WPI Refiner Heat

Energy for Industry recently commissioned a heat recovery project at its partner site, Winstone Pulp International (WPI). WPI is a Meridian Energy large industrial customer.

The project arose out of an energy efficiency improvement programme undertaken jointly by WPI and EFI. Agreed in April 2008 the project was fast-tracked in order to utilise heat at the mill. In WPI’s pulping process, wood chips are mechanically ground to pulp in electrically driven refiners. Moisture in the wood chip is vaporised and discharged from the refiners as steam. The heat recovery project takes this steam, scrubs it to remove any wood fibre and then sends the steam to a new set of heat exchangers. These exchangers heat ambient air up to around 90 degrees, providing 5MW of recovered heat.

WPI require large amounts of hot air in order to dry pulp to a suitable level. Traditionally this hot air was provided by the combustion of LPG. The first stage of air heating is now provided by the new heat recovery system. EFI’s existing 12MW biofuels heat plant provides the next stage of heating, taking air from 90 up to 250 degrees. This plant is fuelled on bark, process wood residues and pulp sludge.

The result of the heat recovery project is LPG savings of around 2.5 million litres per year. This translates to a green house gas emission reduction of 4,000 tonnes CO_2e per year.

Paul Saunders, WPI Plant Manager speaks highly of the EFI as WPI’s energy efficiency partners and highlights efficiencies achieved through the partnership.

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