Ash discharging and pneumatic conveying device for high-temperature pyrolysis dust trapping

Abstract

The invention provides an ash discharging and pneumatic conveying device for high-temperature pyrolysis dust trapping. Comprising an upstream dust removal device, an automatic ash discharge system, a water-cooling spiral conveying device, a stock bin and a pneumatic conveying system which are sequentially connected in the material flow direction. High-temperature ash captured by upstream dust removal equipment; the automatic ash discharge system is a double-valve automatic ash discharge sealing system, one valve is always in a closed state in the ash discharge process, and direct communication between upstream dust removal equipment and water-cooling spiral conveying equipment is cut off; the water-cooling spiral conveying equipment provides inert atmosphere, cools the input dust and conveys the dust to the stock bin; the stock bin is used for temporarily storing cooled materials and providing a stable material source for the pneumatic conveying system; the pneumatic conveying system adopts inert gas as a power source, and materials in a stock bin are pressed into a conveying pipeline in a plug flow mode.

Description

Technical Field

[0001] This invention relates to the field of solid material conveying and processing technology, specifically to an apparatus and method for the safe, continuous, and stable discharge and conveying of high-temperature carbonaceous dust (fly ash) in processes such as coal chemical industry, waste incineration, and biomass pyrolysis. Background Technology

[0002] In high-temperature processes such as pulverized coal gasification, fluidized bed boilers, and waste pyrolysis, a large amount of carbonaceous dust with temperatures of 500-800℃ or even higher is generated. These carbon-based high-temperature ashes have two significant characteristics: First, due to their high temperature, they will rapidly oxidize or even ignite and explode if they come into direct contact with air; second, when the temperature drops below the freezing point of some of their components (such as low-condensation-point organic matter, which is usually around 370-450℃), the ash viscosity increases sharply, making it prone to adhesion and blockage, which brings great difficulties to subsequent transportation and treatment.

[0003] Currently, common methods for handling this type of high-temperature ash include using cold upstream dust collection equipment or water quenching. Cold upstream dust collection equipment is bulky, has low cooling efficiency, and is prone to thermal stress cracking due to uneven temperature inside. While water quenching provides rapid cooling, it generates a large amount of water vapor, leading to heat loss, potential equipment corrosion, and moisture content in the material, affecting its subsequent use (such as as a cement admixture).

[0004] Regarding ash removal, traditional single-valve ash removal systems cannot guarantee long-term sealing at high temperatures, and the system pressure fluctuates greatly during ash removal, affecting the stable operation of upstream processes. In terms of conveying, conventional mechanical conveying (such as ordinary screw conveyors) cannot solve the problems of cooling and oxidation of high-temperature ash; while directly using pneumatic conveying of high-temperature ash places extremely high demands on the material of the conveying pipeline, and there is still a risk of condensation and blockage of the high-temperature ash within the pipeline.

[0005] Therefore, there is an urgent need in this field for a comprehensive device that integrates sealed ash discharge, controllable cooling, inert protection, and reliable conveying to solve the safety, blockage, and energy recovery problems in the high-temperature pyrolysis ash treatment process. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide an ash discharge and pneumatic conveying device for high-temperature pyrolysis dust collection. This device enables the safe and sealed discharge of high-temperature ash under an inert atmosphere; it can precisely control the cooling process to prevent material condensation and adhesion in the low-temperature zone; and it uses inert gas for pneumatic conveying, preventing oxidation throughout the process, while also having pipeline anti-clogging function to ensure long-term stable operation of the system.

[0007] The solution of the present invention is: an ash removal and pneumatic conveying device for high-temperature pyrolysis dust collection, comprising an upstream dust removal device, an automatic ash removal system, a water-cooled screw conveyor, a silo, and a pneumatic conveying system connected sequentially along the material flow direction; High-temperature ash collected by upstream dust removal equipment; the automatic ash discharge system is a dual-valve automatic ash discharge sealing system, with one valve always closed during the ash discharge process to cut off the direct connection between the upstream dust removal equipment and the water-cooled screw conveyor. Water-cooled screw conveyors provide an inert atmosphere to cool the incoming dust and transport it to the silo. The silo is used to temporarily store cooled materials and provide a stable material source for the pneumatic conveying system; The pneumatic conveying system uses inert gas as a power source to force the material in the silo into the conveying pipeline in the form of a slug flow.

[0008] Preferably, the automatic ash discharge system includes an upper ash discharge valve, a lower ash discharge valve, an intermediate vertical pipe formed between the two, a balancing valve, a pressure connecting pipe, and an automatic ash discharge control PLC; the pressure connecting pipe connects the intermediate vertical pipe to the upstream dust removal equipment; the balancing valve is installed on the pressure connecting pipe; During ash discharge, the automatic ash discharge control PLC first closes the lower ash discharge valve and opens the upper ash discharge valve and the balancing valve. The ash in the upstream dust removal equipment falls into the middle vertical pipe under the action of gravity and pressure balance. Then, the upper ash discharge valve and the balancing valve are closed, and the lower ash discharge valve is opened again. The ash in the middle vertical pipe falls into the downstream equipment.

[0009] Preferably, the water-cooled spiral conveyor includes a cylinder and a control module; The cylinder is equipped with a low-pressure nitrogen inlet, a low-pressure nitrogen outlet, a material inlet, and a material outlet; a screw conveyor is installed inside the cylinder. The cylinder has a jacketed structure with a circulating cooling medium inside. The control module controls the speed of the screw conveyor, the flow rate and temperature of the cooling medium to cool the material inside the cylinder to above 370°C. The control module also controls the continuous introduction of inert gas from the low-pressure nitrogen inlet to ensure that the cylinder always maintains a positive pressure inert atmosphere in conjunction with the low-pressure nitrogen outlet.

[0010] Preferably, the material cooling temperature is 370~430℃.

[0011] Preferably, a low-pressure inert gas is continuously introduced, wherein the low pressure is 0.1~0.5 kPa.

[0012] Preferably, a backflush port is set at regular intervals along the conveying pipeline. Each backflush port is connected to a high-pressure inert gas source through a branch pipe and a pulse solenoid valve. Pressure measuring points on the conveying pipeline monitor pressure changes in real time. If the pressure at a certain point continues to be higher than the set threshold, the pulse solenoid valves at that point and adjacent points are triggered to perform instantaneous backflush until the pressure value is normal.

[0013] Preferably, a backflush port is installed every 3 to 10 meters along the conveying pipeline.

[0014] Preferably, the silo adopts intermittent dense phase conveying. When the material level in the silo reaches the set height, the air inlet valve of the pneumatic conveying system opens to start material conveying.

[0015] Preferably, the automatic ash unloading control PLC, control module, and backflushing control are integrated into a single PLC control module.

[0016] A method for removing ash using the aforementioned ash removal and pneumatic conveying device for high-temperature pyrolysis dust collection includes: Initial state: Upper ash discharge valve closed, lower ash discharge valve closed, balance valve closed; water-cooled screw conveyor operating normally; Ash discharge cycle begins: Step 1: Open the balance valve and the upper ash discharge valve. At this time, the pressure of the upstream dust removal equipment and the middle vertical pipe is balanced. The high-temperature ash falls into the middle vertical pipe under the action of gravity for a preset time. Step 2: Close the upper ash discharge valve and the balancing valve. At this point, the middle vertical pipe becomes an independent pressure vessel. Step 3: Open the lower ash discharge valve, and the material inside the middle vertical pipe will fall into the water-cooled screw conveyor. Cooling and conveying: The material is cooled during the conveying process of the water-cooled screw conveyor, while being protected by nitrogen. The cooled material is then continuously fed into the silo. Pneumatic conveying: The silo adopts intermittent dense phase conveying. When the material level in the silo reaches the set height, the air inlet valve opens, and nitrogen gas forces the material into the conveying pipeline in the form of a slug flow. During pneumatic conveying, pressure measurement points on the pipeline monitor pressure changes in real time. If the pressure at a certain point continues to exceed the set threshold, the solenoid valves at that point and adjacent points are immediately triggered to perform instantaneous backflushing.

[0017] The advantages of this invention compared to the prior art are: (1) High safety and reliability: Through the design of "dual valve ash discharge + full-process inertial protection", the risk of high temperature ash coming into contact with air is fundamentally eliminated, preventing fire and explosion accidents. All key equipment is insulated, reducing thermal stress damage and extending equipment life; (2) Effectively prevents blockage: The innovative use of water-cooled spiral conveyor equipment for controllable cooling keeps the material temperature above the freezing point, thus preventing blockage caused by condensation and adhesion from the source. At the same time, the backflush anti-blockage port on the pneumatic conveying pipeline provides an active anti-blockage method, solving the problem of pipe blockage in long-distance conveying.

[0018] (3) Stable system operation: The setting of the air pressure balance pipe ensures smooth ash discharge of the dual valves, and the ash discharge process is not affected by the pressure changes of the upstream equipment. The water-cooled screw conveyor realizes the continuity and controllability of the cooling process, providing stable material conditions for the subsequent pneumatic conveying system.

[0019] (4) Energy recovery potential: After the cooling water in the jacket of the water-cooled screw conveyor is heated, it can be used as a low-temperature heat source for other process links, realizing partial waste heat recovery and improving the energy efficiency of the whole system.

[0020] (5) High degree of automation: The switching of dual valves, the introduction of inert gas, and the triggering of backflushing and anti-blocking can all be automatically controlled by the PLC system, which greatly reduces the intensity of manual operation and the risk of error. Attached Figure Description

[0021] Figure 1 : A schematic diagram of the overall structure and process flow of the device of the present invention; Figure 2 Schematic diagram of pneumatic conveying pipeline and backflush anti-clogging port layout.

[0022] In the diagram: Upstream dust removal equipment 1, automatic ash discharge system 2 including upper ash discharge valve 21, lower ash discharge valve 22, intermediate vertical pipe 23, pressure connecting pipe valve (also known as balancing valve) 24, pressure connecting pipe 25, ash discharge automatic control PLC 26, water-cooled screw conveyor equipment 3 including low-pressure nitrogen inlet 31, low-pressure nitrogen outlet 32, material inlet 33, material outlet 34, motor 35, silo 4, nitrogen buffer tank 5, pneumatic conveying fan 6, pneumatic conveying pipeline spray anti-clogging device 7 including pressure reducing valve 71, solenoid valve 72, spray opening 73, pressure measuring point 74, nitrogen spray control PLC 75, dust storage bin 8. Detailed Implementation

[0023] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] A dust removal and pneumatic conveying device for high-temperature pyrolysis dust collection includes an upstream dust removal device, an automatic dust removal system, a water-cooled screw conveyor, a silo 4, and a pneumatic conveying system connected sequentially along the material flow direction.

[0025] (1) Upstream dust removal equipment and automatic ash removal system: High-temperature ash (500~800℃) collected by upstream dust removal equipment (such as cyclone separators, dust collectors, etc.). Its body is made of heat-resistant steel and covered with an insulation layer to reduce heat loss.

[0026] The automatic ash discharge system is the core component ensuring the system's airtightness, employing a dual-valve automatic ash discharge sealing system. It consists of an upper ash discharge valve 21, a lower ash discharge valve 22, an intermediate vertical pipe 23 forming between them, a pressure connecting pipe valve 24, a pressure connecting pipe 25, and an automatic ash discharge control PLC 26. Both the upper ash discharge valve 21 and the lower ash discharge valve 22 are high-temperature resistant rigid sealing valves, such as high-temperature ball valves and high-temperature dome valves. Its working logic is as follows: During ash discharge, the lower ash discharge valve 22 is first closed, and the upper ash discharge valve 21 and the valve on the pressure balancing pipe are opened. Ash from the upstream dust collector 1 falls into the intermediate vertical pipe 23 under the action of gravity and pressure balance. Then, the upper ash discharge valve 21 and the balancing valve are closed, and the lower ash discharge valve 22 is opened again, allowing ash in the intermediate vertical pipe 23 to fall into the downstream equipment. Throughout this process, one valve remains closed, effectively cutting off the direct connection between the upstream dust collector 1 and the downstream low-pressure equipment, ensuring the system's airtightness and safety.

[0027] The pressure connecting pipe 25 connects the upper part of the upstream dust removal equipment 1 to the middle vertical pipe 23. Its function is to balance the pressure difference between the upstream dust removal equipment 1 and the middle vertical pipe 23 when the upper ash discharge valve 21 is opened to discharge ash, so that the material can fall smoothly by gravity and avoid the difficulty of material discharge or gas leakage caused by pressure difference.

[0028] (2) Water-cooled screw conveyor equipment: The water-cooled screw conveyor 3 is another core innovation of this invention. It combines conveying, cooling, and atmosphere control functions. It includes a low-pressure nitrogen inlet 31, a low-pressure nitrogen outlet 32, a material inlet 33, a material outlet 34, and a motor 35.

[0029] Conveying function: Through the rotation of the screw shaft, the high-temperature ash from the automatic ash discharge system is continuously and stably pushed to the hopper 4.

[0030] Cooling function: Its cylinder has a jacketed structure with an internal circulating cooling medium (such as softened water). By precisely calculating the length, speed, flow rate, and temperature of the cooling medium of the screw conveyor, the material inlet temperature (500-800℃) can be accurately cooled to above 370℃ (preferably 370-450℃). This temperature range is higher than the freezing point of ash, effectively preventing viscosity increase and equipment adhesion and blockage caused by condensation.

[0031] Inert gas protection function: The cylinder is equipped with an inert gas injection port and an outlet, continuously supplying low-pressure (0.1~0.5 kPa) inert gas (such as nitrogen). This ensures that the screw conveyor always maintains a slightly positive pressure inert atmosphere, completely isolating it from air and preventing high-temperature ash from oxidizing and igniting during the conveying process.

[0032] (3) Silos and pneumatic conveying system: The hopper 4 is used to temporarily store cooled materials and provide a stable material source for pneumatic conveying.

[0033] The pneumatic conveying system uses inert gas (nitrogen) as the conveying gas source to transport materials from silo 4 through pipelines to a distant vertical pipeline. Using inert gas as the power source ensures that the entire process from ash discharge to the conveying endpoint is carried out in an oxygen-free environment, resulting in extremely high safety.

[0034] Backflush nozzles are crucial for ensuring the reliability of long-distance transportation. A backflush nozzle is installed at regular intervals (e.g., 3-10 meters) along the transportation pipeline. Each nozzle is connected to a high-pressure inert gas source via a branch pipe and a pulse solenoid valve. When the transportation resistance increases or a blockage occurs at a point in the pipeline due to changes in material properties or unexpected circumstances, a pressure sensor sends a signal, triggering the pulse valve at the corresponding location to open instantaneously. A high-pressure airflow then impacts the blockage point in the opposite or lateral direction, quickly and effectively dispersing the blockage and restoring the pipeline's flow.

[0035] Example 1. Equipment selection and parameters: Upstream dust removal equipment 1: with a volume of 10m³, made of 310S heat-resistant stainless steel, and covered with a 150mm thick aluminum silicate fiber insulation layer on the outside.

[0036] Automatic ash discharge system 2: Both the upper ash discharge valve 21 and the lower ash discharge valve 22 are DN200 high-temperature wear-resistant ball valves with hard alloy seats that can withstand temperatures up to 600℃ for extended periods. The intermediate vertical pipe 23 has a volume of approximately 0.1m³. The pressure connecting pipe 25 is a DN50 stainless steel pipe with a pressure connecting valve 24 installed on it, which is interlocked with the upper ash discharge valve 21 and the lower ash discharge valve 22 by the control system.

[0037] Water-cooled screw conveyor 3: Conveying capacity is 5 t / h, length is 8 meters. The screw shaft and blades are made of 304 stainless steel. The jacketed cylinder is cooled by 80℃ softened water, and the cooling water flow rate is adjusted via PID control to ensure the outlet material temperature remains stable at 400±30℃. The inert gas injection pressure is set to 0.3 kPa, and the nitrogen purity is >99.5%.

[0038] Pneumatic delivery system: The gas source is a pressure swing adsorption (PSA) nitrogen generator, providing atmospheric pressure nitrogen. The delivery pipeline is a seamless steel pipe of DN125, with a delivery distance of approximately 150 meters. There are 15 injection nozzles (73) installed every 10 meters. The backflush gas source is a group of compressed nitrogen cylinders at 0.8 MPa, and the injection solenoid valve (72) is a pulse solenoid valve with a response time of <100 ms.

[0039] 2. Workflow: Initial state: Upper ash discharge valve 21 is closed, lower ash discharge valve 22 is closed, and pressure connecting pipe valve 24 is closed. The water-cooled screw conveyor 3 and the nitrogen generation system are operating normally.

[0040] Ash removal cycle begins: The control system issues a command.

[0041] Step 1: Open the pressure connection valve 24 and the upper ash discharge valve 21. At this time, the pressure of the upstream dust removal equipment 1 and the intermediate vertical pipe 23 is balanced, and the high-temperature ash falls into the intermediate vertical pipe 23 under the action of gravity for about 30 seconds.

[0042] Step 2: Close the upper ash discharge valve 21 and the pressure connecting pipe valve 24. At this time, the middle vertical pipe 23 becomes an independent pressure vessel.

[0043] Step 3: Open the lower ash discharge valve 22. The material in the middle vertical pipe 23 falls into the material inlet 33 of the water-cooled screw conveyor 3.

[0044] Cooling and conveying: The high-temperature ash undergoes a conveying process of about 2 minutes in the water-cooled screw conveyor 3, during which the temperature drops from about 600℃ to 400℃, while being under nitrogen protection. The cooled material is then continuously fed into the silo 4.

[0045] Pneumatic conveying: Silo 4 uses intermittent dense-phase conveying. When the material level in silo 4 reaches the set height, the pneumatic conveying fan 6 is started, and the material falls by gravity to the inlet of the conveying fan. The material is then conveyed along with nitrogen into the pressurized conveying pipeline. The conveying process lasts for about 5 minutes.

[0046] Anti-clogging monitoring: During pneumatic conveying, pressure measurement points 74 on the pipeline monitor pressure changes in real time. If the pressure at a certain point continues to exceed the set threshold, the control system will immediately trigger the solenoid valves 72 at that point and adjacent points to perform instantaneous backflushing. Usually, 1-2 backflushings are sufficient to eliminate the risk of blockage.

[0047] 3. Control strategy: The entire system is integrated and controlled by a PLC. The core control logic includes: The PLC26 automatic ash discharge control system features a strict interlocking logic between the dual-valve ash discharge and the air pressure balancing valve, ensuring that at least one valve is always in a closed and sealed state.

[0048] The opening of the cooling water regulating valve is automatically adjusted based on the feedback from the temperature sensor at the outlet of the water-cooled screw conveyor.

[0049] The water-cooled screw conveyor has a slightly positive internal pressure that is interlocked with the inert gas flow rate.

[0050] Nitrogen injection control PLC75: Intelligent triggering for pressure analysis and backflushing prevention in pneumatic conveying pipelines.

[0051] Through the above-mentioned device and method, the present invention has successfully solved a series of technical problems in the treatment of high-temperature pyrolysis ash, such as safety, cooling, oxidation prevention and blockage prevention, and provides a reliable guarantee for the continuous, stable and safe operation of related industrial processes.

[0052] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A dust removal and pneumatic conveying device for high-temperature pyrolysis dust collection, characterized in that... It includes upstream dust removal equipment, automatic ash removal system, water-cooled screw conveyor, silo and pneumatic conveying system connected in sequence along the material flow direction; High-temperature ash collected by upstream dust removal equipment; the automatic ash discharge system is a dual-valve automatic ash discharge sealing system, with one valve always closed during the ash discharge process to cut off the direct connection between the upstream dust removal equipment and the water-cooled screw conveyor. Water-cooled screw conveyors provide an inert atmosphere to cool the incoming dust and transport it to the silo. The silo is used to temporarily store cooled materials and provide a stable material source for the pneumatic conveying system; The pneumatic conveying system uses inert gas as a power source to force the material in the silo into the conveying pipeline in the form of a slug flow.

2. The apparatus according to claim 1, characterized in that: The automatic ash discharge system includes an upper ash discharge valve, a lower ash discharge valve, an intermediate vertical pipe formed between the two, a balancing valve, a pressure connecting pipe, and an automatic ash discharge control PLC; the pressure connecting pipe connects the intermediate vertical pipe to the upstream dust removal equipment; the balancing valve is installed on the pressure connecting pipe; During ash discharge, the automatic ash discharge control PLC first closes the lower ash discharge valve and opens the upper ash discharge valve and the balancing valve. The ash in the upstream dust removal equipment falls into the middle vertical pipe under the action of gravity and pressure balance. Then, the upper ash discharge valve and the balancing valve are closed, and the lower ash discharge valve is opened again. The ash in the middle vertical pipe falls into the downstream equipment.

3. The apparatus according to claim 2, characterized in that: The water-cooled spiral conveyor includes a cylinder and a control module; The cylinder is equipped with a low-pressure nitrogen inlet, a low-pressure nitrogen outlet, a material inlet, and a material outlet; a screw conveyor is installed inside the cylinder. The cylinder has a jacketed structure with a circulating cooling medium inside. The control module controls the speed of the screw conveyor, the flow rate and temperature of the cooling medium to cool the material inside the cylinder to above 370°C. The control module also controls the continuous introduction of inert gas from the low-pressure nitrogen inlet to ensure that the cylinder always maintains a positive pressure inert atmosphere in conjunction with the low-pressure nitrogen outlet.

4. The apparatus according to claim 3, characterized in that: Material cooling temperature: 370~430℃.

5. The apparatus according to claim 3, characterized in that: A low-pressure inert gas is continuously introduced, wherein the low pressure is 0.1~0.5 kPa.

6. The apparatus according to claim 3, characterized in that: A backflush port is installed at regular intervals along the delivery pipeline. Each backflush port is connected to a high-pressure inert gas source through a branch pipe and a pulse solenoid valve. Pressure measurement points on the delivery pipeline monitor pressure changes in real time. If the pressure at a certain point continues to be higher than the set threshold, the pulse solenoid valves at that point and adjacent points are triggered to perform instantaneous backflush until the pressure value is normal.

7. The apparatus according to claim 6, characterized in that: A backflush port should be installed every 3 to 10 meters along the delivery pipeline.

8. The apparatus according to claim 1, characterized in that: The silo uses intermittent dense phase conveying. When the material level in the silo reaches the set height, the air inlet valve of the pneumatic conveying system opens to start material conveying.

9. The apparatus according to claim 6, characterized in that: The automatic ash unloading control PLC, control module, and backflushing control are integrated into a single PLC control module.

10. A method for removing ash using the ash removal and pneumatic conveying device for high-temperature pyrolysis dust collection as described in claim 6, characterized in that... include: Initial state: Upper ash discharge valve closed, lower ash discharge valve closed, balance valve closed; water-cooled screw conveyor operating normally; Ash discharge cycle begins: Step 1: Open the balance valve and the upper ash discharge valve. At this time, the pressure of the upstream dust removal equipment and the middle vertical pipe is balanced. The high-temperature ash falls into the middle vertical pipe under the action of gravity for a preset time. Step 2: Close the upper ash discharge valve and the balancing valve. At this point, the middle vertical pipe becomes an independent pressure vessel. Step 3: Open the lower ash discharge valve, and the material inside the middle vertical pipe will fall into the water-cooled screw conveyor. Cooling and conveying: The material is cooled during the conveying process of the water-cooled screw conveyor, while being protected by nitrogen. The cooled material is then continuously fed into the silo. Pneumatic conveying: The silo adopts intermittent dense phase conveying. When the material level in the silo reaches the set height, the air inlet valve opens, and nitrogen gas forces the material into the conveying pipeline in the form of a slug flow. During pneumatic conveying, pressure measurement points on the pipeline monitor pressure changes in real time. If the pressure at a certain point continues to exceed the set threshold, the solenoid valves at that point and adjacent points are immediately triggered to perform instantaneous backflushing.

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