Top condenser of ammonia evaporation tower in soda ash industry
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In the soda ash industry, the condenser at the top of the ammonia vaporization tower has the ammonia vapor flowing through the tube side from bottom to top, while the cooling water flows through the shell side. The ammonia vapor contains saturated water vapor, and the condensate is discharged from the head of the lower tube box. In my opinion, this constitutes a reflux condenser; when using the reflux condenser model in HTFS for calculations, the program indicates that the critical flow velocity in the tube side is 7 M/S (I believe that beyond this velocity, the condensate will not be able to flow out of the lower tube box due to gravity), yet the actual calculated flow velocity in the tube side is greater than 20 M/S. I suggested to the user that the ammonia vapor should flow from top to bottom, but they refused, stating that the equipment currently in use operates well with the existing flow pattern. They mentioned that the equipment needs to be replaced due to tube sheet corrosion. I consulted the process design engineers at the Eighth Chemical Research Institute on this issue, and they recommended that an optimal flow velocity inside the tubes be around 4 M/S. I’m very confused now and don’t know which figure to trust; I would appreciate some guidance from those with more experience. Thank you in advance.
Regarding the question you raised, I used it at my previous employer. In my opinion, when designing, considering an inlet at the bottom and an outlet at the top is a viable option; however, the flow rate must be reduced. A high flow rate can significantly affect the service life of the equipment. It is also recommended to use titanium tubes for the heat exchange tubes. The 316L heat exchange tubes we used before developed numerous leakage points resembling erosion corrosion at the lower inlet of the heat exchanger in less than a year. I haven’t calculated the specific flow rate
Reply to 1# yajie0321: What is the ammonia vaporization process used in your area? In our tower’s top condenser, the ammonia gas flows through the shell side while the cooling water flows through the tube side; having the gas flow through the shell side results in less resistance, which facilitates achieving a higher distillation vacuum