Water distribution to the furnace wall tubes of a bagasse-fired boiler

This paper describes a mathematical model that solves for the distribution of flow in a boiler circuit consisting of downcomer pipes, the furnace wall header and furnace wall tubes. The driving force for circulation is the density difference caused by generation of steam in the tubes, which depends on the flow rate through each tube and the heat flux supplied to each tube. The model predicts the flow in the downcomer pipes and steam tubes and the amount of steam generated in each tube. The model is applied to analyse the distribution of flow in the front wall of a large bagasse-fired boiler that has shown the initial indications of circulation failure (tube misalignment and distortion). Various scenarios studied show how the supply pipe work design affects the distribution of water to each tube in the furnace wall. Additionally, the influence of the heat flux distribution on the flow distribution in the tube bank is examined.