A dual regenerative heating furnace system to prevent flue gas flash explosion

Abstract

This invention relates to the field of regenerative heating furnace technology, specifically to a dual regenerative heating furnace system for preventing flue gas flash explosions. The system includes a heat storage box, a three-way valve, and a flue gas manifold. The heat storage box, three-way valve, and flue gas manifold are sequentially arranged along the flue gas conveying direction between the furnace output end and the main flue gas pipe. The inlet end of the heat storage box is connected to the furnace output end. Inside the heat storage box, from the inlet end towards the exhaust side, one layer of baffle bricks and nine layers of heat storage material are sequentially arranged. A fluororubber sealing strip is provided on the valve plate end face that mates with the valve port on the exhaust side of the three-way valve. Explosion relief valves are installed on the side walls of the flue gas manifold. This system helps to completely eliminate the risk of flue gas flash explosions.

Description

Technical Field

[0001] This invention relates to the field of regenerative heating furnace technology, and specifically to a dual regenerative heating furnace system for preventing flue gas flash explosion. Background Technology

[0002] Air-gas dual-regenerative heating furnaces are widely used in the metallurgical steel rolling industry, achieving full waste heat recovery from flue gas through alternating heat absorption and release by the regenerator. However, the following problems exist in actual operation: 1. The heat storage capacity of the heat storage box is insufficient. After long-term operation, the heat storage body may form a flue gas short-circuit channel due to high temperature creep, damage, etc., causing some high temperature flue gas to be directly discharged into the flue without sufficient heat exchange, resulting in high flue gas temperature.

[0003] 2. The sealing ring on the exhaust side of the flue gas reversing valve is prone to aging and failure under long-term high temperature and frequent reversing conditions. Poor sealing will cause coal gas to be drawn to the flue gas duct side, which will increase the carbon monoxide content in the flue gas.

[0004] 3. High-temperature flue gas mixed with carbon monoxide in the flue can easily cause flash explosions under specific concentration and temperature conditions, resulting in safety and equipment accidents such as explosion damage to the induced draft fan and coal smoke pipeline.

[0005] Existing technologies mostly employ single temperature monitoring or single explosion venting measures, lacking a systematic explosion protection solution from the source to the end. Summary of the Invention

[0006] The purpose of this invention is to provide a dual regenerative heating furnace system for preventing flue gas flash explosions, which helps to completely eliminate the risk of flue gas flash explosions.

[0007] The technical solution of the present invention is as follows: a dual regenerative heating furnace system for preventing flue gas flash explosion, comprising a heat storage box, a three-way valve, and a flue gas manifold. The heat storage box, the three-way valve, and the flue gas manifold are sequentially arranged between the furnace output end and the main flue gas pipe along the flue gas conveying direction. The inlet end of the heat storage box is connected to the output end of the furnace. One layer of baffle bricks and nine layers of heat storage body are sequentially arranged in the heat storage box from the inlet end towards the flue gas exhaust side. A fluororubber sealing strip is provided on the valve plate end face that cooperates with the valve port on the flue gas exhaust side of the three-way valve. Explosion relief valves are installed on the side walls of the flue gas manifold.

[0008] Furthermore, the first three layers of the nine-layer heat storage body, which are closest to the retaining brick side, are high-energy-storage heat storage bodies with round holes of 3mm diameter; the last six layers are heat storage bodies with hexagonal holes of 4.5mm diameter.

[0009] Furthermore, the high-energy-storage heat storage body is made of zirconium corundum mullite; the hexagonal-hole heat storage body is an extruded honeycomb heat storage body.

[0010] Furthermore, an annular sealing plate is provided on the outer side of the valve port on the smoke exhaust side of the three-way valve. The valve plate is connected to the valve stem, and a fluororubber sealing strip is provided on the end face of the valve plate that mates with the annular sealing plate.

[0011] Furthermore, the valve plate is provided with an annular groove with a dovetail-shaped cross-section; the cross-section of the fluororubber sealing strip is composed of a dovetail-shaped connecting part and a semi-circular sealing part, the dovetail-shaped connecting part cooperates with the annular groove, and the fluororubber sealing strip is provided with an annular recess on the side of the dovetail-shaped connecting part near the bottom of the annular groove; the semi-circular sealing part is used to cooperate with the end face of the annular sealing plate.

[0012] Furthermore, an annular protrusion is provided on the valve plate inside the fluororubber sealing strip, and the height of the annular protrusion is less than the height of the semi-circular sealing part.

[0013] Furthermore, the explosion relief valve is installed on the side wall of the flue gas manifold away from the flue gas inlet port, and each section of the flue gas manifold is equipped with an explosion relief valve.

[0014] Furthermore, the explosion relief valve is a self-returning explosion relief valve that is normally closed during operation; when the internal pressure of the flue gas manifold reaches a preset critical value, the explosion relief valve opens, and the valve cover automatically closes after the pressure is released.

[0015] Furthermore, the critical value is ≤0.1MPa.

[0016] Furthermore, the output end of the flue gas main pipe is connected to the exhaust chimney via a coal smoke induced draft fan.

[0017] Compared with the prior art, the present invention has the following advantages: (1) Systemic explosion protection: By modifying the heat storage box, modifying the reversing valve sealing ring, and adding the explosion relief valve, a complete explosion protection chain of "source cooling → process sealing → end protection" is formed. The synergistic effect of multiple links greatly reduces the probability of flue flash explosion and the risk of equipment damage.

[0018] (2) Effective reduction in flue gas temperature: The expansion and stratified configuration of the heat storage box increases the heat storage capacity and heat exchange efficiency, effectively reducing the flue gas temperature and preventing short-circuiting of the flue gas. High-energy-storage heat storage bodies have the advantages of higher strength, higher temperature resistance, higher density, and better heat storage effect compared with conventional extruded honeycomb heat storage bodies. Since the density of high-energy-storage heat storage bodies is more than 50% higher than that of conventional extruded heat storage bodies, the heat storage capacity is large. Using heavy-duty high-energy-storage cast honeycomb heat storage bodies can significantly reduce the flue gas temperature and reduce coal gas energy consumption by more than 5-10% compared with other honeycomb heat storage bodies.

[0019] (3) Reduced carbon monoxide leakage: Improved material and shape of the reversing valve sealing ring significantly reduced gas leakage to the flue side.

[0020] (4) Safety protection under extreme working conditions: The explosion relief valve automatically depressurizes and returns to its original position at the moment of flash explosion, protecting the flue and induced draft fan without the need for manual reset.

[0021] (5) High practicality: All three improvements can be implemented on existing heating furnaces without rebuilding the furnace body, making the cost controllable and highly practical. This system is suitable for the explosion-proof and safe operation of flue gas in air-gas dual regenerative heating furnaces. Attached Figure Description

[0022] Figure 1 This is a flue gas flow direction diagram for the entire system of the present invention.

[0023] Figure 2 This is a schematic diagram of the heat storage box structure of the present invention.

[0024] Figure 3 This is a partial enlarged view of the valve port of the three-way valve of the present invention.

[0025] Figure 4 This is an enlarged view of the fluororubber sealing strip and sealing plate of the present invention.

[0026] Figure 5 This is a diagram showing the installation position of the explosion relief valve of the present invention on the flue gas manifold.

[0027] In the diagram: 1-Heat storage box, 11-Baffle brick, 12-Round hole high-energy storage heat storage body, 13-Hexagonal hole heat storage body, 2-Three-way valve, 21-Valve port, 22-Valve plate, 221-Annular groove, 222-Annular protrusion, 23-Fluororubber sealing strip, 231-Dovetail-shaped connection, 232-Semi-circular sealing part, 233-Annular recess, 24-Annular sealing plate, 25-Valve stem, 31-Explosion relief valve, 3-Fluorite manifold, 4-Heating furnace chamber, 5-Fluorite main pipe, 6-Coal smoke induced draft fan, 7-Exhaust chimney. Detailed Implementation

[0028] To make the above features and advantages of the present invention more readily understood, specific embodiments are described below in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0029] refer to Figures 1 to 5 A dual-regenerative heating furnace system for preventing flue gas flash explosion includes a heat storage box 1, a three-way valve 2 (two-position three-way reversing valve), and a flue gas manifold 3. The heat storage box 1, three-way valve 2, and flue gas manifold 3 are sequentially arranged between the output end of the furnace chamber 4 and the main flue gas pipe 5 along the flue gas conveying direction. The inlet end of the heat storage box 1 is connected to the output end of the furnace chamber 4. Inside the heat storage box 1, from the inlet end towards the exhaust side, one layer of baffle bricks 11 and nine layers of heat storage materials are sequentially arranged. The height or length of the heat storage box 1 is also correspondingly increased, and the length of the area where the heat storage materials and baffle bricks 11 are installed is increased from the original 720mm to 1020mm. By increasing the heat storage capacity of the heat storage box 1, the heat exchange efficiency between the flue gas and the heat storage materials is improved, effectively reducing the exhaust gas temperature. A fluororubber (FKM) sealing strip 23 is provided on the end face of the valve plate 22 that cooperates with the valve port 21 on the exhaust side of the three-way valve 2. The temperature resistance increases from about 200°C of the raw material to about 250°C, adapting to fluctuating exhaust temperature conditions. Explosion relief valves 31 are installed on the side walls of the flue gas manifold 3. These valves provide end-point safety protection. Even in the extreme case where the first two lines of defense fail, the explosion relief valves 31 can release pressure at the moment of flash explosion, protecting the flue and induced draft fan from damage and completely eliminating the damage to the equipment from the explosion at the end.

[0030] In this embodiment, see Figure 2 The first three layers of the nine-layer heat storage body, located near the baffle brick, are high-energy-storage heat storage bodies with 3mm diameter circular holes (12). The larger surface area of ​​these circular holes increases the heat storage area and improves heat exchange efficiency. This allows for rapid heat absorption at the inlet section where the flue gas temperature is highest, minimizing the exhaust gas temperature. Simultaneously, the denser structure provides stronger creep resistance, preventing short-circuiting of the flue gas caused by creep damage during long-term operation. This also prevents high-temperature flue gas from directly entering the flue, ensuring sufficient heat exchange before discharge. This reduces the temperature of the flue gas entering the flue from the source, lowering the thermal conditions for flash explosions within the flue.

[0031] In this embodiment, the high-energy-storage heat storage body 12 is made of zirconium-corundum-mullite. For a material with a corundum-mullite ratio of 75:25, the addition of 15% ZrO2 can effectively improve the high-temperature strength of corundum-mullite, effectively reduce its creep at high temperatures, and also improve its thermal shock resistance. When the corundum-mullite material containing ZrO2 is heated to 1300℃ and quenched in water, its strength loss is significantly lower, that is, its thermal shock resistance is significantly improved.

[0032] Specifically, the use of a perforated high-energy-storage thermal accumulator 12 has the following characteristics and functions: 1. Large specific surface area: The circular hole structure can provide a larger heat exchange area within the same external dimensions, allowing for more thorough contact between the flue gas and the heat storage body; 2. High heat exchange efficiency: Under the same hole cross-sectional area and equivalent diameter, the flow resistance of the circular hole is the greatest, but at the same time the heat exchange efficiency is also the highest. The circular hole high energy storage heat storage body 12 can achieve a high temperature efficiency. 3. Strong anti-clogging ability: The cross-section of the round hole channel is smoothly transitioned and has no sharp corners, making it less prone to dust accumulation and clogging. It can intercept dust and molten material in the flue gas, avoiding blockage or burn-out of the rear thin-walled hexagonal hole heat storage body 13, and has higher operational reliability under dusty flue gas conditions.

[0033] 4. High structural strength: The thick-walled structure with round holes can withstand high-temperature creep and thermal shock impact better than the thin-walled hexagonal structure with round holes. It has high structural strength and is not easily deformed or damaged.

[0034] In this embodiment, the last six layers of the nine-layer heat storage body are hexagonal porous heat storage bodies 13 with a pore size of 4.5 mm, which can better maintain air permeability. The hexagonal porous heat storage body 13 is an extruded honeycomb heat storage body.

[0035] Specifically, the hexagonal porous heat storage body 13 has the following characteristics and functions: 1. Low resistance (pressure drop): Under the same orifice cross-sectional area and equivalent diameter, the hexagonal orifice has the lowest flow resistance and the lowest pressure loss when flue gas passes through.

[0036] 2. Good air permeability: The hexagonal hole channel is unobstructed, suitable for large flow of flue gas. After heat exchange by the front row of round hole heat storage body, the flue gas temperature has been significantly reduced. The use of hexagonal holes in the rear row can reduce system resistance, avoid fan overload, and reduce system fan power consumption.

[0037] 3. Relatively low temperature efficiency: Studies show that the temperature efficiency of hexagonal pore regenerators is relatively low among several pore types, but the pressure drop is also the smallest.

[0038] 4. Continued deep heat exchange: Although the heat exchange efficiency of a single hexagonal hole is not as good as that of a round hole, it can still continue to recover waste heat in the later stage when the flue gas temperature has decreased.

[0039] In this embodiment, see Figure 3 In order to achieve the cooperation between the fluororubber sealing strip 23 and the valve port 21, an annular sealing plate 24 is provided on the outer side of the valve port 21 on the smoke exhaust side of the three-way valve 2. The valve plate 22 is connected to the valve stem 25, and the valve plate is driven by the valve stem 25 through the driving mechanism to achieve opening and closing. A fluororubber sealing strip 23 is provided on the end face of the valve plate 22 that cooperates with the annular sealing plate 24.

[0040] In this embodiment, the cross-sectional shape of the fluororubber sealing strip 23 was optimized to ensure a tighter fit with the valve seat, reducing minor leakage during the switching process. Specifically, see... Figure 4The valve plate 22 is provided with an annular groove 221 with a dovetail-shaped cross-section; the cross-section of the fluororubber sealing strip 23 is composed of a dovetail-shaped connecting part 231 and a semi-circular sealing part 232. The dovetail-shaped connecting part 231 cooperates with the annular groove 221. An annular recess 233 is provided on the side of the fluororubber sealing strip 231 near the bottom of the annular groove 221; the semi-circular sealing part 232 is used to cooperate with the end face of the annular sealing plate 24.

[0041] The above structure, combined with the fluororubber sealing strip 23, improves the temperature resistance and fit, reduces gas leakage to the flue side due to sealing failure, reduces the carbon monoxide content in the flue gas, and reduces the source of combustibles that may cause flash explosions.

[0042] In this embodiment, see Figure 4 An annular protrusion 222 is provided on the valve plate 22 inside the fluororubber sealing strip 23, and the height of the annular protrusion 222 is less than the height of the semi-circular sealing part 232. The annular protrusion 222 serves as a limit part for the maximum compression of the semi-circular sealing part 232, preventing damage to the semi-circular sealing part 232 during compression sealing. Simultaneously, in conjunction with the annular recess 233 on the fluororubber sealing strip 23, it effectively increases the deformation space of the fluororubber sealing strip 23 under pressure, improving sealing performance and service life.

[0043] In this embodiment, see Figure 5 The explosion relief valve 31 is installed on the side wall of the flue gas manifold 3 away from the flue gas inlet port (the flue gas in front of the nozzle), and each section of the flue gas manifold 3 is equipped with an explosion relief valve 31.

[0044] In this embodiment, the explosion relief valve 31 is a self-opening, self-returning explosion relief valve that is normally closed. In the event of a flash explosion, it opens to release pressure and automatically returns to its original position. This self-opening, self-returning explosion relief valve is an MBX series explosion relief valve. When the internal pressure of the flue gas manifold 3 reaches a preset critical value (typically ≤0.1 MPa), the valve plate or rupture diaphragm of the explosion relief valve 31 instantly ruptures / opens, rapidly releasing overpressure gas. After pressure relief, the valve cover automatically closes, blocking outside air from entering the system and preventing secondary explosions or flame backflow. This effectively prevents flames and heat, providing a safe environment for equipment, buildings, and personnel.

[0045] In this embodiment, the output end of the flue gas main pipe 5 is connected to the exhaust chimney 7 via the coal smoke induced draft fan 6 so that the flue gas can be discharged.

[0046] Taking a double-regenerative walking beam furnace with air-gas combustion at Egang Steel as an example, this furnace had previously suffered two accidents due to flue gas flash explosions causing damage to the flexible connection of the induced draft fan. The following modification plan was implemented: 1. By modifying the heat storage box 1 to have 1 layer of baffle bricks + 9 layers of heat storage body (the first 3 layers use 3.0mm diameter round hole high energy storage heat storage body 12, and the last 6 layers use 4.5mm diameter conventional hexagonal hole heat storage body 13), the exhaust gas temperature is reduced by about 30-50℃ compared with the original.

[0047] 2. The use of fluororubber sealing strips with optimized cross-sectional shape 2 significantly reduces the carbon monoxide content in the flue gas after the modification compared to before the modification.

[0048] 3. A self-returning explosion relief valve was installed in both the heating section and the soaking section of the main gas pipe. Since the modification, no equipment damage accidents caused by flash explosions have occurred.

[0049] After the implementation of the three improvements, the risk of flash explosion in the flue of the heating furnace was fundamentally eliminated, and the operational safety and equipment reliability were significantly improved.

[0050] The above description is only a preferred embodiment of the present invention. For those skilled in the art, designing different forms of dual regenerative heating furnace systems to prevent flue gas flash explosions based on the teachings of the present invention does not require creative labor. All equivalent changes, modifications, substitutions and variations made in accordance with the scope of the patent application of the present invention without departing from the principles and spirit of the present invention shall be covered by the present invention.

Claims

1. A dual regenerative heating furnace system for preventing flue gas flash explosion, comprising a heat storage tank, a three-way valve, and a flue gas manifold, wherein the heat storage tank, the three-way valve, and the flue gas manifold are sequentially arranged between the furnace outlet end and the main flue gas pipe along the flue gas conveying direction, characterized in that, The inlet end of the heat storage box is connected to the output end of the furnace chamber of the heating furnace. The heat storage box is provided with one layer of baffle bricks and nine layers of heat storage body from the inlet end to the flue gas side. A fluororubber sealing strip is provided on the end face of the valve plate that cooperates with the valve port on the flue gas side of the three-way valve. An explosion relief valve is installed on the side wall of the flue gas manifold.

2. A dual regenerative furnace system for preventing flue flashbacks according to claim 1, wherein The first three layers of the nine-layer heat storage body, which are closest to the retaining brick side, are high-energy-storage heat storage bodies with round holes of 3mm diameter; the last six layers are hexagonal heat storage bodies with holes of 4.5mm diameter.

3. A dual regenerative furnace system to prevent flue flashbacks according to claim 2, wherein The high-energy-storage heat storage body is made of zirconium corundum mullite; the hexagonal-hole heat storage body is an extruded honeycomb heat storage body.

4. A dual regenerative heating furnace system for preventing flue gas flash explosion according to claim 1, 2, or 3, characterized in that, An annular sealing plate is provided on the outer side of the valve port on the smoke exhaust side of the three-way valve. The valve plate is connected to the valve stem, and a fluororubber sealing strip is provided on the end face of the valve plate that mates with the annular sealing plate.

5. A dual regenerative furnace system to prevent flue flashbacks according to claim 4, wherein The valve plate is provided with an annular groove with a dovetail-shaped cross-section; the cross-section of the fluororubber sealing strip is composed of a dovetail-shaped connecting part and a semi-circular sealing part. The dovetail-shaped connecting part cooperates with the annular groove, and the fluororubber sealing strip is provided with an annular recess on the side of the dovetail-shaped connecting part near the bottom of the annular groove; the semi-circular sealing part is used to cooperate with the end face of the annular sealing plate.

6. A dual regenerative furnace system to prevent flue flashbacks according to claim 5, wherein An annular protrusion is provided on the valve plate inside the fluororubber sealing strip, and the height of the annular protrusion is less than the height of the semi-circular sealing part.

7. A dual regenerative furnace system to prevent flue flashbacks according to claim 1, wherein The explosion relief valve is installed on the side wall of the flue gas manifold away from the flue gas inlet port, and each section of the flue gas manifold is equipped with an explosion relief valve.

8. A dual regenerative furnace system for preventing flue flashbacks according to claim 1 or 7, wherein The explosion relief valve is a self-returning type that is normally closed during operation; when the internal pressure of the flue gas manifold reaches a preset critical value, the explosion relief valve opens and the valve cover automatically closes after the pressure is released.

9. A dual regenerative furnace system to prevent flue flashbacks according to claim 8, wherein The critical value is ≤0.1MPa.

10. A dual regenerative furnace system for preventing flue flashbacks according to claim 1, wherein The output end of the flue gas main pipe is connected to the exhaust chimney via a coal smoke induced draft fan.

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