Reference no: EM133207420

The Pump Affinity Laws, sometimes called simply the Pump Laws, about which you have learned in this module, establish a process for relating the speed of the vanes of the pump impeller to the flow through the pump, the head developed by the pump, and the power consumed by the pump. These 'laws' relate specifically to situations in which variable speed pumps are used to move a working fluid. Consider, for example, the water pump on an automobile engine: as the engine speed increases, so does the water pump speed and, consequently, the flow, head, and pumping power. Of course, this example falls apart when you realize that, with the gearing changes in a car transmission, engine speed does not continuously increase. But it is nevertheless an illustrative example.

While variable speed pumps are used in some applications in some power plants (for example, Reactor Recirculation/Coolant pumps at BWRs/PWRs), most centrifugal pump applications use constant speed induction motors to drive the pump at a similarly constant speed. Consequently, the Pump Laws cannot be applied to determine system flow, head, or power response. Some other method must be used.

Describe how the flow is changed in plant systems that use constant speed centrifugal pumps.

In your descriptive post, include a discussion of the changes in system flow, head, and power, specifying how and why each changes. That is, provide a technical basis for your position.

Feel free to use drawings and diagrams, if you think they will help clarify your points.