BIOMASS FUELS WORLD PULP&PAPER 104 Juhani Isaksson, Business Development Manager for Gasifiers at Valmet. Valmet has delivered four gasifier-lime kiln solutions for pulp mills. One of the first to be implemented is Metsä Group’s Äänekoski bioproduct mill. “Bark-derived product gas is produced for the bioproduct mill’s lime kiln. This is one example of solutions which enable the mill to be fully free of fossil fuels,” says Ilkka Poikolainen, Vice President of the Äänekoski bioproduct Mill, Metsä Fibre. “In these projects we have proven that lime kilns fueled with gasified biomass is safe and works well. We have achieved more than 100% of the design capacity, our customers have been able to operate with 100% gasifier gas, without support fuel and have reached good lime product quality of 2-4% CaCO3,” Isaksson concludes. CHOOSING THE BEST ALTERNATIVE The driver for choosing a biomass- based solution may be the company’s commitment to reducing CO2 emissions or the availability of suitable biomass as a byproduct of mill operations. In recent years, Valmet has delivered both gasification and wood powder solutions for new mills and rebuilds. “The best solution and the business case needs to be evaluated each time, based on the available biomass, kiln size and possible bottlenecks in the process. Gasification is the right solution for mills with a large or medium-sized kiln and which have bark at their disposal, while wood powder firing is most suitable for smaller kilns,” Jensen-Holm explains. It is also possible to convert existing fossil fuel kilns to use either wood powder or gasification, but it must be acknowledged that replacing the kiln fuel may impact kiln design and operation. In recent years, Valmet has delivered both gasification and wood powder solutions for new mills and rebuilds. Figure 5. Bark can be used as a biomass source in gasification Figure 6. Valmet has delivered four gasifier-lime kiln solutions for pulp mills. One of the first delivered is Metsä Group’s Äänekoski bioproduct mill. fuel, and it is important to understand how the process should be controlled and optimised. This is where Valmet’s complete understanding of the process from the dryer, gasifier and lime kiln operation comes into its own,” explains