A ring cooling machine sintering waste heat recycling system

Abstract

The application discloses a sintering waste heat recycling system of a circular cooler, wherein exhaust gas of a first temperature zone is cooled by a first waste heat boiler, exhaust gas of a fourth temperature zone is cooled by a fourth waste heat boiler, exhaust gas of a second temperature zone is cooled by a second waste heat boiler, and exhaust gas of a third temperature zone is cooled by a third waste heat boiler. The higher the temperature of the exhaust gas at the inlet of the waste heat boiler, the lower the temperature of the exhaust gas. The application creatively changes the exhaust gas recirculation mode, uses the high-temperature exhaust gas to cool the high-temperature sinter, and uses the low-temperature exhaust gas to cool the low-temperature sinter. As a result, the temperature of the exhaust gas above the high-temperature sinter is higher, the waste heat recovery amount is larger, the temperature of the exhaust gas for cooling the low-temperature sinter is lower, and the cooling of the final sinter and the cascade utilization of the sinter waste heat are facilitated.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and environmental protection technology, and specifically relates to a waste heat recovery and utilization system for sintering in an annular cooler. Background Technology

[0002] An annular cooler is an essential piece of equipment for cooling sintered ore. Its function is to cool the high-temperature sintered ore exiting the sintering machine. An annular cooling fan is installed at the bottom of the annular cooler. The fan blows air into the annular cooler, and the air carries away the sensible heat of the sintered ore through a heat exchanger, ultimately cooling the sintered ore.

[0003] The cooling of sinter in the annular cooler is a heat transfer process, with the temperature rising after air heat exchange. To save energy, the waste heat from the sinter is currently recovered. Depending on the distribution of the cooling sections in the annular cooler, the high-temperature waste heat from the first and second stages is typically recovered and used to generate steam of different qualities for power generation or other purposes via a waste heat boiler. For the low-temperature exhaust gas after the first and second stages of the annular cooler, some sintering plants also use exhaust gas recirculation to generate steam and recover this portion of waste heat. However, because the exhaust gas temperature is too high after recirculation, it is impossible to cool the ore discharge temperature from the annular cooler to the design value. This forces the sintering system to operate at reduced load, affecting sinter production.

[0004] Some sintering plants directly discharge the waste gas from the low-temperature section, resulting in a large amount of high-temperature dusty waste gas being directly released into the atmosphere, polluting the environment.

[0005] In view of this, in order to solve the above-mentioned technical problems in the existing technology, a waste heat recovery and utilization system for sintering ring cooler is proposed, which can maximize the energy recovery of sintered ore while ensuring that the cooling temperature of the ore meets the process requirements. Summary of the Invention

[0006] To address the above problems, this application provides a waste heat recovery and utilization system for an annular cooler sintering process. The annular cooler includes a first temperature zone 100, a second temperature zone 200, a third temperature zone 300, and a fourth temperature zone 400, divided according to the sinter temperature from high to low. The system includes a first waste heat boiler 2, a second waste heat boiler 3, a third waste heat boiler 4, a fourth waste heat boiler 5, a first circulating fan 6, a second circulating fan 7, a third circulating fan 8, a fourth circulating fan 9, and an annular cooling fan 10.

[0007] The air outlet of the first temperature zone is connected to the air inlet of the first waste heat boiler, and the air outlet of the first waste heat boiler is connected to the air inlet of the first circulating fan; the air outlet of the first circulating fan is connected to the air inlet of the fourth temperature zone.

[0008] The air outlet of the fourth temperature zone is connected to the air inlet of the fourth waste heat boiler; the air outlet of the fourth waste heat boiler is connected to the air inlet of the fourth circulating fan; the air outlet of the fourth circulating fan is connected to the air inlet of the first temperature zone.

[0009] The air outlet of the second temperature zone is connected to the air inlet of the second waste heat boiler; the air outlet of the second waste heat boiler is connected to the air inlet of the second circulating fan; and the air outlet of the second circulating fan is connected to the air inlet of the third temperature zone.

[0010] The air outlet of the third temperature zone is connected to the air inlet of the third waste heat boiler, and the air outlet of the third waste heat boiler is connected to the air inlet of the third circulating fan; the air outlet of the third circulating fan is connected to the air inlet of the second temperature zone.

[0011] Optionally, the annular cooler also includes a fifth temperature zone with a temperature lower than the fourth temperature zone. The air inlet of the fifth temperature zone is connected to the air outlet of the annular cooler 10, and the air inlet of the annular cooler is connected to the outside.

[0012] Optionally, the fifth temperature zone air outlet branches off to a first air outlet branch pipe 501, which merges with the first waste heat boiler air outlet and then connects to the first circulating fan air inlet.

[0013] Optionally, the fifth temperature zone air outlet also branches out into a fourth air outlet branch pipe 504, which merges with the air outlet of the fourth waste heat boiler and then connects to the air inlet of the fourth circulating fan.

[0014] Optionally, a second air outlet branch pipe 502 branches out from the air outlet of the fifth temperature zone. The second air outlet branch pipe merges with the air outlet of the second waste heat boiler and then connects to the air inlet of the second circulating fan.

[0015] Optionally, a third air outlet branch pipe 503 branches out from the air outlet of the fifth temperature zone. The third air outlet branch pipe merges with the air outlet of the third waste heat boiler and then connects to the air inlet of the third circulating fan.

[0016] Optionally, the exhaust gas temperature discharged from the first temperature zone outlet is 400-500℃, the exhaust gas temperature discharged from the second temperature zone outlet is 300-500℃, the exhaust gas temperature discharged from the third temperature zone outlet is 200-400℃, the exhaust gas temperature discharged from the fourth temperature zone outlet is 200-300℃, and the exhaust gas temperature discharged from the fifth temperature zone outlet is 50-200℃.

[0017] Optionally, for each waste heat boiler, the higher the exhaust gas temperature at its air inlet, the lower the flue gas temperature at its air outlet.

[0018] Optionally, the exhaust gas temperature of the first waste heat boiler is 50-100℃, the exhaust gas temperature of the second waste heat boiler is 100-150℃, the exhaust gas temperature of the third waste heat boiler is 100-200℃, and the exhaust gas temperature of the fourth waste heat boiler is 100-250℃.

[0019] Compared with the prior art, this application has the following advantages:

[0020] (1) Based on the characteristics of steam production by the low-temperature waste heat boiler (the higher the inlet waste gas temperature of the waste heat boiler, the lower the exhaust gas temperature of the waste heat boiler), the waste gas recirculation method is creatively changed. The high-temperature section sinter is cooled by the circulating waste gas with high exhaust gas temperature, and the low-temperature section sinter is cooled by the circulating waste gas with low exhaust gas temperature. This makes the waste gas temperature above the high-temperature section sinter higher and the waste heat recovery more. At the same time, the temperature of the circulating waste gas cooling the low-temperature section sinter is reduced even further, which helps to cool the final sinter and utilize the waste heat of the sinter in stages.

[0021] Since the flue gas temperature in the fourth temperature zone only needs to reach 200-300℃, and the flue gas temperature in the third temperature zone only needs to reach 200-400℃, while the flue gas temperature of the first waste heat boiler is 50-100℃ and that of the second waste heat boiler is 100-150℃, this application allows the flue gas from the second waste heat boiler to be introduced into the third temperature zone, which is sufficient to cool it by 200-400℃, and can also make the flue gas temperature in the third temperature zone higher within the range, thus increasing the amount of waste heat recovered. Introducing the flue gas from the first waste heat boiler into the fourth temperature zone is sufficient to cool the sintered ore in the fourth temperature zone by 200-300℃, and can also make the flue gas temperature lower within the range. This conforms to the principle of extreme recovery: high-temperature sintered ore is cooled by high-temperature waste gas, and low-temperature sintered ore is cooled by low-temperature waste gas.

[0022] Since the flue gas temperature in the first temperature zone only needs to reach 400-500℃, and the flue gas temperature in the second temperature zone only needs to reach 300-500℃, while the flue gas temperature of the fourth waste heat boiler 5 is 100-250℃ and the flue gas temperature of the third waste heat boiler is 100-200℃, this application introduces the flue gas from the fourth waste heat boiler into the first temperature zone, which is sufficient to cool the first temperature zone and makes the flue gas temperature in the first temperature zone higher within the range, resulting in greater waste heat recovery. Introducing the flue gas from the third waste heat boiler 4 into the second temperature zone is sufficient to cool the second temperature zone and makes the flue gas temperature lower within the range. This also conforms to the principle of extreme recovery: high-temperature sintered ore is cooled by high-temperature waste gas, and low-temperature sintered ore is cooled by low-temperature waste gas.

[0023] (2) The sinter in the first to fourth temperature zones is cooled by waste gas recirculation. The fifth temperature zone is cooled by a ring-cooled fan drawing cold air from the outdoor atmosphere. The exhaust gas is introduced into the first to fourth temperature zones as the air volume lost by the ring-cooled fan during the cooling process, thereby ensuring the balance of the exhaust gas volume of the entire ring-cooled fan system and achieving near-zero emissions from the ring-cooled fan.

[0024] (3) Moreover, two sets of waste gas cross-circulation systems are constructed. Using this cascade cooling technology, the cooling efficiency is higher, which is sufficient to ensure that the sintered ore is cooled to the required temperature.

[0025] (4) By utilizing the characteristics of low-temperature waste heat boilers, recirculated waste gas at different temperatures is used to cross-cool sinter at different temperatures, thereby reducing the gas-solid heat exchange temperature difference, improving the energy recovery rate, reducing the breakage rate of sinter during the cooling process, and increasing the yield of sinter. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the waste heat recovery and utilization system for the sintering of the annular cooler according to an embodiment of this application;

[0027] 1. Circulating cooler; 2. First waste heat boiler; 3. Second waste heat boiler; 4. Third waste heat boiler; 5. Fourth waste heat boiler; 6. First circulating fan; 7. Second circulating fan; 8. Third circulating fan; 9. Fourth circulating fan; 10. Circulating cooler; 100. First temperature zone; 200. Second temperature zone; 300. Third temperature zone; 400. Fourth temperature zone; 500. Fifth temperature zone; 501. First outlet branch pipe; 502. Second outlet branch pipe; 503. Third outlet branch pipe; 504. Fourth outlet branch pipe. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The waste heat recovery and utilization system for the sintering ring cooler in this embodiment achieves near-zero emissions from the ring cooler. Furthermore, by utilizing the characteristics of a low-temperature waste heat boiler, it cross-cools sintered ore at different temperatures using recirculated waste gas at different temperatures, reducing the gas-solid heat exchange temperature difference, improving energy recovery rate, decreasing the breakage rate of sintered ore during cooling, and increasing the yield of sintered ore. In addition, the recirculated waste gas in the third and fourth stages is at a lower temperature, and the sintered ore is then cooled by outdoor air in the fifth stage, which is sufficient to cool the sintered ore to the design temperature, ensuring that the rated capacity of the sintering machine is not reduced.

[0030] The waste heat recovery and utilization system for sintering in the annular cooler of this embodiment includes a first waste heat boiler 2, a second waste heat boiler 3, a third waste heat boiler 4, a fourth waste heat boiler 5, a first circulating fan 6, a second circulating fan 7, a third circulating fan 8, a fourth circulating fan 9, and an annular cooler fan 10.

[0031] The annular cooler 1 is divided into five zones based on the temperature of the sinter, from highest to lowest: Zone 1 (100°C), Zone 2 (200°C), Zone 3 (300°C), Zone 4 (400°C), and Zone 5 (500°C). Please refer to the above description. Figure 1The exhaust gas temperature from the first temperature zone (100°C outlet) is 400-500°C; from the second temperature zone (200°C outlet) it is 300-500°C; from the third temperature zone (300°C outlet) it is 200-400°C; from the fourth temperature zone (400°C outlet) it is 200-300°C; and from the fifth temperature zone it is 50-200°C. Each temperature zone has one inlet and one outlet. The inlet is used to introduce cooling air to cool the sintered ore within the zone, and the outlet is used to discharge the flue gas that has absorbed heat through heat exchange with the sintered ore.

[0032] The air inlet of the fifth temperature zone is connected to the air outlet of the annular cooling fan 10. The air inlet of the annular cooling fan 10 draws air from the outdoor air to cool the sinter in the fifth temperature zone.

[0033] The air outlet of the first temperature zone 100 is connected to the air inlet of the first waste heat boiler 2. A first air outlet branch pipe 501 branches out from the air outlet of the fifth temperature zone 500. The first air outlet branch pipe 501 merges with the air outlet of the first waste heat boiler 2 and then connects to the air inlet of the first circulating fan 6. The air outlet of the first circulating fan 6 is connected to the air inlet of the fourth temperature zone 400.

[0034] The air outlet of the fourth temperature zone 400 is connected to the air inlet of the fourth waste heat boiler 5; a fourth air outlet branch pipe 504 branches off from the air outlet of the fifth temperature zone 500, and the fourth air outlet branch pipe 504 merges with the air outlet of the fourth waste heat boiler 5 and then connects to the air inlet of the fourth circulating fan 9; the air outlet of the fourth circulating fan 9 is connected to the air inlet of the first temperature zone 100, thereby forming a cross-circulation system for cooling the exhaust gas of the first and fourth temperature zones.

[0035] The air outlet of the second temperature zone 200 is connected to the air inlet of the second waste heat boiler 3; a second air outlet branch pipe 502 branches off from the air outlet of the fifth temperature zone 500, and the second air outlet branch pipe 502 merges with the air outlet of the second waste heat boiler 3 and then connects to the air inlet of the second circulating fan 7. The air outlet of the second circulating fan 7 is connected to the air inlet of the third temperature zone 300.

[0036] The air outlet of the third temperature zone 300 is connected to the air inlet of the third waste heat boiler 4; a third air outlet branch pipe 503 branches off from the air outlet of the fifth temperature zone 500, and the third air outlet branch pipe 503 merges with the air outlet of the third waste heat boiler 4 and then connects to the air inlet of the third circulating fan 8; the air outlet of the third circulating fan 8 is connected to the air inlet of the second temperature zone 200, thereby forming a cross-circulation system for cooling the exhaust gas of the second and third temperature zones.

[0037] The working process of the waste heat recovery and utilization system for the sintering of the annular cooler is explained below.

[0038] The waste heat utilization of the exhaust gas on the annular cooler is a low-temperature waste heat recovery method, which adopts the steam recovery method. The exhaust gas temperature discharged from the outlet of the first temperature zone is 400-500℃, which means that the exhaust gas temperature at the inlet of the first waste heat boiler 2 is 400-500℃. After heat exchange, the exhaust gas temperature of the first waste heat boiler 2 will be reduced to 50-100℃. This low-temperature exhaust gas of 50-100℃ is then connected to the first outlet branch pipe 501 branched from the outlet of the fifth temperature zone through a pipeline and enters the first circulating fan 6. The first circulating fan 6 sends the exhaust gas to the fourth temperature zone to cool the sintered ore. After cooling the sintered ore, the exhaust gas temperature rises to 200-300℃. After entering the fourth waste heat boiler 5 for heat exchange, the exhaust gas temperature drops to 100-250℃. This part of the exhaust gas merges with the fourth air outlet branch pipe 504 of the fifth temperature zone 500 through the pipeline and enters the fourth circulating fan 9. The fourth circulating fan 9 returns the exhaust gas to the first temperature zone 100 to cool the sintered ore, completing a cross-circulation process of exhaust gas.

[0039] The exhaust gas temperature from the outlet of the second temperature zone 200 is 300-500℃, which is the inlet exhaust gas temperature of the second waste heat boiler 3. After heat exchange, the exhaust gas temperature of the second waste heat boiler 3 will drop to 100-150℃. This low-temperature exhaust gas of 100-150℃ is then combined with the second outlet branch pipe 502 of the fifth temperature zone 500 through a pipeline and enters the third circulating fan 7. The third circulating fan 7 blows the exhaust gas into the third temperature zone 300 of the annular cooler 1, where the temperature of the sintered ore is raised to 200-400℃ after cooling. After heat exchange by the third waste heat boiler 4, the exhaust gas temperature drops to 100-200℃. This part of the exhaust gas is then combined with the third outlet branch pipe 503 of the fifth temperature zone 500 through a pipeline and enters the third circulating fan 8. The third circulating fan 8 returns the exhaust gas to the second temperature zone 200 to cool the sintered ore, completing a cross-circulation process of exhaust gas.

[0040] Since the annular cooling fan 10 directly draws cold air from the atmosphere and introduces it into the fifth temperature zone 500 of the annular cooler 1 to cool the last section of sintered ore, the exhaust gas at 50-150°C after heat exchange enters the first to fourth temperature zones through the first circulating fan 6, the second circulating fan 7, the third circulating fan 8 and the fourth circulating fan 9 respectively, making up for the air volume lost by the exhaust gas in the first to fourth temperature zones during the circulation process, and achieving near-zero emissions of exhaust gas from the annular cooler.

[0041] As can be seen, the flue gas from the first waste heat boiler 2 is 50-100℃, and the flue gas from the second waste heat boiler 3 is 100-150℃. Since the flue gas temperature in the fourth temperature zone only needs to reach 200-300℃, and the flue gas temperature in the third temperature zone only needs to reach 200-400℃, this application introduces the flue gas from the first waste heat boiler 2 into the fourth temperature zone (400℃) and the flue gas from the second waste heat boiler 3 into the third temperature zone, which is sufficient to cool the fourth and third temperature zones to this temperature range. This conforms to the principle of extreme recovery: high-temperature sintered ore is cooled by high-temperature waste gas, and low-temperature sintered ore is cooled by low-temperature waste gas.

[0042] The flue gas temperature of the fourth waste heat boiler 5 is 100-250℃, and that of the third waste heat boiler 4 is 100-200℃. Since the flue gas temperature in the first temperature zone only needs to reach 400-500℃, and the flue gas temperature in the second temperature zone only needs to reach 300-500℃, this application introduces the flue gas from the fourth waste heat boiler 5 into the first temperature zone and the flue gas from the third waste heat boiler 4 into the second temperature zone. This also conforms to the principle of extreme recovery: high-temperature sintered ore is cooled by high-temperature waste gas, and low-temperature sintered ore is cooled by low-temperature waste gas. Moreover, by constructing two sets of cross-circulation waste gas systems and adopting this cascade cooling technology, the cooling efficiency is higher, which is sufficient to ensure that the sintered ore is cooled to the required temperature.

[0043] Moreover, the sinter in the first to fourth temperature zones of the annular cooler 1 is cooled by waste gas recirculation, and the fifth temperature zone is cooled by the annular cooler fan 10 drawing cold air from the outdoor atmosphere. The exhaust gas is introduced into the first to fourth temperature zones as the air volume lost by the annular cooler during the cooling process, thereby ensuring the balance of the waste gas volume of the entire annular cooler system and achieving near-zero emissions from the annular cooler.

[0044] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications are all within the protection scope of the claims of the present invention.

Claims

1. A ring cooler sintering waste heat recovery and utilization system, characterized in that, The ring cooling machine comprises a first temperature zone (100), a second temperature zone (200), a third temperature zone (300) and a fourth temperature zone (400) divided according to the sinter temperature from high to low, and the system comprises a first waste heat boiler (2), a second waste heat boiler (3), a third waste heat boiler (4), a fourth waste heat boiler (5), a first circulating fan (6), a second circulating fan (7), a third circulating fan (8), a fourth circulating fan (9) and a ring cooling fan (10), The first temperature zone air outlet is communicated with the first waste heat boiler air inlet, the first waste heat boiler air outlet is communicated with the first circulating fan air inlet, the first circulating fan air outlet is communicated with the fourth temperature zone air inlet, the fourth temperature zone air outlet is communicated with the fourth waste heat boiler air inlet, the fourth waste heat boiler air outlet is communicated with the fourth circulating fan air inlet, and the fourth circulating fan air outlet is communicated with the first temperature zone air inlet. The second temperature zone air outlet is communicated with the second waste heat boiler air inlet, the second waste heat boiler air outlet is communicated with the second circulating fan air inlet, the second circulating fan air outlet is communicated with the third temperature zone air inlet, the third temperature zone air outlet is communicated with the third waste heat boiler air inlet, the third waste heat boiler air outlet is communicated with the third circulating fan air inlet, and the third circulating fan air outlet is communicated with the second temperature zone air inlet.

2. The ring cooler sintering waste heat recovery and utilization system according to claim 1, characterized in that, The ring cooling machine further comprises a fifth temperature zone with a lower temperature than the fourth temperature zone, and the fifth temperature zone air inlet is communicated with the ring cooling fan (10) air outlet, and the ring cooling fan air inlet is communicated with the outdoor.

3. The ring cooler sintering waste heat recovery and utilization system according to claim 2, characterized in that, The fifth temperature zone air outlet branches into a first air outlet branch pipeline (501), which is communicated with the first waste heat boiler air outlet and then with the first circulating fan air inlet.

4. The ring cooler sintering waste heat recovery and utilization system according to claim 2, characterized in that, The fifth temperature zone air outlet further branches into a fourth air outlet branch pipeline (504), which is communicated with the fourth waste heat boiler air outlet and then with the fourth circulating fan air inlet.

5. The ring cooler sintering waste heat recovery and utilization system according to claim 2, characterized in that, The fifth temperature zone air outlet branches into a second air outlet branch pipeline (502), which is communicated with the second waste heat boiler air outlet and then with the second circulating fan air inlet.

6. The ring cooler sintering waste heat recovery and utilization system according to claim 2, characterized in that, The fifth temperature zone air outlet branches into a third air outlet branch pipeline (503), which is communicated with the third waste heat boiler air outlet and then with the third circulating fan air inlet.

7. The ring cooler sintering waste heat recovery and utilization system according to claim 2, characterized in that, The exhaust gas temperature of the first temperature zone air outlet is 400-500℃, the exhaust gas temperature of the second temperature zone air outlet is 300-500℃, the exhaust gas temperature of the third temperature zone air outlet is 200-400℃, the exhaust gas temperature of the fourth temperature zone air outlet is 200-300℃, and the exhaust gas temperature of the fifth temperature zone air outlet is 50-200℃.

8. The ring cooler sintering waste heat recovery and utilization system according to claim 1, characterized in that, For each waste heat boiler, the higher the exhaust gas temperature of the air inlet, the lower the exhaust gas temperature of the waste heat boiler air outlet.

9. The ring cooler sintering waste heat recovery and utilization system according to claim 1, characterized in that, The exhaust gas temperature of the first waste heat boiler is 50-100℃, the exhaust gas temperature of the second waste heat boiler is 100-150℃, the exhaust gas temperature of the third waste heat boiler is 100-200℃, and the exhaust gas temperature of the fourth waste heat boiler is 100-250℃.

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