Waste plastic pyrolysis system

Abstract

A waste plastic pyrolysis system includes a controller; a feeder controlled by the controller to convey waste plastic to a higher position; a pyrolysis furnace with a pyrolysis chamber inside its metal furnace body, a high-frequency wire wound around the surface of the furnace wall, and an inlet for receiving the waste plastic and an exhaust outlet above the pyrolysis chamber; a frequency converter electrically connected to both ends of the high-frequency wire to rectify and convert industrial frequency AC voltage into high-frequency AC voltage, which is then output to the high-frequency wire to magnetically cut the furnace wall and generate eddy current heating; a temperature detector to detect the heating temperature of the pyrolysis chamber and feed it back to the controller; and a heating controller of an auxiliary heating device electrically connected to the controller to control multiple heating rods and one or more heating plates to heat the central area of ​​the upper and lower parts of the pyrolysis chamber. The entire system achieves uniform heating and control of the waste plastic pyrolysis temperature by using the multiple heating rods and one or more heating plates to assist the eddy current heating of the furnace wall via the high-frequency wire.

Claims

1. A waste plastic pyrolysis system, wherein waste plastic is first pyrolyzed to generate pyrolysis fumes, and then the pyrolysis fumes are processed through an oil recovery system to produce fuel oil and gas for recovery; the pyrolysis system comprises: A controller, powered by a power supply; a feeder, electrically connected to the controller, for receiving the waste plastic from an incoming end, controlled by the controller to convey the waste plastic to an upward end, the upward end having a discharge port; a pyrolysis furnace, a metal furnace body, having a pyrolysis chamber inside, the furnace wall of the body covered with a high-temperature resistant and insulating coating layer, on the outer surface of the coating layer having a high-frequency wire spirally wound; the pyrolysis chamber has a feed inlet and a flue gas outlet above it, and a slag outlet below it; the feed inlet is connected to the discharge port, so that the waste plastic falling from the discharge port can enter the pyrolysis chamber through the feed inlet; A frequency converter is electrically connected to both ends of the high-frequency conductor and serves as a receiving end of a control signal output from the controller. It is used to connect to the power output from the power supply, rectify the industrial frequency AC power into DC voltage, and then convert the DC voltage into a high-frequency AC voltage with a frequency of 20 to 40 kHz, which is output to the high-frequency conductor. The magnetic lines of force formed by the high-speed changing magnetic field inside the high-frequency conductor cut the furnace wall of the pyrolysis furnace body to generate eddy current heating. The heat energy of the furnace wall can heat the waste plastic in the pyrolysis chamber to form oil fumes that are discharged from the exhaust port. A stirrer is installed above the pyrolysis furnace and has a stirring motor electrically connected to the controller. It also has a rotating shaft driven by the stirring motor and extending into the pyrolysis chamber. The rotating shaft is equipped with a stirrer that can stir the waste plastic in the pyrolysis chamber. An auxiliary heating device is provided, which is electrically connected to multiple heating rods and one or more heating plates via a heating controller. The heating controller serves as a receiver for the control signal output of the controller, and is used to connect to the power output of the power supply to control the heating execution and heating power of the multiple heating rods and one or more heating plates. The multiple heating rods are located in the upper part of the pyrolysis chamber near the central area, distributed around the rotating shaft of the mixer. The one or more heating plates are arranged on the outer surface of the bottom of the pyrolysis furnace body, which can heat the bottom of the furnace body, so that the central area of ​​the bottom of the pyrolysis chamber can receive radiated and conducted heat energy from the heated bottom of the furnace body. A temperature detector is provided on the pyrolysis furnace and electrically connected to the controller, and has a temperature detection end extending into the pyrolysis chamber, which is used to feed back the pyrolysis temperature of the waste plastic in the pyrolysis chamber to the controller, and the controller outputs a control signal to the frequency converter and the heating controller. A heavy component capture separator is installed at the exhaust port outlet of the pyrolysis chamber for capturing and separating the oil fumes discharged from the exhaust port into pyrolysis oil fumes and incompletely pyrolysis oil fumes. The pyrolysis oil fumes are connected to the oil recovery system, and the incompletely pyrolysis oil fumes are returned to the pyrolysis chamber for reheating and pyrolysis. A slag discharge device is installed at the slag discharge port outlet of the pyrolysis chamber and has a slag discharge valve and a slag discharge machine. The slag discharge valve is electrically connected to the controller and is used to control the slag discharge port. The controller can control the opening or closing of the slag discharge port.The slag discharge machine is electrically connected to the controller and is used to collect the residue discharged from the slag discharge port when the port is open. The controller can control the machine to send the residue to a residue collection bin for centralized processing.

2. The waste plastic pyrolysis system as described in claim 1, wherein, A feeding control device is provided between the discharge port at the high end of the feeder and the inlet of the pyrolysis chamber. The feeding control device has a feeding hopper. A first feeding control valve is provided at the inlet end of the feeding hopper to connect to the discharge port, and a second feeding control valve is provided at the outlet end to connect to the inlet. The first feeding control valve and the second feeding control valve are electrically connected to a control signal output terminal of the controller. The controller can determine the opening / closing timing of the first feeding control valve and the second feeding control valve, so that the waste plastic falling from the discharge port first enters the feeding hopper and then falls from the feeding hopper to the pyrolysis chamber.

3. The waste plastic pyrolysis system as described in claim 2, wherein, The outer surface of the feed hopper is covered with a heating element, which is electrically connected to the controller.

4. The waste plastic pyrolysis system as described in claim 1, wherein, The controller receives the temperature feedback signal from the temperature detector and outputs control signals to the frequency converter and the heating controller. The frequency converter receives the control signal from the controller and controls the eddy current heating of the furnace wall to start when the thermal pyrolysis temperature of the waste plastic in the pyrolysis chamber is lower than a lower limit temperature, and controls the eddy current heating of the furnace wall to stop when it is higher than an upper limit temperature. The heating controller receives the control signal from the controller and controls the multiple heating rods and the one or more heating plates to use a multi-stage heating mode from high power to low power during the period from the start to the stop of the eddy current heating of the furnace wall to compensate for the thermal pyrolysis temperature of the waste plastic in the upper and lower central areas of the pyrolysis chamber. When the eddy current heating of the furnace wall stops, it controls the multiple heating rods and the one or more heating plates to continue heating in the low power heating mode.

5. The waste plastic pyrolysis system as described in claim 4, wherein, The mixer's stirring motor power input terminal is equipped with a current sensor, which is electrically connected to a power output terminal of the power supply. The current sensor is also electrically connected to a signal input terminal of the controller to feed back the current data value of the stirring motor to the controller.

6. The waste plastic pyrolysis system as described in claim 4, wherein, The pyrolysis system also includes a nitrogen generator, the nitrogen output of which is at least connected to the pyrolysis chamber.

7. The waste plastic pyrolysis system as described in claim 1, wherein, The multiple heating rods are each filled with an insulating and thermally conductive filler inside a heating sheath tube, and a resistance wire is isolated in the filler. The two ends of the resistance wire extend out of the heating sheath tube and are electrically connected to the heating controller.

8. The waste plastic pyrolysis system as described in claim 7, wherein, The heating sheath can be a metal or ceramic tube, or a composite tube in which a metal tube is wrapped with a ceramic tube. The filler can be magnesium oxide powder with insulating and thermally conductive properties, and the resistance wire can be a spiral heating chromium or nickel-chromium alloy wire.

9. The waste plastic pyrolysis system as described in claim 1, wherein, The multiple heating rods are mounted on a support frame at the top of the pyrolysis chamber. The support frame has a main frame through which the rotating shaft passes. The main frame has multiple branch rods, and the multiple heating rods are supported by the multiple branch rods.

10. The waste plastic pyrolysis system as described in claim 1, wherein, The heating plate consists of an insulating and thermally conductive filler material installed inside a hollow heating plate body, and a resistor element isolated in the filler material. The two ends of the resistor element extend out of the hollow heating plate body and are electrically connected to the heating controller.

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