High temperature desulfurization using a new macroporous lime particle

高温脱除H_2S是发展IGCC、拔高循环等先进电厂的关键技术。直径约1 mm的石灰颗粒是一种候选的脱硫剂，但由于CaO颗粒只有微孔，因此只能利用颗粒的外表面。当CaO转化为CaS时，微孔很容易堵塞，阻止了H_2S渗入颗粒内部。从这个角度出发，我们尝试以石灰或氢氧化钙水浆为原料，通过以下方法制备了几种大孔钙基复合材料：(A)将粉碎在10um以下的石灰颗粒压制，在900℃的水蒸气中烧成10min。将Ca(OH)2-水浆和几种有机酸的混合物加热到900℃。将在晚上10点以下粉碎的石灰颗粒加热到900℃。C和少量CaCl2。所有制备的样品都经过粉碎和筛分，得到直径为1 mm的CaO颗粒。所制备的CaO颗粒具有大量的大孔，孔径约为0.8微米。然后，我们在900℃用大孔CaO进行了H_2S和SO_2的脱除。用方法(A)和(B)制备的CaO颗粒在20min左右完全转化为CaS。脱硫率与CaO颗粒中的大孔体积有很好的相关性。由此可见，该方法是制备具有高脱硫性能的大孔CaO颗粒的有效方法。

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.