Near-zero emission method for lump ore drying and circular cooler coupling

Abstract

A lump ore drying and circular cooler coupled near-zero emission method comprises the steps that (1) sinter to be cooled sequentially passes through a high-temperature area, a medium-temperature area and a low-temperature area of a circular cooler to be cooled, and the cooled sinter is discharged from a discharging port of the circular cooler; (2) the lump ore to be dried enters a drying machine to be dried, and the dried lump ore is discharged from a discharging opening of the drying machine; (3) the cooling air enters a high-temperature area of the circular cooler and exchanges heat with the sintered ore in the high-temperature area, and after heat exchange, high-temperature hot air discharged from the high-temperature area is pumped back to the high-temperature area to circularly cool the sintered ore after waste heat utilization; and (4) cooling air entering the medium-low temperature area of the circular cooler continues to cool the sintered ore, mixed hot air discharged from the medium-low temperature area is conveyed to the drying machine to dry lump ore after heat exchange with the sintered ore, and dry air discharged from the drying machine is condensed and then pumped back to the medium-low temperature area to circularly cool the sintered ore. According to the system, lump ore drying and the circular cooler are coupled, and full utilization and near-zero emission of waste gas waste heat of the circular cooler are achieved.

Description

Technical Field

[0001] The invention relates to the utilization of waste heat resources of waste gas from a ring cooler, and in particular to a near-zero emission method for coupling lump ore drying with a ring cooler, belonging to the technical fields of metallurgy and environmental protection. Background Art

[0002] As one of the main components of blast furnace charge, natural lump ore can be added in an amount of up to 30%. At present, the proportion of lump ore entering the furnace is generally 5-15%, which is relatively low. The reason is that there are problems with powder and high moisture content in lump ore. Due to the high moisture content of lump ore, generally 8-15%, the moisture content of lump ore in the rainy season of some port steel mills even exceeds 20%. After the high-moisture lump ore enters the furnace, energy is consumed to dry the moisture, and the drying process takes a certain amount of time, which increases the coke ratio of the blast furnace, resulting in an increase in the smelting cost of the blast furnace, and affects the normal production of the blast furnace, which has a significant impact on the smooth operation of the steel process and the economic benefits of the steel plant. Therefore, reducing the moisture content of lump ore is of great significance to reducing the cost of ironmaking and enhancing the stability of the furnace condition. At present, the lump ore drying system has problems such as high construction cost, low drying efficiency, and high energy consumption.

[0003] At present, the domestic ring cooler exhaust gas has basically recovered the high-temperature waste heat resources of the first and second stages. The waste heat resources at the rear of the ring cooler are difficult to use because the exhaust temperature is too low. On the other hand, domestic ring coolers have basically not achieved zero emissions, resulting in a large amount of high-temperature dust-containing exhaust gas being directly discharged into the atmosphere, polluting the environment. For the low-temperature exhaust gas after the first and second stages of the ring cooler, some domestic sintering plants have also adopted the method of recycling exhaust gas to produce steam to recover this part of the waste heat. Because the exhaust temperature is too high after recycling, it is impossible to cool the discharge temperature of the ring cooler to the design value. The sintering system can only operate at a reduced load, affecting the output of sintered ore. Summary of the invention

[0004] In view of the problems of high construction cost, low drying efficiency and high energy consumption in the lump ore drying system in the above-mentioned prior art, as well as the problem that the waste heat of exhaust gas in the low-temperature section of the ring cooler is difficult to utilize and it is difficult to achieve zero emissions, the present invention couples the drying of lump ore with the utilization of waste heat of exhaust gas in the low-temperature section of the ring cooler, and proposes a near-zero emission method of coupling lump ore drying with a ring cooler. In the technical scheme of the present invention, on the one hand, the waste heat of the exhaust gas in the high temperature zone of the ring cooler is fully utilized, and the high-temperature hot air discharged from the high temperature zone is drawn back to the high temperature zone of the ring cooler after the waste heat is utilized, so as to circulate and cool the sintered ore in this area; on the other hand, the mixed hot air discharged from the medium and low temperature zone of the ring cooler is transported to the dryer to dry the lump ore, so as to fully utilize the waste heat of the exhaust gas in the medium and low temperature zone of the ring cooler. After the drying is completed, the dry air discharged from the dryer is drawn back to the medium and low temperature zone of the ring cooler for circulated cooling of the sintered ore, that is, through the air volume balance and heat balance between the sintered ore ring cooler and the lump ore dryer, the near-zero emission of the lump ore drying and the coupling of the ring cooler is finally achieved, which effectively solves the problem that the waste heat of the exhaust gas in the low temperature zone of the existing ring cooler is difficult to utilize and it is difficult to achieve zero emission, while reducing the investment cost of lump ore drying and improving the drying efficiency of lump ore.

[0005] According to an embodiment of the present invention, a near-zero emission method of lump ore drying coupled with a ring cooler is provided.

[0006] A near-zero emission method for lump ore drying coupled with a ring cooler, the method comprising the following steps:

[0007] 1) The sintered ore to be cooled enters the ring cooler and is cooled in the high temperature zone, medium temperature zone and low temperature zone in turn. The cooled sintered ore is discharged from the discharge port of the ring cooler.

[0008] 2) The lump ore to be dried enters the dryer for drying, and the dried lump ore is discharged from the discharge port of the dryer.

[0009] 3) The cooling air enters the high temperature zone of the ring cooler and exchanges heat with the sintered ore to be cooled in the high temperature zone. After the heat exchange, the temperature of the cooling air increases to form high temperature hot air, which is discharged from the air outlet of the high temperature zone. The high temperature hot air is drawn back to the high temperature zone after waste heat utilization to circulate and cool the sintered ore to be cooled.

[0010] 4) The cooling air entering the medium temperature zone and low temperature zone of the ring cooler continues to cool the sintered ore. After heat exchange with the sintered ore, the temperature of the cooling air rises to form medium and low temperature hot air, which are discharged from the air outlets of the medium temperature zone and low temperature zone respectively. The medium and low temperature hot air are mixed and transported to the air inlet of the dryer. The mixed hot air dries the lump ore in the dryer. The dry air discharged from the dryer is condensed and then drawn back to the medium temperature zone and low temperature zone to circulate and cool the sintered ore.

[0011] In the present invention, in step 3), the high-temperature hot air is drawn back to the high-temperature zone of the ring cooler through the high-temperature zone air inlet duct after waste heat utilization. The high-temperature zone air inlet duct is connected to a first natural wind duct. The initial cooling air entering the high-temperature zone of the ring cooler is supplied by the first natural wind duct.

[0012] In the present invention, in step 4), the dry air is condensed and then drawn back to the medium temperature zone and the low temperature zone of the ring cooler through the medium and low temperature zone air inlet duct. The medium and low temperature zone air inlet duct is connected to a second natural air duct. The initial cooling air entering the medium temperature zone and the low temperature zone of the ring cooler is supplied by the second natural air duct.

[0013] In the present invention, after the initial cooling air supply to the high temperature zone is completed, the high temperature zone solenoid valve disposed on the first natural air duct is closed.

[0014] In the present invention, after the initial cooling air supply to the medium-temperature zone and the low-temperature zone is completed, the medium- and low-temperature zone solenoid valve disposed on the second natural wind duct is closed.

[0015] In the present invention, a first circulation fan is provided on the high temperature zone air inlet duct, and the first circulation fan is located downstream of the connection position between the first natural wind duct and the high temperature zone air inlet duct.

[0016] In the present invention, a second circulation fan is provided on the medium and low temperature zone air inlet duct, and the second circulation fan is located downstream of the connection position between the second natural wind duct and the medium and low temperature zone air inlet duct.

[0017] In the present invention, in step 1), the temperature of the sintered ore after cooling is ≤120° C. In step 2), the moisture content of the dried agglomerate is ≤2%.

[0018] In the present invention, in step 3), the temperature of the high-temperature hot air is ≥350°C. In step 4), the temperature of the mixed hot air obtained by mixing the medium- and low-temperature hot air is 150-250°C. The temperature of the drying air is 70-90°C.

[0019] In the present invention, the method further comprises the step of calculating the cooling air volume of the high temperature zone of the ring cooler, which specifically comprises the following sub-steps:

[0020] ① The mathematical model of gas-solid heat transfer is established for the cooling process of the sintered ore in the high temperature zone of the ring cooler, and the following is obtained:

[0021]

[0022] in:

[0023]

[0024] Nu=0.198ε 0.07 Rep 0.66 Pr 1 / 3 ……(3).

[0025]

[0026] Where: E x It is the heat exchange of the sintered ore bed to be cooled in the high temperature zone of the ring cooler. v is the gas-solid heat transfer coefficient. ΔT is the gas-solid temperature difference between the cooling air and the sintered ore to be cooled in the high temperature zone of the ring cooler. V 高 T is the volume of the sintered ore bed to be cooled in the high temperature zone of the ring cooler. H is the height of the sintered ore bed to be cooled in the high temperature zone of the ring cooler. s1 is the initial temperature of the sintered ore to be cooled. T2 is the temperature of the high-temperature hot air discharged from the high-temperature zone. T1 is the temperature of the cooling air drawn back to the high-temperature zone after waste heat utilization. g1 Cp is the cooling air volume entering the high temperature zone of the ring cooler per unit time. g is the specific heat capacity of the cooling air. Nu is the Nusselt number of gas-solid heat transfer in the sintering bed. g is the thermal conductivity of the cooling air. ε is the porosity of the sintering bed. p Re is the particle size of sintered ore. p is the Reynolds number of sintered ore particles. Pr is the Prandtl number. ρ g is the density of cooling air. u g is the apparent velocity of cooling air. μ is the dynamic viscosity of cooling air.

[0027] ② Detect the initial temperature T of the sintered ore to be cooled s1 , the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization T1, the volume of the sintered ore bed to be cooled in the high temperature zone of the ring cooler V 高 , the height H of the sintered ore bed to be cooled in the high temperature zone of the ring cooler, and the temperature T2 of the high temperature hot air discharged from the high temperature zone is set to be ≥ 350°C. Formulas (1)-(5) are combined to calculate the cooling air volume V entering the high temperature zone of the ring cooler per unit time. g1 .

[0028] Open the high temperature zone solenoid valve on the first natural air duct, and adjust the first circulating fan on the high temperature zone air inlet duct so that the cooling air volume entering the high temperature zone of the ring cooler per unit time is V g1 .

[0029] In the present invention, the method further includes the step of calculating the cooling air volume of the medium and low temperature zones of the ring cooler, which specifically includes the following sub-steps:

[0030] ① According to the heat balance between the sintered ore and the cooling air in the ring cooler, it can be obtained that the heat released by the sintered ore to be cooled during the cooling process is equal to the sum of the heat absorbed by the cooling air in the high temperature zone of the ring cooler and the heat absorbed by the cooling air in the medium temperature zone and the low temperature zone of the ring cooler. That is:

[0031] M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +V g2 ×ρ g ×(T4-T3)×Cp g ……(6).

[0032] Where: M s1 It is the amount of sintered ore to be cooled that is transported to the ring cooler per unit time. s1 is the initial temperature of the sintered ore to be cooled. s2 Cp is the temperature of the sintered ore after cooling. s1 V is the specific heat capacity of sintered ore. g1 It is the cooling air volume entering the high temperature area of ​​the ring cooler per unit time. g is the density of cooling air. T2 is the temperature of the high-temperature hot air discharged from the high-temperature zone. T1 is the temperature of the cooling air drawn back to the high-temperature zone after waste heat utilization. Cp g is the specific heat capacity of the cooling air. g2 is the cooling air volume entering the medium temperature zone and low temperature zone of the ring cooler per unit time. T4 is the temperature of the mixed hot air discharged from the medium temperature zone and low temperature zone. T3 is the temperature of the cooling air drawn back to the medium temperature zone and low temperature zone after condensation.

[0033] ② Detect the amount of sintered ore to be cooled transported to the ring cooler per unit time M s1 , the initial temperature T of the sinter to be cooled s1 , the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization is T1, the temperature of the cooling air drawn back to the medium temperature zone and the low temperature zone after condensation is T3, and the temperature of the sintered ore after cooling is set to T s2 ≤120℃, the temperature of the high temperature hot air discharged from the high temperature zone T2≥350℃, the temperature of the mixed hot air discharged from the medium temperature zone and the low temperature zone T4 is 150~250℃, combined with the cooling air volume V entering the high temperature zone of the ring cooler per unit time calculated by the gas-solid heat transfer mathematical model g1 , calculate the cooling air volume V entering the medium temperature zone and low temperature zone of the ring cooler per unit time by formula (6) g2 .

[0034] Open the medium and low temperature zone solenoid valve set on the second natural wind duct, and adjust the second circulation fan set on the medium and low temperature zone air inlet duct so that the cooling air volume entering the medium and low temperature zones of the ring cooler per unit time is V g2 .

[0035] In the present invention, the method further comprises the step of calculating the feed amount of lump ore in the dryer, which specifically comprises the following sub-steps:

[0036] ① According to the overall air volume balance and heat balance of the ring cooler and the dryer, it can be obtained that the heat released by the sintered ore to be cooled during the cooling process is equal to the sum of the heat absorbed by the cooling air in the high temperature zone of the ring cooler, the heat absorbed by the lump ore to be dried during the drying process, the heat absorbed by the water in the lump ore, the heat absorbed by the evaporated water during the drying process, and the heat absorbed by the cooling air in the low temperature zone of the ring cooler during the cooling of the sintered ore and the drying of the lump ore. That is:

[0037] M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +M s2 ×(1-a1)×(T s4 -T s3 )×Cp s2 +M s2 ×a2×

[0038] (T s4 -T s3 )×Cp l +M s2 ×(a1-a2)×(100-T s3 )×Cp l +M s2 ×(a1-a2)×r 水 +V g2 ×ρ g ×(T5-T3)×Cp g ……(7).

[0039] Where: M s2 is the amount of lump ore to be dried delivered to the dryer per unit time. a1 is the initial moisture content of the lump ore to be dried. T s3 is the initial temperature of the lump ore to be dried. s4 Cp is the temperature of the lump ore after drying. s2 is the specific heat capacity of the lump ore. a2 is the moisture content of the lump ore after drying. Cp l is the specific heat capacity of water. 水is the heat of vaporization of water. T5 is the temperature of the dry air discharged from the dryer.

[0040] ② Detect the amount of sintered ore to be cooled transported to the ring cooler per unit time M s1 , the initial temperature T of the sinter to be cooled s1 , the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization T1, the initial moisture content a1 of the lump ore to be dried, the initial temperature T s3 , the temperature of the lump ore after drying T s4 , the temperature of the cooling air drawn back to the medium temperature zone and the low temperature zone after condensation is T3, and the temperature of the sintered ore after cooling is set to T s2 ≤120℃, the temperature of the high-temperature hot air discharged from the high-temperature zone T2≥350℃, the moisture content of the dried lump ore a2≤2%, the temperature of the dry air discharged from the dryer T5 is 70~90℃, combined with the calculated cooling air volume V entering the high-temperature zone of the ring cooler per unit time g1 , the cooling air volume V entering the medium temperature zone and low temperature zone of the ring cooler per unit time g2 , the amount of lump ore to be dried delivered to the dryer per unit time M is calculated by formula (7): s2 .

[0041] Adjust the lump ore feeding speed so that the amount of lump ore to be dried delivered to the dryer per unit time is M s2 .

[0042] In the present invention, the annular cooler and the dryer are both annular structures, wherein the dryer is arranged in the inner annular space of the annular cooler, and the dryer and the annular cooler are arranged coaxially.

[0043] In the present invention, in step 4), the medium and low temperature hot air are mixed and then transported to the air inlet of the dryer through a mixed hot air duct. The mixed hot air duct is provided with a third circulation fan.

[0044] Preferably, in step 3), the high-temperature hot air is used as waste heat by a high-temperature waste heat boiler. In step 4), the medium- and low-temperature hot air are mixed by a mixer. The dry air is condensed by a condenser.

[0045] In view of the problems of high construction cost, low drying efficiency and high energy consumption in the lump ore drying system in the prior art, as well as the problem that the waste heat of the exhaust gas in the low-temperature section of the ring cooler is difficult to utilize and it is difficult to achieve zero emissions, the present invention couples the drying of the lump ore with the utilization of the waste heat of the exhaust gas in the low-temperature section of the ring cooler, and proposes a near-zero emission method of coupling lump ore drying with a ring cooler. In the technical scheme of the present invention, on the one hand, the waste heat of the exhaust gas in the high temperature zone of the ring cooler is fully utilized, and the high-temperature hot air discharged from the high temperature zone is drawn back to the high temperature zone of the ring cooler after the waste heat is utilized, so as to circulate and cool the sintered ore in this area; on the other hand, the mixed hot air discharged from the medium and low temperature zone of the ring cooler is transported to the dryer to dry the lump ore, so as to fully utilize the waste heat of the exhaust gas in the medium and low temperature zone of the ring cooler. After the drying is completed, the dry air discharged from the dryer is drawn back to the medium and low temperature zone of the ring cooler for circulated cooling of the sintered ore, that is, through the air volume balance and heat balance between the sintered ore ring cooler and the lump ore dryer, the near-zero emission of the lump ore drying and the coupling of the ring cooler is finally achieved, which effectively solves the problem that the waste heat of the exhaust gas in the low temperature zone of the existing ring cooler is difficult to utilize and it is difficult to achieve zero emission, while reducing the investment cost of lump ore drying and improving the drying efficiency of lump ore.

[0046] In the present invention, the high-temperature hot air discharged from the high-temperature zone of the ring cooler is circulated to the high-temperature zone of the ring cooler through the high-temperature zone air inlet duct after waste heat utilization (for example, power generation through a high-temperature waste heat boiler). The high-temperature zone air inlet duct is connected to a first natural wind duct. Preferably, the first natural wind duct is also provided with a high-temperature zone solenoid valve. At the beginning of the system startup, the cooling air (i.e., initial cooling air) entering the high-temperature zone of the ring cooler is supplied by the first natural wind duct, and the high-temperature zone solenoid valve is in an open state at this time; when the required high-temperature zone cooling air supply is completed, the high-temperature zone solenoid valve is closed at this time. Correspondingly, the dry air discharged from the dryer is condensed (by the condenser) and circulated to the medium-temperature zone and low-temperature zone of the ring cooler through the medium- and low-temperature zone air inlet duct. The medium- and low-temperature zone air inlet duct is connected to a second natural wind duct. Preferably, the second natural wind duct is also provided with a medium- and low-temperature zone solenoid valve. At the beginning of system startup, the cooling air (i.e. initial cooling air) entering the medium temperature zone and low temperature zone of the ring cooler is supplied by the second natural wind duct, and the solenoid valves in the medium and low temperature zones are in the open state; when the required cooling air volume in the medium and low temperature zones is supplied, the solenoid valves in the medium and low temperature zones are closed.

[0047] It should be noted that the cooling air required for the high temperature zone and medium and low temperature zones of the ring cooler is only the initial cooling air volume supplied by the first natural air duct and the second natural air duct respectively, and in the subsequent system operation process, the cooling air volume in the high temperature zone is circulated and supplied by the high temperature hot air discharged from the high temperature zone after waste heat utilization, and the cooling air volume in the medium and low temperature zone is circulated and supplied by the dry air discharged from the dryer after condensation, thereby realizing near-zero emissions of the coupling of lump ore drying and ring cooler.

[0048] In order to further control or adjust the cooling air volume in the high temperature zone and the medium and low temperature zone of the ring cooler, the present invention is provided with a first circulation fan on the air inlet duct of the high temperature zone, and a second circulation fan on the air inlet duct of the medium and low temperature zone. Correspondingly, in order to control or adjust the drying air volume of the dryer, the present invention mixes the medium and low temperature hot air discharged from the medium temperature zone and the low temperature zone of the ring cooler through a (mixer) and transports them to the dryer through a mixed hot air duct, and a third circulation fan is provided on the mixed hot air duct. When the system needs to change the air volume, the solenoid valve of the high temperature zone and the solenoid valve of the medium and low temperature zone are opened, the pressure heads of the three circulation fans are adjusted, and after the air volume is changed as required, the two solenoid valves are closed to realize the circulation of the system's fresh air volume and near-zero emissions.

[0049] As a preferred embodiment, the ring cooler and the dryer described in the present invention are both ring structures, that is, Figure 3 As shown, the dryer used for lump ore drying can also adopt an annular structure similar to that of the ring cooler. Preferably, the present invention arranges the dryer in the inner ring space of the ring cooler, that is, the inner ring dryer is used to dry the lump ore, and the outer ring ring cooler is used to cool the sintered ore. The dryer and the ring cooler arranged in the inner and outer rings can better realize the mutual utilization of each other's flue gas waste heat. The setting of the inner ring dryer can also make full use of the inner space of the traditional ring cooler and reduce the construction cost of lump ore drying. In order to further ensure that the dryer fully and evenly utilizes the waste heat of the exhaust gas in the middle and low temperature zones of the ring cooler, the present invention arranges the dryer and the ring cooler coaxially. It should be noted that the ring cooler includes a cooling zone and a non-cooling zone, and the cooling zone is further divided into a high temperature zone, a medium temperature zone, and a low temperature zone. Figure 3 In the ring cooler, the unmarked part corresponds to the non-cooling area.

[0050] In order to further utilize the waste heat of the ring cooler and achieve near-zero emissions of the ring cooler, the near-zero emission method of coupling lump ore drying with a ring cooler described in the present invention also includes precise control of the cooling air volume in the high-temperature zone and the cooling air volume in the medium and low-temperature zones of the ring cooler, as well as the lump ore feed amount of the dryer, to ensure the circulation of the system air volume and near-zero emissions, while not affecting the cooling effect of the sintered ore and the drying effect of the lump ore.

[0051] First, under the condition of achieving near-zero emissions of the system, the present invention also improves the waste heat recovery rate of the high-temperature zone of the ring cooler as much as possible, and according to the waste heat utilization of the high-temperature hot air discharged from the high-temperature zone, for example, according to the thermal efficiency requirements of the high-temperature waste heat boiler, the average temperature of the high-temperature hot air discharged from the high-temperature zone should be ≥350°C (for example, the average temperature of the high-temperature hot air is between 350 and 450°C). Generally speaking, according to the influence of temperature and air volume on the waste heat utilization efficiency, under the premise of ensuring that the temperature of the high-temperature hot air is ≥350°C, the larger the air volume of the high-temperature hot air discharged from the high-temperature zone, the higher the waste heat utilization efficiency. Based on this, the present invention applies a gas-solid heat transfer mathematical model to the cooling process of the sintered ore to be cooled in the high-temperature zone of the ring cooler, and calculates the maximum value of the cooling air volume in the high-temperature zone of the ring cooler through the gas-solid heat transfer mathematical model, thereby ensuring that the waste heat recovery rate of the system, that is, the waste heat recovery rate of the high-temperature zone of the ring cooler is the highest.

[0052] In the present invention, the formula of the gas-solid heat transfer mathematical model is: Among them, dE x is the heat transfer capacity of the moving bed, ρ v is the gas-solid heat transfer coefficient, ΔT1 is the gas-solid temperature difference, dV is the moving bed volume, and H1 is the moving bed layer height. Therefore, in the high temperature area of ​​the ring cooler, according to the mathematical model of gas-solid heat transfer, we have:

[0053]

[0054] According to the above formula, by substituting the constraint condition that the temperature of the high-temperature hot air discharged from the high-temperature zone T2 ≥ 350°C, the maximum cooling air volume V in the high-temperature zone of the ring cooler can be calculated. g1 Open the high temperature zone solenoid valve on the first natural air duct, and adjust the first circulating fan on the high temperature zone air inlet duct so that the cooling air volume entering the high temperature zone of the ring cooler per unit time is V g1 After the cooling air volume in the high temperature zone is adjusted, close the solenoid valve in the high temperature zone.

[0055] After calculating the maximum cooling air volume in the high temperature zone, the present invention constructs the following formula based on the heat balance between the sintered ore and the cooling air in the ring cooler:

[0056] M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +V g2 ×ρ g ×(T4-T3)×Cp g ……(6);

[0057] Generally speaking, the temperature of the sintered ore after cooling T s2 Control it below 120℃ to ensure smooth production, protect equipment, meet subsequent blast furnace needs, and save energy and protect the environment. In addition, the present application transports the mixed hot air discharged from the low temperature zone of the ring cooler to the dryer for drying the lump ore. Therefore, in order to achieve the drying of the lump ore, ensure the drying efficiency, and prevent the lump ore from bursting due to excessive temperature, the present application preferably controls the temperature T4 of the mixed hot air discharged from the low temperature zone to 150-250℃. Based on this, in the above formula (6), substitute the temperature T2≥350℃ of the high temperature hot air discharged from the high temperature zone and the temperature T4 of the sintered ore after cooling. s2 ≤120℃, the temperature T4 of the mixed hot air discharged from the medium and low temperature zone is 150~250℃, combined with the cooling air volume V entering the high temperature zone of the ring cooler per unit time calculated by the gas-solid heat transfer mathematical model g1 , the cooling air volume V in the low temperature zone of the ring cooler can be calculated g2 Open the medium and low temperature zone solenoid valve set on the second natural wind duct, and adjust the second circulating fan set on the medium and low temperature zone air inlet duct so that the cooling air volume entering the medium and low temperature zones of the ring cooler per unit time is V g1 After the cooling air volume in the medium and low temperature zones is adjusted, close the solenoid valves in the medium and low temperature zones.

[0058] After calculating the maximum cooling air volume in the high temperature zone of the ring cooler and the corresponding cooling air volume in the medium and low temperature zones, the present invention constructs the following formula based on the overall air volume balance and heat balance of the ring cooler and the dryer:

[0059] M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +M s2 ×(1-a1)×(T s4 -T s3 )×Cp s2 +M s2 ×a2×

[0060] (T s4 -T s3 )×Cp l +M s2 ×(a1-a2)×(100-T s3 )×Cp l +M s2 ×(a1-a2)×r 水 +V g2 ×ρ g ×(T5-T3)×Cpg ……(7);

[0061] For lump ore, the moisture content is generally required to be below 2% before entering the blast furnace (i.e., the moisture content of the lump ore after drying is a2 ≤ 2%). Since the hot air from drying the lump ore circulates in the system, if condensation and water removal are not performed, the moisture content of the system will become higher and higher, and eventually it will be impossible to balance. Therefore, a condenser is added to the system. From the perspective of the working efficiency of the condenser, the inlet temperature of the condenser (i.e., the temperature T5 of the dry air discharged from the dryer) is required to be controlled at 70-90°C. Based on this, in the above formula (7), the temperature T2 ≥ 350°C of the high-temperature hot air discharged from the high-temperature zone and the temperature T5 of the sintered ore after cooling are substituted. s2 ≤120℃, moisture content of the dried lump ore a2≤2%, temperature of the dry air T5 discharged from the dryer is 70~90℃, combined with the cooling air volume V entering the high temperature zone of the ring cooler per unit time obtained by the above calculation g1 , the cooling air volume V entering the medium temperature zone and low temperature zone of the ring cooler per unit time g2 , the corresponding feed amount M of lump ore in the dryer can be calculated s2 Adjust the lump ore feeding speed so that the amount of lump ore to be dried delivered to the dryer per unit time is M s2 .

[0062] Therefore, the present invention couples the lump ore drying with the ring cooler, making full use of the waste heat of the waste gas in the medium and low temperature zones of the ring cooler. At the same time, according to the air volume matching and heat balance of the sintered ore ring cooler and the lump ore dryer, the near-zero emission of the entire system is achieved. In addition, the present invention also applies a gas-solid heat transfer mathematical model to the cooling process of the sintered ore in the high temperature zone of the ring cooler, and calculates the maximum cooling air volume in the high temperature zone of the ring cooler through the model, and calculates the corresponding cooling air volume in the medium and low temperature zones of the ring cooler and the feed amount of the lump ore in the dryer in combination with the system heat balance formula, thereby determining the optimal values ​​of various parameters of the near-zero emission of the lump ore drying and ring cooler coupling system, that is, the present invention uses the cooling air volume in the high temperature zone, medium and low temperature zone of the ring cooler and the feed amount of the lump ore as control means, so that the system has the highest waste heat recovery amount under the premise of satisfying the full cycle.

[0063] In this application, the "high temperature zone" and "high temperature section", "medium temperature zone" and "medium temperature section", "low temperature zone" and "low temperature section" of the ring cooler can be used interchangeably. "Medium and low temperature zone" and "medium temperature zone and low temperature zone" have the same meaning and can be used interchangeably.

[0064] Compared with the prior art, the present invention has the following beneficial technical effects:

[0065] 1. The present invention couples lump ore drying with a ring cooler, thereby fully utilizing the waste heat of exhaust gas in the low temperature zone of the ring cooler.

[0066] 2. The present invention utilizes the waste heat of the high-temperature hot air discharged from the high-temperature zone of the ring cooler and draws it back to the high-temperature zone of the ring cooler to circulate and cool the sintered ore in this area. At the same time, the mixed hot air discharged from the medium and low temperature zones of the ring cooler is transported to the dryer to dry the lump ore. After the drying is completed, the dry air discharged from the dryer is drawn back to the medium and low temperature zones of the ring cooler to circulate and cool the sintered ore. That is, through the air volume balance and heat balance between the sintered ore ring cooler and the lump ore dryer, the near-zero emission of the lump ore drying coupled with the ring cooler is achieved.

[0067] 3. The present invention applies a gas-solid heat transfer mathematical model to the cooling process of sintered ore in the high temperature zone of the ring cooler. The maximum cooling air volume in the high temperature zone of the ring cooler is calculated by the model, and the corresponding cooling air volume in the medium and low temperature zones of the ring cooler and the feed amount of lump ore in the dryer are calculated in combination with the system heat balance formula. That is, the present invention ensures the maximum waste heat recovery rate in the high temperature zone of the ring cooler while achieving near-zero emissions of the system.

[0068] 4. The present invention adopts an annular dryer with a structure similar to that of an annular cooler to dry the lump ore, and arranges the lump ore dryer in the inner ring position of the annular cooler, making full use of the inner ring space of the existing annular cooler, thereby reducing the investment cost of lump ore drying and improving the drying efficiency of the lump ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 The process flow chart of the near-zero emission method of lump ore drying coupled with an annular cooler of the present invention is as follows;

[0070] Figure 2 It is a schematic diagram of the system structure of the near-zero emission method for coupling lump ore drying and annular cooler in the present invention;

[0071] Figure 3 It is a schematic diagram of the arrangement of the ring cooler and the dryer in the present invention.

[0072] Reference numerals:

[0073] 1: Circular cooler; 101: High temperature zone; 102: Medium temperature zone; 103: Low temperature zone; 2: Dryer; 301: High temperature zone solenoid valve; 302: Medium and low temperature zone solenoid valve; 401: First circulation fan; 402: Second circulation fan; 403: Third circulation fan; 5: High temperature waste heat boiler; 6: Mixer; 7: Condenser;

[0074] L1: air inlet duct for high temperature zone; L2: first natural air duct; L3: air inlet duct for medium and low temperature zone; L4: second natural air duct; L5: mixed hot air duct. DETAILED DESCRIPTION

[0075] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0076] Example 1

[0077] like Figure 1 As shown, a near-zero emission method for lump ore drying coupled with a ring cooler comprises the following steps:

[0078] 1) The sintered ore to be cooled enters the ring cooler 1 and is cooled in the high temperature zone 101 , the medium temperature zone 102 and the low temperature zone 103 in sequence. The cooled sintered ore is discharged from the discharge port of the ring cooler 1 .

[0079] 2) The lump ore to be dried enters the dryer 2 for drying, and the dried lump ore is discharged from the discharge port of the dryer 2.

[0080] 3) The cooling air enters the high temperature zone 101 of the ring cooler 1 and performs heat exchange with the sintered ore to be cooled in the high temperature zone 101. After the heat exchange, the temperature of the cooling air increases to form high temperature hot air, which is discharged from the air outlet of the high temperature zone 101. The high temperature hot air is drawn back to the high temperature zone 101 after waste heat utilization to circulate and cool the sintered ore to be cooled.

[0081] 4) The cooling air entering the medium temperature zone 102 and the low temperature zone 103 of the ring cooler 1 continues to cool the sintered ore. After heat exchange with the sintered ore, the temperature of the cooling air increases to form medium and low temperature hot air, which are discharged from the air outlets of the medium temperature zone 102 and the low temperature zone 103 respectively. The medium and low temperature hot air are mixed and transported to the air inlet of the dryer 2. The mixed hot air dries the lump ore in the dryer 2. The dry air discharged from the dryer 2 is condensed and then drawn back to the medium temperature zone 102 and the low temperature zone 103 to circulate and cool the sintered ore, realizing the circulation of the system air volume and near-zero emissions.

[0082] Example 2

[0083] like Figure 1 As shown, a near-zero emission method for lump ore drying coupled with a ring cooler comprises the following steps:

[0084] 1) The sintered ore to be cooled enters the ring cooler 1 and is cooled in the high temperature zone 101 , the medium temperature zone 102 and the low temperature zone 103 in sequence. The cooled sintered ore is discharged from the discharge port of the ring cooler 1 .

[0085] 2) The lump ore to be dried enters the dryer 2 for drying, and the dried lump ore is discharged from the discharge port of the dryer 2.

[0086] 3) The cooling air enters the high temperature zone 101 of the ring cooler 1 and performs heat exchange with the sintered ore to be cooled in the high temperature zone 101. After the heat exchange, the temperature of the cooling air increases to form high temperature hot air, which is discharged from the air outlet of the high temperature zone 101. The high temperature hot air is recycled to the high temperature zone 101 after the waste heat is utilized by the high temperature waste heat boiler 5 to circulate and cool the sintered ore to be cooled.

[0087] 4) The cooling air entering the medium temperature zone 102 and the low temperature zone 103 of the ring cooler 1 continues to cool the sintered ore. After heat exchange with the sintered ore, the temperature of the cooling air increases to form medium and low temperature hot air, which are discharged from the air outlets of the medium temperature zone 102 and the low temperature zone 103 respectively. The medium and low temperature hot air are mixed by the mixer 6 and transported to the air inlet of the dryer 2. The mixed hot air dries the lump ore in the dryer 2. The dry air discharged from the dryer 2 is condensed by the condenser 7 and then drawn back to the medium temperature zone 102 and the low temperature zone 103 to circulate and cool the sintered ore, realizing the circulation of the system air volume and near-zero emissions.

[0088] Example 3

[0089] like Figure 2 As shown, Example 2 is repeated, except that in step 3), the high-temperature hot air is drawn back to the high-temperature zone 101 of the ring cooler 1 through the high-temperature zone air inlet duct L1 after waste heat utilization. The high-temperature zone air inlet duct L1 is connected to the first natural wind duct L2. The initial cooling air entering the high-temperature zone 101 of the ring cooler 1 is supplied by the first natural wind duct L2.

[0090] After the initial cooling air supply to the high temperature zone 101 is completed, the high temperature zone solenoid valve 301 provided on the first natural air duct L2 is closed.

[0091] Example 4

[0092] Example 3 is repeated, except that in step 4), the dry air is condensed and drawn back to the medium temperature zone 102 and the low temperature zone 103 of the ring cooler 1 through the medium and low temperature zone air inlet duct L3. The medium and low temperature zone air inlet duct L3 is connected to the second natural air duct L4. The initial cooling air entering the medium temperature zone 102 and the low temperature zone 103 of the ring cooler 1 is supplied by the second natural air duct L4.

[0093] After the initial cooling air supply to the medium temperature zone 102 and the low temperature zone 103 is completed, the medium and low temperature zone solenoid valve 302 provided on the second natural wind duct L4 is closed.

[0094] Example 5

[0095] The embodiment 4 is repeated, except that the high temperature zone air inlet duct L1 is provided with a first circulation fan 401. The first circulation fan 401 is located downstream of the connection position between the first natural wind duct L2 and the high temperature zone air inlet duct L1.

[0096] Example 6

[0097] Example 5 is repeated, except that the medium and low temperature zone air inlet duct L3 is provided with a second circulation fan 402. The second circulation fan 402 is located downstream of the connection position between the second natural wind duct L4 and the medium and low temperature zone air inlet duct L3.

[0098] Example 7

[0099] like Figure 3 As shown, the embodiment 6 is repeated, except that the annular cooler 1 and the dryer 2 are both annular structures. The dryer 2 is arranged in the inner annular space of the annular cooler 1, and the dryer 2 and the annular cooler 1 are arranged coaxially.

[0100] Example 8

[0101] Example 7 is repeated, except that in step 4), the medium and low temperature hot air are mixed and transported to the air inlet of the dryer 2 through the mixed hot air duct L5. The mixed hot air duct L5 is provided with a third circulation fan 403.

[0102] Example 9

[0103] Example 8 is repeated, except that the method further includes the step of calculating the cooling air volume of the high temperature zone of the ring cooler 1, which specifically includes the following sub-steps:

[0104] ① A mathematical model of gas-solid heat transfer is established for the cooling process of the sintered ore to be cooled in the high temperature zone 101 of the ring cooler 1, and the following is obtained:

[0105]

[0106] in:

[0107]

[0108] Nu=0.198ε 0.07 Re p 0.66 Pr 1 / 3 =20.847……(3).

[0109]

[0110] Where: E x It is the heat exchange of the sintered ore bed to be cooled in the high temperature zone of the ring cooler. v is the gas-solid heat transfer coefficient. ΔT is the gas-solid temperature difference between the cooling air and the sintered ore to be cooled in the high temperature zone of the ring cooler. V 高 T is the volume of the sintered ore bed to be cooled in the high temperature zone of the ring cooler. H is the height of the sintered ore bed to be cooled in the high temperature zone of the ring cooler. s1 is the initial temperature of the sintered ore to be cooled. T2 is the temperature of the high-temperature hot air discharged from the high-temperature zone. T1 is the temperature of the cooling air drawn back to the high-temperature zone after waste heat utilization. g1 Cp is the cooling air volume entering the high temperature zone of the ring cooler per unit time. g is the specific heat capacity of cooling air, Cp g=1400 J / (kg·℃). Nu is the Nusselt number of gas-solid heat transfer in the sinter bed. g is the thermal conductivity of cooling air, λ g =0.65W / (m·℃). ε is the porosity of the sintered ore bed, ε=0.40. p is the particle size of the sintered ore, d p =0.2m. p is the Reynolds number of sintered ore particles. Pr is the Prandtl number. ρ g is the density of cooling air, ρ g =1.29kg / m 3 .u g is the apparent velocity of cooling air, u g =2.5m / s. μThe dynamic viscosity of cooling air, μ=0.00055Pa·s.

[0111] ② Detect the initial temperature T of the sintered ore to be cooled s1 =700℃, the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization T1 =100℃, the volume of the sintered ore bed to be cooled in the high temperature zone of the ring cooler V 高 =135m 3 , the height of the sintered ore bed to be cooled in the high temperature zone of the ring cooler is H = 1m, and the temperature of the high temperature hot air discharged from the high temperature zone is set to T2 = 350°C. Formulas (1)-(5) are combined to calculate the cooling air volume V entering the high temperature zone of the ring cooler per unit time g1 =43.758m 3 / s=157529m 3 / h,V g1 It is the maximum cooling air volume in the high temperature zone of the ring cooler obtained under the condition of high temperature hot air temperature T2 = 350℃.

[0112] Open the high temperature zone solenoid valve 301 set on the first natural wind duct L2, and adjust the first circulation fan 401 set on the high temperature zone air inlet duct L1, so that the cooling air volume entering the high temperature zone of the ring cooler per unit time is V g1 , thereby ensuring the maximum waste heat recovery rate in the high temperature zone of the ring cooler.

[0113] Example 10

[0114] Example 9 is repeated, except that the method further includes the step of calculating the cooling air volume of the medium and low temperature zone of the ring cooler 1, which specifically includes the following sub-steps:

[0115] ① According to the heat balance between the sintered ore and the cooling air in the ring cooler 1, it can be obtained that the heat released by the sintered ore to be cooled during the cooling process is equal to the sum of the heat absorbed by the cooling air in the high temperature zone of the ring cooler and the heat absorbed by the cooling air in the medium temperature zone and the low temperature zone of the ring cooler. That is:

[0116] M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +V g2 ×ρ g ×(T4-T3)×Cp g ……(6).

[0117] Where: M s1 It is the amount of sintered ore to be cooled that is transported to the ring cooler per unit time. s1 is the initial temperature of the sintered ore to be cooled. s2 Cp is the temperature of the sintered ore after cooling. s1 is the specific heat capacity of sintered ore, Cp s1 =850J / (kg·℃) V g1 It is the cooling air volume entering the high temperature zone of the ring cooler per unit time. g is the density of cooling air, ρ g =1.29kg / m 3 T2 is the temperature of the high-temperature hot air discharged from the high-temperature zone. T1 is the temperature of the cooling air drawn back to the high-temperature zone after waste heat utilization. Cp g is the specific heat capacity of cooling air, Cp g =1400J / (kg·℃).V g2 is the cooling air volume entering the medium temperature zone and low temperature zone of the ring cooler per unit time. T4 is the temperature of the mixed hot air discharged from the medium temperature zone and low temperature zone. T3 is the temperature of the cooling air drawn back to the medium temperature zone and low temperature zone after condensation.

[0118] ② Detect the amount of sintered ore to be cooled transported to the ring cooler per unit time M s1 =430t / h, initial temperature of sintered ore to be cooled T s1 =700℃, the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization is T1=100℃, the temperature of the cooling air drawn back to the medium temperature zone and the low temperature zone after condensation is T3=50℃, and the temperature of the sintered ore after cooling is set to T s2 = 120 ° C, the temperature of the high temperature hot air discharged from the high temperature zone T2 = 350 ° C, the temperature of the mixed hot air discharged from the medium temperature zone and the low temperature zone T4 = 200 ° C, combined with the cooling air volume V entering the high temperature zone of the ring cooler per unit time calculated by the above-mentioned gas-solid heat transfer mathematical model g1 , calculate the cooling air volume V entering the medium temperature zone and low temperature zone of the ring cooler per unit time by formula (6) g2 =519991m 3 / h.

[0119] Open the medium and low temperature zone solenoid valve 302 set on the second natural wind duct L4, and adjust the second circulation fan 402 set on the medium and low temperature zone air inlet duct L2 so that the cooling air volume entering the medium and low temperature zones of the ring cooler per unit time is V g2 .

[0120] Embodiment 11

[0121] Example 10 is repeated, except that the method further includes the step of calculating the feed amount of lump ore in the dryer 2, specifically including the following sub-steps:

[0122] ① According to the overall air volume balance and heat balance of the ring cooler 1 and the dryer 2, it can be obtained that the heat released by the sintered ore to be cooled during the cooling process is equal to the sum of the heat absorbed by the cooling air in the high temperature zone of the ring cooler, the heat absorbed by the lump ore to be dried during the drying process, the heat absorbed by the moisture in the lump ore, the heat absorbed by the evaporated moisture during the drying process, and the heat absorbed by the cooling air in the low temperature zone of the ring cooler during the cooling of the sintered ore and the drying of the lump ore. That is:

[0123] M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +M s2 ×(1-a1)×(T s4 -T s3 )×Cp s2 +M s2 ×a2×

[0124] (T s4 -T s3 )×Cp l +M s2 ×(a1-a2)×(100-T s3 )×Cp l +M s2 ×(a1-a2)×r 水 +V g2 ×ρ g ×(T5-T3)×Cp g ……(7).

[0125] Where: M s2 is the amount of lump ore to be dried delivered to the dryer per unit time. a1 is the initial moisture content of the lump ore to be dried. T s3 is the initial temperature of the lump ore to be dried. s4 Cp is the temperature of the lump ore after drying. s2is the specific heat capacity of the lump ore, Cp s2 =600 J / (kg·℃). a2 is the moisture content of the lump ore after drying. Cp l is the specific heat capacity of water, Cp l =4200 J / (kg·℃). 水 is the heat of vaporization of water, r 水 =2500 kJ / kg. T5 is the temperature of the dry air discharged from the dryer.

[0126] ② Detect the amount of sintered ore to be cooled transported to the ring cooler per unit time M s1 =430t / h, initial temperature of sintered ore to be cooled T s1 =700℃, the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization is T1=100℃, the initial moisture content of the lump ore to be dried is a1=8%, the initial temperature of the lump ore to be dried is T s3 =25℃, the temperature of the lump after drying T s4 = 80℃, the temperature of the cooling air drawn back to the medium temperature zone and the low temperature zone after condensation is T3 = 50℃, and the temperature of the sintered ore after cooling is set to T s2 = 120°C, the temperature of the high-temperature hot air discharged from the high-temperature zone T2 = 350°C, the moisture content of the dried lump ore a2 = 2%, the temperature of the dry air discharged from the dryer T5 = 80°C, combined with the calculated cooling air volume V entering the high-temperature zone of the ring cooler per unit time g1 , the cooling air volume V entering the medium temperature zone and low temperature zone of the ring cooler per unit time g2 , the amount of lump ore to be dried delivered to the dryer per unit time M is calculated by formula (7): s2 =552739.573kg / h≈553t / h.

[0127] Adjust the lump ore feeding speed so that the amount of lump ore to be dried delivered to the dryer 2 per unit time is M s2 .

[0128] In summary, the present invention couples the lump ore drying with the ring cooler, making full use of the waste heat of the waste gas in the low temperature zone of the ring cooler. At the same time, according to the air volume matching and heat balance of the sintered ore ring cooler and the lump ore dryer, near-zero emissions of the entire system are achieved. In addition, the present invention also applies a gas-solid heat transfer mathematical model to the cooling process of the sintered ore in the high temperature zone of the ring cooler, and calculates the maximum cooling air volume in the high temperature zone of the ring cooler through the model, and calculates the corresponding cooling air volume in the low temperature zone of the ring cooler and the feed amount of the lump ore in the dryer in combination with the system heat balance formula. That is, the present invention ensures the maximum waste heat recovery rate in the high temperature zone of the ring cooler under the premise of achieving near-zero emissions of the system.

Claims

1. A near-zero emission method for lump ore drying coupled with a ring cooler, the method comprising the following steps: 1) The sintered ore to be cooled enters a ring cooler (1), passes through a high temperature zone (101), a medium temperature zone (102) and a low temperature zone (103) in sequence for cooling, and the cooled sintered ore is discharged from a discharge port of the ring cooler (1); 2) The lump ore to be dried enters the dryer (2) for drying, and the dried lump ore is discharged from the discharge port of the dryer (2); 3) The cooling air enters the high temperature zone (101) of the ring cooler (1) and performs heat exchange with the sintered ore to be cooled in the high temperature zone (101). After the heat exchange, the temperature of the cooling air increases to form high temperature hot air, which is discharged from the air outlet of the high temperature zone (101); the high temperature hot air is drawn back to the high temperature zone (101) after waste heat utilization to perform circulation cooling on the sintered ore to be cooled; 4) The cooling air entering the medium temperature zone (102) and the low temperature zone (103) of the ring cooler (1) continues to cool the sintered ore. After heat exchange with the sintered ore, the temperature of the cooling air increases to form medium and low temperature hot air, which are discharged from the air outlets of the medium temperature zone (102) and the low temperature zone (103) respectively; the medium and low temperature hot air are mixed and transported to the air inlet of the dryer (2), and the mixed hot air dries the lump ore in the dryer (2). The dry air discharged from the dryer (2) is condensed and then drawn back to the medium temperature zone (102) and the low temperature zone (103) to circulate and cool the sintered ore.

2. The near-zero emission method according to claim 1, characterized in that: In step 3), the high-temperature hot air is drawn back to the high-temperature zone (101) of the ring cooler (1) through the high-temperature zone air inlet duct (L1) after waste heat utilization; the high-temperature zone air inlet duct (L1) is connected to a first natural air duct (L2); wherein the initial cooling air entering the high-temperature zone (101) of the ring cooler (1) is supplied by the first natural air duct (L2); and / or In step 4), the dry air is condensed and then drawn back to the medium temperature zone (102) and the low temperature zone (103) of the ring cooler (1) through the medium and low temperature zone air inlet duct (L3); the medium and low temperature zone air inlet duct (L3) is connected to a second natural air duct (L4); wherein the initial cooling air entering the medium temperature zone (102) and the low temperature zone (103) of the ring cooler (1) is supplied by the second natural air duct (L4).

3. The near-zero emission method according to claim 2, characterized in that: After the initial cooling air supply to the high temperature zone (101) is completed, the high temperature zone solenoid valve (301) provided on the first natural air duct (L2) is closed; and / or After the initial cooling air supply to the medium temperature zone (102) and the low temperature zone (103) is completed, the medium and low temperature zone solenoid valve (302) provided on the second natural air duct (L4) is closed.

4. The near-zero emission method according to claim 3, characterized in that: A first circulation fan (401) is provided on the high-temperature zone air inlet duct (L1); the first circulation fan (401) is located downstream of a connection position between the first natural wind duct (L2) and the high-temperature zone air inlet duct (L1); and / or A second circulation fan (402) is provided on the medium and low temperature zone air inlet duct (L3); the second circulation fan (402) is located downstream of the connection position between the second natural wind duct (L4) and the medium and low temperature zone air inlet duct (L3).

5. The near-zero emission method according to any one of claims 1 to 4, characterized in that: In step 1), the temperature of the sintered ore after cooling is ≤120°C; In step 2), the moisture content of the dried lump ore is ≤2%.

6. The near-zero emission method according to claim 5, characterized in that: In step 3), the temperature of the high temperature hot air is ≥350°C; In step 4), the temperature of the mixed hot air obtained by mixing the medium and low temperature hot air is 150-250°C; the temperature of the drying air is 70-90°C.

7. The near-zero emission method according to any one of claims 4 to 6, characterized in that: The method further comprises the step of calculating the cooling air volume of the high temperature zone of the ring cooler (1), which specifically comprises the following sub-steps: ① A mathematical model of gas-solid heat transfer is established for the cooling process of the sintered ore to be cooled in the high temperature zone (101) of the ring cooler (1), and the following is obtained: in: Nu=0.198ε 0.07 Re p 0.66 Pr 1 / 3 ……(3); Where: E x h is the heat exchange of the sintered ore bed to be cooled in the high temperature zone of the ring cooler; v is the gas-solid heat transfer coefficient; ΔT is the gas-solid temperature difference between the cooling air and the sintered ore to be cooled in the high temperature zone of the ring cooler; V 高 is the volume of the sintered ore bed to be cooled in the high temperature zone of the ring cooler; H is the height of the sintered ore bed to be cooled in the high temperature zone of the ring cooler; T s1 is the initial temperature of the sintered ore to be cooled; T2 is the temperature of the high-temperature hot air discharged from the high-temperature zone; T1 is the temperature of the cooling air drawn back to the high-temperature zone after waste heat utilization; V g1 Cp is the cooling air volume entering the high temperature zone of the ring cooler per unit time; g is the specific heat capacity of cooling air; Nu is the Nusselt number of gas-solid heat transfer in the sintering bed; λ g is the thermal conductivity of the cooling air; ε is the porosity of the sintering bed; d p is the particle size of sintered ore; Re p is the Reynolds number of sintered ore particles; Pr is the Prandtl number; ρ g is the density of cooling air; u g is the apparent velocity of cooling air; μ is the dynamic viscosity of cooling air; ② Detect the initial temperature T of the sintered ore to be cooled s1 , the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization T1, the volume of the sintered ore bed to be cooled in the high temperature zone of the ring cooler V 高 , the height H of the sintered ore bed to be cooled in the high temperature zone of the ring cooler, and the temperature T2 of the high temperature hot air discharged from the high temperature zone is set to be ≥ 350°C. Formulas (1)-(5) are combined to calculate the cooling air volume V entering the high temperature zone of the ring cooler per unit time. g1 ; The high temperature zone electromagnetic valve (301) provided on the first natural air duct (L2) is opened, and the first circulation fan (401) provided on the high temperature zone air inlet duct (L1) is adjusted so that the cooling air volume entering the high temperature zone of the ring cooler per unit time is V g1 .

8. The near-zero emission method according to claim 7, characterized in that: The method further comprises the step of calculating the cooling air volume in the medium and low temperature zones of the ring cooler (1), which specifically comprises the following sub-steps: ① According to the heat balance between the sintered ore and the cooling air in the ring cooler (1), it can be obtained that the heat released by the sintered ore during the cooling process is equal to the sum of the heat absorbed by the cooling air in the high temperature zone of the ring cooler and the heat absorbed by the cooling air in the medium temperature zone and the low temperature zone of the ring cooler; That is: M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +V g2 ×ρ g ×(T4-T3)×Cp g ……(6); Where: M s1 T is the amount of sintered ore to be cooled that is transported to the ring cooler per unit time; s1 is the initial temperature of the sintered ore to be cooled; T s2 is the temperature of the sintered ore after cooling; Cp s1 is the specific heat capacity of sintered ore; V g1 is the cooling air volume entering the high temperature zone of the ring cooler per unit time; ρ g is the density of cooling air; T2 is the temperature of high-temperature hot air discharged from the high-temperature zone; T1 is the temperature of cooling air drawn back to the high-temperature zone after waste heat utilization; Cp g is the specific heat capacity of cooling air; V g2 is the cooling air volume entering the medium temperature zone and low temperature zone of the ring cooler per unit time; T4 is the temperature of the mixed hot air discharged from the medium temperature zone and low temperature zone; T3 is the temperature of the cooling air drawn back to the medium temperature zone and low temperature zone after condensation; ② Detect the amount of sintered ore to be cooled transported to the ring cooler per unit time M s1 , the initial temperature T of the sinter to be cooled s1 , the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization is T1, the temperature of the cooling air drawn back to the medium temperature zone and the low temperature zone after condensation is T3, and the temperature of the sintered ore after cooling is set to T s2 ≤120℃, the temperature of the high temperature hot air discharged from the high temperature zone T2≥350℃, the temperature of the mixed hot air discharged from the medium temperature zone and the low temperature zone T4 is 150~250℃, combined with the cooling air volume V entering the high temperature zone of the ring cooler per unit time calculated by the gas-solid heat transfer mathematical model g1 , calculate the cooling air volume V entering the medium temperature zone and low temperature zone of the ring cooler per unit time by formula (6) g2 ; The medium and low temperature zone electromagnetic valve (302) provided on the second natural air duct (L4) is opened, and the second circulating fan (402) provided on the medium and low temperature zone air inlet duct (L2) is adjusted so that the cooling air volume entering the medium and low temperature zones of the ring cooler per unit time is V g2 .

9. The near-zero emission method according to claim 8, characterized in that: The method further comprises the step of calculating the feed amount of lump ore in the dryer (2), which specifically comprises the following sub-steps: ① According to the overall air volume balance and heat balance of the ring cooler (1) and the dryer (2), it can be obtained that the heat released by the sintered ore to be cooled during the cooling process is equal to the sum of the heat absorbed by the cooling air in the high temperature zone of the ring cooler, the heat absorbed by the lump ore to be dried during the drying process, the heat absorbed by the water in the lump ore, the heat absorbed by the water evaporated during the drying process, and the heat absorbed by the cooling air in the low temperature zone of the ring cooler during the cooling of the sintered ore and the drying of the lump ore; That is: M s1 ×(T s1 -T s2 )×Cp s1 =V g1 ×ρ g ×(T2-T1)×Cp g +M s2 ×(1-a1)×(T s4 -T s3 )×Cp s2 +M s2 ×a2× (T s4 -T s3 )×Cp l +M s2 ×(a1-a2)×(100-T s3 )×Cp l +M s2 ×(a1-a2)×r 水 +V g2 ×ρ g ×(T5-T3)×Cp g ……(7); Where: M s2 is the amount of lump ore to be dried transported to the dryer per unit time; a1 is the initial moisture content of the lump ore to be dried; T s3 is the initial temperature of the lump ore to be dried; T s4 Cp is the temperature of the lump ore after drying; s2 is the specific heat capacity of the lump ore; a2 is the moisture content of the lump ore after drying; Cp l is the specific heat capacity of water; r 水 is the heat of vaporization of water; T5 is the temperature of the dry air discharged from the dryer; ② Detect the amount of sintered ore to be cooled transported to the ring cooler per unit time M s1 , the initial temperature T of the sinter to be cooled s1 , the temperature of the cooling air drawn back to the high temperature zone after waste heat utilization T1, the initial moisture content a1 of the lump ore to be dried, the initial temperature T s3 , the temperature of the lump ore after drying T s4 , the temperature of the cooling air drawn back to the medium temperature zone and the low temperature zone after condensation is T3, and the temperature of the sintered ore after cooling is set to T s2 ≤120℃, the temperature of the high-temperature hot air discharged from the high-temperature zone T2≥350℃, the moisture content of the dried lump ore a2≤2%, the temperature of the dry air discharged from the dryer T5 is 70~90℃, combined with the calculated cooling air volume V entering the high-temperature zone of the ring cooler per unit time g1 , the cooling air volume V entering the medium temperature zone and low temperature zone of the ring cooler per unit time g2 , the amount of lump ore to be dried delivered to the dryer per unit time M is calculated by formula (7): s2 ; Adjust the lump ore feeding speed so that the amount of lump ore to be dried delivered to the dryer (2) per unit time is M s2 .

10. The near-zero emission method according to any one of claims 1 to 9, characterized in that: The annular cooler (1) and the dryer (2) are both annular structures; wherein the dryer (2) is arranged in the inner annular space of the annular cooler (1), and the dryer (2) and the annular cooler (1) are arranged coaxially; and / or In step 4), the medium and low temperature hot air are mixed and transported to the air inlet of the dryer (2) through a mixed hot air duct (L5); the mixed hot air duct (L5) is provided with a third circulation fan (403); Preferably, in step 3), the high-temperature hot air is used as waste heat by a high-temperature waste heat boiler (5); in step 4), the medium- and low-temperature hot air are mixed by a mixer (6); and the dry air is condensed by a condenser (7).

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