Method and system for producing ceramsite by comprehensively utilizing coal-based solid waste

Abstract

The invention relates to a method and a system for producing ceramsite by comprehensively utilizing coal-based solid waste. The method specifically comprises the following steps: 1) a two-step pelletizing process; 2) fluidized drying and preheating process; 3) a fluidized cooling process; and 4) application of the biomass fuel in ceramsite production. The method has the advantages that (1) when the coal-based solid waste is treated in the prior art, the (air dry basis) proportion is about 60%, and the coal gangue proportion can be increased to 70%-95%; (2) the cylinder compressive strength of the coal-based high-strength ceramsite produced in the prior art is mostly 3.0-10.0 MPa, and the cylinder compressive strength can be improved to 12.0-25.0 MPa by applying the technology, so that the requirements of the high-strength ceramsite are easily met; (3) the heat consumption (the product of the mass consumed by unit ceramsite and the accumulated value of the heat value of the ceramsite) in the prior art is averagely about 4500 KJ / kg, and the firing heat consumption of the ceramsite is reduced to below 2781 KJ / kg; and (4) the main fuel of the invention is biomass fuel which is a clean and renewable energy form.

Description

Technical Field

[0001] The invention relates to a method and a system for producing ceramsite by comprehensively utilizing coal-based solid waste. Background Art

[0002] Gangue is the largest solid waste discharged in my country. China has accumulated more than 1 billion tons of gangue, and will discharge 100 million tons of gangue every year. Its discharge and accumulation not only occupy a large amount of arable land, but the escape or leaching of sulfides in the gangue will pollute the atmosphere, farmland and water bodies, causing great pollution to the surface atmosphere. Gangue mountains can also spontaneously combust and cause fires, or collapse in the rainy season, silting up rivers and causing disasters; coal slime is a semi-solid substance containing water from coal powder formed during coal mining and coal washing. It is produced in large quantities and is difficult to handle, which puts great pressure on the environment.

[0003] The current coal-based solid waste expanded clay production process is derived from clay expanded clay production technology, which mainly relies on the plasticity of the material to form balls and relies on external heat sources (mostly coal powder) for firing.

[0004] The current pelletizing methods mainly include extrusion pelletizing, pelletizing disc pelletizing, and drum pelletizing. However, because coal gangue is a lean material with poor plasticity, it is difficult to form pellets or the pellets have poor strength when the coal gangue ratio is slightly high. The existing expanded clay sintering technology has low output, high heat consumption, and low pellet strength.

[0005] In summary, the disadvantages of the prior art are: low ratio of coal gangue, difficulty in balling, low strength of the ball, high heat consumption during burning, and the prohibition of using raw coal in a considerable part of the region. These five major problems restrict the development of coal-based ceramsite, and the present invention focuses on solving these problems.

[0006] The technical problems to be solved by this technology are as follows: 1. Use a two-step balling method to make these barren materials stably balled and with good ball strength; 2. Use an efficient fluidized bed to efficiently dry, preheat and improve the ball strength, creating good conditions for the calcination of the balls in the rotary kiln; 3. The high-temperature ceramsite discharged from the kiln is efficiently and quickly cooled by an efficient fluidized bed, which, on the one hand, enables the sintered ceramsite to be efficiently cooled and improves the strength of the ceramsite, and on the other hand, the hot air after drying is used as the combustion air of the rotary kiln and the drying and preheating air of the wet balls; 4. According to the material properties and product goals, the drying and preheating air volume and the drying and preheating time of the product are reasonably determined, on the one hand, to ensure sufficient ball strength, and on the other hand, to make full use of the calorific value of the coal gangue itself; 5. Use a biomass fuel burner as the main fuel for ceramsite firing in coal-free areas. The innovative ceramsite production process is low-carbon, environmentally friendly and green, and the heat consumption of ceramsite firing is reduced to below 2781KJ / kg. Summary of the invention

[0007] The object of the present invention is to provide a method and a system for comprehensively utilizing coal-based solid waste to produce ceramsite, so as to solve the problems raised in the above-mentioned background technology.

[0008] To solve the above technical problems, the technical solution provided by the present invention is as follows: A method and a system for comprehensively utilizing coal-based solid waste to produce ceramsite, specifically including the following steps:

[0009] 1) Two-step ball forming process: This system consists of a slurry storage bin, a powder storage bin, a plunger pump, a powder scale, a feeding fan, a granulator, a ball forming machine, a dust collector and a conveying belt; the slurry storage bin and the powder storage bin are used to store slurry and powder; the plunger pump is used to transport and measure the slurry; the powder scale is used to measure the powder, and the feeding fan is used to transport the powder; the granulator is used to complete the drying and granulation of the slurry; the ball forming machine is used to complete the ball forming of the core and the powder; the dust collector is used to purify the dust-containing gas; the conveying equipment is used to transport the materials; the slurry is transported to the granulation tower by the plunger pump, and in the granulation tower, the slurry is fully dispersed from top to bottom in the hot air flow from bottom to top, and its moisture is quickly reduced to 4-6%, and with the larger-sized particles among them as the center, it combines with the sprayed powder to form granular materials with a diameter of 1.8-2.2 mm; the granular materials are immediately sent into the ball forming machine as the ball core;

[0010] After the ball core enters the ball forming machine, it further combines with the powder and water mist, and the ball diameter further increases during rolling. After reaching the required diameter, it is discharged from the ball forming machine and enters the ball conveying belt.

[0011] 2) Fluidized drying and preheating process: This system consists of a roller screen, a fluidized dryer, a fluidized preheater, a gas-solid separator, a kiln head blower, a rotary kiln, and a high-temperature blower; the roller screen is used to screen out unqualified balls; the fluidized dryer uses low-temperature gas below 350 °C to dry the balls, bake out the moisture in the balls, and at the same time slightly increase the temperature of the balls; the fluidized preheater uses high-temperature gas at 950-1050 °C from the rotary kiln to quickly preheat the dried balls, and the temperature of the balls rises rapidly; the wet balls are transported to the roller screen by the belt conveyor, the unqualified balls are screened out, the qualified balls enter the fluidized dryer to be dried, and then enter the fluidized preheater to be quickly heated and preheated; the preheated ceramsite balls enter the rotary kiln for calcination;

[0012] 3) Fluidized cooling process: This system consists of a kiln head hood, a quenching bed, a cooling bed, a cooling fan, a medium-temperature air outlet, a medium-temperature air blower, and a ceramsite conveyor; the kiln head hood is used to connect the rotary kiln and the fluidized cooling machine. The secondary air required for fuel combustion in the kiln enters the rotary kiln from the kiln head hood, and the sintered ceramsite falls from the kiln head into the quenching bed below the kiln head hood for rapid cooling; the extremely cooled ceramsite enters the cooling bed for cooling. As the cooling bed moves forward, the ceramsite is continuously transported forward and falls from the discharge port of the cooling machine onto the ceramsite conveyor; after the ceramsite enters the cooling machine, continuous heat exchange occurs between the fluidized bed and natural air, the air temperature rises, and the ceramsite is cooled to an appropriate temperature; the medium-temperature air in the middle and rear parts of the cooling machine is sent by a blower to the fluidized dryer as a drying heat source; the sintered ceramsite falls from the rotary kiln head into the fluidized cooling machine, and the high-temperature ceramsite continuously exchanges heat with natural air on the fluidized bed. The cooled ceramsite is discharged from the discharge port of the cooling machine and enters the ceramsite conveying equipment. The high-temperature air after heat exchange enters the rotary kiln as the air for fuel combustion at the kiln head, and the remaining air is sent as medium-temperature air to the ball fluidized dryer as a drying heat source;

[0013] 4) Application of biomass fuel in ceramsite production: Biomass fuel is derived from crop straws, withered leaves, and branches pruned from trees; the main fuel for this project is biomass fuel, and only a part of fossil fuel is used during production fluctuations and when starting the kiln; the characteristics of biomass fuel are high volatile content, Vf = 60 - 80%, and fast combustion speed during calcination in the kiln; low density, between 0.55 - 0.75 t / m 3 , short flight distance in the kiln; insufficient length of the burning zone in the kiln; the traditional pulverized coal burner for rotary kilns cannot adapt; it is necessary to redesign the structure of the kiln head burner; the kiln head burner system includes a suspension and moving mechanism, a primary air channel, a biomass fuel channel and distributor, inner and outer air channels and adjustment mechanisms, and a burner head.

[0014] Preferably, the slurry in step 1) is sludge, coal slime, silt, red mud, or gasification slag.

[0015] The advantages of the present invention are as follows: ① In the prior art for treating coal-based solid waste, the (air-dried basis) ratio is about 60%, while the present invention can increase the coal gangue ratio to 70% - 95%; ② For the coal-based high-strength ceramsite produced by the prior art, the cylinder compressive strength is mostly between 3.0 - 10.0 MPa. By applying this technology, the cylinder compressive strength can be increased to 12.0 - 25.0 MPa, easily meeting the requirements of high-strength ceramsite; ③ The heat consumption of the prior art (for substances with calorific value in the raw and fuel materials, the mass consumed per unit ceramsite multiplied by the cumulative calorific value) is on average about 4500 KJ / kg, while the firing heat consumption of the ceramsite of the present invention is reduced to below 2781 KJ / kg; ④ The main fuel of the present invention is biomass fuel, which is a clean and renewable energy form. Description of the Drawings

[0016] Figure 1 It is the process flow diagram of the two-step pelletizing process.

[0017] Figure 2 It is the process flow diagram of fluidized drying and preheating process.

[0018] Figure 3 It is the process flow diagram of fluidized cooling process.

[0019] Figure 4 It is the overall structure diagram of the kiln head burner system. Specific embodiments

[0020] The following specific embodiments are used to illustrate the present invention, but not to limit the present invention.

[0021] Embodiment

[0022] A method and system for comprehensively utilizing coal-based solid waste to produce ceramsite specifically include the following steps:

[0023] 1) Two-step pelletizing process: This system consists of a slurry bin 1, a powder bin 3, a plunger pump 2, a powder scale 6, a feeding fan 7, a granulator 5, a pelletizer 8, a dust collector 4 and a conveyor belt; the slurry bin and the powder bin are used to store slurry and powder; the plunger pump is used to transport and meter the slurry; the powder scale is used to meter the powder, and the feeding fan is used to transport the powder; the granulator is used to complete the drying and granulation of the slurry; the pelletizer is used to complete the pelletizing of the pellet core and powder; the dust collector is used to purify the dust-containing gas; the conveying equipment is used to transport the materials; the connection relationship of each part is shown in Figure 1 , the slurry is represented by red, the powder, pellet core and pellet are represented by cyan, the dust-containing gas is represented by blue, and the purified gas is represented by green. The flow directions of each material and air flow are represented by arrows. The slurry is transported to the granulation tower by a plunger pump. In the granulation tower, the slurry is fully dispersed from top to bottom in the hot air flow from bottom to top. Its moisture is quickly reduced to 4-6%, and with the larger diameter particles as the center, it combines with the sprayed powder to form 1.8-2.2 mm granular materials; the granular materials are immediately sent to the pelletizer as pellet cores;

[0024] After the pellet cores enter the pelletizer, they further combine with the powder and water mist, and the pellet diameter further increases during rolling. After reaching the required diameter, they are discharged from the pelletizer and enter the pellet conveying belt;

[0025] 2) Fluidized drying and preheating process: This system consists of a roller screen 21, a fluidized bed dryer 22, a fluidized bed preheater 23, a gas-solid separator 26, a kiln head blower 24, a rotary kiln 25, and a high-temperature blower 26; the roller screen is used to screen out unqualified material balls; the fluidized bed dryer uses low-temperature gas below 350°C to dry the material balls, drying out the moisture in the material balls and slightly increasing the temperature of the material balls at the same time; the fluidized bed preheater uses the high-temperature gas at 950 - 1050°C from the rotary kiln to quickly preheat the dried material balls, and the temperature of the material balls rises rapidly; the connection relationship of each part is shown in Figure 2 , the slurry is represented in red, the powder, the material core, and the material balls are represented in cyan, the dusty gas is represented in blue, and the purified gas is represented in green. The flow directions of each material and gas are indicated by arrows. The wet material balls are transported to the roller screen by a belt conveyor, the unqualified material balls are screened out, the qualified material balls enter the fluidized bed dryer to be dried, and then enter the fluidized bed preheater to be quickly heated and preheated; the preheated ceramsite balls enter the rotary kiln for calcination;

[0026] 3) Fluidized cooling process: This system consists of a kiln head hood 32, a rapid cooling bed 33, a cooling bed 34, a cooling fan 37, a medium-temperature air outlet 35, a medium-temperature air blower 36, and a ceramsite conveyor 38; the kiln head hood is used to connect the rotary kiln and the fluidized cooler, and the secondary air required for fuel combustion in the kiln enters the rotary kiln 31 from the kiln head hood, and the sintered ceramsite falls from the kiln head into the rapid cooling bed under the kiln head hood for rapid cooling; the extremely cooled ceramsite enters the cooling bed for cooling, and as the cooling bed moves forward, the ceramsite is continuously transported forward and falls from the discharge port of the cooler onto the ceramsite conveyor; after the ceramsite enters the cooler, continuous heat exchange is carried out with natural air through the fluidized bed, the air temperature rises, and the ceramsite is cooled to an appropriate temperature; the medium-temperature air in the middle and rear parts of the cooler is sent by the blower to the fluidized bed dryer as the drying heat source; the connection relationship of each part is shown in Figure 3 , the ceramsite is represented in cyan, the dusty gas is represented in blue, and the natural air is represented in green. The flow directions of each material and gas are indicated by arrows. The sintered ceramsite falls from the kiln head of the rotary kiln into the fluidized cooler, and the high-temperature ceramsite continuously exchanges heat with natural air on the fluidized bed. The cooled ceramsite is discharged from the discharge port of the cooler and enters the ceramsite conveying equipment, and the high-temperature air after heat exchange enters the rotary kiln as the air for fuel combustion at the kiln head, and the remaining air is sent to the material ball fluidized bed dryer as the drying heat source;

[0027] 4) Application of biomass fuel in ceramsite production: Biomass fuel is derived from crop straws, withered leaves, and branches trimmed from trees; the main fuel for this project is biomass fuel, and only a part of fossil fuel is used during production fluctuations and when starting the kiln; the characteristics of biomass fuel are high volatile content, Vf = 60 - 80%, and fast combustion speed during calcination in the kiln; light density, at 0.55 - 0.75t / m 3, the flight distance in the kiln is short; the length of the firing zone in the kiln is not enough; the traditional pulverized coal burner for rotary kiln cannot adapt; the structure of the kiln head burner must be redesigned; the kiln head burner system suspension moving mechanism, primary air channel, biomass fuel channel and distributor, internal and external air channels and adjustment mechanism, burner head.

[0028] like Figure 4 As shown, 41. Biomass fuel inlet, 42. Primary air inlet, 43. Biomass fuel distributor, 44. Adjustment mechanism, 45. Central air channel, 46. Inner air channel, 47. Outer air channel, 48. Pressure gauge, 49. Suspension travel mechanism

[0029] As a preferred embodiment of this example, the slurry in step 1) is sewage sludge, coal sludge, silt or red mud.

[0030] Technical features of the newly designed biomass fuel kiln head burner:

[0031] 1) Biomass fuel diffuses and burns under the wrapping of internal and external winds, and the burning zone can be extended by 3-4 meters;

[0032] 2) High Vf biomass combustion requires higher flame thrust to increase the length of the burning zone. Configure high primary air volume;

[0033] 3) Maintain a smooth flame in the kiln, and the swirl intensity and swirl angle of the burner should not be too large;

[0034] 4) In order to adapt to the changing kiln conditions, the kiln head burner should have good online adjustable performance in hot state. The axial wind pressure can be adjusted online at 10-45kpa; the thickness of the flame can be adjusted online; the cross-sectional area of the internal wind is required to be adjustable at -50+100% of the zero cross-sectional area;

[0035] 5) This burner has 2 to 3 circular channel outputs to reduce the chance of blockage;

[0036] 6) To ensure the necessary flame length, an online adjustable flame hood is required. The adjustable length Δx = 0-70mm. The firing zone can be expanded to 7-14 meters in length, compensating for the short firing zone.

[0037] 7) In order to quickly adapt to the combustion characteristics of different types of biomass fuels, the internal wind cyclone is replaceable. The swirl angles are 25°, 32°, 37°, and 42°. It can be quickly replaced within 4 hours of stopping the kiln.

[0038] Connection relationship of each part: the primary air coming out of the Roots blower enters the burner and is divided into central air, inner air and outer air in the internal channel; the air from the feeding Roots blower carries the biomass fuel into the burner and is distributed to 2 to 3 channels by the distributor; then the biomass fuel entering the burner is mixed with the inner and outer air and then sprayed into the rotary kiln for combustion.

[0039] According to the requirements of the combustion time in the kiln, different biomass fuels are pressed into particulate matters with corresponding particle sizes, and the biomass particulate matters are sent to the biomass fuel inlet of the burner at the kiln head by compressed gas from a Roots blower. The biomass particles entering the burner are mixed with the inner and outer air of the primary air to form a biomass material flow. The biomass therein is driven by the air flow and enters the kiln at a relatively high speed, and burns after being mixed with the high-temperature secondary air in the kiln. By adjusting the flow rate and pressure of the inner and outer air, a flame shape required by the process can be formed. A smooth and suitable flame shape is a necessary condition for the calcination of ceramsite in the kiln.

[0040] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method and system for comprehensively utilizing coal-based solid waste to produce ceramsite, characterized in that, Specifically, it includes the following steps: 1) Two-step pelletizing process: This system consists of a slurry bin, a powder bin, a plunger pump, a powder scale, a feeding fan, a granulator, a pelletizer, a dust collector and a conveyor belt; the slurry bin and the powder bin are used to store slurry and powder; the plunger pump is used to transport and measure the slurry; the powder scale is used to measure the powder, and the feeding fan is used to transport the powder; granulation is used to complete the drying and granulation of the slurry; the pelletizer is used to complete the pelletization of the material core and the powder; the dust collector is used to purify the dust-containing gas; the conveying equipment is used to transport the materials; the slurry is transported to the granulation tower by the plunger pump, and in the granulation tower, the slurry is fully dispersed from top to bottom in the hot air flow from bottom to top, and its moisture is quickly reduced to 4-6%, and with the larger-sized particles among them as the center, it combines with the sprayed powder to form granular materials of 1.8-2.2 mm; the granular materials are then sent into the pelletizer as pellet cores; After the pellet cores enter the pelletizer, they further combine with the powder and water mist, and the pellet diameter further increases during rolling. After reaching the required diameter, they are discharged from the pelletizer and enter the pellet conveying belt; 2) Fluidized drying and preheating process: This system consists of a roller screen, a fluidized dryer, a fluidized preheater, a gas-solid separator, a kiln head blower, a rotary kiln, and a high-temperature fan; the roller screen is used to screen out unqualified pellets; the fluidized dryer uses low-temperature gas below 350 °C to dry the pellets, bake out the moisture in the pellets, and at the same time slightly increase the temperature of the pellets; the fluidized preheater uses high-temperature gas of 950-1050 °C from the rotary kiln to quickly preheat the dried pellets, and the temperature of the pellets rises rapidly; the wet pellets are transported to the roller screen by a belt conveyor, the unqualified pellets are screened out, the qualified pellets enter the fluidized dryer to be dried, and then enter the fluidized preheater to be quickly heated and preheated; the preheated ceramsite pellets enter the rotary kiln for calcination; 3) Fluidized cooling process: This system consists of a kiln head hood, a quench bed, a cooling bed, a cooling fan, a medium-temperature air outlet, a medium-temperature air blower, and a ceramsite conveyor; the kiln head hood is used to connect the rotary kiln and the fluidized cooler, and the secondary air required for fuel combustion in the kiln enters the rotary kiln from the kiln head hood, and the sintered ceramsite falls from the kiln head into the quench bed below the kiln head hood for rapid cooling; the extremely cooled ceramsite enters the cooling bed for cooling. As the cooling bed moves forward, the ceramsite is continuously transported forward and falls from the discharge port of the cooler onto the ceramsite conveyor; after the ceramsite enters the cooler, it continuously exchanges heat with natural air through the fluidized bed, the air temperature rises, and the ceramsite is cooled to an appropriate temperature; the medium-temperature air in the middle and rear parts of the cooler is sent to the fluidized dryer by a blower as the drying heat source; the sintered ceramsite falls from the kiln head of the rotary kiln into the fluidized cooler, and the high-temperature ceramsite continuously exchanges heat with natural air on the fluidized bed. The cooled ceramsite is discharged from the discharge port of the cooler and enters the ceramsite conveying equipment, and the high-temperature air after heat exchange enters the rotary kiln as the air for fuel combustion at the kiln head, and the remaining air is sent to the pellet fluidized dryer as the drying heat source; 4) Application of Biomass Fuel in Pellet Production: Biomass fuel is sourced from crop straws, withered branches and leaves, and pruned branches of trees; the main fuel for this project is biomass fuel, and only a part of fossil fuel is used during production fluctuations and when starting the kiln; the characteristics of biomass fuel are high volatile content, Vf = 60 - 80%, and fast combustion speed during calcination in the kiln; light density, at 0.55 - 0.75t / m 3 , short flight distance in the kiln; insufficient length of the firing zone in the kiln; the traditional coal powder burner for rotary kilns cannot adapt; it is necessary to redesign the structure of the burner at the kiln head; the burner system at the kiln head includes a suspension moving mechanism, a primary air channel, a biomass fuel channel and distributor, inner and outer air channels and adjustment mechanisms, and a burner head.

2. According to claim 1, wherein: The slurry in step 1) is sludge, slime, silt, red mud or gasification slag.

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