A method of assembling a high pressure HPSCR reactor

Abstract

The application discloses a kind of assembly methods of high pressure HPSCR reactor, belong to ship environmental protection equipment manufacturing technical field.The method mainly includes: segmented manufacturing is carried out to cylinder, adjustable support structure is installed in each cylinder segment, and the inner wall is adjusted to suppress deformation;Pre-marking and installing reaction bed under segmented state;After assembling cylinder, it is placed on adjustable roller tire frame to assemble external components;After welding, assemble bottom support, by rotating tire frame, four support base surfaces are adjusted to the same side, laser scribe instrument is detected and controlled, and height deviation is controlled within 5mm, to reserve uniform allowance for subsequent processing.The application solves the technical problems of deformation control difficulty of large thin-walled welded structure, low installation precision by the core technology of "segmented pre-support, segmented pre-installation, laser accurate measurement", and significantly improves assembly efficiency and product qualification rate.

Description

Technical Field

[0001] This invention relates to the field of marine environmental protection equipment manufacturing technology, specifically a method for assembling a high-pressure HPSCR (high-pressure selective catalytic reduction) reactor, which is particularly applicable to the manufacturing and assembly process of SCR reactors in marine exhaust gas treatment systems. Background Technology

[0002] Selective Catalytic Reduction (SCR) systems, as key equipment for treating marine engine exhaust gases, play a vital role in the shipbuilding industry by reducing emissions of nitrogen oxides (NOx) through catalytic reduction reactions. The SCR reactor shell, as the main component of the SCR system for catalytically filtering exhaust gases, is fixed to the ship's hull via sliding supports. It also connects to other components such as exhaust pipes to form the SCR system. Its complex internal structure includes components such as the reaction bed, flow guiding devices, end caps, and supports, placing extremely high demands on manufacturing and assembly processes.

[0003] The HPSCR reactor has a complex composition, consisting of a reactor body, flow guide, butterfly head, reaction bed, and base. It requires a well-designed production process, from individual parts to components and finally to overall assembly. Therefore, a suitable assembly process ensures the successful fabrication of the SCR reactor body.

[0004] Currently, HPSCR reactors are typically manufactured using a segmented structure: first, parts are made by cutting steel plates, then the parts are assembled into components, and finally the whole assembly and welding are performed. After the reactor shell is welded, several important connecting surfaces need to be machined as a whole to achieve the required dimensional accuracy. By using a reasonable assembly sequence and auxiliary assembly tooling, the assembly of SCR reactors can be made more efficient, and welding deformation caused by subsequent welding processes can be reduced. This ensures that the reactor has sufficient machining allowance, so that the dimensional accuracy of the machined reactor shell meets the requirements of the design drawings.

[0005] However, due to the large diameter, thin walls, and numerous welds of the cylinder, deformation is prone to occur during assembly and welding, resulting in insufficient machining allowances or excessive deviations at key connection surfaces (such as bracket mounting surfaces and flange interfaces), affecting the overall performance and installation accuracy. Although existing processes have adopted methods such as jig support and segmented pre-assembly, problems such as unreasonable assembly sequence, insufficient support rigidity, and outdated testing methods still exist, leading to low finished product qualification rates, high rework rates, and increased manufacturing costs.

[0006] Therefore, there is an urgent need for a systematic, high-precision, and easy-to-operate assembly method that can control welding deformation while ensuring structural rigidity, ensure that key dimensions meet design requirements, and improve the manufacturing quality and assembly efficiency of HPSCR reactors. Summary of the Invention

[0007] The purpose of this invention is to provide an assembly method for HPSCR reactor shells, addressing problems in existing technologies such as low dimensional accuracy and insufficient machining allowances caused by unreasonable assembly sequence, insufficient support, and welding deformation. This invention improves the efficiency of HPSCR reactor assembly by optimizing the assembly sequence, introducing internal support structures and high-precision detection methods, rationally setting assembly gaps to reduce deformation caused by subsequent welding, and enhancing the overall dimensional accuracy of the reactor shell after machining, ensuring it meets design drawing requirements.

[0008] The present invention is achieved through the following technical solution.

[0009] A method for assembling a high-pressure HPSCR reactor, characterized by the following steps:

[0010] The reactor cylinder is manufactured in sections, consisting of a first section and a second section.

[0011] An adjustable internal support structure is installed inside each cylinder section. By adjusting the internal support structure, the arc surfaces at both ends of the structure are radially pressed against the inner wall of the cylinder section to provide internal rigid support for the cylinder and suppress deformation during subsequent assembly and welding processes.

[0012] Mark the assembly positions of the two end faces of the reactor bed inside each cylinder section, and complete the installation of the reactor bed in its respective cylinder section;

[0013] The first and second cylindrical sections, which are equipped with the reaction bed and the internal support structure, are assembled to form an integral cylindrical body;

[0014] The assembled integral cylinder is hoisted onto an adjustable-spacing tire rack. By adjusting the roller spacing and support height of the tire rack, it can accommodate cylinders of different diameters and assemble external components.

[0015] After the welding process of the overall cylinder is completed, the four bottom supports are assembled. By rotating the tire frame, the base surfaces of the four supports are adjusted to the same vertical side. A laser scribing instrument is used to detect the height deviation of the four base surfaces under the same reference, and the deviation range is controlled to not exceed 5mm, so as to ensure that the base plates of each support have uniform and sufficient machining allowance during subsequent overall processing.

[0016] Furthermore, the adjustable internal support structure includes two arc-shaped support plates, a fully threaded long bolt, and a matching nut; by tightening the nut, the two arc-shaped support plates are driven to move towards each other along the bolt axis until their arc-shaped working surfaces are completely fitted and pressed against the inner wall of the cylinder, forming a distributed internal support.

[0017] Furthermore, the curvature of the arc-shaped support plate matches the curvature of the inner wall of the reactor cylinder.

[0018] Furthermore, the center of the fully threaded long bolt is provided with a centering scale line for indicating the symmetrical center of the two arc-shaped support plates; the fully threaded long bolt passes through the flat plate with the threaded hole of the arc-shaped support plate, and the two nuts are screwed to the middle position of the long bolt, and then passes through the flat plate with the threaded hole of the other arc-shaped support plate. By rotating the two adjusting nuts respectively, the two arc-shaped support plates can be driven to move towards or away from each other.

[0019] Furthermore, the roller frame includes two independent frames, and the distance between the two rollers of each frame is adjustable to accommodate reactor cylinders of different diameters.

[0020] Furthermore, the height deviation of the base surface of the four brackets is controlled to be no more than 5mm, so that the thickness of the base plate of each bracket after subsequent overall processing is no more than 10mm.

[0021] Furthermore, when adjusting the support height of the tire frame, one of the tire frames is made slightly higher than the other, so that the axis of the integral cylinder is tilted at a small angle of 0.5° to 2° with the horizontal plane. This facilitates the slight rotation of the integral cylinder under gravity during assembly, making positioning easier.

[0022] Furthermore, the laser beam emitted by the laser scribing instrument forms a reference plane. Within this reference plane, a height vernier caliper or dial indicator with digital display is used to sequentially measure the actual distance between each detection point on the four base surfaces and the reference plane, and the deviation is calculated.

[0023] Furthermore, after completing the overall machining of the base surfaces of the four supports, the integral cylinder is re-hoisted onto the tire roller frame. Using the machined support base surfaces as a reference, a laser alignment instrument is used to align the axis of the integral cylinder, and then the sealing surfaces of the flanges at each pipe opening on the reactor are precision machined.

[0024] Furthermore, after the reaction bed is installed into the first and second cylindrical sections respectively, temporary fastening fixtures are used to fix it to the inner wall of the corresponding cylindrical section to prevent displacement during subsequent hoisting and assembly.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1) The SCR reactor shell of this invention is assembled by segmentation. After the two sections of the shell are cold-rolled into a cylinder, the two sections of the reactor shell are internally supported and fixed by a support to prevent deformation during subsequent assembly and welding. The support consists of two supports, fully threaded bolts and nuts. After the support is assembled with the two sections of the shell, the arc plates at both ends of the support are tightened against the shell by adjusting the nuts, which plays the role of fixing the support.

[0027] 2) Before installing the respective reaction beds of the two cylindrical sections, the assembly positions of the two end faces of the SCR reaction bed are marked inside the cylindrical section. The reaction beds are then assembled inside the two cylindrical sections before the two sections are spliced ​​together.

[0028] 3) When assembling some components on the outside of the SCR reactor, the spacing between the two sets of assembly jigs must first be adjusted to a suitable distance. The cylinder is then placed on the jig and supported to a certain height before assembly. The distance between the two rollers of each set of assembly jigs is adjustable and is suitable for assembling reactor cylinders of different diameters in all low-speed high-pressure HPSCR reactors.

[0029] 4) This invention adopts a novel approach: “segmented manufacturing → internal support reinforcement → segmented pre-installation → welding into a whole → overall precision machining.” It moves the critical internal installation process forward to the segmented state and proactively “pre-counters” subsequent deformation by installing adjustable internal supports. This process optimization invention fundamentally changes the manufacturing logic and breaks free from traditional thinking patterns.

[0030] 5) This invention transforms the problem of spatial coplanarity of the four support bases into a two-dimensional height deviation problem within the same vertical plane by rotating the jig. By combining a general laser scribing instrument with the adjustable roller jig unique to this invention, rapid, accurate, and synchronous detection of multiple dispersed mounting surfaces on large-sized workpieces is achieved. Attached Figure Description

[0031] Figure 1 This is a schematic flowchart of the assembly method of the high-pressure HPSCR reactor of the present invention;

[0032] Figure 2 This is a structural diagram of the SCR reactor of the present invention;

[0033] Figure 3 This is a schematic diagram illustrating the use of the support cylinder;

[0034] Figure 4 Schematic diagram of the supporting structure

[0035] Figure 5 Structural diagram of the reaction bed

[0036] Figure 6 A scribe line drawing of the two end faces of the reaction bed inside the cylinder.

[0037] Figure 7 Schematic diagram of the jig assembly

[0038] Figure 8 This is a schematic diagram of the bracket scribing inspection, where (a) is the front view of the laser inspection instrument in use and (b) is the side view of the laser inspection instrument in use. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0040] Please see Figure 1 , Figure 1 This is a schematic flowchart of the assembly method for the high-pressure HPSCR reactor of the present invention. As shown in the figure, the SCR reactor cylinder a is divided into two sections, a1 and a2. After each section is manufactured, a support b is installed inside the cylinder a to prevent deformation during subsequent assembly. Before splicing the two sections of the reactor cylinder a1 and a2, the reactor bed c inside each section needs to be assembled into the corresponding reactor cylinder. After the cylinder a is assembled, it is placed on the tire frame c to assemble the remaining parts. The assembly accuracy of the four supports d at the bottom of the SCR reactor is very high, and the deviation range of the bottom surface of the four supports d must not exceed 5mm. The entire assembly process can reduce welding deformation caused by subsequent welding processes through reasonable assembly procedures and tooling, ensuring that the reactor has sufficient machining allowance and that the dimensional accuracy of the machined reactor meets the requirements of the design drawings.

[0041] This embodiment takes a high-pressure HPSCR reactor for a certain type of marine low-speed diesel engine as an example. The steps are as follows:

[0042] Step S1. Prefabrication of segmented cylinders and installation of internal supports

[0043] See Figure 2 , Figure 3 and Figure 4 The cylinder of the HPSCR reactor is manufactured using a segmented process. First, the cylinder a is divided into two sections: the first section a1 and the second section a2. These sections are then cut, cold-worked, rolled, and welded with longitudinal seams.

[0044] Before subsequent welding of each cylindrical section a1, a2, a crucial deformation-resistant step is the installation of an adjustable internal support structure b. This support structure b consists of two arc-shaped support plates b1 (their curvature matching the inner wall curvature of the cylindrical section), a fully threaded long bolt b2, and four adjusting nuts b3 (two at each end for locking). During installation, the support structure b is placed inside cylindrical sections a1, a2. By simultaneously tightening the nuts b3 at both ends, the two arc-shaped support plates b1 are driven to move towards each other along the bolt axis until their arc-shaped working surfaces are fully in contact with the inner wall of the cylindrical section, generating sufficient pre-tightening force. This step provides strong internal rigid support for each cylindrical section, effectively resisting elliptic deformation and shrinkage deformation caused by its own weight and welding stress during subsequent hoisting, flipping, and component welding.

[0045] Step S2. Segmentation, positioning, and pre-installation of the reaction bed

[0046] like Figure 5 and Figure 6 As shown, after the internal support installation is completed, the reactor bed c is pre-installed in sections. This is crucial to ensuring the final installation accuracy of the reactor bed. Before the reactor bed c in each of the two cylindrical sections (first section a1 and second section a2), the theoretical assembly position lines of the two end faces of the reactor bed c are marked inside each section using an optical scribing instrument or a laser tracker. Subsequently, according to the marked positions, the reactor bed c is hoisted into and fixed inside the corresponding section a1 or a2. By pre-marking the positioning inside the cylindrical section, and taking advantage of the larger operating space and better field of vision in the segmented state, the reactor bed is installed in a segmented state, avoiding the installation difficulties and accumulated errors caused by the narrow internal space and difficulty in tracing the positioning benchmark after the integral cylindrical section is formed, thus improving installation accuracy and efficiency.

[0047] Step S3. Cylinder assembly and jig-assisted assembly

[0048] After completing the above steps, the two cylindrical sections a1 and a2, which already have the built-in reaction bed c and support structure b, are joined together to form a complete reactor cylinder a.

[0049] like Figure 7 As shown, the assembled integral cylinder a is hoisted onto two pre-set sets of tire roller frames c. The roller spacing of these tire roller frames c can be adjusted according to the diameter of different reactor cylinder models (e.g., through stepless adjustment via slide rails or lead screw mechanisms), and the support height can be adjusted hydraulically or mechanically. After supporting cylinder a to a certain height, assembly can be carried out. The rolling function of the tire roller frames allows for convenient rotation of the cylinder, facilitating the assembly and welding of external components such as guide vanes, end caps, various pipes, and flanges, greatly improving assembly efficiency and operational safety.

[0050] Step S4. Bracket Installation and Laser Inspection

[0051] See Figure 8 The four supports d mounted at the bottom of the SCR reactor are key components connecting to the hull base, requiring extremely high precision in the coplanarity of their mounting surfaces and their height. After all major welding work is completed, the assembly and precision control of the supports d are carried out.

[0052] 1. Initially weld the four supports d to the designed positions at the bottom of the cylinder a;

[0053] 2. By rotating the tire frame c, the base surfaces of the four supports d are precisely rotated to the same side perpendicular to the horizontal plane; this transforms the three-dimensional coplanarity measurement problem into a two-dimensional height deviation measurement problem, simplifying the measurement difficulty.

[0054] 3. Use a laser scribing instrument to establish a horizontal laser reference surface, and sequentially scan and measure the height values ​​of the pre-scribed inspection lines on the four bracket base surfaces. By comparing the height data of the four surfaces, calculate the maximum deviation between them. If the deviation exceeds 5mm, fine-tune the bracket installation position or correct the welding posture until the height deviation of the four base surfaces is controlled within 5mm, leaving machining allowance for subsequent overall processing.

[0055] 4. After confirming the accuracy, the final welding of bracket d is completed. This strict deviation control ensures that each bracket base plate has a uniform and sufficient machining allowance during the subsequent overall milling process (ultimately ensuring that the machining removal amount does not exceed 10mm), thereby efficiently obtaining a high-precision final product that fully meets the design drawing requirements.

[0056] This invention, through the organic combination of a series of innovative processes and tooling, such as "internal support to suppress deformation", "segmented pre-assembly to ensure accuracy", "adjustable jig to increase flexibility" and "laser detection to control deviation", forms a complete, efficient and reliable high-pressure HPSCR reactor assembly process, which effectively solves the problem of deformation control and accuracy assurance in the manufacturing of large thin-walled welded structural components.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for assembling a high-pressure HPSCR reactor, characterized in that, Includes the following steps: The reactor cylinder is manufactured in sections, consisting of a first section and a second section. An adjustable internal support structure is installed inside each cylinder section. By adjusting the internal support structure, the arc surfaces at both ends of the structure are radially pressed against the inner wall of the cylinder section to provide internal rigid support for the cylinder and suppress deformation during subsequent assembly and welding processes. Mark the assembly positions of the two end faces of the reactor bed inside each cylinder section, and complete the installation of the reactor bed in its respective cylinder section; The first and second cylindrical sections, which are equipped with the reaction bed and the internal support structure, are assembled to form an integral cylindrical body; The assembled integral cylinder is hoisted onto an adjustable-spacing tire rack. By adjusting the roller spacing and support height of the tire rack, it can accommodate cylinders of different diameters and assemble external components. After the welding process of the overall cylinder is completed, the four bottom supports are assembled. The base surfaces of the four supports are adjusted to the same vertical side by rotating the tire frame. The height deviation of the four base surfaces is detected by a laser scribing instrument under the same reference. The deviation range is controlled to not exceed 5mm to ensure that the base plates of each support have uniform and sufficient machining allowance during subsequent overall processing. The adjustable internal support structure includes two arc-shaped support plates, a fully threaded long bolt, and a matching nut; by tightening the nut, the two arc-shaped support plates are driven to move towards each other along the bolt axis until their arc-shaped working surfaces are completely fitted and pressed against the inner wall of the cylinder, forming a distributed internal support. The fully threaded long bolt has a centering scale line in the middle to indicate the center of symmetry of the two arc-shaped support plates; the fully threaded long bolt passes through the flat plate with the threaded hole of the arc-shaped support plate, and the two nuts are screwed to the middle position of the long bolt, and then pass through the flat plate with the threaded hole of the other arc-shaped support plate. By rotating the two nuts respectively, the two arc-shaped support plates can be driven to move towards each other or away from each other.

2. The assembly method of the high-pressure HPSCR reactor according to claim 1, characterized in that, The curvature of the arc-shaped support plate matches the curvature of the inner wall of the reactor cylinder.

3. The assembly method of the high-pressure HPSCR reactor according to claim 1, characterized in that, The roller frame includes two independent frames, and the distance between the two rollers of each frame is adjustable to accommodate reactor cylinders of different diameters.

4. The assembly method of the high-pressure HPSCR reactor according to claim 1 or 3, characterized in that, The height deviation of the base surface of the four brackets is controlled to not exceed 5mm, so that the thickness of the base plate of each bracket after subsequent overall processing does not exceed 10mm.

5. The assembly method of the high-pressure HPSCR reactor according to claim 4, characterized in that, When adjusting the support height of the tire rack, make one of the racks slightly higher than the other, so that the axis of the overall cylinder forms a small inclination angle of 0.5° to 2° with the horizontal plane. This facilitates the slight rotation of the overall cylinder under gravity during assembly, making positioning easier.

6. The assembly method of the high-pressure HPSCR reactor according to claim 1, characterized in that, The laser beam emitted by the laser scribing instrument forms a reference plane. Within this reference plane, a height vernier caliper or dial indicator with digital display is used to measure the actual distance between each detection point on the four base surfaces and the reference plane, and the deviation is calculated.

7. The assembly method of the high-pressure HPSCR reactor according to any one of claims 1-6, characterized in that, After completing the overall machining of the base surfaces of the four supports, the integral cylinder is re-hoisted onto the tire roller frame. Using the machined support base surfaces as a reference, a laser alignment instrument is used to align the axis of the integral cylinder, and then the sealing surfaces of the flanges at each pipe opening on the reactor are precision machined.

8. The assembly method of the high-pressure HPSCR reactor according to any one of claims 1-6, characterized in that, After the reaction bed is installed into the first and second cylindrical sections respectively, temporary fastening fixtures are used to fix it to the inner wall of the corresponding cylindrical section to prevent displacement during subsequent hoisting and assembly.

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