Structure and Construction Method of Anti-coking Coating on Heating Surface of Gasifier

Abstract

This invention belongs to the field of coal gasification equipment protection technology, specifically relating to the anti-coking coating structure and construction method of the heating surface of a gasifier. Along the height of the gasifier, blank zones and coated zones are alternately distributed on the heating surface. The coated zone includes an anti-corrosion layer and an anti-coking layer. The anti-corrosion layer is disposed on the heating surface of the gasifier, and the anti-coking layer is disposed on top of the anti-corrosion layer, with the anti-coking layer and the anti-corrosion layer interlocking together. The surface of the blank zone undergoes micro-arc oxidation treatment. This invention improves the anti-corrosion and anti-coking performance of the coating and solves the problem of interlayer peeling in traditional structures.

Description

Technical Field

[0001] This invention belongs to the field of protection technology for coal gasification equipment, specifically relating to the anti-coking coating structure and construction method of the heating surface of the gasifier. Background Technology

[0002] A gasifier is a device that converts solid fuels (such as coal) into gaseous fuels under high temperatures and other conditions. The gaseous fuels mainly contain carbon monoxide, hydrogen, methane, and other components. Gasifiers are widely used in energy, chemical, and other fields. The gasification process is based on thermochemical conversion, where fuel reacts with a gasifying agent (such as steam or air) at high temperatures to produce syngas, a carbon-containing gas. The materials in a gasifier typically contain a certain amount of ash. The ash produced during combustion at high temperatures melts and adheres to the inner wall of the furnace or the heated surfaces, forming solid coke lumps, which is the coking problem.

[0003] To solve this problem, the traditional approach is to first prepare an anti-coking layer on the heated surface of the gasifier, and then prepare an anti-corrosion layer on top of the anti-coking layer. However, high-temperature molten slag can easily penetrate into the anti-corrosion layer, causing it to fail, and there is also the problem of peeling caused by the mismatch of thermal expansion between the layers. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an anti-coking coating structure for the heating surface of a gasifier and its construction method. The structure employs a zebra-type reverse gradient anti-coking coating and improves the composition of the anti-coking layer and the anti-corrosion layer, thereby solving the problems of coking and interlayer peeling.

[0005] The present invention is specifically implemented through the following technical solutions.

[0006] The gasifier's heating surface anti-coking coating structure comprises blank zones and coated zones alternately distributed along the height of the gasifier. Each coated zone includes an anti-corrosion layer and an anti-coking layer. The anti-corrosion layer is disposed on the gasifier's heating surface, and the anti-coking layer is disposed on top of the anti-corrosion layer. The anti-coking layer and the anti-corrosion layer are interlocked together. The surface of the blank zone is an Al2O3 self-cleaning film.

[0007] The anti-corrosion layer is composed of the following components by mass percentage: Cr3C2 60%~65%, NiCr alloy 15%~20%, Y2O3-ZrO2 10%~12%, and the balance is CeO2-HfO2 solid solution, totaling 100%; wherein, Y2O3-ZrO2 refers to ZrO2 doped with Y2O3, with a doping amount of 2mol%~3mol%; the mass ratio of Ce to Hf elements in the CeO2-HfO2 solid solution is 1:1~2; in the NiCr alloy, there are 80mol% Ni and 20mol% Cr.

[0008] The anti-coking layer is composed of the following components by mass percentage: 80%~85% Y2O3-ZrO2, with the balance being Cr2O3 nanocrystals, totaling 100%; wherein, Y2O3-ZrO2 refers to ZrO2 doped with Y2O3, with a doping amount of 7mol%~8mol.

[0009] Preferably, the surface of the anti-corrosion layer is uniformly distributed with cross-shaped grid grooves, and the side of the anti-coking layer near the anti-corrosion layer is embedded in the cross-shaped grid grooves to form a locking connection.

[0010] Preferably, the depth of each groove in the cross-shaped grid groove is 20±2μm, the width is 50±3μm, and the distance between two adjacent grooves is 200±5μm.

[0011] Preferably, the edge of each of the coated strips is processed into a smooth transition bevel of 30±2°, and the radius of the smooth transition bevel is 0.5±3mm.

[0012] Preferably, the ratio of the width of the coating strip to the width of the blank strip is 2:0.8~1.2.

[0013] Preferably, the thickness of the anti-corrosion layer is 50μm~200μm, and the thickness of the anti-coking layer is 50μm~200μm;

[0014] When the flue gas temperature in the gasifier is >1400℃, the thickness ratio of the anti-corrosion base layer to the anti-coking layer is 1:2.

[0015] When the flue gas temperature inside the gasifier is ≤1400℃, the thickness ratio of the anti-corrosion base layer to the anti-coking layer is 1:1.

[0016] Preferably, the self-cleaning film layer refers to an Al2O3 ceramic film with a thickness of 10μm~20μm generated on the surface of the blank zone through micro-arc oxidation.

[0017] The present invention also provides a construction method for the above-mentioned anti-coking coating structure on the heating surface of the gasifier, comprising the following steps:

[0018] S1. Matrix pretreatment:

[0019] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0020] S2. Blank band processing:

[0021] Al2O3 (10μm~20μm thick, contact angle greater than 150°) is generated on the heated surface after sandblasting through micro-arc oxidation.

[0022] S3. Coating tape application:

[0023] S31: Mask covers blank areas, cutout coating areas;

[0024] S32: Sprayed anti-corrosion coating;

[0025] S33: Laser-textured cross-shaped grid grooves;

[0026] S34: Apply anti-coking coating;

[0027] S4, Edge Processing:

[0028] Use a diamond grinding head to grind the edge of the coated strip into a smooth transition bevel of 30±2° (R=0.5mm).

[0029] Preferably, S2 specifically includes the following steps: depositing a pure aluminum layer on the heated surface after sandblasting using cold spray technology, followed by micro-arc oxidation treatment. The electrolyte composition is: Na2SiO3 8~15 g / L; NaOH 1~2 g / L; Na2WO4 2~5 g / L; glycerol 3~5 mL / L, with deionized water as the solvent; parameters: current density 5A / dm²~15 A / dm², frequency 400Hz~600Hz, duty cycle 30%~50%, time 20min~60min, and temperature 25℃~40℃.

[0030] Preferably, in S3, the specific operation of coating tape application is as follows:

[0031] S31: The mask covers the blank area, and the coating area is hollowed out. The boundary error of the coating area is ≤0.2mm.

[0032] S32: Spray anti-corrosion coating, single-pass spraying, pressure 1MPa~3MPa, spraying distance 150mm~160mm, spray gun moving speed: 250mm / s~300mm / s; powder particle size 15μm~45μm.

[0033] S33: Laser-textured cross-grid grooves, using fiber laser, cross-grid scanning mode, groove depth is 20±2μm, width is 50±3μm, and the distance between two adjacent grooves is 200±5μm; power: 110W~130W, frequency: 45kHz~55kHz, scanning speed: 400mm / s~500mm / s.

[0034] S34: On the structure formed in S33, spray an anti-coking layer: pressure 0.5~1MPa, spray gun distance 100mm~110mm, moving speed 350mm / s~400mm / s. Powder particle size: 10μm~55μm.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] This invention addresses the problems of coking and interlayer delamination on the heating surface of a gasifier by improving the structure, composition, and process of the functional layer. Specifically, it is reflected in:

[0037] (1) A reverse gradient structure design is carried out on the heating surface, that is, the design concept opposite to the traditional structure is adopted. First, an anti-corrosion layer is set on the heating surface, and then an anti-coking layer is set on the anti-corrosion layer. The anti-corrosion layer directly protects the substrate and isolates acidic gases such as H2S and SO2. The anti-coking layer is on the outermost side and can block the molten slag from contacting the anti-corrosion layer and avoid high-temperature failure.

[0038] (2) To improve the anti-corrosion effect and coking inhibition effect of the anti-corrosion layer, and to improve the interlayer bonding force, the present invention improves the composition, and the two compositions are compatible, which can improve the bonding force between the two layers. Specifically, the anti-corrosion layer of the present invention is composed of the following components by mass percentage: Cr3C2 60%~65%, NiCr alloy 15%~20%, 2mol%~3mol% Y2O3-ZrO2 10%~12%, and the balance is CeO2-HfO2 solid solution, totaling 100%; Cr3C2 has acid corrosion resistance and wear resistance, NiCr alloy is the binder phase, which improves the toughness of the material, and Y2O3-ZrO2 can form a eutectic interface with ZrO2 in the anti-coking layer. The anti-coking layer is composed of the following components by mass percentage: 7mol%~8mol% Y2O3-ZrO2 80%~85%, and the balance is Cr2O3 nanocrystals, totaling 100%. Y₂O₃-ZrO₂ is the main anti-coking phase, with Cr₂O₃ nanocrystals that can diffuse into the anti-corrosion layer. Cr, Zr, and O form chemical bridges, with oxygen atoms acting as bridging atoms, connecting Cr and Zr. Through the interaction of components in the anti-corrosion layer and the anti-coking layer, the interlayer bonding force can be improved.

[0039] (3) Based on the above design, the present invention further improves the interlayer bonding force by laser-texturing cross-grid grooves on the surface of the anti-corrosion layer and then spraying an anti-coking layer, so that the anti-corrosion layer and the anti-coking layer are mechanically interlocked, thereby increasing the bonding area and improving the interlayer bonding force.

[0040] (4) The anti-corrosion layer and the anti-coking layer constitute the coating belt. Along the height direction of the gasifier, the coating belt and the blank belt are alternately distributed. The coating belt is used to cover the core coking area, and the blank belt is used for stress release. The surface of the blank belt is treated with micro-arc oxidation to form an Al2O3 ceramic film self-cleaning surface. The edge of the coating belt is processed into a 30±2° rounded transition bevel with a radius of 0.5±3mm. The rounded transition bevel can eliminate edge stress concentration, improve thermal cycle life, and also prevent flue gas eddies from peeling off the coating edge.

[0041] Through the above-mentioned structural design, composition design and process design, the present invention improves the anti-corrosion and anti-coking performance of the coating, and has strong interlayer bonding force. The process is easy to implement and is suitable for large-scale application. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the inverse gradient structure.

[0043] Figure 2 This is a schematic diagram of the zebra-patterned arrangement of the heated surfaces.

[0044] Figure 3 This is a schematic diagram showing the interlocking connection between the anti-corrosion layer and the anti-coking layer.

[0045] Figure 4 This is a photo of the actual product after six months of use on the heated surface of Comparative Example 4.

[0046] Figure 5 This is a photograph of the heated surface of Example 1 after 24 months of use. Detailed Implementation

[0047] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention. Unless otherwise specified, the experimental methods and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials described are commercially available.

[0048] This invention addresses the problem of coking easily on the inner wall of gasifiers and proposes an improved solution. It is important to note that the functional layer in this invention, set on the heating surface, is the opposite of the traditional design approach. The traditional process involves first setting an anti-coking layer on the heating surface substrate, followed by an anti-corrosion layer. While this structure can provide some short-term effectiveness, as the gasifier is used for an extended period, high-temperature molten slag adheres to the inner wall of the furnace and easily penetrates into the anti-corrosion layer, causing it to fail. Furthermore, due to the mismatch in thermal expansion between the anti-corrosion layer and the anti-coking layer, delamination occurs.

[0049] Based on the above problems, this invention proposes an anti-coking coating structure for the heating surface of a gasifier, such as... Figure 1 and Figure 2 As shown, the structure is specifically as follows:

[0050] Along the height of the gasifier, blank strips 1 and coated strips 2 are alternately distributed on the heating surface 3 of the gasifier. The coated strip 2 includes an anti-corrosion layer 4 and an anti-coking layer 5. The anti-corrosion layer 4 is disposed on the heating surface 3 of the gasifier, and the anti-coking layer 5 is disposed on the anti-corrosion layer 4. The anti-coking layer 5 and the anti-corrosion layer 4 are interlocked together. The surface of the blank strip is a self-cleaning film layer.

[0051] It should be noted that this invention changes the approach by adopting a reverse gradient design. First, an anti-corrosion layer 4 is applied to the heated surface 3 of the gasifier. Then, an anti-coking layer 5 is applied on top of the anti-corrosion layer 4. The anti-coking layer 5 is in direct contact with the high-temperature environment, preventing the adhesion and penetration of high-temperature molten slag, blocking slag contact with the anti-corrosion layer, and avoiding high-temperature failure. The anti-corrosion layer 4 directly protects the substrate and isolates it from the erosion of acidic gases. The anti-corrosion layer 4 and the anti-coking layer 5 constitute a coating strip. Along the height direction of the gasifier, coating strips 2 and blank strips 1 are alternately distributed. Coating strip 2 is used to cover the core coking area, while blank strip 1 is used for stress release. The micro-arc oxidation of the blank strip provides self-cleaning capability (contact angle >150°).

[0052] In a preferred embodiment of the present invention, the self-cleaning film layer refers to an Al2O3 ceramic film with a thickness of 10μm~20μm generated on the surface of the blank strip through micro-arc oxidation.

[0053] To further improve the functionality of the anti-corrosion layer and the anti-coking layer, the present invention also improves the composition of these two functional layers. The improved composition not only has excellent anti-corrosion effect and coking inhibition performance, but also improves the bonding force between the anti-corrosion layer and the anti-coking layer at the composition level.

[0054] In a preferred embodiment of the present invention, the anti-corrosion layer of the present invention is composed of the following components by mass percentage: Cr3C2 60%~65%, NiCr alloy (specifically, the present invention uses 80mol%Ni-20mol%Cr) 15%~20%, 2mol%~3mol% Y2O3-ZrO2 (representing ZrO2 doped with Y2O3, with a doping amount of 2mol%~3mol%, specifically 3mol%) 10%~12%, and the balance being CeO2-HfO2 solid solution, totaling 100%; Cr3C2 has acid corrosion resistance and wear resistance, NiCr alloy is a binder phase that improves the toughness of the material, and Y2O3-ZrO2 can form a eutectic interface with ZrO2 in the anti-coking layer. The anti-coking layer is composed of the following components by mass percentage: 7 mol%~8 mol% Y₂O₃-ZrO₂ (representing ZrO₂ doped with Y₂O₃, with a doping amount of 7 mol%~8 mol%, specifically 8 mol% used in the examples and comparative examples below), 80%~85%, and the balance being Cr₂O₃ nanocrystals, totaling 100%. Y₂O₃-ZrO₂ is the main anti-coking phase, and Cr₂O₃ nanocrystals (200~300 nm) can diffuse into the anti-corrosion layer. Cr, Zr, and O form chemical bridges, with oxygen atoms acting as bridging atoms, connecting Cr and Zr. The interaction between the components in the anti-corrosion layer and the anti-coking layer can improve the interlayer bonding force. The CeO₂-HfO₂ solid solution is prepared by ball milling CeO₂ and HfO₂ nanoparticles at a mass ratio of 1:2, drying, pressing into sheets, and sintering at 1500℃ for 6 hours, resulting in a particle size of 50~70 nm.

[0055] To further enhance the bonding strength between the anti-corrosion layer and the anti-coking layer, this invention also utilizes laser texturing technology to create a mechanical interlocking bond between them, such as... Figure 3 As shown, in a preferred embodiment of the present invention, the surface of the anti-corrosion layer 4 is uniformly distributed with cross-shaped grid grooves 4-1, and the side of the anti-coking layer 5 near the anti-corrosion layer 4 is embedded in the cross-shaped grid grooves 4 to form a locking connection.

[0056] In a preferred embodiment of the present invention, each groove in the cross-shaped mesh groove 4-1 has a depth of 20±2μm and a width of 50±3μm, and the spacing between two adjacent cross-shaped mesh grooves is 200±5μm. The anti-coking layer is sprayed onto the cross-shaped mesh grooves of this size, with a portion of the anti-coking layer embedded within the grooves. On the one hand, compared to planar contact, this increases the bonding area by approximately 40%. On the other hand, this structure forms a locking structure, significantly improving the interlayer bonding strength to 35MPa (tested according to standard ASTM D4541).

[0057] In a preferred embodiment of the invention, the edge of each coating strip is further processed into a smooth transition bevel of 30±2°, with a radius of 0.5±3mm. This smooth transition bevel structure eliminates edge stress concentration, increasing thermal cycle life by 200%, and also prevents flue gas eddies from stripping the coating edges.

[0058] Preferably, the ratio of the width of the coated strip to the width of the blank strip is 2:1 ± 0.2. The coated strip and the blank strip are arranged alternately along the height to form a zebra-like structure, and the specific parameter rules are shown in Table 1.

[0059] Table 1 Zebra Parameter Rules

[0060]

[0061] Preferably, the thickness of the anti-corrosion layer is ≥50μm, and the thickness of the anti-coking layer is ≥50μm; the layer thickness ratio is adjusted according to the flue gas temperature.

[0062] When the flue gas temperature inside the gasifier is >1400℃, the ratio of the anti-corrosion layer to the anti-coking layer thickness is 1:2. When the flue gas temperature inside the gasifier is ≤1400℃, the ratio of the anti-corrosion layer to the anti-coking layer thickness is 1:1. See Table 2 for details.

[0063] Table 2 Relationship between flue gas temperature and layer thickness ratio

[0064]

[0065] The present invention also provides a construction method for the above-mentioned anti-coking coating structure on the heating surface of the gasifier, comprising the following steps:

[0066] S1. Matrix pretreatment:

[0067] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0068] S2. Blank band processing:

[0069] Al2O3 (preferably 15 μm thick, contact angle 152°) is generated on the heated surface after sandblasting through micro-arc oxidation.

[0070] S3. Coating tape application:

[0071] S31: Mask covers blank areas, cutout coating areas;

[0072] S32: Sprayed anti-corrosion coating;

[0073] S33: Laser-textured cross-shaped grid grooves;

[0074] S34: Apply anti-coking coating;

[0075] S4, Edge Processing:

[0076] Use a diamond grinding head to grind the edge of the coated strip into a smooth transition bevel of 30±2° (R=0.5±3mm).

[0077] Preferably, in S2, the specific operation steps of the micro-arc oxidation process are as follows: a pure aluminum layer (1~5μm) is deposited on the surface using cold spray technology, which is metallurgically bonded to the substrate and contains the Fe-Al phase. Micro-arc oxidation treatment is then performed. The electrolyte formulation is: Na2SiO3, 8~15 g / L; NaOH, 1~2 g / L; Na2WO4, 2~5 g / L; glycerol, 3~5 mL / L, with deionized water as the solvent. Parameters: current density 5~15 A / dm², frequency 400~600 Hz, duty cycle 30%~50%, time 20~60 min, temperature 25~40℃.

[0078] Preferably, in S3, the specific operation of coating tape application is as follows:

[0079] S31: Mask covers blank area, cuts out coating area, coating boundary error ≤0.2mm.

[0080] S32: Spray anti-corrosion coating, single-pass spraying, pressure 1~3MPa, spraying distance 150~160mm, spray gun moving speed: 250~300mm / s.

[0081] S33: Laser-textured cross-grid grooves, using fiber laser, cross-grid scanning mode, groove depth is 20±2μm, width is 50±3μm, and the distance between two adjacent grooves is 200±5μm; power: 110~130W, frequency: 45~55kHz, scanning speed: 400~500mm / s.

[0082] S34: On the structure formed by S33, spray an anti-coking layer: pressure 0.5~1MPa, spray gun distance: 100~110mm, moving speed: 350~400mm / s.

[0083] The invention will now be described in detail through the following embodiments and comparative examples.

[0084] Example 1

[0085] The anti-coking coating structure for the heating surface of the gasifier provided in this embodiment is used in high-temperature environments where the flue gas temperature is >1400℃.

[0086] Along the height of the gasifier, blank strips and coated strips are alternately distributed on the heating surface. The width W1 of the coated strip is 2000 mm, and the edge of each coated strip is machined with a 30° smooth transition bevel with a radius of 0.5 mm. The width W2 of the blank strip is 1000 mm, and the surface of the blank strip is coated with an Al2O3 ceramic film with a thickness of 15 μm formed by micro-arc oxidation. The coated strip includes an anti-corrosion layer and an anti-coking layer. The anti-corrosion layer is placed on the heating surface of the gasifier, and the anti-coking layer is placed on top of the anti-corrosion layer. The anti-coking layer and the anti-corrosion layer are interlocked. The thickness of the anti-corrosion layer is 60 μm, and the thickness of the anti-coking layer is 120 μm. The surface of the anti-corrosion layer has uniformly distributed cross-shaped grid grooves. The side of the anti-coking layer closest to the anti-corrosion layer is embedded in the cross-shaped grid grooves to form an interlocking connection. Each groove in the cross-shaped grid groove has a depth of 20 μm and a width of 50 μm, and the distance between two adjacent grooves is 200 μm.

[0087] The anti-corrosion layer consists of the following components by mass percentage: Cr3C 260%, NiCr alloy (80mol% Ni - 20mol% Cr) 20%, Y2O3-ZrO2 12%, and the balance being CeO2-HfO2 solid solution, totaling 100%; the powder particle size is 20μm~45μm. The anti-coking layer consists of the following components by mass percentage: 8mol% Y2O3-ZrO2 85%, and the balance being Cr2O3 nanocrystals, totaling 100%; the powder particle size is 20μm~55μm.

[0088] The present invention also provides a construction method for the above-mentioned anti-coking coating structure on the heating surface of the gasifier, comprising the following steps:

[0089] S1. Matrix pretreatment:

[0090] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0091] S2. Blank band processing:

[0092] Al2O3 (15 μm thick, contact angle 152°) was generated on the heated surface after sandblasting through micro-arc oxidation. The specific steps were as follows: a pure aluminum layer was deposited on the surface using cold spraying technology, metallurgically bonded to the substrate, containing the Fe-Al phase; followed by micro-arc oxidation treatment. The electrolyte formulation was: Na2SiO3, 10 g / L; NaOH, 1 g / L; Na2WO4, 3 g / L; glycerol, 4 mL / L; and deionized water as the solvent. Parameters: current density 10 A / dm², frequency 500 Hz, duty cycle 50%, time 40 min, with the temperature controlled within the range of 25–40 °C during the process.

[0093] S3. Coating tape application:

[0094] S31: The mask covers the blank area, and the coating area is hollowed out. The boundary error of the coating area is ≤0.2mm.

[0095] S32: Apply anti-corrosion coating, pressure 1MPa, single pass, spraying distance 150mm, spray gun moving speed: 300mm / s;

[0096] S33: Laser-textured cross-grid grooves, using fiber laser, cross-grid scanning mode, groove depth 20μm, width 50μm, spacing between two adjacent grooves 200μm; power: 120W, frequency: 450kHz, scanning speed: 500mm / s;

[0097] S34: On the structure formed by S33, spray an anti-coking layer at a pressure of 0.5 MPa, a spray gun distance of 100 mm, and a moving speed of 400 mm / s.

[0098] S4, Edge Processing:

[0099] Use a diamond grinding head to grind the edge of the coated strip into a smooth 30° bevel (R=0.5mm).

[0100] To highlight the advantages of the present invention, the following comparative examples are also provided.

[0101] Comparative Example 1

[0102] Compared with Example 1, the order of the anti-corrosion layer and the anti-coking layer in the coating belt is reversed, that is, the anti-coking layer is placed on the heating surface of the gasifier, and the anti-corrosion layer is placed on the anti-coking layer.

[0103] The specific construction method includes the following steps:

[0104] S1. Matrix pretreatment:

[0105] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0106] S2. Blank Zone Treatment: Al2O3 (15μm thick, contact angle 152°) is generated on the heated surface after sandblasting through micro-arc oxidation. The specific steps are as follows: A pure aluminum layer is deposited on the surface using cold spraying technology, metallurgically bonded to the substrate, containing the Fe-Al phase. Micro-arc oxidation is then performed. The electrolyte formulation is: Na2SiO3, 10 g / L; NaOH, 1 g / L; Na2WO4, 3 g / L; glycerol, 4 mL / L, with deionized water as the solvent. Parameters: Current density 10 A / dm², frequency 500 Hz, duty cycle 50%, time 40 min, with the temperature controlled within the range of 25~40℃ during the process.

[0107] S3. Coating tape application:

[0108] S31: The mask covers the blank area, and the coating area is hollowed out. The boundary error of the coating area is ≤0.2mm.

[0109] S32: Spraying anti-coking layer: pressure 0.5MPa, spray gun distance: 100mm, moving speed: 400mm / s.

[0110] S33: Laser-textured cross-grid grooves, using fiber laser, cross-grid scanning mode, groove depth is 20μm, width is 50μm, and the distance between two adjacent grooves is 200μm; power: 120W, frequency: 450kHz, scanning speed: 500mm / s.

[0111] S34: On the structure formed by S33, spray an anti-corrosion layer, single-pass spraying, pressure 1MPa, spraying distance 150mm, spray gun moving speed: 300mm / s.

[0112] S4, Edge Processing:

[0113] Use a diamond grinding head to grind the edge of the coated strip into a smooth 30° bevel (R=0.5mm).

[0114] Comparative Example 2

[0115] Compared to Example 1, the anti-corrosion layer and the anti-coking layer are not connected by interlocking, i.e., they are connected in a planar manner.

[0116] The construction method of Comparative Example 2 includes the following steps:

[0117] S1. Matrix pretreatment:

[0118] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0119] S2. Blank Zone Treatment: Al2O3 (15μm thick, contact angle 152°) is generated on the heated surface after sandblasting through micro-arc oxidation. The specific steps are as follows: A pure aluminum layer is deposited on the surface using cold spraying technology, metallurgically bonded to the substrate, containing the Fe-Al phase. Micro-arc oxidation is then performed. The electrolyte formulation is: Na2SiO3, 10 g / L; NaOH, 1 g / L; Na2WO4, 3 g / L; glycerol, 4 mL / L, with deionized water as the solvent. Parameters: Current density 10 A / dm², frequency 500 Hz, duty cycle 50%, time 40 min, with the temperature controlled within the range of 25~40℃ during the process.

[0120] S3. Coating tape application:

[0121] S31: The mask covers the blank area, and the coating area is hollowed out. The boundary error of the coating area is ≤0.2mm.

[0122] S32: Apply anti-corrosion coating by spraying, single-pass spraying, pressure of 1MPa, spraying distance of 150mm, and spray gun moving speed of 300mm / s.

[0123] S33: On the anti-corrosion layer formed in S32, spray an anti-coking layer: pressure 0.5MPa, spray gun distance: 100mm, moving speed: 400mm / s, thickness 120μm.

[0124] S4, Edge Processing:

[0125] Use a diamond grinding head to grind the edge of the coated strip into a smooth 30° bevel (R=0.5mm).

[0126] Comparative Example 3

[0127] Compared to Example 1, there is no zebra-shaped structure, i.e., no blank band is provided.

[0128] The specific construction method includes the following steps:

[0129] S1. Matrix pretreatment:

[0130] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0131] S2. Coating tape application:

[0132] S21: Spray anti-corrosion coating, single-pass spraying, pressure of 1MPa, spraying distance of 150mm, spray gun moving speed: 300mm / s;

[0133] S22: Laser-textured cross-grid grooves, using fiber laser, cross-grid scanning mode, groove depth 20μm, width 50μm, spacing between two adjacent grooves 200μm; power: 120W, frequency: 450kHz, scanning speed: 500mm / s;

[0134] S23: On the structure formed by S22, spray an anti-coking layer at a pressure of 0.5 MPa, a spray gun distance of 100 mm, and a moving speed of 400 mm / s.

[0135] Comparative Example 4

[0136] Using the traditional method, compared with Example 1, an anti-coking layer and an anti-corrosion layer are sequentially set on the heated surface, and they are in planar contact without any blank zones.

[0137] The specific construction method includes the following steps:

[0138] S1. Matrix pretreatment:

[0139] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0140] S2: Spray anti-coking layer, pressure 0.5MPa, spray gun distance: 100mm, moving speed: 400mm / s.

[0141] S3: On the structure formed in S2, spray an anti-corrosion layer, single-pass spraying, pressure 1MPa, spraying distance 150mm, spray gun moving speed: 300mm / s.

[0142] Example 2

[0143] The anti-coking coating structure for the heating surface of the gasifier provided in this embodiment is used in high-temperature environments with flue gas temperatures ≤1400℃.

[0144] Along the height of the gasifier, blank strips and coated strips are alternately distributed on the heated surface. The width W1 of the coated strip is 2000 mm, and the edge of each coated strip is machined into a 30° smooth transition bevel with a radius of 0.5 mm. The width W2 of the blank strip is 1000 mm, and an Al2O3 ceramic film with a thickness of 15 μm is formed on the surface of the blank strip through micro-arc oxidation.

[0145] The coating includes an anti-corrosion layer and an anti-coking layer. The anti-corrosion layer is disposed on the heating surface of the gasifier, and the anti-coking layer is disposed on top of the anti-corrosion layer. The anti-coking layer and the anti-corrosion layer are interlocked. The thickness of both the anti-corrosion layer and the anti-coking layer is 70 μm. The surface of the anti-corrosion layer has uniformly distributed cross-shaped grid grooves. The side of the anti-coking layer closest to the anti-corrosion layer is embedded in these cross-shaped grid grooves, forming an interlocking connection. Each groove in the cross-shaped grid groove has a depth of 20 μm and a width of 50 μm, and the distance between two adjacent grooves is 200 μm.

[0146] The anti-corrosion layer is composed of the following components by mass percentage: Cr3C 265%, NiCr alloy 20%, 3mol% Y2O3-ZrO2 10%, and the balance is CeO2-HfO2 solid solution, totaling 100%.

[0147] The anti-coking layer is composed of the following components by mass percentage: 8 mol% Y2O3-ZrO2 80%, with the balance being Cr2O3 nanocrystals, totaling 100%.

[0148] The present invention also provides a construction method for the above-mentioned anti-coking coating structure on the heating surface of the gasifier, comprising the following steps:

[0149] S1. Matrix pretreatment:

[0150] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0151] S2. Blank band processing:

[0152] Al2O3 (15μm thick, contact angle 152°) was generated on the heated surface after sandblasting through micro-arc oxidation. The specific steps of the micro-arc oxidation process are as follows: a pure aluminum layer containing Fe-Al phase was deposited on the surface using cold spraying technology and metallurgically bonded to the substrate. Micro-arc oxidation was then performed. The electrolyte formulation was: Na2SiO3, 10 g / L; NaOH, 1 g / L; Na2WO4, 3 g / L; glycerol, 4 mL / L, with deionized water as the solvent. Parameters: current density 10 A / dm², frequency 500 Hz, duty cycle 50%, time 40 min, and temperature controlled within the range of 25~40℃ during the process.

[0153] S3. Coating tape application:

[0154] S31: The mask covers the blank area, and the coating area is hollowed out. The boundary error of the coating area is ≤0.2mm.

[0155] S32: Spray anti-corrosion coating, single-pass spraying, pressure 1MPa, spraying distance 160mm, spray gun moving speed: 250mm / s, thickness 70μm;

[0156] S33: Laser-textured cross-grid grooves, using fiber laser, cross-grid scanning mode, groove depth 22μm, width 50μm, spacing between two adjacent grooves 200μm; Power: 110W, frequency: 45kHz, scanning speed: 400mm / s;

[0157] S34: On the structure formed in S33, spray an anti-coking layer (70μm thick): pressure 0.5MPa, spray gun distance: 100mm, moving speed: 350mm / s.

[0158] S4, Edge Processing:

[0159] Use a diamond grinding head to grind the edge of the coated strip into a smooth 30° bevel (R=0.5mm).

[0160] Example 3

[0161] The anti-coking coating structure for the heating surface of the gasifier provided in this embodiment is used in high-temperature environments with flue gas temperatures ≤1400℃.

[0162] Along the height of the gasifier, blank strips and coated strips are alternately distributed on the heated surface. The width W1 of the coated strip is 2020 mm, and the edge of each coated strip is machined into a 30° smooth transition bevel with a radius of 0.5 mm. The width W2 of the blank strip is 1010 mm, and an Al2O3 ceramic film with a thickness of 15 μm is formed on the surface of the blank strip through micro-arc oxidation.

[0163] The coating includes an anti-corrosion layer and an anti-coking layer. The anti-corrosion layer is disposed on the heating surface of the gasifier, and the anti-coking layer is disposed on top of the anti-corrosion layer. The anti-coking layer and the anti-corrosion layer are interlocked together. The thickness of both the anti-corrosion layer and the anti-coking layer is 60 μm. The surface of the anti-corrosion layer has uniformly distributed cross-shaped grid grooves. The side of the anti-coking layer closest to the anti-corrosion layer is embedded in these cross-shaped grid grooves, forming an interlocking connection. Each groove in the cross-shaped grid groove has a depth of 20 μm and a width of 50 μm, and the distance between two adjacent grooves is 200 μm.

[0164] The anti-corrosion layer is composed of the following components by mass percentage: Cr3C 265%, NiCr alloy 20%, 3mol% Y2O3-ZrO2 10%, and the balance is CeO2-HfO2 solid solution, totaling 100%.

[0165] The anti-coking layer is composed of the following components by mass percentage: 8 mol% Y2O3-ZrO2 85%, with the balance being Cr2O3 nanocrystals, totaling 100%.

[0166] The present invention also provides a construction method for the above-mentioned anti-coking coating structure on the heating surface of the gasifier, comprising the following steps:

[0167] S1. Matrix pretreatment:

[0168] The heating surface of the gasifier is sandblasted to Sa3 level (anchor pattern depth 50μm).

[0169] S2. Blank band processing:

[0170] Al2O3 (15μm thick, contact angle 152°) was generated on the heated surface after sandblasting through micro-arc oxidation. The specific steps of the micro-arc oxidation process are as follows: a pure aluminum layer containing Fe-Al phase was deposited on the surface using cold spraying technology and metallurgically bonded to the substrate. Micro-arc oxidation was then performed. The electrolyte formulation was: Na2SiO3, 10 g / L; NaOH, 1 g / L; Na2WO4, 3 g / L; glycerol, 4 mL / L, with deionized water as the solvent. Parameters: current density 10 A / dm², frequency 500 Hz, duty cycle 50%, time 40 min, and temperature controlled within the range of 25~40℃ during the process.

[0171] S3. Coating tape application:

[0172] S31: The mask covers the blank area, and the coating area is hollowed out. The boundary error of the coating area is ≤0.2mm.

[0173] S32: Spray anti-corrosion coating, single-pass spraying, pressure 1MPa, spraying distance 150mm, spray gun moving speed: 300mm / s, thickness 60μm;

[0174] S33: Laser-textured cross-grid grooves, using fiber laser, cross-grid scanning mode, groove depth 18μm, width 53μm, spacing between two adjacent grooves 200μm; Power: 130W, frequency: 55kHz, scanning speed: 500mm / s;

[0175] S34: On the structure formed in S33, spray an anti-coking layer (thickness 60μm): pressure 0.5MPa, spray gun distance: 100mm, moving speed: 400mm / s.

[0176] S4, Edge Processing:

[0177] Use a diamond grinding head to grind the edge of the coated strip into a smooth 30° bevel (R=0.5mm).

[0178] The performance of the anti-coking coating structures on the heated surfaces of the gasifiers prepared in the above embodiments and comparative examples was tested, and the results are shown in Tables 3 and 4. The interlayer bond strength was tested according to standard ASTM D4541.

[0179] Table 3 Comparison of Effects

[0180]

[0181] Using the same testing method as in Example 1, the performance of Examples 2 to 3 was measured and is shown in Table 4.

[0182] Table 4. Effect data of Examples 2-3

[0183]

[0184] As shown in Tables 3 and 4, Comparative Example 4 uses a traditional positive gradient coating structure. Compared to Comparative Example 4, Example 1 shows an increase in the anti-corrosion layer lifespan from a maximum of 8 months to over 24 months, and an increase in interlayer adhesion from 15 MPa to 35 MPa. This demonstrates the effectiveness of the interlayer strengthening technology in Example 1, which significantly improves interlayer adhesion. In Example 1, the blank zone provides space for stress release in the coated strip, helping to reduce stress damage. Furthermore, the blank zone forms a self-cleaning Al2O3 film through micro-arc oxidation, preventing ash adhesion. The scheme in Example 1 further increases steam production. Correspondingly, in Comparative Example 1, the order of the anti-corrosion layer and anti-coking layer in the coated strip is reversed compared to Example 1. However, it still suffers from the problems of Comparative Example 4, where the anti-corrosion layer is located on the outermost layer, making it susceptible to ash penetration and failure. In Comparative Example 2, the anti-corrosion layer and anti-coking layer are not interlocked, resulting in a significant decrease in interlayer adhesion. Comparative Example 3 lacks a zebra-like structure, i.e., no blank strip is provided. Consequently, the coated strip is damaged due to unreleased stress, reducing interlayer adhesion and affecting the coating's service life. Examples 2-4 exhibit performance similar to Example 1, achieving superior results compared to traditional coating solutions.

[0185] Figure 4 This is a photo of the actual product after six months of use on the heating surface of Comparative Example 4. Figure 5 These are actual photos of the heating surface of Example 1 after 24 months of use. As can be seen from the comparison, there is less coking in Example 1, which shows that the method of the present invention can effectively prevent coking on the heating surface of the gasifier.

[0186] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A structure of a heat surface anti-coking coating of a gasifier, characterized by, Alternately distributed with blank zone and coating zone along the height direction of the gasifier, the coating zone comprises anticorrosion layer and anti-coking layer, the anticorrosion layer is arranged on the gasifier heating surface, the anti-coking layer is arranged on the anticorrosion layer, and the anti-coking layer and the anticorrosion layer are locked together; the surface of the blank zone is Al2O3 self-cleaning film layer; The anticorrosion layer is composed of the following components in mass percentage: Cr3C2 60%~65%, NiCr alloy 15%~20%, Y2O3-ZrO2 10%~12%, and the balance of CeO2-HfO2 solid solution, totaling 100%; wherein Y2O3-ZrO2 refers to ZrO2 doped with Y2O3, and the doping amount is 2mol%~3mol%; the mass ratio of Ce element and Hf element in the CeO2-HfO2 solid solution is 1:1~2; The anti-coking layer is composed of the following components in mass percentage: Y2O3-ZrO2 80%~85%, and the balance of Cr2O3 nanocrystals, totaling 100%; wherein Y2O3-ZrO2 refers to ZrO2 doped with Y2O3, and the doping amount is 7mol%~8mol%.

2. The gasifier heating surface anti-coking coating structure according to claim 1, characterized by, The surface of the anticorrosion layer is uniformly distributed with cross grid grooves, and the side of the anti-coking layer close to the anticorrosion layer is embedded in the cross grid grooves to form a lock.

3. The gasifier heating surface anti-coking coating structure according to claim 2, characterized by, The depth of each groove in the cross grid groove is 20±2μm, the width is 50±3μm, and the distance between adjacent two grooves is 200±5μm.

4. The gasifier heating surface anti-coking coating structure according to claim 1, characterized by, The edge of each coating zone is processed into a 30±2° smooth transition bevel, and the radius of the smooth transition bevel is 0.5±3mm.

5. The gasifier heating surface anti-coking coating structure according to claim 1, characterized by, The width of the coating zone: the width ratio of the blank zone is 2:0.8~1.

2.

6. The gasifier heat surface anti-coking coating structure according to claim 1, characterized in that, The thickness of the anticorrosion layer is 50μm~200μm, and the thickness of the anti-coking layer is 50μm~200μm; When the flue gas temperature in the gasifier is >1400℃, the thickness ratio of the anticorrosion layer to the anti-coking layer is 1:2; When the flue gas temperature in the gasifier is ≤1400℃, the thickness ratio of the anticorrosion layer to the anti-coking layer is 1:

1.

7. The gasifier heating surface anti-coking coating structure according to claim 1, characterized by, The surface of the blank zone is Al2O3 ceramic film generated by micro-arc oxidation, and the thickness is 10μm~20μm.

8. The construction method of the gasification furnace heating surface anti-coking coating structure according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: Base body pretreatment: sand blasting the gasifier heating surface to Sa3 level; Blank zone treatment: generating Al2O3 film on the heating surface after sand blasting treatment by micro-arc oxidation; Coating zone construction: covering the blank zone with a mask, hollowing out the coating zone area, then spraying the anticorrosion layer; laser texturing cross grid grooves on the surface of the anticorrosion layer; then spraying the anti-coking layer; Edge processing: polishing the edge of the coating zone into a smooth transition bevel with a diamond grinding head.

9. The construction method according to claim 8, characterized in that, The blank strip treatment specifically comprises the following steps: depositing an aluminum layer on the heat receiving surface after sand blasting treatment by using a cold spraying technology, and then performing micro-arc oxidation treatment, the electrolyte composition being: Na2SiO38g / L~15g / L; NaOH 1g / L~2g / L; Na2WO42g / L~5g / L; glycerol 3mL / L~5mL / L, the solvent being deionized water; the parameters being: current density 5A / dm²~15 A / dm², frequency 400Hz~600 Hz, duty cycle 30%~50%, time 20min~60min, temperature 25℃~40℃.

10. The construction method according to claim 8, characterized in that, When the anticorrosion layer is sprayed, single pass spraying is performed, the pressure is 1MPa~3MPa, the spraying distance is 150mm~160mm, and the spray gun moving speed is 250mm / s~300mm / s; When the laser texture cross grid groove is formed, a fiber laser is used, a cross grid scanning mode is adopted, the depth of the groove is 20±2μm, the width of the groove is 50±3μm, the distance between two adjacent grooves is 200±5μm; the power is 110W~130W, the frequency is 45kHz~55kHz, and the scanning speed is 400mm / s~500mm / s; When the anti-coking layer is sprayed, the pressure is 0.5MPa~1MPa, the spray gun distance is 100mm~110mm, and the moving speed is 350mm / s~400mm / s.

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