Combustible waste material processing device and processing method

Abstract

[Problem] The present invention addresses the problem of effectively using waste plastic or another combustible waste material as fuel in a cement kiln. [Solution] Provided is a combustible waste material processing device comprising a gasification furnace 3 that heats and gasifies a combustible waste material W using a crushed or granulated solid heat medium C1, and a combustible gas supply device that supplies a combustible gas G1 generated in the gasification furnace into a cement kiln from in front of the cement kiln. The present invention may comprise a medium preheating device 2 that combusts exhaust gas G1 from the gasification furnace to preheat the solid heat medium, and a mixture M1 of the solid heat medium and the remaining combustible waste material discharged from the gasification furnace may be introduced into the medium preheating device. Employing, as the solid heat medium, a preheating raw material that is isolated from a preheater cyclone of a cement firing device makes it possible to process the combustible waste material using waste heat in the cement firing device.

Description

Combustible waste treatment device and treatment method

[0001] The present invention relates to a treatment device and a treatment method for combustible waste, and more particularly to a device and a method for effectively utilizing combustible waste such as waste plastics as fuel for a cement kiln.

[0002] Conventionally, in the cement manufacturing process, attempts have been made to use various combustible wastes as substitute fuels, thereby contributing to waste disposal and reducing the unit consumption of expensive fossil fuels in cement manufacturing.

[0003] For example, Patent Document 1 describes a combustible waste treatment device that includes a partial gasification furnace that supplies a gasifying agent together with the combustible waste to partially gasify the combustible waste, and a burner that injects the partially gasified combustible waste into a cement kiln.

[0004] On the other hand, Patent Document 2 describes a fuel conversion system for combustible waste, which includes a pyrolysis gasification furnace that gasifies combustible waste by pyrolysis, a flow regulator that alternately operates two or more pyrolysis gasification furnaces and adjusts the flow rate of the pyrolysis gas discharged from the operating pyrolysis gasification furnaces, and a supply means that continuously supplies the pyrolysis gas, the flow rate of which has been adjusted by the flow regulator, to the main burner of a cement kiln.

[0005] Japanese Patent Publication No. 2009-281600 Japanese Patent Publication No. 2021-098619

[0006] However, in the inventions described in the above patent documents, a partial gasification furnace or a dry distillation gasification furnace is used to gasify combustible waste, but no specific device configuration is disclosed.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an apparatus and method suitable for effectively utilizing combustible waste such as waste plastics as fuel for cement kilns.

[0008] To achieve the above object, the present invention provides a combustible waste treatment device comprising a gasification furnace that heats and gasifies combustible waste using a powdered or granular solid heat medium, and a combustible gas supply device that supplies the combustible gas generated in the gasification furnace into the cement kiln from before the cement kiln is fired. According to the present invention, combustible waste such as waste plastics can be effectively used as fuel for the cement kiln.

[0009] In the treatment device, by providing a medium preheating device that combusts the exhaust gas from the gasification furnace to preheat the solid heat medium, the exhaust gas from the gasification furnace can be used efficiently.

[0010] By introducing a mixture of the residue of the combustible waste discharged from the gasification furnace and a solid heat transfer medium into the medium preheating device, the solid heat transfer medium can be recycled and reused.

[0011] The solid heat transfer medium may be a preheated raw material separated from a preheater cyclone of a cement calciner, and the waste heat from the cement calciner can be used to treat combustible waste.

[0012] A mixture of the residue of combustible waste discharged from the gasification furnace and the preheated raw material can be introduced into the cement kiln of the cement burning device and burned.

[0013] The present invention also provides a method for treating combustible waste, which comprises heating and gasifying combustible waste using a powdered or granular solid heat transfer medium, and supplying the generated combustible gas into the cement kiln from the front of the kiln to be burned. According to the present invention, combustible waste such as waste plastics can be effectively used as kiln fuel for the cement kiln.

[0014] In the above method, by using a preheated raw material separated from a preheater cyclone of a cement calciner as the solid heat transfer medium, the combustible waste can be treated using waste heat from the cement calciner.

[0015] A mixture of the residue remaining after gasifying the combustible waste and the preheated raw material used to heat the solid heat transfer medium can be introduced into the cement kiln and fired.

[0016] As described above, according to the present invention, combustible waste such as waste plastics can be effectively utilized as fuel for cement kilns.

[0017] 1 is an overall configuration diagram showing a first embodiment of a treatment apparatus for combustible waste according to the present invention, and FIG. 2 is an overall configuration diagram showing a second embodiment of a treatment apparatus for combustible waste according to the present invention.

[0018] Next, embodiments of the present invention will be described in detail with reference to the drawings.

[0019] FIG. 1 shows a first embodiment of a treatment device for combustible waste (hereinafter referred to as the "treatment device") according to the present invention. This treatment device 1 includes a medium preheating device 2 that preheats cement clinker dust (hereinafter referred to as "clinker dust") C1 as a powdered or granular solid heat medium, a gasification furnace 3 that heats and gasifies waste plastic (hereinafter referred to as "waste plastic") W as combustible waste using the preheated clinker dust C3, a heat exchanger 4 that performs heat exchange using exhaust gas G2 from the medium preheating device 2, and a gas conveying path 11 that conveys combustible gas G1 generated in the gasification furnace 3 to a cement kiln burner (not shown).

[0020] The medium preheating device 2 includes a combustion burner 2b at the bottom of a main body 2a, and a cyclone 2c and a double flap damper (hereinafter referred to as "damper") 2d at the rear of the main body 2a. Fuel gas, high-temperature gas G3 from a heat exchanger 4, and combustible gas G4 from the gasifier 3 are supplied to the combustion burner 2b via fans 9 and 10, and the combustion gas preheats clinker dust C1 (during normal operation, a mixture M2 of clinker dust C2 and a mixture M1, described below). An outlet gas duct of the cyclone 2c is connected to the heat exchanger 4, and clinker dust C3 from the cyclone 2c is introduced into the gasifier 3 via the damper 2d.

[0021] Preheated clinker dust C3 is supplied to the gasifier 3 from the damper 2d, and the waste plastic W supplied from the storage tank 13 is heated and gasified. The gasifier 3 is equipped with a gas duct 3b at the top of the main body 3a, and a cyclone 3d and a damper 3e downstream of the gas duct 3b. A damper 3c is also provided at the bottom of the main body 3a for discharging a mixture M1 of the clinker dust used for heating and the residue of the gasified waste plastic W. Clinker dust C1 used as a solid heat transfer medium is supplied to the gas duct 3b from the storage tank 12, and combustible gas G1 obtained by preheating the clinker dust C1 is supplied to the kiln burner via the gas conveying path 11 and the fan 8. A portion G4 of the combustible gas G1 is introduced into the combustion burner 2b of the medium preheating device 2 via the fan 10. The clinker dust C2 recovered by the cyclone 3d is supplied to the medium preheating device 2 together with the mixture M1 via the damper 3e and is preheated.

[0022] A fan 7 is provided near the heat exchanger 4 to introduce the air A into the heat exchanger 4, and a dust collector 5 and a chimney 6 are arranged downstream of the heat exchanger 4. The air A introduced by the fan 7 is heat exchanged with the exhaust gas G2 from the medium preheating device 2.

[0023] Next, a method for treating combustible waste according to the present invention using the treatment device 1 having the above-described configuration will be described with reference to FIG.

[0024] Fuel gas is burned in the combustion burner 2b of the medium preheating device 2 to heat the inside of the main body 2a, and then the clinker dust C1 stored in the storage tank 12 is supplied to the medium preheating device 2 via the gasification furnace 3 and preheated. Preheated clinker dust C3 of about 500°C is supplied to the gasification furnace 3 via the cyclone 2c and damper 2d, and the waste plastic W supplied from the storage tank 13 is heated and gasified.

[0025] After preheating clinker dust C1 (mixture M2 during normal operation), exhaust gas G2 at about 700°C is introduced into heat exchanger 4 and heat exchanged with air A from fan 7, producing high-temperature gases G3, G5 to G7 at about 200°C. High-temperature gas G3 is introduced into combustion burner 2b of medium preheating device 2 via fan 9, and high-temperature gas G6 is used as combustion air for the kiln burner, while high-temperature gases G5 and G7 are exhausted. High-temperature gas G7 is filtered out in dust collector 5 and then released into the atmosphere from chimney 6.

[0026] Combustible gas G1 of about 300 to 500°C generated by gasifying waste plastic W in the gasification furnace 3 is used to preheat clinker dust C1 in gas duct 3b, and then supplied to the kiln burner via cyclone 3d, gas conveying path 11, and fan 8, and used for combustion in the kiln. A portion of the combustible gas G1 is introduced as high-temperature gas G4 via fan 10 into the combustion burner 2b of the medium preheating device 2.

[0027] The clinker dust C1 discharged from the storage tank 12 is preheated by the combustible gas G1 in the gas duct 3b, then passes through the cyclone 3d and the damper 3e and is introduced into the medium preheating device 2 together with the mixture M1, where it is preheated and used for gasification in the gasification furnace 3.

[0028] In the above embodiment, the case where clinker dust is used as the solid heat transfer medium is exemplified, but silica sand, slag, etc. may also be used in place of clinker dust.

[0029] Next, a second embodiment of the processing apparatus according to the present invention will be described with reference to FIG.

[0030] This treatment device 21 uses preheated raw material R1 taken from a raw material chute 22a of a lowermost cyclone 22 of a preheater of a cement burning device as a solid heat medium to heat and gasify waste plastic W as combustible waste.

[0031] Below the lowest-stage cyclone 22 are arranged a screw conveyor 27 for collecting preheated raw material R1, a damper 28, a cushion hopper 29, and a screw conveyor 30. The screw conveyor 27 has an opening formed by removing the upper half of its casing, and the preheated raw material R1 is collected from this opening and introduced into the damper 28. The cushion hopper 29 is provided to prevent fluctuations in the amount of preheated raw material R1 supplied to the screw conveyor 30.

[0032] On the other hand, a damper 31, a cushion hopper 32, and a screw conveyor 33 are arranged below a storage tank (not shown) to supply the waste plastic W to the gasification furnace 23. The cushion hopper 32 is provided to prevent fluctuations in the amount of waste plastic W supplied to the screw conveyor 33.

[0033] The gasification furnace 23 is provided with a supply port (not shown) at the top of the main body 23a for the preheated raw material R1 and waste plastic W from the screw conveyors 30 and 33, and a damper 34 at the bottom for discharging the mixture M of the preheated raw material R1 used for heating and the residue of the gasified waste plastic W. In addition, a nitrogen gas generator 39 is provided to reduce the oxygen concentration inside the main body 23a and to prevent gas from blowing out from the shaft seal.

[0034] Furthermore, it is provided with a gas conveying path 35 for conveying the combustible gas G21 generated in the gasification furnace 23 to a cement kiln burner (not shown), and a fan 36 and a gas conveying path 37 for conveying the combustible gas G22 to a calciner burner 38.

[0035] In this embodiment, the preheated raw material R1 is taken from the lowest cyclone 22 of the preheater of the cement burning apparatus, but the preheated raw material may be taken from another preheater cyclone above the lowest cyclone 22.

[0036] Next, a method for treating combustible waste according to the present invention using the treatment device 21 having the above-described configuration will be described with reference to FIG.

[0037] During operation of a cement burning apparatus equipped with a cement kiln 24, a calciner 26, a lowest-stage cyclone 22, etc., preheated raw material R1 at approximately 900°C is collected from the lowest-stage cyclone 22 by a screw conveyor 27 and supplied to the gasifier 23 via a damper 28, a cushion hopper 29, and a screw conveyor 30. Meanwhile, waste plastics W stored in a storage tank (not shown) are supplied to the gasifier 23 via a damper 31, a cushion hopper 32, and a screw conveyor 33. Note that preheated raw material R2 not collected by the screw conveyor 27 is supplied directly to the cement kiln 24.

[0038] In the gasification furnace 23, the waste plastics W are heated and gasified using the sensible heat of the preheated raw material R1, and the resulting combustible gas G21 at approximately 300 to 500°C is supplied to a cement kiln burner via a gas conveyance line 35 and used for combustion in the cement kiln. In addition, the combustible gas G22 is supplied to a calciner burner 38 via a fan 36 and a gas conveyance line 37 and used for combustion in the calciner 26.

[0039] The mixture M of the preheated raw material R1 and the residue of the waste plastic W discharged from the gasification furnace 23 is introduced into the rising part 25 at the end of the cement kiln 24 via the damper 34 and is fired in the cement kiln 24.

[0040] Furthermore, if the oxygen concentration inside the main body 23a increases during operation of the gasification furnace 23 and there is a concern of an explosion, nitrogen generated by the nitrogen gas generator 39 is introduced into the gasification furnace 23 to reduce the oxygen concentration.

[0041] Furthermore, when the gasification furnace 23 is installed on the side of the calciner 26, a cyclone and a fan are installed in the gasification furnace 23, and the combustible gas G21 generated in the gasification furnace 23 is removed from the gas and then transported to the cement kiln burner.

[0042] Furthermore, in the above-described embodiment, the combustible gases G1 and G21 generated in the gasification furnaces 3 and 23 are introduced into the cement kiln burner, but they can also be blown into the cement kiln from a dedicated nozzle or the like provided separately from the cement kiln burner. Any configuration is possible as long as the combustible gas supply device can supply the combustible gases G1 and G21 into the cement kiln from in front of the cement kiln.

[0043] REFERENCE SIGNS LIST 1 Treatment device 2 Medium preheating device 3 Gasification furnace 4 Heat exchanger 5 Dust collector 6 Chimney 7 to 10 Fan 11 Gas conveying path 12, 13 Storage tank 21 Treatment device 22 Lowermost cyclone 23 Gasification furnace 24 Cement kiln 25 Rise section 26 Calciner 27 Screw conveyor 28 Damper 29 Cushion hopper 30 Screw conveyor 31 Damper 32 Cushion hopper 33 Screw conveyor 34 Damper 35 Gas conveying path 36 Fan 37 Gas conveying path 38 Calciner burner 39 Nitrogen gas generator

Claims

1. A gasification furnace that heats and gasifies combustible waste with preheated raw materials separated from a preheater cyclone of a cement firing device, and a combustible gas supply device that supplies the combustible gas generated at 300 to 500 °C in the gasification furnace into the cement kiln from in front of the kiln of the cement kiln with a fan. A treatment device for combustible waste, characterized in that it comprises

2. The treatment device for combustible waste according to claim 1, further comprising a preheating device that burns the exhaust gas of the gasification furnace to preheat the preheated raw materials.

3. The treatment device for combustible waste according to claim 2, characterized in that a mixture of the residue of the combustible waste discharged from the gasification furnace and the preheated raw materials is introduced into the preheating device.

4. (Deleted)

5. The treatment device for combustible waste according to claim 1, 2 or 3, characterized in that a mixture of the residue of the combustible waste discharged from the gasification furnace and the preheated raw materials is introduced into the cement kiln of the cement firing device.

6. Heat and gasify combustible waste with preheated raw materials separated from a preheater cyclone of a cement firing device, A method for treating combustible waste, characterized in that the generated combustible gas is supplied into the cement kiln from in front of the kiln of the cement kiln with a fan and burned.

7. (Deleted)

8. The method for treating combustible waste according to claim 6, characterized in that a mixture of the residue after gasifying the combustible waste and the preheated raw materials is introduced into the cement kiln.