Influence of fuel mixtures and biomass on efficiency and safety in combustion process

Combustion equipments use fuel mixtures with variable composition according to the availability of materials, in order to analyze the characteristics of this blends a group of cases were simulated using the Simci's Pro II® software, this simulation was used to find the correlation between process safety problems, combustion efficiency, equipments reliability and service life with the fuel composition. It follows that the modes of combustion failures are related with High Heating Value (HHV) and density of fuel. The impact of changes in the compositions blends over thermal consumption might be significant and may exceed the technical limits of flame specified in design standards for boilers and furnaces, situations that may conduce to the emergence of operational problems for the equipment. The main effects of the variation in 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 of 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 abnormality; they generate combustion inefficiencies, and negative impact on the integrity of equipment. © 2014, AIDIC Servizi S.r.l.