Resin drying device and method and application

Abstract

The invention provides a resin drying device and method and application, an inner-layer annular Johnson net and an outer-layer annular Johnson net are coaxially arranged in a vertical tower body of the resin drying device to form an annular columnar material channel, an inner-ring air chamber and an outer-ring air chamber, and the inner-ring air chamber and the outer-ring air chamber are divided into an inner cooling section, an outer cooling section and drying sections in the height direction; the gas in the inner / outer cooling section radially penetrates through a material layer from inside to outside, and sensible heat in the material is recovered to realize self-preheating of the gas; the preheated gas starts from the lower outer drying section on the lowest layer, penetrates through the material layers corresponding to the different drying sections in the alternately changing radial direction, is heated through a heat exchanger between the drying sections and then enters the previous drying section; heat gradient utilization and alternate cross-flow drying are formed, so that uniform and efficient drying of the resin is achieved, heat energy recovery and drying and cooling are integrated, and the drying device is particularly suitable for safe and energy-saving drying of the easily-oxidized resin.

Description

Technical Field

[0001] This invention relates to the field of material drying and thermal technology, specifically to a resin drying apparatus, method, and application. Background Technology

[0002] For resins that are easily oxidized and sensitive to oxygen, such as PET, PA, PBT, and barrier resins, the drying process must be carried out in an inert gas atmosphere.

[0003] Currently used inert gas circulating drying equipment typically employs a simple single-loop system: the gas is heated and then passed into an adsorption dryer, where it absorbs moisture, is then condensed and dehumidified, and reheated, repeating this process to complete the heating. However, this model has significant drawbacks: 1) The drying and cooling of the material are usually separated and independent in terms of equipment structure and gas flow, resulting in a complex system structure; 2) The gas flow direction within the adsorption dryer is fixed and unidirectional, easily causing uneven drying of the material; 3) The sensible heat carried by the cooled material is directly discharged or only partially recovered, resulting in low energy utilization; 4) The temperature drop of the entire circulating gas is large, leading to high reheating energy consumption.

[0004] Therefore, there is an urgent need for a closed-loop inert gas drying solution that can achieve uniform drying, deep energy saving, and compact structure to solve the defects of existing single-loop drying equipment. Summary of the Invention

[0005] To address the shortcomings of existing single-loop drying equipment, this invention provides a resin drying device, method, and application. The resin drying device uses inert gas as the drying medium, and the inert gas dries the resin in a circulating and alternating cross-flow manner. This not only results in excellent drying uniformity and high thermal energy utilization, but also completes inert gas drying, cooling, and heat recovery in a closed system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A resin drying apparatus, comprising:

[0008] The tower body has a feed inlet at the top, a discharge outlet at the bottom, a humid gas outlet on the upper side wall, and a gas inlet on the lower side wall.

[0009] The heating system includes at least one gas pipeline containing a heat exchanger.

[0010] The condensation dehumidification system has an inlet connected to the outlet of the humid gas and an outlet connected to the gas inlet.

[0011] The control system is connected to the vertical tower body and the heating system respectively via signal transmission;

[0012] The vertical tower body is coaxially provided with inner and outer annular Johnson nets, and the inner and outer annular Johnson nets form an annular material channel. The inner annular Johnson net independently encloses to form an inner annular air chamber, and the outer annular Johnson net and the inner wall of the vertical tower body enclose to form an outer annular air chamber.

[0013] The annular material channel is connected to the inlet and the outlet respectively, and the annular width (i.e. radial thickness) of the annular material channel is 100-400mm;

[0014] The inner annular air chamber is vertically divided into a bottom inner cooling section and at least two inner drying sections; the outer annular air chamber is vertically divided into a bottom outer cooling section and an outer drying section with the same number of inner drying sections; the inner cooling sections and the outer cooling sections have the same height, and the number of inner drying sections and the number of outer drying sections are counted sequentially from bottom to top, with the inner drying sections having the same height as the corresponding outer drying sections (the heights of the inner drying sections may be the same or different, preferably the same).

[0015] The gas inlet is connected to the inner cooling section of the inner ring air chamber via a pressurization device (such as a booster).

[0016] Each of the external drying sections is divided into an upper external drying section and a lower external drying section. A circulation outlet is provided on the side wall of the vertical tower body corresponding to the positions of the upper external drying section and the external cooling section. A circulation inlet is provided on the side wall of the vertical tower body corresponding to the position of the lower external drying section. Each circulation outlet and its uppermost circulation inlet are connected via a gas pipeline containing a heat exchanger. The circulation outlet on the side wall of the vertical tower body, corresponding to the uppermost upper external drying section, is the humid gas outlet.

[0017] The maximum gap size of the inner and outer annular Johnson mesh is smaller than the minimum particle size of the resin (i.e., the inner annular air chamber, the outer annular air chamber, and the annular material channel are only used for gas passage and for blocking materials).

[0018] In the resin drying apparatus provided by this invention, the purpose of setting up inner and outer cooling sections in the vertical tower body is to allow circulating gas to enter from the inner cooling section of the inner ring air chamber and penetrate the material layer radially from the inside to the outside to absorb the sensible heat in the dried material; the purpose of setting up each inner and outer drying section, as well as the upper outer drying section and the lower outer drying section, is to allow circulating gas to penetrate the material layer radially from the outside to the inside and from the inside to the outside, so as to improve the drying effect and drying uniformity of the material; the purpose of setting up a gas pipeline containing a heat exchanger between each circulation outlet and the circulation inlet above it is to realize that the inert gas flows in an S-shaped path (forming an alternating cross-flow pattern for the material) while simultaneously heating the inert gas in stages (used to heat the cooled inert gas flowing out of the circulation outlet and then send it back to the previous drying section through the circulation inlet) to improve the drying effect of the material.

[0019] The resin drying device provided by this invention uses an inert gas (such as nitrogen) as the drying medium and integrates heat recovery in stages, alternating cross-flow drying, and cooling functions into a highly efficient and energy-saving resin drying device. The inert gas used for drying the resin forms a closed-loop circulation loop between the vertical tower, the heating system, and the condensation and dehumidification system: condensation and dehumidification system outlet → pressurization device → inner cooling section → material section at the same height as the inner cooling section in the annular material channel → outer cooling section → heat exchanger → lower outer drying section → material section at the same height as the lower drying section in the annular material channel → inner drying section → material section at the same height as the upper drying section in the annular material channel → upper outer drying section → ... the uppermost upper outer drying section → condensation and dehumidification system inlet.

[0020] In one optional embodiment, the upper outer drying section and the lower outer drying section may have the same or different heights, preferably the same.

[0021] In one alternative embodiment, the filaments of the inner and outer annular Johnson mesh are arranged vertically.

[0022] In one optional embodiment, the groove width of the inner and outer annular Johnson mesh can be selected according to the material size, so as to control the material from passing through the Johnson mesh, which is generally about 0.5-1.2mm.

[0023] In one optional embodiment, the number of both the inner drying section and the outer drying section is 2-10, such as 3, 4, 5, 6, 7, 8, 9, etc.

[0024] In one optional embodiment, the inner annular air chamber has a circular cross-section with a diameter of 200-1200 mm.

[0025] In one alternative embodiment, the ratio of the radius of the inner annular air chamber to the width of the annular material channel is 0.25 to 4.

[0026] In one optional embodiment, the outer annular air chamber is annular, with a ring width of 100-600 mm.

[0027] In one optional embodiment, the annular cross-sectional area of ​​the outer annular air chamber is greater than or equal to the cross-sectional area of ​​the inner annular air chamber.

[0028] In one optional embodiment, the ratio of the circumference width of the outer annular air chamber to the circumference width of the annular material channel is 0.25 to 4.

[0029] In one optional implementation, the height of the vertical tower is not specifically limited and can be set according to actual needs. Generally, the height of the vertical tower is greater than 1m.

[0030] In one alternative embodiment, the inner annular air chamber is divided by at least two inner annular partitions, and the outer annular air chamber is divided by at least two outer annular partitions.

[0031] In one alternative embodiment, each of the outer drying sections is divided into an upper outer drying section and a lower outer drying section by an outer annular partition plate.

[0032] In one alternative embodiment, the heat exchanger heats the gas to a preset temperature using an external heat source such as steam or thermal oil.

[0033] In one alternative embodiment, the condensation dehumidification system includes a combination of a condenser and a refrigerated adsorption dryer, which can cool the high-humidity gas from the wet gas outlet of the vertical tower to below its dew point temperature, reducing the gas moisture content to -40°C or lower.

[0034] In one optional embodiment, a top distributor is provided between the top feed inlet of the vertical tower and the annular material channel to evenly distribute the material within the annular material channel, forming a stable moving bed.

[0035] In one alternative embodiment, a radar level gauge is provided at the top feed inlet of the vertical tower.

[0036] In one alternative embodiment, each of the gas pipelines containing the heat exchanger is equipped with a valve for controlling the gas flow rate.

[0037] In one optional embodiment, the heating power of the heat exchangers on each of the gas pipelines containing heat exchangers can be independently adjusted to control the temperature of the circulating gas entering the corresponding drying section within a set range.

[0038] In one optional embodiment, temperature sensors, pressure sensors, flow sensors, etc., are respectively installed on each of the gas pipelines containing heat exchangers to detect real-time parameters such as temperature, pressure, and flow rate.

[0039] In one optional embodiment, the pipeline between the condensation dehumidification system and the gas inlet of the vertical tower is equipped with a pressure sensor, a flow sensor, and other detection elements for detecting pressure and flow, in addition to a pressurization device for pressurization.

[0040] In one alternative implementation, the control system is a conventional control system, such as a conventional PLC control system, which can be specifically implemented with reference to PLC control in related technologies.

[0041] The present invention also provides a resin drying method using the above-mentioned resin drying apparatus, comprising the following steps:

[0042] S1: After the inert gas is pressurized, it enters the internal cooling section from the gas inlet, and then flows in a continuous S-shaped path between the vertical tower body and each gas pipeline. Finally, it is discharged from the wet gas outlet. The discharged inert gas is condensed and dehumidified, and then pressurized again before circulating back into the vertical tower body from the gas inlet, forming a closed loop of inert gas, so that the vertical tower body is filled with flowing inert gas.

[0043] S2: Wet resin is continuously fed into the annular material channel through the feed inlet, forming a moving bed that moves downward. During the downward movement, it is radially dried by inert gas flowing in a continuous S-shaped path between the inner drying section and the outer drying section at the same height (for wet resin, the inert gas passes through the wet resin radially from the inside to the outside and from the outside to the inside, forming an alternating cross-flow pattern for drying). Finally, after the sensible heat is absorbed by the inert gas between the inner cooling section and the outer cooling section, it is continuously discharged through the discharge port.

[0044] The inert gas is heated in each of the gas pipelines during the continuous S-shaped flow process; the process parameters of the entire drying process are controlled by the control system.

[0045] In one optional embodiment, the temperature of the inert gas inside the vertical tower decreases from bottom to top along the height of the vertical tower (i.e., except for the cooling section, the temperature of the inert gas decreases from bottom to top along the height of the vertical tower). The specific rate or rhythm of the decrease can be selected according to the actual situation.

[0046] In one alternative embodiment, the inert gas is nitrogen.

[0047] In one optional embodiment, the continuous S-shaped path of the inert gas includes: a gas inlet on the lower side wall of the vertical tower body → an inner cooling section → a material layer at the same height as the cooling section in the annular material channel → an outer cooling section → a gas pipeline containing a heat exchanger → a lower outer drying section → a material layer at the same height as the lower outer drying section in the annular material channel → an inner drying section → a material layer at the same height as the upper outer drying section in the annular material channel → an upper outer drying section → another gas pipeline containing a heat exchanger... → a wet gas outlet on the upper side wall of the vertical tower body. That is, the continuous S-shaped path of the inert gas includes: after being pressurized, the inert gas enters the inner cooling section from the gas inlet, then passes radially through the material layer at the same height as the cooling section in the annular material channel, and the outer cooling section in sequence. After being heated by the heat exchanger on the gas pipeline at the circulation outlet of the outer cooling section, it enters the lower outer drying section through the circulation inlet of the lower outer drying section adjacent to the outer cooling section. Then, it passes radially through the annular material channel section corresponding to the lower outer drying section and enters the inner drying section. It then passes radially through the annular material channel section corresponding to the upper outer drying section and the upper outer drying section in sequence. Then, it repeats the process of being heated by the heat exchanger on another gas pipeline at the circulation outlet and entering the next lower outer drying section through the circulation inlet. In this way, the inert gas flows in an S-shaped path between the vertical tower body and each of the gas pipelines (located outside the vertical tower body), and finally exits from the wet gas outlet on the upper side wall of the vertical tower body.

[0048] In the actual process, the relevant process parameters can be precisely adjusted with the help of a PLC control system, taking into account the structure and component parameters of the resin drying device (such as the ring width of the outer ring air chamber, the diameter of the annular material channel, the height of each drying section, etc.) and the process objectives.

[0049] In one optional implementation, step S2 specifically includes the following steps:

[0050] S21 Cooling and Preliminary Heating: The low-temperature circulating gas, after being condensed and dehumidified by the condensation and dehumidification system, is driven by a booster device (such as a booster fan) to first enter the inner ring air chamber from the gas inlet of the vertical tower body, and then radially passes through the dried high-temperature resin layer from the inside to the outside. During this process, the low-temperature circulating gas absorbs the sensible heat in the resin and is preheated itself.

[0051] S22 First-stage heating and drying: The preheated circulating gas enters the first gas pipeline through the external cooling section and is heated by the first heat exchanger on the first gas pipeline (heated to the target temperature, such as 110-120℃ by an external heat source, such as steam or heat transfer oil). Subsequently, the hot gas passes radially from the outside to the inside through the material layer of the first lower external drying section immediately above the external cooling section and enters the corresponding first inner drying section. In the first inner drying section, the hot gas flows upward and then radially from the inside to the outside through the corresponding material layer to enter the first upper external drying section, where the resin is heated and dehydrated. The gas releases heat here, and the temperature decreases (e.g., to 85-100℃).

[0052] S23 Secondary Heating and Re-drying: The cooled gas flowing out of the upper outer drying section is introduced into the second heat exchanger on the second gas pipeline for intermediate reheating, causing the gas temperature to rise back to the second target drying temperature (110-115℃). Then, the reheated hot gas is sent to the lower outer drying section of the adjacent upper second outer drying section, where it again penetrates the material layer from the outside in for drying, entering the second inner drying section. In the second inner drying section, the hot gas flows upwards, then radially from the inside out through the corresponding material layer to enter the second upper outer drying section, where it heats and dehydrates the resin.

[0053] S24 Repeat: Following step 3 above, the gas is sequentially moved upwards in alternating cross-flow and heat cascade utilization (repeating the process of "alternating penetration of the material layer twice → temperature reduction → reheating → feeding into the next layer") until the gas reaches the upper outer drying section at the top of the vertical tower. By grouping the drying sections and designing the airflow paths, alternating hot air penetration directions can be achieved (for example, some drying sections use "outside to inside" and some use "inside to outside"), forming a cascade utilization and alternating cross-flow pattern, which greatly improves the uniformity of material drying.

[0054] S25 Dehumidification and Circulation Closed: The high-temperature and high-humidity gas discharged from the upper outer drying section at the top of the vertical tower enters the condensation and dehumidification system. Through condensation and molecular sieve adsorption, it becomes low-temperature dry gas again (dew point below -40℃). It is then sent into the inner cooling section of the vertical tower by a booster fan and other booster devices to start a new cycle.

[0055] When the number of drying sections inside and outside the vertical tower is 2, the repeating step S24 is omitted.

[0056] In one optional embodiment, in step S1, the inert gas entering the cooling section of the vertical tower body has a dew point of -40°C at atmospheric pressure. That is, the inert gas entering the cooling section of the inner annular air chamber through the gas inlet on the lower side wall of the vertical tower body has a very low water content.

[0057] In one alternative embodiment, the humid inert gas discharged from the humid gas outlet of the vertical tower has a dew point of 20~45°C at atmospheric pressure.

[0058] In one optional embodiment, in step S2, the dew point of the inert gas after condensation and dehumidification is -40°C at normal pressure. That is, the water content of the inert gas after condensation and dehumidification is very low.

[0059] The pressurization of the inert gas and the heating temperature of the heat exchangers on each gas pipeline are not specifically limited and can be adjusted according to the actual situation. In an optional embodiment, in steps S1 and S2, the inert gas can be pressurized to 3-10 kPaG.

[0060] In one optional embodiment, when there are two gas pipelines from bottom to top along the height of the vertical tower, the first heat exchanger on the first gas pipeline can heat the inert gas to 115-125°C; and the second heat exchanger on the second gas pipeline can heat the inert gas to 100-115°C.

[0061] In one alternative implementation, the process parameters of the entire drying process are controlled by a conventional control system such as a PLC control system.

[0062] The resin drying apparatus provided by this invention can also be used for the removal of VOCs from resins.

[0063] The resin drying method provided by this invention can remove VOCs (volatile organic compounds, such as toluene, benzene, ethyl acetate, etc.) from the resin while drying it.

[0064] 1. The resin drying device provided by the present invention includes a vertical tower, a heating system, a condensation and dehumidification system and a control system. In use, an inert gas is used as the drying medium, and a closed loop is formed between the vertical tower, the heating system and the condensation and dehumidification system. By coaxially arranging inner and outer annular Johnson nets within the vertical tower, an annular columnar material channel, an inner annular air chamber, and an outer annular air chamber are formed from top to bottom. The inner and outer annular air chambers are divided along the height direction by horizontal annular baffles. The divided inner / outer cooling sections and each drying section are sequentially connected to the gas pipelines containing heat exchangers in the heating system, thus forming an S-shaped path between the vertical tower and the heating system. This allows the inert gas within the vertical tower to flow in an alternating cross-flow pattern: In the inner / outer cooling sections, the gas penetrates the material layer radially outward from the inner cooling section, recovering the sensible heat in the material to achieve self-preheating; the preheated gas is then heated sequentially through the outer cooling section and the gas pipeline heat exchanger connected to the outer cooling section, and then, starting from the bottom outer drying section, penetrates the material layer of different drying sections in an alternating radial direction (from outside to inside / from inside to outside). After passing through each drying section, the gas is reheated by the heat exchanger before entering the next drying section, forming a heat cascade utilization and alternating cross-flow drying. When using this resin drying device to dry resin, it can achieve uniform and efficient drying, ultimate heat recovery and integrated drying and cooling, and is especially suitable for safe and energy-saving drying of easily oxidized resins.

[0065] Specifically, (1) the resin drying device can achieve the ultimate energy saving effect: through the thermodynamic circulation form of "heat absorption in the cooling section + multi-stage heating of the drying gas during the drying process", it ensures that the cooling section recovers and utilizes the sensible heat of the discharged material to preheat the circulating gas, reducing the load on the heat exchanger. The multi-stage heating technology accurately replenishes the heat lost by the gas in the drying section, avoiding the drying driving force attenuation and energy waste caused by the gradual decrease of gas temperature after traditional single heating, and the overall system energy efficiency is extremely high. (2) the resin drying device has excellent drying uniformity for materials: through the design of the inner ring air chamber and the outer ring air chamber, combined with the segmentation of the two, the direction of radial gas penetration (from inside to outside or from outside to inside) can be flexibly switched in different drying sections, forming alternating crossflow, so that the resin particles can obtain uniform heat and mass transfer effect at each radial position of the annular cross section, solving the inherent problem of uneven drying of the annular moving bed. (3) The resin drying device integrates the drying and cooling processes of the material in terms of equipment structure and gas flow, while ensuring the safety of operation: the material drying, sensible heat recovery and gas treatment are integrated into a single vertical tower and a closed-loop system formed by the vertical tower, heating system and condensation dehumidification system, which is compact and simple. The device uses inert gas (nitrogen) circulation throughout the process, which can completely isolate oxygen and safely solve the drying problem of easily oxidized resin. In addition, the highly integrated design of the device simplifies the process flow, which not only reduces equipment investment and floor space, but also avoids the risk of moisture absorption and pyrolysis during the transportation of high-temperature materials. (4) The resin drying device is stable and reliable in operation. Its Johnson mesh has high strength and excellent porosity, which can reliably support the material to form a stable moving bed and ensure uniform airflow distribution. The material falls steadily in the annular channel by gravity without mechanical stirring, which reduces particle wear and dust generation. At the same time, the material presents a plug flow state with uniform residence time and uniform heating, which ensures the consistency and uniformity of product quality. (5) The resin drying device is precisely and flexibly controlled: the inlet temperature of each drying section can be independently adjusted through the corresponding heat exchanger, which can accurately control the drying according to the different moisture content stages of the resin, thereby optimizing the process curve and effectively protecting the product quality. (6) The resin drying device has the advantages of energy saving and consumption reduction: the radial thickness of the annular material channel is designed to be 100-400mm, and the resistance when hot air penetrates the material layer is small, which can significantly reduce the power consumption of the blower to transport gas.

[0066] 2. The resin drying method provided by the present invention, by using the resin drying device provided by the present invention, can achieve uniform and efficient drying of resin and effective heat recovery, and is particularly suitable for safe and energy-saving drying of easily oxidized resins.

[0067] 3. The resin drying apparatus and resin drying method provided by the present invention can remove VOCs (volatile organic compounds, such as toluene, benzene, ethyl acetate, etc.) from the resin while drying it. Attached Figure Description

[0068] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0069] Figure 1 This is a schematic diagram of a resin drying apparatus provided by the present invention;

[0070] Figure 2 for Figure 1 Cross-sectional view of the internal structure of the neutral tower;

[0071] Figure 3 for Figure 1 A schematic diagram of the cross-section of the internal structure of a neutral tower.

[0072] Wherein, H1-first heat exchanger; H2-second heat exchanger; 1-vertical tower body; 2-inner annular Johnson mesh; 3-outer annular Johnson mesh; 4-annular material channel; T1-discharge rotary valve; 5-top material distribution area; 6a-second inner drying section; 6b-upper second outer drying section; 6c-lower second outer drying section; 7a-first inner drying section; 7b-upper first outer drying section; 7c-lower first outer drying section; 8a-inner cooling section; 8b-outer cooling section; 9-inner annular air chamber; 10-outer annular air chamber; 11-bottom discharge area; 12-inner annular partition plate; 13-outer annular partition plate; X1-condensation dehumidification system; C1-booster compressor. Detailed Implementation

[0073] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments to further understand the purpose, solution and effect of the present invention, but it is not intended to limit the scope of protection of the appended claims.

[0074] This specification and the claims use certain terms to refer to specific components or parts. Those skilled in the art will understand that users or manufacturers may use different names or terms to refer to the same component or part. This specification and the claims do not distinguish components or parts by differences in name, but rather by differences in function. The terms "comprising" and "including" used throughout this specification and the claims are open-ended and should be interpreted as "including but not limited to". Furthermore, the term "connection" here includes any direct and indirect electrical connection means. Indirect electrical connection means include connections made through other means.

[0075] It should be noted that in the description of this invention, the terms "top," "bottom," "upper part," "lower part," "vertical," "side wall," "lower layer," "upper," "lower," "upper end," "lower end," "inner," and "outer," etc., indicate the orientation or positional relationship or parameters based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, a specific size, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0076] Example 1

[0077] This embodiment provides a resin drying device, such as... Figures 1 to 3 As shown, it includes a vertical tower body 1, a heating system, a condensation and dehumidification system X1, and a control system. The control system is a conventional control system, such as a PLC control system, which is connected to the vertical tower body and the heating system via signal transmission. Figure 1 The arrows inside the neutral tower body 1 indicate the direction of gas flow.

[0078] The heating system includes two gas pipelines containing heat exchangers. From bottom to top, they are the first gas pipeline containing the first heat exchanger H1 and the second gas pipeline containing the second heat exchanger H2. The number of gas pipelines can be adjusted according to actual needs. It is not limited to 2, but can also be 3, 4, 5, 6, 7, 8, 10, etc.

[0079] The vertical tower body 1 has a feed inlet at the top and a discharge outlet at the bottom. A humid gas outlet is located on the upper side wall, and a gas inlet is located on the lower side wall. The interior of the vertical tower body 1 is coaxially equipped with an inner annular Johnson mesh 2 and an outer annular Johnson mesh 3, forming an annular material channel 4. The upper end of the annular material channel 4 is connected to the feed inlet via a top distributor (not shown in the figure), and a radar level gauge is installed at the feed inlet. The lower end of the annular material channel 4, located in a conical area below the inner cooling section 8a, is the bottom discharge area 11. The bottom discharge area 11 is connected to the discharge outlet, and a discharge rotary valve T1 is installed at the discharge outlet. The annular width (i.e., radial thickness) of the annular material channel 4 is 300 mm. The top distributor, via the top distribution area 5 (located between the top of the annular material channel 4 and the top of the inner annular air chamber 9 described below), is used to evenly distribute the material within the annular material channel 4, forming a stable moving bed. Other industry-standard distributors can also be used, as long as they ensure even material distribution within the annular material channel. The radar level gauge is used to monitor the material height within the annular material channel. Other industry-standard ultrasonic level gauges, laser level gauges, etc., can also be used, as long as they effectively monitor the material height within the annular material channel.

[0080] The inner annular Johnson mesh 2 independently encloses to form the inner annular air chamber 9, and the outer annular Johnson mesh 3, together with the inner wall of the vertical tower, encloses to form the outer annular air chamber 10. The inner annular air chamber 9 is vertically divided from bottom to top by an inner annular partition plate 12 into independent inner cooling sections 8a, a first inner drying section 7a, and a second inner drying section 6a (vertically, the inner cooling sections 8a, the first inner drying section 7a, and the second inner drying section 6a are not interconnected and gas is not allowed to pass through them). The outer annular air chamber 10 is vertically divided from bottom to top by an outer annular partition plate 12... The partition plate 13 divides the space into an outer cooling section 8b, a first outer drying section (upper first outer drying section 7b + lower first outer drying section 7c), and a second outer drying section (upper second outer drying section 6b + lower second outer drying section 6c). (Vertically, the outer cooling section 8b, the first outer drying section, and the second outer drying section are not connected to each other, and gas is not allowed to pass through them.) The inner cooling section 8a has the same height as the outer cooling section 8b, the first inner drying section 7a has the same height as the first outer drying section, and the second inner drying section 6a has the same height as the second outer drying section. The number of drying sections within the inner and outer annular air chambers can be adjusted according to actual needs, and is not limited to just two drying sections. The diameter of the inner annular air chamber 9 and the ring width of the outer annular air chamber 10 can be selected according to actual conditions; for example, the diameter of the inner annular air chamber is generally 200-1200 mm, and the ring width of the outer annular air chamber is 100-600 mm.

[0081] The first and second outer drying sections are further divided by the outer annular partition plate 13 into an upper first outer drying section 7b and a lower first outer drying section 7c, an upper second outer drying section 6b and a lower second outer drying section 6c (in the vertical direction, the upper first outer drying section 7b and the lower first outer drying section 7c, as well as the upper second outer drying section 6b and the lower second outer drying section 6c, are not connected and gas is not allowed to pass through). The heights of the upper first outer drying section 7b and the lower first outer drying section 7c can be the same or different, and the heights of the upper second outer drying section 6b and the lower second outer drying section 6c can be the same or different, preferably the same to improve the uniformity of drying. A first circulation outlet is located on the side wall of the vertical tower body corresponding to the position of the external cooling section. A second circulation outlet is located on the side wall of the vertical tower body 1 corresponding to the position of the upper first external drying section 7b. A humid gas outlet is located on the side wall of the vertical tower body 1 corresponding to the position of the upper second external drying section 6b. A first circulation inlet is located on the side wall of the vertical tower body 1 corresponding to the position of the lower first external drying section 7c. A second circulation inlet is located on the side wall of the vertical tower body 1 corresponding to the position of the lower second external drying section 6c. The first circulation outlet and the first circulation inlet are connected via a first gas pipeline containing a first heat exchanger H1, a first valve for controlling gas flow, a first temperature sensor, a first pressure sensor, and a first flow sensor. The second circulation outlet and the second circulation inlet are connected via a second gas pipeline containing a second heat exchanger H2, a second valve for controlling gas flow, a second temperature sensor, a second pressure sensor, and a second flow sensor. Temperature sensors, pressure sensors, flow sensors, etc., are used to detect parameters such as temperature, pressure, and flow. The heating power of the first heat exchanger and the first heat exchanger can be independently adjusted to control the temperature of the circulating gas entering the corresponding drying section within a set range.

[0082] In this design, the filaments of both the inner annular Johnson mesh 2 and the outer annular Johnson mesh 3 are arranged perpendicularly. The groove width can be selected according to the material size, ensuring that the material cannot pass through the Johnson mesh; it is generally about 0.5-1.2 mm. The maximum gap size of both the inner annular Johnson mesh 2 and the outer annular Johnson mesh 3 is smaller than the minimum particle size of the resin. This is to ensure that the inner annular air chamber 9, the outer annular air chamber 10, and the annular material channel 4 are used only for gas passage and to block material.

[0083] The wet gas outlet on the upper side wall of the vertical tower body 1 is connected to the inlet of the condensation and dehumidification system X1. The outlet of the condensation and dehumidification system X1 is connected to the gas inlet on the lower side wall of the vertical tower body via a pipeline containing a pressurizing device (such as a booster C1) and detection elements such as pressure sensors and flow sensors for detecting pressure and flow. The gas inlet on the lower side wall of the vertical tower body is connected to the inner cooling section 8a of the inner ring air chamber 9.

[0084] In this embodiment, the condensation dehumidification system X1 is a combination of a condenser and a refrigerated adsorption dryer. This combined refrigerated condenser can cool the high-humidity gas from the outlet of the vertical tower to below its dew point temperature, reducing the gas moisture content to -40°C or lower. Alternatively, a pneumatic condensation dehumidification system or a zeolite molecular sieve rotary adsorption dehumidifier can be used, as long as the moisture in the high-humidity gas can be removed to meet the drying requirements.

[0085] Example 2

[0086] This embodiment provides a resin drying method using the resin drying apparatus in Embodiment 1 (wherein the annular material channel has a width of 300 mm, the inner annular air chamber has a diameter of 400 mm, and the outer annular air chamber has a width of 600 mm), comprising the following steps:

[0087] S1: Dry, cold nitrogen gas is pressurized to 5 kPaG and enters the internal cooling section from the gas inlet. It then flows in a continuous S-shaped path between the vertical tower body and the heating system, and finally exits from the wet gas outlet. The discharged nitrogen gas is dehumidified by a condenser + refrigeration adsorption dryer until the moisture content is reduced to below the dew point of -40℃. After being pressurized to 5 kPaG again, it is circulated back into the vertical tower body from the gas inlet, forming a closed loop of nitrogen gas, so that the vertical tower body is filled with flowing dry nitrogen gas.

[0088] The continuous S-shaped path flow is as follows:

[0089] Dry, cold nitrogen gas enters the inner cooling section through the gas inlet on the lower side wall of the vertical tower, then radially passes through the annular material channel (since no material has been added to the annular material channel at this time, the nitrogen gas will also fill the annular material channel upwards) and the outer cooling section. The nitrogen gas discharged through the first circulation outlet enters the first gas pipeline and is heated to 115-125°C by the first heat exchanger. Then, it enters the lower first outer drying section through the first circulation inlet, then radially passes through the annular material channel into the first inner drying section. In the first inner drying section, it rises and radially passes through the annular material channel into the upper first outer drying section. Then, it enters the second gas pipeline through the second circulation outlet and is heated to 100-115°C by the second heat exchanger. Then, it enters the lower second outer drying section through the second circulation inlet, then radially passes through the annular material channel into the second inner drying section. In the second inner drying section, it rises and radially passes through the annular material channel, and finally, it is discharged through the wet gas outlet on the upper side wall of the vertical tower.

[0090] S2: After the entire drying device is filled with flowing nitrogen, wet resin with a water content of 1wt%~25wt% (25wt% wet resin is used in this embodiment, with a particle size range of 1.5-4mm) is continuously and evenly added into the annular material channel through the feed inlet via the top distributor. This allows the wet resin to be continuously filled and evenly distributed in the annular material channel, and under the action of gravity, it forms a stable moving bed that moves downward. During the downward movement, it is radially dried by inert gas flowing in a continuous S-shaped path between the inner drying section and the outer drying section at the same height (for the wet resin, nitrogen passes through the wet resin radially from the inside to the outside and from the outside to the inside, forming an alternating cross-flow pattern for drying). Finally, after the sensible heat is absorbed by the nitrogen between the inner cooling section and the outer cooling section, it is continuously discharged through the outlet. The water content of the discharged dried resin is 500-1000ppm.

[0091] The nitrogen circulation process in step S2 is as follows:

[0092] S21 Cooling and Initial Heating: After condensation and dehumidification by a condenser and a freeze adsorption dryer, low-temperature nitrogen gas at approximately 10-20°C (with water content reduced to a dew point of -40°C) is driven by a booster fan (pressurized to 5 kPaG). It first enters the inner cooling section of the inner ring air chamber through the gas inlet, and then passes radially from the inside out through the high-temperature dried resin layer at approximately 110-120°C in the corresponding cooling section of the annular material channel. During this process, the low-temperature circulating nitrogen gas absorbs the sensible heat in the resin and is preheated to approximately 60-80°C. The dried resin is then cooled to below approximately 40°C and discharged from the outlet.

[0093] S22 First-stage heating and drying: Nitrogen gas, preheated to approximately 60-80°C, enters the first gas pipeline through the external cooling section and the first circulation outlet. After being heated by the first heat exchanger on the first gas pipeline (heated to the target temperature of 115-125°C by external heat source heat transfer oil), it enters the lower first external drying section through the first circulation inlet. It then passes radially from the outside to the inside through the corresponding resin layer in the annular material channel and the first internal drying section. In the first internal drying section, the hot gas flows upward and then radially from the inside to the outside through the corresponding resin layer in the annular material channel to enter the upper first external drying section, where the resin is heated and dehydrated. The gas releases heat here and decreases to 85-100°C, and then is discharged from the second circulation outlet.

[0094] S23 Secondary Heating and Re-drying: The cooled gas discharged from the second circulation outlet is introduced into the second heat exchanger on the second gas pipeline for intermediate reheating to 100-115℃. Then, the reheated hot gas enters the lower second outer drying section through the second circulation inlet, and then radially penetrates the corresponding resin layer in the annular material channel from the outside in to dry the resin. It then enters the second inner drying section, where the hot gas flows upwards and radially passes through the corresponding resin layer in the annular material channel from the inside out to heat and dehydrate the resin. The dehydrated resin is approximately 110-120℃. The humid gas (approximately 60-70℃) that has absorbed moisture enters the upper second outer drying section and is discharged from the humid gas outlet.

[0095] S24 Dehumidification and Circulation Closure: High-humidity gas at 60-70℃ enters the refrigeration adsorption condenser and, through condensation, becomes low-temperature dry gas at approximately 10-20℃ (dew point below -40℃). After being pressurized by the booster fan, it is sent back to the internal cooling section of the vertical tower to begin a new cycle.

[0096] The entire drying process parameters are precisely integrated and regulated by a PLC control system. After receiving the material level data signal from the radar level gauge, the PLC control system sends control commands to the feeding valve at the top inlet to control the feeding rate. Simultaneously, it controls the rotation speed of the discharge rotary valve at the bottom outlet of the vertical tower to control the downward movement speed of the material within the tower, thus achieving continuous resin feeding and discharging. After receiving the detection data from the various temperature sensors, the PLC control system sends control commands to the corresponding heat exchangers to achieve precise control of the heating quantity. After receiving pressure and flow data signals from the pressure and flow sensors on the pressurization device and various gas pipelines, the PLC control system sends commands to the pressurization device and corresponding valves to adjust their operating status and valve opening, thereby precisely controlling the gas pressure and flow rate.

[0097] Example 3

[0098] This embodiment provides a resin drying method, which is also applicable to the deep removal of VOCs (toluene, benzene, ethyl acetate, etc.) from resin. It uses the resin drying apparatus from Example 1 (wherein the annular material channel has a ring width of 300 mm, the inner annular air chamber has a diameter of 400 mm, and the outer annular air chamber has a ring width of 600 mm), and includes the following steps:

[0099] S1: Dry, VOC-free cold nitrogen gas is pressurized to 8 kPaG and enters the internal cooling section from the gas inlet. It then flows in a continuous S-shaped path between the vertical tower body and the heating system, and finally exits from the wet gas outlet. The discharged nitrogen gas is then pressurized again to 8 kPaG through a condenser + freeze adsorption dryer (if the gas discharged from the wet gas outlet contains VOCs, the condenser + freeze adsorption dryer can remove more than 95% of the VOCs and reduce the moisture content to below the dew point of -40℃). It then circulates back into the vertical tower body from the gas inlet, forming a closed loop of nitrogen gas, so that the vertical tower body is filled with flowing, dry nitrogen gas that contains no or trace amounts of VOCs.

[0100] The continuous S-shaped path flow is as follows:

[0101] Dry, cold nitrogen gas enters the inner cooling section through the gas inlet on the lower side wall of the vertical tower, then radially passes through the annular material channel (since no material has been added to the annular material channel at this time, the nitrogen gas will also fill the annular material channel upwards) and the outer cooling section. The nitrogen gas discharged through the first circulation outlet enters the first gas pipeline and is heated to 115-125°C by the first heat exchanger. Then, it enters the lower first outer drying section through the first circulation inlet, then radially passes through the annular material channel into the first inner drying section. In the first inner drying section, it rises and radially passes through the annular material channel into the upper first outer drying section. Then, it enters the second gas pipeline through the second circulation outlet and is heated to 100-115°C by the second heat exchanger. Then, it enters the lower second outer drying section through the second circulation inlet, then radially passes through the annular material channel into the second inner drying section. In the second inner drying section, it rises and radially passes through the annular material channel, and finally, it is discharged through the wet gas outlet on the upper side wall of the vertical tower.

[0102] S2: After the entire drying device is filled with flowing nitrogen, resin with a VOC (i.e., toluene, benzene, ethyl acetate, etc.) content of 500-2000ppm (in this embodiment, resin with a VOC content of 1000ppm and a particle size range of 3-4mm) is continuously and evenly added into the annular material channel through the feed inlet via the top distributor. This allows the VOC-containing wet resin to be continuously filled and evenly distributed in the annular material channel, forming a stable moving bed that moves downward under gravity. During the downward movement, the nitrogen flowing in a continuous S-shaped path dries the resin radially between the inner drying section and the outer drying section at the same height (for the VOC-containing wet resin, the nitrogen passes through the VOC-containing wet resin radially from the inside to the outside and from the outside to the inside, forming an alternating cross-flow pattern for drying). Finally, the resin, after having its sensible heat and VOC absorbed by the nitrogen between the inner cooling section and the outer cooling section, is continuously discharged through the outlet. The final VOC content of the discharged devolatilized resin is <30ppm.

[0103] The nitrogen circulation process in step S2 is as follows:

[0104] S21 Cooling and Initial Heating: Low-temperature nitrogen gas at approximately 10-20℃ (moisture content reduced to dew point -40℃) is condensed and removed from more than 95% of VOCs by a condenser and a freeze adsorption dryer. Driven by a booster fan (pressurized to 8kPaG), it first enters the inner cooling section of the inner ring air chamber from the gas inlet, and then passes radially from the inside out through the corresponding cooling section of the annular material channel, where the volatilized high-temperature dried resin material layer at approximately 110-120℃ has been dried. During this process, the low-temperature circulating nitrogen gas absorbs the sensible heat in the resin and is preheated to approximately 60-80℃. The dried resin is cooled to below approximately 40℃ and discharged from the outlet.

[0105] S22 First-stage heating and drying: Nitrogen gas, preheated to approximately 60-80°C, enters the first gas pipeline through the external cooling section and the first circulation outlet. After being heated by the first heat exchanger on the first gas pipeline (heated to the target temperature of 115-125°C by external heat source heat transfer oil), it enters the lower first external drying section through the first circulation inlet. It then passes radially from the outside to the inside through the corresponding resin layer in the annular material channel and the first internal drying section. In the first internal drying section, the hot gas flows upward and then radially from the inside to the outside through the corresponding resin layer in the annular material channel to enter the upper first external drying section, where the resin is heated, dehydrated, and volatilized. The gas releases heat here and decreases to 85-100°C, and then is discharged from the second circulation outlet.

[0106] S23 Secondary Heating and Re-drying: The cooled gas discharged from the second circulation outlet is introduced into the second heat exchanger on the second gas pipeline for intermediate reheating to 115-125℃. Then, the reheated hot gas enters the lower second outer drying section through the second circulation inlet, and then radially penetrates the corresponding resin layer in the annular material channel from the outside in to dry the resin. It then enters the second inner drying section, where the hot gas flows upwards and radially passes through the corresponding resin layer in the annular material channel from the inside out to heat and dehydrate the resin. The dehydrated resin, at approximately 110-120℃, containing VOC gas (approximately 60-70℃), enters the upper second outer drying section and exits through the wet gas outlet.

[0107] S24 Dehumidification and Circulation Closure: VOC-containing gas at 60-70℃ enters the refrigeration adsorption condenser and, through condensation, becomes dry gas at a low temperature of about 10-20℃ (dew point below -40℃ and VOC content <100ppm). After being pressurized by the booster fan, it is sent back to the internal cooling section of the vertical tower to start a new cycle.

[0108] The entire drying process parameters are precisely integrated and regulated by a PLC control system. After receiving the material level data signal from the radar level gauge, the PLC control system sends control commands to the feeding valve at the top inlet to control the feeding rate. Simultaneously, it controls the rotation speed of the discharge rotary valve at the bottom outlet of the vertical tower to control the downward movement speed of the material within the tower, thus achieving continuous resin feeding and discharging. After receiving the detection data from the various temperature sensors, the PLC control system sends control commands to the corresponding heat exchangers to achieve precise control of the heating quantity. After receiving pressure and flow data signals from the pressure and flow sensors on the pressurization device and various gas pipelines, the PLC control system sends commands to the pressurization device and corresponding valves to adjust their operating status and valve opening, thereby precisely controlling the gas pressure and flow rate.

Claims

1. A resin drying apparatus, comprising: The tower body has a feed inlet at the top, a discharge outlet at the bottom, a humid gas outlet on the upper side wall, and a gas inlet on the lower side wall. The heating system includes at least one gas pipeline containing a heat exchanger. The condensation dehumidification system has an inlet connected to the outlet of the humid gas and an outlet connected to the gas inlet. The control system is connected to the vertical tower body and the heating system respectively via signal transmission; The vertical tower body is characterized by having inner and outer annular Johnson nets coaxially arranged inside, forming an annular material channel between the inner and outer annular Johnson nets, with the inner annular Johnson net independently enclosing to form an inner annular air chamber, and the outer annular Johnson net enclosing with the inner wall of the vertical tower body to form an outer annular air chamber. The annular material channel is connected to the inlet and the outlet respectively, and the annular width of the annular material channel is 100-400mm; The inner ring air chamber is vertically divided into a bottom inner cooling section and at least two inner drying sections; the outer ring air chamber is vertically divided into a bottom outer cooling section and an outer drying section with the same number of inner drying sections; the inner cooling section and the outer cooling section have the same height, and the number of inner drying sections and outer drying sections is counted sequentially from bottom to top, with the inner drying section having the same height as the corresponding outer drying section; The gas inlet is connected to the inner cooling section of the inner ring air chamber via a pressurization device; Each of the aforementioned external drying sections is divided into an upper external drying section and a lower external drying section. A circulation outlet is provided on the side wall of the vertical tower body corresponding to the positions of the upper external drying section and the external cooling section. A circulation inlet is provided on the side wall of the vertical tower body corresponding to the position of the lower external drying section. Each circulation outlet and its uppermost circulation inlet are connected via a gas pipeline containing a heat exchanger. The circulation outlet on the side wall of the vertical tower body, corresponding to the uppermost upper external drying section, is the humid gas outlet. The maximum gap size of the inner and outer annular Johnson mesh is smaller than the minimum particle size of the resin.

2. The resin drying apparatus according to claim 1, characterized in that, The upper outer drying section and the lower outer drying section may have the same or different heights.

3. The resin drying apparatus according to claim 1, characterized in that, The inner and outer ring-shaped Johnson mesh fibers are arranged vertically; and / or The groove width of the inner and outer annular Johnson mesh is 0.5-1.2 mm.

4. The resin drying apparatus according to claim 1, characterized in that, The number of both the inner drying section and the outer drying section is 2-10.

5. The resin drying apparatus according to claim 1, characterized in that, The inner ring air chamber has a circular cross-section with a diameter of 200-1200 mm.

6. The resin drying apparatus according to claim 1, characterized in that, The outer ring width of the air chamber is 100-600mm.

7. The resin drying apparatus according to claim 1, characterized in that, The condensation dehumidification system includes a condenser and a refrigerated adsorption dryer; and / or The control system is a PLC control system.

8. A method for drying resin, characterized in that, The resin drying apparatus according to any one of claims 1-7 comprises the following steps: S1: After the inert gas is pressurized, it enters the internal cooling section from the gas inlet, and then flows in a continuous S-shaped path between the vertical tower body and each gas pipeline. Finally, it is discharged from the wet gas outlet. The discharged inert gas is condensed and dehumidified, and then pressurized again before circulating back into the vertical tower body from the gas inlet, forming a closed loop of inert gas, so that the vertical tower body is filled with flowing inert gas. S2: Wet resin is continuously added to the annular material channel from the feed inlet, forming a moving bed that moves downward. During the downward movement, it is radially dried by inert gas flowing in a continuous S-shaped path between the inner drying section and the outer drying section at the same height. Finally, after the sensible heat is absorbed by the inert gas between the inner cooling section and the outer cooling section, it is continuously discharged through the discharge port. The inert gas is heated in each of the gas pipelines as it flows in a continuous S-shaped path; The process parameters for the entire drying process are controlled by the control system.

9. The resin drying method according to claim 8, characterized in that, The temperature of the inert gas inside the vertical tower decreases from bottom to top along the height of the vertical tower.

10. The resin drying method according to claim 8, characterized in that, In step S1, the inert gas entering the cooling section of the vertical tower has a dew point of -40°C at atmospheric pressure; and / or The humid inert gas discharged from the humid gas outlet of the vertical tower has a dew point of 20~45℃ at normal pressure; and / or In step S2, the dew point of the inert gas after condensation and dehumidification is -40℃ at normal pressure.

11. The resin drying method according to claim 8, characterized in that, In steps S1 and S2, the inert gas is pressurized to 3-10 kPaG; and / or When there are two heat exchangers in the gas pipeline along the height of the vertical tower body from bottom to top, the first heat exchanger heats the inert gas to 115-125℃; the second heat exchanger heats the inert gas to 100-115℃.

12. The application of the resin drying apparatus according to any one of claims 1-7 or the resin drying method according to any one of claims 8-11 in the removal of VOCs from resin.

Images