Power stations using steam turbines to drive generators are reliant on boiler feed pumps, among several other vital pieces of equipment, to ensure output to the grid matches demand from consumers. Periodic planned maintenance should ensure continued reliability, but as these pumps reach the end of their service lives, the frequency of interventions can increase and even affect the productivity of the plant.
After 28 years in service, the original group of four ring-section boiler feed pumps were starting to show their age. Typically, the pumps would have been overhauled every three years as part of a planned maintenance routine. However, more recently, the efficiency of the pumps had started to decrease and vibration levels were rising noticeably.
Sulzer assembled a team of specialist pump and mechanical engineers to conduct a study of the existing installation and to assess the most suitable solution. Having analysed the condition of the original pumps, the team concluded they had reached the end of their service lives and replacements would be needed.
In terms of time and expense, the best design would be a drop-in replacement that required minimal alterations to the surrounding infrastructure. This proposal would allow Sulzer to design, manufacture and test the new pumps off-site in preparation for a planned outage, during which the pump changeover could be completed. By creating a pump with the same external connections, the time to carry out the switch-over would be kept to a minimum.
Using the measurements taken during the initial investigation, the Sulzer team engineered a customised pump with the hydraulic design based on its MD series. The aim was to deliver the same performance with improved efficiency, which was achieved through the optimized design.
In addition to the boiler feed pump, Sulzer also supplied automatic recirculation valves, drive couplings, seals and some additional lube oil pipework. The project saw Sulzer deliver all of the design and manufacturing aspects as well as supply the ancillaries and civils works.
Once the shutdown was in place, Sulzer’s field service team started removing the original pumps and installing the replacements. The drop-in design enabled this process and the commissioning to be completed in two weeks.
Although some additional lubrication piping was required, the remainder of the surrounding infrastructure was unchanged.
Sulzer’s turnkey solution also included a training package for the operations and maintenance teams that involved hands-on and theoretical learning that would help maintain optimum performance for the new pumps.
The custom pumps from Sulzer have been in operation for two years and periodic vibration measurements have consistently returned values of just 2 mm/s – within the acceptable range and a considerable improvement on the original pumps. Furthermore, the efficiency of the pumps has been improved due to the modern hydraulic design and precision manufacturing.
As with all the other Sulzer pumps in the company’s portfolio, there is full product lifecycle support that includes expert servicing and just-in-time parts supply, which minimises the spares inventory for the facility. The new boiler feed pumps have ensured uninterrupted operational continuity for the power plant and allowed the maintenance team to focus efforts on other areas in need of optimisation.