An embedded SCR flue gas denitration device and method for a blast furnace hot blast stove

Abstract

The present invention discloses an embedded SCR flue gas denitration device and method for a blast furnace hot blast stove, relating to the technical field of flue gas denitration of blast furnace hot blast stoves. The device includes a blast furnace hot blast stove, a main flue, a heat exchanger group, and an end device connected in sequence according to the flow direction. It also includes an SCR denitration reactor. The SCR denitration reactor is connected to the main flue through an inlet flue at an air extraction point and through an outlet flue at a gas return point. A first electric shut-off valve and an ammonia injection device are installed on the inlet flue, a second electric shut-off valve is installed on the outlet flue, and a first electric regulating valve is installed on the main flue. The first electric regulating valve is arranged between the air extraction point and the gas return point. It can maintain the stability of the main flue pressure, improve the sudden change of flue gas pressure caused by the sudden change of flue gas volume during the furnace tilting and furnace changing of the blast furnace hot blast stove, set the SCR system in the high-temperature flue gas section of the blast furnace hot blast stove, utilize the positive pressure of the hot blast stove exhaust to overcome the resistance of the SCR system, and the start-stop and operation of the SCR system do not affect the normal production of the original equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of denitrification of flue gas from blast furnace hot stoves, and particularly to an embedded SCR flue gas denitrification device and method for blast furnace hot stoves. Background Art

[0002] In recent years, with the implementation of the ultra-low emission work in the iron and steel industry, major nitrogen oxide emitters such as sintering, pelletizing, and coking in the iron and steel industry have basically achieved ultra-low emissions. However, for blast furnace hot stoves, especially large blast furnace hot stoves, due to their high roof temperature, the NOx content in the discharged waste flue gas remains high. Given the great difficulty in treating them, the environmental protection index of the waste flue gas emission from blast furnace hot stoves has been maintained at 100 mg / Nm 3 , which is significantly higher than the ultra-low emission indexes of sintering and pelletizing. Therefore, to comprehensively promote the implementation of ultra-low emissions in the iron and steel industry, it is urgent to develop a flue gas denitrification technology suitable for blast furnace hot stoves.

[0003] According to the technological requirements of the iron-making blast furnace, each blast furnace is usually equipped with 3 - 4 hot stoves, which work in a cyclic and alternating manner. The hot stoves emit waste gas during the firing process and do not emit waste gas during the air supply process. Since the waste gas emission volume of the hot stove system decreases instantaneously by 50% during the stove-changing stage, and after the stove-changing is completed, the flue gas volume instantaneously returns to 100%. During this period, the flue gas volume changes greatly and rapidly, which has a certain impact on the pressure stability of the hot stove system and is not conducive to adding an SCR denitrification reactor. Summary of the Invention

[0004] Based on the above problems, the present application provides an embedded SCR flue gas denitrification device and method for blast furnace hot stoves.

[0005] The present application provides an embedded SCR flue gas denitrification device for blast furnace hot stoves, which includes a blast furnace hot stove, a main flue, a heat exchanger group, and an end device connected in sequence according to the flow direction. Multiple blast furnace hot stoves are respectively connected to the main flue through exhaust flue gas ducts; the embedded SCR flue gas denitrification device for blast furnace hot stoves further includes an SCR denitrification reactor. The SCR denitrification reactor is communicated with the main flue through an inlet flue at an air-intake point and through an outlet flue at a gas-return point. The inlet flue is equipped with a first electric shut-off valve and an ammonia injection device, the outlet flue is equipped with a second electric shut-off valve, and a first electric regulating valve is installed on the main flue. The air-intake point, the first electric regulating valve, and the gas-return point are arranged in sequence according to the flow direction on the main flue. Under the condition of sudden change in flue gas volume when the blast furnace hot stove is tilting or changing stoves, it is controlled that the first electric shut-off valve and the second electric shut-off valve are changed from the open state to the closed state, and the first electric regulating valve maintains the open state.

[0006] In some embodiments, a first pressure monitoring device and a second pressure monitoring device are further installed on the main flue. The first pressure monitoring device, the air-intake point, the first electric regulating valve, the gas-return point, and the second pressure monitoring device are arranged in sequence according to the flow direction on the main flue.

[0007] In some embodiments, a temperature monitoring device is further installed on the main flue, and in the flow direction of the main flue, the temperature monitoring device is arranged before the air extraction point.

[0008] In some embodiments, the terminal equipment includes a chimney and a pulverized coal injection and milling device. The chimney and the pulverized coal injection and milling device are arranged in parallel, and both the chimney and the pulverized coal injection and milling device are connected to the flue gas pipeline of the heat exchanger group.

[0009] In some embodiments, the heat exchanger group includes a flue gas-air heat exchanger and a flue gas-gas heat exchanger arranged in parallel. One end of the flue gas pipeline of the flue gas-air heat exchanger and one end of the flue gas pipeline of the flue gas-gas heat exchanger are both connected to the main flue, and the other end is led to the terminal equipment. One end of the air pipeline of the flue gas-air heat exchanger is connected to the combustion-supporting fan, and the other end is led to the blast furnace hot blast stove. One end of the gas pipeline of the flue gas-gas heat exchanger is connected to the gas inlet, and the other end is led to the blast furnace hot blast stove.

[0010] In some embodiments, a second electric control valve is installed at the inlet end of the air pipeline of the flue gas-air heat exchanger, and a third electric control valve is installed at the outlet end. A first bypass is arranged in parallel between the inlet and outlet of the flue gas-air heat exchanger, and a fourth electric control valve is installed on the first bypass; a first differential pressure monitoring device is installed on the flue gas pipeline of the flue gas-air heat exchanger, and the first differential pressure monitoring device is connected to the inlet end and the outlet end of the flue gas pipeline of the flue gas-air heat exchanger.

[0011] In some embodiments, a fifth electric control valve is installed at the inlet end of the gas pipeline of the flue gas-gas heat exchanger, and a sixth electric control valve is installed at the outlet end. A second bypass is arranged in parallel between the inlet and outlet of the flue gas-gas heat exchanger, and a seventh electric control valve is installed on the second bypass; a second differential pressure monitoring device is installed on the flue gas pipeline of the flue gas-gas heat exchanger, and the second differential pressure monitoring device is connected to the inlet end and the outlet end of the flue gas pipeline of the flue gas-gas heat exchanger.

[0012] In some embodiments, the embedded SCR flue gas denitration device for blast furnace hot blast stove further includes a preheating furnace. The preheating furnace is installed on the connecting channel between the air pipeline of the flue gas-air heat exchanger and the blast furnace hot blast stove. The preheating furnace is connected to the main flue through an exhaust flue, and the connection point formed is located before the air extraction point in the flow direction of the main flue.

[0013] An embedded SCR flue gas denitration method for blast furnace hot blast stove, which applies the above-mentioned embedded SCR flue gas denitration device for blast furnace hot blast stove, the method includes:

[0014] The embedded SCR flue gas denitration device of the blast furnace hot blast stove starts to operate. Open the first electric shut-off valve and the second electric shut-off valve, and gradually reduce the opening degree of the first electric regulating valve so that part of the flue gas enters the SCR denitration reactor along the inlet flue through the air extraction point, and the remaining flue gas continues to be transported along the first electric regulating valve;

[0015] After part of the flue gas enters the SCR denitration reactor, the SCR denitration reactor reduces the NOx concentration in this part of the flue gas to 30 mg / Nm 3 or less;

[0016] Part of the flue gas after passing through the SCR denitration reactor joins the main flue through the return air point along the outlet flue and mixes with part of the flue gas coming from the first electric regulating valve. The NOx concentration in the mixed flue gas reaches 50 mg / Nm 3 or less, and the mixed flue gas is transported to the end equipment for treatment after heat exchange through the heat exchanger group.

[0017] In some embodiments, the method further includes: under the condition of sudden change in the amount of flue gas in the main flue during the tilting and furnace changing of the blast furnace hot blast stove, changing the first electric shut-off valve and the second electric shut-off valve from the open state to the closed state, and keeping the first electric regulating valve open to maintain the stability of the system pressure.

[0018] The beneficial effects of the present application are as follows: A blast furnace hot stove embedded SCR flue gas denitration device is provided, which includes a blast furnace hot stove, a main flue, a heat exchanger group, and an end device connected in sequence according to the flow direction. The flue gas generated by the blast furnace hot stove enters the main flue; during normal operation, the opening of the first electric control valve is adjusted so that part of the flue gas passes through the first electric control valve, and the other part of the flue gas enters the inlet flue through the opened first electric shut-off valve. The ammonia gas sent by the ammonia injection device is mixed evenly with the flue gas and then enters the SCR denitration reactor. The denitration reaction is completed under the action of the catalyst. The denitrated flue gas enters the outlet flue through the opened second electric shut-off valve, enters the main flue after passing through the gas return point, and is mixed with the part of the non-denitrated flue gas coming from the first electric control valve. The NOx concentration of the mixed flue gas meets the emission requirements. The mixed flue gas provides heat for the heat exchanger group and is finally sent to the end device for emission or reuse; when the blast furnace hot stove is tilting or changing stoves, the flue gas volume decreases instantaneously by 50%. The first electric shut-off valve and the second electric shut-off valve are adjusted to the closed state, and the opening state of the first electric control valve is maintained. The flue gas flows through the first electric control valve. Therefore, this device plays a role in maintaining the stability of the main flue pressure, protects the SCR denitration reactor, maintains the normal operation of the heat exchanger group and the end device, and improves the sudden change of flue gas pressure caused by the sudden change of flue gas volume when the blast furnace hot stove is tilting or changing stoves; this device sets the SCR system in the high-temperature flue gas section of the blast furnace hot stove, where the flue gas temperature is 250-350°C, which can meet the temperature requirements for the denitration reaction. The catalyst has high activity and high efficiency, and does not require heat supplementation, which can reduce energy consumption; the positive pressure of the hot stove exhaust gas is used to overcome the resistance of the SCR system, so there is no need to set up a heat-resistant fan, which solves the contradiction that the frequency conversion rate of the fan cannot follow up with the sudden change of flue gas volume when the blast furnace hot stove is changing stoves or tilting, and saves the electricity consumption of the fan; the start-stop and operation of the SCR system do not affect the normal production of the original equipment, and the SCR system can be quickly started and put into or cut off from the hot stove production sequence at any time. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention.

[0020] Figure 1 It is a schematic structural diagram of the blast furnace hot stove embedded SCR flue gas denitration device provided by the present application;

[0021] Figure 2 It is a schematic flow diagram of a method for the blast furnace hot stove embedded SCR flue gas denitration provided by the present application.

[0022] Attached drawing markings: 100 - blast furnace hot blast stove, 110 - flue gas discharge duct, 200 - main flue, 210 - first electric control valve, 220 - first pressure monitoring device, 230 - second pressure monitoring device, 240 - temperature monitoring device, 300 - heat exchanger group, 310 - flue gas - air heat exchanger, 311 - flue gas duct, 311a - first differential pressure monitoring device, 312 - air duct, 312a - second electric control valve, 312b - third electric control valve, 313 - first bypass, 313a - fourth electric control valve, 320 - flue gas - gas heat exchanger, 321 - flue gas duct, 321a - second differential pressure monitoring device, 322 - gas duct, 322a - fifth electric control valve, 322b - sixth electric control valve, 323 - second bypass, 323a - seventh electric control valve, 400 - end equipment, 410 - chimney, 420 - pulverized coal injection equipment, 421 - waste gas induced draft fan, 500 - SCR denitration reactor, 510 - inlet flue, 511 - gas extraction point, 512 - first electric shutoff valve, 513 - ammonia injection device, 520 - outlet flue, 521 - gas return point, 522 - second electric shutoff valve, 600 - combustion support fan, 700 - gas inlet, 800 - preheating furnace. Detailed implementation mode

[0023] Example 1

[0024] This example discloses an embedded SCR flue gas denitration device for a blast furnace hot blast stove. Please refer to Figure 1 , which includes a blast furnace hot blast stove 100, a main flue 200, a heat exchanger group 300, and an end equipment 400 that are connected in sequence according to the flow direction. Multiple blast furnace hot blast stoves 100 are respectively connected to the main flue 200 through a flue gas discharge duct 110, and the blast furnace hot blast stove 100 discharges waste gas along the flue gas discharge duct 110.

[0025] Please refer to Figure 1 , the embedded SCR flue gas denitration device for a blast furnace hot blast stove further includes an SCR denitration reactor 500. The SCR denitration reactor 500 is communicated with the main flue 200 through an inlet flue 510 at a gas extraction point 511, and the SCR denitration reactor 500 is communicated with the main flue 200 through an outlet flue 520 at a gas return point 521. Flue gas can enter the SCR denitration reactor 500 from the gas extraction point 511 and then return to the main flue 200 from the gas return point 521.

[0026] Please refer to Figure 1, a first electric shut-off valve 512 and an ammonia injection device 513 are installed in the inlet flue 510. The on-off of the inlet flue 510 is controlled by the first electric shut-off valve 512, and the airtightness can also be ensured. The ammonia gas introduced by the ammonia injection device 513 enters the SCR denitration reactor 500 after being evenly mixed with the flue gas. A second electric shut-off valve 522 is installed in the outlet flue 520. The on-off of the outlet flue 520 is controlled by the second electric shut-off valve 522, and the airtightness can also be ensured. A first electric regulating valve 210 is installed on the main flue 200, and the opening degree is adjusted by the first electric regulating valve 210. An air extraction point 511, the first electric regulating valve 210 and a gas return point 521 are arranged in sequence along the flow direction on the main flue 200. Under the condition of sudden change in flue gas volume during the furnace tilting and furnace changing of the blast furnace hot blast stove 100, the first electric shut-off valve 512 and the second electric shut-off valve 522 are controlled to change from the open state to the closed state, and the first electric regulating valve 210 is maintained in the open state.

[0027] Specifically, during normal operation, that is, when the situation of sudden change in flue gas volume during the furnace tilting and furnace changing of the blast furnace hot blast stove 100 does not occur, all flue gases are aggregated to the start section of the main flue 200. The first electric shut-off valve 512 and the second electric shut-off valve 522 are in the open state. The opening degree of the first electric regulating valve 210 is gradually reduced, so that part of the flue gas passes through the first electric regulating valve 210, and other flue gases enter the inlet flue 510 along the opened first electric shut-off valve 512. The ammonia gas sent by the ammonia injection device 513 is evenly mixed with the flue gas and then enters the SCR denitration reactor 500. The denitration reaction is completed under the action of the catalyst. The flue gas after denitration enters the outlet flue 520 through the opened second electric shut-off valve 522. After entering the main flue 200 through the gas return point 521, it is mixed with the part of the un-denitrated flue gas coming from the first electric regulating valve 210. The NOx concentration of the mixed flue gas meets the emission requirements. The subsequent mixed flue gas provides heat for the heat exchanger group 300 and is finally sent to the terminal equipment 400 for direct emission or reuse.

[0028] When the furnace tilting and furnace changing of the blast furnace hot blast stove 100 occur, the flue gas volume instantaneously decreases by 50%. At this time, the first electric shut-off valve 512 and the second electric shut-off valve 522 are adjusted from the open state to the closed state, and the open state of the first electric regulating valve 210 is maintained. At this time, the flue gas flows through the first electric regulating valve 210 and no longer passes through the SCR denitration reactor 500. Therefore, this device plays a role in maintaining the pressure stability of the main flue 200, protects the SCR denitration reactor 500, is beneficial to the normal operation of the heat exchanger group 300 and the terminal equipment 400, and improves the sudden change in flue gas pressure caused by the sudden change in flue gas volume during the furnace tilting and furnace changing of the blast furnace hot blast stove 100.

[0029] The inlet flue 510, the ammonia injection device 513, the SCR denitration reactor 500, the outlet flue 520, and the valves installed on the inlet flue 510 and the outlet flue 520 can be collectively referred to as the SCR system. In this device, the SCR system is arranged in the high-temperature flue gas section of the blast furnace hot stove 100, where the flue gas temperature is 250 - 350 °C, which can meet the temperature requirements for the denitration reaction. The catalyst has high activity and high efficiency, and no heat supplement is required, which can reduce energy consumption.

[0030] By arranging the SCR system in the high-temperature flue gas section of the blast furnace hot stove 100, the positive pressure of the hot stove exhaust is utilized to overcome the resistance of the SCR system. Therefore, there is no need to set up a heat-resistant fan, which solves the contradiction that the variable frequency rate of the fan cannot keep up with the sudden change of the flue gas volume during the furnace change and furnace inversion of the blast furnace hot stove 100, and saves the electricity consumption of the fan.

[0031] In addition, when this device is applied, the start-stop and operation of the SCR system do not affect the normal production of the original equipment, and the SCR system can be quickly started and put into or cut off from the hot stove production sequence at any time.

[0032] In some embodiments, please refer to Figure 1 A temperature monitoring device 240 is also installed on the main flue 200. In the flow direction of the main flue 200, the temperature monitoring device 240 is arranged before the air extraction point 511. The flue gas temperature in the main flue 200 at this location is obtained through the temperature monitoring device 240. When the flue gas temperature at this location exceeds a preset value, such as 400 °C, the first electric shut-off valve 512 and the second electric shut-off valve 522 are interlocked to close, cutting off the passage of the flue gas into the SCR system, and all the flue gas is conveyed through the branch where the first electric regulating valve 210 is located, so as to relieve the adverse damage of high temperature to the SCR denitration reactor 500 and the catalyst in the reactor, and realize the over-temperature protection of the SCR denitration reactor 500.

[0033] In some embodiments, the blast furnace hot stove embedded SCR flue gas denitration device further includes a preheating furnace 800. The combustion-supporting air entering the blast furnace hot stove 100 is preheated by the preheating furnace 800, and the flue gas generated by the preheating furnace 800 can be merged into the main flue 200 for denitration reaction.

[0034] In some embodiments, the end device 400 includes a chimney 410 and a pulverized coal injection and preparation device 420. The pulverized coal injection and preparation device 420 and the chimney 410 are arranged in parallel. Specifically, both the chimney 410 and the pulverized coal injection and preparation device 420 are connected to the flue gas pipeline of the heat exchanger group 300. After heat exchange and utilization, part of the flue gas is discharged through the chimney 410, and part of the flue gas is sent to the pulverized coal injection and preparation device 420 by the waste gas induced draft fan 421.

[0035] In some embodiments, please refer to Figure 1, the heat exchanger group 300 includes a flue gas-air heat exchanger 310 and a flue gas-gas heat exchanger 320 arranged in parallel. The flue gas-air heat exchanger 310 heats the combustion-supporting air conveyed by the combustion-supporting air blower 600, and the flue gas-gas heat exchanger 320 heats the blast furnace gas.

[0036] Please refer to Figure 1 , it is described above that the flue gas-air heat exchanger 310 and the flue gas-gas heat exchanger 320 are arranged in parallel. Specifically, one end of the flue gas pipeline 311 of the flue gas-air heat exchanger 310 is connected to the main flue 200, and the other end leads to the terminal device 400. One end of the flue gas pipeline 321 of the flue gas-gas heat exchanger 320 is connected to the main flue 200, and the other end leads to the terminal device 400. Additionally, one end of the air pipeline 312 of the flue gas-air heat exchanger 310 is connected to the combustion-supporting air blower 600, and the other end leads to the blast furnace hot blast stove 100. One end of the gas pipeline 322 of the flue gas-gas heat exchanger 320 is connected to the gas inlet 700, and the other end leads to the blast furnace hot blast stove 100 to smoothly achieve the transportation of combustion-supporting air and blast furnace gas.

[0037] In the solution where the heat exchanger group 300 includes a flue gas-air heat exchanger 310 and a flue gas-gas heat exchanger 320 arranged in parallel, the preheating furnace 800 is installed on the connection channel between the air pipeline 312 of the flue gas-air heat exchanger 310 and the blast furnace hot blast stove 100. The preheating furnace 800 is connected to the main flue 200 through the flue gas exhaust duct 110, and the connection point formed is located before the air extraction point 511 in the flow direction of the main flue 200. (The main function of the preheating furnace is to provide hot air for the hot blast stove. It is considered okay to be with the hot blast stove. This is also similar common sense)

[0038] In some embodiments, please refer to Figure 1 , a first pressure monitoring device 220 and a second pressure monitoring device 230 are also installed on the main flue 200. On the main flue 200, the first pressure monitoring device 220, the air extraction point 511, the first electric control valve 210, the air return point 521, and the second pressure monitoring device 230 are arranged in sequence according to the flow direction. It can be understood that, please refer to Figure 1 , in the flow direction of the main flue 200, the connection point between the preheating furnace 800 and the main flue 200 is before the first pressure monitoring device 220. The first pressure monitoring device 220 and the second pressure monitoring device 230 are used to respectively obtain the flue gas pressure before the air extraction point 511 and the flue gas pressure value after the air return point 521, and the gas supply volume of the blast furnace gas and the flow rate of the combustion-supporting air are adjusted through the pressure values to maintain the pressure values in each area within a preset range.

[0039] The adjustment of the pressure values in each region is mentioned above. Specifically, since the resistance of the SCR system needs to be overcome by the positive exhaust pressure of the blast furnace hot stove 100, the resistance of the SCR system is controlled ≤ 1000 Pa. By adjusting the frequencies of the sixth electric control valve 322b and the combustion-supporting fan 600, the pressure of the main flue 200 at the second pressure monitoring device 230 is maintained at 300 - 400 Pa, thus ensuring the operation of the flue gas-air heat exchanger 310 and the flue gas-gas heat exchanger 320 in a safe working environment. At the same time, the pressure of the main flue 200 at the first pressure monitoring device 220 is controlled ≤ 1600 Pa to ensure the normal operation of the blast furnace hot stove 100 and the preheating furnace 800.

[0040] During the normal operation process, the first electric control valve 210 maintains a certain opening degree, allowing some flue gas not to pass through the SCR system, reducing the sudden change in flue gas pressure caused by the sudden change in flue gas volume during the furnace tilting and furnace changing of the blast furnace hot stove 100, maintaining the stability of the system pressure, and controlling the maximum value of the pressure of the main flue 200 at the first pressure monitoring device 220 ≤ 2000 Pa.

[0041] In some embodiments, please refer to Figure 1 , at the inlet end of the air pipeline 312 of the flue gas-air heat exchanger 310, a second electric control valve 312a is installed, and at the outlet end, a third electric control valve 312b is installed. A first bypass 313 is connected in parallel between the inlet and outlet of the flue gas-air heat exchanger, and a fourth electric control valve 313a is installed on the first bypass 313. The parallel setting is mentioned in this section. It can be understood that both the second electric control valve 312a and the third electric control valve 312b are installed on the branch where the air pipeline 312 is located. In addition, a first differential pressure monitoring device 311a is also installed on the flue gas pipeline 311 of the flue gas-air heat exchanger 310, and the first differential pressure monitoring device 311a is connected to the inlet end and the outlet end of the flue gas pipeline 311 of the flue gas-air heat exchanger 310.

[0042] Specifically, the differential pressure between the inlet and outlet pipelines of the flue gas pipeline 311 of the flue gas-air heat exchanger 310 is obtained through the first differential pressure monitoring device 311a. When the system resistance in the reaction exceeds 1.4 times the initial value, the second electric control valve 312a and the third electric control valve 312b are closed, and the fourth electric control valve 313a is opened, thereby blocking the air from entering the flue gas-air heat exchanger 310 again, raising the outlet temperature of the flue gas pipeline 311 of the heat exchanger 310 above 280 °C, realizing the analysis protection of the heat exchanger by using the hot flue gas, and alleviating the problem of blockage of the heat exchanger caused by the long-term accumulation of NH4HSO4 generated in the low-temperature outlet area of the heat exchanger.

[0043] In some embodiments, please refer to Figure 1, a fifth electric control valve 322a is installed at the inlet end of the gas pipeline 322 of the flue gas-gas heat exchanger 320, and a sixth electric control valve 322b is installed at the outlet end. A second bypass 323 is connected in parallel between the inlet and outlet of the flue gas-gas heat exchanger. A seventh electric control valve 323a is installed on the second bypass 323. This paragraph mentions a parallel setting. It can be understood that the fifth electric control valve 322a and the sixth electric control valve 322b are arranged on the branch where the gas pipeline 322 is located. In addition, a second differential pressure monitoring device 321a is also installed on the flue gas pipeline 321 of the flue gas-gas heat exchanger 320, and the second differential pressure monitoring device 321a is connected to the inlet end and the outlet end of the flue gas pipeline 321 of the flue gas-gas heat exchanger 320.

[0044] Specifically, similar to the flue gas-air heat exchanger 310, the differential pressure between the inlet and outlet pipelines of the flue gas pipeline 321 of the flue gas-gas heat exchanger 320 is obtained through the second differential pressure monitoring device 321a. When the system resistance of the reaction exceeds 1.4 times the initial value, the fifth electric control valve 322a and the sixth electric control valve 322b are closed, and the seventh electric control valve 323a is opened, thereby blocking the blast furnace gas from entering the flue gas-gas heat exchanger 320 again, increasing the outlet temperature of the flue gas pipeline 321 of the heat exchanger 320 to above 280 °C, realizing the analysis protection of the heat exchanger by using the hot flue gas, and alleviating the problem of blockage of the heat exchanger caused by the long-term accumulation of NH4HSO4 generated in the low-temperature outlet area of the heat exchanger.

[0045] The above-mentioned first pressure monitoring device 220 and second pressure monitoring device 230 are mentioned. The flow rate of the blast furnace gas and the flow rate of the combustion-supporting air delivered to the blast furnace heating furnace are adjusted through the pressure value. Specifically, the opening degree of the sixth electric control valve 322b and the frequency of the combustion-supporting fan 600 are adjusted through the pressure value.

[0046] Embodiment 2

[0047] Based on the blast furnace hot blast stove embedded SCR flue gas denitration device provided in Embodiment 1, this embodiment provides a method for blast furnace hot blast stove 100 embedded SCR flue gas denitration. Please refer to Figure 2 , including:

[0048] The blast furnace hot blast stove embedded SCR flue gas denitration device starts to operate. The flue gas generated by the blast furnace hot blast stove 100 (and the flue gas generated by the preheating furnace 800) converges in the main flue 200. The first electric shut-off valve 512 and the second electric shut-off valve 522 are opened, and the opening degree of the first electric control valve 210 is gradually reduced, so that part of the flue gas enters the SCR denitration reactor 500 along the inlet flue 510 through the air extraction point 511, and the remaining flue gas is transported along the branch where the first electric control valve 210 is located;

[0049] After a part of the flue gas enters the SCR denitration reactor 500, under the action of the catalyst in the reactor, the SCR denitration reactor 500 reduces the NOx concentration in this part of the flue gas to 30 mg / Nm 3 Next, after the denitration reaction is completed, it is ready to return to the main flue 200;

[0050] A part of the flue gas after passing through the SCR denitration reactor 500 flows along the outlet flue 520 and merges into the main flue 200 through the gas return point 521, and is mixed with a part of the flue gas coming through the first electric control valve 210. The NOx concentration in the mixed flue gas reaches 50 mg / Nm 3 Next;

[0051] The mixed flue gas is heat-exchanged by the heat exchanger group 300 and then transported to the terminal equipment 400 for treatment. Specifically, a part of the flue gas is sent to the pulverized coal injection equipment 420 by the waste gas induced draft fan 421, and the rest of the flue gas is discharged through the chimney 410.

[0052] When the blast furnace hot stove 100 tilts or changes the stove, the flue gas volume in the main flue 200 changes suddenly. The embedded SCR flue gas denitration method for the blast furnace hot stove 100 in this embodiment further includes changing the first electric shut-off valve 512 and the second electric shut-off valve 522 from the open state to the closed state, and the first electric control valve 210 remains open to maintain the system pressure stability, improving the sudden change in flue gas pressure caused by the sudden change in flue gas volume when the blast furnace hot stove 100 tilts or changes the stove.

[0053] After the tilting and stove changing are completed, the flue gas volume in the main flue 200 returns to 100%. Correspondingly, the first electric shut-off valve 512 and the second electric shut-off valve 522 are opened, and a part of the flue gas enters the SCR system to complete the denitration reaction.

[0054] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0055] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. An embedded SCR flue gas denitration device for a blast furnace hot blast stove, characterized in that, It includes a blast furnace hot blast stove, a main flue, a heat exchanger group, and a terminal device connected in sequence according to the flow direction. A plurality of the blast furnace hot blast stoves are respectively connected to the main flue through exhaust gas flues; The embedded SCR flue gas denitration device for the blast furnace hot blast stove further includes an SCR denitration reactor. The SCR denitration reactor is communicated with the main flue through an inlet flue at an air intake point and communicated with the main flue through an outlet flue at a gas return point. A first electric shut-off valve and an ammonia injection device are installed on the inlet flue, a second electric shut-off valve is installed on the outlet flue, and a first electric regulating valve is installed on the main flue. The air intake point, the first electric regulating valve, and the gas return point are arranged in sequence according to the flow direction on the main flue. Under the condition of sudden change in flue gas volume when the blast furnace hot blast stove is tilting or changing stoves, control the first electric shut-off valve and the second electric shut-off valve to change from the open state to the closed state, and the first electric regulating valve maintains the open state; A first pressure monitoring device and a second pressure monitoring device are also installed on the main flue. The first pressure monitoring device, the air intake point, the first electric regulating valve, the gas return point, and the second pressure monitoring device are arranged in sequence according to the flow direction on the main flue; A temperature monitoring device is also installed on the main flue. The temperature monitoring device is arranged before the air intake point in the flow direction of the main flue.

2. The embedded SCR flue gas denitration device for blast furnace hot blast stove according to claim 1, characterized in that, The terminal device includes a chimney and a pulverized coal injection and pulverizing device. The chimney and the pulverized coal injection and pulverizing device are arranged in parallel, and both the chimney and the pulverized coal injection and pulverizing device are communicated with the flue gas pipeline of the heat exchanger group.

3. The embedded SCR flue gas denitration device for blast furnace hot blast stove according to claim 1 or 2, characterized in that, The heat exchanger group includes a flue gas-air heat exchanger and a flue gas-coal gas heat exchanger arranged in parallel. One end of the flue gas pipeline of the flue gas-air heat exchanger and one end of the flue gas pipeline of the flue gas-coal gas heat exchanger are both communicated with the main flue, and the other end is led to the terminal device. One end of the air pipeline of the flue gas-air heat exchanger is communicated with an auxiliary combustion blower, and the other end is led to the blast furnace hot blast stove. One end of the coal gas pipeline of the flue gas-coal gas heat exchanger is communicated with a coal gas inlet, and the other end is led to the blast furnace hot blast stove.

4. The embedded SCR flue gas denitration device for blast furnace hot blast stove according to claim 3, characterized in that, A second electric regulating valve is installed at the inlet end of the air pipeline of the flue gas-air heat exchanger, and a third electric regulating valve is installed at the outlet end. A first bypass is connected in parallel between the inlet and outlet of the flue gas-air heat exchanger, and a fourth electric regulating valve is installed on the first bypass; A first differential pressure monitoring device is installed on the flue gas pipeline of the flue gas-air heat exchanger, and the first differential pressure monitoring device is connected to the inlet end and the outlet end of the flue gas pipeline of the flue gas-air heat exchanger.

5. The embedded SCR flue gas denitration device for blast furnace hot blast stove according to claim 3, wherein, A fifth electric regulating valve is installed at the inlet end of the coal gas pipeline of the flue gas-coal gas heat exchanger, and a sixth electric regulating valve is installed at the outlet end. A second bypass is connected in parallel between the inlet and outlet of the flue gas-coal gas heat exchanger, and a seventh electric regulating valve is installed on the second bypass; A second differential pressure monitoring device is installed on the flue gas pipeline of the flue gas-coal gas heat exchanger, and the second differential pressure monitoring device is connected to the inlet end and the outlet end of the flue gas pipeline of the flue gas-coal gas heat exchanger.

6. The embedded SCR flue gas denitration device for blast furnace hot blast stove according to claim 3, wherein, The embedded SCR flue gas denitration device for blast furnace hot blast stove further includes a preheating furnace, and the preheating furnace is connected to the main flue through an exhaust flue, and the connection point formed by the connection is located before the air extraction point in the flow direction of the main flue.

7. An embedded SCR flue gas denitrification method for a blast furnace hot blast stove, characterized in that Applying the embedded SCR flue gas denitration device for blast furnace hot blast stove according to any one of claims 1-6, the method includes: The embedded SCR flue gas denitration device for blast furnace hot blast stove starts to operate, the first electric shut-off valve and the second electric shut-off valve are opened, and the opening degree of the first electric regulating valve is gradually reduced, so that part of the flue gas enters the SCR denitration reactor along the inlet flue through the air extraction point, and the remaining flue gas continues to be transported along the first electric regulating valve; After a part of the flue gas enters the SCR denitration reactor, the SCR denitration reactor reduces the NOx concentration in this part of the flue gas to 30 mg / Nm 3 or less; Part of the flue gas after passing through the SCR denitration reactor is merged into the main flue through the return air point along the outlet flue, and is mixed with part of the flue gas coming from the first electric control valve. The NOx concentration in the mixed flue gas reaches 50mg / Nm 3 Next, the mixed flue gas is heat-exchanged by the heat exchanger group and then transported to the terminal equipment for treatment.

8. The embedded SCR flue gas denitration method for blast furnace hot blast stove according to claim 7, characterized in that The method further includes: under the condition that the amount of flue gas in the main flue suddenly changes when the blast furnace hot blast stove is tilted or the furnace is changed, the first electric shut-off valve and the second electric shut-off valve are changed from the open state to the closed state, and the first electric regulating valve remains open to maintain the system pressure stable.

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