Heat treatment system

Abstract

A heat treatment system (1) includes a pyrolysis furnace (10) that pyrolyzes a raw material to produce a pyrolysis product, a co-current rotary kiln (11) that heats an object to be heated using the pyrolysis product produced in the pyrolysis furnace (10), and a heat recovery device (13) that recovers heat of exhaust gas exhausted from the rotary kiln (11).

Description

Heat Treatment System

[0001] The present invention relates to a heat treatment system.

[0002] Among heat treatment systems for waste disposal and the like, there is one that uses a co-flow rotary kiln. A co-flow rotary kiln has a cylindrical rotary furnace that rotates around an axis, and treatment is performed by introducing a heating burner and waste material from the same end of the rotary furnace in the same direction (see, for example, Patent Document 1). Rotary kilns include so-called counter-flow types in which the heating burner and waste material are introduced from different ends of the rotary furnace in opposite directions. However, the above-mentioned co-flow rotary kiln can perform treatment at high temperatures more evenly and in a shorter time than a counter-flow type, making it more suitable for waste treatment.

[0003] Incidentally, conventionally, fossil fuels such as heavy oil and city gas have been used as fuel for the heating burners of co-flow rotary kilns.

[0004] JP 2010-216763 A

[0005] However, in recent years, CO ２ Due to issues such as climate change caused by increased CO2 emissions, restrictions on the use of fossil fuels are becoming stricter, making it desirable to use alternative fuels other than fossil fuels.

[0006] The present invention has been made in consideration of these points, and one of its objects is to provide a heat treatment system that can perform heat treatment of heated materials such as waste in a parallel flow rotary kiln without using fossil fuels as the main fuel.

[0007] A heat treatment system according to one embodiment of the present invention includes a pyrolysis furnace that pyrolyzes raw materials to produce pyrolysis products, and a co-flow rotary kiln that heats the heated material using the pyrolysis products produced in the pyrolysis furnace.

[0008] According to this aspect, in a co-flow rotary kiln, the material to be heated can be heated using the pyrolysis products produced in the pyrolysis furnace, so that the material to be heated can be heat-treated at high temperatures and in a short time without using fossil fuels as the main fuel.

[0009] The heat treatment system may further include a heat recovery device that recovers heat from the exhaust gas discharged from the rotary kiln.

[0010] The heat treatment system may further include a device that uses the heat of the exhaust gas discharged from the rotary kiln as a heat source for the pyrolysis furnace.

[0011] The object to be heated may be waste material.

[0012] The feedstock may include a biomass feedstock.

[0013] The heat treatment system may be configured such that the pyrolysis products produced in the pyrolysis furnace are sent to the rotary kiln without heat recovery.

[0014] According to the present invention, it is possible to provide a heat treatment system that can perform heat treatment of an object to be heated in a co-flow rotary kiln without using fossil fuel as the main fuel.

[0015] It is a schematic diagram showing an outline of the configuration of a heat treatment system, It is a schematic diagram showing an outline of another configuration of a heat treatment system, It is a schematic diagram showing an outline of another configuration of a heat treatment system.

[0016] Preferred embodiments of the present invention will be described below with reference to the drawings. The same elements are designated by the same reference numerals, and duplicate descriptions will be omitted. Furthermore, the dimensional ratios of the drawings are not limited to those shown. Furthermore, the following embodiments are examples for explaining the present invention, and the present invention is not limited to these embodiments.

[0017] 1 is a schematic diagram showing an example of the configuration of a heat treatment system 1 according to this embodiment. The heat treatment system 1 includes a pyrolysis furnace 10 that thermally decomposes a raw material to produce a pyrolysis product, a co-flow rotary kiln 11 that heats an object to be heated using the pyrolysis product produced in the pyrolysis furnace 10, a secondary combustion chamber 12 that performs secondary combustion of the exhaust gas discharged from the rotary kiln 11, and a heat recovery device 13 that recovers the heat of the exhaust gas discharged from the rotary kiln 11.

[0018] The pyrolysis furnace 10 is, for example, a circulating fluidized bed gasification apparatus, and has, for example, a main vessel 20 which is a furnace, a cyclone-type separation section 21, a first duct 22 connecting the upper part of the main vessel 20 with the upper part of the separation section 21, a second duct 23 connecting the lower part of the separation section 21 with the lower part of the main vessel 20, and a third duct 24 connecting the separation section 21 with the rotary kiln 11. In this specification, "upper" means upper in the vertical direction, and "lower" means lower in the vertical direction.

[0019] The main vessel 20 has a vertically long cavity, and while combustion / fluidizing air, circulating material, raw materials, etc. are introduced into the cavity, the raw materials are pyrolyzed to generate pyrolysis products. The main vessel 20 is formed with an inlet 25 for introducing the raw materials. The raw materials include, for example, non-fossil fuels such as woody biomass, waste tires, waste plastics, and waste materials such as sludge. The circulating material includes, for example, fine particles that flow at high temperatures, such as silica sand.

[0020] The main vessel 20 has an inner wall made of a fireproof material and has a structure that can prevent heat radiation to the outside. The raw material supply system (not shown) that introduces raw materials into the introduction part 25 includes, for example, a drying device, a hopper, a screw feeder, a conveyor, a raw material supply pipe, etc., and is configured to store raw materials dried in the drying device in the hopper, send the raw materials from the hopper to the conveyor by the screw feeder in predetermined amounts, transport the predetermined amount of raw materials from the conveyor to the raw material supply pipe, and introduce the raw materials into the main vessel 20 from the introduction part 25 of the raw material supply pipe.

[0021] A combustion air supply system (not shown) that introduces combustion air is also connected to the main vessel 20. The combustion air supply system includes, for example, an air supply pipe connected to the bottom of the main vessel 20, a dust removal device that separates dust and dirt from the combustion air, and a blower that pressurizes the combustion air.

[0022] The first duct 22 can send a high-temperature fluid containing pyrolysis products, circulating material, and impurities from the top of the main vessel 20 to the top of the separation section 21. The impurities here include fine particles of the circulating material that have been powdered and fly ash.

[0023] The separation section 21 swirls the high-temperature fluid sent from the pyrolysis furnace 10 and can separate the circulating material from the high-temperature fluid by centrifugal separation.

[0024] The second duct 23 can return the circulating material separated in the separation section 21 from the bottom of the separation section 21 to the bottom of the main vessel 20. The third duct 24 can send the high-temperature fluid containing impurities and pyrolysis products including fuel gas, from which the circulating material has been removed, to a first end (described below) of the rotary kiln 11. Thus, the pyrolysis furnace 10 is configured so that the pyrolysis products generated in the pyrolysis furnace 10 are sent to the rotary kiln 11 without heat recovery (without lowering their temperature) by a heat exchanger or the like.

[0025] The co-flow rotary kiln 11 has a cylindrical rotary furnace 40 with a first end 41 at one axial end and a second end 42 at the other axial end. The rotary kiln 11 is inclined, for example, so that the first end 41 is higher than the second end 42. The rotary kiln 11 has a drive unit 50 that can rotate the rotary furnace 40 around its axis. The co-flow rotary kiln 11 has a shorter overall axial length than a counter-flow rotary kiln, and is configured, for example, so that the ratio (L / D) of the overall axial length L to the cylindrical diameter D is approximately 3 to 5.

[0026] The first end 41 is connected to the third duct 24, forming a first inlet 60 for fuel gas. The first end 41 is also formed with a second inlet 61 for introducing the object to be heated. For example, a conveyor-equipped delivery mechanism (not shown) for delivering the object to the second inlet 61 is connected to the second inlet 61. The first inlet 60 is located higher or lower than the second inlet 61. The object to be heated is, for example, waste. The second end 42 serves as an outlet for exhaust gas and is connected to the lower part of the secondary combustion chamber 12. The second end 42 may also be connected to a recovery / delivery device for recovering and delivering fluids discharged from the rotary kiln 11.

[0027] The secondary combustion chamber 12 has a vertically long main body, and a heating burner (not shown) is attached to the bottom of the body. The secondary combustion chamber 12 also has a device for supplying substances that promote the secondary combustion of gas and substances that promote the decomposition of gas. For example, the secondary combustion chamber 12 is provided with a heating burner and an air supply unit. The secondary combustion chamber 12 and the heat recovery device 13 are connected by a fourth duct 70.

[0028] The heat recovery device 13 has, for example, a boiler. The heat recovered by the heat recovery device 13 can be used, for example, as a heat source for the pyrolysis furnace 10. As an example, the heat recovery device 13 has a duct through which the exhaust gas flows, and has multiple heat exchangers inside the duct. The heat exchanger has, for example, heat transfer tubes with fins on their surfaces, and water or steam can be passed through the heat transfer tubes to perform heat exchange between the heat transfer tubes inside the duct and the exhaust gas. Note that, as described below, steam generated by recovering the heat from the exhaust gas can be used as a heat source for heating the combustion air in the pyrolysis furnace 10.

[0029] The heat treatment system 1 configured as described above performs the following heat treatment. In the pyrolysis furnace 10, biomass or waste materials are pyrolyzed to generate pyrolysis products, which are then sent to the separation section 21. Within the main vessel 20, combustion and fluidization air introduced through the inlet 25 fluidizes solid materials, including the raw materials and circulating materials. The flowing raw materials are combusted at temperatures ranging from 800 to 900°C, for example, to generate pyrolysis products. In the separation section 21, the circulating materials are separated by centrifugal separation. The separated circulating materials are returned to the pyrolysis furnace 10. The pyrolysis products, including fuel gas, from which the circulating materials have been removed, are sent to the first end 41 of the co-flow rotary kiln 11. In the rotary kiln 11, while the rotary kiln 40 is rotating around its axis, the pyrolysis products are introduced through the first inlet 60 at the first end 41, and the waste material to be heated is introduced through the second inlet 61 at the first end 41. The material to be heated is then heat-treated by the pyrolysis products.

[0030] Here, by positioning the first introduction section 60 at a lower position than the second introduction section 61, the pyrolysis products from the separation section 21 are introduced from the bottom of the rotary kiln 11 and are thoroughly mixed with the heated material within the rotary kiln 11, enabling efficient heating treatment.

[0031] In the rotary kiln 11, materials to be heated are incinerated, melted, or roasted. Materials resulting from the heat treatment in the rotary kiln 11, such as materials produced by incineration, melting, or roasting, 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 the exhaust gas 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, the material to be heated can be heated in the parallel-flow rotary kiln 11 using the pyrolysis products produced in the pyrolysis furnace 10. This allows the material to be heat-treated at high temperatures and in a short time without using fossil fuels. Furthermore, the pyrolysis furnace 10 can continuously and stably produce pyrolysis products, and the pyrolysis products supplied from the pyrolysis furnace 10 are suitable for the parallel-flow rotary kiln 11, which performs heat treatment at high temperatures and in a short time. In the parallel-flow rotary kiln 11, the high-temperature pyrolysis products from the pyrolysis furnace 10 and the material to be heated are introduced through the same end 41. Therefore, the pyrolysis products immediately contact the material to be heated while still at a high temperature, allowing the material to be heat-treated efficiently and in a short time. Furthermore, the high-temperature fluid sent from the pyrolysis furnace 10 to the rotary kiln 11 may contain impurities such as powdered circulating material and fly ash, but these can be treated together with the material to be heated in the rotary kiln 11. Furthermore, the char and fine particles contained in the high-temperature fluid generated in the pyrolysis furnace 10 have a higher radiant heat effect due to light emission than fossil fuels such as city gas, and are efficiently heated in the rotary kiln 11. The co-flow rotary kiln 11 may also be equipped with a recovery section that recovers impurities sent from the pyrolysis furnace 10.

[0034] When biomass raw materials are used as raw materials, CO ２ This can significantly reduce the generation of harmful gases. In addition, the amount of gas treatment equipment required to neutralize the generated gases can be minimized.

[0035] Since the heat treatment system 1 is equipped with a heat recovery device 13, it is possible to effectively utilize the heat of the high-temperature exhaust gas discharged when using a co-flow rotary kiln 11, thereby realizing a heat treatment system 1 with high overall thermal efficiency.

[0036] The heat treatment system 1 is configured so that the pyrolysis products produced in the pyrolysis furnace 10 are sent to the rotary kiln 11 without heat recovery, which increases the amount of heat (lower heating value + gas sensible heat) introduced into the rotary kiln 11, making it easier to raise the temperature of the rotary kiln 11. In addition, heat from the exhaust gas of the rotary kiln 11 is recovered to preheat the combustion and fluidization air of the pyrolysis furnace 11, allowing for sufficient heat recovery and preheating of the combustion and fluidization air.

[0037] The heat treatment system 1 may include a device that uses 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 FIG. 2 , the heat treatment system 1 may recover the heat of the exhaust gas using steam and use the steam to heat the combustion air (combustion / fluidization air) for the pyrolysis furnace 10. In this case, the heat treatment system 1 includes a combustion air inlet duct 80 that leads to the main vessel 20 of the pyrolysis furnace 10, an air preheater 81 provided in the inlet duct 80, and a steam duct 82 that sends steam from the heat recovery device 13 to the air preheater 81. The steam from which the heat of the exhaust gas has been recovered by the heat recovery device 13 is sent to the air preheater 81 through the steam duct 82, and heat exchange occurs between the steam and the combustion air in the air preheater 81, resulting in the high-temperature combustion air being introduced into the main vessel 20 of the pyrolysis furnace 10 through the inlet duct 80. In this case, the heat remaining in the co-flow rotary kiln 11 can be used in the pyrolysis furnace 10, further increasing the thermal efficiency of the heat treatment system 1. In this example, the device that uses the heat of the exhaust gas discharged from the rotary kiln 11 as a heat source for the pyrolysis furnace 10 is composed of, for example, a heat recovery device 13, an inlet duct 80, an air preheater 81, and a steam duct 82.

[0038] 3, the heat treatment system 1 may also perform heat exchange of the exhaust gas heat between the gas and air, and use the air as combustion air for the pyrolysis furnace 10. In this case, the heat treatment system 1 may include, for example, an air preheater 90 connected to the fourth duct 70, an introduction duct 91 for introducing combustion air into the air preheater 90, and an introduction duct 92 for introducing the combustion air from the air preheater 90 into the pyrolysis furnace 10. Heat is exchanged between the exhaust gas discharged from the co-flow rotary kiln 11 and the combustion air introduced into the air preheater 90 through the introduction duct 91, and the high-temperature combustion air from the air preheater 90 is introduced into the main vessel 20 of the pyrolysis furnace 10 through the introduction duct 92. In this case, the heat remaining in the co-flow rotary kiln 11 can be used in the pyrolysis furnace 10, further increasing the thermal efficiency of the heat treatment system 1. In this example, the device that uses the heat of the exhaust gas discharged from the rotary kiln 11 as a heat source for the pyrolysis furnace 10 is composed of, for example, an air preheater 90 and introduction ducts 91 and 92 .

[0039] In the above embodiment, the heat recovery device 13 is a boiler, but it may be any other device that recovers heat from exhaust gas. The heat treatment system 1 is equipped with the secondary combustion chamber 12 and the heat recovery device 13, but the present invention can also be applied to a heat treatment system that does not include the secondary combustion chamber 12 or the heat recovery device 13. In the above embodiment, the heat treatment system 1 does not use any fossil fuel, but the present invention can also be applied to a heat treatment system that uses fossil fuel as auxiliary fuel.

[0040] The heat treatment system 1 is not only used to incinerate waste in a co-flow rotary kiln 11, but may also be used to melt waste to extract reusable metals, or to sinter waste to smelt metals. That is, the rotary kiln 11 can be used as an incinerator or melting furnace for industrial waste, a reduction furnace for waste containing metallic resources such as electric furnace dust, a roasting furnace for waste containing metallic resources such as spent catalysts and batteries, or a melting furnace for waste electronic circuit boards. Furthermore, the heat treatment system 1 is not limited to waste treatment, and may also be used for processes such as pretreatment of iron and steel ore and non-ferrous ore.

[0041] INDUSTRIAL APPLICABILITY The present invention is useful in providing a heat treatment system that can perform heat treatment such as waste treatment in a co-flow rotary kiln without using fossil fuels as the main fuel.

[0042] 1 Heat treatment system 10 Pyrolysis furnace 11 Co-flow rotary kiln 12 Secondary combustion chamber 13 Heat recovery device

Claims

1. A heat treatment system comprising: a pyrolysis furnace that thermally decomposes a raw material to produce a pyrolysis product; and a co-flow rotary kiln that heats an object to be heated using the pyrolysis product produced in the pyrolysis furnace.

2. The heat treatment system according to claim 1, further comprising a heat recovery device for recovering heat from the exhaust gas discharged from the rotary kiln.

3. The heat treatment system according to claim 1 or 2, further comprising a device that uses the heat of the exhaust gas discharged from the rotary kiln as a heat source for the pyrolysis furnace.

4. A heat treatment system according to any one of claims 1 to 3, wherein the object to be heated is waste.

5. A heat treatment system according to any one of claims 1 to 4, wherein the raw material includes a biomass raw material.

6. The heat treatment system according to any one of claims 1 to 5, wherein the pyrolysis product produced in the pyrolysis furnace is sent to the rotary kiln without heat recovery.