Method for manufacturing super-thick aluminum-magnesium alloy pre-deethanization condenser in cryogenic industry

Abstract

The invention discloses a manufacturing method of a super-thick aluminum-magnesium alloy pre-deethanization condenser in the cryogenic industry, and belongs to the technical field of cryogenic equipment manufacturing. According to the method, for an aluminum alloy material with the wall thickness larger than 90 mm, firstly, an equipment barrel is divided into an upper section and a lower section, and a main datum line and an auxiliary datum line are set respectively to control the manufacturing precision; welding shrinkage data are obtained by welding equal-thickness test plates, and plate blanking and assembly gaps are accurately guided. And the segmented cylinder bodies are welded by adopting a special process: preheating before welding, protecting by adopting helium-argon mixed gas, and carrying out layering quality control of penetration detection after bottoming and semi-thickness ray detection. The tapping precision of the connecting pipe is controlled to be 50% of the standard value, and allowance is reserved for closing. And finally, the two sections of cylinder bodies are welded into a whole through a final circular seam at a folding station, and manufacturing is completed after size rechecking, pressure testing and nitrogen sealing. According to the manufacturing method provided by the invention, the technical problems of large deformation, low precision and difficult welding in the manufacturing of ultra-thick aluminum magnesium alloy equipment are solved.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic equipment manufacturing technology, specifically relating to a method for manufacturing an ultra-thick aluminum-magnesium alloy pre-deethane condenser for the cryogenic industry. Background Technology

[0002] Pre-de-ethane condensers are key equipment in the cryogenic industry, especially in the petrochemical sector, and are typically located between the cracked gas compression unit and the cryogenic separation zone in an ethylene plant. Their main function is to perform preliminary separation of the cracked gas, separating light components such as hydrogen and methane from C2 (ethane and ethylene) and C3+ (propane, propylene, and heavier components), thereby preventing the light components from entering the downstream demethanizing system. This separation process can significantly reduce the size and energy consumption of the demethanizing tower and its associated refrigeration system, having a significant impact on the economy and energy efficiency of the entire production process.

[0003] Because pre-de-ethane condensers often operate in cryogenic environments ranging from -40°C to -60°C or even lower, the requirements for the low-temperature performance of materials are extremely stringent. Traditional manufacturing often uses high-quality low-temperature steel, which must pass rigorous low-temperature impact toughness tests, resulting in high raw material costs. In fact, under ultra-low temperature conditions, aluminum alloys typically exhibit superior mechanical properties and toughness compared to steel. Replacing steel with aluminum alloys could not only effectively reduce material costs but also further improve the overall performance of the equipment.

[0004] However, aluminum alloys are generally weaker than steel. To achieve the same load-bearing and sealing capabilities, the wall thickness must be significantly increased, posing a severe challenge to the manufacturing process, especially in the welding and cold forming of ultra-thick aluminum plates. Currently, there is a lack of mature manufacturing technologies for ultra-thick aluminum-magnesium alloy structures in the industry. Overcoming the relevant process bottlenecks and achieving reliable manufacturing will be of great significance to the technological development of pre-ethane removal condensers. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for manufacturing an ultra-thick aluminum-magnesium alloy pre-deethane condenser for the cryogenic industry.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] This invention provides a method for manufacturing an ultra-thick aluminum-magnesium alloy pre-deethane condenser, the specific steps of which are as follows:

[0008] S1: According to the design drawing, the condenser shell to be manufactured is divided into upper and lower sections along the axis, and a closing weld is set at the middle section position; a main reference line and an auxiliary reference line for manufacturing the internal structure are determined in the lower and upper sections of the condenser shell to be manufactured, respectively.

[0009] S2: After rolling the corrected sheet metal, weld the longitudinal seam using the Class A weld method and complete the rounding to obtain the upper and lower complete cylinder sections respectively; based on the actual height of the welded upper and lower cylinder sections, estimate the total length of the condenser cylinder after closing, adjust the positioning of the auxiliary baseline to ensure that the elevation of all pipe openings and the total height meet the preset requirements;

[0010] S3: Place the upper and lower cylindrical sections on the roller frame, and mark the positions of all pipe openings, internal and external parts according to the drawings; after quality inspection, make the openings, and weld the accessories using the Class D weld method;

[0011] S4: After the upper and lower sections of the cylinder are manufactured, they are transferred to the closure station and the closure weld is fixed by using Class B weld welding.

[0012] Preferably, the main reference line of the lower section of the condenser shell is used as the measurement reference for the two sections to be joined together.

[0013] Preferably, the sheet material used to manufacture the condenser shell is an aluminum alloy sheet with a thickness greater than 90 mm.

[0014] As a preferred embodiment, the welding methods for Class A welds and Class B welds are as follows:

[0015] Before welding, the weld area is preheated and kept warm using a heater. During welding, a helium-argon mixture is used as the protective gas, with a volume ratio of helium to argon of (1~3):(3~1), and the gas flow rate is controlled at 20~40L / min. After the root pass welding is completed, penetrant testing is used to detect surface defects in the weld. After the penetrant testing is passed, open arc welding is used for filling. When the weld is filled to half the thickness of the cylinder wall, welding is paused and radiographic testing is performed. After the radiographic testing is passed, the weld filling continues and the capping weld is completed.

[0016] Furthermore, the heater is an LDC type tracked ceramic electric heater; the volume ratio of helium to argon in the helium-argon mixture is 1:1, and the gas flow rate is controlled at 35L / min.

[0017] Furthermore, the open arc welding process uses an ESAB-630 power supply, selects ER5556 welding wire with a diameter of 2.4mm, and the fill welding current is 360A~380A, with a welding voltage of 27V; the cover welding current is 340A~360A, with a welding voltage of 27V.

[0018] As a preferred embodiment, the welding method for the type D weld is as follows:

[0019] First, tungsten inert gas (TIG) welding is used for the root pass, followed by open arc welding for the intermediate filler layer, and finally TIG welding is used for the cover pass. After welding, penetrant testing and ultrasonic testing are performed.

[0020] As a preferred option, the coordinate accuracy of the pipe opening position in step S3 is 50% of the standard requirement, so as to reserve error tolerance space for subsequent welding shrinkage.

[0021] Preferably, before cutting the material, the longitudinal and circumferential seams of a plate of the same thickness as the condenser shell to be manufactured are welded to obtain the actual weld shrinkage data of the plate. Based on the obtained shrinkage data, the dimensional allowance for subsequent shell plate cutting and the welding gap during shell section assembly are determined.

[0022] As a preferred option, in step S4, after the weld seam is closed, the pipe port coordinates and equipment height are checked; finally, pressure testing and nitrogen sealing are performed to obtain an ultra-thick aluminum-magnesium alloy pre-deethane condenser.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) This invention innovatively proposes a manufacturing method of segmented manufacturing with main and auxiliary dual baselines and final assembly, which divides the equipment into upper and lower sections that can be manufactured simultaneously, greatly shortening the overall production cycle. During the manufacturing process, strict dimensional control and multiple rounds of measurement are implemented for each section to ensure that the overall dimensions after final assembly accurately meet the design requirements.

[0025] (2) In this invention, ultrasonic testing is innovatively applied to the D-type welds of the nozzle and the cylinder. Based on the industry standard for testing A and B-type welds, the non-destructive testing requirements for key fillet welds are further improved, thereby more effectively ensuring the overall quality and safety reliability of the equipment.

[0026] (3) Before formal material preparation, the present invention determines the shrinkage allowance of thick-walled welds by welding test pieces, and guides the addition of cylinder section size allowances and the determination of welding gaps during the assembly stage based on the actual welding shrinkage allowance. By actively offsetting deformation from the source, precise control of the final product size is achieved. Attached Figure Description

[0027] Figure 1 Overall flow chart of the manufacturing method of ultra-thick aluminum-magnesium alloy pre-deethane condenser provided by the present invention;

[0028] Figure 2 This is a schematic diagram showing the baseline and weld seam settings in this embodiment;

[0029] Figure 3 This is a schematic diagram of the welding equipment used in this embodiment;

[0030] In the diagram: 1. Main reference line, 2. Closing weld, 3. Auxiliary reference line, 4. Internal component. Detailed Implementation

[0031] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0032] As a preferred embodiment of the present invention, this embodiment provides a method for manufacturing an ultra-thick aluminum-magnesium alloy pre-deethane condenser, the overall flow chart of which is shown below. Figure 1 As shown, the specific steps are as follows:

[0033] Step 1: Segmented Planning and Benchmark Establishment

[0034] According to the overall equipment design drawing, the condenser shell to be manufactured is divided into upper and lower sections along the axis, and a closing weld 2 is set at the middle section. Manufacturing the equipment in two sections separately can reduce the manufacturing time by half.

[0035] like Figure 2 As shown, a main reference line 1 is determined in the lower section of the condenser shell to be manufactured. This main reference line 1 originates from the original reference line in the equipment general drawing. It serves not only as the dimensional reference line during the manufacturing of the lower section but also as the measurement reference line for the final inspection of the entire equipment after the two sections are joined, thereby ensuring the consistency and continuity of the reference lines. An auxiliary reference line 3 is determined in the upper section of the condenser shell to be manufactured for the manufacturing of the internal structure. The auxiliary reference line 3 is used for dimensional control of the internal components 4 during the manufacturing process of the upper section.

[0036] To ensure the final assembly accuracy, the dimensional deviations of the upper and lower sections of the cylinder after segmentation must be set to be stricter than those in the overall equipment design drawing. For example, the dimensional deviation of the upper and lower sections of the cylinder should be ±2.0mm to meet the acceptance conditions of the equipment after final assembly.

[0037] Step 2: Cutting the sheet material

[0038] Before formal product cutting, a welding process qualification test is conducted: using aluminum plates of the same thickness as the product cylinder, simulated longitudinal and circumferential seams are welded, and the actual shrinkage dimensions of the welds are measured. This data forms the basis for subsequent precision manufacturing. Based on the obtained shrinkage dimension data, the dimensional allowance for subsequent cylinder plate cutting and the welding gap during cylinder section assembly are determined.

[0039] During the actual cutting process, except for the last sheet, the actual dimensions of each sheet cut are immediately measured and recorded. The sum of the actual dimensions of all cut sheets is accumulated and compared with the theoretical dimensions on the drawings to determine the cumulative error. This error is then compensated for and eliminated when cutting the last cylindrical sheet. This method ensures the accuracy of the total length of the sheet metal used for each section of the cylindrical body from the source.

[0040] Step 3: Cylindrical Forming

[0041] The precisely cut sheet metal is rolled into shape, and longitudinal seams are welded using Class A welding methods, followed by rounding to obtain complete upper and lower cylinder sections. The equipment used in the welding process includes... Figure 3 As shown.

[0042] After welding, the actual heights of the upper and lower cylindrical sections are measured separately to estimate the total length of the assembled equipment. Based on this estimated total length and the measured height of the lower cylindrical section, the positioning of the upper auxiliary reference line 3 is calculated and adjusted in reverse. This step is crucial for dimensional pre-control, aiming to proactively compensate for welding shrinkage and ensure that the elevation of all pipe openings and other key external dimensions such as the total height of the equipment meet the preset high standard requirement of ±2.0mm.

[0043] Step 4: Drilling and welding accessories

[0044] Place the upper and lower cylindrical sections on the roller frame respectively. Accurately mark the positions of all pipe openings, internal parts 4, and external parts according to the drawings. After the quality inspectors have checked and confirmed that there are no errors, proceed with the opening operation. During this process, it is necessary to ensure that the coordinate accuracy of the opening is 50% of the standard requirement to prevent the error after assembly from exceeding the standard requirement range.

[0045] After drilling, the connecting pipe, internal parts 4, and other accessories are installed. For the Class D weld between the connecting pipe and the cylinder, a composite welding process is adopted, as follows: First, gas tungsten inert gas (GTAW) is used for the root pass; then, open arc welding (GMAW) is used for the intermediate filler layer; and finally, gas tungsten inert gas (GTAW) is used for the cap pass to obtain a beautiful and corrosion-resistant weld surface. After welding, penetrant testing (PT) and ultrasonic testing (UT) are immediately performed. The PT quality meets the Class I requirements of NB / T47013.5, and the ultrasonic testing quality meets the Class I requirements of NB / T 47013.3. The ultrasonic testing pass rate for the Class D weld between the connecting pipe and the cylinder reaches 99.7%, ensuring the internal quality of the weld.

[0046] Step 5: Joining and Welding

[0047] The separately manufactured upper and lower cylinder sections are transferred to a dedicated assembly station for final assembly. First, tack welding is performed to secure the closure weld 2, which is a Class B weld. After tack welding, quality control personnel comprehensively review all key dimensions, such as the coordinates of all pipe joints and the total height of the equipment, to confirm compliance with internal control standards. Once the dimensions are verified to be correct, final welding is performed on closure weld 2.

[0048] It should be noted that this invention employs the same high-standard welding process for both Type A welds (longitudinal butt welds) and Type B welds (circumferential butt welds) of the cylinder. This process is specifically designed to overcome the challenges of deformation, cracking, porosity, and insufficient penetration that easily occur when welding aluminum-magnesium alloy plates thicker than 90mm. The specific steps are as follows:

[0049] ① Before welding, the weld area is preheated and kept warm using an LDC type tracked ceramic electric heater. This method allows for rapid heating and temperature control, effectively preventing cracks during welding and avoiding surface carburization problems that may occur with flame heating, thereby improving the quality requirements and production efficiency of ultra-thick plate welding.

[0050] ② A helium-argon mixture is used as the shielding gas during welding. The volume ratio of helium to argon in the helium-argon mixture is (1~3):(3~1), and the gas flow rate is controlled at 20~40 L / min. Preferably, in this embodiment, a helium-argon mixture with a volume ratio of 1:1 is used, and the gas flow rate is controlled at 35 L / min. At this ratio, the high thermal conductivity of helium allows the arc heat to be transferred to the workpiece more efficiently, resulting in a high concentration of heat in the weld area. This not only helps maintain the welding temperature and increase the welding speed, but also significantly increases the penetration and width of the weld, and effectively reduces porosity, thereby greatly reducing welding defects.

[0051] ③ After the root pass is completed, use penetrant testing (PT) to inspect the weld surface for defects; after passing the PT test, use open arc welding for the filler weld. For the filler weld, the ESAB-630 power supply is preferred, and ER5556 welding wire with a diameter of 2.4mm is selected. The filler welding current is 360A~380A, and the welding voltage is 27V.

[0052] ④ When the weld fills to half the thickness of the cylinder wall, welding is paused for radiographic testing (RT). After passing the RT, the weld filling continues and the capping weld is completed. The capping weld welding current is 340A~360A, and the welding voltage is 27V. The parameters can be fine-tuned during the welding process according to specific circumstances. After all welding is completed, the weld is subjected to another RT test to confirm that its internal quality is completely qualified. The above procedure arrangement can avoid the difficulty of rework due to deep welding defects. In addition, using fine welding wire is beneficial for precise control of weld reinforcement and weld width, which not only reduces the difficulty of operation but also reduces the amount of subsequent grinding work caused by excessive reinforcement.

[0053] Step Six: Dimensional Verification and Inspection

[0054] After the welding was completed, the coordinates of all pipe openings, the overall height of the equipment, and other key dimensions were thoroughly checked. Once confirmed to be in good condition, a pressure test was conducted to verify its strength and sealing performance; subsequently, nitrogen purging and sealing were performed to protect the internal structure. This resulted in a qualified ultra-thick aluminum-magnesium alloy pre-deethaner condenser.

[0055] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A method of manufacturing an ultra-thick aluminum magnesium alloy pre-deethanizer condenser, characterized by, The specific steps are as follows: S1: According to the design drawing, the to-be-manufactured condenser cylinder is divided into upper and lower two sections along the axis, and a closing weld (2) is arranged at the middle section position; a main reference line (1) and an auxiliary reference line (3) for manufacturing the internal structure are determined on the lower section and the upper section of the to-be-manufactured condenser cylinder respectively; S2: After the modified plate is rolled, the longitudinal seam is welded by using the A-type weld welding method, and the circle is corrected, and the complete cylinder sections of the upper section and the lower section are obtained respectively; the total length of the closed condenser cylinder is estimated based on the actual height of the welded upper section and lower section, the positioning of the auxiliary reference line (3) is adjusted to ensure that the height of all pipe openings and the total height meet the preset requirements; S3: The upper section and the lower section are placed on the roller frame, and all pipe opening positions, internal parts (4) and external part installation positions are drawn according to the drawing; after quality inspection, the openings are opened, and the D-type weld welding method is used for welding the accessories; S4: After the upper section and the lower section are respectively manufactured, they are transferred to the closing station, and the B-type weld welding is used to weld and fix the closing weld (2).

2. The ultra-thick aluminum magnesium alloy pre-ethane-removal condenser manufacturing method according to claim 1, characterized by, The main reference line (1) of the lower section of the condenser cylinder serves as the measurement reference for the closing of the two sections.

3. The ultra-thick aluminum magnesium alloy pre-ethane-removal condenser manufacturing method according to claim 1, characterized by, The plate for manufacturing the condenser cylinder is an aluminum alloy plate with a thickness greater than 90 mm.

4. The ultra-thick aluminum magnesium alloy pre-ethane-frac condenser manufacturing method of claim 1, wherein, The A-type weld welding and B-type weld welding methods are as follows: Before welding, a heater is used for preheating and heat preservation of the weld area; during the welding process, helium-argon mixed gas is used as the protective gas, the volume ratio of helium to argon in the helium-argon mixed gas is (1-3):(3-1), and the gas flow is controlled at 20-40 L / min; after the backing welding is completed, the surface defects of the weld are detected by using penetration detection; after the penetration detection passes, the open-arc welding is used for filling; when the weld filling is half of the thickness of the cylinder wall, the welding is paused, and the radiographic inspection is performed; after the radiographic inspection passes, the weld filling is continued and the cover welding is completed.

5. The ultra-thick aluminum magnesium alloy pre-ethane-frac condenser manufacturing method of claim 4, wherein, The heater uses an LDC type crawler type ceramic electric heater; the volume ratio of helium to argon in the helium-argon mixed gas is 1:1, and the gas flow is controlled at 35 L / min.

6. The method of claim 4, wherein the super-thick aluminum magnesium alloy pre- deethanizer condenser is manufactured by the steps of: The open-arc welding process uses an ESAB-630 power source, selects an ER5556 welding wire with a diameter of 2.4 mm, the filling welding current is 360A-380A, and the welding voltage is 27V; the cover welding current is 340A-360A, and the welding voltage is 27V.

7. The ultra-thick aluminum magnesium alloy pre-ethane-frac condenser manufacturing method of claim 1, wherein, The D-type weld welding method is as follows: First, the backing welding is performed by using tungsten inert gas arc welding, the middle filler layer uses open-arc welding, and finally the cover is welded by using tungsten inert gas arc welding; after the welding is completed, the penetration detection and ultrasonic detection are used.

8. The ultra-thick aluminum magnesium alloy pre-ethane-frac condenser manufacturing method of claim 1, wherein, In step S3, the coordinate accuracy of the pipe opening position is 50% of the standard requirement, which reserves a fault tolerance space for the subsequent closing welding shrinkage.

9. The ultra-thick aluminum magnesium alloy pre-ethane-frac condenser manufacturing method of claim 1, wherein, Before cutting, the longitudinal seam and the ring seam of the plate with the same thickness as the to-be-manufactured condenser cylinder are welded to obtain the actual weld shrinkage size data of the plate; according to the obtained shrinkage size data, the size allowance of the subsequent cylinder plate cutting and the welding gap of the cylinder section assembly are determined.

10. The ultra-thick aluminum magnesium alloy pre-ethane-frac condenser manufacturing method of claim 1, wherein, Step S4, the welding of the weld (2) is completed, the pipe opening coordinates and the equipment height are reviewed, and finally the pressure test and nitrogen sealing are performed to obtain the super-thick aluminum-magnesium alloy pre-deethanizing condenser.

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