Corrugated-tube heat exchangers cut costs at dairy AD plant

Dorset, UK – Renewable energy company Clearfleau has installed heat exchangers from HRS Heat Exchangers Ltd for its high-rate anaerobic digestion (AD) system at BV Dairy in Dorset.

The DTI-type model supplied by HRS is a double-tube heat exchanger, featuring a corrugated tube design to enhance turbulence and break the boundary layer at the tube wall.

The design improves the heat transfer to give a shorter thermal length to fit with the Clearfleau compact design solution. Increased turbulence also ensures that the heat exchanger can withstand the negative effects of fouling for longer periods.

The heat exchangers are heating the digester, which takes all the liquid feedstock from site and has helped BV Dairy to reduce its sewage treatment charges, energy costs, and carbon footprint. They units are also transferring residual heat from Clearfleau’s digestion process to the dairy.

BV Dairy officially opened its AD plant in July 2011. Clearfleau is the project partner that designed the system from extracting energy from liquid food processing residues. The plant will treat the waste materials on-site thus reducing sewer disposal costs, while generating renewable energy for use in dairy.

“Clearfleau’s AD technology can deliver at least a 95% reduction in the COD load of liquid bio-effluents fed into the digester, making it more effective than a high-rate AD system,” said Derek Rodman, technical manager, Clearfleau.

“HRS’ heat exchanger applications have helped reduce the running cost of the plant discharging to the local sewage system thereby further contributing to the reduction in the carbon footprint of BV Dairy’s milk processing site,” he added.