Détermination de l’efficacité énergétique d’installations automatiques de combustion de biomasse et comparaison de l’efficacité et des émissions atmosphériques à différents régimes de puissance

Determining the energy yield of automatic installations of biomass combustion and comparing the efficiency and atmospheric emissions at different engine speeds

Context

The energy yield is often, except for the costs, the only point of comparison between combustion installations, but there are many calculation methods of the yield which are of course not all comparable.

Objectives

The project’s objectives are :
- to find the best method to determine the yield ;
- to study the yield variations according to the power.

Description of tasks

The energy yields and atmospheric emissions (CO, CO2, NOx, CH4, SO2, dust and residual oxygen) of an automatic industrial boiler will be evaluated at different thermal output. The thermal output considered will be 100, 50, 30 and a value < 30 % of the nominal thermal output. The characteristics of a boiler (yield and emissions) are always measured at the nominal thermal output.
In real conditions, a boiler never works continually at nominal thermal output. Depending on the energy needs (working time, seasons, …), the boiler works at intermediary engine speed. This problem is wellknown by operators of the energy sector. We want to study the energy yield and the impact on the environment of combustion installations working at intermediary speeds. On/off cycles of the boiler go through the decrease in heat output, the stand by, then the second starting up of the fire. The quality of the emissions and the energy yield value have not yet been studied at industrial scale. This work will aim at having a better knowledge of the intermediate thermal output and to start research tracks about the improvements to be made, especially at environmental level.