The distillation tower selects a thermosyphon reboiler

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Today, I performed a simulation of a distillation column; I selected a kettle reboiler directly, and the hydraulic data showed that everything was normal. Later, in order to calculate the heat exchanger, the kettle was replaced with a thermosyphon reboiler; the first of the three types of thermosyphon reboilers provided by the software was chosen. It was found that the hydraulic data for the penultimate tray were quite unusual – the gas-phase load was about twice that of a kettle reboiler, while the liquid-phase load remained the same. I spent the whole afternoon trying to figure out why the gas load on the penultimate tray was so high. In the schematic diagram of the software’s thermal siphon reboiler, the vapor flowing to the second-to-last tray consists not only of the vapor returning from the reboiler but also of a portion resulting from the evaporation of the liquid at the bottom of the tower. Could it be this amount that causes the high vapor load?