A system and method for purifying ultra-high temperature flue gas and recovering waste heat from electric furnace steelmaking

Abstract

The present invention discloses an electric furnace steelmaking ultra-high temperature flue gas purification and waste heat recovery system and method, which belongs to the field of electric furnace flue gas waste heat recovery. The technical scheme thereof includes an electric furnace, a first waste heat recovery device, an ultra-high temperature flue gas constant temperature filtering and purification device, a second waste heat recovery device, a heat exchanger, an axial flow fan and a chimney connected in sequence. The ultra-high temperature flue gas constant temperature filtering and purification device includes an upper box body, a middle box body and a dust collector ash hopper arranged in sequence from top to bottom. A high temperature composite phase change heat storage rod is arranged in the middle box body. Two groups of high temperature composite phase change heat storage rods are arranged in the vertical direction. A waste heat recovery steam-water system is connected to the first waste heat recovery device. The present invention enables the filter element to work within a relatively stable temperature range, prolongs the service life of the purification device, and at the same time improves the recovery efficiency of waste heat and reduces the waste of resources.

Description

Technical Field

[0001] The present invention relates to the field of waste heat recovery of flue gas from electric furnaces, and in particular to a system and method for purifying ultra-high temperature flue gas from steelmaking in electric furnaces and recovering waste heat. Background Art

[0002] Electric furnace dust is the metal dust volatilized during the metal heating process, including metal and metal oxides. Its type is related to many factors such as the composition of the charge, oxide materials and oil-impregnated substances, smelting speed, furnace temperature and oxygen blowing intensity. Electric furnace dust has the characteristics of small dust particles, high temperature and high toxicity (containing toxic substances such as dioxins / furans / heavy metals). If effective control measures are not taken, it will seriously pollute the workshop and factory environment and affect the health of workers and surrounding residents.

[0003] Because the current high-temperature flue gas filtration engineering application, that is to say, the long-term operation working environment of the filter bag generally makes the high-temperature flue gas reach about 200℃~250℃ after cooling measures. Therefore, referring to the classification standards of thermal power engineering, in the flue gas filtration industry, the flue gas to be filtered can be divided into normal temperature flue gas (<120℃), normal high temperature flue gas (<250℃), sub-high temperature flue gas (250~450℃), and ultra-high temperature flue gas (<800℃). Here, the high-temperature flue gas (about 1200℃) generated during the electric furnace smelting process through the fourth hole on the furnace cover, the combustion sedimentation chamber, and the flue gas coming out through the water-cooled flue is defined as ultra-high temperature flue gas.

[0004] At present, both at home and abroad, the use of rapid cooling waste heat recovery devices and filtering and purification devices for high-temperature flue gas from electric furnace smelting has been promoted. However, the following problems still exist: Due to the high dust content in high-temperature flue gas from electric furnace smelting, the heating surface of the heat exchange element of the rapid cooling waste heat recovery device is seriously dusted, and it is very difficult to remove. The high dust content in high-temperature flue gas from electric furnace smelting causes very serious wear on the heating surface of the heat exchange element of the rapid cooling waste heat recovery device, and the heating surface of the heat exchange element of the rapid cooling waste heat recovery device is severely eroded, and the fin structure cannot be effectively used to effectively increase the heat exchange area and heat exchange efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide an ultra-high temperature flue gas purification and waste heat recovery system and method for electric furnace steelmaking, which can enable the filter element to operate within a relatively stable temperature range, extend the service life of the purification device, while improving the waste heat recovery efficiency and reducing resource waste.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] An ultra-high temperature flue gas purification and waste heat recovery system for electric furnace steelmaking, comprising an electric furnace, a first waste heat recovery device, an ultra-high temperature flue gas constant temperature filtering and purification device, a second waste heat recovery device, a heat exchanger, an axial flow fan and a chimney connected in sequence, the ultra-high temperature flue gas constant temperature filtering and purification device comprising an upper box body, a middle box body and a dust collector ash hopper arranged in sequence from top to bottom, a high temperature composite phase change heat storage rod is arranged in the middle box body, and the high temperature composite phase change heat storage rod is arranged in two groups in the vertical direction, the first waste heat recovery device is connected to a waste heat recovery steam-water system, and the waste heat recovery steam-water system is connected to the second waste heat recovery device and the heat exchanger through pipelines, the middle box body is provided with a smoke inlet, and the upper box body is provided with a smoke outlet.

[0008] Furthermore, the first waste heat recovery device includes a water-cooled sliding sleeve, a combustion settling chamber and a vaporization cooling flue connected in sequence, and the outlet end of the vaporization cooling flue is connected to the inlet section of the ultra-high temperature flue gas constant temperature filtering device.

[0009] Furthermore, the second waste heat recovery device includes a front box body, a middle box section and a rear box body which are arranged in sequence from top to bottom, a smoke inlet is opened at the upper end of the front box body, a heat pipe with fins is arranged in the middle box section, and several groups of heat pipes are arranged in the vertical direction, and a smoke outlet is arranged at the bottom of the rear box body.

[0010] Furthermore, a maintenance manhole door is provided on the front box body, and a plurality of the maintenance manhole doors are arranged in the middle box section. A shock wave soot blowing pipe is connected to the maintenance manhole door, and the shock wave soot blowing pipe is connected to an external power system.

[0011] Furthermore, the heat exchanger is a fin heat exchange tube structure.

[0012] Furthermore, the waste heat recovery steam-water system adopts a water circulation cooling method.

[0013] Furthermore, a method for processing using the system as described above comprises the following steps:

[0014] Step S1: Under the power of the axial flow fan, the ultra-high temperature flue gas generated in the electric furnace enters the water-cooled sliding sleeve and the vaporization cooling flue in sequence for initial cooling, and then enters the combustion settling chamber for dust precipitation;

[0015] Step S2: The ultra-high temperature flue gas treated in step 1 enters the vaporization cooling flue for secondary cooling, and then enters the ultra-high temperature flue gas constant temperature filtering and purification device. The temperature in the ultra-high temperature flue gas constant temperature filtering and purification device is set to 650-800°C, and the generated dust enters the dust collector hopper;

[0016] Step S3: The ultra-high temperature flue gas treated in step S2 enters the second waste heat recovery device and the heat exchanger. The multiple groups of heat pipes in the second waste heat recovery device further cool the flue gas. The heat exchanger combines with the waste heat recovery steam-water system to further recover the waste heat in the flue gas.

[0017] Step S4: The smoke treated in step S3 moves toward the axial flow fan and is then discharged through the chimney.

[0018] Furthermore, the water-cooled sliding sleeve, the vaporization cooling flue, the second waste heat recovery device and the heat exchanger are all connected to the waste heat recovery steam-water system.

[0019] In summary, the present invention has the following beneficial effects:

[0020] 1. Through the setting of the ultra-high temperature flue gas constant temperature filtering and purification device, the high temperature composite phase change heat storage rod absorbs and releases heat through phase change, ensuring that the temperature in the device is constant within the set high temperature range, effectively improving the service life of the filter element in the device, and at the same time purifying the flue gas within the high temperature range, reducing the possibility of the generation of toxic substances such as dioxins / furans in the subsequent cooling process.

[0021] 2. Through the setting of waste heat recovery steam water system, the recovered heat energy is used to preheat the softened water, thus improving the energy utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention in the embodiment;

[0023] Figure 2 In the embodiment, it is used to embody Figure 1 A schematic diagram of the enlarged structure of part A;

[0024] Figure 3 is a schematic diagram of a local structure used in the present invention in an embodiment;

[0025] Figure 4 In the embodiment, it is used to embody Figure 3 Schematic diagram of the enlarged structure of part B.

[0026] In the figure, 1, electric furnace; 2, first waste heat recovery device; 201, water-cooled sliding sleeve; 202, combustion settling chamber; 203, vaporization cooling flue; 3, ultra-high temperature flue gas constant temperature filtering and purification device; 301, upper box; 302, middle box; 303, dust collector ash hopper; 4, second waste heat recovery device; 401, front box; 402, middle box section; 403, rear box; 5, heat exchanger; 6, axial flow fan; 7 , chimney; 8. high-temperature composite phase-change heat storage rod; 9. waste heat recovery steam-water system; 10. smoke inlet; 11. smoke outlet; 12. flue gas inlet; 13. flue gas outlet; 14. inspection manhole door; 15. shock wave soot blowing pipe; 901. high-pressure steam drum; 902. heat accumulator; 903. water distribution header; 904. low-pressure steam drum; 905. deaerator; 906. deaerator is connected to a soft water tank; 907. booster pump. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0028] The same parts are denoted by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "bottom" and "top", "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0029] Example:

[0030] An ultra-high temperature flue gas purification and waste heat recovery system for steelmaking in an electric furnace 1, such as Figure 1 and 2 As shown, it includes an electric furnace 1, a first waste heat recovery device 2, an ultra-high temperature flue gas constant temperature filtering and purification device 3, a second waste heat recovery device 4, a heat exchanger 5, an axial flow fan 6 and a chimney 7 connected in sequence. The ultra-high temperature flue gas constant temperature filtering and purification device 3 includes an upper box body 301, a middle box body 302 and a dust collector ash hopper 303 arranged in sequence from top to bottom. A high temperature composite phase change heat storage rod 8 is arranged in the middle box body 302. The high temperature composite phase change heat storage rod 8 is arranged in two groups along the vertical direction. At the same time, a ceramic filter tube is used in the ultra-high temperature flue gas constant temperature filtering and purification device 3 to purify the dust in the ultra-high temperature flue gas. The first waste heat recovery device 2 is connected to a waste heat recovery steam and water system 9, and the waste heat recovery steam and water system 9 is connected to the second waste heat recovery device 4 and the heat exchanger 5 through pipelines. A smoke inlet 10 is opened on the middle box body 302, and a smoke outlet 11 is opened on the upper box body 301. The heat exchanger 5 is a fin heat exchange tube structure to improve the heat dissipation efficiency.

[0031] like Figure 1As shown, a first waste heat recovery device 2 is provided, which includes a water-cooled sliding sleeve 201, a combustion settling chamber 202 and a vaporization cooling flue 203 connected in sequence. The vaporization cooling flue 203 is connected to both sides of the combustion settling chamber 202, and the outlet end of the vaporization cooling flue 203 is connected to the inlet section of the ultra-high temperature flue gas constant temperature filtering device.

[0032] Figure 1 and 2 As shown, the ultra-high temperature flue gas in the electric furnace 1, driven by the axial flow fan 6, first passes through the water-cooled sliding sleeve 201, enters the vaporization cooling flue 203, and then enters the next vaporization cooling flue 203 through the combustion settling chamber 202, and further recovers the heat in the ultra-high temperature flue gas. After that, the ultra-high temperature flue gas enters the ultra-high temperature flue gas constant temperature filtering and purification device 3 through the smoke inlet 10, and the temperature in the ultra-high temperature flue gas constant temperature filtering and purification device 3 is set to 650-800°C. After the ceramic filter tube and the high-temperature composite phase change heat storage rod 8, the ultra-high temperature flue gas is converted into high-temperature flue gas for discharge. Under the action of the axial flow fan 6, the high-temperature flue gas continues to move toward the second waste heat recovery device 4 and the heat exchanger 5, and the heat in the high-temperature flue gas is further cooled and consumed by the two, and then discharged from the chimney 7.

[0033] like Figure 2 As shown, in order to improve the recovery of heat in the flue gas by the second waste heat recovery device 4, the second waste heat recovery device 4 includes a front box body 401, a middle box section 402 and a rear box body 403 arranged in sequence from top to bottom. The shell of the second waste heat recovery device 4 adopts a membrane water-cooled wall structure. A flue gas inlet 12 is opened at the upper end of the front box body 401, and a finned heat pipe is arranged in the middle box section 402. The heat pipe is inserted into the middle box section 402 from the outside. Five groups of heat pipes are arranged in the vertical direction, and an alloy coating is sprayed on the surface of the heat pipe. A flue gas outlet 13 is arranged at the bottom of the rear box body 403. Through the arrangement of five groups of finned heat pipes, the heating area is increased, and the rapid cooling effect of the heat pipe on the high-temperature flue gas is improved.

[0034] like Figure 3 and 4 As shown, a maintenance manhole door 14 is provided on the front box body 401, four maintenance manhole doors 14 are provided in the middle box section 402, one maintenance manhole door 14 is provided between two groups of heat pipes, and at the same time, a maintenance manhole door 14 is also provided in the front box body 401. The maintenance manhole door 14 is connected to a shock wave soot blowing pipe 15, which is connected to an external power system. 2 When explosive gas is generated, nitrogen can be blown into the second waste heat recovery device 4 through the shock wave soot blowing pipe 15 to reduce the possibility of explosion.

[0035] like Figure 1As shown, the waste heat recovery steam-water system 9 is connected with the water-cooled sliding sleeve 201, the vaporization cooling flue 203, the second waste heat recovery device 4 and the heat exchanger. The waste heat recovery steam-water system 9 is connected with the high-pressure steam drum 901, the heat accumulator 902, the water distribution header 903, the low-pressure steam drum 904 and the deaerator 905 through pipelines. The deaerator 905 is connected with the soft water tank 906. The soft water tank 906 is connected with the heat exchanger 5. The heat exchanger 5 is also connected with the external soft water tank. The heat exchanger 5 can effectively recover the waste heat in the flue gas of ≤200°C, and then use the recovered heat energy to preheat the soft water. The pipeline connecting the soft water tank 906, the deaerator 905 and the water distribution header 903 is connected with a booster pump 907.

[0036] The present invention also discloses a method for processing using the system as described above, comprising the following steps:

[0037] Step S1: Under the power of the axial flow fan 6, the ultra-high temperature flue gas generated in the electric furnace 1 enters the water-cooled sliding sleeve 201 and the vaporization cooling flue 203 in sequence for initial cooling. The water-cooled sliding sleeve 201 and the vaporization cooling flue 203 are both connected to the waste heat recovery steam-water system 9, and then enters the combustion settling chamber 202 for dust precipitation;

[0038] Step S2: The ultra-high temperature flue gas treated in step 1 enters the vaporization cooling flue 203 for secondary cooling, and then enters the ultra-high temperature flue gas constant temperature filtering and purification device 3. The temperature in the ultra-high temperature flue gas constant temperature filtering and purification device 3 is set to 650-800°C. The high-temperature composite phase change heat storage rod 8 can absorb and release heat according to the temperature of the ultra-high temperature flue gas entering, and convert the ultra-high temperature flue gas into high-temperature flue gas for discharge. At the same time, the absorbed dust enters the dust collector hopper 303;

[0039] Step S3: The ultra-high temperature flue gas treated in step S2 enters the second waste heat recovery device 4 and the heat exchanger 5. The multiple groups of heat pipes in the second waste heat recovery device 4 further cool the flue gas. The heat exchanger 5 combines with the waste heat recovery steam-water system 9 to further recover the waste heat in the flue gas.

[0040] Step S4: the smoke treated in step S3 moves toward the axial flow fan 6 and then is discharged through the chimney 7.

[0041] Specific implementation process: Under the action of the axial flow fan 6, the ultra-high temperature flue gas generated in the electric furnace 1 passes through the water-cooled sliding sleeve 201 and the vaporization cooling flue 203 for the first cooling, and then enters the combustion settling chamber 202 for dust precipitation. Then it passes through the vaporization cooling flue 203 for secondary cooling, and then enters the ultra-high temperature flue gas constant temperature filtering and purification device 3 for cooling. The temperature in the ultra-high temperature flue gas constant temperature filtering and purification device 3 is set to 650-800℃, and the generated dust enters the dust collector hopper 303. The exhausted flue gas enters the second waste heat recovery device 4 and the heat exchanger 5 for cooling. At the same time, the heat exchanger 5 combines the waste heat recovery steam-water system 9 to further recycle the waste heat in the flue gas. The purified flue gas passes through the axial flow fan 6 and is discharged from the chimney 7.

[0042] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. An ultra-high temperature flue gas purification and waste heat recovery system for electric furnace steelmaking, characterized in that: The invention comprises an electric furnace (1), a first waste heat recovery device (2), an ultra-high temperature flue gas constant temperature filtering and purification device (3), a second waste heat recovery device (4), a heat exchanger (5), an axial flow fan (6) and a chimney (7) which are connected in sequence. The ultra-high temperature flue gas constant temperature filtering and purification device (3) comprises an upper box body (301), a middle box body (302) and a dust collector ash hopper (303) which are arranged in sequence from top to bottom. A high temperature composite phase change heat storage rod (8) is arranged in the middle box body (302). Two groups of the high temperature composite phase change heat storage rod (8) are arranged in the vertical direction. The first waste heat recovery device (2) is connected to a waste heat recovery steam-water system (9). The waste heat recovery steam-water system (9) is connected to the second waste heat recovery device (4) and the heat exchanger (5) through pipelines. A smoke inlet (10) is provided on the middle box body (302), and a smoke outlet (11) is provided on the upper box body (301). The first waste heat recovery device (2) comprises a water-cooled sliding sleeve (201), a combustion settling chamber (202) and a vaporization cooling flue (203) connected in sequence, and the outlet end of the vaporization cooling flue (203) is connected to the inlet section of the ultra-high temperature flue gas constant temperature filtering device; The second waste heat recovery device (4) comprises a front box body (401), a middle box section (402) and a rear box body (403) which are arranged in sequence from top to bottom, the front box body (401) has a smoke inlet (12) at the upper end, the middle box section (402) is provided with a heat pipe with fins, and the heat pipe is arranged in a plurality of groups in a vertical direction, and the rear box body (403) has a smoke outlet (13) at the bottom; The front box body (401) is provided with a maintenance manhole door (14), and a plurality of the maintenance manhole doors (14) are arranged in the middle box section (402). The maintenance manhole door (14) is connected to a shock wave soot blowing pipe (15), and the shock wave soot blowing pipe (15) is connected to an external power system.

2. The ultra-high temperature flue gas purification and waste heat recovery system for electric furnace steelmaking according to claim 1 is characterized in that: The heat exchanger (5) is a fin heat exchange tube structure.

3. The ultra-high temperature flue gas purification and waste heat recovery system for electric furnace steelmaking according to claim 1 is characterized in that: The waste heat recovery steam-water system (9) adopts a water circulation cooling method.

4. A method for purifying ultra-high temperature flue gas from electric furnace steelmaking using the ultra-high temperature flue gas purification and waste heat recovery system for electric furnace steelmaking according to claim 1, characterized in that: The following steps are involved: Step S1: Under the power of the axial flow fan (6), the ultra-high temperature flue gas generated in the electric furnace (1) enters the water-cooled sliding sleeve (201) and the vaporization cooling flue (203) in sequence for initial cooling, and then enters the combustion settling chamber (202) for dust precipitation; Step S2: the ultra-high temperature flue gas treated in step 1 enters the vaporization cooling flue (203) for secondary cooling, and then enters the ultra-high temperature flue gas constant temperature filtering and purification device (3), the temperature in the ultra-high temperature flue gas constant temperature filtering and purification device (3) is set to 650-800°C, and the generated dust enters the dust collector hopper (303); Step S3: the ultra-high temperature flue gas treated in step S2 enters the second waste heat recovery device (4) and the heat exchanger (5), the multiple groups of heat pipes in the second waste heat recovery device (4) further cool the flue gas, and the heat exchanger (5) combines with the waste heat recovery steam-water system (9) to further recover the waste heat in the flue gas; Step S4: The smoke treated in step S3 moves toward the axial flow fan (6) and is then discharged through the chimney (7).

5. The method for purifying ultra-high temperature flue gas from electric furnace steelmaking according to claim 4, characterized in that: The water-cooled sliding sleeve (201), the vaporization cooling flue (203), the second waste heat recovery device (4) and the heat exchanger are all connected to the waste heat recovery steam-water system (9).

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