CN116160585A - System and method for removing VOCs and odor in thermoplastic high polymer material - Google Patents

Abstract

The invention discloses a devolatilization system and a devolatilization method for removing VOCs and odors in thermoplastic polymer materials. The particle devolatilization device comprises two particle devolatilization machines with the same structure, wherein the particle devolatilization machines comprise a conveying component, a storage bin, a heating blast and other components. The thermoplastic polymer material is extruded by a melt devolatilization device and is devolatilized for the first time to form a strip-shaped high-temperature material, then the strip-shaped high-temperature material is processed by a cooling device, a blow dryer and a granulating device in sequence to form a dry granular material, and finally the dry granular material is devolatilized for the second time by a particle devolatilization device. According to the invention, an integrally-installed devolatilization system is adopted, the materials are continuously devolatilized for a plurality of times in the process from raw materials to granular materials, each process is continuously carried out in the process, each device is not stopped, the efficiency is improved, and the removal of VOCs and the odor concentration in the devolatilized materials reach the enterprise standard.

Description

System and method for removing VOCs and odor in thermoplastic high polymer material

Technical Field

The invention belongs to the technical field of polymer high molecular material volatile component research, and particularly relates to a system and a method for removing VOCs and odor in a thermoplastic high molecular material.

Background

Devolatilization of polymer melts to improve polymer quality is a common process in the industrial production of plastic materials. During this process volatile components such as monomers, oligomers, additives required for polymerization and undesired by-products which detract from the quality of the polymer are removed. Such as VOCs and odors in thermoplastic polymers, need to be devolatilized.

Chinese patent, name: a devolatilizing screw and a devolatilizing extruder, application number: 201910650218.4. in the invention, materials are extruded by a first thread part and a second thread part with opposite thread directions, so that directional conveying is realized; the devolatilizer is internally provided with a material channel, an inlet of the material channel is communicated with the conveying area or the first threaded part, an outlet of the material channel is communicated with the conveying part or/and the first threaded part of the next threaded unit, the discharging plate is provided with a plurality of discharging holes, continuous and uninterrupted films, lines, strips and the like are formed under the action of the material channel and the discharging plate, devolatilization is realized, and the materials are continuously extruded through the rotation of the devolatilization screw. In the process, although the material is devolatilized once, the devolatilization is not thorough, and the removed VOCs and smell can not meet the enterprise standards.

In addition, in the existing devolatilization technology, a melt devolatilization device, a grain cutting device, a vibrating screen device and a particle devolatilization device are installed in a split mode, so that the material extrusion, cutting and subsequent particle devolatilization are independent processes and discontinuous. Such as: and after the drying box is filled with the drying box, the drying box begins to heat and dry and devolatilize, and the drying box is filled with the drying box. In the carrying process, the original residual temperature of the granular materials is lost and is not effectively utilized; in addition, since the material accumulation amount in the drying box is large and since the material is static and cannot flow during the drying process, the duration of the drying and devolatilization process is long, requiring about 12 hours. The process has the advantages of time and labor waste, low efficiency, high cost and huge energy consumption in the particle devolatilization process.

Disclosure of Invention

The invention aims to provide a system and a method for removing VOCs and odor in a thermoplastic high polymer material, which solve the technical problems of low efficiency, high cost, huge energy consumption and incomplete material devolatilization for removing the VOCs and the odor in the thermoplastic high polymer material in the prior art.

In order to solve the technical problems, the invention adopts the following technical scheme:

a VOCs and smell devolatilization system for taking off among thermoplastic macromolecular material, including melt devolatilization device, cooling device, pelleter and the particle devolatilization device of integral installation setting.

The particle devolatilization device comprises two particle devolatilization machines with the same structure, wherein the particle devolatilization machines comprise a feed bin, a conveying assembly and a blast assembly, the conveying assembly is vertically arranged in the feed bin, and a feed inlet and two discharge outlets are arranged at the lower end of the feed bin; the blast assembly is arranged outside the feed bin, hot air is sent to the feed bin through the ventilating duct, and the air outlet is positioned below the discharge end of the conveying assembly.

Extruding and once devolatilizing the thermoplastic polymer material through a melt devolatilization device to form a strip-shaped high-temperature material, and then sequentially processing the strip-shaped high-temperature material through a cooling device, a blow dryer, a granulating device and a vibrating screen device to form a dry granular thermoplastic polymer material; the granular materials are subjected to secondary devolatilization through a particle devolatilization device.

According to the invention, the melt devolatilization device, the cooling device, the granulating device, the vibrating screen device and the particle devolatilization device are integrally arranged, the devolatilization is carried out twice in the process of materials from raw materials to particle materials, each process is continuously carried out in the process, each device does not need to stop, the efficiency is greatly improved, and VOCs and smell in the devolatilized materials reach the enterprise standard.

After the strip material is cut into particles by the particle cutting device, the particle material directly enters the particle devolatilizing device to be devolatilized for the second time, and is not required to be carried to a drying box located at other places manually or through other equipment, so that the time and the labor are saved, the efficiency is improved, the waste heat after the material is cut into particles is effectively utilized, and the cost is reduced.

The granulating device is in the prior art and will not be described in detail.

Further improved, the conveying component is a vertical screw conveyor and comprises a shell, a rotating shaft and a second motor, a screw blade is fixedly arranged on the rotating shaft along the length direction of the rotating shaft, the upper end of the rotating shaft is rotationally connected with a top plate of a storage bin, and the lower end of the rotating shaft is rotationally connected with a support plate of a bracket; the shell is sleeved on the periphery of the rotating shaft and the spiral blade, the lower end of the shell is fixedly connected with the supporting plate, and a feed inlet is formed; the upper end of the shell is open, and a gap exists between the shell and the top plate of the storage bin; the second motor is arranged on the bracket and drives the rotating shaft to rotate through the transmission component; the fixed cover of air funnel is established on the casing, forms cyclic annular ventilation passageway between casing and the air funnel, and ventilation passageway's upper end is closed, and the lower extreme is opened.

Further improved, an air outlet is formed in the top of the storage bin and is communicated with the adsorption device through a second pipeline. Through adsorption equipment, adsorb, purify the VOCs and the smell that the granule material deviate from in first order particle devolatilization machine and second grade devolatilization machine, pollution is reduced.

Further improved, the two particle devolatilizer are sequentially recorded as follows: a primary particle devolatilizer and a secondary devolatilizer; the bin of the primary particle devolatilizer is marked as a first bin, the feed inlet is marked as a first feed inlet, and the two discharge outlets are respectively marked as a first discharge outlet and a second discharge outlet; the bin of the secondary particle devolatilizer is marked as a second bin, the feed inlet is marked as a second feed inlet, and the two discharge outlets are respectively marked as a third discharge outlet and a fourth discharge outlet.

A sensor for detecting the stacking height of the materials is arranged in the first bin; valves are arranged on the four discharge ports, wherein the valves on the first discharge port and the third discharge port can adjust the sizes of the corresponding discharge ports according to the needs; a first receiving groove is arranged below the primary particle devolatilizing machine; the discharge end, the first feed inlet and the first discharge outlet of the vibrating screen device are communicated with the first receiving groove; a second receiving groove is arranged below the secondary particle devolatilizing machine; the second feeding port and the third discharging port are communicated with the second receiving groove.

Further improved, the lower ends of the first bin and the second bin are funnel-shaped, so that materials can flow out from the discharge hole conveniently.

Further improved, the melt devolatilization device comprises a barrel, at least one devolatilizer and at least one devolatilizing screw rod, wherein the devolatilizing screw rod passes through the devolatilizer to be arranged, and a conveying area is formed at the joint of a first thread part and a second thread part of the same thread unit in the devolatilizing screw rod; the devolatilizer is internally provided with a material channel, an inlet of the material channel is communicated with the conveying area or the first threaded part, and an outlet of the material channel is communicated with the conveying part or/and the first threaded part of the next threaded unit; the devolatilizer is provided with a temperature sensor, a cooling channel is arranged in the devolatilizer, and the cooling channel is communicated with a cooling system of the melt devolatilizer through a pipeline.

In order to prevent the material from being transported all the way along the devolatilizing screw without entering the material passage, the gap between the devolatilizing screw and the devolatilizer is designed to be small at the entrance of the material passage. The devolatilization screw rod is easy to rub with the devolatilizer in the rotation process, and the temperature of the devolatilizer is high and the devolatilizer is damaged after long-time work. Through setting up temperature sensor to and set up cooling channel in the devolatilizer, after temperature sensor detects the devolatilizer temperature and reaches the settlement threshold value, the coolant liquid begins to circulate in the cooling channel, cools off the devolatilizer, protects the devolatilizer, prolongs its life.

Further improved, the cooling device comprises a cooling tank, cooling liquid is filled in the cooling tank, and the cooling liquid is used for cooling a strip-shaped high-temperature material formed after extrusion and one-time devolatilization by the melt devolatilization device.

Further improved, the dryer comprises two first air outlets which are arranged in opposite directions, the strip-shaped materials pass through the two first air outlets, the efficiency is high, and the moisture on the surfaces of the strip-shaped materials can be dried rapidly. The blow dryer is the prior art and will not be described in detail.

Further improved, a vibrating screen is arranged between the granulating device and the particle devolatilizing device, the granulating device cuts the materials into particles and then screens the particles through the vibrating screen, and the particle materials meeting the particle size requirements enter the first receiving groove.

A devolatilization method for removing VOCs and odor in thermoplastic polymer materials comprises the following steps:

s1: thermoplastic polymer raw materials enter a melt devolatilization device through a feeding device, are conveyed into a devolatilizer through a devolatilization screw, and are devolatilized once in the extrusion process;

s2: extruding the materials through a melt devolatilization device to form strip-shaped high-temperature intermediate materials, then passing through a cooling tank of a cooling device, cooling by cooling liquid, drying the moisture on the surfaces of the materials through a dryer, and then entering a granulating device, wherein the granulating device cuts the strip-shaped materials into particles; the traction roller in the granulating device pulls the strip-shaped materials to advance, so that the whole process can be continuously carried out;

s3: the granular materials are screened by a vibrating screen, and the granular materials meeting the particle size requirement enter a particle devolatilization device for secondary devolatilization:

s31: and (3) devolatilizing the materials by a primary particle devolatilizer:

s311: the granular materials screened by the vibrating screen enter a first receiving groove, enter a spiral conveyor of a primary particle devolatilizer through a first feeding hole, continuously work, convey the materials upwards, then discharge the materials from an opening at the upper end of a shell, and fall back into a first hopper; the hot air generated by the air blowing component is blown out through the ventilation channel, and the falling particulate material is heated and dried, so that the particulate material is devolatilized; in the process, the second discharge port is closed, and the discharge speed of the first discharge port is smaller than the feed speed of the first feed port;

s312: the materials falling back into the first hopper enter a first receiving groove through a first discharge hole, are mixed with the materials which enter the first receiving groove after being screened by a vibrating screen, enter a spiral conveyor of a primary particle devolatilizer through a first feed hole, and repeat the step S311 to circularly convey the materials in the primary particle devolatilizer for multiple devolatilization;

s313: continuously repeating the step S312 until the sensor detects that the material stacking height in the first bin reaches a set value, opening the second discharge port, and closing the first discharge port; the material enters a secondary particle devolatilizer through a second discharge hole;

s32: carrying out devolatilization treatment on the granular materials again through a secondary particle devolatilization machine:

s321: the material enters a second receiving groove from a second discharge hole, enters a spiral conveyor of the secondary particle devolatilizer through a second feed hole, continuously works, conveys the material upwards, discharges the material from an opening at the upper end of the shell, and falls back into a second storage bin; blowing out hot air generated by the air blowing component through the ventilation channel, and reheating and drying the falling particulate material to devolatilize the particulate material again; in the process, the third discharge port is opened, and the fourth discharge port is closed;

s322: the materials falling back into the second bin enter a second receiving groove through a third discharge hole, are mixed with the materials just entering the second receiving groove from the second discharge hole, enter a spiral conveyor of a secondary particle devolatilizer through a second feed hole, and repeat the step S321, so that the materials are circularly conveyed in the secondary particle devolatilizer to be devolatilized for multiple times;

s323: continuously repeating the step S322, closing the second discharge hole after the height of the materials piled up in the first bin is reduced to a set value, so that the materials in the primary particle devolatilizer start to be piled up again in the first bin; the material is circularly devolatilized in a secondary particle devolatilizing machine, and when the devolatilization time in the stage reaches a set value, the secondary devolatilization of the particle material is completed; then closing the third discharge hole, opening the fourth discharge hole, and discharging the devolatilized material from the fourth discharge hole;

s33: after the discharging of the granular materials in the second storage bin is completed, the third discharge port is opened, and the fourth discharge port is closed;

s4: and (3) repeating the step (S3) to continuously devolatilize the materials.

Further improved, the air speed and the temperature of the hot air generated by the air blowing component can be adjusted according to the material properties; the devolatilization time of the materials in the secondary particle devolatilizer is set according to the material properties.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, the melt devolatilization device, the cooling device, the granulating device, the vibrating screen device and the particle devolatilization device are integrally arranged, the devolatilization is carried out twice in the process of materials from raw materials to particle materials, each process is continuously carried out in the process, each device does not need to be stopped, the efficiency is greatly improved, the whole devolatilization process of the materials can be completed in about 1 hour, and the VOCs and the smell of the devolatilized materials reach the enterprise standard.

2. After the strip material is cut into particles by the particle cutting device, the particle material directly enters the particle devolatilizing device to be devolatilized for the second time, and is not required to be carried to a drying box located at other places manually or through other equipment, so that the time and the labor are saved, the efficiency is improved, the waste heat after the material is cut into particles is effectively utilized, and the cost is reduced.

3. The particle materials are circularly devolatilized in a primary particle devolatilizer and a secondary devolatilizer, the particle materials are dynamic all the time in the whole process, and the devolatilization time is ensured by arranging a sensor for measuring the height in a first storage bin and arranging the circulation time of the materials in a second storage bin; and meanwhile, high-temperature gas is introduced to ensure that the material is fully contacted with hot air, the devolatilization effect is good, and VOCs and smell in the material after devolatilization are up to the enterprise standard.

4. Through setting up adsorption equipment, the VOCs and the smell that the granule material deviate from in primary particle devolatilizer and secondary devolatilizer are adsorbed, purified by adsorption equipment, pollution abatement.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is evident that the drawings described are only some embodiments of the invention, but not all embodiments, and that other designs and drawings can be obtained from these drawings by a person skilled in the art without inventive effort.

FIG. 1 is a schematic diagram of a system for devolatilizing VOCs and odors from thermoplastic polymer materials according to the present invention;

FIG. 2 is a schematic view of the structure of the devolatilizing screw according to the present invention;

FIG. 3 is a schematic view of the structure of the charging device and the melt devolatilizer of the present invention;

fig. 4 is a partial enlarged view of a portion a in fig. 3;

FIG. 5 is a schematic view showing the structure of the particle devolatilizer of the present invention;

FIG. 6 is a flow chart of a devolatilization process for removing VOCs and odors from thermoplastic polymer materials according to the present invention;

FIG. 7 is a flow chart of a secondary devolatilization of particulate material into a particle devolatilization apparatus according to the present invention;

FIG. 8 is a graph showing the results of the test in comparative example 1;

FIG. 9 is a graph showing the results of the test in comparative example 2.

Detailed Description

Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present invention, but not to limit the scope of the present invention.

In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

In the description of the present invention, a number means one or more, a number means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

Embodiment one:

as shown in fig. 1, the devolatilization system for removing VOCs and odors in thermoplastic polymer materials comprises a controller, a feeding device 200, a melt devolatilization device 200, a cooling device 300, a blow dryer 400, a granulating device 500, a vibrating screen 600 and a particle devolatilization device 700, which are integrally installed.

The controller is electrically connected with a display 800 and an input device, through which parameters of materials and control parameters are input. The display is used for displaying the running condition of each device and the data acquired by the sensor in the material devolatilization process.

The particle devolatilization device 700 comprises two particle devolatilizers with the same structure, wherein each particle devolatilizer comprises a storage bin, a conveying assembly and a blast assembly, the conveying assembly is vertically arranged in each storage bin, and a feed inlet and two discharge outlets are formed in the lower end of each storage bin; the blast assembly is arranged outside the feed bin, hot air is sent into the feed bin through the ventilating duct, and the air outlet is positioned below the discharge end of the conveying assembly.

Extruding and once devolatilizing the thermoplastic polymer material through a melt devolatilization device to form a strip-shaped high-temperature material, and then sequentially processing the strip-shaped high-temperature material through a cooling device, a blow dryer, a granulating device and a vibrating screen device to form a dry granular thermoplastic polymer material; the granular materials are subjected to secondary devolatilization through the particle devolatilization device, so that the purpose of thoroughly devolatilizing the materials is achieved.

According to the invention, the melt devolatilization device, the cooling device, the granulating device, the vibrating screen device and the particle devolatilization device are integrally arranged, the devolatilization is carried out twice in the process of materials from raw materials to particle materials, each process is continuously carried out in the process, each device does not need to stop, the efficiency is greatly improved, and VOCs and smell in the particle materials after devolatilization reach the enterprise standard.

After the strip material is cut into particles by the particle cutting device, the particle material directly enters the particle devolatilizing device to be devolatilized for the second time, and is not required to be carried to a drying box located at other places manually or through other equipment, so that the time and the labor are saved, the efficiency is improved, the waste heat after the material is cut into particles is effectively utilized, and the cost is reduced.

The granulating device is in the prior art and will not be described in detail.

In this embodiment, the melt devolatilizer includes a barrel 15, two devolatilizers 20, and one devolatilizing screw, which is disposed through the devolatilizers 20, as shown in fig. 3. The devolatilizer 20 has a material passage 28 therein, and the barrel 15 is provided with a plurality of vent holes 25, as shown in fig. 4.

As shown in fig. 2, the devolatilizing screw comprises a shaft having a conveying portion 13 for conveying the material forward and a two-stage screw unit including a first screw portion 11 for conveying the material forward and a second screw portion 12 connected to the first screw portion 11, and the screw threads of the first screw portion 11 and the screw threads of the second screw portion 12 are opposite in rotation.

After the devolatilization screw is installed on the melt devolatilization device 200, the first motor 50 is started to drive the devolatilization screw to rotate, the material is plasticized by the feeding device 100 and then is fed into the cylinder 15, the conveying part 13 conveys the plasticized material to the first threaded part 11, when the material is conveyed to the junction of the first threaded part 11 and the second threaded part 12 along the first threaded part 11, the material enters the first devolatilizer 20 to devolatilize through the material channel 28 of the first devolatilizer 20 after being subjected to the thrust force P1 and the reverse thrust force P2, the extruded material enters the other section of the first threaded part 11 and then enters the material channel 28 of the second devolatilizer 20, after passing through the discharging plate 21, the material falls into the conveying part and moves forward under the action of the conveying part, and finally, the continuous and uninterrupted strip-shaped high-temperature material enters the cooling device through the extrusion tool 40 at the forefront end of the devolatilization screw.

The pitch of the first thread part 11 is gradually reduced, the first thread part 11 extrudes materials and extrudes, and the pitch of the second thread part 12 is the same as the pitch of the initial end of the first thread part 11, so that |P1| > |P2|. The |p1| refers to the absolute value of the thrust force P1. The |p2| refers to the absolute value of the thrust force P2.

In this embodiment, the material channel 28 is provided with a detachable discharge plate 21 near the outlet, and the discharge plate 21 is provided with a plurality of discharge holes, which may be round holes, bar holes, etc. The outlet of the material channel 28 is divided into a first space 22 far away from the devolatilization screw and a second space 23 near the devolatilization screw by the discharging plate 21, the discharging holes are communicated with the first space 22 and the second space 23, and the inner diameter of the discharging holes near the first space 22 is larger than the inner diameter of the discharging holes near the second space 23. After the material enters the discharge plate 21 along the first space 22, the material is devolatilized after passing through the discharge holes 26 with gradually deformed inner diameters to form continuous and uninterrupted films, wires, strips and the like, and the material enters the second space 23. The extrudate has a greater surface area than the material prior to passing through the take-off plate 21, facilitating the escape of VOCs along the material path 28, devolatilization screw and vent 25 of barrel 15, as shown in fig. 4.

An exhaust passage 24 is provided in the devolatilizer 20, and the exhaust passage 24 communicates the second space 23 with an exhaust hole 25 of the barrel 15, as shown in fig. 4. After the VOCs are separated from the extruded material, part of the VOCs enter the exhaust hole 25 of the cylinder 15 through the diameter of the second space 23, and the rest of the VOCs enter the exhaust hole 25 of the cylinder 15 through the first screw part 11 or the conveying part 13.

In other embodiments, the number of screw units and devolatilizers may be three, four or more, and the number of both may be the same. Multiple devolatilizations are achieved by providing multiple screw units to facilitate multiple devolatilizers 20 on the extruder.

In other embodiments, the number of devolatilizing screws may be two.

In this embodiment, a pressure sensor is disposed at the inlet of the material passage 28, and the pressure sensor is electrically connected to the controller. The pressure sensor is used for the pressure to which the material is subjected near the inlet of the material channel 28. When the resistance P3 of the discharge plate 21 is set, the material can be extruded normally as long as |P1| > |P2| > |P3|. The |p3| is the absolute value of the resistance P3 of the discharge plate 21. When the pressure sensor detects |p3|= |p2|, it indicates that the devolatilizer 20 has adsorbed a large amount of impurities, the resistance to the material increases, and the effect is deteriorated, and then the discharging plate 21 needs to be cleaned in time to prevent the material from leaking to the output portion or the first threaded portion 11 of the next threaded unit along the second threaded portion 12 in the devolatilizer 20.

The material channel 28 comprises a feeding channel 27 and a discharging channel, a sealing plate capable of being opened is arranged on the side wall of the feeding channel 27 and/or the side wall of the discharging channel, and a mounting hole for mounting the discharging plate 21 is formed in the side wall of the discharging channel. The sealing plate is opened, so that workers can clean the material channel 28 conveniently, the materials can be extruded continuously, the surface area of the plasticized materials is increased, and VOCs and odors in the materials are better and fully released.

Regarding the melt devolatilization device, applicant applies for chinese patent, name: a devolatilizing screw and a devolatilizing extruder, application number: 201910650218.4, which are not described in detail.

As shown in fig. 4, the devolatilizer 20 is provided with a temperature sensor 30, a cooling channel 29 is disposed in the devolatilizer, the cooling channel 29 is communicated with a cooling system 31 of the melt devolatilizer through a pipe, and the temperature sensor is electrically connected with the controller. When the temperature sensor detects that the temperature of the devolatilizer reaches a set threshold value, the cooling liquid in the cooling channel starts to circulate, so that the devolatilizer is cooled, the devolatilizer is protected, and the service life of the devolatilizer is prolonged.

In this embodiment, the cooling device includes a cooling tank, in which a cooling liquid is filled, and the strip-shaped high-temperature material formed after being extruded and devolatilized once by the melt devolatilization device 200 is cooled by the cooling liquid.

In this embodiment, the blow dryer 400 includes two first air outlets disposed opposite to each other, and the strip material passes through between the two first air outlets, so that the efficiency is high, and the moisture on the surface of the strip material can be blown dry rapidly. The blow dryer is the prior art and will not be described in detail.

In this embodiment, a vibrating screen 600 is disposed between the granule cutting device 500 and the granule devolatilizing device 700, the granule cutting device 500 cuts the material into granules, then screens the granules through the vibrating screen 600, and the granules with smaller granule diameter fall into the lower recovery chamber and are plasticized and molded again; the particulate material having a larger particle size that meets the requirements enters the particle devolatilizer 700.

In this embodiment, as shown in fig. 5, the conveying assembly is a vertical screw conveyor, and includes a housing 703, a rotating shaft 704 and a second motor 705, where a screw blade is fixedly disposed on the rotating shaft 704 along the length direction of the rotating shaft 704, the upper end of the rotating shaft 704 is rotatably connected with a top plate of the storage bin, and the lower end is rotatably connected with a supporting plate 716 of a bracket 715; the shell 703 is sleeved on the periphery of the rotating shaft and the spiral blade, the lower end of the shell is fixedly connected with the supporting plate, and a feed inlet is formed; the upper end of the shell is open, and a gap exists between the shell and the top plate of the storage bin; the second motor 705 is installed on the bracket and drives the rotating shaft to rotate through the transmission component; the ventilation tube 726 is fixedly sleeved on the shell 703, an annular ventilation channel is formed between the shell 703 and the ventilation tube 726, the upper end of the ventilation channel is closed, the lower end of the ventilation channel is open, hot air is blown downwards from the outlet of the ventilation channel, reflected by the bottom plate of the funnel, changed in direction and then blown upwards, and then enters the adsorption device from the air outlet of the top plate of the storage bin. The lower end of the ventilation channel is opened, so that the path of hot air in the bin is increased, and the material is contacted with the hot air for a longer time; in addition, the material is cut into particles, so that the contact area with hot air is increased, and the devolatilization effect can be further improved.

The transmission component can be in gear transmission, belt transmission, chain transmission and the like.

In this embodiment, an air outlet is formed at the top of the bin, and the air outlet is communicated with the adsorption device 900 through a second pipeline 713. Through adsorption equipment, adsorb, purify the VOCs and the smell that the granule material deviate from in first order particle devolatilization machine and second grade devolatilization machine, pollution is reduced.

In this example, two particle devolatilizers were sequentially written in the devolatilization order: a primary particle devolatilizer and a secondary devolatilizer; the bin of the primary particle devolatilizer is marked as a first bin 701, the feed inlet is marked as a first feed inlet, and the two discharge outlets are respectively marked as a first discharge outlet 706 and a second discharge outlet 707; the bin of the secondary particle devolatilizer is denoted as a second bin 702, the feed inlet is denoted as a second feed inlet, and the two discharge outlets are denoted as a third discharge outlet 708 and a fourth discharge outlet 709, respectively.

The first bin 701 is provided with a ranging sensor for detecting the stacking height of materials, and the ranging sensor is electrically connected with the controller. Valves are arranged on the four discharge holes, wherein the valves on the first discharge hole 706 and the third discharge hole 708 can adjust the sizes of the corresponding discharge holes according to the needs; a first receiving groove 710 is arranged below the primary particle devolatilizer; the discharge end, the first feed inlet and the first discharge outlet 706 of the vibrating screen 600 are all communicated with a first receiving groove 710; a second receiving groove 711 is arranged below the secondary particle devolatilizer; the second feed inlet and the third discharge outlet 708 are both in communication with a second receiving slot 711.

The valve can be an electrically controlled valve of a controller or a valve which can be manually adjusted or opened and closed.

In this embodiment, the lower ends of the first bin 701 and the second bin 702 are funnel-shaped, so that materials can flow out from the discharge port conveniently.

Embodiment two:

as shown in fig. 6, the devolatilization method for removing VOCs and odors in thermoplastic polymer materials comprises the steps of:

s1: thermoplastic polymer raw materials enter a melt devolatilization device 200 through a feeding device 100, are conveyed into devolatilizers 20 through devolatilizing screws 13, are devolatilized through two devolatilizers 20 in sequence, and then pass through an extrusion die 40 at the forefront end of the devolatilizing screws to form continuous and uninterrupted strip-shaped high-temperature materials.

S2: the materials are extruded by the melt devolatilization device 200 to form strip-shaped high-temperature intermediate materials, then pass through a cooling groove of the cooling device 300, are cooled by cooling liquid, and enter the granulating device 500 after being dried by the dryer 400 to dry the moisture on the surfaces of the materials, and the granulating device 500 cuts the strip-shaped materials into particles; the traction roller in the grain cutting device 500 pulls the strip-shaped materials to advance, so that the whole process can be continuously carried out;

s3: the granular materials are screened by the vibrating screen 600, and the granular materials meeting the particle size requirement enter the particle devolatilization device 700 for secondary devolatilization, as shown in fig. 7:

s31: and (3) devolatilizing the materials by a primary particle devolatilizer:

s311: the granular materials screened by the vibrating screen enter a first receiving groove 710, enter a spiral conveyor of a primary particle devolatilizer through a first feeding hole, continuously work, convey the materials upwards, then discharge the materials from an opening at the upper end of a shell 703 and fall back into the first storage bin 701; the hot air generated by the air blowing component 712 is blown out through the ventilation channel, and the falling particulate material is heated and dried, so that the particulate material is devolatilized; during this process, the second discharge port 707 is closed, and the discharge speed of the first discharge port 706 is less than the feed speed of the first feed port;

s312: the materials falling back into the first bin 701 enter the first receiving trough 710 through the first discharge port, are mixed with the materials which enter the first receiving trough 710 after being screened by the vibrating screen 600, enter the spiral conveyor of the primary particle devolatilizer through the first feed port, and repeat the step S311, so that the materials are circularly conveyed in the primary particle devolatilizer for multiple devolatilization;

s313: continuously repeating the step S312 until the ranging sensor detects that the material stacking height in the first hopper 701 reaches a set value, then opening the second discharge hole 707, and closing the first discharge hole 706; the material enters a secondary particle devolatilizer through a second discharge hole 707;

s32: carrying out devolatilization treatment on the granular materials again through a secondary particle devolatilization machine:

s321: the materials enter a second receiving groove 711 from a second discharging hole 707, enter a spiral conveyor of the secondary particle devolatilizer through a second feeding hole, continuously work, convey the materials upwards, then discharge the materials from an opening at the upper end of the shell, and fall back into the second storage bin 702; blowing out hot air generated by the air blowing component through the ventilation channel, and reheating and drying the falling particulate material to devolatilize the particulate material again; in the process, the third discharging hole 708 is opened, and the fourth discharging hole 709 is closed;

s322: the materials falling back into the second bin 702 enter the second receiving groove through the third discharge hole, are mixed with the materials just entering the second receiving groove 711 from the second discharge hole, enter the spiral conveyor of the secondary particle devolatilizer through the second feed hole, and repeat the step S321, so that the materials are circularly conveyed in the secondary particle devolatilizer to perform devolatilization for multiple times;

s323: continuously repeating the step S322, closing the second discharging hole after the height of the materials piled up in the first bin 701 is reduced to a set threshold value, so that the materials in the primary particle devolatilizer start to be piled up again in the first bin; the material is circularly devolatilized in a secondary particle devolatilizing machine, and when the devolatilization time in the stage reaches a set value, the secondary devolatilization of the particle material is completed; then, the third discharging hole 708 is closed, the fourth discharging hole 709 is opened, and the devolatilized material is discharged from the fourth discharging hole 709.

In this embodiment, the set time is 30min.

S33: after the discharging of the granular materials in the second storage bin is completed, the third discharge port is opened, and the fourth discharge port is closed;

s4: and (3) repeating the step (S3) to continuously devolatilize the materials.

In other embodiments, the wind speed and the temperature of the hot air generated by the air blowing component can be adjusted according to the material properties; the devolatilization time of the materials in the secondary particle devolatilizer is set according to the material properties.

Embodiment III:

the devolatilization system and the method of the invention are utilized to perform primary devolatilization and secondary devolatilization on materials. The devolatilized beverage straw material was subjected to odor detection according to PV3900-2000, the detection result was 3.5, the standard value was met, and the detection report was shown in FIG. 8.

Comparative example one:

the product melt devolatilization device developed earlier by the applicant has applied for Chinese patent, and the name is: a devolatilizing screw and a devolatilizing extruder, application number: 201910650218.4 the material is devolatilized once by the device (the material is not devolatilized twice by the particle devolatilizer). The odor detection is carried out on the PP automobile material prepared from the devolatilized material, and the odor detection is carried out according to PV3900-2000, and the detection result is shown in figure 9. The odor detection value was 4.2, which did not meet the standard value.

Comparative example two:

the melt devolatilization device, the granulating device and the particle devolatilization device are installed in a split mode. The granular materials screened by the vibrating screen after cutting are required to be manually conveyed into the oven, and after the oven is filled, the materials are heated, dried and devolatilized, the materials are static in the drying process, the drying and devolatilization require about 12 hours, and the electric energy consumed in the process is about 500 KW/ton. The odor detection is carried out on the devolatilized PP automobile material, the odor detection is carried out according to PV3900-2000, the detection result basically accords with the standard value, but the time consumption is too long, the efficiency is low, and the energy consumption is high.

According to the detection result, the device and the method for devolatilizing the VOCs and the odors in the thermoplastic polymer material, disclosed by the invention, are adopted, so that the production efficiency is greatly improved, the production cost is reduced, and the VOCs and the odors of the devolatilized materials reach the enterprise standard.

While the preferred embodiments of the present invention have been illustrated and described, the present invention is not limited to the embodiments, and various equivalent modifications and substitutions can be made by one skilled in the art without departing from the spirit of the present invention, and these are intended to be included in the scope of the present invention as defined in the appended claims.

Claims (10)

1. A devolatilization system for taking off VOCs and smell among thermoplastic macromolecular material, its characterized in that: comprises a melt devolatilization device, a cooling device, a grain cutting device and a grain devolatilization device which are integrally arranged;

the particle devolatilization device comprises two particle devolatilization machines with the same structure, wherein the particle devolatilization machines comprise a conveying assembly, a storage bin and a heating blast assembly, the conveying assembly is vertically arranged in the storage bin, and a feed inlet and a discharge outlet are arranged at the lower end of the storage bin; the heating blast assembly is arranged outside the hopper, hot air is sent into the bin through the ventilating duct, and the air outlet is positioned below the discharge end of the conveying assembly;

extruding and once devolatilizing the thermoplastic polymer material through a melt devolatilization device to form a strip-shaped high-temperature material, and then sequentially processing the strip-shaped high-temperature material through a cooling device, a blow dryer and a granulating device to form a dry granular thermoplastic polymer material; the granular materials are subjected to secondary devolatilization through a particle devolatilization device.

2. The devolatilization system for removing VOCs and odor from thermoplastic polymer material according to claim 1, wherein the conveying assembly is a vertical screw conveyor, comprising a housing, a rotating shaft and a second motor, wherein screw blades are fixedly arranged on the rotating shaft along the length direction thereof, the upper end of the rotating shaft is rotatably connected with the top plate of the hopper, and the lower end is rotatably connected with the support plate of the bracket; the shell is sleeved on the periphery of the rotating shaft and the spiral blade, the lower end of the shell is fixedly connected with the supporting plate, and a feed inlet is formed; the upper end of the shell is open, and a gap is reserved between the shell and the top plate of the hopper; the second motor is arranged on the bracket and drives the rotating shaft to rotate through the transmission component;

the fixed cover of air funnel is established on the casing, forms cyclic annular ventilation passageway between casing and the air funnel, and ventilation passageway's upper end is closed, and the lower extreme is opened.

3. The devolatilization system for removing VOCs and odor from thermoplastic polymer material as claimed in claim 1 or 2, wherein the top of the hopper is provided with an air outlet, and the air outlet is communicated with the adsorption device through a second pipeline.

4. The devolatilization system for removing VOCs and odor from thermoplastic polymer material as described in claim 3, wherein two particle devolatilizers, in order of devolatilization, are sequentially: a primary particle devolatilizer and a secondary devolatilizer; the bin of the primary particle devolatilizer is marked as a first bin, the feed inlet is marked as a first feed inlet, and the two discharge outlets are respectively marked as a first discharge outlet and a second discharge outlet; the material storage bin of the secondary particle devolatilizer is a second storage bin, the feeding port is a second feeding port, and the two discharging ports are respectively a third discharging port and a fourth discharging port;

the first middle bin is provided with a sensor for detecting the stacking height of materials;

valves are arranged on the four discharge ports, wherein the valves on the first discharge port and the third discharge port can adjust the sizes of the corresponding discharge ports according to the needs;

a first receiving groove is arranged below the primary particle devolatilizing machine; the discharge end, the first feed inlet and the first discharge outlet of the granulating device are communicated with the first receiving groove;

a second receiving groove is arranged below the secondary particle devolatilizing machine; the second feeding port and the third discharging port are communicated with the second receiving groove.

5. The devolatilization system for removing VOCs and odor from a thermoplastic polymer material as described in claim 4, wherein said first and second bins are funnel-shaped at their lower ends.

6. The devolatilization system for removing VOCs and odor from thermoplastic polymer material according to claim 5, wherein said melt devolatilization device comprises a barrel, at least one devolatilizer and at least one devolatilizer screw disposed through the devolatilizer, the junction of the first and second threaded portions of the same threaded element in the devolatilizer screw forming a conveying zone; the devolatilizer is internally provided with a material channel, an inlet of the material channel is communicated with the conveying area or the first threaded part, and an outlet of the material channel is communicated with the conveying part or/and the first threaded part of the next threaded unit;

the devolatilizer is provided with a temperature sensor, a cooling channel is arranged in the devolatilizer, and the cooling channel is communicated with a cooling system of the melt devolatilizer through a pipeline.

7. The devolatilization system for removing VOCs and odor from thermoplastic polymer material as defined in claim 6, wherein said cooling means comprises a cooling tank containing a cooling fluid, said cooling tank being cooled by said cooling fluid after extrusion and one devolatilization by said melt devolatilization means to form a strip of high temperature material;

the blow dryer comprises two first air outlets which are arranged in opposite directions, and the strip-shaped materials pass through the space between the two first air outlets.

8. The system for devolatilization of VOCs and odor in thermoplastic polymer material as described in claim 7, wherein a vibrating screen is provided between said pelletizing device and said particle devolatilization device, and said pelletizing device screens said material after it is pelletized by said pelletizing device, and the pellet material meeting the particle size requirement is fed into said first receiving chute.

9. A devolatilization method for removing VOCs and odors from thermoplastic polymer materials as claimed in any one of claims 1 to 8, comprising the steps of:

s1: thermoplastic polymer raw materials enter a melt devolatilization device through a feeding device, are conveyed into a devolatilizer through a devolatilization screw, and are devolatilized once in the extrusion process;

s2: extruding the materials through a melt devolatilization device to form strip-shaped high-temperature intermediate materials, then passing through a cooling tank of a cooling device, cooling by cooling liquid, drying the moisture on the surfaces of the materials through a dryer, and then entering a granulating device, wherein the granulating device cuts the strip-shaped materials into particles; the traction roller in the granulating device pulls the strip-shaped materials to advance, so that the whole process can be continuously carried out;

s3: the granular materials are screened by a vibrating screen, and the granular materials meeting the particle size requirement enter a particle devolatilization device for secondary devolatilization:

s31: and (3) devolatilizing the materials by a primary particle devolatilizer:

s311: the granular materials screened by the vibrating screen enter a first receiving groove, enter a spiral conveyor of a primary particle devolatilizing machine through a first feeding hole, continuously work, convey the materials upwards, then discharge the materials from an opening at the upper end of a shell, and fall back to a first hopper bin; the hot air generated by the air blowing component is blown out through the ventilation channel, and the falling particulate material is heated and dried, so that the particulate material is devolatilized; in the process, the second discharge port is closed, and the discharge speed of the first discharge port is smaller than the feed speed of the first feed port;

s312: the materials falling back into the first bin enter a first receiving groove through a first discharge hole, are mixed with the materials which enter the first receiving groove after being screened by a vibrating screen, enter a spiral conveyor of a primary particle devolatilizer through a first feed hole, and repeat the step S311 to circularly convey the materials in the primary particle devolatilizer for multiple devolatilization;

s313: continuously repeating the step S312 until the sensor detects that the material stacking height in the first hopper reaches a set value, opening the second discharge port, and closing the first discharge port; the material enters a secondary particle devolatilizer through a second discharge hole;

s32: carrying out devolatilization treatment on the granular materials again through a secondary particle devolatilization machine:

s321: the material enters a second receiving groove from a second discharge hole, enters a spiral conveyor of the secondary particle devolatilizer through a second feed hole, continuously works, conveys the material upwards, discharges the material from an opening at the upper end of the shell, and falls back into a second storage bin; blowing out hot air generated by the air blowing component through the ventilation channel, and reheating and drying the falling particulate material to devolatilize the particulate material again; in the process, the third discharge port is opened, and the fourth discharge port is closed;

s322: the materials falling back into the second hopper enter the second receiving groove through the third discharge hole, are mixed with the materials just entering the second receiving groove from the second discharge hole, enter the spiral conveyor of the secondary particle devolatilizer through the second feed hole, and repeat the step S321, so that the materials are circularly conveyed in the secondary particle devolatilizer to perform multiple devolatilization;

s323: continuously repeating the step S322, closing the second discharge hole after the height of the materials piled up in the first hopper is reduced to a set value, so that the materials in the primary particle devolatilizer start to be piled up again in the first hopper; the material is circularly devolatilized in a secondary particle devolatilizing machine, and when the devolatilization time in the stage reaches a set value, the secondary devolatilization of the particle material is completed; then closing the third discharge hole, opening the fourth discharge hole, and discharging the devolatilized material from the fourth discharge hole;

s33: after the discharging of the granular materials in the second hopper is completed, the third discharging port is opened, and the fourth discharging port is closed;

s4: and (3) repeating the step (S3) to continuously devolatilize the materials.

10. The method for devolatilizing VOCs and odor in thermoplastic polymer material as defined in claim 9, wherein the air velocity and temperature of the hot air generated by said air blowing assembly are all adjustable according to material properties; the devolatilization time of the materials in the secondary particle devolatilizer is set according to the material properties.

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