【Ten Years of Great Development in Chemical Processing Equipment】Domestic production projects for multi-channel piston valves from 1996 to 2009
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This post was last edited by Desert Fish on 2023-6-14 at 11:03. A decade of significant development in chemical processing equipment – let’s celebrate the prosperity and strength of modern China. This is just a starting point; more participation will make things even more lively. Haichuan becomes better with your involvement; we welcome everyone to engage more in discussions on this forum. Everyone should pay attention to safety and know how to handle emergencies. ********************************************* In 2019, CNNC took on the task of developing domestic versions of multi-channel plug valves for Sinopec. Multi-channel plug valves have a complex and diverse structure; the fluid involved is heavy residue with high viscosity. The ports of each channel are subjected to different end loads, and in addition, the uneven temperature distribution at high temperatures further complicates the design, making it much more complex than that of ordinary valves. As a project developer, Li Taiping optimized the flow pattern of the process medium within the valve cavity, developed a wavy rotating plunger structure to achieve a design free from flow dead zones, and resolved the issue of deposits in the valve cavity. At the same time, various mechanical models resulting from multi-channel stress combinations were established, and finite element analysis was carried out on these models to ensure that the strength and stiffness designs of the valve body structure could meet the pressure-bearing and external load requirements of the pipeline system design.
Selection of materials and manufacturing processes for slurry valves: Given that the operating temperature in slurry bed reactors can reach 450°C and the pressure can be as high as 2500 pounds, as well as considering the sulfur content in residue oil, materials chosen are mainly stainless steels and alloy steels with high resistance to high temperatures and pressures as well as corrosion resistance, such as 105A/WCB, F316/CF8M, F316L/CF3M, F347/CF8C, F5/C5, F9/C9, F12/C12, etc. Currently, the main design for valve bodies is ‘fabricated’ through welding or a combination of forging and welding; there are also slurry valves with simpler structures that are made via solid casting or solid forging. For slurry valves of high weight classes of 900 pounds and above, the connection method to the process pipelines is butt welding BW, while for low weight classes of 600 pounds and below, flange connection is used. For multi-port valves with complex structures (three ports or more), it is generally not practical to use integral casting or forging, mainly due to the high difficulty of manufacturing, high costs, low yield rates, and long production cycles. Instead, it is necessary to divide the valve into several parts for processing, which are then welded together to form a single unit. Foreign patent holders and leading slurry valve manufacturers recommend the all-forged welding manufacturing process, in which all components are forged. Given the understanding of welding processes among domestic leading design institutes, as well as the entrenched thinking in the oil refining industry over the years, extensive discussions were held with international manufacturers regarding this manufacturing process; ultimately, the \"Fabricated\" manufacturing approach that combines forging and casting with welding was adopted. That is, the central component is made by forging or centrifugal casting ； The plunger valve is manufactured through integral casting, which eliminates the fillet welds between the valve’s branches and the valve body; finally, multiple plunger valves are welded to the central component using butt welding, and RT radiography is performed for inspection.