A co-pyrolysis process based on plastics and biomass

Abstract

The application discloses a kind of based on plastic and biomass's co-pyrolysis process, belong to biomass pyrolysis technical field, including the following steps: S1, plastic raw materials are subjected to ultraviolet irradiation;S2, plastic raw materials obtained in S1 are pulverized with biomass raw materials, and raw material particles are obtained;S3, raw material particles obtained in S2 are dried;S4, raw material particles after drying are sent to co-pyrolysis furnace for pyrolysis reaction, and co-pyrolysis product is obtained, and co-pyrolysis product includes pyrolysis gas, biochar and pyrolysis oil;S5, pyrolysis gas, biochar and pyrolysis oil in S4 are collected;The application can improve co-pyrolysis efficiency, increase the yield of pyrolysis gas and biochar;The phenomenon that pyrolysis product can be effectively avoided in the process of collecting and blocking pipeline, ensure continuous operation.

Description

Technical Field

[0001] This invention relates to a co-pyrolysis process based on plastics and biomass, belonging to the field of biomass pyrolysis technology. Background Technology

[0002] Co-pyrolysis of plastics (including common plastics such as polyethylene, polypropylene, and polyethylene terephthalate) and biomass (mainly solid biomass, such as crop straw and forestry residues) can improve product quality. Plastics have a higher hydrogen-to-carbon ratio (H / C) and a relatively lower oxygen-to-carbon ratio (O / C), which supports the inherently high O / C and low H / C of solid biomass, thus improving product quality and uniformity while minimizing coke deposition that occurs during the pyrolysis of pure plastic waste. Co-pyrolysis has great potential for mixed wastes by minimizing the need for waste separation. The pyrolysis of plastics can provide pyrolysis oil and syngas with higher hydrogen content and calorific value, while reducing oxygen content, thereby improving oil performance. However, these processes are prone to scalability issues, such as pipeline blockage due to the high viscosity of molten or softened plastics, as well as fluidization inhibition. During experiments, coking also occurred in the reactor, leading to downstream blockage and a decrease in product yield and quality, and increasing the difficulty of experimental operation.

[0003] Patent CN 113122296 A proposes a method for co-pyrolysis of biomass and agricultural film based on a double-cylinder structure. This method effectively solves the problem of breaking the molten plastic layer coating the surface of biomass during co-pyrolysis, while also promoting raw material propulsion and localized stirring. The yield and quality of the co-pyrolysis products are improved, resulting in higher overall industrial application value. While this patent reduces the adhesion between the biomass and molten plastic layers, it does not solve the problem of pipeline blockage caused by the high viscosity of the molten or softened plastic. The discharge port is narrow, and separate discharge still easily leads to adhesion of the discharge pipeline. Furthermore, the pyrolysis furnace design is complex, resulting in high manufacturing costs.

[0004] Patent CN215929558U discloses an industrial solid waste pyrolysis device with anti-clogging function. Its structure includes a placement box, a feed pipe, a feeding plate, and a pretreatment component. This patented pretreatment component uses a transmission belt to drive a straight rod to rotate on a crossbeam, causing the upper cone to contact the waste and disperse it, ensuring orderly entry and preventing accumulation and blockage. Although separating the waste before pyrolysis prevents pipeline blockage, the pyrolysis oil generated after pyrolysis still needs to be collected through the pipeline. This patent does not design a dedicated system for treating this issue, making it difficult to avoid the problem of pyrolysis reaction products clogging the pipeline, resulting in a shorter equipment lifespan.

[0005] In summary, existing internal heating pyrolysis processes and equipment for plastics and biomass have problems such as adhesion and coking of pyrolysis products and low carbon and gas production under continuous operation conditions. Although high temperature can fully burn tar, it cannot completely avoid tar production. Moreover, in most cases, coking after co-pyrolysis of plastics and biomass will still cause pipeline blockage during continuous operation, thus failing to guarantee continuous operation.

[0006] In conclusion, the existing technology obviously has inconveniences and defects in practical use, so it is necessary to improve it. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the above-mentioned shortcomings by providing a co-pyrolysis process based on plastics and biomass, which can achieve the following objectives: 1. It can improve co-pyrolysis efficiency and increase the yield of pyrolysis gas and biochar; 2. It can effectively avoid the phenomenon of pipeline blockage caused by pyrolysis products during the collection process, ensuring continuous operation.

[0008] To solve the above technical problems, the present invention adopts the following technical solution: a co-pyrolysis process based on plastics and biomass, comprising the following steps: S1, ultraviolet irradiation of plastic raw materials; The plastic raw materials obtained in S2 and S1 are crushed together with the biomass raw materials to obtain raw material pellets; The raw material particles obtained in S3 and S2 are dried. S4, the dried raw material particles are sent to a co-pyrolysis furnace for pyrolysis reaction to obtain co-pyrolysis products, including pyrolysis gas, biochar and pyrolysis oil. S5 collects the pyrolysis gas, biochar, and pyrolysis oil from S4.

[0009] Furthermore, in S1, an ultraviolet irradiation box is used to irradiate the plastic raw material. An ultraviolet irradiation lamp is installed inside the ultraviolet irradiation box. The ultraviolet center wavelength of the ultraviolet irradiation lamp is 254nm and the power is 20W. The ultraviolet irradiation time is 24 hours.

[0010] Furthermore, in S2, a hammer mill is used to crush the raw materials; The diameter of the crushed raw material particles is 5~10mm and the length is <20mm.

[0011] Furthermore, in S3, a vacuum drying oven is used to dry the raw material particles; The drying temperature is RT+10℃~200℃, the vacuum degree is 133Pa, and the temperature control accuracy is ±1℃.

[0012] Furthermore, in S5, a portion of the pyrolysis gas is collected after condensation, while another portion is sent back to the pyrolysis furnace to participate in the co-pyrolysis reaction again. Biochar and the pyrolysis oil mixed in with the biochar are directly collected in the co-pyrolysis product collection bin.

[0013] Furthermore, the co-pyrolysis product collection chamber is located at the bottom of the co-pyrolysis furnace, the inner cavity of the co-pyrolysis furnace and the co-pyrolysis product collection chamber are connected, and an openable discharge door is provided between the inner cavity of the co-pyrolysis furnace and the co-pyrolysis product collection chamber.

[0014] Furthermore, the discharge gate includes two openable and closable door panels, which can rotate towards or away from each other; The co-pyrolysis furnace is equipped with two automatic scrapers, each corresponding to one of the two door panels.

[0015] Furthermore, the co-pyrolysis furnace is equipped with a compactor that can move up and down; The compactor includes a pressure bar that can slide through the top wall of the co-pyrolysis furnace, and a pressure plate for compacting the raw materials is fixed at the lower part of the pressure bar.

[0016] Furthermore, the automatic scraper includes a scraper blade adapted to the length of the door panel, and the scraper blade is fixed to the lower end of the scissor-type telescopic mechanism; The upper end of the scissor-type telescopic mechanism is installed on the furnace body of the co-pyrolysis furnace. The scissor-type telescopic mechanism extends and retracts in an inclined direction, and the inclination angle of the scissor-type telescopic mechanism is the same as the inclination angle after the door panel is opened.

[0017] Furthermore, the side of the door panel is fixed on a rotating shaft, which is rotatably mounted on the pyrolysis furnace body; one end of the rotating shaft extends out of the pyrolysis furnace body and is connected to the motor drive.

[0018] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages: 1. This invention involves irradiating plastic raw materials with ultraviolet light, pulverizing the irradiated plastic raw materials together with biomass raw materials, and then performing pretreatment operations such as drying. The pretreated raw materials are then subjected to co-pyrolysis reaction, which can improve the co-pyrolysis efficiency and increase the yield of biochar, pyrolysis oil and pyrolysis gas.

[0019] 2. In this invention, by directly feeding the biochar and the pyrolysis oil mixed therewith into the co-pyrolysis product collection chamber for collection, the phenomenon of pyrolysis products clogging the pipeline during the collection process can be effectively avoided, ensuring continuous operation.

[0020] 3. This invention adopts a method in which the co-pyrolysis product collection bin is directly connected to the bottom of the co-pyrolysis furnace, with the inner cavities of the two connected, and an automatically opening and closing discharge door is set between them. This allows the co-pyrolysis products to directly enter the co-pyrolysis product collection bin, avoiding the need to pass through pipelines. This solves the problem of co-pyrolysis products clogging pipelines in the prior art, and improves the service life of the equipment by 30%. In addition, an automatic scraper is set up. The automatic scraper drives the scraper to move through a scissor telescopic mechanism to clean the residual co-pyrolysis products on the discharge door panel.

[0021] 4. The present invention includes a raw material pretreatment step, a co-pyrolysis step, and a product collection step. It is applicable to co-pyrolysis raw materials of various proportions, can reduce the manpower and material resources for screening and sorting, and can improve the processing efficiency of waste plastics and biomass.

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a three-dimensional view of a co-pyrolysis furnace; Figure 3 This is a cross-sectional view of a co-pyrolysis furnace; Figure 4 This is another cross-sectional view of the co-pyrolysis furnace.

[0024] In the picture, 1-Plastic feed hopper, 2-Support frame, 3-UV irradiation box, 4-Biomass feed hopper, 5-Raw material conveyor belt, 6-Pulverizing device, 7-Drying device, 8-Screw conveyor, 9-Co-pyrolysis furnace, 91-Feed inlet, 92-Discharge door, 921-Door panel, 922-Rotating shaft, 93-Gas outlet, 94-Gas outlet pipe, 95-Return gas pipe, 96-Return gas valve, 97-Gas inlet, 98-Compactor, 981-Pressure rod, 982-Pressure plate, 99-Automatic scraper, 991-Scraper, 992-Scissor-type telescopic mechanism, 910-Mounting hole, 911-Ignition device mounting hole, 10-Co-pyrolysis product collection bin, 101-Binary door, 11-First condenser, 12-First condensate collection tank, 13-Second condenser, 14-Second condensate collection tank, 15-Gas collection tank. Detailed Implementation

[0025] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings. Example

[0026] like Figure 1-4As shown in the figure, the present invention provides a co-pyrolysis process based on plastics and biomass. The process adopts a co-pyrolysis device based on plastics and biomass. The co-pyrolysis device includes a co-pyrolysis furnace 9, which is a square cylindrical structure. The co-pyrolysis furnace 9 is provided with a feed inlet 91. The feed inlet of the co-pyrolysis furnace 9 is connected to a raw material pretreatment system through a screw conveyor 8. The raw material pretreatment system pretreats the plastic and biomass raw materials supplied for pyrolysis.

[0027] The bottom of the co-pyrolysis furnace 9 is provided with a co-pyrolysis product collection bin 10. The inner cavities of the co-pyrolysis furnace 9 and the co-pyrolysis product collection bin 10 are connected, and an openable and closable discharge door 92 is provided between the inner cavities of the co-pyrolysis furnace 9 and the co-pyrolysis product collection bin 10. When the raw material in the co-pyrolysis furnace 9 is co-pyrolyzed, the discharge door 92 is in the closed state. After the co-pyrolysis is completed, the discharge door 92 is opened, and the solid co-pyrolysis product in the co-pyrolysis furnace 9 automatically falls into the co-pyrolysis product collection bin 10. The top of the co-pyrolysis furnace 9 is provided with a gas outlet 93. The end of the gas outlet pipe 94 is connected to the first condenser 11 and the second condenser 13 in sequence. The pyrolysis gas enters the first condenser 11 and the second condenser 13 in sequence through the gas outlet 93 for condensation. The gas outlet of the second condenser 13 is connected to the gas collection tank 15 through a pipe for collecting the remaining gas products after condensation.

[0028] Furthermore, the condensate outlets of the first condenser 11 and the second condenser 13 are respectively connected to a first condensate collection tank 12 and a second condensate collection tank 14 for collecting condensate.

[0029] An air inlet 97 is provided on the upper side wall of the co-pyrolysis furnace 9; an air outlet 93 is connected to an air outlet pipe 94, and a return gas pipe 95 is connected to the air outlet pipe 94. The return gas pipe 95 is connected to the air inlet 97, and a return gas valve 96 is provided on the return gas pipe 95. When the return gas valve 96 is opened, a portion of the co-pyrolysis gas flows back into the co-pyrolysis furnace 9 through the return gas pipe 95 and the air inlet 97.

[0030] The pretreatment system includes an ultraviolet irradiation box 3, a crushing device 6, and a drying device 7 connected in sequence by a material conveyor belt 5. The material conveyor belt 5 is mounted on a support frame 2, and the ultraviolet irradiation box 3 is positioned above the material conveyor belt 5. An ultraviolet irradiation lamp is installed inside the ultraviolet irradiation box 3 to irradiate the plastic material on the material conveyor belt 5. A plastic feed hopper 1 is provided on the side of the ultraviolet irradiation box 3 near the feed end of the material conveyor belt 5, through which the plastic material is fed into the material conveyor belt 5 covered by the ultraviolet irradiation box 3.

[0031] The ultraviolet irradiation box 3 has an opening at the end away from the plastic feed hopper 4, allowing the raw material conveyor belt 5 and the raw materials on it to pass through. The raw material conveyor belt 5 is equipped with a biomass feed hopper 4 near the opening of the ultraviolet irradiation box 3. The biomass feed hopper 4 covers the raw material conveyor belt 5, and the biomass raw materials enter the raw material conveyor belt 5 through the biomass feed hopper 4, mixing with the plastic raw materials covered by the ultraviolet irradiation box 3.

[0032] The crushing device 6 is located behind the biomass feed hopper 4. The crushing device 6 is a hammer mill. When the hammer mill is working, it crushes the material by the combined action of the high-speed rotating hammer blades striking the material in the crushing chamber and the rubbing action of the toothed plates and other components in the crushing chamber.

[0033] The discharge port of the crushing device 6 is connected to the inlet of the drying device 7 via the raw material conveyor belt 5. The drying device 7 is a vacuum drying box, and the discharge port of the drying device 7 is connected to the screw conveyor 8.

[0034] The co-pyrolysis furnace 9 is equipped with a vertically movable compactor 98, which compacts the raw materials entering the co-pyrolysis furnace 9. The compactor 98 includes a pressure rod 981 that slidably penetrates the top wall of the co-pyrolysis furnace 9. The lower part of the pressure rod 981 is fixed with a pressure plate 982 for compacting the raw materials. The upper part of the pressure rod 981 is connected to a drive motor through a transmission structure. The transmission structure can be a gear and rack structure or the like, which converts the rotational motion of the drive motor into the vertical linear motion of the pressure rod 981.

[0035] The discharge gate 92 includes two door panels 921 that can be opened and closed relative to each other. The two door panels 921 can rotate towards or away from each other to open or close. The side of the door panel 921 is fixed on the rotating shaft 922. The rotating shaft 921 is rotatably mounted on the furnace body of the co-pyrolysis furnace 9. One end of the rotating shaft 921 extends out of the furnace body of the co-pyrolysis furnace 9 and is connected to the motor drive.

[0036] After the discharge door 92 is opened, most of the co-pyrolysis products fall directly into the co-pyrolysis product collection bin 10. However, some co-pyrolysis products will adhere to the discharge door 92. In order to clean the pyrolysis products adhering to the discharge door 92, the co-pyrolysis furnace 9 is equipped with two automatic scrapers 99, which correspond one-to-one with two door panels 921. The automatic scraper 99 includes a scraper 991, which is adapted to the length of the door panel 921. The scraper 991 is fixed to the lower end of the scissor-type telescopic mechanism 992. The upper end of the scissor-type telescopic mechanism 992 is installed on the furnace body of the co-pyrolysis furnace 9. The scissor-type telescopic mechanism 992 extends and retracts in an inclined direction. The inclination angle of the scissor-type telescopic mechanism 992 is the same as the inclination angle of the door panel 921 after it is opened.

[0037] It should be noted that the specific structure of the scissor telescopic mechanism 992 is existing technology and will not be described in detail here.

[0038] Furthermore, the side of the co-pyrolysis product collection chamber 10 is provided with a chamber door 101, which can be opened and closed to facilitate the collection of biochar and to ensure unobstructed access from the co-pyrolysis furnace 9 to the co-pyrolysis product collection chamber 10.

[0039] Furthermore, the co-pyrolysis furnace 9 is provided with mounting holes 910, and a temperature sensor is installed in the mounting holes 910 to detect the temperature inside the co-pyrolysis furnace 9; preferably, two mounting holes 910 are provided, and the two mounting holes 910 are respectively provided on opposite side walls of the co-pyrolysis furnace 9.

[0040] Furthermore, an igniter mounting hole 911 is provided on the bottom side wall of the co-pyrolysis furnace 9, and an igniter is installed in the igniter mounting hole 911 for igniting the raw materials in the co-pyrolysis furnace 9.

[0041] The co-pyrolysis process based on plastics and biomass includes the following steps: Step 1: Raw material pretreatment; The raw material pretreatment includes ultraviolet irradiation of plastic raw materials, crushing of plastic and biomass raw materials, and drying of raw materials.

[0042] Ultraviolet irradiation of plastic raw materials: Plastic is fed into the ultraviolet irradiation chamber through a plastic hopper onto a conveyor belt; the plastic raw materials are then irradiated with ultraviolet light inside the chamber.

[0043] The UV irradiation center wavelength of the UV lamp is 254nm, the power is 20W, and the irradiation time is 24 hours.

[0044] Crushing plastic and biomass raw materials: After UV irradiation, the plastic is conveyed out of the UV irradiation box by a raw material conveyor belt and fed into the crushing device together with the biomass raw materials fed from the biomass feed hopper to obtain raw material particles.

[0045] The diameter of the crushed raw material particles is 5~10mm and the length is <20mm.

[0046] Raw material drying: The pulverized raw material particles are dried via a conveyor belt drying device in a vacuum drying oven. The drying temperature is RT+10℃~200℃, the vacuum degree is 133Pa, and the temperature control accuracy is ±1℃. A counter-current drying process is used, supplemented by co-current drying. During counter-current drying, the drying medium and the mixed raw materials move in opposite directions. The mixed raw materials flow downwards continuously under their own gravity, while the hot air medium is forced upwards through the mixed raw materials under wind pressure, carrying away the moisture. This improves energy utilization efficiency and enhances the quality of the dried material.

[0047] Step 2, co-pyrolysis of raw materials The dried material is fed into the co-pyrolysis furnace by a screw conveyor, compacted by a compactor, and ignited by an igniter. The raw material in the co-pyrolysis furnace begins to burn. After the temperature sensor detects that the temperature in the co-pyrolysis furnace has risen to the reaction temperature, it enters the stable combustion stage, and the raw material begins to undergo co-pyrolysis reaction to obtain co-pyrolysis products.

[0048] The co-pyrolysis products include pyrolysis gas, biochar, and pyrolysis oil.

[0049] Step 3: Collect the co-pyrolysis products After the pyrolysis gas is discharged through the outlet, a portion of it is then sequentially fed into the first and second condensers via the outlet pipe for primary and secondary condensation. The condensed liquid products are collected in the first and second condensate collection tanks, respectively, while the condensed gas is collected in the gas collection tank via a pipe. The remaining portion of the pyrolysis gas flows back into the co-pyrolysis furnace via the return gas pipe and inlet to participate in the pyrolysis reaction again, achieving the purpose of recycling the pyrolysis gas.

[0050] After the co-pyrolysis reaction is completed, the discharge gate opens downwards, and the scissor-type telescopic mechanism drives the scraper downwards. Under its push and the gravity of the co-pyrolysis products, the biochar and the pyrolysis oil mixed on the biochar fall into the co-pyrolysis product collection chamber for collection and processing. At the same time, the co-pyrolysis product residues adhering to the door panel are cleaned by the scraper.

[0051] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A co-pyrolysis process based on plastics and biomass, characterized in that, Includes the following steps: S1, ultraviolet irradiation of plastic raw materials; The plastic raw materials obtained in S2 and S1 are crushed together with the biomass raw materials to obtain raw material pellets; The raw material particles obtained in S3 and S2 are dried. S4, the dried raw material particles are sent to a co-pyrolysis furnace for pyrolysis reaction to obtain co-pyrolysis products, including pyrolysis gas, biochar and pyrolysis oil. S5 collects the pyrolysis gas, biochar, and pyrolysis oil from S4; the biochar and the pyrolysis oil mixed in the biochar are directly collected into the co-pyrolysis product collection chamber. In S1, an ultraviolet irradiation box is used to irradiate the plastic raw material. An ultraviolet irradiation lamp is installed inside the ultraviolet irradiation box. The ultraviolet center wavelength of the ultraviolet irradiation lamp is 254nm and the power is 20W. The ultraviolet irradiation time is 24 hours. In S2, a hammer mill is used to crush the raw materials; the crushed raw material particles have a diameter of 5~10mm and a length of <20mm. In S3, a vacuum drying oven is used to dry the raw material particles; the drying temperature is RT+10℃~200℃, the vacuum degree is 133Pa, and the temperature control accuracy is ±1℃. The co-pyrolysis furnace has a square cylindrical structure; the co-pyrolysis product collection bin is located at the bottom of the co-pyrolysis furnace, the inner cavities of the co-pyrolysis furnace and the co-pyrolysis product collection bin are connected, and an openable discharge door is provided between the inner cavities of the co-pyrolysis furnace and the co-pyrolysis product collection bin; The discharge gate includes two openable and closable door panels, which can rotate towards or away from each other; the co-pyrolysis furnace is equipped with two automatic scrapers, which correspond one-to-one with the two door panels; The automatic scraper includes a scraper, the scraper being adapted to the length of the door panel, and the scraper being fixed to the lower end of the scissor-type telescopic mechanism; the upper end of the scissor-type telescopic mechanism is installed on the furnace body of the co-pyrolysis furnace, and the scissor-type telescopic mechanism extends and retracts in an inclined direction, the inclination angle of the scissor-type telescopic mechanism being the same as the inclination angle of the door panel after it is opened.

2. The co-pyrolysis process based on plastics and biomass as described in claim 1, characterized in that, In S5, a portion of the pyrolysis gas is collected after condensation, while the remaining portion is sent back to the pyrolysis furnace to participate in the co-pyrolysis reaction again.

3. The co-pyrolysis process based on plastics and biomass as described in claim 1, characterized in that, The co-pyrolysis furnace is equipped with a compactor that can move up and down. The compactor includes a pressure bar that can slide through the top wall of the co-pyrolysis furnace, and a pressure plate for compacting the raw materials is fixed at the lower part of the pressure bar.

4. The co-pyrolysis process based on plastics and biomass as described in claim 1, characterized in that, The side of the door panel is fixed on a rotating shaft, which is rotatably mounted on the pyrolysis furnace body; one end of the rotating shaft extends out of the pyrolysis furnace body and is connected to the motor drive.

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