Influence of Fuel Mixtures and Biomass on Efficiency and Safety in Combustion Process

Abstract

Combustion equipments use fuel mixtures with variable composition according to available products. In order to analyze the characteristics of these blends a set of particular cases were simulated using SimSci Pro II ® software. Simulation was applied to find the correlation between process safety problems, combustion efficiency, equipment reliability and service life as a function of fuel composition. It was evident that combustion mode failures are related with High Heating Value (HHV) and fuel density. The impact of changes in the composition mixtures over thermal consumption may be significant and may exceed the limits of specified flame conditions in design standards for boilers and furnaces. In turn, these situations may cause both operational problems and integrity issues for the equipment. The main effects of the variation of calorific value and Wobbe index in the furnaces are evident in the high temperatures of tubes surfaces. There is a direct relationship between the increasing of heating power and the increase of surface temperature at the tubes. This effect causes also overheating in equipments, specially on radiation area; likewise, these conditions affect the burner, which is not designed for these blends, and lead to inefficient combustion, increased gas emissions and higher cost for maintenance due to damage in the structure of the furnace and its associated systems. Different biomass and mixtures of natural and refinery gas used as fuel in furnaces and boilers were compared in scenarios of operational upset, all of them generating combustion inefficiencies, and negative impact on the integrity of equipment.