A hot blast stove double flue staged preheating device
By using a dual-flue staged preheating device for hot air furnaces, the problem of inefficient heat exchange after mixing exhaust gases at different temperatures is solved, achieving efficient utilization of waste heat from exhaust gases, improving heat exchange efficiency, and reducing fuel consumption and operating costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGDONG XINXING DUCTILE IRON PIPES CO LTD
- Filing Date
- 2025-07-28
- Publication Date
- 2026-06-16
AI Technical Summary
In existing technologies, the mixing of exhaust gases at different temperatures cannot achieve efficient heat exchange, resulting in the underutilization of the waste heat from the high-temperature exhaust gases, low heat exchange efficiency, and increased energy consumption and operating costs.
A dual-flue staged preheating device for hot air furnaces is adopted. Waste gases of different temperatures are separated through high-temperature and low-temperature exhaust gas channels, and a stepped heat exchange is carried out by a series of front-end high-temperature heat exchangers and rear-end low-temperature heat exchangers to achieve efficient utilization of waste heat from exhaust gases.
It significantly improves heat exchange efficiency, reduces fuel consumption and cost per ton of iron, and meets the industry's demand for energy conservation and emission reduction.
Smart Images
Figure CN224365361U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of waste heat utilization technology of hot blast stove exhaust gas, specifically relating to a dual-flue staged preheating device for hot blast stove. Background Technology
[0002] like Figure 1 As shown, in the field of iron and steel smelting, blast furnaces are typically equipped with three hot blast stoves, operating in a "two-burning-one-sending" cyclical mode (the first two are for burning, and the last one is for sending blast). That is, at any given time, two hot blast stoves are in the burning state (generating heat), and one is in the sending blast state (providing hot air to the blast furnace). The working cycle of each hot blast stove is approximately 180 minutes, including 60 minutes of sending blast, 15 minutes of furnace replacement, and 105 minutes of burning.
[0003] The hot blast stove consumes gas and air during combustion, and the exhaust gas (temperature range 200-400℃) produced contains a large amount of waste heat. Conventional technology introduces the exhaust gas into the heat exchanger 200 through a single large flue 100, using the waste heat to preheat the gas and air required for combustion, thereby saving energy.
[0004] However, existing technology has significant limitations: The two hot blast stoves operating simultaneously have a 60-75 minute time difference in firing time, resulting in different exhaust gas temperatures. The exhaust gas temperature from the stoves just entering the firing stage is 200-300℃, while the temperature from stoves firing for more than 60 minutes can reach 300-400℃. Traditional systems collect exhaust gas through a single flue, leading to the mixing of exhaust gases at different temperatures (the mixed temperature is approximately 250-350℃). This mixed exhaust gas, upon entering the heat exchanger, cannot efficiently exchange heat according to the temperature gradient, resulting in underutilization of the waste heat from the high-temperature exhaust gas and low heat exchange efficiency.
[0005] The aforementioned problems directly lead to increased energy consumption and higher blast furnace operating costs, which contradicts the current industry demand for energy conservation and emission reduction. Therefore, how to achieve temperature-based utilization of waste gas and improve waste heat recovery efficiency has become a key direction for improving hot blast stove preheating technology. Utility Model Content
[0006] The present invention aims to solve the technical problem in the prior art where mixing waste gases at different temperatures for heat exchange results in the underutilization of the waste heat from the high-temperature waste gas, low heat exchange efficiency, and increased energy consumption due to insufficient utilization of waste heat, thus increasing operating costs and failing to meet energy-saving requirements.
[0007] To achieve the above objectives, this utility model provides the following technical solution:
[0008] A dual-flue staged preheating device for a hot blast stove includes:
[0009] There are three hot blast stoves, which are heating equipment supporting the blast furnace. The hot blast stoves generate heat through firing to provide hot blast for the blast furnace. The waste gas generated during the firing process of the hot blast stoves can be used to preheat the gas / air required for firing. Each hot blast stove is connected to two waste gas branch pipes;
[0010] The waste gas channel is used to separate waste gas at different temperatures, providing a waste gas source with temperature separation for subsequent staged heat exchange. The waste gas channel includes a high-temperature main flue for receiving waste gas at 300 - 400 °C and a low-temperature main flue for receiving waste gas at 200 - 300 °C. The flow direction of the waste gas to the high-temperature main flue or the low-temperature main flue is controlled by valves on the waste gas branch pipes;
[0011] The heat exchange system is composed of a front-end high-temperature heat exchanger and a rear-end low-temperature heat exchanger connected in series. Using the separated high- and low-temperature waste gas, heat exchange with the gas / air to be preheated is carried out twice to improve the heat exchange efficiency and make full use of the waste heat of the waste gas.
[0012] Preferably, two of the three hot blast stoves are in the firing state and one is in the air supply state.
[0013] Preferably, high-temperature waste gas valves and low-temperature waste gas valves are respectively installed corresponding to the two waste gas branch pipes connected to each hot blast stove.
[0014] Preferably, the front-end high-temperature heat exchanger is connected to the high-temperature main flue, and the low-temperature heat exchanger is connected to the low-temperature main flue and the waste gas channel after high-temperature heat exchange of the front-end high-temperature heat exchanger.
[0015] Preferably, a normal-temperature gas / air access pipe is provided on the rear-end low-temperature heat exchanger. After the rear-end low-temperature heat exchanger conducts primary heat exchange on the gas / air, it is connected to the front-end high-temperature heat exchanger through the primary heat exchange gas / air connecting pipe on the rear-end low-temperature heat exchanger. After the front-end high-temperature heat exchanger conducts secondary heat exchange on the gas / air, it is discharged through the secondary heat exchange gas / air discharge pipe on the front-end high-temperature heat exchanger.
[0016] Preferably, the flue pipe connected to the low-temperature heat exchanger is connected to the chimney.
[0017] Preferably, the cross-sectional area of the high-temperature main flue is one-half of the cross-sectional area of the low-temperature main flue.
[0018] Compared with the prior art, the technical effects and advantages of the present utility model are:
[0019] This invention solves the problem of mixing waste gases at different temperatures in traditional technologies through an innovative dual-flue design. Traditional systems collect waste gases at different temperatures from two furnaces through a single large flue, resulting in heat neutralization. In contrast, this device uses two flues—one for high temperatures and one for low temperatures—combined with temperature sensors and automatic valve control to achieve precise separation of the high-temperature and low-temperature waste gases. This provides a clear temperature-dependent heat source foundation for subsequent efficient heat exchange, preventing waste heat from the outset.
[0020] Traditional technologies use a single heat exchanger to perform one-time heat exchange on mixed waste gas, which cannot fully utilize the heat of high-temperature waste gas. This device uses a front-end high-temperature heat exchanger and a rear-end low-temperature heat exchanger connected in series, allowing room-temperature gas or air to be preheated by the low-temperature waste gas first, and then deeply heated by the high-temperature waste gas, forming a stepped heat exchange process. This ensures that the heat of waste gas at different temperatures can be matched and utilized, significantly improving the waste heat recovery effect.
[0021] Traditional technologies lack dynamic adaptation to exhaust gas temperature, and the heat exchange process is passive and fixed. This device is equipped with a temperature sensor at the exhaust gas branch pipe valve, which can automatically switch the flue according to the real-time exhaust gas temperature, ensuring that low-temperature exhaust gas enters the low-temperature flue and high-temperature exhaust gas enters the high-temperature flue. Moreover, the switching process does not affect the normal operation of the hot air furnace, thus achieving precise coordination between exhaust gas diversion and heat exchange.
[0022] Traditional technologies suffer from low heat exchange efficiency, resulting in limited preheating effects for gas and air, which indirectly increases fuel consumption and operating costs. This device improves preheating efficiency, reduces the amount of fuel required for furnace firing, and lowers the cost per ton of iron, meeting the energy conservation and emission reduction development needs of the metallurgical industry. It achieves green production while improving production efficiency. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the existing technology;
[0024] Figure 2 This is a schematic diagram of the structure of this utility model.
[0025] In the diagram: 1. Hot blast stove; 2. High-temperature flue; 3. Low-temperature flue; 4. Front-end high-temperature heat exchanger; 5. Rear-end low-temperature heat exchanger; 6. Exhaust gas branch pipe; 7. High-temperature exhaust gas valve; 8. Low-temperature exhaust gas valve; 9. Exhaust gas passage; 10. Ambient temperature gas / air inlet pipe; 11. Primary heat exchange gas / air connecting pipe; 12. Secondary heat exchange gas / air outlet pipe; 13. Flue pipe; 14. Chimney;
[0026] 100. Main flue; 200. Heat exchanger; 300. Waste gas valve; Detailed Implementation
[0027] The technical solutions of the present utility model 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 utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0028] The following combination Figure 2 This application will be described in further detail.
[0029] This application discloses a dual-flue staged preheating device for a hot blast stove 1, comprising a hot blast stove 1 unit, a waste gas channel 9 system, and a heat exchange system. This dual-flue staged preheating device for the hot blast stove 1 is designed for the efficient utilization of waste heat from the waste gas of the blast furnace hot blast stove 1. Through the coordinated operation of the hot blast stove 1 unit, the waste gas channel 9 system, and the heat exchange system, it achieves the functions of staged collection and gradient heat exchange of waste gas, as detailed below:
[0030] The hot blast stove unit 1 is equipped with 3 hot blast stoves 1, which serve as supporting heating equipment for the blast furnace and generate hot air through furnace firing to supply the blast furnace.
[0031] Operating mode: adopts a "two-burner-one-supplier" cycle (two furnaces generate heat, one furnace supplies air for energy), and the working cycle of a single hot blast stove is 180 minutes (60 minutes of air supply, 15 minutes of furnace replacement, and 105 minutes of furnace burning).
[0032] Waste gas utilization characteristics: The furnace process generates waste gas at 200-400℃, which can be preheated with the coal gas and air it needs through heat exchange;
[0033] The exhaust gas generated during the firing process of the hot blast stove 1 can be used to preheat the gas / air required for firing. Each hot blast stove 1 is connected to two exhaust gas branch pipes 6. Each of the two exhaust gas branch pipes 6 connected to the hot blast stove 1 is equipped with a high-temperature exhaust gas valve 7 and a low-temperature exhaust gas valve 8 respectively.
[0034] The exhaust gas passage 9 in the exhaust gas passage 9 system is used to separate exhaust gases at different temperatures, providing a precise heat source for staged heat exchange.
[0035] The exhaust gas passage 9 includes a high-temperature flue 2 and a low-temperature flue 3;
[0036] High-temperature flue 2: Receives exhaust gas at 300-400℃, with a cross-sectional area that is half that of the low-temperature flue (adapted to the flow characteristics of high-temperature exhaust gas);
[0037] Low-temperature flue 3: receives exhaust gas at 200-300℃ and can be compatible with two hot blast furnaces 1 exhausting simultaneously;
[0038] Each exhaust gas branch pipe 6 is equipped with a high-temperature exhaust gas valve 7 and a low-temperature exhaust gas valve 8. Combined with the temperature sensor at the front end of the valve, automatic flow guidance is achieved (the low-temperature exhaust gas valve 8 is opened when the temperature is <300℃, and the high-temperature exhaust gas valve 7 is opened when the temperature is ≥300℃).
[0039] The heat exchange system consists of a front-end high-temperature heat exchanger 4 and a rear-end low-temperature heat exchanger 5 connected in series, forming a stepped heat exchange process. The separated high- and low-temperature waste gases are exchanged with the preheated coal gas / air in two stages to improve heat exchange efficiency and fully utilize the waste heat. The front-end high-temperature heat exchanger 4 is connected to the high-temperature flue 2 to treat waste gas at 300-400℃; the rear-end low-temperature heat exchanger 5 is connected to the low-temperature flue 3 and receives the cooled waste gas after heat exchange by the front-end heat exchanger.
[0040] The rear heat exchanger is equipped with a normal temperature gas / air inlet pipe 10, and the front heat exchanger is equipped with a secondary heat exchange gas / air outlet pipe 12. The gas / air flow between the front high temperature heat exchanger 4 and the rear low temperature heat exchanger 5 is realized through the primary heat exchange gas / air connecting pipe 11.
[0041] The specific connections are as follows: the front-end high-temperature heat exchanger 4 is connected to the high-temperature flue 2, and the low-temperature heat exchanger is connected to the low-temperature flue 3 and the exhaust gas passage 9 after high-temperature heat exchange by the front-end high-temperature heat exchanger 4. The rear-end low-temperature heat exchanger 5 is equipped with a normal temperature gas / air inlet pipe 10. After the initial heat exchange of gas / air by the rear-end low-temperature heat exchanger 5, it is connected to the front-end high-temperature heat exchanger 4 through the initial heat exchange gas / air connecting pipe 11 on the rear-end low-temperature heat exchanger 5. After the secondary heat exchange of gas / air by the front-end high-temperature heat exchanger 4, it is discharged through the secondary heat exchange gas / air outlet pipe 12 on the front-end high-temperature heat exchanger 4. The flue pipe 13 connected to the low-temperature heat exchanger is connected to the chimney 14.
[0042] The dual-flue staged preheating device of the hot blast stove 1 achieves efficient utilization of waste heat through a three-step cycle of "waste gas temperature monitoring - automatic flue switching - gradient heat exchange". The specific process is based on hot blast stoves 1#, 2#, and 3#. Figure 2 Taking furnaces #1 and #2 as examples, and furnace #3 as an example:
[0043] (1) Waste gas staged flow diversion process
[0044] Initial state: Hot blast stove #3 has finished burning (exhaust gas around 400℃) and is ready to switch to air supply; Hot blast stove #1 has been burning for more than 60 minutes (exhaust gas around 300℃), and Hot blast stove #2 is about to start burning.
[0045] Flue switching: Because the temperature of hot air furnace 1 has reached the standard, the high temperature exhaust gas valve 7 is automatically opened and the low temperature exhaust gas valve 8 is closed, and the exhaust gas is transferred to the high temperature flue 2;
[0046] Cyclic switching: After the No. 3 hot blast stove 1 switches to air supply, the No. 2 hot blast stove 1 starts to burn (the initial exhaust gas temperature is about 200°C), and the low temperature exhaust gas valve 8 is automatically opened, and the exhaust gas enters the low temperature flue 3; subsequently, as the burning time of the No. 2 stove increases (reaching more than 60 minutes), it switches to the high temperature flue 2, forming a periodic cycle.
[0047] (2) Gradient heat transfer process
[0048] Initial heat exchange (low-temperature heat exchanger 5 at the rear end): ambient temperature gas / air first enters the rear end heat exchanger and mixes with the 200-300℃ exhaust gas from the low-temperature flue 3 and the cooled exhaust gas discharged from the front end heat exchanger to complete the initial heating.
[0049] Secondary heat exchange (front-end high-temperature heat exchanger 4): The preheated gas / air enters the front-end heat exchanger and undergoes deep heat exchange with the 300-400℃ exhaust gas in the high-temperature flue 2 to achieve secondary heating.
[0050] Exhaust gas emissions: After two heat exchanges (with a significantly reduced temperature), the exhaust gas is introduced into the chimney 14 via the flue pipe 13 connected to the low-temperature heat exchanger and discharged (total emissions are approximately 63,000 Nm³). 3 / h, at 400m 3 (Taking the blast furnace as an example).
[0051] Temperature sensors are installed at the front end of the high-temperature exhaust valve 7 and low-temperature exhaust valve 8 on the exhaust branch pipe 6 of each hot blast stove 1. When the hot blast stove 1 enters the furnace firing state:
[0052] 1. When the exhaust gas temperature is <300℃, the low-temperature exhaust gas valve 8 will automatically open and remain open, while the high-temperature exhaust gas valve 7 will remain closed.
[0053] 2. When the exhaust gas temperature is ≥300℃, the high-temperature exhaust gas valve 7 will be automatically opened and kept open, and then the low-temperature exhaust gas valve 8 will be automatically closed.
[0054] As shown in Table 1, compared with the traditional single-flue preheating system (heat exchange at 250-350℃ after exhaust gas mixing), this device achieves significant improvement through "temperature separation + gradient utilization":
[0055] Table 1. Comparison of core technical indicators between traditional hot blast stove preheating system and dual-flue hot blast stove staged preheating system
[0056] index Traditional solution This plan Increase Air preheating temperature ℃ 170℃ 200℃ +30℃ Gas preheating temperature (°C) 175℃ 195℃ +20℃ Theoretical wind temperature Increase by 20°C or more Fuel consumption per ton of iron Reduce iron by 2 kg / ton Cost per ton of iron Reduce iron price by 3 yuan / ton
[0057] By avoiding the temperature neutralization problem caused by mixing high and low temperature exhaust gases, the high temperature exhaust gas is allowed to focus on heating the medium that has already been preheated (reducing heat loss), while the low temperature exhaust gas undertakes the basic preheating, thereby improving the heat exchange efficiency by more than 30%.
[0058] The core working principle of the dual-flue staged preheating device of the hot blast stove 1 is to achieve efficient utilization of waste heat from exhaust gas through staged collection and gradient heat exchange. The hot blast stove 1 unit operates in a "two-burning-one-sending" cycle. The two hot blast stoves 1 generate exhaust gas at different temperatures. Through the high-temperature and low-temperature flues 3 and corresponding valves of the exhaust gas channel 9 system, combined with temperature sensors, the exhaust gas is automatically separated (high-temperature exhaust gas enters high-temperature flue 2, and low-temperature exhaust gas enters low-temperature flue 3). The front-end high-temperature heat exchanger 4 and the rear-end low-temperature heat exchanger 5 of the heat exchange system work in series. The ambient temperature gas or air first exchanges heat with the low-temperature exhaust gas in the rear-end low-temperature heat exchanger 5, and then enters the front-end high-temperature heat exchanger 4 to exchange heat with the high-temperature exhaust gas for the second time, finally completing the step-by-step heating. The exhaust gas after heat exchange is discharged through the chimney 14.
[0059] Compared to traditional single-flue preheating technology, this device solves the key problem of "exhaust gas temperature neutralization." Existing technologies mix exhaust gases of different temperatures through a single large flue for heat exchange, failing to fully utilize the waste heat of high-temperature exhaust gases. In contrast, this device separates exhaust gases of different temperatures through dual flues, allowing high-temperature exhaust gases to focus on heating the already preheated medium, while low-temperature exhaust gases undertake basic preheating. This avoids heat waste, significantly improves heat exchange efficiency, and enables more complete utilization of the waste heat from the exhaust gases.
[0060] In terms of operational economy and energy efficiency, this device represents a significant improvement over existing technologies. Existing technologies suffer from low heat exchange efficiency, resulting in limited preheating effects for gas and air, indirectly increasing fuel consumption and operating costs. This device, through gradient heat exchange, enhances the preheating temperature of gas and air, thereby increasing the blast furnace blast temperature, reducing the amount of fuel required for furnace operation, and lowering the cost per ton of iron. Simultaneously, it meets industry requirements for energy conservation and emission reduction, creating a dual advantage in energy utilization and cost control.
[0061] In terms of operational economy and energy efficiency, this device represents a significant improvement over existing technologies. Existing technologies suffer from low heat exchange efficiency, resulting in limited preheating effects for gas and air, indirectly increasing fuel consumption and operating costs. This device, through gradient heat exchange, enhances the preheating temperature of gas and air, thereby increasing the blast furnace blast temperature, reducing the amount of fuel required for furnace operation, and lowering the cost per ton of iron. Simultaneously, it meets industry requirements for energy conservation and emission reduction, creating a dual advantage in energy utilization and cost control.
[0062] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A dual-flue staged preheating device for a hot blast stove, characterized in that, include: Three hot blast stoves (1) are provided as heating equipment for the blast furnace. The hot blast stoves (1) generate heat by burning the furnace to provide hot air for the blast furnace. The waste gas generated during the burning process of the hot blast stoves (1) can be used to preheat the gas / air required for burning the furnace. Each hot blast stove (1) is connected to two waste gas branch pipes (6). The exhaust gas channel (9) is used to separate exhaust gases of different temperatures and provide a source of exhaust gas with temperature separation for subsequent staged heat exchange. The exhaust gas channel (9) includes a high-temperature flue (2) for receiving exhaust gases of 300-400℃ and a low-temperature flue (3) for receiving exhaust gases of 200-300℃. The exhaust gas flow direction to the high-temperature flue (2) or the low-temperature flue (3) is controlled by the valve on the exhaust gas branch pipe (6). The heat exchange system consists of a front-end high-temperature heat exchanger (4) and a rear-end low-temperature heat exchanger (5) connected in series. It utilizes the separated high and low temperature waste gases to exchange heat with the preheated coal gas / air in two stages to improve heat exchange efficiency and make full use of the waste heat of the waste gas.
2. The hot blast stove dual-flue staged preheating device according to claim 1, characterized in that: Two of the three hot blast stoves (1) are in the firing state, and one is in the air supply state.
3. The hot blast stove dual-flue staged preheating device according to claim 1, characterized in that: Each hot air furnace (1) has two exhaust gas branch pipes (6) connected to it, with a high-temperature exhaust gas valve (7) and a low-temperature exhaust gas valve (8) installed respectively.
4. The hot blast stove dual-flue staged preheating device according to claim 1, characterized in that: The front-end high-temperature heat exchanger (4) is connected to the high-temperature flue (2), and the low-temperature heat exchanger is connected to the low-temperature flue (3) and the exhaust gas passage (9) after high-temperature heat exchange of the front-end high-temperature heat exchanger (4).
5. A hot blast stove dual-flue staged preheating device according to claim 4, characterized in that: The low-temperature heat exchanger (5) at the rear end is provided with a normal temperature gas / air inlet pipe (10). After the gas / air undergoes initial heat exchange at the rear end, the low-temperature heat exchanger (5) is connected to the high-temperature heat exchanger (4) at the front end through the initial heat exchange gas / air connecting pipe (11) on the low-temperature heat exchanger (5). After the gas / air undergoes secondary heat exchange at the front end, the gas / air is discharged through the secondary heat exchange gas / air outlet pipe (12) on the high-temperature heat exchanger (4).
6. The hot blast stove dual-flue staged preheating device according to claim 5, characterized in that: The flue pipe (13) connected to the low-temperature heat exchanger is connected to the chimney (14).
7. A hot blast stove dual-flue staged preheating device according to claim 1, characterized in that: The cross-sectional area of the high-temperature flue (2) is half that of the low-temperature flue (3).