The study of waste wood biomass as a biofuel in the context of boiler operational problems – slagging and high-temperature corrosion

This paper presents the melting characteristics of ash from different residual forest biomass - wood pellets, oak chips, coniferous bark, deciduous tree bark, wet sawdust and non-sorted blueberries. The melting temperatures of ash in reducing and oxidizing atmospheres were similar and did not differ by more than 10°C to 30°C. These values were within a range of 1230°C to 1330°C, and for the blueberry it was more than 1500°C. Only ash pellets melted in a reducing atmosphere at a temperature of 1280°C, and in an oxidizing temperature at 1430°C. To compare, determination tests were also performed for ash from “agro” biomass waste. Ash melting temperatures for biomass composites of agricultural origin (made in an oxidizing atmosphere), turned out to be lower than the temperatures of ash from wood biomass. In the results of the presented elemental analysis, the share of chlorine and sulphur and the impact S/Cl on high temperature corrosion processes were indicated. On the basis of the results for all the tested types of biomass, the calculated ratio S/Cl was below the value of 2.0. This means that the tested biofuels do not meet the safe use of biofuels detailed in the energy sector criterium (from the point of view of boiler operation).