Novel double-falling-film crystallizer structure and process

Abstract

The invention relates to the technical field of falling film crystallization, in particular to a novel double-falling-film crystallizer structure and process, and adopts the technical scheme that the novel double-falling-film crystallizer structure comprises a crystallizer cabin, a multi-section type double-falling-film assembly and a temperature control assembly; the crystallizer cabin body comprises a heat exchange cabin, a lower tube box is mounted at the bottom of the heat exchange cabin, a lower tube plate is mounted in the lower tube box, and a plurality of heat exchange tubes are mounted on the top surface of the lower tube plate; the multi-section type double-falling-film assembly comprises a solution film distributor, a first falling-film plate is fixedly installed on the upper portion of the inner wall of the heat exchange cabin, and a second falling-film plate and a third falling-film plate are installed on the inner wall of the heat exchange cabin in a sliding mode. And the heat exchange medium falls on the outer wall of the heat exchange pipe through the first falling film plate, the second falling film plate and the third falling film plate, double falling films of the solution and the heat exchange medium are achieved, the traditional mode that a large amount of heat exchange medium is injected is replaced, and the energy consumption of the crystallizer is reduced while the high heat exchange efficiency is kept.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of falling film crystallization, in particular to a novel double falling film crystallizer structure and process. BACKGROUND

[0002] The dichlorobenzene falling film crystallizer is a crystallization device for preparing dichlorobenzene, which utilizes the principle of falling film to guide the solution on the heated wall surface, and the solute in the solution is gradually precipitated to form crystals through evaporation or cooling. During operation, the molten material mixture is uniformly distributed along the inner wall of the crystallizer heat exchange pipe by a pump from the top distributor of the crystallizer, and the heat exchange medium exchanges heat inward through the heat exchange pipe, so that the material is crystallized on the inner wall of the heat exchange pipe.

[0003] For the dichlorobenzene falling film crystallizer, the distribution of the heat exchange medium is very critical, as it directly affects the efficiency and quality of the crystallization process. In the current falling film crystallizer, a large amount of heat exchange medium is injected outside the heat exchange pipe. Although this method can provide high heat exchange efficiency and has the characteristics of small temperature fluctuation, which helps to stabilize the crystallization process, it still has some defects, such as:

[0004] 1. In order to maintain the heat exchange efficiency, a large amount of heat exchange medium needs to be injected into the crystallizer and its flow rate needs to be properly ensured, which will increase energy consumption, especially in the case of large flow of heat exchange medium, additional pumps and driving devices may be required, resulting in increased energy consumption, and the contact surface between the heat exchange pipe and the heat exchange medium is limited, so a large amount of injected heat exchange medium may cause waste of heat exchange medium energy;

[0005] 2. The flow distribution of the heat exchange medium outside the heat exchange pipe may be uneven, which may cause low or high temperature zones in the crystallizer, resulting in local overheating or incomplete crystallization, thereby affecting the uniformity of the crystallization process;

[0006] 3. The injection of large flow of heat exchange medium requires a large space for the flow and heat dissipation of the heat exchange medium, which may cause the size of the crystallizer to increase and occupy more space;

[0007] Therefore, it is necessary to invent a novel double falling film crystallizer structure and process. SUMMARY

[0008] In order to achieve the above purpose, the present application provides the following technical scheme: a novel double falling film crystallizer structure and process, comprising a crystallizer cabin, a multi-section double falling film assembly and a temperature control assembly.

[0009] The crystallizer cabin includes a heat exchange cabin, an upper pipe box mounted on the top of the heat exchange cabin, a feed pipe mounted on the top of the upper pipe box, an upper pipe plate mounted in the upper pipe box, a lower pipe box mounted on the bottom of the heat exchange cabin, a lower feed pipe mounted on the bottom of the lower pipe box, and a lower pipe plate mounted on the top surface of the lower pipe box, wherein the outer wall of the heat exchange cabin is provided with a multi-stage heat exchange medium injection pipe group.

[0010] The multi-section double falling film assembly includes a solution film distributor mounted on the bottom of the upper pipe plate, the solution film distributor includes a film distribution pipe, the lower end of the film distribution pipe is connected with the upper end of the heat exchange pipe, a first falling film plate is fixedly mounted on the upper portion of the inner wall of the heat exchange cabin, a second falling film plate and a third falling film plate are slidingly mounted on the inner wall of the heat exchange cabin below the first falling film plate, the second falling film plate and the third falling film plate are both provided with a heat exchange medium interception and guide-in mechanism, and the heat exchange medium interception and guide-in mechanism is sleevedly mounted on the outer wall of the heat exchange pipe.

[0011] The temperature control assembly includes a multi-point thermocouple arranged in the heat exchange pipe, and a central control module mounted on the outer side of the lower pipe box.

[0012] Preferably, the multi-stage heat exchange medium injection pipe group includes a first injection pipe, the first injection pipe is insertedly mounted on one side of the upper pipe box, a support plate is mounted on the inner wall of the opening in the lower portion of the upper pipe box, and one end of the first injection pipe inserted into the upper pipe box is bent downward and penetrates through the support plate.

[0013] Preferably, the multi-stage heat exchange medium injection pipe group includes a discharge pipe, the discharge pipe is mounted on one side of the lower pipe box, a second injection pipe is mounted on the upper portion of the outer side of the heat exchange cabin, and a third injection pipe is mounted on the lower portion of the outer side of the heat exchange cabin.

[0014] Preferably, the solution film distributor includes a feed hopper, the feed hopper is embeddedly mounted on the surface of the upper pipe plate, the film distribution pipe is fixedly mounted on the support plate, an S-shaped expansion pipe is mounted on the lower end of the feed hopper, the lower end of the S-shaped expansion pipe is connected with the upper end of the film distribution pipe, a film distributor is arranged in the film distribution pipe, a gap is arranged between the film distributor and the inner wall of the film distribution pipe, a support is mounted on the top surface of the film distribution pipe, and the support is fixedly connected with the inner wall of the film distributor.

[0015] Preferably, a first falling film ring is arranged on the first falling film plate, the first falling film ring is sleeved on the outer side of the heat exchange pipe, a gap is arranged between the inner wall of the first falling film ring and the outer wall of the heat exchange pipe, and a first flow guide groove is arranged on the inner wall of the first falling film ring.

[0016] Preferably, the first falling film plate bottom surface is provided with an upper hydraulic rod, the lower end of the upper hydraulic rod is fixedly connected to the top of the second falling film plate, the lower tube plate top surface is provided with a lower hydraulic rod, the upper end of the lower hydraulic rod is fixedly connected to the bottom of the third falling film plate, and the upper and lower hydraulic rods are electrically connected with the central control module.

[0017] Preferably, the heat exchange medium interception and introduction mechanism comprises a second falling film ring, the second falling film ring is embedded and installed on the second and third falling film plates, a drainage ring is installed on the inner wall of the second falling film ring, drainage holes are arranged on the side surface of the drainage ring and communicate the inner and outer walls, and a sandwich layer is arranged inside the drainage ring.

[0018] Preferably, a trapping ring is installed on the upper end of the inner wall of the drainage ring, the trapping ring is in close contact with the outer wall of the heat exchange pipe, a collecting ring is installed on the upper end of the outer wall of the drainage ring, an outer side film forming ring is installed on the lower end of the outer wall of the drainage ring, an inner side film forming ring is installed on the lower end of the inner wall of the drainage ring, a ring-shaped film is installed on the lower end of the inner side film forming ring, and a second flow guide groove is arranged on the inner wall of the inner side film forming ring.

[0019] Preferably, a plurality of thermocouple probes are installed at different height positions on the surface of the multi-point thermocouple, a fixer is fixedly installed at the lower end of the multi-point thermocouple, the fixer is installed on the bottom surface of the lower tube plate, and the multi-point thermocouple is electrically connected with the central control module.

[0020] According to the production process of the novel double-falling-film crystallizer structure, S1-S4 are included.

[0021] S1, open the first injection pipe to inject the first heat exchange medium into the heat exchange cabin, the first heat exchange medium is distributed on the surface of the first falling film plate and overflowed from the surface of the first falling film ring to form a falling film on the outer wall of the heat exchange pipe, then open the second injection pipe to inject the second heat exchange medium into the heat exchange cabin, the second heat exchange medium is distributed on the surface of the second falling film plate and overflowed from the surface of the second falling film ring on the second falling film plate, enters the inner side film forming ring through the drainage holes on the drainage ring, and is distributed in a falling film on the outer wall of the heat exchange pipe, at the same time, the first heat exchange medium flowing down from the upper part of the heat exchange pipe is intercepted by the interception ring on the second falling film plate, the first heat exchange medium passes through the sandwich layer of the drainage ring and is distributed in a falling film on the outside of the second heat exchange medium along the outer side film forming ring, and similarly, the third injection pipe is opened to inject the third heat exchange medium into the heat exchange cabin, the third heat exchange medium is distributed on the surface of the third falling film plate and is distributed in a falling film between the second heat exchange medium and the outer wall of the heat exchange cabin through the heat exchange medium interception and introduction mechanism on the third falling film plate, so as to realize multi-stage cooling of the heat exchange pipe.

[0022] S2. Open the feed pipe to inject the solution into the upper tube box. The solution is distributed on the surface of the upper tube sheet and flows into the feed hopper. Then it enters the film distribution tube along the S-shaped expansion tube and flows through the gap between the film distribution tube and the film distributor, so that it is evenly distributed on the inner wall of the film distribution tube. Then the solution descends along the inner wall of the film distribution tube to the inner wall of the heat exchange tube. The heat exchange medium cools the solution through the heat exchange tube. The solution is gradually cooled and crystallized, and a uniform crystal layer gradually grows on the inner wall of the heat exchange tube.

[0023] S3. The internal temperature at different heights inside the heat exchange tube is detected in real time by multi-point thermocouples and the electrical signal is sent to the central control module. The central control module controls the upper hydraulic rod and the lower hydraulic rod to adjust the height of the second and third falling film plates respectively according to the received temperature signal, thereby controlling the falling film distribution area and introduction timing of each stage of heat exchange medium to stabilize the temperature range of the heat exchange tube surface in contact with the heat exchange medium.

[0024] S4. When the concentration of the crystal layer is higher than that of the solution, impurities gradually accumulate in the solution. Stop feeding through the feed pipe, control the temperature of the introduced heat exchange medium, and perform multiple partial melting processes on the crystal layer, namely, a first sweating process and a second sweating process. This process partially melts and removes the low-melting-point impurities mixed in the crystal layer. During this process, the solution is separated into residual mother liquor, sweating intermediate liquid, and higher-purity crystals. After four or five cycles, the crystals melt off the tube wall to become a refined crystallized separation product.

[0025] The beneficial effects of this invention are as follows: A dichlorobenzene solution is deposited onto the inner wall of the heat exchange tube using a solution film distributor, and then the heat exchange medium is deposited onto the outer wall of the heat exchange tube using a first, second, and third falling film plate. This achieves double falling film deposition of the solution and the heat exchange medium, replacing the traditional method of injecting a large amount of heat exchange medium. This reduces energy consumption of the crystallizer and minimizes energy waste of the heat exchange medium while maintaining high heat exchange efficiency. The elimination of the need for a large amount of heat medium makes it easier to control the size of the crystallizer and avoids occupying too much space. By adjusting the height of the second and third falling film plates, in conjunction with the heat exchange medium interception and introduction mechanism, the heat exchange medium is injected and distributed in multiple stages onto the surface of the heat exchange tube. This ensures that the temperature of the heat exchange medium outside the heat exchange tube remains within a stable range, preventing a drop in the temperature of the heat exchange medium at the bottom of the heat exchange tube due to heat transfer during the heat exchange process, thus improving the uniformity of the crystallization process. Attached Figure Description

[0026] Figure 1 A front view provided for this invention;

[0027] Figure 2 This is a front sectional view provided for the present invention;

[0028] Figure 3 This is a front cross-sectional view provided for the present invention;

[0029] Figure 4 This is a schematic diagram of the internal structure provided by the present invention;

[0030] Figure 5 Detailed internal view of the upper tube box provided for this invention;

[0031] Figure 6 Detailed view of the upper part of the heat exchange chamber provided by the present invention;

[0032] Figure 7 This is a cross-sectional view of the heat exchange tube provided by the present invention;

[0033] Figure 8 Provided by the present invention Figure 7 Detail image A;

[0034] Figure 9 Detailed view of the lower half of the heat exchange chamber provided by the present invention;

[0035] Figure 10 Detailed diagram of the heat exchange medium interception and induction mechanism provided by the present invention;

[0036] Figure 11 A cross-sectional view of the heat exchange medium interception and induction mechanism provided by the present invention;

[0037] Figure 12 This is a cross-sectional view of the heat exchange medium interception and inlet mechanism provided by the present invention;

[0038] Figure 13 This is a bottom view of the lower tube sheet provided by the present invention.

[0039] In the diagram: Upper tube box 111, heat exchange chamber 112, lower tube box 113, feed pipe 114, first injection pipe 115, second injection pipe 116, third injection pipe 117, discharge pipe 118, discharge pipe 119, upper tube sheet 121, support plate 122, first falling film plate 123, lower tube sheet 124, heat exchange tube 125, feed hopper 131, S-shaped expansion tube 132, film distribution tube 133, bracket 134, film distributor 135, first falling film plate 126, lower tube sheet 127, heat exchange tube 128, discharge pipe 119, upper tube sheet 121, support plate 122, first falling film plate 123, lower tube sheet 124, heat exchange tube 125, feed hopper 131, S-shaped expansion tube 132, film distribution tube 133, bracket 134, film distributor 135, first falling film plate 123, lower tube sheet 124, heat exchange tube 125, lower tube sheet ... lower tube sheet 125, lower tube sheet 123, lower tube sheet 124, lower tube sheet 125, lower tube sheet 123, lower tube sheet 124, lower tube sheet 125, lower tube sheet 123 Membrane ring 141, first guide groove 142, central control module 151, multi-point thermocouple 152, fixture 153, upper hydraulic rod 161, second falling film plate 162, lower hydraulic rod 163, third falling film plate 164, second falling film ring 171, guide ring 172, guide hole 173, collection ring 174, outer film forming ring 175, second guide groove 176, interception ring 177, inner film forming ring 178, annular film 179. Detailed Implementation

[0040] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0041] Example 1, as Figure 1 - Figure 6 As shown, a novel double falling film crystallizer structure and process in the first aspect embodiment of the present invention includes a crystallizer chamber, a multi-segment double falling film assembly, and a temperature control assembly.

[0042] The crystallizer chamber includes a heat exchange chamber 112, an upper tube box 111 installed on the top of the heat exchange chamber 112, a feed pipe 114 installed on the top of the upper tube box 111, an upper tube sheet 121 installed inside the upper tube box 111, a lower tube box 113 installed at the bottom of the heat exchange chamber 112, a feed pipe 119 installed at the bottom of the lower tube box 113, a lower tube sheet 124 installed inside the lower tube box 113, a number of heat exchange tubes 125 installed on the top surface of the lower tube sheet 124, and a multi-stage injection tube assembly for heat exchange medium is provided on the outer wall of the heat exchange chamber 112.

[0043] The multi-segment dual falling film assembly includes a solution film distributor, which is installed at the bottom of the upper tube sheet 121. The solution film distributor includes a film distribution tube 133, the lower end of which is connected to the upper end of the heat exchange tube 125. A first falling film plate 123 is fixedly installed on the upper part of the inner wall of the heat exchange chamber 112. A second falling film plate 162 and a third falling film plate 164 are slidably installed on the inner wall of the heat exchange chamber 112 below the first falling film plate 123. A heat exchange medium interception and introduction mechanism is installed on both the second falling film plate 162 and the third falling film plate 164. The heat exchange medium interception and introduction mechanism is sleeved on the outer wall of the heat exchange tube 125.

[0044] The temperature control component includes a multi-point thermocouple 152, which is installed inside the heat exchange tube 125, and a central control module 151 is installed on the outside of the lower tube box 113.

[0045] In the above embodiments, it should be noted that electronic valves are provided in both the feed pipe 114 and the discharge pipe 119 to control the opening and closing of the feed pipe 114 and the discharge pipe 119. The first injection pipe 115, the second injection pipe 116 and the third injection pipe 117 are all connected to the heat exchange medium cooling device. The cooling device sequentially introduces the cooled heat exchange medium into the first injection pipe 115, the second injection pipe 116 and the third injection pipe 117. The cooling device can control the temperature of the introduced heat exchange medium. The heat exchange medium after heat exchange is discharged through the discharge pipe 118 and reintroduced into the cooling device for recycling.

[0046] The central control module 151 includes

[0047] (1) Microcontroller (MCU): Used to execute control algorithms, process data in real time, and coordinate the work of other sensors and actuators;

[0048] (2) Power module: Provides a stable power supply for the entire central control system to ensure the normal operation of each component. AC / DC power modules are usually used.

[0049] (3) Hydraulic drive system: used to control the operation of the hydraulic rod;

[0050] (4) Display module: Provides a user interface to display real-time data (such as temperature, pressure, flow rate, liquid level, etc.) and allows operators to set and adjust parameters. It usually uses a touch screen or LED display.

[0051] (5) Relay: Used to control the start and stop of actuators such as pumps and valves;

[0052] (6) Communication interface: used to connect to cooling equipment or other related equipment and to control the cooling equipment;

[0053] The dichlorobenzene solution is lowered onto the inner wall of the heat exchange tube 125 by a solution film distributor, and then the heat exchange medium is lowered onto the outer wall of the heat exchange tube 125 by the first falling film plate 123, the second falling film plate 162 and the third falling film plate 164. This achieves a double falling film of the solution and the heat exchange medium, replacing the traditional method of injecting a large amount of heat exchange medium. This reduces the energy consumption of the crystallizer and the energy waste of the heat exchange medium while maintaining high heat exchange efficiency. It also makes it easier to control the size of the crystallizer without injecting a large amount of heat medium, and avoids occupying too much space.

[0054] By adjusting the height of the second falling film plate 162 and the third falling film plate 164, and in conjunction with the heat exchange medium interception and introduction mechanism, the heat exchange medium is injected in multiple stages and distributed on the surface of the heat exchange tube 125 in a falling film manner. This ensures that the temperature of the heat exchange medium outside the heat exchange tube 125 is always kept within a stable range, preventing the temperature of the heat exchange medium at the bottom of the heat exchange tube from dropping due to heat transfer during the heat exchange process, and improving the uniformity of the crystallization process.

[0055] Example 2, as Figure 1 - Figure 4 As shown, a novel dual falling film crystallizer structure and process are described, including Example 1. Furthermore, the multi-stage heat exchange medium injection pipe assembly includes a first injection pipe 115, which is inserted and installed on one side of the upper pipe box 111. A support plate 122 is installed on the inner wall of the lower opening of the upper pipe box 111. One end of the first injection pipe 115 inserted into the upper pipe box 111 is bent downwards and passes through the support plate 122. The multi-stage heat exchange medium injection pipe assembly includes a discharge pipe 118, which is installed on one side of the lower pipe box 113. A second injection pipe 116 is installed on the upper outer side of the heat exchange chamber 112, and a third injection pipe 117 is installed on the lower outer side of the heat exchange chamber 112.

[0056] In the above embodiments, it should be noted that by opening the first injection pipe 115 to inject a primary heat exchange medium into the heat exchange chamber 112, the primary heat exchange medium can be distributed on the surface of the first falling film plate 123; by opening the second injection pipe 116 to inject a secondary heat exchange medium into the heat exchange chamber 112, the secondary heat exchange medium can be distributed on the surface of the second falling film plate 162; and by opening the third injection pipe 117 to inject a tertiary heat exchange medium into the heat exchange chamber 112, the tertiary heat exchange medium can be distributed on the surface of the third falling film plate 164.

[0057] Example 3, as Figure 1 - Figure 8 As shown, a novel double falling film crystallizer structure and process, including Example 2, is described. Furthermore, the solution film distributor includes a feed hopper 131, which is embedded in the surface of the upper tube sheet 121. A film distribution tube 133 is fixedly installed on a support plate 122. An S-shaped expansion tube 132 is installed at the lower end of the feed hopper 131, and the lower end of the S-shaped expansion tube 132 is connected to the upper end of the film distribution tube 133. A film distributor 135 is installed inside the film distribution tube 133, and a gap is provided between the film distributor 135 and the inner wall of the film distribution tube 133. A bracket 134 is installed on the top surface of the film distribution tube 133, and the bracket 134 is fixedly connected to the inner wall of the film distributor 135.

[0058] In the above embodiment, it should be noted that when the feed pipe 114 is opened, the solution is injected into the upper tube box 111. The solution is distributed on the surface of the upper tube plate 121 and flows into the feed hopper 131. Then, it enters the film distribution tube 133 along the S-shaped expansion tube 132 and then flows through the gap between the film distribution tube 133 and the film distributor 135, so that it is evenly distributed on the inner wall of the film distribution tube 133. Then, the solution descends along the inner wall of the film distribution tube 133 to the inner wall of the heat exchange tube 125, so as to achieve the effect of evenly descending the dichlorobenzene solution on the inner wall of the heat exchange tube 125.

[0059] Example 4, as Figure 1 - Figure 4 As shown, a novel dual falling film crystallizer structure and process are described, including Embodiment 1. Furthermore, a first falling film ring 141 is provided on the first falling film plate 123, and the first falling film ring 141 is sleeved on the outside of the heat exchange tube 125. A gap is provided between the inner wall of the first falling film ring 141 and the outer wall of the heat exchange tube 125. A first guide groove 142 is provided on the inner wall of the first falling film ring 141. An upper hydraulic rod 161 is installed on the bottom surface of the first falling film plate 123, and the lower end of the upper hydraulic rod 161 is fixedly connected to the top of the second falling film plate 162. A lower hydraulic rod 163 is installed on the top surface of the lower tube plate 124, and the upper end of the lower hydraulic rod 163 is fixedly connected to the bottom of the third falling film plate 164. Both the upper hydraulic rod 161 and the lower hydraulic rod 163 are electrically connected to the central control module 151.

[0060] In the above embodiments, it should be noted that the primary heat exchange medium distributed on the surface of the first falling film plate 123 can overflow from the surface of the first falling film ring 141 and a gap is provided between the inner wall of the first falling film ring 141 and the outer wall of the heat exchange tube 125, and the flow of the first guide groove 142 leads to the falling film on the outer wall of the heat exchange tube 125.

[0061] The hydraulic drive system within the central control module 151 controls the upper hydraulic rod 161 and the lower hydraulic rod 163 to adjust the height of the second falling film plate 162 and the third falling film plate 164 respectively. This, in conjunction with the heat exchange medium interception and introduction mechanism, controls the falling film distribution area and introduction timing of each stage of heat exchange medium, thereby stabilizing the temperature range of the heat exchange tube 125 surface in contact with the heat exchange medium.

[0062] Example 5, as Figure 2 - Figure 4 , Figure 9 - Figure 12 As shown, a novel double falling film crystallizer structure and process, including Example 1, further includes a heat exchange medium interception and introduction mechanism comprising a second falling film ring 171. The second falling film ring 171 is embedded in both the second falling film plate 162 and the third falling film plate 164. A flow guiding ring 172 is installed on the inner wall of the second falling film ring 171. A flow guiding hole 173 connecting the inner and outer walls is provided on the side of the flow guiding ring 172. An interlayer is provided inside the flow guiding ring 172. A trapping ring 177 is installed on the upper end of the inner wall of the flow ring 172. The trapping ring 177 is in close contact with the outer wall of the heat exchange tube 125. A collecting ring 174 is installed on the upper end of the outer wall of the flow ring 172. An outer film-forming ring 175 is installed on the lower end of the outer wall of the flow ring 172. An inner film-forming ring 178 is installed on the lower end of the inner wall of the flow ring 172. An annular film 179 is installed on the lower end of the inner film-forming ring 178. A second guide groove 176 is provided on the inner wall of the inner film-forming ring 178.

[0063] In the above embodiments, it should be noted that the annular film 179 is made of PVC material and is used to guide the stratified flow of two heat exchange media at different temperatures. During the heat exchange process, after the heat of the first-stage heat exchange medium introduced first rises to a certain range, a brand-new second-stage heat exchange medium will be introduced. At the same time, the first-stage heat exchange medium is placed on the outside of the second-stage heat exchange medium to achieve a heat preservation effect and prevent the temperature of the second-stage heat exchange medium from rapidly escaping to the outside air.

[0064] The secondary heat exchange medium distributed on the surface of the second falling film plate 162 overflows from the surface of the second falling film ring 171 on the second falling film plate 162, enters the space between the inner film forming ring 178 and the heat exchange tube 125 through the drainage hole 173 on the drainage ring 172, and falls and distributes on the outer wall of the heat exchange tube 125 under the guidance of the second guide groove 176. At the same time, the primary heat exchange medium flowing down from the upper part of the heat exchange tube 125 is intercepted by the interception ring 177 on the second falling film plate 162. The intercepted primary heat exchange medium passes through the interlayer of the drainage ring 172 along the collection ring 174 and enters the space between the side film forming ring 175 and the inner film forming ring 178. Then it flows along the outer side of the inner film forming ring 178 to the annular film 179 and falls and distributes on the outer side of the secondary heat exchange medium.

[0065] Similarly, the tertiary heat exchange medium distributed on the surface of the third falling film plate 164 overflows from the surface of the third falling film plate 1642, enters the space between the inner film-forming ring 178 and the heat exchange tube 125 through the drainage hole 173 on the drainage ring 172, and falls onto the outer wall of the heat exchange tube 125 under the guidance of the second guide groove 176. At the same time, the secondary heat exchange medium flowing down from the upper part of the heat exchange tube 125 is intercepted by the interception ring 177 on the third falling film plate 164. The intercepted secondary heat exchange medium passes through the interlayer of the drainage ring 172 along the collection ring 174 and enters the space between the side film-forming ring 175 and the inner film-forming ring 178. Then it flows along the outer side of the inner film-forming ring 178 to the annular film 179 and falls onto the outer side of the tertiary heat exchange medium.

[0066] Example 6, as Figure 3 and Figure 13 As shown, a novel dual falling film crystallizer structure and process are described, including Example 1. In addition, multiple thermocouple probes are installed at different height positions on the surface of the multi-point thermocouple 152. A retainer 153 is fixedly installed at the lower end of the multi-point thermocouple 152. The retainer 153 is installed on the bottom surface of the lower tube sheet 124. The multi-point thermocouple 152 is electrically connected to the central control module 151.

[0067] In the above embodiments, it should be noted that the multi-point thermocouple 152 is mounted on the fixture 153 and extends upward into the heat exchange tube 125 via the fixture 153. The multi-point thermocouple is a sensor that generates voltage by measuring the temperature difference at the metal contact points. By installing multiple thermocouple probes at different heights, the temperature changes at different locations inside the heat exchange tube can be accurately measured.

[0068] The manufacturing process of a novel double falling film crystallizer structure according to the present invention is as follows: First injection pipe 115 is opened to inject a primary heat exchange medium into the heat exchange chamber 112. The primary heat exchange medium is distributed on the surface of the first falling film plate 123 and overflows from the surface of the first falling film ring 141, falling onto the outer wall of the heat exchange tube 125. Then, second injection pipe 116 is opened to inject a secondary heat exchange medium into the heat exchange chamber 112. The secondary heat exchange medium is distributed on the surface of the second falling film plate 162 and overflows from the surface of the second falling film ring 171 on the second falling film plate 162. It then enters the inner film-forming ring 178 through the drainage hole 173 on the drainage ring 172 and falls onto the outer wall of the heat exchange tube 125. Simultaneously, the heat exchange tube 125... The primary heat exchange medium flowing down from the top is intercepted by the interception ring 177 on the second falling film plate 162. The primary heat exchange medium passes through the interlayer of the guide ring 172 and falls along the outer film-forming ring 175 to distribute on the outside of the secondary heat exchange medium. Similarly, the third injection pipe 117 is opened to inject the tertiary heat exchange medium into the heat exchange chamber 112. The tertiary heat exchange medium is distributed on the surface of the third falling film plate 164 and falls between the secondary heat exchange medium and the outer wall of the heat exchange chamber 112 through the heat exchange medium interception and introduction machine on the third falling film plate 164, thus achieving multi-stage cooling of the heat exchange tubes. The feed pipe 114 is opened to inject the solution into the upper tube box 111. The solution is distributed on the surface of the upper tube sheet 121 and flows into the feed hopper 131. The solution enters the film distribution tube 133 through the S-shaped expansion tube 132, and then flows through the gap between the film distribution tube 133 and the film distributor 135, allowing it to be evenly distributed on the inner wall of the film distribution tube 133. The solution then descends along the inner wall of the film distribution tube 133 to the inner wall of the heat exchange tube 125. The heat exchange medium cools the solution through the heat exchange tube 125, and the solution is gradually cooled and crystallized, gradually growing a uniform crystal layer on the inner wall of the heat exchange tube 125. The internal temperature at different heights within the heat exchange tube 125 is monitored in real time by multi-point thermocouples 152, and electrical signals are sent to the central control module 151. The central control module 151 controls the upper hydraulic rod 161 and the lower hydraulic rod 163 to adjust the second descending... The height of the membrane plate 162 and the third falling film plate 164 controls the falling film distribution area and introduction timing of each stage of heat exchange medium to stabilize the temperature range of the heat exchange tube 125 surface in contact with the heat exchange medium. When the concentration of the crystal layer is higher than the concentration of the solution, impurities gradually accumulate in the solution. The feed pipe 114 is stopped, and the temperature of the introduced heat exchange medium is controlled to perform multiple partial meltings on the crystal layer, namely, a first sweating process and a second sweating process, so that the low melting point impurities mixed in the crystal layer are partially melted and removed. During this process, the solution is separated into residual mother liquor, sweating intermediate liquid and higher purity crystals. After four or five cycles, the crystals melt down from the tube wall to become a refined crystallized separation product.

[0069] The above description is merely a preferred embodiment of the present invention. Any person skilled in the art can modify the present invention or modify it into an equivalent technical solution using the technical solutions described above. Therefore, any simple modifications or equivalent substitutions made based on the technical solutions of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A novel dual-falling-film crystallizer structure, comprising a crystallizer chamber, a multi-section dual-falling-film assembly, and a temperature control assembly, characterized in that: The crystallizer chamber includes a heat exchange chamber (112), an upper tube box (111) is installed on the top of the heat exchange chamber (112), a feed pipe (114) is installed on the top of the upper tube box (111), an upper tube sheet (121) is installed inside the upper tube box (111), a lower tube box (113) is installed at the bottom of the heat exchange chamber (112), a feed pipe (119) is installed at the bottom of the lower tube box (113), a lower tube sheet (124) is installed inside the lower tube box (113), a plurality of heat exchange tubes (125) are installed on the top surface of the lower tube sheet (124), and a multi-stage injection tube assembly for heat exchange medium is provided on the outer wall of the heat exchange chamber (112). The multi-segment dual falling film assembly includes a solution film distributor, which is installed at the bottom of the upper tube sheet (121). The solution film distributor includes a film distribution tube (133), the lower end of which is connected to the upper end of the heat exchange tube (125). A first falling film plate (123) is fixedly installed on the upper part of the inner wall of the heat exchange chamber (112). A second falling film plate (162) and a third falling film plate (164) are slidably installed on the inner wall of the heat exchange chamber (112) below the first falling film plate (123). A heat exchange medium interception and introduction mechanism is installed on both the second falling film plate (162) and the third falling film plate (164). The heat exchange medium interception and introduction mechanism is sleeved and installed on the outer wall of the heat exchange tube (125). The temperature control component includes a multi-point thermocouple (152), which is installed inside the heat exchange tube (125), and a central control module (151) is installed on the outside of the lower tube box (113).

2. The novel double falling film crystallizer structure according to claim 1, characterized in that: The heat exchange medium multi-stage injection pipe assembly includes a first injection pipe (115), which is inserted into and installed on one side of the upper pipe box (111). A support plate (122) is installed on the inner wall of the lower opening of the upper pipe box (111). One end of the first injection pipe (115) inserted into the upper pipe box (111) bends downward and passes through the support plate (122).

3. The novel double falling film crystallizer structure according to claim 2, characterized in that: The heat exchange medium multi-stage injection pipe group includes a discharge pipe (118), which is installed on one side of the lower pipe box (113). A second injection pipe (116) is installed on the upper part of the outer side of the heat exchange chamber (112), and a third injection pipe (117) is installed on the lower part of the outer side of the heat exchange chamber (112).

4. The novel double falling film crystallizer structure according to claim 2, characterized in that: The solution membrane applicator includes a feed hopper (131) embedded in the surface of the upper tube plate (121), a membrane applicator tube (133) fixedly mounted on a support plate (122), an S-shaped expansion tube (132) installed at the lower end of the feed hopper (131), the lower end of the S-shaped expansion tube (132) connected to the upper end of the membrane applicator tube (133), a membrane applicator (135) provided inside the membrane applicator tube (133), a gap provided between the membrane applicator (135) and the inner wall of the membrane applicator tube (133), a bracket (134) installed on the top surface of the membrane applicator tube (133), and the bracket (134) fixedly connected to the inner wall of the membrane applicator (135).

5. The novel double falling film crystallizer structure according to claim 1, characterized in that: The first falling film plate (123) is provided with a first falling film ring (141), which is sleeved on the outside of the heat exchange tube (125). A gap is provided between the inner wall of the first falling film ring (141) and the outer wall of the heat exchange tube (125). A first guide groove (142) is provided on the inner wall of the first falling film ring (141).

6. The novel double falling film crystallizer structure according to claim 1, characterized in that: An upper hydraulic rod (161) is installed on the bottom surface of the first falling film plate (123). The lower end of the upper hydraulic rod (161) is fixedly connected to the top of the second falling film plate (162). A lower hydraulic rod (163) is installed on the top surface of the lower tube plate (124). The upper end of the lower hydraulic rod (163) is fixedly connected to the bottom of the third falling film plate (164). Both the upper hydraulic rod (161) and the lower hydraulic rod (163) are electrically connected to the central control module (151).

7. The novel double falling film crystallizer structure according to claim 1, characterized in that: The heat exchange medium interception and introduction mechanism includes a second falling film ring (171). The second falling film plate (162) and the third falling film plate (164) are both embedded with the second falling film ring (171). A flow guide ring (172) is installed on the inner wall of the second falling film ring (171). The flow guide ring (172) has a flow guide hole (173) connecting the inner and outer walls on its side. The flow guide ring (172) has a sandwich layer inside.

8. The novel double falling film crystallizer structure according to claim 7, characterized in that: A trapping ring (177) is installed on the upper end of the inner wall of the flow guiding ring (172), and the trapping ring (177) is in close contact with the outer wall of the heat exchange tube (125). A collecting ring (174) is installed on the upper end of the outer wall of the flow guiding ring (172). An outer film forming ring (175) is installed on the lower end of the outer wall of the flow guiding ring (172). An inner film forming ring (178) is installed on the lower end of the inner wall of the flow guiding ring (172). An annular film (179) is installed on the lower end of the inner film forming ring (178). A second guide groove (176) is provided on the inner wall of the inner film forming ring (178).

9. The novel double falling film crystallizer structure according to claim 1, characterized in that: Multiple thermocouple probes are installed at different height positions on the surface of the multi-point thermocouple (152). A retainer (153) is fixedly installed at the lower end of the multi-point thermocouple (152). The retainer (153) is installed on the bottom surface of the lower tube sheet (124). The multi-point thermocouple (152) is electrically connected to the central control module (151).

10. A manufacturing process for a novel double falling film crystallizer structure as described in claims 1-9, comprising steps S1-S4, characterized in that: S1. Open the first injection pipe (115) to inject the primary heat exchange medium into the heat exchange chamber (112). The primary heat exchange medium is distributed on the surface of the first falling film plate (123) and overflows from the surface of the first falling film ring (141) to fall onto the outer wall of the heat exchange tube (125). Then, open the second injection pipe (116) to inject the secondary heat exchange medium into the heat exchange chamber (112). The secondary heat exchange medium is distributed on the surface of the second falling film plate (162) and overflows from the surface of the second falling film ring (171) on the second falling film plate (162). It enters the inner film-forming ring (178) through the drainage hole (173) on the drainage ring (172) and falls onto the heat exchange tube (125). 125) On the outer wall, the primary heat exchange medium flowing down from the upper part of the heat exchange tube (125) is intercepted by the interception ring (177) on the second falling film plate (162). The primary heat exchange medium passes through the interlayer of the guide ring (172) and falls along the outer film forming ring (175) to be distributed on the outside of the secondary heat exchange medium. Similarly, the third injection pipe (117) is opened to inject the tertiary heat exchange medium into the heat exchange chamber (112). The tertiary heat exchange medium is distributed on the surface of the third falling film plate (164) and falls between the secondary heat exchange medium and the outer wall of the heat exchange chamber (112) through the heat exchange medium interception and introduction machine on the third falling film plate (164) to achieve multi-stage cooling of the heat exchange tube; S2. Open the feed pipe (114) to inject the solution into the upper tube box (111). The solution is distributed on the surface of the upper tube plate (121) and flows into the feed hopper (131). Then, it enters the film distribution tube (133) along the S-shaped expansion tube (132). Subsequently, it flows through the gap between the film distribution tube (133) and the film distributor (135) to make it uniformly distributed on the inner wall of the film distribution tube (133). Then, the solution descends along the inner wall of the film distribution tube (133) to the inner wall of the heat exchange tube (125). The heat exchange medium cools the solution through the heat exchange tube (125). The solution is gradually cooled and crystallized, and a uniform crystal layer gradually grows on the inner wall of the heat exchange tube (125). S3. The internal temperature of the heat exchange tube (125) at different heights is detected in real time by a multi-point thermocouple (152) and the electrical signal is sent to the central control module (151). The central control module (151) controls the upper hydraulic rod (161) and the lower hydraulic rod (163) to adjust the height of the second falling film plate (162) and the third falling film plate (164) respectively according to the received temperature signal, so as to control the falling film distribution area and introduction timing of each stage of heat exchange medium, so as to stabilize the temperature range of the heat exchange tube (125) surface in contact with the heat exchange medium. S4. When the concentration of the crystal layer is higher than that of the solution, impurities gradually accumulate in the solution. Stop feeding through the feed pipe (114), control the temperature of the introduced heat exchange medium, and perform multiple partial meltings on the crystal layer, namely, a first sweating process and a second sweating process, so that the low melting point impurities mixed in the crystal layer are partially melted and removed. During this process, the solution is separated into residual mother liquor, sweating intermediate liquid and higher purity crystals. After four or five cycles, the crystals melt down from the pipe wall to become refined crystallization separation products.

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