Protective device for preventing high-temperature carbonization cracking of wide fins on high-temperature heating surface of once-through boiler

Abstract

The invention discloses a protection device for preventing high-temperature carbonization cracking of wide fins of a high-temperature heating surface of a once-through boiler, and relates to the field of fin protection devices, the protection device comprises a pipeline, the wide fins are installed on the side of the pipeline, patches are installed at damaged holes in the pipeline and the wide fins, and a supporting framework is welded to the installation patches and the wide fins. According to the method, firstly, abrasion-proof and explosion-proof inspection is conducted on a wide fin area of the high-temperature heating surface of the boiler, existing wide fin carbonization cracks are marked one by one through a marking pen and recorded, bench workers with the good technology are arranged to treat the cracks in a grouping mode, secondly, carbonization hole penetrating parts of the wide fins are repaired, a repairing mode of welding and installing patches is adopted, and the repair efficiency is improved. Furthermore, a high-temperature radiation prevention device framework (namely a supporting framework) is arranged, finally, a novel refractory material is laid outside the supporting framework, and the refractory material is made into a semi-elliptical shape, so that scouring and coke hanging of pulverized coal during operation of the boiler can be reduced, and high-temperature carbonization of the wide fins in the area can be prevented.

Description

Technical Field

[0001] This invention relates to the field of fin protection devices, specifically to a protection device for preventing high-temperature carbonization and cracking of wide fins on the high-temperature heating surface of a once-through boiler. Background Technology

[0002] A once-through boiler in a thermal power plant is a device that completes energy transfer by heating and evaporating water in a single pass. Powered by a feedwater pump, the feedwater sequentially passes through the economizer, the evaporating heating surface (water-cooled wall), and the superheater, transforming into superheated steam. It lacks a steam drum; the heating, evaporation, and superheating of the steam occur continuously within the heating surface, thus there are no fixed boundaries between these three stages. It's like a rapidly flowing river where water is continuously heated until it becomes steam. In a once-through boiler, the high-temperature heating surface is a crucial component. The boiler generates steam by the feedwater pump's pressure, passing through all the heating surfaces in a single pass. The high-temperature heating surface is the part of the boiler that directly contacts the high-temperature flue gas and bears the high-temperature heat load. Wide fins are additional heat dissipation structures added to these heating surfaces, typically welded from steel pipes and fins. The fins are relatively wide, and their main function is to increase the heating area and improve the boiler's heat exchange efficiency. Just like in a room, to dissipate or heat more quickly, increasing the area of ​​the heat exchange fins allows for faster heat transfer. In boilers, wide fins allow the heating surfaces to better absorb heat from the flame and flue gas, transferring the heat to the working fluid (water or steam) inside the tubes, thereby improving the overall performance of the boiler. In addition, the combination of wide fins and tubes forms a robust integral structure, improving the strength and rigidity of the entire water-cooled wall, enabling the boiler to better withstand high-temperature and high-pressure environments, extending its service life, and improving operational stability.

[0003] Carbonization is a complex chemical process that typically involves the thermal decomposition of organic compounds at high temperatures. When fin materials contain hydrocarbons or other organic components, these compounds decompose under high-temperature conditions, releasing volatile substances and leaving carbonaceous residues. This process is similar to combustion, but carbonization is more pronounced in oxygen-deficient or low-oxygen environments. Carbonization products are usually black or dark-colored solids. Carbonization is often accompanied by material embrittlement, and cracks easily form at the broken edges. These cracks may propagate under vibration or thermal cycling loads, leading to fin breakage.

[0004] Because the wide fins of the boiler water-cooled wall are exposed to high-temperature heat sources for a long time, large-area carbonization and cracking can occur, forming fin cracks that pose a safety hazard. To eliminate this hazard, the traditional approach is to repair the carbonized cracks or upgrade the material of the wide fins. However, the same problem will still occur during the next maintenance inspection. As the unit load changes during operation, the fin cracks may extend to the tubes. When the cracks penetrate the tube wall and cause leakage, the unit will be forced to shut down, resulting in significant economic losses.

[0005] Therefore, it is necessary to invent a protective device for preventing high-temperature carbonization and cracking of wide fins on the high-temperature heating surface of a DC boiler to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a protective device for preventing high-temperature carbonization cracking of wide fins on the high-temperature heating surface of a once-through boiler. This involves inspecting the wide fin area of ​​the boiler's high-temperature heating surface for wear and explosion protection, marking and recording each existing carbonization crack with a marker, and assigning skilled fitters in groups to treat the cracks. Next, areas where carbonization has perforated the wide fins are repaired using a welding patching method. Then, a high-temperature radiation protection device frame is installed. Finally, a new type of refractory material is laid on the outside of the support frame. This refractory material is semi-elliptical to reduce the scouring and coking of pulverized coal during boiler operation, thereby preventing high-temperature carbonization of the wide fins in this area. This addresses the problem mentioned in the background art where long-standing fin cracks can extend to the tubes during unit operation as the unit load changes, leading to leaks and forced unit shutdown, resulting in significant economic losses.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a protective device for preventing high-temperature carbonization cracking of wide fins on the high-temperature heating surface of a DC boiler, comprising a pipe, wide fins installed on the side of the pipe, patches installed at damaged holes on the pipe and wide fins, a supporting frame welded to the installation patches and wide fins, and refractory material coated on the pipe, wide fins, installation patches, and supporting frame. First, an anti-wear and explosion-proof inspection of the wide fin area of ​​the high-temperature heating surface of the boiler is conducted, and any existing carbonization cracks in the wide fins are marked and recorded. Skilled fitters are then assigned to work on the cracks in groups. Second, the carbonized perforations in the wide fins are repaired using welded installation patches. Third, a high-temperature radiation protection device frame (i.e., a supporting frame) is installed. Finally, a new type of refractory material is applied to the outside of the supporting frame. The refractory material is semi-elliptical in shape, which reduces the scouring and coking of pulverized coal during boiler operation, thereby preventing high-temperature carbonization of the wide fins in this area.

[0008] Preferably, the material of the installation patch is the same as that of the intact and undamaged wide fin. The installation patch is "H" shaped, and there are several installation patches in total, which are evenly spaced and distributed in a straight line. After eliminating the carbonized cracks in the wide fin, the oxide slag on the fin surface is thoroughly polished, and the pipe cuts are thoroughly inspected. Then, the carbonized perforations in the wide fin are repaired. The reused installation patch is a machined part that is scaled down by a certain proportion according to the original drawing size. The machining size is 8mm smaller along the edge based on the original wide fin size, which is a suitable size. Pressing the repaired installation patch onto the pipe can make the welded parts contact more tightly, reduce the generation of welding defects such as porosity and slag inclusions, improve welding quality, and ensure better connection strength between the wide fin and the pipe.

[0009] Preferably, the number of supporting frames is several. The supporting frames are made of high-temperature resistant alloy material, namely 15CrMo. The vertical height of the supporting frames from the wide fins outward is controlled at about 3cm to 3.5cm, which makes the arrangement robust, complementary, operable, and heat-resistant. The supporting frames adopt an array-type "V" structure arrangement. The supporting frames are arranged in "V" shapes in both the transverse and longitudinal directions in the horizontal direction. The characteristics of the V-shaped steel structure support frame can help improve the stability and seismic performance of the overall structure.

[0010] Preferably, the outer surface of the refractory material is made into a semi-elliptical shape to reduce the scouring and coking of coal powder during boiler operation. At the same time, the semi-elliptical outer surface can effectively reduce stress concentration. In high-temperature environments, refractory materials will undergo a process of thermal expansion and contraction, which may lead to stress inside the material. The semi-elliptical surface design can evenly distribute these stresses and avoid generating excessive stress at specific points, thereby reducing the risk of material cracking and damage.

[0011] The technical effects and advantages provided by the present invention in the above technical solution are as follows:

[0012] 1. This invention first involves inspecting the wear and explosion prevention of the wide fin area of ​​the boiler's high-temperature heating surface. Existing carbonization cracks in the wide fins are marked and recorded, and skilled fitters are assigned to work on the cracks in groups. Next, the carbonized perforations in the wide fins are repaired using a welding patching method. Then, a high-temperature radiation protection device frame (i.e., a support frame) is installed. Finally, a new type of refractory material is laid on the outside of the support frame. This refractory material is semi-elliptical in shape, which reduces the scouring and coking of coal dust during boiler operation, thereby preventing high-temperature carbonization of the wide fins in this area.

[0013] 2. The protective device for preventing high-temperature carbonization cracking of wide fins on the high-temperature heating surface of a once-through boiler fundamentally prevents the generation of numerous fin cracks due to high-temperature carbonization cracking on the wide fins. Through experimental application, this protective device, by shielding the furnace heat source from high-temperature radiation and convective heat transfer, prevents the furnace heat source from being directly transferred to the wide fins, effectively achieving the expected protective effect against high-temperature carbonization of the fins. It greatly reduces the generation of carbonization cracks on the heating surface and has significant practical value in preventing boiler leaks. It effectively solves the safety hazard of unplanned unit shutdowns caused by numerous carbonization cracks on the wide fins of the high-temperature heating surface of once-through boilers during operation. At the same time, it greatly reduces the workload of eliminating numerous wide fin cracks during the maintenance of the boiler's high-temperature heating surface, reduces secondary and hidden defects generated during the maintenance process, and greatly improves the reliability of thermal power unit operation. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0015] Figure 1 This is a perspective view of the overall structure of the present invention;

[0016] Figure 2 This is a three-dimensional view of the internal structure of the present invention (partially cut out).

[0017] Figure 3 A three-dimensional view of the overall structure of the installation patch for this invention;

[0018] Figure 4 A three-dimensional view of the overall structure of the support frame of the present invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] 1. Pipes; 2. Wide fins; 3. Installation patches; 4. Support frame; 5. Refractory materials. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] This invention provides, for example Figure 1-4The protective device for preventing high-temperature carbonization cracking of the wide fins on the high-temperature heating surface of the DC boiler shown includes a pipe 1, wide fins 2 installed on the side of the pipe 1, patches 3 installed at the damaged holes on the pipe 1 and the wide fins 2, a support frame 4 welded to the patch 3 and the wide fins 2, and refractory material 5 coated on the pipe 1, the wide fins 2, the patch 3 and the support frame 4.

[0023] First, an anti-wear and explosion-proof inspection was conducted on the wide fin area 2 of the boiler's high-temperature heating surface. All existing carbonization cracks in the wide fin 2 were marked and recorded. Skilled fitters were then assigned to work on the cracks in groups. Next, the carbonized perforations in the wide fin 2 were repaired using a welding patch 3 method. Then, a high-temperature radiation protection device frame (i.e., a support frame 4) was installed. Finally, a new type of refractory material 5 was laid on the outside of the support frame 4. The refractory material 5 was made in a semi-elliptical shape to reduce the scouring and coking of pulverized coal during boiler operation, thereby preventing high-temperature carbonization of the wide fin 2 in this area.

[0024] The installation patch 3 consists of several pieces. Because a specific height area of ​​the boiler experiences a stable high-temperature environment, concentrated heat load, and poor flue gas flow, these factors combined cause the fins at that location to operate under harsh conditions for extended periods, resulting in a concentrated area of ​​carbonized pores. Several installation patches 3 are evenly spaced and arranged in a straight line. The material of the installation patch 3 is the same as that of the intact, undamaged wide fin 2. The installation patch 3 is H-shaped. Pressing the repaired installation patch 3 onto the pipe 1 ensures a tighter contact at the welded joint, reducing welding defects such as porosity and slag inclusions. This method can effectively improve welding quality and ensure the connection strength between the wide fins 2 and the pipe 1. Furthermore, one of the main functions of the wide fins 2 is to increase the heat transfer area and enhance heat transfer. Pressing the patch 3 onto the pipe 1 for repair can ensure good thermal contact between the wide fins 2 and the pipe 1, maintain heat transfer efficiency, and avoid local heat transfer obstruction caused by improper repair, which would affect the overall thermal performance of the boiler. At the same time, it helps to restore the stability of the overall structure of the wide fins 2 and the pipe 1, so that they can better cooperate to withstand high temperature, high pressure and thermal stress during subsequent boiler operation, and prevent further damage caused by structural loosening.

[0025] There are several support frames 4. The support frames 4 are made of high-temperature resistant alloy material, namely 15CrMo. The vertical height of the support frames 4 from the wide fin 2 outward is controlled between 3cm and 3.5cm. The support frames 4 adopt an array-type "V" structure arrangement. The support frames 4 are arranged in a cross "V" shape in both the horizontal and vertical directions in the horizontal direction, which makes the arrangement have the characteristics of firmness, complementarity, operability and high temperature resistance.

[0026] The outer surface of the refractory material 5 is made into a semi-elliptical shape to reduce the scouring and coking of coal powder during boiler operation.

[0027] During use, firstly, the wear and explosion prevention of the wide fin 2 area of ​​the boiler's high-temperature heating surface is checked. The existing carbonization cracks of the wide fin 2 are marked with a marker and recorded. Then, skilled fitters are assigned to work on the cracks in groups. Cracks in the middle of the wide fin 2 were eliminated by grinding, with rounded corners to avoid leaving sharp-angled holes. Cracks near the pipe that were prone to damage were eliminated by drilling anti-crack holes. Next, after eliminating the carbonized cracks in the wide fin 2, the oxide slag on the surface of the wide fin 2 was thoroughly ground. A comprehensive inspection of the cuts on pipe 1 was conducted. After both parties approved the work, the carbonized perforations in the wide fin 2 were repaired. The new installation patch 3 used for this repair was a machined part scaled down from the original drawing dimensions. The machining dimensions were 8mm smaller along the edge from the original wide fin 2 dimensions, which was a suitable size and resulted in a good repair effect. Furthermore, after all the elimination of carbonized cracks and repair of carbonized holes in the wide fin 2 were completed, a comprehensive inspection was conducted. After both parties approved the work, the high-temperature radiation protection device frame (i.e., the support frame 4) was installed. This support frame 4 was made of high-temperature resistant alloy material (15CrM). The structure is composed of an array-type V-shaped arrangement, with V-shaped cross arrangements in both horizontal and vertical directions. The vertical height of the support frame 4 from the wide fins 2 outward is controlled at approximately 3cm to 3.5cm. This arrangement features robustness, complementarity, operability, and high-temperature resistance. After the support frame 4 is installed, a comprehensive inspection of the welding is conducted to confirm that there is no damage to the pipes, that the support frame 4 is firmly welded without any false welds, and that the arrangement of the support frame 4 is reasonable and does not affect expansion. After acceptance by both parties, the new refractory material 5 is laid on the outside of the support frame 4. The refractory material 5 is made into a semi-elliptical shape, which can reduce the scouring and coking of coal powder during boiler operation. This new material has high requirements for construction technology, and strict control of construction quality is necessary to prevent the plastic of the protective device from falling off during operation. The vertical height of the new high-temperature refractory material 5 from the fins outward is controlled at approximately 4cm to 5cm.

[0028] When making refractory material 5, dry mix fused silica powder, alumina powder, vermiculite powder, and hollow glass microspheres for 5 minutes until uniform. Add silica sol and aluminate coupling agent, disperse at high speed for 15 minutes to form a paste base. Slowly add dissolved CMC aqueous solution (pre-dissolved in hot water to a 5% solution) and deionized water, stir for 10 minutes, and finally add defoamer and stir for 2 minutes. Filter with a 100-mesh filter to remove coarse particle impurities to obtain the finished coating. Apply the finished refractory material 5 to the outside of the support frame 4 and scrape it to form a semi-elliptical shape.

[0029] This prevents the wide fins of the high-temperature heating surface of the once-through boiler from undergoing high-temperature carbonization cracking, thus preventing a large number of fin cracks from forming due to high-temperature carbonization cracking on the wide fins 2. Through experimental application, the protective device, by shielding the furnace heat source from high-temperature radiation and convective heat transfer, blocks the furnace heat source from being directly transferred to the wide fins 2, and truly achieves the expected protective effect against high-temperature carbonization of the fins. It greatly reduces the generation of carbonization cracks on the heating surface and has important practical value in preventing boiler leaks. It effectively solves the safety hazard of unplanned unit shutdown caused by a large number of carbonization cracks on the wide fins 2 of the high-temperature heating surface of the once-through boiler during operation. At the same time, it greatly reduces the workload of eliminating a large number of wide fin 2 cracks during the maintenance of the boiler's high-temperature heating surface, reduces secondary and hidden defects generated during the maintenance process, and greatly improves the reliability of thermal power unit operation.

[0030] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A protective device for preventing high-temperature carbonization cracking of wide-finned high-temperature heating surfaces in a DC boiler, comprising a pipe (1), characterized in that, Wide fins (2) are installed on the side of the pipe (1), and patches (3) are installed on the damaged holes of the pipe (1) and the wide fins (2). The installation patches (3) and the wide fins (2) are welded with a support frame (4). The pipe (1), the wide fins (2), the installation patches (3) and the support frame (4) are coated with refractory material (5).

2. The protective device for preventing high-temperature carbonization cracking of wide fins on the high-temperature heating surface of a DC boiler according to claim 1, characterized in that, The content material of the installation patch (3) is the same as that of the complete and undamaged wide fin (2), and the installation patch (3) is in the shape of "H".

3. The protective device for preventing high-temperature carbonization and cracking of wide fins on the high-temperature heating surface of a DC boiler according to claim 2, characterized in that, The installation patch (3) is provided in several pieces, and the several installation patches (3) are distributed in a straight line with equal spacing.

4. The protective device for preventing high-temperature carbonization and cracking of wide fins on the high-temperature heating surface of a DC boiler according to claim 1, characterized in that, The number of the support frame (4) is set in several, and the support frame (4) is made of high temperature resistant alloy material, namely 15CrMo.

5. The protective device for preventing high-temperature carbonization cracking of wide fins on the high-temperature heating surface of a DC boiler according to claim 4, characterized in that, The support frame (4) adopts an array-type "V" shaped structure arrangement, and the support frame (4) is arranged in a "V" shaped intersection in both the horizontal and vertical directions.

6. The protective device for preventing high-temperature carbonization cracking of wide fins on the high-temperature heating surface of a DC boiler according to claim 1, characterized in that, The outer surface of the refractory material (5) is made into a semi-elliptical shape.

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