A method and system for hot air treatment and heat recovery of liquid slag

Abstract

This application provides a method and system for hot air treatment and heat recovery of liquid slag, belonging to the field of metallurgy, and solves the problems of low waste heat recovery rate and poor flue gas purification effect in existing hot air treatment and heat recovery methods for liquid slag. The method includes: performing gradient air quenching and granulation treatment on uniformly falling slag liquid so that the slag liquid passes through a first air pressure section and then a second air pressure section, wherein the air pressure of the first air pressure section is lower than that of the second air pressure section; centrifuging the molten slag treated by gradient air quenching and granulation to obtain slag particles and hot flue gas; the slag particles are heat-converted by a vibrating bed, and the hot flue gas is heat-exchanged by fluidized bed silica sand connected in series with the vibrating bed, recovering and utilizing the hot steam and hot air generated during the heat exchange process, and purifying the hot flue gas generated during the treatment process.

Description

Technical Field

[0001] This application relates to the field of metallurgical technology, and in particular to a method and system for hot air treatment and heat recovery of liquid slag. Background Technology

[0002] The smelting industry is currently facing two major challenges. First, environmental compliance pressures are increasingly severe. Traditional water-quenched slag processes consume 1-1.5 tons of water per ton of slag and produce highly polluting slag filtrate containing hydrogen sulfate, sulfur dioxide, and phenol-cyanide wastewater. Treatment costs are high, and it is difficult to meet zero-emission requirements. Simultaneously, fugitive dust emissions from slag yards lead to PM2.5 exceeding standards, causing continuous environmental damage. Second, energy waste is severe. Molten liquid slag contains approximately 1.8 GJ / ton of sensible heat at 1400-1500℃, but existing dry processes, such as air-quenched granulation combined with waste heat boilers, generally have a waste heat recovery rate of less than 40%, equivalent to an annual heat loss of approximately 20 million tons of standard coal equivalent, resulting in extremely low energy utilization efficiency. While existing solutions have made some improvements in water conservation, they still suffer from low waste heat recovery rates and poor flue gas purification effects, hindering the industry's sustainable development. Summary of the Invention

[0003] This application provides a method and system for hot air treatment and heat recovery of liquid slag, which can solve the problems of low waste heat recovery rate and poor flue gas purification effect in existing hot air treatment and heat recovery methods for liquid slag.

[0004] The first aspect of this application provides a method for hot air treatment and heat recovery of liquid slag, including:

[0005] The uniformly falling slag liquid is subjected to gradient air quenching and granulation treatment so that the slag liquid passes through a first air pressure section and then a second air pressure section, and the air pressure of the first air pressure section is lower than that of the second air pressure section.

[0006] The molten slag from gradient wind quenching and granulation treatment is separated by centrifugation to obtain slag particles and hot flue gas;

[0007] The slag particles are turned over and heat transferred by the vibrating bed. The hot flue gas is heat exchanged through fluidized bed silica sand connected in series with the vibrating bed. The hot steam and hot air generated during the heat exchange process are recovered and reused, and the hot flue gas generated during the treatment process is purified.

[0008] Optionally, the multiple air outlets of the first air pressure section are arranged obliquely around the falling slag liquid, and the multiple air outlets of the second air pressure section are arranged perpendicular to the falling direction of the slag liquid. The air pressure of the first air pressure section is 0.2-0.4 MPa, the air pressure of the second air pressure section is 0.6-1.0 MPa, and the air pressure difference between the first air pressure section and the second air pressure section is greater than or equal to 0.3 MPa. The first air pressure section is used to atomize the molten slag into droplets after contacting the slag liquid, and the second air pressure section is used to collide with the droplets to form smaller uniform particles.

[0009] Optionally, the centrifugal separation of the molten slag from the gradient wind quenching granulation treatment to obtain slag particles and hot flue gas includes:

[0010] The slag from gradient wind quenching and granulation is centrifugally separated through a silicon carbide ceramic filter cartridge. A high-speed airflow carries the slag into the silicon carbide ceramic filter cartridge, causing the slag particles to fall off the cartridge wall due to centrifugal force. Hot air passes through the micropores of the filter cartridge, and the inner wall of the silicon carbide ceramic filter cartridge is coated with a spinel coating.

[0011] Optionally, the vibrating bed is inclined, and the slag particles are subjected to heat transfer via the vibrating bed, including:

[0012] The slag particles are tumbled and rolled from top to bottom on the vibrating bed, exchanging heat with water or steam in the heat exchange tube bundle of the vibrating bed to produce saturated steam.

[0013] Optionally, the quartz sand forms a heat exchange bed, and finned tube bundles are arranged on the heat exchange bed. The hot flue gas undergoes heat exchange through fluidized quartz sand, including:

[0014] The cold air blown into the bottom of the heat exchange bed lifts up the quartz sand particles in the bed, thereby fluidizing the quartz sand.

[0015] The hot flue gas is converted into medium-temperature flue gas with a lower temperature by heat exchange through quartz sand. The high-temperature quartz sand after heat exchange is then converted into high-temperature hot air by heat exchange through cold air in the finned tube bundle.

[0016] Optionally, the purification of the hot flue gas generated during the processing includes:

[0017] When the temperature of the hot flue gas is higher than 350°C, a nano-calcium-based desulfurizing agent is injected into the hot flue gas, and then bag filter dust collection is performed.

[0018] When the temperature of the hot flue gas is below 300°C, the series-connected heat exchange of the vibrating bed and the fluidized bed quartz sand is adjusted to be connected in parallel.

[0019] Optionally, the spinel coating comprises 70 wt% MgO and 25 wt% [unclear - possibly a specific component or ingredient]. And 5wt% .

[0020] Optional, also includes:

[0021] right Ball milling was performed, during which 0.1 wt% carbon nanotubes were added. The particles are ball-milled to D50 = 0.8 μm to make them... The specific surface area of ​​the particles is greater than or equal to 25 m² / g;

[0022] Add 1wt% The nano-calcium-based desulfurizer is obtained by mixing.

[0023] The second aspect of this application provides a hot air treatment and heat recovery system for liquid slag, including:

[0024] The gradient air quenching granulation unit is used to perform gradient air quenching granulation treatment on uniformly falling slag liquid so that the slag liquid first passes through a first air pressure section and then through a second air pressure section, wherein the air pressure of the first air pressure section is lower than the air pressure of the second air pressure section.

[0025] The slag thermal separation unit is used to centrifuge the molten slag from the gradient wind quenching and granulation process to obtain slag particles and hot flue gas.

[0026] The heat exchange unit is used to turn the slag particles over and convert heat through the vibrating bed, and the hot flue gas is heat exchanged through the fluidized bed quartz sand connected in series with the vibrating bed. The hot steam and hot air generated during the heat exchange process are recovered and reused, and the hot flue gas generated during the treatment process is purified.

[0027] Optional, also includes:

[0028] Controller, used for:

[0029] Based on the obtained slag liquid temperature and hot flue gas temperature;

[0030] The wind pressure is dynamically adjusted based on the temperature of the slag liquid, and / or, when the temperature of the hot flue gas is higher than 350°C, a nano-calcium-based desulfurizing agent is injected into the hot flue gas, followed by bag filter dust collection; when the temperature of the hot flue gas is lower than 300°C, the series-connected vibrating bed heat exchanger and fluidized bed quartz sand heat exchanger are adjusted to a parallel relationship.

[0031] Optional, also includes:

[0032] The controller is also used for:

[0033] Controlled periodic backflushing of the slag thermal separation unit and / or heat exchange unit with compressed nitrogen; and / or,

[0034] Control the acoustic horn to perform anti-clogging operation on the slag heat separation unit and / or heat exchange unit.

[0035] In summary, the liquid slag hot air treatment and heat recovery method provided in this application embodiment involves gradient air quenching and granulation treatment of uniformly falling slag liquid so that the slag liquid first passes through a first air pressure section and then through a second air pressure section, where the air pressure of the first air pressure section is lower than that of the second air pressure section; the molten slag treated by gradient air quenching and granulation is centrifuged to obtain slag particles and hot flue gas; the slag particles are heat-converted by a vibrating bed, and the hot flue gas is heat-exchanged by fluidized bed silica sand connected in series with the vibrating bed, so that the hot steam and hot air generated during the heat exchange process are recovered and reused, and the hot flue gas generated during the treatment process is purified. Therefore, this method simultaneously recovers the sensible heat of slag particles and the sensible heat of hot flue gas, solving the defect of traditional processes that only recover the sensible heat of flue gas and waste the sensible heat of slag particles. Gradient granulation makes the particle size more concentrated and the glassy content higher, making the slag particles more suitable as raw materials for downstream products such as mineral powder and micro powder. At the same time, the moving bed cools the slag particles to a safe storage and transportation temperature, reducing the risk of secondary dust and thermal damage. Medium-temperature desulfurization avoids the adverse situation of waste heat loss caused by deep cooling for purification. Desulfurization efficiency is maintained through material and residence time design. The connection from granulation, separation, heat exchange to purification relies on the high efficiency of solid-gas separation, anti-adhesion structure and online dust removal measures, reducing the risk of blockage, wear and unplanned downtime.

[0036] Correspondingly, the systems, electronic devices, and computer-readable storage media provided in the embodiments of the present invention also have the above-mentioned technical effects. Attached Figure Description

[0037] Figure 1 A schematic flowchart illustrating a possible method for hot air treatment and heat recovery of liquid slag, provided for an embodiment of this application;

[0038] Figure 2 A schematic structural block diagram of a possible liquid slag hot air treatment and heat recovery system provided in this application embodiment;

[0039] Figure 3 This is a schematic structural block diagram of a controller for a liquid slag hot air treatment and heat recovery system provided in an embodiment of this application. Detailed Implementation

[0040] This application provides a method and related equipment for hot air treatment and heat recovery of liquid slag, which can solve the problems of low waste heat recovery rate and poor flue gas purification effect in existing hot air treatment and heat recovery methods for liquid slag.

[0041] Please see Figure 1 The flowchart provided in this application embodiment illustrates a method for hot air treatment and heat recovery of liquid slag, which may specifically include:

[0042] S110-S130.

[0043] S110, the uniformly falling slag liquid is subjected to gradient air quenching and granulation treatment so that the slag liquid passes through the first air pressure section and then the second air pressure section, and the air pressure of the first air pressure section is lower than the air pressure of the second air pressure section.

[0044] S120 is used to centrifuge the molten slag from gradient wind quenching and granulation treatment to obtain slag particles and hot flue gas.

[0045] S130, the slag particles are turned over and heat transferred by the vibrating bed, and the hot flue gas is heat exchanged by the fluidized bed quartz sand connected in series with the vibrating bed. The hot steam and hot air generated during the heat exchange process are recovered and reused, and the hot flue gas generated during the treatment process is purified.

[0046] For example, high-temperature molten slag is evenly distributed through a top centrifugal distribution plate, allowing the slag to fall in a stable and uniform manner, reducing the risk of local over-granulation and adhesion caused by flow deviation from the source. Subsequently, a two-stage spray gun is set up in the granulation tower to form two air pressure zones. The upper layer has a low-pressure spray gun with an inclination angle of about 30 degrees arranged in a ring as the first air pressure zone. The lower air pressure is used to pre-atomize the falling molten slag, transforming it from a continuous liquid flow into a group of droplets with a particle size of about 3 to 5 mm, thereby converting the viscosity and flow fluctuations of the slag liquid into... To achieve more controllable droplet size distribution, a vertical high-pressure spray gun is arranged in the lower layer as a second air pressure section. This section uses higher air pressure to perform secondary crushing of the pre-atomized droplets, further refining and converging the droplets into a narrower particle size range of approximately 1 to 3 millimeters. Simultaneously, the rapid cooling during granulation promotes the formation of slag particles with a higher glass transition rate. Furthermore, the slag temperature, obtained from infrared thermography, can be read by the DCS, allowing for dynamic, limited adjustment of the air pressure in both sections based on the slag temperature deviation. This ensures stable granulation efficiency and particle size even when the slag temperature fluctuates. By employing a segmented crushing principle of low pressure followed by high pressure, the granulation process is first stabilized and then intensified, reducing excessively fine powder and particle size dispersion caused by the direct effect of high air pressure in the first stage. This improves slag particle uniformity and glass transition rate, and provides a predictable particle size and thermal state basis for subsequent solid-gas separation and heat exchange.

[0047] For example, the granulated hot gas containing slag particles is introduced into a slag-heat separator. A vortex guide plate is installed at the separator inlet to create a stable rotating flow field within the separation chamber. Utilizing the significantly higher density and inertia of the slag particles compared to the gas phase, the slag particles migrate outwards under high radial acceleration, impacting the cylinder wall before falling and being collected. Meanwhile, the hot flue gas rises in the central area and exits through the micropores of the filter cartridge. To balance separation efficiency and anti-adhesion reliability under high-temperature conditions, a silicon carbide ceramic filter cartridge with an anti-adhesion coating is used to reduce the probability of clogging caused by the softening and adhesion of high-temperature fine particles on the filter material surface. Simultaneously, compressed nitrogen pulse backflushing is configured, triggering short-term backflushing based on pressure difference or operating time to clean the filter pores and stabilize resistance. Even under conditions where high-temperature fine particles are difficult to separate, high separation efficiency is maintained, significantly reducing erosion, ash accumulation, clogging, and secondary dust generation caused by slag particles entrained in subsequent heat exchangers and purification equipment. This ensures the energy-level recovery boundary conditions for slag particles undergoing solid-phase heat exchange and hot flue gas undergoing gas-phase heat exchange are met, and improves the continuous operational stability of the entire system.

[0048] For example, the separated high-temperature slag particles are conveyed into a moving bed heat exchanger. The heat exchanger can be a heat-resistant steel tank with a certain inclination angle and a wear-resistant and heat-resistant lining. High-temperature and corrosion-resistant heat exchange tube bundles are arranged inside. The slag particles move from top to bottom along the bed surface under gravity. Feed water or a steam-water medium is introduced into the tube bundles, forming a counter-current heat exchange with the slag particles. To avoid the formation of stable arches or localized sintering in the slag layer, which would increase thermal resistance, a vibrating feed bed can be used to achieve uniform slag distribution and cause the slag particles to periodically tumble and renew their contact surfaces within the bed. This continuously disrupts the sintering contact points between particles and maintains a relatively stable slag layer porosity. Simultaneously, the slag layer thickness is controlled within a suitable range. By optimizing the heat exchange driving force and residence time, the system can effectively cool slag particles from high temperatures to a safe storage and transportation temperature range, while producing saturated steam at a certain pressure level. To enhance anti-caking capabilities, an acoustic unblocking device can be installed between the pipes, supplemented by nitrogen pulse jet cleaning. When an abnormal increase in the vibration motor current indicates that the slag layer is prone to caking, fine-grained quartz sand can be added as a flow aid medium, and the amplitude can be increased to restore the loose flow of the slag layer. In addition, to solve the problem of high-temperature slag particles easily sticking in the conveying pipeline, a fully enclosed fluidized transport method with nitrogen protection can be adopted, allowing the slag particles to be transported in a suspended state and minimizing contact with the pipe wall. In this way, the high-grade sensible heat carried by the slag particles is converted from unusable solid heat into a dispatchable steam heat source. At the same time, vibration overturning and unblocking measures reduce the risk of caking shutdown, improve the stability of heat exchange efficiency, and reduce the safety and dust hazards caused by the slag particle outlet temperature.

[0049] For example, the hot flue gas after centrifugal separation is sent to a fluidized bed quartz sand heat exchanger arranged in series with the aforementioned moving bed. The bottom of the heat exchanger is equipped with an air distribution plate and filled with quartz sand bed material of a certain particle size range. Low-temperature air is blown into the bottom to bring the bed material to a stable fluidized state. Strong convective heat exchange occurs between the hot flue gas and the bed and the upper finned tube bundle, heating the air inside the finned tubes and outputting it as directly usable high-temperature hot air. To suppress bed segregation and local short-circuiting, a multi-zone independent air chamber air distribution structure can be adopted, and the air volume of each zone can be distributed according to the bed pressure difference to control the bed density difference within a small range. Simultaneously, guide ribs and inclined guide vanes are installed inside the bed to break large bubbles and improve the uniformity of gas-solid contact. During operation... In terms of operation, when the slag temperature at the moving bed outlet is detected to be too high, the fluidized bed air volume can be increased to enhance the gas phase heat exchange capacity and reduce the heat load fluctuation at the subsequent purification inlet. After waste heat recovery, in order to balance desulfurization efficiency and avoid heat loss caused by additional cooling, the flue gas can enter the dry purification unit in a more suitable medium temperature range. First, in the medium temperature desulfurization reaction tower, the residence time is extended by multi-stage swirl calcium spraying and guide grid. Nano-sized calcium hydroxide with a high specific surface area is injected into the flue gas, so that it reacts with sulfur dioxide under oxygen-containing conditions to generate calcium sulfate and achieve a high desulfurization rate. Then, the flue gas enters the bag filter dust collector, where high-temperature resistant filter bags intercept dust and pulse cleaning maintains stable resistance, so that the concentration of emitted particulate matter meets the strict limits. Thus, on the one hand, the high heat transfer coefficient of the fluidized bed is used to efficiently transfer the sensible heat of the hot flue gas to the process air, obtaining hot air with a stable temperature that can be directly used for preheating combustion air and drying materials; on the other hand, dry desulfurization and dust removal are completed in the medium-temperature window after waste heat recovery, which not only ensures that pollutants are discharged in compliance with standards, but also retains the available heat to the maximum extent and reduces the risk of equipment corrosion and condensation, thereby realizing the engineering feasibility of synergistic recovery and safe purification of two energy forms, hot air and steam.

[0050] In summary, this method uses gradient air quenching to stabilize and granulate liquid slag into slag particles with concentrated particle size and high glass transition rate. Then, centrifugal separation reliably separates the solid slag particles from the gaseous hot flue gas. The solid phase enters a moving bed for vibration and tumbling to enhance heat exchange and output steam, while the gas phase enters a fluidized bed for quartz sand heat exchange to output hot air. Finally, dry desulfurization and baghouse dust collection are completed in the medium-temperature range after waste heat recovery. This converts the sensible heat originally dispersed in the slag particles and flue gas into two types of energy, steam and hot air, which can be directly absorbed by the production system. Compared with the common path of only recovering the sensible heat of flue gas, this scheme significantly improves the overall waste heat utilization level. Through separation, vibration tumbling, backflushing to clear blockages, bed homogenization and air distribution, and medium-temperature purification, it reduces the probability of failure caused by difficulties in high-temperature fine particle separation, slag particle adhesion and unstable unit connection, and improves continuous operation capability and the availability of recovered energy.

[0051] In some examples, multiple air outlets of the first air pressure section are arranged obliquely around the falling slag, and multiple air outlets of the second air pressure section are arranged perpendicular to the falling direction of the slag. The air pressure of the first air pressure section is 0.2-0.4 MPa, the air pressure of the second air pressure section is 0.6-1.0 MPa, and the air pressure difference between the first air pressure section and the second air pressure section is greater than or equal to 0.3 MPa. The first air pressure section is used to atomize the molten slag into droplets after contacting the slag, and the second air pressure section is used to collide with the droplets to form smaller, uniform particles.

[0052] For example, the gradient air-quenching granulation treatment is set up with two levels of air pressure zones: In the first air pressure zone, multiple air outlets are arranged circumferentially around the falling slag liquid inside the granulation tower, and tilted at a preset angle relative to the falling direction of the slag liquid towards the jet. This allows the ejected hot air to exert tangential shearing and lateral coating effects on the slag liquid, thereby disrupting the stability of the liquid film and suppressing large-scale liquid flow oscillations under relatively mild dynamic pressure conditions, atomizing the molten slag into a relatively concentrated group of droplets. In the second air pressure zone, multiple air outlets are also arranged circumferentially, but their jetting direction is perpendicular to the falling direction of the slag liquid. This allows the hot air to collide with the droplet group with a higher positive impact momentum, applying a stronger normal pressure difference and transient impact shear to the droplets, thereby triggering secondary droplet breakage and forming smaller, more uniformly sized solidified particles. To achieve graded granulation with pre-atomization followed by uniform refinement, the air pressure in the first air pressure zone is controlled at 0.2 MPa to 0.4 MPa, and the air pressure in the second air pressure zone is controlled at 0.6 MPa. The pressure is increased to 1.0 MPa, and the pressure difference between the first and second pressure sections is greater than or equal to 0.3 MPa, so that the second pressure section has sufficient dynamic pressure increment relative to the first pressure section to ensure that the secondary breakage threshold of the droplets is stably triggered. Thus, on the one hand, it can avoid excessive pulverization, increased fine powder carrying capacity and particle size distribution caused by using high pressure at the beginning. On the other hand, it can achieve particle size convergence in the second pressure section and improve particle uniformity and stability of subsequent centrifugal separation and moving bed heat exchange processes. At the same time, due to the fast granulation speed and high cooling rate, it is beneficial to improve the glassiness of slag particles and reduce the probability of subsequent slag particle agglomeration.

[0053] In some examples, the centrifugal separation of the molten slag from the gradient wind quenching granulation treatment to obtain slag particles and hot flue gas includes:

[0054] The slag from gradient wind quenching and granulation is centrifugally separated through a silicon carbide ceramic filter cartridge. A high-speed airflow carries the slag into the silicon carbide ceramic filter cartridge, causing the slag particles to fall off the cartridge wall due to centrifugal force. Hot air passes through the micropores of the filter cartridge, and the inner wall of the silicon carbide ceramic filter cartridge is coated with a spinel coating.

[0055] For example, the step of centrifugally separating the slag from the gradient wind quenching and granulation treatment to obtain slag particles and hot flue gas can be specifically achieved by setting up a slag heat separator and using a silicon carbide ceramic filter cartridge: the high-speed airflow formed after gradient wind quenching and granulation carries the slag particle mixture into the separation chamber. At the inlet, the airflow is forced to form a stable rotating flow field through a vortex guide plate. The slag particles migrate radially outward due to inertia and centrifugal force in the rotating flow field and fall off the inner wall of the filter cartridge after impacting it. This achieves rapid sedimentation and collection of slag particles in the solid phase path. At the same time, hot air penetrates through the micropores of the filter cartridge along the central area and the radial direction of the filter cartridge. For example, the pore size is about 10 μm. This further intercepts the fine particles and outputs relatively clean hot flue gas. The overall separation process is characterized by inertial separation, centrifugal separation, and then micropore filtration. It can maintain a high separation efficiency even under the condition that fine particles are difficult to separate at high temperatures, with a separation efficiency of more than 97%. This significantly reduces the risk of erosion, ash accumulation, and blockage caused by slag particles being entrained into the subsequent fluidized bed heat exchange and dry purification unit.

[0056] For example, to address the problem of high-temperature slag particles easily softening and adhering to the filter cartridge surface, leading to filter pore blockage, increased pressure differential, and decreased separation efficiency, the inner wall of the silicon carbide ceramic filter cartridge can be coated with a spinel coating, which can be formed by laser cladding. The anti-adhesion layer utilizes the chemical stability and low adhesion tendency of the spinel phase at high temperatures to weaken the wetting and adhesion between slag particles and the filter cartridge matrix, reducing the probability of adhesive bridge formation and extending the continuous operating life of the filter cartridge. Simultaneously, compressed nitrogen pulse backflushing can be configured, for example, a single 0.1-second backflushing pressure of approximately 0.5 MPa periodically cleaning the micropores of the filter cartridge, maintaining stable separator differential pressure and reducing maintenance frequency without significantly disturbing the operating conditions of the upstream granulation tower. By establishing an efficient solid-gas separation boundary, the heat from the slag particles can be deeply recovered in the subsequent moving bed via a controllable solid-phase path, while hot flue gas can enter the fluidized bed heat exchange and purification unit under low entrainment conditions, thereby improving the availability of system heat recovery and the reliability of continuous operation.

[0057] In some examples, the vibrating bed is inclined, and the slag particles are subjected to heat transfer via the vibrating bed, including:

[0058] The slag particles are tumbled and rolled from top to bottom on the vibrating bed, exchanging heat with water or steam in the heat exchange tube bundle of the vibrating bed to produce saturated steam.

[0059] For example, the vibrating bed adopts an inclined moving bed heat exchange structure, with its bed body set at a preset inclination angle along the material's downward direction, so that the slag particles have a natural upward-moving driving force under the action of gravity. When the slag particles are turned over and heat exchanged in the vibrating bed, after entering from the upper end of the vibrating bed, the slag particles undergo continuous turning, rolling, and interlayer renewal under the periodic excitation force generated by the vibrating motor. The surface and internal particles of the slag layer constantly exchange positions, thereby avoiding the formation of sintering and sticking points due to static contact of the slag particles at high temperatures, and reducing the risk of increased heat transfer resistance and channeling caused by slag layer caking. Heat exchange tube bundles are arranged along the bed surface inside the vibrating bed. Feedwater or a steam-water mixture is introduced into the tube bundle. The slag particles are in direct contact with the outer wall of the tube bundle and repeatedly brush the tube wall during the tumbling and rolling process, so that the convective heat transfer coefficient outside the tube is maintained at a high level. The sensible heat of the slag particles is transferred to the working fluid inside the tube through the tube wall, causing it to heat up and vaporize, and finally saturated steam is produced at the tube bundle outlet. The residence time of slag particles and the target steam pressure level can be matched by adjusting the bed inclination angle, vibration frequency and amplitude, and slag layer thickness. For example, when the target is saturated steam with a higher pressure, the residence time of slag particles can be appropriately increased and the feedwater inlet pressure can be increased. When the slag temperature fluctuation causes unstable steam production, the vibration intensity can be increased to enhance the tumbling of slag particles and the tube wall refresh frequency to stabilize evaporative heat transfer. Therefore, the high-grade sensible heat carried by the slag particles is converted into saturated steam that can be dispatched and utilized through direct contact enhanced heat exchange. Compared with the recovery path that relies solely on the waste heat boiler of flue gas, this method can significantly reduce the sensible heat loss of the slag particles. At the same time, since the slag particles are continuously turned and rolled in the bed and gradually cooled to a lower temperature, the safety risks and risks of secondary dust and agglomeration in the subsequent storage and transportation process can be reduced, and the heat exchange stability and reliability of the entire system under long-term operation conditions can be improved.

[0060] In some examples, the quartz sand forms a heat exchange bed, on which finned tube bundles are arranged, and the hot flue gas undergoes heat exchange through fluidized quartz sand, including:

[0061] The cold air blown into the bottom of the heat exchange bed lifts up the quartz sand particles in the bed, thereby fluidizing the quartz sand.

[0062] The hot flue gas is converted into medium-temperature flue gas with a lower temperature by heat exchange through quartz sand. The high-temperature quartz sand after heat exchange is then converted into high-temperature hot air by heat exchange through cold air in the finned tube bundle.

[0063] For example, the fluidized bed quartz sand heat exchanger uses quartz sand to form a heat exchange bed, and finned tube bundles are arranged above or inside the heat exchange bed to achieve indirect heat transfer from hot flue gas to quartz sand to cold air. During operation, cold air, which can also be pre-treated air, is blown in from the bottom of the heat exchange bed through an air distribution plate. The cold air forms a relatively uniform upward airflow at the bottom of the bed and generates upward resistance to the quartz sand particles in the bed. When this resistance is equivalent to the weight of the particles, the quartz sand particles are lifted and exhibit fluidized motion in a fluid-like state. The particles inside the bed undergo strong mixing and circulation, making the bed temperature spatially uniform, and the gas-solid contact interface is continuously renewed, improving the convective heat transfer intensity between the hot flue gas and the bed material and reducing the risk of agglomeration caused by local overheating; subsequently, The hot flue gas enters from the side or top of the heat exchanger and passes through the fluidized quartz sand bed. The sensible heat of the hot flue gas is transferred to the quartz sand particles through gas-solid convection, which lowers the temperature of the hot flue gas and converts it into a lower temperature medium-temperature flue gas. This achieves both cooling and energy extraction of the hot flue gas, and heating the quartz sand particles in the bed to become high-temperature quartz sand. Furthermore, the high-temperature quartz sand continuously washes over and coats the outer surface of the finned tube bundle during its vigorous mixing and turbulence. Cold air blown in from the bottom or another stream of cold air is introduced into the finned tube bundle. The quartz sand particles transfer the heat they have acquired to the finned tube bundle through contact heat transfer between the particles and the tube wall and through micro-convection heat transfer between the particles, which raises the temperature of the cold air inside the tube and converts it into recyclable high-temperature hot air for output. Therefore, by utilizing the strong mixing and high heat transfer coefficient characteristics of the fluidized bed, the sensible heat of the hot flue gas can be rapidly extracted with a small heat transfer temperature difference and output as a relatively stable high-temperature hot air. At the same time, the flue gas side temperature is reduced to a window range more suitable for subsequent medium-temperature dry desulfurization and bag filter dust collection, thereby reducing the temperature resistance and corrosion burden of the purification unit. In addition, due to the uniform bed temperature and the continuous scouring and renewal of the outer surface of the finned tube bundle by quartz sand particles, the heat transfer attenuation caused by dust deposition and local scaling on the heat exchange surface can be reduced. This allows the system to maintain a relatively stable hot air outlet temperature and heat recovery capacity under long-term operation conditions, making it suitable for various energy consumption scenarios such as combustion air preheating, material drying, or process hot air supply.

[0064] In some examples, the purification of the hot flue gas generated during the process includes:

[0065] When the temperature of the hot flue gas is higher than 350°C, a nano-calcium-based desulfurizing agent is injected into the hot flue gas, and then bag filter dust collection is performed.

[0066] When the temperature of the hot flue gas is below 300°C, the series-connected heat exchange of the vibrating bed and the fluidized bed quartz sand is adjusted to be connected in parallel.

[0067] For example, the purification of the hot flue gas generated during the treatment process adopts a segmented strategy that matches the waste heat recovery conditions, so as to simultaneously consider the desulfurization reaction efficiency, dust removal reliability, and thermal energy availability: when the temperature of the hot flue gas is detected to be higher than 350°C, calcium-based dry desulfurization is preferentially implemented in the high-temperature zone. Specifically, before the hot flue gas enters the dust removal unit, a multi-point injection device is set in the flue or desulfurization reaction section to inject nano-calcium-based desulfurizing agents, such as nano-sized calcium hydroxide or surface-activated calcium-based materials, into the hot flue gas, so that it still has a high specific surface area and a fast diffusion mass transfer rate under high temperature conditions. The nanoparticles form a uniform suspension in the flue gas turbulence and fully contact with sulfur dioxide. Upon contact, solid products such as calcium sulfate or calcium sulfite are generated and carried by the airflow into the subsequent bag filter. The bag filter uses high-temperature resistant filter material and maintains a stable pressure difference through pulse cleaning. The dust layer formed on the surface of the filter bag further promotes the contact reaction between residual sulfur dioxide and calcium-based particles in the filter cake layer. Thus, a high desulfurization rate is achieved and particulate matter emission concentration is reduced simultaneously during the process of first spraying calcium and then using the filter bag. In this way, the main desulfurization and particle capture are completed when the temperature is still high, which can reduce the heat loss caused by additional deep cooling to meet the temperature resistance of the filter bag. At the same time, it avoids the risk of ash accumulation and corrosion caused by high-temperature flue gas directly entering the downstream heat exchange surface, thereby improving the long-term stability and maintenance cycle of the purification unit.

[0068] For example, when the temperature of the hot flue gas is detected to be below 300°C, in order to prevent the hot flue gas from being further over-extracted in the series heat exchange path and falling into a temperature range unfavorable to calcium-based reactions or prone to condensation and adhesion, and to maintain the hot flue gas in a more suitable medium-temperature purification window, the originally series-connected vibrating bed heat exchange and fluidized bed quartz sand heat exchange can be adjusted to a parallel relationship. For example, a controllable diversion valve and bypass flue can be set at the hot flue gas distribution node after centrifugal separation, so that the hot flue gas is sent to the vibrating bed section and the fluidized bed quartz sand section in proportion, so that each of the two heat exchange branches only bears part of the flue gas flow and part of the heat exchange load, thereby reducing the heat exchange intensity and flue gas residence time of a single path and inhibiting the flue gas temperature from continuing to drop; at the same time, the medium-temperature flue gas output from the two branches is remixed in the confluence section, so that the temperature and flow of the mixed flue gas are more easily controlled stably and meet the inlet conditions of subsequent calcium spraying and bag dust collection. Therefore, when the initial temperature of the hot flue gas is low, the outlet temperature of the flue gas can be softly limited by changing the topology of the heat exchange network. This ensures that a certain amount of hot air or steam can still be recovered to maintain energy utilization, while avoiding the decrease in desulfurization reaction rate, deliquescence and adhesion on the filter bag surface, or abnormal fluctuations in system pressure caused by excessively low purification inlet temperature. This improves the adaptability of the entire system to low temperature conditions and load fluctuation conditions, as well as the reliability of achieving emission standards.

[0069] In some examples, the spinel coating comprises 70 wt% MgO and 25 wt% [unclear text - possibly a specific ingredient or component]. And 5wt% .

[0070] For example, the spinel coating on the inner wall of the silicon carbide ceramic filter cartridge is made of... The coating is based on spinel and stabilized with rare earth oxides. The spinel coating comprises, by mass percentage, 70 wt% MgO and 25 wt%... And 5wt% Among them, MgO and Under high-temperature conditions, a thermally stable magnesium-aluminum spinel phase can be formed, enabling the coating to maintain high heat resistance and chemical inertness under the conditions of hot flue gas scouring and slag particle impact, and reducing the tendency of slag particles to wet and sinter adhere to the coating surface. As a stabilizing component, it can improve the coating's resistance to high-temperature densification and thermal shock stability, and reduce the propagation of microcracks caused by frequent pulse backflushing and temperature fluctuations. This allows the filter cartridge inner wall to maintain a low probability of surface adhesion and stable micropore permeability during long-term operation. Therefore, under the combined effect of centrifugal separation and micropore filtration, even with the combined effects of high-temperature fine particles and sulfur-containing flue gas, the filter cartridge is less prone to rapid clogging and differential pressure runaway. This extends the continuous operation cycle and reduces the frequency of maintenance and replacement. At the same time, it provides lower entrainment medium-temperature flue gas inlet conditions for subsequent fluidized bed heat exchange and purification units, improving the overall heat recovery efficiency and operational reliability of the system.

[0071] In some examples, it also includes:

[0072] right Ball milling was performed, during which 0.1 wt% carbon nanotubes were added. The particles are ball-milled to D50 = 0.8 μm to make them... The specific surface area of ​​the particles is greater than or equal to 25 m² / g;

[0073] Add 1wt% The nano-calcium-based desulfurizer is obtained by mixing.

[0074] For example, to obtain a nano-calcium-based desulfurizer suitable for high-temperature hot flue gas conditions and possessing high reactivity, the method further includes nano-sizing and catalytic modification of the calcium-based desulfurizer: firstly, calcium hydroxide is selected... As a matrix powder, it is added to a ball mill for mechanical ball milling, and during the ball milling process, it is... Adding 0.1 wt% carbon nanotubes allows the carbon nanotubes to disperse and embed under strong shear and impact. At the interface of particle agglomerates, it plays a role in inhibiting secondary agglomeration and constructing a microscale supporting framework, preventing particles from rapidly re-adheding after high-energy ball milling and causing particle size rebound; by controlling the ball milling speed, ball-to-material ratio, and ball milling time, The median particle size reached a D50 of 0.8 μm, and its specific surface area was increased to greater than or equal to 25 m² / g, thereby significantly increasing... In the smoke The effective contact interface and shortened diffusion path make the desulfurization reaction more dominated by surface reaction and intrapore diffusion, rather than external diffusion restriction; subsequently, the obtained nano-sized Add 1 wt% of the powder by weight And they are mixed evenly to form the nano-calcium-based desulfurizer, wherein, It exhibits strong redox buffering capacity and surface activity in oxygen-containing flue gas environments, which is beneficial for promoting the further conversion of sulfite to sulfate and reducing the rate at which reaction products form a dense layer on the particle surface, thereby delaying passivation and increasing the absorption capacity per unit mass and the reaction persistence in the high-temperature range. Therefore, it can maintain a high desulfurization rate and more efficient calcium utilization even at high flue gas temperatures. Furthermore, due to the inhibitory effect of carbon nanotubes on agglomeration, the powder injected into the flue gas duct more easily forms a stable, dispersed suspension and mixes evenly with the flue gas, reducing the dust load and excessive filter bag cake formation caused by localized excessive calcium injection; and through… After modification and improvement of reaction depth, the amount of calcium-based additives can be reduced under the same emission index, thereby reducing the solid load and cleaning frequency of the subsequent bag filter, and improving the system purification stability and overall energy efficiency.

[0075] In some cases, considering that under certain furnace conditions, the bubbles or microporous structures entrained in the slag are not visually visible, the surface may appear to have been atomized into droplets by the first air pressure section, but there is gas trapped inside the droplets. When the droplets enter the second air pressure section and are subjected to a stronger positive impact, the internal bubbles will expand and burst instantly, causing the droplets to implode and break apart, forming a large amount of ultrafine powder. This ultrafine powder is more likely to enter the microporous area of ​​the separator and filter cartridge with the flue gas, leading to increased pressure differential, coating adhesion, and increased bag filter load. The design logic of the degassing and pressure stabilization zone is to use gentle hot air disturbance and rotating flow before entering the high air pressure impact zone to cause the internal bubbles of the droplets to migrate to the surface and be released in advance, thereby transforming the object of the second air pressure section from gas-containing droplets into solid droplets. Based on this, in some examples, a degassing and stabilizing zone is set between the first and second air pressure sections. The degassing and stabilizing zone applies periodic pressure pulsations of hot air to the droplet group formed by the atomization of slag and liquid, and forms a rotating airflow to promote the migration and rupture of bubbles inside the droplets before they enter the second air pressure section for secondary granulation, thereby reducing the proportion of ultrafine powder generated by the secondary bursting of droplets in the second air pressure section.

[0076] For example, a short-range degassing and pressure-stabilizing zone is set between the downstream of the first pressure section and the upstream of the second pressure section. This zone is equipped with multiple low-flow-rate hot air nozzles, controlled by pulse valves to release hot air at a preset frequency. The pulse amplitude is smaller than the continuous pressure of the first pressure section, allowing it to primarily function as a pressure micro-disturbance and interface disturbance. Simultaneously, a tangential flow guide structure is incorporated into the degassing and pressure-stabilizing zone, causing the pulsed hot air to form a weakly rotating airflow within the tower. Droplets undergo slight spin and lateral tumbling within this rotating airflow, prompting internal bubbles to migrate to the droplet surface and burst. The length of the degassing and pressure-stabilizing zone can be designed based on the average residence time of the droplet group, ensuring that bubble release occurs while the droplets are still in a high-temperature, low-viscosity stage, preventing bubbles from freezing inside the particles after cooling and solidification. If an increase in the proportion of fine powder or a greater rate of increase in the separator pressure difference is detected, the pulse frequency or tangential flow guide intensity can be increased to enhance the degassing effect. The direct effect of this solution is to reduce implosion-type fragmentation in the second air pressure section, decrease the generation of ultrafine powder, and make the particle size distribution more concentrated. The dust load on the separator and filter cartridges is reduced, pressure differential fluctuations are decreased, and the frequency of filter cartridge backflushing and baghouse cleaning can be reduced, thereby improving the stability of continuous operation. When the moisture content of the raw materials or fluctuations in furnace conditions cause an increase in the gas content of the molten slag, conventional processes will experience a sudden increase in baghouse pressure differential and emission fluctuations in a short period of time. After introducing the degassing and pressure stabilization zone, the peak value of fine powder is weakened, the dust concentration in the flue is more stable, and the purification system is more likely to maintain stable operating conditions.

[0077] In some cases, uniform slag fall is often assumed to be the norm in engineering practice. However, wear of the diverter plate, slag buildup, and slag volume fluctuations can create multiple jets or deflected slag curtains. Deflection causes the inclined airflow in the first pressure section to only pre-atomize a portion of the slag flow, while the other portion enters the second pressure section almost directly, ultimately resulting in a polarization where some particles are too fine and others are too coarse. This can be addressed through two methods: first, using a geometry shaper to force the slag liquid to spread into a continuous thin curtain, reducing jet splitting; second, dividing the first pressure section circumferentially and applying differential pressure to provide stronger pre-atomization compensation to the deflected side, restoring the uniformity of droplet size before entering the second pressure section from the source. Based on this, in some examples, the following is also included: a slag curtain forming device is set upstream of the first wind pressure section, the slag curtain forming device includes an annular guide lip and an adjustable overflow groove, so as to force the falling slag liquid to expand into a continuous thin curtain; and the multiple air outlets of the first wind pressure section are divided into at least two circumferential zones, and a first section wind pressure is set on the deflection side zone to be higher than that on the non-deflection side zone, so as to compensate the wind field for the deflection of the falling slag curtain before it enters the second wind pressure section.

[0078] For example, a slag curtain former is installed at the top of the granulation tower or upstream of the first air pressure section. The former includes a high-temperature resistant annular guide lip and an adjustable overflow channel. After passing through the guide lip, the slag liquid is stretched into an annular thin curtain and falls uniformly along the circumference. The opening of the overflow channel can be adjusted according to the slag volume to maintain the thickness of the thin curtain within a preset range. The air outlet of the first air pressure section is divided into at least two sections circumferentially, each section is supplied with air by an independent pressure regulating valve. When the flow deviation direction is identified by monitoring the pressure distribution inside the tower, the eccentric position of the slag curtain, or the online particle size monitoring, the first section air pressure or air volume of the deviated side section is increased to achieve more sufficient shear atomization of the slag curtain on the deviated side, while the non-deviated side maintains a lower air pressure to avoid over-atomization. Subsequently, the droplet group enters the second air pressure section for unified secondary crushing, ensuring that the secondary crushing acts on droplet groups of similar size. This scheme can significantly reduce the tail of the particle size distribution, reduce the coexistence of large particles and ultrafine powder, thereby improving centrifugal separation efficiency and reducing the risk of ash accumulation and wear on the downstream heat exchanger. When local wear of the diversion plate causes the slag liquid to fall to one side, the uncompensated condition will manifest as fluctuations in the porosity of the moving bed slag layer, local channelization, and increased dust load on the hot air side. After adopting slag curtain forming and circumferential differential pressure compensation, the slag particle size is more uniform, the moving bed material is more stable, and the hot air outlet temperature fluctuation is smaller.

[0079] In some cases, considering that certain slag components exhibit a rapid increase in viscosity or enhanced surface stickiness at specific temperature ranges, even if the second pressure section abrades the droplets, the particle surface remains within the viscous window. After collisions in high-solids-content turbulent flow, particles are prone to agglomeration, leading to secondary aggregation and negating the granulation effect, resulting in the abnormal phenomenon of increased agglomeration with finer particles. The purpose of the instantaneous cooling and shaping air curtain is to rapidly raise the particle surface temperature across the viscous window and solidify it into a non-viscous state before centrifugal separation, transforming collisions from adhesive collisions to elastic or weakly adhesive collisions, thereby reducing the probability of agglomeration. Based on this, some examples also include: setting up an instantaneous cooling and shaping air curtain zone downstream of the second pressure section and before centrifugal separation. This instantaneous cooling and shaping air curtain zone injects inert gas or recycled cold air at a temperature lower than the hot flue gas temperature into the granulated particles, so that the particle surface temperature rapidly rises across the viscous temperature zone and solidifies into a non-viscous state before entering the centrifugal separation, thereby suppressing secondary adhesion and agglomeration of particles during turbulent transport.

[0080] For example, a rapid cooling and shaping zone is set up between the downstream of the second air pressure section and the centrifugal separation inlet. The shaping zone is equipped with annular air curtain nozzles, which inject lower-temperature inert gas or recovered cold air. The air curtain forms a short-path cooling channel with a large volumetric flow rate, allowing the particle surface to cool and solidify in a very short time. To avoid excessive heat recovery loss due to overcooling, the low-temperature hot air recovered by the system or the cold air obtained by heat exchange from purified medium-temperature flue gas can be preferentially used as the air curtain medium. The spray angle of the shaping air curtain can be designed as an enveloping or tangential type, causing the particles to tumble within the air curtain and improving cooling uniformity. If the proportion of agglomerates increases or the particle temperature at the separator inlet is too high, the air curtain flow rate can be increased or the air curtain medium temperature can be decreased to enhance the shaping effect. This scheme can reduce the formation of large agglomerates, reduce adhesion and accumulation on the separator inner wall and filter cartridge area, thereby reducing the rate of pressure rise and extending the continuous operation cycle. For example, in high-alumina or high-slag-viscosity operating conditions, common problems include syrupy adhesion at the separator inlet and rapid slag buildup on the filter cartridge surface. After introducing a rapid cooling and shaping air curtain, the particle surface solidifies faster, the slag buildup rate is significantly reduced, the system maintenance interval is lengthened, and the particle size of the moving bed feed is more stable, resulting in reduced steam production fluctuations.

[0081] In some cases, considering abnormal furnace conditions or material fluctuations, molten slag may contain trace amounts of molten metal droplets or high-density heavy phase particles. Their kinetic energy and impact abrasion capacity are far greater than ordinary slag particles. Upon entering the centrifugal separator, they are more strongly flung towards the outer peripheral wall and the windward side of the filter cartridge, causing localized erosion points. Once the spinel coating is eroded, the exposed substrate surface is more prone to adhesion and rapidly expands the blockage area. The separator's durability can be improved by pre-capturing the heavy phase before it enters the filter cartridge and by concentrating erosion on replaceable components. Based on this, some examples also include: a heavy phase trapping chamber located before the silicon carbide ceramic filter cartridge, positioned on the outer periphery of the rotating flow field and featuring wear-resistant settling grooves or intercepting rings, to preferentially trap molten metal droplets or heavy phase particles with a density higher than slag particles and discharge them from a separate outlet; and a replaceable wear-resistant inner liner ring installed at the impact-facing position of the silicon carbide ceramic filter cartridge to reduce the risk of heavy phase particles eroding and peeling off the spinel coating.

[0082] For example, a heavy phase collection chamber is set on the outer periphery of the cyclone generation section at the separator inlet. This chamber is connected to the main flow channel but has an independent settling tank or intercepting ring structure. This allows high-density particles to preferentially enter the collection chamber under the inertial action of the cyclone's outer periphery and settle into the slag hopper, from which they are periodically discharged through an independent outlet. For particles that may still impact the filter cartridge, a replaceable wear-resistant inner liner or wear-resistant liner plate is installed at the impact point of the filter cartridge. The material can be wear-resistant ceramic or wear-resistant alloy, ensuring that erosion first occurs on low-cost, easily replaceable components. A backflow prevention baffle can be installed between the collection chamber outlet and the main flow channel to prevent particles in the collection chamber from being carried back into the main flow. This solution can significantly reduce the probability of localized erosion and coating peeling of the filter cartridge, resulting in a more stable pressure differential, longer lifespan, and reduced unplanned downtime due to filter cartridge failure. When a small amount of metal entrainment occurs in the furnace, traditional systems often experience localized pressure differences in the filter cartridge in a certain direction and rapid aggravation of slag buildup within a few days. After adopting the heavy phase collection chamber, heavy phase particles are isolated in advance, and the wear on the windward side of the filter cartridge is significantly reduced. Maintenance changes from sudden replacement to planned replacement of the replaceable lining.

[0083] In some cases, the high heat transfer coefficient of fluidized beds stems from the continuous scouring and contact of particles with the heat exchange surface, but this also brings long-term wear risks. Finned structures, due to their sharp geometric angles and large scouring area, are more prone to thinning and even perforation; initial micro-leakage is often difficult to detect, manifesting as a slow decrease in hot air outlet temperature or abnormal bed pressure difference, easily misdiagnosed as bed segregation. Reliability can be improved from three aspects: reducing wear intensity, changing the location of wear occurrence, and identifying micro-leakage signs. Based on this, in some examples, a wear-resistant protective structure is provided on the outer surface of the finned tube bundle, which is a replaceable ceramic sheath or a ceramic micro-bump array; and the heat exchange bed is set as a composite bed, with the upper layer being quartz sand and the lower layer being a slow-wearing bed material with a lower hardness than quartz sand, to reduce the scouring wear of the finned tube bundle by the bed material; and early leakage identification points are set on the hot air side or bed pressure difference side of the fluidized quartz sand heat exchanger to output early warning information when micro-leaking occurs in the finned tube bundle.

[0084] For example, a wear-resistant protective structure can be provided on the outer surface of the finned tube bundle, such as a replaceable ceramic sheath or a ceramic micro-bump array sintered on the fin surface, so that actual contact wear occurs in the wear-resistant layer rather than the metal substrate. Simultaneously, the bed is designed as a composite bed, with the upper layer still composed of quartz sand to ensure heat exchange capacity, and the lower layer using a slow-wearing material with a lower hardness than quartz sand to reduce wear intensity on the lower part of the tube bundle and the area near the air distribution plate. Multi-zone air distribution maintains stable fluidization of the bed. For micro-leak detection, pressure perturbation monitoring or acoustic monitoring points can be set on the hot air side to capture characteristic noise changes or pressure fluctuations caused by micro-leaks. These changes, combined with variations in hot air dust content and oxygen content, are used for comprehensive judgment, providing early warning before perforation develops into a significant leak. This solution can extend the life of the heat exchange tube bundle and reduce downtime caused by sudden leaks, while improving the diagnosability of chronic wear faults. Traditional fluidized beds are prone to fin root wear and hot air outlet temperature drop after six months to a year of operation. With the use of wear-resistant sheaths and composite bed layers, the wear rate is reduced and the hot air temperature decays more slowly. With the help of micro-leakage identification points, abnormalities can be detected before the temperature drops significantly, and measures such as load reduction, switching to standby heat exchangers, or replacing local sheaths can be taken to prevent bed conditions from collapsing.

[0085] In some cases, considering that moving bed heat exchange relies on the continuous tumbling and rolling of slag particles to maintain porosity and renew the heat exchange contact surface, some slag may soften and form sintering bridges at local high-temperature points. Once sintering bridges are formed, conventional single-frequency vibration may not be able to destroy their structure, leading to arching of the slag layer, material channelization, and shielding of the heat exchange surface, resulting in a sudden drop in steam production. The role of frequency sweeping excitation is to subject the bed to a frequency change, forcing sintered structures of different sizes and stiffnesses into the resonant response zone, making them easier to destroy; the isolation particles are used to reduce the probability of direct adhesion between particles in hot spots. Based on this, in some examples, the excitation methods of the vibrating bed include fundamental frequency excitation and frequency sweeping excitation. The frequency sweeping excitation changes the excitation frequency within a preset frequency band within a preset time interval to destroy the sintering bridge structure in the slag layer; and segmented temperature monitoring points are set in the bed layer of the vibrating bed. When a local hot spot is detected, inert isolation particles are added to the hot spot area to reduce the probability of direct contact between slag particles forming sintering bridges, thereby suppressing channelization and stabilizing steam production.

[0086] For example, in addition to conventional fundamental frequency vibration, the vibrating bed periodically performs frequency sweep excitation. The frequency sweep parameters can be set by the frequency converter of the vibrating motor, allowing the excitation frequency to vary within a preset frequency band and remain for a period of time. Simultaneously, segmented temperature monitoring points are set within the bed to identify local hot spots. When the hot spot temperature exceeds a threshold or the steam production rate decreases abnormally, inert isolation particles, such as fine-grained silica sand or inert ceramic microspheres, are added to the hot spot area through the bed feeding port. These particles fill the spaces between the slag particles, forming an isolation interface and reducing the probability of direct contact between slag particles and the formation of sintering bridges. To prevent the isolation particles from affecting the quality of downstream slag products, the dosage can be controlled, and a screening or recycling device can be installed at the end of the bed to recycle the isolation particles. This solution can significantly reduce sudden channeling, improve steam production stability, and reduce the number of shutdowns for cleaning due to sintering. If local hot spots and arch bridges occur in the short time that high-temperature slag enters the initial stage of the moving bed, conventional solutions require shutdown and clearing. After adopting frequency sweeping excitation, the arch bridge structure is more easily destroyed, and the addition of isolation particles further suppresses recurrence, enabling the moving bed to restore uniform feeding and stable heat exchange without shutting down, and the steam flow rate recovers and remains stable.

[0087] In some cases, considering the large specific surface area and high surface energy of nano-calcium-based materials, they are more prone to forming highly viscous filter cakes after being injected into the flue gas. This is especially true when the flue gas has high moisture content or the temperature is within certain adhesion-sensitive windows, causing the filter cake to rapidly densify, leading to a rapid increase in the bag filter pressure differential and a deterioration in the dust removal effect. High reactivity can be confined to the reaction section, while good filterability can be confined to the dust removal section, allowing the material to exhibit different particle states or surface properties at different temperature zones. Based on this, in some examples, the nano-calcium-based desulfurizer is set as a temperature-triggered depolymerizable powder. When the temperature is higher than the preset depolymerization temperature, the nano-calcium-based desulfurizer depolymerizes into nano-sized particles to participate in the desulfurization reaction, and forms controllable micron-sized clusters near the bag filter inlet temperature range to reduce filter cake adhesion. Alternatively, a drying and mixing section is set after the nano-calcium-based desulfurizer is injected. This section introduces recovered hot air to control the moisture content of the hot flue gas within a range that makes it difficult to form a highly viscous filter cake.

[0088] For example, the first implementation involves designing the nano-calcium-based desulfurizer as a temperature-triggered deagglomerating powder. After entering the flue gas duct at high temperatures, the powder undergoes thermally triggered changes in its surface coating or structure, dispersing into nano-sized particles to participate in the absorption reaction. As the flue gas cools further and approaches the inlet temperature zone of the filter bag, the powder reforms into controllable micron-sized clusters, making the filter cake more porous and less adhesive. The second implementation involves setting up a drying and mixing section after the calcium spraying point. This section introduces recovered hot air to dry and enhance the mixing of the local flue gas, controlling the moisture content and dew point of the flue gas, and reducing the probability of the nano-powder forming adhesive bridging on the filter bag surface. The drying and mixing section can employ a static mixer structure to ensure more uniform powder distribution and prevent excessive local calcium spraying that could cause abnormal thickening of the filter cake. This solution can maintain desulfurization efficiency while slowing down the rate of increase in filter bag pressure differential, extending the cleaning cycle, and reducing fan energy consumption. In winter or when the raw material has a high moisture content, conventional nano-calcium spraying can cause the pressure difference of the filter bag to rise rapidly in a short period of time. After introducing the drying and mixing section, the moisture window of the flue gas is controlled, the filter cake is looser, and the pressure difference increases more slowly. If temperature-triggered deagglomeration powder is used, the high-temperature section still maintains high calcium utilization, and the filter bag section exhibits a particle morphology that is easier to clean, thereby improving the long-term stable operation capability.

[0089] In some cases, when the flue gas temperature is below 300℃ and the moving bed and fluidized bed are connected in parallel, although this can prevent the flue gas from being further cooled to an unfavorable purification window in a series system, the parallel connection will distribute the heat exchange load, and the moving bed side may experience insufficient steam pressure or flow, resulting in the recovered energy meeting the standards but being unusable. The sand-heat buffer loop utilizes the heat capacity and transportability of quartz sand to temporarily store the gas phase heat in the high-temperature bed material, and then transfer the bed material heat to the moving bed inlet area, thereby maintaining the energy supply intensity at the steam end even when the flue gas temperature is relatively low. Based on this, in some examples, the following is also included: when the heat exchange of the vibrating bed and the fluidized bed quartz sand are adjusted to be in parallel, a sand-heat buffer loop is established. The sand-heat buffer loop includes extracting high-temperature quartz sand from the fluidized bed quartz sand heat exchanger and sending it to the upstream heat exchange zone of the vibrating bed via dense phase conveying, so as to provide a supplementary heat source for the vibrating bed and maintain the pressure or flow rate of saturated steam at a preset lower limit. After the high-temperature quartz sand completes its heat release, it is returned to the bed layer of the fluidized bed quartz sand heat exchanger for recycling.

[0090] For example, in parallel operation mode, a portion of high-temperature quartz sand is extracted from the fluidized bed and fed into the inlet section or high-temperature heat exchange zone of the moving bed via a dense-phase conveying device. This allows the high-temperature quartz sand and high-temperature slag particles to participate in the heat transfer of the heat exchange tube bundle, enhancing the heat exchange driving force in the initial stage of the moving bed. After the quartz sand releases heat and its temperature decreases, it returns to the fluidized bed through the sand return pipeline to continue being heated by the hot flue gas. To prevent quartz sand from entering the slag product and affecting its quality, a screening section can be set at the end of the moving bed, or separation and recovery can be performed using particle size differences, allowing the quartz sand to be recycled. The sand extraction and return rates of the sand-heat buffer loop can be set according to the lower limit requirements of steam pressure or flow rate, ensuring that the moving bed can still produce saturated steam that meets the user's needs under low-temperature flue gas conditions. This scheme maintains the steam-side power supply capacity under low-temperature flue gas conditions while keeping the flue gas within a suitable medium-temperature window for calcium injection and bag filters. When the furnace load is reduced, the flue gas temperature drops. Traditional systems would sacrifice steam production to ensure purification temperature. After introducing the sand heat buffer circuit, the fluidized bed can still extract heat from the flue gas and transfer it to the moving bed through the bed material, so that the steam pressure is kept above the preset lower limit. The steam-using equipment in the plant will not fluctuate frequently or be shut down due to fluctuating flue gas temperature.

[0091] In some cases, considering Transient peak values ​​are often related to raw material fluctuations, changes in blast airflow, or changes in the reaction stage within the furnace; temperature signals do not necessarily change synchronously. Controlling calcium injection solely based on temperature thresholds may result in reaction lag, leading to short-term exceedances. The rising rate, acting as a trigger signal, can identify the emerging peak earlier and increase the reactant concentration and gas-solid contact probability in a short time through pulse injection. Simultaneously, adjusting the split ratio of the parallel heat exchange increases the reaction residence time, significantly enhancing the desulfurization capacity during the peak phase. Based on this, some examples further include: installing a sulfur dioxide concentration detection device at the hot flue gas purification inlet and calculating the sulfur dioxide rising rate; when the sulfur dioxide rising rate exceeds a preset threshold, triggering a pulse injection mode to inject the nano-calcium-based desulfurizer into the hot flue gas, and simultaneously adjusting the split ratio under the parallel relationship to increase the desulfurization reaction residence time; switching to a steady-state injection mode after the sulfur dioxide rising rate recovers below the threshold.

[0092] For example, arranged at the purification entrance Concentration detection device, and calculation in the control system. The concentration increases at a rate over time; when the rate of increase exceeds a threshold, the calcium injection system switches to pulse injection mode. Pulse injection combines short-duration high-volume injection with intermittent injection to create a more uniform calcium concentration distribution across the flue cross-section and avoid long-term excessive addition. Simultaneously, if the system is in parallel heat exchange mode, the opening of the diversion valve can be temporarily adjusted to allow more flue gas to enter the purification front channel with a longer residence time or more thorough gas-solid mixing, thereby increasing the reaction time. After the peak value passes and the rate of increase returns to below the threshold, the calcium injection switches back to steady-state injection and restores the economical diversion ratio. This scheme can reduce the risk of transient peak exceeding the standard and improve the reliability of compliance without a significant increase in the average dosage. For example, when fluctuations in the sulfur content of the raw material lead to… During rapid rises within minutes, traditional temperature control may not be sufficient to increase the calcium spraying rate. By employing rise rate triggering, the system enters pulse spraying early in the peak formation phase and temporarily increases the residence time, thus flattening the peak and improving the bag outlet. The concentration is more stable, reducing emissions penalties or production downtime caused by occasional peaks.

[0093] In some cases, while spinel coatings can reduce adhesion, microcracks can appear in the coating under the thermal and mechanical shocks of high-temperature fluctuations and pulse backflushing. Increased roughness in the microcracked region makes it easier for slag particles to become mechanically embedded, gradually forming adhesion nuclei and expanding into a slag-laden layer, ultimately leading to localized blockage and pressure drift in the filter cartridge. Gradient structure coatings alleviate thermal stress mismatch by introducing a tougher transition layer near the substrate, while maintaining the high-temperature chemical stability of the anti-adhesion surface layer on the surface side. Segmented, incremental backflushing pressure reduces crack propagation caused by a single strong impact by altering the load spectrum. Based on this, in some examples, the spinel coating is a gradient structure coating, comprising a tough transition layer near the silicon carbide ceramic filter cartridge substrate and an anti-adhesion surface layer on the outer side. Furthermore, the pulse backflushing employs a segmented, incremental backflushing pressure strategy, first using a low backflushing pressure to remove filter cake adhesion from the filter cartridge surface, and then using a high backflushing pressure to clean the filter cartridge micropores, thereby reducing the probability of microcrack propagation in the coating under thermal and mechanical shocks.

[0094] For example, a gradient-structured spinel coating is prepared on the inner wall of a silicon carbide filter cartridge. The layer closest to the substrate is a tough transition layer with a composition and coefficient of thermal expansion closer to silicon carbide to reduce interfacial shear stress; the outer layer is an anti-adhesion surface layer, providing low wetting and low adhesion surface characteristics. Regarding the backflushing strategy, a lower backflushing pressure is first used to loosen and peel the filter cake from the filter cartridge surface. Once the filter cake adhesion decreases, a higher backflushing pressure is switched to clean the micropores, ensuring the micropore cleaning effect is not affected but reducing the peak impact load. Simultaneously, the health status of the filter cartridge can be assessed by monitoring the pressure difference recovery before and after backflushing. When the recovery amount continuously decreases, it indicates possible microcrack propagation in the coating or localized slag buildup, requiring maintenance or replacement. This approach can reduce the generation and propagation rate of coating microcracks, delay slag nuclei formation, stabilize the filter cartridge pressure difference over a long period, and reduce backflushing frequency and energy consumption. In operating conditions with large fluctuations in high-temperature flue gas, traditional fixed high-pressure backflushing is prone to local coating peeling and rapid slagging within a few weeks. With gradient coating and segmented incremental backflushing, the coating is more resistant to thermal shock, slagging develops more slowly, the service life of the filter cartridge is significantly extended, and the system is easier to maintain long-term stable operation.

[0095] The above describes the hot air treatment and heat recovery method for liquid slag in the embodiments of this application. The following describes the hot air treatment and heat recovery system for liquid slag in the embodiments of this application.

[0096] Please see Figure 2 One embodiment of the hot air treatment and heat recovery system for liquid slag described in this application may include:

[0097] The gradient air quenching granulation unit 201 is used to perform gradient air quenching granulation treatment on uniformly falling slag liquid so that the slag liquid first passes through a first air pressure section and then passes through a second air pressure section, wherein the air pressure of the first air pressure section is lower than the air pressure of the second air pressure section.

[0098] The slag thermal separation unit 202 is used to centrifuge the molten slag from the gradient wind quenching and granulation treatment to obtain slag particles and hot flue gas.

[0099] The heat exchange unit 203 is used to turn the slag particles over and convert heat through the vibrating bed, and to exchange the hot flue gas with fluidized quartz sand connected in series with the vibrating bed. The hot steam and hot air generated during the heat exchange process are recovered and reused, and the hot flue gas generated during the treatment process is purified.

[0100] For example, the liquid slag hot air treatment and heat recovery system is composed of a gradient air quenching granulation unit 201, a slag heat separation unit 202, and a heat exchange unit 203 connected sequentially along the process flow direction. The gradient air quenching granulation unit 201 is located inside the granulation tower and employs a dual-zone pressure differential structure. The upper first air pressure section is a low-pressure spray gun area arranged around the slag liquid falling channel. Multiple air outlets are inclined at approximately 30° towards the falling slag liquid to form a tangential shearing and coating effect, thereby delaying the slag liquid's descent and extending the crushing time to approximately 0.8 seconds. The air pressure in the first air pressure section is 0.2 MPa to 0.4 MPa to pre-atomize the molten slag into droplets. The lower second air pressure section is a high-pressure spray gun area arranged around the slag liquid with the spray direction perpendicular to the slag liquid falling direction. The air pressure in the second air pressure section is 0.6 MPa. The pressure is between 1.0 MPa and 1.0 MPa, with a pressure difference greater than or equal to 0.3 MPa from the first pressure section. This pressure is used to perform secondary crushing of the droplets through positive collision to force the formation of a 1 mm to 3 mm particle size distribution, accounting for more than 85% and increasing the vitreous content to more than 92%. This results in the output of a hot flue gas mixture carrying slag particles into the downstream section. The slag thermal separation unit 202 includes a vortex guide plate and a silicon carbide ceramic filter cartridge. The vortex guide plate forces the airflow to rotate within the separation chamber at a speed of 500 rpm to 800 rpm, causing the slag particles to impact the filter cartridge wall under centrifugal force and fall for collection. Meanwhile, the hot air passes through the micropores of the filter cartridge, with a pore size of approximately 10 μm, and is output as hot flue gas, thereby achieving a separation efficiency greater than 97%. The inner wall surface of the silicon carbide ceramic filter cartridge is laser-clad. Anti-adhesion spinel coating and can be made with 70wt% MgO, 25wt% and 5wt% The proportions are adjusted to suppress the adhesion and clogging of high-temperature fine particles, and compressed nitrogen pulse backflushing is configured for anti-clogging, for example, backflushing for 0.1 seconds per flush and backflushing pressure of 0.5 MPa; the heat exchange unit 203 includes a moving bed vibrating bed heat exchanger for solid-phase sensible heat recovery and a fluidized bed quartz sand heat exchanger for gas-phase sensible heat recovery. The moving bed heat exchanger adopts a 30° inclined heat-resistant steel tank lined with silicon carbide, and has built-in Inconel 625 heat exchange tube bundles. The slag particles enter at an inlet of about 800° and are evenly spread by the vibrating feed bed to form 0.3 The slag layer thickness ranges from m to 0.5 m. The slag particles flow downwards within the bed and tumble 3 to 5 times under vibration to refresh the heat transfer interface, allowing for counter-current heat exchange with water or steam within the tube bundle and cooling the slag particles to approximately 150°C. Simultaneously, approximately 0.8 MPa of saturated steam is produced. The heat exchange area of ​​the heat tube bundle can be configured to 0.8 m² / ton slag·h, with a heat transfer coefficient reaching 180 W / (m²·K). For anti-clogging and ash removal, an inter-tube inserted sonic horn at a frequency of 150 Hz is used in conjunction with nitrogen pulse jets at 0.5 MPa at 10-minute intervals. When the current of the vibrating motor exceeds 110%, 0.1mm quartz sand is injected as a fluidizing agent, and the amplitude is automatically adjusted to the maximum value to suppress slag layer caking. The fluidized bed quartz sand heat exchanger consists of an air distribution plate and a quartz sand bed, with finned tube bundles arranged on the upper part of the bed. The quartz sand bed can use a particle size of 0.5mm, or 0.3mm to 0.8mm. 20℃ cold air is blown in from the bottom and passes through the air distribution plate, which has a gradient open structure treated with 310S stainless steel aluminized, with a central area pore diameter of 1.5mm and an opening rate of 8%, and an edge area pore diameter of 2mm. With a diameter of 5mm and an opening rate of 15%, the quartz sand particles are lifted to form a fluidized, highly mixed bed. Hot flue gas passes through the bed, releasing heat to the quartz sand and transforming into lower-temperature medium-temperature flue gas. Meanwhile, the heated high-temperature quartz sand continuously washes over the outer surface of the finned tube bundle during the tumbling and mixing process, transferring heat to it. This causes the cold air inside the finned tube bundle to be heated and output as high-temperature hot air at approximately 450℃. The finned tube bundle can be made of SA213T12 alloy steel, with spiral serrated fins of 12mm height, staggered arrangement, and a tube spacing of 80mm. The fin surface is laser-clad. The coating allows for a total heat exchange area of ​​1.2 m² / ton of slag. A bed material circulation system is included, with a cyclone separator recovering and returning fine sand. The bed material quantity can be organized according to a slag-to-sand ratio of 1:3. Multi-zone air distribution, such as six independent air chambers in the air distribution plate, adjusts the airflow based on pressure difference feedback to ensure a bed density difference of less than 5%. Built-in guide ribs and 45° inclined guide vanes suppress segregation and large bubble merging. In collaborative control, the fluidized bed airflow is automatically increased when the slag temperature at the moving bed outlet exceeds 300°C to ensure continuous operation. Furthermore, the system includes a dry purification unit connected to the heat exchange unit outlet to purify the hot flue gas generated during treatment. When the hot flue gas temperature exceeds 350°C, nano-injection is applied to the hot flue gas. After the calcium-based desulfurizing agent is applied, bag filter dust collection is performed. When the temperature of the hot flue gas is below 300℃, the heat exchange between the series-connected vibrating bed and the fluidized bed quartz sand is adjusted to parallel flow to reduce the heat exchange intensity of the single path and stabilize the purification inlet temperature window. The medium-temperature desulfurization reaction tower can adopt a multi-stage cyclone calcium spraying device and a guide grid is installed in the tower to extend the residence time to about 8 seconds. It can achieve a desulfurization rate of more than 95% under flue gas conditions of about 300℃. The bag filter dust collector can use P84 high-temperature resistant fiber filter bags and make the emission concentration less than 10mg / Nm³, thereby achieving the systematic and coordinated goal of converting the sensible heat of slag particles into saturated steam, converting the sensible heat of hot flue gas into high-temperature hot air, and achieving stable emission standards for flue gas.

[0101] In some examples, a controller is also included for:

[0102] Based on the obtained slag liquid temperature and hot flue gas temperature;

[0103] The wind pressure is dynamically adjusted based on the temperature of the slag liquid, and / or, when the temperature of the hot flue gas is higher than 350°C, a nano-calcium-based desulfurizing agent is injected into the hot flue gas, followed by bag filter dust collection; when the temperature of the hot flue gas is lower than 300°C, the series-connected vibrating bed heat exchanger and fluidized bed quartz sand heat exchanger are adjusted to a parallel relationship.

[0104] In some examples, the controller is also used for:

[0105] Controlled periodic backflushing of the slag thermal separation unit and / or heat exchange unit with compressed nitrogen; and / or,

[0106] Control the acoustic horn to perform anti-clogging operation on the slag heat separation unit and / or heat exchange unit.

[0107] above Figure 2 The controller of the liquid slag hot air treatment and heat recovery system in this application embodiment has been described from the perspective of modular functional entities. The controller of the liquid slag hot air treatment and heat recovery system in this application embodiment will now be described in detail from the perspective of hardware processing. Please refer to... Figure 3One embodiment of the controller 300 for the liquid slag hot air treatment and heat recovery system in this application includes:

[0108] The system includes an input device 301, an output device 302, a processor 303, and a memory 304, wherein the number of processors 303 can be one or more. Figure 3 Taking a processor 303 as an example. In some embodiments of this application, the input device 301, output device 302, processor 303, and memory 304 can be connected via a bus or other means, wherein... Figure 3 Taking the example of a connection between China and Israel via a bus.

[0109] Specifically, the processor 303 executes the functional steps of the controller by calling the operation instructions stored in the memory 304.

[0110] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for hot air treatment and heat recovery of liquid slag, characterized in that, include: The uniformly falling slag liquid is subjected to gradient air quenching and granulation treatment so that the slag liquid first passes through a first air pressure section and then through a second air pressure section. The first air pressure section is a low-pressure spray gun area arranged around the slag liquid falling channel and the air outlet direction is towards the falling slag liquid at a preset angle to form a tangential shearing and coating effect. The second air pressure section is a high-pressure spray gun area arranged around the slag liquid and the spray direction is perpendicular to the falling direction of the slag liquid. The air pressure of the first air pressure section is 0.2MPa to 0.4MPa, and the air pressure of the second air pressure section is 0.6MPa to 1.0MPa. The air pressure of the first air pressure section is lower than the air pressure of the second air pressure section, and the air pressure difference between the first air pressure section and the second air pressure section is greater than or equal to 0.3MPa. The molten slag treated by gradient wind quenching and granulation is centrifuged to obtain slag particles and hot flue gas. The hot flue gas mixture carrying slag particles formed after gradient wind quenching and granulation is introduced into the slag thermal separation unit. The airflow is forced to rotate in the separation chamber by using a vortex guide plate, so that the slag particles impact the separation component under the action of centrifugal force and fall for collection. The hot air is output as hot flue gas through the micropores of the filter cartridge. The separation component is a silicon carbide ceramic filter cartridge. The inner wall of the silicon carbide ceramic filter cartridge is formed with an anti-adhesion spinel coating, and compressed nitrogen pulse backflushing is configured to periodically clean the micropores of the filter cartridge. The slag particles are turned over and heat transferred by the vibrating bed, and the hot flue gas is heat exchanged through the fluidized quartz sand connected in series with the vibrating bed. The hot steam and hot air generated during the heat exchange process are recovered and reused. The hot flue gas generated during the process is purified. When the temperature of the hot flue gas is higher than 350°C, a nano-calcium-based desulfurizing agent is injected into the hot flue gas and bag filter dust is used. When the temperature of the hot flue gas is lower than 300°C, the heat exchange between the vibrating bed and the fluidized bed quartz sand is changed from a series connection to a parallel connection.

2. The method according to claim 1, characterized in that, The vibrating bed is inclined, and the slag particles are subjected to heat transfer via the vibrating bed, including: The slag particles are tumbled and rolled from top to bottom on the vibrating bed, exchanging heat with water or steam in the heat exchange tube bundle of the vibrating bed to produce saturated steam.

3. The method according to claim 1, characterized in that, The quartz sand forms a heat exchange bed, and finned tube bundles are arranged on the heat exchange bed. The hot flue gas undergoes heat exchange through the fluidized quartz sand, including: The cold air blown into the bottom of the heat exchange bed lifts up the quartz sand particles in the bed, thereby fluidizing the quartz sand. The hot flue gas is converted into medium-temperature flue gas with a lower temperature by heat exchange through quartz sand. The high-temperature quartz sand after heat exchange is then converted into high-temperature hot air by heat exchange through cold air in the finned tube bundle.

4. The method according to claim 1, characterized in that, The purification of the hot flue gas generated during the processing includes: right Ball milling was performed, during which 0.1 wt% carbon nanotubes were added. The particles are ball-milled to D50 = 0.8 μm to make them... The specific surface area of ​​the particles is greater than or equal to 25 m² / g; Add 1wt% The nano-calcium-based desulfurizer is obtained by mixing.

5. The method according to claim 1, characterized in that, The spinel coating comprises 70 wt% MgO and 25 wt% [unclear - possibly a specific component or ingredient]. And 5wt% .

6. A hot air treatment and heat recovery system for liquid slag, characterized in that, The system, employing the method as described in any one of claims 1 to 5, comprises: The gradient air quenching granulation unit is used to perform gradient air quenching granulation treatment on uniformly falling slag liquid so that the slag liquid first passes through a first air pressure section and then through a second air pressure section, wherein the air pressure of the first air pressure section is lower than the air pressure of the second air pressure section. The slag thermal separation unit is used to centrifuge the molten slag from the gradient wind quenching and granulation process to obtain slag particles and hot flue gas. The heat exchange unit is used to turn the slag particles over and convert heat through the vibrating bed, and the hot flue gas is heat exchanged through the fluidized bed quartz sand connected in series with the vibrating bed. The hot steam and hot air generated during the heat exchange process are recovered and reused, and the hot flue gas generated during the treatment process is purified.

7. The system according to claim 6, characterized in that, Also includes: Controller, used for: Based on the obtained slag liquid temperature and hot flue gas temperature; The wind pressure is dynamically adjusted based on the temperature of the slag liquid, and / or, when the temperature of the hot flue gas is higher than 350°C, a nano-calcium-based desulfurizing agent is injected into the hot flue gas, followed by bag filter dust collection; when the temperature of the hot flue gas is lower than 300°C, the series-connected vibrating bed heat exchanger and fluidized bed quartz sand heat exchanger are adjusted to a parallel relationship.

8. The system according to claim 7, characterized in that, The controller is also used for: Controlled periodic backflushing of the slag thermal separation unit and / or heat exchange unit with compressed nitrogen; and / or, Control the acoustic horn to perform anti-clogging operation on the slag heat separation unit and / or heat exchange unit.

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