A cooling and heat exchange system for high-temperature slag centrifugal granulation waste heat recovery

Abstract

The application discloses a cooling and heat exchanging system for high-temperature molten slag centrifugal granulation waste heat recovery, which comprises a granulation bin and a moving bed; the top of the granulation bin is provided with a cold wall structure; the top of the granulation bin is provided with a hot air outlet; the center of the granulation bin is provided with a granulator, and the edge of the granulator is provided with edge air; the side wall of the granulation bin is provided with a cold wall structure; the side wall of the granulation bin is provided with side wall air above; the lower part of the granulation bin is provided with a vertical heat exchanging surface; the upper part of the moving bed is provided with a cooling pipe bundle; the dense phase zone of the moving bed is provided with a cooling buried pipe; and the bottom of the moving bed is provided with a wind distribution device. The application can effectively recover the heat of high-temperature molten slag.

Description

Technical Field

[0001] This invention belongs to the field of slag granulation and waste heat recovery technology, specifically relating to a cooling heat exchange system for waste heat recovery from centrifugal slag granulation at high temperatures. Background Technology

[0002] Blast furnace slag is a solid waste generated during the iron and steel smelting process. Its discharge temperature is 1400–1550℃, and each ton of blast furnace slag carries approximately 1770 MJ of heat energy, equivalent to 60 kg of standard coal, indicating significant potential for heat recovery. Traditional blast furnace slag treatment mainly employs water quenching, which suffers from drawbacks such as high water consumption, generation of polluting gases like SO2 and H2S, and waste of substantial amounts of waste heat. Energy conservation and emission reduction are urgently needed in the steel industry, and dry slag granulation and waste heat recovery technologies have gained significant attention within the sector.

[0003] Dry slag granulation and waste heat recovery technology is a treatment method that rapidly breaks down and solidifies liquid slag into small particles with minimal water consumption, and utilizes air as a heat storage medium to fully contact and exchange heat with the slag particles, thereby recovering waste heat. Among these methods, centrifugal granulation is the most promising slag treatment method due to its advantages of low energy consumption, good granulation effect, simple and compact equipment, and controllable particle size and morphology.

[0004] Currently, most devices used in research on dry centrifugal granulation and waste heat recovery processes combine a granulation chamber with a traditional moving bed for heat exchange, using air as the main heat exchange medium. This approach suffers from problems such as low waste heat recovery efficiency and low glass conversion rate. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a cooling heat exchange system for waste heat recovery from centrifugal granulation of high-temperature molten slag, which addresses the shortcomings of the prior art and solves the technical problem of efficient heat recovery after centrifugal granulation of molten slag.

[0006] The present invention adopts the following technical solution:

[0007] A cooling and heat exchange system for recovering waste heat from centrifugal granulation of high-temperature molten slag includes a moving bed, a granulation chamber above the moving bed, a cold wall structure and a hot air outlet at the top of the granulation chamber, a granulator at the center inside the granulation chamber, an edge air device at the edge of the granulator, a vertical heat exchange surface at the bottom of the granulation chamber, a cooling tube bundle at the top of the moving bed, cooling buried pipes in the dense phase zone of the moving bed, an air distribution device at the bottom of the moving bed, and side cold walls on the side walls of both the granulation chamber and the moving bed, with side wall air devices corresponding to the granulation chamber on the upper side cold walls.

[0008] Specifically, the top of the granulation chamber has a circular structure, and the cold wall structure is a coil arranged in a ring on the top of the granulation chamber.

[0009] Specifically, the top of the granulation chamber has a rectangular structure, and the cold wall structure is a membrane wall, which is arranged in a polygonal structure on the top of the granulation chamber.

[0010] Specifically, the inlets of the edge air device are evenly distributed along the periphery of the granulator, and a continuous air outlet or multi-point air outlet is adopted.

[0011] Specifically, the sidewall air device has multiple injection ports in the circumferential and vertical directions of the granulation bin. The inlets are located above or below the slag particle concentrating impact area, and the airflow directions of adjacent sidewall air inlets at the same height are either in the same or opposite directions.

[0012] Specifically, the vertical heat exchange surface is a screen heat exchanger or a vertical tube bundle, and the tube type of the tube bundle is a bare tube, a finned tube, or a studded tube.

[0013] Specifically, the cooling tube bundles are horizontally arranged on the top of the moving bed, in the form of equilateral triangles, straight rows of squares, staggered rows of squares, or concentric circles.

[0014] Specifically, the side cold walls are membrane wall structures.

[0015] Specifically, the cooling tubes are horizontally arranged in the dense phase zone of the moving bed, and are arranged in equilateral triangles, staggered squares, or concentric circles.

[0016] Specifically, the air distribution device is an air distribution duct or an air distribution panel.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] This invention discloses a cooling and heat exchange system for recovering waste heat from the centrifugal granulation of high-temperature molten slag. The top of the granulation chamber is designed with a cold wall structure for radiative heat exchange with the granulated high-temperature slag droplets. A hot air outlet is provided at the top of the granulation chamber to exhaust the air that has entered the granulation chamber from the moving bed after heat exchange. Edge air is provided at the edge of the granulator, which convects with the granulated slag droplets to promote rapid cooling. Side wall air is arranged above the side wall of the granulation chamber, which convects with the semi-molten slag particles flying to the side wall of the granulation chamber, accelerating the cooling process of the slag particles and preventing excessive temperature at the wall impact point. A vertical heat exchange surface is provided at the bottom of the granulation chamber to enhance radiative heat exchange with the falling high-temperature slag particles. Both the side walls of the granulation chamber and the moving bed are provided with cold wall structures for radiative heat exchange with the falling slag particles. Cooling tube bundles are provided at the top of the moving bed, and the tube bundles are staggered to increase the extended heat exchange surface to achieve efficient heat exchange with the slag particles. Cooling tubes are arranged in the dense phase zone of the moving bed, and the tube bundles are staggered to improve heat exchange efficiency. An air distribution device is installed at the bottom of the moving bed, which sends cooler cooling gas into the moving bed to recover the remaining heat from the slag particles and improve the overall waste heat recovery rate.

[0019] Furthermore, the top of the granulation chamber can be circular or rectangular, which facilitates industrial manufacturing and ensures uniform airflow. When the top of the granulation chamber is circular, a coil can be installed in a ring shape, with a ring-shaped air outlet reserved to ensure uniform airflow; when the top of the granulation chamber is rectangular, a serpentine tube or membrane wall can be installed, with a rectangular air outlet reserved.

[0020] Furthermore, the inlets of the edge air device are evenly distributed along the periphery of the granulator, and a continuous air outlet or multi-point air outlet is used to cool the slag droplets that have just completed granulation.

[0021] Furthermore, the sidewall air device has multiple inlets in the circumferential and vertical directions of the granulation bin. The uniform arrangement of inlets in the circumferential direction can achieve uniform cooling of the slag particles in the granulation bin. The arrangement of inlets with different velocities in the vertical direction can enhance the turbulence in the granulation bin space, improve the heat exchange effect, and promote the dispersion of slag particles. The sidewall air inlets are located above or below the area where slag particles concentrate and collide with the wall, which can reduce the temperature of the collision zone and protect the cold wall structure. The sidewall air directions of adjacent inlets at the same height are in the same or opposite directions. When they are in the same direction, the cooling of slag particles in the granulation bin space is more uniform. When they are in opposite directions, the turbulence at the wall surface can be enhanced and the wall surface can be protected.

[0022] Furthermore, the vertical heat exchange surface is a screen-type heat exchanger or a vertical tube bundle. The tube bundle can be a bare tube, a finned tube, or a nail-headed tube. The vertical heat exchange surface can enhance the radiative heat exchange of slag particles while preventing the accumulation and remelting of high-temperature slag particles. The use of finned tubes or nail-headed tubes can further increase the heat exchange area with slag particles, disperse slag particles, and promote heat exchange.

[0023] Furthermore, the cooling tube bundles are horizontally arranged on the top of the moving bed, in the form of equilateral triangles, staggered squares, or concentric circles. The staggered tube bundles further enhance the heat conduction of the slag particles on the basis of radiative heat exchange.

[0024] Furthermore, the cold walls on the sides of the granulation bin and moving bed are membrane wall structures, which can fully exchange heat with the slag particles in the entire granulation bin and moving bed space, and ensure that the wall temperature does not get too high, thus reducing heat loss from the outside.

[0025] Furthermore, the cooling tubes are horizontally arranged in the dense phase zone of the moving bed, in the form of equilateral triangles, staggered squares, or concentric circles. When the slag particles flow through the dense phase zone of the moving bed, they come into full contact with the cooling tubes for heat exchange. The staggered tube bundles make the heat exchange of the slag particles more uniform.

[0026] Furthermore, the air distribution device is an air distribution pipe or an air distribution plate. By evenly opening holes in the air distribution pipe or air distribution plate, the cooling air can be evenly input to absorb the heat of the low-temperature slag particles.

[0027] In summary, the cooling and heat exchange system for high-temperature molten slag centrifugal granulation waste heat recovery of the present invention fully considers the heat exchange process of molten slag from high-temperature liquid to low-temperature solid state. It adopts a vertical heat exchange surface structure in the high-temperature section and a horizontal heat exchange surface structure in the low-temperature section. Combined with the enhanced heat exchange of air, it improves the overall waste heat recovery rate of the device.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the cooling and heat exchange system for waste heat recovery from centrifugal granulation of high-temperature molten slag according to the present invention.

[0030] The components include: 1. cold wall structure; 2. edge air device; 3. side wall air device; 4. vertical heat exchange surface; 5. cooling tube bundle; 6. side cold wall; 7. cooling embedded pipe; 8. air distribution device; and 9. hot air outlet. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," and "one side," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0035] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0037] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0038] This invention provides a cooling and heat exchange system for recovering waste heat from centrifugal granulation of high-temperature molten slag. The system comprises a granulation chamber with a cold wall structure at the top, a hot air outlet at the top, a granulator at the center, edge airflow at the edge of the granulator, cold wall structures on the side walls, side wall airflow above the side walls, a vertical heat exchange surface at the bottom, a cooling tube bundle at the top of the moving bed, cooling buried pipes in the dense phase zone of the moving bed, and an air distribution device at the bottom of the moving bed. This system effectively recovers heat from the high-temperature molten slag.

[0039] Please see Figure 1 The present invention discloses a cooling and heat exchange system for waste heat recovery from centrifugal granulation of high-temperature molten slag, comprising a granulation chamber, a moving bed, a cold wall structure 1, a hot air outlet 9, an edge air device 2, a side cold wall 6, a side wall air device 3, a vertical heat exchange surface 4, a cooling tube bundle 5, a cooling buried pipe 7, and an air distribution device 8.

[0040] The cold wall structure 1 and the hot air outlet 9 are located at the top of the granulation chamber. A granulator is located at the center of the granulation chamber, and an edge air device 2 is located at the edge of the granulator. A vertical heat exchange surface 4 is located between the bottom of the granulation chamber and the moving bed. A cooling tube bundle 5 is located at the top of the moving bed below the vertical heat exchange surface 4. Cooling buried pipes 7 are located in the dense phase zone of the moving bed. An air distribution device 8 is located at the bottom of the moving bed. Side cold walls 6 are located on the side walls of the granulation chamber and the moving bed. A side wall air device 3 is located on the side cold walls 6 corresponding to the granulation chamber.

[0041] The top of the granulation chamber is circular or rectangular. When the top of the granulation chamber is circular, the cold wall structure 1 adopts a serpentine coil; when the top of the granulation chamber is rectangular, the cold wall structure 1 adopts a rectangular coil or a membrane wall; depending on the shape of the top of the granulation chamber, it is arranged in a ring or polygon, using a coil or membrane wall. The cooling medium inside the cold wall structure 1 is gas, water or organic medium.

[0042] The inlets of the edge air device 2 are evenly distributed along the periphery of the granulator. They adopt a continuous air outlet or multi-point air outlet, and the air outlet direction is slightly deviated from the outer edge of the granulator. This ensures that while promoting the cooling of high-temperature slag particles, it avoids the molten slag filaments that have not yet completed splitting from cooling too quickly and forming slag wool. The gas used by the edge air device 2 is air, water vapor or inert gas.

[0043] The vertical heat exchange surface 4 is used for radiative heat exchange and a small amount of heat conduction when the slag particles fall. The vertical heat exchange surface 4 is a screen-type heat exchanger or a vertical tube bundle. The tube type is a bare tube, finned tube or nail-head tube. The heat exchange medium in the vertical heat exchange surface 4 is gas, water or organic medium.

[0044] The upper part of the moving bed is equipped with a cooling tube bundle 5, which is placed horizontally and arranged in equilateral triangles, straight squares, staggered squares, or concentric circles. The tube types are plain tubes, finned tubes, nail-head tubes, etc. The cooling medium is gas, water, or organic medium. The slag particles collide with the tube bundle here to form a high-intensity solid-solid heat exchange.

[0045] The side cold wall 6 adopts a membrane wall, and gas, water or organic medium is introduced into the tube. Under natural circulation or forced circulation, the heat exchange medium entering the side cold wall 6 first collects into the inlet header, then distributes it to the cooling wall tubes, and finally collects into the outlet header. The cold wall structure 1 can use the same inlet and outlet headers as the side cold wall 6, or it can be set separately.

[0046] A sidewall air device 3 is installed above the sidewall of the granulation bin. The sidewall air device 3 has multiple inlets in the circumferential and vertical directions of the granulation bin. The inlets are located above or below the area where the slag particles are concentrated and collide with the wall. The airflow directions of adjacent inlets are the same or opposite. When they are in the same direction, they form an annular air belt close to the wall. When they are in opposite directions, the airflow collides and forms high-intensity turbulence. Both can enhance the heat exchange between the sidewall air device 3 and the slag particles. The sidewall air device 3 uses air, water vapor or inert gas.

[0047] Cooling tubes 7 are installed in the dense phase zone of the moving bed. The cooling tubes 7 are placed horizontally and arranged in equilateral triangles, straight squares, staggered squares, or concentric circles. The heat exchange medium inside the tubes is gas, water, or organic medium. Slag particles accumulate in this area and flow slowly, exchanging heat in close contact with the cooling tubes 7.

[0048] A cooling device 8 is installed at the bottom of the moving bed. The cooling device 8 is a cooling pipe or a cooling plate. It recovers the remaining heat of the slag particles by convective heat exchange between the input cooling gas and the low-temperature slag particles at the bottom of the moving bed. The cooling gas is air or inert gas.

[0049] The working principle of the cooling heat exchange system for waste heat recovery from centrifugal granulation of high-temperature molten slag according to the present invention is as follows:

[0050] After being centrifuged and granulated, the high-temperature molten slag forms small slag droplets that fly out from the edge of the granulator. At this time, the edge air around the granulator and the granulated slag droplets exchange heat through convection, which promotes their rapid cooling. During the flight, the slag droplets exchange heat through radiation with the cold wall structure of the top and side walls of the granulation chamber, as well as through convection with the air from the moving bed, and gradually cool down to a semi-molten state.

[0051] As the slag particles fly to the wall of the granulation chamber, they undergo convective heat exchange with the side wall air, accelerating the cooling process and preventing excessive temperature at the impact point. After bouncing off the wall, the slag particles pass through the vertical heat exchange surface at the bottom of the granulation chamber, where they undergo radiative heat exchange and a small amount of collisional heat conduction, while simultaneously exchanging heat with the airflow from the moving bed. The slag particles gradually cool into a solid state. After passing through the cooling tube bundle at the top of the moving bed, the temperature of the slag particles decreases further.

[0052] When the slag particles reach the dense phase zone of the moving bed, they slowly move downwards, making full contact with the cooling submerged pipes to conduct heat, and exchanging heat fully with the air coming from below.

[0053] Finally, at the bottom of the moving bed, the temperature of the slag particles has dropped to a low value, and the remaining heat of the slag particles is recovered through convection heat exchange with the cooler gas.

[0054] In summary, the present invention provides a cooling and heat exchange system for waste heat recovery from centrifugal granulation of high-temperature molten slag. This system fully considers the heat exchange characteristics of molten slag from a high-temperature liquid state to a low-temperature solid state. In the high-temperature section, a vertical heat exchange surface structure is adopted to enhance the radiative heat exchange of slag particles while reducing the risk of adhesion. In the low-temperature section, a horizontal heat exchange surface structure is adopted to enhance the thermal conductivity of slag particles. Combined with the convective heat exchange of air, this improves the overall waste heat recovery rate of the device.

[0055] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A cooling heat exchange system for recovering waste heat from centrifugal granulation of high-temperature molten slag, characterized in that, The system includes a moving bed, a granulation chamber above the moving bed, a cold wall structure (1) and a hot air outlet (9) at the top of the granulation chamber, the top of the granulation chamber being a circular or rectangular structure, the cold wall structure (1) being a coil or membrane wall, the coil being arranged in a ring at the top of the granulation chamber, the membrane wall being arranged in a polygonal structure at the top of the granulation chamber, a granulator being set at the center inside the granulation chamber, an edge air device (2) being set at the edge of the granulator, the inlet of the edge air device (2) being evenly distributed along the periphery of the granulator, and using a continuous air outlet or multi-point air outlet, a vertical heat exchange surface (4) being set at the bottom of the granulation chamber, the vertical heat exchange surface (4) being a screen heat exchanger or a vertical tube bundle, the tube bundle being a bare tube, finned tube or nail head tube, and a cooling pipe being set at the top of the moving bed. The cooling tube bundle (5) is horizontally set on the top of the moving bed, and the arrangement is equilateral triangle, square in a straight line, square staggered or concentric circle. Cooling buried tubes (7) are set in the dense phase zone of the moving bed. Cooling buried tubes (7) are horizontally set in the dense phase zone of the moving bed, and the arrangement is equilateral triangle, square staggered or concentric circle. Air distribution device (8) is set at the bottom of the moving bed. Side cold walls (6) are set on the side walls of the granulation bin and the moving bed. Side wall air device (3) is set on the side cold walls (6) corresponding to the granulation bin. Side wall air device (3) has multiple injection ports in the circumferential and vertical directions of the granulation bin. The inlet is located above or below the slag particle concentrated impact wall area. The air direction of adjacent side wall air inlets at the same height is the same or opposite.

2. The cooling and heat exchange system for waste heat recovery from high-temperature molten slag centrifugal granulation according to claim 1, characterized in that, The side cold wall (6) is a membrane wall structure.

3. The cooling and heat exchange system for waste heat recovery from centrifugal granulation of high-temperature molten slag according to claim 1, characterized in that, The air distribution device (8) is an air distribution duct or air distribution plate.

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