Where is the vacuum tower bottom pump used in the vacuum tower? What is its function?

The bottom pump of a vacuum distillation tower is usually located at a low level, and the pump’s outlet is typically equipped with a pipeline that leads back to the bottom of the tower. The main function of this pipeline is to create a vacuum around the pump, thereby preventing cavitation from occurring in the pump

The question posed by the original poster has left me confused; of course, the bottom pump of a vacuum distillation column is used at the bottom of that column – where else could it be used? To prevent the bottom pump from running dry, the bottom of the vacuum distillation column generally needs to be raised; a cement skirt can be used to elevate it by about 10 meters. To reduce the pressure drop in the pump inlet pipeline, bottom-reduction pumps are also installed within the cement skirt of the vacuum tower; this allows the inlet pipeline to be shortened, thereby helping to prevent pumping action to some extent. Of course, it can also be installed below the pipe tray. The problem is that, as mentioned above, the resistance at the pump inlet increases, which may lead to greater pumping effort. As the name suggests, the function of a bottom-reduction pump is to transport the oil from the bottom of the pressure reduction tower to downstream facilities; these are usually viscosity-reduction units or directly to the heat exchange area where it exchanges heat with the oil from the bottom of the initial distillation tower