WORLD PULP&PAPER 103 Unlike in wood powder firing, bark can be used as a biomass source in gasification. paper mill in Sweden utilises pellets as a wood powder source. “Our lime kiln was 50 years old and had seen better days. To match our Figure 3. Fredrik Lind and Charles Brooks-Wind inspecting the lime kiln at SCA Munksund mill. Figure 4. SCA’s Munksund paper mill in Sweden utilises pellets as a wood powder source. strategy of being fossil fuel free, we decided to build a new kiln utilising biofuel. The new kiln was ready and in operation in January 2015. At first, we had major problems with ring formation and variations of fuel flow. After many hours of trouble shooting and process improvements, we have now taken a huge step toward the goal we set from the outset: a fossil-free kiln with great operational effectiveness and a low impact on the environment,” says Fredrik Lind, Production Engineer at the SCA Munksund mill. UTILISING BARK IN BIOMASS GASIFICATION Unlike in wood powder firing, bark can be used as a biomass source in gasification. Biomass gasification is a combined system of biomass dryer, gasifier and lime kiln, optimised for burning the product gas. After drying, bark or other wood residue is gasified in the CFB gasifier at high temperatures using a controlled amount of air. The resulting product gas is then burned in the lime kiln burner, which is optimised for product gas. “One of the challenges is controlling the whole process. Bark is not a uniform