| dc.description.abstract | This document presents a comparative analysis between the use of a Grundfos CRE 15-3 variable speed centrifugal pump and a Worthington D-824 constant speed centrifugal pump in a steam power plant application. This was performed since, in many applications that require pumping systems, the pumps account for the majority of the energy expenses; and it is believed that, by using variable speed pumps in such applications, the pumps could help increase savings with regard to energy costs. In the steam power plant located at The University of Kansas, these two pumps must supply water to a deaerator tank and to a heat exchanger, where the deaerator tank is the tank that provides water to the boilers inside the power plant. The heat exchanger is only used to capture the steam that is unused by the plant, turning such steam into water that can be reused to again supply water to the deaerator tank. The Grundfos CRE 15-3 has the ability to run in discharge pressure mode as well as level control mode, while the Worthington D-824 is only able to run in discharge pressure mode. With that in mind, data concerning the discharge pressure, flow rate and power consumption was collected when either the Grundfos CRE 15-3 variable speed pump or the Worthington D-824 supplied water to the system. A total of four different cases were considered when gathering this data: (1) Both pumps ran in discharge pressure mode while supplying water to the deaerator tank and the heat exchanger; (2) Both pumps ran in discharge pressure mode, but for part of the day they supplied water only to the deaerator tank, and, for the other part of the day, they supplied water to both the heat exchanger and the deaerator tank; (3) The Grundfos CRE 15-3 ran in level control mode only supplying water to the deaerator tank, while the Worthington D-824 ran in discharge pressure mode only supplying water to the deaerator tank; (4) The Grundfos CRE 15-3 ran in level control mode only supplying water to the deaerator tank, while the Worthington D-824 ran in discharge pressure mode supplying water to both the deaerator tank and the heat exchanger. The gathered data was then compared to the theoretical pump data from their respective pump curves. A life cycle cost analysis was performed, using the BLLC5 software provided by the Department of Energy, to see if the variable speed pump would indeed provide energy savings to the power plant as well as have a lower total life cycle cost as compared to the constant speed pump. As this document will show, energy savings can be obtained when running the Grundfos CRE 15-3 in level control mode, even though the total life cycle costs of both pumps are still fairly similar. For Case 1 the Worthington D-824 pump had a total life cycle cost that was 3.14% lower than the CRE 15-3 pumps; and both pump systems have almost identical energy consumption. When the heat exchanger valve is open in Case 2, the Worthington D-824 pump's life cycle cost is 4.56% lower than the one that of the CRE 15-3 pumps. When the heat exchanger valve is closed, the total life cycle cost of both pump systems are almost identical (0.006% difference). For Case 3, the CRE 15-3 pumps' average energy costs are 68.8% lower than the costs of the Worthington D-824 pump. Even though there is a large difference in energy costs, the CRE 15-3 pumps' total life cycle cost is only 7.89% lower than the total life cycle cost of the Worthington D-824. Finally, a direct percentage comparison cannot be given for Case 4 due to the different jobs that the two pump systems were doing while operating. However, as will be shown in this document, reasonable estimates were made in an attempt to compare these pump systems for the scenario presented in Case 4. | |
