Reduction of CaSO4 oxygen carrier with coal in chemical-looping combustion: Effects of temperature and gasification intermediate

Abstract Chemical-looping combustion (CLC) has been suggested as an energy efficient method for the capture of carbon dioxide from combustion. Thermodynamics and kinetics of CaSO 4 reduction with coal via gasification intermediate in a CLC process were discussed in the paper, with respect to the CO 2 generating efficiency, the environmental factor and the surface morphology of oxygen carrier. Tests on the combined process of coal gasification and CaSO 4 reduction with coal syngas were conducted in a batch fluidized bed reactor at different reaction temperatures and with different gasification intermediates. The products were characterized by gas chromatograph, gas analyzers and scanning electron microscope. And the results showed that an increase in the reaction temperature aggravated the SO 2 emission. The CO 2 generating efficiency also increased with the temperature, but it decreased when the temperature exceeded 950 °C due to the sintering of oxygen carrier particles. The use of CO 2 as gasification intermediate in the fuel reactor had a positive effect on the sintering-resistant of oxygen carrier particles. However, increasing the steam/CO 2 ratio in gasification intermediate evidently enhanced CO 2 generating efficiency and reduced SO 2 environmental impact.

[1]  T. Wheelock,et al.  Reductive decomposition of calcium sulfate with carbon monoxide: reaction mechanism , 1990 .

[2]  Wei-Ping Pan,et al.  Investigation of Chemical Looping Combustion by Solid Fuels. 2. Redox Reaction Kinetics and Product Characterization with Coal, Biomass, and Solid Waste as Solid Fuels and CuO as an Oxygen Carrier , 2006 .

[3]  Anders Lyngfelt,et al.  Design and Operation of a 10 kWth Chemical-Looping Combustor for Solid Fuels - Testing with South African Coal , 2008 .

[4]  Jun Xiao,et al.  Experiments on chemical looping combustion of coal with a NiO based oxygen carrier , 2009 .

[5]  Edward J. Anthony,et al.  Sulfation phenomena in fluidized bed combustion systems , 2001 .

[6]  Stuart A. Scott,et al.  In situ gasification of a solid fuel and CO2 separation using chemical looping , 2006 .

[7]  A. Lyngfelt,et al.  A fluidized-bed combustion process with inherent CO2 separation; Application of chemical-looping combustion , 2001 .

[8]  Anders Lyngfelt,et al.  Sulphur capture in fluidized bed boilers: the effect of reductive decomposition of CaSO4 , 1989 .

[9]  Jun Xiao,et al.  Effect of Temperature on Reduction of CaSO4 Oxygen Carrier in Chemical-Looping Combustion of Simulated Coal Gas in a Fluidized Bed Reactor , 2008 .

[10]  K. Qiu,et al.  CaS Oxidation by Reaction with CO2 and H2O , 2003 .

[11]  Anders Lyngfelt,et al.  The use of petroleum coke as fuel in chemical-looping combustion , 2007 .

[12]  E. Anthony.  Solid looping cycles: A new technology for coal conversion , 2008 .

[13]  Jun Xiao,et al.  Use of coal as fuel for chemical-looping combustion with Ni-based oxygen carrier , 2008 .

[14]  Edward J. Anthony,et al.  Clean combustion of solid fuels , 2008 .

[15]  A. Hayhurst,et al.  On the formation of liquid melts of CaS and CaSO4 and their importance in the absorption of SO2 by CaO , 1996 .

[16]  W. Prins,et al.  The reductive decomposition of calcium sulphate I. Kinetics of the apparent solid-solid reaction , 1993 .

[17]  Mohammad. M. Hossain,et al.  Reactivity and stability of Ni/Al2O3 oxygen carrier for chemical-looping combustion (CLC) , 2008 .

[18]  A. Lyngfelt,et al.  Reaction between Sulfur Dioxide and Limestone under Periodically Changing Oxidizing and Reducing ConditionsEffect of Cycle Time , 1998 .

[19]  Jun Xiao,et al.  Chemical-looping combustion of methane with CaSO4 oxygen carrier in a fixed bed reactor , 2008 .

[20]  A. Lyngfelt,et al.  A 300 W laboratory reactor system for chemical-looping combustion with particle circulation , 2006 .

[21]  Jun Xiao,et al.  A mechanistic investigation of a calcium-based oxygen carrier for chemical looping combustion , 2008 .

[22]  I. Barin,et al.  Thermochemical properties of inorganic substances , 1973 .

[23]  Anders Lyngfelt,et al.  The use of petroleum coke as fuel in a 10 kWth chemical-looping combustor , 2008 .

[24]  Anders Lyngfelt,et al.  CHEMICAL-LOOPING COMBUSTION - STATUS OF DEVELOPMENT , 2008 .

[25]  Olav Bolland,et al.  A novel methodology for comparing CO2 capture options for natural gas-fired combined cycle plants , 2003 .

[26]  Jun Xiao,et al.  Multicycle Study on Chemical-Looping Combustion of Simulated Coal Gas with a CaSO4 Oxygen Carrier in a Fluidized Bed Reactor , 2008 .

[27]  Jean-Xavier Morin,et al.  An ALSTOM Vision of Future CFB Technology Based Power Plant Concepts , 2005 .

[28]  Wei-Ping Pan,et al.  Investigation of chemical looping combustion by solid fuels. 1. Process analysis , 2006 .

[29]  Anders Lyngfelt,et al.  Chemical-looping combustion in a 300 W continuously operating reactor system using a manganese-based oxygen carrier , 2006 .

[30]  M. Uddin,et al.  Role of water vapor in oxidative decomposition of calcium sulfide , 2003 .

[31]  Mohammad. M. Hossain,et al.  Chemical-looping combustion (CLC) for inherent CO2 separations—a review , 2008 .

[32]  P. Hansen,et al.  High-temperature reaction between sulphur dioxide and limestone. V: The effect of periodically changing oxidizing and reducing conditions , 1993 .

[33]  Anders Lyngfelt,et al.  Solid fuels in chemical-looping combustion , 2008 .