Pump impeller
Thread Content
Since heat exchangers often get clogged, it is possible to increase the pressure of the pump in order to raise the flow rate of the fluid within the pipes (the effect on heat exchange is not considered for now). Since the pipes cannot be modified, is it possible to increase the diameter of the impeller? What factors should be considered when making changes? (Centrifugal pump)
For centrifugal pumps, generally, without changing the size of the volute, it is possible to adjust pressure and flow within a certain range by cutting the impeller, and calculations can be carried out using similarity laws.
By changing the number of poles of the motor, the ideal flow rate can be determined by calculating the relationship between the speed of the water pump impeller and the shaft speed.
Whether it is possible to increase the impeller diameter depends on whether the impeller of that pump already represents the maximum size allowed for it. If it isn’t the maximum size, the impeller cutting formula can be used to calculate how much the head pressure can be increased. If the impeller diameter is to be increased, it is first necessary to calculate the shaft power required after the head increase, to determine whether the motor can meet that requirement. Secondly, it is necessary to consider the pressure tolerance of the downstream equipment after the pump.
By changing the diameter of the impeller, do you mean to replace the equipment? Because, from a design perspective, the equipment is designed taking all relevant factors into full consideration. From a safety perspective, it is not recommended to change the impeller; instead, you can adjust the frequency of the motor, increase its speed, and thereby enhance its output.
We can think about this from another perspective: to increase the flow rate of the fluid within the heat exchanger tubes, it is necessary to raise the flow rate of that fluid. Raising the flow rate means increasing the output flow of the pump. According to the performance curve of centrifugal pumps, this requires reducing the pump’s head, in other words, lowering the outlet pressure of the pump. Therefore, the outlet pressure of the pump can be reduced by decreasing the resistance losses in the pump’s outlet pipeline or by reducing the back pressure at the pump’s outlet, thereby increasing the pump’s output flow. The resistance loss in the pump outlet pipeline or the back pressure at the pump outlet can be reduced through process adjustments. If the process cannot be adjusted and it is desired to increase the flow rate at the pump outlet, given that the impeller of a centrifugal pump is designed with specific cuts, then simply replacing it with the original impeller will suffice. If that still doesn’t meet the requirements, the only option is to replace the pump.
When replacing the impeller, the main consideration is whether the motor can handle it.
1. Fully consider the relationship between impeller diameter and power, with a calculation formula available. 2. Adding chemicals can be considered as a solution.
Increasing the impeller diameter can lead to an increase in pressure, but at the same time the flow rate also increases. To increase the pressure, the design pressure of the heat exchanger must be taken into account.