Selection and calculation issues for methanol & propanol condensers
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Hello everyone. I am currently working on the process design for a project that involves the recovery of methanol and propanol as solvents. The volume ratio of methanol to propanol is 1:10, and the operation takes place at atmospheric pressure. The evaporation rate is 1200 kg/h, and the condensate is cooled to 40 degrees Celsius. I plan to use three stages of condensation: the first two stages will utilize normal-temperature circulating water, while the third stage will use water from a cooling tower. Shell-and-tube heat exchangers will be used for the first two stages, in addition to a spiral plate heat exchanger connected in series. Is this approach feasible? How should the area of a heat exchanger be calculated? What size should it be? Thank you
Based on the provided operating parameters, it is indeed possible to achieve complete condensation and recovery when the temperature is reduced to 40 degrees. But why use a scheme in which all three levels are cooled by circulating water? Energy waste! In the case of vacuum condensation, a two-stage condensation system using circulating water plus chilled water is understandable. If the original design involved relatively large shell-and-tube heat exchangers, perhaps one could consider using a heat exchanger with enhanced heat transfer capabilities that is suitable for such conditions.
I think welded or brazed plate exchangers can also be used.
2# Hualong Xu: Thank you for the reminder. Does that mean my shell-and-tube heat exchanger can use tubes with corrugations or fins to enhance heat transfer? I haven’t figured out this calculation yet; I need to study it first. Also, this would require at least secondary condensation, right? If only one stage is used, could the pressure drop be too high? My preliminary calculation suggests that the heat exchange area for the condensation section is around 30 m2. After seeking advice, I was told that this heat exchanger is quite large in size; therefore, I considered splitting it into two units connected in series. However, I still feel there are issues with this calculation. It’s my first time dealing with this, so there are many things I don’t understand. Someone with experience, please take a look – what size do you think this heat exchanger will need to be? Thank you!
It is recommended to use plate-type gas exchangers (condensers). I’ve done some rough calculations: plate-type gas exchangers require little space and have a small volume; at most two stages are needed. It would be best if you could provide more detailed information about the specific operating conditions, so that we can carry out more precise calculations. Please refer to our information on plate-type gas exchangers at http://bbs.hcbbs.com/viewthread.php?tid=544041&highlight=%C6%F8%CC%E5%BB%BB%C8%C8%C6%F7. Plate-type gas exchangers offer 3–5 times higher heat exchange efficiency compared to finned tube types, and they also result in lower pressure losses on the gas side. The best approach is to use plate-type gas exchangers in the initial stage and fully welded plate exchangers in the subsequent stages. If necessary, you can send me the specific parameters via this email address: liujunjoy@126.com