Step-by-step waste plastic pyrolysis oil production system integrating drying and liquefying dehalogenation

Abstract

The utility model belongs to the technical field of organic solid waste recycling treatment, and mainly relates to a step-by-step waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation, which comprises a pretreatment device connected with a drying device; the drying device is connected with a liquefaction dehalogenation device, the liquefaction dehalogenation device is connected with a pyrolysis device, the pyrolysis device is connected with an oil-gas separation device, the oil-gas separation device is connected with a hot blast stove, the hot blast stove is connected with the pyrolysis device, the pyrolysis device is connected with the liquefaction dehalogenation device, and the liquefaction dehalogenation device is connected with the drying device. And hot flue gas generated in the hot blast stove sequentially enters the pyrolysis device, the liquefaction dehalogenation device and the drying device to provide heat for pyrolysis, liquefaction and drying of the waste plastics. In the whole pyrolysis process, energy is self-balanced, no extra fuel needs to be added, a step-by-step treatment mode is adopted, heat energy gradient utilization and distribution of the hot flue gas are reasonable, and the heat energy utilization efficiency of the hot flue gas in the whole pyrolysis process is high.

Description

Technical Field

[0001] The utility model belongs to the technical field of organic solid waste resource disposal, and mainly relates to a step-by-step waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation. Background Art

[0002] The production and use of plastics have brought great convenience to human life. However, a large amount of waste plastics are directly discarded without effective recycling, which also causes serious environmental problems, such as white pollution and microplastic pollution.

[0003] The pyrolysis reaction of waste plastics is an endothermic reaction. Although the heat energy utilization process of the pyrolysis gas and pyrolysis oil produced by pyrolysis can meet the heat required for the pyrolysis of waste plastics and achieve the energy self-balance of the pyrolysis process, due to the limitation of the pyrolysis atmosphere and the influence of the moisture content, the pyrolysis reaction often adopts an indirect heating method, which has low heat transfer efficiency and high energy consumption. At the same time, the halogens in waste plastics are usually discharged in the form of hydrogen halide during pyrolysis, and their acidity is likely to cause equipment corrosion and also has a certain impact on the quality of pyrolysis oil. Therefore, how to solve the dehalogenation and energy consumption reduction in the pyrolysis process of waste plastics has become a difficult problem in the industry.

[0004] The patent application document with the publication number CN115427538A discloses a method and system for liquefying and dehalogenating waste plastics. The waste plastics in this system sequentially pass through a pretreatment process, a liquefaction system, a pyrolysis membrane reactor, a solid separator, and a gas separation unit to obtain pyrolysis gas and pyrolysis oil.

[0005] The energy generated by the liquefaction system in this system has not been effectively recycled, resulting in energy waste and being unfavorable for solving the problem of high energy consumption. Summary of the Utility Model

[0006] The utility model provides a step-by-step waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation to solve the problem that the energy in the prior art has not been effectively recycled.

[0007] To solve the above problems, the utility model adopts the following technical solutions:

[0008] A step-by-step waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation includes a pretreatment device for crushing waste plastics and removing iron in the waste plastics, and the pretreatment device is connected with a drying device for drying waste plastics;

[0009] The drying device is connected with a liquefaction dehalogenation device, and the liquefaction dehalogenation device is connected with a pyrolysis device. The drying device is used to dry the moisture in the waste plastics and convey the dried waste plastics into the liquefaction dehalogenation device. The liquefaction dehalogenation device is used to heat and melt the dried waste plastics into liquefied plastics and convey the liquefied plastics into the pyrolysis device;

[0010] The pyrolysis device is connected to an oil-gas separation device, and the oil-gas separation device is connected to a hot blast stove. The pyrolysis device is used to heat and decompose liquefied plastics into pyrolysis oil-gas and carbon slag, and convey the pyrolysis oil-gas into the oil-gas separation device. The oil-gas separation device is used to separate the pyrolysis oil-gas into liquid pyrolysis oil and non-condensable pyrolysis gas, and convey the non-condensable pyrolysis gas into the hot blast stove. The hot blast stove is used to burn out the non-condensable pyrolysis gas to obtain hot flue gas;

[0011] The hot blast stove is connected to the pyrolysis device so that the hot flue gas enters the pyrolysis device to provide heat for the pyrolysis of liquefied plastics. The pyrolysis device is connected to a liquefaction and dehalogenation device so that the hot flue gas utilized in the pyrolysis device enters the liquefaction and dehalogenation device to provide heat for the melting of waste plastics. The liquefaction and dehalogenation device is connected to a drying device so that the hot flue gas utilized in the liquefaction and dehalogenation device enters the drying device to provide heat for the drying of waste plastics.

[0012] It has the following beneficial effects: The entire pyrolysis process has energy self-balance, without the need to additionally increase fuel. Moreover, a step-by-step disposal method is adopted, and the cascade utilization of the heat energy of the hot flue gas is reasonably distributed, and the heat energy utilization efficiency of the hot flue gas in the entire pyrolysis process is high.

[0013] Further, a dust removal device is connected between the pyrolysis device and the oil-gas separation device. The dust removal device is used to remove the carbon powder contained in the pyrolysis oil-gas so that the pyrolysis oil-gas after dust removal enters the oil-gas separation device.

[0014] Further, a deacidification device is installed between the liquefaction and dehalogenation device and the hot blast stove so that the hydrogen halide and pyrolysis gas generated by the liquefaction and dehalogenation device due to the melting of waste plastics enter the deacidification device. The deacidification device is used to remove hydrogen halide so that the pyrolysis gas after deacidification enters the hot blast stove to be burned out to obtain hot flue gas.

[0015] It has the following beneficial effects: Dispose of the waste plastics by dehalogenation, reduce the corrosion of equipment by acidic gases such as hydrogen halide during the pyrolysis process, and improve the quality of pyrolysis oil.

[0016] Further, the drying device is connected to a flue gas purification device, and the flue gas purification device is used to purify the hot flue gas and moisture discharged from the drying device.

[0017] Further, the inlet temperature of the hot flue gas of the liquefaction and dehalogenation device is 300 - 400 °C, the temperature for heating waste plastics in the liquefaction and dehalogenation device is 250 - 350 °C, and the residence time of the waste plastics in the liquefaction and dehalogenation device is 30 - 60 min.

[0018] Further, the liquefaction and dehalogenation device is one of a liquefaction kettle, a rotary kiln, and a liquefaction screw reactor.

[0019] Further, the pyrolysis device is one of a pyrolysis kettle, a rotary kiln, a tunnel kiln, a pyrolysis screw reactor, and a tubular reactor.

[0020] Further, the oil-gas separation device is a separation device with two or more stages. The oil-gas separation device is a shell-and-tube heat exchanger or a plate heat exchanger. The oil-gas separation device cools the pyrolysis oil-gas in an indirect air-cooling or water-cooling manner to separate out liquid pyrolysis oil and non-condensable pyrolysis gas.

[0021] Further, the dust removal device is one of a cyclone dust collector, a high-temperature ceramic dust collector, and a high-temperature cermet dust collector.

[0022] Further, an alkaline substance for absorbing hydrogen halide is placed in the deacidification device, and the alkaline substance is one or a mixture of more of CaO, CaCO3, NaOH, and Ca(OH)2.

[0023] It has the following beneficial effects: using an alkaline substance to absorb hydrogen halide, reducing the corrosion of equipment by acidic gases such as hydrogen halide during pyrolysis, and improving the quality of pyrolysis oil. Description of the Drawings

[0024] By reading the following detailed description with reference to the drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present utility model will become easily understandable. In the drawings, several embodiments of the present utility model are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0025] Figure 1 It is a block diagram of the present utility model.

[0026] Description of the Reference Numerals in the Drawings

[0027] 1. Waste plastic; 2. Pretreatment device; 3. Drying device; 4. Liquefaction and dehalogenation device; 5. Pyrolysis device; 6. Carbon residue; 7. Oil-gas separation device; 8. Hot blast stove; 9. Dust removal device; 10. Deacidification device; 11. Flue gas purification device; 12. Pyrolysis oil; 13. Hot flue gas. Detailed Embodiments

[0028] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Those skilled in the art should know that the following described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present utility model.

[0029] The following specifically introduces various non-limiting implementation manners of the present utility model. The number of any element in the drawings is for illustration rather than limitation, and any naming is only for distinction without any limiting meaning. It should be noted that, without conflict, the embodiments and features in the embodiments of the present utility model can be combined with each other.

[0030] As Figure 1 shown, a step-by-step waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation includes a pretreatment device 2, a drying device 3, a liquefaction dehalogenation device 4, and a pyrolysis device 5 connected in sequence.

[0031] Waste plastics 1 enter the pretreatment device 2, are crushed to form crushed plastics with a size of less than 100 mm, and enter the drying device 3 after iron removal. The drying device 3 is of direct heating form. The waste plastics 1 directly contact and exchange heat with the hot flue gas 13 in the drying device 3. The dried moisture is discharged from the drying device 3 together with the hot flue gas 13 and enters the flue gas purification device 11. The dried waste plastics 1 are discharged from the drying device 3 and enter the liquefaction dehalogenation device 4. The waste plastics 1 stay in the drying device 3 for 15 - 60 min, and the drying device 3 uses hot flue gas 13 with a temperature below 250 °C to dry the waste plastics 1.

[0032] The dried waste plastics 1 are heated and melted by the hot flue gas 13 in the liquefaction dehalogenation device 4 to form paste-like liquefied plastics. The liquefied plastics are discharged from the liquefaction dehalogenation device 4 and enter the pyrolysis device 5. The liquefaction dehalogenation device 4 in this embodiment is a liquefaction kettle. In other embodiments, the liquefaction dehalogenation device 4 can be a rotary kiln or a liquefaction screw reactor. In the liquefaction dehalogenation device 4, the waste plastics 1 are heated to 250 - 350 °C by the hot flue gas 13, and the waste plastics 1 stay in the liquefaction dehalogenation device 4 for 30 - 60 min. During the liquefaction process, the halogens in the waste plastics 1 are mainly discharged in the form of hydrogen halide. At the same time, a small part of the waste plastics 1 pyrolyze to generate pyrolysis gas. The pyrolysis gas with hydrogen halide enters the deacidification device 10. The deacidification device 10 adopts a dry deacidification form, absorbs acidic gases by adding alkaline substances, and the pyrolysis gas after deacidification enters the hot blast stove 8 to burn out and form hot flue gas 13. The alkaline substance in this embodiment is limestone. In other embodiments, the alkaline substance can be one or a mixture of CaO or CaCO3 or NaOH or Ca(OH)2.

[0033] The liquefied plastic is heated by the hot flue gas 13 in the pyrolysis device 5. The pyrolysis device 5 in this embodiment is a pyrolysis kettle. In other embodiments, the pyrolysis device 5 can be a rotary kiln, a tunnel kiln, a pyrolysis screw reactor, or a tubular reactor. The liquefied plastic is heated by the hot flue gas 13 in the pyrolysis device 5 to 450 - 550 °C and stays for 15 - 60 min, and decomposes into pyrolysis oil gas and carbon slag 6 in an anaerobic or anoxic environment. The carbon slag 6 is discharged from the slag discharge port of the pyrolysis device 5, and the pyrolysis oil gas enters the dust removal device 9 for dust removal. The dust removal device 9 in this embodiment is a high-temperature-resistant device, and the dust removal device 9 in this embodiment is a cyclone dust collector. In other embodiments, the dust removal device 9 can be a high-temperature ceramic dust collector or a high-temperature cermet dust collector. The carbon powder separated by the dust removal device 9 is incorporated into the carbon slag 6, and the pyrolysis oil gas after dust removal enters the oil-gas separation device 7. The oil-gas separation device 7 is a separation device with two or more stages. The separation method of the oil-gas separation device 7 in this embodiment adopts a shell-and-tube heat exchanger, and the pyrolysis oil gas is cooled by an indirect air-cooling form to separate out the liquid pyrolysis oil 12 for collection as fuel, and the remaining non-condensable pyrolysis gas enters the hot blast stove 8 to burn out, generating hot flue gas 13 for discharge. In other embodiments, the oil-gas separation device 7 can be a plate heat exchanger. In other embodiments, the oil-gas separation device 7 can cool the pyrolysis oil gas by a water-cooling form.

[0034] The deacidified pyrolysis gas from the outlet of the deacidification device 10 and the non-condensable pyrolysis gas from the pyrolysis gas outlet of the oil-gas separation device 7 enter the hot blast stove 8 to burn out, generating hot flue gas 13 that enters the pyrolysis device 5. In this embodiment, the hot flue gas 13 generated by the hot blast stove 8 can provide sufficient heat and temperature for the pyrolysis of the liquefied plastic, sufficient for the thermal decomposition of the liquefied plastic. In the pyrolysis device 5, the liquefied plastic is heated by the hot flue gas 13 to 450 - 550 °C, thereby undergoing pyrolysis. The hot flue gas 13 after heat exchange is discharged from the flue gas outlet of the pyrolysis device 5 and enters the liquefaction and dehalogenation device 4. The temperature at the flue gas inlet of the liquefaction and dehalogenation device 4 should be controlled at 300 - 400 °C, which can provide sufficient heat and temperature for the liquefaction and dehalogenation of the waste plastic 1, sufficient for the liquefaction and dehalogenation of the waste plastic 1. In the liquefaction and dehalogenation device 4, the waste plastic 1 is heated by the hot flue gas 13 to 250 - 350 °C. The hot flue gas 13 after heat exchange is discharged from the flue gas outlet of the liquefaction and dehalogenation device 4 and enters the drying device 3 at the flue gas inlet. The temperature of the hot flue gas 13 at the inlet of the drying device 3 should be controlled below 250 °C, which can provide sufficient heat and temperature for the drying of the waste plastic 1. In the drying device 3, the waste plastic 1 is dried in an environment where it is heated by the hot flue gas 13 below 250 °C. The drying temperature of the waste plastic 1 cannot be too high, otherwise the waste plastic 1 will be liquefied in advance. The hot flue gas 13 after heat exchange together with the drying moisture of the waste plastic 1 enters the flue gas purification device 11 and is discharged up to standard after purification. In this embodiment, through the above method, the cascade utilization of the thermal energy of the hot flue gas 13 is reasonably distributed.

[0035] In this embodiment, a step-by-step disposal method is adopted for waste plastic 1: first, waste plastic 1 is dried at a relatively low temperature to reduce the energy consumption during the drying process; at an appropriate temperature, waste plastic 1 is subjected to liquefaction and dehalogenation, and the volume of waste plastic 1 is significantly reduced, reducing the size and manufacturing cost of the subsequent pyrolysis device 5.

[0036] In this embodiment, waste plastic 1 is subjected to dehalogenation treatment to reduce the corrosion of equipment by acidic gases such as hydrogen halide during the pyrolysis process and improve the quality of pyrolysis oil 12.

[0037] This embodiment realizes the recovery of high-quality pyrolysis oil 12 products, which can be used as fuel oil to achieve waste-to-energy conversion.

[0038] In this embodiment, the entire pyrolysis process is energy self-balanced, without the need to additionally increase fuel. Moreover, with the step-by-step disposal method, the cascade utilization distribution of the thermal energy of hot flue gas 13 is reasonable, and the thermal energy utilization efficiency of hot flue gas 13 in the entire pyrolysis process is high.

Claims

1. A step-by-step waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation, comprising a pretreatment device for crushing waste plastics and removing iron in the waste plastics, characterized in that, The pre-treatment device is connected to a drying device for drying waste plastics; The drying device is connected to a liquefaction and dehalogenation device, and the liquefaction and dehalogenation device is connected to a pyrolysis device. The drying device is used to dry the moisture in the waste plastics and convey the dried waste plastics into the liquefaction and dehalogenation device. The liquefaction and dehalogenation device is used to heat and melt the dried waste plastics into liquefied plastics and convey the liquefied plastics into the pyrolysis device; The pyrolysis device is connected to an oil-gas separation device, and the oil-gas separation device is connected to a hot blast stove. The pyrolysis device is used to heat and decompose the liquefied plastics into pyrolysis oil-gas and carbon slag and convey the pyrolysis oil-gas into the oil-gas separation device. The oil-gas separation device is used to separate the pyrolysis oil-gas into liquid pyrolysis oil and non-condensable pyrolysis gas and convey the non-condensable pyrolysis gas into the hot blast stove. The hot blast stove is used to burn the non-condensable pyrolysis gas to obtain hot flue gas; The hot blast stove is connected to the pyrolysis device so that the hot flue gas enters the pyrolysis device to provide heat for the pyrolysis of the liquefied plastics. The pyrolysis device is connected to the liquefaction and dehalogenation device so that the hot flue gas utilized in the pyrolysis device enters the liquefaction and dehalogenation device to provide heat for the melting of the waste plastics. The liquefaction and dehalogenation device is connected to the drying device so that the hot flue gas utilized in the liquefaction and dehalogenation device enters the drying device to provide heat for the drying of the waste plastics.

2. The stepwise waste plastic pyrolysis oil production system for drying and liquefaction dehalogenation according to claim 1, characterized in that, A dust removal device is connected between the pyrolysis device and the oil-gas separation device. The dust removal device is used to remove the carbon powder contained in the pyrolysis oil-gas so that the pyrolysis oil-gas after dust removal enters the oil-gas separation device.

3. The stepwise waste plastic pyrolysis oil production system for drying and liquefaction dehalogenation according to claim 1, characterized in that A deacidification device is installed between the liquefaction and dehalogenation device and the hot blast stove so that the hydrogen halide and pyrolysis gas generated by the liquefaction and dehalogenation device due to the melting of the waste plastics enter the deacidification device. The deacidification device is used to remove the hydrogen halide so that the pyrolysis gas after deacidification enters the hot blast stove to be burned to obtain hot flue gas.

4. A stepwise waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation, as claimed in claim 1, wherein The drying device is connected to a flue gas purification device. The flue gas purification device is used to purify the hot flue gas and moisture discharged from the drying device.

5. A stepwise waste plastic pyrolysis oil production system for drying and liquefaction dehalogenation according to claim 1, characterized in that, The inlet temperature of the hot flue gas of the liquefaction and dehalogenation device is 300 - 400 °C, the temperature for heating the waste plastics in the liquefaction and dehalogenation device is 250 - 350 °C, and the residence time of the waste plastics in the liquefaction and dehalogenation device is 30 - 60 min.

6. A step-by-step waste plastic pyrolysis oil production system for drying and liquefaction dehalogenation according to claim 1, characterized in that, The liquefaction and dehalogenation device is one of a liquefaction kettle, a rotary kiln, and a liquefaction screw reactor.

7. A step-by-step waste plastic pyrolysis oil production system integrating drying and liquefaction dehalogenation, according to claim 1, characterized in that, The pyrolysis device is one of a pyrolysis kettle, a rotary kiln, a tunnel kiln, a pyrolysis screw reactor, and a tubular reactor.

8. A step-by-step waste plastic pyrolysis oil production system for drying and liquefying and dehalogenating, according to claim 1, characterized in that, The oil-gas separation device is a separation device with two or more stages. The oil-gas separation device is a shell-and-tube heat exchanger or a plate heat exchanger. The oil-gas separation device cools the pyrolysis oil-gas in an indirect air-cooled or water-cooled form to separate out liquid pyrolysis oil and non-condensable pyrolysis gas.

9. A step-by-step waste plastic pyrolysis oil production system for drying and liquefaction dehalogenation according to claim 2, characterized in that, The dust removal device is one of a cyclone dust collector, a high-temperature ceramic dust collector, and a high-temperature metal ceramic dust collector.

10. A step-by-step waste plastic pyrolysis oil production system for drying and liquefaction dehalogenation according to claim 3, characterized in that, An alkaline substance for absorbing hydrogen halide is placed in the deacidification device, and the alkaline substance is one or a mixture of more of CaO, CaCO3, NaOH, and Ca(OH)2.

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