CN221525544U - Three-dimensional sealing structure of large box of boiler - Google Patents

Abstract

The utility model discloses a three-dimensional sealing structure of a large boiler box, which comprises a metal sealing plate and an expansion point, wherein the expansion point is arranged on the metal sealing plate at the outer side of the boiler, the expansion point is sealed by a flexible sealing structure, the expansion point is arranged at the central part of the flexible sealing structure, the flexible sealing structure consists of a metal seal and a flexible seal, the metal seal is a metal sealing box, the metal sealing box surrounds the expansion point, the metal sealing box is annular, the metal sealing box is welded on the metal sealing plate through steel nails, steel nails are uniformly arranged at the outer side of the metal sealing box, the flexible seal adopts a three-dimensional flexible sealing mode, and all expansion points possibly generated, namely leakage points, are arranged at the central point of an integral sealing layer, so that the sealing layer of a sira blanket can fully absorb expansion.

Description

Three-dimensional sealing structure of large box of boiler

Technical Field

The utility model relates to the technical field of boiler sealing, in particular to a three-dimensional sealing structure of a large boiler chamber.

Background

The boiler bale is the main part for bearing the water pressure and temperature load of the boiler. It is not only an integral part of the pressure vessel of the boiler, but also one of the largest structural elements in the boiler. The large package is used primarily to store boiler working media, typically including water and steam. The boiler big bag has the functions of stabilizing pressure, preserving heat, storing liquid and the like, and is an important guarantee for ensuring the operation safety of the boiler. After the boiler of the coal-fired steam turbine generator unit is subjected to several times of cold and hot state working condition conversion, the factors such as large cold and hot state displacement change, large thermal stress change, insufficient expansion of metal seal and the like of components at each part of a large boiler ladle cause metal seal cracking, and ash leakage, overtemperature and the like of a large boiler top are generated.

When the boiler is operated, the big bag of the boiler is always in a positive pressure state, and the maintenance of the big bag have important significance for the long-term operation of the boiler equipment. Generally, the large package is detected and maintained periodically to prevent leakage and other safety accidents. Meanwhile, the surface of the big bag is required to be subjected to anti-corrosion treatment so as to prolong the service life of the big bag.

In the process of use, the tensile strength of the original sealing material is insufficient, the structural design defect of the original boiler ladle, the combustion coal type of the boiler and the design coal type are different, and the metal sealing is torn due to improper installation and other reasons of the original metal sealing structure during the construction, so that the ash and air leakage phenomenon is caused:

The traditional bale sealing treatment adopts a ceramic fiber blanket and a high-temperature adhesive, the tensile strength and the linear shrinkage rate of the ceramic fiber blanket are common, the viscosity of the high-temperature adhesive is common, and the expansion of the boiler bale cannot be well resisted.

The China patent discloses a leakage monitoring system (authority number CN 219200732U) for a pressure-containing member of a big bag at the top of a coal-fired boiler furnace, which can timely find the leakage problem of the pressure-containing member at different positions in the big bag at the top of the coal-fired boiler furnace through a leakage monitoring pipe system and a leakage online acoustic wave monitoring system which are arranged at the top of the big bag at the top of the coal-fired boiler furnace, and can further monitor the change of the leakage steam flow of the pressure-containing member; the utility model provides a three-dimensional sealing structure of a large-ladle chamber of a boiler, which is used for guiding operation adjustment, preventing expansion of leakage accidents, creating favorable conditions for subsequent furnace shutdown and defect elimination, and ensuring stable and safe operation of the boiler by carrying out sealing treatment and reformation on the large-ladle of the furnace roof aiming at common tearing of an original metal seal after finding out that technical treatment is required and the large-ladle of the furnace roof is required.

Disclosure of utility model

The utility model aims to provide a three-dimensional sealing structure of a large boiler box, which aims to solve the problems in the prior art.

In order to achieve the above purpose, the present utility model provides the following technical solutions:

The three-dimensional sealing structure of the large boiler box comprises a metal sealing plate and an expansion point, wherein the expansion point is arranged on the metal sealing plate at the outer side of the boiler, the expansion point is sealed through a flexible sealing structure, the flexible sealing structure consists of a metal seal and a flexible seal, the metal seal is a metal sealing box, the metal sealing box surrounds the expansion point, the metal sealing box is welded on the metal sealing plate through steel nails, and steel nails are uniformly arranged at the outer side of the metal sealing box;

The bottom of the metal sealing box is poured with micro-expansion refractory plastic, the upper side of the micro-expansion refractory plastic is provided with a flexible sealing structure, a stainless steel net is covered on the flexible sealing structure, the expansion of the boiler can be better dynamically absorbed, and the flexible sealing structure is paved with at least 3 layers of Sila carpets.

Preferably, the metal seal case is annular.

Preferably, nano-silica gel is coated between each layer of the sira blanket and between the sira blanket and the surface of the metal piece, and the nano-silica gel enables the sira blanket and the metal piece to form a tightly combined three-dimensional flexible whole.

Preferably, the expansion point is located in the central portion of the flexible sealing structure.

Preferably, the distance between the steel nails is 20-35 cm.

Preferably, the steel nails are arranged in a staggered manner along the upper side of the metal sealing ring.

Preferably, the steel nails fix the outer edge of the stainless steel mesh.

Preferably, the sira blanket adopts a smooth transition and natural forming paving mode.

Preferably, the expansion points are located on the sides of the pressure-bearing pipe or other boss.

Preferably, holes for the protrusions to pass through are formed in the stainless steel mesh, the flexible sealing structure is pressed on the metal sealing box and the metal sealing plate, and the sealing is performed by adopting the sira blanket and the nano silica gel, so that the sealing effect is not affected.

Compared with the prior art, the utility model has the beneficial effects that:

The novel material is adopted to treat the sealing problem of the large ladle of the boiler, and the novel material has the characteristics of better tensile strength, better viscosity and the like, so that the expansion of the boiler can be better dynamically absorbed, the metal sealing structure is prevented from being pulled apart, the problem of ash leakage of the large ladle of the boiler is thoroughly solved, meanwhile, the power consumption of a draught fan is reduced, dust pollution and the like are reduced, the heat dissipation capacity of the good large ladle sealing structure can be better reduced, and the economic efficiency of a coal-fired unit is improved.

The boiler ladle treatment adopts a structure combining metal sealing and flexible sealing, and the flexible sealing can not damage the original metal sealing structure of the boiler.

The flexible seal adopts a three-dimensional flexible seal mode, and all expansion points possibly generated, namely leakage points, are arranged at the center point of the flexible seal structure, so that the sira blanket can fully absorb the expansion.

The flexible seal can be sealed on metal seal by adopting a Sila blanket and nano silica gel, and the seal layer is integrally fixed outside by adopting a high-temperature-resistant stainless steel net 4, so that the phenomena of better absorption and expansion, ash leakage caused by cracking of the metal seal and the like are avoided.

Drawings

Fig. 1 is a schematic structural view of a first embodiment of a three-dimensional sealing structure for a large boiler chamber.

Fig. 2 is a schematic top view of a three-dimensional sealing structure of a large boiler chamber.

Fig. 3 is a schematic structural view of a second embodiment of a three-dimensional sealing structure for a large boiler chamber.

In the figure: 1. a metal seal case; 2. steel nails; 3. a sira blanket; 4. stainless steel mesh; 11. expansion points; 12. and (5) a metal sealing plate.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Example 1

Referring to fig. 1-2, in the embodiment of the utility model, a three-dimensional sealing structure of a large boiler box comprises a metal sealing plate 12 and an expansion point 11 of the large boiler box, wherein the expansion point 11 is arranged on the metal sealing plate 12 at the outer side of the boiler, the expansion point 11 is sealed through a flexible sealing structure, the expansion point 11 is arranged at the central part of the flexible sealing structure, the flexible sealing structure is composed of metal sealing and flexible sealing, the metal sealing is a metal sealing box 1, the metal sealing box 1 surrounds the expansion point 11, the metal sealing box 1 is annular, the metal sealing box 1 is welded on the metal sealing plate 12 through steel nails 2, steel nails 2 are uniformly arranged at the outer side of the metal sealing box 1, the steel nails 2 fix the outer edge of a stainless steel net 4, and the intervals between the steel nails 2 are 20-35 cm and are arranged in a staggered manner along the upper side of the metal sealing ring;

The bottom of the metal sealing box 1 is poured with micro-expansion refractory plastic, the upper side of the micro-expansion refractory plastic is provided with a flexible sealing structure, a stainless steel net 4 is covered on the flexible sealing structure, the expansion of the boiler can be better dynamically absorbed, the flexible sealing structure is paved with at least 3 layers of Sila carpets 3, nano silica gel is smeared between each layer of the Sila carpets 3 and between the Sila carpets 3 and the surface of a metal piece, the nano silica gel enables the Sila carpets 3 and the metal piece to form a tightly combined three-dimensional flexible whole, and the Sila carpets 3 adopt a smooth transition and natural molding paving mode.

The working principle of the utility model is as follows:

Sira blanket 3: the compact cotton blanket is higher in tensile strength and lower in ventilation rate than common heat-insulating cotton, the sira blanket 3 is a main material for large-package flexible sealing treatment, the tensile strength and the permanent linear shrinkage rate of the sira blanket 3 are both superior to those of common ceramic fiber blankets, in the use process, the blanket 3 can better resist the expansion of a large package of a boiler, and the blanket 3 has high temperature resistance, low heat conductivity and low specific heat, and is superior to the common ceramic fiber blanket in wind erosion resistance, compression rebound rate and ductility.

Nano silicone gel: the nanometer silica gel is FLR nanometer silica gel, and is a high-temperature adhesive containing silicon-aluminum components and matched with the Siro blanket 3, and has the same source and affinity with the Siro blanket 3, so that the nanometer silica gel is matched with the Siro blanket 3 under the high-temperature condition, has better adhesive property, is not corrosive, and is relatively more environment-friendly and safer. The FLR nano silicone gel is an adhesive between the Sila carpets 3 and the metal component, and the heat-resistant temperature and the viscosity (the viscosity is more than or equal to 3600 cps) of the FLR nano silicone gel are better than the common adhesive (the viscosity is more than or equal to 1200 cps). Has good affinity with both the sialon blanket 3 and the metal member and can be cured at room temperature without special heating. The FLR nano-silica gel is a special viscous colloid, is prepared from a plurality of special adhesive components and refractory materials, has stronger adhesion after solidification, and the main components thereof include Si, PVI, al O3 and the like, thereby greatly increasing the affinity between the Sila blanket 3 and the FLR nano-silica gel. The FLR nano silica gel has the use temperature similar to that of the Sila blanket 3, has good cohesiveness at high temperature, has neutral pH value and has no corrosiveness to metal members of a boiler. The FLR nano silica gel enables the Tilapia blanket 3 and the metal component to form a tightly combined three-dimensional flexible whole.

Application example one:

boiler profile:

The main boiler equipment of a 1050MW coal-fired steam turbine generator unit of a certain power plant is manufactured by Oriental boiler (group) Co. Boiler model: DG 3130/27.46-type II 2 boiler. The boiler type is a pi-type boiler with high-efficiency ultra-supercritical parameter variable pressure direct current furnace, a butt-firing mode, solid slag discharge, single hearth, one-time intermediate reheating, balanced ventilation, open air arrangement, an all-steel framework and a full suspension structure.

After the boiler is subjected to several times of cold and hot working condition transformation, the factors such as large cold and hot state displacement change, large thermal stress change, insufficient expansion of the metal seal and the like of components at each part of the big ladle of the boiler cause the cracking of the metal seal, and the ash leakage, overtemperature and the like of the big ladle of the furnace top occur. Therefore, the large ladle of the boiler needs to be comprehensively treated in a sealing way in 2023, and the problems of ash leakage and the like are thoroughly solved.

The ladle sealing construction process comprises the following steps:

1, clearing up the obstacles such as original heat preservation, dust and the like existing on the construction area, and achieving the degree of finding out leakage points.

And 2, checking the original sealing condition, and repairing the leakage point, the welding off, the breakage and the like.

3, The sealing design is a three-dimensional plastic flexible sealing structure, all the expansion points 11 of the boiler are arranged at the center part of the sealing layer, and the sira blanket 3 is laid in a smooth transition and natural molding mode.

4 Stainless steel nails 2 are welded on the original metal sealing box 1 at intervals of 250mm, the lengths of the steel nails 2 are 80mm, the intervals are 20-35 cm, and the steel nails are arranged in a staggered mode.

5, Paving at least 3 layers of Sila carpets, and coating FLR nano-silica gel between the layers and on the surfaces of the Sila carpets 3 and the metal piece. The part of the metal sealing box 1 is poured with high-temperature micro-expansion fireproof plastic in advance, and the sira blanket 3 is filled with FLR nano silica gel.

And 6, the stainless steel net 4 is additionally arranged on the outermost layer of the sira blanket 3, so that the integral strength of the sealing structure is improved.

7, The sealing treatment of the big ladle is carried out on the basis of the original boiler design without damaging the original design structure of the boiler, and comprises various pressure-bearing pipelines, metal plates and other parts.

Benefits after transformation:

Coal saving benefit: after the sealing treatment of the furnace top big ladle, the temperature in the furnace top big ladle is reduced, thereby reducing the heat loss. The heat dissipation area of a large ladle of 1 1000MW unit boiler is about 1500 square meters, the temperature is reduced by 40 ℃, and the heat dissipation loss can be reduced in the following years according to 6000 hours of operation per year:

Q＝a2·DT·m·h

=9.8x40× 1500×6000= 35.28X108 (Kcal/year)

Folding standard coal: 35.28×108/7000=504 tons

The coal costs can be saved each year as:

504 ton x 800 yuan/ton = 403200 yuan

Electricity-saving benefit: assuming that the current of the induced draft fan is reduced by 20A and the induced draft fan operates for 6000 hours in year, the station service electricity is 0.35 yuan/(kW.h), the annual electricity saving is as follows:

6000×20×6000/1000 x 0.35 x 2 = 504000 yuan

Heat saving benefit: the heat economy of one year is saved by more than 200 ten thousand according to the calculation of 3% air leakage.

The cost of big bag sealing treatment: the sealing treatment cost of a 3000 t/h-level boiler is about 270 ten thousand yuan, the service life of the sealing treatment can reach 12 years, and the average annual expenditure is about 20 ten thousand.

Cost performance analysis: from the above comparison, it can be seen that the cost of sealing the boiler bale is still very significant compared to the cost savings. After the boiler bale of the 1050MW coal-fired steam turbine generator unit is subjected to sealing comprehensive treatment, the construction quality is good through cold and hot state acceptance, and the unit operates normally without ash leakage and air leakage.

By adopting the structure for sealing, the boiler expansion device has the characteristics of better tensile strength, better viscosity and the like, can better dynamically absorb the expansion of the boiler, avoid the metal sealing structure from being pulled apart, further thoroughly solve the problem of ash leakage of the large boiler package, simultaneously reduce the power consumption of a draught fan, reduce dust pollution and the like, and the good large package sealing structure can also better reduce the heat dissipation capacity, thereby being beneficial to improving the economy of the coal-fired unit.

The boiler ladle treatment adopts a structure combining metal sealing and flexible sealing, and the flexible sealing can not damage the original metal sealing structure of the boiler.

The flexible seal adopts a three-dimensional flexible seal mode, and all expansion points 11 which can be generated, namely leakage points, are arranged at the center point of the flexible seal structure, so that the sira blanket 3 can fully absorb expansion.

The flexible seal can be sealed on metal seal by adopting the Sila blanket 3 and the nano silica gel, and the seal layer is integrally fixed outside by adopting the high-temperature-resistant stainless steel net 4, so that the phenomena of better absorption and expansion, ash leakage caused by cracking of the metal seal and the like are prevented.

Example two

Referring to fig. 3, in the embodiment of the present utility model, the difference between the embodiment and the first embodiment is that the expansion point 11 is located on the side of the pressure-bearing pipeline or other protrusions, the stainless steel mesh 4 is provided with holes for the protrusions to pass through, so that the flexible sealing structure is pressed against the metal sealing box 1 and the metal sealing plate 12, and the sealing is performed by using the sira blanket 3 and the nano silicone gel, so that the sealing effect is not affected.

Application example two: sealing of wall-penetrating part in large-package range of boiler top of thermal power plant

① The sealing mode adopts a flexible sealing mode, all possible leakage points are necessarily arranged on the center point of the sealing layer in construction, the FLR nano silicone gel is used for firmly adhering the multi-layer sialon blanket 3 and the metal surface together, displacement caused by different expansion coefficients of metals at the joint of the multi-layer sialon blanket 3 in a thermal state is regulated and absorbed, the whole sealing structure is plastic, and the sealing layer of the sialon blanket 3 can completely absorb expansion in three directions.

② The sealing treatment must not destroy the original design structure and function of the boiler, and the engineering is carried out on the original sealing structure. The sealing material must not damage the original furnace roof body structure, including various pressure-bearing heated pipelines, metal plates, bearing suspenders and other parts. The sealing main material must have a temperature resistance of 1200 ℃ or higher and cannot have a corrosion effect on the metal structure.

③ The sealing layer of the laid sialon blanket 3 must be formed in a smooth transition and natural forming mode.

④ The total expansion of the sealing layers at the front cross and the positions of the ceiling and the two side walls should be not less than 900mm. The other parts of the ceiling penetrating pipes are completely covered with the sealing layer, the total sealing expansion amount is not less than 500mm (the sealing expansion in the height direction is 250mm, and the horizontal sealing expansion is 250 mm).

⑤ The 3 sealing layers of the Sila blanket laid at each part are not less than 3 layers, compaction, flatness and firmness are required between each layer, the joint bonding is realized, and single-layer joint and interlayer joint pressing are required, and the joint distance is not less than 150mm. The FLR nano silicone gel is coated uniformly and completely on the contact surface of the sira blanket 3, the thickness is consistent, and the joint is also coated with high-temperature adhesive. The paving thickness of the sira blanket 3 is 25mm, 25mm and 25mm respectively.

⑥ For the parts which are easy to leak (such as the sealing of the front water-cooled wall and the ceiling pipe, the sealing of the ceiling pipe and the two side walls, and the like), a layer of nichrome steel net is firstly paved after a layer of the sialon blanket 3 is paved, and then the rest of the sealing layers of the sialon blanket 3 are paved.

⑦ Dirt such as dust, greasy dirt, rust and the like existing on a construction area (an original metal sealing steel plate or a metal sealing box 1) should be cleaned in advance before construction, so that the pre-construction area is ensured to be clean and tidy. Meanwhile, the construction site obstacles are cleaned, and the area of the cleaned part is required to be far larger than that of the construction part.

⑧ After the construction area is cleaned, the seller must carry out careful inspection, for example, the original metal seal is found to have the defects of cracks, welding seam cracking or welding leakage and the like, and the seal welding is required to be completed again; the casting material is damaged and needs to be poured again. After the buyer and the seller are accepted together, the flexible sealing work can be carried out in the next step. In some special parts such as front intersections or larger cracks, W-shaped expansion joints are arranged or two steel plates are welded on two sides, and an overlap joint structure is formed in the middle, so that the sealing heat insulation material is prevented from being directly washed by smoke.

⑨ The working surface to be modified and repaired is subjected to rust removal and polishing work on the parts below 300mm of the exposed parts of the metal sealing plate 12 and the wall penetrating roof pipe on the basis of cleaning, so that the repaired working surface is in a dust particle-free and rust-free state, and the working surface can be subjected to next work after being accepted by both parties.

⑩ The stainless steel nails 2 are welded on the working surface to be repaired, and the main function of the stainless steel nails is to fix the diamond-shaped stainless steel net 4. The length of the steel nails 2 is about 120mm, the spacing is 20-25 cm, the steel nails are arranged in staggered arrangement (according to the field condition), the number of steel nails is not less than 15 per square meter, and welding slag and the like are removed completely. The steel nails are required to be welded firmly on two sides, and arc striking and welding are forbidden on pressure-bearing members (tube panels, headers) or stress members (such as various hanging tubes, rods and the like).

The expansion amount of the absorption boiler is not less than 80mm at the wall penetrating pipe at each position, and the expansion amount of the absorption boiler is not less than 120mm at the front crossing position and the joint of the ceiling pipe and the two side walls according to the design of a construction drawing.

The steel mesh is used for completely covering the expanding Sizer sealing layer, and the overlapping of the steel mesh is not less than 100mm. The steel nets are connected by special mortise rings, square non-return steel sheets are used, and the steel nets are fixed on the steel nails 2 by round gaskets. And (3) passing steel wires between the pipes in the height direction of the pipe row to firmly tie the external steel mesh.

The construction process is strictly carried out according to safety measures and technical standards, and wall temperature measuring points, transmission lines and the like cannot be damaged.

Rust removal and polishing requirements of a sealing working face: no rust, no stain and no oil stain. The polishing part should exceed the construction part by about 10%. And (3) injection: the metal tube must retain its original rust inhibitive paint.

The Sila blanket laying requirement: the FLR nano-silica gel is required to be coated between each layer of the sialon blanket and between the sialon blanket and the metal working surface, the coating requirements of the FLR nano-silica gel are uniform, the thickness is consistent, and the sialon blanket is completely covered; compacting and paving are required to be carried out among all layers of the sira carpets, and staggered joints are required to be carried out among the sira carpets, wherein the staggered joint distance is not less than 150mm; FLR nano silicone gel is also required to be smeared at the seam of the Sila blanket.

The laying requirements of the nickel-chromium-manganese soft net are as follows: the soft nickel-chromium-manganese net is paved flatly and fixed at intervals by square non-return gaskets. The square backstop gasket and the fixed gasket must compress tightly the steel mesh, must not have the clearance between them, and the unnecessary steel nail 2 outside the fixed gasket must be welded on the fixed gasket to sealed steel nail 2.

The diamond stainless steel net 4 is laid and fixed: the steel mesh is paved, the sealing layer is compacted, fixed and smooth, the edge warping phenomenon is avoided, the butt joint is firm, the sealing layer is tightly attached and completely covered, and the lap joint between the steel meshes is not less than 100mm. After the steel mesh is laid, all flexible sealing parts are subjected to plastering treatment, and plastering quality is checked and accepted according to national plastering quality standards.

The foregoing is only a preferred embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any person skilled in the art, who is within the scope of the present utility model, should make equivalent substitutions or modifications according to the technical scheme of the present utility model and the inventive concept thereof, and should be covered by the scope of the present utility model.

Claims (10)

1. The three-dimensional sealing structure of the large boiler box comprises a metal sealing plate (12) and an expansion point (11) of the large boiler box, wherein the expansion point (11) is arranged on the metal sealing plate (12) at the outer side of the boiler, and the three-dimensional sealing structure is characterized in that the expansion point (11) is sealed through a flexible sealing structure, the flexible sealing structure is composed of metal sealing and flexible sealing, the metal sealing is a metal sealing box (1), the metal sealing box (1) surrounds the expansion point (11), the metal sealing box (1) is welded on the metal sealing plate (12) through steel nails (2), and the steel nails (2) are uniformly arranged at the outer side of the metal sealing box (1);

the bottom of the metal sealing box (1) is poured with micro-expansion fireproof plastic, the upper side of the micro-expansion fireproof plastic is provided with a flexible sealing structure, a stainless steel net (4) covers the flexible sealing structure, and the flexible sealing structure is composed of at least 3 layers of Sila carpets (3) paved.

2. The three-dimensional sealing structure of a large boiler box according to claim 1, wherein the metal sealing box (1) is annular.

3. The three-dimensional sealing structure of a large boiler box according to claim 2, wherein nano silicone gel is smeared between each layer of the sira blanket (3) and between the sira blanket (3) and the surface of a metal piece.

4. The three-dimensional sealing structure of a boiler large box according to claim 1, characterized in that the expansion point (11) is arranged at the central part of the flexible sealing structure.

5. The three-dimensional sealing structure of a large boiler box according to claim 1, wherein the distance between the steel nails (2) is 20-35 cm.

6. The three-dimensional sealing structure of the large boiler box according to claim 5, wherein the steel nails (2) are arranged in a staggered manner along the upper side of the metal sealing ring.

7. The three-dimensional sealing structure of a large boiler box according to claim 5, wherein the steel nails (2) fix the outer edge of the stainless steel mesh (4).

8. The three-dimensional sealing structure of a large boiler box according to claim 1, characterized in that the sira blanket (3) adopts a smooth transition, natural forming laying mode.

9. A three-dimensional sealing structure for a large boiler box according to claim 1, characterized in that the expansion points (11) are located on the sides of pressure-bearing pipes or other protrusions.

10. The three-dimensional sealing structure of a large boiler box according to claim 1, wherein holes for protrusions to pass through are formed in the stainless steel mesh (4).