Spirax Sarco can save you £10,000

A flash steam recovery system from Spirax Sarco is helping Leighton Hospital in Crewe, UK, reduce its carbon emissions by around 95 tonnes a year, cutting fuel bills by over £10,000.

The skid-mounted system is fitted on the condensate return from the hospital laundry. Around 1,500 kg/h of condensate heads back to the boiler room from the laundry, but an estimated 14% of this was previously vented to atmosphere as flash steam. The new recovery unit retains all this useful energy within the system and uses the flash steam to pre-heat the feed water for the laundry boiler. The feed water used to pass directly from the hot well to the boiler at around 80°C, the flash steam now heats it under pressure to between 120 and 140°C - a rise of over 40°C.

"When we first calculated the potential savings, they worked out at over £17,000 a year," says Adam Lane, Energy Engineer at Leighton Hospital. "As gas prices have fallen they’re more like £10,000, but that doesn’t alter the amount we’ve managed to cut our emissions by. We’re also reducing the amount of make-up water and dosing chemicals we need."

The condensate from the laundry passes first through a flash separation vessel. Steam leaves the top of the vessel and passes through a plate heat exchanger, where it heats the feed water and condenses. Meanwhile, the condensate from the bottom of the flash vessel passes through a second plate heat exchanger, where it also heats the feed water. The heated feed water only enters the boiler once it has been through both exchangers. The original condensate and the condensed flash steam are then recombined before returning to the hot well.

Spirax Sarco engineered systems are supplied skid-mounted and pre-commissioned, which enables straightforward specification, easy installation and they only use a small amount of floor space.

Published in Valve User Magazine Issue 6

Summer 2020 // Issue 53
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