at least one pipeline is circulatedly connected to the inlet of the washer; and at least one pipeline is used to draw out the target product.

[0032] In the device of this invention, at least one pipeline is circulatedly connected to the melting zone, and each pipeline is equipped with a heat exchanger. At least one bypass branch from the heat exchanger outlet is circulatedly connected to the inlet of the scrubber. The fact that at least one pipeline is circulatedly connected to the inlet of the scrubber allows the device of this invention to control the temperature of the liquid phase entering the melting zone as low as possible, that is, slightly higher than the melting point of the target product, without affecting the material conveying, rather than all liquid phases reaching the washing liquid temperature required for solid crystal washing. Therefore, the heat required for heating the solid crystal melting can be significantly reduced, thus reducing energy consumption. On the other hand, the temperature of the washing liquid can be controlled by the amount of liquid phase in the bypass, and the amount of washing liquid can be controlled by the amount of liquid phase circulating through the pipeline connected to the inlet of the scrubber via the clarification zone. This ensures the washing effect of the coarse crystal product in the scrubber, and thus ensures the product purity of the target product in the product melter.

[0033] According to a preferred embodiment of the present invention, the heat exchanger outlet is equipped with a temperature monitoring device, and the temperature monitoring device is cascaded with valves on the pipeline circulating between the clarification zone and the melting zone to control the liquid phase temperature at the heat exchanger outlet. This embodiment allows the washing device of the present invention to control the temperature of the heat exchanger within a suitable range as needed, and then adjust the liquid phase temperature at the heat exchanger outlet according to the amount of liquid phase entering the heat exchanger. Simultaneously, when the temperature monitoring device of the washing device or the temperature monitoring device at the heat exchanger outlet is disturbed, a steady state can be restored through rapid adjustment of the heat exchange medium passing through the heat exchanger, thereby avoiding the need for repeated adjustments between the regulating valves to achieve the final control result, significantly improving control efficiency. Furthermore, it ensures that all solid crystals in the melting zone melt during use of the device of the present invention, and avoids the vaporization of the first liquid phase when the heat exchanger has excessive heat exchange, thus ensuring the stable operation of the product washing process and avoiding energy waste.

[0034] According to a preferred embodiment of the present invention, the inlet of the scrubber is equipped with a temperature monitoring device, and the temperature monitoring device is cascaded with a valve on a bypass connecting the heat exchanger outlet and the scrubber to control the temperature of the washing liquid in the scrubber. The aforementioned embodiment enables the scrubbing device of the present invention to reduce the flow rate and temperature of the liquid phase entering the melt during use, thereby reducing the energy consumption of the corresponding liquid phase conveying product pump and the heat consumption of the heat exchanger, resulting in greater energy efficiency. Simultaneously, it can also reduce the amount of heat exchange medium used in the product heat exchanger, especially the amount of external heat exchange medium, reducing material consumption and saving costs.

[0035] According to a preferred embodiment of the present invention, the inlet of the washing liquid is equipped with a flow monitoring device, and the flow monitoring device is cascaded with valves on the pipeline circulating between the clarification zone and the washer to control the amount of washing liquid used in the washer. The aforementioned embodiment enables the device of the present invention to better ensure the washing effect during use, thereby ensuring the purity of the target product.

[0036] According to the present invention, as long as the purpose of the present invention can be achieved, at least three pipelines can be provided at the outlet of the clarification zone as needed. In a preferred embodiment, the outlet of the clarification zone is provided with three pipelines, and each clarification zone outlet is provided with at least one pipeline; one pipeline is in cyclic communication with the melting zone and is provided with a heat exchanger; one pipeline is in cyclic communication with the inlet of the scrubber; and one pipeline is used to lead out the target product.

[0037] According to the present invention, as long as the purpose of the present invention can be achieved, at least one pipeline can be branched off from the heat exchanger outlet and enter the melting zone from the top or bottom of the melting zone of the melter. Preferably, multiple inlets at the top or bottom of the melting zone can be dispersed to enter the melting zone. More preferably, multiple inlets at the top or bottom of the melting zone can be dispersed to enter the melting zone, thereby improving the dispersion and uniformity of coarse grain melting in the melting zone of the melter and shortening the coarse grain melting time.

[0038] According to the present invention, at least one bypass can be branched off from the heat exchanger outlet and circulated in connection with the inlet of the scrubber. In a preferred embodiment, the bypass branched off from the heat exchanger outlet is circulated in connection with the inlet of the scrubber.

[0039] The clarifying zone in this invention is used to receive the molten liquid phase from the melting zone. This invention does not limit the number of clarifying zones, for example, 1, 2, 3, etc. In one embodiment, the clarifying zone is 1 or 2.

[0040] The clarifying zone can be located on one or both sides of the melting zone. For example, when there are two clarifying zones, the two clarifying zones are located on both sides of the melting zone.

[0041] According to the present invention, in order to ensure that the molten crystals do not affect the liquid phase, the molten zone and the clarifying zone are separated by a baffle. To further improve the separation effect, the baffle is not perforated. The height of the baffle can be selected as needed in the present invention, and the device of the present invention has no special restrictions on this. Preferably, the height of the baffle is 1 / 3 to 3 / 5 of the height of the melter.

[0042] The scrubber in this invention can be any solid-liquid separation device in the art capable of solid-liquid separation, such as a centrifuge, pressure filter, vacuum filter, or scrubbing tower.

[0043] The heat exchanger in this invention can be any type of indirect heat exchanger with a shell and tube layers, such as a plate heat exchanger, a tube heat exchanger, a shell-and-tube heat exchanger, etc.

[0044] According to the present invention, the heat exchanger is used as a heater.

[0045] In this invention, corresponding inlets, outlets, or monitoring ports can be provided on the scrubber and melter as needed. For example, to introduce the circulating liquid phase of the solid crystal, a solid crystal inlet and a liquid phase inlet are provided in the melting zone of the melter. The solid crystal inlet and the liquid phase inlet can be the same or different ports as needed. To better melt the solid crystal, there can be one or multiple liquid phase inlets evenly arranged. To better monitor the liquid level, a level gauge port is provided in the clarification zone of the melter. To extract the liquid phase from the melting zone, a liquid phase outlet is provided in the clarification zone of the melter. When there are two or more clarification zones, liquid phase outlets can be provided in each clarification zone.

[0046] According to the present invention, the melt structure described as an exemplary embodiment is as follows: Figure 1 As shown, Figure 1 (a), (b), (c), and (d) are schematic diagrams of the melt in different embodiments.

[0047] Figure 1 In (a), the melter includes a cylinder 1, which is divided into a melting zone I and a clarifying zone II by a baffle 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are the same inlet. The clarifying zone II is provided with a level gauge port 5 and a liquid phase outlet 4.

[0048] Figure 1 In (b), the melter includes a cylinder 1, which is divided into a melting zone I, a first clarification zone II-1 and a second clarification zone II-2 by two baffles 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are the same inlet. The first clarification zone II-1 and the second clarification zone II-2 are each provided with a level gauge port 5 and a liquid phase outlet 4.

[0049] Figure 1 In (c), the melter includes a cylinder 1, and the inside of the cylinder 1 is divided into a melting zone I and a clarifying zone II by a baffle 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are different ports. The clarifying zone II is provided with a level gauge port 5 and a liquid phase outlet 4.

[0050] Figure 1In (d), the melter includes a cylinder 1. The interior of the cylinder 1 is divided into a melting zone I and a clarifying zone II by a baffle 2. The melting zone I has a melting zone solid crystal inlet 3 at the top and three melting zone liquid phase inlets 6 at the bottom that are evenly distributed. The clarifying zone II has a liquid level gauge port 5 and a melting liquid phase outlet 4.

[0051] In the apparatus of the present invention, without departing from the purpose of the present invention, in order to achieve temperature and flow monitoring and control, flow monitoring devices, temperature monitoring devices, flow regulating valves, etc. can be installed at the inlet or outlet of each device or on each connecting pipeline as needed. Each inlet and outlet can be directly connected by pipelines, or cross-connected, or divided into multiple branch pipelines through one pipeline and connected separately. In the apparatus of the present invention, in order to better draw out or draw out each stream of material, pumps can be installed on the pipeline as needed.

[0052] The second aspect of the present invention provides a washing method for a crystalline product, which is carried out in the apparatus described in the first aspect of the present invention. The washing method includes: (1) washing the coarse crystalline product in a washer with a washing liquid to obtain a solid crystal and a washing filtrate; (2) the solid crystal enters the melting zone of a melter, and overflows to the clarification zone of the melter after melting; wherein the molten liquid phase in the clarification zone is divided into at least three parts: at least one part of the liquid phase is heated by a heat exchanger to obtain a heated liquid phase, a portion of the heated liquid phase enters the washer through a bypass, and the remaining part is recycled back to the melting zone of the melter; at least one part of the liquid phase directly enters the washer and, together with the portion of the heated liquid phase, is returned to step (1) as a washing liquid; at least one part of the liquid phase is drawn out as the target product.

[0053] In the washing method of this invention, to ensure the melting of the solid crystal in the melter, the molten liquid phase in the melter is divided into at least three parts. At least one part of the liquid phase is heated to a significantly higher temperature. This part, along with at least one unheated part of the liquid phase, is used as the washing liquid. This allows the washing method of this invention to control the temperature of the liquid phase in the product melter as low as possible, i.e., slightly higher than the melting point of the target product, without affecting material conveying, rather than all liquid phases reaching the washing liquid temperature required for solid crystal washing. Therefore, the heat required for heating the solid crystal to melt can be significantly reduced, thus reducing energy consumption. Furthermore, since the temperature requirement in the melter can be reduced, the washing method of this invention can reduce the flow rate of the product circulating into the liquid phase in the melter, thereby reducing the energy consumption of the corresponding liquid phase conveying pump, making it more energy-efficient. At the same time, it can also reduce the amount of heat exchange medium used in the heat exchanger, especially the amount of heat exchange medium used outside the system, reducing material consumption and saving costs.

[0054] According to a preferred embodiment of the present invention, the liquid phase temperature at the heat exchanger outlet and the liquid phase flow rate entering the heat exchanger are controlled in cascade. When the liquid phase temperature at the heat exchanger outlet deviates from the control value, the liquid phase flow rate entering the heat exchanger is adjusted. In the aforementioned embodiment, the heat exchange medium in the heat exchanger can be kept constant, and the liquid phase temperature at the heat exchanger outlet can be controlled by adjusting the liquid phase flow rate entering the heat exchanger.

[0055] According to a particularly preferred embodiment of the present invention, the liquid phase temperature at the outlet of the heat exchanger is 30-85°C higher than the melting point of the target product, for example, 30°C, 40°C, 50°C, 65°C, 70°C, 75°C, 80°C, or 85°C, preferably 40-75°C. In the aforementioned embodiment, the low temperature requirement of the product melt reduces the energy of the liquid phase entering the melt and the energy consumption of the corresponding liquid phase transport pump, resulting in greater energy efficiency. It also reduces the amount of heat exchange medium used in the product heat exchanger, especially the amount of external heat exchange medium, thus reducing material consumption and saving costs.

[0056] According to a preferred embodiment of the present invention, the liquid phase flow rate entering the heat exchanger is 1.5-3 times the flow rate of the coarse-grained product, for example, 1.5 times, 1.8 times, 2 times, 2.3 times, 2.5 times, or 3 times.

[0057] In this invention, the temperature of the liquid phase in the clarification zone of the melt or the liquid phase at the outlet of the clarification zone of the melt can be controlled by first controlling the amount of liquid phase entering the heat exchanger, and then the temperature of the liquid phase at the outlet of the heat exchanger can be controlled by controlling the amount of liquid phase entering the heat exchanger.

[0058] According to the present invention, as long as the purpose of the present invention can be achieved, the position of the flow control valve of the heat exchange medium is not particularly limited, and it can be on the inlet pipe or the outlet pipe of the heat exchange medium in the heat exchanger.

[0059] According to the present invention, as long as the purpose of the present invention can be achieved, the source of the heat exchange medium in the heat exchanger is not particularly limited. In one embodiment, the heat exchange medium in the heat exchanger is the hot material of the upstream crystallization unit or other hot material outside the crystallization unit; in order to further reduce energy consumption, the heat exchange medium in the heat exchanger is the hot material of the upstream crystallization unit.

[0060] The coarse crystal product in this invention originates from the crystallization unit. During crystallization, the crystallization unit obtains a suspended crystal slurry containing the coarse crystal product, which can be separated into solid and liquid components to obtain the coarse crystal product. This solid-liquid separation step can be performed in the washer in this invention.

[0061] According to a preferred embodiment of the present invention, the flow rate in the bypass connecting the heat exchanger outlet to the scrubber is controlled to achieve control of the temperature of the scrubbing liquid in the scrubber. In the aforementioned embodiment, the temperature of the scrubbing liquid is achieved by controlling the amount of liquid phase that participates in the scrubbing process after at least a portion of the liquid phase in the melt is heated.

[0062] According to a particularly preferred embodiment of the present invention, the temperature of the washing liquid is controlled to be 10-30°C higher than the melting point of the target product, for example, 10°C, 12°C, 15°C, 16.5°C, 19°C, 21.5°C, 24°C, 27°C, or 30°C, preferably 13-25°C. The aforementioned embodiment further improves the purity of the target product and reduces energy consumption.

[0063] According to a preferred embodiment of the present invention, the amount of washing liquid used is controlled by controlling the liquid flow rate of the pipeline that is circulated between the clarification zone and the inlet of the scrubber.

[0064] In this invention, the washing effect is ensured by controlling the temperature and amount of the washing liquid, thereby ensuring the purity of the target product. Preferably, the liquid phase flow rate of the pipeline that enters the clarification zone and is circulated to the inlet of the washer is 0.15-0.35 times the flow rate of the coarse crystal product, for example, 0.15 times, 0.17 times, 0.22 times, 0.23 times, 0.24 times, 0.25 times, 0.27 times, 0.29 times, 0.3 times, and 0.35 times.

[0065] According to a preferred embodiment of the present invention, the outlet temperature of the melting tank is lower than the temperature of the washing liquid. By employing the aforementioned embodiment, energy consumption can be significantly reduced without affecting material transportation and the purity of the final product.

[0066] According to a preferred embodiment of the present invention, the outlet temperature of the melting tank is 5-25°C lower than the temperature of the washing liquid, for example, 5°C, 8°C, 10°C, 13°C, 15°C, 18°C, 20°C, 22°C, or 25°C, preferably 10-20°C. By employing the aforementioned embodiment, energy consumption can be significantly reduced without affecting material transportation and the purity of the final product.

[0067] According to the present invention, based on the liquid phase flow rate entering the heat exchanger, the proportion of liquid phase flow rate circulating back to the molten zone of the melt is 90-99%, for example, 90%, 92%, 94%, 96%, 97%, 98%, 99%, preferably 94-98%. By adopting the aforementioned embodiments, energy consumption can be significantly reduced without affecting material transportation and the purity of the final product.

[0068] According to the present invention, as long as the purpose of the present invention can be achieved, the flow rate of the target product is not particularly limited; it is only necessary to control the stability of the liquid level in the melting tank by controlling the flow rate of the target product.

[0069] According to a preferred embodiment of the present invention, the content of the target product in the coarse crystal is 95-99.5 wt%, preferably 97-99.5 wt%.

[0070] According to a preferred embodiment of the present invention, the target product in the coarse crystals is selected from aromatic compounds. The aromatic compounds are selected from substituted or unsubstituted benzenes and / or substituted or unsubstituted naphthalenes, preferably from alkyl or halogen-substituted benzenes and / or alkyl-substituted naphthalenes, such as p-xylene, 2,6-diisopropylnaphthalene, mesitylene, or p-dichlorobenzene.

[0071] According to a preferred embodiment of the present invention, this embodiment provides a method for washing a crystallized product, wherein the structure of the melter D101 in the method is as follows: Figure 1 As shown in (a), (b), (c) or (d), Figure 1 In (a), the melter includes a cylinder 1, and the inside of the cylinder 1 is divided into a melting zone I and a clarifying zone II by a baffle 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are the same inlet. The clarifying zone II is provided with a level gauge port 5 and a liquid phase outlet 4. Figure 1 In (b), the melter includes a cylinder 1, which is divided into a melting zone I, a first clarification zone II-1 and a second clarification zone II-2 by two baffles 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are the same inlet. The first clarification zone II-1 and the second clarification zone II-2 are each provided with a level gauge port 5 and a liquid phase outlet 4. Figure 1 In (c), the melter includes a cylinder 1, and the inside of the cylinder 1 is divided into a melting zone I and a clarifying zone II by a baffle 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are different ports. The clarifying zone II is provided with a level gauge port 5 and a liquid phase outlet 4. Figure 1 In (d), the melter includes a cylinder 1. The interior of the cylinder 1 is divided into a melting zone I and a clarifying zone II by a baffle 2. The melting zone I has a melting zone solid crystal inlet 3 at the top and three melting zone liquid phase inlets 6 at the bottom that are evenly distributed. The clarifying zone II has a liquid level gauge port 5 and a melting liquid phase outlet 4.

[0072] like Figure 1-3As shown, the washing method includes: a suspended crystal slurry 101 from the crystallization unit enters a washer C101 for solid-liquid separation to obtain a crystallization mother liquor 102 and a coarse crystal product. The crystallization mother liquor 102 is discharged from the washer C101, while the coarse crystal product remains in the washer C101 and is washed with washing liquid 103. After washing and solid-liquid separation, washing filtrate 104 and solid crystal 105 are obtained. The washing filtrate 104 is discharged from the washer C101, while the solid crystal 105 enters the melting zone I of the melter D101 from the liquid phase inlet of the melting zone. The melted liquid phase overflows through the baffle 2 inside the melter D101 to the clarification zone II on the other side (or the first clarification zone II-1 and the second clarification zone II-2 on both sides). The molten liquid phase 106 in the clarification zone II is collected by the first product pump P101 and divided into three parts: the first liquid phase 107, the second liquid phase 109, and the third liquid phase 100. 10 (or the liquid phase 106 of the first clarification zone II-1 is collected by the first product pump P101 as the first part of the liquid phase 107; the liquid phase 111 of the second clarification zone II-2 is collected by the second product pump P102 and divided into two parts, namely the second part of the liquid phase 109 and the third part of the liquid phase 110): The first part of the liquid phase 107 enters the heat exchanger E101, and the hot liquid phase 108 after being heated by the heating medium 201 is divided into two parts, one part is the main liquid phase 108-1, and the remaining part is the bypass liquid phase 108-2. The main liquid phase 108-1 is circulated back to the melting zone I of the product melter D101 to melt the solid crystal 105 from the scrubber C101. The bypass liquid phase 108-2 is mixed with the second part of the liquid phase 109 from the melter D101 as the washing liquid 103 of the scrubber C101; the third part of the liquid phase 110 is sent out as the final target product.

[0073] In the above method, the temperature of the washing liquid 103 is controlled by controlling the amount of material in the bypass liquid phase 108-2; the amount of washing liquid 103 used in the scrubber C101 is controlled by controlling the amount of material in the second liquid phase 109.

[0074] The liquid level in melter D101 is controlled by controlling the flow rate of the third liquid phase 110;

[0075] The temperature of the liquid phase in the clarification zone or the liquid phase at the outlet of the clarification zone in the melter D101 is controlled by controlling the amount of heat exchange medium 201 in the heat exchanger E101.

[0076] Meanwhile, the temperature of the thermal liquid phase 108 and the flow rate of the first liquid phase 107 are controlled in cascade.

[0077] The present invention will be described in detail below through embodiments.

[0078] The washing and crystallizing products in the following examples are prepared in accordance with... Figure 2 or Figure 3 The washing method process shown is carried out as follows. In the following embodiments, the structure of the melt is as follows: Figure 1 As shown in (a), (b), or (c).

[0079] Figure 1 In (a), the melter includes a cylinder 1, which is divided into a melting zone I and a clarifying zone II by a baffle 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are the same inlet. The clarifying zone II is provided with a level gauge port 5 and a liquid phase outlet 4.

[0080] Figure 1 In (b), the melter includes a cylinder 1, which is divided into a melting zone I, a first clarification zone II-1 and a second clarification zone II-2 by two baffles 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are the same inlet. The first clarification zone II-1 and the second clarification zone II-2 are each provided with a level gauge port 5 and a liquid phase outlet 4.

[0081] Figure 1 In (c), the melter includes a cylinder 1, and the inside of the cylinder 1 is divided into a melting zone I and a clarifying zone II by a baffle 2. The top of the melting zone I is provided with a solid crystal inlet 3 and a liquid phase inlet 6, wherein the solid crystal inlet 3 and the liquid phase inlet 6 are different ports. The clarifying zone II is provided with a level gauge port 5 and a liquid phase outlet 4.

[0082] Figure 1 In (d), the melter includes a cylinder 1. The interior of the cylinder 1 is divided into a melting zone I and a clarifying zone II by a baffle 2. The melting zone I has a melting zone solid crystal inlet 3 at the top and three melting zone liquid phase inlets 6 at the bottom that are evenly distributed. The clarifying zone II has a liquid level gauge port 5 and a melting liquid phase outlet 4.

[0083] like Figure 1-3As shown, the washing method includes: a suspended crystal slurry 101 from the crystallization unit enters a washer C101 for solid-liquid separation to obtain a crystallization mother liquor 102 and a coarse crystal product. The crystallization mother liquor 102 is discharged from the washer C101, while the coarse crystal product remains in the washer C101 and is washed with washing liquid 103. After washing and solid-liquid separation, washing filtrate 104 and solid crystal 105 are obtained. The washing filtrate 104 is discharged from the washer C101, while the solid crystal 105 enters the melting zone I of the melter D101 from the liquid phase inlet of the melting zone. The molten liquid phase overflows through the baffle 2 inside the melter D101 to the clarification zone II on the other side (or the first clarification zone II-1 and the second clarification zone II-2 on both sides). The molten liquid phase 106 in the clarification zone II is collected by the first product pump P101 and divided into three parts: the first liquid phase 107, the second liquid phase 109, and the third liquid phase 100. 10 (or the molten liquid phase 106 of the first clarification zone II-1 is collected by the first product pump P101 as the first part of the liquid phase 107; the liquid phase 111 of the second clarification zone II-2 is collected by the second product pump P102 and divided into two parts, namely the second part of the liquid phase 109 and the third part of the liquid phase 110): The first part of the liquid phase 107 enters the heat exchanger E101, and the hot liquid phase 108 after being heated by the heating medium 201 is divided into two parts, one part is the main liquid phase 108-1, and the remaining part is the bypass liquid phase 108-2. The main liquid phase 108-1 is circulated back to the melting zone I of the product melter D101 to melt the solid crystal 105 from the scrubber C101. The bypass liquid phase 108-2 is mixed with the second part of the liquid phase 109 from the melter D101 as the washing liquid 103 of the scrubber C101; the third part of the liquid phase 110 is sent out as the final target product.

[0084] In the above methods:

[0085] The temperature of the washing liquid 103 is controlled by controlling the amount of material in the bypass liquid phase 108-2; the amount of washing liquid 103 used in the scrubber C101 is controlled by controlling the amount of material in the second liquid phase 109.

[0086] The liquid level in melter D101 is controlled by controlling the flow rate of the third liquid phase 110;

[0087] The control of the liquid phase temperature in the clarification zone or the liquid phase temperature at the outlet of the clarification zone in the melter D101 is achieved by controlling the amount of heat exchange medium 201 in the heat exchanger E101.

[0088] Meanwhile, the temperature of the thermal liquid phase 108 and the flow rate of the first liquid phase 107 are controlled in cascade.

[0089] The following comparisons are based on Figure 4 The washing method shown is performed or followed. Figure 5The washing process shown is in progress:

[0090] Figure 4 In comparison Figure 1 The first part of the liquid phase 107 at the outlet of heat exchanger E101, after being heated by the heat exchanger, is completely circulated back to the melter D101 as the hot liquid phase 108. The washing liquid 103 in the scrubber C101 comes entirely from the second part of the liquid phase 109 at the outlet of the melter D101.

[0091] Figure 5 China: Compared to Figure 1 The molten liquid phase 106 is divided into two parts, namely the first liquid phase 107 and the third liquid phase 110. The hot liquid phase 108 at the outlet of heat exchanger E101 is divided into two parts. One part is the main liquid phase 108-1, which is circulated back to the melting zone I of the product melter D101. The remaining part, the bypass liquid phase 108-2, is cooled to the washing liquid temperature by cooler E102 and then used as washing liquid 103 to wash the solid crystals 105 in the washer C101. The temperature of the washing liquid 103 is achieved by controlling the flow rate of the cooling medium 202 in cooler E102.

[0092] The purity of the product was determined by gas chromatography.

[0093] Example 1

[0094] use Figure 1 In the melt shown in (a), the height of baffle 2 is 1 / 3 of the height of the melt cylinder 1;

[0095] The suspended crystal slurry 101 from the PX crystallization unit enters the scrubber C101 (a centrifuge); the crude crystal product (99.3% purity) after centrifugation is at a temperature of 8.5℃, and then... Figure 2 Wash according to the washing method and procedure shown;

[0096] The first part, liquid phase 107, has a mass flow rate 1.83 times that of the coarse crystal product in suspension slurry 101. It enters heat exchanger E101 and is heated using the high-temperature raw material of the PX crystallization unit itself as the heat exchange medium 201. The resulting hot liquid phase 108 has a temperature of 75°C. 97.02 wt% of the hot liquid phase 108 is used as the main liquid phase 108-1, entering from the connecting pipe between scrubber C101 and melter D101 and circulating back to the melting zone I of melter D101. The outlet temperature of melter D101 is 20°C. The remaining 2.98 wt% of the hot liquid phase 108 is used as the bypass liquid phase 108-2 and flows with the mass... The second liquid phase 109, with a flow rate 0.25 times that of the coarse crystal product, is mixed and used as the washing liquid 103 in the scrubber C101. At this time, the amount of washing liquid 103 is 30% of the mass of the coarse crystal product, and the temperature is 30℃. The energy consumption of the coarse crystal product under the heat exchanger E101 is 182.31KJ per unit mass flow rate. The liquid level of the melter D101 is monitored by the liquid level gauge at the liquid level gauge port 5. By controlling the flow rate of the third liquid phase 110 as the target, the total discharge flow rate of the first product pump P101 is 2.78 times the mass of the coarse crystal product. Finally, the purity of the third liquid phase 110 as the target product is 99.82%.

[0097] Comparative Example 1-1

[0098] The suspended crystal slurry 101 from the PX crystallization unit, similar to that in Example 1, enters the scrubber C101 (a centrifuge), except that:

[0099] use Figure 4 The washing method shown is used for washing. The circulating flow rate of the melt D101 is 2.22 times the mass flow rate of the coarse crystal product in the suspension slurry 101. It enters the heat exchanger E101 for heating. After heating, the temperature of the hot liquid phase 108 is 80°C, and the outlet temperature of the melt D101 is 30°C. The amount of washing liquid 103 is 30% of the mass of the coarse crystal product. At this time, the purity of the third liquid phase 110 as the target product is 99.82%. However, the energy consumption of the heat exchanger E101 per unit mass flow rate of coarse crystal product is 200.40 KJ, which is 9.92% higher than that of Example 1.

[0100] In addition, in Example 1, the total discharge flow rate of the first product pump P101 is 2.78 times the mass of the coarse crystal product, while in Comparative Example 1-1, under the same product yield, the total discharge flow rate of the first product pump P101 is 3.22 times the mass flow rate of the coarse crystal. At this time, the energy consumption of the product pump increases by 15.83% compared with Example 1.

[0101] Example 2

[0102] use Figure 1In the melt shown in (b), the height of baffle 2 is half the height of the melt cylinder 1;

[0103] The suspended crystal slurry 101 from the PX crystallization unit enters the scrubber C101 (a centrifuge); the crude crystal product (99.1% purity) after centrifugation is at a temperature of 7.5℃, and is then processed according to... Figure 2 The washing process shown is as follows: the first part, liquid phase 107, has a mass flow rate 2.03 times that of the coarse crystal product in suspension slurry 101. It enters heat exchanger E101 and is heated using the high-temperature raw material from the PX crystallization unit itself as the heat exchange medium 201. The resulting hot liquid phase 108 reaches 73°C. 96.24 wt% of the hot liquid phase 108 is used as the main liquid phase 108-1, flowing from the connecting pipe between the scrubber C101 and the melter D101 and circulating back to the melting zone I of the melter D101. The outlet temperature of the melter D101 is 22°C. The remaining 3.76 wt% of the hot liquid phase 108 is used as the bypass liquid phase 10. 8-2 The second liquid phase 109, with a mass flow rate 0.22 times that of the coarse crystal product in the slurry, is mixed as the washing liquid 103 in the scrubber C101. At this time, the amount of washing liquid 103 is 30% of the mass of the coarse crystal product, the temperature is 35℃, and the energy consumption of the coarse crystal product under the heat exchanger E101 per unit mass flow rate is 187.74KJ. The liquid level of the melter D101 is monitored by the liquid level gauge at the liquid level gauge port 5, and the total discharge flow rate of the first product pump P101 is 2.96 times the mass of the coarse crystal product by controlling the flow rate of the third liquid phase 110 as the target. Finally, the purity of the third liquid phase 110 as the target product is 99.84%.

[0104] Comparative Example 2-1

[0105] The suspended crystal slurry 101 from the PX crystallization unit, similar to that in Example 2, enters the scrubber C101 (a centrifuge), except that:

[0106] use Figure 4 The washing process shown is as follows: the circulating flow rate of the melt D101 is 2.60 times the mass flow rate of the coarse crystal product in the suspension slurry 101. It enters the heat exchanger E101 for heating. After heating, the temperature of the hot liquid phase 108 is 80°C, and the outlet temperature of the melt D101 is 35°C. The amount of washing liquid 103 is 30% of the mass of the coarse crystal product. At this time, the purity of the third liquid phase 110 as the target product is 99.84%. However, the energy consumption of the heat exchanger E101 per unit mass flow rate of coarse crystal product is 211.26 KJ, which is 12.53% higher than that of Example 2.

[0107] In addition, in Example 2, the total discharge flow rate of the first product pump P101 is 2.96 times the mass of the coarse crystal product, while in Comparative Example 2-1, under the same product yield, the total discharge flow rate of the first product pump P101 is 3.60 times the mass flow rate of the coarse crystal. At this time, the energy consumption of the product pump increases by 21.62% compared with Example 2.

[0108] Example 3

[0109] use Figure 1 The height of the baffle 2 in the melt shown in (c) is half the height of the melt body 1;

[0110] The suspended crystal slurry 101 from the PX crystallization unit enters the scrubber C101 (a pressure filter); the filtered coarse crystal product (98.9% purity) is at a temperature of 7°C, and then... Figure 3 The apparatus and method shown are used for washing.

[0111] The first part, liquid phase 107, has a mass flow rate 2.49 times that of the coarse crystal product in suspension slurry 101. It enters heat exchanger E101 and is heated using the high-temperature raw material of the PX crystallization unit itself as the heat exchange medium 201. The resulting hot liquid phase 108 reaches a temperature of 68°C. 96.74 wt% of the hot liquid phase 108 serves as the main liquid phase 108-1, flowing from the connecting pipe between scrubber C101 and melter D101 and circulating back to the melting zone I of melter D101. The outlet temperature of melter D101 is 25°C. The remaining 3.26 wt% of the hot liquid phase 108 serves as the bypass liquid phase 108-2, flowing with the coarse crystal product at a mass flow rate of... The second liquid phase 109 is mixed with 0.27 times the mass flow rate of the coarse crystal product and used as the washing liquid 103 in the scrubber C101. At this time, the amount of washing liquid 103 is 35% of the mass of the coarse crystal product, the temperature is 35℃, and the energy consumption of the heat exchanger E101 under the coarse crystal product per unit mass flow rate is 194.07KJ. The liquid level of the melt D101 is monitored by the liquid level gauge at the liquid level gauge port 5, and the total discharge flow rate of the first product pump P101 and the second product pump P102 is controlled by the third liquid phase 110 as the target so that it is 3.41 times the mass of the coarse crystal product. Finally, the purity of the third liquid phase 110 as the target product is 99.85%.

[0112] Comparative Example 3-1

[0113] Similar to Example 3, the suspended crystal slurry 101 from the PX crystallization unit enters the scrubber C101 (a pressure filter), except that:

[0114] use Figure 4The washing method shown is used for washing. The circulating flow rate of the melt D101 is 2.61 times the mass flow rate of the coarse crystal product in the suspension slurry 101. It enters the heat exchanger E101 for heating. After heating, the temperature of the hot liquid phase 108 is 80°C, and the outlet temperature of the melt D101 is 35°C. The amount of washing liquid 103 is 35% of the mass of the coarse crystal product. At this time, the purity of the third liquid phase 110 as the target product is 99.85%. However, the energy consumption of the heat exchanger E101 per unit mass flow rate of coarse crystal product is 212.16 KJ, which is 9.32% higher than that of Example 3.

[0115] In addition, in Example 3, the total discharge flow rate of the first product pump P101 and the second product pump P102 is 3.41 times the mass of the coarse crystal product. In Comparative Example 3-1, under the same product yield, the total discharge flow rate of the first product pump P101 is 3.61 times the mass flow rate of the coarse crystal. At this time, the energy consumption of the product pump increases by 5.87% compared with Example 3.

[0116] Example 4

[0117] use Figure 1 In the melt shown in (d), the height of baffle 2 is 3 / 5 of the height of the melt cylinder 1;

[0118] The suspended crystal slurry 101 from the PX crystallization unit enters the scrubber C101 (a vacuum filter); the crude crystal product after filtration (purity 98.7%) is at a temperature of 6.5℃, and then... Figure 3 The washing process shown is as follows:

[0119] The first part, liquid phase 107, has a mass flow rate 1.56 times that of the coarse-grained product in suspension slurry 101. It enters heat exchanger E101 and is heated using steam. The resulting hot liquid phase 108 has a temperature of 86°C. 94.89 wt% of the hot liquid phase 108 is used as the main liquid phase 108-1, flowing from the connecting pipe between scrubber C101 and melter D101 and circulating back to the melting zone I of melter D101. The outlet temperature of melter D101 is 20°C. The remaining 5.11 wt% of the hot liquid phase 108 is used as bypass liquid phase 108-2, flowing with the coarse-grained product at a mass flow rate of 0. The second part of liquid phase 109, which is 27 times larger than the first part, is mixed as the washing liquid 103 in the scrubber C101. At this time, the amount of washing liquid 103 is 35% of the mass of the coarse crystal product, and the temperature is 35°C. The energy consumption of the heat exchanger E101 under the coarse crystal product per unit mass flow rate is 185.93 KJ. The liquid level of the melt D101 is monitored by the liquid level gauge at the liquid level gauge port 5. By controlling the flow rate of the third part of liquid phase 110 as the target, the total discharge flow rate of the first product pump P101 and the second product pump P102 is 2.48 times the crystal mass flow rate. Finally, the purity of the third part of liquid phase 110 as the target product is 99.84%.

[0120] Comparative Example 4-1

[0121] Similar to Example 4, the suspended crystal slurry 101 from the PX crystallization unit enters the scrubber C101 (a vacuum filter), except that:

[0122] use Figure 4 The washing method shown is used for washing. The circulating flow rate of the melt D101 is 2.07 times the mass flow rate of the coarse crystal product in the suspension slurry 101. It enters the heat exchanger E101 for heating. After heating, the temperature of the hot liquid phase 108 is 92°C, and the outlet temperature of the melt D101 is 35°C. The amount of washing liquid 103 is 35% of the mass of the coarse crystal product. At this time, the purity of the third liquid phase 110 as the target product is 99.84%. However, the energy consumption of the heat exchanger E101 per unit mass flow rate of coarse crystal product is 213.06 KJ, which is 14.59% higher than that of Example 3.

[0123] In addition, in Example 4, the total discharge flow rate of the first product pump P101 and the second product pump P102 is 2.48 times the mass of the coarse crystal product. In Comparative Example 4-1, under the same product yield, the total discharge flow rate of the first product pump P101 is 3.07 times the mass flow rate of the coarse crystal. At this time, the energy consumption of the product pump increases by 23.79% compared with Example 4.

[0124] Comparative Example 4-2

[0125] Similar to Example 4, the suspended crystal slurry 101 from the PX crystallization unit enters the scrubber C101 (a vacuum filter), except that:

[0126] use Figure 5 The washing process shown is as follows: the circulating flow rate of the melt D101 is 1.87 times the mass flow rate of the coarse-grained product in the suspension slurry 101, and then it enters the heat exchanger E101 for heating. The temperature of the heated liquid phase 108 is 75°C.

[0127] Of the 108 phase, 84.23 wt% of the hydrothermal phase 108 is used as the main liquid phase 108-1, which enters from the connecting pipe between the scrubber C101 and the melter D101 and circulates back to the melting zone I of the melter D101. The remaining 15.77 wt% is used as the bypass liquid phase 108-2 and enters the cooler E102. After being cooled to 35°C in E102, it enters the scrubber C101 as the washing liquid 103 of the coarse-grained product. The amount of washing liquid 103 used is 35% of the mass of the coarse-grained product. The outlet temperature of the product melter D101 is 20°C. At this time, the total energy consumption of the heat exchanger D101 and the cooler E102 under the unit mass flow rate of coarse-grained product is 213.06 KJ, which is 14.59% higher than that of Example 4.

[0128] In addition, under the same product yield, the total discharge flow rate of the first product pump P101 in Comparative Example 4-2 is 2.87 times the crystal mass flow rate, which is 15.73% higher than the total discharge flow rate of the first product pump P101 and the second product pump P102 in Example 4.

[0129] Example 5

[0130] use Figure 1 In the melt shown in (a), the height of baffle 2 is 1 / 3 of the height of the melt cylinder 1;

[0131] The suspension slurry 101 from the 2,6-diisopropylnaphthalene crystallization unit enters the scrubber C101 (a vacuum filter); the filtered coarse crystal product (purity 97.5%) is heated to 60°C and then... Figure 2 The washing process shown is as follows:

[0132] The first part, liquid phase 107, has a mass flow rate 2.42 times that of the coarse crystal product in the suspension slurry 101. It enters heat exchanger E101 and is heated using the high-temperature raw material from the 2,6-diisopropylnaphthalene crystallization unit itself as the heat exchange medium 201. The resulting hydrothermal phase 108 reaches a temperature of 120°C. 96.90 wt% of the hydrothermal phase 108 is used as the main liquid phase 108-1, flowing from the connecting pipe between scrubber C101 and melter D101 and circulating back to the melting zone I of melter D101. The outlet temperature of melter D101 is 80°C. The remaining 3.10 wt% of the hydrothermal phase 108 is used as the bypass liquid phase 108-. 2. The second liquid phase 109, with a mass flow rate 0.23 times that of the coarse crystal product, is mixed with the second liquid phase 109 to form the washing liquid 103 of the scrubber C101. At this time, the amount of washing liquid 103 is 30% of the mass of the coarse crystal product, the temperature is 90℃, and the energy consumption of the heat exchanger E101 per unit mass flow rate of the coarse crystal product is 136.53KJ. The liquid level of the melt D101 is monitored by the liquid level gauge at the liquid level gauge port 5, and the total discharge flow rate of the first product pump P101 is 3.34 times the mass of the coarse crystal product by controlling the flow rate of the third liquid phase 110 as the target. Finally, the purity of the third liquid phase 110 as the target product is 99.56%.

[0133] Comparative Example 5-1

[0134] The suspension slurry 101 from the 2,6-diisopropylnaphthalene crystallization unit, similar to that in Example 5, enters the scrubber C101 (a vacuum filter), except that:

[0135] according to Figure 4 The washing method shown is used for washing. The circulating flow rate of the melt D101 is 3.55 times the mass flow rate of the coarse crystal product in the suspension slurry 101. It enters the heat exchanger E101 for heating. After heating, the temperature of the hot liquid phase 108 is 120°C, and the outlet temperature of the melt D101 is 90°C. The amount of washing liquid 103 is 30% of the mass of the coarse crystal product. At this time, the purity of the third liquid phase 110 as the target product is 99.56%. However, the energy consumption of the heat exchanger E101 per unit mass flow rate of coarse crystal product is 150.66 KJ, which is 10.35% higher than that of Example 1.

[0136] In addition, in Example 5, the total discharge flow rate of the first product pump P101 is 3.34 times the mass of the coarse crystal product, while in Comparative Example 5-1, under the same product yield, the total discharge flow rate of the first product pump P101 is 4.55 times the mass flow rate of the coarse crystal. At this time, the energy consumption of the product pump increases by 36.23% compared with Example 1.

[0137] Example 6

[0138] use Figure 1In the melt shown in (a), the height of baffle 2 is 1 / 3 of the height of the melt cylinder 1;

[0139] The suspended crystal slurry 101 from the p-dichlorobenzene crystallization unit enters the scrubber C101 (a centrifuge); the coarse crystal product (99% purity) after centrifugation is at a temperature of 48°C, and then... Figure 2 The washing process shown is as follows: the first part, liquid phase 107, has a mass flow rate 2.33 times that of the coarse crystal product in the suspension slurry 101. It enters heat exchanger E101 and is heated using the high-temperature raw material of the dichlorobenzene crystallization unit itself as the heat exchange medium 201. The resulting hot liquid phase 108 reaches a temperature of 95°C. 94.49 wt% of the hot liquid phase 108 is used as the main liquid phase 108-1, entering from the connecting pipe between the scrubber C101 and the melter D101 and circulating back to the melting zone I of the melter D101. The outlet temperature of the melter D101 is 60°C. The remaining 5.51 wt% of the hot liquid phase 108 is used as the bypass liquid phase. 108-2 is mixed with the second liquid phase 109, whose mass flow rate is 0.17 times that of the coarse crystal product, to form the washing liquid 103 of the scrubber C101. At this time, the amount of washing liquid 103 is 30% of the mass of the coarse crystal product, the temperature is 75℃, and the energy consumption of the heat exchanger E101 under the coarse crystal product per unit mass flow rate is 159.48KJ. The liquid level of the melt D101 is monitored by the liquid level gauge at the liquid level gauge port 5, and the total discharge flow rate of the first product pump P101 is 3.21 times the mass of the coarse crystal product by controlling the flow rate of the third liquid phase 110 as the target. Finally, the purity of the third liquid phase 110 as the target product is 99.90%.

[0140] Comparative Example 6-1

[0141] The suspended crystal slurry 101 from the p-dichlorobenzene crystallization unit, similar to that in Example 6, enters the scrubber C101 (a centrifuge), except that:

[0142] according to Figure 4 The washing process shown is as follows: the circulating flow rate of the melt D101 is 3.87 times the mass flow rate of the coarse crystal product in the suspension slurry 101. It enters the heat exchanger E101 for heating. After heating, the temperature of the hot liquid phase 108 is 100°C, and the outlet temperature of the melt D101 is 75°C. The amount of washing liquid 103 is 30% of the mass of the coarse crystal product. At this time, the purity of the third liquid phase 110 as the target product is 99.90%. However, the energy consumption of the heat exchanger E101 per unit mass flow rate of coarse crystal product is 188.77 KJ, which is 18.37% higher than that of Example 6.

[0143] In addition, in Example 6, the total discharge flow rate of the first product pump P101 is 3.21 times the mass of the coarse crystal product, while in Comparative Example 6-1, under the same product yield, the total discharge flow rate of the first product pump P101 is 4.87 times the mass flow rate of the coarse crystal. At this time, the energy consumption of the product pump increases by 51.71% compared with Example 1.

[0144] Example 7

[0145] use Figure 1 In the melt shown in (a), the height of baffle 2 is 1 / 3 of the height of the melt cylinder 1;

[0146] The suspended crystal slurry 101 from the mesitylene crystallization unit enters the scrubber C101 (a pressure filter); the filtered coarse crystal product (98% purity) is at a temperature of 72°C, and then... Figure 2 The washing process shown is as follows: the first part, liquid phase 107, has a mass flow rate 2.06 times that of the coarse crystal product in the suspension slurry 101. It enters heat exchanger E101 and is heated using the high-temperature raw material from the mesitylene crystallization unit itself as the heat exchange medium 201. The resulting hot liquid phase 108 reaches a temperature of 130°C. 96.53 wt% of the hot liquid phase 108 is used as the main liquid phase 108-1, flowing from the connecting pipe between the scrubber C101 and the melter D101 and circulating back to the melting zone I of the melter D101. The outlet temperature of the melter D101 is 88°C. The remaining 3.47 wt% of the hot liquid phase 108 is used as a bypass liquid. Phase 108-2 is mixed with the second liquid phase 109, whose mass flow rate is 0.24 times that of the coarse crystal product, to form the washing liquid 103 of the scrubber C101. At this time, the amount of washing liquid 103 is 30% of the mass of the coarse crystal product, the temperature is 98℃, and the energy consumption of the heat exchanger E101 under the coarse crystal product per unit mass flow rate is 173.77KJ. The liquid level of the melt D101 is monitored by the liquid level gauge at the liquid level gauge port 5, and the total discharge flow rate of the first product pump P101 is 2.99 times the mass of the coarse crystal product by controlling the flow rate of the third liquid phase 110 as the target. Finally, the purity of the third liquid phase 110 as the target product is 99.71%.

[0147] Comparative Example 7-1

[0148] The suspended crystal slurry 101 from the p-dichlorobenzene crystallization unit, similar to that in Example 7, enters the scrubber C101 (a pressure filter), except that:

[0149] according to Figure 4The washing process shown is as follows: the circulating flow rate of the melt D101 is 2.60 times the mass flow rate of the coarse crystal product in the suspension slurry 101. The product enters the heat exchanger E101 for heating. After heating, the temperature of the hot liquid phase 108 is 135°C, and the outlet temperature of the melt D101 is 98°C. The amount of washing liquid 103 is 30% of the mass of the coarse crystal product. At this time, the purity of the third liquid phase 110 as the target product is 99.71%. However, the energy consumption of the heat exchanger E101 per unit mass flow rate of coarse crystal product is 193.89 KJ, which is an increase of 11.58% compared to Example 7.

[0150] In addition, in Example 7, the total discharge flow rate of the first product pump P101 is 2.99 times the mass of the coarse crystal product, while in Comparative Example 7-1, under the same product yield, the total discharge flow rate of the first product pump P101 is 3.60 times the mass flow rate of the coarse crystal. At this time, the energy consumption of the product pump increases by 20.40% compared with Example 1.

[0151] Example 8

[0152] The suspension slurry 101 from the PX crystallization unit, identical to that in Example 1, enters the scrubber C101 (a centrifuge). Following the method and process parameters of Example 1, the mass flow rate of the first liquid phase 107 remains 1.83 times that of the coarse crystal product in the suspension slurry 101. The difference is that 90 wt% of the hydrothermal phase 108 is used as the main liquid phase 108-1, entering from the connecting pipe between the scrubber C101 and the melter D101 and circulating back to the melting zone I of the melter D101. The remaining... 10 wt% of the thermal liquid phase 108 is used as bypass liquid phase 108-2 and mixed with the second liquid phase 109, whose mass flow rate is 0.25 times that of the coarse crystal product, as the washing liquid 103 of the scrubber C101. At this time, the amount of washing liquid 103 is 42.9% of the mass of the coarse crystal product, and the temperature is 46.1℃. Although the purity of the final third liquid phase 110 as the target product is 99.90%, the energy consumption of heat exchanger E101 under the unit mass flow rate of coarse crystal product is 202.57 KJ.

[0153] In addition, the total discharge flow rate of the first product pump P101 is 2.48 times the mass of the coarse crystal product. The reason for the decrease in flow rate is that the washing liquid temperature is too high and the amount used is too large, resulting in more coarse crystals melting. The mass flow rate of the third liquid phase 110 as the target product is 0.25 times the mass of the coarse crystal, which is 64.29% lower than the 0.7 times the mass of the coarse crystal in Example 1. That is, the yield of the target product is reduced by 64.29%.

[0154] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A washing apparatus for crystallized products, characterized in that, Along the material flow direction, the device includes: Washer: Used to wash coarse crystal products with washing liquid to obtain solid crystals and washing filtrate; Melter: The interior includes a melting zone for melting solid crystals and at least one clarifying zone for receiving the molten liquid phase extracted from the melting zone; The clarification zone outlet is equipped with at least three pipelines: At least one pipeline is circulated in connection with the molten zone, and each pipeline is equipped with a heat exchanger. At least one bypass branch is branched off from the outlet of the heat exchanger and circulated in connection with the inlet of the scrubber. At least one pipe is connected to the inlet of the washer in a loop; At least one pipeline is used to lead out the target product.

2. The washing device according to claim 1, wherein, The heat exchanger outlet is equipped with a temperature monitoring device, and this temperature monitoring device is cascaded with valves on the pipeline that circulates between the clarification zone and the molten zone to control the liquid phase temperature at the heat exchanger outlet; and / or The inlet of the washer is equipped with a temperature monitoring device, and the temperature monitoring device is cascaded with the valve on the bypass line that is connected to the outlet of the heat exchanger and the washer to control the temperature of the washing liquid in the washer. and / or The inlet of the washing liquid is equipped with a flow monitoring device, and the flow monitoring device is cascaded with the valves on the pipeline that is in circulation between the clarification zone and the washing machine to control the amount of washing liquid used in the washing machine.

3. The washing apparatus according to claim 1 or 2, wherein, The clarification zone outlet is provided with three pipelines, with at least one pipeline at the outlet of each clarification zone; one pipeline is in cyclic communication with the melting zone and is equipped with a heat exchanger; one pipeline is in cyclic communication with the inlet of the scrubber; and one pipeline is used to draw out the target product; and / or At least one pipeline branches off from the heat exchanger outlet and enters the molten zone from the top or bottom of the molten zone; preferably, it enters from multiple inlets at the top or bottom of the molten zone; more preferably, it enters from multiple inlets with a uniform geometric arrangement at the top or bottom of the molten zone. and / or A bypass branch off from the heat exchanger outlet is connected in a loop to the inlet of the scrubber.

4. The washing apparatus according to any one of claims 1-3, wherein, The clarification zone may be one or two; and / or The melting zone and the refining zone are separated by a baffle, preferably with a height of 1 / 3 to 3 / 5 of the height of the melter; and / or The scrubber is a solid-liquid separation device; and / or The heat exchanger is a partition wall type heat exchanger.

5. A method for washing a crystalline product, characterized in that, The washing method is performed in the washing apparatus according to any one of claims 1-4, and the washing method includes: (1) The coarse crystal product is washed with washing liquid in a scrubber to obtain solid crystals and washing filtrate; (2) The solid crystal enters the melting zone of the melter, and the molten liquid phase after melting overflows into the clarification zone of the melter; The molten liquid phase in the clarifying zone is divided into at least three parts: At least a portion of the liquid phase is heated by a heat exchanger to obtain a heated liquid phase. Part of the heated liquid phase enters the scrubber through a bypass, and the rest is recycled back to the melting zone of the melter. At least a portion of the liquid phase directly enters the scrubber and, together with a portion of the heated liquid phase, is returned to step (1) as the washing liquid; At least a portion of the liquid phase is extracted as the target product.

6. The washing method according to claim 5, wherein, The liquid phase temperature at the heat exchanger outlet is controlled in cascade with the liquid phase flow rate entering the heat exchanger. When the liquid phase temperature at the heat exchanger outlet deviates from the control value, the liquid phase flow rate entering the heat exchanger is adjusted. Preferably, the liquid phase temperature at the heat exchanger outlet is 30-85°C higher than the melting point of the target product, more preferably 40-75°C; and / or The liquid flow rate entering the heat exchanger is 1.5-3 times the mass flow rate of the coarse-grained product.

7. The washing method according to claim 5 or 6, wherein, The liquid phase temperature at the clarification zone or outlet of the molten tank is controlled by adjusting the amount of heat exchange medium entering or leaving the heat exchanger; and / or The heat exchange medium in the heat exchanger is either the hot material from the upstream crystallization unit or other hot materials outside the crystallization unit, preferably the hot material from the upstream crystallization unit.

8. The washing method according to any one of claims 5-7, wherein, The flow rate of the bypass connecting the heat exchanger outlet to the scrubber is controlled to control the temperature of the scrubbing liquid in the scrubber. Preferably, the temperature of the scrubbing liquid is controlled to be 10-30°C higher than the melting point of the target product, more preferably 13-25°C; and / or The amount of washing liquid used can be controlled by controlling the liquid flow rate of the pipeline that is connected to the inlet of the clarification zone and the scrubber. Preferably, the liquid flow rate of the pipeline that is connected to the inlet of the clarification zone and the scrubber is 0.15-0.35 times the flow rate of the coarse crystal product.

9. The washing method according to any one of claims 5-8, wherein, The outlet temperature of the melting tank is lower than the temperature of the washing liquid, preferably 5-25°C lower than the temperature of the washing liquid, and more preferably 10-20°C lower. Based on the liquid phase flow rate entering the heat exchanger, the proportion of liquid phase flow rate circulating back to the molten zone of the melt is 90-99%, preferably 94-98%; and / or The liquid level in the melting tank is stabilized by controlling the flow rate of the target product.

10. The washing method according to any one of claims 5-9, wherein, The content of the target product in the coarse crystals is 95-99.5 wt%, preferably 97-99.5 wt%; and / or The target product in the coarse crystals is selected from aromatic compounds; Preferably, the aromatic compound is selected from substituted or unsubstituted benzene and / or substituted or unsubstituted naphthalene, more preferably from alkyl or halogen-substituted benzene and / or alkyl-substituted naphthalene, and more preferably from p-xylene, 2,6-diisopropylnaphthalene, mesitylene or p-dichlorobenzene.

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