Which pipes in the low-temperature methanol washing process need to be equipped with expansion joints?
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Recently, I came across a drawing of the low-temperature methanol wash purification process. An expansion joint is installed before the feed pump of the carbon dioxide desorption tower (with an inlet temperature of around -30 degrees), but no expansion joints are present at the inlet of the cold pump and the inlet of the hot pump, where the system temperature is at its lowest (-57 degrees). What is the reason for this? Let’s discuss!
I believe that the pressure in the carbon dioxide desorption tower is low, while the outlet pressure of the pump is high; as a result, CO2 dissociates momentarily, which is why an expansion joint is needed.
This section of pipe and container experiences significant thermal expansion and contraction, resulting in excessive stress at the pump inlet due to the expansion joints.
Now that I’m looking at your reply more carefully, I think your answer is incorrect. If the outlet pressure of the pump is high, how can desorption occur? High pressure should facilitate absorption; how can desorption take place in such a situation?
I haven’t encountered any. I hope teachers at normal universities can give some guidance
Generally, expansion joints are taken into account in the pipeline layout and purchased based on the data provided by the piping and mechanical engineering teams. It seems incorrect to include expansion joints in the process diagrams prepared by the process engineering team! Additionally, I have worked on two sets of piping systems for low-temperature methanol washing; under normal circumstances, no expansion joints are needed. Compared to high-temperature pipelines, the stresses in low-temperature pipelines are easier to manage! Hehe, just my personal opinion!
At the connection between the reboiler of the thermal regeneration tower and that of the methanol-water separation tower!