Blast furnace blowdown gas recovery system and method

Abstract

The application discloses a blast furnace blow-off gas recovery system and method, and belongs to the technical field of blast furnace iron-making. In order to solve the problem of environmental pollution caused by low-pressure blow-off gas emission, the blast furnace blow-off gas recovery system comprises a dust collector (2), an inlet instrument group (6) and a TRT (20) connected in sequence, and the TRT (20) is connected with a gas pressurizing pipeline in parallel. The gas pressurizing pipeline comprises an inlet pipeline (5), a main working pipeline (10) and an outlet pipeline (17) connected in sequence. Along the direction from the inlet end of the main working pipeline (10) to the outlet end of the main working pipeline (10), a gas pressurizing device (12) and a three-way switch valve (13) are arranged on the main working pipeline (10) in sequence. The blast furnace blow-off gas recovery system and method can purify and recover 100% of the blow-off gas, and solve the problem of environmental pollution caused by blow-off gas emission.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, specifically to a blast furnace shutdown gas recovery system and a blast furnace shutdown gas recovery method. Background Technology

[0002] Shutdown gas refers to the process from production to shutdown of a blast furnace. During this period, the gas inside the furnace is gradually discharged, and the discharged gas is called shutdown gas. The composition of shutdown gas generally meets the requirements for recycling into the clean gas pipeline network. The flow rate and pressure of shutdown gas gradually decrease as the shutdown process progresses. Currently, most steel plants can only recover the high-pressure portion of shutdown gas from the early stage. High-pressure shutdown gas is discharged from the blast furnace, passes through the dust removal system, and then enters the clean gas pipeline network after passing through the pressure regulating valve group and TRT equipment. Because the flow rate and pressure of shutdown gas fluctuate significantly, the recovery process has a large impact on the clean gas pipeline network, sometimes affecting the operating conditions of other gas users. In addition, since the current shutdown gas recovery utilizes the pressure difference between the blast furnace and the clean gas pipeline network, the pressure difference gradually decreases over time, slowing down the recovery speed and affecting production efficiency. In the later stage, the pressure difference between the low-pressure shutdown gas and the clean gas pipeline network is small, so the recovery is slow and there is a risk of gas backflow. Therefore, most steel plants directly discharge the gas into the atmosphere through venting from the furnace top. The gas produced during the shutdown process contains a large amount of dust and air pollutants, and the current airborne emission treatment has caused serious environmental pollution.

[0003] Definitions:

[0004] TRT (Blast Furnace Gas Residual Pressure Turbine Generator): This system utilizes the pressure and thermal energy of blast furnace top gas, a byproduct of blast furnace smelting. The gas is passed through a turbine expander, converting it into mechanical energy, which is then converted into electrical energy. The high-pressure blast furnace gas enters the TRT unit, where it expands and drives a generator to produce electricity. The low-pressure blast furnace gas exiting the turbine enters the low-pressure pipeline network. Summary of the Invention

[0005] To address the environmental pollution caused by the emission of low-pressure shutdown gas into the atmosphere, this invention provides a blast furnace shutdown gas recovery system and method. The blast furnace shutdown gas recovery system and method can 100% purify and recover the shutdown gas, thus solving the environmental pollution problem caused by the emission of shutdown gas into the atmosphere.

[0006] The technical solution adopted by the embodiments of the present invention to solve its technical problem is as follows:

[0007] A blast furnace shutdown gas recovery system includes a dust collector, an inlet instrument group, and a TRT connected in sequence. The TRT is connected in parallel to a gas pressurization pipeline. The gas pressurization pipeline includes an inlet pipeline, a main working pipeline, and an outlet pipeline connected in sequence. An inlet valve is installed on the inlet pipeline. Along the direction from the inlet end to the outlet end of the main working pipeline, a gas pressurization device and a three-way switching valve are installed in sequence on the main working pipeline. A loop is also provided on the main working pipeline. The three-way switching valve enables the gas discharged from the gas pressurization device to enter the outlet pipeline or return to the gas pressurization device through the loop.

[0008] A method for recovering blast furnace shutdown gas, wherein the method employs the aforementioned blast furnace shutdown gas recovery system, and the method comprises the following steps in sequence:

[0009] Step 1: Before restarting the blast furnace after a shutdown;

[0010] With the inlet valve closed, the gas pressurizing device is turned on, and the three-way switching valve allows the gas discharged from the gas pressurizing device to return to the gas pressurizing device through the circuit;

[0011] Step 2, during the blast furnace shutdown and restart process;

[0012] When the pressure detected by the inlet instrument group is 2 to 3 times higher than the pressure in the clean gas pipeline, the shut-off gas discharged from the blast furnace is recycled into the clean gas pipeline after being processed by the TRT; when the pressure detected by the inlet instrument group is 2 to 3 times lower than or equal to the pressure in the clean gas pipeline, the TRT is cut off, and the shut-off gas discharged from the blast furnace enters the inlet pipeline for blast furnace shutdown recovery. At this time, the silencer is closed, the inlet valve and the working pipeline valve are opened, and the three-way switching valve is switched to allow the gas discharged from the gas pressurization device to enter the outlet pipeline, and the shut-off gas in the outlet pipeline enters the clean gas pipeline.

[0013] Step 3: Blast furnace shutdown ends;

[0014] The three-way switching valve switches the direction so that the gas discharged from the gas pressurizing device returns to the gas pressurizing device through the circuit. The gas pressurizing device gradually stops working, the inlet valve is closed, the silencer is opened, and the residual gas is discharged into the air through the silencer.

[0015] The beneficial effects of the embodiments of the present invention are:

[0016] 1. This blast furnace shutdown gas recovery system can purify and recover 100% of the shutdown gas.

[0017] 2. It can ensure the stable pressure of the gas entering the gas pipeline network.

[0018] 3. The fan can be stopped or operated at low power at any time using the circuit and three-way switching valve.

[0019] 4. It can address problems that may occur during the gas recovery process: excessive gas flow, single fan failure, fan surge, negative pressure caused by excessive fan extraction, and oxygen content in the gas. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a schematic diagram of the blast furnace shutdown gas recovery system described in this invention.

[0022] The annotations in the attached figures are explained as follows:

[0023] 1. Blast furnace; 2. Dust collector; 3. Check valve; 4. Clean gas pipeline; 5. Inlet pipeline; 6. Inlet instrument group; 7. First corrugated compensator; 8. Silencer; 9. Inlet valve; 10. Main working pipeline; 11. Working pipeline valve; 12. Gas pressurization device; 13. Three-way switching valve; 14. Check valve; 15. Circuit; 16. Outlet pressure gauge; 17. Outlet pipeline; 18. Second corrugated compensator; 19. Standby working pipeline; 20. TRT (Total Refrigerant Regulator). Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 As shown in the embodiment of the present invention, a blast furnace shutdown gas recovery system includes a dust collector 2, an inlet instrument group 6, and a TRT20 connected in sequence. The TRT20 is connected in parallel to a gas pressurization pipeline. The gas pressurization pipeline includes an inlet pipeline 5, a main working pipeline 10, and an outlet pipeline 17 connected in sequence. An inlet valve 9 is installed on the inlet pipeline 5. Along the direction from the inlet end to the outlet end of the main working pipeline 10, a gas pressurization device 12 and a three-way switching valve 13 are installed in sequence on the main working pipeline 10. A circuit 15 is also installed on the main working pipeline 10. The three-way switching valve 13 enables the gas discharged from the gas pressurization device 12 to enter the outlet pipeline 17 or return to the gas pressurization device 12 through the circuit 15.

[0026] The imported instrument group 6 is used to determine whether the gas indicators meet the recovery requirements and to determine the recovery method. Based on the characteristic of "high pressure in the early stage and low pressure in the later stage" of the shut-in gas, the pressure of the shut-in gas in blast furnace 1 is higher than that in the clean gas pipeline 4 in the early stage. Utilizing the pressure difference, the shut-in gas is recovered to the clean gas pipeline after passing through TRT20. TRT20 can convert the excess pressure energy of the shut-in gas into electrical energy. During this process, the pipeline is always under positive pressure, so there is no possibility of outside air entering the gas pipeline. As the gas pressure gradually decreases, the gas recovery speed slows down in the middle and later stages. To avoid affecting production efficiency, when the pressure of the imported instrument group 6 drops to 2-3 times the pressure of the clean gas pipeline, TRT20 is shut off. At this time, the gas is recovered to the clean gas pipeline 4 after passing through the inlet pipeline 5, the gas pressurization station 12, and the outlet pipeline 17. The gas pressurization device 12 can make the gas pressure greater than the gas pressure in the clean gas pipeline 4. The blast furnace shutdown gas recovery system can purify and discharge the unrecoverable shutdown gas in the early stage, and safely recover the recoverable shutdown gas in the later stage after purification.

[0027] The three-way switching valve 13 has one inlet and two outlets. Gas entering through the inlet of the three-way switching valve 13 can be discharged from either the first or second outlet. The inlet of the gas pressurizing device 12 is connected to the outlet of the inlet pipe 5, and the outlet of the gas pressurizing device 12 is connected to the inlet of the three-way switching valve 13. The first outlet of the three-way switching valve 13 is connected to the inlet of the outlet pipe 17. The inlet of the circuit 15 is connected to the second outlet of the three-way switching valve 13, and the outlet of the circuit 15 is connected to the inlet of the gas pressurizing device 12.

[0028] like Figure 1 As shown, a working pipeline valve 11 is also provided on the main working pipeline 10, and a one-way valve 14 is provided on the circuit 15. The gas in the circuit 15 can only flow from the inlet end of the circuit 15 to the outlet end of the circuit 15, and the gas in the circuit 15 cannot flow from the outlet end of the circuit 15 to the inlet end of the circuit 15. The blast furnace shutdown gas recovery system also includes a control unit (such as a PLC). The three-way switching valve 13 and the working pipeline valve 11 are all interlocked (or connected) with the control unit.

[0029] The gas pressurizing device 12 is also interlocked with the control unit. The gas pressurizing device 12 is a variable frequency fan (blower) and includes a fan, a motor, and a frequency converter connected in sequence. The motor can be understood as a conventional variable frequency motor. The fan bearing is equipped with a vibration detector, the fan is equipped with a decibel detector, and the motor is equipped with a speed detector. The vibration detector, decibel detector, and speed detector are all interlocked with the control unit.

[0030] During the adjustment process, the gas system is prone to self-backflow. When the gas pressurizing device 12 experiences self-backflow (reverse flow into the blower), it will cause surge, which will affect the operation of the equipment and even bring safety hazards. Therefore, the aforementioned vibration detector, decibel detector, and speed detector are installed. When blower surge is detected, the three-way switching valve 13 automatically switches its position, disconnecting the main working pipeline 10 from the outlet pipeline 17 and connecting it to the circuit 15. The gas pressurizing device 12 no longer sends gas into the clean gas pipeline network 4, but instead connects the inlet and outlet of the gas pressurizing device 12 through the circuit 15 to form an internal circulation, thereby preventing the blower surge caused by the backflow of gas into the gas pressurizing device 12.

[0031] The fan shaft is connected to the output shaft of the variable frequency motor via a diaphragm coupling, and the variable frequency motor adjusts its speed through a frequency converter. The fan can adopt a single-inlet cantilever design or other structures, offering advantages such as simple structure, convenient maintenance, and stable operation. It is directly driven by the variable frequency motor through the diaphragm coupling, and the fan rotor rotates counterclockwise when viewed from the motor end. The fan casing and bearing housing are made of cast iron or similar materials, with a sealed structure at the rear of the casing. The rotor consists of a main shaft and an impeller. To adapt to the frequent changes in operating conditions of the gas recovery fan during shutdowns, the main shaft and impeller are made of high-strength, durable materials such as metals and composite materials to enhance the fan's anti-stall and anti-surge capabilities. The rotor undergoes static and dynamic balancing for smooth operation. The fan is equipped with lubrication, hydraulic, and water pipelines, as well as an oil pump. The casing, rotor, and bearing housing are mounted on an integrated base.

[0032] Surge is accompanied by a sharp increase in noise. When the decibel meter equipped with the fan detects a sudden increase in the noise generated by the fan, the decibel meter sends a signal to the control unit. The control unit controls the three-way switching valve 13 to switch, disconnecting the main working pipeline 10 from the outlet pipeline 17 and connecting it to the circuit 15. The fan outlet no longer supplies gas to the clean gas network 4, and the airflow will flow back to the front end of the fan through the circuit 15, forming an internal circulation. Its function is twofold: first, to cut off the connection between the rear end of the fan and the clean gas network 4 and the standby working pipeline 19, so that the gas will not flow back to the gas pressurization device 12, avoiding fan surge; second, by utilizing the circuit to form an internal circulation, the fan speed can be adjusted, thereby achieving low-energy standby or gradual shutdown of the fan to adapt to the complex needs of actual production.

[0033] like Figure 1 As shown, the blast furnace shutdown gas recovery system also includes a standby working pipeline 19, which is connected in parallel with the main working pipeline 10. The structure of the standby working pipeline 19 is the same as that of the main working pipeline 10. The devices on the standby working pipeline 19 are also interlocked with the control unit.

[0034] The working pipeline valve 11 controls the connection and disconnection of the pipeline, the one-way valve 14 ensures unidirectional gas flow in the circuit 15, and the gas pressurization device 12 is an explosion-proof variable frequency fan. When the gas flow during shutdown is too large and exceeds the capacity of the gas pressurization device 12, or when the equipment on the main working pipeline 10 malfunctions, the equipment on the backup working pipeline 19 can be activated to ensure the smooth operation of gas recovery under abnormal conditions.

[0035] Both the imported instrument group 6 and the imported valve 9 are interlocked with the control unit. The imported instrument group 6 contains a gas composition detector, a pressure gauge, a flow meter, and a temperature gauge. The gas composition detector can detect whether oxygen (O2) is present in the inlet pipeline 5. The gas composition detector can also be called an oxygen detector.

[0036] The imported instrument group 6 is used to determine whether the gas indicators meet the requirements for recovery. When the gas in the shutdown gas contains components such as oxygen that do not meet the recovery requirements, the gas will not be recovered. At this time, the dust collector 2 is turned on. At the same time, the silencer 8 is turned on to purify the gas in the inlet pipeline 5 before it is discharged.

[0037] like Figure 1 As shown, blast furnace 1, dust collector 2, TRT20, and clean gas pipeline 4 are connected in sequence. TRT20 may contain a pressure regulating valve assembly. The inlet end of dust collector 2 is connected to the furnace mouth of blast furnace 1. The shut-off gas discharged from blast furnace 1 can pass through dust collector 2 and TRT20 in sequence before entering clean gas pipeline 4. The inlet end of inlet pipe 5 is located between the outlet end of dust collector 2 and the inlet end of TRT20, and the inlet end of inlet pipe 5 is connected to the outlet end of dust collector 2.

[0038] Along the direction from the inlet end to the outlet end of the gas pressurization pipeline, the inlet pipeline 5, the main working pipeline 10, and the outlet pipeline 17 are arranged. The inlet pipeline 5 is also equipped with a first corrugated compensator 7 and a silencer 8, with the silencer 8 located between the first corrugated compensator 7 and the inlet valve 9.

[0039] The first bellows compensator 7 is used to offset the expansion of the pipeline at different temperatures, so as to avoid the pipeline from expansion and contraction deformation. An inlet valve 9 is provided after the first bellows compensator 7. The inlet valve 9 can be a single valve or a combination of multiple valves, and can be in the form of butterfly valve, blind valve, ball valve, etc., and can be driven by hydraulic, pneumatic or other methods. The inlet valve 9 is connected to the PLC control system.

[0040] like Figure 1As shown, the outlet end of TRT20 is connected to the clean gas pipeline network 4. The outlet end of outlet pipeline 17 is located between the outlet end of TRT20 and the clean gas pipeline network 4. The outlet end of outlet pipeline 17 is connected to the outlet end of TRT20. Along the direction from the inlet end of outlet pipeline 17 to the outlet end of outlet pipeline 17, an outlet pressure gauge 16, a second corrugated compensator 18 and a check valve 3 are sequentially installed on outlet pipeline 17. The blast furnace shutdown gas recovery system also includes a control unit. The outlet pressure gauge 16 is interlocked with the control unit.

[0041] The pressure measured by the outlet pressure gauge 16 is interlocked with the rotational speed of the gas pressurizing device 12. When the gas inlet pressure in the outlet pipeline 17 is high, the exhaust pressure of the gas pressurizing device 12 also increases accordingly, allowing the gas pressurizing device 12 to operate at low speed. When the gas inlet pressure in the outlet pipeline 17 is low, the discharge and pressure of the gas pressurizing device 12 are also low. In this case, the fan can be operated at high speed by adjusting the speed to ensure that the fan outlet pressure is stable and always greater than the gas pipeline pressure. The control unit collects the inlet pressure signal to control the fan speed. A second corrugated compensator 18 is installed on the outlet pipeline 17 to compensate for the expansion of the pipeline at different temperatures, thus avoiding pipeline deformation. A check valve 3 prevents backflow of gas from the clean gas pipeline 4 into the system.

[0042] The shutdown gas discharged from blast furnace 1 can pass through dust collector 2, inlet pipe 5, main working pipe 10 and outlet pipe 17 in sequence before entering clean gas network 4. Check valve 3 can ensure that the gas in outlet pipe 17 can only flow from the inlet end of outlet pipe 17 to the outlet end of outlet pipe 17, and the gas in outlet pipe 17 cannot flow from the outlet end of outlet pipe 17 to the inlet end of outlet pipe 17.

[0043] Leaks are prone to occur at pipe welding points and sealing rubber rings in various blast furnace systems during long-term production. During production, the blast furnace system is under positive pressure, preventing outside air from entering. In the later stages of shut-down gas recovery, the amount of gas in the system is low. If the gas pressurization device 12 exerts excessive suction, it may drain the gas from the system, creating negative pressure. This would cause outside air to enter the blast furnace system and mix with the gas. To eliminate safety hazards, the imported instrument group 6 monitors the system pressure and connects the signal to the control unit. When the pressure drops below atmospheric pressure, the system issues a low-pressure warning, and the shut-down gas system stops recovery. Simultaneously, the silencer 8 opens, releasing the gas through it to prevent air from entering the clean gas pipeline 4.

[0044] When the normal operation of the gas recovery system ends or is stopped due to an emergency, the three-way switching valve 13 switches its direction, disconnecting the main working pipeline 10 from the outlet pipeline 17 and connecting it to the circuit 15; the inlet valve 9 and the working pipeline valve 11 are closed. At this time, the gas pressurizing device 12 and the circuit 15 form a closed loop, causing the gas pressurizing device 12 to steadily reduce its speed until it stops. The silencer 8 is activated to purify and release the remaining gas, and the gas recovery system issues a shutdown command.

[0045] The following describes a method for recovering blast furnace shutdown gas. This method utilizes the aforementioned blast furnace shutdown gas recovery system and includes the following steps:

[0046] Step 1: Before restarting the blast furnace after a shutdown;

[0047] The inlet valve 9 is closed, the working pipeline valve 11 is closed, the gas pressurizing device 12 is turned on, and the three-way switching valve 13 allows the gas discharged from the gas pressurizing device 12 to return to the gas pressurizing device 12 through the circuit 15. The power of the gas pressurizing device 12 is gradually increased until the predetermined speed is reached. For example, the speed of the gas pressurizing device 12 is increased to 50% of the rated speed.

[0048] Step 2, during the blast furnace shutdown and restart process;

[0049] When the inlet instrument group 6 detects that the pressure in the pipeline is 2 to 3 times (e.g., 2 times) higher than the pressure in the clean gas pipeline 4, the shut-off gas discharged from blast furnace 1 is recovered into the clean gas pipeline 4 after TRT20 performs work; when the pressure detected by the inlet instrument group 6 is lower than or equal to 2 to 3 times (e.g., 2 times) lower than the pressure in the clean gas pipeline 4, TRT20 is cut off, and the shut-off gas discharged from blast furnace 1 only enters the inlet pipeline 5. The dust collector 2 is always working, and the inlet instrument group 6 detects the shut-off gas. The inlet instrument group 6 sends the detection result to the control unit to perform blast furnace shut-off gas recovery. At this time, the silencer 8 is closed, the inlet valve 9 and the working pipeline valve 11 are opened (the standby working pipeline 19 is closed and not working), and the three-way switching valve 13 switches the direction so that the gas discharged from the gas pressurization device 12 enters the outlet pipeline 17, and the shut-off gas in the outlet pipeline 17 enters the clean gas pipeline 4;

[0050] Step 3: Blast furnace shutdown ends;

[0051] The three-way switching valve 13 switches the direction so that the gas discharged from the gas pressurizing device 12 returns to the gas pressurizing device 12 through the circuit 15. The gas pressurizing device 12 gradually stops working, closes the inlet valve 9, opens the silencer 8, and the residual gas is discharged into the air through the silencer 8.

[0052] The steps in the blast furnace shutdown gas recovery method are in the following order: Step 1, Step 2, and Step 3. In Step 2, during the blast furnace shutdown gas recovery process (i.e., when the inlet instrument group 6 detects that there is no oxygen in the inlet pipeline 5):

[0053] When the outlet pressure gauge 16 detects that the gas pressure in the outlet pipeline 17 minus the gas pressure in the clean gas pipeline 4 is greater than or equal to the set value (e.g., 10KPa-15KPa), the control unit makes the gas pressurizing device 12 operate at a low speed, such as the actual speed of the fan in the gas pressurizing device 12 being 30%-50% of the rated speed; when the outlet pressure gauge 16 detects that the gas pressure in the outlet pipeline 17 minus the gas pressure in the clean gas pipeline 4 is less than the set value (e.g., 10KPa-15KPa), the control unit makes the gas pressurizing device 12 operate at a high speed, such as the actual speed of the fan in the gas pressurizing device 12 being 70%-90% of the rated speed; in order to ensure that the outlet pressure of the gas pressurizing device 12 is stable and always greater than the pressure of the clean gas pipeline 4, the idle gas is purified by the dust collector 2 and then pressurized by the gas pressurizing device 12 to be recovered to the clean gas pipeline 4.

[0054] Normally, only the main working pipeline 10 is operational. When the inlet instrument group 6 detects that the gas flow rate exceeds twice the rated flow rate of the gas pressurizing device 12, or when the main working pipeline 10 malfunctions, the backup working pipeline 19 is activated. That is, the working pipeline valve 11 in the backup working pipeline 19 is opened, and the gas pressurizing device 12 in the backup working pipeline 19 is operational, thereby ensuring the smooth operation of gas recovery under abnormal conditions.

[0055] When the blast furnace shutdown and recovery are suspended, the three-way switching valve 13 switches the direction so that the gas discharged from the gas pressurizing device 12 returns to the gas pressurizing device 12 through the circuit 15, that is, the gas pressurizing device 12 is circulated internally. The gas pressurizing device 12 reduces its speed to standby mode. The speed of the gas pressurizing device 12 in standby mode is 10%-20% of the rated speed to achieve low power consumption standby.

[0056] When the decibel level generated by the gas pressurizing device 12 is more than twice the normal operating decibel level, the three-way switching valve 13 switches the direction so that the gas discharged from the gas pressurizing device 12 returns to the gas pressurizing device 12 through the circuit 15; thereby preventing the fan surge caused by the backflow of gas into the gas pressurizing device 12 and protecting the equipment.

[0057] When the inlet instrument group 6 detects that the gas pressure in the pipeline is lower than one standard atmosphere, the blast furnace shutdown gas recovery system issues a low-pressure warning, stops the recovery, and closes the inlet valve 9 to prevent air from entering the clean gas pipeline 4.

[0058] When the inlet instrument group 6 detects oxygen in the pipeline, the blast furnace shutdown gas recovery system issues an oxygen warning, opens the silencer 8, closes the inlet valve 9, and the blast furnace shutdown gas recovery system stops recovery. The gas in the inlet pipeline 5 is released into the air through the silencer 8 to prevent oxygen from entering the clean gas pipeline network 4.

[0059] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of protection of this patent, should still fall within the scope of this patent. Furthermore, the technical features, technical solutions, and embodiments of the present invention can be freely combined and used.

Claims

1. A blast furnace blowdown gas recovery system characterized by, The blast furnace shutdown gas recovery system includes a dust collector (2), an inlet instrument group (6) and a TRT (20) connected in sequence. The TRT (20) is connected in parallel with a gas pressurization pipeline. The gas pressurization pipeline includes an inlet pipeline (5), a main working pipeline (10) and an outlet pipeline (17) connected in sequence. An inlet valve (9) is installed on the inlet pipeline (5). Along the direction from the inlet end of the main working pipeline (10) to the outlet end of the main working pipeline (10), a gas pressurization device (12) and a three-way switching valve (13) are installed in sequence on the main working pipeline (10). A loop (15) is also installed on the main working pipeline (10). The three-way switching valve (13) enables the gas discharged from the gas pressurization device (12) to enter the outlet pipeline (17) or return to the gas pressurization device (12) through the loop (15). The three-way switching valve (13) has one inlet end and two outlet ends. The inlet end of the gas pressurizing device (12) is connected to the outlet end of the inlet pipeline (5). The outlet end of the gas pressurizing device (12) is connected to the inlet end of the three-way switching valve (13). The first outlet end of the three-way switching valve (13) is connected to the inlet end of the outlet pipeline (17). The inlet end of the circuit (15) is connected to the second outlet end of the three-way switching valve (13). The outlet end of the circuit (15) is connected to the inlet end of the gas pressurizing device (12).

2. The blast furnace blowdown gas recovery system of claim 1, wherein, The main working pipeline (10) is also equipped with a working pipeline valve (11), and the loop (15) is equipped with a one-way valve (14). The gas in the loop (15) can only flow from the inlet end of the loop (15) to the outlet end of the loop (15). The blast furnace shutdown gas recovery system also includes a control unit. The three-way switching valve (13) and the working pipeline valve (11) are all interlocked with the control unit.

3. The blast furnace shutdown gas recovery system according to claim 1, characterized in that, The blast furnace shutdown gas recovery system also includes a control unit, and a gas pressurization device (12) is interlocked with the control unit. The gas pressurization device (12) contains a fan, a motor and a frequency converter connected in sequence. The fan bearing is equipped with a vibration detector, the fan is equipped with a decibel detector, and the motor is equipped with a speed detector.

4. The blast furnace shutdown gas recovery system according to claim 1, characterized in that, The blast furnace shutdown gas recovery system also includes a standby working pipeline (19), which is connected in parallel with the main working pipeline (10). The structure of the standby working pipeline (19) is the same as that of the main working pipeline (10).

5. The blast furnace shutdown gas recovery system according to claim 1, characterized in that, The blast furnace shutdown gas recovery system also includes a control unit. The inlet instrument group (6) and the inlet valve (9) are all interlocked with the control unit. The inlet instrument group (6) contains a gas composition detector, a pressure gauge, a flow meter and a temperature gauge. The gas composition detector can detect whether there is O2 in the inlet pipeline (5).

6. The blast furnace shutdown gas recovery system according to claim 1, characterized in that, The inlet end of the dust collector (2) is connected to the furnace mouth of the blast furnace (1). The inlet end of the inlet pipe (5) is located between the outlet end of the dust collector (2) and the inlet end of the TRT (20). The inlet end of the inlet pipe (5) is connected to the outlet end of the dust collector (2). The inlet pipe (5) is also equipped with a first corrugated compensator (7) and a silencer (8). The silencer (8) is located between the first corrugated compensator (7) and the inlet valve (9).

7. The blast furnace shutdown gas recovery system according to claim 1, characterized in that, The outlet end of TRT (20) is connected to the clean gas pipeline network (4). The outlet end of the outlet pipeline (17) is located between the outlet end of TRT (20) and the clean gas pipeline network (4). The outlet end of the outlet pipeline (17) is connected to the outlet end of TRT (20). Along the direction from the inlet end of the outlet pipeline (17) to the outlet end of the outlet pipeline (17), the outlet pipeline (17) is sequentially equipped with an outlet pressure gauge (16), a second corrugated compensator (18) and a check valve (3). The blast furnace shutdown gas recovery system also includes a control unit. The outlet pressure gauge (16) is interlocked with the control unit.

8. A method for recovering blast furnace shutdown gas, characterized in that, The blast furnace shutdown gas recovery method employs the blast furnace shutdown gas recovery system described in claim 1, and the blast furnace shutdown gas recovery method includes the following steps in sequence: Step 1: Before restarting the blast furnace after a shutdown; When the inlet valve (9) is closed, the gas pressurizing device (12) is turned on. The three-way switching valve (13) causes the gas discharged from the gas pressurizing device (12) to return to the gas pressurizing device (12) through the circuit (15). Step 2, during the blast furnace shutdown and restart process; When the pressure detected by the inlet instrument group (6) is higher than twice the pressure in the clean gas pipeline (4), the shut-off gas discharged from the blast furnace (1) is recycled into the clean gas pipeline (4) after the TRT (20) does work; when the pressure detected by the inlet instrument group (6) is lower than or equal to twice the pressure in the clean gas pipeline (4), the TRT (20) is cut off, and the shut-off gas discharged from the blast furnace (1) enters the inlet pipeline (5) for blast furnace shutdown recovery. At this time, the silencer (8) is closed, the inlet valve (9) and the working pipeline valve (11) are opened, and the three-way switching valve (13) switches the direction so that the gas discharged from the gas pressurization device (12) enters the outlet pipeline (17), and the shut-off gas in the outlet pipeline (17) enters the clean gas pipeline (4). Step 3: Blast furnace shutdown ends; The three-way switching valve (13) switches the direction so that the gas discharged from the gas pressurizing device (12) returns to the gas pressurizing device (12) through the circuit (15). The gas pressurizing device (12) gradually stops working, closes the inlet valve (9), opens the silencer (8), and the residual gas is discharged into the air through the silencer (8).

9. The method for recovering blast furnace shutdown gas according to claim 8, characterized in that, In step 2, during the blast furnace shutdown and recovery process: When the outlet pressure gauge (16) detects that the gas pressure in the outlet pipeline (17) minus the gas pressure in the clean gas pipeline (4) is greater than or equal to the set value, the gas pressurizing device (12) operates at low speed; when the outlet pressure gauge (16) detects that the gas pressure in the outlet pipeline (17) minus the gas pressure in the clean gas pipeline (4) is less than the set value, the gas pressurizing device (12) operates at high speed. When the inlet instrument group (6) detects that the gas flow rate exceeds twice the rated flow rate of the gas pressurizing device (12), or when the main working pipeline (10) malfunctions, the backup working pipeline (19) is activated. When the blast furnace shutdown recovery is suspended, the three-way switching valve (13) switches the direction so that the gas discharged from the gas pressurizing device (12) returns to the gas pressurizing device (12) through the circuit (15), and the gas pressurizing device (12) reduces its speed to standby state; When the decibel level generated by the gas pressurizing device (12) is more than twice the normal operating decibel level of the gas pressurizing device (12), the three-way switching valve (13) switches the direction so that the gas discharged from the gas pressurizing device (12) returns to the gas pressurizing device (12) through the circuit (15); When the gas pressure detected by the inlet instrument group (6) is lower than one atmosphere, the blast furnace shutdown gas recovery system issues a low pressure warning, the blast furnace shutdown gas recovery system stops recovery, and the inlet valve (9) closes. When the inlet instrument group (6) detects the presence of O2, the blast furnace shutdown gas recovery system issues an oxygen warning, opens the silencer (8), closes the inlet valve (9), and the blast furnace shutdown gas recovery system stops recovering. The gas in the inlet pipeline (5) is released into the air through the silencer (8).

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