Steam impact type water bath dust removal and desulfurization system for air-quenched slag and treatment method of steam impact type water bath dust removal and desulfurization system

Abstract

The invention belongs to the technical field of flue gas purification of nonferrous smelting high-temperature slag, and particularly relates to a steam impact type water bath dust removal and desulfurization system and method for air-quenched slag. The system comprises at least two dust remover units which are arranged in parallel, a dosing regulation and control unit and an exhaust unit. Each dust remover unit is provided with a vertical cylinder, the bottom of the vertical cylinder is a water storage area, the impact air channel is designed to be in an inverted L shape or a gooseneck shape, the tail end of an impact pipe is submerged below the liquid level of alkaline washing liquid in the water storage area, and an induced draft fan is arranged at the top of the cylinder. And the dosing regulation and control unit is used for online monitoring and automatically regulating the alkalinity of the washing liquid. According to the invention, the operation continuity is ensured through the parallel modular design, gas-liquid full contact is realized by utilizing high-speed submerged impact, dust and sulfur dioxide are synchronously and efficiently removed, and the device has the functions of automatic control and valuable metal recovery, and has the advantages of high purification efficiency, stable operation and good economical efficiency.

Description

Technical Field

[0001] This invention relates to the field of flue gas purification technology for high-temperature slag in non-ferrous smelting, specifically to a steam impact water bath dust removal and desulfurization system for air-quenched slag and its treatment method. Background Technology

[0002] In the metallurgical and non-ferrous smelting industries, the treatment of high-temperature slag is a critical process. Among these processes, the air-quenching slag process uses high-pressure air to disperse and granulate molten slag, simultaneously spraying water for rapid cooling to form glassy slag particles that are easy to process later. This process is widely used due to its high cooling efficiency and good slag particle quality. However, while this process provides highly efficient cooling, it also creates a thorny environmental problem: at the moment the molten slag comes into contact with the cooling water, a large amount of high-temperature (usually above 100°C) and high-humidity saturated steam is released. This steam not only carries fine slag particles (typically containing valuable metals such as copper, lead, and zinc) broken by impact and temperature differences, but also contains trace amounts of acidic gases such as sulfur dioxide (SO2) generated by the slag composition. The direct emission of this steam not only leads to the loss of valuable metal dust and environmental pollution, but also causes corrosion to plant equipment.

[0003] Currently, various technologies have been attempted to treat this type of steam. For example, while general-purpose wet scrubbing towers or spray systems can achieve certain cooling and dust removal effects, they are often large, energy-intensive, and have limited adaptability and processing efficiency for instantaneous large-flow steam. Other technologies employ impact water bath dust collectors (such as patent CN206334465U) or structural modifications thereof (such as patent CN2917760Y), but these are mostly designed for ordinary flue gas. They suffer from insufficient structural specificity and operational stability when dealing with the unique characteristics of air-quenched slag steam, such as high dust content, intermittent impact loads, and the need for simultaneous high-efficiency desulfurization. Furthermore, some solutions focused on steam condensation and recovery (such as patent CN205635660U) are complex, require high investment, and do not focus on the synergistic deep purification of dust and sulfur dioxide. Overall, existing technologies struggle to simultaneously ensure efficient and stable dust removal and desulfurization while maintaining system compactness, operational economy, and production continuity.

[0004] Therefore, developing a dust removal and desulfurization system that is specifically designed for the characteristics of air-quenched slag processes, has strong adaptability, high purification efficiency, and is also economically viable is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a steam impact water bath dust removal and desulfurization system for air-quenched slag, used to treat high-temperature dust- and sulfur-containing steam generated in the air-quenched slag process. The system is characterized by comprising at least two parallel impact water bath dust collector units. Each dust collector unit includes: a vertical cylindrical body with a water storage area at its bottom for storing alkaline washing liquid; an impact air duct having an inlet end connected to a steam source and an impact pipe, the end of which is submerged below the liquid surface in the water storage area; an induced draft fan located at the top of the cylindrical body; a dosing control unit connected to the water storage areas of the at least two dust collector units for controlling the alkalinity of the alkaline washing liquid in the water storage areas; and an exhaust unit for centrally discharging the gas purified by the dust collector units.

[0006] Furthermore, the impact duct is an inverted L-shaped or gooseneck-shaped duct.

[0007] Furthermore, the dosing control unit includes an online pH meter for monitoring the pH value of the alkaline washing solution, and a metering pump that is linked to the online pH meter to automatically replenish the alkaline agent.

[0008] Furthermore, the dosing control unit is used to maintain the pH value of the alkaline washing solution within the range of 9-11.

[0009] Furthermore, the bottom of the cylinder is provided with a conical hopper and a slag removal valve communicating with the bottom of the conical hopper.

[0010] Furthermore, the induced draft fan is used to generate a steam flow rate of 15-20 m / s within the impact duct.

[0011] The present invention also provides a method for dust removal and desulfurization using the above-mentioned steam impact water bath dust removal and desulfurization system for air-quenched slag, the method comprising the following steps:

[0012] Under the action of the induced draft fan, the high-temperature dust- and sulfur-containing steam generated by the air quenching slag process is introduced into the dust collector unit operating in parallel through the at least two impact ducts; the steam is then flushed into the alkaline washing liquid below the liquid surface in the water storage area through the end of the impact ducts to capture the dust in the steam and neutralize it with sulfur dioxide; the alkalinity of the alkaline washing liquid is controlled by the dosing control unit; and the purified gas is discharged through the exhaust unit.

[0013] Furthermore, the step of regulating the alkalinity of the alkaline detergent solution specifically involves: monitoring the pH value of the alkaline detergent solution online, and automatically replenishing alkaline agents based on the monitoring results to maintain the pH value within the range of 9-11.

[0014] Furthermore, the dust removal and desulfurization method further includes: when one dust collector unit is being cleaned or maintained, at least one other dust collector unit remains in operation.

[0015] Furthermore, the dust removal and desulfurization method also includes: periodically discharging slurry enriched with slag particles through a slag removal valve at the bottom of the cylinder to recover the metal therein.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) Continuous and stable operation: At least two parallel dust collector units are used to support rotation operation and maintenance, ensuring that the system can continuously handle the steam generated intermittently in the air quenching slag process, ensuring the continuity of production and overcoming the disadvantage of having to shut down the entire line when maintaining a single piece of equipment.

[0018] (2) High purification efficiency and simultaneous operation: Through the unique inverted L-shaped / gooseneck-shaped impact air duct and liquid impact design, efficient inertial dust removal and gas-liquid mass transfer are achieved simultaneously in a single-stage device, which can simultaneously and deeply remove dust and sulfur dioxide from steam, resulting in significant purification effect.

[0019] (3) High automation and economy: The integrated dosing control unit can monitor and automatically maintain the optimal pH value (9-11) of the washing liquid online, accurately controlling the consumption of chemicals while ensuring desulfurization efficiency, thus reducing operating costs. The system has a compact structure, low resistance, and low energy consumption.

[0020] (4) Good resource recycling benefits: The metal-containing (such as copper) slag particles that are efficiently captured are enriched at the bottom of the system, which is convenient for regular recycling, turning waste into treasure, and creating direct economic value while controlling pollution.

[0021] (5) Simple structure and easy maintenance: The core unit has a simple and reliable structure, and the parallel design makes maintenance convenient. The overall system is easier to operate and maintain than a complex large washing tower. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the steam impact water bath dust removal and desulfurization treatment method for air-quenched slag according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] This invention provides a steam impact water bath dust removal and desulfurization system for air-quenched slag. This system is specifically designed to treat high-temperature, high-humidity steam containing metal dust and trace amounts of sulfur dioxide generated during the air-quenching slag process in the metallurgical and non-ferrous smelting industries. Through an integrated and modular design, this system aims to achieve efficient, continuous, and stable purification operations.

[0025] Example 1

[0026] In this embodiment, the system employs a dual-unit parallel configuration to meet the steam treatment requirements of a medium-sized air-quenched slag production line. The core of the system comprises two identical impact-type water bath dust collector units, designated Unit A and Unit B, respectively. The core of each dust collector unit is a vertical cylindrical shell welded from corrosion-resistant 304 stainless steel plates, with a diameter of 1.8 meters and a total height of 5.0 meters. The lower part of the cylinder is designed as a water storage area to hold the alkaline washing liquid, maintaining a liquid level of approximately 1.5 meters during normal operation. To facilitate the collection of settled solid particles, the bottom of the cylinder is machined into a conical hopper with a 60-degree cone angle, and a DN150 pneumatic slag discharge ball valve is connected at the lowest point of the hopper as a slag removal valve.

[0027] The air intake section of each unit is a crucial impact duct. This duct is designed in a gooseneck shape and is also made of 304 stainless steel. Its horizontal intake end has a diameter of DN450 and is connected via a flange to the steam collection hood pipe from the top of the air-quenched slag chamber. Near the top of the dust collector unit, the duct bends upward and turns 90 degrees, forming a vertically downward impact section with a diameter of DN350. The end of this impact section extends vertically, ensuring that its inlet is submerged approximately 200 mm below the liquid surface at normal operating liquid levels. This "subsurface impact" structure forces the high-speed incoming steam flow directly into the washing liquid.

[0028] A corrosion-resistant axial flow fan is installed at the center of the top end cap of each dust collector unit. This fan is designed to establish a stable negative pressure at the inlet of its respective impact duct and control the steam velocity entering the duct at approximately 17 m / s. This high-energy steam stream impacts the liquid surface vertically, generating violent bubbling, churning, and splashing below the liquid level. This process significantly increases the contact area and time between the gas and liquid phases. Solid slag particles (mainly glassy slag and particles containing valuable metals such as copper) entrained in the steam are captured by the liquid due to inertia; simultaneously, SO2 in the gas phase comes into full contact with the alkaline scrubbing liquid, undergoing a neutralization reaction and being absorbed. The purified gas passes through the space above the liquid surface and is extracted by the top-mounted fan.

[0029] To achieve automation and precise control of the desulfurization process, a centralized dosing control unit is installed in the system. This unit includes a 2-cubic-meter PE alkali storage tank for preparing a 15% (mass fraction) NaOH solution. An electromagnetically driven diaphragm metering pump has its inlet connected to the alkali storage tank, and its outlet connected via a branch pipe to the bottom of the water storage area of ​​each of the two dust collector units for alkali replenishment. Online pH meters are installed on the bypass circulation pipes of the water storage areas of both units to monitor the pH of the washing liquid in real time. The metering pump and these two online pH meters are linked to form a closed-loop control system: when the pH value of the washing liquid in any unit falls below the set lower limit (e.g., 10.0), the control system activates the metering pump to replenish alkali solution to that unit until the pH value returns to the set range (e.g., 10.0-10.5). This ensures that the washing liquid is always kept in the alkaline environment required for efficient desulfurization.

[0030] Finally, the exhaust fan outlets at the top of the two dust collector units merge via pipes and connect to a shared exhaust unit. This exhaust unit is a 30-meter-high steel exhaust stack, from which the purified, compliant gas is centrally discharged into the atmosphere. During system operation, Unit A and Unit B operate in parallel, jointly processing steam. When the sludge accumulated at the bottom of one unit reaches a certain amount, its inlet valve can be temporarily closed, and the dense sludge can be discharged using the bottom cleaning valve for metal recovery, while the other unit can continue operating, ensuring the continuity of the production process. Under these standard parameters (pH ~10.3, flow rate ~17m / s), the system outlet dust concentration can be consistently below 15mg / m³. 3 Sulfur dioxide concentration below 35 mg / m³ 3 Furthermore, copper-rich sludge can be recovered during each slag cleaning cycle, resulting in significant economic benefits.

[0031] Example 2

[0032] The system hardware structure in this embodiment is exactly the same as in Embodiment 1, but by adjusting the operating parameters, an economic optimization mode is demonstrated to ensure compliance with standards. In this operating mode, the pH control target range of the dosing control unit is lowered to 9.0-9.5. Simultaneously, the speed of the two induced draft fans is adjusted via frequency converters, reducing the average steam velocity in the impact duct from 17 m / s to approximately 15 m / s. Reducing the flow rate helps reduce the power consumption of the induced draft fans, while moderately lowering the pH value of the washing liquid directly reduces the consumption of NaOH.

[0033] Under this "economic operation mode," the system's purification efficiency remains at a high level due to a slight reduction in impact kinetic energy and alkalinity. Actual measurements show that the outlet dust concentration is typically below 20 mg / m³. 3 SO2 concentration below 60 mg / m³ 3It still meets stringent environmental emission standards. Compared with the standard mode of Example 1, this mode can save about 18% of electricity consumption and about 25% of alkali consumption, significantly reducing long-term operating costs and demonstrating the good operational flexibility and economic benefits of the system of the present invention.

[0034] Example 3

[0035] This embodiment focuses on demonstrating the reliability of the parallel system of the present invention and its ability to handle high-load conditions. The system structure remains the same as in Embodiment 1, but the operating parameters are adjusted to a high-load setting: the upper limit of the pH control target of the dosing control unit is increased to 10.8-11.0, and the induced draft fan is turned on to maximum, so that the steam velocity in the impingement duct reaches approximately 20 m / s. This setting is suitable for situations where the steam generation increases instantaneously or where extreme purification efficiency is required.

[0036] When the two units operate in parallel at these high parameters, the system exhibits optimal purification performance, with extremely low outlet pollutant concentrations. More importantly, this embodiment simulates an equipment maintenance scenario: assuming unit A needs to be shut down for internal inspection or component replacement. The operator first closes the inlet valve of unit A, and its induced draft fan also stops. At this time, all steam load is borne solely by unit B. Although the processing load of unit B is doubled, due to its design margin and operation at higher flow rates (20 m / s) and alkalinity (pH ~11), its purification effect during standalone operation, while slightly lower than that of the two units, still shows that the outlet gas pollutant concentration can be stably controlled within national standard limits, thus ensuring that the upstream air-quenched slag production process does not need to be interrupted. This fully demonstrates the outstanding advantages of the parallel design of this invention in ensuring production continuity and system reliability.

[0037] Comparative Example

[0038] A conventional single-tower wet scrubbing tower with a comparable air volume was used as a comparison. This tower was designed based on existing technology (similar to patent CN108955280A), featuring multiple spray layers, circulating water scrubbing, and manual, timed, and metered addition of sodium hydroxide to roughly adjust the pH of the circulating liquid. It lacked online monitoring and automatic feedback control. When treating air-quenched slag steam of the same source and nature as in the embodiments of this invention, the average dust concentration in the outlet flue gas of this system reached approximately 1500 mg / m³. 3 Sulfur dioxide concentration is between 60 and 120 mg / m³ 3 The desulfurization efficiency fluctuated significantly within a certain range, resulting in a low average desulfurization efficiency. After about 12 hours of system operation, the spray nozzles became severely clogged, and sludge accumulated rapidly at the bottom of the tower, causing a sharp increase in system resistance and a sudden drop in processing efficiency. The system had to be shut down for cleaning, directly causing an interruption in the upstream production process.

[0039] The above description is a preferred embodiment of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A steam impact-type water bath dust removal and desulfurization system for air-quenched slag, characterized in that, include: At least two impact water bath dust collector units are arranged in parallel, each dust collector unit comprising: A vertical cylindrical body with a water storage area at the bottom for storing alkaline detergent; An impingement air duct having an inlet end connected to a steam source and an impingement pipe, the end of which is submerged below the liquid surface of the water storage area; and An induced draft fan is installed at the top of the cylinder; A dosing control unit, connected to the water storage area of ​​the at least two dust collector units, is used to control the alkalinity of the alkaline washing liquid in the water storage area; and An exhaust unit is used to centrally discharge the gas purified by the dust collector unit.

2. The steam impact water bath dust removal and desulfurization system for air-quenched slag as described in claim 1, characterized in that, The impact duct is an inverted L-shaped or gooseneck-shaped duct.

3. The steam impact water bath dust removal and desulfurization system for air-quenched slag as described in claim 1, characterized in that, The dosing control unit includes an online pH meter for monitoring the pH value of the alkaline washing solution, and a metering pump that is linked to the online pH meter to automatically replenish the alkaline agent.

4. The steam impact water bath dust removal and desulfurization system for air-quenched slag as described in claim 3, characterized in that, The dosing control unit is used to maintain the pH value of the alkaline washing solution within the range of 9-11.

5. The steam impact water bath dust removal and desulfurization system for air-quenched slag as described in claim 1, characterized in that, The bottom of the cylinder is provided with a conical hopper and a slag removal valve that communicates with the bottom of the conical hopper.

6. The steam impact water bath dust removal and desulfurization system for air-quenched slag as described in claim 1, characterized in that, The induced draft fan is used to generate a steam flow rate of 15-20 m / s within the impact duct.

7. A method for dust removal and desulfurization using the steam impact water bath dust removal and desulfurization system for air-quenched slag as described in any one of claims 1 to 6, characterized in that, The method includes the following steps: Under the action of the induced draft fan, the high-temperature dust-containing and sulfur-containing steam generated by the air quenching slag process is introduced into the dust collector unit that is operating in parallel through the at least two impact air ducts; The steam is directed through the end of the impact duct into the alkaline washing liquid below the water surface in the water storage area to capture dust in the steam and neutralize it with sulfur dioxide. The alkalinity of the alkaline washing solution is adjusted by the dosing control unit; and The purified gas is discharged through the exhaust unit.

8. The method for dust removal and desulfurization according to claim 7, characterized in that, The specific steps for regulating the alkalinity of the alkaline detergent are as follows: online monitoring of the pH value of the alkaline detergent, and automatic replenishment of alkaline agents based on the monitoring results to maintain the pH value within the range of 9-11.

9. The method for dust removal and desulfurization according to claim 7, characterized in that, The method further includes: when one dust collector unit is being cleaned or maintained, at least one other dust collector unit remains operational.

10. The method for dust removal and desulfurization according to claim 7, characterized in that, The method further includes periodically discharging slurry enriched with slag particles through a slag removal valve at the bottom of the cylinder to recover the metal therein.

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