A negative carbon thermal cycle upgrading furnace and its application

Abstract

This invention provides a negative carbon thermal circulation upgrading furnace and its application, relating to the field of industrial solid waste treatment technology. The upgrading furnace includes at least three assemblable unit modules, each comprising a furnace body, multiple horizontally inserted U-shaped pipes, an air inlet main pipe, and an exhaust main pipe. The furnace body has a rectangular cross-section, with opposing through holes on the front and rear walls. The U-shaped pipes, including U-shaped air inlet pipes and U-shaped air outlet pipes, are inserted into these through holes. The U-shaped air inlet pipes are connected to the air inlet main pipe, and the U-shaped air outlet pipes are connected to the exhaust main pipe. Based on this main body, flue gas is introduced or discharged through the horizontally inserted U-shaped pipes, enabling flexible control of material drying, internal combustion, reheating, and cooling within the furnace. This invention also provides applications of the upgrading furnace. Through modular furnace design and a high-efficiency flue gas circulation system, this invention achieves low-energy, high-value treatment of various solid wastes, ultimately achieving a negative carbon target.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste treatment technology, specifically to a negative carbon thermal circulation upgrading furnace and its application. Background Technology

[0002] With the continuous advancement of industrialization and urbanization in my country, the output of various high-calorific-value solid wastes has increased dramatically, including coal gangue, gasification slag, oil shale, oil sludge, coal slime, and oily sludge. These solid wastes not only occupy vast amounts of land resources, but their heavy metals and harmful organic compounds, after long-term storage, are easily leachated by rainwater and weathered by nature, causing serious pollution to the soil, groundwater, and surrounding ecological environment. Furthermore, these wastes pose a risk of spontaneous combustion and release harmful gases, placing enormous pressure on remediation efforts.

[0003] Currently, the main methods for treating this type of solid waste containing calorific value include open-air stockpiling, landfilling, and traditional energy recovery. Stockpiling and landfilling have significant drawbacks and have become unsustainable disposal routes. Regarding energy recovery, mainstream technologies such as circulating fluidized bed (CFB) boiler co-firing and rotary kiln incineration, while capable of recovering some calorific value, generally suffer from the following technical bottlenecks:

[0004] (1) Low energy efficiency and high operating costs: In order to maintain stable combustion, the above technologies often require the addition of a large amount of auxiliary fuel (such as coal and natural gas). Their own calorific value cannot be efficiently utilized, and self-sustaining combustion cannot be achieved, resulting in poor economic efficiency.

[0005] (2) Low product value and risk of secondary pollution: The ash residue produced after incineration has low activity and unstable quality, and can usually only be used as low-value-added building materials or directly landfilled, failing to achieve high-value utilization. At the same time, if the combustion process is not properly controlled, dioxins and NO are easily generated. x Secondary pollutants such as SO2 are difficult to treat, and the treatment costs are high.

[0006] (3) Large carbon emissions make it difficult to meet low-carbon requirements: Traditional incineration treats solid waste as fuel, and its combustion process directly emits a large amount of carbon dioxide, which is included in the national total carbon emissions, facing huge carbon emission reduction pressure. Under the background of green and low-carbon goals, the sustainability of this path faces severe challenges.

[0007] On the other hand, the building materials industry is actively seeking a green transformation of raw materials, resulting in strong demand for ceramic raw materials, active admixtures, and lightweight aggregates. If these building materials could be prepared using solid waste, it would be possible to "treat waste with waste and turn waste into treasure." However, existing technologies struggle to simultaneously address the three core challenges of efficient temperature field control for quality improvement, reducing auxiliary fuel consumption, and achieving high-performance products.

[0008] Therefore, there is an urgent need in this field for an innovative treatment technology and equipment that can fully utilize the calorific value of solid waste to achieve a stable and efficient heat treatment process with very low or no auxiliary fuel. At the same time, the process should be able to precisely control the thermal environment, transform solid waste into high-value building material raw materials, and ultimately achieve negative carbon benefits overall by utilizing waste heat. That is, not only should carbon emissions during solid waste treatment be avoided from being included in total carbon emissions, but carbon emissions should also be indirectly reduced by replacing fossil energy, thereby truly opening up a technical path for the resource utilization, high-value utilization, and low-carbonization of solid waste with calorific value. Summary of the Invention

[0009] This invention provides a negative carbon thermal cycle upgrading furnace and its application to solve the technical problems of low energy efficiency, inability to control the internal combustion process, low product value, difficulty in burning carbon, and difficulty in realizing the secondary ash resource utilization, high value and low carbonization in existing vertical furnace combustion technology.

[0010] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0011] A negative carbon thermal circulation upgrading furnace includes at least three assemblable unit modules. Each assemblable unit module includes a furnace body, multiple U-shaped pipes horizontally inserted into the furnace body, an air inlet main pipe, and an exhaust main pipe. The furnace body has a rectangular cross-section, and the front arm and rear wall of the furnace body have opposing through holes. The U-shaped pipes can be inserted into the through holes. Each U-shaped pipe includes a U-shaped air inlet pipe and a U-shaped air outlet pipe. The U-shaped air inlet pipe is connected to the air inlet main pipe, and the U-shaped air outlet pipe is connected to the exhaust main pipe. Based on the main body of the equipment, flue gas is introduced or discharged through the horizontally inserted U-shaped pipes, thereby achieving flexible control of material drying, internal combustion, reheating, and cooling within the furnace.

[0012] Preferably, the cross-section of the U-shaped pipe is a pentagon with a rectangular lower section and a triangular upper section, and airflow holes are provided on the sides and bottom of the U-shaped pipe.

[0013] Preferably, the upgrading furnace is assembled from three assemblable unit modules from top to bottom, wherein the first assemblable unit module is a drying section, the second assemblable unit module is an ignition section and a roasting section, and the third assemblable unit module is a cooling section.

[0014] Preferably, the first assembleable unit module has an air inlet header a and an exhaust header a on its side, the second assembleable unit module has an air inlet header b and an exhaust header b on its side, and the third assembleable unit module has an air inlet header c and an exhaust header c on its side. The air inlet of the air inlet header b is connected to the natural gas combustion chamber.

[0015] Preferably, the air inlet of the air inlet main pipe c is connected to a low-temperature gas or normal-temperature gas fan, the air outlet of the smoke exhaust main pipe c is connected to the air inlet of the air inlet main pipe a, and the smoke exhaust main pipe a is connected to the atmosphere.

[0016] Preferably, the air inlet of the air inlet main pipe c is connected to a low-temperature gas or normal-temperature gas fan, the air outlet of the smoke exhaust main pipe c is connected to the air inlet of the air inlet main pipe a, the smoke exhaust main pipe a is connected to the air inlet main pipe b, and the smoke exhaust main pipe b is connected to the air inlet main pipe a.

[0017] An application of the negative carbon thermal cycle upgrading furnace according to the present invention includes the following steps:

[0018] S1. Crush the calorific value-containing solid waste into solid particles with an average particle size of 10-35mm;

[0019] S2. The solid particles are added into the furnace cavity from the top of the furnace at a feeding rate of 1-5 tons / hour.

[0020] S3. Hot air is discharged into the drying section at a volume of 80-120 cubic meters per hour through the U-shaped air inlet duct. The solid particles are preheated and dried by the low-temperature hot air in the drying section.

[0021] S4. The dried material flows down to the ignition section and the roasting section, where it is ignited by the high-temperature ignition gas and begins to burn. The ignition temperature is between 700-1100℃.

[0022] S5. The ignited material completes full combustion and phase transformation during the roasting process to obtain high-temperature products; low-temperature hot air is discharged through the U-shaped air inlet pipe, and high-temperature hot air is extracted to adjust the internal combustion temperature of the material in the combustion zone and control the internal combustion temperature to 1000-1200℃.

[0023] S6. The high-temperature product is cooled by cold air in the cooling section and then screened to obtain the upgraded raw material.

[0024] The low-temperature hot air entering the S3 drying section comes from the hot air discharged after cooling in S6; the low-temperature hot air entering S5 comes from the hot air discharged after cooling in S6, or the hot air and the high-temperature humid air discharged from the S3 drying section, and the 400-600℃ hot air discharged from the S5 high temperature section is circulated to the ignition section as a supplementary heat for the combustion zone; part of it is circulated to the high-temperature cooling section to increase the material burnout temperature; the remaining excess hot air is used as waste heat output.

[0025] Preferably, the calorific value-containing solid waste is one or more of coal gangue, gasification slag, clay, coal slime, and oil sludge.

[0026] Preferably, the calorific value of the solid waste is 600-1500 kcal / kg.

[0027] Preferably, the improving raw material can be used as an active blending material, ceramic raw material, lightweight ceramsite, or ecological restoration material.

[0028] The upgrading furnace in this invention can flexibly adjust the number of assembleable unit modules in each functional section and the circulation ratio of high-temperature flue gas and low-temperature flue gas, and can process a variety of solid wastes such as coal gangue, gasification slag, oil shale, oil sludge, coal sludge, and oily sludge with different calorific values, moisture contents, and compositions, and can control the performance of the final product.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] (1) The core of this invention lies in the adoption of standardized and modular design.

[0031] The furnace body is divided into high-temperature and low-temperature unit modules with different temperature resistance levels. These modules have uniform external dimensions and connection interfaces, and can be flexibly configured like "building blocks" in terms of the height and combination of the drying section, ignition section, roasting section, and cooling section according to the characteristics of the material to be processed (such as calorific value, moisture content, and target product). This design gives a single furnace type extremely strong raw material adaptability and process control capabilities. By adjusting the number and arrangement of modules, it can economically and efficiently process solid waste types with different calorific values ​​and stably produce building materials of different grades, such as eco-soil and ceramic raw materials.

[0032] (2) Strong internal airflow system adjustment capability;

[0033] Traditional vertical shaft furnaces are characterized by low investment and low operating costs, but their biggest problems are poor ability to adjust internal temperature and atmosphere, poor material homogeneity, and limited controllable methods. This invention, combining the aforementioned modular design, specifically incorporates multiple U-shaped pipes horizontally inserted into the furnace body, along with corresponding air inlet and exhaust manifolds. This U-shaped pipe design facilitates the top-to-bottom flow of materials and convective heat exchange with the flue gas.

[0034] Based on the aforementioned modular furnace body, flue gas is introduced or discharged through horizontally inserted U-shaped pipes, and airflow is evenly distributed in the corresponding functional sections of the furnace body. Furthermore, by adjusting the temperature, volume, and oxygen content of the airflow, flexible control of the drying, internal combustion, reheating, and cooling processes of materials inside the furnace can be achieved. In particular, by evenly discharging low-temperature air into the ignition and roasting section and extracting high-temperature air, further heating in the combustion section is avoided, thus controlling the problem of material overheating and adhesion under high calorific value conditions.

[0035] (3) High-efficiency graded flue gas circulation and energy cascade utilization system;

[0036] This invention innovatively constructs a dual-circulation system of low-temperature and high-temperature flue gas working in synergy, achieving tiered energy utilization. The low-temperature circulation directs the 200-450°C hot air generated in the cooling section to the drying section, fully utilizing waste heat for pre-drying the materials, significantly reducing the system's total energy consumption; some of the hot air can also be used as combustion air to supplement the roasting section. The high-temperature circulation mixes the exhaust gas from the drying section with some of the high-temperature roasting flue gas and then returns it to the high-temperature roasting section, forming a highly efficient internal thermal circulation. This significantly reduces the external fuel consumption required to maintain the high temperature, which is key to achieving "self-sustaining combustion" of the materials and reducing operating costs.

[0037] (4) Integrated waste heat recovery and negative carbon pathway realization;

[0038] This invention integrates a high-temperature waste heat recovery device into the cooling section, drawing high-quality hot air (500-800℃) generated after product cooling out of the furnace for power generation or external heating, achieving efficient external energy utilization. This not only improves the overall system's economics but, more importantly, establishes a clear "carbon-negative" pathway: on one hand, the internal heat in solid waste is not included in carbon emissions during the conversion into building materials; on the other hand, the recovered waste heat steam or electricity can replace external fossil fuels, thus indirectly achieving carbon reduction. Ultimately, solid waste treatment is transformed from a traditional "energy-consuming and carbon-emitting" process into a "productive-producing and carbon-negative" process. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a negative carbon heat cycle upgrading furnace.

[0040] Figure 2 This is a schematic diagram of the structure of a U-shaped pipe;

[0041] Figure 3 A schematic diagram of the gas circulation in a negative carbon thermal cycle upgrading furnace;

[0042] Figure 4 Another schematic diagram of the gas circulation in a negative carbon thermal cycle upgrading furnace;

[0043] Figure 5 This is another schematic diagram of the gas circulation in a negative carbon thermal cycle upgrading furnace.

[0044] in:

[0045] First assemblable unit module 1, air inlet main pipe a 11, and exhaust main pipe a 12; second assemblable unit module 2, air inlet main pipe b 21, exhaust main pipe b 22; third assemblable unit module 3, air inlet main pipe c 31, exhaust main pipe c 32; furnace body 4, U-shaped pipe 5, U-shaped air inlet pipe 51, U-shaped exhaust pipe 52, airflow hole 53, through hole 6, natural gas combustion chamber 7, valve 8. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] like Figure 1-3 This embodiment provides a negative carbon thermal circulation upgrading furnace, which is assembled from three assemblable unit modules from top to bottom. The first assemblable unit module 1 is a drying section, the second assemblable unit module 2 is an ignition section and a roasting section, and the third assemblable unit module 3 is a cooling section. Preferably, the number of assemblable unit modules required for each functional section can be increased or decreased according to the characteristics of the raw materials. The first assemblable unit module 1 includes a furnace body 4, multiple U-shaped pipes 5 horizontally inserted into the furnace body 4, an air inlet main pipe a 11, and an exhaust main pipe a 12. The U-shaped air inlet pipe 51 is connected to the air inlet main pipe a 11, and the U-shaped exhaust pipe 52 is connected to the exhaust main pipe a 12.

[0049] The second assemblable unit module 2 includes a furnace body 4, multiple U-shaped pipes 5 that are horizontally inserted into the furnace body 4, an air inlet main pipe b21, and a smoke exhaust main pipe b22. The U-shaped air inlet pipe 51 of this part is connected to the air inlet main pipe b21, and the U-shaped air exhaust pipe 52 is connected to the smoke exhaust main pipe b22.

[0050] The third assemblable unit module 3 includes a furnace body 4, multiple U-shaped pipes 5 that are horizontally inserted into the furnace body 4, an air inlet main pipe c31, and a smoke exhaust main pipe c32. The U-shaped air inlet pipe 51 of this part is connected to the air inlet main pipe c31, and the U-shaped air exhaust pipe 52 is connected to the smoke exhaust main pipe c32.

[0051] The furnace body 4 in the first, second, and third assembleable unit modules 1 and 2 all has a rectangular cross-section. The front arm and rear wall of the furnace body 4 each have facing through holes 6. The shape of the through holes 6 should conform to the shape of the U-shaped pipe 5 so that the U-shaped pipe 5 can be inserted parallel to the through holes 6. The vertical and horizontal spacing and density of the U-shaped pipe 5 are determined based on the number of airflow circulations. Furthermore, the cross-section of the U-shaped pipe 5 can be a pentagon with a rectangular lower section and a triangular upper section, and the sides and bottom of the U-shaped pipe 5 are provided with airflow holes 53. Figure 2 As shown.

[0052] The U-shaped pipe 5 can be divided into a U-shaped air inlet pipe 51 and a U-shaped air outlet pipe 52 set at the same horizontal height. For example, in the same assemblable unit module, the upper U-shaped pipe 5 is used for air inlet, and the lower U-shaped pipe 5 is used for exhausting the flue gas in the furnace. The purpose of controlling the air direction is achieved by setting fans at the corresponding positions.

[0053] The upper part of the U-shaped pipe 5 inside the furnace has a triangular structure to ensure that the material can flow smoothly downwards; the lower part of the U-shaped pipe 5 is relatively loose after the material passes through the pipe, ensuring that the airflow from the equidistant openings at the lower part of the U-shaped pipe 5 can pass through the material evenly.

[0054] The air inlet of the main air inlet pipe b 21 is connected to the natural gas combustion chamber 7. The high-temperature gas generated in the natural gas combustion chamber 7 enters the main air inlet pipe b 21, and then enters the U-shaped air inlet pipe 51 connected to the main air inlet pipe b 21. The high-temperature gas is then injected into the furnace cavity through the airflow holes 53 at the bottom of the U-shaped air inlet pipe 51 to increase the gas temperature entering the ignition section, ensuring it is between 600-1000℃. The flue gas from the ignition and roasting sections is drawn in by the U-shaped exhaust pipe 52 in this section and collected in the exhaust pipe b 22. The exhaust pipe b 22 can be connected to the main air inlet pipe a 11, allowing the high-temperature flue gas from the ignition and roasting sections to be input into the drying section for material drying.

[0055] The air inlet of the main air inlet pipe c31 is connected to a low-temperature gas or normal-temperature gas fan, and the air outlet of the exhaust pipe c32 is connected to the air inlet of the main air inlet pipe a11, thereby achieving waste heat drying of particulate materials. The hot air temperature in the hot air main pipe 1 is between 200-450℃. The exhaust pipe a12 is connected to the main air inlet pipe b21, and the flue gas in the exhaust pipe a12 circulates to the middle ignition section and roasting section to replenish the oxygen during the internal combustion process of the material. A flue gas flow control valve can be designed here as needed to control the flow rate of flue gas from the exhaust pipe a12 into the main air inlet pipe b21.

[0056] Example 2

[0057] Combination Figure 4 Based on Example 1, the exhaust header a 12 can also be connected to the atmosphere, and the low-temperature gas in the drying section can be discharged directly after dust removal to meet the emission standards.

[0058] Example 3

[0059] Combination Figure 5Based on Example 1, the hot air discharged from the upper drying section with a portion of the high-temperature flue gas generated in the ignition and roasting sections is mixed in proportion by valve 8 and then sent back into the ignition and roasting sections to form a high-temperature internal circulation, maintain the high-temperature environment required for roasting, and reduce external fuel consumption.

[0060] In another embodiment, preferably, the hot air discharged from the upper drying section and part of the high-temperature flue gas generated in the ignition section and roasting section are directly connected to the energy storage device to collect or utilize this part of the heat source.

[0061] In another embodiment, preferably, when the temperature of the gas discharged from the flue gas header c 32 is greater than 500°C, part of the flue gas can also be drawn out to produce steam through a waste heat boiler or to preheat air through a heat exchanger for power generation or external process heating, thereby achieving efficient external utilization of energy.

[0062] It is important to emphasize that the furnace body 4, related I-shaped pipes 5, and other pipes in the ignition and roasting sections should be made of refractory materials with a temperature resistance exceeding 1300℃. For example, the I-shaped pipes 5 in the high-temperature section can be made of high-temperature resistant alloy steel. The materials in other areas should have a temperature resistance exceeding 900℃. To achieve airflow circulation, fans can be added at appropriate locations.

[0063] Example 4

[0064] An application of a negative carbon thermal cycle upgrading furnace as described in Example 1 includes the following steps:

[0065] S1. Crush coal gangue with a calorific value of 900 kcal / kg into solid particles with an average particle size of 35 mm.

[0066] S2. The solid particles are continuously added into the furnace cavity from the top of the furnace at a continuous feeding rate of 5 tons / hour, and the ignition switch of the natural gas combustion chamber 7 is turned on.

[0067] S3. Solid particles are preheated and dried by low-temperature hot air in the drying section. The moisture content of the solid particles is 10%. Hot air is introduced through the U-shaped air inlet pipe 51 in this section, with a corresponding air volume of 100 cubic meters / hour. The air temperature entering the furnace at this stage is 180°C, and the temperature of the humid air discharged is 90°C.

[0068] S4. The dried material flows down to the ignition section and the roasting section, where it is ignited by the high-temperature ignition gas and begins to burn. The ignition temperature is 900℃.

[0069] S5. The ignited material completes full combustion and phase transformation during the roasting process to obtain high-temperature products; low-temperature hot air is discharged through the I-shaped pipe (because the material will increase the temperature inside the furnace during the combustion process, low-temperature hot air can be introduced to regulate the temperature inside the furnace cavity), and high-temperature hot air is extracted to adjust the internal combustion temperature of the material in the combustion zone, control the internal combustion temperature at 1080℃, and the high-temperature exhaust hot air temperature at 500℃.

[0070] S6. Cold air is blown in through the U-shaped air inlet pipe 51 in this section. The high-temperature product is cooled by the cold air in the cooling section and hot air is discharged. The hot air temperature is 350°C. After screening, the upgraded raw material is obtained, and its residual carbon content is reduced from 12.34% to 0.48%, and its sulfur oxide content is reduced from 1.23% to 0.25%. It can be used as a ceramic raw material.

[0071] Example 5

[0072] An application of a negative carbon thermal cycle upgrading furnace as described in Example 2 includes the following steps:

[0073] S1. Coal gangue-gasification slag-clay ceramsite with a calorific value of 1200 kcal / kg and an average particle size of 15 mm (made by grinding coal gangue, gasification slag and clay in a ratio of 2:2:1 and then granulating).

[0074] S2. The solid particles are intermittently added into the furnace cavity from the top of the furnace at an intermittent feeding rate of 1 ton / hour, and the ignition switch of the natural gas combustion chamber 7 is turned on.

[0075] S3. Solid particles are preheated and dried by low-temperature hot air in the drying section. The moisture content of the solid particles is 15%. Hot air is discharged through the U-shaped air inlet pipe 51 in this section, with a corresponding air volume of 80 cubic meters / hour. The temperature of the air entering the furnace is 220°C, and the temperature of the humid air discharged is 130°C.

[0076] S4. The dried material flows down to the ignition section and the roasting section, where it is ignited by the high-temperature ignition gas and begins to burn. The ignition temperature is 850℃.

[0077] S5. The ignited material completes full combustion and phase transformation during the roasting process to obtain high-temperature products; low-temperature hot air is discharged through the U-shaped pipe and high-temperature hot air is extracted to adjust the internal combustion temperature of the material in the combustion zone, control the internal combustion temperature at 1100℃, and the high-temperature exhaust hot air temperature at 550℃.

[0078] S6. Cold air is blown in through the U-shaped air inlet duct 51 in this section. The high-temperature product is cooled by the cold air in the cooling section and hot air is discharged. The hot air temperature is 480℃. After screening, the upgraded raw material is obtained. Its residual carbon content is reduced from 13.34% to 0.57%, and the sulfur oxide content is reduced from 0.98% to 0.13%. It can be used as an active composite material, lightweight ceramsite, or ecological restoration material.

[0079] Example 6

[0080] An application of a negative carbon thermal cycle upgrading furnace as described in Example 3 includes the following steps:

[0081] S1. Oil sludge-coal gangue-clay with a calorific value of 1500 kcal / kg and an average particle size of 16 mm (oil sludge, coal gangue and clay are ground and granulated in a dry basis mass ratio of 3:5:2).

[0082] S2. The solid particles are intermittently added into the furnace cavity from the top of the furnace at an intermittent feeding rate of 2 tons / hour, and the ignition switch of the natural gas combustion chamber 7 is turned on.

[0083] S3. Solid particles are preheated and dried by low-temperature hot air in the drying section; the moisture content of the solid particles is 12%, and hot air is discharged through the U-shaped pipe with a corresponding air volume of 90 cubic meters / hour. The temperature of the air entering the furnace is 200℃, and the temperature of the humid air discharged is 110℃.

[0084] S4. The dried material flows down to the ignition section and the roasting section, where it is ignited by the high-temperature ignition gas and begins to burn. The ignition temperature is 700℃.

[0085] S5. The ignited material completes full combustion and phase transformation during the roasting process to obtain high-temperature products; low-temperature hot air is discharged through the U-shaped air inlet pipe 51 in this part, and high-temperature hot air is extracted to adjust the internal combustion temperature of the material in the combustion zone, control the internal combustion temperature at 1000℃, and the high-temperature exhaust hot air temperature at 600℃.

[0086] S6. Cold air is blown in through the U-shaped air inlet duct 51 of this section, and hot air is discharged. The temperature of the hot air is 700℃. The high-temperature product is cooled by the cold air in the cooling section. After screening, the upgraded raw material is obtained. Its residual carbon content is reduced from 10.43% to 0.33%, and the sulfur oxide content is reduced from 0.78% to 0.10%. It can be used as ceramic raw material, lightweight ceramsite, or ecological restoration material.

[0087] Example 7

[0088] An application of a negative carbon thermal cycle upgrading furnace as described in Example 2 includes the following steps:

[0089] S1. Coal gangue-coal slime ceramsite with a calorific value of 600 kcal / kg and an average particle size of 10 mm (made by grinding coal gangue and coal slime in a dry basis mass ratio of 4:1 and then granulating).

[0090] S2. The solid particles are continuously added into the furnace cavity from the top of the furnace at a continuous feeding rate of 3 tons / hour. The ignition switch of the natural gas combustion chamber 7 is turned on.

[0091] S3. Solid particles are preheated and dried by low-temperature hot air in the drying section. The moisture content of the solid particles is 12%. Hot air is discharged through the U-shaped air inlet pipe 51 in this section, with a corresponding air volume of 120 cubic meters / hour. The air temperature entering the furnace is 230°C, and the temperature of the humid air discharged is 125°C.

[0092] S4. The dried material flows down to the ignition section and the roasting section, where it is ignited by the high-temperature ignition gas and begins to burn. The ignition temperature is 1100℃.

[0093] S5. The ignited material completes full combustion and phase transformation during the roasting process, and the unloading time is controlled to obtain high-temperature products; low-temperature hot air is discharged through the U-shaped pipe, high-temperature hot air is extracted, the internal combustion temperature of the material in the combustion zone is adjusted, the internal combustion temperature is controlled at 1200℃, and the high-temperature exhaust hot air temperature is 400℃.

[0094] S6. Cold air is blown in through the U-shaped air inlet pipe 51 in this section. The high-temperature product is cooled by the cold air in the cooling section and hot air is discharged. The hot air temperature is 260℃. After screening, the upgraded raw material is obtained. Its residual carbon content is reduced from 11.27% to 0.35%, and its sulfur oxide content is reduced from 0.73% to 0.11%. It can be used as a ceramic raw material.

[0095] Comparative Example

[0096] The solid waste to be treated in this comparative example is the same as that in Example 4. A conventional vertical shaft furnace is used in this comparative example. The residual carbon content of the solid waste raw material after treatment in this comparative example is reduced from 12.34% to 3.48%, and the sulfur oxide content is reduced from 1.23% to 0.75%.

[0097] Conventional vertical shaft furnaces suffer from poor temperature and atmosphere adjustment capabilities, poor material homogeneity, and limited controllable methods, making effective regulation during sintering difficult and resulting in relatively high carbon content in the sintered material. A traditional vertical shaft furnace resembles a giant silo, with material flowing downwards and air blowing upwards or downwards. The entire furnace interior is a single unit, making independent adjustment of process conditions in specific areas impossible. Furthermore, due to its simple structure, airflow is prone to "short-circuiting" in areas of low resistance, leading to significant differences in temperature and airflow across different areas of the furnace. Simultaneously, operators can only macroscopically adjust a few parameters such as total airflow and total fuel volume, failing to address the complex and ever-changing conditions within the furnace. For example, if the calorific value of material suddenly increases in a certain area, the lack of effective local cooling methods can easily lead to "combustion overheating and adhesion." However, this patented vertical shaft furnace modification design achieves "refined, segmented" precise control of internal temperature, atmosphere, and material residence time, thereby optimizing the combustion process, improving combustion efficiency, and effectively avoiding carbon residue and adhesion problems.

[0098] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An application method of a negative carbon thermal circulation upgrading furnace, characterized in that, The negative carbon thermal circulation upgrading furnace includes at least three assemblable unit modules. Each assemblable unit module includes a furnace body, multiple U-shaped pipes inserted horizontally into the furnace body, an air inlet main pipe, and an exhaust main pipe. The furnace body has a rectangular cross-section. The front arm and rear wall of the furnace body have facing through holes. The U-shaped pipes can be inserted into the through holes. Each U-shaped pipe includes a U-shaped air inlet pipe and a U-shaped air outlet pipe. The U-shaped air inlet pipe is connected to the air inlet main pipe, and the U-shaped air outlet pipe is connected to the exhaust main pipe. Airflow holes are provided on the sides and bottom of the U-shaped pipes. The application method includes the following steps: S1. Crush solid waste with a calorific value of 600-1500 kcal / kg into solid particles with an average particle size of 10-35 mm. S2. The solid particles are added into the furnace cavity from the top of the furnace at a feeding rate of 1-5 tons / hour. S3. Hot air is discharged into the drying section at a volume of 80-120 cubic meters per hour through the U-shaped air inlet duct, and the solid particles are preheated and dried by the low-temperature hot air in the drying section. S4. The dried material flows down to the ignition section and the roasting section, where it is ignited by the high-temperature ignition gas and begins to burn. The ignition temperature is 700-1100℃. S5. The ignited material completes full combustion and phase transformation during the roasting process to obtain high-temperature products; low-temperature hot air is discharged through the U-shaped air inlet pipe, and high-temperature hot air is extracted to adjust the internal combustion temperature of the material in the combustion zone and control the internal combustion temperature to 1000-1200℃. S6. The high-temperature product is cooled by cold air in the cooling section and then screened to obtain the upgraded raw material.

2. The application method according to claim 1, characterized in that, The cross-section of the U-shaped pipe is a pentagon with a rectangular lower section and a triangular upper section.

3. The application method according to claim 2, characterized in that, The upgrading furnace is assembled from three modular units from top to bottom. The first modular unit is the drying section, the second modular unit is the ignition section and the roasting section, and the third modular unit is the cooling section.

4. The application method according to claim 3, characterized in that, The first assembleable unit module has an air inlet header a and an exhaust header a on its side, the second assembleable unit module has an air inlet header b and an exhaust header b on its side, and the third assembleable unit module has an air inlet header c and an exhaust header c on its side. The air inlet of the air inlet header b is connected to the natural gas combustion chamber.

5. The application method according to claim 3, characterized in that, The air inlet of the air inlet main pipe c is connected to a low-temperature gas or normal-temperature gas fan, the air outlet of the exhaust main pipe c is connected to the air inlet of the air inlet main pipe a, and the exhaust main pipe a is connected to the atmosphere.

6. The application method according to claim 3, characterized in that, The air inlet of the air inlet main pipe c is connected to a low-temperature gas or normal-temperature gas fan, the air outlet of the exhaust main pipe c is connected to the air inlet of the air inlet main pipe a, the exhaust main pipe a is connected to the air inlet main pipe b, and the exhaust main pipe b is connected to the air inlet main pipe a.

7. The application method according to claim 1, characterized in that, The solid waste is one or more of the following: coal gangue, gasification slag, coal slime, and oil sludge.

8. The application method according to claim 1, characterized in that, The upgrading raw materials are active blending materials, ceramic raw materials, or lightweight ceramsite.

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