Salisbury hospital’s steam trap success

Against this backdrop, Salisbury District Hospital has implemented a concerted energy-saving programme, key elements of which include replacing existing bucket steam traps with higher performing, lower maintenance, and more effective GEM venturi steam traps from Thermal Energy International (TEI), installing a new gas CHP engine, and looking into fitting a TEI condensate economiser system. HEJ editor Jonathan Baillie reports.

Against a backdrop of a significant redevelopment and expansion that has taken place at the Salisbury District Hospital in recent years – see panel – “History and recent developments” – the estates and facilities team at Salisbury NHS Foundation Trust has been acutely aware of the need, despite the challenge of achieving this at a time when a variety of new equipment has come on stream, to reduce energy use and cut the hospital’s overall carbon footprint in line with both NHS and broader environmental targets. One of the key ways via which the team, led by general manager, estates technical services George Atkinson, is already doing this, is via the installation, undertaken between late 2009 and April 2010, of new GEM venturi steam traps from Thermal Energy International (TEI). Around 70 such steam traps have replaced existing “traditional” mechanical steam traps, including “bucket”, “float”, and other thermodynamic valve-operated variants, on the steam distribution network that, for instance, links the hospital’s main boiler plant and laundry with its sterile services department some 400 metres away, as well as on equipment such as sterilisers in the SSD. The replacement GEM steam traps’ installation was undertaken by TEI’s technicians. Like many such large healthcare facilities, the Salisbury District Hospital currently uses steam widely both for its laundry operations and in its sizeable sterile services department. Many of the existing steam traps had suffered failures, principally due to malfunctioning of moving parts over time. According to TEI, leaks and other losses of steam from, for instance, failed mechanical steam traps, account for around 10% of the overall primary energy losses in a large acute hospital’s steam system (the company claims, also, that some 10% of these (typically) bucket, float, and other mechanically-based traps will fail in any given year). Other primary sources of steam loss (TEI says), meanwhile, include stack loss – accounting for 18%; boiler blowdown – 2%; inadequate insulation – 5%, and flash steam – 5%, while secondary losses from standing losses and pipe leakage lead to a further 5% loss of steam. TEI says: “Therefore, of the money spent by the NHS on producing steam each year, around 45% could be lost, when in fact up to 40% could be viably recovered.”

Traps’ function explained