Cost Analysis of Replacing Power Plant Cooling Water Volute Casing Pumps with Mixed Flow and Variable Pitch Propeller Pumps
Overview: Replacements are being considered for a cooling water system that currently consists of four volute casing pumps. A cost analysis is done comparing the baseline versus variable pitch propeller pumps and mixed flow pumps with variable inlet guide vanes. Mixed flow pumps have the fastest payback in this application with a payback time of 0.4 years.
Category: Blogs, Case Studies August 1, 2025
Intended Audience: Power Plant
Objective: Determine whether variable pitch propeller pumps or mixed flow pumps with variable inlet guide vanes are the more cost-efficient replacement to the volute casing pumps.
Description of System: The suction levels are the tide levels, which fluctuate in this case within a range of 7 m. The station operates at a full load capacity of 500 MW for 75 percent of the annual operating time and at 400 MW during 25 percent. The total head of the system at low tide level is 17 m (56 ft). The cooling water pump installation consists of four volutcasing pumps.
Description of Intervention: The invested alternatives are four tube type casing pumps with variable pitch hydraulics capable to adjust the pump head of the system and to save energy consumption.
See Table 1 below:
Table 1: Summary of Results
Summary of Results: Variable pitch propeller pumps resulted in 1.4 years for payback. Mixed flow pumps with variable inlet guide vanes resulted in 0.4 year for payback. The details for these costs are shown in Table 1.
Conclusion: Pumps operate near to BEP and vibration and bearing loads are minimized. The variable geometry can also provide higher efficiencies than variable frequency, but the design is mechanically more complex with higher parts count.
Written by:
Members of the Committee, 1st Edition
Published In: Pump Life Cycle Cost: A Guide to LCC Analysis for Pumping Systems, 2nd Edition
Year of Publication: 2021
Pump Life Cycle Costs: A Guide to LCC Analysis for Pumping Systems – 2nd Edition – Pumps.org
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