CN217351416U

CN217351416U - Blast furnace diffused gas recycling and diffusing device

Info

Publication number: CN217351416U
Application number: CN202122572944.4U
Authority: CN
Inventors: 赵素梅
Original assignee: Beijing Zhongbei Ouruizhi Engineering Technology Co ltd
Current assignee: Beijing Zhongbei Ouruizhi Engineering Technology Co ltd
Priority date: 2021-10-25
Filing date: 2021-10-25
Publication date: 2022-09-02
Anticipated expiration: 2031-10-25

Abstract

The application relates to a blast furnace diffused gas recovery diffusing device, and relates to the field of blast furnace gas purification and recovery technology. It includes furnace body, gas pipeline, dust collector, pressure reducing valve group and coal gas pipe network, and furnace body and coal gas pipe network communicate respectively in the both ends of gas pipeline, and dust collector and pressure reducing valve group lay in proper order on the gas pipeline between furnace body and coal gas pipe network, its characterized in that: the blast furnace gas injection device is characterized by further comprising an injection assembly, wherein the injection assembly comprises an external gas source and an injector, the injector is installed on the gas pipeline, the external gas source is communicated with the injector, and the blast furnace gas directionally moves towards the gas pipeline network under the driving of the external gas source. The method can be used for carrying out full recovery on the blast furnace gas when the gas quality meets the recovery conditions; when the coal gas does not meet the recovery condition, the coal gas is purified and then is diffused, so that the pollution of the environment caused by the toxic and harmful gas diffused by the blast furnace is reduced as much as possible.

Description

Blast furnace diffused gas recycling and diffusing device

Technical Field

The application relates to the field of blast furnace gas purification and recovery technology, in particular to a blast furnace diffused gas recovery and diffusion device.

Background

In the production of blast furnaces, iron ore, coke and a flux for slag formation are generally charged from the top of the furnace, and preheated air is blown through tuyeres located along the periphery of the furnace at the lower part of the furnace. And reacting carbon element in the coke with oxygen element blown into air at high temperature to generate carbon monoxide, and carrying out oxidation reduction reaction with the oxygen element in the iron ore in the ascending process in the furnace so as to obtain molten iron. The generated gas is led out from the top of the furnace, dedusted and input into a special gas pipe network to be used as fuel of a hot blast stove, a heating furnace, a coke oven or a boiler.

Referring to fig. 1, there is shown a blast furnace gas processing apparatus in the related art. The device includes furnace body 1, gas pipeline 2, dust collector 3, diffuse pipeline 4, pressure reducing valve group 5, silencing device 6 and coal gas pipe network 7, diffuse pipeline 4 and gas pipeline 2 and all set up the top position department at furnace body 1, be provided with the valve 41 that diffuses that is used for controlling the 4 switching of pipeline of diffusing in the pipeline 4 of diffusing, pressure reducing valve group 5 and silencing device 6 are installed on gas pipeline 2 in proper order in the direction of keeping away from furnace body 1, and the one end and the coal gas pipe network 7 intercommunication that furnace body 1 was kept away from to gas pipeline 2.

During normal production of the blast furnace, the bleeding valve 41 is closed, and the pressure reducing valve block 5 is opened. The coal gas generated by the blast furnace can be input into a coal gas pipe network 7 through a coal gas pipeline 2 to recycle the coal gas generated by the blast furnace.

In the process of blast furnace iron making, the operations of blowing out and restarting the blast furnace are often carried out, the input process of gradually reducing the air volume during blowing out is blowing down, and the process of gradually increasing the air volume input during restarting the blast furnace is reblowing.

In the processes of damping down and re-blowing, under the condition that the air inlet amount in the blast furnace is small, the pressure in the direction of the blast furnace is reduced, the coal gas generated by the blast furnace is difficult to be continuously input into a coal gas pipe network 7, and a worker usually opens a bleeding valve 41 at the top of the blast furnace after closing a pressure reducing valve group 5, so that the coal gas generated by the blast furnace is directly diffused into the air through a bleeding pipeline 4.

Aiming at the related technologies, the inventor finds that the quality of coal gas meets the recovery condition in the damping-down process, but the treatment mode that the treatment device in the related technologies directly diffuses the coal gas into the air causes waste of the coal gas generated by the coal gas generated in the damping-down process of the blast furnace.

SUMMERY OF THE UTILITY MODEL

In order to improve the processing mode that the processing apparatus among the relevant art is in the damping down process, the coal gas that produces the blast furnace with the quality accords with the condition of retrieving directly diffuses to the air and causes extravagant problem, this application provides a blast furnace diffuses coal gas recovery diffusing device.

The application provides a blast furnace diffuses coal gas recovery diffusing device adopts following technical scheme:

the utility model provides a blast furnace diffuses coal gas and retrieves diffusing device, which comprises a furnace body, the gas pipeline, dust collector, pressure reducing valve group and coal gas pipe network, furnace body and coal gas pipe network communicate respectively in the both ends of gas pipeline, dust collector and pressure reducing valve group lay in proper order on the gas pipeline between furnace body and coal gas pipe network, retrieve diffusing device still including drawing the penetrating subassembly, draw the penetrating subassembly to include outside air supply and ejector, the ejector is installed on the gas pipeline, outside air supply and ejector intercommunication, under the drive of outside air supply, blast furnace gas takes place directional movement towards the coal gas pipe network.

By adopting the technical scheme, the worker can open the gas valve to enable the high-pressure gas flow to drive the coal gas to be totally recycled into the gas pipe network in the damping down process, so that the waste of the coal gas caused by the direct discharge of the coal gas meeting the recycling condition in the damping down process is reduced.

Optionally, the gas in the external gas source is selected from water vapor.

By adopting the technical scheme, the cost of high-pressure gas is reduced to a certain extent, and meanwhile, the water vapor can further adsorb residual dust substances in the coal gas, so that the residual of the dust substances in the coal gas is reduced as much as possible.

Optionally, a buffer tower is arranged between the ejector and the bleeding valve, and a demister is arranged in an inner cavity of the buffer tower.

Through adopting above-mentioned technical scheme, the dust in vapor and the coal gas has carried out more abundant mixture and has taken place to condense and subside, and the defroster can eliminate owing to adsorb the dust material in the coal gas or because the condensation live condensation phenomenon appears atomizing or liquefied vapor, has reduced the flow of vapor in the pipeline to a certain extent to the content of dust in the coal gas has further been reduced.

Optionally, a drain pipe is arranged at the bottom of the buffer tower, and a drain valve is installed on the drain pipe.

Through adopting above-mentioned technical scheme, the sewage that is detained in pipeline and buffer tower assembles can follow the blow off pipe outflow behind the buffer tower bottom to the cleanness of buffer tower and pipeline inner chamber has been kept to a certain extent.

Optionally, the gas pipeline includes conventional pipeline and external recovery pipeline, furnace body and gas pipe network communicate respectively in the both ends of conventional pipeline, dust collector and pressure reducing valve group lay in proper order on the conventional pipeline between furnace body and gas pipe network, the both ends of external recovery pipeline all communicate with conventional pipeline between dust collector and gas pipe network, install the off-line valves of the open and close of external recovery pipeline of control on the external recovery pipeline, draw the subassembly to install on external recovery pipeline, and draw the subassembly to connect in parallel with the pressure reducing valve group.

Through adopting above-mentioned technical scheme for it is easier when the staff reforms transform conventional pipeline, has improved external recovery pipeline as far as possible and has added the flexibility when establishing, and the condition that the place is not enough when the installation of various facilities on the at utmost has been avoided external recovery pipeline.

Optionally, the two groups of off-line valve banks are respectively located at two ends of the external recovery pipeline.

By adopting the technical scheme, the external recovery pipeline can be in a complete off-line state after the two groups of off-line valve groups are closed by a worker, and the conveying distance of coal gas in the coal gas pipeline is reduced to a certain extent.

Optionally, the offline valve group comprises a cut-off butterfly valve and a blind plate valve which are connected in series.

By adopting the technical scheme, the circulation of the pipelines at the two sides of the off-line device can be reduced as much as possible by cutting off the butterfly valve and the blind plate valve, the isolation effect of the off-line valve group on the pipelines at the two sides of the off-line device is ensured when the coal gas is recovered by the recovery and diffusion device, and the condition of coal gas leakage is also reduced when the coal gas is recovered.

Optionally, a diffusing pipeline is arranged on the external recycling pipeline, a diffusing valve for controlling the opening and closing of the diffusing pipeline is installed on the diffusing pipeline, and one end of the diffusing pipeline is communicated with the gas pipeline between the buffer tower and the gas pipe network.

By adopting the technical scheme, when the worker diffuses the coal gas which is not in accordance with the recovery condition in the process of re-air through the diffusing pipe, the coal gas can be filtered and dedusted for many times, so that the dust amount carried in the diffused coal gas is reduced as much as possible, and the pollution of the blast furnace gas to the environment during diffusion is reduced as much as possible.

Optionally, the ejector is of a tubular structure, orifices at two ends of the ejector are named as an air source port and an air outlet respectively, an air inlet is formed in the pipe wall of the ejector, the air source port of the ejector is communicated with an air source pipeline, the air inlet and the air outlet of the ejector are communicated with an external recovery pipeline, and coal gas flows to the air outlet from the air inlet in the ejector.

By adopting the technical scheme, when high-pressure airflow passes through the ejector, negative pressure can be generated at the position of the air inlet, so that coal gas in the ejector moves towards the air outlet along the air inlet under the action of the negative pressure.

Optionally, the inner circumferential surface of the gas source port is a tapered surface, and the port of the gas source pipeline is a tapered port adapted to the gas source port.

Through adopting above-mentioned technical scheme, guaranteed the leakproofness of being connected between ejector and the air supply pipeline to a certain extent.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the injection assembly is arranged on the gas pipeline, so that the recovery and diffusion device can recover the gas in a damping-down state, and further the waste of the gas in the damping-down process is reduced;

2. the external recovery pipeline is arranged on the original conventional pipeline, and the ejector is arranged on the external recovery pipeline, so that the worker can modify the conventional pipeline more conveniently;

3. through setting up the pipeline that diffuses on the external recovery pipeline for diffuse recovery unit can remove dust to the coal gas that needs to diffuse among the compound wind process, thereby has reduced the dust content in the diffused coal gas as far as possible, has reduced the pollution to the environment when diffusing of coal gas that is not conform to the recovery condition.

Drawings

Fig. 1 is a schematic view of a layout of a diffusion recovery apparatus in the related art.

Fig. 2 is a schematic layout diagram of a diffusion recovery device in the embodiment of the present application.

Fig. 3 is a sectional view of an installation structure of an ejector in an embodiment of the present application.

Description of reference numerals: 1. a furnace body; 2. a gas pipeline; 21. a conventional pipeline; 22. a recovery pipeline is arranged outside; 221. an off-line valve bank; 3. a dust removal device; 31. a coarse dust collector; 32. a fine dust collector; 4. a blow-off line; 41. a bleeding valve; 5. a pressure relief valve bank; 6. a silencer device; 7. a gas pipe network; 8. an injection assembly; 81. an external gas source; 811. a gas source conduit; 8111. a flow stabilizing pipe; 812. an air valve; 82. an ejector; 821. a gas source port; 822. an air outlet; 823. an air inlet; 824. shrinking the pipe; 9. a buffer tower; 91. a demister; 92. a blow-off pipe; 921. a blowoff valve.

Detailed Description

The present application is described in further detail below with reference to figures 2-3.

The embodiment of the application discloses a blast furnace diffused gas recycling and diffusing device. Referring to fig. 2, the recycling and diffusing device comprises a furnace body 1, a gas pipeline 2, a dust removal device 3, a pressure reducing valve group 5, a gas pipe network 7 and an injection assembly 8.

One end of the gas pipeline 2 is connected to the top of the furnace body 1, the other end of the gas pipeline 2 is communicated with the gas pipe network 7, and the gas generated in the furnace body 1 is recycled into the gas pipe network 7 through the gas pipeline 2.

The dust removing device 3 and the pressure reducing valve group 5 are sequentially arranged in series in the direction away from the furnace body 1 on the gas pipeline 2, and respectively perform dust removal and pressure reduction treatment on the gas generated by the blast furnace.

The gas pipeline 2 is provided with an injection assembly 8. The eductor assembly 8 includes an external gas source 81 and an eductor 82. An air source pipeline 811 is arranged between the external air source 81 and the ejector 82, the external air source 81 is communicated with the ejector 82 through the air source pipeline 811, and an air valve 812 for controlling the opening and the closing of the pipeline is arranged on the air source pipeline 811.

The dust removing device 3 includes a rough dust remover 31 and a plurality of fine dust removers 32. The gas generated by the blast furnace sequentially passes through the rough dust collector 31 and the fine dust collector 32 in the gas pipeline 2 and then enters the gas pipe network 7, and the rough dust collector 31 and the fine dust collector 32 remove dust for the blast furnace gas for multiple times, so that the dust amount carried in the blast furnace gas is reduced to a certain extent, and the influence of the dust on the quality of the recovered gas is reduced as much as possible.

In the damping-down stage, the quality of the coal gas meets the recovery standard. After a worker opens the gas valve 812, high-pressure airflow is input into the gas pipeline from the external gas source 81 through the ejector 82, and the high-pressure airflow can generate negative pressure in the pipeline between the ejector 82 and the blast furnace in the flowing process, so that the blast furnace gas is attracted to directionally flow along with the high-pressure airflow until the blast furnace gas is fully recovered into the gas pipe network 7, and the problem of waste of the blast furnace gas caused by a processing mode that the quality of the gas meeting the recovery condition is directly diffused into the air by a processing device in the related technology in the damping-down process is solved.

In order to reduce the noise generated in the conveying process of the blast furnace gas, a silencer 6 is arranged on the gas pipeline 2 between the pressure reducing valve group 5 and the gas pipe network 7.

The gas of the external gas source 81 may be nitrogen gas, water vapor or other high-pressure gas of a blast furnace. Because vapor manufacturing cost is lower, and can further adsorb the dust in the coal gas after mixing with the coal gas and purify, this application adopts vapor as the gas in the external air supply 81.

A buffer tower 9 is arranged between the ejector 82 and the gas pipe network 7, the buffer tower 9 is arranged at the lowest point of the diffusing pipeline 4, and a demister 91 is arranged at the central position of the inner cavity of the buffer tower 9. An air inlet 823 is arranged at the lower part of the buffer tower 9, an air outlet 822 is arranged at the upper part of the buffer tower 9, and the air inlet 823 is communicated with the air outlet 822 and is evenly externally provided with a recovery pipeline 22.

In the buffer tower 9, under the guidance of high-pressure steam, the coal gas enters the inner cavity of the buffer tower 9 from the air inlet 823, enters the demister 91, returns to the external recovery pipeline 22 from the air outlet 822, and then enters the coal gas pipe network 7. The dust in vapor and coal gas has carried out more abundant mixture and has condensed and subsided, and defroster 91 can eliminate because adsorb the dust material in the coal gas or because the atomizing or liquefied vapor appears in the condensation active condensation phenomenon, has reduced the influence that steam caused in the pipeline to coal gas recovery to a certain extent.

The bottom of the buffer tower 9 is provided with a drain pipe 92, and the drain pipe 92 is provided with a drain valve 921. Part of liquid water in the pipeline flows and is accumulated in the buffer tower 9, and staff in the worksheet can discharge the liquid water in the buffer tower 9 through the drain pipe 92 after the damping down, so that the cleanness of the buffer tower 9 and the interior of the pipeline is ensured as far as possible.

The gas pipeline 2 comprises a conventional pipeline 21 and an external recovery pipeline 22. The furnace body 1 and the gas pipe network 7 are respectively communicated with two ends of a conventional pipeline 21, and the dust removing device 3 and the pressure reducing valve group 5 are sequentially arranged on the conventional pipeline 21 between the dust removing device 3 and the gas pipe network 7.

The two ends of the external recovery pipeline 22 are communicated with the conventional pipeline 21 between the furnace body 1 and the gas pipe network 7, an off-line valve bank 221 for controlling the external recovery pipeline 22 to open and close is installed on the external recovery pipeline 22, the injection assembly 8 is installed on the external recovery pipeline 22, and the injection assembly 8 is connected with the pressure reducing valve bank 5 in parallel.

The arrangement of the external recovery pipeline 22 reduces the difficulty degree of the conventional pipeline 21 in transformation as much as possible, improves the flexibility of the external recovery pipeline 22 in installation as much as possible, and avoids the situation that the site is not enough when various facilities on the external recovery pipeline 22 are installed in the installation.

The two groups of off-line valve sets 221 are arranged, and the two groups of off-line valve sets 221 are respectively installed at two ends of the external recovery pipeline 22. The worker can cut off the two sets of off-line valve sets 221, so that the external recovery pipeline 22 is completely disconnected from the conventional pipeline 21, and the blast furnace gas is recovered only through the conventional pipeline 21, thereby reducing the conveying distance of the gas in the gas pipeline 2 to a certain extent.

In order to ensure the blocking performance of the off-line valve set 221, the off-line valve set 221 includes a cut-off butterfly valve and a blind plate valve, and the blind plate valve is connected in series to one side of the cut-off butterfly valve, which is far away from the conventional pipeline 21.

The external recycling pipeline 22 is provided with a diffusing pipeline 4, and the diffusing pipeline 4 communicates the outside with the external recycling pipeline 22. The diffusing pipeline 4 is provided with a diffusing valve 41 for controlling the opening and closing of the diffusing pipeline 4, and the diffusing pipeline 4 and the external recovery pipeline 22 are communicated with the top end position of the buffer tower 9.

In the process of re-air, the quality of the coal gas does not meet the recovery standard. The staff opens the relief valve 41 after cutting off the pressure reducing valve group 5 and the off-line valve group 221 close to the gas pipe network 7 and opening the off-line valve group 221 far away from the gas pipe network 7, unqualified gas generated in the process of re-air can pass through the purification of the purification device and then be purified again through the demister 91, the dust content diffused into external gas in the process of re-air is reduced as far as possible, and therefore the pollution to the environment caused by the blast furnace gas in the process of diffusion is reduced.

Referring to fig. 3, the ejector 82 has a tubular structure, and ports at two ends of the ejector 82 are named as a gas source port 821 and a gas outlet port 822 respectively. An air inlet 823 is formed in the center of the upper side of the pipe wall of the ejector 82. The air source port 821 of the ejector 82 is communicated with an air source pipeline 811, and the air inlet 823 and the air outlet 822 of the ejector 82 are both communicated with the external recovery pipeline 22.

After valve 812 is opened, high pressure gas flows from gas supply port 821 to gas outlet port 822. Under the flow of the high-pressure gas flow, negative pressure is generated in the tube cavity at the position of the gas inlet 823, so that the gas flows from the gas inlet 823 to the gas outlet 822 directionally.

In order to ensure the connection sealing performance between the air supply pipeline 811 and the injector 82, the inner circumferential surface of the air supply port 821 is provided with a tapered surface, and the port of the air supply pipeline 811 is a tapered port adapted to the air supply port 821. The port of the air supply pipeline 811 is connected in the air supply port 821 through a screw thread, and a sealing ring for improving the sealing performance is further installed between the air supply pipeline 811 and the air supply port 821.

The end face of the gas source pipeline 811 extending into the ejector 82 is coaxially and fixedly connected with a flow stabilizing pipe 8111. Flow stabilizer 8111 is a cylindrical straight tube, and flow stabilizer 8111 extends to a position proximate to gas outlet 822. The flow stabilizing pipe 8111 can maintain the flow direction of the air flow passing through the tapered port to be horizontal to a certain extent, so that the direction of the high-pressure air flow sprayed out from the air source pipeline 811 is more stable.

In order to enhance the negative pressure effect generated when the high-pressure airflow passes through the ejector 82, an inner reducing pipe 824 is coaxially and fixedly connected to the inner wall of the position of the air outlet 822 of the ejector 82, chamfer structures are arranged at two ends of the inner reducing pipe 824, and the inner reducing pipe 824 is smoothly connected with the inner wall of the ejector 82 through the chamfer structures.

The application principle of the blast furnace diffused gas recovery and diffusion device is as follows:

during normal production of the blast furnace, the valves of the external recycling line 22 are all in a closed state. When the blast furnace is ready for damping down, the following steps are taken by the staff:

1. the off-line valve group 221 close to the gas pipe network 7 is opened in advance, and the recovery and diffusion device enters a preparation state.

2. After the blast furnace starts to enter a damping-down state, the air inlet amount in the gas pipeline 2 is gradually reduced, the air inlet pressure is gradually reduced, and the pressure reducing valve set 5 is fully opened after the air inlet pressure is reduced to a set value.

3. After the pressure reducing valve set 5 is fully opened, the air valve 812 is opened, the off-line valve set 221 far away from the gas pipe network 7 is opened, and the pressure reducing valve set 5 is closed. So that gas can only enter the gas network 7 through the external recovery line 22.

4. The blast furnace further reduces the air inlet quantity, the generation quantity of blast furnace gas is smaller than the quantity of gas entering the gas pipe network 7 by observing the change of the pressure at the top of the blast furnace, at the moment, the pressure at the top of the blast furnace is continuously reduced to micro positive pressure, and the blast furnace is completely shut down.

5. After the blast furnace is completely shut down, all off-line valve blocks 221 and air valves 812 are closed.

6. And (5) after the blast furnace damping down is finished, carrying out subsequent operation according to the conventional requirement of the blast furnace.

When the blast furnace is not in production, the valves of the recovery and diffusion device are all in a closed state. When the blast furnace is ready for reblowing, the working personnel adopt the following steps:

1. when the blast furnace determines to return air, before the blast furnace supplies air, the bleeding valve 41 and the off-line valve set 221 far away from the gas pipe network 7 are opened in advance, and the recovery and bleeding device enters a preparation state.

2. The blast furnace supplies air, the coal gas enters the buffer tower 9 along the external recovery pipeline 22 after passing through the dust removing device 3, and then is diffused to the outside from the diffusing pipeline 4.

3. With the operation of the blast furnace, the component detection of the blast furnace gas is qualified, after the recovery condition is met, the off-line valve group 221 close to the gas pipe network 7 is opened, the bleeding valve 41 is closed, and the gas enters the gas pipe network 7 through the external recovery pipeline 22 to be recovered.

4. The pressure reducing valve set 5 is gradually opened, and all the off-line valve sets 221 are closed, so that the external recovery pipeline 22 is in an off-line state. At the moment, the blast furnace gas with qualified quality enters the gas pipe network 7 through the conventional pipeline 21, and the gas generated by the blast furnace is recovered.

It should be noted that the recovery and dispersion device in the application is not only a flow for recording and operating coal gas according to a treatment mode in a damping-down process and a re-wind process, but also only takes the damping-down process as a representative situation that blast furnace coal gas with qualified quality is generated but air inlet pressure is insufficient; and the re-wind process is taken as a representative situation when the quality of the coal gas is unqualified.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

1. The utility model provides a blast furnace diffuses coal gas and retrieves diffusing device, includes furnace body (1), gas pipeline (2), dust collector (3), pressure reducing valve group (5) and gas pipe network (7), and furnace body (1) and gas pipe network (7) communicate respectively in the both ends of gas pipeline (2), and dust collector (3) and pressure reducing valve group (5) are laid in proper order on gas pipeline (2) between furnace body (1) and gas pipe network (7), its characterized in that: the blast furnace gas injection device is characterized by further comprising an injection assembly (8), wherein the injection assembly (8) comprises an external gas source (81) and an injector (82), the injector (82) is installed on the gas pipeline (2), the external gas source (81) is communicated with the injector (82), and the blast furnace gas is driven by the external gas source (81) to move directionally towards the gas pipe network (7).

2. The blast furnace diffused gas recovery and diffusion device according to claim 1, characterized in that: the gas in the external gas source (81) is selected from water vapor.

3. The blast furnace diffused gas recovery and diffusion device according to claim 2, characterized in that: a buffer tower (9) is arranged between the ejector (82) and the bleeding valve (41), and a demister (91) is arranged in an inner cavity of the buffer tower (9).

4. The blast furnace diffused gas recovery and diffusion device according to claim 3, characterized in that: a drain pipe (92) is arranged at the bottom of the buffer tower (9), and a drain valve (921) is arranged on the drain pipe (92).

5. The blast furnace diffused gas recovery and diffusion device according to claim 4, characterized in that: the coal gas pipeline (2) comprises a conventional pipeline (21) and an external recovery pipeline (22), the furnace body (1) and the coal gas pipeline network (7) are respectively communicated with two ends of the conventional pipeline (21), the dust removal device (3) and the pressure reduction valve bank (5) are sequentially arranged on the conventional pipeline (21) between the furnace body (1) and the coal gas pipeline network (7), two ends of the external recovery pipeline (22) are communicated with the conventional pipeline (21) between the dust removal device (3) and the coal gas pipeline network (7), an off-line valve bank (221) for controlling the external recovery pipeline (22) to be opened and closed is installed on the external recovery pipeline (22) in an injection mode, and the injection module (8) is connected with the pressure reduction valve bank (5) in parallel.

6. The blast furnace diffused gas recovery and diffusion device according to claim 5, characterized in that: the two groups of off-line valve banks (221) are respectively located at two ends of the external recovery pipeline (22).

7. The blast furnace diffused gas recovery and diffusion device according to claim 5, characterized in that: the off-line valve bank (221) comprises a cut-off butterfly valve and a blind plate valve which are connected in series.

8. The blast furnace diffused gas recovery and diffusion device according to claim 6, characterized in that: the external recovery pipeline (22) is provided with a diffusing pipeline (4), the diffusing pipeline (4) is provided with a diffusing valve (41) for controlling the opening and closing of the diffusing pipeline (4), and one end of the diffusing pipeline (4) is communicated with the gas pipeline (2) between the buffer tower (9) and the gas pipeline network (7).

9. The blast furnace diffused gas recovery and diffusion device according to claim 1, characterized in that: ejector (82) are the tubular structure, and the both ends mouth of pipe of ejector (82) is named as air supply mouth (821) and gas outlet (822) respectively, has seted up air inlet (823) on ejector (82) pipe wall, and air supply mouth (821) and air supply pipeline (811) intercommunication of ejector (82), air inlet (823) and gas outlet (822) of ejector (82) all communicate with external recovery pipeline (22), and coal gas flows to gas outlet (822) from air inlet (823) in ejector (82).

10. The blast furnace diffused gas recovery and diffusion device according to claim 9, characterized in that: the inner circumferential surface of the air supply port (821) is provided with a conical surface, and the port of the air supply pipeline (811) is a conical port matched with the air supply port (821).