A grouting sealing device and method for coke oven brick gas passages

Abstract

This invention discloses a grouting and sealing device and method for coke oven brick gas ducts, belonging to the field of coke oven technology. The invention includes a main spraying rod with a quick connector at its input end; an outer wall for the main spraying rod; and multiple sets of radial injection holes at the top of the main spraying rod. An upper sealing device and a lower sealing device are respectively installed on the rod body; and scraping devices are installed along the outer edges of the upper and lower sealing devices. This invention can address various types of brick gas duct damage, effectively improve the grouting effect, and quickly and effectively repair damaged brick gas ducts. It effectively reduces coke oven gas leakage in the brick gas ducts, lowers the coking calorific value of the coke oven, and extends the service life of the coke oven. Simultaneously, it avoids the grout entering the combustion chamber and clogging the inclined channel, and significantly saves grout.

Description

Technical Field

[0001] This invention relates to the field of coke oven technology, and more specifically, to a grouting and sealing device and method for the coal gas passage of a coke oven brick. Background Technology

[0002] The brick gas duct is the final channel through which coke oven gas enters the combustion chamber from the gas injection pipe, providing heat for heating the coke oven. The brick gas duct is constructed from specific types of refractory bricks and clay mortar. During the pre-start-up hot-drying process of the coke oven body, the expansion of the masonry causes cracks in the mortar joints between the bricks, resulting in cracks in the brick gas duct. During production, as the coke oven body gradually ages, gas leakage can cause explosions in the gas exchange system, which can also lead to cracks in the brick gas duct. Furthermore, because the gas pipes in the coke oven are made of silica bricks, which have poor resistance to rapid heating and cooling, and the small flue area experiences frequent temperature fluctuations, the silica bricks are prone to cracking due to these temperature changes. Damaged pipes can block the gas pipes, preventing gas from entering the combustion chamber and creating a dead combustion channel. Additionally, gas can leak from the gas pipes into the regenerator and small flue, causing the waste gas pan to ignite, melting the checker bricks, and damaging the regenerator walls, severely impacting the coke oven's lifespan. Simultaneously, blocked flues result in low temperatures, affecting normal coke oven heating and leading to problems such as high current during coke pushing, fluctuating coke quality, and unorganized venting during coke discharge.

[0003] Due to the unique location and narrow structure of the brick gas ducts, the operation is extremely difficult. Traditional repair methods for damaged coke oven brick gas ducts primarily rely on large-scale excavation and replacement from the outside or combustion chamber after the furnace body has cooled. This method has significant drawbacks, including long construction cycles (usually requiring several days or even weeks of production shutdown), high repair costs, and significant disruption to production continuity. More importantly, traditional methods cannot accurately locate hidden, minute damage points, often resulting in large-area replacements, leading to "over-repair," and the sealing and durability after repair are difficult to guarantee, easily causing secondary leaks. Recently, with the increasing prevalence of segmented regenerator structures in large coke ovens, replacing the tube bricks is even more challenging. Furthermore, the currently used grouting technology generally suffers from problems such as inaccurate control of grout injection height, easy blockage of adjacent channels (such as lamp head bricks and inclined passages), incomplete grout filling, and inability to recover and clean residual material. The method of inserting pipes to repair the brick gas duct will result in a significant reduction in the cross-sectional area of ​​the brick gas duct, increasing the resistance of the coke oven heating system. In addition, the furnace head flue is most affected by the expansion of the furnace body, which causes the pre-embedded pipe in the foundation top plate to be misaligned with the brick gas duct, making it impossible to insert pipes.

[0004] Existing technologies include a "communicating vessel grouting method," which repairs leaks by controlling the grout height. While this reduces the risk of grout overflow to some extent, it lacks visual diagnostic tools for internal conditions, essentially constituting blind repair. Furthermore, the device structure is relatively simple, with limited sealing performance and pressure filling effectiveness. Other designs, such as "overflow devices" or "full-flow devices," primarily prevent blockages through return flow paths, but their ability to fully fill deep cracks and maintain post-construction pipe wall cleanliness still needs improvement. Therefore, developing an online repair method that integrates comprehensive, efficient repair, and clean operation of brick-and-coal tunnels has become a pressing technical challenge in this field. Summary of the Invention

[0005] 1. The technical problem that the invention aims to solve

[0006] To address the shortcomings and deficiencies of existing technologies, this invention provides a grouting and sealing device and method for coke oven brick gas ducts. This invention can handle various types of brick gas duct damage, effectively improve the grouting effect, and quickly and effectively repair damaged brick gas ducts. It also effectively reduces coke oven gas leakage within the brick gas ducts, lowers the coking calorific value of the coke oven, and extends the service life of the coke oven. Simultaneously, it prevents grout from entering the combustion chamber and clogging the inclined channel, and significantly saves on grout.

[0007] 2. Technical Solution

[0008] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0009] The present invention provides a grouting and sealing device for a coke oven brick gas duct, comprising a main spraying rod, wherein the input end of the main spraying rod is provided with a quick connector;

[0010] The outer ring of the main shotcrete rod is provided with a shotcrete rod outer wall, and the top of the main shotcrete rod is provided with multiple sets of radial injection holes;

[0011] The main shotcrete rod is equipped with an upper sealing device and a lower sealing device on its shaft; a scraping device is provided on the outer edge of the upper sealing device and the lower sealing device.

[0012] Furthermore, the main spraying rod extends into the brick gas duct, and the damaged area of ​​the brick gas duct is located between the upper sealing device and the lower sealing device.

[0013] Furthermore, the upper sealing device and the lower sealing device have the same structure, both including a drive motor, bearing housing, lead screw, slider, swing arm, linkage rod, sealing cover, and hinge support;

[0014] The output end of the drive motor passes through the bearing housing and is connected to the lead screw. A slider is provided on the body of the lead screw. Multiple sets of swing arms are connected at intervals on the surface of the slider. One end of the swing arm is movably connected to the slider, and the other end of the swing arm is connected to a linkage rod. A sealing cover is fitted on the surface of the multiple sets of linkage rods.

[0015] The lead screw is provided with bearing seats at both the upper and lower ends. A hinge support is provided on the top of the bearing seat at the upper end of the lead screw. Multiple sets of linkage rods are evenly distributed on the outer surface of the hinge support. The linkage rods are movably connected to the hinge support.

[0016] The drive motor drives the lead screw to rotate, causing the slider to slide along the lead screw. The slider drives the linkage rod to swing synchronously through the swing arm. During the swing, the sealing cover unfolds and the scraping device on its outer ring fits against the inner wall of the brick gas duct, thereby producing a sealing effect.

[0017] Furthermore, the drive motor is fixed to the surface of the outer wall of the shotcrete rod, and a protective plate is also provided on the outer ring of the drive motor.

[0018] Furthermore, the outer ring of the sealing cover is provided with a scraping device, which is a scraper structure.

[0019] Furthermore, the scraping device is a brush head structure.

[0020] Furthermore, the main shotcrete bar is composed of multiple sets of sub-shotcrete bars, which are connected to each other by threaded connections.

[0021] The top sub-shotcrete rod penetrates the outer wall of the shotcrete rod and extends to the upper end of the outer wall of the shotcrete rod; the bottom sub-shotcrete rod is connected to a quick connector.

[0022] Furthermore, multiple sets of annular discharge valves are spaced apart on the lower part of the outer wall of the shotcrete rod; the annular discharge valves are connected to a recovery pipeline, and the output end of the recovery pipeline is connected to a slurry storage tank.

[0023] A method for using a grouting and sealing device for a coke oven brick gas duct, characterized by the following steps:

[0024] S1: Forming a sealed cavity in the brick gas duct:

[0025] The main shotcrete rod is lowered to a predetermined depth so that the damaged area of ​​the brick gas duct is completely located between the upper and lower sealing devices of the main shotcrete rod. Then the upper and lower sealing devices are opened to form a tight fit with the inner wall of the brick gas duct above and below the damaged area, respectively, thereby forming an annular and closed pressure working chamber between the outer wall of the shotcrete rod and the inner wall of the brick gas duct.

[0026] S2: Pressure spraying filling repair:

[0027] The pre-prepared refractory slurry is injected into the high-pressure slurry pump; the slurry pump is connected to the quick connector of the main slurry rod through a pressure-resistant hose. The slurry pump is started and the slurry is pumped into the pressure working chamber at the set pressure. Under the action of continuous pressure, the slurry is evenly sprayed out through multiple sets of radial injection holes, squeezed into the sealed cavity from all directions, and fully penetrated and filled into the deep joints and cracks of the damaged bricks to achieve dense bonding and curing.

[0028] S3: Pressure monitoring and residual material recovery:

[0029] During the shotcreting process, the system pressure is monitored in real time. When the pressure gauge reading reaches the preset value and remains stable without a significant and continuous drop, indicating that the crack has been filled, the pumping is stopped. First, the pressure in the shotcreting pipeline and the pressure working chamber is depressurized. Then, the annular discharge valve located in the lower sealing device is opened. Excess slurry that has not been injected into the crack is discharged from the chamber under the action of gravity or slight pressure difference through the annular discharge valve and the connected recovery pipeline, flowing into the slurry storage tank for recycling.

[0030] S4: Spray bar retraction and inner wall cleaning

[0031] After the repair and residual material recovery are completed, the scraping device installed on the top of the main spraying rod will come into contact with the inner wall of the brick gas duct during the unfolding of the upper sealing device. During the withdrawal of the main spraying rod, the scraping device will scrape, clean and collect the thin layer of excess slurry or dripping material adhering to the repair area and the nearby inner wall of the brick gas duct, and carry it out with the rod to ensure that the inner wall of the brick gas duct is smooth and the cross-section of the channel is not reduced after the repair.

[0032] 3. Beneficial effects

[0033] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0034] This invention can address various types of damage to brick-fired gas ducts, effectively improving the spraying effect and enabling quick and efficient repair of damaged ducts. It also effectively reduces gas leakage within the ducts, lowers coking calorific value, and extends the coke oven's service life. Furthermore, it prevents sprayed material from entering the combustion chamber and clogging the inclined channel, significantly saving on sprayed material. Attached Figure Description

[0035] Figure 1 This is an overall structural diagram of the present invention;

[0036] Figure 2 This is a diagram illustrating the installation effect of the recycling pipeline of the present invention.

[0037] Figure 3 This is an initial state diagram of the upper sealing device of the present invention;

[0038] Figure 4This is a diagram showing the sealing state of the upper sealing device of the present invention;

[0039] Figure 5 This is a top view of the sealed cover of the present invention in the open state.

[0040] In the diagram: 1. Brick gas duct; 2. Upper sealing device; 200. Drive motor; 201. Bearing seat; 202. Lead screw; 203. Sliding block; 204. Swing arm; 205. Linkage rod; 206. Sealing cover; 207. Hinge support; 208. Protective plate; 3. Outer wall of shotcrete rod; 4. Main shotcrete rod; 401. Sub-shotcrete rod; 5. Lower sealing device; 6. Quick connector; 7. Radial injection hole; 8. Thread; 9. Annular discharge valve; 901. Recovery pipeline; 902. Slurry storage tank. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0042] Example 1

[0043] from Figure 1-5 As can be seen, the coke oven brick gas duct grouting and sealing device of this embodiment includes a main spraying rod 4, and a quick connector 6 is provided at the input end of the main spraying rod 4; a three-way valve is externally connected to the bottom of the quick connector 6; the other two ports of the three-way valve are respectively connected in series to the grouting pipeline and the recovery pipeline 901, and a one-way valve can be provided on the pipeline as appropriate.

[0044] The outer ring of the main shotcrete rod 4 is provided with a shotcrete rod outer wall 3, and the top of the main shotcrete rod 4 is provided with multiple sets of radial injection holes 7;

[0045] The main shotcrete rod 4 is equipped with an upper sealing device 2 and a lower sealing device 5 on its rod body; a scraping device 10 is provided on the outer edge of the upper sealing device 2 and the lower sealing device 5.

[0046] The main shotcrete rod 4 extends into the brick gas duct 1, and the damaged area of ​​the brick gas duct 1 is located between the upper sealing device 2 and the lower sealing device 5.

[0047] The upper and lower parts of the main spraying rod 4 are effectively sealed by the sealing device, forming a closed space between the pipe body and the brick gas duct 1. The upper seal prevents the sprayed material from entering the combustion chamber and blocking the inclined channel, and the lower seal prevents the sprayed material from blocking the nozzle and the coke oven gas horizontal pipe.

[0048] The upper sealing device 2 and the lower sealing device 5 have the same structure, both including a drive motor 200, a bearing seat 201, a lead screw 202, a slider 203, a swing arm 204, a linkage rod 205, a sealing cover 206, and a hinge support 207.

[0049] The output end of the drive motor 200 passes through the bearing housing 201 and is connected to the lead screw 202. A slider 203 is provided on the body of the lead screw 202. Multiple sets of swing arms 204 are connected to the surface of the slider 203 at intervals. One end of the swing arm 204 is movably connected to the slider 203, and the other end of the swing arm 204 is connected to the linkage rod 205. The surfaces of the multiple sets of linkage rods 205 are all fitted with a sealing cover 206.

[0050] Both the upper and lower ends of the lead screw 202 are provided with bearing seats 201. The top of the bearing seat 201 at the upper end of the lead screw 202 is provided with a hinge support 207. Multiple sets of linkage rods 205 are evenly distributed on the outer surface of the hinge support 207. The linkage rods 205 are movably connected to the hinge support 207.

[0051] The drive motor 200 drives the lead screw 202 to rotate, thereby causing the slider 203 to slide along the lead screw 202. The slider 203 drives the linkage rod 205 to swing synchronously through the swing arm 204. During the swing, the sealing cover 206 unfolds and makes the scraping device 10 on its outer ring fit against the inner wall of the brick gas duct, thereby producing a sealing effect.

[0052] The drive motor 200 is fixed to the surface of the outer wall 3 of the shotcrete rod, and a protective plate 208 is also provided on the outer ring of the drive motor 200.

[0053] The outer ring of the sealing cover 206 is provided with a scraping device 10, which can be a scraper structure or a brush head structure. In this embodiment, a scraper structure is selected.

[0054] The main shotcrete rod 4 is composed of multiple sets of sub-shotcrete rods 401, which are connected to each other by threaded connections 8. The modular assembly of the rods makes the length of the main shotcrete rod 4 controllable and adjustable. According to the length of the brick gas duct, a suitable number and specification of modular extension rods are selected and threaded together to form a main shotcrete rod with a total length slightly greater than the distance from the top of the damaged area to the inlet. It can be adjusted in real time for different working conditions.

[0055] The sub-shotcrete rod 401 at the top position penetrates the outer wall 3 of the shotcrete rod and extends to the upper end of the outer wall 3 of the shotcrete rod; the sub-shotcrete rod 401 at the bottom position is connected to the quick connector 6.

[0056] Multiple sets of annular discharge valves 9 are spaced apart on the lower part of the outer wall 3 of the shotcrete rod; the annular discharge valves 9 are connected to a recovery pipeline 901, and the output end of the recovery pipeline 901 is connected to a slurry storage tank 902.

[0057] The grout is sprayed through the radial injection hole 7 into the space between the inner nozzle and the brick gas duct 1, and a certain pressure is maintained. Since the upper and lower channels of the brick gas duct 1 are effectively sealed, the grout can be squeezed into the damaged part of the brick gas duct to effectively repair the damaged brick gas duct.

[0058] After the sprayed grout has fully filled the joints between the damaged bricks and the pressure has not dropped significantly, release the pressure and open the annular discharge valve 9 to recover the excess sprayed grout.

[0059] When the main spraying rod 4 is pulled out, the top scraping device 10 can clean the excess slurry on the wall of the brick gas duct 1, preventing the slurry from clogging the brick gas duct.

[0060] Example 2

[0061] from Figure 1-5 As can be seen, the method of using the coke oven brick gas duct grouting sealing device in this embodiment provides a controllable and sealed pressure spraying repair method that can quickly and effectively repair and seal damaged brick gas ducts.

[0062] The steps are as follows:

[0063] S1: A sealed cavity is formed in the brick gas duct 1:

[0064] The main shotcrete rod 4 is lowered to a predetermined depth so that the damaged area of ​​the brick gas duct 1 is completely located between the upper sealing device 2 and the lower sealing device 5 of the main shotcrete rod 4; then the upper sealing device 2 and the lower sealing device 5 are opened, respectively forming a tight fit with the inner wall of the brick gas duct 1 above and below the damaged area, thereby forming an annular, closed pressure working chamber between the outer wall 3 of the shotcrete rod and the inner wall of the brick gas duct 1;

[0065] The upper seal prevents slurry from rising into the combustion chamber and the ramp; the lower seal, located above the lower nozzle interface, prevents slurry from leaking down and clogging the nozzle and horizontal pipe.

[0066] S2: Pressure spraying filling repair:

[0067] The pre-prepared refractory slurry is injected into the high-pressure slurry pump. The refractory slurry can be a mixture of clay fire clay, silica fire clay, phosphoric acid and other main components. The slurry pump is connected to the quick connector 6 of the main slurry rod 4 through a pressure-resistant hose. The slurry pump is started and the slurry is pumped into the pressure working chamber at a set pressure (such as 0.3-0.8MPa). Under the action of continuous pressure, the slurry is evenly sprayed out through multiple sets of radial injection holes 7, squeezed into the sealed cavity from all directions, and fully penetrated and filled into the deep joints and cracks of the damaged bricks to achieve dense bonding and curing.

[0068] S3: Pressure monitoring and residual material recovery:

[0069] During the shotcreting process, the system pressure is monitored in real time. When the pressure gauge reading reaches the preset value and remains stable without a significant and continuous drop, indicating that the crack has been filled, the pumping is stopped. First, the pressure in the shotcreting pipeline and the pressure working chamber is depressurized. Then, the annular discharge valve 9 located in the lower sealing device 5 is opened. Excess slurry that has not been injected into the crack is discharged from the chamber through the annular discharge valve 9 and the connected recovery pipeline 901 under the action of gravity or slight pressure difference, and flows into the slurry storage tank 902 for recycling, which significantly improves the material utilization rate.

[0070] S4: Spray bar retraction and inner wall cleaning

[0071] After the repair and residual material recovery are completed, the scraping device 10 installed on the top of the main spraying rod 4 will come into contact with the inner wall of the brick gas duct 1 during the unfolding process of the upper sealing device 2. During the withdrawal of the main spraying rod 4, the scraping device 10 will scrape, clean and collect the thin layer of excess slurry or dripping material adhering to the repair area and the nearby inner wall of the brick gas duct 1, and carry it out with the rod, ensuring that the inner wall of the brick gas duct 1 is smooth after repair and the cross-section of the channel is not reduced, thus fundamentally eliminating the risk of blockage caused by slurry residue.

[0072] This invention can address various types of damage to brick-fired gas ducts, effectively improving the spraying effect and enabling quick and efficient repair of damaged ducts. It also effectively reduces gas leakage within the ducts, lowers coking calorific value, and extends the coke oven's service life. Furthermore, it prevents sprayed material from entering the combustion chamber and clogging the inclined channel, significantly saving on sprayed material.

[0073] Example 3

[0074] from Figure 1-5 As can be seen, in this embodiment of the coke oven brick gas duct grouting sealing device, the upper sealing device 2 and the lower sealing device 5 in embodiments 1-2 both adopt an umbrella-shaped mechanical structure. In this embodiment, an air-filled or liquid-filled airbag sealing device can be used to replace it; the same sealing effect can be produced.

[0075] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A grouting and sealing device for a coke oven brick gas duct, comprising a main spraying rod (4), characterized in that: The input end of the main shotcrete rod (4) is provided with a quick connector (6). The outer ring of the main shotcrete rod (4) is provided with a shotcrete rod outer wall (3), and the top of the main shotcrete rod (4) is provided with multiple sets of radial injection holes (7). The main shotcrete rod (4) is provided with an upper sealing device (2) and a lower sealing device (5) respectively; a scraping device (10) is provided on the outer edge of the upper sealing device (2) and the lower sealing device (5).

2. The grouting and sealing device for coke oven brick gas passages according to claim 1, characterized in that: The main spraying rod (4) extends into the brick gas duct (1), and the damaged area of ​​the brick gas duct (1) is located between the upper sealing device (2) and the lower sealing device (5).

3. The grouting and sealing device for coke oven brick gas passages according to claim 1, characterized in that: The upper sealing device (2) and the lower sealing device (5) have the same structure, both including a drive motor (200), a bearing seat (201), a lead screw (202), a slider (203), a swing arm (204), a linkage rod (205), a sealing cover (206), and a hinge support (207). The output end of the drive motor (200) passes through the bearing housing (201) and is connected to the lead screw (202). A slider (203) is provided on the body of the lead screw (202). Multiple sets of swing arms (204) are connected to the surface of the slider (203) at intervals. One end of the swing arm (204) is movably connected to the slider (203), and the other end of the swing arm (204) is connected to a linkage rod (205). A sealing cover (206) is fitted on the surface of the multiple sets of linkage rods (205). The upper and lower ends of the lead screw (202) are provided with bearing seats (201), and the top of the bearing seat (201) at the upper end of the lead screw (202) is provided with a hinge support (207). Multiple sets of linkage rods (205) are evenly distributed on the outer surface of the hinge support (207), and the linkage rods (205) are movably connected to the hinge support (207). The drive motor (200) drives the lead screw (202) to rotate, thereby causing the slider (203) to slide along the lead screw (202). The slider (203) drives the linkage rod (205) to swing synchronously through the swing arm (204). During the swing, the sealing cover (206) unfolds and the scraping device (10) on its outer ring comes into contact with the inner wall of the brick gas duct, thereby producing a sealing effect.

4. The grouting and sealing device for coke oven brick gas passages according to claim 3, characterized in that: The drive motor (200) is fixed on the surface of the outer wall (3) of the shotcrete rod, and a protective plate (208) is also provided on the outer ring of the drive motor (200).

5. The grouting and sealing device for coke oven brick gas passages according to claim 3, characterized in that: The outer ring of the sealing cover (206) is provided with a scraper device (10), which is a scraper structure.

6. The grouting and sealing device for coke oven brick gas passages according to claim 5, characterized in that: The scraping device (10) is a brush head structure.

7. The grouting and sealing device for coke oven brick gas passages according to claim 1, characterized in that: The main shotcrete bar (4) is composed of multiple sets of sub-shotcrete bars (401), and the multiple sets of sub-shotcrete bars (401) are connected to each other by threaded connections (8). The sub-shotcrete rod (401) at the top position penetrates the outer wall (3) of the shotcrete rod and extends to the upper end of the outer wall (3) of the shotcrete rod; the sub-shotcrete rod (401) at the bottom position is connected to the quick connector (6).

8. The grouting and sealing device for coke oven brick gas passages according to claim 1, characterized in that: Multiple sets of annular discharge valves (9) are provided at intervals on the lower part of the outer wall (3) of the shotcrete rod; the annular discharge valves (9) are connected to a recovery pipeline (901), and the output end of the recovery pipeline (901) is connected to a slurry storage tank (902).

9. The method of using the grouting and sealing device for the gas duct of a coke oven brick according to claim 1, characterized in that: The steps are as follows: S1: A sealed cavity is formed in the brick gas duct (1): The main shotcrete rod (4) is placed to a predetermined depth so that the damaged area of ​​the brick gas duct (1) is completely located between the upper sealing device (2) and the lower sealing device (5) of the main shotcrete rod (4); then the upper sealing device (2) and the lower sealing device (5) are opened, respectively forming a tight fit with the inner wall of the brick gas duct (1) above and below the damaged area, thereby forming an annular, closed pressure working chamber between the outer wall (3) of the shotcrete rod and the inner wall of the brick gas duct (1); S2: Pressure spraying filling repair: The pre-prepared refractory slurry is injected into the high-pressure slurry pump; the slurry pump is connected to the quick connector (6) of the main slurry rod (4) through a pressure-resistant hose. The slurry pump is started and the slurry is pumped into the pressure working chamber at the set pressure. Under the action of continuous pressure, the slurry is sprayed out evenly through multiple sets of radial injection holes (7), squeezed into the sealed cavity from all directions, and fully penetrated and filled into the deep joints and cracks of the damaged bricks to achieve dense bonding and curing. S3: Pressure monitoring and residual material recovery: During the shotcreting process, the system pressure is monitored in real time; when the pressure gauge reading reaches the preset value and remains stable (without obvious continuous decline, indicating that the broken joint has been filled), the pumping is stopped; first, the pressure in the shotcreting pipeline and pressure working chamber is depressurized. Then, the annular discharge valve (9) located in the lower sealing device (5) is opened; Excess slurry that has not been injected into the cavity is discharged through the annular discharge valve (9) and the connected recovery pipeline (901) under the action of gravity or slight pressure difference, and flows into the slurry storage tank (902) for recycling. S4: Spray bar retraction and inner wall cleaning After the repair and residual material recovery are completed, the scraping device (10) installed on the top of the main spraying rod (4) will come into contact with the inner wall of the brick gas duct (1) during the unfolding process of the upper sealing device (2). During the withdrawal process of the main spraying rod (4), the scraping device (10) will scrape, clean and collect the thin layer of excess slurry or dripping material attached to the repair area and the nearby inner wall of the brick gas duct (1) and carry it out with the rod, so as to ensure that the inner wall of the brick gas duct (1) is smooth and the channel cross-section is not reduced after the repair.

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