Sampling method for woody biomass particles conveyed by air in the fuel pipe of a pulverized coal firing boiler

Abstract

In Japan, a feed-in tariff was introduced to promote and expand the renewable energy ratio to 22-24% by FY 2030. Biomass is one of important renewable energy. Recently, several biomass projects for not only fluidized bed boilers, but also pulverized coal fired boilers, are being planned around the world to reduce CO2 emissions as the main reason. The required particle size of woody biomass for combustion in a pulverized coal fired boiler is around 1mm, while that of coal is several tens of m. Woody biomass particles grinded by a mill are sent to burners via a fuel pipe by air. It is important to measure the particle size distribution in order to understand combustibility and grindability. However, it was unknown whether the particle size distribution could be measured by the same sampling method for pulverized coal. We conducted sampling tests of woody biomass particles in a fuel pipe using the isokinetic sampling method. As a result, we observed that the flow of woody biomass particles in the pipe was significantly non-uniform to the influence of the upstream elbow. It is necessary for woody biomass to measure at a pitch of at least 45 in order to obtain the particle size distribution in a fuel pipe.

Keywords

• woody biomass
• particle size distribution
• isokinetic sampling method
• pulverized coal fired boiler
• biomass co-firing