A waste plastic pyrolysis oilization system and process

Abstract

The application provides a waste plastic pyrolysis oil system and process, which comprises a waste plastic pyrolysis system and a pyrolysis oil separation and refining system; the waste plastic pyrolysis system comprises a screening and crushing device, a pyrolysis reactor, a solid heat carrier furnace, a gas-solid separation device, a waste heat recovery system and a flue gas purification device; the pyrolysis oil separation and refining system comprises an oil washing system, a heavy oil storage tank, a staged indirect cooling system, an oil product impurity removal device and a distillate oil storage tank. The application solves the problems of poor universality, large viscosity of waste plastic melt, easy coking of the system, low oil yield, corrosion of HCl to the system and the like of the existing pyrolysis technology, and realizes resource recycling and utilization under the premise of reducing environmental pollution caused by waste plastics.

Description

Technical Field

[0001] This invention belongs to the field of waste plastic treatment technology, and specifically relates to a waste plastic pyrolysis oilification system and process. Background Technology

[0002] Due to the sheer volume and difficulty in degrading waste plastics, they cause severe environmental damage, resulting in "white pollution." Solving this problem has become a global challenge. Recycling and reusing waste plastics, turning waste into resources and transforming a "burden" into economic benefits, is the only way to address waste plastic disposal and utilization, and it is also an urgent need for ecological civilization construction.

[0003] Currently, my country's waste plastic recycling mainly includes physical recycling and chemical recycling, which are complementary. Physical recycling primarily processes "high-value waste plastics" such as PET and HDPE, and involves downgrading the plastics, with the products mainly used in fields with low requirements for plastics. Chemical recycling mainly processes "low-value waste plastics," namely waste plastics that cannot be recycled by physical recycling, have low recycling efficiency, or have been downgraded to the point of no further recycling after physical recycling. "Low-value waste plastics" account for 70% of the total, and are mainly treated through landfill and incineration for volume reduction and harmless disposal. However, these methods have poor resource utilization, generate secondary pollution, and cause serious environmental damage and resource waste. Chemical recycling of waste plastics transforms waste plastics into petrochemical products and chemical raw materials, which can be used to synthesize new plastic products with the same quality as virgin plastics, and can be used in fields with high requirements for plastics. Chemical recycling of waste plastics will become a key treatment technology for eliminating white pollution from waste plastics and realizing the resource utilization of waste plastics in the future.

[0004] Waste plastic oiling technology can convert non-recyclable waste plastics into petroleum products. The process is pollution-free and can effectively reduce environmental pollution. It can also realize the resource utilization of waste plastics and generate considerable income. It can provide the final solution for truly achieving the harmless treatment and resource utilization of waste plastics and is the main technology for the chemical recycling of waste plastics.

[0005] my country has conducted relevant research and applications in waste plastic to oil conversion technology, but there are still technical difficulties and key issues to be addressed in the development of waste plastic to oil conversion technology:

[0006] First, waste plastics are diverse in type, with significant differences in volume and density, necessitating the development of universally applicable pyrolysis technologies. Second, waste plastics have high viscosity and poor flowability, requiring careful consideration of the feeding method. Third, waste plastics have poor thermal conductivity, resulting in high viscosity of the molten material, which easily adheres to the walls, leading to carbon buildup, long reaction times, low liquid yield, reactor coking, and short operating cycles. Fourth, considering the pyrolysis characteristics, to obtain more oil, extremely rapid heating rates and extremely short residence times are required to avoid excessive coke and dry gas products generated from deep cracking. Fifth, for catalytic cracking methods, directly mixing and heating waste plastics and catalysts can easily cause supramolecular carbonization reactions at the beginning of pyrolysis, clogging the catalyst pores and hindering the catalyst's effectiveness. Sixth, due to the widespread use of PVC, without prior sorting, the generation of HCl during the pyrolysis reaction needs to be considered, as it will severely corrode equipment, and the chlorine content in the product requires further treatment. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, the inventors have conducted intensive research and developed a waste plastic pyrolysis-to-oil system and process. This system addresses problems such as poor applicability, high viscosity of molten waste plastic, easy coking of the system, low oil yield, and corrosion of the system by HCl, thus achieving resource recovery and utilization while reducing environmental pollution from waste plastics. Waste plastics are converted into oil, gas, and carbon through pyrolysis technology. The resulting pyrolysis oil is then separated to obtain distillate oil. This invention maximizes the economic benefits of pyrolysis oil while simultaneously enabling resource utilization of waste plastics and protecting the environment.

[0008] The technical solution provided by this invention is as follows:

[0009] In a first aspect, a waste plastic pyrolysis oilification system includes a waste plastic pyrolysis system and a pyrolysis oil separation and refining system;

[0010] The waste plastic pyrolysis system includes: a screening and crushing device (1a), a pyrolysis reactor (1b), a solid heat carrier furnace (1c), a gas-solid separation device (1d), a waste heat recovery system (1e), and a flue gas purification device (1f);

[0011] The material outlet of the screening and crushing device (1a) is connected to the material inlet of the pyrolysis reactor (1b), feeding the screened and crushed waste plastic along with the dechlorinating agent into the pyrolysis reactor (1b) for pyrolysis. The pyrolysis reactor (1b) is used for pre-dechlorination and pyrolysis of the waste plastic, converting it into pyrolysis oil and gas and pyrolysis carbon. The gas outlet of the pyrolysis reactor (1b) is connected to the inlet of the oil washing system (2a) in the pyrolysis oil separation and refining system, allowing the pyrolysis oil and gas to enter the oil washing system (2a). The solid outlet of the pyrolysis reactor (1b) is connected to the lower inlet of the solid heat carrier furnace (1c), allowing the heating solid heat carrier and the generated pyrolysis carbon to enter the solid heat carrier furnace (1c). The solid heat carrier furnace (1c) utilizes the pyrolysis carbon and the graded indirect... The pyrolysis gas separated by the cooling system (2c) is used as fuel to heat the solid heat carrier. The outlet of the solid heat carrier furnace is connected to the inlet of the gas-solid separation device (1d) to transport the solid heat carrier to the gas-solid separation device (1d). The outlet of the gas-solid separation device (1d) is connected to the inlet of the pyrolysis reactor (1b) and the waste heat recovery system (1e). After separating the solid heat carrier, it is sent to the pyrolysis reactor (1b) to complete the pre-dechlorination of waste plastics and the pyrolysis of waste plastics. The flue gas is sent to the waste heat recovery system (1e). The outlet of the waste heat recovery system (1e) is connected to the inlet of the flue gas purification device (1f). The high-temperature flue gas is used to heat the medium to generate steam. The cooled flue gas is sent to the flue gas purification device (1f) to purify the flue gas before being discharged.

[0012] The pyrolysis oil separation and refining system includes: an oil washing system (2a), a heavy oil storage tank (2b), a staged indirect cooling system (2c), an oil impurity removal device (2d), and a distillate oil storage tank (2e);

[0013] The liquid outlet of the oil washing system (2a) is connected to the inlet of the heavy oil storage tank (2b), and the gas outlet is connected to the inlet of the staged cooling system (2c). This system is used for dust removal and heavy oil removal from the pyrolysis oil and gas. The separated heavy oil components enter the heavy oil storage tank (2b), and the separated pyrolysis oil and gas enter the staged cooling system (2c). The outlet of the heavy oil storage tank (2b) is connected to the inlet of the pyrolysis reactor (1b), returning the heavy oil to the pyrolysis reactor (1b) for re-pyrolysis. The staged cooling system (2c)... The gas outlet of the pyrolysis gas is connected to the inlet of the solid heat carrier furnace (1c), and the liquid outlet is connected to the inlet of the oil purification device (2d). The light component distillate oil in the pyrolysis gas is condensed, and the non-condensable pyrolysis gas is sent to the solid heat carrier furnace (1c) for combustion as fuel. The distillate oil is sent to the oil purification device (2d). The outlet of the oil purification device (2d) is connected to the distillate oil storage tank (2e). After desulfurization, dechlorination, removal of organosilicon, decolorization and deodorization of the distillate oil, it is sent to the distillate oil storage tank (2e).

[0014] Secondly, a waste plastic pyrolysis-oiling process includes:

[0015] Waste plastics are fed into a screening and crushing device (1a) to recover metals and pulverize them. The crushed waste plastics and dechlorination agent are then fed into a pyrolysis reactor (1b). In the front section of the pyrolysis reactor (1b), the waste plastics are mixed with solid heat carriers and pyrolysis carbon from the tail of the pyrolysis reactor (1b) or solid heat carriers from the gas-solid separation device (1d) for low-temperature pre-dechlorination. In the middle section of the pyrolysis reactor (1b), the waste plastics are mixed with solid heat carriers from the gas-solid separation device (1d) and transformed into pyrolysis oil and gas and pyrolysis carbon under the heating of the solid heat carriers. The cooled solid heat carriers, carrying pyrolysis carbon, are output from the tail outlet of the pyrolysis reactor (1b) in two parts. One part is returned to the front section of the pyrolysis reactor for heating the waste plastics for pre-dechlorination. Chlorine; a portion enters the solid heat carrier furnace (1c), where the pyrolytic carbon is burned as fuel to heat the solid heat carrier. After the solid heat carrier is heated to the set temperature, it is conveyed to the top of the solid heat carrier furnace (1c) and enters the gas-solid separation device (1d). In the gas-solid separation device (1d), the solid heat carrier is separated into two streams, which enter the front and middle sections of the pyrolysis reactor (1b) respectively to complete the pre-dechlorination of waste plastics and heat the waste plastics. The flue gas enters the waste heat recovery system (1e) from the gas-solid separation device (1d) to heat the medium in the waste heat recovery system (1e) to generate steam. Subsequently, the cooled flue gas enters the flue gas purification device (1f) to purify the flue gas. After the flue gas meets the standards, it is discharged.

[0016] The pyrolysis oil gas enters the oil washing system (2a) from the gas outlet of the pyrolysis reactor (1b). In the oil washing system (2a), the pyrolysis oil gas is dusted and heavy oil is removed. The separated heavy oil components enter the heavy oil storage tank (2b) and are returned to the pyrolysis reactor (1b) for pyrolysis again. The separated pyrolysis oil gas enters the staged indirect cooling system (2c), where the light component distillate oil in the pyrolysis oil gas is condensed. The non-condensable pyrolysis gas enters the solid heat carrier furnace (1c) as fuel for combustion. The distillate oil passes through the oil impurity removal device (2d) for desulfurization, dechlorination, desilicon removal, decolorization, and deodorization before entering the distillate oil storage tank (2e).

[0017] The waste plastic pyrolysis oilification system and process provided by the present invention have the following beneficial effects:

[0018] (1) The present invention provides a waste plastic pyrolysis oiling system and process, which is equipped with a screening and crushing device, eliminating the need for cleaning and sorting of waste plastics, effectively reducing the difficulty of waste plastic recycling and expanding the scope of waste plastic recycling.

[0019] (2) The present invention provides a waste plastic pyrolysis oilification system and process, which uses a solid heat carrier mechanical circulation fluidization method to heat and decompose waste plastics in an oxygen-free or oxygen-deficient environment to generate pyrolysis oil and gas and pyrolysis carbon. The pyrolysis gas and pyrolysis carbon in the pyrolysis oil and gas serve as fuel to provide the energy required for the pyrolysis reaction of the system itself. At the same time, the waste heat of the high-temperature flue gas after separation is used to generate steam for the device's own use and external supply. The final output products are distillate oil and steam.

[0020] (3) The present invention provides a waste plastic pyrolysis oilification system and process, in which the waste plastic is pre-dechlorinated in the front section of the pyrolysis reactor, and the pyrolysis oil and gas are separated to obtain fractions with different temperature ranges. After further processing, they can become finished oil or chemical products, realizing the recycling of waste plastics.

[0021] (4) The waste plastic pyrolysis oilification system and process provided by the present invention are in an oxygen-free or oxygen-deficient state during the pyrolysis process, which destroys the conditions for the formation of dioxins and precursors, and can reduce / prevent the formation of dioxins. All wastewater, waste gas and waste residue generated can be discharged in compliance with standards. It has the advantages of high environmental protection indicators, good economic benefits, wide applicability, and continuous and large-scale industrial application. It can generate good economic, social and environmental benefits and provide a highly environmentally friendly and economical solution for the high-value application of low residual value waste plastics.

[0022] (5) The present invention provides a waste plastic pyrolysis oiling system and process, which uses a solid heat carrier to directly contact and grind the waste plastic, thereby achieving the self-cleaning effect of the reactor and solving the problem of equipment coking during the pyrolysis process. Attached Figure Description

[0023] Figure 1 This is a structural block diagram of a waste plastic pyrolysis oilification system according to the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of a pyrolysis reactor;

[0025] Figure 3 This is a schematic diagram of the oil washing system. Detailed Implementation

[0026] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0027] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0028] like Figure 1As shown, the present invention provides a waste plastic pyrolysis oilification system, which mainly includes a waste plastic pyrolysis system and a pyrolysis oil separation and refining system.

[0029] The waste plastic pyrolysis system includes: a screening and crushing device (1a), a pyrolysis reactor (1b), a solid heat carrier furnace (1c), a gas-solid separation device (1d), a waste heat recovery system (1e), and a flue gas purification device (1f);

[0030] The material outlet of the screening and crushing device (1a) is connected to the material inlet of the pyrolysis reactor (1b), and the screened and crushed waste plastic and dechlorinating agent are sent into the pyrolysis reactor (1b) for pyrolysis.

[0031] The pyrolysis reactor (1b) is used to pre-dechlorinate and pyrolyze waste plastics, converting them into pyrolysis oil and gas and pyrolysis carbon. The gas outlet of the pyrolysis reactor (1b) is connected to the inlet of the oil washing system (2a) in the pyrolysis oil separation and refining system, so that the pyrolysis oil and gas enter the oil washing system (2a). The solid outlet of the pyrolysis reactor (1b) is connected to the lower inlet of the solid heat carrier furnace (1c), so that the heating solid heat carrier and the generated pyrolysis carbon enter the solid heat carrier furnace (1c).

[0032] The solid heat carrier furnace (1c) uses pyrolysis carbon and pyrolysis gas separated by the staged indirect cooling system (2c) as fuel to heat the solid heat carrier. The outlet of the solid heat carrier furnace is connected to the inlet of the gas-solid separation device (1d) to transport the solid heat carrier to the gas-solid separation device (1d).

[0033] The outlet of the gas-solid separation device (1d) is connected to the inlet of the pyrolysis reactor (1b) and the waste heat recovery system (1e). After separating the solid heat carrier, it is sent to the pyrolysis reactor (1b) to complete the pre-dechlorination of waste plastic and the pyrolysis of waste plastic. The flue gas is sent to the waste heat recovery system (1e).

[0034] The outlet of the waste heat recovery system (1e) is connected to the inlet of the flue gas purification device (1f). The high-temperature flue gas is used to heat the medium (such as water) to generate steam, and the cooled flue gas is sent into the flue gas purification device (1f) for purification before being discharged.

[0035] The pyrolysis oil separation and refining system includes: an oil washing system (2a), a heavy oil storage tank (2b), a staged indirect cooling system (2c), an oil impurity removal device (2d), and a distillate oil storage tank (2e);

[0036] The liquid outlet of the oil washing system (2a) is connected to the inlet of the heavy oil storage tank (2b), and the gas outlet is connected to the inlet of the staged cooling system (2c). It is used to remove dust and heavy oil from the pyrolysis oil and gas. The separated heavy oil components enter the heavy oil storage tank (2b), and the separated pyrolysis oil and gas enter the staged cooling system (2c).

[0037] The outlet of the heavy oil storage tank (2b) is connected to the inlet of the pyrolysis reactor (1b), so that the heavy oil is returned to the pyrolysis reactor (1b) for re-pyrolysis;

[0038] The gas outlet of the staged cooling system (2c) is connected to the inlet of the solid heat carrier furnace (1c), and the liquid outlet is connected to the inlet of the oil purification device (2d). The light component distillate oil in the pyrolysis oil gas is condensed, and the pyrolysis gas (non-condensable gas) is sent into the solid heat carrier furnace (1c) for combustion as fuel. The distillate oil is sent into the oil purification device (2d).

[0039] The outlet of the oil purification device (2d) is connected to the distillate oil storage tank (2e). After desulfurization, hydrochlorination, desiliconization, decolorization and deodorization of the distillate oil, it is sent into the distillate oil storage tank (2e).

[0040] In this invention, Figure 2 A schematic diagram of the pyrolysis reactor is provided. The pyrolysis reactor (1b) includes a first reaction section as the front section and a second reaction section as the middle and rear section. The first reaction section and the second reaction section are connected head to tail. The first reaction section is equipped with a first conveying device, a waste plastic inlet (1b-1), and a front heat carrier inlet (1b-2). The second reaction section is equipped with a second conveying device, a middle and rear heat carrier inlet (1b-3), a pyrolysis gas outlet (1b-4), and a solid outlet (1b-5). The first conveying device mixes the materials in the first reaction section and transports them to the second reaction section through a connecting pipeline. The second conveying device mixes the materials in the second reaction section and transports them from the head to the tail. Pyrolysis gas is discharged from the pyrolysis gas outlet (1b-4), and solid materials are discharged from the pyrolysis reactor from the solid outlet (1b-5).

[0041] The waste plastic inlet (1b-1) and the front heat carrier inlet (1b-2) are located at the front end of the first reaction section, and waste plastic, dechlorination agent and solid heat carrier are respectively input.

[0042] The mid-to-rear section heat carrier inlet (1b-3) is located at the front end of the second reaction section, feeding in solid heat carrier; the pyrolysis gas outlet (1b-4) and solid outlet (1b-5) are located at the rear end of the second reaction section, providing sufficient reaction bed length.

[0043] The first conveying device includes a motor and a material conveying shaft. The motor output shaft is connected to the material conveying shaft, which is located within the first reaction section. The material conveying shaft includes a shaft body and propeller blades fixed to the shaft body. The motor drives the material conveying shaft to rotate, and the propeller blades mix and convey the material. Preferably, the length of the material conveying shaft body is shorter than the length of the propeller blades, and the front end of the propeller blades is a shafted propeller blade, while the rear end is a shaftless propeller blade. More preferably, the length of the material conveying shaft body is less than 1 / 3 of the length of the first reaction section, and the free end of the propeller blades is close to the end of the first reaction section.

[0044] The second feeding device has the same structure as the first feeding device, and will not be described in detail here.

[0045] The pre-dechlorination process of waste plastics is completed in the front section of the pyrolysis reactor (1b). The pre-dechlorination temperature range is 200-350℃. The heat source enters the front section of the pyrolysis reactor through the heat carrier inlet (1b-2). The heat carrier can be the cooled solid heat carrier and pyrolytic carbon output from the solid outlet (1b-5) at the tail end of the pyrolysis reactor (1b), with a temperature range of 400-500℃. Alternatively, the heat source can be the solid heat carrier from the gas-solid separation device (1d). The solid heat carrier separated by the gas-solid separation device (1d) has a temperature of 850℃-900℃. The pre-dechlorination temperature is ensured by controlling the amount of solid heat carrier. Waste plastics and dechlorinating agent enter through the waste plastic inlet (1b-1). HCl is removed in the front section of the pyrolysis reactor (1b) at a temperature of 200-350℃, and the dechlorinating agent reacts to generate chloride salts, completing the dechlorination process. The dechlorinating agent is an oxide, hydroxide, or carbonate of an alkali metal or alkaline earth metal.

[0046] The dechlorinated waste plastics undergo pyrolysis in the middle and later sections of the pyrolysis reactor (1b). The solid heat carrier separated by the gas-solid separation device (1d) is at a temperature of 850℃-900℃ and enters the middle and later sections of the pyrolysis reactor (1b) through the middle and later section heat carrier inlet (1b-3). The waste plastics and solid heat carriers are fully mixed, and the pyrolysis temperature range is 400-500℃. The direct contact of the heat carriers allows the waste plastics to be pyrolyzed quickly, which improves the oil yield. Furthermore, due to the properties of the solid heat carriers themselves, the sufficient friction prevents the equipment from coking during the pyrolysis process.

[0047] In this invention, the sealed feeding mechanism uniformly feeds waste plastic into the pyrolysis reactor (1b), and the pyrolysis reaction is maintained under slight negative pressure, oxygen-free or oxygen-deficient conditions throughout the process.

[0048] The slight negative pressure in the pyrolysis reactor (1b) is controlled by the frequency of the blower connected downstream of the pyrolysis gas outlet (1b-4);

[0049] At the waste plastic inlet (1b-1) of the pyrolysis reactor (1b), a material seal is formed by the accumulation of material in the feed pipe through the feeding mechanism, isolating it from air. At the heat carrier inlets (1b-2, 1b-3), the flow rate of the heat carrier entering the pyrolysis reactor (1b) is controlled by valves, ensuring a column of heat carrier material within the pipes at the heat carrier inlets (1b-2, 1b-3), thus achieving a material seal. At the heat carrier and pyrolysis carbon outlet (1b-5), the discharge rate is controlled by a mechanical structure, ensuring a certain column of pyrolysis carbon and solid heat carrier material within the pipes, isolating it from air. These measures ensure an oxygen-free or oxygen-deficient environment throughout the pyrolysis reactor (1b).

[0050] In this invention, the solid heat carrier is quartz sand, spherical particles with a particle size of 200-300 micrometers.

[0051] In this invention, Figure 3 A schematic diagram of the oil washing system is provided. The oil washing system (2a) consists of a two-stage dust removal system (cyclone dust collector and membrane dust collector) plus an oil washing tower. The oil washing tower (2a-3) uses the pyrolysis oil condensed from the bottom of the tower as the medium to spray and cool the heavy oil component of the pyrolysis oil gas. The top temperature of the tower is set to 350℃, and the oil washing tower collects the fractions above 350℃. Cyclone dust removal is implemented using a cyclone dust collector (2a-1), and membrane dust removal is implemented using a ceramic membrane dust collector or a metal membrane dust collector (2a-2).

[0052] In this invention, the staged indirect cooling system (2c) can be equipped with one or more indirect condensers to collect fractions with an initial boiling point (IBP) of -350°C.

[0053] The present invention proposes a method for the pyrolysis and oilification of waste plastics, comprising the following steps:

[0054] Waste plastic pyrolysis: Mixed waste plastics enter from outside the boundary area and first pass through a screening and crushing device (1a). During this process, the metals in the waste plastics are recycled. The remaining waste plastics do not need to be washed and sorted; they only need to be crushed to 60-80mm. Then, the crushed waste plastics and dechlorination agent are fed into the pyrolysis reactor (1b) through the feeding mechanism for pyrolysis. In the front section of the pyrolysis reactor (1b), the waste plastics are mixed with solid heat carriers and pyrolysis carbon from the tail of the pyrolysis reactor (1b) or solid heat carriers from the gas-solid separation device (1d) for low-temperature pre-dechlorination. In the middle section of the pyrolysis reactor (1b), the waste plastics are mixed with solid heat carriers from the gas-solid separation device (1d), and under the heating of the solid heat carriers, they are transformed into pyrolysis oil and gas and pyrolysis carbon. The cooled solid heat carriers carry heat... Carbon decomposition is output in two parts from the tail outlet of the pyrolysis reactor (1b). One part is returned to the front section of the pyrolysis reactor for pre-dechlorination of waste plastics; the other part enters the solid heat carrier furnace (1c), where the pyrolysis carbon is burned as fuel to heat the solid heat carrier. After the solid heat carrier is heated to 850-900℃, it is pneumatically conveyed to the top of the solid heat carrier furnace (1c) and enters the gas-solid separation device (1d). In the gas-solid separation device (1d), the solid heat carrier is separated into two streams, which enter the front and middle sections of the pyrolysis reactor (1b) respectively to complete the pre-dechlorination and heating of the waste plastics. The flue gas enters the waste heat recovery system (1e) from the gas-solid separation device (1d) to heat the medium in the waste heat recovery system (1e) to generate steam. Subsequently, the cooled flue gas enters the flue gas purification device (1f) for purification, and is discharged after meeting the standards.

[0055] The pyrolysis oil and gas produced by pyrolysis enters the pyrolysis oil separation and refining system for oiling. The pyrolysis oil and gas enters the oil washing system (2a) of the pyrolysis oil separation and refining system from the gas outlet of the pyrolysis reactor (1b). In this system, the pyrolysis oil and gas undergo dust removal and heavy oil removal. The separated heavy oil components enter the heavy oil storage tank (2b) and are then returned to the pyrolysis reactor (1b) for re-pyrolysis. After exiting the oil washing system (2a), the pyrolysis oil and gas enter the staged indirect cooling system (2c), where the light component distillate oil in the pyrolysis oil and gas is condensed. The pyrolysis gas (non-condensable gas) enters the solid heat carrier furnace (1c) for combustion as fuel. The distillate oil undergoes desulfurization, dechlorination, desiliconization, decolorization, and deodorization in the oil purification device (2d) before entering the distillate oil storage tank (2e), where it can be sold as a commodity.

[0056] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0057] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A waste plastic pyrolysis oiling system, characterized in that, This includes waste plastic pyrolysis systems and pyrolysis oil separation and refining systems; The waste plastic pyrolysis system includes: a screening and crushing device (1a), a pyrolysis reactor (1b), a solid heat carrier furnace (1c), a gas-solid separation device (1d), a waste heat recovery system (1e), and a flue gas purification device (1f). The material outlet of the screening and crushing device (1a) is connected to the material inlet of the pyrolysis reactor (1b), and the screened and crushed waste plastics are fed into the pyrolysis reactor (1b) together with the dechlorination agent for pyrolysis. The pyrolysis reactor (1b) is used to pre-dechlorinate and pyrolyze waste plastics, converting them into pyrolysis oil and gas and pyrolysis carbon. The gas outlet of the pyrolysis reactor (1b) is connected to the inlet of the oil washing system (2a) in the pyrolysis oil separation and refining system, so that the pyrolysis oil and gas enter the oil washing system (2a). The solid outlet of the pyrolysis reactor (1b) is connected to the inlet of the solid heat carrier furnace (1c), so that the heating solid heat carrier and the generated pyrolysis carbon enter the solid heat carrier furnace (1c). The solid heat carrier furnace (1c) uses pyrolysis carbon and pyrolysis gas separated by the staged indirect cooling system (2c) as fuel to heat the solid heat carrier. The outlet of the solid heat carrier furnace is connected to the inlet of the gas-solid separation device (1d) to transport the solid heat carrier to the gas-solid separation device (1d). The outlet of the gas-solid separation device (1d) is connected to the inlet of the pyrolysis reactor (1b) and the waste heat recovery system (1e). After separating the solid heat carrier, it is sent to the pyrolysis reactor (1b) to complete the pre-dechlorination of waste plastic and the pyrolysis of waste plastic. The flue gas is sent to the waste heat recovery system (1e). The outlet of the waste heat recovery system (1e) is connected to the inlet of the flue gas purification device (1f). The high-temperature flue gas is used to heat the medium to generate steam, and the cooled flue gas is sent into the flue gas purification device (1f) for purification before being discharged. The pyrolysis oil separation and refining system includes: an oil washing system (2a), a heavy oil storage tank (2b), a staged indirect cooling system (2c), an oil impurity removal device (2d), and a distillate oil storage tank (2e). The liquid outlet of the oil washing system (2a) is connected to the inlet of the heavy oil storage tank (2b), and the gas outlet is connected to the inlet of the staged indirect cooling system (2c). It is used to remove dust and heavy oil from pyrolysis oil and gas. The separated heavy oil components enter the heavy oil storage tank (2b), and the separated pyrolysis oil and gas enter the staged indirect cooling system (2c). The outlet of the heavy oil storage tank (2b) is connected to the inlet of the pyrolysis reactor (1b), so that the heavy oil is returned to the pyrolysis reactor (1b) for re-pyrolysis; The gas outlet of the staged indirect cooling system (2c) is connected to the inlet of the solid heat carrier furnace (1c), and the liquid outlet is connected to the inlet of the oil purification device (2d). The light component distillate oil in the pyrolysis oil gas is condensed, and the non-condensable pyrolysis gas is sent into the solid heat carrier furnace (1c) for combustion as fuel. The distillate oil is sent into the oil purification device (2d). The outlet of the oil purification device (2d) is connected to the distillate oil storage tank (2e). After desulfurization, dechlorination, removal of organosilicon, decolorization and deodorization of the distillate oil, it is sent into the distillate oil storage tank (2e). The pyrolysis reactor (1b) includes a first reaction section as the front section and a second reaction section as the middle and rear section. The first reaction section and the second reaction section are connected head to tail. The first reaction section completes the pre-dechlorination process of waste plastics and is equipped with a first conveying device, a waste plastic inlet (1b-1), and a front heat carrier inlet (1b-2). The second reaction section completes the pyrolysis process and is equipped with a second conveying device, a middle and rear heat carrier inlet (1b-3), a pyrolysis gas outlet (1b-4), and a solid outlet (1b-5). The first conveying device mixes the materials in the first reaction section and transports them to the second reaction section through a connecting pipeline. The second conveying device mixes the materials in the second reaction section and transports them from the head to the tail. Pyrolysis gas is output from the pyrolysis gas outlet (1b-4) of the pyrolysis reactor, and solid materials are output from the solid outlet (1b-5) of the pyrolysis reactor.

2. The waste plastic pyrolysis oilification system according to claim 1, characterized in that, The waste plastic inlet (1b-1) and the front heat carrier inlet (1b-2) are located at the front end of the first reaction section, and waste plastic, dechlorination agent and solid heat carrier are respectively input.

3. The waste plastic pyrolysis oilification system according to claim 1, characterized in that, The mid-to-rear section heat carrier inlet (1b-3) is located at the front end of the second reaction section, and a solid heat carrier is input; the pyrolysis gas outlet (1b-4) and the solid outlet (1b-5) are located at the rear end of the second reaction section.

4. The waste plastic pyrolysis oilification system according to claim 1, characterized in that, The first conveying device includes a motor and a material conveying shaft. The motor output shaft is connected to the material conveying shaft. The material conveying shaft is located in the first reaction section and includes a shaft body and a propeller blade fixed on the shaft body. The motor drives the material conveying shaft to rotate, and the propeller blade mixes and conveys the material.

5. The waste plastic pyrolysis oiling system according to claim 4, characterized in that, The length of the material conveying shaft is shorter than that of the propeller blades. The front end of the propeller blades is a shafted propeller blade, and the rear end is a shaftless propeller blade.

6. The waste plastic pyrolysis oilification system according to claim 1, characterized in that, The pre-dechlorination temperature range of the pyrolysis reactor (1b) is 200-350℃. The heat source is the cooled solid heat carrier and pyrolytic carbon output from the solid outlet (1b-5) at the tail of the pyrolysis reactor (1b), with a temperature of 400-500℃, and / or the solid heat carrier separated by the gas-solid separation device (1d), with a temperature of 850℃-900℃.

7. The waste plastic pyrolysis oilification system according to claim 2, characterized in that, The pyrolysis reactor (1b) has a pyrolysis temperature range of 400-500℃, and the heat source is a solid heat carrier separated by the gas-solid separation device (1d) with a temperature of 850℃-900℃.

8. The waste plastic pyrolysis oilification system according to claim 1, characterized in that, A blower is connected downstream of the pyrolysis gas outlet (1b-4) of the pyrolysis reactor (1b); The waste plastic inlet (1b-1) of the pyrolysis reactor (1b) is sealed by the accumulation of material in the feed pipe of the feeding mechanism to isolate air. The flow rate of the heat carrier entering the pyrolysis reactor (1b) is controlled by valves at the front heat carrier inlet (1b-2) and the rear heat carrier inlet (1b-3), so that there is a column of solid heat carrier in the pipe of the front heat carrier inlet (1b-2) and the rear heat carrier inlet (1b-3), thus implementing the solid heat carrier sealing. The discharge speed is controlled by the solid heat carrier and pyrolysis carbon outlet, so that the pyrolysis carbon and solid heat carrier form a column in the discharge pipe.

9. A process for the pyrolysis and oilification of waste plastics, characterized in that, The waste plastic pyrolysis oiling system according to any one of claims 1 to 8 is used for implementation, including: Waste plastics are fed into a screening and crushing device (1a) to recover metals and pulverize them. The crushed waste plastics and dechlorinating agent are then fed into a pyrolysis reactor (1b). In the front section of the pyrolysis reactor (1b), the waste plastics are mixed with solid heat carriers and pyrolysis carbon from the tail of the pyrolysis reactor (1b) or solid heat carriers from the gas-solid separation device (1d) for pre-dechlorination. In the middle section of the pyrolysis reactor (1b), the waste plastics are mixed with solid heat carriers from the gas-solid separation device (1d) and, under the heating of the solid heat carriers, are converted into pyrolysis oil and gas and pyrolysis carbon. The cooled solid heat carriers, carrying pyrolysis carbon, are output from the tail outlet of the pyrolysis reactor (1b) in two parts. One part is returned to the front section of the pyrolysis reactor to heat the waste plastics for pre-dechlorination. A portion of the waste plastic enters the solid heat carrier furnace (1c), where the pyrolysis carbon is burned as fuel to heat the solid heat carrier. After the solid heat carrier is heated to the set temperature, it is conveyed to the top of the solid heat carrier furnace (1c) and enters the gas-solid separation device (1d). In the gas-solid separation device (1d), the solid heat carrier is separated into two streams, which enter the front and middle sections of the pyrolysis reactor (1b) respectively to complete the pre-dechlorination and heating of the waste plastic. The flue gas enters the waste heat recovery system (1e) from the gas-solid separation device (1d) to heat the medium in the waste heat recovery system (1e) to generate steam. The cooled flue gas then enters the flue gas purification device (1f) to purify the flue gas. The flue gas is discharged after meeting the standards. The pyrolysis oil gas enters the oil washing system (2a) from the gas outlet of the pyrolysis reactor (1b). In the oil washing system (2a), the pyrolysis oil gas is dusted and heavy oil is removed. The separated heavy oil components enter the heavy oil storage tank (2b) and are returned to the pyrolysis reactor (1b) for pyrolysis again. The separated pyrolysis oil gas enters the staged indirect cooling system (2c), where the light component distillate oil in the pyrolysis oil gas is condensed. The non-condensable pyrolysis gas enters the solid heat carrier furnace (1c) as fuel for combustion. The distillate oil passes through the oil impurity removal device (2d) for desulfurization, dechlorination, desilicon removal, decolorization, and deodorization before entering the distillate oil storage tank (2e).

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