CO and NOx dual-separation energy-saving process and equipment for autocatalytic sintering machine

Abstract

The invention provides a CO and NOx dual-separation energy-saving process and equipment for an autocatalytic sintering machine, and relates to the technical field of sintering flue gas emission reduction and industrial energy saving. According to the method, the distribution rule of CO and NOx in a flue gas system of the sintering machine is utilized, and the distribution rule of high-concentration CO in a specific area of a sintering zone of the sintering machine and the distribution rule of high-concentration NOx in a specific area of a cooling zone of the sintering machine are detected and analyzed through an intelligent means; cO and NOx generated in different areas of the sintering machine are subjected to targeted preliminary precise treatment by utilizing the self-catalytic oxidation function of the sintered ore and the rule and characteristic that CO and NOx in flue gas can spontaneously perform oxidation-reduction reaction under certain conditions, and the discharged sintering flue gas is subjected to heat exchange with the sintered ore to be cooled again through an external pre-cooler; therefore, CO and NOx in the discharged flue gas are deeply removed. And through the application of the closed three-blade heat exchanger, the overall efficiency of the sintering machine system is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of sintering fume emission reduction and industrial energy saving, and in particular to a self-catalytic sintering machine CO and NOx dual removal energy-saving process and equipment. Background Art

[0002] There are a lot of CO and NOx in the flue gas, which are difficult to control. The sintering machine is a key equipment for sintering operations in large-scale ferrous metallurgical sintering plants. It is mainly suitable for the sintering treatment of iron ore powder in large and medium-sized sintering plants. The sintering process is a complex multiphase reaction, which starts with a solid phase reaction. The product of the solid phase reaction is the basis for the formation of the bonding phase. In the sintering of magnetite concentrate, the calcium ferrite generated is first Fe3O4, which must be oxidized to Fe2O3. The oxygen content in the exhaust gas in the preheating zone is very low, and the sintering material basically maintains the original loose state of the mixture. In the combustion zone, carbon burns violently to deprive oxygen, the fuel basically disappears, the free CaO solid gangue disappears, and the iron oxide (Fe2O3 and CaFe2O4) still exists mainly in magnetite. Less calcium ferrite is generated, and part of the CaO solid solution enters the magnetite, part of it generates dicalcium silicate, part of it generates calcium ferrite, and the other part enters the glass phase. After the combustion zone, it enters the cooling zone, where the high temperature and oxidation conditions are met, which is called the high-temperature cooling zone. Calcium ferrite, the main bonding phase of high-basicity sinter, is formed in the high-temperature cooling zone (high-temperature oxidation zone) after the combustion zone. At this time, calcium ferrite increases significantly layer by layer and is generally needle-shaped. Magnetite and dicalcium silicate decrease significantly, while reoxidized hematite gradually develops. Calcium ferrite, magnetite and hematite widely form interwoven melt structures, and the sintered ore is basically consolidated. Since the flue gas from the sintering zone and preheating zone of the sintering machine mainly contains CO and NOx, if high-sulfur iron powder is used for batching production, the pollutant factors in the flue gas, including heavy metal pollutants and dioxin-containing substances, are relatively high. It is necessary to control the CO and NOx removal conditions at the source and in the process to reduce the impact of high-sulfur, high-CO, NOx, heavy metal pollutants and dioxin-containing flue gas on the production process. In addition, many circulating flue gases are recycled from the sintering zone reduction wind to the sintering zone, which aggravates the imbalance of the flue gas components in the sintering zone.

[0003] The general solutions for treating CO and NOx in sintering flue gas are to add metal oxide composite carriers, transition metals and precious metals, non-precious metals, transition metals and precious metals and other catalysts, but fail to fully utilize the catalytic oxidation and catalytic reduction effects of iron oxides (Fe2O3 and CaFe2O4) generated during the sintering process.

[0004] After the sintered ore is crushed or rolled, a ring cooler or a vertical heat exchanger is usually used. The efficiency of recovering the waste heat of the red-hot sintered ore is usually only about 30%, which makes it difficult to recover and utilize it efficiently. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides an energy-saving process and equipment for dual removal of CO and NOx in an autocatalytic sintering machine, which solves the technical problem that external catalysts are commonly used in the existing CO and NOx treatment, but the autocatalytic effect of iron oxides (Fe2O3 and CaFe2O4) in the sintered ore is not fully utilized.

[0006] (II) Technical solution To achieve the above objectives, the present invention is implemented through the following technical solutions: A self-catalytic sintering machine CO and NOx double removal energy-saving process, comprising the following steps: S1. The special iron ore powder, sintering return material, small pellets of miscellaneous materials, various fluxes and fine coke in the sintering operation are mixed and granulated to form sintering raw materials, which are then added to the sintering machine through the material distribution system. After the gas and combustion-supporting air are introduced, the fine coke is ignited by the igniter, and then the sintering reaction is completed by exhaust fan; the oxygen content at the inlet of the material entering the preheating zone and the supplementary air is controlled to be above 16%; S2. After dust removal, the high CO flue gas from the sintering belt of the sintering machine is circulated to the specific area of ​​high NOx flue gas at the tail end of the sintering belt. The high NOx flue gas undergoes an oxidation catalytic reaction with Fe2O3 and CaFe2O4 in the red-hot sintering product to oxidize CO into CO2. At the same time, under the autocatalytic action of Fe2O3 and CaFe2O4, CO and NO undergo a reduction reaction to generate CO2 and N2. The main reaction formula is: 2CO+O2=2CO2 2CO+2NO=2CO2+N2; S3. After being crushed by a crusher or a rolling mill, the sintered ore enters a precooler and comes into close contact with the exhaust gas from the sintering machine, so that CO and NOx in the exhaust gas are further removed under the autocatalytic effect of the sintered ore; the cooling medium of the precooler is all the exhaust gas from the sintering machine, and the ventilation capacity of the precooler is 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 ; S4. The pre-cooled sintered ore enters the closed three-leaf heat exchanger to complete heat exchange and cooling. The sintered ore with a size smaller than 5 mm is then returned to the silo through a screening device. The sintered ore with a size larger than 5 mm is the finished product and is transported to the blast furnace batching room to be used as the main raw material for blast furnace ironmaking. Here, the addition of a closed three-leaf heat exchanger has three functions: First, it compensates for the insufficient cooling capacity of the annular cooler caused by installing a pre-cooler on the annular cooler, which may affect the output of sintered ore. Second, the heat taken away by the external sintering flue gas when passing through the sintered ore is transferred to the cooling medium of the pre-cooler through GGH1 to avoid affecting the fluctuation of the pre-cooler's power generation efficiency. Third, it further improves the recovery rate of waste heat from sintered ore. S5. The sintering flue gas discharged from the precooler enters the multi-tube dust collector under the action of the exhaust fan, and is decarbonized and denitrified again by the CO+SCR reactor. After heat exchange by GGH, the flue gas is desulfurized and bag-type dust removed before being discharged from the chimney in compliance with the standards.

[0007] An autocatalytic sintering machine CO and NOx dual removal energy-saving process, comprising the following steps: S1. The special iron ore powder, sintering return material, small pellets of miscellaneous materials, various fluxes and fine coke in the sintering operation are mixed and granulated to form sintering raw materials, which are then added to the sintering machine through the material distribution system. After the gas and combustion-supporting air are introduced, the fine coke is ignited by the igniter, and then the sintering reaction is completed by exhaust fan; the oxygen content at the inlet of the material entering the preheating zone and the supplementary air is controlled to be above 16%; S2. After dust removal, the high CO flue gas from the sintering belt of the sintering machine is circulated to the specific area of ​​high NOx flue gas at the tail end of the sintering belt. The high NOx flue gas undergoes an oxidation catalytic reaction with Fe2O3 and CaFe2O4 in the red-hot sintering product to oxidize CO into CO2. At the same time, under the autocatalytic action of Fe2O3 and CaFe2O4, CO and NO undergo a reduction reaction to generate CO2 and N2. The main reaction formula is: 2CO+O2=2CO2 2CO+2NO=2CO2+N2; S3. After being crushed by a crusher or a rolling mill, the sintered ore enters a precooler installed on the ring cooler, where it comes into close contact with the exhaust gas from the sintering machine, so that CO and NOx in the exhaust gas are further removed under the autocatalytic effect of the sintered ore; the cooling medium of the precooler is all the exhaust gas from the sintering machine, and the ventilation capacity of the precooler is 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 ; S4. The sintered ore discharged from the ring cooler enters the closed three-leaf heat exchanger to complete heat exchange and cooling. The sintered ore with a size smaller than 5 mm is then returned to the silo through a screening device. The sintered ore with a size larger than 5 mm is the finished product and is transported to the blast furnace batching room to be used as the main raw material for blast furnace ironmaking. Here, the addition of a closed three-leaf heat exchanger has three functions: First, it compensates for the insufficient cooling capacity of the ring cooler caused by installing a pre-cooler on the ring cooler, which affects the output of sintered ore. Second, the heat taken away by the external sintering flue gas when passing through the sintered ore is transferred to the cooling medium of the ring cooler through GGH1 to avoid affecting the fluctuation of the power generation efficiency of the ring cooler. Third, it further improves the recovery rate of waste heat from sintered ore. S5. The sintering flue gas discharged through GGH1 first enters the multi-tube dust collector for dust removal under the action of the exhaust fan, and then undergoes decarbonization and denitrification again in the CO+SCR reactor. After heat exchange through GGH, the flue gas is further desulfurized and bag-type dust removed before being discharged through the chimney in compliance with the standards.

[0008] The present invention particularly points out that: 1. The cooling medium of the precooler is all the sintering machine flue gas, and its technical parameters such as ventilation capacity and ventilation area must match the total amount of exhaust flue gas. The present invention requires the ventilation capacity of the precooler to be 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 .

[0009] 2. The precooler needs to be equipped with a main exhaust fan, a smoke hood and a bellows.

[0010] 3. The closed three-leaf drum heat exchanger has a high-efficiency heat exchange function. During operation, it can fully utilize the gravity inertia of the sintered mineral material to automatically turn the material over, and slowly throw the sintered mineral material high up, which is very beneficial to the heat exchange between the sintered mineral material and the cooling medium.

[0011] 4. The original sintering machine waste heat recovery power generation system can be utilized.

[0012] Preferably, in S2 and S3, Fe2O3 and CaFe2O4 in the red-hot sintered product calcium ferrite have a catalytic oxidation effect on CO to generate CO2, and also have a catalytic reduction effect on the reaction of CO and NO to generate CO2 and N2.

[0013] Preferably, in S4, the closed three-leaf drum heat exchanger has the functions of automatic material turning and full sealing, and can efficiently complete gas-gas reaction and gas-solid-liquid heat exchange, and its heat exchange efficiency is not less than 80%.

[0014] Preferably, in S5, the CO concentration in the flue gas discharged from the precooler is less than 500 mg / m 3 , NOx concentration is reduced by more than 80% compared with the precooler inlet concentration.

[0015] Preferably, in S1, S2, S3, S4, and S5, a flue gas composition analysis system and a thermal energy intelligent control system are installed accordingly to collect and analyze the distribution patterns of CO and NOx in the sintering machine flue gas system, and to detect and analyze the distribution patterns of high-concentration CO in specific areas of the sintering belt of the sintering machine and high-concentration NOx in specific areas of the cooling belt of the sintering machine through intelligent means. Then, the CO and NOx generated in the high-CO area of ​​the sintering machine are precisely controlled by using autocatalytic means and the laws and characteristics of the mutual reaction between CO and NOx. An external pre-cooler is used to allow the exhausted sintering flue gas to exchange heat with the sintered ore to be cooled again, so that the CO and NOx in the exhausted flue gas are deeply removed. Then, through the application of a closed three-leaf heat exchanger, the overall efficiency of the sintering machine system is greatly improved.

[0016] To sum up, the specific method is: 1. After dust removal, the high-CO flue gas in a specific area of ​​the sintering belt of the sintering machine is circulated to a specific area of ​​high-NOx flue gas in the sintering section. Fe2O3 and CaFe2O4 in the red-hot sintered ore in this mineralization area are used to autocatalytically oxidize CO to CO2, and at the same time, CO and NO are reduced to generate CO2 and N2. Then, this part of the high-temperature flue gas is led back to the sintering belt of the sintering machine. The preliminary removal of CO and NOx in the sintering flue gas and the utilization of waste heat are achieved.

[0017] 2. Furthermore, all or part of the exhaust gas in the main flue gas pipeline of the sintering machine is introduced into the ring cooler, and the residual CO and NOx in the exhaust gas are deeply removed again by using the self-catalytic function of the high-temperature sintered ore. In addition, the exhaust gas is heated by the sintered ore which is still in a high-temperature state after being crushed, and the flue gas temperature can reach above 320℃.

[0018] 3. Furthermore, the sintered ore after the pre-cooler is still in a high temperature state. The sintered ore can directly enter the closed three-leaf heat exchanger, or it can enter the closed three-leaf heat exchanger after the ring cooling heat exchange, and utilize its self-turning and efficient heat exchange functions to efficiently recycle the waste heat of the sintered ore.

[0019] It is particularly noted that the sintered ore cooling system of the present invention needs to be upgraded, and an external precooler and a closed three-leaf heat exchanger can be installed, or a closed three-leaf heat exchanger can be installed on the ring cooler.

[0020] After two autocatalytic removals of CO and NOx in the sintering flue gas, the CO concentration is ≤500mg / m 3 , NOx removal rate ≥ 90%. The flue gas discharged from the precooler meets the emission standards after multi-tube dust removal, CO+SCR denitrification, GGH heat exchange, desulfurization, and bag dust removal. According to the design calculation, after passing through the CO+SCR reactor, CO and NOx can be further reduced to 200mg / m 3 and 30 mg / m 3the following.

[0021] The present invention does not require an external catalyst, but only uses the sintered ore in a high temperature state as a self-catalyst. After two removals, the CO in the exhaust gas can be reduced from 9000 mg / m 3 Above 200 mg / m 3 Below, the concentration of exhaust NOx is reduced to more than 90% of its generated amount.

[0022] In addition, by introducing the high-CO flue gas from the rear section of the sintering machine to the internal circulation of the rear section of the sintering belt of the sintering machine, exchanging heat with the high-temperature sintered ore in the pre-cooler, and automatically turning the material and efficiently exchanging heat in the closed three-blade drum heat exchanger, the waste heat recovery efficiency of this process system is increased by more than 80% compared with a single ring cooler, with a significant energy-saving effect.

[0023] (III) Beneficial effects The present invention provides an energy-saving process and equipment for dual removal of CO and NOx in an autocatalytic sintering machine. It has the following beneficial effects: 1. Circulate the sintering zone and high CO-containing flue gas to the rear section of the sintering zone of the sintering machine, and use the self-catalytic function of Fe2O3 and CaFe2O4 in the red-hot sintered ore to preliminarily remove CO and NOx from the circulating flue gas.

[0024] 2. Use the pre-cooler to further remove CO and NOx from the sintering flue gas. This can significantly reduce the CO and NOx in the sintering flue gas. This can reduce the CO in the sintering flue gas discharged from the pre-cooler to 500mg / m 3 Below, the exhaust NOx concentration is reduced by more than 80% compared with the original concentration.

[0025] 3. The closed three-leaf heat exchanger has a high-efficiency heat exchange function. During operation, it can fully utilize the self-gravity inertia of the sintered mineral material to automatically turn the material over, and slowly throw the sintered mineral material high up, which is very beneficial to the heat exchange between the sintered mineral material and the cooling medium; secondly, the original sintering machine waste heat recovery power generation system can be utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process flow of Embodiment 1 and Embodiment 2 of the present invention; Figure 2 This is a schematic diagram of the process flow of Example 3 of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Embodiment 1: like Figure 1 As shown, the embodiment of the present invention provides an autocatalytic sintering machine CO and NOx dual removal energy-saving process and equipment, including the following steps: S1. The special iron ore powder, sintering return material, small pellets of miscellaneous materials, various fluxes and fine coke in the sintering operation are mixed and granulated to make sintering raw materials, which are added to the sintering machine through the material distribution system. After the gas and combustion-supporting air are introduced, the fine coke is ignited by the igniter, and then the exhaust fan exhausts air to complete the sintering reaction; S2, the high CO flue gas of the sintering belt of the belt sintering machine with 24 bellows is dedusted and circulated to the tail section of the sintering belt and enters the high NOx flue gas specific area from the smoke hood 2. The high NOx flue gas undergoes catalytic oxidation reaction with Fe2O3 and CaFe2O4 in the sintering product in a red-hot state, oxidizing CO to CO2. At the same time, CO and NO undergo reduction reaction to generate CO2 and N2 under the autocatalytic action of Fe2O3 and CaFe2O4. The main reaction formula is: 2CO+O2=2CO2 2CO+2NO=2CO2+N2; Then, the flue gas returns to the fume hood 1 to enter the circulation; S3. After the sintered ore is sintered and crushed by a crusher or a rolling mill, it enters the precooler. The precooler is equipped with a main exhaust fan, a smoke hood and a bellows. The sintering flue gas discharged from the sintering machine enters the precooler flue gas inlet 1 from the sintering machine flue gas outlet 1 and comes into close contact with the sintered ore on the precooler, so that the CO and NOx in the flue gas are further removed under the self-catalytic effect of the sintered ore. The cooling medium of the precooler is all the sintering machine flue gas discharged from the sintering machine. Its technical parameters such as exhaust capacity and ventilation area must match the total amount of the exhaust flue gas. The process requires the ventilation capacity of the precooler to be 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 .

[0029] S4. After precooling, the sintered ore directly enters the closed three-leaf heat exchanger to complete heat exchange and cooling. Then, the sintered ore with a size smaller than 5 mm is returned to the silo through the screening device, and the sintered ore with a size larger than 5 mm is the finished product and transported to the blast furnace batching room to be used as the main raw material for blast furnace ironmaking.

[0030] Here, the closed three-blade drum heat exchanger has a high-efficiency heat exchange function. During operation, it can make full use of the self-gravity inertia of the sintered mineral material to automatically turn the material over, and slowly throw the sintered mineral material high up, which is very beneficial to the heat exchange between the sintered mineral material and the cooling medium.

[0031] S5. The sintering flue gas discharged through the precooler is discharged from the sintering flue gas outlet 2 through the exhaust flue gas inlet 2 under the action of the exhaust fan, and then decarbonized and denitrified again through the CO+SCR reactor. After the flue gas passes through the GGH heat exchange, it is desulfurized and dust-removed by bag filters before being discharged from the chimney in compliance with the standards.

[0032] This embodiment achieves the following beneficial effects: 1. Circulate the sintering zone and high CO-containing flue gas to the rear section of the sintering zone of the sintering machine, and use the self-catalytic function of Fe2O3 and CaFe2O4 in the red-hot sintered ore to preliminarily remove CO and NOx from the circulating flue gas.

[0033] 2. Use the pre-cooler to further remove CO and NOx from the sintering flue gas. This can significantly reduce the CO and NOx in the sintering flue gas, and reduce the CO in the sintering flue gas discharged from the pre-cooler to 500mg / m 3 Below, the NOx concentration is reduced by more than 80% compared with the original concentration.

[0034] 3. The use of closed three-leaf heat exchanger can ensure sufficient heat exchange of flue gas and increase the heat energy recovery rate to more than 80%.

[0035] Embodiment 2: like Figure 1 As shown, the embodiment of the present invention provides an autocatalytic sintering machine CO and NOx dual removal energy-saving process and equipment, including the following steps: S1. The special iron ore powder, sintering return material, small pellets of miscellaneous materials, various fluxes and fine coke in the sintering operation are mixed and granulated to make sintering raw materials, which are added to the sintering machine through the material distribution system. After the gas and combustion-supporting air are introduced, the fine coke is ignited by the igniter, and then the exhaust fan exhausts air to complete the sintering reaction; S2. After dust removal, the high CO flue gas from the belt sintering machine with several bellows is circulated to the tail section of the sintering belt and enters the high NOx flue gas specific area from the smoke hood 2. The high NOx flue gas undergoes an oxidation catalytic reaction with Fe2O3 and CaFe2O4 in the red-hot sintering product to oxidize CO into CO2. At the same time, under the autocatalytic action of Fe2O3 and CaFe2O4, CO and NO undergo a reduction reaction to generate CO2 and N2. The main reaction formula is: 2CO+O2=2CO2 2CO+2NO=2CO2+N2; Then, the flue gas returns to the fume hood 1 to enter the circulation; S3. After the sintered ore is sintered and crushed by the crusher, it enters the precooler. The precooler is equipped with a main exhaust fan, a smoke hood and a bellows. The sintering flue gas discharged from the sintering machine enters the precooler flue gas inlet 1 from the sintering machine flue gas outlet 1 and comes into close contact with the sintered ore on the precooler, so that the CO and NOx in the flue gas are further removed under the self-catalytic effect of the sintered ore; here, the cooling medium of the precooler is all the sintering machine flue gas discharged from the sintering machine, and its technical parameters such as exhaust capacity and ventilation area must match the total amount of the exhaust flue gas. The process requires the ventilation capacity of the precooler to be 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 .

[0036] S4. After precooling, the sintered ore directly enters the closed three-leaf heat exchanger to complete heat exchange and cooling. Then, the sintered ore with a size smaller than 5 mm is returned to the silo through the screening device, and the sintered ore with a size larger than 5 mm is the finished product and transported to the blast furnace batching room to be used as the main raw material for blast furnace ironmaking.

[0037] Here, the closed three-blade drum heat exchanger has a high-efficiency heat exchange function. During operation, it can make full use of the self-gravity inertia of the sintered mineral material to automatically turn the material over, and slowly throw the sintered mineral material high up, which is very beneficial to the heat exchange between the sintered mineral material and the cooling medium.

[0038] S5. The sintering flue gas discharged through the precooler is discharged from the sintering flue gas outlet 2 through the exhaust flue gas inlet 2 under the action of the exhaust fan, and then decarbonized and denitrified again through the CO+SCR reactor. After the flue gas passes through the GGH heat exchange, it is desulfurized and dust-removed by bag filters before being discharged from the chimney in compliance with the standards.

[0039] This embodiment achieves the following beneficial effects: 1. Circulate the sintering zone and high CO-containing flue gas to the rear section of the sintering zone of the sintering machine, and use the self-catalytic function of Fe2O3 and CaFe2O4 in the red-hot sintered ore to preliminarily remove CO and NOx from the circulating flue gas.

[0040] 2. Use the pre-cooler to further remove CO and NOx from the sintering flue gas. This can significantly reduce the CO and NOx in the sintering flue gas, and reduce the CO in the sintering flue gas discharged from the pre-cooler to 500mg / m 3 Below, the NOx concentration is reduced by more than 80% compared with the original concentration.

[0041] 3. The use of closed three-leaf heat exchanger can ensure sufficient heat exchange of flue gas and increase the heat energy recovery rate to more than 80%.

[0042] Embodiment three: like Figure 2As shown, the embodiment of the present invention provides an autocatalytic sintering machine CO and NOx dual removal energy-saving process and equipment, including the following steps: S1. The special iron ore powder, sintering return material, small pellets of miscellaneous materials, various fluxes and fine coke in the sintering operation are mixed and granulated to make sintering raw materials, which are added to the sintering machine through the material distribution system. After the gas and combustion-supporting air are introduced, the fine coke is ignited by the igniter, and then the exhaust fan exhausts air to complete the sintering reaction; S2, the high CO flue gas of the sintering belt of the belt sintering machine with 22 bellows is dedusted and circulated to the tail section of the sintering belt and enters the high NOx flue gas specific area from the smoke hood 2. The high NOx flue gas undergoes an oxidation catalytic reaction with Fe2O3 and CaFe2O4 in the sintering product in a red-hot state, oxidizing CO to CO2. At the same time, under the autocatalytic action of Fe2O3 and CaFe2O4, CO and NO undergo a reduction reaction to generate CO2 and N2. The main reaction formula is: 2CO+O2=2CO2 2CO+2NO=2CO2+N2; Then, the flue gas returns to the fume hood 1 to enter the circulation.

[0043] S3, after the sintered ore is calcined and crushed by the crusher, it enters the precooler set on the ring cooler from the smoke hood 3, and is in close contact with the exhaust gas from the sintering machine. The precooler on the ring cooler is equipped with a main exhaust fan, a smoke hood, and a bellows. CO and NOx in the flue gas are further removed under the autocatalytic effect of the sintered ore; the cooling medium of the precooler is all the exhaust gas from the sintering machine, and the ventilation capacity of the precooler is 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 ; S4. The sintered ore discharged from the ring cooler enters the closed three-leaf heat exchanger to complete heat exchange and cooling. The sintered ore with a diameter less than 5 mm is returned to the silo through the screening device, and the sintered ore with a diameter greater than 5 mm is the finished product and is transported to the blast furnace batching room to be used as the main raw material for blast furnace ironmaking.

[0044] Here, the addition of a closed three-leaf heat exchanger has three functions: First, it compensates for the insufficient cooling capacity of the ring cooler due to the installation of a precooler on the ring cooler, which may affect the output of sintered ore. Second, it transfers the heat taken away by the sintering flue gas when passing through the sintered ore to the cooling medium of the ring cooler through GGH1 to avoid affecting the fluctuation of the power generation efficiency of the ring cooler. Third, it further improves the recovery and utilization rate of the waste heat of sintered ore.

[0045] S5. The sintering flue gas discharged through the ring cooler enters the multi-tube dust collector for dust removal from the external sintering flue gas outlet 2 through the bellows 3 under the action of the exhaust fan. The sintering flue gas discharged through GGH1 enters the multi-tube dust collector for dust removal under the action of the exhaust fan, and is decarbonized and denitrified again through the CO+SCR reactor. After heat exchange through GGH2, the flue gas is desulfurized and dust-removed through bags before being discharged through the chimney in compliance with the standards.

[0046] S6. Under the action of the blower, the cooling medium passes through the closed three-blade drum heat exchanger in reverse to complete heat exchange. After heat exchange at GGH3, it enters the annular cooler from the smoke hood 4 to continue heat exchange, and enters the power generation system from the wind box 4.

[0047] This embodiment achieves the following beneficial effects: 1. Circulate the sintering zone and high CO-containing flue gas to the rear section of the sintering zone of the sintering machine, and use the self-catalytic function of Fe2O3 and CaFe2O4 in the red-hot sintered ore to preliminarily remove CO and NOx from the circulating flue gas.

[0048] 2. Use the ring cooler with smoke hood and wind box to further remove CO and NOx from the sintering flue gas. This can significantly reduce the CO and NOx in the sintering flue gas, and reduce the CO in the sintering flue gas discharged from the ring cooler to 500mg / m 3 Below, the NOx concentration is reduced by more than 80% compared with the original concentration.

[0049] 3. The use of closed three-leaf heat exchanger can ensure sufficient heat exchange of flue gas and increase the heat energy recovery rate to more than 80%.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An autocatalytic sintering machine CO and NOx dual removal energy-saving process, characterized by: The following steps are involved: S1. The special iron ore powder, sintering return material, small pellets of miscellaneous materials, various fluxes and fine coke in the sintering operation are mixed and granulated to form sintering raw materials, which are then added to the sintering machine through the material distribution system. After the gas and combustion-supporting air are introduced, the fine coke is ignited by the igniter, and then the sintering reaction is completed by exhaust fan; the oxygen content at the inlet of the material entering the preheating zone and the supplementary air is controlled to be above 16%; S2. After dust removal, the high CO flue gas from the sintering belt of the sintering machine is circulated to the specific area of ​​high NOx flue gas at the tail end of the sintering belt. The high NOx flue gas undergoes an oxidation catalytic reaction with Fe2O3 and CaFe2O4 in the red-hot sintering product to oxidize CO into CO2. At the same time, under the autocatalytic action of Fe2O3 and CaFe2O4, CO and NO undergo a reduction reaction to generate CO2 and N2. The main reaction formula is: 2CO+O2=2CO2 2CO+2NO=2CO2+N2; S3. After being crushed by a crusher or a rolling mill, the sintered ore enters a precooler and comes into close contact with the exhaust gas from the sintering machine, so that CO and NOx in the exhaust gas are further removed under the autocatalytic effect of the sintered ore; the cooling medium of the precooler is all the exhaust gas from the sintering machine, and the ventilation capacity of the precooler is 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 ; S4, the pre-cooled sintered ore enters the closed three-leaf heat exchanger to complete heat exchange and cooling, and then the sintered ore with a diameter less than 5 mm is returned to the silo through the screening device, and the sintered ore with a diameter greater than 5 mm is the finished product, which is transported to the blast furnace batching room and used as the main raw material for blast furnace ironmaking; S5. The sintering flue gas discharged from the precooler enters the multi-tube dust collector under the action of the exhaust fan, and is decarbonized and denitrified again by the CO+SCR reactor. After heat exchange by GGH, the flue gas is desulfurized and bag-type dust removed before being discharged from the chimney in compliance with the standards.

2. The energy-saving process for dual removal of CO and NOx from an autocatalytic sintering machine according to claim 1, characterized in that: In the S2 and S3, Fe2O3 and CaFe2O4 in the red-hot sintered product calcium ferrite have a catalytic oxidation effect on CO to generate CO2, and also have a catalytic reduction effect on the reaction of CO and NO to generate CO2 and N2.

3. The energy-saving process for dual removal of CO and NOx from an autocatalytic sintering machine according to claim 1, characterized in that: In S4, the closed three-leaf heat exchanger has the functions of automatic material turning and full sealing, and can efficiently complete gas-gas reaction and gas-solid heat exchange, and its heat exchange efficiency is not less than 80%.

4. The energy-saving process for dual removal of CO and NOx from an autocatalytic sintering machine according to claim 1, characterized in that: In S5, the CO concentration in the flue gas discharged from the precooler is less than 500 mg / m 3 , NOx concentration is reduced by more than 80% compared with the precooler inlet concentration.

5. The energy-saving process for dual removal of CO and NOx from an autocatalytic sintering machine according to claim 1, characterized in that: In the above-mentioned S1, S2, S3, S4 and S5, a flue gas composition analysis system and a thermal energy intelligent control system are installed to collect and analyze the distribution patterns of CO and NOx in the flue gas system of the sintering machine. The distribution patterns of high-concentration CO in specific areas of the sintering belt of the sintering machine and high-concentration NOx in specific areas of the cooling belt of the sintering machine are detected and analyzed by intelligent means. Then, the CO and NOx generated in the high-CO area of ​​the sintering machine are treated with targeted preliminary precision by using self-catalytic means and the laws and characteristics of the mutual reaction between CO and NOx. An external pre-cooler is installed to allow the exhausted sintering flue gas to exchange heat with the sintered ore to be cooled again, so that the CO and NOx in the exhausted flue gas are deeply removed. Then, the overall efficiency of the sintering machine system is greatly improved by using a closed three-leaf heat exchanger.

6. An autocatalytic sintering machine CO and NOx dual removal energy-saving process, characterized by: The following steps are involved: S1. The special iron ore powder, sintering return material, small pellets of miscellaneous materials, various fluxes and fine coke in the sintering operation are mixed and granulated to form sintering raw materials, which are then added to the sintering machine through the material distribution system. After the gas and combustion-supporting air are introduced, the fine coke is ignited by the igniter, and then the sintering reaction is completed by exhaust fan; the oxygen content at the inlet of the material entering the preheating zone and the supplementary air is controlled to be above 16%; S2. After dust removal, the high CO flue gas from the sintering belt of the sintering machine is circulated to the specific area of ​​high NOx flue gas at the tail end of the sintering belt. The high NOx flue gas undergoes an oxidation catalytic reaction with Fe2O3 and CaFe2O4 in the red-hot sintering product to oxidize CO into CO2. At the same time, under the autocatalytic action of Fe2O3 and CaFe2O4, CO and NO undergo a reduction reaction to generate CO2 and N2. The main reaction formula is: 2CO+O2=2CO2 2CO+2NO=2CO2+N2; S3. After being crushed by a crusher or a rolling mill, the sintered ore enters a precooler installed on the ring cooler, where it comes into close contact with the exhaust gas from the sintering machine, so that CO and NOx in the exhaust gas are further removed under the autocatalytic effect of the sintered ore; the cooling medium of the precooler is all the exhaust gas from the sintering machine, and the ventilation capacity of the precooler is 12500-15000m 3 / m 2 •h, the ventilation area of ​​​​ton of mine is 0.133-0.160m 2 ; S4, the sintered ore discharged from the ring cooler enters the closed three-leaf heat exchanger to complete heat exchange and cooling, and then the sintered ore with a diameter less than 5 mm is returned to the silo through the screening device, and the sintered ore with a diameter greater than 5 mm is the finished product, which is transported to the blast furnace batching room and used as the main raw material for blast furnace ironmaking; S5. The sintering flue gas discharged through GGH1 first enters the multi-tube dust collector for dust removal under the action of the exhaust fan, and then undergoes decarbonization and denitrification again in the CO+SCR reactor. After heat exchange through GGH, the flue gas is further desulfurized and bag-type dust removed before being discharged through the chimney in compliance with the standards.

7. The energy-saving process for dual removal of CO and NOx from an autocatalytic sintering machine according to claim 6, characterized in that: In the S2 and S3, Fe2O3 and CaFe2O4 in the red-hot sintered product calcium ferrite have a catalytic oxidation effect on CO to generate CO2, and also have a catalytic reduction effect on the reaction of CO and NO to generate CO2 and N2.

8. The energy-saving process for dual removal of CO and NOx from an autocatalytic sintering machine according to claim 6, characterized in that: In S4, the closed three-leaf heat exchanger has the functions of automatic material turning and full sealing, and can efficiently complete gas-gas reaction and gas-solid heat exchange, and its heat exchange efficiency is not less than 80%.

9. The energy-saving process for dual removal of CO and NOx from an autocatalytic sintering machine according to claim 6, characterized in that: In S5, the CO concentration in the flue gas discharged from the precooler is less than 500 mg / m 3 , NOx concentration is reduced by more than 80% compared with the precooler inlet concentration.

10. The energy-saving process for dual removal of CO and NOx in an autocatalytic sintering machine according to claim 6, characterized in that: In the above-mentioned S1, S2, S3, S4 and S5, a flue gas composition analysis system and a thermal energy intelligent control system are installed to collect and analyze the distribution patterns of CO and NOx in the flue gas system of the sintering machine. The distribution patterns of high-concentration CO in specific areas of the sintering belt of the sintering machine and high-concentration NOx in specific areas of the cooling belt of the sintering machine are detected and analyzed by intelligent means. Then, the CO and NOx generated in the high-CO area of ​​the sintering machine are treated with targeted preliminary precision by using self-catalytic means and the laws and characteristics of the mutual reaction between CO and NOx. An external pre-cooler is installed to allow the exhausted sintering flue gas to exchange heat with the sintered ore to be cooled again, so that the CO and NOx in the exhausted flue gas are deeply removed. Then, the overall efficiency of the sintering machine system is greatly improved by using a closed three-leaf heat exchanger.

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