Heat treatment system
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2021-03-04
- Publication Date
- 2021-10-01
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to a heat treatment system. This application claims priority to Japanese Patent Application No. 2020-047716, filed on March 18, 2020. The entire contents of that Japanese application are incorporated herein by reference. [Previous Technology]
[0002] In heat treatment systems for waste disposal, there are co-current rotary kilns. A co-current rotary kiln is a cylindrical rotary furnace that rotates around an axis, in which heating burners and waste are introduced from the same end of the rotary furnace in the same direction for processing (for example, see Patent Document 1). There are also so-called counter-current rotary kilns in which heating burners and waste are introduced from different ends of the rotary furnace in opposite directions for processing. However, compared with the counter-current type, the co-current rotary kiln described above can process waste at high temperatures without spots for a short time, making it suitable for waste disposal.
[0003] Historically, fossil fuels such as heavy oil and city gas have been used as fuels for the heating burners of parallel-flow rotary kilns. [Previous Technical Documents]
[0004] [Patent Document 1] Japanese Patent Application Publication No. 2010-216763 [Summary of the Invention]
[0005] [The problem the invention aims to solve]
[0006] However, in recent years, due to problems such as climate change caused by increased CO2 emissions, restrictions on the use of fossil fuels have become strict, leading to a situation where alternative fuels other than fossil fuels are desired.
[0007] This invention was made in view of this purpose, and one of its objectives is to provide a heat treatment system capable of treating waste and other heated materials in a co-current rotary kiln using fossil fuels as the primary fuel. [Technical Means for Solving the Problem]
[0008] A heating treatment system of the same type of the present invention includes a pyrolysis furnace for thermally decomposing raw materials to produce pyrolysis products and a co-current rotary kiln for heating the heated material using the pyrolysis products produced in the pyrolysis furnace.
[0009] According to this model, since the thermal decomposition products generated in the thermal decomposition furnace can be used to heat the heated material in the parallel flow rotary kiln, the heated material can be heated at high temperature and for a short time without the use of fossil fuels as the main fuel.
[0010] The heating system may also include a heat recovery device for recovering heat from the exhaust gas discharged from the rotary kiln.
[0011] The heating treatment system may also include a device that uses the heat from the exhaust gas discharged from the rotary kiln as a heat source for the pyrolysis furnace.
[0012] The object being heated can be waste.
[0013] Raw materials may include biomass raw materials.
[0014] The heat treatment system can be configured such that the thermal decomposition products generated in the pyrolysis furnace are not recovered from heat but are instead transported to the rotary kiln. [Effects of the Invention]
[0015] According to the present invention, a heating treatment system is provided that can heat the object being heated without using fossil fuels, using a co-flow rotary kiln as the main fuel.
Implementation Method
[0016] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same symbols will be used for the same elements, and repeated descriptions will be omitted. Furthermore, the scale of the drawings is not limited to the scale of the drawings. Also, the following embodiments are examples for illustrating the present invention, and the present invention is not limited to these embodiments.
[0017] FIG1 is a schematic diagram showing an example of the configuration of the heat treatment system 1 of this embodiment. The heat treatment system 1 includes: a pyrolysis furnace 10 for thermally decomposing raw materials to produce pyrolysis products, a co-current rotary kiln 11 for heating the heated material using the pyrolysis products produced in the pyrolysis furnace 10, a secondary combustion chamber 12 for secondary combustion of the exhaust gas discharged from the rotary kiln 11, and a heat recovery device 13 for recovering the heat of the exhaust gas discharged from the rotary kiln 11.
[0018] The pyrolysis furnace 10 is, for example, a circulating fluidized bed (CFB) gasification furnace, and includes, for example, a main container 20 as a furnace, a cyclone separator 21, a first conduit 22 connecting the upper part of the main container 20 and the upper part of the separator 21, a second conduit 23 connecting the lower part of the separator 21 and the lower part of the main container 20, and a third conduit 24 connecting the separator 21 and the rotary kiln 11. In this specification, "upper" means above in the vertical direction, and "lower" means below in the vertical direction.
[0019] The main container 20 has a long cavity in the vertical direction, which allows combustion / flowing air, circulating materials, raw materials, etc., introduced into the cavity to rise while simultaneously thermally decomposing the raw materials to produce thermal decomposition products. An inlet section 25 for introducing raw materials is formed in the main container 20. Examples of raw materials include non-fossil fuels, wood biomass, waste tires, waste plastics, sludge, and other waste materials. Examples of circulating materials include silica sand and other particulate matter that flows at high temperatures.
[0020] The inner wall of the main container 20 is made of refractory material and has a structure that prevents heat loss to the outside. The raw material supply system (not shown) that introduces raw materials into the inlet 25 is configured to include, for example, a drying device, a hopper, a screw feeder, a conveyor, and a raw material supply pipe. The raw materials dried by the drying device are stored in the hopper, and the screw feeder delivers the raw materials from the hopper to the conveyor in a specified amount. The conveyor then transports the specified amount of raw materials to the raw material supply pipe, and the raw materials are introduced into the main container 20 from the inlet 25 of the raw material supply pipe.
[0021] Furthermore, the main container 20 is connected to a combustion air supply system (not shown) for introducing combustion air. The combustion air supply system includes, for example, an air supply pipe connected to the lower part of the main container 20, a dust removal device for separating dust and other particles from the combustion air, and a blower for pressurizing the combustion air.
[0022] The first conduit 22 can deliver a high-temperature fluid containing thermal decomposition products, circulating materials, and impurities from the upper part of the main container 20 to the upper part of the separation section 21. The impurities mentioned here include particulate matter from the pulverization of circulating materials and fly ash.
[0023] The separation unit 21 can rotate the high-temperature fluid sent from the pyrolysis furnace 10 and separate the circulating material from the high-temperature fluid by centrifugal separation.
[0024] The second conduit 23 allows the circulating material separated by the separation section 21 to return from the lower part of the separation section 21 to the lower part of the main container 20. The third conduit 24 allows the removal of the circulating material, including the pyrolysis products containing fuel gas and the high-temperature fluid containing impurities, to the first end of the rotary kiln 11 (described later). Therefore, the pyrolysis furnace 10 is configured such that the pyrolysis products generated in the pyrolysis furnace 10 are not recovered by heat exchangers or the like (the temperature does not decrease) and are transported to the rotary kiln 11.
[0025] The co-flow rotary kiln 11 has a cylindrical rotary furnace 40, with a first end 41 at one end in the axial direction and a second end 42 at the other end. The rotary kiln 11 is tilted, for example, such that the first end 41 is located at a higher position than the second end 42. The rotary kiln 11 has a drive device 50, which enables the rotary furnace 40 to rotate about an axis. Compared with the counter-flow rotary kiln, the co-flow rotary kiln 11 has a shorter total axial length, for example, configured such that the ratio of the total axial length L to the diameter D of the cylinder (L / D) is about 3 or more and less than 5.
[0026] The first end 41 is connected to the third conduit 24 and forms a first inlet 60 for fuel gas. The first end 41 also forms a second inlet 61 for introducing the heated material. For example, the second inlet 61 is connected to a conveyor (not shown) for transporting the heated material to the second inlet 61. The first inlet 60 is positioned either higher or lower than the second inlet 61. The heated material is, for example, waste. The second end 42 is an outlet for exhaust gas and is connected to the lower part of the secondary combustion chamber 12. Furthermore, the second end 42 may be connected to a recovery and removal device for recovering and removing the fluid discharged from the rotary kiln 11.
[0027] The secondary combustion chamber 12 has a long main body in the vertical direction, and a heating burner (not shown) is installed at its lower part. Furthermore, the secondary combustion chamber 12 includes devices for supplying substances that promote secondary combustion of the gas and substances that promote the decomposition of the gas. For example, the secondary combustion chamber 12 is provided with a heating burner and an air supply unit as an example. The secondary combustion chamber 12 and the heat recovery device 13 are connected by a fourth conduit 70.
[0028] The heat recovery device 13 includes, for example, a boiler. The heat recovered by the heat recovery device 13 can be used as a heat source for the pyrolysis furnace 10. As an example, the heat recovery device 13 has a conduit for the flow of exhaust gas and a plurality of heat exchangers within the conduit. The heat exchangers have, for example, heat transfer tubes with fins on their surfaces, through which water and water vapor can flow, enabling heat exchange between the heat transfer tubes and the exhaust gas within the conduit. In addition, as described later, the steam formed from the heat recovered from the exhaust gas can be used as a heat source for heating the combustion air of the pyrolysis furnace 10.
[0029] In the heat treatment system 1 configured as described above, the following heat treatment is performed. In the pyrolysis furnace 10, biomass raw materials and waste materials are pyrolyzed to produce pyrolysis products, which are then sent to the separation section 21. At this time, in the main container 20, combustion and flow air introduced from the inlet section 25 causes a solid material containing raw materials and recycled materials to flow. While the raw materials are flowing, they are burned at, for example, 800 to 900°C, thereby generating pyrolysis products. In the separation section 21, recycled materials are separated by centrifugal separation. The separated recycled materials are returned to the pyrolysis furnace 10. The pyrolysis products containing fuel gas, after the recycled materials have been removed, are sent to the first end 41 of the co-current rotary kiln 11. In the rotary kiln 11, while the rotary furnace 40 is rotating around its axis, pyrolysis products are introduced from the first inlet section 60 of the first end 41, and waste materials to be heated are introduced from the second inlet section 61 of the first end 41. The heated materials are then treated by heating with the pyrolysis products.
[0030] Here, the first inlet 60 is positioned lower than the second inlet 61, thereby introducing the thermal decomposition products from the separation section 21 from the lower part of the rotary kiln 11, which are then thoroughly mixed with the heated material in the rotary kiln 11, enabling effective heating treatment.
[0031] In the rotary kiln 11, the heated material is incinerated, melted, or baked. The products of the heat treatment in the rotary kiln 11, such as those produced by incineration, melting, or baking, are recovered as needed.
[0032] The exhaust gas discharged from the second end 42 of the rotary kiln 11 is sent to the secondary combustion chamber 12, where it is further combusted. The exhaust gas discharged from the secondary combustion chamber 12 is sent to the heat recovery device 13, where the heat of the exhaust gas is recovered. The recovered heat is used, for example, as a heat source for the pyrolysis furnace 10.
[0033] According to this embodiment, in the co-current rotary kiln 11, since the pyrolysis products generated in the pyrolysis furnace 10 can be used to heat the heated material, the heated material can be heated at high temperature and for a short time without the use of fossil fuels. Furthermore, the pyrolysis furnace 10 is capable of continuously and stably generating pyrolysis products, and the pyrolysis products supplied from the pyrolysis furnace 10 are suitable for heating the material in the co-current rotary kiln 11 at high temperature and for a short time. In the co-current rotary kiln 11, the high-temperature pyrolysis products from the pyrolysis furnace 10 and the heated material are introduced from the same end 41, so the pyrolysis products immediately contact the heated material at high temperature, enabling effective and short-time heating of the heated material. Also, the high-temperature fluid sent from the pyrolysis furnace 10 to the rotary kiln 11 contains particulate matter from the pulverization of circulating materials and fly ash impurities, but these can be processed together with the heated material in the rotary kiln 11. Furthermore, the carbon and particulate components contained in the high-temperature fluid generated in the pyrolysis furnace 10 have a higher radiant heat effect due to light emission compared to fossil fuels such as city gas, and effectively heat the rotary kiln 11. In addition, the co-current rotary kiln 11 may also be equipped with a recovery section that recovers impurities transported from the pyrolysis furnace 10.
[0034] When biomass is used as a raw material, CO2 production can be significantly reduced. Furthermore, the gas treatment equipment used to detoxify the generated gases can be minimized.
[0035] Since the heating system 1 is equipped with a heat recovery device 13, it can effectively utilize the heat of the high-temperature exhaust gas discharged when using the parallel-flow rotary kiln 11, thus achieving a heating system 1 with high overall thermal efficiency.
[0036] The heating system 1 is configured such that the thermal decomposition products generated in the pyrolysis furnace 10 are not recovered but are transported to the rotary kiln 11. Therefore, the heat introduced into the rotary kiln 11 (lower heating value + sensible heat of the gas) increases, making it easier to raise the temperature of the rotary kiln 11. Furthermore, the heat of the exhaust gas from the rotary kiln 11 is recovered to preheat the combustion and flow air of the pyrolysis furnace 11, thus enabling sufficient heat recovery or combustion and preheating of the flow air.
[0037] The heating system 1 may also include a device for using the heat of the exhaust gas discharged from the rotary kiln 11 as a heat source for the pyrolysis furnace 10. For example, as shown in FIG2, the heating system 1 may recover the heat of the exhaust gas with steam and use the steam to heat the combustion air (combustion and flow air) of the pyrolysis furnace 10. In this case, the heating system 1 includes: a combustion air inlet conduit 80 leading to the main container 20 of the pyrolysis furnace 10, an air preheater 81 provided in the inlet conduit 80, and a steam conduit 82 for conveying the steam of the heat recovery device 13 to the air preheater 81. The steam that recovers the heat of the exhaust gas by the heat recovery device 13 is conveyed to the air preheater 81 through the steam conduit 82. In the air preheater 81, heat exchange occurs between the steam and the combustion air, and the high-temperature combustion air is introduced into the main container 20 of the pyrolysis furnace 10 through the inlet conduit 80. In this case, since the heat remaining in the co-current rotary kiln 11 can be used for the pyrolysis furnace 10, the thermal efficiency of the heating system 1 can be further improved. In addition, in this example, the device for using the heat of the exhaust gas discharged from the rotary kiln 11 as a heat source for the pyrolysis furnace 10 is, for example, composed of a heat recovery device 13, an inlet duct 80, an air preheater 81, and a steam duct 82.
[0038] Furthermore, the heating treatment system 1 can, as shown in FIG3, exchange heat between the exhaust gas and air, and use this air as the combustion air for the pyrolysis furnace 10. In this case, the heating treatment system 1 includes, for example, an air preheater 90 connected to the fourth conduit 70, an inlet conduit 91 for introducing combustion air into the air preheater 90, and an inlet conduit 92 for introducing combustion air from the air preheater 90 into the pyrolysis furnace 10. Heat exchange occurs between the exhaust gas discharged from the co-current rotary kiln 11 and the combustion air introduced into the air preheater 90 through the inlet conduit 91, and the high-temperature combustion air from the air preheater 90 is introduced into the main container 20 of the pyrolysis furnace 10 through the inlet conduit 92. In this case, since the heat remaining in the co-current rotary kiln 11 can be used for the pyrolysis furnace 10, the thermal efficiency of the heating treatment system 1 can be further improved. In addition, in this example, the device for using the heat of the exhaust gas discharged from the rotary kiln 11 as a heat source for the pyrolysis furnace 10 is, for example, composed of an air preheater 90 and inlet pipes 91 and 92.
[0039] In the above embodiments, the heat recovery device 13 is a boiler, but it can also be any device that recovers heat from waste gas. The heating treatment system 1 has a secondary combustion chamber 12 and a heat recovery device 13, but the present invention can also be applied to heating treatment systems that do not have a secondary combustion chamber 12 and a heat recovery device 13. In the above embodiments, the heating treatment system 1 does not use fossil fuels at all, but the present invention can also be applied to heating treatment systems that use fossil fuels as auxiliary fuels.
[0040] The heat treatment system 1 can be used not only as a system for incinerating waste in a parallel-flow rotary kiln 11, but also as a system for melting waste to extract reusable metals, and a system for sintering waste to smelt metals. That is, the rotary kiln 11 can be used as an incinerator and melting furnace for industrial waste, a reduction furnace for waste containing metal resources such as electric furnace dust, a roasting furnace for waste containing metal resources such as used catalysts and batteries, and a melting furnace for waste electronic substrates. Furthermore, the heat treatment system 1 is not limited to waste treatment; it can also be used for the pretreatment of steel and non-ferrous ores. [Industrial Applicability]
[0041] The present invention is useful in providing a heating treatment system that can perform heat treatment such as waste treatment in a parallel-flow rotary kiln without using fossil fuels as the main fuel. [Simplified Explanation of the Diagram]
[0043] [Figure 1] is a schematic diagram showing the general structure of the heat treatment system. [Figure 2] is a schematic diagram showing the general structure of other components of the heat treatment system. [Figure 3] is a schematic diagram showing the general structure of other components of the heat treatment system.
Claims
1. A heating treatment system comprising: a pyrolysis furnace for pyrolyzing raw materials to produce pyrolysis products; and a co-current rotary kiln for heating a heated object using the pyrolysis products produced in the aforementioned pyrolysis furnace.
2. The heat treatment system as described in claim 1, wherein, It also has a heat recovery device for recovering heat from the exhaust gas discharged from the aforementioned rotary kiln.
3. The heat treatment system as described in claim 1 or claim 2, wherein, It also has a device for using the heat from the exhaust gas discharged from the aforementioned rotary kiln as a heat source for the aforementioned pyrolysis furnace.
4. The heat treatment system as described in claim 1 or claim 2, wherein, The aforementioned heated object is waste.
5. The heat treatment system as described in claim 1 or claim 2, wherein, The aforementioned raw materials include biomass raw materials.
6. The heat treatment system as described in claim 1 or claim 2, wherein, The thermal decomposition products generated in the aforementioned pyrolysis furnace are not recovered by heat and are instead transported to the aforementioned rotary kiln.