Self-sieving molten slag dry granulation waste heat recovery device

Abstract

The application discloses a self-screening molten slag dry granulation waste heat recovery device, which comprises a centrifugal granulator, a granulation bin body, a molten slag conveying pipe, a screening structure and a side wall heat exchange device, the centrifugal granulator is arranged in the granulation bin body, the molten slag conveying pipe is used for conveying high-temperature molten slag into the centrifugal granulator, the screening structure can generate upward cooling air, a middle part of the screening structure is provided with a granulation bin outlet which is in communication with the outside, a plurality of molten slag screening openings which are in communication with the outside are arranged on the screening structure in a spaced mode, the screening structure can classify and screen the particles falling thereon according to particle sizes and discharge the particles from the granulation bin body through the molten slag screening openings or the granulation bin outlet, and the side wall heat exchange device is used for cooling the side wall of the granulation bin body. The self-screening molten slag dry granulation waste heat recovery device can solve the problem of adhesion of high-temperature slag particles in the granulation process and realize efficient waste heat recovery and self-screening of classified granulation particles.

Description

Technical Field

[0001] This invention relates to the field of high-temperature metallurgical slag waste heat recovery, specifically to a self-screening slag dry granulation waste heat recovery device. Background Technology

[0002] In the steel production process, along with the output of steel products, high-temperature byproducts such as blast furnace slag, which reaches temperatures as high as 1500℃, are also generated. Blast furnace slag contains abundant waste heat resources, accounting for 22% of all waste heat resources in the steel industry, and is currently one of the few unrecovered waste heat resources in the steel industry. According to statistics, global pig iron production in 2022 was 1.3 billion tons, and approximately 0.3 tons of blast furnace slag are generated for every ton of pig iron produced. Therefore, the waste heat resources contained in blast furnace slag emitted globally in 2022 were equivalent to 24.2 million tons of standard coal. On the other hand, the main components of blast furnace slag are CaO, SiO2, MgO, and Al2O3, etc. During the rapid cooling process, the high-temperature liquid blast furnace slag forms amorphous phase substances with potential chemical activity, which can be used as cement admixtures in the production of silicate cement, slag concrete, etc., thereby creating more economic value.

[0003] Currently, the main method for treating blast furnace slag is water quenching, which involves using hydraulic impact to bring the high-temperature molten slag into direct contact with cooling water. During water quenching, the blast furnace slag is rapidly cooled, resulting in a high glass content; simultaneously, under thermal stress, the blast furnace slag automatically breaks into tiny particles. However, water quenching has many drawbacks, such as wasting fresh water, generating toxic gases, and wasting the waste heat of the molten slag. To overcome these drawbacks, researchers have focused on dry treatment technology for high-temperature molten slag, which uses physical methods to break the molten slag into small particles, allowing the high-temperature particles to directly exchange heat with the cooling airflow or through indirect heat exchange with water-cooled coils, ultimately obtaining high-temperature air or steam for utilization, achieving efficient waste heat recovery.

[0004] Centrifugal granulation technology is considered the most promising dry treatment technology for blast furnace slag due to its advantages such as low water consumption, high waste heat recovery rate, no generation of harmful gases, and high added value utilization of materials. In the dry centrifugal granulation process, high-temperature liquid slag is granulated into small droplets by the granulator. After the droplets collide with the water-cooled wall for heat exchange, they gradually enter the bottom of the granulation chamber and are discharged, and then enter the subsequent moving bed heat exchange device.

[0005] It should be noted that the size of granulated particles is usually uneven, ranging from 0-10 mm, making them wide-sized particles. Different particle sizes contain varying amounts of vitreous matter, meaning they have different chemical activities and therefore different industrial applications. Furthermore, the high frequency of collisions between particles during movement easily leads to particle adhesion, forming large particles or even lumps. Therefore, it is necessary to screen and classify particles of different sizes to meet different application requirements, while simultaneously removing large, adhered particles from the granulation chamber in advance. To address these issues, this invention designs a self-screening molten slag dry granulation waste heat recovery device, effectively solving the aforementioned problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the technical problem to be solved by this invention is to provide a self-screening slag dry granulation waste heat recovery device, which has the functions of particle self-screening and waste heat recovery, effectively solving the problems in the background technology.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: a waste heat recovery device for dry granulation of self-screening molten slag, comprising a centrifugal granulator, and further comprising:

[0008] The centrifugal granulator is characterized by further comprising:

[0009] The granulation chamber body has a closed top with an exhaust vent and an open bottom. The centrifugal granulator is located inside the granulation chamber body.

[0010] A slag feeding pipe extends from the external slag discharge device through the top of the granulation bin body into the granulation bin body, and is used to transport high-temperature molten slag from the outside of the granulation bin body to the centrifugal granulator.

[0011] A sidewall heat exchange device is used to cool the sidewall of the granulation chamber body;

[0012] A screening structure covers the bottom of the granulation chamber body. The screening structure can generate upward cooling air. The top surface of the screening structure gradually slopes downward from its edge to the center. The middle part of the screening structure has a granulation chamber outlet that communicates with the outside. The screening structure has multiple slag openings that communicate with the outside at intervals. The screening structure can classify and screen the particles that fall on it according to their particle size and discharge them from the granulation chamber body through the slag openings or the granulation chamber outlet.

[0013] Furthermore, the sidewall surface of the granulation chamber body is a smooth surface.

[0014] Furthermore, the sidewall heat exchange device includes a pipe that is spirally coiled around the sidewall of the granulation chamber body, and the water inlet end of the pipe can be connected to an external water source.

[0015] Furthermore, the sidewall heat exchange device also includes a flow control valve, which is installed on the pipe and used to control the flow rate of the liquid in the pipe.

[0016] Furthermore, the pipe has a semi-circular cross-section, with the arc end of the semi-circular cross-section facing the outside of the granulation chamber body and the straight end of the semi-circular cross-section facing the inside of the granulation chamber body. The pipe is covered on the outer wall of the granulation chamber body to form a closed water passage.

[0017] Furthermore, the screening structure includes an air distribution plate, an air supply pipe, and a blower. The air distribution plate covers the open bottom of the granulation bin body and gradually slopes downwards from the edge of the granulation bin body to the center in an inverted cone shape. The center of the air distribution plate has an outlet for the granulation bin that communicates with the outside. The air distribution plate has multiple annular slag screening openings spaced from the outside to the inside. An independent air chamber is provided between every two adjacent slag screening openings on the air distribution plate. An air outlet is provided on the air distribution plate that connects the air chamber to the inner cavity of the granulation bin body. Each air chamber is connected to the blower through a separate air supply pipe, and each air supply pipe is equipped with an air volume control valve. The blower is used to supply air into the air chamber.

[0018] Furthermore, the width of the slag opening is adjustable.

[0019] Furthermore, the angle between the air distribution plate and the granulation chamber body is adjustable.

[0020] Furthermore, the air distribution plate includes partitions, support rings, and a lifting structure. There are multiple partitions arranged in a ring, inclined downwards, and staggered vertically to form the air distribution plate. The upper partition is supported on both sides by the partitions on the left and right sides. There are multiple support rings, and the diameter of the rings decreases sequentially from the outside to the inside. The multiple support rings are spaced apart and supported on all the lower partitions and connected by sliders. The sliders can slide radially along the granulation chamber body. Each support ring is supported by the lifting structure, which can push the support ring up or down.

[0021] Furthermore, the dividing plate includes segments arranged radially at intervals along the granulation bin body. Each segment is provided with an air chamber and an air outlet. A gap is formed between two radially adjacent segments. The gaps in the same circumferential direction form an annular slag opening. The front and rear ends of the lower segment are supported by the support ring.

[0022] The beneficial effects of this invention are:

[0023] In the above-mentioned self-screening molten slag dry granulation waste heat recovery device, high-temperature liquid molten slag is first sent into the centrifugal granulator through the slag feeding pipe. The centrifugal granulator is driven by a motor to rotate at high speed. The high-temperature liquid molten slag flowing into the centrifugal granulator is granulated into droplets of different sizes under the action of centrifugal force and surface tension. The droplets fly at high speed and hit the side wall of the granulation chamber. During this process, the droplets exchange heat with the air and cool down. Small droplets form solid particles, while large droplets are liquid or semi-molten liquid particles.

[0024] Particles falling onto the screening structure undergo heat exchange with the cooling air from within the structure, and the hot air is discharged from the top exhaust vent, achieving efficient recovery of waste heat. Furthermore, due to the cooling air from the air distribution plate, particles that have not agglomerated slide from the top of the screening structure to the granulation bin outlet at the bottom, thus being discharged from the granulation bin body. Simultaneously, during the granulation process in the granulation bin, the particles collide frequently, easily agglomerating into large particles or even slag. These slag, under the influence of drag and elastic collision forces, can be discharged from the granulation bin through the screening function of the screening structure, preventing further agglomeration and clogging of the moving bed heat exchanger.

[0025] The above-mentioned self-screening slag dry granulation waste heat recovery device can achieve efficient waste heat recovery and granulation particle classification and self-screening, thus meeting the purpose of different application requirements. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly described below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0027] Figure 1 This is a schematic diagram of a waste heat recovery device for dry granulation of self-screening slag provided in an embodiment of the present invention;

[0028] Figure 2 for Figure 1 A partial schematic diagram of point A;

[0029] Figure 3 for Figure 1 A top view of a schematic diagram of an air distribution plate in a self-screening slag dry granulation waste heat recovery device;

[0030] Figure label:

[0031] 100. Centrifugal granulator; 200. Granulation bin body; 300. Slag delivery pipe; 400. Screening structure; 410. Air distribution plate; 411. Grading air plate; 4111. Block; 412. Support ring; 413. Lifting structure; 414. Sliding block; 420. Air supply pipe; 430. Fan; 440. Granulation bin outlet; 450. Slag screening port; 460. Air chamber; 470. Air outlet; 480. Air volume control valve; 500. Side wall heat exchange device; 510. Pipeline; 520. Flow control valve. Detailed Implementation

[0032] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0033] Please see Figures 1 to 3 This invention provides a waste heat recovery device for dry granulation of self-screening molten slag, comprising a centrifugal granulator 100, a granulation chamber body 200, a slag feeding pipe 300, a screening structure 400, and a sidewall heat exchange device 500. The top of the granulation chamber body 200 is closed and has an exhaust port 611, while the bottom is open. The centrifugal granulator 100 is disposed inside the granulation chamber body 200. The slag feeding pipe 300 extends from an external slag discharge device through the granulation chamber body 200 into the granulation chamber body 200, used to transport high-temperature molten slag from outside the granulation chamber body 200 to the centrifugal granulator 100. The sidewall heat exchange device 500 is used to cool the sidewalls of the granulation chamber body 200.

[0034] A screening structure 400 covers the bottom of the granulation bin body 200 and generates upward cooling air. The top surface of the screening structure 400 gradually slopes downward from its edge to the center. A granulation bin outlet 440 communicating with the outside is opened in the middle of the screening structure 400. Multiple slag openings 450 communicating with the outside are spaced along the screening structure 400, which can classify and screen particles falling onto it and discharge them from the granulation bin body 200 through the slag openings 450 or the granulation bin outlet 440. A sidewall heat exchange device 500 is used to cool the sidewalls of the granulation bin body 200.

[0035] In use, high-temperature liquid slag is first fed into the centrifugal granulator 100 through the slag feeding pipe 300. The centrifugal granulator 100 is driven by a motor to rotate at high speed. The high-temperature liquid slag flowing into the centrifugal granulator 100 is granulated into droplets of different sizes under the action of centrifugal force and surface tension. The droplets fly at high speed and hit the side wall of the granulation chamber body 200. During this process, the droplets exchange heat with the air and cool down. Small droplets form solid particles, while large droplets are liquid or semi-molten liquid particles.

[0036] Particles falling onto the screening structure 400 undergo heat exchange with the cooling air from the screening structure 400, achieving efficient recovery of waste heat. In addition, due to the cooling air from the air distribution plate 410, the particles slide from the top of the screening structure 400 to the granulation bin outlet 440 at the bottom, thus being discharged from the granulation bin body 200. At the same time, during the granulation process in the granulation bin body 200, the collision frequency between particles is relatively high, and the particles are prone to agglomerate into large particles or even slag. The slag formed can be discharged from the granulation bin through the screening function of the screening structure 400 under the action of drag and elastic collision force, avoiding further agglomeration and blockage of the moving bed heat exchanger.

[0037] In practical implementation, the side wall of the granulation bin body 200 is a smooth surface, which can reduce the adhesion between the particles and the side wall of the granulation bin body 200. In addition, insulation material can be wrapped on the surface of the slag feeding pipe 300 to reduce heat loss during the molten slag flow process and ensure fluidity.

[0038] In this embodiment, the sidewall heat exchange device 500 includes a pipe 510. The pipe 510 is spirally coiled around the sidewall of the granulation chamber body 200, and the water inlet end of the pipe 510 is connected to an external water source. As a preferred embodiment, the sidewall heat exchange device 500 may further include a flow control valve 520, which is disposed on the pipe 510 and used to control the flow rate of the liquid in the pipe 510.

[0039] In practice, the cooling water flow rate is determined by the molten slag flow rate, and the flow rate is controlled by the flow control valve 520. During the flow process, the cooling water can form heat exchange with the side wall of the granulation chamber body 200, thereby promoting heat exchange with the side wall of the granulation chamber body 200, and further promoting the granulation of the droplets after impact with the side wall of the granulation chamber body 200.

[0040] In a preferred embodiment, the pipe 510 has a semi-circular cross-section, with the curved end of the semi-circular cross-section facing outwards from the granulation chamber body and the straight end facing inwards from the granulation chamber body. The pipe 510 covers the outer wall of the granulation chamber body 200, forming a closed water passage. This allows cooling water to directly contact the outer side wall of the granulation chamber body 200, improving heat exchange efficiency.

[0041] In this embodiment, the screening structure 400 includes an air distribution plate 410, an air supply pipe 420, and a blower 430. The air distribution plate 410 covers the open bottom of the granulation bin body 200 and gradually slopes downwards from the edge of the granulation bin body 200 to the center in an inverted cone shape. A granulation bin outlet 440 communicating with the outside is opened at the center of the air distribution plate 410, and multiple annular slag openings 450 are spaced apart from the outside to the inside on the air distribution plate 410. An independent air chamber 460 is provided between every two adjacent slag openings 450 on the air distribution plate 410. An air outlet 470 is opened on the air distribution plate 410 to connect the air chamber 460 with the inner cavity of the granulation bin body 200. Each air chamber 460 is connected to the blower 430 through a separate air supply pipe 420, and each air supply pipe 420 is provided with an air volume control valve 480. The blower 430 is used to supply air into the air chamber 460. There can be multiple fans or a single fan.

[0042] During use, the downward-sloping air distribution plate 410 ensures that particles on it can fall smoothly into the slag discharge port of the granulation chamber under gravity, preventing large-area particle adhesion and thus avoiding equipment operation. The opening can be a vertical circular hole, preferably with a diameter of less than 2-3 mm, so particles larger than 3 mm will not fall into the air chamber 460 from the air outlet 470. For particles smaller than 3 mm, the air velocity at the outlet can be adjusted to be greater than the minimum fluidization velocity of the particles, ensuring that small particles also do not fall into the air chamber 460. Each air distribution plate 410 has an independent air chamber 460, and each air chamber 460 has an independent airflow regulating valve, allowing for free adjustment of the airflow. Furthermore, the opening ratio of the air outlet 470 can be gradually reduced from the edge to the center, thereby enhancing heat exchange when particles fall into the air distribution plate 410, reducing the particle surface temperature, and minimizing particle adhesion.

[0043] Particles falling onto the screening structure 400 undergo heat exchange under the action of cooling air blown from the air chamber 460. The hot air is discharged from the top exhaust port, achieving efficient recovery of waste heat. In addition, under the action of cooling air from the air distribution plate 410, particles that have not agglomerated slide from the top of the screening structure 400 to the granulation bin outlet 440 at the bottom, thus being discharged from the granulation bin body 200. During the sliding process, the increased collision frequency between particles increases the occurrence of particle agglomeration. Larger slag lumps formed by agglomeration can be discharged through the slag opening 450 near the side wall of the granulation bin body 200, larger particles formed by agglomeration of small particles can be discharged through the middle slag opening 450, and the smallest particles are discharged through the slag opening 450 away from the side wall of the granulation bin body 200, thereby achieving the screening of slag lumps, large particles, and small particles.

[0044] In a preferred embodiment, the width of the slag screening opening 450 is adjustable. By changing the width of the slag screening opening 450, the diameter of the particles flowing out of the corresponding slag screening opening 450 can be changed, thereby achieving an automatic screening function. At the same time, the slag screening opening 450 can also be adjusted to a closed state.

[0045] Under normal circumstances, the downward tilt angle of the inclined air distribution plate 410 is 25°-30°. In specific implementation, the width of the slag opening 450 can be changed by adjusting the included angle between the air distribution plate 410 and the granulation bin body 200, thereby realizing the automatic screening function.

[0046] In this embodiment, the air distribution plate 410 includes multiple partition plates 411, support rings 412, and a lifting structure 413. Multiple partition plates 411 are arranged in a ring-like sequence, tilted downwards, and staggered vertically to form the air distribution plate 410. The upper partition plate 411 is supported on its left and right sides by the partition plates 411 on its left and right sides. Multiple support rings 412 have annular diameters that decrease sequentially from the outside to the inside. These support rings 412 are spaced apart and supported on all the lower partition plates 411, and are connected by sliders 414. The sliders 414 can slide radially along the granulation chamber body. Each support ring 412 is supported by the lifting structure 413, which can push the support ring 412 up or down.

[0047] In use, activating the lifting structure 413 raises or lowers the plate. By pushing the support ring 412, all the lower plates 411 can be raised or lowered, thereby adjusting the angle of the air distribution plate 410 and the width of the slag opening 450. This achieves automatic screening and ensures that particles on the air distribution plate 410 can fall smoothly into the slag discharge port of the granulation chamber under gravity, without affecting the operation of subsequent equipment. Alternatively, in other embodiments, the air distribution plate 410 can be an integral conical plate with a certain degree of elastic deformation. By changing the angle of the integral plate, the air distribution plate 410 can deform, thus adjusting the width of the slag opening 450.

[0048] In a more preferred embodiment, the dividing plate 411 includes blocks 4111 arranged radially along the granulation bin body. Each block 4111 is provided with an air chamber 460 and an air outlet 470. A gap is formed between two adjacent blocks 4111 in each radial direction. The gaps in the same circumferential direction form an annular slag screen opening 450. The front and rear ends of the lower block 4111 are supported by support rings 412.

[0049] When it is necessary to change the width of a certain slag opening 450, simply activate the lifting structures 413 on both sides of the corresponding slag opening 450. The lifting structures 413 push the support ring 412 up or down, which in turn drives the ends of all the blocks 4111 above the support ring 412 up or down, thus achieving the adjustment of the width of the slag opening 450. Furthermore, in the initial stage of granulation, the slag opening 450 can be closed to facilitate granulation. In specific implementations, the lifting structure 413 can be a commonly used lifting motor or similar device in the prior art.

[0050] The above-mentioned self-screening molten slag dry granulation waste heat recovery device can solve the problem of slag block discharge during the granulation process of high-temperature slag particles, and can achieve efficient waste heat recovery and granulation particle classification and self-screening to meet different application requirements.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A waste heat recovery device for dry granulation of self-screening molten slag, comprising a centrifugal granulator, characterized in that, Also includes: The granulation chamber body has a closed top with an exhaust vent and an open bottom. The centrifugal granulator is located inside the granulation chamber body. A slag feeding pipe extends from the external slag discharge device through the top of the granulation bin body into the granulation bin body, and is used to transport high-temperature molten slag from the outside of the granulation bin body to the centrifugal granulator. A sidewall heat exchange device is used to cool the sidewall of the granulation chamber body; A screening structure covers the bottom of the granulation bin body. The screening structure can generate upward cooling air. The top surface of the screening structure gradually slopes downward from its edge to the center. The middle part of the screening structure has a granulation bin outlet that communicates with the outside. The screening structure has multiple slag openings that communicate with the outside at intervals. The screening structure can classify and screen the particles that fall on it according to their particle size and discharge them from the granulation bin body through the slag openings or the granulation bin outlet. The screening structure includes an air distribution plate, an air supply pipe, and a blower. The air distribution plate covers the open bottom of the granulation bin body and gradually slopes downwards from the edge of the granulation bin body to the center in an inverted cone shape. The center of the air distribution plate has an outlet for the granulation bin that communicates with the outside. The air distribution plate has multiple annular slag screening openings spaced from the outside to the inside. An independent air chamber is provided between every two adjacent slag screening openings on the air distribution plate. An air outlet is provided on the air distribution plate that connects the air chamber to the inner cavity of the granulation bin body. Each air chamber is connected to the blower through a separate air supply pipe, and each air supply pipe is equipped with an air volume control valve. The blower is used to supply air into the air chamber. The angle between the air distribution plate and the granulation chamber body is adjustable; The air distribution plate includes partitions, support rings, and a lifting structure. Multiple partitions are arranged in a ring-like, downward-sloping, and staggered manner to form the air distribution plate. The upper partition is supported on its left and right sides by the partitions on its left and right sides. Multiple support rings are also included, with their diameters decreasing sequentially from the outside to the inside. These support rings are spaced apart and supported on all the lower partitions, connected by sliders that can slide radially along the granulation chamber body. Each support ring is supported by the lifting structure, which can push the support ring up or down.

2. The waste heat recovery device for dry granulation of self-screening slag according to claim 1, characterized in that, The sidewall of the granulation chamber body is a smooth surface.

3. The waste heat recovery device for dry granulation of self-screening slag according to claim 1, characterized in that, The sidewall heat exchange device includes a pipe that is spirally coiled around the sidewall of the granulation chamber body, and the water inlet end of the pipe can be connected to an external water source.

4. The waste heat recovery device for dry granulation of self-screening slag according to claim 3, characterized in that, The sidewall heat exchange device also includes a flow control valve, which is installed on the pipeline and used to control the flow rate of the liquid in the pipeline.

5. The waste heat recovery device for dry granulation of self-screening slag according to claim 3 or 4, characterized in that, The pipe has a semi-circular cross-section, with the arc end of the semi-circular cross-section facing the outside of the granulation chamber body and the straight end of the semi-circular cross-section facing the inside of the granulation chamber body. The pipe is covered on the outer wall of the granulation chamber body to form a closed water passage.

6. The waste heat recovery device for dry granulation of self-screening slag according to claim 1, characterized in that, The width of the slag screen opening is adjustable.

7. The waste heat recovery device for dry granulation of self-screening slag according to claim 6, characterized in that, The dividing plate includes segments arranged radially at intervals along the granulation bin body. Each segment is provided with an air chamber and an air outlet. A gap is formed between two radially adjacent segments. The gaps in the same circumference form an annular slag screening opening. The front and rear ends of the lower segment are supported by the support ring.

Images