High temperature desulfurization using a new macroporous lime particle

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High temperature removal of H2S is a key technology for developing advanced power plants such as IGCC and the Topping-Cycle. The lime particle of about 1 mm in diameter is a candidate of adsorbents for the desulfurization, but only the outer surface of the particle can be utilized because the CaO particles has only micropores. The micropores are easily plugged when CaO is converted to CaS, preventing H_2S from penetrating into the interior of the particle. This drawback will be overcome if the lime particle with a large amount of macropore is prepared.From this viewpoint, we tried to prepare several macroporous CaC from lime or Ca(OH)_2-water slurry by the following methods : (a) the lime particles pulverized under 10um were pressed and sintered in steam for 10 min at 900 。C ; (b) mixture of Ca(OH) 2-water slurry and several organic acids were heated up to 900 。C ; (c) the lime particles pulverized under 10p.m were heated up to 900 。C with a small amount of CaCI_2. All the samples prepared were crushed and sieved to get CaO particles of 1mm in diameter. The CaO particles prepared had a large amount of macropore with around 0.8mum in pore diameter. Then, we performed desulfurization of H_2S and SO_2 using the macroporous CaO at 900 。C.The CaO particles prepared by methods (a) and (b) were converted to CaS completely within 20 min or so. The desulfurization rate was correlated well with the macropore volume in the CaO particle. Thus it was clarified that the proposed method was effective to prepare the macroporous CaO particle having high desulfurization performance.