Waste plastic recycling melting and washing system and method

Abstract

The present application discloses a waste plastic recycling melting and washing system and method. The waste plastic is processed and transferred to a secondary tank under the action of high-temperature and high-pressure steam melting and washing in a main tank. The inner tank is set in an outer tank to form a main tank. The inner tank is driven to rotate in the outer tank, and the generated cleaning steam is directly introduced into the inner tank to clean the impurities on the waste plastic. At the same time, a plurality of prefabricated through holes are provided on the inner tank, and the generated high-pressure steam is used to spray and heat the inner tank, which greatly improves the melting and washing efficiency. In addition, on the first conveying path and the first waste heat recovery path, the waste heat is recycled by setting a first exchanger, a second exchanger, and a third exchanger, thereby improving energy utilization efficiency and reducing energy consumption.

Description

Technical Field

[0001] The present application relates to the technical field of waste plastic processing, and in particular to a waste plastic recycling melting and washing system and method. Background Art

[0002] Plastics are primarily synthetic resin products made from materials such as polyethylene, polypropylene, and polystyrene. Waste plastics refer to plastic products generated in daily life and production activities that have lost their original value and are discarded. If not properly handled, these waste plastics will cause serious environmental pollution. To reduce the negative impact of waste plastics on the environment, it is usually necessary to sort, clean, and crush waste plastics, converting them into raw materials or products to achieve resource recycling.

[0003] The first step in processing waste plastics is meticulous sorting to ensure that different types of plastic are strictly separated. Subsequently, efficient cleaning equipment removes dirt and impurities from the plastic surface. These removed waste and cleaned plastic are collected separately to ensure the high purity of the plastic raw materials. Finally, specialized crushing machinery is used to process the waste plastic into small pieces or granules for further processing and utilization.

[0004] With the growing demand for recycling and reuse of waste plastics, the demand for plastic waste treatment is also increasing. However, the existing cleaning equipment is not technologically advanced and has many deficiencies in energy consumption and cleaning efficiency.

[0005] Traditional equipment is typically mechanically controlled, resulting in unstable cleaning temperatures and pressures, making it difficult to achieve efficient energy conservation and precise cleaning of different plastic types. Furthermore, high energy consumption, complex operation, and significant environmental pollution are also common issues with existing equipment. Summary of the Invention

[0006] To this end, the present application provides a waste plastic recycling melting and washing system and method to solve the problem that the current waste plastic washing cannot achieve high efficiency and energy saving and accurate cleaning of different types of plastics.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] According to a first aspect of an embodiment of the present invention, an embodiment of the present application provides a waste plastic recycling melting and washing system, the system comprising:

[0009] A main tank and a subsidiary tank, wherein the main tank includes an outer bin and an inner bin, the inner bin is sleeved in the outer bin and rotated in the outer bin by a drive, the inner bin is provided with a plurality of prefabricated through holes, and the main tank and the subsidiary tank are connected through a feed pipe;

[0010] A first delivery path is formed by a first delivery end connected to a first high-pressure cleaning main pipeline in sequence through a first circulation pump, a first low-temperature circuit of a first exchanger, a second low-temperature circuit of a second exchanger, a third low-temperature circuit of a third exchanger, a first heater, and a first compressor, wherein the first high-pressure cleaning main pipeline is connected to an air intake pipe communicating with the inner chamber;

[0011] A first waste heat recovery path is formed by the first pressure relief port, sequentially passing through the third high-temperature circuit of the third exchanger, the second high-temperature circuit of the second exchanger, the first high-temperature circuit of the first exchanger, and the second circulation pump to connect to the first input end of the waste liquid purifier;

[0012] Among them, the input ends of the first high-temperature circuit and the second high-temperature circuit are respectively connected to the waste liquid outlet and the second pressure relief port; the first pressure relief port and the second pressure relief port are respectively arranged on the outer chamber and the auxiliary tank, and the waste liquid outlet is arranged at one end of the auxiliary tank near the bottom.

[0013] Furthermore, the output end of the third low-temperature circuit is connected to a second high-pressure cleaning main pipeline via a second heater and a second compressor, and the second high-pressure cleaning main pipeline is connected to a cleaning pipeline in the auxiliary tank.

[0014] Furthermore, the system further comprises:

[0015] a second delivery path formed by the second delivery end being connected to the first high-pressure steam main pipeline in sequence through the third circulation pump, the fourth low-temperature circuit of the fourth exchanger, the fifth low-temperature circuit of the fifth exchanger, the sixth low-temperature circuit of the sixth exchanger, the third heater, and the third compressor, wherein the first high-pressure steam main pipeline is connected to each steam nozzle arranged on the outer chamber;

[0016] A second waste heat recovery path is formed by the first pressure relief port, sequentially passing through the sixth high-temperature circuit of the sixth exchanger, the fifth high-temperature circuit of the fifth exchanger, the fourth high-temperature circuit of the fourth exchanger, and the fourth circulation pump to connect to the second input end of the waste liquid purifier;

[0017] The input ends of the fourth high-temperature circuit and the fifth high-temperature circuit are connected to the waste liquid outlet and the second pressure relief port respectively.

[0018] Furthermore, the output end of the sixth low-temperature circuit is connected to the second high-pressure steam main pipeline via the fourth heater and the fourth compressor, and the second high-pressure steam main pipeline is connected to each cooling nozzle arranged on the outer compartment.

[0019] Furthermore, the first delivery end is formed by the first liquid storage tank connecting with the second liquid storage tank via the third circulation pump, the second delivery end is directly formed by the output end of the first liquid storage tank, and the output end of the waste liquid purifier is connected to the input end of the first liquid storage tank.

[0020] Furthermore, a first switch valve is arranged between the second liquid storage tank and the first circulation pump, a second switch valve is arranged between the third circulation pump and the output end of the fourth low-temperature circuit, a first intersection point is formed between the first switch valve and the first circulation pump, a second intersection point is formed between the third circulation pump and the second switch valve, a third switch valve is arranged between the first intersection point and the second intersection point, and a fourth switch valve, a fifth switch valve, a sixth switch valve and a seventh switch valve are respectively arranged at the output end of the first compressor, the output end of the second compressor, the output end of the third compressor and the output end of the fourth compressor.

[0021] Furthermore, the system further includes: a controller configured to perform the following steps:

[0022] Starting the third circulation pump, the third compressor, and the third heater, and closing the second on-off valve and the sixth on-off valve, thereby opening the second delivery passage and spraying the first high-pressure steam into the inner chamber through the first high-pressure steam main pipeline and the various steam nozzles;

[0023] Starting the second circulation pump and the fourth circulation pump to connect the first waste heat recovery path and the second waste heat recovery path;

[0024] Initializing settings for the first preset condition, the second preset condition, the third preset condition, the fourth preset condition, the fifth preset condition, the sixth preset condition, the seventh preset condition, and the eighth preset condition;

[0025] Detecting a first temperature T11 and a first pressure P11 in the main tank according to a preset period and recording a corresponding first collection time t1;

[0026] determining whether the first temperature T11 satisfies a first preset condition, where the first preset condition is that the first temperature T11 is greater than or equal to a first preset temperature threshold and less than or equal to a second preset temperature threshold, and the second preset temperature threshold is greater than the first preset temperature threshold;

[0027] If the first temperature T11 does not meet the first preset condition, determining whether the first temperature T11 meets a second preset condition, where the second preset condition is that the first temperature T11 is greater than or equal to a third preset temperature threshold, and the third preset temperature threshold is greater than the second preset temperature threshold;

[0028] If the first temperature T11 meets the second preset condition, the fourth compressor and the fourth heater are started according to the first preset time period, and the seventh switch valve is turned on, and the second high-pressure steam is sprayed into the inner chamber through the second high-pressure steam main pipeline and each cooling nozzle. The cycle continues until the first temperature T11 and the first pressure P11 in the main tank are detected in the next preset period, and the corresponding first collection time t1 is recorded;

[0029] If the first temperature T11 does not meet the second preset condition, then obtaining a first target control temperature T01 corresponding to the current first acquisition time t1 based on the first preset temperature control function;

[0030] Calculate a first temperature difference ΔT1 by subtracting the first target control temperature T01 from the first temperature T11;

[0031] Determining whether the absolute value of the first temperature difference ΔT1 is greater than or equal to a first preset temperature difference threshold;

[0032] If the absolute value of the first temperature difference ΔT1 is greater than or equal to a first preset temperature difference threshold, adjusting the heating power of the third heater based on the first temperature difference ΔT1, and determining whether the first pressure P11 meets a third preset condition, wherein the third preset condition is that the first pressure P11 is greater than or equal to a first preset pressure threshold and less than or equal to a second preset pressure threshold, and the second preset pressure threshold is greater than the first preset pressure threshold;

[0033] If the absolute value of the first temperature difference ΔT1 is less than the first preset temperature difference threshold, it is directly determined whether the first pressure P11 meets the third preset condition;

[0034] If the first pressure P11 does not meet the third preset condition, determining whether the first pressure P11 meets a fourth preset condition, the fourth preset condition being that the first pressure P11 is greater than or equal to a third preset pressure threshold, and the third preset pressure threshold is greater than the second preset pressure threshold;

[0035] If the first pressure P11 satisfies the fourth preset condition, the second circulation pump and the fourth circulation pump are started according to the second preset time period and the first pressure relief port is opened. The process continues until the first temperature T11 and the first pressure P11 in the main tank are detected in the next preset period and the corresponding first collection time t1 is recorded.

[0036] If the first pressure P11 does not meet the fourth preset condition, then obtaining a first target control pressure P01 corresponding to the current first acquisition time t1 based on the first preset pressure control function;

[0037] Calculating a first pressure difference value ΔP1 by subtracting the first target control pressure P01 from the first pressure P11;

[0038] Determining whether the absolute value of the first pressure difference value ΔP1 is greater than or equal to a first preset pressure difference threshold;

[0039] If the absolute value of the first pressure difference ΔP1 is greater than or equal to a first preset pressure difference threshold, the speeds of the third compressor and the third circulation pump are adjusted based on the first pressure difference ΔP1, and the process continues until the first temperature T11 and the first pressure P11 in the main tank of the next preset period are detected and the corresponding first collection time t1 is recorded;

[0040] If the absolute value of the first pressure difference ΔP1 is smaller than the first preset pressure difference threshold, the process directly cycles to detecting the first temperature T11 and the first pressure P11 in the main tank in the next preset period and records the corresponding first collection time t1.

[0041] The controller is further configured to perform the following steps:

[0042] If the first pressure P11 satisfies a third preset condition, the first circulation pump, the first compressor, and the first heater are started, and the first on-off valve, the third on-off valve, and the fourth on-off valve are connected, thereby opening the first delivery passage and delivering the first cleaning steam to the inner chamber through the first high-pressure cleaning main pipeline and the air intake pipe. It is then determined whether the first collection time t1 satisfies a fifth preset condition, wherein the fifth preset condition is that the first collection time t1 is greater than or equal to a first preset time threshold.

[0043] If the first collection time t1 does not meet the fifth preset condition, the process loops to detect the first temperature T11 and the first pressure P11 in the main tank in the next preset period and records the corresponding first collection time t1;

[0044] If the first collection time t1 satisfies a fifth preset condition, the second compressor and the second heater are started and the fifth switch valve is turned on to deliver the second cleaning steam to the auxiliary tank through the second high-pressure cleaning main pipeline and the cleaning pipeline;

[0045] Detecting the second temperature T12 and the second pressure P12 in the auxiliary tank according to a preset period and recording the corresponding second collection time t2;

[0046] determining whether the second temperature T12 satisfies a sixth preset condition, the sixth preset condition being that the second temperature T12 is greater than or equal to a fourth preset temperature threshold and less than or equal to a fifth preset temperature threshold, and the fifth preset temperature threshold is greater than the fourth preset temperature threshold;

[0047] If the second temperature T12 does not meet the sixth preset condition, obtaining a second target control temperature T02 corresponding to the current second acquisition time t2 based on the second preset temperature control function;

[0048] Calculate a second temperature difference ΔT2 by subtracting the second target control temperature T02 from the second temperature T12;

[0049] Determining whether the absolute value of the second temperature difference ΔT2 is greater than or equal to a second preset temperature difference threshold;

[0050] If the absolute value of the second temperature difference ΔT2 is greater than or equal to a second preset temperature difference threshold, adjusting the heating power of the second heater based on the second temperature difference ΔT2, and determining whether the second pressure P12 meets a seventh preset condition, the seventh preset condition being that the second pressure P12 is greater than or equal to a fourth preset pressure threshold;

[0051] If the absolute value of the second temperature difference ΔT2 is less than the second preset temperature difference threshold, directly determining whether the second pressure P12 meets the seventh preset condition;

[0052] If the second pressure P12 meets the seventh preset condition, the second pressure relief port is opened according to the second preset time period, and the first temperature T11 and the first pressure P11 in the main tank are detected in the next preset period and the corresponding first collection time t1 is recorded;

[0053] If the second pressure P12 does not meet the seventh preset condition, the process loops to detect the first temperature T11 and the first pressure P11 in the main tank in the next preset period and records the corresponding first collection time t1.

[0054] The controller is further configured to perform the following steps:

[0055] If the first acquisition time t1 does not meet the fifth preset condition, determining whether the first acquisition time t1 meets a sixth preset condition, the sixth preset condition being that the first acquisition time t1 is greater than or equal to a second preset time threshold;

[0056] If the first collection time t1 does not meet the fifth preset condition, the process loops to detect the first temperature T11 and the first pressure P11 in the main tank in the next preset period and records the corresponding first collection time t1;

[0057] If the first collection time t1 satisfies the fifth preset condition, then updating the first preset condition, the second preset condition, the third preset condition, the fourth preset condition and the seventh preset condition according to a preset rule;

[0058] The first acquisition time t1 is updated to 0 and the cycle continues to detect the first temperature T11 and the first pressure P11 in the main tank in the next preset period.

[0059] According to a second aspect of an embodiment of the present invention, an embodiment of the present application provides a method for recycling and melting waste plastics, the method comprising:

[0060] The inner bin is placed inside the outer bin to form a main tank, and the main tank is connected to the auxiliary tank through a feed pipe. The inner bin is driven to rotate inside the outer bin, and a plurality of prefabricated through holes are provided on the inner bin;

[0061] A first conveying path is formed by connecting the first conveying end to the first high-pressure cleaning main pipeline through the first circulation pump, the first low-temperature circuit of the first exchanger, the second low-temperature circuit of the second exchanger, the third low-temperature circuit of the third exchanger, the first heater, and the first compressor in sequence. The first high-pressure cleaning main pipeline is connected to the air intake pipe communicated with the inner chamber.

[0062] A first waste heat recovery path is formed by connecting the first pressure relief port to the first input end of the waste liquid purifier through the third high-temperature circuit of the third exchanger, the second high-temperature circuit of the second exchanger, the first high-temperature circuit of the first exchanger, and the second circulation pump in sequence;

[0063] Among them, the input ends of the first high-temperature circuit and the second high-temperature circuit are respectively connected to the waste liquid outlet and the second pressure relief port; the first pressure relief port and the second pressure relief port are respectively arranged on the outer chamber and the auxiliary tank, and the waste liquid outlet is arranged at one end of the auxiliary tank near the bottom.

[0064] Compared with the prior art, the embodiments of the present application provide a waste plastic recycling melting and washing system and method. The waste plastic is processed and transferred to a secondary tank under the action of high-temperature and high-pressure steam melting and washing in a main tank. The inner tank is set in the outer tank to form a main tank. The inner tank is driven to rotate in the outer tank, and the generated cleaning steam is directly introduced into the inner tank to clean the impurities on the waste plastic. At the same time, a plurality of prefabricated through holes are provided on the inner tank, and the generated high-pressure steam is used to spray and heat the inner tank, which greatly improves the melting and washing efficiency. In addition, on the first conveying path and the first waste heat recovery path, the waste heat is recycled and utilized by setting the first exchanger, the second exchanger, and the third exchanger, thereby improving energy utilization efficiency and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0066] The structures, proportions, sizes, etc. illustrated in this specification are intended only to complement the contents disclosed herein and to facilitate understanding and reading by persons familiar with the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall still fall within the scope of the technical contents disclosed herein.

[0067] Figure 1 A schematic diagram of the structure of a main tank and a sub-tank in a waste plastic recycling melting and washing system provided in an embodiment of the present application;

[0068] Figure 2 A schematic diagram of the structure of a circulating air supply and waste heat recovery system for recycling and melting and washing waste plastics provided in an embodiment of the present application;

[0069] Figure 3 A schematic diagram of the control logic structure of a controller for a waste plastic recycling melting and washing system provided in an embodiment of the present application;

[0070] Figure 4 A schematic flow chart of execution steps of a controller of a waste plastic recycling melting and washing system provided in one embodiment of the present application;

[0071] Figure 5 A schematic flow chart of execution steps of a controller of a waste plastic recycling melting and washing system provided in another embodiment of the present application;

[0072] Figure 6 A flowchart illustrating the execution steps of a controller of a waste plastic recycling melting and washing system provided in another embodiment of the present application.

[0073] Description of reference numerals:

[0074] 01. Main tank; 02. Auxiliary tank; 03. Inner chamber; 04. Outer chamber; 05. Feed pipe; 06. Feed switch valve; 07. Air inlet pipe; 08. Stirring rod; 09. Stirring blade; 10. Drive motor; 11. Cleaning pipe; 12. Cleaning hole; 13. Steam nozzle; 14. Cooling nozzle; 15. First pressure relief port; 16. Second pressure relief port; 17. Waste liquid outlet; 18. First thermometer; 19. First pressure gauge; 20. Second thermometer; 21. Second pressure gauge; 22. First conveying passage 23. First delivery end; 24. First circulation pump; 25. First exchanger; 26. First low-temperature circuit; 27. First high-temperature circuit; 28. Second exchanger; 29. ​​Second low-temperature circuit; 30. Second high-temperature circuit; 31. Third exchanger; 32. Third low-temperature circuit; 33. Third high-temperature circuit; 34. First heater; 35. First compressor; 36. Fourth on-off valve; 37. First high-pressure cleaning main pipeline; 38. Second heater; 39. Second compressor; 40. Fifth on-off valve; 41. Second high-pressure cleaning main pipeline; 42. Second circulation pump; 43. Waste liquid purifier; 44. Second delivery passage; 45. Second delivery terminal; 46. Third circulation pump; 47. Second on-off valve; 48. Fourth exchanger; 49. Fourth low-temperature circuit; 50. Fourth high-temperature circuit; 51. Fifth exchanger; 52. Fifth low-temperature circuit; 53. Fifth high-temperature circuit; 54. Sixth exchanger; 55. Sixth low-temperature circuit; 56. Sixth high-temperature circuit; 57. Third heater; 58. Third compressor; 59. Sixth switch valve; 60. First high-pressure steam main pipeline; 61. Fourth heater; 62. Fourth compressor; 63. Seventh switch valve; 64. Second high-pressure steam main pipeline; 65. Fourth circulation pump; 66. First liquid storage tank; 67. Second liquid storage tank; 68. First switch valve; 69. First intersection point; 70. Second intersection point; 71. Third switch valve; 72. Eighth switch valve; 73. Ninth switch valve; 74. First waste heat recovery passage; 75. Second waste heat recovery passage; 76. Controller. DETAILED DESCRIPTION

[0075] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0076] The purpose of the embodiments of the present invention is to provide a waste plastic recycling melting and washing system and method, which can perform efficient plastic melting and washing processing under high pressure conditions and achieve precise management of temperature, pressure and medium flow through an intelligent control system.

[0077] In order to solve the above technical problems, Figure 1 As shown, the embodiment of the present application provides a waste plastic recycling melting and washing system, which specifically includes two parts, a reactor equipment part and a control part. The reactor equipment part includes: a main tank 01 and a sub-tank 02.

[0078] The main tank 01 is mainly used to hold waste plastics to be processed and to melt and wash the waste plastics to be processed. The main tank 01 includes an inner warehouse 03 and an outer warehouse 04. The waste plastics to be processed are held in the inner warehouse 03. The inner warehouse 03 is arranged in the outer warehouse 04. A plurality of prefabricated through holes are provided on the inner warehouse 03, and the inner warehouse 03 is connected with the outer warehouse 04 through the prefabricated through holes.

[0079] The auxiliary tank 02 is mainly used to receive the processed waste plastics and melt and wash them again, and at the same time collect and transfer the impurities washed out. At least one discharge pipe 05 is provided between the main tank 01 and the auxiliary tank 02. The main tank 01 and the auxiliary tank 02 are connected through the discharge pipe 05, and each discharge pipe 05 is provided with a discharge switch valve 06.

[0080] like Figure 2 As shown, a waste plastic recycling melting and washing system in an embodiment of the present application also includes: a first conveying passage 22 and a first waste heat recovery passage 74.

[0081] Furthermore, the first conveying passage 22 is formed by the first conveying end 23, which is connected to the first high-pressure cleaning main pipeline 37 in sequence through the first circulation pump 24, the first low-temperature circuit 26 of the first exchanger 25, the second low-temperature circuit 29 of the second exchanger 28, the third low-temperature circuit 32 of the third exchanger 31, the first heater 34 and the first compressor 35.

[0082] like Figure 1 As shown, a stirring rod 08 is mounted horizontally within inner bin 03. Multiple stirring blades 09 are positioned on stirring rod 08, facing the inner bin. These blades are arranged in multiple groups, with equal spacing between each group. A drive motor 10, via a coupling, drives inner bin 03 and stirring rod 08 to rotate together within inner bin 03. Inner bin 03 can rotate 360° within outer bin 04, facilitating the even rolling and flipping of waste plastics within inner bin 03, ensuring sufficient exposure to steam cleaning.

[0083] The stirring rod 08 and the stirring blade 09 are both hollow, and the inner cavity of the stirring rod 08 is connected to the inner cavity of the stirring blade. The stirring blade 09 is provided with multiple air injection holes. The stirring rod 08 passes through the closed door of the main tank 01 through the air intake pipe 07. The first high-pressure cleaning main pipe 37 is connected to the air intake pipe 07. In this way, the first high-pressure cleaning main pipe 37 is connected to the inner chamber 03 through the air intake pipe 07. The air intake pipe 07 is connected through the stirring rod 08 and the stirring blade 09.

[0084] like Figure 2 As shown, the first delivery end 23 is formed by the first liquid storage tank 66 connected to the second liquid storage tank 67 via the third circulation pump 46. In the embodiment of the present application, the first liquid storage tank 66 is a water storage tank, and the second liquid storage tank 67 is a liquid detergent / cleaning agent solution storage tank. In this way, through the combined action of the first circulation pump 24 and the third circulation pump 46, water and liquid detergent / cleaning agent solution are respectively delivered from the first liquid storage tank 66 and the second liquid storage tank 67, a mixed cleaning liquid can be obtained at the first delivery end 23. The ratio of the cleaning liquid can be controlled by adjusting the speed ratio of the first circulation pump 24 and the third circulation pump 46. The mixed cleaning liquid obtained at the first delivery end 23 is heated by the first heater 34 to meet the cleaning temperature requirement in the inner chamber 03, and then compressed by the first compressor 35 to meet the cleaning pressure requirement in the inner chamber 03.

[0085] Furthermore, the first waste heat recovery path 74 is formed by the first pressure relief port 15, which is connected in sequence to the third high-temperature circuit 33 of the third exchanger 31, the second high-temperature circuit 30 of the second exchanger 28, the first high-temperature circuit 27 of the first exchanger 25, and the second circulation pump 42 to the first input end of the waste liquid purifier 43.

[0086] In addition, the input ends of the first high-temperature circuit 27 and the second high-temperature circuit 30 are respectively connected to the waste liquid outlet 17 and the second pressure relief port 16; the first pressure relief port 15 and the second pressure relief port 16 are respectively arranged on the outer chamber 04 and the auxiliary tank 02, and the waste liquid outlet 17 is arranged at one end of the auxiliary tank 02 near the bottom.

[0087] As described above, in this embodiment of the present application, high-temperature, high-pressure cleaning gas is delivered to the inner chamber 03 via the first delivery passage 22 for high-temperature, high-pressure melting and cleaning of the waste plastics to be processed. Simultaneously, waste heat is recovered through the first waste heat recovery passage 74 from the first pressure relief port 15, the second pressure relief port 16, and the waste liquid outlet 17. When the pressure in the main tank 01 and the auxiliary tank 02 becomes excessive, the first and second pressure relief high-temperature gases are discharged from the first and second pressure relief ports 15, 16, respectively. The condensate and impurities removed from the auxiliary tank 02 are discharged from the waste liquid outlet 17. The temperature of the first pressure relief high-temperature gas discharged from the first pressure relief port 15 is higher than that of the second pressure relief high-temperature gas discharged from the second pressure relief port 16, and the temperature of the second pressure relief high-temperature gas is higher than that of the mixed liquid discharged from the waste liquid outlet 17. Thus, the first heat exchanger functions as a low-temperature heat exchanger, the second heat exchanger as a medium-temperature heat exchanger, and the third heat exchanger as a high-temperature heat exchanger. The above-described embodiment of the present application utilizes a three-stage heat exchanger to recover waste heat, improving energy efficiency and reducing energy consumption.

[0088] Further, combined with Figure 1 and Figure 2 The output end of the third low-temperature circuit 32 is connected to the second high-pressure cleaning main pipeline 41 through the second heater 38 and the second compressor 39. The second high-pressure cleaning main pipeline 41 is connected to the cleaning pipeline 11 in the auxiliary tank 02. A plurality of cleaning holes 12 are provided on the cleaning pipeline 11.

[0089] In this way, the mixed cleaning liquid obtained at the first conveying end 23 is transported to the auxiliary tank 02 through the second high-pressure cleaning main pipeline 41, and the transferred plastic is cleaned again in the auxiliary tank 02, and a second heater 38 and a second compressor 39 are arranged before the second high-pressure cleaning main pipeline 41. The second heater 38 can be set to a heating efficiency different from that of the first heater 34, and the second compressor 39 can also be set to a speed different from that of the first compressor 35, so as to meet the different cleaning temperature and cleaning pressure requirements in the auxiliary tank 02.

[0090] The output end of the waste liquid purifier 43 is connected to the input end of the first liquid storage tank 66 , so that a closed loop is formed between the first conveying passage 22 and the first waste heat recovery passage 74 .

[0091] like Figure 2 As shown, a waste plastic recycling melting and washing system disclosed in an embodiment of the present invention further includes: a second conveying passage 44 and a second waste heat recovery passage 75.

[0092] Furthermore, the second conveying passage 44 is formed by the second conveying end 45, which is connected to the first high-pressure steam main pipeline 60 in sequence through the third circulation pump 46, the fourth low-temperature circuit 49 of the fourth exchanger 48, the fifth low-temperature circuit 52 of the fifth exchanger 51, the sixth low-temperature circuit 55 of the sixth exchanger 54, the third heater 57 and the third compressor 58. The first high-pressure steam main pipeline 60 is connected to each steam nozzle 13 arranged on the outer warehouse 04.

[0093] Combine Figure 1 and Figure 2 The second delivery end 45 is directly formed by the output end of the first liquid storage tank 66. Thus, the third circulating pump 46 can deliver water from the first liquid storage tank 66 through the second delivery end 45, and then through the first high-pressure steam main pipeline 60 to the various steam nozzles 13 arranged on the outer chamber 04. Each steam nozzle 13 sprays high-temperature and high-pressure steam into the inner chamber 03. The drive motor 10 drives the inner chamber 03 to rotate, heating the inner chamber 03. The heating of the third heater 57 can meet the required injection heating temperature, and the third compressor 58 can meet the required injection pressure.

[0094] Furthermore, the second waste heat recovery passage 75 is formed by the first pressure relief port 15, which is connected to the second input end of the waste liquid purifier 43 in sequence through the sixth high-temperature circuit 56 of the sixth exchanger 54, the fifth high-temperature circuit 53 of the fifth exchanger 51, the fourth high-temperature circuit 50 of the fourth exchanger 48, and the fourth circulation pump 65.

[0095] In addition, the input ends of the fourth high-temperature circuit 50 and the fifth high-temperature circuit 53 are connected to the waste liquid outlet 17 and the second pressure relief port 16 , respectively.

[0096] As described above, in the embodiment of the present application, high-temperature, high-pressure cleaning gas is delivered to the inner chamber 03 via the first delivery passage 22 to melt and wash the waste plastics to be processed at high temperature and high pressure. When the drive motor 10 drives the inner chamber 03 to rotate, high-temperature, high-pressure steam is provided to each steam nozzle 13 via the second delivery passage 44 to spray and heat the inner chamber 03. At the same time, waste heat is recovered from the first pressure relief port 15, the second pressure relief port 16, and the waste liquid outlet 17 via the first waste heat recovery passage 74, and from the first pressure relief port 15, the second pressure relief port 16, and the waste liquid outlet 17 via the second waste heat recovery passage 75. When the pressure in the main tank 01 and the auxiliary tank 02 is too high, the first pressure relief high-temperature gas and the second pressure relief high-temperature gas are discharged from the first pressure relief port 15 and the second pressure relief port 16, respectively. The condensate in the auxiliary tank 02 and the cleaned impurities are discharged from the waste liquid outlet 17. The temperature of the first pressure-relief high-temperature gas discharged from the first pressure-relief port 15 is higher than the temperature of the second pressure-relief high-temperature gas discharged from the second pressure-relief port 16, and the temperature of the second pressure-relief high-temperature gas is higher than the temperature of the mixed liquid discharged from the waste liquid discharge port 17. Similarly, the fourth exchanger is equivalent to a low-temperature exchanger, the fifth exchanger is equivalent to a medium-temperature exchanger, and the sixth exchanger is equivalent to a high-temperature exchanger. The above embodiment of the present application corresponds to the second conveying passage 44 and recycles waste heat through a three-stage heat exchanger, thereby improving energy utilization efficiency and reducing energy consumption.

[0097] The output end of the sixth low-temperature circuit 55 is connected to the second high-pressure steam main pipeline 64 via the fourth heater 61 and the fourth compressor 62 . The second high-pressure steam main pipeline 64 is connected to each cooling nozzle 14 arranged on the outer compartment 04 .

[0098] In this way, the water output through the second delivery end 45 is transported to the third heater 57 through the second delivery passage 44, and cooling gas is generated through the third heater 57 and the third compressor 58. The cooling gas is then transported to each cooling nozzle 14 on the outer warehouse 04 through the second high-pressure steam main pipeline 64. When the temperature in the main tank 01 is too high, cooling gas is sprayed into the main tank 01, and a fourth heater 61 and a fourth compressor 62 are arranged before the second high-pressure steam main pipeline 64. The fourth heater 61 can be set to a heating efficiency different from that of the third heater 57, and the fourth compressor 62 can also be set to a speed different from that of the third compressor 58, so that the temperature and pressure requirements of the cooling gas can be met.

[0099] like Figure 2 As shown, a first switch valve 68 is provided between the second liquid storage tank 67 and the first circulation pump 24, a second switch valve 47 is provided between the third circulation pump 46 and the output end of the fourth low-temperature circuit 49, a first intersection point 69 is formed between the first switch valve 68 and the first circulation pump 24, a second intersection point 70 is formed between the third circulation pump 46 and the second switch valve 47, and a third switch valve 71 is provided between the first intersection point 69 and the second intersection point 70. In this way, by using the first switch valve 68, the second switch valve 47 and the third switch valve 71 in combination, the requirements of the first conveying path 22 and the second conveying path 44 can be met. For example, when the first switch valve 68 and the third switch valve 71 are turned on and the second switch valve 47 is turned off, the first conveying path 22 operates normally and the second conveying path 44 is turned off; when the first switch valve 68 and the third switch valve 71 are turned off and the second switch valve 47 is turned on, the first conveying path 22 is turned off and the second conveying path 44 operates normally; when the first switch valve 68 and the third switch valve 71 are turned on and the second switch valve 47 is turned on, the first conveying path 22 and the second conveying path 44 both operate normally.

[0100] The output ends of the first compressor 35, the second compressor 39, the third compressor 58, and the fourth compressor 62 are respectively provided with a fourth on-off valve 36, a fifth on-off valve 40, a sixth on-off valve 59, and a seventh on-off valve 63. The fourth on-off valve 36, the fifth on-off valve 40, the sixth on-off valve 59, and the seventh on-off valve 63 are respectively used to control the shutoff and conduction of the first high-pressure cleaning main pipeline 37, the second high-pressure cleaning main pipeline 41, the first high-pressure steam main pipeline 60, and the second high-pressure steam main pipeline 64.

[0101] refer to Figure 3The waste plastic recycling and washing system disclosed in an embodiment of the present invention further includes a controller 76. A first thermometer 18 and a first pressure gauge 19 are provided on the outer chamber 04, and a second thermometer 20 and a second pressure gauge 21 are provided on the auxiliary tank 02. The input end of the controller 76 is connected to the first thermometer 18, the first pressure gauge 19, the second thermometer 20, and the second pressure gauge 21.

[0102] The output end of the controller 76 is connected to the first heater 34, the second heater 38, the third heater 57, the fourth heater 61, the first circulation pump 24, the second circulation pump 42, the third circulation pump 46, the fourth circulation pump 65, the first switch valve 68, the second switch valve 47, the third switch valve 71, the fourth switch valve 36, the fifth switch valve 40, the sixth switch valve 59, and the seventh switch valve 63.

[0103] In addition, an eighth switch valve 72 and a ninth switch valve 73 are respectively provided at the first pressure relief port 15 and the second pressure relief port 16 , and an output end of the controller 76 is connected to the eighth switch valve 72 and the ninth switch valve 73 .

[0104] Conventional cleaning equipment is usually mechanically controlled, and the cleaning temperature and pressure are unstable, making it impossible to achieve precise cleaning of different types of plastics. In the embodiment of the present application, the controller 76 can intelligently control the cleaning temperature and pressure, effectively improving the automation level of the equipment.

[0105] refer to Figure 4 , further, the execution steps of the controller 76 are described in detail below.

[0106] First, the third circulation pump 46, the third compressor 58, and the third heater 57 are started, and the second on-off valve 47 and the sixth on-off valve 59 are closed. This opens the second delivery passage 44, and the first high-pressure steam is sprayed into the inner chamber 03 through the first high-pressure steam main pipeline 60 and the various steam nozzles 13. Then, the second circulation pump 42 and the fourth circulation pump 65 are started, and the first waste heat recovery passage 74 and the second waste heat recovery passage 75 are opened.

[0107] The first preset condition, the second preset condition, the third preset condition, the fourth preset condition, the fifth preset condition, the sixth preset condition, the seventh preset condition and the eighth preset condition are initialized and set.

[0108] The first temperature T11 and the first pressure P11 in the main tank 01 are detected according to a preset period and the corresponding first acquisition time t1 is recorded. In the embodiment of the present application, for example, the preset period can be 5ms; it is determined whether the first temperature T11 meets the first preset condition. The first preset condition is that the first temperature T11 is greater than or equal to the first preset temperature threshold and less than or equal to the second preset temperature threshold, and the second preset temperature threshold is greater than the first preset temperature threshold.

[0109] In the embodiment of the present application, the first temperature T11 and the first pressure P11 in the main tank 01 are adjusted to maintain in different set value ranges according to the thermal melting temperature of different plastics. Different types of plastics are thermally melted and shrunk at different temperatures and pressures and discharged from the discharge pipe 05, thereby sorting out different types of plastic materials in the plastic.

[0110] For example, when melting polyethylene, a first plastic material, the first preset temperature threshold is set to 120°C, and the second preset temperature threshold is set to 136°C. Thus, the first preset condition is that the first temperature T11 is greater than or equal to 120°C and less than or equal to 136°C. Maintaining the first temperature T11 within the main tank 01 at the first preset condition allows the polyethylene to melt and be separated from the waste plastic. If melting polyoxymethylene, a second plastic material, is required, the first preset temperature threshold is set to 165°C, and the second preset temperature threshold is set to 175°C. Thus, the first preset condition is that the first temperature T11 is greater than or equal to 165°C and less than or equal to 175°C. Maintaining the first temperature T11 within the main tank 01 at the first preset condition allows the polyoxymethylene to melt and be separated from the waste plastic.

[0111] If the first temperature T11 does not meet the first preset condition, it is determined whether the first temperature T11 meets the second preset condition. The second preset condition is that the first temperature T11 is greater than or equal to a third preset temperature threshold, and the third preset temperature threshold is greater than the second preset temperature threshold.

[0112] In an embodiment of the present application, corresponding to the first preset condition, the third preset temperature threshold of the second preset condition can be set 5°C higher than the second preset temperature threshold. As described above, when the second preset temperature threshold is set to 136°C, the third preset temperature threshold can be set to 141°C; when the second preset temperature threshold is set to 175°C, the third preset temperature threshold can be set to 180°C.

[0113] If the first temperature T11 satisfies the second preset condition, the fourth compressor 62 and the fourth heater 61 are activated according to the first preset time period, and the seventh on-off valve 63 is closed. Second high-pressure steam is sprayed into the inner chamber 03 through the second high-pressure steam main pipeline 64 and the cooling nozzles 14. The cycle continues until the first temperature T11 and the first pressure P11 in the main tank are detected in the next preset period, and the corresponding first collection time t1 is recorded. Furthermore, in this embodiment of the present application, the first preset time period may be 20 seconds.

[0114] If the first temperature T11 does not meet the second preset condition, based on the first preset temperature control function, obtain the first target control temperature T01 corresponding to the current first acquisition time t1; calculate the first temperature difference ΔT1 of the first temperature T11 minus the first target control temperature T01; and determine whether the absolute value of the first temperature difference ΔT1 is greater than or equal to the first preset temperature difference threshold.

[0115] In the embodiment of the present application, the first preset temperature difference threshold value can be greater than or equal to 3°C and less than or equal to 5°C. For the third heater 57, according to the empirical value of heating efficiency, the corresponding first temperature actual value in the main tank is collected based on multiple first heating time points to obtain a first sampling data pair. Based on each first sampling data pair (first heating time point and corresponding first temperature actual value), a first preset temperature control function is constructed. The formula of the first preset temperature control function is:

[0116] T01=K1·t1+b1

[0117] Wherein, K1 is the first temperature rise parameter, and b1 is the first temperature base value.

[0118] If the absolute value of the first temperature difference ΔT1 is greater than or equal to the first preset temperature difference threshold, the heating power of the third heater 57 is adjusted based on the first temperature difference ΔT1, and it is determined whether the first pressure P11 meets the third preset condition.

[0119] If the absolute value of the first temperature difference value ΔT1 is greater than or equal to the first preset temperature difference threshold, specifically, when the first temperature difference value ΔT1 is a positive value, the first temperature T11 is greater than the first target control temperature T01, and the heating power of the third heater 57 is lowered based on the absolute value of the first temperature difference value ΔT1; when the first temperature difference value ΔT1 is a negative value, the first temperature T11 is less than the first target control temperature T01, and the heating power of the third heater 57 is increased based on the absolute value of the first temperature difference value ΔT1.

[0120] If the absolute value of the first temperature difference ΔT1 is smaller than a first preset temperature difference threshold, or the first temperature T11 satisfies a first preset condition, it is directly determined whether the first pressure P11 satisfies a third preset condition.

[0121] The third preset condition is that the first pressure P11 is greater than or equal to the first preset pressure threshold and less than or equal to the second preset pressure threshold, and the second preset pressure threshold is greater than the first preset pressure threshold. In this embodiment of the present application, a third preset condition is provided corresponding to the first preset condition for the first pressure P11 in the main tank O1.

[0122] As described above, for example, when the first plastic material polyethylene needs to be melted, the above-mentioned first preset condition is that the first temperature T11 is greater than or equal to 120°C and less than or equal to 136°C. At this time, the first preset pressure threshold and the second preset pressure threshold of the third preset condition set corresponding to the first preset condition are 2.1 MPa and 2.9 MPa respectively, that is, the third preset condition is that the first pressure P11 is greater than or equal to 2.1 MPa and less than or equal to 2.9 MPa. The first temperature T11 in the main tank 01 is maintained at the above-mentioned first preset condition, and the first pressure P11 in the main tank 01 is maintained at the above-mentioned third preset condition, so that the polyethylene is melted and separated from the waste plastic. If it is necessary to melt the second plastic material polyformaldehyde, the above-mentioned first preset condition is that the first temperature T11 is greater than or equal to 165°C and less than or equal to 175°C. At this time, the first preset pressure threshold and the second preset pressure threshold of the third preset condition set corresponding to the first preset condition are 3.1 MPa and 3.5 MPa respectively. The first temperature T11 in the main tank 01 is maintained at the above-mentioned first preset condition, and the first pressure P11 in the main tank 01 is maintained at the above-mentioned third preset condition, so that the polyformaldehyde is melted and separated from the waste plastic.

[0123] refer to Figure 5 If the first pressure P11 does not meet the third preset condition, it is determined whether the first pressure P11 meets a fourth preset condition. The fourth preset condition is that the first pressure P11 is greater than or equal to a third preset pressure threshold, and the third preset pressure threshold is greater than the second preset pressure threshold.

[0124] In an embodiment of the present application, corresponding to the third preset condition, the third preset pressure threshold of the fourth preset condition can be set to 0.3 MPa greater than the second preset pressure threshold. As described above, when the second preset pressure threshold is set to 2.9 MPa, the third preset pressure threshold can be set to 3.2 MPa; when the second preset pressure threshold is set to 3.5 MPa, the third preset pressure threshold can be set to 3.8 MPa.

[0125] If the first pressure P11 satisfies the fourth preset condition, the second and fourth circulation pumps are activated and the first pressure relief port is opened for a second preset period. The process continues until the first temperature T11 and first pressure P11 in the main tank are detected for the next preset period, and the corresponding first collection time t1 is recorded. Furthermore, in this embodiment of the present application, the second preset period may also be 20 seconds.

[0126] If the first pressure P11 does not meet the fourth preset condition, then based on the first preset pressure control function, obtain the first target control pressure P01 corresponding to the current first acquisition time t1; calculate the first pressure difference value ΔP1 of the first pressure P11 minus the first target control pressure P01; and determine whether the absolute value of the first pressure difference value ΔP1 is greater than or equal to the first preset pressure difference threshold.

[0127] In the embodiment of the present application, the first preset pressure difference threshold value can be greater than or equal to 0.03 MPa and less than or equal to 0.05 MPa. For the third compressor 58, according to the empirical value of the speed, the corresponding first pressure actual value in the main tank is collected based on multiple first heating time points to obtain a second sampling data pair. Based on each second sampling data pair (first heating time point and corresponding first pressure actual value), a first preset pressure control function is constructed. The formula of the first preset pressure control function is:

[0128] P01=K2·t1+b2

[0129] Wherein, K2 is the first pressure increase parameter, and b1 is the first pressure base value.

[0130] If the absolute value of the first pressure difference value ΔP1 is greater than or equal to the first preset pressure difference threshold, the speed of the third compressor 58 and the third circulation pump 46 is adjusted based on the first pressure difference value ΔP1, and the cycle is continued to detect the first temperature T11 and the first pressure P11 in the main tank 01 in the next preset period and record the corresponding first collection time t1.

[0131] If the absolute value of the first pressure difference value ΔP1 is greater than or equal to the first preset pressure difference threshold, specifically, when the first pressure difference value ΔP1 is a positive value, the first pressure P11 is greater than the first target control pressure P01, and at this time, the speeds of the third compressor 58 and the third circulation pump 46 are reduced based on the absolute value of the first pressure difference value ΔP1; when the first pressure difference value ΔP1 is a negative value, the first pressure P11 is less than the first target control pressure P01, and at this time, the speeds of the third compressor 58 and the third circulation pump 46 are increased based on the absolute value of the first pressure difference value ΔP1.

[0132] If the absolute value of the first pressure difference ΔP1 is less than the first preset pressure difference threshold, the process directly cycles to detecting the first temperature T11 and the first pressure P11 in the main tank 01 in the next preset period and records the corresponding first collection time t1.

[0133] If the first pressure P11 meets the third preset condition, the first circulation pump 24, the first compressor 35 and the first heater 34 are started and the first switch valve 68, the third switch valve 71 and the fourth switch valve 36 are connected, the first conveying passage 22 is opened, and the first cleaning steam is delivered to the inner chamber 03 through the first high-pressure cleaning main pipeline 37 and the air intake pipe 07, and it is determined whether the first collection time t1 meets the fifth preset condition.

[0134] In the embodiment of the present application, the fifth preset condition is that the first acquisition time t1 is greater than or equal to a first preset time threshold. For example, the first preset time threshold may be 15 minutes.

[0135] refer to Figure 6 If the first collection time t1 does not meet the fifth preset condition, the process loops to detect the first temperature T11 and the first pressure P11 in the main tank 01 in the next preset period and records the corresponding first collection time t1.

[0136] If the first acquisition time t1 satisfies the fifth preset condition, it is determined whether the first acquisition time t1 satisfies the sixth preset condition.

[0137] In the embodiment of the present application, the sixth preset condition is that the first acquisition time t1 is greater than or equal to a second preset time threshold. For example, the second preset time threshold may be 20 minutes.

[0138] If the first collection time t1 does not meet the sixth preset condition, the second compressor 39 and the second heater 38 are started and the fifth switch valve 40 is turned on to deliver the second cleaning steam to the auxiliary tank 02 through the second high-pressure cleaning main pipeline 41 and the cleaning pipeline 11.

[0139] The second temperature T12 and the second pressure P12 in the auxiliary tank are detected according to a preset period and the corresponding second collection time t2 is recorded; and it is determined whether the second temperature T12 meets a seventh preset condition. The seventh preset condition is that the second temperature T12 is greater than or equal to the fourth preset temperature threshold and less than or equal to the fifth preset temperature threshold, and the fifth preset temperature threshold is greater than the fourth preset temperature threshold.

[0140] In the embodiment of the present application, the seventh preset condition needs to be set accordingly based on the first preset condition. As described above, for example, when the first plastic material, polyethylene, needs to be melted, the first preset condition is that the first temperature T11 is greater than or equal to 120°C and less than or equal to 136°C. At this time, the fourth preset temperature threshold and the fifth preset temperature threshold of the seventh preset condition set corresponding to the first preset condition are 40°C and 55°C, respectively. That is, the seventh preset condition is that the second temperature T12 is greater than or equal to 40°C and less than or equal to 55°C. The second temperature T12 in the auxiliary tank 02 is maintained at the seventh preset condition, so that the polyethylene is transferred to the auxiliary tank 02. If it is necessary to melt the second plastic material polyformaldehyde, the above-mentioned first preset condition is that the first temperature T11 is greater than or equal to 165°C and less than or equal to 175°C. At this time, the fourth preset temperature threshold and the fifth preset temperature threshold of the seventh preset condition set corresponding to the first preset condition are 60°C and 75°C respectively, that is, the seventh preset condition is that the second temperature T12 is greater than or equal to 60°C and less than or equal to 75°C. The second temperature T12 in the auxiliary tank 02 is maintained under the above-mentioned seventh preset condition to transfer the polyformaldehyde to the auxiliary tank 02.

[0141] If the second temperature T12 does not meet the seventh preset condition, then based on the second preset temperature control function, obtain the second target control temperature T02 corresponding to the current second acquisition time t2; calculate the second temperature difference ΔT2 by subtracting the second target control temperature T02 from the second temperature T12; and determine whether the absolute value of the second temperature difference ΔT2 is greater than or equal to the second preset temperature difference threshold.

[0142] In the embodiment of the present application, the second preset temperature difference threshold value can also be greater than or equal to 3°C and less than or equal to 5°C. For the second heater 38, according to the empirical value of the heating efficiency, the corresponding second temperature actual value in the main tank 01 is collected based on multiple second heating time points to obtain a third sampling data pair. Based on each third sampling data pair (second heating time point and corresponding second temperature actual value), a second preset temperature control function is constructed. The formula of the second preset temperature control function is:

[0143] T02=K3·t2+b3

[0144] Wherein, K3 is the second temperature rise parameter, and b3 is the second temperature base value.

[0145] If the absolute value of the second temperature difference ΔT2 is greater than or equal to the second preset temperature difference threshold, the heating power of the second heater 38 is adjusted based on the second temperature difference ΔT2, and it is determined whether the second pressure P12 meets the eighth preset condition.

[0146] If the absolute value of the second temperature difference value ΔT2 is greater than or equal to the second preset temperature difference threshold, specifically, when the second temperature difference value ΔT2 is a positive value, the second temperature T12 is greater than the second target control temperature T02, and the heating power of the second heater 38 is lowered based on the absolute value of the second temperature difference value ΔT2; when the second temperature difference value ΔT2 is a negative value, the second temperature T12 is less than the second target control temperature T02, and the heating power of the second heater 38 is increased based on the absolute value of the second temperature difference value ΔT2.

[0147] If the absolute value of the second temperature difference ΔT2 is smaller than the second preset temperature difference threshold, or the second temperature T12 satisfies the seventh preset condition, it is directly determined whether the second pressure P12 satisfies the eighth preset condition.

[0148] In the embodiment of the present application, the eighth preset condition is that the second pressure P12 is greater than or equal to a fourth preset pressure threshold. For example, the fourth preset pressure threshold can be set to 4.5 MPa.

[0149] If the second pressure P12 meets the eighth preset condition, the second pressure relief port is opened according to the second preset time period, and the process cycles to detect the first temperature T11 and the first pressure P11 in the main tank 01 in the next preset period and records the corresponding first collection time t1.

[0150] If the second pressure P12 does not meet the eighth preset condition, the process loops to detect the first temperature T11 and the first pressure P11 in the main tank 01 in the next preset period and records the corresponding first collection time t1.

[0151] refer to Figure 6 If the first collection time t1 satisfies the sixth preset condition, the first preset condition, the second preset condition, the third preset condition, the fourth preset condition, and the seventh preset condition are updated according to the preset rule; then the first collection time t1 is updated to 0 and the process loops to detect the first temperature T11 and the first pressure P11 in the main tank in the next preset cycle.

[0152] The embodiment of the present application provides a waste plastic recycling melting and washing system and method, which uses a main tank to process the waste plastic and transfer it to a sub-tank under the action of high-temperature and high-pressure steam melting and washing. The inner bin is set in the outer bin to form a main tank. The inner bin is driven to rotate in the outer bin, and the generated cleaning steam is directly introduced into the inner bin to clean the impurities on the waste plastic. At the same time, a plurality of prefabricated through holes are provided on the inner bin, and the generated high-pressure steam is used to spray and heat the inner bin, which greatly improves the melting and washing efficiency. In addition, on the first conveying path and the first waste heat recovery path, the waste heat is recycled by setting a first exchanger, a second exchanger, and a third exchanger, thereby improving energy utilization efficiency and reducing energy consumption. At the same time, the cleaning temperature and pressure can be intelligently controlled by the controller, which effectively solves the problem of being unable to achieve efficient energy saving and accurate cleaning of different types of plastics due to unstable cleaning temperature and pressure.

[0153] The technical features of the above embodiments can be combined arbitrarily as long as there is no contradiction in the combination of these technical features. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A waste plastic recycling melting and washing system, characterized in that: The system comprises: A main tank and a subsidiary tank, wherein the main tank includes an outer bin and an inner bin, the inner bin is sleeved in the outer bin and rotated in the outer bin by a drive, the inner bin is provided with a plurality of prefabricated through holes, and the main tank and the subsidiary tank are connected through a feed pipe; A first delivery path is formed by a first delivery end connected to a first high-pressure cleaning main pipeline in sequence through a first circulation pump, a first low-temperature circuit of a first exchanger, a second low-temperature circuit of a second exchanger, a third low-temperature circuit of a third exchanger, a first heater, and a first compressor, the first high-pressure cleaning main pipeline being connected to an air intake pipe communicating with the inner chamber, an output end of the third low-temperature circuit being connected to a second high-pressure cleaning main pipeline via a second heater and a second compressor, and the second high-pressure cleaning main pipeline being connected to a cleaning pipeline in the auxiliary tank; A first waste heat recovery path is formed by the first pressure relief port, sequentially passing through the third high-temperature circuit of the third exchanger, the second high-temperature circuit of the second exchanger, the first high-temperature circuit of the first exchanger, and the second circulation pump to connect to the first input end of the waste liquid purifier; a second delivery path formed by the second delivery end being connected to the first high-pressure steam main pipeline in sequence through the third circulation pump, the fourth low-temperature circuit of the fourth exchanger, the fifth low-temperature circuit of the fifth exchanger, the sixth low-temperature circuit of the sixth exchanger, the third heater, and the third compressor, wherein the first high-pressure steam main pipeline is connected to each steam nozzle arranged on the outer chamber; A second waste heat recovery path is formed by the first pressure relief port, sequentially passing through the sixth high-temperature circuit of the sixth exchanger, the fifth high-temperature circuit of the fifth exchanger, the fourth high-temperature circuit of the fourth exchanger, and the fourth circulation pump to connect to the second input end of the waste liquid purifier; The input ends of the first high-temperature circuit and the second high-temperature circuit are connected to the waste liquid outlet and the second pressure relief port, respectively; the first pressure relief port and the second pressure relief port are respectively provided on the outer chamber and the auxiliary tank, and the waste liquid outlet is provided at one end of the auxiliary tank near the bottom; the input ends of the fourth high-temperature circuit and the fifth high-temperature circuit are connected to the waste liquid outlet and the second pressure relief port, respectively; The first delivery end is formed by the first liquid storage tank connecting with the second liquid storage tank via the third circulation pump, the second delivery end is directly formed by the output end of the first liquid storage tank, and the output end of the waste liquid purifier is connected to the input end of the first liquid storage tank.

2. A waste plastic recycling melting and washing system according to claim 1, characterized in that: The output end of the sixth low-temperature circuit is connected to the second high-pressure steam main pipeline via the fourth heater and the fourth compressor, and the second high-pressure steam main pipeline is connected to the various cooling nozzles arranged on the outer warehouse.

3. A waste plastic recycling melting and washing system according to claim 2, characterized in that: A first switch valve is arranged between the second liquid storage tank and the first circulation pump, a second switch valve is arranged between the third circulation pump and the output end of the fourth low-temperature circuit, a first intersection point is formed between the first switch valve and the first circulation pump, a second intersection point is formed between the third circulation pump and the second switch valve, a third switch valve is arranged between the first intersection point and the second intersection point, and a fourth switch valve, a fifth switch valve, a sixth switch valve and a seventh switch valve are respectively arranged at the output end of the first compressor, the output end of the second compressor, the output end of the third compressor and the output end of the fourth compressor.

4. A method for recycling and melting waste plastics, characterized in that: The method comprises: The inner bin is placed inside the outer bin to form a main tank, and the main tank is connected to the auxiliary tank through a feed pipe. The inner bin is driven to rotate inside the outer bin, and a plurality of prefabricated through holes are provided on the inner bin; A first delivery path is formed by connecting the first delivery end to the first high-pressure cleaning main pipeline in sequence through the first circulation pump, the first low-temperature circuit of the first exchanger, the second low-temperature circuit of the second exchanger, the third low-temperature circuit of the third exchanger, the first heater, and the first compressor. The first high-pressure cleaning main pipeline is connected to the air intake pipe communicating with the inner chamber. The output end of the third low-temperature circuit is connected to the second high-pressure cleaning main pipeline through the second heater and the second compressor. The second high-pressure cleaning main pipeline is connected to the cleaning pipeline in the auxiliary tank. A first waste heat recovery path is formed by connecting the first pressure relief port to the first input end of the waste liquid purifier through the third high-temperature circuit of the third exchanger, the second high-temperature circuit of the second exchanger, the first high-temperature circuit of the first exchanger, and the second circulation pump in sequence; The second delivery end is connected to the first high-pressure steam main pipeline through the third circulation pump, the fourth low-temperature circuit of the fourth exchanger, the fifth low-temperature circuit of the fifth exchanger, the sixth low-temperature circuit of the sixth exchanger, the third heater and the third compressor in sequence to form a second delivery path. The first high-pressure steam main pipeline is connected to each steam nozzle arranged on the outer chamber. A second waste heat recovery path is formed by connecting the first pressure relief port to the second input end of the waste liquid purifier through the sixth high-temperature circuit of the sixth exchanger, the fifth high-temperature circuit of the fifth exchanger, the fourth high-temperature circuit of the fourth exchanger, and the fourth circulation pump in sequence; The input ends of the first high-temperature circuit and the second high-temperature circuit are connected to the waste liquid outlet and the second pressure relief port, respectively; the first pressure relief port and the second pressure relief port are respectively provided on the outer chamber and the auxiliary tank, and the waste liquid outlet is provided at one end of the auxiliary tank near the bottom; the input ends of the fourth high-temperature circuit and the fifth high-temperature circuit are connected to the waste liquid outlet and the second pressure relief port, respectively; The first delivery end is formed by the first liquid storage tank connecting with the second liquid storage tank via the third circulation pump, the second delivery end is directly formed by the output end of the first liquid storage tank, and the output end of the waste liquid purifier is connected to the input end of the first liquid storage tank.

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