Investment in steam recovery system cuts energy costs by 10%

09/09/2005

A Spirax Sarco flash steam recovery system is delivering direct energy savings of 10% plus a further 10% in indirect savings at PDM Group’s site at Nuneaton. The system has also dramatically cut visible plumes of steam from the site.

The Nuneaton plant uses around 25 tonnes per hour of steam to dry and sterilise animal by-products. Before the new system was installed, the flash steam from the returning drier condensate was vented to atmosphere. The company decided to recover this wasted energy as part of a group-wide policy to save energy and reduce visible emissions.

Spirax Sarco was called in and working with the PDM team, designed built and delivered a complete packaged flash steam recovery system.
Now, condensate and flash steam is fed from the dryers to the flash recovery vessel, which separates them into two streams. Each stream then flows through its own dedicated plate heat exchanger, which transfers the energy in the flash steam or condensate to the boiler feedwater. This raises the temperature of the pressurised feedwater to around 130degC, rather than the 90degC typically achieved before flash steam recovery was introduced.

There are five boilers on the site, of which three were running prior to the Waste Heat Recovery Unit installation. By raising the feedwater temperature and therefore the system efficiency has allowed for one of the boilers to be taken off line. “The boilers work closer to their optimal firing capacity, saving an extra 10% on top of the 10% saved directly by waste heat recovery,” explains PDM Group’s Operations Director Mr Rob Ratcliffe.

The flash vessel, heat exchangers and associated equipment were all supplied as a skid-mounted, engineered system. With all the major assembly work carried out at Spirax Sarco’s Cheltenham facility, the complete recovery system was integrated with the Nuneaton site’s existing plant over a normal weekend shutdown. “The modular approach was helpful for the installation and the Spirax Sarco team has been very supportive,” says Mr Ratcliffe.

The Nuneaton plant is one of six animal by-product processing plants around the country operated by PDM Group. According to Mr Ratcliffe, the success of the steam recovery system at Nuneaton is likely to be followed by a number of similar installations throughout the group.

For further information on Spirax Sarco visit www.spiraxsarco.com/uk

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