Development of the Next Generation CaO-Sorbent for Sulfur- and Nitrogen-Compound Removal

开发用于去除硫和氮化合物的下一代 CaO 吸附剂

基本信息

批准号：
11218207
负责人：
SASAOKA Eiji
金额：
$ 19.2万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2002
项目状态：
已结题

项目摘要

Limestone and lime are very important materials as sorbents for S-and N-compound removal. However their porosities are usually low, and their capacity are low. To solute this problem, the clarifications of the reaction mechanisms and the clarification of the effect of pore size distribution on the reactivity are very important in addition to the development of a preparation method of a porous lime which porosityis suitable for the removal. We present new preparation methods of macro-porous CaO using acetic acid, water and a mixture of acetic acid and water. By using these methods, we could prepare the samples, which pore size distributions were different each other, from a natural lime. The effects of pore size distribution of the CaO- and CaCO_3- sorbent on the removal of SO_x using the serial samples were studied. It was concluded that if we can prepared a lime that has an adequate number of macropore, mesopore and micropore, and good serial connection of these different size pore to … More ensure the permeability of reactant(SO_2 and O_2) and prevent pore plugging during sulfation, the reactivity and utility of the lime will be drastically improved. From the results of study on the CaCO_3-sorbent, it was also suggested that if the macropores in the CaCO_3 sample are developed enough to SO_2 removal, the reactivity of the CaCO_3 sample is same as that of CaOWhen CaO is used for H_2S removal, CaS formed from the CaO-absorbent has to be converted to CaSO_4 before disposal because H_2S is released from the reaction between CaS and water. To find out a method for the perfect conversion of CaS to CaSO_4 and CaO, the basic characters of the oxidative decomposition of CaS were examined using reagent grade CaS in the presence of H_2O because hot combustion gas contained moisture is usually used for the decomposition of CaS. It was found that the presence of H_2O affected drastically to the conversion of CaS to CaO and SO_2 : H_2O directly reacted with CaS and formed H_2 reacted immediately with O_2.The mechanism of the simultaneous removal of SOx and NOx by slaked lime was clarified : A reaction scheme of this reaction was proposed : SO_2 reacted with H_2O and formed SO_3^<2->, then NO and NO_2 might participate the reaction in one step and the other hand, accelerated the conversion of SO_3^<2-> to SO_4^<2->. The main part of NO_2 was converted to nitrate salts in the presence of H_2O. SO_3^<2-> formed from the adsorption is supposed to be significant for the removal of NO, and the enhancement of NO to the SO_2 was ascribed to its catalytic effect in the oxidation of SO_3^<2-> to SO_4^<2->. Less

石灰石和石灰是非常重要的材料，作为S和N-复合去除的分类。但是它们的孔隙率通常很低，其容量较低。为了解决这个问题，除了开发出适合去除的多孔石灰的制备方法外，对反应机理的澄清以及孔径分布对反应性的影响非常重要。我们使用乙酸，水和乙酸和水的混合物提出了宏孔CAO的新制备方法。通过使用这些方法，我们可以准备样品，这些样品与天然石灰彼此不同。研究了使用串行样品的CAO-和CACO_3的孔径分布对去除SO_X的影响。得出的结论是，如果我们能够准备好具有足够数量的大孔，室管和微孔的石灰，并且这些不同尺寸的孔的良好连接到……更多的孔连接，以确保反应物（SO_2和O_2）的渗透性（SO_2和O_2）（SO_2和O_2），并防止在硫酸化过程中插入硫化时，将得到极大的改善，将得到极大的改善。 From the results of study on the CaCO_3-sorbent, it was also suggested that if the macropores in the CaCO_3 sample are developed enough to SO_2 removal, the reactivity of the CaCO_3 sample is same as that of CaO When CaO is used for H_2S removal, CaS formed from the CaO-absorbent has to be converted to CaSO_4 before disposal because H_2S is released from the reaction between CaS and 水。为了找出一种将CAS到CASO_4和CAO完美转化的方法，在H_2O的存在下，使用试剂级CAS检查了CAS的氧化分解的基本特征，因为通常将水分含有水分的水分用于CAS的分解。 It was found that the presence of H_2O affected drastically to the conversion of CaS to CaO and SO_2 : H_2O directly reacted with CaS and formed H_2 reacted immediately with O_2.The mechanism of the simple removal of SOx and NOx by slaked lime was clarified : A reaction scheme of this reaction was proposed : SO_2 reacted with H_2O and formed SO_3^<2->, then NO and NO_2 might participate the reaction一步一步，另一方面将SO_3^<2->转换为SO_4^<2->。在H_2O的存在下，NO_2的主要部分被转换为硝酸盐。从添加吸附形成的SO_3^<2->预计对于去除NO将很重要，并且在SO_3^<2-> so_4^<2->的氧化中，将NO的NO增强为SO_2的催化效应。较少的