A coal gangue decarbonization and resource utilization disposal system

Abstract

The present invention relates to the technical field of coal gangue decarbonization and resource treatment, and discloses a coal gangue decarbonization and resource treatment system. The treatment system includes a preheating device, a conveying device, and a decarbonization and mineral phase reconstruction device, which is mixed and burned with preheated air in the decarbonization and mineral phase reconstruction device. The decarbonization and mineral phase reconstruction device is connected to a waste heat recovery device and a preheating device, and the primary air preheated air outlet of the waste heat recovery device is connected to the decarbonization and mineral phase reconstruction device; the decarbonization and mineral phase reconstruction device includes a hot air supply system and a rotary kiln body; through material and air staged preheating, the waste heat generated by the combustion of coal gangue is effectively utilized to increase the enthalpy values of the coal gangue and air entering the mineral phase reconstruction device, which is beneficial to the stable combustion and decarbonization of low-calorie coal gangue; fluidizing air is arranged in the rotary kiln to strengthen the mass transfer, heat transfer and reaction between the coal gangue and the hot air, greatly shortening the combustion time and enabling the coal gangue to burn sufficiently.

Description

Technical Field

[0001] The present invention relates to the technical field of coal gangue decarbonization and resource treatment, and more specifically, to a coal gangue decarbonization and resource treatment system. Background Art

[0002] Coal gangue contains a large amount of valuable elements such as silicon and aluminum, which are the basic elements of inorganic non-metallic materials. Especially in some areas, the coal gangue has a high aluminum content and a low impurity content, and has high development and utilization value.

[0003] To realize the resource treatment of coal gangue, it is necessary to decarbonize and thermally activate the coal gangue. The existing coal gangue decarbonization and activation treatment processes include:

[0004] 1) Using lump coal gangue as raw material and adopting shaft kiln and tunnel kiln calcination processes;

[0005] 2) Using powdered coal gangue as raw material and adopting rotary kiln, suspension furnace calcination, etc. The above decarbonization and activation treatment processes all have some problems.

[0006] For example, the shaft kiln calcination process of lump coal gangue has problems such as long calcination cycle, easy incomplete calcination of raw materials, and the need for secondary sorting. The tunnel kiln calcination of lump coal gangue also has the problems of easy incomplete calcination of raw materials and the need for secondary sorting, and has high energy consumption.

[0007] The defects of using a single shaft kiln and tunnel kiln of lump coal gangue are small processing capacity; the existing rotary kiln calcination process of powdered coal gangue has disadvantages such as small contact area between raw materials and hot gas, difficult temperature control, and unstable quality; using the powdered suspension kiln calcination process, although waste heat is recovered by means of cyclone preheating, etc., there are problems such as excessive VOC emissions such as volatile components, too short calcination time, incomplete calcination, incomplete crystal form transformation, and low finished product rate. Summary of the Invention

[0008] In view of this, the present invention proposes a coal gangue decarbonization and resource treatment system, aiming to solve the problems in the existing technology such as low finished product rate and unstable quality caused by incomplete calcination, high energy consumption caused by insufficient waste heat recovery, and excessive VOC emissions caused by ineffective utilization of volatile components.

[0009] The present invention provides a coal gangue decarbonization and resource treatment system, including a decarbonization and mineral phase reconstruction device, which is mixed and burned with preheated air in the decarbonization and mineral phase reconstruction device. The decarbonization and mineral phase reconstruction device includes a hot air supply system. The hot air supply system includes a hot air main pipe and a air distribution device. The arrangement spacing of the air distribution device on the hot air main pipe , and its specific relationship is shown in formula (1):

[0010] (1)

[0011] where: n > 2;

[0012] C is the flammability discrimination index;

[0013] When n = 1, is .

[0014] The hot air is distributed through the air distribution device. When the length from the kiln head of the rotary kiln accounts for 50% of the total length, the amount of hot air accounts for the total amount ;

[0015] The arrangement spacing of the air distribution pipes in the hot air supply system The spacing value near the kiln tail is the largest.

[0016] Furthermore, it further 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 to the waste heat recovery device and the preheating device. The primary air preheated air outlet of the waste heat recovery device is connected to the decarbonization and mineral phase reconstruction device; The decarbonization and mineral phase reconstruction device further includes a feeding device, a kiln head, a rotary kiln body, a refractory insulation lining, a material lifting plate, and a kiln tail. The kiln tail is provided with a high-temperature flue gas outlet and a solid material outlet.

[0017] Furthermore, when the length from the kiln head of the rotary kiln accounts for 50% of the total length, the amount of hot air accounts for the total amount .

[0018] Furthermore, the air distribution device includes a connecting pipe and air distribution pipes connected to each other. 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 on the surface. The air distribution pipes are in an arc structure, and there is an air distribution interval between the arc surface of the arc structure and the arc surface of the solid materials.

[0019] Furthermore, reinforcing ribs are arranged at the connection between the connecting pipe and the air distribution pipes.

[0020] Furthermore, a number of air holes are evenly opened on the air distribution pipes, and the wind speed of the air holes is .

[0021] Furthermore, an air preheater is arranged between the high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device and the preheating device. The secondary air preheated air outlet of the air preheater is connected to the decarbonization and mineral phase reconstruction device;

[0022] When the calorific value of coal gangue ≥ 500 kcal / 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 flue gas outlet of the waste heat boiler is connected to the air preheater; when the calorific value of coal gangue < 500 kcal / kg, a heat supplement device is arranged 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.

[0023] Further, the decarbonization and mineral phase reconstruction device includes a decarbonization device and a mineral phase reconstruction device. After being dried, 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, the high-temperature flue gas outlet of the mineral phase reconstruction device is connected to the waste heat recovery device, and the tertiary air preheated air outlet of the mineral phase reconstruction device and the secondary air preheated air outlet of the waste heat recovery device are both connected to the decarbonization device.

[0024] Further, a sealing surface is arranged between the rotary kiln body and the kiln head and the kiln tail, and the rotary kiln is sealed through a combination form of packing labyrinth seal and scale seal.

[0025] Further, 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 to carry out a combustion reaction with the hot air entering from the fluidized bed air distribution device, and the solid material after the reaction enters the decarbonization and mineral phase reconstruction device through the slag discharge pipe; the generated high-temperature flue gas enters the kiln head of the decarbonization and mineral phase reconstruction device from the smoke exhaust port at the top of the fluidized bed.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1) In the present invention, through the staged preheating of materials and air, the waste heat generated by the combustion of coal gangue is effectively utilized to increase the enthalpy values of the coal gangue and air entering the mineral phase reconstruction device, which is beneficial to the stable combustion decarbonization of low-calorific-value coal gangue.

[0028] 2) The rotary kiln with internal components such as a material propulsion spiral plate and a lifting plate reduces the problems of overburning and underburning caused by the backmixing of solid materials, and the adjustable and stable residence time is beneficial to the uniformity of the mineral phase reconstruction of coal gangue.

[0029] 3) Fluidizing air is arranged in the rotary kiln to strengthen the mass transfer, heat transfer and reaction between coal gangue and hot air, greatly shortening the combustion time and enabling the coal gangue to burn sufficiently. Description of the Drawings

[0030] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiments. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Also, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0031] Figure 1 is the process flow (I) of coal gangue decarbonization and resource utilization

[0032] Figure 2 is the structural schematic diagram of the decarbonization and mineral phase reconstruction device

[0033] Figure 3 is the structural schematic diagram of the air distribution device

[0034] Figure 4 is the process flow (II) of coal gangue decarbonization and resource utilization

[0035] Figure 5 is the structural schematic diagram of the fluidized bed coupled rotary kiln decarbonization and mineral phase reconstruction device

[0036] Among them, the preheating device 1; the decarbonization and mineral phase reconstruction device 2, the fluidized bed 20; the main hot air pipe 21, the feeding device 22, the kiln head 23, the rotary kiln body 24, the refractory heat-insulating lining 25, the lifting plate 26, the air distribution device 27, the main hot air pipe support beam 28, the kiln tail 29, the high-temperature flue gas outlet 30, the solid material outlet 31, the solid material 32, the fluidized bed air distribution device 33, the slag discharge pipe 34, the smoke outlet 35; the waste heat recovery device 3; the conveying device 4; the air preheater 5; the mineral phase reconstruction device 6; the decarbonization device 7. Specific Embodiments

[0037] The following will describe the exemplary embodiments of the present disclosure in more detail with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the 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 so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0038] The following is the coal gangue decarbonization and resource utilization process as Figure 1 shown:

[0039] 1) The coal gangue G is dried and preheated by the preheating device 1, and the temperature of the coal gangue is preheated from room temperature to 50 °C below the temperature at which volatile matter is released (usually ≤250 °C); the coal gangue G is directly preheated by flue gas, and the temperature of the preheated flue gas 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.

[0040] 2) Optionally, the preheating device 1 is divided into two sections. The low-temperature section is a rotary kiln drying cylinder, which dries the coal gangue G. The coal gangue is directly preheated by flue gas from room temperature to 150 °C, and the moisture of the coal gangue is evaporated, and then it enters the high-temperature section of the preheating device 1. The high-temperature section is a wall-type heat exchanger. The dried coal gangue is preheated and pyrolyzed at low temperature inside the rotary kiln. The flue gas flows reversely with the coal gangue in the outer cavity of the rotary kiln, raising the temperature of the coal 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.

[0041] 3) The preheated coal gangue enters the decarbonization and mineral phase reconstruction device 2 through the conveying device 4 and is mixed and burned with the preheated air in the decarbonization and mineral phase reconstruction device 2; the conveying device 4 is a screw conveying device, a star feeder device or a chain plate feeder device; the decarbonization and mineral phase reconstruction device 2 is a rotary kiln. The residence time of the coal gangue in the rotary kiln is adjusted by the rotation speed of the rotary kiln, and the residence time of the coal gangue material in different combustion temperature ranges is adjusted by the change of the pitch of the lifting plates arranged in a spiral structure inside the rotary kiln, so as to achieve full decarbonization and mineral phase reconstruction of the coal gangue. The preheated air comes from two parts: one part is the primary air A1 preheated by the waste heat recovery device 3 from the hot product P formed after the decarbonization and mineral phase reconstruction of the coal gangue; the other part is the secondary air A2 preheated by the air preheater 5 from the high-temperature flue gas discharged from the tail of the decarbonization and mineral phase reconstruction device 2. The temperature of the product P is reduced to ≤100 °C after being cooled by the waste heat recovery device 3. The temperature of the preheated air entering the decarbonization and mineral phase reconstruction device 2 is , and the combustion temperature of the decarbonization and mineral phase reconstruction device 2 is , and 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 is adjusted by the excess air coefficient and adding burners.

[0042] 4) The product P after the combustion reaction in 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 ; the waste heat recovery device 3 is a grate cooler, a chain grate or a fluidized bed.

[0043] 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 , and the secondary air is heated to .

[0044] 6) The primary air A1 and the secondary air A2 can be mixed and fed into the kiln head, or the primary air A1 and the secondary air A2 can be separately fed into 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 fed into the kiln head to avoid the influence of the secondary air A2 on the local decarbonization of coal gangue; the mixing method of the primary air A1 and the secondary air A2 can be realized by setting valves. 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.

[0045] Schematic diagram of the structure of the decarbonization and mineral phase reconstruction device 2, as shown in Figure 2 (the spacing in the figure is only for illustration and does not represent 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 and heat-insulating 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, a air distribution device 27 and a hot air main pipe support beam 28. A sealing surface is provided between the rotary kiln body 24 and the kiln head 23 and the kiln tail 29, and the rotary kiln is sealed through a combination of packing labyrinth seal and scale seal to reduce the air leakage. The arrangement spacing of the air distribution pipes of the air distribution device 27 on the hot air main pipe 21 gradually increases. The poorer the activity, the more compact the arrangement is to promote its rapid combustion. For materials with high activity, the air distribution spacing is widened to avoid local overheating and overburning. The spacing is related to the activity of coal gangue, and the specific relationship is shown in Equation (1):

[0046] (1)

[0047] In the formula: n > 2;

[0048] C is the combustibility discrimination index. The smaller the combustibility discrimination index C, the poorer the activity and the poorer the combustibility;

[0049] When n = 1, is .

[0050] Hot air is distributed through the air distribution device 27. When the length from the kiln head of the rotary kiln accounts for 50% of the total length, the amount of hot air accounts for the total amount , preferably .

[0051] The structural schematic diagram of the air distribution device 27 is as shown in Figure 3 . The solid material 32 is located at the bottom of the rotary kiln and is spread out in an arc shape on the surface. The air distribution device consists of a connecting pipe connected to the hot air main pipe 21 and an arc-shaped air distribution pipe. To make the structure of the air distribution device stable, stiffeners are provided at the connection between the connecting pipe and the air distribution pipe. 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 air velocity of the air holes is .

[0052] When the calorific value of coal gangue ≥ 500 kcal / kg, the high-temperature flue gas coming out of the rotary kiln tail first enters the waste heat boiler, and then enters the air preheater to fully recover the waste heat and generate steam.

[0053] When the calorific value of coal gangue < 500 kcal / kg, the self-sustained combustion of coal gangue is unstable, the decarbonization and mineral phase reconstruction are uneven, and the finished product rate 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.

[0054] Decouple the decarbonization and mineral phase reconstruction of coal gangue, and adopt the process as shown in Figure 4 . After being dried, the coal gangue enters the decarbonization device 7 through the conveying device 4 for combustion decarbonization, and then enters the mineral phase reconstruction device 6 for isothermal mineral phase reconstruction after decarbonization. Generally, the decarbonization device maintains a temperature of , and the mineral phase reconstruction device 6 maintains a temperature of . 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, and introduces of the theoretical combustion air volume of coal gangue to strengthen the heat transfer inside the mineral phase reconstruction device 6, promote the uniformity of the internal temperature, and supplement oxygen for decarbonization combustion at the same time. The hot flue gas of the mineral phase reconstruction device 6 is combined with the waste heat recovery device 3.

[0055] 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, and its structural schematic diagram is as shown in Figure 5 . The feeding device 22 enters the fluidized bed 20 to carry out a combustion reaction with the hot air entering from the fluidized bed air distribution device 33, and the decarbonization rate reaches 50% - 90%. The reacted solid material enters the rotary kiln through the slag discharge pipe 34 for decarbonization and mineral phase reconstruction; the generated high-temperature flue gas enters the kiln head of the rotary kiln from the smoke exhaust port 35 at the top of the fluidized bed.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A coal gangue decarbonization and resource utilization disposal system, characterized in that, It includes a decarbonization and mineral phase reconstruction device, which conducts mixed combustion with preheated air inside the decarbonization and mineral phase reconstruction device. The decarbonization and mineral phase reconstruction device includes a hot air supply system. The hot air supply system includes a hot air main pipe and a air distribution device. The arrangement spacing △L of the air distribution device on the hot air main pipe, and its specific relationship is shown in Equation (1): △Ln = △Ln-1×(C×10 6 )n (1) In the formula: 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. When the length from the kiln head of the rotary kiln accounts for 50% of the total length, the hot air volume accounts for 60% - 100% of the total volume; The arrangement spacing △L of the air distribution pipes in the hot air supply system is the largest near the kiln tail; It includes a preheating device for drying and preheating coal gangue. The preheated coal gangue enters the decarbonization and mineral phase reconstruction device through a conveying device. The high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device is respectively connected to a waste heat recovery device and the preheating device. The primary air preheated air outlet of the waste heat recovery device is connected to 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 heat-insulating lining, a material lifting plate, and a kiln tail. The kiln tail is provided with a high-temperature flue gas outlet and a solid material outlet; 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. The secondary air preheated air outlet of the air preheater is connected to the decarbonization and mineral phase reconstruction device; When the calorific value of coal gangue ≥ 500 kcal / kg, the high-temperature flue gas outlet at the tail of the decarbonization and mineral phase reconstruction device is connected to the inlet of a waste heat boiler, and the outlet of the waste heat boiler is connected to the air preheater; when the calorific value of coal gangue < 500 kcal / kg, a heat supplement device is provided 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.

2. The coal gangue decarbonization and resource utilization disposal system according to claim 1, wherein When the length from the kiln head of the rotary kiln accounts for 50% of the total length, the hot air volume accounts for 60% - 80% of the total volume.

3. The coal gangue decarbonization and resource utilization disposal system according to claim 1 or 2, characterized in that The air distribution device includes a connecting pipe and air distribution pipes that are connected. 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 on the surface, the air distribution pipes are in an arc structure, and there is an air distribution interval between the arc surface of the arc structure and the arc surface of the solid materials.

4. The coal gangue decarbonization and resource utilization disposal system according to claim 3, wherein, Reinforcing ribs are provided at the connection between the connecting pipe and the air distribution pipes.

5. The coal gangue decarbonization and resource utilization disposal system according to claim 4, wherein A number of air holes are evenly opened on the air distribution pipes, and the air velocity of the air holes is 30 m / s - 60 m / s.

6. The coal gangue decarbonization and resource utilization disposal system according to claim 1, wherein, 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 isothermal 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. The high-temperature flue gas outlet of the mineral phase reconstruction device is connected to the waste heat recovery device. The tertiary air preheated air outlet of the mineral phase reconstruction device and the secondary air preheated air outlet of the waste heat recovery device are both connected to the decarbonization device.

7. The coal gangue decarbonization and resource utilization disposal system according to claim 1, characterized in that, A sealing surface is provided between the rotary kiln body and the kiln head and the kiln tail, and the rotary kiln is sealed through a combined form of packing labyrinth seal and scale seal.

8. The coal gangue decarbonization and resource utilization disposal system according to claim 1 or 7, 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 reacts 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 smoke exhaust port at the top of the fluidized bed.

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