Kiln tail humidification duct with settling chamber and kiln tail exhaust gas treatment method

Abstract

The present application relates to cement production processing technical field, disclose a kind of kiln tail humidification pipeline with settling chamber and kiln tail waste gas processing method.The pipeline includes by humidification tower frame support vertical setting humidification air pipe, top cooling water lance is equipped, towards the kiln tail gas in humidification air pipe and sprays atomized cooling water;Air pipe bottom is equipped with settling chamber, outlet is connected with high-temperature fan;Settling chamber inside is not equipped with spoiler, limit support is set around shell, and polytetrafluoroethylene plate is set between limit support bottom and structure welding embedded plate;Settling chamber below is provided with back ash screw conveyor unit and is provided with can kiln dust discharge and back ash to production line;Humidification air pipe is equipped with SP boiler air inlet pipe interface and SP boiler air return pipe interface.Both realize the function of kiln tail high-temperature gas cooling, protect dust collector filter bag, avoid the problem that kiln tail air pipe and high-temperature fan distance is far from easily ash deposition.Meanwhile, the operation and maintenance safety hazard of large high-altitude equipment is eliminated.

Description

Technical Field

[0001] This invention relates to the field of cement production and processing technology, specifically to a kiln tail humidification pipe with a settling chamber and a method for treating kiln tail exhaust gas. Background Technology

[0002] In cement clinker production lines, baghouse dust collectors are commonly used as the main dust collectors at the kiln tail. The filter bags in these collectors have strict temperature requirements, typically needing to be controlled at ≤160℃. Exceeding this temperature will significantly shorten the lifespan of the filter bags. When the kiln tail power boiler or raw material mill is not operating, the temperature of the exhaust gas directly entering the kiln tail dust collector can reach as high as 200℃ to 310℃, therefore, it is essential to cool the high-temperature exhaust gas.

[0003] In traditional processes, a separate humidification tower is typically installed between the kiln tail and the high-temperature fan to protect the filter bags of the subsequent baghouse dust collector by spraying water for cooling. However, this approach has the following shortcomings: 1. High energy consumption: Taking a 5000t / d production line as an example, the humidification tower itself has a resistance of about 300Pa, which leads to an increase in the power consumption of the high-temperature fan by about 0.3kWh / ton of clinker.

[0004] 2. Low utilization rate: The kiln tail boiler can operate at a rate of over 95%, while the raw material mill operates at a rate of 70% to 85%, resulting in a low actual operating rate of the humidification tower and low equipment utilization.

[0005] 3. Significant safety hazards: Humidification towers are high-altitude structures. For production lines that have been in operation for a long time, their structure poses safety hazards, and daily operation, maintenance and repair are extremely inconvenient.

[0006] 4. Dust accumulation risk: If the humidification tower is directly eliminated, the long-distance connecting duct between the kiln tail and the high-temperature fan is prone to dust accumulation due to angle limitations (usually less than 35°), which will affect the continuous and stable operation of the production line. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of low operating rate of humidification towers, inconvenient high-altitude operation and maintenance, significant safety hazards, and easy dust accumulation due to the large distance between the kiln tail duct and the high-temperature fan in existing technologies. This invention provides a kiln tail humidification duct with a settling chamber and a method for treating kiln tail exhaust gas. This achieves both the function of cooling the high-temperature gas at the kiln tail and protecting the dust collector filter bags, while avoiding the problem of dust accumulation due to the large distance between the kiln tail duct and the high-temperature fan. Simultaneously, it eliminates the safety hazards associated with the operation and maintenance of large high-altitude equipment.

[0008] To achieve the above objectives, the present invention provides a kiln tail humidification pipe with a settling chamber. This kiln tail humidification pipe includes a humidification air duct supported vertically by a humidification tower frame. A cooling water spray gun is located at the top of the humidification air duct, configured to spray atomized cooling water towards the kiln tail gas inside the humidification air duct. A settling chamber is located at the bottom of the humidification air duct, and the outlet of the settling chamber is connected to a high-temperature fan via an air duct. No baffle is installed inside the settling chamber, and limit supports are installed around the shell. A polytetrafluoroethylene (PTFE) plate is installed between the bottom of the limit supports and the structural welded embedded plate. A return ash screw conveyor unit is installed below the settling chamber and configured to discharge kiln ash and return it to the production line by controlling the forward and reverse rotation of the motor. An SP boiler inlet pipe interface is located above the cooling water spray gun on the humidification air duct, and an SP boiler return air pipe interface is located above the settling chamber on the humidification air duct.

[0009] Preferably, the cooling water spray gun is a dual-fluid spray gun.

[0010] Preferably, the diameter of the middle and lower sections of the humidification duct is greater than or equal to 5600 mm.

[0011] Preferably, the ash return screw conveyor unit consists of two reversible screw conveyors.

[0012] Preferably, two reversible screw conveyors are arranged in staggered layers to collect and transport the ash discharged from the settling chamber to the downstream kiln ash system.

[0013] A second aspect of the present invention provides a method for treating kiln tail exhaust gas using the aforementioned kiln tail humidification pipe with a settling chamber. The method includes increasing the diameter of the middle and lower sections of the humidification pipe, reducing the wind speed inside the humidification pipe, and extending the residence time of the gas sprayed by the cooling water spray gun.

[0014] Preferably, the air velocity inside the humidification duct is reduced to below 8 m / s.

[0015] Preferably, the residence time of the gas below the water spray is controlled to be more than 4 seconds.

[0016] Preferably, the method further includes controlling the cross-sectional wind speed at the outlet of the settling chamber along the airflow direction to below 5 m / s.

[0017] Preferably, the method further includes setting the return ash screw conveyor unit to redundant operation.

[0018] The above technical solution modifies the existing clinker production process in cement plants, eliminating the humidification tower and utilizing water spray cooling and dust collection / treatment in the kiln tail exhaust duct. Removing the humidification tower reduces system resistance, while adding water spray cooling to the kiln tail exhaust duct ensures the lifespan of the dust collector filter bags. The settling chamber between the exhaust duct and the high-temperature fan effectively reduces dust accumulation in the duct. Furthermore, the removal of the humidification tower eliminates safety hazards associated with the operation and maintenance of large, high-altitude equipment, significantly improving safety. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the kiln tail humidification pipe with a settling chamber provided according to the present invention. Figure 2 This is a side view of a kiln tail humidification pipe with a settling chamber provided according to the present invention; Figure 3 This is a top view of a kiln tail humidification pipe with a settling chamber provided according to the present invention; Figure 4 This is a schematic diagram of the settling chamber in the kiln tail humidification pipe with a settling chamber provided by the present invention.

[0020] Explanation of reference numerals in the attached figures 1-Humidification air duct, 2-Cooling water spray gun, 3-Settling chamber, 4-High temperature fan, 5-Ash return screw conveyor unit, 6-SP boiler inlet air duct interface, 7-SP boiler return air duct interface. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] In this invention, unless otherwise stated, directional terms such as "upper," "middle," "lower," "top," "bottom," "inner," and "outer" in the terminology only represent the orientation of the term in its conventional use or are common terms understood by those skilled in the art, and should not be regarded as limitations on the terminology.

[0023] See Figures 1 to 4This invention provides a kiln tail humidification pipe with a settling chamber. The kiln tail humidification pipe includes a humidification air duct 1 supported by a humidification tower frame. A cooling water spray gun 2 is provided at the top of the humidification air duct 1, which is configured to spray atomized cooling water toward the kiln tail gas inside the humidification air duct 1. A settling chamber 3 is provided at the bottom of the humidification air duct 1, and the outlet of the settling chamber 3 is connected to a high-temperature fan 4 through an air duct. The settling chamber 3 does not have a baffle plate inside, and a limit support is provided around the shell. A polytetrafluoroethylene plate is provided between the bottom of the limit support and the structural welded embedded plate. A return ash screw conveyor unit 5 is provided below the settling chamber 3 and is configured to realize the discharge of kiln ash and the return of ash to the production line by controlling the forward and reverse rotation of the motor. An SP boiler air inlet duct interface 6 is provided on the humidification air duct 1 above the cooling water spray gun 2, and an SP boiler air return duct interface 7 is provided on the humidification air duct 1 above the settling chamber 3.

[0024] Specifically, in this embodiment, the cooling water spray gun 2 is preferably a dual-fluid spray gun, and the diameter of the middle and lower sections of the humidifying air duct 1 is greater than or equal to 5600 mm.

[0025] In this embodiment, preferably, the ash return screw conveyor unit 5 consists of two reversible screw conveyors. More preferably, the two reversible screw conveyors are arranged in staggered layers to collect and transport the ash discharged from the settling chamber 3 to the downstream kiln ash system.

[0026] In this way, by installing a cooling water spray gun 2 at the top of the humidification duct 1 and directly connecting it to the settling chamber 3 and high-temperature fan 4 at the bottom, the traditional high-resistance humidification tower is replaced. The settling chamber 3 does not have baffles inside, avoiding additional local resistance losses, thus reducing the total system resistance by approximately 300 Pa. The power consumption of the high-temperature fan 4 is consequently reduced, achieving energy saving and consumption reduction. The cooling water spray gun 2 is located at the top of the humidification duct 1, and the sprayed atomized cooling water fully contacts the high-temperature kiln tail exhaust gas within the vertical pipe. Combined with the expanded diameter design in the lower section of the humidification duct 1, the air velocity within the pipe is reduced, and the gas residence time is extended, ensuring that the exhaust gas temperature is reliably reduced to ≤160℃ before entering the subsequent dust collector, effectively protecting the filter bags from high-temperature damage. Simultaneously, the settling chamber 3 is located between the bottom of the humidification duct 1 and the high-temperature fan 4, serving as a deflection and buffer space for airflow. Dust in the exhaust gas, especially the sludge-like material formed after water spraying, settles in the settling chamber 3 due to gravity, preventing dust accumulation in the horizontal duct and ensuring continuous and stable operation of the production line. Furthermore, limiting supports are installed around the shell of the settling chamber 3, with a polytetrafluoroethylene (PTFE) plate between the bottom of the supports and the welded structural plate. This structure reduces the coefficient of friction between the steel plates, guiding the settling chamber 3 to slide orderly along the airflow direction under heat, effectively absorbing lateral displacement caused by thermal expansion and contraction. Simultaneously, the limiting plates prevent excessive offset and avoid localized cracking. Moreover, the ash return screw conveyor unit 5 installed below the settling chamber 3, by controlling the forward and reverse rotation of the motor, can either discharge the wet sludge-like material generated during water spraying and cooling, or return dry ash to the production line, achieving flexible switching between material recovery and discharge. Two reversible screw conveyors are arranged in a staggered manner, shortening the length of a single unit (avoiding the 12m limit), reducing wear on the screw blades from wet materials and the risk of long shaft breakage. They also provide redundancy, ensuring uninterrupted system operation even if one unit fails. Furthermore, the SP boiler inlet pipe interface 6 located above the cooling water spray gun 2 on the humidification duct 1, and the SP boiler return air interface 7 located above the settling chamber 3, allow for seamless integration with the existing SP boiler waste heat power generation system without affecting waste heat recovery efficiency under normal operating conditions.

[0027] On the other hand, the present invention also provides a method for treating kiln tail exhaust gas using the aforementioned kiln tail humidification pipe with a settling chamber. This method includes increasing the diameter of the middle and lower sections of the humidification duct 1, reducing the air velocity within the humidification duct 1, and extending the residence time of the gas sprayed by the cooling water spray gun 2. This increased diameter leads to a larger cross-sectional area of ​​the pipe, resulting in a significant decrease in air velocity within the pipe under the same operating conditions (e.g., approximately 720,000 m³ / h for a 5000 t / d production line). The reduced air velocity extends the contact time between the atomized cooling water and the high-temperature exhaust gas within the humidification duct 1, allowing for more thorough heat exchange between the water and gas. This reliably reduces the exhaust gas temperature to ≤160℃, which is permissible by the bag filter, effectively protecting the filter bag's lifespan. Simultaneously, the lower air velocity reduces dust erosion and wear on the pipe wall, and also lowers the risk of secondary droplet entrainment caused by high-speed airflow, which is beneficial to the separation efficiency of the subsequent settling chamber 3.

[0028] In this embodiment, the kiln tail exhaust gas treatment method further includes reducing the air velocity in the humidifying duct 1 to below 8 m / s. This air velocity range can prevent dust from being re-entrained due to excessive flow velocity, and at the same time prevent atomized water droplets from being carried away by the airflow before they can vaporize, ensuring the cooling effect. Furthermore, the lower air velocity in the duct also creates favorable conditions for the uniform distribution of airflow in the subsequent settling chamber 3, reducing the interference of turbulence on the settling process.

[0029] In this embodiment, the kiln tail exhaust gas treatment method further includes controlling the gas residence time below the water spray to at least 4 seconds. This ensures that the cooling water has sufficient time to completely vaporize and absorb heat from the exhaust gas. Experiments and engineering practice show that a residence time of 4 seconds allows the atomized water and high-temperature gas to reach thermal equilibrium, preventing unvaporized water droplets from entering downstream equipment and causing bag clogging or corrosion. Simultaneously, it causes dust to agglomerate and increase in weight due to water absorption, making it easier to separate within the settling chamber 3.

[0030] In this embodiment, the kiln tail gas treatment method further includes controlling the cross-sectional wind speed at the outlet of settling chamber 3 along the airflow direction to below 5 m / s, which significantly improves the dust separation efficiency of settling chamber 3. According to the theory of gravity settling, the lower the cross-sectional wind speed, the slower the horizontal movement speed of particles in the settling chamber, and the longer the settling time, which is conducive to the smaller dust particles and mud-like materials formed by water spray falling to the bottom by gravity. This measure achieves efficient natural settling by relying on low wind speed without adding baffles (there are no baffles inside settling chamber 3), avoiding additional resistance, and at the same time preventing fine dust from being carried by the airflow into the high-temperature fan 4 and the subsequent bag dust collector, reducing the burden on the dust collector.

[0031] In this embodiment, the kiln tail exhaust gas treatment method also includes setting the ash return screw conveyor unit 5 to redundant operation. Redundant operation means that the two reversible screw conveyors can serve as backups for each other or work in coordination. Specifically, when water spraying and cooling produces wet mud-like materials, the two devices can operate simultaneously to share the conveying load, preventing a single ultra-long screw (over 12m) from being overloaded or having its blades fall off due to wet material adhering to the blades. If one of them malfunctions (such as a burnt-out motor or a broken screw shaft), the other can still maintain basic ash discharge functions, preventing ash accumulation and blockage in the settling chamber 3, and ensuring that the production line is not forced to stop due to ash discharge equipment failure. At the same time, through the forward and reverse rotation control of the motor, the redundant setting also allows for flexible switching between external discharge and ash return modes, enabling stable operation under both dry and wet conditions.

[0032] In summary, this invention, through the aforementioned technical solution, modifies the existing clinker production process in cement plants, eliminating the humidification tower and utilizing the kiln tail exhaust gas duct for water spray cooling and dust collection and treatment. The removal of the humidification tower reduces system resistance, while the addition of water spray cooling to the kiln tail exhaust gas duct ensures the service life of the filter bags in the kiln tail dust collector. The settling chamber between the exhaust gas duct and the high-temperature fan effectively reduces dust accumulation in the duct. Furthermore, the removal of the humidification tower eliminates the safety hazards associated with the operation and maintenance of large, high-altitude equipment, significantly improving the safety factor.

[0033] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A kiln tail moistening duct having a settling chamber, characterized in that, The kiln tail humidification pipe with a settling chamber includes a humidification air duct (1) erected and supported by a humidification tower frame. A cooling water spray gun (2) is installed at the top of the humidification air duct (1), and the cooling water spray gun (2) is configured to spray atomized cooling water towards the kiln tail gas inside the humidification air duct (1). A settling chamber (3) is installed at the bottom of the humidification air duct (1), and the outlet of the settling chamber (3) is connected to a high-temperature fan (4) via an air duct. The settling chamber (3) does not have a baffle plate inside, and the shell... Limiting supports are provided around the body, and polytetrafluoroethylene plates are provided between the bottom of the limiting supports and the structural welding embedded plate; a return ash screw conveyor unit (5) is provided below the settling chamber (3) and is configured to enable the kiln ash to be discharged and returned to the production line by controlling the forward and reverse rotation of the motor; an SP boiler air inlet pipe interface (6) is provided on the humidifying air pipe (1) above the cooling water spray gun (2), and an SP boiler return air pipe interface (7) is provided on the humidifying air pipe (1) above the settling chamber (3).

2. The kiln hood moistening duct with a settling chamber according to claim 1, characterized in that, The cooling water spray gun (2) is a dual-fluid spray gun.

3. The kiln hood moistening duct with a settling chamber according to claim 1, characterized in that, The diameter of the middle and lower sections of the humidification duct (1) is greater than or equal to 5600 mm.

4. The kiln tail humidification pipe with a settling chamber according to claim 1, characterized in that, The ash return screw conveyor unit (5) consists of two reversible screw conveyors.

5. The kiln hood moistening duct with a settling chamber according to claim 4, characterized in that, The two reversible screw conveyors are arranged in staggered layers to collect and transport the ash discharged from the settling chamber (3) to the downstream kiln ash system.

6. A method for treating kiln exhaust using the kiln hood moistening duct with a settling chamber according to any one of claims 1-5, characterized in that, The method includes increasing the diameter of the middle and lower sections of the humidifying air duct (1), reducing the wind speed inside the humidifying air duct (1), and extending the residence time of the gas sprayed by the cooling water spray gun (2).

7. The kiln exhaust gas treatment method according to claim 6, characterized in that, Reduce the air velocity in the humidification duct (1) to below 8 m / s.

8. The kiln exhaust gas treatment method according to claim 7, characterized in that, The residence time of the gas below the water spray should be controlled to be more than 4 seconds.

9. The method for treating kiln tail exhaust gas according to claim 6, characterized in that, The method also includes controlling the cross-sectional wind speed at the outlet of the settling chamber (3) along the airflow direction to below 5 m / s.

10. The kiln exhaust gas treatment method according to claim 6, characterized by, The method also includes setting the return ash screw conveyor unit (5) to redundant operation.

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