Thermogravimetric analyses (TGA) were conducted in order to analyze the pyrolysis behaviors of coal and FB. The coal and biomass particles were size classified, using a sieve shaker.

The combustion air (80-90% of required air) is supplied to the boiler burner by a secondary air blower; it is then preheated to 100-200°C, before it enters the boiler through a swirl burner nozzle. A commercial volumetric feeding is used . Primary air transports the fuel suspension into the quarl of the boiler burner. Dual water jets catch particulates and ash, and quench the furnace gases. The entire facility is operated from a central control panel. The diagnostic system consisted of an orifice plate for measuring the secondary airflow and sheathed "type K" and "type S" thermocouples, rotometer to measure the primary airflow rate and emission measurements Lancom and ENERAC systems.

Funding Sources

1. Department of Energy, Pittsburgh, University Coal Research, "Development of all-solid-state sensors for Measurement of Nitric Oxide and Ammonia concentrations by Optical Absorption in Particle-laden Combustion Exhaust Streams," Annamalai with Luct and Caton
2. Department of Energy, Pittsburgh, "Cofiring Coal:Feedlot and Litter Biomass (CFB and CLB) Fuels in Pulverized Fuel and Fixed Bed Burners," 6/15/2000 to 12/31/2002
3. Texas Advanced Technology Program, 2000-2002, "Co-firing Coal:Biowaste (poultry waste) Blends in a Boiler burner,"
4. Energy Resources Program ,Office of Vice President -Texas A&M 1999-2001, "Combustion and Emission studies on coal:manure blend, Energy Resources Program , Annamalai
5. Department of Energy Biomass Programs , 1999-2001, utilization and disposal of animal waste as coal:manure blend for boiler burners, Western DOE Biomass Programs, Annamalai and Sweeten
6. EXCEL Energy (Utilities at Amarillo):Gift funds, 1997-2000
7. Texas Cattle Feeders Association : Gift Funds, 1997-2000

Modeling- Cofiring

PCGC2 stands for Pulverized Coal Gasification and Combustion Code - Two Dimensional. This code employs the mixture fraction - equilibrium chemistry approach to solve axisymmetric combustion and gasification of coal/coal slurry/oil/gas in a swirl burner. The code consists of many submodels. The comprehensive PCGC2 model/code for pulverized fuel combustion is significantly modified by using three mixture fractions to track primary air, CLB fuel offgas, and vaporized moisture, respectively. Gas-solid phase coupling is handled by PSI-Cell (Particle Source In Cell) method.

A drying model for fuel particles is incorporated into the model/code. Four major char combustion reactions are considered. Turbulence mean distributions and emissions of 15 gaseous species (H2, N2, O2, CH4, H2O, H2S, CO, CO2, NH3, HCN, NO, P4O10, PO2, SO2, and SO3) are calculated and a fairly good agreement with experimental data is achieved. Parametric study is carried out to determine effects of excess air, swirl number and fuel moisture content on combustion behavior and pollutant emissions. The following physical and chemical modules are used in the current modified PCGC2 model:
For more details, please refer to our recent paper Sami et al (1999) and PhD theses of Wei .

The original code was developed at the Brigham Young University in Utah.

The original code was developed at the Brigham Young University in Utah under a joint effort by the BYU and the University of Utah.

Results (2-mixture vs 3-mixture)
Temperature contours in the near burner region
Coal-only case with new reactor dimensions
Grid-size = 40 x 40 (This is the maximum grid we can use in the original code)
Due to coarser grid, the contour plot is not as sharp as the three-mixture code are.

The second plot is based on three-mixture code with 50:50 coal:coal blend
MF used: 25, 50,65,80,100 miccrons
0.119,0.139,0.109,0.069,0.059, !pmf(ips),ips = 1,5
0.119,0.139,0.109,0.069,0.059, !pmf(ips),ips = 6,10

This is from 90:10 coal:coal with BYU input data.
NOTE: Mass fractions used are 0.36,0.225,0.135,0.09,0.09, !pmf(ips),ips = 1,5
0.04,0.025,0.015,0.01,0.01, !pmf(ips),ips = 1,5