Blast furnace gas safety diffusion device and operation method thereof

Abstract

The invention relates to a blast furnace gas safety diffusion device and an operation method thereof, and belongs to the technical field of metallurgical equipment and methods. According to the technical scheme, a combustion-supporting pipeline (1), a main diffusion pipeline (2), a nitrogen purging pipeline (3) and a diffusion tower body (4) are each provided with at least two branches which are arranged in parallel; the branch pipelines are respectively connected with corresponding diffusion tower bodies (4); the branch pipeline is provided with a control valve. The method has the beneficial effects that the problems of diffusion blow-off and flameout during main diffusion large-flow diffusion can be avoided, the blast furnace gas diffusion amount is effectively shunted, and the flow in a single main diffusion branch pipeline is reduced; the diffusion flow can be accurately adjusted, the pressure of a blast furnace gas pipe network can be controlled, and excessive diffusion is avoided; nitrogen purging is carried out after diffusion is finished, and the problems of residual gas and tempering of the pipeline after diffusion is finished are effectively solved.

Description

Technical Field

[0001] The present invention relates to a safe blow-off device for blast furnace gas and an operation method thereof, belonging to the technical field of metallurgical equipment and methods. Background Art

[0002] The comprehensive utilization rate of blast furnace gas in China is about 98.6%. Compared with the annual output base of nearly one trillion cubic meters, there is still a large amount of blast furnace gas being discharged. Currently, the main discharge form is to burn the blast furnace gas in the blow-off tower to consume CO in the blast furnace gas. Therefore, the blast furnace gas blow-off tower is an essential gas blow-off device in iron and steel enterprises, used to achieve gas blow-off in case of accidents or emergencies.

[0003] The calorific value of blast furnace gas is lower than that of converter gas and coke oven gas. Its main component is N2, with a content of about 50%, and the main combustible component is CO, with a content of about 22%. The flame is not easy to burn continuously.

[0004] When the blast furnace gas blow-off tower is put into operation, due to the impact of large flow and high pressure, the blow-off tower often has problems of flameout and extinguishing, resulting in excessive CO in the plant area, polluting the environment, endangering the safety of the surrounding population and causing environmental protection accidents. After the blow-off, there is still a large amount of blast furnace gas remaining in the blow-off tower body, which is likely to cause poisoning of maintenance personnel and backfire accidents.

[0005] The traditional blow-off tower uses a long flame for auxiliary combustion, resulting in a large amount of gas loss. Structurally, it fails to effectively divide the large-flow blow-off, and at the same time, it cannot implement precise control in the operation mode, resulting in frequent problems of flameout and extinguishing during the blow-off of blast furnace gas. After the blow-off, there is still residual gas in the pipeline, causing backfire problems and even threatening the safety of maintenance personnel.

[0006] Therefore, a new type of safe blow-off device for blast furnace gas and an operation method thereof are needed to solve the above technical problems. Summary of the Invention

[0007] The object of the present invention is to provide a safe blow-off device for blast furnace gas and an operation method thereof. Through the pre-ignition and stable combustion of the auxiliary combustion blast furnace gas, the problems of flameout and extinguishing during the large-flow blow-off of the main blow-off can be avoided, effectively solving the environmental protection problem caused by excessive CO in the plant area during the blow-off with extinguishing; through multiple auxiliary combustion branch pipes, main blow-off branch pipes and blow-off tower branches, the blow-off volume of blast furnace gas is effectively divided, reducing the flow rate in a single main blow-off branch pipe; by setting control valves on each main blow-off branch pipe, the blow-off flow rate can be precisely adjusted and the pressure of the blast furnace gas pipeline can be controlled to avoid excessive blow-off; by setting a nitrogen purging device, nitrogen purging is carried out after the blow-off, effectively solving the problems of residual gas and backfire in the pipeline after the blow-off, and effectively solving the above problems existing in the background art.

[0008] The technical solution of the present invention is: a blast furnace gas safety relief device, which includes a combustion-supporting pipeline, a main relief pipeline, a nitrogen purging pipeline, and a relief tower body. At least two branches are provided in parallel for each of the combustion-supporting pipeline, the main relief pipeline, the nitrogen purging pipeline, and the relief tower body; the first combustion-supporting branch pipeline, the first main relief branch pipeline, the first nitrogen purging branch pipeline, and their parallel and identically structured branch pipelines are respectively connected to their corresponding relief tower bodies; the first combustion-supporting branch pipeline, the first main relief branch pipeline, and the first nitrogen purging branch pipeline are provided with control valves.

[0009] A first manual butterfly valve for the combustion-supporting branch and a first pneumatic butterfly valve for the combustion-supporting branch are provided on the first combustion-supporting branch pipeline and are connected to the first relief tower branch; an electric butterfly valve I, an electric spectacle valve I, a pneumatic regulating valve I, a branch flowmeter I, a pneumatic quick cut-off valve I, and an expansion joint I are provided on the first main relief branch pipeline and are connected to the first relief tower branch; a first manual butterfly valve for the nitrogen purging branch and a first pneumatic butterfly valve for the nitrogen purging branch are provided on the first nitrogen purging branch pipeline and are connected to the first relief tower branch.

[0010] The diameters of the combustion-supporting pipeline, the main relief pipeline, and the nitrogen purging pipeline are different; the diameters of the first combustion-supporting branch pipeline, the first main relief branch pipeline, and the first nitrogen purging branch pipeline are different.

[0011] A flowmeter is provided on the main relief pipeline.

[0012] The first combustion-supporting branch pipeline is arranged in a straight line and is connected to the relief tower branch through the first manual butterfly valve for the combustion-supporting branch and the first pneumatic butterfly valve for the combustion-supporting branch; it also includes a second combustion-supporting branch pipeline and a third combustion-supporting branch pipeline. The structures and valve settings of the second combustion-supporting branch pipeline and the third combustion-supporting branch pipeline are the same as those of the first combustion-supporting branch pipeline and are respectively connected to the second relief tower branch and the third relief tower branch.

[0013] The first main relief branch pipeline is arranged in a straight line and is connected to the first relief tower branch through the electric butterfly valve I, the electric spectacle valve I, the pneumatic regulating valve I, the branch flowmeter I, the pneumatic quick cut-off valve I, and the expansion joint I; it also includes a second main relief branch pipeline and a third main relief branch pipeline. The structures and valve settings of the second main relief branch pipeline and the third main relief branch pipeline are the same as those of the first main relief branch pipeline and are respectively connected to the second relief tower branch and the third relief tower branch.

[0014] The first nitrogen purging branch pipeline is arranged in a straight line and is connected to the first relief tower branch through the first manual butterfly valve for the nitrogen purging branch and the first pneumatic butterfly valve for the nitrogen purging branch; it also includes a second nitrogen purging branch pipeline and a third nitrogen purging branch pipeline. The structures and valve settings of the second nitrogen purging branch pipeline and the third nitrogen purging branch pipeline are the same as those of the first nitrogen purging branch pipeline and are respectively connected to the second relief tower branch and the third relief tower branch.

[0015] A method for operating a safety relief device for blast furnace gas, comprising the following steps: (1) Set three values for the relief pressure of the blast furnace gas pipeline network, corresponding to the lower limit value, the median value, and the upper limit value respectively; (2) When the pressure of the blast furnace gas pipeline network is higher than the lower limit value and lower than the median value, the combustion-supporting branch pneumatic butterfly valve I on the combustion-supporting branch pipeline I opens, the relief tower branch I is put into operation and the combustion-supporting blast furnace gas is ignited; after the combustion-supporting blast furnace gas is ignited, the pneumatic regulating valve I and the pneumatic quick cut-off valve I on the main relief branch pipeline I open, and during this period, the opening degree of the pneumatic regulating valve I is adjusted according to the pressure of the blast furnace gas pipeline network for precise control of the pipeline network pressure; (3) When the pressure of the blast furnace gas pipeline network reaches the median value and is lower than the upper limit value, the combustion-supporting branch pneumatic butterfly valve I on the combustion-supporting branch pipeline I opens, the combustion-supporting branch pneumatic butterfly valve II on the combustion-supporting branch pipeline II opens, the relief tower branch I and the relief tower branch II are put into operation and the combustion-supporting blast furnace gas is ignited; after the combustion-supporting blast furnace gas is ignited, the pneumatic regulating valve I and the pneumatic quick cut-off valve I on the main relief branch pipeline I open, the pneumatic regulating valve II and the pneumatic quick cut-off valve II on the main relief branch pipeline II open, and during this period, the opening degrees of the pneumatic regulating valve I and the pneumatic regulating valve II are adjusted according to the pressure of the blast furnace gas pipeline network for precise control of the pipeline network pressure; (4) When the pressure of the blast furnace gas pipeline network reaches the upper limit value, the combustion-supporting branch pneumatic butterfly valve I on the combustion-supporting branch pipeline I opens, the combustion-supporting branch pneumatic butterfly valve II on the combustion-supporting branch pipeline II opens, the combustion-supporting branch pneumatic butterfly valve III on the combustion-supporting branch pipeline III opens, the relief tower branch I, the relief tower branch II, and the relief tower branch III are put into operation and the combustion-supporting blast furnace gas is ignited; after the combustion-supporting blast furnace gas is ignited, the pneumatic regulating valve I and the pneumatic quick cut-off valve I on the main relief branch pipeline I open, the pneumatic regulating valve II and the pneumatic quick cut-off valve II on the main relief branch pipeline II open, the pneumatic regulating valve III and the pneumatic quick cut-off valve III on the main relief branch pipeline III open, and during this period, the opening degrees of the pneumatic regulating valve I, the pneumatic regulating valve II, and the pneumatic regulating valve III are adjusted according to the pressure of the blast furnace gas pipeline network for precise control of the pipeline network pressure; (5) After the relief is completed, that is, when the pressure of the blast furnace gas pipeline network is lower than the lower limit value, according to the situation of the relief tower branch I, the relief tower branch II, and the relief tower branch III that have been put into operation, the nitrogen purge branch pneumatic butterfly valve I on the nitrogen purge branch pipeline I, the nitrogen purge branch pneumatic butterfly valve II on the nitrogen purge branch pipeline II, and the nitrogen purge branch pneumatic butterfly valve III on the nitrogen purge branch pipeline III are opened to purge the residual gas in the relief tower branch I, the relief tower branch II, and the relief tower branch III, and after the flame goes out, the nitrogen purge branch pneumatic butterfly valve I, the nitrogen purge branch pneumatic butterfly valve II, and the nitrogen purge branch pneumatic butterfly valve III that have been put into operation are closed.

[0016] The diameters of the combustion-supporting pipeline, the main relief pipeline, and the nitrogen purge pipeline are different; the diameters of the combustion-supporting branch pipeline I, the main relief branch pipeline I, and the nitrogen purge branch pipeline I are different.

[0017] A flowmeter is provided on the main relief pipeline.

[0018] The beneficial effects of the present invention are as follows: Through the pre-ignition and stable combustion of the combustion-supporting blast furnace gas, the problems of flameout and extinction during large-flow relief of the main relief can be avoided, effectively solving the environmental protection problem caused by excessive CO in the plant area during extinguishing and discharging; Through multiple combustion-supporting branch pipelines, main relief branch pipelines, and relief tower branches, the discharge volume of blast furnace gas is effectively diverted, reducing the flow rate in a single main relief branch pipeline; By setting control valves on each main relief branch pipeline, the relief flow rate can be precisely adjusted and the pressure of the blast furnace gas pipeline network can be controlled to avoid excessive discharge; By setting a nitrogen purging device, nitrogen purging is carried out after the discharge is completed, effectively solving the problems of residual gas and backfire in the pipeline after the discharge is completed. Description of the Drawings

[0019] Figure 1 is a schematic diagram of the overall structure of the present invention; In the figure: combustion-supporting pipeline 1, combustion-supporting branch pipeline one 11, combustion-supporting branch manual butterfly valve one 111, combustion-supporting branch pneumatic butterfly valve one 112, combustion-supporting branch pipeline two 12, combustion-supporting branch manual butterfly valve two 121, combustion-supporting branch pneumatic butterfly valve two 122, combustion-supporting branch pipeline three 13, combustion-supporting branch manual butterfly valve three 131, combustion-supporting branch pneumatic butterfly valve three 132, main relief pipeline 2, main relief branch pipeline one 21, electric butterfly valve one 211, electric spectacle valve one 212, pneumatic regulating valve one 213, branch flowmeter one 214, pneumatic quick cut-off valve one 215, expansion joint one 216, main relief branch pipeline two 22, electric butterfly valve two 221, electric spectacle valve two 222, pneumatic regulating valve two 223, branch flowmeter two 224, pneumatic quick cut-off valve two 225, expansion joint two 226, main relief branch pipeline three 23, electric butterfly valve three 231, electric spectacle valve three 232, pneumatic regulating valve three 233, branch flowmeter three 234, pneumatic quick cut-off valve three 235, expansion joint three 236, flowmeter 24, nitrogen purging pipeline 3, nitrogen purging branch pipeline one 31, nitrogen purging branch manual butterfly valve one 311, nitrogen purging branch pneumatic butterfly valve one 312, nitrogen purging branch pipeline two 32, nitrogen purging branch manual butterfly valve two 321, nitrogen purging branch pneumatic butterfly valve two 322, nitrogen purging branch pipeline three 33, nitrogen purging branch manual butterfly valve three 331, nitrogen purging branch pneumatic butterfly valve three 332, relief tower body 4, relief tower branch one 41, relief tower branch two 42, relief tower branch three 43. Detailed Embodiments

[0020] In order to make the objectives, technical solutions, and advantages of the invention implementation cases clearer, the following will, in combination with the accompanying drawings in the implementation cases, clearly and completely describe the technical solutions in the implementation cases of the present invention. Obviously, the described implementation cases are a small part of the implementation cases of the present invention, rather than all of the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0021] A blast furnace gas safety relief device includes a combustion-supporting pipeline 1, a main relief pipeline 2, a nitrogen purging pipeline 3, and a relief tower body 4. The combustion-supporting pipeline 1, the main relief pipeline 2, the nitrogen purging pipeline 3, and the relief tower body 4 each have at least two branches arranged in parallel; the first combustion-supporting branch pipeline 11, the first main relief branch pipeline 21, and the first nitrogen purging branch pipeline 31 and their parallel and identically structured branch pipelines are respectively connected to their corresponding relief tower body 4; the first combustion-supporting branch pipeline 11, the first main relief branch pipeline 21, and the first nitrogen purging branch pipeline 31 are provided with control valves.

[0022] The first combustion-supporting branch pipeline 11 is provided with a first manual butterfly valve 111 for the combustion-supporting branch and a first pneumatic butterfly valve 112 for the combustion-supporting branch and is connected to the first relief tower branch 41; the first main relief branch pipeline 21 is provided with an electric butterfly valve 211, an electric spectacle valve 212, a pneumatic regulating valve 213, a first branch flowmeter 214, a first pneumatic quick cut-off valve 215, and an expansion joint 216 and is connected to the first relief tower branch 41; the first nitrogen purging branch pipeline 31 is provided with a first manual butterfly valve 311 for the nitrogen purging branch and a first pneumatic butterfly valve 312 for the nitrogen purging branch and is connected to the first relief tower branch 41.

[0023] The diameters of the combustion-supporting pipeline 1, the main relief pipeline 2, and the nitrogen purging pipeline 3 are different; the diameters of the first combustion-supporting branch pipeline 11, the first main relief branch pipeline 21, and the first nitrogen purging branch pipeline 31 are different.

[0024] The main relief pipeline 2 is provided with a flowmeter 24.

[0025] The first combustion-supporting branch pipeline 11 is arranged in a straight line and is connected to the relief tower branch 41 through the first manual butterfly valve 111 for the combustion-supporting branch and the first pneumatic butterfly valve 112 for the combustion-supporting branch; it also includes a second combustion-supporting branch pipeline 12 and a third combustion-supporting branch pipeline 13. The structures and valve settings of the second combustion-supporting branch pipeline 12 and the third combustion-supporting branch pipeline 13 are the same as those of the first combustion-supporting branch pipeline 11 and are respectively connected to the second relief tower branch 42 and the third relief tower branch 43.

[0026] The main discharge branch pipe 1-21 is arranged in a straight line and is connected to the discharge tower branch 1-41 through an electric butterfly valve 1-211, an electric spectacle valve 1-212, a pneumatic regulating valve 1-213, a branch flowmeter 1-214, a pneumatic quick cut-off valve 1-215 and an expansion joint 1-216; it also includes a main discharge branch pipe 2-22 and a main discharge branch pipe 3-23. The structures and valve settings of the main discharge branch pipe 2-22 and the main discharge branch pipe 3-23 are the same as those of the main discharge branch pipe 1-21 and are respectively connected to the discharge tower branch 2-42 and the discharge tower branch 3-43 correspondingly.

[0027] The nitrogen purging branch pipe 1-31 is arranged in a straight line and is connected to the discharge tower branch 1-41 through a nitrogen purging branch manual butterfly valve 1-311 and a nitrogen purging branch pneumatic butterfly valve 1-312; it also includes a nitrogen purging branch pipe 2-32 and a nitrogen purging branch pipe 3-33. The structures and valve settings of the nitrogen purging branch pipe 2-32 and the nitrogen purging branch pipe 3-33 are the same as those of the nitrogen purging branch pipe 1-31 and are respectively connected to the discharge tower branch 2-42 and the discharge tower branch 3-43 correspondingly.

[0028] A method for operating a blast furnace gas safety discharge device includes the following steps: (1) Set three values for the discharge pressure of the blast furnace gas pipeline network, corresponding to the lower limit value, the median value, and the upper limit value respectively; (2) When the blast furnace gas pipeline network pressure is higher than the lower limit value and lower than the median value, the combustion-supporting branch pneumatic butterfly valve 1 on the combustion-supporting branch pipe 1 opens, the discharge tower branch 1 is put into operation and the combustion-supporting blast furnace gas is ignited; after the combustion-supporting blast furnace gas is ignited, the pneumatic regulating valve 1 and the pneumatic quick cut-off valve 1 on the main discharge branch pipe 1 open, and during this period, the opening degree of the pneumatic regulating valve 1 is adjusted according to the blast furnace gas pipeline network pressure for precise control of the pipeline network pressure; (3) When the blast furnace gas pipeline network pressure reaches the median value and is lower than the upper limit value, the combustion-supporting branch pneumatic butterfly valve 1 on the combustion-supporting branch pipe 1 opens, the combustion-supporting branch pneumatic butterfly valve 2 on the combustion-supporting branch pipe 2 opens, the discharge tower branch 1 and the discharge tower branch 2 are put into operation and the combustion-supporting blast furnace gas is ignited; after the combustion-supporting blast furnace gas is ignited, the pneumatic regulating valve 1 and the pneumatic quick cut-off valve 1 on the main discharge branch pipe 1 open, the pneumatic regulating valve 2 and the pneumatic quick cut-off valve 2 on the main discharge branch pipe 2 open, and during this period, the opening degrees of the pneumatic regulating valve 1 and the pneumatic regulating valve 2 are adjusted according to the blast furnace gas pipeline network pressure for precise control of the pipeline network pressure; (4)When the pressure of the blast furnace gas pipeline network reaches the upper limit value, the combustion-supporting pneumatic butterfly valve 1 on the first combustion-supporting branch pipeline opens, the combustion-supporting pneumatic butterfly valve 2 on the second combustion-supporting branch pipeline opens, the combustion-supporting pneumatic butterfly valve 3 on the third combustion-supporting branch pipeline opens, the first, second, and third blast furnace gas blow-off tower branches are put into operation and the combustion-supporting blast furnace gas is ignited; after the combustion-supporting blast furnace gas is ignited, the pneumatic regulating valve 1 and the pneumatic quick cut-off valve 1 on the first main blow-off branch pipeline open, the pneumatic regulating valve 2 and the pneumatic quick cut-off valve 2 on the second main blow-off branch pipeline open, the pneumatic regulating valve 3 and the pneumatic quick cut-off valve 3 on the third main blow-off branch pipeline open, and during this period, the opening degrees of the pneumatic regulating valve 1, the pneumatic regulating valve 2, and the pneumatic regulating valve 3 are adjusted according to the pressure of the blast furnace gas pipeline network to precisely control the pipeline network pressure; (5)After the blow-off is completed, that is, when the pressure of the blast furnace gas pipeline network is lower than the lower limit value, according to the situation of the first, second, and third blast furnace gas blow-off tower branches that have been put into operation, the nitrogen purge branch pneumatic butterfly valve 1 on the first nitrogen purge branch pipeline, the nitrogen purge branch pneumatic butterfly valve 2 on the second nitrogen purge branch pipeline, and the nitrogen purge branch pneumatic butterfly valve 3 on the third nitrogen purge branch pipeline are opened to purge the residual gas in the first, second, and third blast furnace gas blow-off tower branches, and after the flame goes out, the nitrogen purge branch pneumatic butterfly valve 1, the nitrogen purge branch pneumatic butterfly valve 2, and the nitrogen purge branch pneumatic butterfly valve 3 that have been put into operation are closed.

[0029] The diameters of the combustion-supporting pipeline, the main blow-off pipeline, and the nitrogen purge pipeline are different; the diameters of the first combustion-supporting branch pipeline, the first main blow-off branch pipeline, and the first nitrogen purge branch pipeline are different.

[0030] A flowmeter is provided on the main blow-off pipeline.

[0031] Through the stable combustion of the combustion-supporting blast furnace gas and the shunting effect of the main blow-off pipelines arranged in parallel, the problems of blow-off flashback and flameout during large-flow blow-off of the main blow-off can be avoided, and the environmental protection problem caused by excessive CO in the plant area during blow-off with flameout is effectively solved. At the same time, control valves are provided on each main blow-off branch pipeline, which can precisely adjust the blow-off flow rate and control the pressure of the blast furnace gas pipeline network to avoid excessive blow-off.

[0032] By setting up a nitrogen purge device, the problems of residual gas and backfire in the pipeline after blow-off are effectively solved.

[0033] In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0034] Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A blast furnace gas safety release device, characterized in that: The invention comprises a combustion-supporting pipeline (1), a main emission pipeline (2), a nitrogen purge pipeline (3) and a emission tower body (4), wherein the combustion-supporting pipeline (1), the main emission pipeline (2), the nitrogen purge pipeline (3) and the emission tower body (4) are each provided with at least two branches arranged in parallel; a combustion-supporting branch pipeline (11), a main emission branch pipeline (21) and a nitrogen purge branch pipeline (31) and branch pipelines arranged in parallel and having the same structure are respectively connected to their corresponding emission tower bodies (4); and a combustion-supporting branch pipeline (11), a main emission branch pipeline (21) and a nitrogen purge branch pipeline (31) are provided with control valves.

2. A blast furnace gas safety release device according to claim 1, characterized in that: The combustion-supporting branch pipeline (11) is provided with a combustion-supporting branch manual butterfly valve (111) and a combustion-supporting branch pneumatic butterfly valve (112), and is connected to a discharge tower branch (41); the main discharge branch pipeline (21) is provided with an electric butterfly valve (211), an electric eyeglass valve (212), a pneumatic regulating valve (213), a branch flow meter (214), a pneumatic quick-cut valve (215) and an expansion joint (216), and is connected to a discharge tower branch (41); the nitrogen purge branch pipeline (31) is provided with a nitrogen purge branch manual butterfly valve (311) and a nitrogen purge branch pneumatic butterfly valve (312), and is connected to a discharge tower branch (41).

3. A blast furnace gas safety release device according to claim 1, characterized in that: The diameters of the combustion-supporting pipeline (1), the main emission pipeline (2) and the nitrogen purge pipeline (3) are different; the diameters of the combustion-supporting branch pipeline 1 (11), the main emission branch pipeline 1 (21) and the nitrogen purge branch pipeline 1 (31) are different.

4. A blast furnace gas safety release device according to claim 1, characterized in that: The main relief pipe (2) is provided with a flow meter (24).

5. A blast furnace gas safety release device according to claim 2, characterized in that: The combustion-supporting branch pipe 1 (11) is arranged in a straight line and is connected to the discharge tower branch (41) through a combustion-supporting branch manual butterfly valve 1 (111) and a combustion-supporting branch pneumatic butterfly valve 1 (112); it also includes a combustion-supporting branch pipe 2 (12) and a combustion-supporting branch pipe 3 (13). The structures and valve settings of the combustion-supporting branch pipe 2 (12) and the combustion-supporting branch pipe 3 (13) are the same as those of the combustion-supporting branch pipe 1 (11) and are respectively connected to the discharge tower branch 2 (42) and the discharge tower branch 3 (43).

6. A blast furnace gas safety release device according to claim 2, characterized in that: The main discharge branch pipeline 1 (21) is arranged in a straight line and is connected to the discharge tower branch 1 (41) through an electric butterfly valve 1 (211), an electric glasses valve 1 (212), a pneumatic regulating valve 1 (213), a branch flow meter 1 (214), a pneumatic quick-cut valve 1 (215) and an expansion joint 1 (216); it also includes a main discharge branch pipeline 2 (22) and a main discharge branch pipeline 3 (23). The structures and valve settings of the main discharge branch pipeline 2 (22) and the main discharge branch pipeline 3 (23) are the same as those of the main discharge branch pipeline 1 (21) and are respectively connected to the discharge tower branch 2 (42) and the discharge tower branch 3 (43).

7. A blast furnace gas safety release device according to claim 2, characterized in that: The nitrogen purge branch pipeline 1 (31) is arranged in a straight line and is connected to the discharge tower branch 1 (41) through a nitrogen purge branch manual butterfly valve 1 (311) and a nitrogen purge branch pneumatic butterfly valve 1 (312); it also includes a nitrogen purge branch pipeline 2 (32) and a nitrogen purge branch pipeline 3 (33). The structure and valve arrangement of the nitrogen purge branch pipeline 2 (32) and the nitrogen purge branch pipeline 3 (33) are the same as those of the nitrogen purge branch pipeline 1 (31) and are respectively connected to the discharge tower branch 2 (42) and the discharge tower branch 3 (43).

8. A method for operating a blast furnace gas safety release device, characterized in that The following steps are involved: (1) The blast furnace gas network release pressure is set to three values, corresponding to the lower limit, median value and upper limit respectively; (2) When the blast furnace gas network pressure is higher than the lower limit and lower than the median value, the combustion branch pneumatic butterfly valve 1 on the combustion branch pipeline 1 is opened, the venting tower branch 1 is put into operation and the combustion blast furnace gas is ignited; after the combustion blast furnace gas is ignited, the pneumatic regulating valve 1 and the pneumatic quick-cut valve 1 on the main venting branch pipeline 1 are opened, and during this period, the opening of the pneumatic regulating valve 1 is adjusted according to the blast furnace gas network pressure to accurately control the network pressure; (3) When the blast furnace gas network pressure reaches the median value and is lower than the upper limit value, the combustion branch pneumatic butterfly valve 1 on the combustion branch pipeline 1 is opened, the combustion branch pneumatic butterfly valve 2 on the combustion branch pipeline 2 is opened, the venting tower branch 1 and the venting tower branch 2 are put into operation and the combustion blast furnace gas is ignited; after the combustion blast furnace gas is ignited, the pneumatic regulating valve 1 and the pneumatic quick-cut valve 1 on the main venting branch pipeline 1 are opened, and the pneumatic regulating valve 2 and the pneumatic quick-cut valve 2 on the main venting branch pipeline 2 are opened. During this period, the opening of the pneumatic regulating valve 1 and the pneumatic regulating valve 2 are adjusted according to the blast furnace gas network pressure to accurately control the network pressure; (4) When the blast furnace gas network pressure reaches the upper limit, the combustion branch pneumatic butterfly valve 1 on the combustion branch pipe 1 is opened, the combustion branch pneumatic butterfly valve 2 on the combustion branch pipe 2 is opened, and the combustion branch pneumatic butterfly valve 3 on the combustion branch pipe 3 is opened, and the venting tower branch 1, venting tower branch 2 and venting tower branch 3 are put into operation and ignite the combustion blast furnace gas; after the combustion blast furnace gas is ignited, the pneumatic regulating valve 1 and the pneumatic quick-cut valve 1 on the main venting branch pipe 1 are opened, the pneumatic regulating valve 2 and the pneumatic quick-cut valve 2 on the main venting branch pipe 2 are opened, and the pneumatic regulating valve 3 and the pneumatic quick-cut valve 3 on the main venting branch pipe 3 are opened. During this period, the openings of the pneumatic regulating valve 1, the pneumatic regulating valve 2 and the pneumatic regulating valve 3 are adjusted according to the blast furnace gas network pressure to accurately control the network pressure; (5) After the release is completed, that is, when the pressure of the blast furnace gas pipeline network is lower than the lower limit, according to the conditions of the release tower branch 1, release tower branch 2 and release tower branch 3 that have been put into operation, open the nitrogen purge branch pneumatic butterfly valve 1 on the nitrogen purge branch pipeline 1, the nitrogen purge branch pneumatic butterfly valve 2 on the nitrogen purge branch pipeline 2 and the nitrogen purge branch pneumatic butterfly valve 3 on the nitrogen purge branch pipeline 3 to purge the residual gas in the release tower branch 1, release tower branch 2 and release tower branch 3. After the flame is extinguished, close the nitrogen purge branch pneumatic butterfly valve 1, nitrogen purge branch pneumatic butterfly valve 2 and nitrogen purge branch pneumatic butterfly valve 3 that have been put into operation.

9. The method for operating a blast furnace gas safety release device according to claim 8, characterized in that: The diameters of the combustion-supporting pipeline, the main emission pipeline and the nitrogen purge pipeline are different; the diameters of the combustion-supporting branch pipeline 1, the main emission branch pipeline 1 and the nitrogen purge branch pipeline 1 are different.

10. The method for operating a blast furnace gas safety release device according to claim 8, characterized in that: A flow meter is provided on the main venting pipeline.

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