Automatic system identification and optimization of centrifugal pump operation

Centrifugal pumps are a notable end-consumer of electrical energy. Typical application of a centrifugal pump is the filling or emptying of a reservoir tank, where the pump is often operated at a constant speed until the process is completed. Installing a frequency converter to control the motor substitutes the traditional fixed-speed pumping system, allows the optimization of rotational speed profile for the pumping tasks and enables the estimation of rotational speed and shaft torque of an induction motor without any additional measurements from the motor shaft. Utilization of variable-speed operation provides the possibility to decrease the overall energy consumption of the pumping task. The static head of the pumping process may change during the pumping task. In such systems, the minimum rotational speed changes during reservoir filling or emptying, and the minimum energy consumption can’t be achieved with a fixed rotational speed. This thesis presents embedded algorithms to automatically identify, optimize and monitor pumping processes between supply and destination reservoirs, and evaluates the changing static head –based optimization method.

Savings Calculator for Centrifugal Pumps

Centrifugal pumps are one of the major energy consuming end-devices in developed coun-tries both in industrial and services sectors. According to recent studies, even 30 % of the energy used in pumping systems could be saved by more careful choosing of devices and system design. One of the most efficient and affordable ways to decrease the energy con-sumption of the pumping system is to substitute traditionally used flow control methods, like valve control, with modern variable speed drive (VSD) control. In this thesis, Microsoft Excel based program, Savings Calculator for Centrifugal Pumps (SCCP), is designed. SCCP calculates the achievable energy and financial savings when throttle control is substituted by VSD control in the pumping system. Compared to the sim-ilar existing programs, the goal is to make SCCP calculations more accurate and require less input information. Also some useful additional features are added to the designed program to make it more user friendly. The reliability of the calculations of designed program seem to vary depending on case. The results are corresponding accurately to the laboratory measurements, but there occurs high deviations in some cases, when the results are compared to the pump information specified by manufacturer. On the basis of verification in this thesis, SCCP seems to be at least as accurate as similar existing programs and it can be used as help in investment decision whether to have VSD or not.