A non-metal expansion joint and a production method thereof

Abstract

The present invention provides a non-metal expansion joint, which is arranged on an exhaust pipe of a medium-sized gas engine. The exhaust pipe comprises an air inlet section and an air outlet section, which are arranged at intervals from the air inlet section and comprise a frame pipe, an expansion assembly and a guide pipe, the two ends of the frame pipe are respectively connected with the air inlet section and the air outlet section, and an air duct is opened around the middle section of the frame pipe; the expansion assembly comprises a skin, a heat-insulating cotton belt and two metal rings, the two metal rings are symmetrically sleeved on both sides of the air duct, the skin is arranged around the outer rings of the two metal rings, and the heat-insulating cotton belt is arranged between the two metal rings and the skin; the guide pipe is conical, and its large-diameter end is sealed and connected with a side of the frame pipe close to the air inlet section, and a tortuous buffer cavity is formed between the guide pipe, the frame pipe and the air outlet section; the guide pipe solves the problems of difficulty in ensuring flange flatness, coaxiality of welding of various parts and easy generation of cold cracks after welding when the size is huge.

Description

Technical Field

[0001] The invention relates to the technical field of expansion joints, and in particular to a non-metallic expansion joint and a production method thereof. Background Art

[0002] Non-metal expansion joints can compensate for axial, lateral and angular forces, have the characteristics of no thrust, simplified support design, corrosion resistance, high temperature resistance, noise reduction and vibration reduction, etc., and are particularly suitable for hot air ducts and smoke ducts. For the exhaust ducts of medium-sized gas turbines, the working temperature of the high-temperature gas is as high as about 650℃. In order to avoid the thermal expansion caused by the exhaust temperature of the medium-sized gas turbine under the worst working conditions, it is necessary to install non-metal expansion joints in the exhaust diffusion section of the medium-sized gas turbine to solve the problem.

[0003] The non-metallic expansion joints required for medium-sized gas turbine exhaust pipes are larger in size. The diameter of medium-sized gas turbine exhaust pipes is usually about six meters. Due to the large size, the following issues need to be paid attention to in the process of producing non-metallic expansion joints that can be used accordingly:

[0004] (1) The non-metal expansion joint is rigidly connected to the exhaust diffuser section of the gas turbine through flange bolts, and no sealing welding is performed after assembly. In order to avoid leakage of high-temperature gas (working temperature of about 650°C), the flatness of the non-metal expansion joint flange must be ensured;

[0005] (2) Non-metallic expansion joints have a large diameter, small welding gaps between parts, and a large amount of welding. It is necessary to determine the welding sequence of each part to control welding deformation and the coaxiality of each part, which makes welding, processing, and transportation more difficult.

[0006] (3) The frame is the contour support of the non-metallic expansion joint. It must have sufficient strength and rigidity. The material of the frame should be compatible with the medium temperature. It is mostly made of stainless steel or heat-resistant steel. However, heat-resistant steel has poor welding performance. When the welding process is cooled, cold cracks are easily generated in the incomplete melting zone and overheating zone. Therefore, a reasonable process plan needs to be designed to prevent cold cracks and ensure the quality of the weld. Summary of the invention

[0007] The object of the present invention is to provide a non-metallic expansion joint and a production method thereof, which solves the problems of difficulty in ensuring the flatness of flanges when the size is huge, coaxiality of welding of various parts, and easy generation of cold cracks after welding.

[0008] The embodiment of the present invention is realized by the following technical scheme: a non-metal expansion joint is arranged on the exhaust pipe of a medium-sized gas engine, the exhaust pipe includes an air inlet section and an air outlet section, the air inlet section and the air outlet section are arranged at intervals, and includes a frame pipe, an expansion assembly and a guide pipe, the two ends of the frame pipe are respectively connected to the air inlet section and the air outlet section, the ends of the air inlet section and the air outlet section are both placed in the frame pipe, and an air passage is opened around the middle section of the frame pipe;

[0009] The expansion assembly includes a skin, a heat-insulating cotton belt and two metal rings. The two metal rings are symmetrically sleeved on both sides of the airway. The skin is surrounded by the outer rings of the two metal rings to cover the gap between the two metal rings to prevent gas leakage and absorb the expansion amount. The heat-insulating cotton belt is arranged between the two metal rings and the skin.

[0010] The guide pipe is tapered, and one end of the guide pipe with a large diameter is sealed and connected to the side of the rack pipe close to the air inlet section, and one end of the guide pipe with a small diameter is located between the air outlet section and the rack pipe. A tortuous buffer cavity is formed between the guide pipe, the rack pipe and the air outlet section, and one end of the buffer cavity is communicated with the airway, and the other end of the buffer cavity is communicated with the inner cavities of the air inlet section and the air outlet section.

[0011] Furthermore, the metal ring comprises a plurality of hollow cones with different diameters, the plurality of hollow cones are sequentially connected in a stepped shape, and the distance between the outer rings of two metal rings is greater than the distance between the inner rings thereof.

[0012] Furthermore, it also includes a plurality of arched frames, which are arranged around the circumference of the two metal rings, and the two ends of the arched frames are respectively connected to the two metal rings by bolts;

[0013] The arch frame includes two arch plates, one end of one arch plate is connected to one metal ring, and the other end thereof is provided with a plurality of lock holes at intervals, and one end of the other arch plate is connected to another metal ring, and the other end thereof is provided with a waist hole, and the lock hole cooperates with the waist hole and is fixed by bolts.

[0014] Furthermore, the thermal insulation cotton belt includes a first thermal insulation cotton ring, a second thermal insulation cotton ring and a third thermal insulation cotton ring, the first thermal insulation cotton ring and the second thermal insulation cotton ring are respectively attached to the stepped parts of the two metal rings, a cavity is left between the first thermal insulation cotton ring and the second thermal insulation cotton ring, and the cavity is connected to the airway;

[0015] The third thermal insulation cotton ring is fitted on the inner wall of the skin, and the inner ring wall of the third thermal insulation cotton ring is in contact with the first thermal insulation cotton ring and the second thermal insulation cotton ring.

[0016] Furthermore, it also includes two cone tubes, which are respectively arranged at both ends of the rack tube, both ends of the rack tube are provided with a main flange, the large diameter end of the cone tube is provided with a secondary flange, and the main flange and the secondary flange are fixedly connected by bolts;

[0017] One of the conical tubes is sleeved on the air inlet section, and the small diameter end of the conical tube is sealed and connected to the air inlet section; the other conical tube is sleeved on the air outlet section, and the small diameter end of the conical tube is sealed and connected to the air outlet section.

[0018] Furthermore, it also includes a buffer ring, which is located in the buffer cavity. A plurality of the buffer rings are provided at intervals on the air outlet section, and a plurality of buffer rings are also provided at intervals on the small diameter section of the guide tube.

[0019] Furthermore, it also includes a plurality of rib plates, one end of each of the rib plates is connected to the frame tube, and the other end is connected to the inner cavity of the guide tube.

[0020] Furthermore, it also includes a plurality of lifting rings, which are symmetrically arranged on the tube walls on both sides of the rack tube.

[0021] A method for producing a non-metallic expansion joint, applicable to the implementation of the production of a non-metallic expansion joint in any of the above steps, comprises the following steps:

[0022] S1, when producing rack tubes, the length of the rack tubes should be increased by 10mm on the basis of the predetermined length to ensure the subsequent cutting margin. Three metal strips of the same length are cut according to the required size, and the three metal strips are made into arc plates with an arc of 120° through a rolling machine. The three arc plates are spliced ​​into a cylindrical rack tube through a number of tie bars, and the adjacent arc plates are spot welded at intervals;

[0023] S2, welding the first steps of two metal rings on the rack tube at intervals, and the first steps of the two metal rings are symmetrically arranged; the specific method of welding the first steps of the metal rings is:

[0024] First, preheat the first step of the rack tube and the metal ring, then weld a fan ring on each arc plate of the rack tube, the three fan rings are coaxially arranged and located in the same plane, then weld a first arc plate on the outer arc end of each fan ring, the three first arc plates are coaxially arranged and abutted in sequence; spot welding is performed first, and full welding is performed after the angle is adjusted;

[0025] The first arc-shaped plates of the two first steps are located between the fan rings of the two first steps;

[0026] S3, after the first step of the two metal rings is welded, the rack pipe is cut around the middle section to divide the rack pipe into two identical short rack pipes;

[0027] Each main flange is composed of three flanges with the same arc. Two main flanges are composed of six flanges in total. The six flanges are overlapped and spot welded in pairs to form a group of sub-flanges. The three groups of sub-flanges are coaxially placed between the two short rack tubes, and the sub-flanges and the two short rack tubes are preheated. The two sides of each group of sub-flanges are respectively connected vertically to the ends of the arc plates of the two short rack tubes. When connecting, spot welding is first performed, and then the process lap is welded to make the sub-flanges perpendicular to the short rack tubes. Finally, the sub-flanges and the short rack tubes are fully welded.

[0028] S4, then on the first step of the metal ring, the remaining step parts are welded in the same way as the first step. Preheating is required before welding. Spot welding is performed first, and then full welding is performed after the angle is adjusted. After the metal ring is welded, the two overlapping sub-flanges are separated to obtain two sections of sub-frame pipes with main flanges and metal rings.

[0029] S5, then weld a guide pipe in the inner cavity of the sub-frame tube with the main flange and the first step of the metal ring, the guide pipe is also in three sections, each section is welded to the corresponding arc plate, and it needs to be preheated before welding, and then spot welded, and then spot welded to the rib plate, and after the three sections are spot welded and the angles are adjusted, they are fully welded;

[0030] S6, welding a plurality of buffer rings on the guide pipe at intervals, each buffer ring also having three sections of equal arc, respectively welded on the three sections of the guide pipe and located on the same plane; the sub-rack pipes with the guide pipes are collectively referred to as left rack pipes, and the sub-rack pipes without the guide pipes are collectively referred to as right rack pipes;

[0031] S7, dismantle the left frame tube and the right frame tube into three sections of equal arc, grind off the spot welds between the three arc plates, and then perform heat treatment on each section to eliminate the internal stress after full welding;

[0032] S8, produce two cone tubes, each cone tube is also three-section with equal curvature, assembled into a whole by tie rods, then overlap the two sub-flanges and spot weld them, place the two cone tubes on both sides of the overlapping sub-flanges, and vertically connect the large diameter ends of the two cone tubes to the two sub-flanges respectively. The two sub-flanges are also three-section with equal curvature, and each section is connected to a section of the corresponding cone tube. Preheat before welding, spot weld first when welding, and then fully weld after adjusting the angle. When adjusting the angle between the sub-flange and the cone tube, it is also necessary to use a process tack to ensure that they are perpendicular to each other. After full welding, disassemble the two cone tubes with sub-flanges into three sections and perform heat treatment to eliminate internal stress;

[0033] S9, after all parts are heat treated, disassemble the process scaffold, and then reassemble the disassembled left and right rack tubes into a circular whole through tensioning, and reassemble the two cone tubes with sub-flanges into a cone shape, and set the left and right rack tubes coaxially and at intervals, and place the end with the main flange on the outside, and then install the insulation cotton belt and the skin between the two metal rings, and lock the skin and the metal ring through the arch plates of several arch scaffolds, and then connect the two arch plates of the arch scaffolds to each other, so as to connect and fix the left and right rack tubes, and finally connect the sub-flanges of the two cone tubes to the main flanges of the left and right rack tubes, respectively, to complete the trial assembly and inspection of the non-metallic expansion joint as a whole;

[0034] S10, after the trial assembly is qualified, the parts that are not fully welded are disassembled into three small sections, transported to the site and assembled and welded. The two cone tubes are respectively mounted on the air inlet section and the air outlet section. The left frame tube is connected with the cone tube on the air inlet section, and the air outlet section extends to the inner cavity of the guide tube. All three-section parts are welded into a whole with nickel-based welding materials, and no heat treatment is required.

[0035] Furthermore, the frame tube, metal ring, guide tube, cone tube, rib plate, buffer ring, main flange and auxiliary flange are all made of martensitic and semi-austenitic precipitation hardening stainless steel, and metal flaw detection is required after all welding and heat treatment to inspect the weld quality.

[0036] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0037] 1. The present invention has a reasonable design and a simple structure. A plurality of plates are rolled into an arc shape, connected to form a cylinder, and then the cylinder is cut from the middle into two small cylinders, thereby ensuring the coaxiality and size of the rack pipe body. Six sections of two main flanges with equal arcs are spot welded together in pairs, and then the two ends are respectively connected to the two small cylinders. This segmented back-to-back welding method can ensure the flatness of the large-sized main flange and the rack pipe after welding.

[0038] 2. The rack tube, metal ring, guide tube, cone tube, rib plate, buffer ring, main flange and auxiliary flange are all composed of three sections with equal arcs. The segmented operation is not only convenient for welding, transportation, heat treatment, etc., but also easy to adjust to ensure the overall coaxiality.

[0039] 3. All welding during production requires preheating, insulation, spot welding, full welding, flaw detection, heat treatment flaw detection, and on-site assembly and connection of all three small parts using nickel-based welding materials to solve problems such as cold cracks that are easy to occur after welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A half-section schematic diagram of a non-metallic expansion joint provided by the present invention;

[0042] Figure 2 A schematic diagram of the assembly of a non-metallic expansion joint provided by the present invention;

[0043] Figure 3 A schematic diagram of the structure of a non-metallic expansion joint provided by the utility model after welding the main flange;

[0044] Figure 4 A schematic diagram of the structure of a non-metallic expansion joint main flange provided by the utility model after being welded and separated;

[0045] Figure 5 A flow chart of a method for producing a non-metallic expansion joint provided by the present invention;

[0046] Icons: 1. Air inlet section, 2. Air outlet section, 3. Rack pipe, 4. Guide pipe, 5. Skin, 6. Insulation cotton belt, 7. Metal ring, 8. Air duct, 9. Buffer chamber, 10. Arch frame, 11. Arch plate, 12. Keyhole, 13. Waist hole, 14. First insulation cotton ring, 15. Second insulation cotton ring, 16. Third insulation cotton ring, 17. Conical tube, 18. Buffer ring, 19. Rib plate, 20. Lifting ring, 21. Main flange, 22. Auxiliary flange. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Reference Figures 1 to 4As shown, the present embodiment provides a non-metallic expansion joint, which is arranged on the exhaust pipe of a medium-sized gas engine. The exhaust pipe includes an air inlet section 1 and an air outlet section 2. The internal gas flows from the air inlet section 1 to the air outlet section 2. The air inlet section 1 and the air outlet section 2 are arranged at intervals, including a frame pipe 3, an expansion assembly and a guide pipe 4. The two ends of the frame pipe 3 are respectively connected to the air inlet section 1 and the air outlet section 2. The ends of the air inlet section 1 and the air outlet section 2 are both placed in the frame pipe 3. An air duct 8 is opened around the middle section of the frame pipe 3. When positive pressure and negative pressure are generated inside the exhaust pipe, the gas enters the air duct 8 from the gap between the air inlet section 1 and the air outlet section 2, and then passes through the expansion assembly to offset the positive pressure and negative pressure.

[0050] like Figure 1 As shown, the expansion assembly includes a skin 5, a heat-insulating cotton belt 6 and two metal rings 7. The two metal rings 7 are symmetrically sleeved on both sides of the airway 8. The skin 5 is arranged around the outer rings of the two metal rings 7 to seal the gap between the two metal rings 7. The skin 5 is annular and is the main expansion body of the non-metallic expansion joint. It is a multi-layer composite of excellent performance silicone rubber or high-silicon polytetrafluoroethylene and alkali-free glass wool. It is a high-strength sealing composite material, which is used to prevent the leakage of gas and rainwater and absorb the expansion amount.

[0051] The thermal insulation cotton belt 6 is arranged between the two metal rings 7 and the skin 5. The thermal insulation cotton plays the dual role of thermal insulation and air tightness of the non-metallic expansion joint. It is composed of glass fiber cloth, high silica cloth and various thermal insulation cotton felts. Its length and width are consistent with the outer skin and it has good elongation and tensile strength.

[0052] like Figure 1 As shown, the guide pipe 4 is conical, and the large-diameter end of the guide pipe 4 is sealed and connected to the side of the rack pipe 3 close to the air inlet section 1, and the small-diameter end of the guide pipe 4 is located between the air outlet section 2 and the rack pipe 3. A tortuous buffer cavity 9 is formed between the guide pipe 4, the rack pipe 3 and the air outlet section 2. One end of the buffer cavity 9 is connected to the airway 8, and the other end of the buffer cavity 9 is connected to the inner cavity of the air inlet section 1 and the air outlet section 2. In specific implementation, when the exhaust pipe generates positive pressure, the gas passes through the tortuous irregular buffer cavity, which reduces the impact amount of the high-temperature combustion gas directly impacting the skin 5, and prolongs the service life of the equipment to a certain extent.

[0053] The metal ring 7 comprises a plurality of hollow truncated cones of different diameters, and the plurality of hollow truncated cones are sequentially connected in a stepped shape, and the distance between the outer rings of two metal rings 7 is greater than the distance between the inner rings thereof. Figure 1 As shown, in the specific implementation, the metal ring 7 is in the shape of a multi-stage cone, which is not only stronger than the traditional straight plate structure and can withstand greater positive and negative pressures, but also increases the contact area with the thermal insulation cotton belt 6, which helps to install and fix the thermal insulation cotton belt and improve the thermal insulation effect. At the same time, the larger volume ensures the expansion and contraction of the non-metallic expansion joint and the structural strength is also high.

[0054] like Figure 1 and 2 As shown, it also includes a plurality of arched frames 10, which are arranged around the circumference of the two metal rings 7, and the two ends of the arched frames 10 are respectively connected to the two metal rings 7 by bolts, so as to fix the skin 5 and the metal ring 7, and ensure the relative position relationship of the rack pipe 3 cut into two sections, and ensure that the size of the air duct 8 remains unchanged;

[0055] In specific implementation, the arch frame 10 includes two arch plates 11, one end of one arch plate 11 is connected to a metal ring 7, and a plurality of lock holes 12 are arranged at intervals at the other end thereof, one end of the other arch plate 11 is connected to another metal ring 7, and a waist hole 13 is arranged at the other end thereof, and the lock hole 12 cooperates with the waist hole 13 and is fixed by bolts, so as to facilitate adjusting the distance between the two arch plates of the arch frame 10, and then the distance between the two metal rings 7 can be adjusted according to the on-site installation conditions, and then the length of the rack pipe 3 can be adjusted, thereby overcoming the error of insufficient installation distance on the left and right sides sometimes.

[0056] like Figure 1 As shown, the heat-insulating cotton belt 6 includes a first heat-insulating cotton ring 14, a second heat-insulating cotton ring 15 and a third heat-insulating cotton ring 16. The first heat-insulating cotton ring 14 and the second heat-insulating cotton ring 15 are respectively attached to the stepped parts of the two metal rings 7. A cavity is left between the first heat-insulating cotton ring 14 and the second heat-insulating cotton ring 15. The cavity is connected to the airway 8, which ensures the normal circulation of gas and prevents the temperature from being lost from the metal ring 7.

[0057] The third thermal insulation cotton ring 16 is fitted on the inner wall of the skin 5, and the inner ring wall of the third thermal insulation cotton ring 16 abuts against the first thermal insulation cotton ring 14 and the second thermal insulation cotton ring 15. In specific implementation, the third thermal insulation surface supports and protects the skin 5 to a certain extent, and alleviates the damage of positive and negative pressure to the skin 5 to a certain extent.

[0058] like Figure 1 As shown, two cone tubes 17 are also included, and the two cone tubes 17 are respectively arranged at both ends of the frame tube 3. Both ends of the frame tube 3 are provided with a main flange 21, and the large diameter end of the cone tube 17 is provided with a secondary flange 22. The main flange 21 and the secondary flange 22 are fixedly connected by bolts;

[0059] One conical tube 17 is sleeved on the air inlet section 1, and one end of the air inlet section 1 close to the air outlet section 2 extends into the side conical tube 17, and can even extend into the frame tube 3. The small diameter end of the conical tube 17 is sealed and connected to the air inlet section 1; the other conical tube 17 is sleeved on the air outlet section 2, and one end of the air outlet section 2 close to the air inlet section 1 extends into the side conical tube 17 and extends into the frame tube 3, leaving a small gap with the air inlet section 1, preferably its size is slightly larger than the air inlet section 1, to prevent high-speed gas from directly rushing into the buffer chamber 9, and the small diameter end of the conical tube 17 is sealed and connected to the air outlet section 2.

[0060] The buffer ring 18 is also included. The buffer ring 18 is located in the buffer cavity 9. A plurality of buffer rings 18 are provided at intervals on the gas outlet section 2. A plurality of buffer rings 18 are also provided at intervals on the small diameter section of the flow guide tube 4. Figure 1 As shown, in a specific implementation, a plurality of buffer rings 18 are used to slow down the high-temperature airflow entering the buffer cavity 9 , thereby slowing down the impact of the airflow on the skin 5 to a certain extent.

[0061] It also includes a plurality of ribs 19, one end of each of which is connected to the frame tube 3, and the other end of each of which is connected to the inner cavity of the flow guide tube 4. Figure 1 As shown, in a specific implementation, a plurality of ribs 19 are mainly used to fix the connection between the guide tube 4 and the rack tube 3 to prevent the guide tube 4 from falling off when subjected to high pressure impact.

[0062] It also includes a plurality of lifting rings 20. The pipe walls on both sides of the rack pipe 3 are symmetrically surrounded by a plurality of lifting rings 20. The lifting rings 20 are mainly used for the installation and lifting of the metal expansion joint.

[0063] like Figure 1-5 As shown, a non-metallic expansion joint production method is applicable to the implementation of any of the above steps of a non-metallic expansion joint production method, comprising the following steps:

[0064] S1, when producing the rack tube 3, the length of the rack tube 3 should be increased by 10 mm on the basis of the predetermined length to ensure the subsequent cutting margin, three metal strips of the same length are cut according to the required size, the three metal strips are made into arc plates with an arc of 120° through a rolling machine, the three arc plates are spliced ​​into a cylindrical rack tube 3 through a plurality of tie bars, and the adjacent arc plates are spot welded at intervals;

[0065] S2, the first steps of two metal rings 7 are welded on the rack pipe 3 at intervals. The first steps of the two metal rings 7 are symmetrically arranged. The two metal rings are welded first to avoid that after the main flange 21 is welded, the main flange will block some metal rings 7, resulting in poor welding of the metal rings 7. The specific method of welding the first steps of the metal rings 7 is:

[0066] First, preheat the first step of the rack tube 3 and the metal ring 7, then weld a fan ring on each arc plate of the rack tube 3, the three fan rings are coaxially arranged and located in the same plane, and then weld a first arc plate at the outer arc end of each fan ring, the three first arc plates are coaxially arranged and abutted in sequence; when welding, spot welding is performed first, and then full welding is performed after the angle is adjusted. After adjustment, triangular supports need to be welded to ensure their verticality, so that they will not tilt during the full welding process;

[0067] The first arc-shaped plates of the two first steps are located between the fan rings of the two first steps;

[0068] S3, after the first steps of the two metal rings 7 are welded, the rack tube 3 is cut around the middle section to divide the rack tube 3 into two identical short rack tubes;

[0069] Each main flange 21 is composed of three flanges with the same arc. Two main flanges 21 are composed of six flanges in total. The six flanges are overlapped and spot welded in pairs to form a group of sub-flanges. The three groups of sub-flanges are coaxially placed between the two short rack tubes, and the sub-flanges and the two short rack tubes are preheated. The two sides of each group of sub-flanges are respectively connected vertically to the ends of the arc plates of the two short rack tubes. When connecting, spot welding is first performed, and then a process clasp is welded to make the sub-flange perpendicular to the short rack tube. Finally, the sub-flange and the short rack tube are fully welded.

[0070] S4, then on the first step of the metal ring 7, the remaining step parts are welded in the same manner as the first step. Preheating is required before welding. Spot welding is performed first, and then full welding is performed after the angle is adjusted. After the metal ring 7 is welded, the two overlapping sub-flanges are separated to obtain two sections of sub-frame pipes with main flanges 21 and metal rings 7.

[0071] S5, then weld the guide pipe 4 in the inner cavity of the sub-frame tube with the main flange 21 and the first step of the metal ring 7, the guide pipe 4 is also in three sections, each section is welded to the corresponding arc plate, and preheating is required before welding, and then spot welding, and spot welding the rib plate 19, and full welding is performed after the three sections are spot welded and the angles are adjusted;

[0072] S6, weld a plurality of buffer rings 18 on the guide tube 4 at intervals, each buffer ring 18 also has three sections of equal arc, which are respectively welded on the three sections of the guide tube 4 and are located in the same plane; the sub-rack tubes with the guide tube 4 are collectively referred to as left rack tubes, and the sub-rack tubes without the guide tube 4 are collectively referred to as right rack tubes;

[0073] S7, dismantle the left frame tube and the right frame tube into three sections of equal arc, grind off the spot welds between the three arc plates, and then perform heat treatment on each section to eliminate the internal stress after full welding;

[0074] S8, produce two cone tubes 17, each cone tube 17 is also three-section type with equal curvature, and is assembled into a whole by using tie bars, then overlap the two sub-flanges 22 and spot weld them, place the two cone tubes 17 on both sides of the overlapping sub-flanges 22, and vertically connect the large diameter ends of the two cone tubes 17 to the two sub-flanges 22 respectively. The two sub-flanges 22 are also three-section type with equal curvature, and each section is connected to a section of the corresponding cone tube 17 respectively. Preheat before welding, spot weld first during welding, and then fully weld after adjusting the angle. When adjusting the angle between the sub-flange 22 and the cone tube 17, it is also necessary to use a process tack to ensure that they are perpendicular to each other. After full welding is completed, the two cone tubes 17 with sub-flanges 22 are disassembled into three sections and heat treated to eliminate internal stress;

[0075] S9, after all parts are heat treated, disassemble the process scaffold, and then reassemble the disassembled left and right rack tubes into a circular whole by tensioning, and reassemble the two tapered tubes 17 with secondary flanges 22 into a cone shape, and place the left and right rack tubes coaxially and at intervals, and place one end with the main flange 21 on the outside, and then install the insulation cotton belt 6 and the skin 5 between the two metal rings 7, and lock the skin 5 and the metal ring 7 through the arch plates 11 of several arch scaffolds 10, and then connect the two arch plates 11 of the arch scaffold 10 to each other, so that the left and right rack tubes are connected and fixed, and finally the secondary flanges 22 of the two tapered tubes 17 are respectively connected to the main flanges 21 of the left and right rack tubes, and the trial assembly and inspection of the non-metallic expansion joint as a whole are completed;

[0076] S10, after the trial assembly is qualified, the parts that are not fully welded are disassembled into three small parts, transported to the site and assembled and welded, the two cone tubes 17 are respectively mounted on the air inlet section 1 and the air outlet section 2, the left frame tube is connected with the cone tube 17 on the air inlet section 1, and the air outlet section 2 extends to the inner cavity of the guide tube 4. When all the three-section parts are welded into a whole, nickel-based welding materials are used for welding, and no heat treatment is required.

[0077] The rack tube 3, metal ring 7, guide tube 4, cone tube 17, rib plate 19, buffer ring 18, main flange 21 and auxiliary flange 22 are all made of martensitic and semi-austenitic precipitation hardening stainless steel. Metal flaw detection is required after all welding and heat treatment to inspect the quality of the weld.

[0078] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-metallic expansion joint, arranged on an exhaust pipe of a medium-sized gas engine, the exhaust pipe comprising an air inlet section (1) and an air outlet section (2), the air inlet section (1) and the air outlet section (2) being arranged at intervals, characterized in that: It comprises a frame tube (3), an expansion assembly and a flow guide tube (4), the two ends of the frame tube (3) are respectively connected to the air inlet section (1) and the air outlet section (2), the ends of the air inlet section (1) and the air outlet section (2) are both placed in the frame tube (3), and an air passage (8) is opened around the middle section of the frame tube (3); The expansion assembly comprises a skin (5), a heat-insulating cotton belt (6) and two metal rings (7); the two metal rings (7) are symmetrically sleeved on both sides of the air duct (8); the skin (5) is arranged around the outer rings of the two metal rings (7) to seal the gap between the two metal rings (7) to prevent gas leakage and absorb the expansion amount; the heat-insulating cotton belt (6) is arranged between the two metal rings (7) and the skin (5); The guide tube (4) is tapered, the large-diameter end of the guide tube (4) is sealedly connected to the side of the rack tube (3) close to the air inlet section (1), the small-diameter end of the guide tube (4) is located between the air outlet section (2) and the rack tube (3), a tortuous buffer cavity (9) is formed between the guide tube (4), the rack tube (3) and the air outlet section (2), one end of the buffer cavity (9) is in communication with the air passage (8), and the other end of the buffer cavity (9) is in communication with the inner cavities of the air inlet section (1) and the air outlet section (2); The metal ring (7) comprises a plurality of hollow truncated cones of different diameters, the plurality of hollow truncated cones being connected in sequence to form a step-like shape, and the distance between the outer rings of two metal rings (7) is greater than the distance between the inner rings thereof; It also comprises two conical tubes (17), the two conical tubes (17) are respectively arranged at two ends of the frame tube (3), both ends of the frame tube (3) are provided with a main flange (21), the large diameter end of the conical tube (17) is provided with a secondary flange (22), and the main flange (21) and the secondary flange (22) are fixedly connected by bolts; One of the conical tubes (17) is sleeved on the air inlet section (1), and the small diameter end of the conical tube (17) is sealed and connected to the air inlet section (1); the other of the conical tubes (17) is sleeved on the air outlet section (2), and the small diameter end of the conical tube (17) is sealed and connected to the air outlet section (2).

2. A non-metallic expansion joint according to claim 1, characterized in that: It also comprises a plurality of arched frames (10), wherein the plurality of arched frames (10) are arranged around the circumference of the two metal rings (7), and the two ends of the arched frames (10) are respectively connected to the two metal rings (7) by bolts; The arch frame (10) comprises two arch plates (11), one end of one arch plate (11) is connected to one metal ring (7), and the other end thereof is provided with a plurality of lock holes (12) at intervals, and one end of the other arch plate (11) is connected to another metal ring (7), and the other end thereof is provided with a waist hole (13), and the lock hole (12) cooperates with the waist hole (13) and is fixed by bolts.

3. A non-metallic expansion joint according to claim 1, characterized in that: The thermal insulation cotton belt (6) comprises a first thermal insulation cotton ring (14), a second thermal insulation cotton ring (15) and a third thermal insulation cotton ring (16); the first thermal insulation cotton ring (14) and the second thermal insulation cotton ring (15) are respectively attached to the stepped portions of the two metal rings (7); a cavity is left between the first thermal insulation cotton ring (14) and the second thermal insulation cotton ring (15), and the cavity is communicated with the airway (8); The third heat-insulating cotton ring (16) is arranged in a close fit on the inner wall of the skin (5), and the inner ring wall of the third heat-insulating cotton ring (16) is in contact with the first heat-insulating cotton ring (14) and the second heat-insulating cotton ring (15).

4. A non-metallic expansion joint according to claim 1, characterized in that: It also comprises a buffer ring (18), the buffer ring (18) being located in the buffer cavity (9), a plurality of the buffer rings (18) being spaced apart on the air outlet section (2), and a plurality of the buffer rings (18) being spaced apart on the small diameter section of the flow guide tube (4).

5. A non-metallic expansion joint according to claim 1, characterized in that: It also includes a plurality of rib plates (19), wherein one end of the plurality of rib plates (19) is connected to the frame tube (3), and the other end is connected to the inner cavity of the flow guide tube (4).

6. A non-metallic expansion joint according to claim 1, characterized in that: It also comprises a plurality of lifting rings (20), and the plurality of lifting rings (20) are symmetrically arranged around the tube walls on both sides of the frame tube (3).

7. A method for producing a non-metallic expansion joint, suitable for the production of a non-metallic expansion joint according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, when producing the rack tube (3), the length of the rack tube (3) is to be increased by 10 mm on the basis of the predetermined length to ensure the subsequent cutting margin, three metal plates of the same length are cut according to the required size, the three metal plates are made into arc plates with an arc of 120° by a rolling machine, the three arc plates are spliced ​​into a cylindrical rack tube (3) by a plurality of tie bars, and adjacent arc plates are spot welded at intervals; S2, welding the first steps of two metal rings (7) on the frame tube (3) at intervals, wherein the first steps of the two metal rings (7) are symmetrically arranged; the specific method of welding the first steps of the metal rings (7) is: First, the first step of the rack tube (3) and the metal ring (7) is preheated, and then a fan ring is welded on each arc plate of the rack tube (3), the three fan rings are coaxially arranged and located on the same plane, and then a first arc plate is welded on the outer arc end of each fan ring, and the three first arc plates are coaxially arranged and abutted in sequence; when welding, spot welding is performed first, and then full welding is performed after the angle is adjusted; The first arc-shaped plates of the two first steps are located between the fan rings of the two first steps; S3, after the first steps of the two metal rings (7) are welded, the rack tube (3) is cut around the middle section to divide the rack tube (3) into two identical short rack tubes; Each main flange (21) is composed of three flanges with the same arc, and the two main flanges (21) are composed of six flanges in total. The six flanges are overlapped and spot welded in pairs to form a group of sub-flanges. The three groups of sub-flanges are coaxially placed between the two short rack tubes, and the sub-flanges and the two short rack tubes are preheated. The two sides of each group of sub-flanges are respectively connected vertically to the ends of the arc plates of the two short rack tubes. When connecting, spot welding is first performed, and then a process lap is welded to make the sub-flanges perpendicular to the short rack tubes. Finally, the sub-flanges and the short rack tubes are fully welded. S4, then welding the remaining step portion on the first step of the metal ring (7) in the same manner as welding the first step. Preheating is required before welding. Spot welding is first performed, and then full welding is performed after adjusting the angle. After the metal ring (7) is welded, the two overlapping sub-flanges are separated to obtain two sections of sub-frame pipes with main flanges (21) and metal rings (7); S5, then welding the guide pipe (4) to the inner cavity of the sub-frame tube with the main flange (21) and the first step of the metal ring (7), the guide pipe (4) also has three sections, each section is welded to the corresponding arc plate, and preheating is required before welding, and then spot welding is performed, and the rib plate (19) is spot welded, and after the three sections are spot welded and the angles are adjusted, full welding is performed; S6, welding a plurality of buffer rings (18) on the guide tube (4) at intervals, each buffer ring (18) also having three sections of equal arc, which are respectively welded on the three sections of the guide tube (4) and are located on the same plane; the sub-rack tubes with the guide tube (4) are collectively referred to as left rack tubes, and the sub-rack tubes without the guide tube (4) are collectively referred to as right rack tubes; S7, dismantle the left frame tube and the right frame tube into three sections of equal arc, grind off the spot welds between the three arc plates, and then perform heat treatment on each section to eliminate the internal stress after full welding; S8, producing two conical tubes (17), each conical tube (17) is also a three-section type with equal arc, and is assembled into a whole by using tie bars, then the two auxiliary flanges (22) are overlapped and spot welded, the two conical tubes (17) are respectively placed on both sides of the overlapping auxiliary flanges (22), and the large diameter ends of the two conical tubes (17) are respectively vertically connected to the two auxiliary flanges (22), the two auxiliary flanges (22) are also three-section types with equal arc, and each section is respectively connected to a section of the corresponding conical tube (17), preheating is performed before welding, spot welding is performed during welding, and full welding is performed after the angle is adjusted. When adjusting the angle between the auxiliary flange (22) and the conical tube (17), a process sling is also required to ensure that they are perpendicular to each other. After full welding is completed, the two conical tubes (17) with auxiliary flanges (22) are disassembled into three sections and heat treated to eliminate internal stress; S9, after all parts are heat treated, the process scaffold is disassembled, and the disassembled left and right rack tubes are reassembled into a circular whole by means of tie bars, and the two cone tubes (17) with secondary flanges (22) are reassembled into a cone shape, and the left and right rack tubes are coaxially arranged and spaced apart, and one end thereof with the main flange (21) is placed outside, and then the heat insulation cotton belt (6) and the skin (5) are installed between the two metal rings (7), and the skin (5) and the metal ring (7) are locked by means of the arch plates (11) of the arch scaffolds (10), and then the two arch plates (11) of the arch scaffolds (10) are connected to each other, thereby connecting and fixing the left and right rack tubes, and finally the secondary flanges (22) of the two cone tubes (17) are connected to the main flanges (21) of the left and right rack tubes, respectively, to complete the trial assembly and inspection of the non-metallic expansion joint as a whole; S10, after the trial assembly is qualified, the unwelded parts of the whole are disassembled into three small parts, transported to the site, assembled and welded, the two cone tubes (17) are respectively mounted on the air inlet section (1) and the air outlet section (2), the left frame tube is connected to the cone tube (17) on the air inlet section (1), and the air outlet section (2) extends to the inner cavity of the guide tube (4). When all the three-section parts are welded into a whole, nickel-based welding materials are used for welding, and no heat treatment is required.

8. A method for producing a non-metallic expansion joint according to claim 7, characterized in that: The frame tube (3), metal ring (7), guide tube (4), cone tube (17), rib plate (19), buffer ring (18), main flange (21) and auxiliary flange (22) are all made of martensitic and semi-austenitic precipitation hardening stainless steel. Metal flaw detection is required after all welding and heat treatment to inspect the quality of the weld.

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