New heat exchanger improves hospital energy performance

Replacing four shell-and-tube heat exchangers with plate heat exchangers at Leighton Hospital in Crewe is expected to achieve energy savings of more than £5000 a year. The savings come mainly form improved control. Ken Hardy, estates manager at the hospital, says, ‘The new units are saving energy, because they have eliminated the frequent [temperature] overshoots we used to get.’ Efficiency has been improved by over 5%. There are two 3 MW plate heat exchangers, one running and one on standby. They use plant steam to heat water for space heating throughout the 700-bed hospital and were supplied pre-assembled in frame-mounted packages with ancilliary equipment such as steam traps. This modular approach saves time and reduces disruption on site during installation. The precise controllability of the new units enables the temperature of return water to be controlled to within ±0.5 K. Mr Hardy says, ‘The controllability is phenomenal, especially when you consider that we are using the same control system as we were before.’ The old shell-and-tube heat exchangers were starting to cause maintenance issues. They have to be stripped down every two years for an insurance inspection, with the frequency increasing if problems are found. The insurers would cover the tube bundle in one of the units for six months instead of the normal two years. Ken Hardy estimates that the entire cost of the project, including stripping out the old units and installing the new ones, will be repaid by energy savings alone within five years.

Related links:

• www.spiraxsarco.com