Does the pump’s minimum flow line circuit lead to the container or to the inlet pipeline?

This post was last edited by ylb913 on 2016-9-29 at 23:00. The pump inlet container can be used to regulate the temperature (usually to lower it), thereby allowing for a new establishment of gas-liquid equilibrium. We have used quite a few designs for the pump return inlet so far; it depends on the flow rate at the pump outlet (excluding the return flow). It could be either the pump return inlet or a container before the pump, and ultimately it comes down to whether this will cause an increase in the pump’s temperature, which in turn could lead to the pump being emptied of fluid. As an example, this is a case where I identified a problem related to one of our top-mounted return pumps back in 1994 and implemented improvements: originally, the return flow from the pump outlet went back to the pump inlet; however, due to the low volume of this return flow and its significant fluctuations, coupled with the fact that the liquid level in the return tank was used as the main control mechanism, the fluid would often circulate back and forth between the pump’s inlet and outlet for extended periods, which caused the fluid temperature to rise continuously. As a result, the pump would frequently experience vacuum conditions. I then suggested changing the direction of the return flow to the inlet of the return tank, and that solved the problem. ——Due to the very low flow rate, initially a temporary pipe was connected via the vent on the glass plate to return the fluid to the tank while the unit was running; later, during shutdown for maintenance, it was changed to the tank inlet. It is assumed that if the pump outlet flow rate remains too low for an extended period of time, this will cause the pump body to heat up (in fact, the temperature of the medium increases), leading to the vaporization of the medium or the desorption of the absorbed substances (under normal conditions, the fluid entering the pump from the tower top reflux tank is at a saturated concentration; an increase in temperature causes desorption), which ultimately results in the pump becoming empty. ——At this point, returning to the pump inlet causes the temperature at the pump inlet to rise increasingly... If it returns to the tank and mixes with the larger amount of liquid there, the temperature will drop significantly. Even if the temperature rises, a new gas-liquid equilibrium will be established at a higher temperature; when it enters the pump inlet again, desorption will not occur, or at least it can be prevented from happening for an extended period of time, thus avoiding pump cavitation.

I think it should be connected to the inlet pipeline, especially in cases where the material is prone to crystallization, contains particles, or when the inlet pipeline is long – in such situations it’s even more necessary to connect it to the inlet pipe. It can also be joined at an angle to function as a venturi, thereby preventing cavitation

If it is a return pump, the minimum flow line leads back to the return tank； If it is a bottom pump, it will return into the tower

In fact, as long as the flow rate at the pump outlet isn’t very high and the backflow isn’t significant, the temperature won’t increase much; so it’s okay to connect it to the inlet as well

Well, it depends on the specific situation. If heating is provided, less crystallization will occur, and it should be possible to connect it to the container

Do you mean that the return line should be connected to the inlet container?

Well, it’s from where it came from, and back to there