Environmental impact of electricity production has come under increasing international scrutiny over the last few decades. In particular, fossil fuel-fired power plants constitute a significant portion of the world’s carbon dioxide emissions. One of the main internal energy-consuming components in a thermal power plant is the main boiler feedwater pump, and its efficiency is a contributor to overall plant efficiency.
This paper reports the design optimization of a 30 MW multistage, double-case, volute pump in order to increase overall efficiency by at least three percentage points. The six stage barrel pump produces 3865 m (12680 ft) of head at a capacity of 2750 m3/hr (12100 USGPM) at a speed of 4665 RPM. The machine is installed at the coal-fired supercritical Nuon Hemweg 8 power station in Amsterdam, the Netherlands, as the main boiler feedwater pump.
The design study employed Computational Fluid Dynamics (CFD) to identify energy losses and evaluate design iterations. This paper describes the optimization of several individual components, including volutes, short and long crossovers, suction box and final discharge. Scaled model tests were conducted on series stages to validate the CFD results. Additional design constraint that had to be taken into account was that new hardware had to be installed within the limits of the existing pressure boundary components, sealing device and bearing design, which confines the design space considerably. Hardware has, at the time of writing this paper, entered production and is planned to be installed during a May 2013 plant outage.