Pressurized Combustion and Gasification

Sandia’s pressurized entrained flow reactor (PEFR, Figure 1) can characterize and quantify the combustion and gasification characteristics of solid fuels at elevated pressures. This electrically heated reactor system features a reactor tube that is 1.5 m in length and can operate at temperatures up to 1,650 K and pressures up to 20 atm. Particles and gases can be sampled at any position along the reactor tube and an optical pyrometer provides particle temperature measurements at five discrete positions along the reactor length.

 

Figure 1. Photograph (left) and schematic (right) of Sandia’s pressurized entrained flow reactor (PEFR) for investigating the pressurized combustion and gasification characteristics of solid fuels such as coal and biomass.

Current research is focused on measuring char combustion rates during pressurized oxy-fuel combustion and on quantifying the kinetics of CO2 and steam gasification of coal char. Pressurizing oxy-fuel combustion plants offers overall improved thermal efficiency while retaining the carbon-capture feature of conventional oxy-fuel combustion. However, properly designing new pressurized combustion burners and boilers requires accurate data on coal devolatilization and combustion rates under these conditions. Similarly, coal gasification offers an attractive route for carbon capture while producing synthetic fuels or power, but contemporary gasifier designs are based on scaling up smaller, historic gasifier designs without the benefit of computational fluid dynamics modeling and simulation because of uncertainties over gasification rate parameters. Accurate quantification of gasification rates requires a distinct understanding of the influence of reactor parameters (T and p, for example) on the coal devolatilization process and the char gasification process. Figure 2 shows photographs of char particles produced from a devolatilization experiment in the PEFR.

 

 

 

 

 

 

 

Figure 2. Scanning electron microscopy micrographs of char particles produced in the PEFR at 1,200 ˚C from a subbituminous coal (left) and high-volatile bituminous coal (right).

Contact: Chris Shaddix, (925) 294-3840, crshadd@sandia.gov