Thermal barrier coating exhaust passage with anti-tempering function and mounting method

Abstract

The invention provides a thermal barrier coating exhaust passage with an anti-tempering function and an installation method, and relates to the technical field of thermal barrier coatings and diesel engine exhaust passages, the thermal barrier coating exhaust passage comprises an exhaust passage body, the exhaust passage body is coated with a thermal barrier coating, and the thermal barrier coating comprises a first bonding layer, a ceramic layer and a second bonding layer from outside to inside; the first bonding layer and the second bonding layer are made of the same material, an exhaust passage heat exchanger is installed on the exhaust passage body, and a spiral static mixer is installed on the inner side of the exhaust passage body, the exhaust passage with a spiral mixing structure is designed, mixing of incomplete combustion tail gas can be effectively promoted, in addition, a heat exchange channel is arranged on the outer side of the exhaust passage, and the heat exchange efficiency is improved. According to the design, heat transferred to the exhaust passage from the high-temperature cylinder cover can be reduced, heat on the high-temperature wall surface of the exhaust passage can be taken away, and the heat exchange passage and the exhaust passage are combined, so that the temperature of the wall surface of the exhaust passage is effectively reduced, and meanwhile, the situation that the local gas concentration is too high is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of thermal barrier coatings and diesel engine exhaust ducts, and in particular to a thermal barrier coating exhaust duct with anti-flashback function and an installation method thereof. Background Art

[0002] As diesel engine technology continues to develop in the direction of high reinforcement, light weight, compactness and low emissions, the exhaust duct, as a key heat load component, faces major challenges. Traditional cast iron and aluminum alloy materials can no longer meet the performance requirements of modern high-efficiency, low-emission diesel engines. Therefore, high-temperature nickel-based alloys and stainless steel materials have gradually become the first choice due to their excellent high strength and high temperature resistance. However, the low thermal conductivity of these materials causes the temperature of the inner surface of the exhaust duct to rise. If the cooling is insufficient, it will cause local high temperature, thermal damage and carbon deposition. In severe cases, the incompletely burned exhaust gas will enter the exhaust duct and flash back, which will affect the operating performance and reliability of the diesel engine. Therefore, it is usually used to reduce the heat load by coating the inner and outer walls of the exhaust duct with thermal barrier coatings or adding a cooling oil cavity in the cylinder head. However, the current exhaust duct optimization technology often has the following defects.

[0003] (1) After the thermal barrier coating is applied to the inner and outer walls of the exhaust duct, heat conduction is significantly reduced, resulting in an increase in the temperature of the exhaust duct wall. The high-temperature wall is in direct contact with the exhaust gas, which can easily ignite the residual fuel and accelerate the flame propagation and oxidation reaction, thereby increasing the risk of flame flashback in the exhaust system.

[0004] (2) Although the addition of a cooling oil cavity in the cylinder head can effectively reduce the temperature of the exhaust duct wall, excessive cooling will lead to a large temperature difference, increase the heat load, and may cause thermal cracks under the coupling effect of high-pressure exhaust gas, thereby reducing the fatigue strength of the exhaust duct.

[0005] (3) The cooling oil cavity in the cylinder head will remove a large amount of heat generated by the cylinder head. However, since the cylinder head is in direct contact with the combustion chamber, excessive heat dissipation in the cooling oil cavity may cause a significant drop in the temperature of the combustion chamber. This temperature drop will affect the efficiency of the combustion process, thereby significantly reducing the overall thermal efficiency of the diesel engine. In addition, excessive heat dissipation may also lead to incomplete combustion of the fuel, increasing exhaust emissions and fuel consumption.

[0006] (4) The cooling oil cavity in the cylinder head will have a significant impact on the structure of the cylinder head. Due to the presence of the cooling oil cavity, the overall mechanical strength of the cylinder head is reduced. This structural weakening may cause the cylinder head to be prone to deformation or cracking under high temperature and high pressure environment, thereby affecting the normal operation and reliability of the diesel engine. In addition, the reduction in mechanical strength may also lead to a series of serious consequences, including seal failure, combustion chamber pressure leakage and potential engine damage. Therefore, the present invention proposes a thermal barrier coating exhaust duct with anti-backfire function and an installation method to solve the problems existing in the prior art. Summary of the invention

[0007] In view of the above problems, the purpose of the present invention is to propose a thermal barrier coating exhaust duct with anti-flashback function and an installation method. This thermal barrier coating exhaust duct with anti-flashback function and an installation method can effectively promote the mixing of incomplete combustion exhaust gas and solve the problems existing in the prior art.

[0008] To achieve the purpose of the present invention, the present invention is implemented through the following technical scheme: a thermal barrier coating exhaust duct with anti-flashback function, comprising an exhaust duct body, the exhaust duct body is coated with a thermal barrier coating, the thermal barrier coating is respectively a first bonding layer, a ceramic layer and a second bonding layer from the outside to the inside, the first bonding layer and the second bonding layer are made of the same material, an exhaust duct heat exchanger is installed on the exhaust duct body, and a spiral static mixer is installed on the inner side of the exhaust duct body.

[0009] A further improvement is that the exhaust duct heat exchanger comprises an exhaust duct heat exchange wall and heat exchange holes, the exhaust duct heat exchange wall is provided with heat exchange holes, and the heat exchange holes are evenly arranged in a plurality of groups, and the plurality of groups of heat exchange holes are connected.

[0010] A method for installing a thermal barrier coating exhaust duct with an anti-flashback function, characterized in that it comprises the following steps:

[0011] Step 1: Clean the inner and outer walls of the exhaust duct

[0012] Use sandpaper to polish and remove the surface residues on the inner and outer wall areas of the exhaust duct body to ensure that the wall surface is smooth and flat, then rinse with deionized water, dehydrate with alcohol and blow dry;

[0013] Step 2: Installation of spiral mixer and exhaust duct heat exchanger

[0014] Install the spiral mixer into the exhaust duct bend, then heat the outer wall of the exhaust duct to 100°C through an external heating device, evenly apply the thermal conductive glue on the outer wall of the exhaust duct, and then install the exhaust heat exchanger and cool it naturally at room temperature until the wall is completely fitted;

[0015] Step 3: Treatment of cylinder head

[0016] Prepare the cylinder head where the exhaust duct body needs to be installed, and use sandpaper to polish the exhaust duct cavity of the cylinder head, and then drill a hole from the top of the cylinder head to the exhaust duct cavity;

[0017] Step 4: Prepare bonding layer materials

[0018] High-density polyethylene powder, NiCrAlY alloy powder and 0.1-0.2wt% high-purity Dy powder are mixed by mechanical mixing for 15 minutes, and after mixing evenly, the powder is placed in a high-temperature oven for baking;

[0019] Step 5: Prepare ceramic layer materials

[0020] Pour YSZ powder into 400-500 ml high-purity ethanol and place it in an ultrasonic cleaning machine to form a YSZ suspension, add La(NO3)3·6(H2O) and ZrOCl2·8(H2O), stir evenly, add linear alkylbenzene sulfonate sodium, adjust the pH value, let it stand for 30-60 minutes, filter, put the precipitate into a thermoelectric furnace, and treat it at a high temperature of 500-600°C for 1 hour to obtain a mixed powder of YSZ and La2Zr2O7;

[0021] Step 6: Apply thermal barrier coating

[0022] A 100 μm bonding layer material is uniformly coated on the outer wall of the exhaust duct heat exchanger by plasma spraying, and then a 300 μm ceramic layer material is coated on the bonding layer surface by electron beam-physical vapor deposition method, and finally a 100 μm bonding layer material is coated on the outermost layer by plasma spraying;

[0023] Step 7: Install the exhaust duct

[0024] After cleaning the residual coating material on the exhaust duct body, align it with the mounting holes on the cylinder head and install the exhaust duct body.

[0025] A further improvement is that in step 4, the baking conditions are: temperature 1100° C. to 1300° C., and time 3 to 4 hours.

[0026] A further improvement is that in step 4, the specific composition of the NiCrAlY alloy powder is: 23wt% Co, 17wt% Cr, 12wt% Al, 0.5wt% Y and 47.5wt% Ni.

[0027] A further improvement is that in step 4, the particle size of the powder material is 30 to 60 μm.

[0028] A further improvement is that in step five, the particle size of the mixed powder is 30 to 100 nm.

[0029] A further improvement is that in the step five, the weight of YSZ powder is 2 parts, the weight of La(NO3)3·6(H2O) is 2.5 parts, the weight of ZrOCl2·8(H2O) is 1 part, and the weight of sodium linear alkylbenzene sulfonate is 1.5 parts.

[0030] The beneficial effects of the present invention are:

[0031] (1) The exhaust heat exchanger design of the present invention can effectively reduce the exhaust duct wall temperature, thereby reducing the risk of exhaust duct flashback. In addition, it can also reduce the thermal stress on the exhaust system and surrounding components, thereby extending their service life.

[0032] (2) The present invention can promote the mixing of incomplete combustion exhaust gas by using a spiral mixer, which can effectively avoid the occurrence of excessive concentration of local incomplete combustion exhaust gas and reduce the risk of exhaust duct backfire.

[0033] (3) The present invention can reduce exhaust gas temperature and improve the working efficiency of post-treatment equipment such as SCR (selective catalytic reduction) and DPF (diesel particulate filter).

[0034] (4) The present invention uses a thermal barrier coating to prevent the cylinder head from conducting heat to the exhaust duct, while reducing the thermal stress generated by the different thermal expansion coefficients between the metal layers, thereby extending the service life of the exhaust duct.

[0035] (5) The present invention has little impact on the engine cylinder head structure and is more stable and reliable than traditional cylinder head cooling systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic side view of the end of the exhaust duct body of the present invention.

[0037] Figure 2 It is a front view structural schematic diagram of the exhaust duct body and the cylinder head after being installed.

[0038] Figure 3 It is a partially enlarged front view structural schematic diagram of the exhaust duct body of the present invention after installation.

[0039] Figure 4 It is a schematic diagram of the thermal barrier coating structure of the present invention.

[0040] Among them: 1. Exhaust duct body; 2. Thermal barrier coating; 3. First bonding layer; 4. Ceramic layer; 5. Second bonding layer; 6. Exhaust duct heat exchanger; 7. Spiral static mixer; 8. Exhaust duct heat exchange wall; 9. Heat exchange hole; 10. Cylinder head. DETAILED DESCRIPTION

[0041] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0042] according to Figure 1 to Figure 4As shown, this embodiment proposes a thermal barrier coating exhaust duct with anti-flashback function, including an exhaust duct body 1, on which a thermal barrier coating 2 is coated, and the thermal barrier coating 2 is respectively composed of a first bonding layer 3, a ceramic layer 4 and a second bonding layer 5 from the outside to the inside, the first bonding layer 3 and the second bonding layer 5 have the same thickness, and the first bonding layer 3 and the second bonding layer 5 are made of the same material, an exhaust duct heat exchanger 6 is installed on the exhaust duct body 1, and a spiral static mixer 7 is installed on the inner side of the exhaust duct body 9, wherein the exhaust duct heat exchanger 7 includes an exhaust duct heat exchange wall 8 and a heat exchange hole 9, and the exhaust duct heat exchange wall 8 Heat exchange holes 9 are provided on the upper surface, and the heat exchange holes 9 are evenly provided in several groups, and the several groups of heat exchange holes 9 are connected. In this embodiment, the heat exchange holes 9 are evenly provided in four groups. In the exhaust duct body 1, a spiral static mixer 7 is provided, which uses a spiral mixing structure to promote the mixing of incomplete combustion exhaust gas, which can effectively avoid the occurrence of the problem of excessive concentration of local incomplete combustion exhaust gas and reduce the risk of exhaust duct flashback. The introduction of the exhaust duct heat exchanger 7 can effectively reduce the wall temperature of the exhaust chamber of the cylinder head 10 (the exhaust chamber is used to install the exhaust duct body 1), thereby reducing the risk of exhaust duct flashback. In addition, the thermal stress on the exhaust system and surrounding components can be reduced, thereby extending their service life. Further, the use of the thermal barrier coating 2 can reduce the thermal stress caused by the different thermal expansion coefficients between the metal layers while avoiding the cylinder head from conducting heat to the exhaust duct, thereby extending the service life of the exhaust duct.

[0043] A method for installing a thermal barrier coating exhaust duct with an anti-flashback function comprises the following steps:

[0044] Step 1: Clean the inner and outer walls of the exhaust duct

[0045] Use sandpaper to polish and remove the surface residues on the inner and outer wall areas of the exhaust duct body. Specifically, use 80-mesh sandpaper for rough polishing to remove large residues and unevenness, and then use 240-mesh sandpaper for fine polishing to ensure that the wall surface is smooth and flat, and then rinse with deionized water to remove all dust and residues, and then dehydrate with alcohol and blow dry;

[0046] Step 2: Installation of spiral mixer and exhaust duct heat exchanger

[0047] Install the spiral mixer into the exhaust duct bend, then heat the outer wall of the exhaust duct to 100°C through an external heating device, evenly apply the thermal conductive glue on the outer wall of the exhaust duct, and then install the exhaust heat exchanger, and cool it naturally at room temperature (25°C±2°C) until the wall is completely fitted;

[0048] Step 3: Treatment of cylinder head

[0049] Prepare the cylinder head where the exhaust duct body needs to be installed, and use sandpaper to polish the exhaust duct cavity of the cylinder head. Specifically, polish the exhaust duct cavity of the cylinder head according to the exhaust duct size to ensure that the exhaust duct cavity can properly accommodate the entry of the exhaust duct body, and then drill a hole from the top of the cylinder head to the exhaust duct cavity. The drilling position is a pre-set position.

[0050] Step 4: Prepare bonding layer materials

[0051] High-density polyethylene (HDPE) powder, NiCrAlY alloy powder and 0.1-0.2wt% high-purity Dy (dysprosium) powder are mixed by mechanical mixing for 15 minutes. After mixing evenly, the powder is placed in a high-temperature oven for baking. The particle size of the powder material is 30-60μm, wherein the specific composition of the NiCrAlY alloy powder is: 23wt% Co, 17wt% Cr, 12wt% Al, 0.5wt% Y and 47.5wt% Ni. The baking conditions are: temperature 1100°C-1300°C, time 3-4h. In this embodiment, the preferred temperature is 1200°C, and the time is 3.5h.

[0052] Step 5: Prepare ceramic layer materials

[0053] Pour YSZ (yttrium stabilized zirconium oxide) powder into 400-500 ml high-purity ethanol and place it in an ultrasonic cleaning machine. Use ultrasonic treatment to help the YSZ powder disperse evenly in the ethanol to form a YSZ suspension. Add La(NO3)3·6(H2O) (lanthanum nitrate hexahydrate) and ZrOCl2·8(H2O) (zirconium oxychloride octahydrate), stir evenly with a glass rod, and then add linear alkylbenzene sodium sulfonate. During the addition process, add it dropwise into the solution and stir continuously. The pH value is then adjusted to between 10 and 11, preferably 10 in the present embodiment, and then allowed to stand for 30 to 60 minutes, preferably 45 minutes in the present embodiment, until no more precipitate appears, and then filtered. The precipitate is placed in a thermoelectric furnace and treated at a high temperature of 500 to 600°C for 1 hour, preferably 450°C in the present embodiment, to obtain a mixed powder of YSZ and La2Zr2O7 with a particle size of 30 to 100 nm, that is, the ceramic layer material is nanomaterial.

[0054] Wherein, YSZ powder is 2 parts by weight, La(NO3)3·6(H2O) is 2.5 parts by weight, ZrOCl2·8(H2O) is 1 part by weight, and linear alkylbenzene sulfonate sodium is 1.5 parts by weight. In this embodiment, each part by weight corresponds to 1 g;

[0055] Step 6: Apply thermal barrier coating

[0056] The outer wall surface (except the heat exchange holes) of the exhaust duct heat exchanger is evenly coated with a 100 μm bonding layer material by plasma spraying. Before coating, the surface to be coated is preheated to 280° C. to 300° C., preferably 290° C. in this embodiment, and then a 300 μm ceramic layer material is coated on the bonding layer surface (except the heat exchange holes) by electron beam-physical vapor deposition method. Finally, a 100 μm bonding layer material is coated on the outermost layer by plasma spraying.

[0057] Step 7: Install the exhaust duct

[0058] After cleaning the residual coating material on the exhaust duct body, align it with the mounting holes on the cylinder head and install the exhaust duct body.

[0059] The present invention can effectively promote the mixing of incompletely burned exhaust gas by designing an exhaust duct with a spiral mixing structure. In addition, a heat exchange channel is arranged on the outside of the exhaust duct, and a thermal barrier coating is coated on the heat exchange channel and the outer wall of the exhaust duct. This design can reduce the heat transferred from the high-temperature cylinder head to the exhaust duct, while taking away the heat from the high-temperature wall of the exhaust duct. The combination of the two can effectively reduce the temperature of the exhaust duct wall while avoiding the situation where the local gas concentration is too high. In this way, it can prevent the incompletely burned exhaust gas from burning when it encounters the high-temperature wall, thereby effectively curbing the occurrence of backfire.

[0060] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the framework and scope of application of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A thermal barrier coating exhaust duct with anti-flashback function, characterized in that: The invention comprises an exhaust duct body (1), the exhaust duct body (1) being coated with a thermal barrier coating (2), the thermal barrier coating (2) comprising, from the outside to the inside, a first bonding layer (3), a ceramic layer (4) and a second bonding layer (5), the first bonding layer (3) and the second bonding layer (5) being made of the same material, an exhaust duct heat exchanger (6) being installed on the exhaust duct body (1), and a spiral static mixer (7) being installed on the inner side of the exhaust duct body (1).

2. The thermal barrier coating exhaust duct with anti-flashback function according to claim 1, characterized in that: The exhaust duct heat exchanger (7) comprises an exhaust duct heat exchange wall (8) and heat exchange holes (9). The exhaust duct heat exchange wall (8) is provided with heat exchange holes (9), and the heat exchange holes (9) are evenly arranged in a plurality of groups, and the plurality of groups of heat exchange holes (9) are connected to each other.

3. The method for installing a thermal barrier coating exhaust duct with anti-flashback function as claimed in claim 1 is characterized in that: The following steps are involved: Step 1: Clean the inner and outer walls of the exhaust duct Use sandpaper to polish and remove the surface residues on the inner and outer wall areas of the exhaust duct body to ensure that the wall surface is smooth and flat, then rinse with deionized water, dehydrate with alcohol and blow dry; Step 2: Installation of spiral mixer and exhaust duct heat exchanger Install the spiral mixer into the exhaust duct bend, then heat the outer wall of the exhaust duct to 100°C through an external heating device, evenly apply the thermal conductive glue on the outer wall of the exhaust duct, and then install the exhaust heat exchanger and cool it naturally at room temperature until the wall is completely fitted; Step 3: Treatment of cylinder head Prepare the cylinder head where the exhaust duct body needs to be installed, and use sandpaper to polish the exhaust duct cavity of the cylinder head, and then drill a hole from the top of the cylinder head to the exhaust duct cavity; Step 4: Prepare bonding layer materials High-density polyethylene powder, NiCrAlY alloy powder and 0.1-0.2wt% high-purity Dy powder are mixed by mechanical mixing for 15 minutes, and after mixing evenly, the powder is placed in a high-temperature oven for baking; Step 5: Prepare ceramic layer materials Pour YSZ powder into 400-500 ml high-purity ethanol and place it in an ultrasonic cleaning machine to form a YSZ suspension, add La(NO3)3·6(H2O) and ZrOCl2·8(H2O), stir evenly, add linear alkylbenzene sulfonate sodium, adjust the pH value, let it stand for 30-60 minutes, filter, put the precipitate into a thermoelectric furnace, and treat it at a high temperature of 500-600°C for 1 hour to obtain a mixed powder of YSZ and La2Zr2O7; Step 6: Apply thermal barrier coating A 100 μm bonding layer material is uniformly coated on the outer wall of the exhaust duct heat exchanger by plasma spraying, and then a 300 μm ceramic layer material is coated on the bonding layer surface by electron beam-physical vapor deposition method, and finally a 100 μm bonding layer material is coated on the outermost layer by plasma spraying; Step 7: Install the exhaust duct After cleaning the residual coating material on the exhaust duct body, align it with the mounting holes on the cylinder head and install the exhaust duct body.

4. The method for installing a thermal barrier coating exhaust duct with anti-flashback function according to claim 3, characterized in that: In the step 4, the baking conditions are: temperature 1100° C. to 1300° C., and time 3 to 4 hours.

5. The method for installing a thermal barrier coating exhaust duct with anti-flashback function according to claim 3, characterized in that: In the step 4, the specific composition of the NiCrAlY alloy powder is: 23wt% Co, 17wt% Cr, 12wt% Al, 0.5wt% Y and 47.5wt% Ni.

6. The method for installing a thermal barrier coating exhaust duct with anti-flashback function according to claim 3, characterized in that: In the step 4, the particle size of the powder material is 30 to 60 μm.

7. The method for installing a thermal barrier coating exhaust duct with anti-flashback function according to claim 3, characterized in that: In the step 5, the particle size of the mixed powder is 30 to 100 nm.

8. The method for installing a thermal barrier coating exhaust duct with anti-flashback function according to claim 3, characterized in that: In the step 5, the weight of YSZ powder is 2 parts, the weight of La(NO3)3·6(H2O) is 2.5 parts, the weight of ZrOCl2·8(H2O) is 1 part, and the weight of linear alkylbenzene sodium sulfonate is 1.5 parts.

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