Method and system for recycling exhaust gas from circular sinter cooler

Abstract

Disclosed in the present invention are a method and system for recycling exhaust gas from a circular sinter cooler. By combining the technical means of cascade utilization of low-temperature exhaust gas from circular sinter cooling, synchronous heat supply and oxygen supply for quality improvement with medium-temperature exhaust gas from circular sinter cooling, gradient heat exchange for steam enrichment, etc., low-temperature exhaust gas is first circulated, the temperature of medium-temperature exhaust gas is then raised, high-temperature oxygen-rich exhaust gas is further obtained by means of oxygen-enriched combustion, and subsequently the high-temperature oxygen-rich exhaust gas is subjected to gradient heat exchange to obtain high-quality steam, industrial hot water, and low-temperature oxygen-rich steam-containing exhaust gas that can be directly used for sintering. Therefore, the waste heat of medium- and low-temperature exhaust gas from a circular sinter cooler is efficiently recovered at a low cost, the emissions of exhaust gas are also significantly reduced, the yield and quality indexes of sintered ore are further improved, and the production cost is reduced.

Description

A method and system for recycling waste gas from a sintering ring cooler Technical Field

[0001] The present invention relates to the treatment of sintering ring cooling waste gas, and in particular to a method and system for recycling sintering ring cooling waste gas, belonging to the technical field of sintering ring cooling waste gas treatment. Background Art

[0002] During the sintering process, the temperature of the sinter cake after it is unloaded from the sintering machine can reach 700-800°C. The physical sensible heat it carries is the most important component of the sintering waste heat resource. During the air cooling process, the sinter temperature drops below 150°C, generating a large amount of hot air. Generally, the temperature of the cooling exhaust gas varies from different parts of the sintering ring cooler, gradually decreasing from the receiving end to the discharge end. It is generally divided into three sections: a high-temperature zone above 250°C, a medium-temperature zone between 150°C and 250°C, and a low-temperature zone below 150°C.

[0003] At present, in order to fully utilize the waste heat resources of high-temperature exhaust gas generated by the sintering ring cooling process, many companies have built supporting sintering waste heat recovery systems. The high-temperature exhaust gas of the ring cooler is heat-exchanged in a waste heat boiler to generate steam for power generation, or the exhaust gas after heat exchange in the waste heat boiler is further returned to the air inlet of the high-temperature zone of the ring cooler to cool the sintered ore and recycle it. This method makes better use of the cooling exhaust gas in the high-temperature zone of the ring cooler. However, for the medium and low temperature cooling exhaust gas generated in the medium and low temperature zones of the ring cooler, the waste heat utilization of this exhaust gas has always been difficult because the exhaust gas temperature is low and cannot meet the waste heat boiler gas inlet temperature requirements, or the steam generated by heat exchange in the waste heat boiler is of poor quality and difficult to use. In some companies, there is even a situation where medium and low temperature exhaust gas is directly discharged, which not only wastes waste heat resources but also causes dust pollution.

[0004] To address the difficulty in utilizing low-temperature waste gas from sinter ring cooling, existing technologies have proposed a variety of technical solutions from the perspectives of resource utilization and environmental protection. For example, patent CN206683423U provides a device for utilizing waste heat from flue gas in a sinter ring cooler. This device returns the low-temperature cooling waste gas to the cooling air inlets of the high-temperature and medium-temperature zones through a circulating fan. The cooling waste gas from the high-temperature and medium-temperature zones then enters the waste heat boiler. After heat exchange in the waste heat boiler, the waste gas also returns to the cooling air inlets of the high-temperature and medium-temperature zones. This recycling within the ring cooler system improves the efficiency of sinter waste heat utilization and reduces thermal and dust pollution to the atmosphere. Patent CN108731486 A proposes a system and method for recycling medium- and low-temperature exhaust gas from an annular cooler. A smoke hood is provided above the sintering machine and connected to the smoke hood above the annular cooler. The medium- and low-temperature exhaust gas from the annular cooler with a temperature of 80°C to 250°C is converted from being directly discharged into the atmosphere to being directly reused in the bed of the sintering machine. This replaces the air originally inhaled from the surrounding atmosphere by the sintering machine for the sintering of raw and auxiliary fuels, thereby fully utilizing the sensible heat in the medium- and low-temperature exhaust gas and eliminating the pollution to the atmospheric environment caused by the direct discharge of dust-laden exhaust gas.

[0005] That is to say, in the existing technology, although the selective recycling of cooling exhaust gas by the ring cooler system itself can improve the utilization of waste heat of low-temperature exhaust gas to a certain extent, it still cannot solve the problem of poor quality of heat exchange steam and low utilization efficiency of medium-temperature exhaust gas; although returning medium and low-temperature exhaust gas to sintering instead of air can greatly utilize the waste heat of exhaust gas, the temperature of cooling exhaust gas is much higher than that of air, and the volume expansion of gas causes the oxygen concentration to be lower than that of normal temperature air (about 310 mg / L). The amount of oxygen drawn into the sintering material layer is reduced, which is not conducive to fuel combustion and affects the quality of sintered minerals. Therefore, the exhaust gas must be cooled to <100°C before returning to sintering, and the efficiency of utilizing the waste heat of exhaust gas in the sintering process is low. Summary of the Invention

[0006] In view of the problems in the existing technology of low efficiency and high cost of direct waste heat recovery of medium and low temperature exhaust gases in sintering ring cooling waste gas, and the need to lower the temperature when returning to sintering, resulting in low waste heat utilization efficiency, the present invention provides a method and system for recycling waste gas from a sintering ring cooler. The low-temperature exhaust gas is circulated to increase the temperature of the medium-temperature exhaust gas, and high-temperature exhaust gas is further obtained through oxygen-enriched combustion. The high-temperature exhaust gas is then subjected to step-by-step heat exchange to obtain high-quality steam, industrial hot water and low-temperature oxygen-enriched steam-containing exhaust gas that can be directly used for sintering. While realizing the waste heat recovery of medium and low temperature exhaust gases from sintering ring cooling with low cost and high efficiency, the emission of waste gas is significantly reduced, and the quality indicators of sintered mineral products and pollutant emissions are further improved.

[0007] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0008] According to a first embodiment of the present invention, a method for recycling sintering ring cooler exhaust gas is provided:

[0009] A method for recycling waste gas from a sintering ring cooler, the method comprising the following steps:

[0010] 1) After sintering, the high-temperature material passes through the ring cooling front section, ring cooling middle section and ring cooling rear section of the ring cooler in sequence to obtain the cooled material.

[0011] 2) First, cold air is sent in from the bottom air inlet of the rear section of the ring cooling, and then it exchanges heat with the low-temperature material upwards to obtain low-temperature exhaust gas. Then, the low-temperature exhaust gas is circulated through the bottom air inlet of the middle section of the ring cooling to exchange heat with the medium-temperature material to obtain medium-temperature exhaust gas.

[0012] 3) The medium-temperature exhaust gas is mixed with low-value combustible gas and then burned in oxygen-enriched combustion to produce high-temperature oxygen-enriched exhaust gas. Industrial hot water is then used to exchange heat with the high-temperature oxygen-enriched exhaust gas to produce high-quality steam and medium-temperature oxygen-enriched exhaust gas. A secondary heat exchange is then performed with ambient temperature water to produce industrial hot water and low-temperature oxygen-enriched exhaust gas. Water mist is then sprayed onto the low-temperature oxygen-enriched exhaust gas for cooling and homogenization, producing low-temperature oxygen-enriched steam-containing exhaust gas. Finally, the low-temperature oxygen-enriched steam-containing exhaust gas is circulated to the sintering surface for sintering.

[0013] Preferably, the method further comprises:

[0014] 4) Cool air is introduced through the bottom air inlet of the front section of the annular cooling system and moves upward to exchange heat with the high-temperature material, producing high-temperature exhaust gas. This high-temperature exhaust gas is then heat-exchanged with industrial hot water to produce high-quality steam, which is then mixed with the high-quality steam obtained in step 3) for power generation.

[0015] Preferably, in step 2), the temperature of the low-temperature exhaust gas is lower than 150°C, preferably 110-150°C, more preferably 120-140°C.

[0016] Preferably, in step 2), the temperature of the medium-temperature exhaust gas is not lower than 150°C, preferably 160-250°C, more preferably 170-240°C.

[0017] Preferably, in step 3), the temperature of the high-temperature oxygen-enriched exhaust gas is not less than 400° C., preferably 450-600° C., and more preferably 500-550° C. The oxygen concentration of the high-temperature oxygen-enriched exhaust gas is not less than 140 mg / L, preferably 160-300 mg / L, and more preferably 180-260 mg / L.

[0018] Preferably, in step 3), the temperature of the medium-temperature oxygen-enriched exhaust gas is not higher than 200°C, preferably 160-190°C, more preferably 170-180°C.

[0019] Preferably, in step 3), the temperature of the low-temperature oxygen-rich exhaust gas is not higher than 160°C, preferably 130-155°C, more preferably 135-150°C.

[0020] Preferably, in step 3), the pressure of the high-quality steam is not less than 1.5 MPa, preferably 1.8-3 MPa, more preferably 2-2.5 MPa. The temperature of the high-quality steam is not less than 350°C, preferably 380-500°C, more preferably 400-480°C.

[0021] Preferably, in step 3), the temperature of the low-temperature oxygen-enriched steam-containing exhaust gas is not less than 120°C, preferably 120-145°C, and more preferably 125-140°C. The oxygen concentration of the low-temperature oxygen-enriched steam-containing exhaust gas is not less than 310 mg / L, preferably 320-400 mg / L, and more preferably 330-380 mg / L. The water vapor concentration of the low-temperature oxygen-enriched steam-containing exhaust gas is not less than 3 wt%, preferably 3.2-5 wt%, and more preferably 3.5-4.5 wt%.

[0022] Preferably, in step 3), the calorific value of the low-value combustible gas is not higher than 2000 kcal. Both the primary heat exchange and the secondary heat exchange are indirect heat exchanges.

[0023] According to a second embodiment of the present invention, a sintering ring cooler exhaust gas recycling system is provided:

[0024] A system for recycling waste gas from a sintering ring cooler or a system for the method for recycling waste gas from a sintering ring cooler described in the first embodiment, the system comprising a ring cooler, an oxygen-enriched heat supplement device, and a cascade heat exchange device. According to the direction of the high-temperature material after sintering, the ring cooler comprises a ring cooling front section, a ring cooling middle section, and a ring cooling rear section connected in series. A front section air hood, a middle section air hood, and a rear section air hood are respectively provided above the ring cooling front section, the ring cooling middle section, and the ring cooling rear section. The exhaust port of the rear section air hood is connected to the bottom air inlet of the ring cooling middle section through a first waste gas conveying pipe. The exhaust port of the middle section air hood is connected to the air inlet of the oxygen-enriched heat supplement device through a second waste gas conveying pipe. The exhaust port of the oxygen-enriched heat supplement device is connected to the air inlet of the cascade heat exchange device through a third waste gas conveying pipe. The exhaust port of the cascade heat exchange device is connected to the air inlet of the sintering machine fume hood through a fourth waste gas conveying pipe.

[0025] Preferably, the system further includes a waste heat utilization device. The exhaust port of the front air hood is connected to the air inlet of the waste heat utilization device via a fifth exhaust gas delivery pipe. Preferably, the waste heat utilization device is a steam boiler.

[0026] Preferably, the system further comprises a steam power generation device. The steam outlet of the waste heat utilization device is connected to the steam inlet of the steam power generation device through a first steam delivery pipeline.

[0027] Preferably, the oxygen-enriched heat supplemental device includes a combustion chamber, an oxygen-enriched nozzle, and a combustible gas nozzle. The combustion chamber's air inlet is connected to the second exhaust gas delivery pipeline, and the combustion chamber's exhaust is connected to the third exhaust gas delivery pipeline. The oxygen-enriched nozzle and the combustible gas nozzle are both disposed within the combustion chamber and connected to the oxygen-enriched gas delivery pipeline and the combustible gas delivery pipeline, respectively.

[0028] Preferably, the cascade heat exchange device comprises a high-temperature heat exchange chamber, a low-temperature heat exchange chamber, and a cooling homogenizing chamber, connected in series from bottom to top. The air inlet of the high-temperature heat exchange chamber is connected to a third exhaust gas delivery pipeline. The exhaust outlet of the cooling homogenizing chamber is connected to a fourth exhaust gas delivery pipeline. A steam generator is installed in the high-temperature heat exchange chamber, an industrial water heater is installed in the low-temperature heat exchange chamber, and a water mist nozzle is installed in the cooling homogenizing chamber.

[0029] Preferably, the hot water outlet of the industrial water heater is connected to a hot water delivery pipeline, from which a hot water delivery branch pipe extends, connected to the hot water inlet of the steam generator. The steam outlet of the steam generator is connected to the steam inlet of the steam power generation device via a second steam delivery pipeline. The water inlet of the industrial water heater is connected to the industrial water delivery pipeline.

[0030] Preferably, the bottom air inlet of the front section of the ring cooling system and the bottom air inlet of the rear section of the ring cooling system are independently connected to cooling fans. A blower is provided between the first exhaust gas delivery duct and the bottom air inlet of the middle section of the ring cooling system.

[0031] In the present invention, the volume of the oxygen-enriched heat supplement device is 0.1-1000m 3 , preferably 1-800m 3 , more preferably 3-500m 3 The height of the cascade heat exchanger is 1-500m, preferably 2-300m, and more preferably 3-100m. All gas or liquid transport pipelines are independently equipped with flow control regulating valves. The length ratios of the annular cooling front section, annular cooling middle section, and annular cooling rear section may be the same or different.

[0032] In the present invention, the low-temperature exhaust gas (temperature < 150°C) discharged from the rear section of the ring cooler is circulated to the cooling air inlet of the middle section of the ring cooler to fully or partially replace the cold air as the cooling air of the middle section of the ring cooler to cool the sintered material. That is, by recycling the low-temperature exhaust gas, on the one hand, the direct discharge of the low-temperature exhaust gas can be completely avoided, and the temperature of the medium-temperature exhaust gas discharged from the middle section of the ring cooler with an original temperature between 150°C and 250°C can be increased to 200°C to 300°C, thereby realizing the enrichment of the sensible heat of the material and facilitating the efficient recovery of subsequent heat. On the other hand, by fully or partially replacing the cold air entering the middle section of the ring cooler, the total amount of cold air used for cooling by the ring cooler is significantly reduced, and then the output of hot exhaust gas is significantly reduced, and finally the heat discharged with the exhaust gas is also significantly reduced.

[0033] In the present invention, cold air alone is used to perform heat exchange cooling on the high-temperature material in the front section of the ring cooling, thereby obtaining high-temperature hot exhaust gas. This part of the high-temperature hot exhaust gas has a relatively high temperature (the air temperature is generally >250°C) and can be directly used as waste heat, for example, it can be transported to a preheating boiler to generate high-quality steam and used for power generation or other metallurgical processes.

[0034] In the present invention, although the temperature of the medium-temperature exhaust gas discharged from the middle section of the ring cooling is higher than that of the exhaust gas in the traditional process, there is still a disadvantage in that the wind temperature is relatively low and the waste heat utilization efficiency is relatively low when it is directly utilized (that is, it is difficult to exchange heat with industrial hot water to obtain high-parameter steam). Therefore, the medium-temperature exhaust gas is transported to the oxygen-enriched reheat chamber for oxygen-enriched combustion to achieve oxygen and heat supplementation. The oxygen-enriched combustion chamber generally uses low-value combustible gas (such as blast furnace gas, converter gas, etc., which are easy to obtain low-value gas in steel plants, can achieve self-sufficiency, and also make this part of low-value gas fully recycled and utilized; high-value fuel or gas can also be used when necessary, but the relative cost will be higher) and oxygen-enriched gas for combustion. Supplementing oxygen-enriched gas (excess oxygen) is beneficial to promote the full combustion of low-value combustible gas and thus increase the flue gas temperature. On the other hand, it can increase the oxygen concentration in the flue gas, that is, while achieving heat supplementation for the medium-temperature exhaust gas, the oxygen concentration is simultaneously increased. After oxygen-enriched combustion, the medium-temperature exhaust gas is converted into high-temperature oxygen-enriched exhaust gas with a temperature of more than 400°C and an oxygen concentration of more than 140 mg / L. In other words, by reheating the medium-temperature exhaust gas with oxygen enrichment, the medium-temperature exhaust gas that is difficult to directly utilize is converted into high-temperature oxygen-rich exhaust gas that is easy to directly utilize, and at the same time, the efficient recovery and utilization of low-value combustible gas in the plant area is achieved.

[0035] In the present invention, a step-by-step heat exchange method is used to achieve efficient recycling of high-temperature oxygen-rich waste gas, that is, the high-temperature oxygen-rich waste gas is sequentially passed through the high-temperature heat exchange zone for a primary indirect heat exchange, the low-temperature heat exchange zone for a secondary indirect heat exchange, and the steam supplement temperature control zone for cooling and homogenization, respectively generating high-quality steam, industrial hot water, and low-temperature oxygen-rich steam-containing waste gas that can be directly reused for sintering. Specifically: the high-temperature oxygen-rich waste gas is first heat-exchanged with industrial hot water in the high-temperature heat exchange zone to produce high-quality steam with a pressure ≥1.5MPa and a temperature ≥350°C for power generation, and the outlet flue gas temperature of the high-temperature heat exchange zone is reduced to 160°C~200°C (medium-temperature oxygen-rich waste gas); then the medium-temperature oxygen-rich waste gas is heat-exchanged with normal temperature water (industrial water) in the low-temperature heat exchange zone to produce industrial hot water with a temperature ≥90°C. The industrial hot water can be reused in the high-temperature heat exchange zone for heat exchange with the high-temperature oxygen-rich waste gas to generate high-quality steam or In the sintering process, the flue gas temperature at the outlet of the low-temperature heat exchange zone is reduced to 130-160°C (low-temperature oxygen-rich waste gas). Finally, the low-temperature oxygen-rich waste gas is sprayed with atomized water for heat exchange and cooling in the steam supply temperature control zone, further lowering the flue gas temperature. Simultaneously, the atomized water absorbs heat and vaporizes into water vapor, ultimately producing low-temperature oxygen-rich steam-containing waste gas with a temperature of 120-145°C, an oxygen concentration of 310mg / L-400mg / L, and a water vapor concentration of 3%-5%, which can be directly reused in sintering. In other words, the present invention achieves efficient, step-by-step utilization of high-temperature oxygen-rich waste gas through a cascade heat exchange method, resulting in a multi-stage product that can be directly recycled internally, achieving complete utilization of the high-temperature oxygen-rich waste gas with no waste gas emissions.

[0036] In the present invention, low-temperature oxygen-rich steam-containing exhaust gas is transported through a pipe connected to the smoke hood above the sintering machine, and then returned to the sintering material surface, replacing room-temperature air to enter the sintering material layer to promote the sintering reaction.

[0037] In the present invention, the recycling system of the exhaust gas of the sintering ring cooler of the present invention adopts pipes and valves to connect the air inlet of the blower of the medium-temperature section of the ring cooler in the smoke hood above the rear section of the sintering ring cooler, so that the cooling exhaust gas of the low-temperature section circulates as the cooling medium of the middle section of the ring cooler; and further continues to adopt pipes to connect the exhaust gas of the low-temperature section to the air inlet of the oxygen-enriched heat supplement device above the middle section of the ring cooler, and the oxygen-enriched heat supplement device is provided with a heat supplement and oxygen supplement mechanism for increasing the temperature and oxygen concentration of the medium-temperature exhaust gas of the ring cooler, which can be an independent heat supplement burner and oxygen supplement nozzle, or an oxygen-enriched combustion burner; the air outlet of the oxygen-enriched heat supplement device is connected to the air inlet of the cascade heat exchange device through a pipe, and the cascade heat exchange device From bottom to top, it includes a high-temperature heat exchange chamber, a low-temperature heat exchange chamber and a cooling homogenizing chamber; the high-temperature heat exchange chamber is provided with a high-parameter steam generator for heat exchange with the flue gas after oxygen-enriched heat supplementation to produce high-quality steam for power generation; the low-temperature heat exchange chamber is provided with an industrial water heater for further heat exchange with the exhaust gas leaving the high-temperature heat exchange chamber, and to generate industrial hot water to supply the steam generator and sintering production process in the high-temperature heat exchange chamber; the cooling homogenizing chamber is provided with a water mist nozzle for spraying water mist on the exhaust gas leaving the low-temperature heat exchange chamber, thereby reducing the exhaust gas temperature and increasing the concentration of water vapor in the exhaust gas, thereby obtaining low-temperature oxygen-enriched steam-containing exhaust gas that can be directly reused for sintering.

[0038] In the present invention, the method and system of the present invention adopt technical means such as cascade utilization of comprehensive sintering ring-cooled low-temperature exhaust gas, simultaneous heat and oxygen supplementation and quality improvement of medium-temperature exhaust gas, and cascade heat exchange and steam enrichment. First, the ring-cooled low-temperature exhaust gas is returned to the air inlet of the medium-temperature section to serve as a cooling medium, eliminating the direct emission of low-temperature exhaust gas and increasing the temperature of the medium-temperature exhaust gas. Then, low-value coal gas combustion in the steel plant is used for heat supplementation and coordinated oxygen supplementation or oxygen-enriched combustion to increase the temperature of the medium-temperature exhaust gas to meet the production requirements of high-parameter steam while significantly increasing the oxygen content in the exhaust gas. After heat exchange to produce high-quality steam and industrial hot water, water mist is sprayed to further control the flue gas temperature, thereby achieving the purpose of containing a certain amount of water vapor in the exhaust gas. By taking the above technical measures, first, the recovery of waste heat from medium and low-temperature exhaust gases in sintering ring cooling is transformed from direct emission or recovery of low-parameter steam to recovery of high-parameter steam, thereby improving the quality and efficiency of waste heat recovery; second, oxygen and steam are added to the medium and low-temperature exhaust gases while replenishing heat, thereby increasing the oxygen concentration in the exhaust gas finally returned to sintering (≥310 mg / L of oxygen concentration in normal temperature air), so that when the exhaust gas temperature entering sintering is greater than 120°C, its oxygen content can still meet the needs of the sintering reaction, eliminating the negative impact of thin oxygen at high temperature on the sintering process, and improving the utilization rate of waste heat from the sintering process; third, the exhaust gas finally returned to the sintering material surface contains both excess oxygen and some steam compared to ordinary air, superimposing the improvement effects of the existing "oxygen-enriched sintering technology" and "material surface water steam injection technology" on sintering. When this exhaust gas is used to replace air for sintering, the quality indicators of sintered minerals can be significantly improved and pollutant emissions can be reduced.

[0039] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0040] 1: The method and system provided by the present invention adopt the low-value coal gas combustion in the steel plant to supplement heat and coordinate oxygen supplementation or oxygen-enriched combustion to increase the temperature of the ring-cooled medium and low-temperature exhaust gas to meet the production requirements of high-parameter steam, and at the same time significantly increase the oxygen content in the exhaust gas (≥ the oxygen concentration of air at room temperature), so that when the exhaust gas temperature is greater than 120°C, the oxygen content entering the sintering material layer can still meet the reaction needs, eliminate the negative impact of the dilute oxygen at high temperature on the sintering process, and improve the utilization rate of the exhaust gas waste heat in the waste heat recovery process and the sintering process.

[0041] 2: The method and system provided by the present invention sprays water mist according to the control target of the final exhaust gas temperature after the exhaust gas completes the heat exchange process, so that the flue gas temperature is reduced and oxygen is enriched while generating a certain amount of water vapor. After returning to sintering, it plays the excellent effect of dual auxiliary sintering of oxygen enrichment and water vapor injection, significantly improving the sintering quality.

[0042] 3: The method and system provided by the present invention integrates units such as heat supplement, oxygen enrichment, temperature control, and steam injection, and comprehensively utilizes the positive effects of technical means such as cascade utilization of low-temperature exhaust gas from sintering ring cooling, simultaneous heat and oxygen supplementation and quality improvement of medium-temperature exhaust gas, and cascade heat exchange and steam enrichment, thereby greatly improving the waste heat utilization efficiency of medium and low-temperature exhaust gas from the ring cooler, while improving the quality indicators of sintered minerals, significantly reducing exhaust gas and waste heat emissions, and reducing pollutant emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is a process flow chart of the method for recycling waste gas from a sintering ring cooler according to the present invention.

[0044] FIG2 is a simplified structural diagram of the sintering ring cooler waste gas recycling system according to the present invention.

[0045] FIG3 is a schematic diagram of the overall structure of the sintering ring cooler waste gas recycling system of the present invention.

[0046] Reference numerals: 1: annular cooler; 101: annular cooling front section; 102: annular cooling middle section; 103: annular cooling rear section; 104: annular cooling front section gas hood; 105: annular cooling middle section gas hood; 106: annular cooling rear section gas hood; 107: a first exhaust gas delivery pipeline; 108: a second exhaust gas delivery pipeline; 109: a third exhaust gas delivery pipeline; 110: a fourth exhaust gas delivery pipeline; 111: a fifth exhaust gas delivery pipeline; 2: an oxygen-enriched heat supplement device; 201: a combustion chamber; 202: an oxygen-enriched nozzle; 203: a combustible gas nozzle; 204 : Oxygen-enriched gas delivery pipeline; 205: Combustible gas delivery pipeline; 3: Cascade heat exchange device; 301: High-temperature heat exchange chamber; 302: Low-temperature heat exchange chamber; 303: Cooling and homogenizing chamber; 304: Steam generator; 305: Industrial water heater; 306: Water mist nozzle; 307: Hot water delivery pipeline; 308: Hot water delivery branch pipe; 309: Second steam delivery pipeline; 310: Industrial water delivery pipeline; 4: Waste heat utilization device; 401: First steam delivery pipeline; 5: Steam power generation device. DETAILED DESCRIPTION

[0047] The technical solutions of the present invention are illustrated below with examples, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0048] Example 1

[0049] As shown in FIG1 , a method for recycling waste gas from a sintering ring cooler comprises the following steps:

[0050] 1) After sintering, the high-temperature material passes through the ring cooling front section, ring cooling middle section and ring cooling rear section of the ring cooler in sequence to obtain the cooled material.

[0051] 2) First, cold air is sent in from the bottom air inlet of the rear section of the ring cooling, and then it exchanges heat with the low-temperature material upwards to obtain low-temperature exhaust gas. Then, the low-temperature exhaust gas is circulated through the bottom air inlet of the middle section of the ring cooling to exchange heat with the medium-temperature material to obtain medium-temperature exhaust gas.

[0052] 3) The medium-temperature exhaust gas is mixed with low-value combustible gas and then burned in oxygen-enriched combustion to produce high-temperature oxygen-enriched exhaust gas. Industrial hot water is then used to exchange heat with the high-temperature oxygen-enriched exhaust gas to produce high-quality steam and medium-temperature oxygen-enriched exhaust gas. A secondary heat exchange is then performed with ambient temperature water to produce industrial hot water and low-temperature oxygen-enriched exhaust gas. Water mist is then sprayed onto the low-temperature oxygen-enriched exhaust gas for cooling and homogenization, producing low-temperature oxygen-enriched steam-containing exhaust gas. Finally, the low-temperature oxygen-enriched steam-containing exhaust gas is circulated to the sintering surface for sintering.

[0053] Example 2

[0054] Repeat Example 1, except that the method further comprises:

[0055] 4) Cool air is introduced through the bottom air inlet of the front section of the annular cooling system and moves upward to exchange heat with the high-temperature material, producing high-temperature exhaust gas. This high-temperature exhaust gas is then heat-exchanged with industrial hot water to produce high-quality steam, which is then mixed with the high-quality steam obtained in step 3) for power generation.

[0056] Example 3

[0057] Example 2 was repeated, except that in step 2), the temperature of the low-temperature exhaust gas was lower than 170°C, and the temperature of the medium-temperature exhaust gas was not lower than 170°C.

[0058] Example 4

[0059] Example 3 was repeated, except that the temperature range of the low-temperature exhaust gas was 120-165°C and the temperature range of the medium-temperature exhaust gas was 180-250°C.

[0060] Example 5

[0061] Example 4 was repeated, except that the temperature range of the low-temperature exhaust gas was 130-150°C and the temperature range of the medium-temperature exhaust gas was 200-240°C.

[0062] Example 6

[0063] Example 5 is repeated, except that in step 3), the temperature of the high-temperature oxygen-rich exhaust gas is not lower than 400°C. The oxygen concentration of the high-temperature oxygen-rich exhaust gas is not lower than 140 mg / L. The temperature of the medium-temperature oxygen-rich exhaust gas is not higher than 200°C. The temperature of the low-temperature oxygen-rich exhaust gas is not higher than 160°C. The pressure of the high-quality steam is not lower than 1.5 MPa. The temperature of the high-quality steam is not lower than 350°C. The temperature of the low-temperature oxygen-rich steam-containing exhaust gas is not lower than 120°C. The oxygen concentration of the low-temperature oxygen-rich steam-containing exhaust gas is not lower than 310 mg / L. The water vapor concentration of the low-temperature oxygen-rich steam-containing exhaust gas is not lower than 3wt%.

[0064] Example 7

[0065] Example 6 is repeated, except that the temperature range of the high-temperature oxygen-rich exhaust gas is 450~600℃. The oxygen concentration range of the high-temperature oxygen-rich exhaust gas is 160~300mg / L. The temperature range of the medium-temperature oxygen-rich exhaust gas is 160~190℃. The temperature range of the low-temperature oxygen-rich exhaust gas is 130~155℃. The pressure range of the high-quality steam is 1.8~3MPa. The temperature range of the high-quality steam is 380~500℃. The temperature range of the low-temperature oxygen-rich steam-containing exhaust gas is 120~145℃. The oxygen concentration range of the low-temperature oxygen-rich steam-containing exhaust gas is 320~400mg / L. The water vapor concentration range of the low-temperature oxygen-rich steam-containing exhaust gas is 3.2~5%.

[0066] Example 8

[0067] Example 7 is repeated, except that the temperature range of the high-temperature oxygen-rich exhaust gas is 500~550℃. The oxygen concentration range of the high-temperature oxygen-rich exhaust gas is 180~260mg / L. The temperature range of the medium-temperature oxygen-rich exhaust gas is 170~180℃. The temperature range of the low-temperature oxygen-rich exhaust gas is 135~150℃. The pressure range of the high-quality steam is 2~2.5MPa. The temperature range of the high-quality steam is 400~480℃. The temperature range of the low-temperature oxygen-rich steam-containing exhaust gas is 125~140℃. The oxygen concentration range of the low-temperature oxygen-rich steam-containing exhaust gas is 330~380mg / L. The water vapor concentration range of the low-temperature oxygen-rich steam-containing exhaust gas is 3.5~4.5%.

[0068] Example 9

[0069] Example 8 was repeated, except that in step 3), the calorific value of the low-value combustible gas was approximately 1912 kcal. Both the primary heat exchange and the secondary heat exchange were indirect heat exchanges.

[0070] Example 10

[0071] As shown in Figures 2-3, a system for recycling waste gas from a sintering ring cooler is shown. The system includes a ring cooler 1, an oxygen-enriched heat recovery device 2, and a cascade heat exchange device 3. Based on the flow of the high-temperature material after sintering, the ring cooler 1 includes a front section 101, a middle section 102, and a rear section 103 connected in series. A front section hood 104, a middle section hood 105, and a rear section hood 106 are respectively disposed above the front section 101, the middle section 102, and the rear section 103. The exhaust port of the rear section hood 106 is connected to the bottom air inlet of the middle section 102 via a first exhaust gas conveying pipe 107. The exhaust port of the middle section hood 105 is connected to the air inlet of the oxygen-enriched heat recovery device 2 via a second exhaust gas conveying pipe 108. The exhaust port of the oxygen-enriched heat recovery device 2 is connected to the air inlet of the cascade heat exchange device 3 via a third exhaust gas conveying pipe 109. The exhaust port of the cascade heat exchange device 3 is connected to the air inlet of the sintering machine hood through the fourth exhaust gas conveying pipe 110.

[0072] Example 11

[0073] Repeat Example 10, except that the system further includes a waste heat utilization device 4. The exhaust port of the front air hood 104 is connected to the air inlet of the waste heat utilization device 4 through the fifth exhaust gas conveying pipe 111. Preferably, the waste heat utilization device 4 is a steam boiler.

[0074] Example 12

[0075] The embodiment 11 is repeated except that the system further includes a steam power generation device 5. The steam outlet of the waste heat utilization device 4 is connected to the steam inlet of the steam power generation device 5 through the first steam delivery pipeline 401.

[0076] Example 13

[0077] Example 12 was repeated, except that the oxygen-enriched heat supplemental device 2 included a combustion chamber 201, an oxygen-enriched nozzle 202, and a combustible gas nozzle 203. The air inlet of combustion chamber 201 was connected to the second exhaust gas delivery pipeline 108, and the exhaust port of combustion chamber 201 was connected to the third exhaust gas delivery pipeline 109. Both the oxygen-enriched nozzle 202 and the combustible gas nozzle 203 were disposed within combustion chamber 201 and connected to the oxygen-enriched gas delivery pipeline 204 and the combustible gas delivery pipeline 205, respectively.

[0078] Example 14

[0079] Example 13 was repeated, except that the cascade heat exchange device 3 included a high-temperature heat exchange chamber 301, a low-temperature heat exchange chamber 302, and a cooling and homogenizing chamber 303, connected in series from bottom to top. The air inlet of the high-temperature heat exchange chamber 301 was connected to the third exhaust gas conveying pipeline 109. The exhaust outlet of the cooling and homogenizing chamber 303 was connected to the fourth exhaust gas conveying pipeline 110. A steam generator 304 was installed in the high-temperature heat exchange chamber 301, an industrial water heater 305 was installed in the low-temperature heat exchange chamber 302, and a water mist nozzle 306 was installed in the cooling and homogenizing chamber 303.

[0080] Example 15

[0081] Example 14 was repeated, except that the hot water outlet of the industrial water heater 305 was connected to a hot water delivery pipe 307. A hot water delivery branch pipe 308 branched from the hot water delivery pipe 307 and connected to the hot water inlet of the steam generator 304. The steam outlet of the steam generator 304 was connected to the steam inlet of the steam power generation device 5 via a second steam delivery pipe 309. The water inlet of the industrial water heater 305 was connected to an industrial water delivery pipe 310.

[0082] Example 16

[0083] Example 15 was repeated except that the bottom air inlet of the front section 101 and the bottom air inlet of the rear section 103 were independently connected to cooling fans. A blower was provided between the first exhaust gas delivery duct 107 and the bottom air inlet of the middle section 102.

[0084] Application Example 1

[0085] The method described in Example 9 and the system described in Example 16 are used to recycle the ring cooling waste gas generated by ring cooling of sintered ore:

[0086] The low-temperature exhaust gas (approximately 142°C) from the rear section of the annular cooler is first circulated through a pipeline back to the inlet of the middle section of the annular cooler, where it serves as a cooling medium to cool the medium-temperature materials, generating medium-temperature exhaust gas at approximately 271°C. This medium-temperature exhaust gas is then fed into an oxygen-enriched reheating unit for oxygenation and heat replenishment, producing high-temperature oxygen-enriched exhaust gas at approximately 512°C and an oxygen concentration of approximately 210 mg / L. This high-temperature oxygen-enriched exhaust gas is then fed into a cascade heat exchanger, passing through a high-temperature heat exchange chamber, a low-temperature heat exchange chamber, and a cooling and homogenizing chamber for heat exchange. This process generates high-parameter steam at a flow rate of approximately 49 t / h, a pressure of approximately 1.8 MPa, and a temperature of approximately 410°C, and hot water at a flow rate of approximately 50 t / h and a temperature of approximately 90°C. This low-temperature oxygen-enriched steam-containing exhaust gas is simultaneously generated at a temperature of approximately 137°C, an oxygen content of approximately 364 mg / L, and a water vapor content of approximately 3.5%. This low-temperature oxygen-enriched steam-containing exhaust gas is then returned to the sintering surface for sintering. Compared with conventional processes, the medium-temperature waste heat exhaust gas is directly utilized, and the hot air temperature on the sintering material surface is increased by about 37°C. The overall waste heat utilization rate of the ring cooling exhaust gas is increased by about 26%, the sintering ore return rate is reduced by about 1%, the sintering ore drum strength is increased by about 1.5%, and the utilization coefficient is increased by about 0.026t / m 2 ·h -1 .

[0087] Comparative Example 1

[0088] Conventional processes are used for cooling sintered ore. The exhaust gas from the low-temperature cooling section of the ring cooler (about 142°C) is directly discharged, and the exhaust gas from the medium-temperature cooling section of the ring cooler (about 219°C) is exchanged with waste heat boilers and industrial water to generate low-parameter steam with a flow rate of about 11.5t / h, a pressure of about 0.4MPa, and a temperature of about 180°C, and hot water with a flow rate of about 50t / h and a temperature of about 90°C. This low-pressure steam cannot be fully utilized in the plant, and its heat utilization efficiency is low.

[0089] Comparative Example 2

[0090] Conventional processes are used to cool sintered ore. The exhaust gas from the low-temperature cooling section of the ring cooler (about 142°C) is directly discharged, and the exhaust gas from the medium-temperature cooling section of the ring cooler (about 219°C) is returned to the sintering ignition section and the sintering material surface. Due to the high exhaust gas temperature, significant volume expansion, and thin oxygen content (about 188 mg / L), the amount of oxygen absorbed into the sintering material layer per unit time is low, and the quality of the sintered ore is reduced. In order to ensure the sintering quality, a large amount of cold air must be added to lower the exhaust gas temperature, resulting in the inability to fully utilize the cooling exhaust gas and its heat.

Claims

1. A method for recycling sintering ring cooler exhaust gas, characterized by: The method comprises the following steps: 1) The high-temperature material after sintering passes through the ring cooling front section, ring cooling middle section and ring cooling rear section of the ring cooling machine in sequence to obtain the cooled material; 2) First, cold air is sent in from the bottom air inlet of the rear section of the ring cooling, and is transferred upward to exchange heat with the low-temperature material to obtain low-temperature exhaust gas; then the low-temperature exhaust gas is circulated through the bottom air inlet of the middle section of the ring cooling to exchange heat with the medium-temperature material to obtain medium-temperature exhaust gas; 3) The medium-temperature exhaust gas is mixed with the low-value combustible gas and then subjected to oxygen-enriched combustion to obtain high-temperature oxygen-enriched exhaust gas. Industrial hot water is then used to perform a heat exchange with the high-temperature oxygen-enriched exhaust gas to obtain high-quality steam and medium-temperature oxygen-enriched exhaust gas. Normal temperature water is then used to perform a secondary heat exchange with the medium-temperature oxygen-enriched exhaust gas to obtain industrial hot water and low-temperature oxygen-enriched exhaust gas. Water mist is then sprayed into the low-temperature oxygen-enriched exhaust gas for cooling and homogenization to obtain low-temperature oxygen-enriched steam-containing exhaust gas. Finally, the low-temperature oxygen-enriched steam-containing exhaust gas is circulated to the sintering material surface to participate in the sintering process.

2. The method according to claim 1, wherein: The method further includes: 4) Cold air is introduced from the bottom air inlet of the front section of the ring cooling, and is transferred upward to exchange heat with the high-temperature material to obtain high-temperature exhaust gas; then, industrial hot water is used to exchange heat with the high-temperature exhaust gas to obtain high-quality steam, and the obtained high-quality steam is mixed with the high-quality steam obtained in step 3) for power generation.

3. The method according to claim 1 or 2, characterized in that: In step 2), the temperature of the low-temperature exhaust gas is lower than 150° C., preferably 110-150° C., more preferably 120-140° C.; and / or In step 2), the temperature of the medium-temperature exhaust gas is not less than 150°C, preferably 160-250°C, more preferably 170-240°C.

4. The method according to any one of claims 1 to 3, characterized in that: In step 3), the temperature of the high-temperature oxygen-rich exhaust gas is not less than 400°C, preferably 450-600°C, and more preferably 500-550°C; the oxygen concentration of the high-temperature oxygen-rich exhaust gas is not less than 140 mg / L, preferably 160-300 mg / L, and more preferably 180-260 mg / L.

5. The method according to any one of claims 1 to 4, characterized in that: In step 3), the temperature of the medium-temperature oxygen-rich exhaust gas is not higher than 200°C, preferably 160-190°C, more preferably 170-180°C; and / or In step 3), the temperature of the low-temperature oxygen-rich exhaust gas is not higher than 160° C., preferably 130-155° C., more preferably 135-150° C.; and / or In step 3), the pressure of the high-quality steam is not less than 1.5 MPa, preferably 1.8-3 MPa, more preferably 2-2.5 MPa; the temperature of the high-quality steam is not less than 350°C, preferably 380-500°C, more preferably 400-480°C.

6. The method according to any one of claims 1 to 5, characterized in that: In step 3), the temperature of the low-temperature oxygen-enriched steam-containing exhaust gas is not less than 120° C., preferably 120-145° C., more preferably 125-140° C.; the oxygen concentration of the low-temperature oxygen-enriched steam-containing exhaust gas is not less than 310 mg / L, preferably 320-400 mg / L, more preferably 330-380 mg / L; the water vapor concentration of the low-temperature oxygen-enriched steam-containing exhaust gas is not less than 3wt%, preferably 3.2-5wt%, more preferably 3.5-4.5wt%; Preferably, in step 3), the calorific value of the low-value combustible gas is not higher than 2000 kcal; and the primary heat exchange and the secondary heat exchange are both indirect heat exchanges.

7. A system for recycling waste gas from a sintering ring cooler or a system for the method for recycling waste gas from a sintering ring cooler according to any one of claims 1 to 6, characterized in that: The system comprises a ring cooler (1), an oxygen-enriched heat supplement device (2) and a cascade heat exchange device (3); according to the direction of the high-temperature material after sintering, the ring cooler (1) comprises a ring cooling front section (101), a ring cooling middle section (102) and a ring cooling rear section (103) connected in series; a front section gas hood (104), a middle section gas hood (105) and a rear section gas hood (106) are respectively arranged above the ring cooling front section (101), the ring cooling middle section (102) and the ring cooling rear section (103); the exhaust of the rear section gas hood (106) The air port is connected to the bottom air inlet of the annular cooling middle section (102) through the first waste gas delivery pipe (107); the exhaust port of the middle section air hood (105) is connected to the air inlet of the oxygen-enriched heat supplement device (2) through the second waste gas delivery pipe (108); the exhaust port of the oxygen-enriched heat supplement device (2) is connected to the air inlet of the cascade heat exchange device (3) through the third waste gas delivery pipe (109); the exhaust port of the cascade heat exchange device (3) is connected to the air inlet of the sintering machine smoke hood through the fourth waste gas delivery pipe (110).

8. The system according to claim 7, characterized in that: The system further comprises a waste heat utilization device (4); the exhaust port of the front air hood (104) is connected to the air inlet of the waste heat utilization device (4) via a fifth waste gas delivery pipe (111); preferably, the waste heat utilization device (4) is a steam boiler; Preferably, the system further comprises a steam power generation device (5); the steam outlet of the waste heat utilization device (4) is connected to the steam inlet of the steam power generation device (5) via a first steam delivery pipeline (401).

9. The system according to claim 7 or 8, characterized in that: The oxygen-enriched heat supplement device (2) comprises a combustion chamber (201), an oxygen-enriched nozzle (202), and a combustible gas nozzle (203); an air inlet of the combustion chamber (201) is connected to a second waste gas delivery pipe (108), and an exhaust port of the combustion chamber (201) is connected to a third waste gas delivery pipe (109); the oxygen-enriched nozzle (202) and the combustible gas nozzle (203) are both arranged in the combustion chamber (201) and are respectively connected to an oxygen-enriched gas delivery pipe (204) and a combustible gas delivery pipe (205).

10. The system according to any one of claims 7 to 9, characterized in that: The cascade heat exchange device (3) comprises a high-temperature heat exchange chamber (301), a low-temperature heat exchange chamber (302), and a cooling homogenizing chamber (303) connected in series from bottom to top; an air inlet of the high-temperature heat exchange chamber (301) is connected to a third exhaust gas delivery pipe (109); an exhaust port of the cooling homogenizing chamber (303) is connected to a fourth exhaust gas delivery pipe (110); a steam generator (304) is provided in the high-temperature heat exchange chamber (301), an industrial water heater (305) is provided in the low-temperature heat exchange chamber (302), and a water mist nozzle (306) is provided in the cooling homogenizing chamber (303); Preferably, the hot water outlet of the industrial water heater (305) is connected to a hot water delivery pipe (307), and a hot water delivery branch pipe (308) connected to the hot water inlet of the steam generator (304) is led out from the hot water delivery pipe (307); the steam outlet of the steam generator (304) is connected to the steam inlet of the steam power generation device (5) through a second steam delivery pipe (309); the water inlet of the industrial water heater (305) is connected to the industrial water delivery pipe (310); Preferably, the bottom air inlet of the annular cooling front section (101) and the bottom air inlet of the annular cooling rear section (103) are independently connected to cooling fans; and a blower is provided between the first exhaust gas conveying duct (107) and the bottom air inlet of the annular cooling middle section (102).

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