System and method for resource treatment of gasified slag

Abstract

The invention discloses a gasification slag resource treatment system which comprises a slurry bin and a powder bin, and slurry output by the slurry bin and powder output by the powder bin are mixed in a granulator; material cores output by the pelletizer are conveyed to the balling disc through the belt conveyor; material balls output by the balling disc are conveyed to the double-layer vibrating screen by the belt conveyor, and qualified material balls on the double-layer vibrating screen enter the fluidized drying machine to be dried; dry gasified slag balls discharged from a discharge port of the dryer enter the suspended cooler through a blanking pipe and a turning plate air locking valve; and residual air from the suspended cooler is sent to the hot blast stove to be used as combustion air. The low-temperature waste heat can be used for drying the gasified fine slag in an environment-friendly mode, and the beneficial effects of being high in drying efficiency and low in drying energy consumption are achieved.

Description

Technical Field

[0001] This invention relates to the field of gasification slag resource utilization technology, specifically to a system and method for gasification slag resource utilization. Background Technology

[0002] In existing technologies, fine slag particles are small, with an average particle size of about 3.0 micrometers and a specific surface area of ​​up to 1000 m². 2 / kg (specific surface area of ​​cement not exceeding 400m²) 2 / kg). In conventional drying systems, fine particles easily escape into the dust collection system with the hot drying air, causing the dust collection system to malfunction and resulting in excessive dust emissions. The moisture content of the fine residue is 35-50%, and it should be used as an alternative fuel after treatment. The temperature of the hot drying air should not exceed 270℃, and current conventional drying methods make it difficult to reduce the moisture content to below 10%. The dried fine residue is also prone to flying away during packaging, transportation, and use, causing secondary pollution.

[0003] Existing technologies for drying gasification slag have low cost-effectiveness: Conventional technologies use gases below 270°C to dry gasification slag, which is difficult to dry and can only reduce the moisture content to close to 10%. This makes the gasification slag difficult to transport and use, and the calorific value of the gasification slag is low. While high-temperature gas drying can reduce the moisture content, it results in a large loss of calorific value of the gasification slag and also poses certain safety hazards.

[0004] Existing technologies suffer from small gas-solid contact areas and difficulty in maintaining stable contact times. They require relatively high gas temperatures (typically around 400℃), and the gas exchanges heat with the wet material only once. The temperature of the exhaust gas after drying is also high, resulting in an average drying heat consumption of around 2600 KJ / kg.

[0005] The moisture content of the fine residue is 35-50%. In conventional drying systems, the fine residue is to be used as an alternative fuel after treatment. The temperature of the drying hot air should not exceed 270℃. It is difficult for the current conventional drying methods to reduce its moisture content to below 10%. The dried fine residue is very easy to fly away during packaging, transportation and use, causing secondary pollution.

[0006] Existing conventional technologies cannot dry and gasify fine slag: fine particles are very easy to escape into the dust collection system in large quantities with the drying hot air, which on the one hand causes the dust collection system to be unstable, and on the other hand causes dust emissions to exceed the standard.

[0007] In summary, the shortcomings of existing technologies are:

[0008] The drying process can easily cause malfunctions in the dust collection system, leading to excessive emissions; it is difficult to dry fine residue with an air temperature below 270℃; after drying, the fine residue particles are very easy to fly away during packaging, transportation, and use, causing secondary pollution. Summary of the Invention

[0009] In order to overcome the defects of the existing technology, the purpose of this invention is to provide a system and method for the resource-based disposal of gasification slag. This system and method can use low-temperature waste heat to dry the gasification fine slag in an environmentally friendly manner, and has the characteristics of high drying efficiency and low drying energy consumption.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A system for the resource utilization of gasification slag includes a slurry silo 1 and a powder silo 3. The slurry output from the slurry silo 1 and the powder output from the powder silo 3 are mixed in a granulator 5 to generate material nuclei. The material nuclei output from the granulator 5 are conveyed to a pelletizing disc 8 via a belt conveyor. The pellets output from the pelletizing disc 8 are conveyed to a double-layer vibrating screen 9 via a belt conveyor. The qualified pellets on the double-layer vibrating screen 9 enter a fluidized bed dryer 10 for drying. The dried gasification slag pellets discharged from the outlet of the dryer 10 enter a suspension cooler 12 via a feed pipe and a flap valve 11. The residual air from the suspension cooler 12 is sent to a hot blast stove 14 as combustion air.

[0012] An ammonia spray gun 15 is installed on the outlet pipe of the hot blast stove 14. The ammonia spray gun 15 sprays ammonia to remove NO from the hot gas. X Hot gas and circulating gas are drawn by high-temperature induced draft fan 16 and enter the second chamber of fluidized bed dryer 10 as heat source to exchange heat with the material balls. Low-temperature gas exiting the second chamber is filtered by gas-solid separator 18 and cloud demisting spray gun 19, and then drawn by low-temperature induced draft fan 20 into the first chamber of fluidized bed dryer 10. The purified low-temperature gas exchanges heat with the wet material balls and then exits the fluidized bed dryer 10.

[0013] The slurry at the bottom of the slurry bin 1 is pumped to the granulator 5 by the plunger pump 2; the powder at the bottom of the powder bin 3 is measured by the powder metering scale 6 and then pumped to the granulator 5 by the feeding fan 7.

[0014] The slurry and powder entering the granulator 5 form continuous small nuclei of about 10 micrometers in the granulator 5. The powder surrounds the small nuclei and gradually forms nuclei of about 500 micrometers, which are discharged from the bottom of the granulator 5.

[0015] The spherical disc 8 rotates to further combine the powder and the core to form spheres with a diameter of about 2 mm.

[0016] The double-layer vibrating screen 9 consists of two types of screen surfaces with different screen openings: a 3mm screen surface on top and a 1mm screen surface on the bottom. The material balls first enter the upper 3mm screen surface, and the material balls with screen openings smaller than 3mm fall through the upper screen surface to the lower 1mm screen surface. The material balls larger than 3mm on the upper screen surface and the material balls smaller than 1mm that are screened off the lower screen surface are all transported to the waste area for reuse as waste. The material balls on the lower 1mm screen surface are qualified material balls and enter the fluidized bed dryer 10 for drying.

[0017] The fluidized bed dryer 10 includes chamber II and chamber I connected end to end; the fluidized bed dryer 10 forms a material layer of about 180 mm thick on the material bed; gas at 240-300°C enters the dryer 10, passes through the material layer, and continuously exchanges heat with the material balls on the fluidized bed to dry out the moisture in the material balls, while raising the temperature of the material balls until the temperature of the material balls reaches the target value.

[0018] The exhaust gas from the fluidized bed dryer 10 enters the condenser 17, where most of the water vapor is condensed into water droplets and discharged (the condensate is used for powder pelletizing). A portion of the gas then directly enters the bag filter 21, and the purified gas is discharged into the chimney and then into the atmosphere via the drying system exhaust fan 22. The remaining gas is guided by the high-temperature fan 16 and recirculated back into the fluidized bed dryer 10. The airflow for both portions is adjusted according to the dryer's parameters. Airflow adjustment is achieved through automatic regulating valves on the pipeline.

[0019] The beneficial effects of this invention are:

[0020] This invention solves the problem of the inability to apply fine gasification slag in large quantities, and provides resource-based treatment for this solid waste: Conventional drying technologies cannot solve the dust problem during drying, transportation, and use due to the extremely small particle size of the gasification slag (around 3.0 micrometers), thus preventing its large-scale application. This invention first granulates the slag into pellets, then dries it, which avoids excessive dust generation during production. A small amount of dust is removed using cloud-based dust collection technology, the drying exhaust gas is recycled, and a small amount of emitted gas is further purified by bag filters before being released, ensuring stable compliance with emission requirements.

[0021] This invention first significantly increases the contact area and gas-solid contact time between hot gas and wet slag through efficient suspension drying, thus making it possible to use low-temperature (below 270℃) gas as a drying heat source. The slurry from slurry silo 1 and the powder from powder silo 3 are dried and mixed in granulator 5, forming 1-3mm pellets. Hot gas passes through the fluidized bed of the pellet dryer, making full contact with the pellets. The drying hot gas can exchange heat with the wet material 2-3 times as needed. This forms a highly efficient and stable gas-solid heat exchange, reducing the moisture content of the gasified fine slag pellets to below 5.0% within a suitable gas-solid heat exchange time. This improves the material's calorific value and cost-effectiveness, significantly expands its transportation radius, and broadens its application range.

[0022] The gasification slag dried product produced by this invention has a high calorific value utilization rate, which reduces the heat consumption and coal cost of enterprises and reduces carbon emissions. The gasification slag pellets dried by this technology can be directly injected into the kiln for combustion. Compared with adding raw materials, the calorific value utilization rate of gasification slag can be increased from about 50% to nearly 100%.

[0023] The present invention features a large gas-solid contact area, allowing for 2-3 heat exchanges between the gas and wet material as needed, with the gas-solid heat exchange time being flexibly adjustable. This results in a reduced exhaust gas temperature and a drying heat consumption below 2150 KJ / kg, approximately 17% lower than existing technologies.

[0024] The drying heat consumption of this invention is reduced from 2600 KJ / kg to 2150 KJ / kg. Converted to standard coal, the coal consumption for drying is reduced from 88.82 kg standard coal / t gasification slag to 73.44 kg standard coal / t gasification slag. Taking 2 million tons of dry slag as an example, it can save 30,744 tons of standard coal and reduce CO2 emissions by 76,645 tons.

[0025] This invention can safely and stably process gasification slag into pellets with a moisture content of 5.0% and a particle size of 1-3mm, which can then be dried and used directly in heating kilns. Attached Figure Description

[0026] Figure 1 This is a flowchart of the two-step sphere forming process.

[0027] Figure 2 This is a schematic diagram of a fluidized bed drying process.

[0028] Figure 3 This is a process flow diagram for the gasification fine slag pelletizing and drying process.

[0029] Figure label:

[0030] 1. Slurry silo, 2. Plunger pump, 3. Powder silo, 4. Dust collector, 5. Granulator, 6. Powder weighing scale, 7. Feeding fan, 8. Pelletizing disc, 9. Double-layer vibrating screen, 10. Fluidized bed dryer, 11. Flip-plate airlock valve, 12. Suspension cooler, 13. Hot air furnace heat exchanger, 14. Hot air furnace, 15. Denitrification ammonia water spray gun, 16. High-temperature induced draft fan, 17. Condenser, 18. Gas-solid separator, 19. Cloud dust removal spray gun, 20. Low-temperature induced draft fan, 21. Bag filter, 22. Drying system exhaust fan. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings.

[0032] like Figures 1-3 As shown, this invention discloses a system and method for the resource-based disposal of gasification slag, including:

[0033] 1. Two-step ball-forming process:

[0034] By first forming fine particles that are difficult to dry to low moisture content with low-temperature gas into pellets, the phenomenon of fine particles escaping into the dust collection system with the drying hot air during processing is greatly reduced, thus avoiding excessive dust emissions caused by the unstable operation of the dust collection system.

[0035] This system consists of a slurry silo 1, a powder silo 3, a plunger pump 2, a powder weighing scale 6, a feeding fan 7, a granulator 5, a pelletizer 8, a dust collector 4, and a conveyor belt.

[0036] After being discharged from the bottom of slurry silo 1, the slurry is conveyed by plunger pump 2 and sprayed into granulator 5. The powder is discharged from the bottom of powder silo 3, weighed by powder metering scale 6, and then conveyed into granulator 5 by feeding fan 7. The slurry entering granulator 5 forms continuous small nuclei (approximately 10 micrometers). The incoming powder is fully dispersed, surrounding the small nuclei, gradually forming larger nuclei (approximately 500 micrometers) which are discharged from the bottom of granulator 5. The granulated nuclei are conveyed by conveyor belt into pelletizing disc 8, while the powder is conveyed by belt conveyor to pelletizing disc 8. In the rotating pelletizing disc 8, the powder and nuclei further combine to form pellets with a diameter of approximately 2 mm.

[0037] Slurry bin 1 and powder bin 3 are used to store slurry and powder.

[0038] The plunger pump 2 is used to transport and measure slurry; the powder weighing scale 6 is used to measure powder; and the feeding blower 7 is used to transport powder.

[0039] Granulator 5 is mainly used to dry and granulate slurry; pelletizing disc 8 is used to pelletize material cores and powders.

[0040] Dust collector 4 is used to purify dust-laden gas; conveying equipment is used to transport materials.

[0041] The connections between the various parts are shown in the "Two-Step Process Flow Diagram". Slurry is represented in red, powder, material cores, and material balls are represented in cyan, dust-laden gas is represented in blue, and purified gas is represented in green. The direction of each material and airflow is indicated by arrows.

[0042] All the slurry and a portion of the powder (approximately 20%) are first processed into nuclei in granulator 5. These nuclei then combine with the remaining 80% of the powder to form pellets approximately 2mm in diameter. This flow pattern results in a simple and efficient process while also making full use of the high-moisture-content gasification slag (slurry) initially fed into the plant. The benefits include streamlined material flow and the ability to stably form high-strength pellets from lean materials (those with very poor plasticity).

[0043] The slurry (original wet gasification slag, moisture content 30-45%) is pumped to the granulator 5 by the plunger pump 2. In the granulator 5, the slurry is fully dispersed from top to bottom in the hot airflow (temperature below 270℃) from bottom to top. Its moisture content is quickly reduced to 5%, and the larger particles are combined with the injected powder to form granules of about 0.5mm. The granules are then sent to the pelletizer 8 as pellet nuclei.

[0044] After entering the pelletizer 8, the pellet cores further combine with the powder and water mist, and the diameter of the pellets increases further during rolling. Once the required diameter is reached, the pellets are discharged from the pelletizer 8 and enter the pellet conveyor belt.

[0045] The ratio of spheres to powder is 25%:75%.

[0046] 2. Fluidized bed drying process

[0047] This system consists of a double-layer vibrating screen 9, a fluidized bed dryer 10, a gas-solid separator 18, and a low-temperature induced draft fan 20.

[0048] The material balls are conveyed by a belt conveyor to a double-layer vibrating screen 9, which consists of two screen surfaces with different screen openings: a 3mm screen surface on top and a 1mm screen surface on the bottom. The material balls first enter the upper 3mm screen surface, and the material balls with screen openings smaller than 3mm fall through the upper screen surface to the lower 1mm screen surface. The material balls larger than 3mm on the upper screen surface and the material balls smaller than 1mm that are screened off the lower screen surface are all transported to the waste area for reuse as waste material. The material balls on the lower 1mm screen surface are qualified material balls and enter the fluidized bed dryer 10 for drying.

[0049] Qualified pellets enter the fluidized bed dryer 10, forming a material layer of about 180mm thickness on the material bed (this thickness ensures that the deformation rate of the pellets is less than 95% and that the pellets have a reasonable heat exchange time). Gas at 240-300℃ passes through the material layer and continuously exchanges heat with the pellets on the fluidized bed, drying out the moisture in the pellets and slightly increasing the temperature of the pellets until the moisture content of the pellets is reduced to the target value.

[0050] The temperature of the dried pellets is too high (around 100℃), so they must be cooled down before entering the conveying and storage system. This also reduces the heat loss of the dry gasification slag.

[0051] The dry gasified slag pellets discharged from the outlet of the dryer 10 enter the suspension cooler 12 through the feed pipe and the flap lock valve 11.

[0052] The flue gas from the hot air furnace and the circulating gas are drawn by the high-temperature induced draft fan 16 and enter the II chamber of the fluidized bed dryer 10 as a heat source to exchange heat with the material balls. The low-temperature gas exiting the II chamber is purged by the gas-solid separator 18 and the cloud demisting spray gun 19, and then drawn by the low-temperature induced draft fan 20 into the I chamber of the fluidized bed dryer. The purified low-temperature gas exchanges heat with the wet material balls and then exits the fluidized bed dryer.

[0053] The exhaust gas from the fluidized bed dryer enters the condenser 17, where most of the water vapor is condensed and discharged (the condensate is used for powder pelletizing). A portion of the gas then directly enters the bag filter, and the purified gas is discharged through the drying system exhaust fan 22 into the chimney and then into the atmosphere. The remaining gas is guided by the high-temperature fan 16 and recirculated back into the dryer. The airflow for both portions is adjusted according to the dryer's parameters. Airflow adjustment is achieved through automatic regulating valves on the pipeline. This airflow design effectively utilizes the residual heat from the drying process while significantly reducing the pressure on the system's end dust collector.

[0054] The connections between the various parts are shown in the "Fluorescent Drying Process Flow Diagram". Slurry is represented in red, powder, material cores, and material balls are represented in cyan, dust-laden gas is represented in blue, and purified gas is represented in green. The direction of each material and airflow is indicated by arrows.

[0055] In the fluidized bed dryer 10, the airflow flows from top to bottom at the rear, where the high-temperature airflow exchanges heat with the drier pellets. At the front, the airflow flows from bottom to top, preventing the lower pellets from drying poorly and deforming. The high-temperature gas enters from the rear, first exchanging heat with the drier pellets, then cooling to approximately 180°C before exchanging heat with the wet pellets. This prevents the wet pellets from heating up too quickly, causing excessive moisture evaporation and resulting in more pellet bursts. The result is a high yield of finished pellets, less waste pellets requiring rework, high drying system output, and reduced costs.

[0056] 3. Suspension cooling process

[0057] This system consists of a suspended cooler 12, a material feeding box, and an airlock discharge valve.

[0058] The pellets, around 100°C, exiting the fluidized bed dryer 10, enter the feeding box of the suspension cooler 12 via the feeding pipe and airlock valve. After being spread by the feeding plate, they are fully dispersed in the rising ambient air. The pellets rapidly exchange heat with the ambient air, causing a significant decrease in pellet temperature and an increase in gas temperature. The excess air from the suspension cooler 12 is sent to the hot blast stove 14 as combustion air. An ammonia spray gun 15 is installed on the hot blast stove outlet pipe to inject ammonia water to remove NO from the hot gas. X .

[0059] The connections between the various parts are shown in the "Suspension Cooling Process Flow Diagram". Particles are represented in cyan, dust-laden gas in blue, and natural wind in green. The direction of each material and airflow is indicated by arrows.

[0060] In the suspended cooler 12, the airflow enters from the bottom of the device, and the hot material balls enter from the middle of the device and are dispersed into the airflow at ambient temperature. Due to the good dispersion effect, the airflow and the hot material balls complete heat exchange instantly (about 0.05 seconds), and the material balls are cooled to about 60°C. The result is good dispersion of the material balls and rapid and thorough heat exchange.

[0061] After cooling, the ceramsite falls from the outlet of the suspension cooler 12 into the belt conveyor and is sent to the storage silo for storage, packaging and shipping.

Claims

1. A system for the resource-based disposal of gasification slag, characterized in that, The system includes a slurry silo (1) and a powder silo (3). The slurry output from the slurry silo (1) and the powder output from the powder silo (3) are mixed in a granulator (5). The powder output from the granulator (5) is conveyed to a pelletizing disc (8) via a belt conveyor. The pellets output from the pelletizing disc (8) are conveyed to a double-layer vibrating screen (9) via a belt conveyor. The qualified pellets on the double-layer vibrating screen (9) enter a fluidized bed dryer (10) for drying. The dry gasified slag pellets discharged from the outlet of the dryer (10) enter a suspended cooler (12) via a discharge pipe and a flap valve (11). The residual air from the suspended cooler (12) is sent to a hot blast stove (14) as combustion air. An ammonia spray gun (15) is installed on the outlet pipe of the hot blast stove (14). The ammonia spray gun (15) sprays ammonia to remove NO from the hot gas. X Hot gas and circulating gas are drawn by a high-temperature induced draft fan (16) and enter the second chamber of the fluidized bed dryer (10) as a heat source to exchange heat with the material balls. The low-temperature gas exiting the second chamber is purged by a gas-solid separator (18) and a cloud demisting spray gun (19) and then drawn by a low-temperature induced draft fan (20) into the first chamber of the fluidized bed dryer (10). The purified low-temperature gas exchanges heat with the wet material balls and then exits the fluidized bed dryer (10).

2. The system for resource utilization and disposal of gasification slag according to claim 1, characterized in that, The slurry at the bottom of the slurry bin (1) is pumped to the granulator (5) by a plunger pump (2); the powder at the bottom of the powder bin (3) is measured by a powder metering scale (6) and then pumped to the granulator (5) by a feeding fan (7).

3. The system for resource utilization of gasification slag according to claim 1, characterized in that, The slurry of the granulator (5) forms continuous small nuclei of about 10 micrometers. The powder surrounds the small nuclei and gradually forms a nucleus of about 500 micrometers, which is discharged from the bottom of the granulator (5).

4. The system for resource utilization of gasification slag according to claim 1, characterized in that, The spherical disc (8) rotates to further combine the powder and the core to form a sphere with a diameter of about 2 mm.

5. A system for the resource-based disposal of gasification slag according to claim 1, characterized in that, The double-layer vibrating screen (9) consists of two screen surfaces with different screen openings: the screen surface with 3mm screen openings is on top, and the screen surface with 1mm screen openings is on the bottom. The material balls first enter the upper 3mm screen surface, and the material balls with screen openings smaller than 3mm fall through the upper screen surface to the lower 1mm screen surface. The material balls larger than 3mm on the upper screen surface and the material balls smaller than 1mm that are screened off the lower screen surface are all transported to the waste area for reuse as waste. The material balls on the lower 1mm screen surface are qualified material balls and enter the fluidized bed dryer (10) for drying.

6. A system for the resource-based disposal of gasification slag according to claim 1, characterized in that, The fluidized bed dryer (10) includes chamber II and chamber I connected end to end; the fluidized bed dryer (10) forms a 180mm thick material layer on the material bed, and gas at 240-300℃ passes through the material layer and continuously exchanges heat with the material balls on the fluidized bed to dry out the moisture in the material balls, while slightly increasing the temperature of the material balls until the moisture content of the material balls is reduced to the target value.

7. A system for the resource-based disposal of gasification slag according to claim 1, characterized in that, The exhaust gas from the fluidized bed dryer (10) enters the condenser (17), where most of the water vapor is condensed into water droplets and discharged. Then, a portion of the gas directly enters the bag filter (21), and the purified gas is discharged into the chimney and then into the atmosphere via the exhaust fan (22) of the drying system. Another portion of the gas is guided by the high-temperature fan (16) to circulate and re-enter the fluidized bed dryer (10).

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