The installation of efficient, modern steam equipment for boiler systems is helping laundries achieve a number of potential energy savings.
According to Brian Johnston, regional engineer for Cheltenham-based Spirax Sarco, improving boilerhouse efficiency need not be a major investment. A wide variety of modern control equipment can be added as an when budgets allow. This equipment, when installed, can result in genuine savings.
“Tremendous cost savings can be made by improving boiler water blowdown systems which control boiler contamination,” he says. “In many boilerhouses, the blowdown valve is manually opened at regular intervals by the boiler operator and the water removed in just dumped to drain. “Using a blowdown controller that continuously monitors the build-up of total dissolved solids in the boiler and regulates the blowdown valve opening to reduce contamination is a much better option,” he explains.
Mr Johnston says efficiency can also be greatly improved by recovering the heat from the blowdown water as it flashes to steam. “The flash steam can be separated out in a flash vessel and injected into the boiler feed tank. Even greater savings can be made by passing the remaining blowdown through a heat exchanger to heat the make-up water coming into the boiler feedtank.” Less fuel is needed to produce steam from hot feedwater than from cold and, using returned condensate to raise boiler feedwater temperature by 6°C gives a fuel saving of 1%. “Ideally, feedwater should be maintained at 90°C,” Mr Johnston says.
He warns that simply feeding condensate into the top of the feedwater tank can be inefficient. “As it falls through the space above the water, vapour and energy can be lost and air will be admitted.” Pipework should be adequately insulated to prevent heat loss. This includes not only pipes, but flanged joints and the bodies of steam valves, which should all be covered by insulated boxes—“50 mm lagging can cut heat loss by 90%,” he says.