Layered slow-release calcining device capable of maintaining spontaneous combustion of low-heating-value coal gangue

Abstract

The invention relates to the technical field of coal gangue recycling, in particular to a layered slow-release calcining device capable of maintaining spontaneous combustion of low-heating-value coal gangue, which comprises a kiln body, a feeding valve is mounted at the top of the kiln body, a discharging hopper is arranged at the lower part of the kiln body, and a discharging valve is mounted at the bottom of the discharging hopper. The portion, between the feeding valve and the discharging hopper, of the kiln body is divided into a plurality of air chambers through a plurality of discharging components, the lower portion of the kiln body is connected with the air inlet end of a third fan through a fifth air pipe, the air outlet end of the third fan is connected with the upper portion of the kiln body through a first air pipe, and the middle of the kiln body is connected with the air inlet end of a second fan through a fourth air pipe. The discharging hopper is connected with a fourth fan; the coal gangue moves downstream with the hot air on the upper portion of the kiln body and flows countercurrent with the hot air on the lower portion of the kiln body. According to the device disclosed by the invention, scientific and reasonable thermal regulation and raw material ratio are adopted, the heat value and mineral components of the device are fully utilized, and the dual purposes of resource utilization and environmental protection are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of coal gangue recycling, and in particular to a layered slow-release calcining device capable of maintaining spontaneous combustion of low-calorific value coal gangue. Background Art

[0002] Coal gangue is primarily composed of inorganic matter, containing a variety of oxides and minerals. Among these, SiO2 (silicon dioxide) and Al2O3 (aluminum oxide) are the primary oxide components, representing silicate and aluminosilicate minerals, respectively. It also contains oxides such as Fe2O3 (ferric oxide), CaO (calcium oxide), and MgO (magnesium oxide), as well as trace amounts of rare metal elements.

[0003] The mineral composition of coal gangue is complex and diverse, including clay minerals such as kaolinite, illite, chlorite, and montmorillonite, as well as silicate minerals such as quartz and feldspar. These mineral compositions determine the chemical stability and reactivity of coal gangue.

[0004] Gangue has a relatively low calorific value and cannot usually be used directly as a fuel. However, in some cases, it can be burned to recover the heat or for purposes such as power generation, but it requires pretreatment to improve its combustion efficiency. Summary of the Invention

[0005] In order to solve the defects in the prior art, the present invention provides a layered slow-release calcining device that can maintain spontaneous combustion of low calorific value coal gangue, which is specifically achieved through the following technical solutions: A layered slow-release calcining device capable of maintaining spontaneous combustion of low-calorific value coal gangue comprises a kiln body, a feed valve is installed on the top of the kiln body, a discharge hopper is provided at the bottom of the discharge hopper, a discharge valve is installed at the bottom of the discharge hopper, and a plurality of blanking components are installed from top to bottom on the kiln body between the feed valve and the discharge hopper, and the blanking components divide the kiln body into a plurality of air chambers, the lower part of the kiln body is connected to the air inlet end of the third fan through a fifth air duct, the air outlet end of the third fan is connected to the upper part of the kiln body through a first air duct, the middle part of the kiln body is connected to the air inlet end of the second fan through a fourth air duct, and the discharge hopper is connected to the fourth fan; the coal gangue moves downstream with the hot air at the upper part of the kiln body, and flows countercurrently with the hot air at the lower part of the kiln body.

[0006] A gap is left between two adjacent blanking parts.

[0007] The blanking component comprises an upper material guide hopper and a material guide pipe fixed at the bottom of the material guide hopper.

[0008] The guide hopper is in a trumpet shape, with an outer diameter of the top greater than that of the bottom, and an inner diameter of the top greater than that of the bottom; the inner diameter of the top of the guide hopper is equal to the inner diameter of the kiln body.

[0009] The material guide pipe is a hollow tubular structure with an equal diameter, and the inner diameter is equal to the inner diameter of the bottom of the material guide hopper.

[0010] An ignition chamber is fixedly installed on the outside of the discharge hopper. The ignition chamber is connected to the fourth fan through a sixth air duct. The ignition chamber is communicated with the discharge hopper through an ignition chamber air chamber.

[0011] A plurality of second air ducts are also installed on the kiln body, and the second air ducts are connected to the air outlet end of the first fan.

[0012] The feed valve and the discharge valve are both automatic valves.

[0013] The air outlet of the second fan is connected to the waste heat recovery system through a third air duct.

[0014] The fifth air duct is installed above the discharge hopper.

[0015] The technical solution of the present invention has the following advantages: The interior of the kiln is divided into multiple air chambers by the blanking components consisting of a guide hopper and a guide pipe. Combined with the multi-stage air duct layout of the first, second, and third fans, a stepped hot air circulation system is formed. In the drying and preheating section, the hot air moves downstream with the material, utilizing the 300-500°C residual heat to accelerate volatilization and analysis combustion while avoiding local high temperatures. In the decarbonization and calcination section, the hot air flows upward in a countercurrent, enhancing the contact efficiency between fixed carbon and oxygen for more complete combustion. The gap design between the air chambers and the layered air supply mechanism can dynamically adjust the temperature of each section to a stable range of 700-900°C, preventing the silicate components from overburning and hardening while ensuring the complete combustion of residual carbon. This solves the technical problem of excessive CO and CH4 emissions in the traditional countercurrent process.

[0016] By precisely matching the calorific value of the gangue (≥300 kcal / kg) with the stratified combustion structure, spontaneous combustion can be maintained without an external heat source. The vertical kiln layout and thermal insulation design significantly minimize heat loss. The 600-800°C hot air generated by combustion is pumped by a secondary fan to a waste heat recovery system for power generation or drying, significantly improving overall thermal efficiency. Furthermore, the cooling section utilizes countercurrent heat exchange, preheating the cold air before recycling it to the combustion zone, further reducing energy consumption.

[0017] Automatic control of the feed and discharge valves, combined with real-time feedback from temperature sensors, ensures continuous material flow and dynamic balance of thermal parameters. Stratified combustion fully oxidizes volatile matter and fixed carbon in stages, reducing combustible components in the exhaust by over 80%. Combined with waste heat recovery, this significantly reduces particulate matter and greenhouse gas emissions, meeting environmental regulations.

[0018] After pre-processing the coal gangue through crushing, the silica-alumina minerals are gradually converted into crystalline mullite through a low-temperature, slow-burning process. The resulting product can be directly used in building materials production. The precise temperature control of the combustion residue avoids the loss of activity caused by over-burning in traditional processes, significantly improving resource utilization.

[0019] The device of this invention utilizes a scientifically sound thermal system and raw material ratios to fully utilize the gangue's calorific value and mineral composition, achieving the dual goals of resource utilization and environmental protection. When the gangue's calorific value is ≥300 kcal / kg, this stratified combustion device can be used. The gangue's own calorific value sustains combustion, generating high-temperature hot air at 600-800°C for secondary waste heat utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 It is a structural schematic diagram of the present invention; In the figure, 1-kiln body, 2-feed valve, 3-guide hopper, 4-guide pipe, 5-first air duct, 6-second air duct, 7-first fan, 8-second fan, 9-third air duct, 10-fourth air duct, 11-third fan, 12-fifth air duct, 13-discharge hopper, 14-discharge valve, 15-sixth air duct, 16-fourth fan, 17-ignition chamber. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the modules or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0025] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] As attached Figure 1 As shown, the present invention provides a layered slow-release calcining device that can maintain the spontaneous combustion of low-calorific value coal gangue, including a vertical kiln body 1. The entire kiln body 1 is fixed to the ground to keep it stable, and the coal gangue is processed by feeding from the top and discharging from the bottom.

[0027] A feed port is provided at the top of the kiln body 1, on which a feed valve 2 is installed. The feed valve 2 can be an automatic valve that can cooperate with a feeder to achieve automatic feeding and maintain continuous operation of the entire device.

[0028] Several material-discharging components are fixedly mounted within the kiln body 1. These include a hopper 3 at the top and a guide tube 4 fixed to the bottom of the hopper 3. The hopper 3 is bell-shaped, with a larger outer diameter at the top than at the bottom, and a larger inner diameter at the top than at the bottom. The inner diameter of the top of the hopper 3 is equal to the inner diameter of the kiln body 1, ensuring that all the gangue above the hopper 3 falls into the hopper 3.

[0029] The top of the guide hopper 3 is fixedly connected to the inner wall of the kiln body 1. The guide hopper 3 divides the kiln body 1 into an air chamber. The air chamber can not only ensure that the coal gangue falls evenly, but also effectively hinder the upward flow of air.

[0030] The material guide pipe 4 is a hollow tubular structure of equal diameter, and its inner diameter is equal to the inner diameter of the bottom of the material guide hopper 3 .

[0031] Several drop components are arranged in a linear array and fixed in sequence, allowing the gangue to fall evenly without obstructing the flow of air. A gap is left between adjacent drop components, that is, a gap is left between the bottom of the guide pipe 4 of the drop component located above and the top of the guide hopper 3 of the discharge component located below.

[0032] like Figure 1As shown, four blanking components are installed in the kiln body 1, wherein the first blanking component and the second blanking component are located at the upper part of the kiln body 1, the third blanking component is located in the middle part of the kiln body 1, and the fourth blanking component is located at the lower part of the kiln body 1; the fourth blanking component is located above the discharge hopper 13.

[0033] The discharge hopper 13 is located at the lower part of the kiln body 1 . A discharge port is provided at the bottom of the discharge hopper 13 . A discharge valve 14 is installed on the discharge port. The discharge valve 14 can be an automatic valve.

[0034] In this embodiment, both the discharge valve 14 and the feed valve 2 are automatic valves. The controller controls the opening of the discharge valve 14 and the feed valve 2 based on the temperature data measured by temperature sensors installed at various locations in the kiln body 1, ensuring that the temperature of the kiln body 1 remains relatively stable while the entire device operates stably and continuously, so that the coal gangue can burn by relying on the heat contained in itself.

[0035] An annular ignition chamber 17 is fixedly mounted on the outer side of the discharge hopper 13 , and the ignition chamber 17 passes through a sixth air duct 15 and a fourth fan 16 .

[0036] The ignition chamber 17 is communicated with the discharge hopper 13 through the ignition chamber air chamber.

[0037] The ignition chamber 17 uses natural gas or other fuels. The high-temperature gas generated by combustion is sent into the equipment through the ignition chamber wind chamber to reach the combustion temperature of the coal gangue. The temperature gradually rises from low to high. After stabilization, the combustion system is turned off, and the cooling fan is turned on, and the air volume of each fan is gradually adjusted to a balance.

[0038] The lower part of the kiln body 1 is connected to the air inlet of the third fan 11 through the fifth air duct 12, and the air outlet of the third fan 11 is connected to the upper part of the kiln body 1 through the first air duct 5. Figure 1 As shown, the connection point between the fifth air duct 12 and the kiln body 1 is located between the discharge hopper 13 and the fourth blanking component, that is, installed above the discharge hopper 13; the connection point between the first air duct 5 and the kiln body 1 is located between the first blanking component and the second blanking component.

[0039] The kiln body 1 is also equipped with a second air duct 6 and a fourth air duct 10, wherein the second air duct 6 is connected to the air outlet of the first fan 7, the fourth air duct 10 is connected to the air inlet of the second fan 8, and the air outlet of the second fan 8 is connected to the waste heat recovery system through the third air duct 9.

[0040] The second fan 8 is used to discharge high-temperature hot air from the middle of the kiln body 1.

[0041] Several second air ducts 6 are installed at the middle, upper and lower parts of the kiln body 1 , and each second air duct 6 is connected to a first fan 7 .

[0042] The number of blanking parts in this embodiment can be determined according to the heat of the coal gangue.

[0043] In this embodiment, the feed valve 2, the first fan 7, the second fan 8, the third fan 11, the discharge valve 14, the fourth fan 16 and the ignition device installed in the ignition chamber are all electrically connected to the controller.

[0044] The feed valve 2 and the discharge valve 14 can be automatic valves such as electric gate valves.

[0045] Gangue is prone to spontaneous combustion during stacking, especially under conditions of high temperature, high humidity, and poor ventilation. This spontaneous combustion produces large amounts of harmful gases and smoke, which harm the environment and human health. Therefore, fire prevention measures are necessary during the stacking and handling of gangue.

[0046] Targeting the physical, chemical, and engineering properties of gangue, this device utilizes a scientifically sound thermal system and raw material ratio to fully utilize its calorific value and mineral composition, achieving the dual goals of resource utilization and environmental protection. When the calorific value of gangue is ≥300 kcal / kg, this stratified combustion device can be used. The gangue's own calorific value can sustain combustion, generating high-temperature hot air at 600-800°C for secondary waste heat utilization.

[0047] Before the gangue enters the kiln body 1, it is first crushed to a suitable particle size (5-50mm) and shape (round, cylindrical or irregular), or other pre-treatment methods (first grinding into powder and then granulating) are used to meet the above requirements.

[0048] The material is fed into the kiln body 1 and is slowly burned at low temperature from the first blanking device to the discharge hopper 13, and undergoes drying and preheating, slow burning at low temperature, and cooling. Minerals such as silicon and aluminum account for more than 80% of the gangue. The gangue contains coal and clay components and has the dual properties of combustion and silicate components.

[0049] The coal in the gangue exists inside the gangue. During the combustion process, the oxygen in the air enters the interior through the surface and pores of the gangue particles and reacts with the carbon to generate carbon dioxide and then release it. This process takes a relatively long time. The time required for the silicate material to generate crystalline mullite during low-temperature slow burning is also relatively long. In order to achieve complete combustion of the residual coal in the gangue, the combustion product must be calcined into crystalline mullite. During the calcination process, it is necessary to ensure that the combustion time of the fixed carbon in the gangue is consistent with the crystalline mullite generation time curve during low-temperature slow burning.

[0050] Before igniting the equipment, the ventilation system (the fourth fan 16) is turned on to check whether the ventilation inside the equipment is normal.

[0051] As attached Figure 1As shown, in the drying and preheating section, that is, the upper part of the kiln body 1, the material and the hot air are in parallel flow, and the inlet air temperature is 300-500°C. The heat comes from the waste heat generated by the cooling product, that is, the hot air delivered by the third fan 11. The volatile matter in the coal gangue is precipitated and burned at this temperature. Since the hot air and the material have the same running direction, the heat generated by the combustion of the volatile matter and fixed carbon is further used for evaporation of water in the material and heating of the material. At the same time, according to the calculated calorific value of the volatile matter in the coal gangue, layered blanking parts are added in the calcining kiln to form an air chamber. One or more first fans 7 are added to the drying and preheating section (for every 150-200 kcal increase in the calorific value of the coal gangue, an additional layer of air chamber is required) to adjust the temperature of this section to ensure a low-temperature slow burning temperature range of 700-900°C to avoid excessive temperature and overburning and hardening. This section adopts a parallel flow method. The unburned gas components in the drying and preheating section enter the high-temperature section, i.e. the middle part of the kiln body 1, along with the hot air, and are further burned. This solves the problem of excessive emissions of combustible gases such as CO and CH4 in the tail gas using the previous countercurrent method.

[0052] The material then enters the fixed carbon removal and combustion stage, which is located in the lower part of the kiln body 1 and above the discharge hopper 13. In this section, the hot air and the material flow in the opposite direction, which is a countercurrent method. The material moves downward, and the hot air moves from bottom to top. At the same time, according to the calorific value of the fixed carbon in the gangue raw material, a layered material flow belt structure is added to the combustion device to form an air chamber. One or more blowers are added to the decarbonization and calcination section (for every 150-200 kcal increase in the calorific value of the gangue, an additional air chamber is required) to adjust the temperature of this section to ensure a low-temperature slow burning temperature range of 700-900°C. This method can ensure uniform temperature distribution throughout the kiln body 1.

[0053] The product after decarbonization and calcination enters the cooling section, that is, the discharge hopper 13. In this section, the material and air are countercurrent. During the falling process of the material, the cold air just moves upward and the temperature gradually increases. Part of the high-temperature air enters the drying section for preheating, and part enters the decarbonization and calcination zone for combustion.

[0054] From an engineering perspective, the combustion process during the calcination is smokeless. Almost all of the heat generated by the combustion of the gangue is used to heat the raw material and evaporate the water. A small amount of hot material near the surface of the kiln body 1 will dissipate heat through the surface of the kiln body 1. Since the device is fixed, it is easy to take insulation measures. The high-temperature hot air generated by calcination is discharged from the center of the high-temperature zone of the combustion device. The upper material is driven from top to bottom, and the high-temperature combustion air is driven from top to bottom. The heat carried by the high-temperature hot air evaporates the water and preheats the material, concentrating and then dispersing the heat to avoid the rapid combustion of volatiles and causing local high temperatures. The lower material is driven from top to bottom, and the combustion air is driven from bottom to top. The movement process is reasonable, heat loss is small, and its thermal engineering principle is reasonable.

[0055] Gangue calcination presents challenges in early heat storage, making combustion difficult. Later, heat is concentrated, leading to overburning and calcination. This device, with its up-and-down movement of material and air, ensures full contact, facilitating combustion and heat generation. The vertical structure maximizes heat preservation and storage in the early stages, maintaining a stable temperature within a reasonable range. The fixed, layered vertical structure creates multiple air chambers, allowing for the addition of a central air blast system to disperse localized high temperatures and maintain a stable temperature within the kiln. This ultimately enables simultaneous feeding and discharging of materials.

[0056] When the calorific value of gangue is 300 kcal / kg, no additional heat source is needed; its own calorific value can maintain the combustion temperature. As the calorific value of gangue increases, the temperature in the calcination zone may become too high. In this case, it is necessary to add several air supply ducts to the side of the combustion device to increase the amount of air entering and lower the calcination environment temperature. This ensures that the time curve of the low-temperature slow combustion of the silicate component is consistent with the time curve of the precipitation combustion of volatile matter and fixed carbon in the gangue.

[0057] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue, characterized in that: The invention comprises a kiln body (1), wherein a feed valve (2) is installed on the top of the kiln body (1), a discharge hopper (13) is provided at the bottom, a discharge valve (14) is installed at the bottom of the discharge hopper (13), and a plurality of blanking components are installed from top to bottom on the kiln body (1) between the feed valve (2) and the discharge hopper (13), wherein the blanking components divide the kiln body (1) into a plurality of air chambers, and the lower part of the kiln body (1) is connected to the third air duct (12) through the fifth air duct (13). The air inlet end of the fan (11) is connected, the air outlet end of the third fan (11) is connected to the upper part of the kiln body (1) through the first air duct (5), the middle part of the kiln body (1) is connected to the air inlet end of the second fan (8) through the fourth air duct (10), and the discharge hopper (13) is connected to the fourth fan (16); the coal gangue moves in the upper part of the kiln body (1) along with the hot air, and the coal gangue flows in the lower part of the kiln body (1) in the countercurrent direction with the hot air.

2. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 1, characterized in that: A gap is left between two adjacent blanking parts.

3. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 1, characterized in that: The blanking component comprises an upper material guide hopper (3) and a material guide pipe (4) fixed at the bottom of the material guide hopper (3).

4. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 3, characterized in that: The guide hopper (3) is in a trumpet shape, with an outer diameter at the top being larger than that at the bottom, and an inner diameter at the top also being larger than that at the bottom; the inner diameter at the top of the guide hopper (3) is equal to the inner diameter of the kiln body (1).

5. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 4, characterized in that: The material guide pipe (4) is a hollow tubular structure of equal diameter, and its inner diameter is equal to the inner diameter of the bottom of the material guide hopper (3).

6. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 1, characterized in that: An ignition chamber (17) is fixedly installed on the outside of the discharge hopper (13). The ignition chamber (17) is connected to the fourth fan (16) through the sixth air duct (15). The ignition chamber (17) is communicated with the discharge hopper (13) through the ignition chamber air chamber.

7. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 1, characterized in that: A plurality of second air ducts (6) are also installed on the kiln body (1), and the second air ducts (6) are connected to the air outlet end of the first fan (7).

8. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 1, characterized in that: The feed valve (2) and the discharge valve (14) are both automatic valves.

9. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 1, characterized in that: The air outlet end of the second fan (8) is connected to the waste heat recovery system via a third air duct (9).

10. The layered slow-release calcining device capable of maintaining spontaneous combustion of low calorific value coal gangue according to claim 1, characterized in that: The fifth air duct (12) is installed above the discharge hopper (13).

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