Experimental parameters

TXL was used as the base case fuel. TXL and WYO were fired as blends with two DB fuels. Each coal was blended with each DB fuel in 100-0, 95-5, 90-10, and 80-20 blends on a mass basis. Note that on a heat basis, the percent of heat attributed to each fuel type was much less compared to percent mass basis. For example: for the 80:20 WYO:HA-PC-DB-SoilS fuel, 80% of the mass was WYO, but more than 94% of the heat came from WYO. All fuel and air flow rates were calculated from a program developed by Goughnour (2006). For each blended fuel, the equivalence ratio was varied from 0.8 to 1.2 in 0.1 increments. Combustion any leaner than

0. 8 created a heavy strain on the compressor and was also useless for industrial applications. The 80-20 blends were too rich in DB to be used in industrial applications, but were used in order to get more data points for the study. In the rich regime (equivalence ratio > 1.0) the HA-PC-DB-SoilS (Fig. 3.3b) quickly clogged the sampling port due to high ash content and may not be suitable for co-firing with coal; however it could be used as fuel for producing low heat value gases using gasifiers (see the section on gasification). The coal: biomass blends needed slightly more fuel flow rates compared to pure coal in order to compensate for the lower energy content of biomass for same thermal output.