Materials issues in waste and biomass combustion plants: approaches for improved energy efficiency

Abstract

Efforts to improve the energy efficiency of waste incineration and biomass combustion plants continue to attract an increasing level of importance as the drive to improve energy efficiency and the security of energy supply continues to gather pace. All renewable sources of energy are important to help minimise the impact of climate change of processes feeding the ever rising worldwide demand for energy. Waste incineration and biomass combustion plants can make important contributions in both the short-to-medium and the long term. In the efforts to utilise these sources as efficiently as possible, a number of materials and process control issues are critical and gaseous and deposit corrosion are frequently limiting factors.This paper describes an integrated approach to the understanding of materials behaviour in waste and biomass boilers. The approach involves monitoring the combustion conditions on the grate of boilers in order to determine flue gas conditions that will have an impact on energy recovery as well as plant performance from the materials perspective. Plant monitoring was also carried out using a cooled process probe whose main purpose was to collect solids from the flue gases of a range of power plants. The deposits were then available for use in laboratory and pilot plant corrosion tests. An innovative process sensor instrument is described. From the materials side, the results of a comprehensive study involving the collection of thermodynamic and kinetic data relevant to boiler materials corrosion, and the building of a model enabling the prediction of corrosion behaviour have been described and used for materials selection. This integrated approach is started to enable more efficient materials studies to be carried out and in the same frame, improvements in plant process control to be achieved.