Coal gangue decarbonization and recycling treatment system

Abstract

The invention relates to the technical field of coal gangue decarburization and resourceful treatment, and discloses a coal gangue decarburization and resourceful treatment system which comprises a preheating device, a conveying device and a decarburization and ore phase reconstruction device. The decarburization and ore phase reconstruction device is communicated with the waste heat recovery device and the preheating device, and a primary air preheating air outlet of the waste heat recovery device is communicated with the decarburization and ore phase reconstruction device; the decarbonization and ore phase reconstruction device comprises a hot air supply system and a rotary kiln body; through graded preheating of materials and air, waste heat generated by coal gangue combustion is effectively utilized to increase enthalpy values of coal gangue and air entering the ore phase reconstruction device, and stable combustion decarburization of low-heating-value coal gangue is facilitated; fluidizing air is arranged in the rotary kiln to strengthen mass and heat transfer and reaction between the coal gangue and hot air, so that the combustion time is greatly shortened, and the coal gangue is fully combusted.

Description

Technical Field

[0001] The present invention relates to the technical field of coal gangue decarbonization and resource processing, and in particular to a coal gangue decarbonization and resource processing system. Background Art

[0002] Gangue is a solid waste produced during coal mining. Mining 1 ton of coal produces about 0.25 to 0.33 tons of gangue. According to statistics, my country's gangue production will reach 808 million tons in 2023, resulting in a large amount of gangue storage, which not only occupies land but also causes great harm to the ecological environment. However, gangue contains a large amount of valuable elements such as silicon and aluminum, which are basic elements of inorganic non-metallic materials. In particular, the aluminum content in gangue in some areas is high and the impurity content is low, which has a high development and utilization value.

[0003] To realize the resource disposal of coal gangue, it is necessary to decarbonize and thermally activate the coal gangue. The existing coal gangue decarbonization and activation treatment processes include: 1) Using blocky coal gangue as raw material, adopting vertical kiln and tunnel kiln calcination process; 2) Using powdered coal gangue as raw material, using rotary kiln, suspension furnace calcination, etc., the above decarbonization and activation treatment processes still have some problems.

[0004] For example, the vertical kiln calcination process for lump gangue has problems such as long calcination cycle, raw materials are easily not calcined through, and require secondary sorting. The tunnel kiln calcination of lump gangue also has problems such as raw materials are easily not calcined through, and require secondary sorting, and the energy consumption is relatively high.

[0005] The drawback of using single kilns such as vertical kilns and tunnel kilns for blocky coal gangue is that the processing capacity is small; the existing rotary kiln calcination process for powdery coal gangue has the disadvantages of small contact surface with hot gas, difficult temperature control, unstable quality, etc.; the powdery suspension kiln calcination process, although the waste heat is recovered by means such as cyclone preheating, has problems such as excessive VOC emissions such as volatile matter, too short calcination time, incomplete calcination, incomplete crystal transformation, and low yield. Summary of the invention

[0006] In view of this, the present invention proposes a coal gangue decarbonization and resource disposal system, aiming to solve the problems in the prior art such as insufficient calcination resulting in low yield and unstable quality, insufficient waste heat recovery resulting in high energy consumption, and failure to effectively utilize volatile matter resulting in excessive VOC emissions.

[0007] The present invention provides a coal gangue decarbonization and resource disposal system, comprising a decarbonization and mineral phase reconstruction device, in which mixed combustion with preheated air is performed, the decarbonization and mineral phase reconstruction device comprises a hot air supply system, the hot air supply system comprises a hot air main pipe and an air distribution device, the arrangement spacing △L of the air distribution device on the hot air main pipe, and the specific relationship thereof is shown in formula (1): △L n =△L n-1 ×(C×10 6 ) n (1) Where: n>2; C is the flammability discrimination index; When n=1, △L is 150~300.

[0008] The hot air is distributed through the air distribution device, and when the length of the rotary kiln from the kiln head accounts for 50% of the total length, the amount of hot air accounts for 60% to 100% of the total amount; The arrangement spacing ΔL of the air ducts in the hot air supply system is the largest near the kiln tail.

[0009] Furthermore, it also includes a preheating device for drying and preheating the coal gangue. The coal gangue preheated by the conveying device enters the decarbonization and mineral phase reconstruction device. The high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device is respectively connected with the waste heat recovery device and the preheating device, and the primary air preheating air outlet of the waste heat recovery device is connected with the decarbonization and mineral phase reconstruction device; the decarbonization and mineral phase reconstruction device also includes a feeding device, a kiln head, a rotary kiln body, a refractory insulation lining, a lifting plate and a kiln tail, and the kiln tail is provided with a high-temperature flue gas outlet and a solid material outlet.

[0010] Furthermore, when the length of the rotary kiln from the kiln head accounts for 50% of the total length, the amount of hot air accounts for 60% to 80% of the total amount.

[0011] Furthermore, the air distribution device includes a connecting pipe and an air distribution pipe that are connected to each other, and the connecting pipe is connected to the hot air main pipe; the solid material gathered at the bottom of the rotary kiln has a surface spread out in an arc shape, and the air distribution pipe has an arc-shaped structure, and an air distribution gap is provided between the arc surface of the arc structure and the arc surface of the solid material.

[0012] Furthermore, reinforcing ribs are provided at the connection between the connecting pipe and the air distribution pipe.

[0013] Furthermore, a plurality of air holes are evenly arranged on the air distribution duct, and the wind speed of the air holes is 30m / s~60m / s.

[0014] Furthermore, an air preheater is provided between the high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device and the preheating device, and the secondary air preheating air outlet of the air preheater is connected to the decarbonization and mineral phase reconstruction device; When the calorific value of coal gangue is ≥500kcal / kg, the high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device is connected to the air inlet of the waste heat boiler, and the air outlet of the waste heat boiler is connected to the air preheater; when the calorific value of coal gangue is <500 kcal / kg, a heat supplement device is installed at the kiln head of the decarbonization and mineral phase reconstruction device, and the heat supplement device is a natural gas burner, a pulverized coal burner and / or hot air from other equipment.

[0015] Furthermore, the decarbonization and mineral phase reconstruction device includes a decarbonization device and a mineral phase reconstruction device. After drying, the mineral phase enters the decarbonization device through a conveying device for combustion decarbonization, and then enters the mineral phase reconstruction device for constant temperature mineral phase reconstruction after decarbonization. The high-temperature flue gas outlet of the decarbonization device is respectively connected to the mineral phase reconstruction device and the preheating device, and the high-temperature flue gas outlet of the mineral phase reconstruction device is connected to the waste heat recovery device. The tertiary air preheating air outlet of the mineral phase reconstruction device and the secondary air preheating air outlet of the waste heat recovery device are both connected to the decarbonization device.

[0016] Furthermore, sealing surfaces are arranged between the rotary kiln body and the kiln head and the kiln tail, and the rotary kiln is sealed by a combination of a packing labyrinth seal and a flake seal.

[0017] Furthermore, for coal gangue with poor combustion activity, a fluidized bed coupled with a rotary kiln is used to form a decarbonization and mineral phase reconstruction device. The feeding device enters the fluidized bed and undergoes combustion reaction with the hot air entering from the fluidized bed air distribution device. The solid material after the reaction enters the decarbonization and mineral phase reconstruction device through a slag discharge pipe; the high-temperature flue gas generated enters the kiln head of the decarbonization and mineral phase reconstruction device from the exhaust port on the top of the fluidized bed.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1) In the present invention, by preheating materials and air in stages, the waste heat generated by the combustion of coal gangue is effectively utilized to increase the enthalpy value of the coal gangue and air entering the mineral phase reconstruction device, which is beneficial to the stable combustion and decarbonization of low calorific value coal gangue.

[0019] 2) The use of a rotary kiln with material-propelling spiral plates and lifting plate internal components reduces the problems of over-burning and under-burning caused by back-mixing of solid materials, and the adjustable and stable residence time is beneficial to the uniformity of the reconstruction of the coal gangue ore phase.

[0020] 3) Fluidized air is arranged in the rotary kiln to strengthen the mass transfer, heat transfer and reaction between the gangue and the hot air, greatly shortening the combustion time and ensuring full combustion of the gangue. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 Decarbonization and resource disposal process of coal gangue (I); Figure 2 It is a schematic diagram of the structure of the decarbonization and mineral phase reconstruction device; Figure 3 It is a schematic diagram of the structure of the air distribution device; Figure 4 Decarbonization and resource disposal process of coal gangue (II); Figure 5 It is a schematic diagram of the structure of the fluidized bed coupled rotary kiln decarbonization ore phase reconstruction device; Among them, there are preheating device 1; decarbonization and mineral phase reconstruction device 2, fluidized bed 20; hot air main pipe 21, feeding device 22, kiln head 23, rotary kiln body 24, refractory insulation lining 25, lifting plate 26, air distribution device 27, hot air main pipe support beam 28, kiln tail 29, high-temperature flue gas outlet 30, solid material outlet 31, solid material 32, fluidized bed air distribution device 33, slag discharge pipe 34, smoke exhaust port 35; waste heat recovery device 3; conveying device 4; air preheater 5; mineral phase reconstruction device 6; decarbonization device 7. DETAILED DESCRIPTION

[0022] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0023] The following coal gangue decarbonization and resource disposal processes are as follows Figure 1 As shown: 1) The gangue G is dried and preheated by the preheating device 1, and the temperature of the gangue is preheated from room temperature to 50°C lower than the volatile analysis temperature (usually ≤250°C); the gangue G is directly preheated by flue gas, and the flue gas temperature after preheating is 120~180°C, which is higher than the dew point temperature of the flue gas. The flue gas F and fly ash a enter the dust removal and purification device at the tail; the preheating device 1 is a rotary kiln or a fluidized bed preheating device.

[0024] 2) Optionally, the preheating device 1 is divided into two sections. The low-temperature section is a rotary kiln drying cylinder, which dries the gangue G. The gangue temperature is preheated from room temperature to 150°C by direct flue gas preheating, and the moisture in the gangue is evaporated, and then enters the high-temperature section of the preheating device 1. The high-temperature section is a partition heat exchanger. The dried gangue is preheated and low-temperature pyrolyzed inside the rotary kiln. The flue gas flows in the reverse direction to the gangue in the outer cavity of the rotary kiln, raising the temperature of the gangue to 300-500°C. The volatile matter generated by low-temperature pyrolysis is sent to the decarbonization and mineral phase reconstruction device 2 through a pipeline, providing fuel for the stable combustion of the decarbonization and mineral phase reconstruction device 2, further improving the thermal efficiency, and at the same time decomposing the volatile matter generated by pyrolysis to avoid VOC emissions.

[0025] 3) The preheated gangue enters the decarbonization and mineral phase reconstruction device 2 through the conveying device 4, and is mixed with the preheated air for combustion in the decarbonization and mineral phase reconstruction device 2; the conveying device 4 is a screw conveying device, a star-shaped feeding device or a chain plate feeding device; the decarbonization and mineral phase reconstruction device 2 is a rotary kiln, and the residence time of the gangue in the rotary kiln is adjusted by the rotation rate of the rotary kiln, and the residence time of the gangue material in different combustion temperature ranges is adjusted by the pitch change of the lifting plate arranged in a spiral structure in the rotary kiln, so as to achieve full decarbonization and mineral phase reconstruction of the gangue. The preheated air comes from two parts: one part comes from the primary air A1 preheated by the waste heat recovery device 3 of the hot product P formed after the decarbonization and mineral phase reconstruction of the gangue; the other part comes from the secondary air A2 preheated by the air preheater 5 of the high-temperature flue gas discharged from the tail of the decarbonization and mineral phase reconstruction device 2. After cooling by the waste heat recovery device 3, the temperature of the product P is reduced to ≤100℃. The temperature of the preheated air entering the decarbonization and mineral phase reconstruction device 2 is 200~600℃, and the combustion temperature of the decarbonization and mineral phase reconstruction device 2 is 850~1200℃. The appropriate combustion temperature can be selected according to the mineral phase and activity requirements of the product P. The combustion temperature of the decarbonization and mineral phase reconstruction device 2 can be adjusted by the excess air coefficient and the addition of burners.

[0026] 4) The product P after the combustion reaction from the decarbonization and mineral phase reconstruction device 2 enters the waste heat recovery device 3 and is cooled by the primary air A1 of the decarbonization and mineral phase reconstruction device 2. At the same time, the primary air A1 is heated to 200~600℃; the waste heat recovery device 3 is a grate cooler, a chain conveyor or a fluidized bed.

[0027] 5) The high-temperature flue gas generated by the combustion reaction of the decarbonization and mineral phase reconstruction device 2 enters the air preheater 5, and exchanges heat with the secondary air A2 of the decarbonization and mineral phase reconstruction device 2, and the temperature drops to 300~600℃, while the secondary air is heated to 200~600℃.

[0028] 6) The primary air A1 and the secondary air A2 can be mixed and introduced from the kiln head, or the primary air A1 and the secondary air A2 can be separately introduced from different positions of the rotary kiln to meet the requirements of the decarbonization and mineral phase reconstruction device for the decarbonization and mineral phase reconstruction of coal gangue. It should be noted here that: a temperature sensor is set on the conveying pipeline of the secondary air A2 to monitor the temperature of the secondary air A2 before entering the kiln head. If the temperature value of the secondary air is lower than 200°C, the primary air A1 and the secondary air A2 are mixed and introduced from the kiln head to avoid the influence of the secondary air A2 on the local decarbonization of coal gangue; the mixing mode of the primary air A1 and the secondary air A2 can be achieved by setting a valve. When mixing is required, the conveying pipeline of the secondary air A2 is connected to the conveying pipeline of the primary air A1, and the connection between the conveying pipeline of the secondary air A2 and the inside of the kiln head is closed.

[0029] Schematic diagram of the structure of the decarbonization and mineral phase reconstruction device 2, as shown in Figure 2 As shown (the spacing in the figure is only a schematic diagram, and does not indicate the relationship between the spacings), the decarbonization and mineral phase reconstruction device 2 includes a hot air supply system, a feeding device 22, a kiln head 23, a rotary kiln body 24, a refractory insulation lining 25, a lifting plate 26 arranged in a spiral structure, a kiln tail 29 and a high-temperature flue gas outlet 30, and a solid material outlet 31. The hot air supply system includes a hot air main pipe 21, an air distribution device 27 and a hot air main pipe support beam 28. A sealing surface is set between the rotary kiln body 24 and the kiln head 23 and the kiln tail 29. The rotary kiln is sealed by a combination of a packing labyrinth seal and a scale seal to reduce air leakage. The arrangement spacing △L of the air distribution pipe of the air distribution device 27 on the hot air main pipe 21 gradually increases. The worse the activity of the arrangement spacing, the more compact the arrangement is, which promotes its rapid combustion. The air distribution spacing with high activity is opened to avoid excessive local temperature and overburning. The spacing △L is related to the activity of coal gangue. The specific relationship is shown in formula (1): △L n =△L n-1 ×(C×10 6 ) n (1) Where: n>2; C is the flammability discrimination index. The smaller the flammability discrimination index C is, the worse the activity and the worse the flammability; When n=1, △L is 150~300.

[0030] The hot air is distributed through the air distribution device 27. When the length of the rotary kiln from the kiln head accounts for 50% of the total length, the amount of hot air accounts for 60% to 100% of the total amount, preferably 60% to 80%.

[0031] The structural diagram of the air distribution device 27 is as follows: Figure 3As shown, the solid material 32 is located at the bottom of the rotary kiln, and the surface is spread out in an arc shape. The air distribution device includes a connecting pipe connected to the hot air main pipe 21 and an arc-shaped air distribution pipe. In order to make the structure of the air distribution device stable, reinforcing ribs are provided at the connection between the connecting pipe and the air distribution pipe. In order to make the air distribution uniform and quickly disperse the heat generated by the combustion of the solid material at the bottom of the rotary kiln, uniform air holes are provided on the air distribution pipe, and the wind speed of the air holes is 30m / s~60m / s.

[0032] When the calorific value of coal gangue is ≥500kcal / kg, the high-temperature flue gas coming out of the rotary kiln first enters the waste heat boiler and then enters the air preheater to fully recover the waste heat and generate steam.

[0033] When the calorific value of coal gangue is less than 500 kcal / kg, the self-sustaining combustion of coal gangue is unstable, the decarbonization and mineral phase reconstruction are uneven, and the yield is not high. Therefore, a heat supplement device is set at the kiln head. The heat supplement device can be a natural gas burner, a pulverized coal burner, or hot air from other equipment.

[0034] Decoupling the decarbonization of coal gangue from the mineral phase reconstruction, using Figure 4 The process shown. After drying, the gangue enters the decarbonization device 7 through the conveying device 4 for combustion and decarbonization. After decarbonization, it enters the mineral phase reconstruction device 6 for constant temperature mineral phase reconstruction. Generally, the decarbonization device maintains a temperature of 850~1000℃, and the mineral phase reconstruction device 6 maintains a temperature of 950~1200℃. The mineral phase reconstruction device uses external heat sources such as electricity, natural gas or hot air to maintain the heat demand of the mineral phase reconstruction device. 3%~15% of the theoretical combustion air volume of the gangue is introduced to enhance the internal heat transfer of the mineral phase reconstruction device 6, promote the internal temperature uniformity, and supplement oxygen for decarbonization combustion. The hot flue gas of the mineral phase reconstruction device 6 is merged with the waste heat recovery device 3.

[0035] For coal gangue with poor combustion activity, a fluidized bed coupled with a rotary kiln is used to form a decarbonization mineral phase reconstruction device, as shown in the schematic diagram of the structure. Figure 5 The feeding device 22 enters the fluidized bed 20 and undergoes combustion reaction with the hot air entering from the fluidized bed air distribution device 33, and the decarbonization rate reaches 50%-90%. The solid materials after the reaction enter the rotary kiln through the slag discharge pipe 34 for decarbonization and mineral phase reconstruction; the generated high-temperature flue gas enters the rotary kiln head from the exhaust port 35 at the top of the fluidized bed.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A coal gangue decarbonization and resource disposal system, characterized in that: It comprises a decarbonization and mineral phase reconstruction device, in which mixed combustion with preheated air is carried out, the decarbonization and mineral phase reconstruction device comprises a hot air supply system, the hot air supply system comprises a hot air main pipe and an air distribution device, the arrangement spacing △L of the air distribution device on the hot air main pipe, and the specific relationship thereof is shown in formula (1): △L n =△L n-1 ×(C×10 6 ) n (1) Where: n>2; C is the flammability discrimination index; When n=1, △L is 150~300; The hot air is distributed through the air distribution device, and when the length of the rotary kiln from the kiln head accounts for 50% of the total length, the amount of hot air accounts for 60% to 100% of the total amount; The arrangement spacing ΔL of the air ducts in the hot air supply system is the largest near the kiln tail.

2. The coal gangue decarbonization and resource disposal system according to claim 1 is characterized in that: It includes a preheating device for drying and preheating coal gangue, and the coal gangue preheated by the conveying device enters the decarbonization and mineral phase reconstruction device, and the high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device is respectively connected with the waste heat recovery device and the preheating device, and the primary air preheating air outlet of the waste heat recovery device is connected with the decarbonization and mineral phase reconstruction device; the decarbonization and mineral phase reconstruction device also includes a feeding device, a kiln head, a rotary kiln body, a refractory insulation lining, a lifting plate and a kiln tail, and the kiln tail is provided with a high-temperature flue gas outlet and a solid material outlet.

3. The gangue decarbonization and resource disposal system according to claim 1 is characterized in that: When the length of the rotary kiln from the kiln head accounts for 50% of the total length, the amount of hot air accounts for 60%~80% of the total amount.

4. The gangue decarbonization and resource disposal system according to claim 1 or 3, characterized in that: The air distribution device includes a connecting pipe and an air distribution pipe which are connected to each other, and the connecting pipe is connected to the hot air main pipe; the solid materials gathered at the bottom of the rotary kiln are spread out in an arc shape, and the air distribution pipe is an arc-shaped structure, and an air distribution gap is provided between the arc surface of the arc structure and the arc surface of the solid materials.

5. The gangue decarbonization and resource disposal system according to claim 4 is characterized in that: A reinforcing rib is provided at the connection between the connecting pipe and the air distribution pipe.

6. The coal gangue decarbonization and resource disposal system according to claim 5, characterized in that: A plurality of air holes are evenly arranged on the air distribution duct, and the wind speed of the air holes is 30m / s~60m / s.

7. The coal gangue decarbonization and resource disposal system according to claim 2, characterized in that: An air preheater is provided between the high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device and the preheating device, and the secondary air preheating air outlet of the air preheater is connected to the decarbonization and mineral phase reconstruction device; When the calorific value of coal gangue is ≥500kcal / kg, the high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device is connected to the air inlet of the waste heat boiler, and the air outlet of the waste heat boiler is connected to the air preheater; when the calorific value of coal gangue is <500 kcal / kg, a heat supplement device is installed at the kiln head of the decarbonization and mineral phase reconstruction device, and the heat supplement device is a natural gas burner, a pulverized coal burner and / or hot air from other equipment.

8. The gangue decarbonization and resource disposal system according to claim 2 or 7, characterized in that: The decarbonization and mineral phase reconstruction device includes a decarbonization device and a mineral phase reconstruction device. After drying, it enters the decarbonization device through a conveying device for combustion decarbonization, and then enters the mineral phase reconstruction device for constant temperature mineral phase reconstruction after decarbonization. The high-temperature flue gas outlet of the decarbonization device is respectively connected to the mineral phase reconstruction device and the preheating device, and the high-temperature flue gas outlet of the mineral phase reconstruction device is connected to the waste heat recovery device. The tertiary air preheating air outlet of the mineral phase reconstruction device and the secondary air preheating air outlet of the waste heat recovery device are both connected to the decarbonization device.

9. The coal gangue decarbonization and resource disposal system according to claim 2, characterized in that: Sealing surfaces are arranged between the rotary kiln body and the kiln head and the kiln tail, and the rotary kiln is sealed by a combination of packing labyrinth seal and flake seal.

10. The coal gangue decarbonization and resource disposal system according to claim 2 or 9, characterized in that: For coal gangue with poor combustion activity, a fluidized bed coupled with a rotary kiln is used to form a decarbonization and mineral phase reconstruction device. The feeding device enters the fluidized bed and undergoes combustion reaction with the hot air entering from the fluidized bed air distribution device. The solid material after the reaction enters the decarbonization and mineral phase reconstruction device through the slag discharge pipe; the high-temperature flue gas generated enters the kiln head of the decarbonization and mineral phase reconstruction device from the exhaust port on the top of the fluidized bed.

Images