Waste plastic pyrolysis oil production equipment capable of cooperatively controlling pyrolysis temperature through composite heating

Abstract

The utility model discloses waste plastic pyrolysis oil-making equipment capable of cooperatively controlling pyrolysis temperature through composite heating, and aims to solve the problems of misalignment of thermal field regulation and low efficiency of energy circulation in the existing waste plastic pyrolysis oil-making technology. The equipment comprises a raw material bin, an extruding machine, a grid type feeder, a preheating bin and a rotary reactor penetrating through a plastic melting furnace, a pyrolyzing furnace and a gasification furnace, an electric heating shoveling plate, a spiral weir plate and a stirring paddle are arranged on the inner wall of the rotary reactor; a pushing mechanism is arranged at the bottom of the preheating bin to continuously convey preheated materials; the flue gas circulating system recovers and reuses flue gas waste heat of all the furnace bodies, organic non-condensable gas separated by the oil gas recovery device is supplied to the combustor, and an energy closed loop is formed. Through the synergistic effect of multi-stage composite heating, dynamic power supply and a spiral flow guide structure, the problems that traditional equipment is uneven in thermal field, high in energy consumption and poor in raw material adaptability are solved, and waste plastics are efficiently pyrolyzed to prepare oil.

Description

Technical Field

[0001] This utility model belongs to the field of waste plastic resource utilization technology, specifically relating to a waste plastic pyrolysis oil production equipment with composite heating and synergistic control of pyrolysis temperature, which is particularly suitable for efficient pyrolysis conversion of mixed waste plastics. Background Technology

[0002] Plastic products, with their advantages of being lightweight, corrosion-resistant, and easy to process, are widely used in national production and daily life. However, the surge in waste plastics has led to increasingly severe pollution problems caused by non-degradable materials. Thermochemical pyrolysis technology is an important way to utilize waste plastics (such as PE, PP, PET, etc.) as resources. It involves heating waste plastics to 300-500℃ in an oxygen-deficient environment to pyrolyze them into oil and gas, offering both environmental and economic benefits. However, existing mainstream processes such as externally heated rotary kiln pyrolysis and fluidized bed pyrolysis have significant drawbacks: externally heated rotary kilns have low thermal efficiency and high energy consumption; circulating fluidized bed pyrolysis produces oil and gas products with high dust content, resulting in high subsequent purification costs. Industrial practice shows that existing technologies suffer from inaccurate thermal field control, inefficient energy recycling, and insufficient equipment adaptability, leading to low-quality pyrolysis products, resource waste, and short operating cycles. The industry urgently needs to develop a new generation of pyrolysis technology to solve key issues such as precise temperature control, efficient energy recovery, and strong raw material adaptability, thereby promoting the upgrading of "white pollution" control to a resource-recycling-based industry. Utility Model Content

[0003] The purpose of this invention is to address the problems of inaccurate thermal field control, inefficient energy circulation, and insufficient equipment adaptability mentioned above by proposing a waste plastic pyrolysis oil production equipment with composite heating and synergistic control of pyrolysis temperature, so as to achieve precise temperature control, efficient energy recovery, and enhanced raw material adaptability.

[0004] To achieve the above objectives, this utility model provides a waste plastic pyrolysis oil production equipment with composite heating and synergistic control of pyrolysis temperature, comprising: a raw material silo, an extruder, a grid feeder, a preheating silo, a rotary reactor, a melting furnace, a pyrolysis furnace, and a gasification furnace;

[0005] The raw material silo outlet is connected to the extruder inlet and is equipped with a metering device for quantitative conveying of waste plastic raw materials. The extruder outlet is connected to the feeder inlet, where the extruder compresses loose waste plastic into blocks and fills them into the feeder's storage compartment. The feeder outlet is connected to the preheating silo inlet, where the feeder's storage compartment is fully filled before feeding material into the preheating silo. The preheating silo is equipped with a thermal radiation furnace at its upper part for preliminary heating of the block material. The top of the preheating silo shell is equipped with an oil and gas outlet connected to an oil and gas recovery device. The preheating silo outlet is connected to the rotary reactor inlet, which sequentially passes through the cavities of a melting furnace, a pyrolysis furnace, and a vaporization furnace. After the raw material is melted, cracked, and vaporized, oil and gas are generated and conveyed to the oil and gas recovery device through the oil and gas outlet at the top of the preheating silo shell. Electric heating plates are respectively installed on the inner wall of the rotary reactor located in the pyrolysis furnace and vaporization furnace cavity sections to provide auxiliary heat for the pyrolysis and vaporization sections of the rotary reactor.

[0006] Furthermore, the electric heating plates are multiple pieces, evenly distributed along the axial direction on the inner wall of the reactor. The ratio of the reactor's inner diameter to the height of the electric heating plates is 5:1 to 10:1, and the included angle between the extended lines of two adjacent electric heating plates is 15° to 30°. The surface temperature of the electric heating plates is maintained within the range of 300°C to 350°C by current control. An annular power supply slide rail is provided on the outer wall of the rotary reactor shell between the pyrolysis furnace and the gasification furnace. The power supply slide rail forms a sliding electrical contact with the electric heating plates to implement dynamic power supply.

[0007] Furthermore, a pushing mechanism is provided at the bottom of the preheating chamber. The pushing mechanism includes a material trough, a pushing rod, and a transmission mechanism for driving the pushing rod, which are connected in sequence. The pushing rod is driven by the transmission mechanism to make the material trough perform a reciprocating pushing action at the bottom of the preheating chamber, so as to transport the preheated material to the rotary reactor.

[0008] Furthermore, the inner wall of the rotary reactor located in the cavity section of the melting furnace is equipped with a stirring paddle, which generates directional thrust during rotation to continuously transport the molten material to the pyrolysis section.

[0009] Furthermore, the inner wall of the rotary reactor is provided with several spiral weir plates spaced axially, extending and distributed within the cavity sections of the pyrolysis furnace and the gasification furnace. The ratio of the reactor's inner diameter to the radial height of the spiral weir plates is in the range of 5:1 to 8:1, and the axial spacing between adjacent spiral weir plates is 2 to 3 times the reactor's inner diameter. The pitch of a single spiral weir plate is 0.5 to 0.3 times the reactor's inner diameter. The continuous spiral extension length of a single spiral weir plate is 7 / 6 to 7.5 / 6 turns (i.e., the weir plate circumference is 360+60° to 360°+90°). The spiral weir plates can extend the material residence time and enhance heat transfer.

[0010] Furthermore, it also includes: a flue gas fan, a flue gas heat exchanger, and a flue gas heater; the outlet of the flue gas heater is connected to the flue gas inlets at the bottom of the melting furnace, pyrolysis furnace, and gasification furnace via flue gas pipes; the flue gas outlets at the top of the melting furnace, pyrolysis furnace, and gasification furnace are connected to the inlet of the flue gas fan via flue gas pipes; the outlet of the flue gas fan is connected to the high-temperature side inlet of the flue gas heat exchanger and the circulating flue gas inlet of the flue gas heater, respectively, so that a portion of the flue gas is introduced into the flue gas heat exchanger for waste heat recovery, and another portion of the flue gas is returned to the flue gas heater for recycling; the high-temperature side outlet of the flue gas heat exchanger is connected to the chimney, its low-temperature side inlet is connected to the air supply pipeline, and its low-temperature side outlet is connected to the burner of the flue gas heater via a pipeline; the oil and gas outlet of the preheating chamber is connected to the oil and gas recovery device, and the organic non-condensable gas outlet of the oil and gas recovery device is connected to the burner of the thermal radiation furnace and the flue gas heater, respectively, to achieve efficient fuel utilization and reduce VOC emissions.

[0011] Furthermore, a semi-annular turbulence plate communicating with the flue gas inlet is provided above the flue gas inlet of the melting furnace, pyrolysis furnace and gasification furnace. The turbulence plate extends along the axial direction of the rotary reactor and covers its outer surface circumferentially. Gas injection holes are evenly distributed on the turbulence plate. An annular gap of 50mm to 100mm is formed between the inner wall of the turbulence plate and the outer wall of the rotary reactor to achieve turbulent enhanced heat transfer on the outer wall of the rotary reactor.

[0012] Furthermore, the thermal radiation furnace is equipped with a pyrolysis gas-air regenerative heat exchanger, which is filled with honeycomb ceramic regenerator; the regenerative heat exchanger is equipped with a pyrolysis gas-air reversing valve group, the reversing valve group has a reversing cycle of 60s~90s, and alternately switches the airflow direction to improve the heat storage efficiency.

[0013] Another objective of this utility model is to disclose a waste plastic pyrolysis oil extraction process that uses composite heating to synergistically control the pyrolysis temperature, comprising the following steps:

[0014] Step 1: Preheated air output from the low-temperature side of the flue gas heat exchanger is mixed with the first non-condensable pyrolysis gas from the oil and gas recovery device in a predetermined ratio and then fed into the burner of the flue gas heating furnace for combustion. The high-temperature flue gas generated by combustion is distributed to the flue gas inlets of the melting furnace, pyrolysis furnace, and gasification furnace. After being evenly distributed by the turbulence plate, it provides differentiated heating to the rotary reactor. The melting furnace section uses pure flue gas for heating, while the pyrolysis furnace section and the gasification furnace section use a combination of flue gas and electric heating for temperature control. The flue gas discharged from the melting furnace, pyrolysis furnace, and gasification furnace is pressurized by the flue gas fan and then enters the flue gas heating furnace as a circulating heating medium, and enters the high-temperature side of the flue gas heat exchanger to preheat the air on the low-temperature side. The second non-condensable pyrolysis gas from the oil and gas recovery device enters the thermal radiation furnace to provide radiant heating energy for the preheating chamber.

[0015] Step 2: Quantitatively measure the waste plastic using the weighing device in the raw material silo, and transport the waste plastic to the extruder according to the preset intermittent cycle;

[0016] Step 3: In the extruder, the loose waste plastic is compressed into dense blocks by hydraulic push rods. The formed waste plastic compressed blocks are then pushed to the storage compartment of the feeder.

[0017] Step 4: After the feeder has filled the storage compartment, start the rotary unloading mechanism. Control the blocks to fall into the preheating chamber in sequence through the slide valve. At the same time, the upper thermal radiation furnace preheats the falling blocks.

[0018] Step 5: The pushing mechanism at the bottom of the preheating chamber continuously pushes the preheated block to the rotary reactor. After each stroke, the pushing rod resets along the track, and the pushing frequency is synchronized with the unloading rate of the feeder.

[0019] Step 6: The waste plastic entering the rotary reactor is heated and melted in the melting section, cracked by heat in the pyrolysis section, and vaporized into oil and gas in the vaporization section. The oil and gas products generated in the rotary reactor are transported to the oil and gas recovery device through the oil and gas outlet of the preheating chamber for gas-liquid separation, and the separated non-condensable pyrolysis gas is returned to the thermal radiation furnace and the burner of the flue gas heating furnace.

[0020] Compared with the prior art, this utility model has the following advantages:

[0021] 1) Precise temperature control: The waste plastic pyrolysis temperature is controlled by a combination of heating furnace, electric heating plate, melting furnace, pyrolysis furnace and vaporization furnace. This achieves coordinated and precise control of the pyrolysis temperature, making the waste plastic pyrolysis reaction process mild and controllable, and improving the yield and quality of oil products.

[0022] 2) High-efficiency energy recovery: Through flue gas circulation and thermal radiation furnace heat storage and exchange unit, the waste heat of flue gas and non-condensable heat decomposition gas are effectively recovered and utilized to improve thermal efficiency and reduce energy consumption.

[0023] 3) Enhance raw material adaptability: Through the synergistic action of the feeding mechanism, stirring paddle and spiral weir plate, it adapts to the characteristics of raw materials with high impurity content and large differences in physical properties of mixed plastics, and extends the continuous operation cycle of the equipment. Attached Figure Description

[0024] Figure 1 Flowchart of waste plastic pyrolysis oil production equipment for combined heating and synergistic control of pyrolysis temperature;

[0025] Figure 2 This is a schematic diagram of the spiral weir plate arrangement inside the rotary reactor;

[0026] Figure 3 Right view of spiral weir plate AA inside the rotary reactor;

[0027] Figure 4 This is a schematic diagram of a turbulence plate.

[0028] 1-Raw material silo; 2-Extruder; 3-Format feeder; 4-Radiant furnace; 5-Preheating silo; 6-Rotary reactor; 7-Electric heating plate; 8-Flue gas fan; 9-Flue gas heat exchanger; 10-Flue gas heater; 11-Power supply slide rail; 12-Melting furnace; 13-Pyrolysis furnace; 14-Gasification furnace; 15-Turbulence plate; 16-Pushing mechanism; 17-Spiral weir plate. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] This embodiment discloses a waste plastic pyrolysis oil production equipment with composite heating and synergistic temperature control. The waste plastic pyrolysis oil production equipment of this embodiment has a waste plastic pyrolysis processing capacity of 20,000 tons / year. Figure 1-4 As shown, the waste plastic pyrolysis oil production equipment with composite heating and synergistic control of pyrolysis temperature includes a raw material silo, an extruder, a grid feeder, a preheating silo, a rotary reactor, a melting furnace, a pyrolysis furnace, and a gasification furnace.

[0031] The outlet of the raw material silo 1 is connected to the inlet of the extruder 2, and has a built-in metering device that feeds 50kg of material intermittently each time. The outlet of the extruder 2 is connected to the inlet of the grid feeder 3. The extruder 2 compresses the loose raw material into square plastic blocks and fills them into the storage compartments of the grid feeder 3. The outlet of the grid feeder 3 is connected to the inlet of the preheating silo 5. After the storage compartments are completely filled, the feeder 3 supplies material to the preheating silo 5. The upper part of the preheating silo 5 is equipped with a thermal radiation furnace 4, which has a heat exchanger filled with honeycomb ceramic heat storage body and is equipped with a pyrolysis gas-air reversing valve group with a reversing cycle of 90s and a thermal radiation wall surface temperature of 1000℃. This allows for the radiant preheating of the waste plastic in the preheating silo 5.

[0032] The outlet of the preheating chamber 5 is connected to the inlet of the rotary reactor 6. A pushing mechanism 16 is provided at its bottom, including a material trough, a pushing rod, and a transmission mechanism that drives the pushing rod in sequence. The preheated material is transported to the rotary reactor 6 through reciprocating pushing action. The pushing rod resets along the track after each stroke. The pushing frequency is synchronized with the unloading rate of the feeder 3. The filling interval is 30 minutes.

[0033] The rotary reactor 6 passes through the cavities of the melting furnace 12, the pyrolysis furnace 13 and the vaporization furnace 14 in sequence, and the inner diameter of the rotary reactor 6 is 2m. The internal structure of the rotary reactor 6 includes electrically heated lifting plates 7 evenly distributed along the axial direction of the pyrolysis and vaporization sections of the rotary reactor 6, with a radial height of 300 mm and an angle of 30° between the extension lines of two adjacent electrically heated lifting plates 7. Power is dynamically supplied via a ring-shaped power supply slide rail 11 located on the outer wall of the rotary reactor 6 shell between the pyrolysis furnace 13 and the vaporization furnace 14, and the surface temperature is controlled between 300°C and 350°C. The inner wall of the melting section of the rotary reactor 6 is equipped with a stirring paddle, which generates directional thrust during rotation to continuously transport the molten material to the pyrolysis section. Several spiral weir plates 17 are spaced axially along the inner wall of the pyrolysis and vaporization sections of the rotary reactor 6, with a radial height of 300 mm, an axial distance of 6 m between adjacent spiral weir plates 17, a pitch of 600 mm for a single spiral weir plate 17, and a continuous spiral extension length of 7 / 6 turns for a single spiral weir plate 17, used to extend the material residence time and enhance heat transfer.

[0034] The melting furnace 12, pyrolysis furnace 13, and vaporization furnace 14 are heated by a flue gas circulation system. The flue gas heater 10 generates high-temperature flue gas at 800°C, which is transported through pipelines to the flue gas inlets at the bottom of the melting furnace 12, pyrolysis furnace 13, and vaporization furnace 14. A semi-annular turbulence plate 15 is installed above the flue gas inlet of each furnace, covering the outer wall of the rotary reactor 6. The inner wall of the turbulence plate forms an 80mm annular gap with the outer wall of the reactor. Gas injection holes are evenly opened on the plate to enhance turbulent heat transfer. The flue gas outlet at the top of each furnace is connected to a flue gas fan 8. After passing through the flue gas fan 8, the flue gas is divided into two paths: one path enters the flue gas heat exchanger 9, which preheats the air to 400°C and then supplies it to the burner, where the flue gas is cooled to 150°C before being discharged; the other path returns to the flue gas heater 10 for recycling.

[0035] The melting furnace 12 heats the furnace cavity to 650°C using high-temperature flue gas, heating the outer wall of the rotary reactor 6 that runs through it. The internal melting section temperature is stabilized at 200°C. Waste plastic blocks melt into a viscous flow state within the melting section of the rotary reactor 6. The stirring paddle generates directional thrust as it rotates, continuously conveying the molten material to the pyrolysis section. The pyrolysis furnace 13 heats the furnace cavity to 600°C using high-temperature flue gas. The electric heating plates 7 are dynamically powered via an annular power supply rail 11, working in conjunction with the flue gas heating to stabilize the temperature within the pyrolysis section of the rotary reactor 6 at 200-300°C. The molten material undergoes a cracking reaction in the pyrolysis section. The vaporization furnace 14 heats the furnace cavity to 600°C using high-temperature flue gas. An external heat source is provided for the vaporization section of the rotary reactor 6. The electric heating plate 7 is dynamically powered through the annular power supply slide rail 11. It works in conjunction with the flue gas heating to stabilize the temperature of the vaporization section of the rotary reactor 6 at 300~450℃. After the pyrolysis products are vaporized, product oil and gas are generated. The product oil and gas is transported to the oil and gas recovery device through the oil and gas outlet at the top of the preheating chamber 5 to obtain pyrolysis oil products. The separated organic non-condensable gas is fed back to the thermal radiation furnace 4 for heat exchange and back to the burner of the flue gas heating furnace 10. It is mixed with the 400℃ air preheated by the flue gas heat exchanger 9 and burned to generate 800℃ high-temperature flue gas for recycling in the melting furnace 12, pyrolysis furnace 13 and vaporization furnace 14, while reducing VOC emissions.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A waste plastic pyrolysis oil production device for composite heating and synergistic control of pyrolysis temperature, characterized in that, include: The raw material silo (1), extruder (2), feeder (3), preheating silo (5), rotary reactor (6), melting furnace (12), pyrolysis furnace (13) and gasification furnace (14); the outlet of the raw material silo (1) is connected to the inlet of the extruder (2); The outlet of the extruder (2) is connected to the inlet of the feeder (3); The outlet of the feeder (3) is connected to the inlet of the preheating chamber (5). The upper part of the preheating chamber (5) is equipped with a thermal radiation furnace (4), and the top of the shell of the preheating chamber (5) is equipped with an oil and gas outlet. The outlet of the preheating chamber (5) is connected to the inlet of the rotary reactor (6), which passes through the chambers of the melting furnace (12), the pyrolysis furnace (13) and the vaporization furnace (14) in sequence. Among them, electric heating plates (7) are respectively provided on the inner wall of the rotary reactor (6) located in the cavity section of the pyrolysis furnace (13) and the gasification furnace (14).

2. The waste plastic pyrolysis oil production plant with composite heating synergic control pyrolysis temperature according to claim 1, characterized in that, The electric heating plate (7) consists of multiple pieces, which are evenly distributed along the axial direction on the inner wall of the rotary reactor (6). The included angle between the extension lines of two adjacent electric heating plates (7) is 15° to 30°. The outer wall of the rotary reactor (6) between the pyrolysis furnace (13) and the gasification furnace (14) is provided with an annular power supply slide rail (11), and the power supply slide rail (11) forms a sliding electrical contact with the electric heating plate (7).

3. The waste plastic pyrolysis oil plant for composite heating and synergic control of pyrolysis temperature according to claim 1, characterized in that, The preheating chamber (5) is provided with a pushing mechanism (16) at the bottom. The pushing mechanism (16) includes a material trough, a pushing rod, and a transmission mechanism for driving the pushing rod, which are fixedly connected in sequence.

4. The waste plastic pyrolysis oil production equipment with composite heating and synergistic control of pyrolysis temperature according to claim 1, characterized in that, A stirring paddle is provided on the inner wall of the rotary reactor (6) located in the cavity section of the melting furnace (12).

5. The plant for the pyrolysis of waste plastics to oil with composite heating and synergic control of the pyrolysis temperature according to claim 1, characterized in that, The inner wall of the rotary reactor (6) is provided with a number of spiral weir plates (17) spaced along the axial direction. The spiral weir plates (17) extend and are distributed in the cavity sections of the pyrolysis furnace (13) and the gasification furnace (14).

6. The plant for the pyrolysis of waste plastics to oil at a complex heating and synergic control of the pyrolysis temperature according to claim 1, characterized by the fact that, Also includes: Flue gas fan (8), flue gas heat exchanger (9) and flue gas heater (10); The outlet of the flue gas heating furnace (10) is connected to the flue gas inlets at the bottom of the melting furnace (12), the pyrolysis furnace (13) and the vaporization furnace (14) respectively through flue gas pipes; The flue gas outlets at the top of the melting furnace (12), pyrolysis furnace (13) and vaporization furnace (14) are connected to the inlet of the flue gas fan (8) through flue gas pipes; The outlet of the flue gas fan (8) is connected to the high-temperature side inlet of the flue gas heat exchanger (9) and the circulating flue gas inlet of the flue gas heater (10), respectively. The high-temperature side outlet of the flue gas heat exchanger (9) is connected to the chimney, its low-temperature side inlet is connected to the air supply pipeline, and its low-temperature side outlet is connected to the burner of the flue gas heater (10) through a pipeline. The oil and gas outlet of the preheating chamber (5) is connected to the oil and gas recovery device, and the organic non-condensable gas outlet of the oil and gas recovery device is connected to the burners of the thermal radiation furnace (4) and the flue gas heating furnace (10).

7. The waste plastic pyrolysis oil production plant with composite heating synergic control pyrolysis temperature according to claim 6, characterized in that, The melting furnace (12), pyrolysis furnace (13) and gasification furnace (14) are all equipped with a semi-annular turbulence plate (15) above the flue gas inlet, which is connected to the flue gas inlet. The turbulence plate (15) extends along the axial direction of the rotary reactor (6) and covers its outer surface circumferentially. Gas injection holes are evenly distributed on the turbulence plate (15). An annular gap is formed between the inner wall of the turbulence plate (15) and the outer wall of the rotary reactor (6).

8. The waste plastic pyrolysis oil production plant with composite heating synergic control pyrolysis temperature according to claim 7, characterized in that, The thermal radiation furnace (4) is equipped with a pyrolysis gas-air heat storage heat exchanger, which is filled with honeycomb ceramic heat storage body; the heat storage heat exchanger is equipped with a pyrolysis gas-air reversing valve group.

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