Pellet post-treatment conveying system

Abstract

The application relates to the field of high polymer material production equipment, in particular to a granule post-treatment conveying system, which comprises, in sequence, an underwater pelletizing unit, a first solid-liquid separator, a desorption unit, a hydraulic conveying unit, a drying and dewatering unit, a screening unit, a vertical pneumatic conveying unit and a blending and homogenizing unit; the desorption unit comprises a residence tank and a heating piece; the residence tank is provided with a gas collecting pipe; solid-liquid mixture is put into the residence tank through a feeding pipe; the heating piece is used for heating the solid-liquid mixture; the granule stays in the residence tank; the water body heats the granule so that VOC organic volatile matters are desorbed from the granule; after the VOC organic volatile matters are desorbed, the VOC organic volatile matters are diffused to a VOC centralized treatment unit through the gas collecting pipe; and the granule from which the VOC organic volatile matters are removed is conveyed to the hydraulic conveying unit through a discharging pipe. In the application, the waste heat of the cut granule and the pelletizing water is fully utilized, so that only a small amount of energy is needed to heat the water body, the VOC organic volatile matters are desorbed from the granule, and the energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high polymer material production equipment, and in particular to a granule post-processing conveying system. BACKGROUND

[0002] Polyolefin belongs to one kind of thermoplastic plastic, and polyolefin can be used to make plastic products by injection molding or blow molding. In the prior art, the general production process of polyolefin powder to granules is as follows: 1. extruding a material strip by an extruder → 2. underwater pelletizing the material strip → 3. dehydrating and drying the granules → 4. screening → 5. conveying the granules by pneumatic force → blending and homogenizing. By conveying the granules by pneumatic force, the friction and collision between the granules and the equipment and between the granules will generate dust and stringing; thus, the quality of the granules is reduced, and more energy needs to be consumed.

[0003] A polyolefin granule post-processing system is disclosed in Chinese Patent Application No. CN202010580313.4; after underwater pelletizing the material strip, the granules are conveyed by hydraulic force to eliminate the conditions for generating dust from the granules and to reduce energy consumption.

[0004] In the production process of polyolefin granules, VOC organic volatile substances are left in the powder polymerization reaction section, and VOC organic volatile substances are generated in the extrusion granulation process; VOC organic volatile substances will have adverse effects on human health, and therefore, the polyolefin granule production plant will take certain measures to reduce the amount of VOC organic volatile substances in the polyolefin granules.

[0005] In the prior art, steam and hot air can be used to heat the granules to make the VOC organic volatile substances in the granules desorb from the high molecular polyolefin, and then the VOC organic volatile substances are taken away by the fluid, so as to reduce the amount of VOC organic volatile substances in the granules and improve the quality of the granules. In the prior art, energy needs to be continuously consumed to maintain the supply of steam or hot air, which greatly increases the energy consumption cost in the production of granules. SUMMARY

[0006] In order to reduce the treatment cost of VOC organic volatile substances in the granules and reduce energy consumption, the present application provides a granule post-processing conveying system.

[0007] The granule post-processing conveying system provided by the present application adopts the following technical solution:

[0008] The granule post-processing conveying system comprises, in sequence, an underwater pelletizing unit, a first solid-liquid separator, a desorption unit, a hydraulic conveying unit, a drying and dewatering unit, a screening unit, a vertical pneumatic conveying unit and a blending and homogenizing unit; the underwater pelletizing unit cuts the strip into granules, and the granules form a primary solid-liquid mixture with the water body; the first solid-liquid separator is used for concentrating the solid-liquid mixture; the concentrated solid-liquid mixture is conveyed to the desorption unit through a pipeline; the desorption unit comprises a residence tank and a heating device; the residence tank is provided with a feeding pipe, a discharging pipe and a gas collecting pipe; the solid-liquid mixture is fed into the residence tank through the feeding pipe; the heating device is used for heating the solid-liquid mixture; the granules stay in the residence tank; the water body heats the granules to make the VOC organic volatile matter desorb from the granules; the desorbed VOC organic volatile matter escapes to a VOC centralized treatment unit through the gas collecting pipe; and the granules from which the VOC organic volatile matter is removed are conveyed to the hydraulic conveying unit through the discharging pipe; and the hydraulic conveying unit conveys the granules through the water body.

[0009] By using the above technical scheme, the waste heat of the cut granules and the cutting water is fully utilized, so that only a small amount of energy is needed to heat the water body in the residence tank to make the VOC organic volatile matter desorb from the granules, thereby reducing the energy consumption and the cost of the granule post-processing process.

[0010] Optionally, the desorption unit further comprises a second solid-liquid separator, a hot water circulating tank and a hot water circulating pump; the heating device is used for heating the water body in the hot water circulating tank; the hot water circulating pump pumps the water body in the hot water circulating tank into the residence tank; the second solid-liquid separator is connected to the discharging pipe of the residence tank; the second solid-liquid separator is used for concentrating the solid-liquid mixture; the water body separated by the second solid-liquid separator is returned to the hot water circulating tank through a pipeline; part of the water body separated by the first solid-liquid separator is conveyed and mixed with the solid-liquid mixture concentrated by the second solid-liquid separator to reduce the temperature of the solid-liquid mixture; and the mixed solid-liquid mixture is conveyed through the hydraulic conveying unit.

[0011] By using the above technical scheme, the solid-liquid mixture is filtered twice by the first solid-liquid separator and the second solid-liquid separator; since the waste heat of the strip in the extrusion process is fully utilized, the heat supplement of the desorption unit only needs to consider a temperature difference of about 5℃ of the water body in the hot water circulating tank; that is, only a small amount of steam consumption is needed to achieve effective desorption of the VOC organic volatile matter; and the energy consumption is greatly reduced, thereby reducing the cost of the granule post-processing.

[0012] Optionally, the desorption unit comprises at least two residence tanks; and a plurality of the residence tanks are connected in sequence through pipelines, so that the solid-liquid mixture flows through the plurality of residence tanks in sequence.

[0013] By adopting the above technical scheme, the residence time of the granules in the residence tank can be ensured, and the uniformity of the water body heating the granules is improved; thus, the uniformity of the VOC organic volatile matter desorption in different granules is improved, and the VOC organic volatile matter desorption effect is improved.

[0014] Optionally, the residence tank comprises a tank body and a stirring assembly, the stirring assembly comprises a driving member, a rotating shaft and a stirring paddle, the rotating shaft is vertically arranged, the driving member is fixedly arranged on the tank body, and the driving member drives the rotating shaft to rotate, and the stirring paddle is fixedly connected with the rotating shaft.

[0015] By adopting the above technical scheme, the stirring assembly and the flowing water body can destroy the stagnant flow layer on the surface of the granules, reduce the mass transfer resistance of the VOC organic volatile matter, so as to facilitate the VOC organic volatile matter to be desorbed from the high molecular polyolefin in the granules and enter the water body, and improve the VOC removal efficiency.

[0016] Optionally, the residence tank comprises a flow slowing assembly, the flow slowing assembly comprises a plurality of flow slowing plates, the flow slowing plates are fixedly connected with the inner circumferential wall of the tank body, the flow slowing plates are provided with mounting holes for the rotating shaft to pass through, the flow slowing plates are provided with flow-through openings for the water body to pass through, the top of each flow slowing plate is provided with a first downward inclined guide surface, and the bottom of each flow slowing plate is provided with a second upward inclined guide surface, the granules flow along the first guide surface to the flow-through opening, and the desorbed gas monomer flows along the second guide surface to the flow-through opening; the flow-through openings of the plurality of flow slowing plates are staggered on both sides of the central axis of the tank body, so that the water body flows from top to bottom through the plurality of flow slowing plates, and the stirring paddle is arranged between adjacent flow slowing plates.

[0017] By adopting the above technical scheme, the flow path of the solid-liquid mixture in the residence tank is prolonged, and the residence time of the granules in the residence tank is prolonged, so that the VOC organic volatile matter in the granules can be fully heated and desorbed.

[0018] Optionally, the desorption unit further comprises a gas dissolving structure, the gas dissolving structure comprises a gas dissolving tank, a first gas dissolving water conveying pipeline and a gas releasing device, the first gas dissolving water conveying pipeline passes through the tank body, one end of the first gas dissolving water conveying pipeline is connected with the gas dissolving tank, and the gas dissolving tank conveys gas dissolving water into the residence tank through the first gas dissolving water conveying pipeline; the gas releasing device is arranged on the first gas dissolving water conveying pipeline and communicates with the first gas dissolving water conveying pipeline, and the gas releasing device is used for releasing the supersaturated gas in the gas dissolving water in the form of tiny bubbles, and the released bubbles are used for capturing the desorbed VOC organic volatile matter gas.

[0019] By adopting the technical scheme, the bubbles released by the dissolved air water can capture the VOC organic volatile substances diffused into the water body during the floating process, so that the VOC organic volatile substances are carried from the water body to the upper region of the tank body, and more VOC organic volatile substances can be collected to the VOC centralized treatment unit through the gas collection pipeline, thereby improving the desorption effect of the VOC organic volatile substances.

[0020] Optionally, the plurality of dissolved air release devices are arranged along the first dissolved air water conveying pipeline.

[0021] By adopting the technical scheme, when the dissolved air release device releases the bubbles, the uniformity of the distribution of the bubbles in the tank body can be improved.

[0022] Optionally, the desorption unit comprises three stay tanks, which are sequentially named as a first stay tank, a second stay tank and a third stay tank, and the solid-liquid mixture flows through the first stay tank, the second stay tank and the third stay tank in sequence; the dissolved air structure is connected with the second stay tank, and the dissolved air structure conveys the dissolved air water into the second stay tank.

[0023] By adopting the technical scheme, the residence time of the granules in the stay tank can be ensured, and the uniformity of the heating of the granules by the water body is improved, so that the uniformity of the desorption of the VOC organic volatile substances in different granules is improved, and the desorption effect of the VOC organic volatile substances is improved.

[0024] Optionally, the dissolved air structure further comprises a rotary joint and a second dissolved air water conveying pipeline; the first dissolved air water conveying pipeline is connected with the rotating shaft in a rotating sealing manner through the rotary joint; a hollow section is arranged at an end of the rotating shaft away from the driving member, a flow channel is arranged in the hollow section, and the flow channel is connected with the first dissolved air water conveying pipeline; the second dissolved air water conveying pipeline is horizontally arranged on the rotating shaft, and the second dissolved air water conveying pipeline is connected with the flow channel; along the dissolved air water conveying direction, the second dissolved air water conveying pipeline is provided with the dissolved air release devices at intervals.

[0025] By adopting the technical scheme, when the rotating shaft rotates, the rotating shaft can drive the dissolved air release device to release the bubbles at different positions, so as to improve the uniformity of the distribution of the bubbles in the tank body, and improve the capturing efficiency and effect of the bubbles released by the dissolved air water on the VOC organic volatile substances in the water body.

[0026] Optionally, the second dissolved air water conveying pipeline comprises a first straight section, an arc section and a second straight section in sequence, the first straight section and the second straight section are arranged along the radial direction of the tank body, and the arc section is arranged along the inner circumferential wall of the tank body.

[0027] By adopting the technical scheme, the first straight line segment and the second straight line segment are arranged along the radial direction of the tank body, and the gas dissolving releaser is arranged on the first straight line segment and the second straight line segment, so that the uniformity of the gas bubbles released by the dissolved air water is further improved.

[0028] In summary, the present application has at least one of the following beneficial technical effects:

[0029] 1. The waste heat of the cut pellets and the cutting water is fully utilized, so that only a small amount of energy is needed to heat the water in the residence tank, so that the VOC organic volatile matter is desorbed from the pellets, thereby reducing energy consumption and reducing the cost of pellet post-processing process;

[0030] 2. The solid-liquid mixture is filtered twice by the first solid-liquid separator and the second solid-liquid separator. Since the waste heat of the material strip in the extrusion process is fully utilized, the heat supplement of the desorption unit only needs to consider the temperature difference of about 5°C of the water in the hot water circulating tank. That is, only a small amount of steam consumption is needed to achieve effective desorption of VOC organic volatile matter; at the same time, the energy consumption is greatly reduced, and the cost of pellet post-processing is reduced;

[0031] 3. The bubbles released by the dissolved air water will capture the VOC organic volatile matter diffused into the water during the floating process; thereby carrying the VOC organic volatile matter from the water to the upper region of the tank; so that more VOC organic volatile matter can be collected to the VOC centralized treatment unit through the gas collection pipeline, improving the desorption effect of VOC organic volatile matter. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a module schematic diagram of the pellet post-processing conveying system in Example 1.

[0033] Figure 2 is a structural schematic diagram of the pellet post-processing conveying system in Example 1.

[0034] Figure 3 is a structural schematic diagram of the underwater pelletizing unit in Example 1.

[0035] Figure 4 is a structural schematic diagram of the first solid-liquid separation unit in Example 1.

[0036] Figure 5 is a structural schematic diagram of the residence tank in Example 1.

[0037] Figure 6 is a structural schematic diagram of the residence tank in Example 2.

[0038] Figure 7 is a structural schematic diagram of the pellet post-processing conveying system in Example 2.

[0039] Figure 8is a structural schematic diagram of the desorption unit in Example 3.

[0040] Figure 9 is a structural schematic diagram of the gas dissolving structure in Example 4.

[0041] Figure 10 is a structural schematic diagram of the desorption unit in Example 5.

[0042] Figure 11 is a structural schematic diagram of the desorption unit in Example 6.

[0043] Figure 12 is Figure 11 is an enlarged view of A in FIG. 6.

[0044] Figure 13 is a structural schematic diagram of the gas dissolving structure in Example 6.

[0045] BRIEF DESCRIPTION OF DRAWINGS 1, extruder; 2, underwater pelletizing unit; 21, underwater pelletizer, 22, pelletizing water heat exchanger; 23, pelletizing water circulating pump; 24, pelletizing water return tank; 3, first solid-liquid separation unit; 31, first solid-liquid separator; 32, first water filter; 33, water amount control valve group; 4, desorption unit; 41, residence tank; 411, tank body; 4111, feed pipe; 4112, discharge pipe; 4113, gas collection pipe; 42, material pump; 43, stirring assembly; 431, driving member; 432, rotating shaft; 4321, flow channel; 433, stirring paddle; 44, flow slowing assembly; 441, flow slowing plate; 4411, first guide surface; 4412, second guide surface; 442, mounting hole; 443, flow passage; 48, gas dissolving structure; 481, gas dissolving tank; 482, first gas dissolving water conveying pipeline; 483, gas dissolving releaser; 484, rotary joint; 485, second gas dissolving water conveying pipeline; 4851, first straight line segment; 4852, arc segment; 4853, second straight line segment; 5, hydraulic conveying unit; 51, stirring feeder; 52, hydraulic conveying pump; 6, drying and dewatering unit; 7, screening unit; 8, vertical pneumatic conveying unit; 9, blending and homogenizing unit; 10, VOC centralized treatment unit; 11, vacuum member. DETAILED DESCRIPTION

[0046] The following description will be made in conjunction with the accompanying drawings. Figure 1 - the accompanying drawings Figure 13 The application is described in further detail.

[0047] Example 1

[0048] The embodiments of the application disclose a pellet post-treatment conveying system. Referring to Figure 1 and Figure 2The pellet post-processing conveying system comprises, in sequence, an underwater pellet cutting unit 2, a first solid-liquid separation unit 3, a desorption unit 4, a hydraulic conveying unit 5, a drying and dehydration unit 6, a screening unit 7, a vertical pneumatic conveying unit 8 and a blending and homogenizing unit 9.

[0049] With reference to Figure 2 and Figure 3 , the extruder 1 is a device for melting and plasticizing plastic powder and extruding the plastic powder into a strip. The underwater pellet cutting unit 2 comprises an underwater pellet cutting head 21, a pellet cutting water return tank 24, a pellet cutting water circulating pump 23 and a pellet cutting water heat exchanger 22. The underwater pellet cutting head 21 is arranged at the outlet of the extruder 1. The underwater pellet cutting head 21 cuts the molten extruded pellets into pellets under water, and the pellets are mixed with the pellet cutting water into a solid-liquid mixture. In this embodiment, the extrusion temperature of the strip is 220°C, the temperature of the pellet cutting water input into the underwater pellet cutting head 21 is 50-60°C, and the temperature of the solid-liquid mixture formed by mixing the pellets with the pellet cutting water is about 70°C.

[0050] Taking the granulation of polyolefin as an example, VOC organic volatile substances are left in the polymerization section of the plastic powder, and VOC organic volatile substances are also generated in the extrusion and granulation process. VOC organic volatile substances can have adverse effects on human health; therefore, the pellets need to be further treated to desorb VOC organic volatile substances from the pellets during the pellet post-processing and conveying process.

[0051] In polyolefin pellets, hydrocarbons are molecular crystals, and the adsorption between molecules is mainly based on van der Waals force, i.e. VOC organic volatile substances are adsorbed by high molecular polyolefin by van der Waals force.

[0052] Desorption is the reverse process of adsorption. Small-molecule VOC organic volatile substances need to absorb energy to overcome the van der Waals force between VOC organic volatile substances and high molecular polyolefin, so that VOC organic volatile substances are desorbed from high molecular polyolefin and escape to the external fluid environment. The desorption time of small-molecule VOC organic volatile substances is related to temperature; as long as there is a suitable desorption temperature and desorption time, VOC organic volatile substances in the pellets can be kept at a very low concentration.

[0053] With reference to Figure 2 and Figure 4 , the solid-liquid mixture is conveyed to the first solid-liquid separation unit 3, which comprises a first solid-liquid separator 31, a first water filter 32 and a water volume control valve group 33. The first solid-liquid separator 31 is used to separate the pellets and the water body in the solid-liquid mixture. The filtered pellets are conveyed to the desorption unit 4; the filtered water body is filtered again by the first water filter 32, part of the water body is reflowed back to the pellet cutting water return tank 24 through a branch, and part of the water body is conveyed to the desorption unit 4 through another branch provided with the water volume control valve group 33.

[0054] With reference to Figure 4 and Figure 5 The desorption unit 4 comprises a residence tank 41, a heating device and a material pump 42. In the present embodiment, the residence tank 41 comprises a tank body 411 for containing the solid-liquid mixture and a stirring assembly 43 for stirring the solid-liquid mixture.

[0055] The tank body 411 is provided with a feeding pipe 4111, a discharging pipe 4112 and a gas collecting pipe 4113. The granules separated from the first solid-liquid separation unit 3 are fed into the tank body 411 through the feeding pipe 4111. The heating device (not shown in the figure) can be in the form of an electric heating device, a heating jacket or a steam heating device, etc. The heating device is used to heat the solid-liquid mixture to increase the temperature of the water body in the tank body 411. In the present embodiment, the heating device heats the water body in the residence tank 41 to a temperature of 90°C. In other embodiments, the temperature in the residence tank 41 can also be 88°C, 89°C, 90.5°C, 91°C, etc.

[0056] The heating device heats the water body containing the granules from 70°C to 90°C, at which time the gaps between the granules are filled with high-temperature water body. The granules stay in the residence tank 41, and the high-temperature water body heats the granules; so that the VOC organic volatile substances absorb energy and desorb from the granules. After the VOC organic volatile substances that are insoluble in water desorb from the granules, they form bubbles in the water body and float up, and escape from the water body in the residence tank 41, and then the VOC organic volatile substances escape to the VOC centralized treatment unit 10 through the gas collecting pipe 4113. In the prior art, there are many ways to treat VOC organic volatile substances, such as activated carbon adsorption method, organic solvent adsorption method, condensation method, catalytic combustion method, etc. Therefore, the VOC centralized treatment unit 10 in the present embodiment can use any of the above methods to treat VOC organic volatile substances, and the specific structure of the VOC centralized treatment unit 10 is not described in detail in the present embodiment.

[0057] In the present embodiment, the residence time of the granules in the residence tank 41 is not less than 30 min, so that the VOC organic volatile substances in the granules can fully absorb energy and be fully desorbed. In other embodiments, the residence time of the granules in the residence tank 41 can also be 32 min, 30 min or 40 min, etc. The actual residence time of the granules in the residence tank 41 can be determined by the workers according to the solubility of the VOC organic volatile substances in the granules and the solubility of the granules in the solid-liquid mixture.

[0058] With reference to Figure 5The stirring assembly 43 comprises a driving member 431, a rotating shaft 432 and stirring blades 433. The rotating shaft 432 is vertically arranged. The driving member 431 is fixedly arranged on the tank body 411 and drives the rotating shaft 432 to rotate. The stirring blades 433 are fixedly connected with the rotating shaft 432. The stirring assembly 43 is used for stirring and mixing the solid-liquid mixture in the tank body 411, so that the granules are uniformly distributed in the water body, and the water body uniformly heats the granules, so that the VOC organic volatile matters in the granules fully absorb energy, and then the VOC organic volatile matters are desorbed, diffused and dispersed into the external gas. On the other hand, the stirring assembly 43 and the flowing water body can destroy the stagnant layer on the surface of the granules, reduce the mass transfer resistance of the VOC organic volatile matters, so as to facilitate the VOC organic volatile matters to be desorbed from the high molecular polyolefin in the granules and enter the water body, and improve the removal efficiency of the VOC.

[0059] With reference to Figure 2 and Figure 4 A vacuum member 11 is arranged on the pipeline between the gas collecting pipe 4113 and the VOC centralized treatment unit 10. The vacuum member 11 is used for extracting the gas in the inside of the residence tank 41, so that the tank top region of the residence tank 41 has a certain vacuum degree, so as to facilitate the VOC organic volatile matters to be dispersed from the water body to the tank top region of the residence tank 41, and then be collected to the VOC organic volatile matters. In this embodiment, the vacuum member 11 is a vacuum pump, and in other embodiments, the vacuum member 11 can also be an air extraction fan.

[0060] The volume of the tank body 411 can be determined according to the conveying flow of the solid-liquid mixture and the concentration of the granules in the solid-liquid mixture. For example, the conveying flow of the solid-liquid mixture into the tank body 411 is 204 t / h, and the residence time of the solid-liquid mixture in the tank body 411 is 30 min. The effective volume of the tank body 411 is 102 cubic meters, and the volume of the tank body is greater than 102 cubic meters, so as to reserve a vacuum region at the tank top. Thus, when the solid-liquid mixture flows into the tank body 411 and then flows out of the tank body 411, the granules can stay in the tank body 411 for 30 min.

[0061] With reference to Figure 4 The granules and the water body from which the VOC organic volatile matters are removed are discharged through the discharge pipe 4112. The material pump 42 in the desorption unit 4 pumps the solid-liquid mixture to the hydraulic conveying unit 5. The hydraulic conveying unit 5 conveys the granules through the water body.

[0062] With reference to Figure 4 In this embodiment, the hydraulic conveying unit 5 comprises a stirring feeder 51 and a hydraulic conveying pump 52. The pipeline of the hydraulic conveying unit 5 is horizontally arranged. The stirring feeder 51 and the hydraulic conveying pump 52 are arranged on the pipeline of the hydraulic conveying unit 5, so as to drive the solid-liquid mixture to flow in the pipeline for a long distance.

[0063] With reference toFigure 2 The solid-liquid mixture after being transported by the hydraulic transportation unit 5 enters the drying and dewatering unit 6. The centrifugal dryer of the drying and dewatering unit 6 separates the solid-liquid mixture. The separated water is transported back to the pellet cutting water return tank 24 of the underwater pellet cutting unit 2 through a pipeline. The separated pellets are transported to the screening unit 7 after being dried. The vibrating screen in the screening unit 7 classifies the pellets, and the pellets with a qualified size are transported to the vertical pneumatic transportation unit 8. The pipeline in the vertical pneumatic transportation unit 8 is vertically arranged, so that the pellets are vertically transported to the blending and homogenizing unit 9 by using air power. The blending and homogenizing unit 9 blends and homogenizes the pellets, and then the pellets are packaged.

[0064] In the prior art, the drying and dewatering unit 6, the screening unit 7, the vertical pneumatic transportation unit 8 and the blending and homogenizing unit 9 of the pellets have more applications, and the above units are not the focus of the technical scheme of the present application. Therefore, the specific structure of the present application embodiment is not described in detail.

[0065] The implementation principle of the pellet post-processing transportation system in the present application embodiment is as follows:

[0066] The desorption effect of VOC organic volatile matters in the pellets is related to the desorption temperature of the pellets, the diffusion environment and the heat transfer balance of the pellets. In the present embodiment, the waste heat of the cut pellets and the pellet cutting water is fully utilized, so that only a small amount of energy is needed to heat the water in the retention tank 41, so that the VOC organic volatile matters are desorbed from the pellets, thereby reducing the energy consumption and the cost of the pellet post-processing process. Compared with air transportation of the pellets, the hydraulic transportation unit 5 consumes less energy, which can save the cost of the pellet post-processing process.

[0067] Embodiment 2

[0068] The difference between the present embodiment 2 and the embodiment 1 is as follows:

[0069] Reference Figure 6The residence tank 41 further comprises a flow slowing assembly 44, which comprises a plurality of flow slowing plates 441. The flow slowing plates 441 are arranged in the tank body 411 and are vertically spaced apart. The flow slowing plates 441 are fixedly connected to the inner wall of the tank body 411. The flow slowing plates 441 are provided with mounting holes 442 for the rotating shaft 432 to pass through, so as to mount the stirring assembly 43. The outer periphery of the flow slowing plates 441 is provided with flow-through openings 443 for the water body to pass through. The flow-through openings 443 of the plurality of flow slowing plates 441 are staggered on both sides of the central axis of the tank body 411, so that the water body flows from top to bottom through the plurality of flow slowing plates 441. That is, the flow slowing plates 441 divide the containing cavity in the tank body 411 into a plurality of sub-containing cavities, so that the solid-liquid mixture flows through the plurality of sub-containing cavities in sequence; thereby prolonging the flow path of the solid-liquid mixture in the residence tank 41, prolonging the residence time of the granules in the residence tank 41, and allowing the VOC organic volatile substances in the granules to be fully desorbed.

[0070] The top of the flow slowing plate 441 is provided with a first downwardly inclined guide surface 4411, and the granules flow along the first guide surface 4411 to the flow-through opening 443, thereby facilitating the flow of the solid-liquid mixture in the residence tank 41. The bottom of the flow slowing plate 441 is provided with a second upwardly inclined guide surface 4412. The desorbed VOC organic volatile substances exist in the water body in the form of bubbles, and the VOC organic volatile substance bubbles flow along the second guide surface 4412 to the flow-through opening 443 and float upwards, thereby facilitating the VOC organic volatile substances to separate from the water body, so that the VOC organic volatile substances are collected to the VOC centralized treatment unit 10 for harmless treatment.

[0071] Referring to Figure 7 In addition, the desorption unit 4 further comprises a hot water circulating tank, a hot water circulating pump and a second solid-liquid separator. The heating element is used to heat the water body in the hot water circulating tank. In this embodiment, the heating element is provided as a heating pipe for conveying steam, so as to heat the water body by using high-temperature steam.

[0072] Referring to Figure 6 The first solid-liquid separator 31 discharges the separated granules into the residence tank 41. The hot water circulating pump pumps the water body in the hot water circulating tank into the feeding pipe 4111 at the upper part of the residence tank 41, and the water body in the hot water circulating tank is mixed with the granules in the upper region of the residence tank 41 to form a solid-liquid mixture.

[0073] Referring to Figure 6 The second solid-liquid separator is connected to the discharging pipe 4112 of the residence tank 41 and is used to separate the desorbed solid-liquid mixture. The water body separated by the second solid-liquid separator is returned to the hot water circulating tank through a pipeline. The granules separated by the second solid-liquid separator are mixed with the water body separated by the first solid-liquid separator 31, and the mixed solid-liquid mixture is transported by the hydraulic transport unit 5.

[0074] The implementation principle of the granule post-processing conveying system in the embodiment of the present application is as follows:

[0075] Referring to Figure 7 The first solid-liquid separator 31 separates the granules from the water body, and the temperature of the granules is about 70°C. Then, the granules filtered by the first solid-liquid separator 31 are put into the residence tank 41 of the desorption unit 4, and the water body at 90°C in the hot water circulating tank is conveyed through a pipeline to mix with the granules at 70°C. The residence time of the granules in the residence tank 41 is not less than 30 min, and in this period of time, the water body at a higher temperature heats the granules, and the temperature of the granules rises to between 85°C and 90°C, so that the VOC organic volatile substances in the granules absorb sufficient energy, and the VOC organic volatile substances are desorbed from the polyolefin polymers. In this period of time, the granules move from the top of the tank body 411 to the bottom of the tank body 411 along with the flow of the water flow in the tank body 411; finally, the solid-liquid mixture of the granules and the water body is discharged from the tank body 411 through the discharge pipe 4112.

[0076] Referring to Figure 7 Then, the second solid-liquid separator separates the solid-liquid mixture flowing out of the residence tank 41, the water body filtered in the second solid-liquid separator is conveyed to the hot water circulating tank, and the heating element heats the water body in the hot water circulating tank, so that the water body in the hot water circulating tank is maintained at 90°C. The solid filtered by the second solid-liquid separator is mixed with the water body filtered by the first solid-liquid separator 31 to form a new solid-liquid mixture, and the solid-liquid mixture is pumped to the hydraulic conveying unit 5 through the material pump 42. Since the temperature of the water body filtered by the first solid-liquid separator 31 is relatively low, the temperature of the water body filtered by the first solid-liquid separator is about 70°C, so that the temperature of the newly mixed solid-liquid mixture is relatively low; thus, when the hydraulic conveying unit 5 conveys the solid-liquid mixture over a long distance, the risk of mutual adhesion of the granules can be reduced, so as to improve the quality of the granules.

[0077] In the embodiment, the solid-liquid mixture is filtered twice by the first solid-liquid separator 31 and the second solid-liquid separator, and since the residual heat of the strands in the extrusion process is fully utilized, the heat supplement of the desorption unit 4 only needs to consider the temperature difference of about 5°C of the water body in the hot water circulating tank; that is, a small amount of steam consumption can realize the effective desorption of the VOC organic volatile substances.

[0078] In summary, the cooperation of the first solid-liquid separation unit 3 and the desorption unit 4 not only realizes the desorption of the VOC organic volatile substances, but also greatly reduces the energy consumption and the cost of the granule post-processing.

[0079] Embodiment 3

[0080] The difference between the embodiment 3 and the embodiment 2 is as follows:

[0081] Referring to Figure 8The desorption unit 4 includes three residence tanks 41, which are sequentially named as a first residence tank, a second residence tank and a third residence tank, and the solid-liquid mixture flows through the first residence tank, the second residence tank and the third residence tank in sequence; the first residence tank, the second residence tank and the third residence tank are connected with the VOC centralized treatment unit 10 through a gas collection pipe 4113.

[0082] With reference to Figure 8 The granules separated by the first solid-liquid separator 31 are fed into the first residence tank, and the hot water circulating pump also delivers the hot water in the hot water circulating tank to the first residence tank, so that the granules are mixed with the water body with a higher temperature to heat the granules by the water body.

[0083] With reference to Figure 8 The implementation principle of the granule post-processing conveying system in the embodiment is as follows: since the solid-liquid mixture flows through the first residence tank, the second residence tank and the third residence tank in sequence, the residence time of the granules in the residence tanks 41 can be ensured, and the uniformity of the heating of the granules by the water body is improved; therefore, the uniformity of the desorption of the VOC organic volatile matters in different granules is improved, and the desorption effect of the VOC organic volatile matters is improved.

[0084] Embodiment 4

[0085] The difference between the embodiment 4 and the embodiment 2 is as follows:

[0086] With reference to Figure 9 The desorption unit 4 further includes a dissolved gas structure 48, which includes a dissolved gas tank 481, a first dissolved gas water conveying pipeline 482 and a dissolved gas releaser 483. The dissolved gas tank 481 dissolves the gas without oxygen in water under the action of a certain pressure to form supersaturated dissolved gas water. In the embodiment, the dissolved gas tank 481 dissolves nitrogen in water under the action of a certain pressure to form supersaturated dissolved gas water.

[0087] With reference to Figure 9 The first dissolved gas water conveying pipeline 482 is arranged in the tank body 411, one end of the first dissolved gas water conveying pipeline 482 is connected with the dissolved gas tank 481, and the dissolved gas tank 481 delivers the dissolved gas water into the residence tank 41 through the first dissolved gas water conveying pipeline 482. The dissolved gas releaser 483 is arranged on the first dissolved gas water conveying pipeline 482 and is connected with the first dissolved gas water conveying pipeline 482. The dissolved gas water flows into the tank body 411 through the dissolved gas releaser 483, and a large amount of micro-bubbles are released after the dissolved gas water is decompressed, and the micro-bubbles expand in volume under the action of the water body. In the embodiment, the outer peripheral wall and the inner peripheral wall of the first dissolved gas water conveying pipeline 482 are coated with a heat insulation coating to reduce the influence of the external water body. In other embodiments, an intermediate heat insulation filling layer can also be arranged in the first dissolved gas water conveying pipeline to reduce the influence of the external water body.

[0088] In the present embodiment, the input amount of the dissolved air water into the tank 411 is smaller compared to the input amount of the solid-liquid mixture into the tank 411; therefore, the delivery of the dissolved air water into the tank 411 has a smaller effect on the temperature of the water body in the tank. In addition, the input temperature of the hot water circulating tank can be adjusted to compensate for the effect of the dissolved air water input on the temperature of the water body; so that the temperature of the water body in the tank 411 can be maintained near the design value.

[0089] The implementation principle of the pellet post-treatment delivery system in the present embodiment is as follows:

[0090] Referring to Figure 9 , after the desorption of the VOC organic volatile matter from the pellets, the VOC organic volatile matter will diffuse into the water body; the VOC organic volatile matter is difficult to dissolve in the water body, and the VOC organic volatile matter will exist in the water body in the form of bubbles. Since the content of the desorbed VOC organic volatile matter in the pellets is small, the VOC organic volatile matter bubbles are also small; thus, when the water body flows from top to bottom in the tank 411, part of the VOC organic volatile matter bubbles will be difficult to float upwards, and even will be re-adsorbed on the high molecular polyolefin in the pellets.

[0091] Referring to Figure 9 , during the floating process of the bubbles released by the dissolved air water, the bubbles will capture the VOC organic volatile matter diffused into the water body, and the bubbles containing nitrogen will merge with the bubbles containing the VOC organic volatile matter to form large bubbles with a larger volume and float upwards.

[0092] In addition, after part of the VOC organic volatile matter is desorbed from the high molecular polyolefin, the VOC organic volatile matter bubbles will be adsorbed on the surface of the pellets; the bubbles released by the dissolved air water will also disturb the pellets, and the bubbles released by the dissolved air water will collide with the VOC organic volatile matter bubbles on the surface of the pellets to timely carry away the VOC organic volatile matter on the surface of the pellets.

[0093] The large bubbles containing the VOC organic volatile matter have a larger buoyancy, so that the large bubbles float to the liquid surface and break, thereby carrying the VOC organic volatile matter from the water body to the upper region of the tank 411; so that more VOC organic volatile matter can be collected to the VOC centralized treatment unit 10 through the gas collection pipe 4113.

[0094] At the same time, the bubbles released by the dissolved air water carry the VOC organic volatile matter in the water body, reducing the concentration of the VOC organic volatile matter in the water body, which is beneficial to the diffusion of the VOC organic volatile matter from the pellets to the water body.

[0095] Embodiment 5

[0096] The difference between the present embodiment 5 and the embodiment 4 is as follows:

[0097] Referring to Figure 10In the embodiment, the desorption unit 4 includes three residence tanks 41, which are sequentially named as a first residence tank, a second residence tank and a third residence tank, and the solid-liquid mixture sequentially flows through the first residence tank, the second residence tank and the third residence tank. The three residence tanks 41 have the same connection relationship with other structures as in Embodiment 3.

[0098] In the embodiment, the gas dissolving structure 48 is connected with the second residence tank, and the gas dissolving structure 48 delivers the gas dissolving water into the second residence tank.

[0099] The implementation principle of the granular post-treatment conveying system in the embodiment is as follows:

[0100] Referring to Figure 10 In the first residence tank, the content of bubbles in the solid-liquid mixture is small, and the granules can be fully contacted with the water body, so as to improve the speed of energy absorption of the granules and rapidly increase the temperature of the granules; so that the VOC organic volatile matters in the granules absorb energy and are desorbed from the high molecular polyolefin in the granules, and the desorbed VOC organic volatile matters diffuse into the water body to form small bubbles. The VOC organic volatile matter bubbles float upward and then escape to the top area of the tank body 411 to be collected to the VOC centralized treatment unit 10.

[0101] Referring to Figure 10 Subsequently, the solid-liquid mixture is delivered from the first residence tank to the second residence tank, at this time, the temperature of the granules is high, and the water body does not need to heat the granules. After the gas dissolving structure 48 delivers the gas dissolving water into the second residence tank, the bubbles released by the gas dissolving water can capture the VOC organic volatile matter bubbles in the water body.

[0102] Referring to Figure 10 Finally, the solid-liquid mixture is delivered from the second residence tank to the third residence tank. At this time, the newly input solid-liquid mixture is arranged in the upper area of the second residence tank, so that the bubbles in the second residence tank that do not float upward in time are separated from the water body in a low-pressure environment, further reducing the content of VOC organic volatile matters in the water body; at the same time, the bubbles in the water body can be fully escaped to facilitate the subsequent delivery of the solid-liquid mixture.

[0103] Embodiment 6

[0104] The difference between Embodiment 6 and Embodiment 5 is as follows:

[0105] Referring to Figure 11 and Figure 12 The gas dissolving structure 48 further includes a rotary joint 484 and a second gas dissolving water conveying pipeline 485; the first gas dissolving water conveying pipeline 482 is rotationally and sealingly connected with the rotating shaft 432 through the rotary joint 484.

[0106] Referring to Figure 12, the rotating shaft 432 is provided with a hollow section at one end away from the driving part 431, the hollow section is internally provided with a flow channel 4321, the flow channel 4321 is communicated with the first dissolved air water conveying pipeline 482. The second dissolved air water conveying pipeline 485 is horizontally fixed on the rotating shaft 432, and the second dissolved air water conveying pipeline 485 is communicated with the flow channel 4321 in the rotating shaft 432, and a plurality of dissolved air releasers 483 are arranged on the second dissolved air water conveying pipeline 485 along the dissolved air water conveying direction.

[0107] With reference to Figure 12 When the dissolved air tank 481 conveys the dissolved air water into the stay tank 41, the dissolved air water will flow through the first dissolved air water conveying pipeline 482, the rotary joint 484, the flow channel 4321 of the rotating shaft 432, the second dissolved air water conveying pipeline 485 and the dissolved air releaser 483 in sequence. The first dissolved air water conveying pipeline 482, the rotary joint 484, the flow channel 4321, the second dissolved air water conveying pipeline 485 can be coated with a heat insulation coating.

[0108] With reference to Figure 13 In the embodiment, the second dissolved air water conveying pipeline 485 comprises a first straight section 4851, an arc section 4852 and a second straight section 4853 in sequence, the first straight section 4851 and the second straight section 4853 are arranged along the radial direction of the tank body 411, and the arc section 4852 is arranged along the inner wall of the tank body 411. The first straight section 4851, the arc section 4852 and the second straight section 4853 are all provided with the dissolved air releaser 483.

[0109] The implementation principle of the granular post-treatment conveying system in the embodiment is as follows:

[0110] With reference to Figure 11 And Figure 12 When the rotating shaft 432 rotates, the rotating shaft 432 drives the second dissolved air water conveying pipeline 485 and the dissolved air releasers 483 on the second dissolved air water conveying pipeline 485 to rotate; so that the rotating shaft 432 can drive the dissolved air releasers 483 to release air bubbles at different positions, so as to improve the uniformity of the bubble distribution in the tank body 411, improve the capture efficiency and capture effect of the released air bubbles of the dissolved air water on the VOC organic volatile substances in the water body, and improve the removal effect of the VOC organic volatile substances.

[0111] At the same time, the rotating shaft 432 drives the second container water conveying pipeline to periodically pass below the flow port 443; while improving the uniformity of the bubble distribution in the tank body 411, it is also beneficial to the downward flow of the granular solid-liquid mixture, so that the device runs stably.

[0112] The first straight section 4851 and the second straight section 4853 are arranged along the radial direction of the tank body 411, and the dissolved gas releaser 483 is also arranged on the first straight section 4851 and the second straight section 4853, so as to further improve the uniformity of the bubbles released by the dissolved air water.

[0113] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, so: any equivalent changes made on the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A granules post-treatment conveying system, characterized by: The device comprises sequentially connected underwater pelletizing unit (2), first solid-liquid separator (31), desorption unit (4), hydraulic conveying unit (5), drying and dewatering unit (6), screening unit (7), vertical pneumatic conveying unit (8) and blending and homogenizing unit (9); the underwater pelletizing unit (2) cuts the material strip into pellets, and the pellets form a primary solid-liquid mixture with the water body; the first solid-liquid separator (31) is used for concentrating the solid-liquid mixture; the concentrated solid-liquid mixture is conveyed to the desorption unit (4) through a pipeline; the desorption unit (4) comprises a residence tank (41) and a heating device; the residence tank (41) is provided with a feeding pipe (4111), a discharging pipe (4112) and a gas collecting pipe (4113); the solid-liquid mixture is fed into the residence tank (41) through the feeding pipe (4111); the heating device is used for heating the solid-liquid mixture; the pellets stay in the residence tank (41); the water body heats the pellets so that the VOC organic volatile matter is desorbed from the pellets; after the VOC organic volatile matter is desorbed, it escapes to a VOC centralized treatment unit (10) through the gas collecting pipe (4113); the pellets from which the VOC organic volatile matter is removed are conveyed to the hydraulic conveying unit (5) through the discharging pipe (4112); the hydraulic conveying unit (5) conveys the pellets through the water body; the desorption unit (4) further comprises a dissolved air structure (48); the dissolved air structure (48) comprises a dissolved air tank (481), a first dissolved air water conveying pipeline (482) and a dissolved air releaser (483); the first dissolved air water conveying pipeline (482) is arranged in the residence tank (41); one end of the first dissolved air water conveying pipeline (482) is connected with the dissolved air tank (481); the dissolved air tank (481) conveys dissolved air water into the residence tank (41) through the first dissolved air water conveying pipeline (482); the dissolved air releaser (483) is arranged on the first dissolved air water conveying pipeline (482) and communicates with the first dissolved air water conveying pipeline (482); the dissolved air releaser (483) is used for releasing the supersaturated gas in the dissolved air water in the form of tiny bubbles; the released bubbles are used for capturing the VOC organic volatile matter gas after desorption.

2. The pellet post-treatment conveying system of claim 1, wherein: The desorption unit (4) further comprises a second solid-liquid separator, a hot water circulating tank and a hot water circulating pump; the heating device is used for heating the water body in the hot water circulating tank; the hot water circulating pump pumps the water body in the hot water circulating tank into the residence tank (41); the second solid-liquid separator communicates with the discharging pipe (4112) of the residence tank (41); the second solid-liquid separator is used for concentrating the solid-liquid mixture; the water body separated by the second solid-liquid separator is returned to the hot water circulating tank through a pipeline; Part of the water body separated by the first solid-liquid separator (31) is mixed with the solid-liquid mixture concentrated by the second solid-liquid separator through a pipeline to reduce the temperature of the solid-liquid mixture; the mixed solid-liquid mixture is conveyed through the hydraulic conveying unit (5).

3. The pellet post-treatment conveying system of claim 1, wherein: The desorption unit (4) comprises at least two residence tanks (41), and the residence tanks (41) are sequentially connected by pipelines, so that the solid-liquid mixture sequentially flows through the residence tanks (41).

4. The pellet post-treatment conveying system of claim 1, wherein: The residence tank (41) comprises a tank body (411) and a stirring assembly (43), the stirring assembly (43) comprises a driving member (431), a rotating shaft (432) and stirring paddles (433), the rotating shaft (432) is vertically arranged, the driving member (431) is fixedly arranged on the tank body (411), and the driving member (431) drives the rotating shaft (432) to rotate, and the stirring paddles (433) are fixedly connected with the rotating shaft (432).

5. The pellet post-treatment conveying system of claim 4, wherein: The residence tank (41) comprises a flow slowing assembly (44), the flow slowing assembly (44) comprises a plurality of flow slowing plates (441), the flow slowing plates (441) are fixedly connected with the inner wall of the tank body (411), the flow slowing plates (441) are provided with mounting holes (442) for the rotating shaft (432) to pass through, the flow slowing plates (441) are provided with flow-through openings (443) for water to pass through, the top of the flow slowing plates (441) is provided with a first downwardly inclined guide surface (4411), the bottom of the flow slowing plates (441) is provided with a second upwardly inclined guide surface (4412), the granules flow along the first guide surface (4411) to the flow-through openings (443), and the desorbed gas monomers flow along the second guide surface (4412) to the flow-through openings (443); the flow-through openings (443) of the plurality of flow slowing plates (441) are staggered and arranged on both sides of the central axis of the tank body (411), so that the water flows through the plurality of flow slowing plates (441) from top to bottom, and the stirring paddles (433) are arranged between adjacent flow slowing plates (441).

6. The pellet post-treatment conveying system of claim 1, wherein: The gas dissolving release device (483) is provided in plurality, and the plurality of gas dissolving release devices (483) are arranged at intervals along the first gas dissolving water conveying pipeline (482).

7. The pellet post-treatment conveying system of claim 1, wherein: The desorption unit (4) comprises three residence tanks (41), the three residence tanks (41) are sequentially named as a first residence tank, a second residence tank and a third residence tank, and the solid-liquid mixture sequentially flows through the first residence tank, the second residence tank and the third residence tank; the gas dissolving structure (48) is connected with the second residence tank, and the gas dissolving structure (48) conveys gas dissolving water into the second residence tank.

8. The pellet post-treatment conveying system of claim 4, wherein: The air dissolving structure (48) comprises an air dissolving tank (481), a first air dissolving water conveying pipe (482) and a rotary joint (484); the other end of the first air dissolving water conveying pipe (482) is rotationally and sealingly connected with the rotating shaft (432) through the rotary joint (484); the rotating shaft (432) is provided with a hollow section at the end away from the driving member (431), the hollow section is internally provided with a flow channel (4321), the flow channel (4321) is communicated with the first air dissolving water conveying pipe (482); the stirring assembly (43) further comprises a second air dissolving water conveying pipe (485), the second air dissolving water conveying pipe (485) is horizontally fixed on the rotating shaft (432), and the second air dissolving water conveying pipe (485) is communicated with the flow channel (4321); along the air dissolving water conveying direction, the second air dissolving water conveying pipe (485) is provided with the air dissolving releasers (483) at intervals.

9. The pellet post-treatment conveying system of claim 8, wherein: The second air dissolving water conveying pipe (485) comprises a first straight section (4851), an arc section (4852) and a second straight section (4853) in sequence, the first straight section (4851) and the second straight section (4853) are arranged along the radial direction of the tank body (411), and the arc section (4852) is arranged along the inner circumferential wall of the tank body (411).

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