Management of digestate

HRS Heat Exchangers Limited, a heat transfer specialist for the process industry, has signed a €1.3 million contract with Scottish and Southern Energy (SSE) to deliver a Scraped Surface Vacuum Evaporator, for their Barkip anaerobic digestion plant in North Ayrshire. The HRS self-cleaning evaporator system overcomes the fouling issues associated with the evaporation of organic digestate.

The Barkip plant will be the first of its kind to incorporate a novel digestate processing stage: Waste heat from the CHP engines is used to concentrate the liquid fraction of the digestate into a nutrient rich liquid fertilizer. Under the terms of the contract, the HRS technology will enable the Barkip Anaerobic Digestion plant to process 75,000 tonne’s of waste annually, in a plant setup that produces around 2.5MW of renewable electricity which will contribute towards Scotland’s renewable energy industry.

At the heart of this technology is HRS’ Unicus Dynamic Scraped Surface Heat Exchanger that ensures that any high organic load in contact with hot surfaces does not lead to fouling. This patented technology provides a continuous cleaning to the walls of the HRS evaporator. For many environmental applications, standard evaporation technologies are not ideal and do not achieve the desired optimum thermal and waste recycling performance. The HRS evaporator can work continuously with very little maintenance, at times for more than 6 months. The project was co-developed by Zebec Biogas, which has the specialist enzyme and biological process expertise.

“The evaporator from HRS was chosen not just for its operational performance, but because the quality of the team behind the product is excellent." When we made enquires about the product and its suitability we were immediately offered the opportunity to see this type of equipment in operation to access the suitability for ourselves, not at the factory but by being able to speak to a current operator at their own premises. As a customer that level of confidence in a product with a proven track record is vitally important. SSE looks forward to becoming the latest of HRS’s satisfied customers”, said Pat Howe Project Manager Barkip Anaerobic Digester Plant.

“HRS is proud to associate itself with such a pioneering project. Our self-cleaning evaporator system has the unique capacity to overcome fouling issues in a digestion plant. We're proud to operate in a sector where innovation can save energy, reduce waste, and CO2, and improve final product quality without harming the environment. At HRS, we strive to have a positive impact on our environment, and for our customers, and in turn their customers”, said Steven Pither, Managing Director, HRS Heat Exchangers Limited.