A cascade ejector recovery device for blast furnace shutdown venting gas

Abstract

This application relates to a cascade ejector recovery device for blast furnace shutdown venting gas, belonging to the field of blast furnace ironmaking technology. It includes a blast furnace, a gas transmission pipe, a high-pressure clean gas pipe, a low-pressure clean gas pipe, and a gas recovery network. A cascade ejector recovery device is installed between the high-pressure and low-pressure clean gas pipes. The inlet of the first ejector pipe is connected to the outlet of the high-pressure clean gas pipe, and the inlet of the second ejector pipe is connected to both the outlet of the first ejector pipe and the outlet of the high-pressure clean gas pipe. The cascade ejector recovery device also includes a high-pressure gas source assembly. Under the injection of high-pressure gas, a negative pressure is formed in the first ejector pipe for gas recovery. The mixed gas in the first ejector pipe serves as the working gas for the second ejector pipe, allowing a portion of the gas from the high-pressure clean gas pipe to enter the second ejector pipe for recovery. This satisfies the need for blast furnace shutdown venting gas recovery while simultaneously saving on high-pressure gas source consumption.

Description

Technical Field

[0001] This application relates to the field of blast furnace ironmaking technology, and in particular to a cascade ejector recovery device for blast furnace shutdown venting gas. Background Technology

[0002] Blast furnace shutdown refers to the temporary cessation of air supply to the blast furnace for maintenance work, such as equipment replacement or blast furnace repair. During blast furnace shutdown, a byproduct called blast furnace gas is generated. Blast furnace gas contains combustible gases such as carbon monoxide, hydrogen, and methane, which can be utilized. Therefore, the gas generated during blast furnace shutdown needs to be recovered and treated.

[0003] Similar existing blast furnace gas recovery systems mainly involve installing ejectors on the blast furnace gas pipeline. By supplying high-pressure gas into the ejectors to create negative pressure, the low-pressure gas in the blast furnace is transported to the gas pipeline network, thus completing the gas recovery.

[0004] Because blast furnace shutdown gas has the characteristics of high pressure and easy recovery when the flow rate is large, and low pressure and difficult recovery when the flow rate is small, the recovery difficulty of blast furnace shutdown gas varies with different flow rates and pressures. Therefore, when using conventional ejectors for recovery, there are disadvantages such as large consumption of high-pressure gas and difficulty for enterprises to provide the corresponding gas source. Summary of the Invention

[0005] To address the varying recovery difficulties of blast furnace shutdown gas under different flow and pressure variations, and to reduce the consumption of high-pressure gas sources during blast furnace shutdown gas recovery, this application provides a cascade ejector recovery device for blast furnace shutdown vent gas.

[0006] This application provides a cascade ejector recovery device for blast furnace shutdown venting gas, which adopts the following technical solution:

[0007] A cascade ejector recovery device for blast furnace shutdown venting gas includes a blast furnace, a gas transmission pipe, a high-pressure clean gas pipe, a low-pressure clean gas pipe, and a gas recovery network. One end of the gas transmission pipe is connected to the blast furnace, and the other end is connected to the high-pressure clean gas pipe. The low-pressure clean gas pipe is connected to the gas recovery network.

[0008] A cascade ejector recovery device is installed between the high-pressure clean gas pipe and the low-pressure clean gas pipe. The cascade ejector recovery device includes a first ejector pipe and a second ejector pipe, wherein the diameter of the second ejector pipe is larger than that of the first ejector pipe. The inlet of the first ejector pipe is connected to the outlet of the high-pressure clean gas pipe, and the inlet of the second ejector pipe is connected to both the outlet of the first ejector pipe and the outlet of the high-pressure clean gas pipe. The outlet of the second ejector pipe is connected to the inlet of the low-pressure clean gas pipe. The cascade ejector recovery device also includes a high-pressure gas source assembly for providing initial ejection power to the first ejector pipe.

[0009] By adopting the above technical solution, when the blast furnace is shut down, the high-pressure gas source assembly operates, blowing high-pressure gas into the first ejector tube. At this time, the shut-down gas is transported to the first and second ejector tubes through the high-pressure clean gas pipe. Under the jet action of the high-pressure gas, a negative pressure is formed in the first ejector tube for gas recovery. The recovered gas mixes with the high-pressure gas and enters the input port of the second ejector tube from the output port of the first ejector tube. This allows the mixed gas in the first ejector tube to serve as the working gas for the second ejector tube, creating a negative pressure in the second ejector tube. This allows a portion of the gas to enter the second ejector tube from the high-pressure clean gas pipe for recovery. This satisfies the need for blast furnace shutdown vented gas recovery while simultaneously saving on the consumption of the high-pressure gas source.

[0010] Furthermore, the inlet of the first ejector tube is connected to a recovered gas inlet pipe, and a first connecting pipe is connected between the recovered gas inlet pipe and the high-pressure clean gas pipe. The outlet of the second ejector tube is connected to a second connecting pipe between the outlet of the second ejector tube and the low-pressure clean gas pipe. Gas valve assemblies are installed on both the first connecting pipe and the second connecting pipe.

[0011] Furthermore, a bypass pipe is connected to the side wall of the recovered gas inlet pipe, and the bypass pipe is connected to the inlet of the second ejector pipe.

[0012] By adopting the above technical solution and setting a bypass pipe, the first ejector pipe and the second ejector pipe can work independently, which makes it more convenient to install the first ejector pipe, the second ejector pipe and other pipes, and also makes subsequent maintenance more convenient.

[0013] Furthermore, an on / off valve is provided on the bypass pipe.

[0014] By adopting the above technical solution, as the blast furnace shutdown process progresses, the flow rate and pressure of the blast furnace gas decrease, gradually increasing the difficulty of gas recovery. When the negative pressure generated by the second ejector tube cannot meet the requirements for gas recovery, the on / off valve on the bypass pipe automatically closes. At this time, the shut-off gas relies on the first ejector tube for recovery. Because the high-pressure gas has a higher velocity when ejected, the first ejector tube can generate a larger negative pressure, meeting the recovery needs in the later stages of the blast furnace shutdown, until the gas pressure inside the blast furnace drops to the set value, at which point the blast furnace can be shut down normally, and the entire recovery process ends.

[0015] Furthermore, the first ejector tube is inserted inside the second ejector tube, the second ejector tube is connected to the first connecting pipe, and there is a gap between the pipe wall of the recovered gas inlet pipe and the inner wall of the second ejector tube.

[0016] Furthermore, the high-pressure gas source assembly includes a high-pressure working gas source, a high-pressure gas supply pipe, and a high-pressure gas nozzle. One end of the high-pressure gas supply pipe passes through the wall of the first ejector tube and extends into the first ejector tube. The high-pressure gas nozzle is located at the end of the high-pressure gas supply pipe located inside the first ejector tube. The input end of the high-pressure gas supply pipe is connected to the high-pressure working gas source. A gas shut-off valve is provided on the high-pressure gas supply pipe.

[0017] Furthermore, the high-pressure working gas source is a high-pressure coal gas source, a nitrogen source, or a steam source.

[0018] Furthermore, a pressure buffer tank is installed between the cascade ejector recovery device and the gas recovery pipeline network.

[0019] Furthermore, the high-pressure working gas source is a steam source, and the pressure buffer tank is equipped with a spray system for cooling the steam.

[0020] Furthermore, at least two sets of the cascade ejector recovery devices are arranged in parallel.

[0021] In summary, this application includes at least one of the following beneficial technical effects:

[0022] 1. When the blast furnace is shut down, the high-pressure gas source assembly operates, blowing high-pressure gas into the first ejector tube. At this time, the shut-down gas is transported to the first and second ejector tubes through the high-pressure clean gas pipe. Under the jet action of the high-pressure gas, a negative pressure is formed in the first ejector tube for gas recovery. The recovered gas mixes with the high-pressure gas and enters the input of the second ejector tube from the output port of the first ejector tube. This makes the mixed gas in the first ejector tube the working gas of the second ejector tube. A negative pressure is formed in the second ejector tube, causing a portion of the gas to enter the second ejector tube from the high-pressure clean gas pipe for recovery. This satisfies the need for blast furnace shutdown vented gas recovery while saving the consumption of high-pressure gas source.

[0023] 2. As the blast furnace shutdown process progresses, the flow rate and pressure of the blast furnace gas decrease, gradually increasing the difficulty of gas recovery. When the negative pressure generated by the second ejector tube is insufficient to meet the gas recovery requirements, the on / off valve on the bypass pipe automatically closes. At this point, the shut-off gas is recovered via the first ejector tube. Because the high-pressure gas has a higher velocity when ejected, the first ejector tube can generate a greater negative pressure, meeting the recovery needs in the later stages of the blast furnace shutdown, until the gas pressure inside the blast furnace drops to the set value. Then, the blast furnace can be shut down normally, and the entire recovery process ends. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this application;

[0025] Figure 2 This is a partial structural schematic diagram of Embodiment 1 of this application;

[0026] Figure 3 This is a schematic diagram of the structure of the cascade ejector recovery device, which is the main feature of Embodiment 1 of this application.

[0027] Figure 4 This is a schematic diagram of the structure of Embodiment 3 of this application;

[0028] Figure 5 This is a structural schematic diagram of Embodiment 4 of this application;

[0029] Figure 6 This is a structural schematic diagram of Embodiment 4 of this application.

[0030] Explanation of reference numerals in the attached drawings: 1. Blast furnace; 21. Gas riser pipe; 22. Gas downcomer pipe; 23. Primary dust collector; 24. Coarse gas pipe; 25. Secondary dust collector; 31. High-pressure clean gas pipe; 311. First connecting pipe; 32. Low-pressure clean gas pipe; 321. Second connecting pipe; 33. Gas valve assembly; 4. Gas recovery pipeline network; 5. Cascade ejector recovery device; 51. First ejector pipe; 511. Recovered gas inlet pipe; 52. Second ejector pipe; 53. Bypass pipe; 531. On / off valve; 61. Energy recovery mechanism; 62. Pressure reducing valve assembly; 7. High-pressure gas source assembly; 71. High-pressure working gas source; 72. High-pressure gas supply pipe; 721. Gas shut-off valve; 73. High-pressure gas nozzle; 8. Pressure buffer tank. Detailed Implementation

[0031] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.

[0032] Example 1

[0033] This application discloses a cascade ejector recovery device for blast furnace shutdown venting gas.

[0034] Reference Figure 1 A cascade ejector recovery device for blast furnace shutdown venting gas includes a blast furnace 1, a gas transmission pipe, a high-pressure clean gas pipe 31, a low-pressure clean gas pipe 32, and a gas recovery network 4. One end of the gas transmission pipe is connected to the blast furnace 1, and the other end is connected to the high-pressure clean gas pipe 31. The low-pressure clean gas pipe 32 is connected to the gas recovery network 4. A cascade ejector recovery device 5 is installed between the high-pressure clean gas pipe 31 and the low-pressure clean gas pipe 32.

[0035] Reference Figure 2An energy recovery mechanism 61 and a pressure reducing valve group 62 are installed between the high-pressure clean gas pipe 31 and the low-pressure clean gas pipe 32. The energy recovery mechanism 61 is either a TRT or a BPRT. The energy recovery mechanism 61 and the pressure reducing valve group 62 are arranged in parallel. When blast furnace 1 is shut down normally, the air volume and gas volume of blast furnace 1 are gradually reduced, and the gas pressure control is gradually switched from TRT or BPRT to pressure reducing valve group 62. When the gas volume is reduced to the set value, the gas source cut-off valve is opened, and the cascade ejector recovery device 5 starts to work.

[0036] Reference Figure 1 The gas transmission pipe includes a gas riser pipe 21 and a gas downcomer pipe 22. The top of blast furnace 1 is connected to the gas riser pipe 21, and the output end of the gas riser pipe 21 is connected to the gas downcomer pipe 22. To reduce dust in the gas and protect the environment, a primary dust collector 23 is connected to the output end of the gas downcomer pipe 22. The output end of the primary dust collector 23 is connected to a coarse gas pipe 24, and a secondary dust collector 25 is installed at the output end of the coarse gas pipe 24. Multiple secondary dust collectors 25 are installed, and the output end of the secondary dust collector 25 is connected to the input end of the high-pressure clean gas pipe 31. The primary dust collector 23 and the secondary dust collector 25 can be cyclone dust collectors or baghouse dust collectors.

[0037] Reference Figure 2 and Figure 3 The cascade ejector recovery device 5 includes a first ejector tube 51 and a second ejector tube 52, the diameter of which is larger than that of the first ejector tube 51. The inlet of the first ejector tube 51 is connected to the outlet of the high-pressure clean gas pipe 31. Specifically, the inlet of the first ejector tube 51 is connected to a recovered gas inlet pipe 511, and a first connecting pipe 311 connects the recovered gas inlet pipe 511 and the high-pressure clean gas pipe 31. The inlet of the second ejector tube 52 is connected to the outlet of the first ejector tube 51 and the outlet of the high-pressure clean gas pipe 31, and the outlet of the second ejector tube 52 is connected to the inlet of the low-pressure clean gas pipe 32. A second connecting pipe 321 connects the outlet of the second ejector tube 52 and the low-pressure clean gas pipe 32.

[0038] Reference Figure 2 and Figure 3 Both the first connecting pipe 311 and the second connecting pipe 321 are equipped with gas valve assemblies 33, which are shut-off valves and can be butterfly valves or blind valves. A bypass pipe 53 is connected to the side wall of the recovered gas inlet pipe 511, and the bypass pipe 53 is connected to the inlet of the second ejector pipe 52. An on / off valve 531 is installed on the bypass pipe 53, which can be a butterfly valve, gate valve, or check valve.

[0039] Reference Figure 2 and Figure 3The cascade ejector recovery device 5 also includes a high-pressure gas source assembly 7 for providing initial ejection power to the first ejector tube 51. The high-pressure gas source assembly 7 includes a high-pressure working gas source 71, a high-pressure gas supply pipe 72, and a high-pressure gas nozzle 73. One end of the high-pressure gas supply pipe 72 passes through the wall of the first ejector tube 51 and extends into the first ejector tube 51. The high-pressure gas nozzle 73 is located at the end of the high-pressure gas supply pipe 72 inside the first ejector tube 51, and the gas flow direction emitted from the high-pressure gas nozzle 73 is towards the second ejector tube 52. The input end of the high-pressure gas supply pipe 72 is connected to the high-pressure working gas source 71, and a gas shut-off valve 721 is installed on the high-pressure gas supply pipe 72. During the recovery of coal gas during shutdown, the gas shut-off valve 721 is opened.

[0040] The high-pressure working gas source 71 is a high-pressure coal gas source, a nitrogen source, or a steam source.

[0041] As blast furnace 1 shuts down, the flow rate and pressure of the gas decrease, making gas recovery increasingly difficult. When the negative pressure created by the second ejector pipe 52 is insufficient for gas recovery, the on / off valve 531 on the bypass pipe 53 automatically closes. The on / off valve 531 can close automatically under gas pressure or electronic control. At this point, the shut-down gas is recovered via the first ejector pipe 51. Because the high-pressure gas has a high velocity when ejected, the first ejector pipe 51 can create a greater negative pressure to meet the recovery needs in the later stages of blast furnace 1 shutdown, until the gas pressure in blast furnace 1 drops to the set value, at which point blast furnace 1 can be shut down normally, and the entire recovery process ends.

[0042] The implementation principle of this application embodiment is as follows: When the blast furnace 1 is running normally, the gas valve groups 33 at both ends of the cascade ejector recovery device 5 are closed. At this time, the cascade ejector recovery device 5 and the gas pipeline network of the blast furnace 1 are reliably isolated, and the blast furnace 1 continues to operate normally. When blast furnace 1 is shut down, the high-pressure gas source assembly 7 operates, blowing high-pressure gas into the first ejector tube 51. At this time, the shut-down gas is transported through the high-pressure clean gas pipe 31 to the first ejector tube 51 and the second ejector tube 52. Under the jet action of the high-pressure gas, a negative pressure is formed in the first ejector tube 51 to recover the gas. The recovered gas mixes with the high-pressure gas and enters the input port of the second ejector tube 52 from the output port of the first ejector tube 51. This makes the mixed gas in the first ejector tube 51 the working gas of the second ejector tube 52. A negative pressure is formed in the second ejector tube 52, causing a portion of the gas to enter the second ejector tube 52 from the high-pressure clean gas pipe 31 for recovery. This satisfies the need for recovery of blast furnace 1's shut-down vented gas, while also saving the consumption of the high-pressure gas source.

[0043] At this time, since the gas from blast furnace 1 is easily recovered, the gas from the shutdown process will enter the second ejector pipe 52 through the first ejector pipe 51 and the bypass pipe 53. The on / off valve 531 on the bypass pipe 53 remains open under the action of the gas. Under the injection of high-pressure gas, the first ejector pipe 51 forms a negative pressure for gas recovery. The mixed gas at the outlet of the first ejector pipe 51 serves as the working gas for the second ejector pipe 52, causing the second ejector pipe 52 to form a negative pressure. A portion of the gas from the shutdown process of blast furnace 1 can also enter the second ejector pipe 52 through the bypass pipe 53 and enter the low-pressure clean gas pipe 32 from the outlet of the second ejector pipe 52 for recovery. At this time, a cascade working mode of the front and rear ejector pipes is formed, with only one ejector pipe consuming high-pressure working gas, realizing the recovery of a large gas flow and saving the consumption of high-pressure gas source.

[0044] As blast furnace 1 shuts down, the flow rate and pressure of the gas decrease, making gas recovery increasingly difficult. When the negative pressure created by the second ejector pipe 52 is insufficient for gas recovery, the gas pressure in the bypass pipe 53 decreases, and the on / off valve 531 on the bypass pipe 53 automatically closes. At this point, the shut-down gas is recovered via the first ejector pipe 51. Because the high-pressure gas has a high velocity when ejected from the nozzle, the first ejector pipe 51 can create a greater negative pressure, meeting the recovery needs in the later stages of blast furnace 1's shutdown, until the gas pressure in blast furnace 1 drops to the set value, at which point blast furnace 1 can be shut down normally, and the entire recovery process ends.

[0045] Example 2

[0046] The main difference between this implementation and Example 1 is that the first ejector tube 51 is inserted inside the second ejector tube 52, the second ejector tube 52 is connected to the first connecting pipe 311, and there is a gap between the wall of the recovered gas inlet pipe 511 and the inner wall of the second ejector tube 52. To improve the uniformity of gas intake into the second ejector tube 52, the first ejector tube 51 and the second ejector tube 52 are coaxially arranged. In actual use, the second ejector tube 52 has a stronger ejection effect, a larger gas access area, fewer bends, less flow velocity loss, and a more uniform negative pressure suction.

[0047] Example 3

[0048] Reference Figure 4 The main difference between this implementation and Example 1 is that a pressure buffer tank 8 is installed between the cascade ejector recovery device 5 and the gas recovery pipeline network 4. Specifically, a pressure buffer tank 8 is installed on the second connecting pipe 321. This can better stabilize the gas pressure during the recovery process and reduce the pressure impact on the downstream pipeline network; at the same time, it plays a dehydration role, reducing the moisture in the gas.

[0049] In this embodiment, when the high-pressure working gas source 71 is a steam source, i.e., when steam is used as the working gas source, the pressure buffer tank 8 can also be used as a drain tank for steam condensate to reduce the amount of water entering the gas recovery pipeline network 4. The pressure buffer tank 8 is equipped with a spray system for cooling the steam. The spray system includes nozzles installed inside the pressure buffer tank 8 for spraying cooling water into the pressure buffer tank 8, thereby reducing the temperature and improving the steam condensation effect, further reducing the amount of water entering the downstream pipeline network.

[0050] Example 4

[0051] Reference Figure 5 and Figure 6 The main difference between this embodiment and Example 1 is that at least two sets of cascade ejector recovery devices 5 are arranged side by side. In this embodiment, two sets of cascade ejector recovery devices 5 are arranged, while in other embodiments, multiple sets may be arranged. If maintenance is required on the first ejector tube 51 and / or the second ejector tube 52 of one set of cascade ejector recovery devices 5, it is only necessary to close the gas valve group 33 at both ends of the cascade ejector recovery device 5 that needs maintenance, and the other set of cascade ejector recovery devices 5 can continue to perform ejector recovery work normally. A pressure buffer tank 8 is provided on the second connecting pipe 321.

[0052] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A cascade ejector gas recovery device for blast furnace shutdown venting, comprising a blast furnace (1), a gas transmission pipe, a high-pressure clean gas pipe (31), a low-pressure clean gas pipe (32), and a gas recovery network (4), characterized in that: One end of the gas transmission pipe is connected to the blast furnace (1), and the other end is connected to the high-pressure clean gas pipe (31). The low-pressure clean gas pipe (32) is connected to the gas recovery network (4). A cascade ejector recovery device (5) is provided between the high-pressure clean gas pipe (31) and the low-pressure clean gas pipe (32). The cascade ejector recovery device (5) includes a first ejector pipe (51) and a second ejector pipe (52). The diameter of the second ejector pipe (52) is larger than that of the first ejector pipe (51). The inlet of the first ejector pipe (51) is connected to the outlet of the high-pressure clean gas pipe (31). The inlet of the second ejector pipe (52) is connected to the outlet of the first ejector pipe (51) and the outlet of the high-pressure clean gas pipe (31). The outlet of the second ejector pipe (52) is connected to the inlet of the low-pressure clean gas pipe (32). The cascade ejector recovery device (5) also includes a high-pressure gas source assembly (7) for providing initial ejection power to the first ejector pipe (51).

2. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 1, characterized in that: The inlet of the first ejector tube (51) is connected to a recovered gas inlet pipe (511), and the recovered gas inlet pipe (511) is connected to the high-pressure clean gas pipe (31) by a first connecting pipe (311). The outlet of the second ejector tube (52) is connected to the low-pressure clean gas pipe (32) by a second connecting pipe (321). Gas valve groups (33) are provided on both the first connecting pipe (311) and the second connecting pipe (321).

3. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 2, characterized in that: The side wall of the recovered gas inlet pipe (511) is connected to a bypass pipe (53), which is connected to the inlet of the second ejector pipe (52).

4. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 3, characterized in that: The bypass pipe (53) is equipped with an on / off valve (531).

5. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 2, characterized in that: The first ejector tube (51) is inserted inside the second ejector tube (52), the second ejector tube (52) is connected to the first connecting pipe (311), and there is a gap between the wall of the recovered gas inlet pipe (511) and the inner wall of the second ejector tube (52).

6. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 1, characterized in that: The high-pressure gas source assembly (7) includes a high-pressure working gas source (71), a high-pressure gas supply pipe (72), and a high-pressure gas nozzle (73). One end of the high-pressure gas supply pipe (72) passes through the wall of the first ejector pipe (51) and extends into the first ejector pipe (51). The high-pressure gas nozzle (73) is located at one end of the high-pressure gas supply pipe (72) inside the first ejector pipe (51). The input end of the high-pressure gas supply pipe (72) is connected to the high-pressure working gas source (71). A gas shut-off valve (721) is provided on the high-pressure gas supply pipe (72).

7. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 6, characterized in that: The high-pressure working gas source (71) is a high-pressure coal gas source, a nitrogen source, or a steam source.

8. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 7, characterized in that: A pressure buffer tank (8) is provided between the cascade ejector recovery device (5) and the gas recovery pipeline (4).

9. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 8, characterized in that: The high-pressure working gas source (71) is a steam source, and the pressure buffer tank (8) is equipped with a spray system for cooling steam.

10. The cascade ejector recovery device for blast furnace shutdown venting gas according to claim 1 or 9, characterized in that: The cascade ejector recovery device (5) is arranged in at least two sets in parallel.

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