TSG retrofits SWRO train with APP pump to boost efficiency and reliability

TSG's client, a Bahamas resort with a growing number of luxury villas strung around a stunning golf course, was running low on water and there was little or no redundancy. So the client had already ordered a fifth 984 CMD (260,000 GPD) train from TSG to bolster its 4,164 CMD (1.1 MGD) facility's four existing trains. "We specified a Danfoss APP for the new train," explains Chip Harris, TSG's vice president and general manager, "because we have an extremely high degree of confidence in them, and now consider them to be our standard, go-to high-pressure pump for SWRO applications because of their energy efficiency, simple maintenance and reliability."

But shortly after the new pump had been delivered to the island, one of the massive old plunger pumps began showing signs of distress. Within days, bad went to worse. When pump bearings seized up and resulted in a cracked case, the catastrophic failure cost the plant 25% of its capacity in an instant.

The client, who is responsible for capital investments and improvements, quickly agreed to the unexpected retrofit. Resort managers had already understood the value of the APP for its new plant. The manufacturer of the old plunger pump had lead times of 16 weeks for anything major. Furthermore, TSG had designed the plant's four existing trains in 2008, so it knew its construction perfectly and still had all original drawings. It had also planned the new, fifth train around the Danfoss APP 53, so the simpler fittings required for this were similarly well understood.

"Sometimes you just get lucky," smiles Harris, "even in the middle of what could have been a real mess for the client. Our engineers knew the old as well as the new train intimately. We have our own full-service manufacturing facility so we could move some jobs around and quickly do all the stainless steel piping ourselves. And we just happened to have a brand new APP 53 sitting on the island, waiting for the construction guys to finish the building for the fifth train." 

In total, the emergency retrofit took less than two days, and the client did not experience any significant difficulties. Harris is convinced that the old plunger pump's failure was a blessing in disguise.

"By virtue of their design and robust construction, the Danfoss APP is the best pump we could possibly use for our operations and those of others," he says. "As the APPs get bigger and bigger, they are increasingly relevant for retrofits. Our client will probably retrofit the other three trains already next year. What used to be the most efficient pumps of their capacity back in 2008 can now be favourably replaced with APP 53."