Abstract
The co-firing of biomass and waste in power generation systems offers a means to utilise renewable CO2 neutral fuels. The potential affects of firing coal with <20 wt % of biomass material has been assessed with corrosion tests on five materials: 1 Cr steel, 2.25 Cr steel, X20CrMoV121, AISI 347H and alloy 625. Test conditions were targeted at superheater and evaporator conditions, with gas and deposit compositions selected on the basis of plant experience and potential fuel compositions. Laboratory corrosion tests were carried out using the ‘deposit recoat’ technique in controlled atmosphere furnaces for 1000 hour periods. The performance of the material in these tests was determined from dimensional metrology before and after their exposure. These data have been used to derive empirically based corrosion models of the materials corrosion performance under these test conditions. The corrosion data/models obtained from this programme of work has been compared to that available from operating power plants fired on coal, straw or wood fuels. This indicates that the levels of damage anticipated for dilute mixes of biomass in coal are similar to the ranges of damage observed for coal or wood firing alone.
