A hot direct reduction of sponge iron with hot delivery device

Abstract

The utility model relates to metallurgical technical field, concretely provides a kind of hot sending device of high-temperature direct reduction sponge iron.The device includes nitrogen storage tank, shaft furnace, high-temperature material blocking valve, high-temperature dome valve, conveying pump body, conveying pipeline and elbow, electric furnace hot stock bin, conveying valve group, auxiliary blowing valve group and block valve group, form nitrogen protection conveying system by closed connection.The utility model effectively solves the problem of large heat loss, short equipment life and low efficiency of sponge iron conveying in the prior art, and the beneficial effects include energy efficiency improvement of 30-50%, equipment life extension and conveying stability improvement.The specification abstract reflects the core innovation of the device, is suitable for direct hot sending of high-temperature sponge iron, improves the economy and environmental protection of metallurgical production.

Description

Technical Field

[0001] This utility model relates to the field of metallurgical technology, specifically to a high-temperature material conveying device, and more particularly to a hot conveying device for directly conveying high-temperature direct reduction sponge iron produced in a vertical shaft furnace to an electric furnace hot material bin. Background Technology

[0002] High-temperature direct reduced sponge iron (HDR) is a pre-reduced pellet widely used in the metallurgical industry. It involves pretreating iron oxides with a reducing agent to obtain partially metallic iron. Due to its porous structure, HDR serves as a scrap steel substitute in electric arc furnace (EAF) steelmaking, effectively reducing costs and resource consumption. As of 2024, global HDR production reached 54.7 million tons, highlighting its industrial importance. In existing technologies, HDR produced from shaft furnaces typically reaches temperatures of 800 to 1200 degrees Celsius. Traditional conveying methods rely on conventional equipment, such as ordinary conveyor belts or containers, to transfer this high-temperature HDR to the EAF's hot charge bins. However, ordinary equipment cannot withstand the high temperatures or prevent oxidation; therefore, HDR must be cooled to a lower temperature (e.g., room temperature or several hundred degrees Celsius) before conveying. This cooling process is achieved through natural heat dissipation or forced cooling systems, resulting in significant heat loss. It is estimated that heat loss can account for 30% to 50% of the total thermal energy of HDR, causing significant energy waste.

[0003] The shortcomings of existing technologies are mainly reflected in the following aspects: First, energy consumption is huge. The cooling and reheating processes require additional fuel or electricity, increasing carbon emissions and driving up operating costs. Second, equipment lifespan is short. Ordinary valves and pipes cannot withstand high-temperature environments, easily becoming worn, oxidized, or deformed, requiring frequent replacement and resulting in high maintenance costs. For example, valve body materials may soften under high temperatures, leading to seal failure. Third, conveying efficiency is low. Larger sponge iron particles easily accumulate at pipe bends, causing blockages and conveying interruptions, affecting continuous production. Furthermore, existing technologies lack effective insulation measures, further reducing overall efficiency due to heat loss. Summary of the Invention

[0004] The technical problem this invention aims to solve is that in the existing technology, high-temperature direct reduction of sponge iron requires cooling before transportation due to reliance on ordinary equipment, resulting in significant heat loss and serious energy waste. At the same time, ordinary valves and pipelines cannot withstand high-temperature environments, leading to short equipment lifespan and high maintenance costs. Furthermore, sponge iron particles are prone to accumulate at conveying bends, causing blockages and transportation interruptions, which affect production continuity and efficiency.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution.

[0006] A high-temperature direct reduction sponge iron hot conveying device includes a nitrogen storage tank 1, a vertical furnace 2, a high-temperature baffle valve 3, a high-temperature dome valve 4, a conveying pump body 5, a conveying pipeline and elbow 6, an electric furnace hot material bin 7, a conveying valve group 8, an auxiliary blowing valve group 9, and a blockage removal valve group 10. The device is characterized in that the outlet of the nitrogen storage tank 1 is connected to the conveying valve group 8, the auxiliary blowing valve group 9, and the blockage removal valve group 10; the outlet of the vertical furnace 2 is connected to the inlet of the high-temperature baffle valve 3; the outlet of the high-temperature baffle valve 3 is connected to the inlet of the high-temperature dome valve 4; the outlet of the high-temperature dome valve 4 is connected to the inlet of the conveying pump body 5; the outlet of the conveying pump body 5 is connected to the front end of the conveying pipeline and elbow 6; and the end of the conveying pipeline and elbow 6 is connected to the inlet of the electric furnace hot material bin 7, forming a closed conveying system.

[0007] In a preferred embodiment of the present invention, the valve body material of the high-temperature baffle valve 3 and the high-temperature dome valve 4 is 310S stainless steel.

[0008] In a preferred embodiment of the present invention, the sealing surfaces of the high-temperature baffle valve 3 and the high-temperature dome valve 4 are provided with a wear-resistant ceramic coating.

[0009] In a preferred embodiment of the present invention, the outer shell 51 of the pump body 5 includes an inner working layer 511, a middle permanent layer 512 and an outer heat insulation layer 513.

[0010] In a preferred embodiment of the present invention, the working layer 511 is made of slag-resistant and wear-resistant castable with a thickness of 50-100 mm.

[0011] In a preferred embodiment of the present invention, the permanent layer 512 is made of heat-resistant and wear-resistant spray coating with a thickness of 30-50 mm.

[0012] In a preferred embodiment of the present invention, the thermal insulation layer 513 is made of lightweight mullite and has a thickness of 50-80 mm.

[0013] In a preferred embodiment of the present invention, the conveying pipe and elbow 6 includes an inner pipe layer 63, a middle pipe layer 62, and an outer pipe layer 61.

[0014] In a preferred embodiment of the present invention, the inner layer 63 of the pipe is made of rare earth alloy, the middle layer 62 of the pipe is filled with aluminum silicate thermal insulation material, and the outer shell layer 61 of the pipe is made of No. 20 steel.

[0015] In a preferred embodiment of the present invention, the delivery valve group 8, the blowing valve group 9, and the unblocking valve group 10 are controlled by an automated system.

[0016] Compared with the prior art, the beneficial technical effects of this utility model are as follows: This invention utilizes a closed-loop nitrogen protection system and insulation design to directly deliver high-temperature sponge iron at 800-1200 degrees Celsius, avoiding heat loss during the cooling process. Theoretical analysis suggests that heat loss can be reduced by 30% to 50%, thereby lowering the energy demand for reheating in the electric furnace and improving overall energy efficiency by approximately 20% or more. For example, preheating to around 100 degrees Celsius with nitrogen prevents sudden cooling and further optimizes thermal management.

[0017] By employing high-temperature resistant materials (such as 310S stainless steel) and wear-resistant coatings (such as ceramic coatings), key components such as the high-temperature baffle valve and the high-temperature dome valve are resistant to deformation and oxidation under high-temperature environments, extending their service life to more than twice that of ordinary equipment. Experimental data shows that the valve body exhibits no significant wear during continuous operation, and the maintenance interval has been extended from once a month to once every six months.

[0018] Through automated valve control and a blockage-clearing mechanism, the conveying process is continuous and uninterrupted. Theoretical analysis shows that the blockage rate is reduced by 90% and the conveying efficiency is increased by 25%, thanks to the blockage-clearing valve assembly at the elbows and the nitrogen-assisted blowing system. In addition, the insulation layer design reduces the external temperature to 40-60 degrees Celsius, ensuring safe operation.

[0019] By reducing carbon emissions and operating costs, energy savings reduce the cost of processing each ton of sponge iron by 15%, which meets the requirements of sustainable development. Attached Figure Description

[0020] Figure 1 A schematic diagram of the overall structure of the high-temperature direct reduction sponge iron heat delivery device provided by this utility model; Figure 2 A schematic diagram of the overall structure of the outer shell of the conveying pump provided by this utility model; Figure 3 A cross-sectional view of the multi-layer structure of the outer shell of the conveying pump provided by this utility model; Figure 4 A schematic diagram of the multi-layer structure of the conveying pipeline provided by this utility model; Figure 5 A schematic diagram of the connection structure of the anchoring nails on the conveying pipeline provided by this utility model.

[0021] The labels for each attached drawing are as follows: 1: Nitrogen storage tank; 2: Vertical furnace; 3: High-temperature baffle valve; 4: High-temperature dome valve; 5: Conveying pump body; 6: Conveying pipeline and elbow; 7: Electric furnace hot material bin; 8: Conveying valve assembly; 9: Auxiliary blowing valve assembly; 10: Deblocking valve assembly; 51: Conveying pump body outer shell; 511: Working layer; 512: Permanent layer; 513: Thermal insulation layer; 514: Anchoring nails for the outer shell of the conveying pump body; 61: Pipe outer shell layer; 62: Pipe intermediate layer; 63: Pipe inner layer; 64: Anchoring nails for the conveying pipeline. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] like Figure 1 As shown, in the first embodiment of this utility model, a hot conveying device for high-temperature direct reduction of sponge iron is provided. The hot conveying device is specifically used to directly transport high-temperature sponge iron produced in the vertical furnace at a temperature range of 800 to 1200 degrees Celsius to the electric furnace hot material bin, thereby avoiding heat loss during the cooling process and improving energy utilization efficiency.

[0025] The hot conveying device includes a nitrogen storage tank 1, a vertical furnace 2, a high-temperature baffle valve 3, a high-temperature dome valve 4, a conveying pump body 5, conveying pipes and elbows 6, an electric furnace hot material bin 7, a conveying valve assembly 8, an auxiliary blowing valve assembly 9, and a plugging valve assembly 10. These components are connected by pipes and flanges to form a complete closed system, ensuring the safe conveying of sponge iron under nitrogen protection.

[0026] The nitrogen storage tank 1, serving as an energy storage device for compressed gas used in transportation, is located at the beginning of the system. Its inlet is connected to an external nitrogen source, and its outlet is connected to the transportation valve group 8, the purging valve group 9, and the plugging valve group 10 via pipelines.

[0027] Nitrogen is used as the carrier gas because its inert properties prevent the sponge iron from oxidizing at high temperatures. Preferably, the nitrogen is preheated to about 100 degrees Celsius to avoid rapid cooling caused by low-temperature gas contacting the sponge iron. The discharge port of the vertical furnace 2 is directly connected to the inlet of the high-temperature baffle valve 3 via a flange. The vertical furnace 2 is responsible for generating high-temperature sponge iron and ensuring continuous production by controlling the material feeding rhythm.

[0028] The high-temperature baffle valve 3 is a high-temperature isolation valve. Its outlet is connected to the inlet of the high-temperature dome valve 4. Its function is to initially seal and regulate the material flow to prevent pressure imbalance in the vertical furnace.

[0029] The high-temperature dome valve 4 is located below the high-temperature baffle valve 3, and its outlet is connected to the inlet of the conveying pump body 5. The valve is designed with a high-temperature resistant sealing structure, which can both isolate heat and ensure that the conveying pump body 5 is isolated from the external environment when feeding.

[0030] The pump body 5 serves as a transfer container. The upper inlet is connected to the high-temperature dome valve 4, the top air inlet is connected to the conveying valve group 8, the bottom air inlet is connected to the blowing valve group 9, and the outlet is connected to the front end of the conveying pipeline and the elbow 6.

[0031] The end of the conveying pipe and elbow 6 is connected to the inlet of the electric furnace hot material silo 7, forming a complete conveying path; the inner layer of the pipe is wear-resistant, the middle layer is heat-insulated, and the outer layer is supported. A blockage relief valve group 10 is provided at the elbow for emergency blockage relief.

[0032] The delivery valve group 8 and the blowing valve group 9 control the direction of nitrogen flow, while the plugging valve group 10 is distributed at each bend and is automatically managed through pressure monitoring.

[0033] Vertical shaft furnace 2 is the production equipment for high-temperature direct reduced iron. Its outlet is directly connected to the inlet of high-temperature baffle valve 3 via a flange. The vertical shaft furnace is responsible for producing sponge iron and generating high-temperature pellets through its internal reduction process.

[0034] Because the temperature of the sponge iron is extremely high when it exits the furnace, ordinary valves cannot be used. Therefore, the high-temperature baffle valve 3 is designed as a high-temperature isolation valve. Its inlet is connected to the outlet of the vertical furnace 2, and its outlet is connected to the inlet of the high-temperature dome valve 4. The function of the high-temperature baffle valve 3 is to control the feeding rhythm of the sponge iron, prevent continuous material falling and causing system overload, and at the same time, it plays a preliminary sealing role to reduce heat loss. The high-temperature dome valve 4 is located below the high-temperature baffle valve 3, and its outlet is connected to the inlet of the conveying pump body 5. The high-temperature dome valve 4 is a special valve that can withstand high temperatures and provide a reliable seal, ensuring that the conveying pump body 5 is isolated from the external environment during the feeding process, avoiding oxidation and temperature loss.

[0035] Preferably, the valve body materials of the high-temperature baffle valve 3 and the high-temperature dome valve 4 must meet the requirements of high temperature resistance, deformation resistance, and strong structural stability to cope with the extreme temperature environment of sponge iron produced by the vertical furnace, and avoid problems such as valve body deformation and sealing failure caused by high temperature in ordinary valves. Schematic, 310S stainless steel can be used. At a working temperature of 800-1200℃, 310S stainless steel will not undergo a phase transformation and can maintain high room temperature strength, with a tensile strength ≥520MPa and a yield strength ≥205MPa. It can effectively resist the impact load when high-temperature sponge iron falls, avoiding structural deformation of the valve body due to high-temperature softening. More preferably, the valve sealing surfaces of the high-temperature baffle valve 3 and the high-temperature dome valve 4, i.e., the contact surfaces between the valve plate and the valve body, are coated with a plasma-sprayed wear-resistant ceramic coating. This coating is composed of alumina or zirconium oxide. The high-temperature resistance of this coating matches the 310S stainless steel valve body substrate, and the coating will not peel off or crack at a working temperature of 800-1200℃, ensuring the long-term sealing performance of the sealing surface.

[0036] The pump body 5 is a transfer container. Its upper inlet is connected to the high-temperature dome valve 4, the top is provided with an air inlet connected to the conveying valve group 8, the bottom air inlet is connected to the blowing valve group 9, and the outlet is connected to the front end of the conveying pipeline and the elbow 6.

[0037] The design focus of the pump body 5 is on thermal insulation performance, which is described below. Figure 2 and Figure 3 Detailed description of the pump body 5, outer casing 51. For example... Figure 2 As shown, the outer casing 51 of the conveying pump body 5 is generally cylindrical or rectangular, with the specific shape optimized according to the conveying capacity and installation space. The casing surface is smooth and has multiple interfaces: the upper inlet connects to the high-temperature dome valve 4 for receiving sponge iron; the top and sides have air inlets respectively, connected to the conveying valve assembly 8 and the blowing valve assembly 9 for injecting nitrogen; the bottom outlet connects to the conveying pipeline and elbow 6, forming a material flow path. The overall dimensions of the casing are customized according to the processing capacity, for example, the volume can be 5-20 cubic meters. In addition, brackets or lifting lugs may be added to the outside of the casing for easy installation and maintenance, resulting in a compact overall structure.

[0038] Figure 3 The internal multi-layered structure of the pump body 5 is shown in detail through a cross-sectional view. The outer shell consists of three layers from the inside out: the innermost layer is the working layer 511, which directly contacts the high-temperature sponge iron and is made of slag-resistant and wear-resistant castable material with a preferred thickness of 50-100 mm. This material is composed of high-alumina or silicon carbide-based composite materials, exhibiting excellent high-temperature resistance, capable of withstanding temperatures above 1300 degrees Celsius, and also able to resist repeated impacts and friction from sponge iron particles. The surface of the working layer is smooth and designed with a slight inclination or arc to promote material flow and prevent accumulation.

[0039] The intermediate layer 512 is a permanent layer located outside the working layer. It is made of heat-resistant and wear-resistant spray paint and is approximately 30-50 mm thick. The function of the permanent layer is to enhance structural stability and prevent the working layer from cracking under thermal expansion and contraction. Its material contains ceramic fiber or alumina components, providing additional heat insulation and cushioning.

[0040] The outermost 513 layer is a thermal insulation layer made of lightweight mullite, with a thickness of 50-80 mm. Its function is to block heat convection and radiation, reducing the external temperature of the outer shell to near room temperature, such as 40-60 degrees Celsius, thereby avoiding heat loss and impact on the surrounding environment.

[0041] To prevent these insulation layers from detaching under high temperatures or vibrations, multiple anchoring studs 514 are welded inside the outer shell. These anchoring studs 514 are made of 310S stainless steel round bars, such as... Figure 3As shown. Anchor pins 514 are distributed on the inner wall of the outer shell, and their length is adjusted according to the layer thickness. Schematic, for example, they penetrate 20-30 mm into the working layer or 20-30 mm into the permanent layer. The heads of anchor pins 514 have various shapes, such as hook-shaped or plate-shaped, to enhance the adhesion to the castable.

[0042] The conveying pipe and elbow 6 is the conveying path of the sponge iron. Its front end is connected to the outlet of the conveying pump body 5, and its end is connected to the inlet of the electric furnace hot material bin 7.

[0043] See further Figure 4 and Figure 5 The pipeline also adopts a multi-layer structure. The pipeline includes an inner layer 63, which is made of high-temperature resistant and wear-resistant rare earth alloy to resist the friction and high-temperature corrosion of sponge iron; a middle layer 62 is closely attached to the outside of the inner layer 63 and is filled with aluminum silicate thermal insulation material to reduce heat conduction; the outer shell layer 61 is the outermost pressure-bearing and supporting shell of the pipeline, which is made of No. 20 steel to provide mechanical strength and assist in thermal insulation.

[0044] Several 310S anchor pins 64 are evenly distributed around the circumference of the pipe. One end of the anchor pin 64 is pre-welded to the inner wall of the outer shell layer 61 of the pipe, and then penetrates the middle layer 62 of the pipe, with its end firmly embedded or anchored in the high-temperature alloy layer of the inner layer 63 of the pipe.

[0045] The elbows are prone to blockage due to the large size of the sponge iron particles. Therefore, a deblocking valve assembly 10 is installed at each elbow. Once an abnormal pressure or blockage is detected, nitrogen can be injected through the deblocking valve assembly 10 to purge and restore flow. The electric furnace hot charge silo 7 is the end point of the conveying process. Its inlet is connected to the end of the conveying pipeline and the elbow 6. It is responsible for receiving high-temperature sponge iron and using it directly for electric furnace steelmaking, thus eliminating the need for reheating.

[0046] The conveying valve assembly 8 connects the nitrogen storage tank 1 and the top air inlet of the conveying pump body 5, and is used to inject nitrogen into the pump body during the conveying stage to create pressure and drive the sponge iron to move. The purging valve assembly 9 connects the nitrogen storage tank 1 and the bottom air inlet of the conveying pump body 5. Its function is to provide auxiliary airflow during the conveying process, prevent the sponge iron from accumulating at the bottom of the pump body, and ensure that the material completely enters the pipeline. The unblocking valve assembly 10 is distributed at each bend of the conveying pipeline and bend 6, and is connected to the nitrogen source for emergency unblocking. All valve assemblies are controlled by an automated system to achieve time-sequential operation.

[0047] The working process of the high-temperature direct reduction sponge iron heat transfer device provided by this utility model is as follows.

[0048] Before system startup, ensure all equipment and pipelines are connected and debugged, the nitrogen supply is ready, and the vertical furnace 2 has produced high-temperature sponge iron. First, after production is complete in the vertical furnace 2, a startup command is issued. The high-temperature baffle valve 3 and the high-temperature dome valve 4 open sequentially, allowing the high-temperature sponge iron to fall from the furnace into the conveying pump body 5. After the material falls, the high-temperature baffle valve 3 and the high-temperature dome valve 4 close, achieving a seal. Subsequently, the valves of the conveying valve group 8 and the auxiliary blowing valve group 9 open, and nitrogen enters the conveying pump body 5 from the nitrogen storage tank 1, gradually increasing the pressure within the pump body. Under the pressure of the nitrogen, the sponge iron is pushed into the conveying pipeline and elbow 6, moving along the pipeline and finally entering the electric furnace hot charge bin 7. When the pressure sensor in the conveying pump body 5 indicates that the conveying is complete, the conveying valve group 8 and the auxiliary blowing valve group 9 close, ending one conveying cycle. If abnormal pressure occurs during the conveying process, indicating a blockage, the control system will automatically or manually trigger the blockage removal valve group 10 to spray nitrogen into the elbow to clear the blockage. If the vertical shaft furnace is in continuous production, the system can run in a cycle starting from the material feeding step until a stop command is received.

[0049] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0050] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-temperature direct reduction sponge iron hot conveying device, comprising a nitrogen storage tank (1), a vertical furnace (2), a high-temperature baffle valve (3), a high-temperature dome valve (4), a conveying pump body (5), a conveying pipeline and elbows (6), an electric furnace hot material bin (7), a conveying valve group (8), an auxiliary blowing valve group (9), and a plugging valve group (10), characterized in that, The outlet of the nitrogen storage tank (1) is connected to the conveying valve group (8), the blowing valve group (9) and the plugging valve group (10). The discharge port of the vertical furnace (2) is connected to the inlet of the high temperature baffle valve (3). The outlet of the high temperature baffle valve (3) is connected to the inlet of the high temperature dome valve (4). The outlet of the high temperature dome valve (4) is connected to the inlet of the conveying pump body (5). The outlet of the conveying pump body (5) is connected to the front end of the conveying pipe and elbow (6). The end of the conveying pipe and elbow (6) is connected to the inlet of the electric furnace hot material bin (7), forming a closed conveying system.

2. The high-temperature direct reduction sponge iron heat conveying device according to claim 1, characterized in that, The valve body material of the high-temperature baffle valve (3) and the high-temperature dome valve (4) is 310S stainless steel.

3. The high-temperature direct reduction sponge iron heat conveying device according to claim 2, characterized in that, The sealing surfaces of the high-temperature baffle valve (3) and the high-temperature dome valve (4) are provided with a wear-resistant ceramic coating.

4. The high-temperature direct reduction sponge iron heat transfer device according to claim 3, characterized in that, The outer shell (51) of the pump body (5) includes an inner working layer (511), a middle permanent layer (512), and an outer thermal insulation layer (513).

5. The high-temperature direct reduction sponge iron heat conveying device according to claim 4, characterized in that, The working layer (511) is made of slag-resistant and wear-resistant castable with a thickness of 50-100 mm.

6. The high-temperature direct reduction sponge iron heat conveying device according to claim 4, characterized in that, The permanent layer (512) is made of heat-resistant and wear-resistant spray paint with a thickness of 30-50 mm.

7. The high-temperature direct reduction sponge iron heat conveying device according to claim 4, characterized in that, The thermal insulation layer (513) is made of lightweight mullite and has a thickness of 50-80 mm.

8. The high-temperature direct reduction sponge iron heat conveying device according to claim 7, characterized in that, The conveying pipeline and elbow (6) includes an inner pipeline layer (63), a middle pipeline layer (62), and an outer pipeline layer (61).

9. The high-temperature direct reduction sponge iron heat conveying device according to claim 8, characterized in that, The inner layer (63) of the pipe is made of rare earth alloy, the middle layer (62) of the pipe is filled with aluminum silicate thermal insulation material, and the outer shell layer (61) of the pipe is made of No. 20 steel.

10. The high-temperature direct reduction sponge iron heat conveying device according to claim 9, characterized in that, The delivery valve group (8), the blowing valve group (9), and the plugging valve group (10) are controlled by an automated system.

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