I have a question regarding the setup of the siphon reboiler in HTRI
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Dear sea friends, I would like to ask: what exactly does the \"Required liquid static head\" refer to in terms of height? Why does the heat transfer efficiency decrease as I set this value to be higher? Additionally, when I keep this value unchanged and adjust the length or height of the pipeline, there is no change at all – the heat transfer efficiency remains the same. Where is the problem? The Simulation mode is being used.
"\"Required liquid static head\" refers to the static pressure head needed in a reboiler to ensure effective circulation of the liquid, that is, the pressure generated by the weight of the liquid itself. Theoretically, the greater this height, the greater the hydrostatic pressure, which helps to drive the circulation of the liquid. However, if it is set too high, it may lead to an increase in fluid flow resistance and a decrease in circulation efficiency, thereby affecting the heat transfer performance. As for the fact that changes in the length and height of the pipes have no effect on the heat exchange efficiency, it is likely because other parameters set in the simulation mode (such as the heat transfer area and heat transfer coefficient) play a dominant role; minor changes in liquid flow do not have a significant impact on the heat exchange efficiency in the model. It may be necessary to check other settings of the HTRI model or consider certain limiting factors of the actual operating conditions. .
Hello, the owner; this is the distance from the lower tube sheet of the heat exchanger to the normal liquid level in the tower. For equipment at atmospheric or positive pressure, the upper tube sheet is generally set at the same level as the normal liquid level in the tower; this is a relatively conservative approach, so the required liquid static head is equal to the length of the heat exchange tubes. If it is less than the length of the heat exchange tube, there will be a decrease in the circulation rate, an increase in the vaporization rate, and a misty region will appear at the upper end of the heat exchange tube (I do not recommend that the vaporization rate exceed 35%; some studies suggest 50%). If it is greater than the length of the heat exchange tube, the circulation rate increases while the vaporization rate decreases; in extreme cases, no boiling will occur (the higher the pressure, the higher the boiling point), which results in no circulation. In summary, the required liquid static head should not be too short nor too long; therefore, in my designs I typically set this value to be about 0–1 meter more than the length of the heat exchange tubes.