Device system and method for coupling CO recovery and waste heat recovery in sintering flue gas

Abstract

The invention provides a device system and method for coupling CO recovery and waste heat recovery in sintering flue gas. The device system comprises a waste gas buffer tank, an SCR denitration reactor, a flue gas heating device and a catalytic oxidation reactor which are sequentially connected. A high-temperature flue gas outlet of the catalytic oxidation reactor is connected with the flue gas heating device; and a cooled flue gas outlet of the flue gas heating device is connected with the waste heat boiler. By adopting the device system and the method provided by the invention, ultralow emission of CO can be realized, the temperature of sintering flue gas can reach the reaction temperature of denitration reaction through internal heat transfer on the premise of not consuming extra fuel by utilizing reaction heat of CO catalytic oxidation, effective removal of nitrogen oxides in the flue gas is realized, and the denitration efficiency is improved. And the waste heat of the tail flue gas is further recycled, so that the device has the advantages of greenness and low carbon.

Description

Technical Field

[0001] The present invention belongs to the field of flue gas purification, and relates to a method for treating sintering flue gas, and in particular to a device system and method for coupling CO recovery and waste heat recovery in sintering flue gas. Background Art

[0002] Iron and steel smelting is a high-energy-consuming and highly polluting industry, and sintering is one of the most important production process links in steel enterprises. It not only consumes a lot of energy, but also produces a large amount of high-temperature harmful flue gas. Sintering flue gas is the main atmospheric pollutant emitted by steel enterprises, accounting for more than 50% of the total emissions of the entire steel enterprise. In recent years, through continuous technological innovation, the consumption of electricity, gas, solid fuels, etc. in the sintering process has continued to decline. In addition, the development of waste heat recovery technology for ring coolers has further reduced process energy consumption. Breakthrough development has also been achieved in the desulfurization, denitrification and dioxin treatment technologies of the head flue gas.

[0004] At present, most enterprises adopt measures to reduce CO by reducing carbon and increasing oxygen. According to the survey, the CO concentration in sintering flue gas has been around 5000mg / m 3 ~6000mg / m 3 For enterprises that are good at reducing CO concentration, the CO concentration in flue gas can reach 2000mg / m 3 .

[0005] CN 115253668A discloses a low-temperature CO catalytic oxidation treatment system and method, the treatment system includes a catalytic oxidation reactor, a regenerator and an elevator, the low-temperature flue gas after desulfurization, denitrification and dust removal enters the catalytic oxidation reactor, and the CO in the flue gas reacts with oxygen under the action of the catalyst to convert into carbon dioxide. The patent realizes the recycling of the catalyst by setting a regenerator, thereby improving the utilization rate of the catalyst. CN 110841481A discloses a sintering flue gas double heating SCR denitrification method and system, the method includes the following steps: after the sintering flue gas is desulfurized, it is mixed with the high-temperature flue gas for the first time; then it is heat exchanged with the flue gas after denitrification; the flue gas after heat exchange is mixed with the high-temperature flue gas for the second time, and then denitrification is carried out; the flue gas after denitrification is discharged after heat exchange. This patent solves the problem of blockage of the medium and low temperature SCR denitrification heating GGH. However, none of the above patents makes the CO concentration in the discharged flue gas lower than 20mg / m 3 .

[0006] Therefore, it is necessary to provide a method to further reduce the CO concentration in the sintering flue gas to achieve the purpose of green environmental protection. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a device system and method for coupling CO recovery and waste heat recovery in sintering flue gas. The device system and method provided by the present invention not only achieve ultra-low CO emissions, but also innovate in energy saving and environmental protection, and have the advantages of green and low carbon.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a device system for coupling CO recovery and waste heat recovery in sintering flue gas, the device system comprising a waste gas buffer tank, an SCR denitration reactor, a flue gas heating device and a catalytic oxidation reactor connected in sequence;

[0010] The high-temperature flue gas outlet of the catalytic oxidation reactor is connected to the flue gas heating device; and the cooling flue gas outlet of the flue gas heating device is connected to the waste heat boiler.

[0011] The present invention utilizes the temperature of the sintering flue gas itself and combines it with an SCR denitration reactor to achieve the removal of NOx in the sintering flue gas, and then utilizes a flue gas heating device (abbreviated as GGH) to heat the denitration flue gas to reach the operating temperature of the catalytic oxidation reactor, thereby achieving the removal of CO; the heat source of the flue gas heating device comes from the high-temperature flue gas removed by the catalytic oxidation reactor, and without consuming additional fuel, the temperature of the flue gas is transferred through internal heat to reach the reaction temperature of the CO removal catalyst.

[0012] The device system provided by the present invention makes full use of the reaction heat of CO in the sintering flue gas, replaces the hot blast furnace to provide the heat and temperature required for the catalytic oxidation of CO, and realizes energy saving; in addition, the present invention uses the reaction heat of CO to heat the sintering flue gas, and further recovers the waste heat of the tail flue gas, which can produce a large amount of steam as a by-product, improve efficiency, and the recovery efficiency of the entire system reaches more than 93%. Therefore, the device system provided by the present invention not only achieves ultra-low emissions of CO, but also innovates in energy saving, environmental protection (NOx), etc., and has the advantages of green and low carbon.

[0013] As a preferred technical solution of the present invention, the flue gas outlet of the waste heat boiler is connected to the chimney;

[0014] Preferably, the waste heat boiler is also provided with a boiler feed water inlet and a saturated steam outlet.

[0015] As a preferred technical solution of the present invention, an oxidation catalyst is arranged inside the catalytic oxidation reactor.

[0016] Preferably, the oxidation catalyst includes a solid solution substrate, and a platinum group metal supported on the solid solution substrate.

[0017] Preferably, in terms of weight percentage, the solid solution matrix comprises: 1-10wt% silicon dioxide, 0.5-5wt% tantalum oxide, and the balance zirconium oxide.

[0018] Exemplarily, the content of silicon dioxide in the solid solution matrix is ​​1 to 10 wt%, for example, it can be 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt% or 10 wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] The content of tantalum in the solid solution matrix is ​​0.5-5wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt% or 5wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the specific surface area of ​​the solid solution substrate is 200 to 300 m 2 / g, for example, it can be 200m 2 / g, 220m 2 / g, 240m 2 / g, 260m 2 / g, 280m 2 / g or 300m 2 / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the loading amount of the platinum group metal is 3 to 5 g / L, for example, 3 g / L, 3.4 g / L, 3.8 g / L, 4.2 g / L, 4.6 g / L or 5 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the specifications of the honeycomb ceramic carrier catalyst are a cross-section of 150×150 mm and a length of 70 to 80 mm, for example, 70 mm, 72 mm, 74 mm, 76 mm, 78 mm or 80 mm, but are not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the average pore size is 350 to 450 mesh, for example, 350 mesh, 370 mesh, 390 mesh, 410 mesh, 430 mesh or 450 mesh, but are not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0023] As a preferred technical solution of the present invention, a denitration catalyst is arranged inside the SCR denitration reactor.

[0024] Preferably, the denitration catalyst comprises a titanium dioxide carrier, and an active component supported on the titanium dioxide carrier.

[0025] Preferably, the active components include metallic cerium and metallic manganese.

[0026] Preferably, the molar ratio of the metal elements cerium, manganese and titanium in the denitration catalyst is 0.1-0.3:0.05-0.2:1.

[0027] In a second aspect, the present invention provides a method for coupling CO recovery and waste heat recovery in sintering flue gas, and the method is performed using the device system provided in the first aspect.

[0028] As a preferred technical solution of the present invention, the method comprises the following steps:

[0029] (1) Sintering flue gas and dilution air are mixed in a waste gas buffer tank, and then denitrified by an SCR denitrification reactor to obtain denitrified flue gas;

[0030] (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1), and then performing a CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas;

[0031] (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

[0032] It is worth noting that the role of the dilution air in step (1) of the present invention is to: reduce the explosion limit of the imported sintering flue gas;

[0033] In addition, the heat source for the temperature increase treatment in step (2) of the present invention comes from the high-temperature mixed flue gas obtained in step (2). The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for temperature reduction treatment, which is the temperature increase treatment of the denitrification flue gas in step (2). This method enables the temperature of the flue gas to reach the reaction temperature of the denitrification catalyst and catalytic oxidation treatment through internal heat transfer without consuming additional fuel, thereby saving energy.

[0034] As a preferred technical solution of the present invention, the concentration of CO in the sintering flue gas in step (1) is 6000-10000 mg / Nm 3 , for example, it can be 6000mg / Nm 3 、6500mg / Nm 3 、7000mg / Nm 3 、7500mg / Nm 3 、8000mg / Nm 3 、8500mg / Nm 3 、9000mg / Nm 3 、9500mg / Nm 3 or 10000mg / Nm3 , but not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the concentration of NOx in the sintering flue gas in step (1) is ≤300 mg / Nm 3 , for example, it can be 300mg / Nm 3 、280mg / Nm 3 、260mg / Nm 3 、240mg / Nm 3 、220mg / Nm 3 or 200mg / Nm 3 , but not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0036] Preferably, the temperature of the sintering flue gas in step (1) is 120-130°C, for example, 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] As a preferred technical solution of the present invention, the temperature of the denitrification treatment in step (1) is 120-130°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] In the present invention, the temperature of the denitration treatment is the same as the temperature of the sintering flue gas. The denitration catalyst provided by the present invention can effectively denitrate the sintering flue gas without increasing the temperature, further reducing the flue gas treatment cost.

[0039] As a preferred technical solution of the present invention, the terminal temperature of the temperature increase treatment in step (2) is 150-220°C, for example, it can be 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C or 220°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the temperature of the CO catalytic oxidation treatment in step (2) is 150-220°C, for example, it can be 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C or 220°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] Preferably, the reaction space velocity of the CO catalytic oxidation treatment in step (2) is 20000-40000h -1 , for example, it can be 20000h-1 、24000h -1 、28000h -1 、32000h -1 、36000h -1 or 40000h -1 , but not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0042] As a preferred technical solution of the present invention, the method for coupling CO recovery and waste heat recovery in sintering flue gas provided in the second aspect of the present invention comprises the following steps:

[0043] (1) Mix the waste gas at 120-130°C and CO concentration of 6000-10000 mg / Nm 3 The sintering flue gas and the dilution air are then denitrated by the SCR denitration reactor to obtain denitrated flue gas; the denitration treatment temperature is 120-130°C;

[0044] (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1) to 150-220° C., and then performing CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas; the CO catalytic oxidation treatment temperature is 150-220° C., and the reaction space velocity is 20000-40000 h -1 ;

[0045] (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

[0046] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The method for coupling CO recovery and waste heat recovery in sintering flue gas by using the device system provided by the present invention makes the CO removal efficiency in sintering flue gas ≥ 99.9%, and CO emission reaches the standard without pressure;

[0049] (2) The method for coupling CO recovery and waste heat recovery from sintering flue gas using the device system provided by the present invention has a high waste heat recovery efficiency. In addition to using the reaction heat of CO catalytic oxidation to heat the denitrification flue gas, the waste heat of the tail flue gas is further recovered, which can produce a large amount of steam by-product and improve efficiency. The recovery efficiency of the entire system is more than 93%;

[0050] (3) The method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided by the present invention has high waste heat recovery efficiency. The reaction heat of CO catalytic oxidation can be used to achieve the temperature of the sintering flue gas reaching the reaction temperature of CO catalytic oxidation treatment through internal heat transfer without consuming additional fuel, thereby achieving effective removal of CO in the flue gas;

[0051] (4) The device system provided by the present invention utilizes the waste heat of the tail flue gas to produce steam, thereby reducing the temperature of the exhaust gas;

[0052] (5) The device system provided by the present invention not only achieves ultra-low CO emissions and no wastewater discharge, but also innovates in energy saving and environmental protection, and has the advantages of being green and low-carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic diagram of the structure of a device system for coupling CO recovery and waste heat recovery in sintering flue gas provided by the present invention;

[0054] Among them, 1 is an exhaust gas buffer tank, 2 is an SCR denitrification reactor, 3 is a flue gas heating device, 4 is a catalytic oxidation reactor, 5 is a waste heat boiler, and 6 is a chimney. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0056] In a specific embodiment, the present invention provides a device system for coupling CO recovery and waste heat recovery in sintering flue gas, such as Figure 1 As shown, the device system includes an exhaust gas buffer tank 1, an SCR denitration reactor 2, a flue gas heating device 3 and a catalytic oxidation reactor 4 which are sequentially connected;

[0057] The high-temperature flue gas outlet of the catalytic oxidation reactor 4 is connected to the flue gas heating device 3 ; and the cooling flue gas outlet of the flue gas heating device 3 is connected to the waste heat boiler 5 .

[0058] The flue gas outlet of the waste heat boiler 5 is connected to the chimney 6; the waste heat boiler 5 is also provided with a boiler feed water inlet and a saturated steam outlet.

[0059] An oxidation catalyst is disposed inside the catalytic oxidation reactor 4; the oxidation catalyst comprises a solid solution substrate and a platinum group metal supported on the solid solution substrate;

[0060] In terms of weight percentage, the solid solution substrate comprises: 1-10wt% silicon dioxide, 0.5-5wt% tantalum oxide, and the balance zirconium oxide;

[0061] The specific surface area of ​​the solid solution substrate is 200 to 300 m 2 / g; the loading amount of the platinum group metal is 3 to 5 g / L;

[0062] The specifications of the oxidation catalyst are: a cross section of 150×150 mm, a length of 70 to 80 mm, and an average pore size of 350 to 450 meshes.

[0063] A denitration catalyst is arranged inside the SCR denitration reactor 2; the denitration catalyst comprises a titanium dioxide carrier and an active component loaded on the titanium dioxide carrier; the active component comprises metallic cerium and metallic manganese; the molar ratio of the metallic elements cerium, manganese and titanium in the denitration catalyst is 0.1-0.3:0.05-0.2:1.

[0064] In another specific embodiment, the present invention provides a method of Figure 1 The device system shown in the figure performs a method for coupling CO recovery and waste heat recovery in sintering flue gas, and the method comprises the following steps:

[0065] (1) Mix the waste gas at 120-130°C and CO concentration of 6000-10000 mg / Nm 3 The sintering flue gas and the dilution air are then denitrated by the SCR denitration reactor to obtain denitrated flue gas; the denitration treatment temperature is 120-130°C;

[0066] (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1) to 150-220° C., and then performing CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas; the CO catalytic oxidation treatment temperature is 150-220° C., and the reaction space velocity is 20000-40000 h -1 ;

[0067] (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

[0068] Example 1

[0069] This embodiment provides a device system for coupling CO recovery and waste heat recovery in sintering flue gas, such as Figure 1 As shown, the device system includes an exhaust gas buffer tank 1, an SCR denitration reactor 2, a flue gas heating device 3 and a catalytic oxidation reactor 4 which are sequentially connected;

[0070] The high-temperature flue gas outlet of the catalytic oxidation reactor 4 is connected to the flue gas heating device 3 ; and the cooling flue gas outlet of the flue gas heating device 3 is connected to the waste heat boiler 5 .

[0071] The flue gas outlet of the waste heat boiler 5 is connected to the chimney 6; the waste heat boiler 5 is also provided with a boiler feed water inlet and a saturated steam outlet.

[0072] An oxidation catalyst is disposed inside the catalytic oxidation reactor 4; the oxidation catalyst comprises a solid solution substrate and a platinum group metal supported on the solid solution substrate;

[0073] In terms of weight percentage, the solid solution matrix comprises: 5wt% silicon dioxide, 2.5wt% tantalum oxide, and the balance zirconium oxide;

[0074] The specific surface area of ​​the solid solution substrate is 250 m 2 / g; the loading amount of the platinum group metal is 4g / L;

[0075] The specifications of the oxidation catalyst are: a cross section of 150×150 mm, a length of 75 mm, and an average pore size of 400 meshes.

[0076] A denitration catalyst is arranged inside the SCR denitration reactor 2; the denitration catalyst comprises a titanium dioxide carrier and an active component loaded on the titanium dioxide carrier; the active component comprises metallic cerium and metallic manganese; the molar ratio of the metallic elements cerium, manganese and titanium in the denitration catalyst is 0.2:0.1:1.

[0077] Example 2

[0078] This embodiment provides a device system for coupling CO recovery and waste heat recovery in sintering flue gas, such as Figure 1 As shown, the device system includes an exhaust gas buffer tank 1, an SCR denitration reactor 2, a flue gas heating device 3 and a catalytic oxidation reactor 4 which are sequentially connected;

[0079] The high-temperature flue gas outlet of the catalytic oxidation reactor 4 is connected to the flue gas heating device 3 ; and the cooling flue gas outlet of the flue gas heating device 3 is connected to the waste heat boiler 5 .

[0080] The flue gas outlet of the waste heat boiler 5 is connected to the chimney 6; the waste heat boiler 5 is also provided with a boiler feed water inlet and a saturated steam outlet.

[0081] An oxidation catalyst is disposed inside the catalytic oxidation reactor 4; the oxidation catalyst comprises a solid solution substrate and a platinum group metal supported on the solid solution substrate;

[0082] In terms of weight percentage, the solid solution substrate comprises: 1wt% silicon dioxide, 5wt% tantalum oxide, and the balance zirconium oxide;

[0083] The specific surface area of ​​the solid solution substrate is 200 m 2 / g; the loading amount of the platinum group metal is 5g / L;

[0084] The specifications of the oxidation catalyst are: a cross section of 150×150 mm, a length of 70 mm, and an average pore size of 350 meshes.

[0085] A denitration catalyst is arranged inside the SCR denitration reactor 2; the denitration catalyst comprises a titanium dioxide carrier and an active component loaded on the titanium dioxide carrier; the active component comprises metallic cerium and metallic manganese; the molar ratio of the metallic elements cerium, manganese and titanium in the denitration catalyst is 0.1:0.2:1.

[0086] Example 3

[0087] This embodiment provides a device system for coupling CO recovery and waste heat recovery in sintering flue gas, such as Figure 1 As shown, the device system includes an exhaust gas buffer tank 1, an SCR denitration reactor 2, a flue gas heating device 3 and a catalytic oxidation reactor 4 which are sequentially connected;

[0088] The high-temperature flue gas outlet of the catalytic oxidation reactor 4 is connected to the flue gas heating device 3 ; and the cooling flue gas outlet of the flue gas heating device 3 is connected to the waste heat boiler 5 .

[0089] The flue gas outlet of the waste heat boiler 5 is connected to the chimney 6; the waste heat boiler 5 is also provided with a boiler feed water inlet and a saturated steam outlet.

[0090] An oxidation catalyst is disposed inside the catalytic oxidation reactor 4; the oxidation catalyst comprises a solid solution substrate and a platinum group metal supported on the solid solution substrate;

[0091] In terms of weight percentage, the solid solution matrix comprises: 10wt% silicon dioxide, 0.5wt% tantalum oxide, and the balance zirconium oxide;

[0092] The specific surface area of ​​the solid solution substrate is 300 m 2 / g; the loading amount of the platinum group metal is 3g / L;

[0093] The specifications of the oxidation catalyst are: a cross section of 150×150 mm, a length of 80 mm, and an average pore size of 450 meshes.

[0094] A denitration catalyst is arranged inside the SCR denitration reactor 2; the denitration catalyst comprises a titanium dioxide carrier and an active component loaded on the titanium dioxide carrier; the active component comprises metallic cerium and metallic manganese; the molar ratio of the metallic elements cerium, manganese and titanium in the denitration catalyst is 0.3:0.05:1.

[0095] Comparative Example 1

[0096] This comparative example provides a device system for coupling CO recovery and waste heat recovery in sintering flue gas. The difference between the device system and Example 1 is only that:

[0097] In this comparative example, the high-temperature flue gas outlet of the catalytic oxidation reactor 4 is adjusted to be connected to the waste heat boiler 5 ; and a heating device is provided at the inlet of the flue gas heating device 3 .

[0098] Comparative Example 2

[0099] This comparative example provides a device system for coupling CO recovery and waste heat recovery in sintering flue gas. The difference between the device system and Example 1 is only that:

[0100] In this comparative example, the cooling flue gas outlet of the flue gas heating device 3 is connected to the chimney 6 .

[0101] Application Example 1

[0102] This application example provides a method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided in Example 1, the method comprising the following steps:

[0103] (1) Mix 125℃ and 8000mg / Nm2 of CO in the exhaust gas buffer tank. 3 The sintering flue gas and the dilution air are then denitrated by the SCR denitration reactor to obtain denitrated flue gas; the denitration treatment temperature is 124°C;

[0104] (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1) to 180° C., and then performing a CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas; the CO catalytic oxidation treatment temperature is 180° C., and the reaction space velocity is 30000 h -1 ;

[0105] (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

[0106] Application Example 2

[0107] This application example provides a method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided in Example 1, the method comprising the following steps:

[0108] (1) Mix the waste gas at 120°C and CO concentration of 6000 mg / Nm in the waste gas buffer tank. 3 The sintering flue gas and the dilution air are then denitrated by the SCR denitration reactor to obtain denitrated flue gas; the denitration treatment temperature is 120°C;

[0109] (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1) to 150° C., and then performing a CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas; the CO catalytic oxidation treatment temperature is 150° C., and the reaction space velocity is 20000 h -1 ;

[0110] (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

[0111] Application Example 3

[0112] This application example provides a method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided in Example 1, the method comprising the following steps:

[0113] (1) Mix the waste gas at 130°C and the CO concentration at 10000 mg / Nm 3 The sintering flue gas and the dilution air are then denitrated by the SCR denitration reactor to obtain denitrated flue gas; the denitration treatment temperature is 130°C;

[0114] (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1) to 220° C., and then performing a CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas; the CO catalytic oxidation treatment temperature is 220° C., and the reaction space velocity is 40000 h -1 ;

[0115] (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

[0116] Application Example 4

[0117] This application example provides a method for recovering CO and waste heat from coupled sintering flue gas using the device system provided in Example 2, and the method is the same as that in Application Example 1.

[0118] Application Example 5

[0119] This application example provides a method for recovering CO and waste heat from coupled sintering flue gas using the device system provided in Example 2, and the method is the same as that in Application Example 1.

[0120] Application Example 6

[0121] This application example provides a method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided in Example 1. The method differs from Application Example 1 only in that:

[0122] In this application example, the terminal temperature of the temperature increase treatment in step (2) is adjusted to 130°C, that is, the temperature of the CO catalytic oxidation treatment in step (2) is 130°C.

[0123] Application Example 7

[0124] This application example provides a method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided in Example 1. The method differs from Application Example 1 only in that:

[0125] In this application example, the terminal temperature of the temperature increase treatment in step (2) is adjusted to 260°C, that is, the temperature of the CO catalytic oxidation treatment in step (2) is 260°C.

[0126] Application Example 8

[0127] This application example provides a method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided in Example 1. The method differs from Application Example 1 only in that:

[0128] In this application example, the temperature of the sintering flue gas in step (1) is adjusted to 80°C, that is, the temperature of the denitration treatment in step (1) is 80°C.

[0129] Comparative application example 1

[0130] This comparative application example provides a method for recovering CO and waste heat from coupled sintering flue gas using the device system provided in Comparative Example 1, and the method is the same as that in Application Example 1.

[0131] Comparative Application Example 2

[0132] This comparative application example provides a method for coupling CO recovery and waste heat recovery in sintering flue gas using the device system provided in Comparative Example 2, and the method is the same as that in Application Example 1.

[0133] Performance testing:

[0134] The exhaust gas provided in the above embodiments and comparative examples was tested for CO concentration and nitrogen oxides, and the results are shown in Table 1.

[0135] Table 1

[0136] NOx removal efficiency / % CO removal efficiency / % Application Example 1 92.99 99.996 Application Example 2 91.8 99.97 Application Example 3 94.4 99.98 Application Example 4 92.95 99.96 Application Example 5 91.99 99.96 Application Example 6 92.49 98.71 Application Example 7 92.99 99.92 Application Example 8 75 99.995 Comparative application example 1 90 99.994 Comparative Application Example 2 90 99.96

[0137] According to Table 1, we can know the following points:

[0138] (1) Comprehensive analysis of application examples 1-5 shows that the device system and method provided by the present invention can effectively remove CO and NOx in sintering flue gas, wherein the CO removal rate is ≥ 99.9%, and no waste gas and wastewater are discharged during the reaction process, which has the advantages of being green and low-carbon;

[0139] (2) Comprehensive analysis of Application Example 1 and Application Examples 6-7 shows that the change in temperature during the CO catalytic oxidation process will affect the CO removal effect. When the treatment temperature is too low (such as Example 6) or too high (such as Example 7), the removal effect will be reduced;

[0140] (3) Comprehensive analysis of Application Example 1 and Application Example 8 shows that when the temperature of denitrification treatment is too low, the denitrification effect of flue gas will be seriously affected;

[0141] (4) Comprehensive analysis of Application Example 1 and Comparative Application Examples 1-2 shows that adjusting the flow direction of flue gas in the device system will affect the utilization of heat in the system;

[0142] When the high-temperature flue gas outlet of the catalytic oxidation reactor 4 is adjusted to be connected to the waste heat boiler 5 (such as in Comparative Example 1), the heat in the high-temperature flue gas obtained by the catalytic oxidation reactor cannot be recycled, and an external heat source is required to provide heat for the catalytic reaction, thereby increasing the operating cost;

[0143] When the cooling flue gas outlet of the flue gas heating device 3 is connected to the chimney 6 (such as comparative example 2), the high-temperature flue gas still retains a large amount of heat after being cooled by the preheater. Direct discharge will also cause a large amount of heat loss, which is not in line with the concept of energy conservation and emission reduction.

[0144] In summary, the device system and method provided by the present invention can not only achieve ultra-low emissions of CO, but also utilize the reaction heat of CO catalytic oxidation to achieve the temperature of the sintering flue gas through internal heat transfer without consuming additional fuel, thereby achieving effective removal of nitrogen oxides in the flue gas and further recycling the waste heat of the tail flue gas, which has the advantages of being green and low-carbon.

[0145] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A device system for coupling CO recovery and waste heat recovery in sintering flue gas, characterized in that: The device system comprises an exhaust gas buffer tank, an SCR denitration reactor, a flue gas heating device and a catalytic oxidation reactor which are sequentially connected; The high-temperature flue gas outlet of the catalytic oxidation reactor is connected to the flue gas heating device; and the cooling flue gas outlet of the flue gas heating device is connected to the waste heat boiler.

2. The device system according to claim 1, characterized in that: The flue gas outlet of the waste heat boiler is connected to the chimney; Preferably, the waste heat boiler is also provided with a boiler feed water inlet and a saturated steam outlet.

3. The device system according to claim 1 or 2, characterized in that: An oxidation catalyst is arranged inside the catalytic oxidation reactor; Preferably, the oxidation catalyst comprises a solid solution substrate, and a platinum group metal supported on the solid solution substrate; Preferably, the solid solution matrix comprises, by weight percentage: 1-10wt% silicon dioxide, 0.5-5wt% yttrium oxide, and the balance zirconium oxide; Preferably, the specific surface area of ​​the solid solution substrate is 200 to 300 m 2 / g; Preferably, the loading amount of the platinum group metal is 3 to 5 g / L; Preferably, the specifications of the oxidation catalyst are a cross-section of 150×150 mm, a length of 70 to 80 mm, and an average pore size of 350 to 450 meshes.

4. The device system according to any one of claims 1 to 3, characterized in that: A denitration catalyst is arranged inside the SCR denitration reactor; Preferably, the denitration catalyst comprises a titanium dioxide carrier, and an active component supported on the titanium dioxide carrier; Preferably, the active components include metallic cerium and metallic manganese; Preferably, the molar ratio of the metal elements cerium, manganese and titanium in the denitration catalyst is 0.1-0.3:0.05-0.2:

1.

5. A method for coupling CO recovery and waste heat recovery in sintering flue gas, characterized in that: The method is carried out using the device system described in any one of claims 1 to 4.

6. The method according to claim 5, characterized in that The method comprises the following steps: (1) Sintering flue gas and dilution air are mixed in a waste gas buffer tank, and then denitrified by an SCR denitrification reactor to obtain denitrified flue gas; (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1), and then performing a CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas; (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

7. The method according to claim 6, characterized in that The concentration of CO in the sintering flue gas in step (1) is 6000-10000 mg / Nm 3 ; Preferably, the concentration of NOx in the sintering flue gas in step (1) is ≤300 mg / Nm 3 ; Preferably, the temperature of the sintering flue gas in step (1) is 120-130°C.

8. The method according to claim 6 or 7, characterized in that: The temperature of the denitration treatment in step (1) is 120-130°C.

9. The method according to any one of claims 6 to 8, characterized in that: The terminal temperature of the heating treatment in step (2) is 150-220°C; Preferably, the temperature of the CO catalytic oxidation treatment in step (2) is 150-220°C; Preferably, the reaction space velocity of the CO catalytic oxidation treatment in step (2) is 20000-40000h -1 .

10. The method according to any one of claims 6 to 9, characterized in that: The method comprises the following steps: (1) Mix the waste gas at 120-130°C and CO concentration of 6000-10000 mg / Nm 3 The sintering flue gas and the dilution air are then denitrated by the SCR denitration reactor to obtain denitrated flue gas; the denitration treatment temperature is 120-130°C; (2) using a flue gas heating device to heat the denitrified flue gas obtained in step (1) to 150-220° C., and then performing CO catalytic oxidation treatment in a catalytic oxidation reactor to obtain a high-temperature mixed flue gas; the CO catalytic oxidation treatment temperature is 150-220° C., and the reaction space velocity is 20000-40000 h -1 ; (3) The high-temperature mixed flue gas obtained in step (2) is refluxed to the flue gas heating device for cooling treatment, and then passed through the waste heat boiler for secondary cooling to obtain exhaust gas.

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