Pollutant emissions in a bubbling fluidized bed combustor working in oxy-fuel operating conditions: Effect of flue gas recirculation

A review of oxy-fuel combustion in fluidized bed reactors

“…This section provides an overview of BFB technology together with research work performed, general observations and findings on oxy‐fuel in BFB units. Oxy‐combustion in BFB has mainly been applied at bench‐scale , with some exceptions at pilot‐scale .…”

“…And the sulfation reaction rate was also found to increase with reduced sorbent particle size and increasing SO 2 concentration. In 2013, they studied the pollutant emissions under oxy‐firing conditions with anthracite coal used as fuel and limestone for sulfur retention in the same unit as depicted in Figure – 3 kWth BFB furnace . This study showed that SO 2 recirculation increased the Ca‐based sorbent activity; however, it did not affect N 2 O emission, while most of the recycled NO was reduced to N 2 and N 2 O. Lastly, steam recirculation resulted in a sharp decrease in NO emissions, a minor increase in N 2 O emissions, and the CO concentration in the flue gas was not affected.…”

The combined effect of H2O and SO2 on the simultaneous calcination/sulfation reaction in CFBs

“…One of the main problems of the in situ desulfurization in CFBs is the low calcium utilization. Investigators have recommended many ways to improve the calcium utilization, for example, operating temperature optimization and limestone particle size optimization …”

Achievement of high CO2 concentration in the flue gas at slightly positive pressure during oxy-coal combustion in a 300kWth furnace

“…Laboratory-scale studies performed in universities and research facilities have been used to study the effects of oxy-fuel combustion characteristics. However, these laboratory-scale experiments [16][17][18][19][20][21][22][23] cannot properly simulate aspects such as the heat transfer phenomena for the radiative and convective section of the combustion chamber and the pollutant concentration in the flue gas, and thus cannot be used to determine how to efficiently treat these pollutants to generate a cleaner exhaust gas. Therefore, pilot-scale studies are more appropriate for a better understanding of the overall oxy-fuel combustion phenomena [23][24][25][26][27][28][29].…”

“…Garcia-Maraver et al [15] evaluated the relationship between the fuel quality and the gaseous and particulate matter emissions with five different types of pellets, and the results showed the PM emissions derived from these five types of pellets were dominated by particles with sizes below 2.5 lm, which are significantly affected by the fuel ash composition, namely by the amount of volatile inorganic elements K and Na. Diego et al [16] examined the effect of flue gas recirculation on pollutant emissions in a bubbling fluidized bed combustor at oxy-firing conditions. It was observed that the most important effect of CO 2 recirculation was the increase of the optimum temperature for SO 2 retention from 850°C (conventional air combustion) to 900-925°C.…”