Tackifier and tackifying unit for recycling PET (Polyethylene Terephthalate)

Abstract

The tackifier comprises a tackifying cylinder, the lower end of the tackifying cylinder is connected with a discharging hopper, the discharging hopper comprises an inner hopper body, a middle hopper body and an outer hopper body from inside to outside, the inner hopper body, the middle hopper body and the outer hopper body are all fixedly connected through annular connecting plates, the outer hopper body is provided with a nitrogen total gas port, and the nitrogen total gas port is connected with the middle hopper body. An outer annular cavity is formed between the outer hopper and the middle hopper, an inner annular cavity is formed between the middle hopper and the inner hopper, the nitrogen total gas port is communicated with the outer annular cavity, the upper portion and the lower portion of the outer annular cavity are communicated with the upper portion and the lower portion of the inner annular cavity respectively, a plurality of air inlet holes are further formed in the hopper wall of the inner hopper, and an air extractor is arranged at the top of the tackifying barrel. And a negative pressure vacuum meter and a thermometer are arranged on the tackifying cylinder. According to the tackifier, heated nitrogen is used for heating a PET material, negative-pressure air exhaust is carried out while heating is carried out, the material is prevented from making contact with oxygen in the reaction process, and therefore the color of the tackified PET material is whiter and closer to that of a new material.

Description

Technical Field

[0001] The utility model relates to the technical field of PET recycling, in particular to a tackifier and a tackifier unit for PET recycling. Background Art

[0002] In the field of PET recycling technology, a viscosity-enhancing machine is generally used for viscosity-enhancing. Due to the complex sources of recycled polyester and the difficulty in ensuring consistent composition, the viscosity of the melt fluctuates greatly during the production process. In order to stabilize the viscosity and ensure that it is suitable for secondary use, the current viscosity-enhancing machine mainly heats the PET material inside the reactor through a reactor and thermal oil heating. For example, the viscosity-enhancing device disclosed in the publication of the authorization announcement number CN220328623U, a solid-phase viscosity-enhancing device with low thermal oil volatility, uses thermal oil to heat the reactor to heat the PET material inside, and the internal stirring device is required to ensure uniform heating.

[0003] However, this type of viscosity-enhancing device still has the following disadvantages: 1. The space utilization of this reactor is relatively small. A stirring device needs to be installed inside the reactor, which takes up a certain amount of space, resulting in a reduction in the space for material storage inside, which makes the size of the entire device relatively large. Moreover, since the heat transfer oil is hotter on the side walls of the reactor, the temperature of the side walls will always be higher than that of the middle part. Therefore, even if the material is stirred, the heating uniformity cannot be guaranteed. 2. The efficiency of this viscosity-enhancing device is relatively low. In order to ensure that the reaction time of the PET material in the reactor is consistent, the reactor needs to be filled with PET material first, then the polymerization reaction is carried out for a certain period of time, and then the material in the reactor is discharged. The entire process requires a one-time filling and one-time discharge, resulting in a long interval time. 3. The reactor is not isolated from oxygen in the air during the reaction, resulting in the color of the viscosity-enhanced PET material being yellowish compared to the new PET material. Therefore, this PET material cannot be used in the production of transparent PET. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a PET recycling thickening machine, which uses heated nitrogen to heat the PET material and simultaneously performs negative pressure extraction to avoid contact between the material and oxygen during the reaction, so that the color of the PET material after thickening is whiter and closer to that of new material.

[0005] Another technical problem to be solved by the present invention is to provide a PET recycling thickening unit, which connects an infrared dehumidification crystallization drying integrated machine with the thickening machine. The PET material after recovery and granulation enters the infrared dehumidification crystallization drying integrated machine for infrared heating and crystallization drying, and is then directly sent to the thickening machine for thickening, thereby saving the time of thickening treatment.

[0006] In order to solve the above technical problems, the technical solution of the utility model is: a PET recycling thickening machine, comprising a vertical thickening cylinder, the upper end of the thickening cylinder is provided with a material adding port for convenient entry of PET material, a material adding device is installed on the material adding port, the lower end of the thickening cylinder is connected to a conical discharge hopper for convenient discharge, the lower end of the discharge hopper is opened and connected to a discharge control device, the discharge hopper includes an inner hopper, an intermediate hopper and an outer hopper from the inside to the outside, and the inner hopper, the intermediate hopper and the outer hopper are fixedly connected by an annular connecting plate The outer hopper is provided with a nitrogen main gas port for communicating with the hot nitrogen supply system, an outer annular chamber is provided between the outer hopper and the intermediate hopper, an inner annular chamber is formed between the intermediate hopper and the inner hopper, the nitrogen main gas port is communicated with the outer annular chamber, the upper and lower parts of the outer annular chamber and the inner annular chamber are respectively communicated, a communicating hole is provided on the annular connecting plate, and a plurality of air inlet holes are also provided on the hopper wall of the inner hopper, an exhaust device is provided on the top of the thickening cylinder, and a negative pressure vacuum gauge and a thermometer are provided on the thickening cylinder.

[0007] As a preferred solution, the outside of the viscosity-enhancing cylinder and the outside of the outer hopper are both provided with a heat-insulating layer.

[0008] As a preferred solution, a material level meter is provided on the upper portion of the viscosity increasing cylinder.

[0009] As a preferred solution, the material adding device includes a feeding bin fixed on the material adding port, a first feeding control valve is provided at the bottom of the feeding bin, a vacuum loader is fixedly installed at the upper end of the feeding bin, and a second feeding control valve is provided between the vacuum loader and the feeding bin.

[0010] As a preferred solution, the discharge control device includes a cache bin fixed on the lower opening of the discharge hopper, a first discharge control valve is arranged between the cache bin and the discharge hopper, the lower end of the cache bin is connected to a discharge bin, and a second discharge control valve is installed between the discharge bin and the cache bin.

[0011] As a preferred solution, an auxiliary heating device for auxiliary heating the viscosity-increasing cylinder is further provided in the thermal insulation layer.

[0012] As a preferred solution, sight glasses are provided on the upper and lower parts of the viscosity enhancing cylinder.

[0013] As a preferred solution, the nitrogen main gas inlet is arranged in the middle of the discharge hopper.

[0014] After adopting the above technical solution, the effect of the utility model is as follows: a PET recycling thickening machine includes a vertical thickening cylinder, the upper end of the thickening cylinder is provided with a material adding port for convenient entry of PET material, a material adding device is installed on the material adding port, the lower end of the thickening cylinder is connected to a conical discharge hopper for convenient discharge, the lower end of the discharge hopper is opened and connected to a discharge control device, the discharge hopper includes an inner hopper, an intermediate hopper and an outer hopper from the inside to the outside, and the inner hopper, the intermediate hopper and the outer hopper are fixedly connected by an annular connecting plate The outer hopper is provided with a nitrogen total gas port for communicating with the hot nitrogen supply system, an outer annular chamber is provided between the outer hopper and the intermediate hopper, an inner annular chamber is formed between the intermediate hopper and the inner hopper, the nitrogen total gas port is communicated with the outer annular chamber, the outer annular chamber and the upper and lower parts of the inner annular chamber are communicated respectively, a communicating hole is provided on the annular connecting plate, and a plurality of air inlet holes are also provided on the hopper wall of the inner hopper, an exhaust device is provided on the top of the viscosity increasing cylinder, and a negative pressure vacuum gauge and a thermometer are provided on the viscosity increasing cylinder. Therefore, the viscosity increasing machine uses heated nitrogen to enter from the nitrogen main gas port. The nitrogen line passes through the outer annular chamber and flows upward and downward, and then passes through the upper connecting chamber and the lower connecting chamber into the inner annular chamber, and enters the inner hopper evenly through the air inlet hole on the inner hopper, and gradually flows upward and is exhausted by the exhaust device at the upper end of the viscosity increasing cylinder. In this way, the whole process is protected by nitrogen to prevent the PET material from coming into contact with oxygen during the reaction and causing discoloration. At the same time, nitrogen enters the inner hopper from the bottom and top, and the nitrogen will pass through the gaps between the materials to The material is heated evenly, avoiding heating dead corners, and the heating effect is more uniform, so the stirring device is omitted, and the space utilization rate is higher. In addition, since the material is fed at the upper end and discharged at the lower end of the thickening cylinder, the time the material stays in the thickening cylinder can be controlled by controlling the feeding frequency and the discharging frequency, thereby controlling the reaction time more accurately and achieving better thickening effect. Vacuuming is performed during the heating process, and low molecular substances in the material are vaporized and extracted at high temperature, thereby improving the purity of the material. Therefore, the PET material treated by this thickening machine can be used for the production of PET bottles.

[0015] Furthermore, since the outside of the thickening cylinder and the outside of the outer hopper are both provided with a heat-insulating layer, the heat-insulating layer can keep the thickening cylinder warm and avoid heat loss.

[0016] Furthermore, since a material level meter is provided on the upper portion of the viscosity increasing cylinder, the material level meter can detect the height of the material in the viscosity increasing cylinder to ensure that the amount of material added is appropriate.

[0017] Since the material adding device includes a feeding bin fixed on the material adding port, a first feeding control valve is provided at the bottom of the feeding bin, a vacuum loader is fixedly installed at the upper end of the feeding bin, and a second feeding control valve is provided between the vacuum loader and the feeding bin. Therefore, when adding materials, the vacuum loader can deliver the PET material to the feeding bin. When the material in the feeding bin is full, the vacuum loader can stop feeding, and at the same time, the first feeding control valve at the bottom of the feeding bin is opened to add the material in the entire feeding bin into the thickening cylinder, so that the volume of material added each time is the same.

[0018] Furthermore, since the discharge control device includes a buffer bin fixed on the lower opening of the discharge hopper, a first discharge control valve is provided between the buffer bin and the discharge hopper, the lower end of the buffer bin is connected to a discharge bin, and a second discharge control valve is installed between the discharge bin and the buffer bin. Similarly, when the material needs to be turned over, the material is first placed in the buffer bin for cache. At this time, the size of the buffer bin is set to be consistent with the size of the feeding bin, so that the feeding amount and the discharge amount can be kept consistent, thereby accurately controlling the heating reaction time of the material.

[0019] Furthermore, since the thermal insulation layer is also provided with an auxiliary heating device for auxiliary heating of the thickening cylinder, when the temperature in the thickening cylinder does not meet the standard, auxiliary heating can be performed by the auxiliary heating device to meet the heating requirements in some low temperature environments.

[0020] In order to solve the above-mentioned second technical problem, the solution of the utility model is: to provide a PET recycling viscosity increasing unit, which includes an infrared dehumidification crystallization drying all-in-one machine and the PET recycling viscosity increasing machine, the discharge port of the infrared dehumidification crystallization drying all-in-one machine is connected to the feeding port of the material adding device through a material conveying pipe, and the hot nitrogen supply system is connected to the nitrogen total gas port through a pipeline.

[0021] Further preferably, the material adding device includes a feeding bin fixed on the material adding port, a first feeding control valve is provided at the bottom of the feeding bin, a vacuum loader is fixedly installed at the upper end of the feeding bin, a second feeding control valve is provided between the vacuum loader and the feeding bin, and the hot nitrogen gas supply system is also connected to the vacuum loader.

[0022] After adopting the above technical solution, the effect of the utility model is: the infrared dehumidification, crystallization and drying integrated machine can heat, dry and crystallize PET particles, so that the moisture content of the PET particles is controlled very low, and then the crystallized PET particles are sent to the thickening cylinder of the thickening machine, so that the heat of the PET particles themselves is not lost, which can further shorten the thickening time. At the same time, the thickening cylinder is heated by heated nitrogen, which makes the heating more uniform and can also prevent the PET particles from coming into contact with oxygen and causing discoloration.

[0023] Furthermore, since the material adding device includes a feeding bin fixed on the material adding port, a first feeding control valve is provided at the bottom of the feeding bin, a vacuum loader is fixedly installed at the upper end of the feeding bin, a second feeding control valve is provided between the vacuum loader and the feeding bin, and the hot nitrogen gas supply system is also connected to the vacuum loader. Therefore, the hot nitrogen gas supply system supplies heated nitrogen to the vacuum loader. Therefore, the vacuum loader also uses hot nitrogen as the gas source for feeding, thereby ensuring nitrogen protection during the transportation process to avoid contact with oxygen. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Figure 1 It is a structural cross-sectional view of an embodiment of the utility model;

[0026] Figure 2 yes Figure 2 A partial enlarged schematic diagram;

[0027] Figure 3 It is a structural schematic diagram of the viscosity increasing unit in the embodiment of the utility model;

[0028] In the attached figure: 1, viscosity increasing cylinder; 2, vacuum loader; 3, feeding bin; 4, second feeding control valve; 5, first feeding control valve; 6, exhaust device; 7, discharge hopper; 8, sight glass; 9, frame; 10, insulation layer; 11, material level meter; 12, negative pressure vacuum gauge; 13, thermometer; 14, buffer bin; 15, discharge bin; 16, first discharge control valve; 17, second discharge control valve; 18, extraction pipe; 71, inner hopper; 72, intermediate material Bucket; 73, outer hopper; 74, annular connecting plate; 75, outer annular chamber; 76, upper connecting chamber; 77, inner annular chamber; 78, lower connecting chamber; 79, nitrogen main air port; 710, air inlet; 100, viscosity enhancer; 200, infrared dehumidification crystallization drying integrated machine; 2001, feeding device; 2002, barrel; 2003, light box; 2004, discharge bin; 300, material conveying pipeline; 400, hot nitrogen supply system. DETAILED DESCRIPTION

[0029] The present invention will be described in further detail below through specific embodiments.

[0030] like Figure 1 and Figure 2As shown, a PET recycling thickening machine includes a vertical thickening cylinder 1, which is fixed on a frame 9 and arranged in an upright manner. The upper end of the thickening cylinder 1 is provided with a material addition port for facilitating the entry of PET materials, and a material addition device is installed on the material addition port. The material addition device includes a feeding bin 3 fixed on the material addition port, a first feeding control valve 5 is provided at the bottom of the feeding bin 3, a vacuum feeder 2 is fixedly installed on the upper end of the feeding bin 3, and a second feeding control valve 4 is provided between the vacuum feeder 2 and the feeding bin 3. The first feeding control valve 5 and the second feeding control valve 4 can be selected as pneumatic butterfly valves. The vacuum feeder 2 is a conventional feeding device currently used and is a conventional technology in this field.

[0031] The lower end of the viscosity increasing cylinder 1 is connected to a conical discharge hopper 7 for convenient discharge of materials. The lower end of the discharge hopper 7 is opened and connected to a discharge control device.

[0032] In this embodiment, the discharge control device includes a buffer bin 14 fixed to the lower opening of the discharge hopper 7, a first discharge control valve 16 is provided between the buffer bin 14 and the discharge hopper 7, the lower end of the buffer bin 14 is connected to a discharge bin 15, and a second discharge control valve 17 is installed between the discharge bin 15 and the buffer bin 14. Similarly, the first discharge control valve 16 and the first discharge control valve 16 also adopt pneumatic butterfly valves, and the bottom of the discharge bin 15 is connected to a suction pipe 18 to facilitate the discharge of materials.

[0033] like Figure 2 As shown, the discharge hopper 7 includes an inner hopper 71, an intermediate hopper 72 and an outer hopper 73 from the inside to the outside. The inner hopper 71, the intermediate hopper 72 and the outer hopper 73 are fixedly connected by an annular connecting plate 74. The annular connecting plate 74 is provided with communicating holes. The number of communicating holes is multiple and evenly distributed around the circumference, so that nitrogen can pass through evenly. Of course, the annular connecting plate 74 can also be replaced with discrete connecting blocks. The spacing formed between the connecting blocks can facilitate the passage of nitrogen.

[0034] The outer hopper 73 is provided with a nitrogen main gas port 79 for communicating with a hot nitrogen gas supply system. The hot nitrogen gas supply system heats nitrogen before it enters through the nitrogen main gas port 79. The nitrogen main gas port 79 is preferably located in the middle of the discharge hopper 7 so that the nitrogen flows upward or downward after entering, avoiding the situation where the nitrogen enters from a concentrated position and causes uneven heating.

[0035] An outer annular chamber 75 is provided between the outer hopper 73 and the intermediate hopper 72, and an inner annular chamber 77 is formed between the intermediate hopper 72 and the inner hopper 71. The nitrogen total gas port 79 is connected to the outer annular chamber 75, and an upper connecting chamber 76 is formed between the upper part of the outer hopper 73 and the upper part of the inner hopper 71. A lower connecting chamber 78 is formed between the lower part of the outer hopper 73 and the lower part of the inner hopper 71. The upper connecting chamber 76 and the lower connecting chamber 78 connect the upper and lower parts of the outer annular chamber 75 and the inner annular chamber 77 respectively. Several air inlet holes 710 are also provided on the hopper wall of the inner hopper 71. An exhaust device 6 is provided on the top of the thickening cylinder 1, and a negative pressure vacuum gauge 12 and a thermometer 13 are provided on the thickening cylinder 1. The negative pressure vacuum gauge 12 and the thermometer 13 monitor the pressure and temperature inside the thickening cylinder 1 in real time to ensure that the reaction of the PET material is carried out under a suitable process parameter. A material level meter 11 is provided on the upper portion of the viscosity increasing cylinder 1 to control the upper limit position of the material.

[0036] The exhaust device 6 includes an exhaust hood arranged on the top of the thickening cylinder 1. The exhaust port of the exhaust hood extends out of the thickening cylinder 1 and is connected to the exhaust pump, so that the internal gas is continuously extracted.

[0037] The outside of the thickening cylinder 1 and the outside of the outer hopper 73 are both provided with a heat-insulating layer 10, and the heat-insulating layer 10 can be made of heat-insulating cotton or other heat-insulating materials.

[0038] The insulation layer 10 is also provided with an auxiliary heating device for auxiliary heating of the viscosity increasing cylinder 1. The auxiliary heating device can be assisted by electric heating or thermal oil heating. Under normal circumstances, no pneumatic operation is required, and only the nitrogen temperature needs to be controlled. In special circumstances, such as when the nitrogen heating device fails and the nitrogen temperature is insufficient, the auxiliary heating device can be activated to replenish energy.

[0039] The upper and lower parts of the viscosity increasing cylinder 1 are both provided with sight glasses 8, which makes it easy to observe the condition of the internal material.

[0040] The working principle of the present invention is: first, the PET material is delivered to the feeding bin 3 by the vacuum feeder 2, and then the material is delivered to the thickening cylinder 1 through the first feeding control valve 5. When the material in the thickening cylinder 1 reaches the upper limit, it will be detected by the level meter 11. At this time, the feeding is stopped, and the heated nitrogen is evenly introduced into the thickening cylinder 1. The upper end exhaust device 6 performs continuous exhaust to ensure that the vacuum degree in the thickening cylinder 1 reaches the set value. After heating, the PET material undergoes polyester repolymerization reaction in a vacuum environment, and the low molecular substances in the raw materials are vaporized and extracted at high temperature, thereby improving the purity of the melt. At the same time, the molecules of the PET material undergo polymerization reaction, resulting in the continuous growth of the molecular chain, thereby increasing the characteristic viscosity, and isolating oxygen, so that the color of the thickened PET material is not yellow, so it can meet the production of transparent PET bottles.

[0041] like Figure 3 As shown, Figure 3 The diagram shows a PET recycling viscosity increasing unit, which includes an infrared dehumidification crystallization drying all-in-one machine 200 and the PET recycling viscosity increasing machine 100. The discharge port of the infrared dehumidification crystallization drying all-in-one machine 200 is connected to the feeding port of the material adding device 2 through a material conveying pipe 300, and the hot nitrogen supply system 400 is connected to the nitrogen total gas port 79 through a pipeline.

[0042] The applicant has previously applied for a domestic patent for the basic structure of the infrared dehumidification crystallization drying machine, with the specific publication number being CN 214521287 U. The basic structure of the infrared dehumidification crystallization drying machine includes a rotating barrel 2002, an infrared heating light box 2003, a fan for exhausting air from the interior, a feeding device 2001 for feeding materials, and a discharge port provided on the side wall of the barrel 2002. A discharge bin 2004 is provided at the bottom of the barrel 2002. PET particles enter the barrel 2002 through the feeding device 2001. The barrel 2002 rotates and is heated internally by the infrared light box 2003, so that the particles are dried, dehumidified, and crystallized. During the dehumidification process, air is exhausted to remove the heated and evaporated moisture and impurities. When the crystallization and drying are completed, the moisture content of the PET particles is very low, and then the PET particles are discharged. The PET particles enter the discharge bin 2004 and are then transported to the viscosity increasing machine 100 through the vacuum loader 2 for viscosity increasing treatment. The material adding device includes a feeding bin 3 fixed to the material adding port, a first feeding control valve 5 is provided at the bottom of the feeding bin, and a vacuum loader 2 is fixedly installed at the upper end of the feeding bin 3. A second feeding control valve 4 is provided between the vacuum loader 2 and the feeding bin 3. The hot nitrogen gas supply system 400 is also connected to the vacuum loader 2. The discharge bin 2004 is configured as a closed structure, so that the conveying gas source of the vacuum loader 2 also uses heated nitrogen, which further protects the PET particles during the conveying process.

[0043] The hot nitrogen supply system 400 in this embodiment may be composed of a nitrogen recovery system and a nitrogen heating supply system to achieve nitrogen recovery and reuse.

[0044] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Various modifications and alterations to the technical solutions of the present invention, without departing from the spirit of the present invention, should fall within the scope of protection defined in the claims of the present invention.

Claims

1. A PET recycling tackifier, characterized in that: The invention comprises a vertical viscosity increasing cylinder, the upper end of which is provided with a material adding port for facilitating the entry of PET material, a material adding device being installed on the material adding port, the lower end of the viscosity increasing cylinder being connected to a conical discharge hopper for facilitating discharge, the lower end of the discharge hopper being opened and connected to a discharge control device, the discharge hopper comprising an inner hopper, an intermediate hopper and an outer hopper from the inside out, the inner hopper, the intermediate hopper and the outer hopper being fixedly connected by an annular connecting plate, the outer hopper being provided with a connection plate for contacting with hot nitrogen The nitrogen total gas port is connected to the air supply system, an outer annular chamber is provided between the outer hopper and the intermediate hopper, an inner annular chamber is formed between the intermediate hopper and the inner hopper, the nitrogen total gas port is connected to the outer annular chamber, the upper and lower parts of the outer annular chamber and the inner annular chamber are respectively connected, a connecting hole is provided on the annular connecting plate, and a plurality of air inlet holes are also provided on the hopper wall of the inner hopper, an exhaust device is provided on the top of the thickening cylinder, and a negative pressure vacuum gauge and a thermometer are provided on the thickening cylinder.

2. A PET recycling tackifier according to claim 1, characterized in that: The outside of the viscosity increasing cylinder and the outside of the outer hopper are both provided with a heat insulation layer.

3. A PET recycling tackifier as claimed in claim 2, characterized in that: A material level meter is provided on the upper portion of the viscosity increasing cylinder.

4. A PET recycling viscosity increasing machine as claimed in claim 1, characterized in that: The material adding device includes a feeding bin fixed on the material adding port, a first feeding control valve is provided at the bottom of the feeding bin, a vacuum loader is fixedly installed at the upper end of the feeding bin, and a second feeding control valve is provided between the vacuum loader and the feeding bin.

5. A PET recycling viscosity increasing machine as claimed in claim 1, characterized in that: The discharge control device includes a buffer bin fixed on the lower opening of the discharge hopper, a first discharge control valve is provided between the buffer bin and the discharge hopper, the lower end of the buffer bin is connected to a discharge bin, and a second discharge control valve is installed between the discharge bin and the buffer bin.

6. A PET recycling viscosity increasing machine as claimed in claim 2, characterized in that: The thermal insulation layer is also provided with an auxiliary heating device for auxiliary heating of the viscosity increasing cylinder.

7. A PET recycling viscosity increasing machine as claimed in claim 1, characterized in that: The upper and lower parts of the viscosity increasing cylinder are both provided with sight glasses.

8. A PET recycling viscosity increasing machine as claimed in claim 1, characterized in that: The nitrogen main gas port is set in the middle of the discharge hopper.

9. A PET recovery and thickening unit, characterized by: The viscosity increasing unit includes an infrared dehumidification crystallization drying integrated machine and a PET recycling viscosity increasing machine as described in any one of claims 1 to 8, the discharge port of the infrared dehumidification crystallization drying integrated machine is connected to the feeding port of the material adding device through a material conveying pipeline, and the hot nitrogen gas supply system is connected to the nitrogen total gas port through a pipeline.

10. A PET recycling viscosity increasing unit according to claim 9, characterized in that: The material adding device includes a feeding bin fixed on the material adding port, a first feeding control valve is provided at the bottom of the feeding bin, a vacuum loader is fixedly installed at the upper end of the feeding bin, a second feeding control valve is provided between the vacuum loader and the feeding bin, and the hot nitrogen gas supply system is also connected to the vacuum loader.

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