JP4131428B2 - Thermal decomposition apparatus and thermal decomposition method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal decomposition apparatus and a thermal decomposition method for heating and decomposing plastics such as waste plastic in the absence of oxygen.
[0002]
[Prior art]
There are various types of plastics discharged from factories and households, such as olefin plastics such as polyethylene and polypropylene, and styrene plastics such as polystyrene. In order to recover useful components from these plastics as resources, a method of thermally decomposing plastics in the absence of oxygen using a pyrolyzer is widely employed. The cracked gas generated by thermal decomposition is often cooled and condensed by a cooler (condenser) and recovered as an oil component.
[0003]
Typical pyrolyzers include a tank type and a tube type. The tank-type pyrolyzer has a cylindrical tank body with a conical bottom, and a heating unit placed around it. The plastic charging part, cracking gas discharging part, and the residue discharging part at the bottom. Are provided respectively. In addition, the tube-type pyrolyzer includes a horizontally long and slender cylindrical reaction tube and a heating unit disposed around the tube, and a plastic supply unit is provided at one end of the reaction tube, and a cracked gas and residue discharge unit is provided at the other end. . In any of the pyrolyzers, the plastic is pyrolyzed by the heat energy from the heating unit disposed around.
[0004]
There are two types of heating methods for the heating unit, that is, a method of supplying a heated gas from the outside and a method of heating with an electric heater, but the former heated gas supply method is widely adopted from the viewpoint of economy and the like. In the case of the heated gas supply system, a heated gas generator is provided, in which gas fuel or liquid fuel is burned to generate high-temperature heated gas, and the heated gas is connected to the heating section of the pyrolyzer by piping (or a duct). Supply.
On the other hand, the cracked gas produced by the pyrolyzer is cooled by a cooler and the condensed oil is recovered, but the gas component that does not condense by the cooler has a very low utility value, so it is burned by a heated gas generator as a gaseous fuel. Often to do.
[0005]
[Problems to be solved by the invention]
However, in the method of combusting gas components with a heated gas generator, the amount of gas components generated varies greatly depending on the type and properties of the plastic used as the raw material, so the temperature of the heated gas supplied from the heated gas generator to the pyrolyzer However, there is a problem that it fluctuates accordingly. For example, when the amount of gas components generated is less than the amount of heat energy required by the heated gas generator, the temperature of the generated heated gas decreases. Conversely, when the amount of gas component generated is greater than the amount of thermal energy required by the heated gas generator, the temperature of the generated heated gas rises.
[0006]
Then, this invention makes it a subject to solve the problem at the time of using a gas component as gaseous fuel of a heating gas generator, and it aims at providing the new thermal decomposition apparatus and thermal decomposition method for it.
Another object of the present invention is to provide a thermal decomposition apparatus and a thermal decomposition method that can stably burn gas components with a heated gas generator.
Furthermore, this invention also aims at providing the thermal decomposition apparatus which can cool a thermal decomposer rapidly, and the thermal decomposition method.
[0007]
[Means for Solving the Problems]
That is, the thermal decomposition apparatus of the present invention includes a thermal decomposer that heats and decomposes plastic in the absence of oxygen, a heating unit provided in the thermal decomposer, and a heated gas generator that supplies heated gas to the thermal decomposer. And a cooler for cooling the cracked gas generated by the thermal cracker. The heated gas generator is provided with a gas combustion device, a liquid combustion device, and a cooling air supply unit. A gas component that is not condensed by the cooler is supplied to the gas combustion device, and an oil component condensed by the cooler is supplied. It is configured to be supplied to the liquid combustion apparatus. Further, a temperature control device is provided, which supplies or increases the oil component to the liquid combustion device when the gas component is insufficient and the temperature of the heating gas falls, and the gas component is excessive and the heating gas Control is performed such that when the temperature rises, the cooling air is supplied or increased from the cooling air supply unit (claim 1).
[0008]
In the thermal decomposition apparatus, a pressure control apparatus for controlling the pressure of the gas component supplied to the gas combustion apparatus to a preset value can be provided.
Further, in the above thermal decomposition apparatus, there can be provided a heated gas stop means for stopping the supply of the heated gas to the thermal decomposer and a cooling air supply means for supplying cooling air to the thermal decomposer.
[0009]
The thermal decomposition method of the present invention includes a thermal decomposer having a heating unit, a heated gas generator for supplying heated gas to the thermal decomposer, and a cooler for cooling the decomposed gas generated by the thermal decomposer. This is a method in which a plastic is heated and pyrolyzed in the absence of oxygen using an apparatus. Then, the cracked gas generated by the pyrolyzer is cooled by a cooler, and the gas components that are not condensed by the cooler are burned by the heated gas generator, and the supply amount of the gas components is insufficient, and the temperature of the heated gas decreases. The oil component condensed in the cooler is combusted in the heated gas generator, and when the supply amount of the gas component is excessive and the heating temperature rises, the cooling air is supplied to the heated gas generator. (Claim 4).
In the thermal decomposition method, when the thermal decomposer is cooled, the supply of the heated gas from the heated gas generator to the heating unit can be stopped and the cooling air can be supplied to the heating unit.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a process flow diagram illustrating a thermal decomposition apparatus and a thermal decomposition method according to the present invention. In the figure, 1 is a thermal decomposer, 2 is a heating unit, 3 is a heated gas generator, 4 is a cooler, 5 is an oil recovery tank, 6 is a pump, 7 is a blower, 8 is a suction blower, and 9 is gas combustion. Device, 10 is a liquid combustion device, 11 is a temperature control device, 12 is a temperature measuring device, 13 is a pressure control device, 14 is a pressure measuring device, 15 is a cooling air regulating valve, 16, 17 and 18 are on-off valves (or dampers) And gate valves) and a to k are pipes.
[0011]
In this example, a tank mold is used as the pyrolyzer 1, and although not shown, a plastic charging part is provided at the top, a scraper is provided inside, and a residue discharging part is provided at the bottom. The heating unit 2 is disposed so as to cover the periphery of the pyrolyzer 1, and heats the plastic in the pyrolyzer 1 while the heated gas supplied from the pipe a passes through the inside. In addition, a tubular type can also be used as the pyrolyzer 1.
The cracked gas generated by thermally decomposing the plastic in the pyrolyzer 1 is introduced into the cooler 4 from the pipe c, where it is cooled by cooling water or the like and partly condensed to become oil. The oil is stored in the oil recovery tank 5 via the pipe d. On the other hand, gas components that are not condensed in the cooler 4 are supplied to the gas combustion device 9 through the pipe e. The oil content in the oil recovery tank 5 is supplied to the liquid combustion apparatus 10 through a pipe f provided with a pump 6.
[0012]
The heated gas generator 3 includes a gas combustion device 9 that burns gas components and a liquid combustion device 10 that burns oil, and the generated high-temperature combustion gas is discharged from the pipe h as a heating gas. Further, the heating gas generator 3 is supplied with cooling air from a pipe g.
The gas combustion device 9 includes a gas burner 19, a gas regulating valve 20 provided in a pipe e from the cooler 4, and an air regulating valve 21 provided in a pipe i from the blower blower 7. The gas regulating valve 20 and the air regulating valve 21 are connected to the drive unit 22 by a linkage, and the drive unit 22 drives the linkage by a control signal from the pressure control device 13. As described above, by mechanically interlocking the gas regulating valve 20 and the air regulating valve 21 with the linkage, the combustion air necessary for the flow rate of the gas component can be automatically supplied at the optimum air-fuel ratio.
[0013]
The pressure measuring device 14 measures the pressure of the gas component in the pipe e, and the measurement signal is input to the pressure control device 13. The pressure control device 13 outputs a control signal to the drive unit 22 so as to maintain the pressure of the gas component supplied to the gas burner 19 at a preset value (for example, a low pressure of about 50 mm underwater). When the gas pressure is lower, the gas regulating valve 20 and the air regulating valve 21 are controlled to be throttled. Conversely, when the gas pressure is higher than the set value, the gas regulating valve 20 and the air regulating valve 21 are controlled to open. It is also possible to provide a gas discharge part at the upper part of the cooler 4 and connect the pipe e to the discharge part as shown by a dotted line to supply the gas component flowing out to the gas combustion device 9. When the pyrolyzer 1 is operated in a reduced pressure state, a vacuum pump is provided in the dotted line portion of the pipe e. In this case, the gas component is supplied to the gas combustion device 9 by using the pressure on the secondary side of the vacuum pump. be able to.
[0014]
The liquid combustion apparatus 10 includes an oil burner 23, an oil adjustment valve 24, and an air adjustment valve 25. The oil adjustment valve 24 and the air adjustment valve 25 are connected to a drive unit 26 by a linkage, and the drive unit 26 is connected to the temperature control device 11. It is driven by the control signal. By linking the oil regulating valve 24 and the air regulating valve 25 mechanically by the linkage, the combustion air necessary for the flow rate of the oil component can be automatically supplied at the optimum air-fuel ratio.
The cooling air adjustment valve 15 adjusts the flow rate of the cooling air sent from the blower blower of the cooling air supply source (not shown) through the pipe g, and is driven by a control signal from the temperature control device 11. The cooling air adjusting valve 15 and the piping g constitute a cooling air supply unit 30. In addition, the drive system of the drive parts 22 and 26 and the cooling air regulating valve 15 may be any of electric type, pneumatic type or hydraulic type.
[0015]
The temperature control device 11 controls the oil supply amount or the cooling air supply amount to the heating gas generator 3 so as to maintain the temperature of the heating gas flowing out from the heating gas generator 3 within a preset allowable range.
For example, when the temperature of the heated gas is maintained within a set range by only supplying the gas component from the cooler 4 as the main fuel in normal times, oil temperature combustion or cooling air supply from the temperature control device 11 is performed. The requested control signal is not output. However, at the time of starting the apparatus or when the supply flow rate of the gas component is temporarily reduced and the temperature of the heated gas falls below the set range, control for supplying oil from the temperature control device 11 to the drive unit 26 as auxiliary fuel. A signal is output to recover the temperature. Conversely, when the supply amount of the gas component increases and the temperature of the heated gas rises beyond the set range, a control signal for supplying cooling air from the temperature control device 11 to the cooling air adjustment valve 15 is output. Similarly, recover the temperature.
[0016]
Even during normal operation, if the supply amount of the gas component is insufficient due to the type or properties of the plastic, the temperature control device 11 compensates for the shortage because the heating gas temperature falls below the set range. In addition, a control signal for supplying oil as auxiliary fuel is output to the drive unit 26. On the contrary, when the supply amount of the gas component is excessive during normal operation, the temperature of the heating gas rises from the set range, so that the temperature control device 11 compensates for the excess by the cooling air regulating valve. 15 outputs a control signal for supplying cooling air.
[0017]
As described above, in the normal operation, when the supply amount of the gas component further decreases while some oil is being burned, the temperature control device 11 outputs a control signal for increasing the oil to the drive unit 26. On the other hand, when the amount of the gas component increases when some oil is combusted during normal operation, and the temperature of the heated gas can be maintained within the set range by itself, the temperature control device 11 causes the drive unit 26 to Outputs a control signal to stop oil supply.
On the other hand, when the supply amount of the gas component further increases while supplying some cooling air during normal operation, the temperature control device 11 sends a control signal to the cooling air adjustment valve 15 so as to increase the cooling air. Output. On the other hand, when some amount of cooling air is supplied during normal operation and the supply amount of the gas component decreases, the temperature control device 11 sends a control signal to the cooling air adjustment valve 15 to stop the supply of cooling air. Output.
[0018]
The temperature control device 11 can be configured by a computer device, a sequencer device, or the like. For example, a computer device includes a main processing unit (CPU), a storage unit, an interface, an input unit such as a keyboard, a display unit such as a display, and the like. The main calculation unit compares the signal from the temperature measuring device 12 with the set value, outputs a control signal to the drive unit 26 and the cooling air regulating valve 15, and further starts the pump 6 if necessary. A stop signal is also output.
[0019]
An open / close valve 16 is provided in a pipe h for supplying the heated gas from the heated gas generator 3 to the thermal decomposer 1, and an open / close valve 17 is provided between the pipe h on the upstream side of the open / close valve 16 and the pipe b to the suction blower 8. Is bypassed by pipe j having Further, the upstream side of the cooling air adjustment valve 15 provided in the pipe g and the downstream side of the on-off valve 16 are bypassed by the pipe k having the on-off valve 18. The on-off valve 16 and the on-off valve 17 constitute a heating gas stop means 31 for stopping the supply of the heating gas to the thermal decomposer 1, and the on-off valve 18 and the piping k supply the cooling air to supply the cooling air to the thermal decomposer 1. Means 32 are configured.
[0020]
The heated gas stop means 31 and the cooling air supply means 32 are used for rapidly cooling the thermal decomposer 1 when the operation of the thermal decomposer 1 is completed or abnormally stopped. For example, when the operation of the pyrolyzer 1 is stopped, while the operation of the suction blower 8 is continued, the gas combustion device 9 and the liquid combustion device 10 in the heated gas generator 3 are stopped and the operation of the blower blower 7 is performed. In a continuous state, the on-off valve 16 is closed and the on-off valves 17 and 18 are opened. Then, the supply of the heated gas supplied from the heated gas generator 3 to the thermal decomposer 1 is stopped. Instead, the cooling air from the pipe g is supplied to the thermal decomposer 1 via the on-off valve 18 and is supplied to the thermal decomposer 1. Cools rapidly.
[0021]
On the other hand, the inside of the heated gas generator 3 is cooled by continuing the blowing from the blower blower 7, and the heated air is discharged by the suction blower 8 through the on-off valve 17. However, in the case where the pyrolyzer 1 is temporarily stopped and cooled, for example, when the heated gas generator 3 is not desired to be cooled, the blower blower 7 is stopped and the on-off valve 17 is closed.
The thermal decomposition apparatus of the present invention can be applied to either the batch operation of the thermal decomposer 1 or the continuous operation. Further, when the recovered oil is further distilled by a distillation apparatus and recovered as a purified chemical, a part of the heating gas obtained by the heating gas generator 3 can be used as a heating source of the distillation apparatus. .
[0022]
【The invention's effect】
As described above, the thermal decomposition apparatus of the present invention is provided with the temperature control device for controlling the temperature of the heated gas supplied to the heating section of the thermal decomposition device, and the temperature control device is configured to supply the gas component from the cooler. When the temperature of the heated gas falls due to a shortage of gas, the oil component is supplied to the liquid combustion device or increased, and when the supply amount of the gas component is excessive and the temperature of the heated gas rises, the cooling air supply unit The cooling air is supplied from or controlled to increase it. Therefore, by using the pyrolysis apparatus of the present invention, the heating gas supplied to the heating section of the pyrolyzer can be maintained within a set range while the gas component that does not condense in the cooler is burned in the heated gas generator. . In addition, when the gas component is insufficient, the oil recovered by the cooler is used as the auxiliary fuel, so that the thermal decomposition apparatus can be operated at a low cost.
[0023]
In the above thermal decomposition apparatus, a pressure control device for controlling the pressure of the gas component supplied to the gas combustion device to a preset value can be provided, so that even if the flow rate of the gas component from the cooler fluctuates, The gas component can be stably burned by the gas combustion device.
In the above thermal decomposition apparatus, it is possible to provide a heating gas stop means for stopping the supply of the heating gas to the pyrolyzer and a cooling air supply means for supplying cooling air to the pyrolyzer, thereby completing the operation of the pyrolyzer. The pyrolyzer can be rapidly cooled during times and during abnormal stops.
[0024]
In the pyrolysis method of the present invention, the cracked gas generated by the pyrolyzer is cooled by a cooler, and the gas component that is not condensed by the cooler is combusted by the heated gas generator, and the supply amount of the gas component is insufficient and heating is performed. When the gas temperature falls, the oil component condensed in the cooler is burned in the heated gas generator, and when the supply amount of the gas component is excessive and the heating temperature rises, the cooling air is supplied to the heated gas generator. It is characterized by that. Therefore, according to the present method, the heating gas supplied to the heating section of the pyrolyzer can be maintained within a set range while all the gas components that are not condensed by the cooler are burned by the heated gas generator. In addition, when the gas component is insufficient, the oil recovered by the cooler is used as the auxiliary fuel, so that the thermal decomposition apparatus can be operated at a low cost.
[Brief description of the drawings]
FIG. 1 is a process flow diagram illustrating a thermal decomposition apparatus and a thermal decomposition method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thermal decomposition device 2 Heating part 3 Heating gas generator 4 Cooler 5 Oil recovery tank 6 Pump 7 Blower blower 8 Suction blower 9 Gas combustion device 10 Liquid combustion device 11 Temperature control device 12 Temperature measurement device 13 Pressure control device 14 Pressure measurement 15 Cooling air regulating valve 16 On-off valve 17 On-off valve 18 On-off valve 19 Gas burner 20 Gas regulating valve 21 Air regulating valve 22 Drive unit 23 Oil burner 24 Oil regulating valve 25 Air regulating valve 26 Driving unit 30 Cooling air supply unit 31 Heating gas Stop means 32 Cooling air supply means a to k Piping

Claims (5)

A pyrolyzer 1 that heats and decomposes plastic in the absence of oxygen, a heating unit 2 provided in the pyrolyzer 1, a heated gas generator 3 that supplies heated gas to the pyrolyzer 1, and pyrolysis In the thermal decomposition apparatus including the cooler 4 for cooling the cracked gas generated in the vessel 1,
The heated gas generator 3 includes a gas combustion device 9, a liquid combustion device 10, and a cooling air supply unit 30,
A gas component that is not condensed by the cooler 4 is supplied to the gas combustion device 9, and an oil component condensed by the cooler 4 is supplied to the liquid combustion device 10, and a temperature control device 11 is further provided. And
The temperature control device 11 supplies or increases the oil component to the liquid combustion device 10 when the gas component is insufficient and the heating gas temperature falls, and cooling air when the gas component is excessive and the heating temperature rises. A thermal decomposition apparatus that controls to supply cooling air from the supply unit 30 or increase the cooling air. The thermal decomposition apparatus according to claim 1, wherein a pressure control device 13 that controls a pressure of a gas component supplied to the gas combustion device 9 to a preset value is provided. The thermal decomposition according to claim 1 or 2, wherein a heating gas stop means 31 for stopping the gas supply for heating to the pyrolyzer 1 and a cooling air supply means 32 for supplying cooling air to the pyrolyzer 1 are provided. apparatus. A thermal decomposition apparatus including a thermal decomposer 1 having a heating unit 2, a heated gas generator 3 for supplying heated gas to the thermal decomposer 1, and a cooler 4 for cooling the decomposed gas generated in the thermal decomposer 1. In the method of using and heat-decomposing plastics in the absence of oxygen,
The gas component that is not condensed in the cooler 4 is combusted in the heated gas generator 3, and when the supply amount of the gas component is insufficient and the heated gas temperature is lowered, the oil component condensed in the cooler 4 is generated as a heated gas. A pyrolysis method characterized by supplying cooling air to the heated gas generator 3 when the heating temperature rises due to an excessive amount of gas components burned in the vessel 3. 5. The thermal decomposition method according to claim 4, wherein when the thermal decomposer 1 is cooled, the supply of the heated gas from the heated gas generator 3 to the heating unit 2 is stopped and the cooling air is supplied to the heating unit 2.

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