By Kevin Parker P ower boilers are commonly used in paper mills to burn industrial wood waste to generate process steam and electric power. As a result, unburned wood fuel may be blown out of the boiler, causing efficiency and emissions problems. Technicians had tried adjusting airflow and firing arrangements without success. An animated sequence of streamlines showing airflow provided engineers with a clear understanding of exactly what was happening inside the boiler, making it relatively easy to adjust operating conditions and solve the problem.
Computer simulations provide a clear picture of what is happening at any point within the boiler.
Wood waste and air are injected at several points on the sides of the boiler. About one-third of the wood is burned in suspension above the stoker grate, and what remains burns on the grate. Residual ash is dumped at the end of the grate into an ash pit, and combustion gases go out the top of the boiler. The problem in this application was that a considerable amount of unburned wood was being entrained by the gas and carried through the steam-generating banks. Technicians at the plant tried adjusting the boiler's operating parameters.