Staged cooling system and method for reducing coking and improving oil yield through pyrolysis of mixed plastics

Abstract

The invention discloses a graded cooling system and method for reducing coking and improving oil yield during pyrolysis of mixed plastics, relates to the technical field of pyrolysis treatment and processing of the mixed plastics, and solves the problem that equipment special for cooling pyrolysis gas of mixed plastic raw materials is lacked. A pyrolysis reactor, a wax removal tank, a first-stage cooler, a second-stage cooler, a first collection oil tank, a third-stage cooler and a second collection oil tank are sequentially communicated; the cooling mode of the first-stage cooler, the second-stage cooler and the third-stage cooler is water cooling, the first-stage cooler is a horizontal cooler, and the second-stage cooler is a vertical cooler. The multi-stage cooler is arranged, so that the temperature of high-temperature gas is effectively reduced, and the pyrolysis efficiency and the product quality are improved; and through the mode of combining the horizontal cooler and the vertical cooler, the oil yield can be improved, the problem that a cooling system is coked to block a pipeline is avoided, and the production efficiency is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pyrolysis treatment of mixed plastics, and specifically to a hierarchical cooling system and method for reducing coking and increasing oil yield in the pyrolysis of mixed plastics. Background Art

[0002] With the development of economy and the progress of society, plastic products are widely used in daily life. However, in the production process of plastic products, a large amount of waste plastics will be generated. If these waste plastics cannot be properly treated, they will cause serious pollution to the environment. At present, the treatment methods for waste plastics mainly include landfill, incineration and pyrolysis, etc. Among them, pyrolysis is an effective waste plastic recycling technology, which converts waste plastics into useful chemicals and energy through high-temperature decomposition. In the pyrolysis process, the cooling system is of great significance for ensuring pyrolysis efficiency and product quality. Existing cooling systems often have problems such as low oil yield and coking of the cooling system. Therefore, it is of great practical significance to research and develop a high-efficiency, energy-saving and easy-to-operate hierarchical cooling system device and method for the pyrolysis of mixed plastics. The existing vertical cooler is a device for cooling the pyrolysis gas generated after the pyrolysis of oil sludge, and the existing horizontal cooler is a device for cooling the pyrolysis gas generated after the pyrolysis of tire rubber. There is no special device and system for cooling the pyrolysis gas generated after the pyrolysis of mixed plastic raw materials in the existing technology; when the vertical cooler is used for the pyrolysis of mixed plastic raw materials, there is a problem of coking due to too fast cooling, and when the horizontal cooler is used for the pyrolysis of mixed plastic raw materials, there is a problem that the main furnace is scrapped due to excessive heating. Summary of the Invention

[0003] In order to solve the problem of the lack of a special device for cooling the pyrolysis gas of mixed plastic raw materials mentioned above, the present invention hereby provides a hierarchical cooling system and method for reducing coking and increasing oil yield in the pyrolysis of mixed plastics. By setting up multiple stages of coolers, the present invention effectively reduces the temperature of high-temperature gas, improves pyrolysis efficiency and product quality; and by combining a horizontal cooler and a vertical cooler, the oil yield can be increased, the problem of coking and blocking of the pipeline in the cooling system can be avoided, and the production efficiency can be further improved.

[0004] The present invention provides a hierarchical cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics, which specifically includes a pyrolysis reactor, a first-stage cooler, a second-stage cooler and a first collection oil tank. The pyrolysis reactor, the first-stage cooler, the second-stage cooler and the first collection oil tank are connected in sequence; the cooling methods of the first-stage cooler and the second-stage cooler are water cooling. The first-stage cooler is a horizontal cooler, and the second-stage cooler is a vertical cooler.

[0005] Furthermore, the first-stage cooler is internally provided with a metal pipeline with a diameter of more than 200 millimeters and a downward inclination angle of 15°.

[0006] Furthermore, the second-stage cooler is internally provided with metal pipes with a diameter of 120 mm and a spiral distribution.

[0007] Furthermore, a wax removal tank is arranged between the pyrolysis reactor and the first-stage cooler, and the pyrolysis reactor, the wax removal tank and the first-stage cooler are connected in sequence.

[0008] Furthermore, a collecting steam tank is arranged between the pyrolysis reactor and the wax removal tank.

[0009] Furthermore, it further includes a third-stage cooler and a second collecting oil tank, and the first collecting oil tank, the third-stage cooler and the second collecting oil tank are connected in sequence.

[0010] Furthermore, the third-stage cooler is a water-cooled cooler.

[0011] Furthermore, temperature sensors are arranged in the first-stage cooler, the second-stage cooler and the third-stage cooler.

[0012] Furthermore, flow regulating valves are arranged in the first-stage cooler and the second-stage cooler to regulate the flow rate of the cooling medium.

[0013] A method for using a hierarchical cooling system for reducing coking and increasing oil yield in the pyrolysis of the above-mentioned mixed plastics includes the following steps:

[0014] S1: After removing wax from the high-temperature gas after pyrolysis, it is transmitted to the first-stage cooler;

[0015] S2: In the first-stage cooler, the high-temperature gas is preliminarily cooled in a horizontal manner, and the preliminarily cooled gas is transmitted to the second-stage cooler;

[0016] S3: In the second-stage cooler, the preliminarily cooled gas is further cooled in a vertical manner, and the cooled gas is transmitted to the third-stage cooler;

[0017] S4: In the third-stage cooler, the cooled gas is condensed to obtain a liquid product.

[0018] The beneficial effects of the hierarchical cooling system and method for reducing coking and increasing oil yield in the pyrolysis of the mixed plastics according to the present invention are as follows:

[0019] (1) The hierarchical cooling system and method for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to the present invention overcomes the problem of the lack of special equipment for cooling the pyrolysis gas of mixed plastic raw materials, solves the problems of low oil yield and coking in the existing cooling system. By setting up coolers with multiple different structures, the temperature of high-temperature gas can be effectively reduced, and the pyrolysis efficiency and product quality can be improved. At the same time, by combining a horizontal cooler and a vertical cooler, the oil yield can be increased, the coking problem of the cooling system can be avoided, and the production efficiency can be further improved. In addition, the system has the advantages of simple structure, convenient operation, low energy consumption, etc., and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0021] In the drawings:

[0022] Figure 1 is a schematic structural diagram of a hierarchical cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to the present invention;

[0023] Wherein: 1 - pyrolysis reactor, 2 - collection steam tank, 3 - dewaxing tank, 4 - first-stage cooler, 5 - second-stage cooler, 6 - first collection oil tank, 7 - third-stage cooler, 8 - second collection oil tank. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "linkage" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Specific Embodiment 1: Refer to Figure 1 Specifically illustrate this embodiment. A hierarchical cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to this embodiment specifically includes a pyrolysis reactor 1, a first-stage cooler 4, a second-stage cooler 5, a first collection oil tank 6, a third-stage cooler 7, and a second collection oil tank 8. The pyrolysis reactor 1, the first-stage cooler 4, the second-stage cooler 5, the first collection oil tank 6, the third-stage cooler 7, and the second collection oil tank 8 are connected in sequence; the cooling methods of the first-stage cooler 4, the second-stage cooler 5, and the third-stage cooler 7 are all water cooling. The first-stage cooler 4 is a horizontal cooler, and the second-stage cooler 5 is a vertical cooler; the liquid products collected by the first collection oil tank 6 and the second collection oil tank 8.

[0029] The first-stage cooler 4 is internally provided with a metal pipe with a diameter of more than 200 millimeters and a downward inclination angle of 15°. The pyrolysis gas passes through the metal pipe and exchanges heat with the cooling medium. By setting a large-diameter pipe, while ensuring that coking is concentrated inside the first-stage cooler 4, coking blocking of the pipe is avoided.

[0030] The second-stage cooler 5 is internally provided with a metal pipe with a diameter of 120 millimeters and a spiral distribution. The pyrolysis gas passes through the metal pipe and exchanges heat with the cooling medium. The liquefaction effect is enhanced through the second-stage cooler 5 to increase the output.

[0031] A dewaxing tank 3 is arranged between the pyrolysis reactor 1 and the first-stage cooler 4. The pyrolysis reactor 1, the dewaxing tank 3, and the first-stage cooler 4 are connected in sequence. The wax component in the pyrolysis gas is separated through the dewaxing tank 3.

[0032] A collection steam tank 2 is arranged between the pyrolysis reactor 1 and the dewaxing tank 3.

[0033] Temperature sensors are installed in the first-stage cooler 4, the second-stage cooler 5, and the third-stage cooler 7 to achieve real-time monitoring of the internal temperature of the coolers. Flow regulating valves are installed in the first-stage cooler 4 and the second-stage cooler 5 to automatically adjust the flow rate of the cooling medium according to the signals from the temperature sensors.

[0034] A method for using a hierarchical cooling system for pyrolysis of mixed plastics to reduce coking and increase oil yield as described above includes the following steps:

[0035] S1: Transfer the high-temperature gas after pyrolysis to the first-stage cooler 4 after dewaxing in the dewaxing tank 3.

[0036] S2: In the first-stage cooler 4, preliminarily cool the high-temperature gas horizontally and transfer the preliminarily cooled gas to the second-stage cooler 5.

[0037] S3: In the second-stage cooler 5, further cool the preliminarily cooled gas vertically, store the resulting liquid product in the first collection oil tank 6, and transfer the cooled gas to the third-stage cooler 7.

[0038] S4: In the third-stage cooler 7, condense the cooled gas to obtain a liquid product, and store the liquid product in the second collection oil tank 8.

[0039] Summarizing the above embodiments, the hierarchical cooling system and method for pyrolysis of mixed plastics to reduce coking and increase oil yield according to the present invention overcomes the problem of lacking special equipment for cooling the pyrolysis gas of mixed plastic raw materials, solves the problems of low oil yield and coking in the existing cooling system. By setting up multiple coolers with different structures, the temperature of the high-temperature gas can be effectively reduced, improving the pyrolysis efficiency and product quality. At the same time, by combining a horizontal cooler and a vertical cooler, the oil yield can be increased, the problem of coking in the cooling system can be avoided, and the production efficiency can be further improved. In addition, the system has the advantages of simple structure, convenient operation, and low energy consumption, and has a wide application prospect.

[0040] In the specific embodiments described above, the purpose, technical solution, and beneficial effects of the present invention are further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the invention. It can also be a reasonable combination of the features described in the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A hierarchical cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics, characterized in that: It includes a pyrolysis reactor (1), a first-stage cooler (4), a second-stage cooler (5) and a first collection oil tank (6). The pyrolysis reactor (1), the first-stage cooler (4), the second-stage cooler (5) and the first collection oil tank (6) are connected in sequence. The cooling methods of the first-stage cooler (4) and the second-stage cooler (5) are water cooling. The first-stage cooler (4) is a horizontal cooler, and the second-stage cooler (5) is a vertical cooler.

2. The fractional cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 1, wherein: The first-stage cooler (4) is internally provided with a metal pipe with a diameter of more than 200 mm and a downward inclination angle of 15°.

3. The staged cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 1, characterized in that: The second-stage cooler (5) is internally provided with a metal pipe with a diameter of 120 mm and a spiral distribution.

4. The fractional cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 1, characterized in that: A dewaxing tank (3) is arranged between the pyrolysis reactor (1) and the first-stage cooler (4). The pyrolysis reactor (1), the dewaxing tank (3) and the first-stage cooler (4) are connected in sequence.

5. The fractional cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 4, characterized in that: A collection steam tank (2) is arranged between the pyrolysis reactor (1) and the dewaxing tank (3).

6. The fractional cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 4, characterized in that: It further includes a third-stage cooler (7) and a second collection oil tank (8). The first collection oil tank (6), the third-stage cooler (7) and the second collection oil tank (8) are connected in sequence.

7. The fractional cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 6, characterized in that: The third-stage cooler (7) is a water-cooled cooler.

8. The hierarchical cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 6, characterized in that: Temperature sensors are arranged in the first-stage cooler (4), the second-stage cooler (5) and the third-stage cooler (7).

9. The fractional cooling system for reducing coking and increasing oil yield in the pyrolysis of mixed plastics according to claim 8, characterized in that: Flow regulating valves are arranged in the first-stage cooler (4) and the second-stage cooler (5) to regulate the flow rate of the cooling medium.

10. A method for using a hierarchical cooling system for reducing coking and increasing oil yield in the pyrolysis of the hybrid plastic described in claim 9, characterized in that: It includes the following steps: S1: After dewaxing the high-temperature gas after pyrolysis, transfer it to the first-stage cooler (4). S2: In the first-stage cooler (4), preliminarily cool the high-temperature gas in a horizontal manner and transfer the preliminarily cooled gas to the second-stage cooler (5). S3: In the second-stage cooler (5), further cool the preliminarily cooled gas in a vertical manner and transfer the cooled gas to the third-stage cooler (7). S4: In the third-stage cooler (7), condense the cooled gas to obtain a liquid product.

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