Calculation of propylene vaporizer flow rate
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I encountered a shell-and-tube propylene vaporizer, in which propylene flows through the shell side, while the tube side carries a mixture of ethylene and methane, with ethylene being the predominant component at around 99%. The temperature of the propylene in the shell side remains constant; only phase change occurs there. The pipeline flow rate is 280 t/h, the temperature at the inlet is -30 degrees, at the outlet it is -34.8 degrees, and the pressure is 1.866 MPa. The shell-side flow rate is 230 t/h, the temperature is -40 degrees, and the pressure is 0.042 MPa. I now want to increase the flow rate in the shell side in order to boost production. I’m wondering if anyone experienced can help calculate how high the shell side flow rate can be increased Or if you know the calculation method, you can tell me that as well. Thank you!
This can be calculated using htri; it’s very simple
First of all, your question is itself a problem. 1. To increase the flow rate on the shell side, it is first necessary to verify whether heat exchange is balanced; if even heat exchange balance cannot be achieved, what is the point of making any modifications? 2. If heat exchange equilibrium can be achieved, with the current heat exchange area of this exchanger, can it deliver the desired heat exchange effect? 3. If both of the previous conditions are met and the flow rate on the shell side is increased, resulting in changes in pressure and flow velocity, will the heat exchanger design still be suitable for such operating conditions?
I really don’t understand it either. A friend asked me to inquire on his behalf; I’m not sure if this is appropriate or not. If the teacher has any suggestions, I would be extremely grateful if you could share them so that I can learn from them as well!
The simplest way is to first find out what the design margin for this equipment was originally. Then, assume by what percentage the amount of propylene needs to increase, and determine whether that design margin is sufficient. If you want to consider things carefully, it is possible to make such estimates; however, the temperature or amount of ethylene may change as a result (when the flow rate of propylene increases and the equipment remains unchanged, the flow velocity will also be affected, which in turn affects the heat exchange efficiency)