Experimental Investigation Of Caso₄ For Chemical-looping Combustion

It is widely accepted today that CO₂ emissions escalate the greenhouse effect and hence contribute to a higher average temperature on earth.There is an urgent need for developing new techniques for CO₂ capture to control the greenhouse gas with less energy loss.Chemical-looping combustion(CLC)is completely different from the traditional one,CO₂ capture takes place during combustion without energy penalty and with no need of special CO₂ separation equipment,By using this process,NOx formation can be eliminated, without the use of NOx technologies.CLC involves the use of a metal oxide as an oxygen carrier that transfers oxygen from the air to the fuel,avoiding direct contact between fuel and air.Comparing with metal oxides,calcium sulfate has proven to be a kind of new oxygen carrier with sufficient reactivities in reduction and oxidation reactions,with enough ability for carrying oxygen and no secondary pollution.In this paper,fixed-bed reactor is used to determine the reaction performance of calcium sulfate.In this study,the cyclic test of a CaSO₄-based oxygen carrier in alternating reducing simulated carbon monoxide and methane and oxidizing conditions was performed at 950°C in a fixed bed reactor at atmospheric pressure.The release of SO₂ during the cyclic test was found to be responsible for the decrease of reactivity of a CaSO₄ oxygen carrier by analyzing the chemical mechanism of off-gas.X-ray diffraction analysis revealed that the presence of Carbon Deposition during the cyclic test of a CaSO₄ in methane/Air.Surface morphology analysis demonstrates that the natural anhydrite particle surface varied from impervious to porous after the cyclic test.There isn't any sintering between different oxygen carriers.