Lost Heat to be Recovered from Food Processing Industry’s Wastewater

The new heating pump recovering lost heat from wastewater has produced more than one kilowatt-hour of energy in a Pietarsaari-based food processing company during its first six months of operation.

Oy Scancool Ab is one of Finland’s leading suppliers of refrigeration facilities. Last year, Scancool provided Oy Snellman Ab with a system where heat exchangers delivered by Vahterus play an important role. The objective of the project is to produce savings of up to EUR 100,000 in energy costs and reduce the environmental load. The most important objectives – the amount of recovered energy, temperatures and efficiency – have been achieved ‘even better than anticipated’, says Jonny Asplund, Managing Director of Scancool. ‘The system delivered by Scancool recovers heat from the industrial plant’s wastewater and uses it to heat the required washing water. The heat pump reduces the consumption of heavy fuel oil by about 400 tonnes a year. Supplied water can be heated to 45–55 degrees, whereas we were only able to increase the temperature to about 20 degrees using the old system.’

Impure liquids and gases are commonplace in heat-recovery projects and variation in water quality turned out to be a challenge. Water at its dirtiest cannot always be processed sufficiently and purification causes breaks in the process. Asplund explains: ‘The central objective of this project was to find a solution that functions in water that is somewhat impure, regardless of filtering. We required a heat exchanger system that’s easy to wash and operates without excessive production breaks.’

The Vahterus solution was ideal for the customer. ‘We selected Vahterus heat exchangers because they can be washed and they endure demanding conditions required by these types of processes’, says Asplund. ‘It was important to find a heat exchanger supplier that can promise that particles of certain size will travel through the heat exchanger. It was also important that the heat exchanger can be opened easily and that it can be washed without opening using the back-flush principle. This can be performed more easily using Vahterus heat exchangers than traditional exchangers.’

Another challenge was created by temperature fluctuations in the plant’s wastewater and incoming pure water. According to Asplund, this problem was solved using automation technology, which helps to achieve optimal efficiency under all conditions.

Asplund believes that the successful collaboration with Vahterus will extend to future projects: ‘When lost heat is recovered from demanding targets, the requirements related to heat exchangers are fairly crucial. I believe that Vahterus can offer the most suitable solution for a number of situations.’