A waste plastic pyrolysis dechlorination device

Abstract

The utility model discloses a kind of waste plastics pyrolysis dechlorination devices, belong to waste plastics thermal cracking dechlorination technical field, including cracking furnace, cracking furnace is connected with high-temperature fan by first cracking gas delivery pipeline, the output end of high-temperature fan is connected with first condenser, the gas output end of first condenser is connected with high-temperature membrane dust collector, the liquid output end of first condenser is connected with hydrocarbon storage tank, high-temperature membrane dust collector is connected with filter chamber, filter chamber is connected with dechlorination tower, dechlorination tower is equipped with deionized water;Gas outlet is equipped on dechlorination tower, gas outlet is connected with lye tower, outlet is equipped on dechlorination tower, outlet is connected with hydrochloric acid purification device;The utility model high-temperature fan promptly extracts the hydrogen chloride generated by cracking, reduces the contact time of hydrogen chloride and cracking furnace, water in dechlorination tower is recovered to hydrogen chloride, remaining cracking gas is discharged into lye washing tower and is absorbed, reduce environmental pollution.

Description

Technical Field

[0001] This utility model relates to the field of waste plastic thermal cracking dechlorination technology, specifically to a waste plastic pyrolysis dechlorination device. Background Technology

[0002] Currently, there are three main methods for treating plastic waste: landfill, incineration, and recycling. Landfill and incineration cause serious environmental pollution and waste a large amount of land and energy. High-value recycling has become a hot topic in recent years. High-value recycling can be divided into energy recovery, mechanical recovery, and chemical recovery. Chemical recycling refers to the method of breaking down waste plastics into small molecules or monomers, and then using these small molecules to prepare fuel oil, chemicals, etc. This method can transform waste plastics into higher-value products and can also process mixed and polluted low-end waste plastics, making it a focus of research in various fields in recent years. Among these methods, the pyrolysis of plastics is the core technology of chemical recycling.

[0003] During the pyrolysis process, chlorinated waste plastics produce toxic or corrosive gases such as hydrogen chloride, which not only corrode the oil refinery furnace but also directly impact the environment if discharged directly. Patent CN208151289U describes a novel plastic oil refinery furnace in which a dechlorinating agent is added along with the waste plastic. During pyrolysis, the hydrogen chloride produced is absorbed. While this device addresses the corrosion problem of the refinery furnace to some extent, it does not effectively utilize the hydrogen chloride. Summary of the Invention

[0004] To address the problems existing in the prior art, this utility model provides a waste plastic pyrolysis and dechlorination device, which uses a condenser and filter to treat hydrocarbons and dust in the pyrolysis gas, improves the purity of hydrogen chloride in the pyrolysis gas, and recovers hydrogen chloride using water in the dechlorination tower.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: This utility model provides a waste plastic pyrolysis and dechlorination device, including a pyrolysis furnace. The pyrolysis furnace is connected to a high-temperature fan via a first pyrolysis gas conveying pipeline. The output end of the high-temperature fan is connected to a first condenser. The gas output end of the first condenser is connected to a high-temperature membrane dust collector. The liquid output end of the first condenser is connected to a hydrocarbon storage tank. The high-temperature membrane dust collector is connected to a filter chamber. The filter chamber is connected to a dechlorination tower, which is filled with deionized water. The dechlorination tower has a gas outlet, which is connected to an alkali tower. The dechlorination tower also has a liquid outlet, which is connected to a hydrochloric acid purification device.

[0006] As a preferred technical solution, the dechlorination tower is equipped with a pH sensor, which is connected to a PLC.

[0007] As a preferred technical solution, the dechlorination tower is connected to the filtration chamber via a second pyrolysis gas delivery pipe, one end of which extends below the liquid surface of the dechlorination tower.

[0008] As a preferred technical solution, the dechlorination tower is provided with a water inlet and a motor at the top. The output end of the motor is connected to a rotating shaft, which is vertically arranged. The lower end of the rotating shaft extends into the dechlorination tower, and several stirring rods are provided on the rotating shaft.

[0009] As a preferred technical solution, the first condenser is connected to the high-temperature membrane dust collector through a third pyrolysis gas delivery pipeline, and a temperature sensor is provided on the third pyrolysis gas delivery pipeline.

[0010] As a preferred technical solution, the third cracked gas conveying pipeline is provided with a first three-way valve, which is located between the temperature sensor and the high-temperature membrane dust collector. One output end of the first three-way valve is connected to a second condenser, the gas outlet of the second condenser is connected to the input end of the high-temperature membrane dust collector, and the liquid outlet of the second condenser is connected to the hydrocarbon storage tank.

[0011] As a preferred technical solution, the PLC is electrically connected to the temperature sensor.

[0012] As a preferred technical solution, the filter chamber is equipped with an activated carbon adsorption layer, which is placed horizontally, and the pyrolysis gas passes through the filter chamber from bottom to top.

[0013] As a preferred technical solution, a high-temperature steam pipe is connected to the top of the filter chamber, and a light hydrocarbon storage tank is connected to the bottom of the filter chamber.

[0014] The beneficial effects of this utility model are as follows: 1. This utility model utilizes a high-temperature fan to promptly extract the hydrogen chloride produced by pyrolysis, reducing the contact time between hydrogen chloride and the pyrolysis furnace. The first condenser condenses the pyrolysis gas, liquefies and separates heavy hydrocarbon components, and then a high-temperature membrane dust collector separates the dust in the pyrolysis gas. The filter chamber adsorbs light hydrocarbon components, and the water in the dechlorination tower absorbs hydrogen chloride to recover hydrogen chloride. The remaining pyrolysis gas is discharged into the alkaline washing tower for absorption, reducing environmental pollution. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a waste plastic pyrolysis and dechlorination device according to the present invention; Figure 2 This is a schematic diagram of the filter chamber and dechlorination tower in a waste plastic pyrolysis and dechlorination device of this utility model.

[0016] In the diagram: 1-Cracking furnace, 2-First cracked gas conveying pipeline, 3-High temperature fan, 4-First condenser, 5-High temperature membrane dust collector, 6-Filter chamber, 7-Dechlorination tower, 8-Alkali tower, 9-Hydrochloric acid purification device, 10-Second cracked gas conveying pipeline, 11-Third cracked gas conveying pipeline, 12-Temperature sensor, 13-First three-way valve, 14-Second condenser, 15-Activated carbon adsorption layer, 16-Water inlet, 17-Motor, 18-Shaft, 19-Stirring rod, 20-Hydrocarbon storage tank, 21-Light hydrocarbon storage tank, 22-High temperature steam pipe. Detailed Implementation

[0017] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0018] Please refer to Figures 1-2 This invention provides a waste plastic pyrolysis and dechlorination device, including a pyrolysis furnace 1. The pyrolysis furnace 1 is connected to a high-temperature fan 3 via a first pyrolysis gas delivery pipe 2. The high-temperature fan 3 promptly extracts the hydrogen chloride produced by pyrolysis, reducing the residence time of hydrogen chloride in the pyrolysis furnace 1, while simultaneously promoting the pyrolysis reaction and maintaining the pressure inside the pyrolysis furnace 1 at 0-1 kPa. The output end of the high-temperature fan 3 is connected to a first condenser 4. The gas output end of the first condenser 4 is connected to a high-temperature membrane dust collector 5, and the liquid output end of the first condenser 4 is connected to a hydrocarbon storage tank 20. The first condenser 4 condenses the output high-temperature pyrolysis gas, causing heavy hydrocarbons in the pyrolysis gas to condense and separate from the pyrolysis gas, which are then stored in the hydrocarbon storage tank 20. This prevents the pyrolysis gas from directly entering the high-temperature membrane dust collector 5, where heavy hydrocarbons would adhere to the membrane surface and cause blockage. The high-temperature membrane dust collector 5 thoroughly removes dust from the pyrolysis gas and is connected to a filter chamber 6. The filter chamber 6 contains an activated carbon adsorption layer 15, which is placed horizontally. The pyrolysis gas passes through the filter chamber 6 from bottom to top. The activated carbon adsorbs light hydrocarbon components (such as propylene and propane) in the pyrolysis gas, further purifying it. The filter chamber 6 is connected to a dechlorination tower 7, which contains deionized water. The deionized water in the dechlorination tower 7 absorbs hydrogen chloride to obtain crude hydrochloric acid. The dechlorination tower 7 has a gas outlet connected to an alkali tower 8, which absorbs residual acidic gases, preventing direct discharge and environmental impact. The dechlorination tower 7 also has a liquid outlet connected to a hydrochloric acid purification device 9, which is used to purify the crude hydrochloric acid. Conventional equipment in this field can be used, and will not be described in detail here.

[0019] In this embodiment, please refer to Figure 1 and Figure 2The dechlorination tower 7 is equipped with a pH sensor (not shown in the figure). The pH sensor monitors the acid value in the dechlorination tower 7 in real time to confirm the concentration of hydrogen chloride in the water. It can promptly discharge the solution in the dechlorination tower 7 to the hydrochloric acid purification device 9 for purification and replace the deionized water in the dechlorination tower 7 with fresh water. The pH sensor is connected to a PLC. The top of the dechlorination tower 7 is equipped with a water inlet 16 and a motor 17. Deionized water is supplied to the dechlorination tower 7 through the water inlet 16. The output end of the motor 17 is connected to a rotating shaft 18. The lower end of the rotating shaft 18 extends into the dechlorination tower 7, and several stirring rods 19 are provided on the rotating shaft 18. The motor 17 can drive the stirring rods 19 on the rotating shaft 18 to rotate, promoting the absorption of hydrogen chloride. The dechlorination tower 7 is connected to the filter chamber 6 through a second cracked gas conveying pipe 10. One end of the second cracked gas conveying pipe 10 extends below the liquid surface of the dechlorination tower 7, and hydrogen chloride is directly introduced into the water. The top of the filter chamber 6 is connected to a high-temperature steam pipe 22, and the bottom of the filter chamber 6 is connected to a light hydrocarbon storage tank 21. High-temperature and high-pressure steam is introduced into the filter chamber 6 through the high-temperature steam pipe 22 to desorb the light hydrocarbon components in the pores of the activated carbon. The light hydrocarbon components are then stored in the light hydrocarbon storage tank 21.

[0020] It should be noted that during the pyrolysis gas treatment process, the system is under a slightly positive pressure condition, ranging from 0.1 to 1 kPa (excluding pyrolysis furnace 1). The first condenser 4 and the high-temperature membrane dust collector 5 are connected via a third pyrolysis gas delivery pipeline 11. A temperature sensor 12 is installed on the third pyrolysis gas delivery pipeline 11 to monitor the temperature of the pyrolysis gas. The PLC is electrically connected to the temperature sensor 12. Preferably, the temperature of the pyrolysis gas after condensation by the first condenser 4 is controlled to be no higher than 60°C, so that the heavy hydrocarbon gases in the pyrolysis gas are condensed and separated. The temperature sensor 12 is a corrosion-resistant temperature sensor.

[0021] In this embodiment, please refer to Figure 1 The third cracked gas conveying pipeline 11 is equipped with a first three-way valve 13, one output end of which is connected to a second condenser 14. The gas outlet of the second condenser 14 is connected to the input end of the high-temperature membrane dust collector 5, and the liquid outlet of the second condenser 14 is connected to the hydrocarbon storage tank 20. When the condensation effect of the first condenser 4 decreases and the temperature sensor 12 shows a temperature greater than 60°C, the cracked gas output from the first condenser 4 needs to be re-input into the second condenser 14 for further condensation to improve the condensation effect. Cracking gas pressure gauges (not shown in the figure) are installed on the first cracked gas conveying pipeline 2, the second cracked gas conveying pipeline 10, and the third cracked gas conveying pipeline 11 to monitor the pipeline pressure. Each pipeline is equipped with a switch valve.

[0022] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A waste plastic pyrolysis and dechlorination device, characterized in that, The system includes a pyrolysis furnace (1), which is connected to a high-temperature fan (3) via a first pyrolysis gas delivery pipeline (2). The output end of the high-temperature fan (3) is connected to a first condenser (4). The gas output end of the first condenser (4) is connected to a high-temperature membrane dust collector (5). The liquid output end of the first condenser (4) is connected to a hydrocarbon storage tank (20). The high-temperature membrane dust collector (5) is connected to a filter chamber (6). The filter chamber (6) is connected to a dechlorination tower (7). The dechlorination tower (7) is filled with deionized water. The dechlorination tower (7) is provided with a gas outlet, which is connected to an alkali tower (8). The dechlorination tower (7) is provided with a liquid outlet, which is connected to a hydrochloric acid purification device (9).

2. The waste plastic pyrolysis and dechlorination device according to claim 1, characterized in that, The dechlorination tower (7) is equipped with a pH sensor, which is connected to a PLC.

3. The waste plastic pyrolysis and dechlorination device according to claim 1, characterized in that, The dechlorination tower (7) is connected to the filter chamber (6) through a second cracked gas delivery pipe (10), one end of which extends below the liquid surface of the dechlorination tower (7).

4. The waste plastic pyrolysis and dechlorination device according to claim 1, characterized in that, The dechlorination tower (7) is provided with an inlet (16) and a motor (17) at the top. The output end of the motor (17) is connected to a rotating shaft (18). The rotating shaft (18) is vertically arranged, and the lower end of the rotating shaft (18) extends into the dechlorination tower (7). Several stirring rods (19) are provided on the rotating shaft (18).

5. The waste plastic pyrolysis and dechlorination device according to claim 2, characterized in that, The first condenser (4) is connected to the high-temperature membrane dust collector (5) through a third pyrolysis gas delivery pipe (11), and a temperature sensor (12) is provided on the third pyrolysis gas delivery pipe (11).

6. The waste plastic pyrolysis and dechlorination device according to claim 5, characterized in that, The third cracked gas delivery pipeline (11) is provided with a first three-way valve (13). The first three-way valve (13) is located between the temperature sensor (12) and the high-temperature membrane dust collector (5). One output end of the first three-way valve (13) is connected to a second condenser (14). The gas outlet end of the second condenser (14) is connected to the input end of the high-temperature membrane dust collector (5). The liquid outlet end of the second condenser (14) is connected to the hydrocarbon storage tank (20).

7. The waste plastic pyrolysis and dechlorination device according to claim 5, characterized in that, The PLC is electrically connected to the temperature sensor (12).

8. The waste plastic pyrolysis and dechlorination device according to claim 1, characterized in that, The filter chamber (6) is filled with an activated carbon adsorption layer (15), which is placed horizontally, and the pyrolysis gas passes through the filter chamber (6) from bottom to top.

9. The waste plastic pyrolysis and dechlorination device according to claim 8, characterized in that, The top of the filter chamber (6) is connected to a high-temperature steam pipe (22), and the bottom of the filter chamber (6) is connected to a light hydrocarbon storage tank (21).

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