Near Zero CO₂ Emissions in Coal Firing with Oxy‐Fuel Circulating Fluidized Bed Boiler

Abstract

Carbon capture and storage is a concept to reduce greenhouse gas emissions of energy production from fossil fuels. In oxy-fuel combustion, the fuel is burned in a mixture of oxygen and recycled flue gas. This generates CO 2 -rich flue gas from which the CO 2 is easily separated and compressed. Foster Wheeler Power Group is developing the existing design tools and process models of air-fired circulating fluidized bed boilers to implement specific features of oxycombustion. The validation data is produced from bench-scale and pilot-scale experiments at the VTT, Technical Research Centre of Finland. A three-dimensional circulating fluidized bed (CFB) furnace model is developed and applied by Lappeenranta University of Technology for predicting the effects of oxycombustion in full scale units. This paper presents concept studies and initial 3D modeling results based on a 460 MW e supercritical CFB power plant at Lagisza, and pilot-scale studies with flue gas recirculation demonstrating real oxygen combustion conditions.

Sulfur fate during bituminous coal combustion in an oxy-fired circulating fluidized bed combustor

“…In air atmosphere, CaO and CaSO 4 are the main forms of calcium, which indicates that CaCO 3 decomposes into CaO first and then part of CaO reacts with SO 2 to form CaSO 4 . The calcium conversion to CaSO 4 is about 30%, which is close to the results in the references [15,16]. In O 2 /CO 2 atmosphere, CaO, CaCO 3 and CaSO 4 are all main forms in the ash.…”

“…Lawrence [14] found even without lime injection the SO 2 emissions were dramatically decreased with oxy-CFB combustion. VTT's pilot experiment showed that the desulfurization efficiency of limestone during oxy-CFB combustion can reach 98% [15], much higher than that in air combustion. Jia et al [16] observed that the sulfur capture was lower in oxy-CFB combustor at 850 o C than air-fired, ranging from 65% to 78.2%.…”

“…Lawrence et al [14] studied the oxy-coal combustion in a small-scale CFB and found the CO 2 concentration in the flue gas was more than 85% (dry basis). Foster Wheeler and VTT are developing the near zero emissions oxy-CFB boiler and have done the bench and pilot experiments at VTT [15]. CANMET has carried the oxy-CFB experiment with full flue gas recycled [16].…”

Calcium-based sorbents behaviour during sulphation at oxy-fuel fluidised bed combustion conditions

“…One is a 20 MW th PC boiler and the other is a circulating fluidised bed (CFB) combustor of 15 MW th operating in air-mode and 30 MW th operating in oxy-mode. It is believed that an oxy-fuel CFB combustor will be an important candidate for new coal fired power plants [6][7][8] mainly because the circulation of solids in the combustor can help to an effective control of the temperature.…”

Integration of a Ca looping system for CO2 capture in existing power plants

“…Any future improvements in their energy consumption will also improve the efficiencies claimed in this work. In particular, it should be highlighted that the Ca looping system described in this article will benefit the fast development that is expected for oxy-CFB technology, 26 which is an enabling technology for the Ca looping process described in this work.…”