Combined shaft furnace installation for green ball charging

Abstract

This utility model relates to a combined vertical shaft furnace device for feeding green pellets, belonging to the field of low-carbon metallurgy or hydrogen metallurgy. This device achieves seamless integration of green pellet sintering and reduction reactions through vertical coupling of the pelletizing vertical furnace and the reduction vertical furnace. Specifically, green pellets are conveyed to the pelletizing vertical furnace via a feeding system, sintered into hot pellets in an oxidizing atmosphere, and then directly transferred to the reduction vertical furnace via a sealed valve assembly and an intermediate tank, where they react with the introduced reducing gas to produce direct reduced iron. Key components of the device include the pelletizing vertical furnace inlet pipe, flue gas emission system, sealed valves, and a material distributor, ensuring independent environmental isolation between the two furnaces and continuous material transport. This solution reduces repeated energy consumption by eliminating the cooling and reheating stages in traditional processes; the highly compact equipment reduces construction and maintenance costs; and the sensible heat of the hot pellets is directly used for the reduction reaction, improving overall thermal efficiency. Furthermore, the exhaust gas can be recycled, providing an efficient, economical, and environmentally friendly technical path for the low-carbon transformation of the steel industry.

Description

Technical Field

[0001] This utility model belongs to the field of low-carbon metallurgy or hydrogen metallurgy technology, and relates to a combined vertical furnace device for feeding green pellets into the furnace. Background Technology

[0002] With the development of global low-carbon metallurgical technologies, gas-based vertical shaft furnace technology has become an important direction for the green transformation of the steel industry due to its low emission characteristics. Traditional gas-based vertical shaft furnace technology typically employs a step-by-step processing mode: green pellets are first sintered into hot pellets in an oxidizing atmosphere in a pelletizing vertical shaft furnace, then cooled through a cooling system to form cold pellets, which are then transferred to a reduction vertical shaft furnace for heating and reduction. While this process achieves the metallurgical processing of pellets, it has significant drawbacks. First, in the traditional pelletizing vertical shaft furnace process, hot pellets lose a large amount of residual heat during cooling, and cold pellets need to be reheated to a high temperature before entering the reduction vertical shaft furnace, resulting in repeated energy consumption and waste. Furthermore, the addition of pellet cooling equipment increases investment costs. Second, the addition of cooling and preheating sections in the reduction vertical shaft furnace not only prolongs the process flow but also increases the overall height of the unit, increasing the complexity and cost of plant construction and equipment maintenance. In addition, multi-stage material transfer easily introduces thermal efficiency losses, reduces pellet strength, increases losses, and the connection between equipment relies on complex sealing and temperature control systems, further increasing operating energy consumption and the risk of failure.

[0003] While existing technologies have attempted to optimize the vertical shaft furnace structure, such as by improving the distribution of reducing gas or optimizing pellet composition to enhance reaction efficiency, these improvements have not fundamentally solved the energy consumption problem in the cooling and reheating stages. Some processes attempt to shorten cooling time or employ waste heat recovery technology, but the energy-saving effect is limited by equipment layout and thermodynamic efficiency. Therefore, how to achieve seamless connection between pellet sintering and reduction processes through process integration and equipment innovation, and avoid heat loss in the intermediate cooling stage, has become a pressing technical challenge in the field of low-carbon metallurgy. Utility Model Content

[0004] In view of this, the purpose of this utility model is to provide a combined vertical furnace device for feeding green pellets into the furnace, which aims to break through the limitations of traditional processes through structural innovation and process integration, and provide a new solution for the high efficiency and energy saving of gas-based vertical furnace processes.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A combined vertical furnace device for feeding green pellets into the furnace, wherein a feeding unit is arranged sequentially along the material transport direction, including a pellet vertical furnace, an intermediate tank, a material distributor, a reduction vertical furnace, and a DRI discharge port.

[0007] Optionally, the pelletizing vertical shaft furnace is equipped with at least two pelletizing vertical shaft furnace inlet pipes and at least one flue gas emission system.

[0008] Optionally, a pellet discharge port is provided on the pellet vertical furnace.

[0009] Optionally, the pellet outlet is connected to the intermediate tank via a pellet discharge valve.

[0010] Optionally, the pelletizing vertical furnace is connected to the intermediate tank via an upper sealing valve.

[0011] Optionally, the intermediate tank is connected to the fabric distributor via a lower sealing valve.

[0012] Optionally, the reduction shaft furnace is provided with at least one reduction main pipe and at least one gas outlet pipe.

[0013] The beneficial effects of this utility model are as follows:

[0014] This utility model's combined gas-based vertical shaft furnace process achieves efficient coupling of pellet sintering and reduction reactions through structural innovation and process integration, demonstrating significant advantages in energy saving, equipment simplification, and operating cost optimization, specifically in the following aspects:

[0015] 1. Significant energy-saving effect, reducing repeated energy consumption.

[0016] In traditional processes, hot pellets need to be cooled in a cooling section to form cold pellets, and then transferred to a reduction shaft furnace via conveying equipment for reheating to the reduction temperature. This process not only wastes a large amount of waste heat but also requires additional energy for secondary heating. Furthermore, the traditional pelletizing shaft furnace process increases equipment investment due to the added cooling and preheating systems. This solution connects the pelletizing shaft furnace and the reduction shaft furnace directly in series, using a sealed valve and intermediate tank to achieve continuous transfer of high-temperature pellets, eliminating the cooling and preheating stages. After sintering, the pellets directly enter the reduction shaft furnace at a high temperature, and their sensible heat is fully retained and used for subsequent reduction reactions. It is estimated that this design can reduce heating energy consumption by approximately 30%-40%, significantly reducing the overall energy consumption per unit product, meeting the core requirements of low-carbon metallurgy.

[0017] 2. The process flow is shortened, and equipment investment and maintenance costs are reduced.

[0018] In traditional processes, the pelletizing shaft furnace and the reduction shaft furnace are set up independently, requiring separate cooling sections, preheating sections, and supporting conveying systems. This results in an increase in the overall equipment height (usually exceeding 50 meters) and high plant construction costs. This solution uses a compact design to vertically stack the two shaft furnaces and utilizes an intermediate tank and sealing valves to achieve the closed-loop transfer of hot pellets, eliminating redundant facilities such as cooling towers and preheaters. The overall height of the unit can be reduced, significantly decreasing the amount of steel structure and civil engineering work. Furthermore, the simplified process reduces the number of equipment (such as eliminating cooling fans and reheat burners), lowering not only initial investment but also the complexity of later maintenance and spare parts costs.

[0019] 3. Improved thermal efficiency, reducing heat loss and emissions.

[0020] In traditional processes, heat loss is easily caused during pellet cooling and reheating, and the efficiency of flue gas waste heat recovery is limited. This solution directly connects the pelletizing vertical shaft furnace and the reduction vertical shaft furnace, allowing for centralized treatment of sintering flue gas (including high-temperature waste heat) and reduction tail gas (such as gas discharged from the gas outlet pipe), facilitating the integration of waste heat recovery systems (such as waste heat boilers or gas recycling devices). Simultaneously, the design of the sealing valve and intermediate tank effectively isolates the reaction environments (oxidizing and reducing environments) of the two vertical furnaces, preventing gas cross-contamination, thus ensuring reaction efficiency and reducing heat loss due to leakage.

[0021] 4. Enhanced production continuity and stability

[0022] In traditional processes, the conveying of cold pellets is easily affected by factors such as ambient temperature and humidity, which may lead to agglomeration or pulverization, resulting in uneven feeding into the reduction shaft furnace. This solution, through the synergistic action of the distributor and intermediate tank, ensures that high-temperature pellets are evenly distributed to the reduction shaft furnace at a stable flow rate, avoiding material loss associated with cold conveying. Furthermore, the independent sealing design of the two shaft furnaces (such as upper and lower sealing valves) allows for separate control of process parameters (such as gas flow rate and temperature) for the oxidation sintering and reduction reactions, resulting in more precise production process control and significantly improved product quality consistency (such as DRI metallization rate).

[0023] 5. Improved environmental friendliness and reduced carbon emissions

[0024] This solution optimizes the process, reducing the consumption of fossil fuels (such as natural gas or coal) in secondary heating and directly lowering CO2 emissions. Simultaneously, the flue gas emission system of the pelletizing shaft furnace and the gas outlet pipe of the reduction shaft furnace can be integrated with desulfurization, denitrification, and carbon capture devices, achieving centralized purification and resource utilization of the tail gas. For example, the gas produced after the reduction reaction is rich in CO and H2 and can be recycled back to the main reduction pipe through a circulation system, further reducing the demand for fresh reducing gas and forming a closed-loop energy-saving mode. The overall carbon emissions of this process are reduced compared to traditional methods, providing a practical and feasible technical path for the steel industry to achieve its "dual carbon" goals.

[0025] 6. Highly adaptable and can be extended to various raw materials and processes.

[0026] The structural design of this unit is highly flexible, compatible with green pellet feedstocks of different compositions (such as high-grade iron concentrate or carbon-containing composite pellets). By adjusting the gas composition (such as the air-to-fuel ratio) in the pelletizing shaft furnace inlet pipe and the reducing gas ratio (such as a mixture of H2 and CO) in the reduction main pipe, it can adapt to diverse metallurgical needs. Furthermore, this combined unit can be integrated with cutting-edge technologies such as hydrogen metallurgy and oxy-fuel combustion, reserving interfaces for future low-carbon process upgrades and possessing broad application prospects.

[0027] In summary, the combined gas-based vertical shaft furnace process of this solution has achieved multi-dimensional breakthroughs in energy saving and consumption reduction, equipment simplification, thermal efficiency improvement, production stability and environmental benefits through structural innovation and process reengineering, providing an efficient, economical and sustainable technical solution for the green transformation of the steel industry.

[0028] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description

[0029] To make the objectives, technical solutions, and advantages of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, wherein:

[0030] Figure 1 This is a schematic diagram of the combined vertical furnace unit for feeding green pellets into the furnace according to this scheme.

[0031] Figure labels: 1. Feeding system, 2. Pelletizing vertical furnace, 3. Pelletizing vertical furnace inlet pipe (1), 4. Pelletizing vertical furnace inlet pipe (2), 5. Flue gas emission system, 6. Pellet discharge port, 7. Pellet discharge valve, 8. Upper sealing valve, 9. Intermediate tank, 10. Lower sealing valve, 11. Distributor, 12. Reduction vertical furnace, 13. Reduction main pipe, 14. DRI discharge port, 15. Gas outlet pipe. Detailed Implementation

[0032] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model 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. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0035] Please see Figure 1 The combined gas-based vertical shaft furnace unit in this scheme achieves continuous production of green pellet sintering and reduction reactions through the vertical coupling design of the pelletizing vertical shaft furnace and the reduction vertical shaft furnace. The following is a combination of... Figure 1 The specific embodiments of the present invention will be described in detail to ensure that all technical features in the claims are covered.

[0036] Equipment structure and process flow

[0037] 1. Feeding and sintering stage

[0038] Green pellets are continuously conveyed to the top of the pelletizing shaft furnace 2 via the feeding system 1. The interior of the pelletizing shaft furnace 2 is an oxidizing environment, with inlet pipes 3 and 4 on both sides, which respectively introduce preheated air and fuel (such as natural gas or coal gas) into the furnace to form a high-temperature oxidizing atmosphere. As the green pellets move downwards within the furnace, they undergo a sintering reaction with the gases supplied by the inlet pipes 3 and 4, forming hot pellets with a certain strength. After sintering, the hot pellets are discharged through the pellet outlet 6, and the flow rate is controlled by the pellet discharge valve 7.

[0039] 2. Hot pellet transfer and sealing control

[0040] The upper sealing valve 8 below the pellet discharge valve 7 and the intermediate tank 9 form a sealed transition section. After the hot pellets enter the intermediate tank 9 through the upper sealing valve 8, the lower sealing valve 10 opens, conveying the pellets to the distributor 11. The upper sealing valve 8 and the lower sealing valve 10 open and close alternately to ensure gas environment isolation between the pellet vertical furnace 2 and the reduction vertical furnace 12. The volume design of the intermediate tank 9 must meet the buffering requirements of the hot pellets to avoid gas pressure fluctuations between the two furnaces affecting reaction stability.

[0041] 3. Reduction reaction and DRI formation

[0042] The distributor 11 evenly distributes the hot pellets to the top of the reduction shaft furnace 12. The reduction shaft furnace 12 is circulated with reducing gas (such as pure H2 or a mixture of H2 and CO, the ratio of which is adjustable) through the reduction main pipe 13, maintaining a reducing environment inside the furnace. As the hot pellets move downwards within the furnace, they undergo a reduction reaction with the reducing gas to produce direct reduced iron (DRI). After the reaction is complete, the DRI is discharged from the DRI discharge port 14 at the bottom of the reduction shaft furnace 12 and enters subsequent processing steps.

[0043] 4. Gas treatment and energy recovery

[0044] The flue gas (containing CO2, H2O, etc.) generated by the sintering reaction in the pelletizing shaft furnace 2 is centrally discharged through the flue gas emission system 5, which can be connected to a waste heat boiler, heat exchanger, or carbon capture device to achieve waste heat utilization and emission reduction. The tail gas (containing unreacted CO, H2, and a small amount of CO2) after the reaction in the reduction shaft furnace 12 is discharged through the gas outlet pipe 15. After purification, it can be returned to the reduction main pipe 13 through the circulation system, or used as fuel to supplement the pelletizing shaft furnace inlet pipe 4, forming a closed-loop temperature control mode and reducing the consumption of reducing gas.

[0045] Key component functions and collaboration

[0046] Sealing valve system: The upper sealing valve 8 and the lower sealing valve 10 are made of high-temperature resistant materials (such as silicon carbide ceramics) and are rapidly opened and closed by hydraulic or pneumatic drive. When the two valves operate alternately, the intermediate tank 9 is always in a sealed state, ensuring that the oxidizing gas in the pelletizing shaft furnace 2 and the reducing gas in the reduction shaft furnace 12 do not interfere with each other and maintain the independence of their respective reaction environments.

[0047] The feeder 11 adopts a rotating feeder or a multi-layer grid structure to ensure that the hot pellets are evenly spread on the cross-section of the reduction shaft furnace 12, avoiding local airflow short circuits or uneven reactions.

[0048] Intermediate tank 9: Its interior is lined with high-temperature resistant lining (such as high-alumina refractory bricks), and its volume design needs to match the discharge frequency of the pellet vertical furnace 2 to achieve temporary storage and smooth transition of hot pellets.

[0049] Operating parameters and control

[0050] Gas flow control: The gas flow rates of the pellet vertical furnace inlet pipes 3 and 4 are adjusted according to the green pellet composition and sintering temperature requirements. For example, increasing the fuel ratio can accelerate the sintering reaction. The reducing gas flow rate and ratio (H2 / CO) of the reduction main pipe 13 are dynamically adjusted according to the DRI metallization rate target.

[0051] Temperature linkage: The sintering temperature of the pellet vertical furnace 2 is controlled by the fuel and air ratio through the gas inlet pipes 3 and 4, while the temperature of the reduction vertical furnace 12 is adjusted by the preheating temperature and flow rate of the reducing gas. The sensible heat transfer between the two furnaces through hot pellets reduces additional energy consumption.

[0052] Implementation Example

[0053] Taking iron concentrate green pellets as an example, the green pellets enter the pelletizing shaft furnace 2 via the feeding system 1. After being sintered into hot pellets, they are transferred to the reduction shaft furnace 12 via the pellet discharge valve 7, upper sealing valve 8, intermediate tank 9, and lower sealing valve 10. Reducing gas is introduced through the reduction main pipe 13 to reduce the hot pellets to DRI. The tail gas is recovered through the gas outlet pipe 15, with part of it returned to the reduction main pipe 13 for recycling, and the remainder used as fuel to assist in heating the pelletizing shaft furnace inlet pipe 4.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of this technical solution, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A combined shaft furnace installation for green ball charging, characterized in that: The following components are arranged sequentially along the material transport direction: feeding unit (1), pellet vertical furnace (2), intermediate tank (9), material distributor (11), reduction vertical furnace (12), and DRI discharge port (14).

2. A combined shaft furnace arrangement for green ball feed-in according to claim 1, characterized in that: The pelletizing vertical furnace (2) is equipped with at least two pelletizing vertical furnace inlet pipes (3, 4) and at least one flue gas emission system (5).

3. A combination shaft plant for green ball charging according to claim 1, characterized in that: The pellet discharge port (6) is provided on the pellet vertical furnace (2).

4. The combined vertical furnace device for feeding green pellets into the furnace according to claim 3, characterized in that: The pellet outlet (6) is connected to the intermediate tank (9) through the pellet discharge valve (7).

5. The combined vertical furnace device for feeding green pellets into the furnace according to claim 1, characterized in that: The pelletizing vertical furnace (2) is connected to the intermediate tank (9) via an upper sealing valve (8).

6. The combined vertical furnace device for feeding green pellets into the furnace according to claim 1, characterized in that: The intermediate tank (9) is connected to the distributor (11) via a lower sealing valve (10).

7. The combined vertical furnace device for feeding green pellets into the furnace according to claim 1, characterized in that: The reduction shaft furnace (12) is provided with at least one reduction main pipe (13) and at least one gas outlet pipe (15).

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