System and method for preparing limonene based on pyrolysis of waste tires after swelling pretreatment

Abstract

The invention discloses a system and method for preparing limonene based on pyrolysis of waste tires after swelling pretreatment, a waste tire outlet of a stripping device is communicated with an inlet of a crushing device, an outlet of the crushing device is communicated with an inlet of a swelling device, an outlet of the swelling device is communicated with an inlet of a pyrolysis device through a feeding device, and an outlet of the pyrolysis device is communicated with an outlet of a stripping device. A tar outlet of the pyrolysis device is communicated with an inlet of the tar collecting device, a gas outlet of the pyrolysis device is communicated with an inlet of the condensing device, a gas outlet of the condensing device is communicated with an inlet of the gas collecting device, and a pyrolysis oil outlet of the condensing device is communicated with an inlet of the separating device. A limonene outlet of the separation device communicates with an inlet of the limonene collecting device, and a pyrolytic oil outlet of the separation device communicates with the oil collecting device, the system and the method can be used for preparing limonene based on pyrolysis of the waste tires after swelling pretreatment, high-value recycling of the waste tires is achieved, and the pyrolysis economical efficiency of the waste tires is improved.

Description

Technical Field

[0001] The invention belongs to the field of recycling waste tires and preparing high-value compounds, and relates to a system and method for preparing limonene by pyrolyzing waste tires after swelling pretreatment. Background Art

[0002] With the rapid development of the transportation industry, the demand for tires is increasing day by day. Correspondingly, the speed of tire replacement has accelerated, resulting in a sharp increase in the number of discarded tires. The degradation process of waste tires in the natural environment is very slow. If waste tires are discarded at will or handled improperly, it will have a serious impact on the environment. Not only will it occupy land resources, but it may also release harmful chemicals, pollute soil and water sources, and pose a threat to the ecological balance. Pyrolysis is one of the key technologies for high-value treatment of waste tires, and it has also been encouraged and supported by the country. Waste tires can produce high-value pyrolysis oil through pyrolysis, which improves the economic value of waste tire pyrolysis oil. However, there are still shortcomings in the preparation of high-value pyrolysis oil by pyrolysis of waste tires: the high-value degree of waste tire pyrolysis oil is not enough. As a high-value chemical, limonene can be generated during the pyrolysis of waste tires. However, under ordinary pyrolysis methods, limonene is very easy to undergo secondary reaction decomposition, resulting in a decrease in the quality of pyrolysis oil. If the pyrolysis process can be regulated to promote the generation of limonene, the high-value level of waste tire pyrolysis oil will be significantly improved. As a new type of waste tire pyrolysis pretreatment, the swelling pretreatment method can significantly change the physical properties of waste tires, especially the size of their internal pores, reduce the residence time of volatiles from waste tire pyrolysis, and promote the generation of limonene. Therefore, it is urgent to develop a system for preparing limonene from waste tires by pyrolysis after swelling pretreatment. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a system and method for preparing limonene based on pyrolysis of waste tires after swelling pretreatment. The system and method can prepare limonene based on pyrolysis of waste tires after swelling pretreatment, realize high-value recycling of waste tires, and improve the economic effect of waste tire pyrolysis.

[0004] To achieve the above-mentioned purpose, the present invention discloses a system for preparing limonene based on pyrolysis of waste tires after swelling pretreatment, comprising a stripping device, a crushing device, a swelling device, a feeding device, a pyrolysis device, a coke collecting device, a condensing device, a gas collecting device, a separation device, a limonene collecting device and an oil collecting device;

[0005] The waste tire outlet of the stripping device is connected with the inlet of the pulverizing device, the outlet of the pulverizing device is connected with the inlet of the swelling device, the outlet of the swelling device is connected with the inlet of the pyrolysis device via the feeding device, the tar outlet of the pyrolysis device is connected with the inlet of the tar collecting device, the gas outlet of the pyrolysis device is connected with the inlet of the condensing device, the gas outlet of the condensing device is connected with the inlet of the gas collecting device, the pyrolysis oil outlet of the condensing device is connected with the inlet of the separation device, the limonene outlet of the separation device is connected with the inlet of the limonene collecting device, and the pyrolysis oil outlet of the separation device is connected with the oil collecting device.

[0006] The improvement of the system for preparing limonene based on pyrolysis of waste tires after swelling pretreatment according to the present invention is:

[0007] Furthermore, the swelling device contains an organic solvent.

[0008] Furthermore, the organic solvent is one or a mixture of ethanol, glycerol, n-pentanol and isoamyl alcohol.

[0009] Furthermore, the interior of the pyrolysis device is vacuum and the temperature is 400-500°C.

[0010] Furthermore, one-way valves are provided between the stripping device and the crushing device, between the crushing device and the swelling device, between the swelling device and the feeding device, between the feeding device and the pyrolysis device, between the pyrolysis device and the coke collection device, between the pyrolysis device and the condensation device, between the condensation device and the gas collection device, between the condensation device and the separation device, between the separation device and the limonene collection device, and between the separation device and the oil collection device.

[0011] The present invention discloses a method for preparing limonene by pyrolyzing waste tires after swelling pretreatment, comprising the following steps:

[0012] 1) taking the cleaned waste tires and adding them into a stripping device, wherein the waste tires are stripped of the steel wires in the waste tires by the stripping device and then enter the crushing device, and then pass through the crushing device to obtain waste tire powder;

[0013] 2) feeding the waste tire powder into a swelling device, where the waste tire powder is soaked to expand the volume of the waste tire, and feeding the swollen waste tire powder into a pyrolysis device through a feeding device, and then pyrolyzing in the pyrolysis device;

[0014] 3) The coke obtained by pyrolysis is sent to a coke collecting device, and the volatile matter generated by pyrolysis is sent to a condensing device for condensation, wherein the uncondensed gas output by the condensing device is sent to a gas collecting device, and the pyrolysis oil output by the condensing device is sent to a separation device for separation, wherein the separated limonene enters the limonene collecting device, and the remaining separated part is sent to an oil collecting device.

[0015] The improvement of the system for preparing limonene based on pyrolysis of waste tires after swelling pretreatment according to the present invention is:

[0016] Furthermore, the particle size of the waste tire powder in step 1) is 20-100 mesh.

[0017] Further, in step 2), the mixture is immersed for 8-12 hours.

[0018] Furthermore, in step 2), the pyrolysis time is 20-30 min.

[0019] Furthermore, the yield of pyrolysis oil is 20-40wt%, and the yield of limonene is 10-25%.

[0020] The present invention has the following beneficial effects:

[0021] The system and method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to the present invention, in specific operation, changes the internal pores of waste tire powder through swelling pretreatment, regulates the pyrolysis process of waste tires, is beneficial to promoting pore formation during the pyrolysis process of waste tires, promotes the generation of limonene to prepare pyrolysis oil rich in limonene, contributes to the high-value recycling of waste tires, and improves the economic efficiency of pyrolysis of waste tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 It is a structural diagram of the present invention;

[0024] Figure 2 The figure is a flow chart of the method of the present invention.

[0025] Among them, 1 is a stripping device, 2 is a crushing device, 3 is a swelling device, 4 is a feeding device, 5 is a pyrolysis device, 6 is a coke collecting device, 7 is a condensing device, 8 is a gas collecting device, 9 is a separation device, 10 is a limonene collecting device, and 11 is an oil collecting device. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0028] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0029] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0030] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0031] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0034] Embodiment 1

[0035] refer to Figure 1 The system for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to the present invention comprises a stripping device 1, a crushing device 2, a swelling device 3, a feeding device 4, a pyrolysis device 5, a coke collecting device 6, a condensing device 7, a gas collecting device 8, a separation device 9, a limonene collecting device 10 and an oil collecting device 11;

[0036] The waste tire outlet of the stripping device 1 is connected to the inlet of the crushing device 2, the outlet of the crushing device 2 is connected to the inlet of the swelling device 3, the outlet of the swelling device 3 is connected to the inlet of the pyrolysis device 5 via the feeding device 4, the tar outlet of the pyrolysis device 5 is connected to the inlet of the tar collecting device 6, the gas outlet of the pyrolysis device 5 is connected to the inlet of the condensing device 7, the gas outlet of the condensing device 7 is connected to the inlet of the gas collecting device 8, the pyrolysis oil outlet of the condensing device 7 is connected to the inlet of the separation device 9, the limonene outlet of the separation device 9 is connected to the inlet of the limonene collecting device 10, and the pyrolysis oil outlet of the separation device 9 is connected to the oil collecting device 11.

[0037] As an embodiment of the present invention, the waste tire containing steel wires is stripped by a stripping device 1 .

[0038] As an embodiment of the present invention, the swelling device 3 contains an organic solvent.

[0039] As an embodiment of the present invention, specifically, the swelling device 3 contains organic solvents such as ethanol, glycerol, n-pentanol, isoamyl alcohol, etc., and the interior of the pyrolysis device 5 is vacuum and the temperature is 400-500°C.

[0040] As an embodiment of the present invention, one-way valves are provided between the stripping device 1 and the crushing device 2, between the crushing device 2 and the swelling device 3, between the swelling device 3 and the feeding device 4, between the feeding device 4 and the pyrolysis device 5, between the pyrolysis device 5 and the coke collection device 6, between the pyrolysis device 5 and the condensation device 7, between the condensation device 7 and the gas collection device 8, between the condensation device 7 and the separation device 9, between the separation device 9 and the limonene collection device 10, and between the separation device 9 and the oil collection device 11 to prevent backflow of materials or products.

[0041] Embodiment 2

[0042] refer to Figure 2 The method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to the present invention comprises the following steps:

[0043] 1) Take the cleaned waste tires and add them into the stripping device 1. After the steel wires in the waste tires are stripped off by the stripping device 1, the waste tires enter the crushing device 2, and then pass through the crushing device 2 to obtain 20-100 mesh waste tire powder;

[0044] 2) The waste tire powder is fed into a swelling device 3, and the waste tire powder is soaked in the swelling device 3 for 8-12 hours to expand the volume of the waste tire. The swollen waste tire powder is fed into a pyrolysis device 5 through a feeding device 4, and then pyrolyzed in the pyrolysis device 5 for 20-30 minutes;

[0045] 3) The coke obtained by pyrolysis is sent to a coke collecting device 6, and the volatile matter produced by pyrolysis is sent to a condensing device 7 for condensation, wherein the uncondensed gas output by the condensing device 7 is sent to a gas collecting device 8, and the pyrolysis oil output by the condensing device 7 is sent to a separation device 9 for separation, wherein the separated limonene enters a limonene collecting device 10, and the remaining separated part is sent to an oil collecting device 11.

[0046] The yield of pyrolysis oil in the present invention is 20-40wt%, and the yield of limonene is 10-25%.

[0047] Embodiment 3

[0048] The method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to the present invention comprises the following steps:

[0049] 1) Take the cleaned waste tires and add them into the stripping device 1. After the steel wires in the waste tires are stripped off by the stripping device 1, the waste tires enter the crushing device 2 and are crushed into 40 meshes by the crushing device 2 to obtain waste tire powder;

[0050] 2) The waste tire powder is sent to the swelling device 3, and the waste tire powder is soaked in the swelling device 3 for 10 hours to expand the volume of the waste tire. The swollen waste tire powder is sent to the pyrolysis device 5 through the feeding device 4, and then pyrolyzed in the pyrolysis device 5 for 25 minutes;

[0051] 3) The coke obtained by pyrolysis is sent to a coke collecting device 6, and the volatile matter produced by pyrolysis is sent to a condensing device 7 for condensation, wherein the uncondensed gas output by the condensing device 7 is sent to a gas collecting device 8, and the pyrolysis oil output by the condensing device 7 is sent to a separation device 9 for separation, wherein the separated limonene enters a limonene collecting device 10, and the remaining separated part is sent to an oil collecting device 11.

[0052] The samples were taken out, weighed and the product yields were calculated. In this embodiment, the pyrolysis coke yield was 44.7wt%, the pyrolysis gas yield was 22.4wt%, the pyrolysis oil yield was 32.9wt%, and the limonene yield was 8.9wt%.

[0053] Embodiment 4

[0054] The method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to the present invention comprises the following steps:

[0055] 1) Take the cleaned waste tires and add them into the stripping device 1. After the steel wires in the waste tires are stripped off by the stripping device 1, the waste tires enter the crushing device 2, and then pass through the crushing device 2 to obtain 20-100 mesh waste tire powder;

[0056] 2) The waste tire powder is fed into a swelling device 3, and the waste tire powder is soaked in the swelling device 3 for 8 hours to expand the volume of the waste tire. The swollen waste tire powder is fed into a pyrolysis device 5 through a feeding device 4, and then pyrolyzed in the pyrolysis device 5 for 20 minutes;

[0057] 3) The coke obtained by pyrolysis is sent to a coke collecting device 6, and the volatile matter produced by pyrolysis is sent to a condensing device 7 for condensation, wherein the uncondensed gas output by the condensing device 7 is sent to a gas collecting device 8, and the pyrolysis oil output by the condensing device 7 is sent to a separation device 9 for separation, wherein the separated limonene enters a limonene collecting device 10, and the remaining separated part is sent to an oil collecting device 11.

[0058] In this embodiment, the yield of pyrolysis oil is 20wt%, and the yield of limonene is 10%.

[0059] In this embodiment, the organic solvent is ethanol.

[0060] In this embodiment, the interior of the pyrolysis device 5 is vacuum and the temperature is 400°C.

[0061] Embodiment 5

[0062] The method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to the present invention comprises the following steps:

[0063] 1) Take the cleaned waste tires and add them into the stripping device 1. After the steel wires in the waste tires are stripped off by the stripping device 1, the waste tires enter the crushing device 2, and then pass through the crushing device 2 to obtain 20-100 mesh waste tire powder;

[0064] 2) The waste tire powder is fed into a swelling device 3, and the waste tire powder is soaked in the swelling device 3 for 12 hours to expand the volume of the waste tire. The swollen waste tire powder is fed into a pyrolysis device 5 through a feeding device 4, and then pyrolyzed in the pyrolysis device 5 for 30 minutes;

[0065] 3) The coke obtained by pyrolysis is sent to a coke collecting device 6, and the volatile matter produced by pyrolysis is sent to a condensing device 7 for condensation, wherein the uncondensed gas output by the condensing device 7 is sent to a gas collecting device 8, and the pyrolysis oil output by the condensing device 7 is sent to a separation device 9 for separation, wherein the separated limonene enters a limonene collecting device 10, and the remaining separated part is sent to an oil collecting device 11.

[0066] In this embodiment, the yield of pyrolysis oil is 40wt%, and the yield of limonene is 25%.

[0067] In this embodiment, the organic solvent is a mixture of ethanol, propylene glycol, n-pentanol and isoamyl alcohol.

[0068] In this embodiment, the interior of the pyrolysis device 5 is vacuum and the temperature is 500°C.

[0069] Embodiment 6

[0070] The method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to the present invention comprises the following steps:

[0071] 1) Take the cleaned waste tires and add them into the stripping device 1. After the steel wires in the waste tires are stripped off by the stripping device 1, the waste tires enter the crushing device 2, and then pass through the crushing device 2 to obtain 20-100 mesh waste tire powder;

[0072] 2) The waste tire powder is fed into a swelling device 3, and the waste tire powder is soaked in the swelling device 3 for 10 hours to expand the volume of the waste tire. The swollen waste tire powder is fed into a pyrolysis device 5 through a feeding device 4, and then pyrolyzed in the pyrolysis device 5 for 25 minutes;

[0073] 3) The coke obtained by pyrolysis is sent to a coke collecting device 6, and the volatile matter produced by pyrolysis is sent to a condensing device 7 for condensation, wherein the uncondensed gas output by the condensing device 7 is sent to a gas collecting device 8, and the pyrolysis oil output by the condensing device 7 is sent to a separation device 9 for separation, wherein the separated limonene enters a limonene collecting device 10, and the remaining separated part is sent to an oil collecting device 11.

[0074] In this embodiment, the yield of pyrolysis oil is 30wt%, and the yield of limonene is 15%.

[0075] In this embodiment, the organic solvent is isoamyl alcohol.

[0076] In this embodiment, the interior of the pyrolysis device 5 is vacuum and the temperature is 450°C.

[0077] It should be noted that the present invention changes the physical properties of the waste tires through the swelling modulation treatment of the waste tires, which is beneficial to promoting pore formation during the pyrolysis of the waste tires, reducing the retention time of volatiles during the pyrolysis of the waste tires, and promoting the generation of limonene during the pyrolysis of the waste tires. Therefore, the present invention is conducive to the high-value utilization of the waste tires and improves the economic benefits of the pyrolysis of the waste tires.

[0078] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0079] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0080] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A system for preparing limonene by pyrolysis of waste tires after swelling pretreatment, characterized in that: It comprises a stripping device (1), a crushing device (2), a swelling device (3), a feeding device (4), a pyrolysis device (5), a coke collecting device (6), a condensing device (7), a gas collecting device (8), a separation device (9), a limonene collecting device (10) and an oil collecting device (11); The waste tire outlet of the stripping device (1) is connected to the inlet of the pulverizing device (2), the outlet of the pulverizing device (2) is connected to the inlet of the swelling device (3), the outlet of the swelling device (3) is connected to the inlet of the pyrolysis device (5) via the feeding device (4), the tar outlet of the pyrolysis device (5) is connected to the inlet of the tar collecting device (6), the gas outlet of the pyrolysis device (5) is connected to the inlet of the condensing device (7), the gas outlet of the condensing device (7) is connected to the inlet of the gas collecting device (8), the pyrolysis oil outlet of the condensing device (7) is connected to the inlet of the separation device (9), the limonene outlet of the separation device (9) is connected to the inlet of the limonene collecting device (10), and the pyrolysis oil outlet of the separation device (9) is connected to the oil collecting device (11).

2. The system for preparing limonene by pyrolysis of waste tires after swelling pretreatment according to claim 1, characterized in that: The swelling device (3) contains an organic solvent.

3. The system for preparing limonene by pyrolysis of waste tires after swelling pretreatment according to claim 2, characterized in that: The organic solvent is one or a mixture of ethanol, glycerol, n-pentanol and isoamyl alcohol.

4. The system for preparing limonene by pyrolysis of waste tires after swelling pretreatment according to claim 1, characterized in that: The interior of the pyrolysis device (5) is vacuum and the temperature is 400-500°C.

5. The system for preparing limonene by pyrolysis of waste tires after swelling pretreatment according to claim 1, characterized in that: One-way valves are provided between the stripping device (1) and the crushing device (2), between the crushing device (2) and the swelling device (3), between the swelling device (3) and the feeding device (4), between the feeding device (4) and the pyrolysis device (5), between the pyrolysis device (5) and the coke collection device (6), between the pyrolysis device (5) and the condensation device (7), between the condensation device (7) and the gas collection device (8), between the condensation device (7) and the separation device (9), between the separation device (9) and the limonene collection device (10), and between the separation device (9) and the oil collection device (11).

6. A method for preparing limonene by pyrolysis of waste tires after swelling pretreatment, characterized in that: The system for preparing limonene based on pyrolysis of waste tires after swelling pretreatment according to claim 1 comprises the following steps: 1) taking cleaned waste tires and adding them into a stripping device (1); the waste tires are stripped of steel wires in the waste tires by the stripping device (1) and then enter a crushing device (2); and then pass through the crushing device (2) to obtain waste tire powder; 2) feeding the waste tire powder into a swelling device (3), where the waste tire powder is soaked to expand the volume of the waste tire, and the swollen waste tire powder is fed into a pyrolysis device (5) through a feeding device (4), and then pyrolyzed in the pyrolysis device (5); 3) The coke obtained by pyrolysis is sent to a coke collecting device (6), and the volatile matter generated by pyrolysis is sent to a condensing device (7) for condensation, wherein the uncondensed gas output by the condensing device (7) is sent to a gas collecting device (8), and the pyrolysis oil output by the condensing device (7) is sent to a separation device (9) for separation, wherein the separated limonene enters a limonene collecting device (10), and the remaining separated part is sent to an oil collecting device (11).

7. The method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to claim 6, characterized in that: The particle size of the waste tire powder in step 1) is 20-100 meshes.

8. The method for preparing limonene by pyrolysis of waste tires after swelling pretreatment according to claim 6, characterized in that: Soak in step 2) for 8-12 hours.

9. The method for preparing limonene by pyrolyzing waste tires after swelling pretreatment according to claim 6, characterized in that: The pyrolysis time in step 2) is 20-30 min.

10. The method for preparing limonene by pyrolysis of waste tires after swelling pretreatment according to claim 6, characterized in that: The yield of pyrolysis oil is 20-40wt%, and the yield of limonene is 10-25%.

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