CALCIUM-OXIDE SINTERING IN ATMOSPHERES CONTAINING WATER AND CARBON-DIOXIDE
CALCIUM-OXIDE SINTERING IN ATMOSPHERES CONTAINING WATER AND CARBON-DIOXIDE
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DOI：
10.1021/ie00088a019
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发表时间：
1989-04-01
影响因子：
4.2
通讯作者：
BORGWARDT, RH
中科院分区：
文献类型：
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作者：
BORGWARDT, RH
使用通过CaCO 3和Ca（OH）2的快速分解制备的CaO，测量水蒸气和CO2对初生氧化钙的烧结速率的影响作为分压和温度的函数。每种气体都强烈地催化了烧结过程，并且它们的组合效应是相加的。由德国和Munir制定的模型，它描述了由一个单一的机制表面积减少，经验修改，以考虑气相的催化作用。尽管在CO2和/或H2O存在下多种烧结机制显然是可操作的，但经验模型在380-1150 ℃的温度范围内和39 Pa至15 kPa的分压下将等温表面积减少与时间相关。在烧结气氛中存在H2O或CO2也加速了孔隙率降低。在模拟烟道气的气氛中，孔隙率降低遵循theble对数律在烧结过程中在800，900，和1000 C的诱导期分别为6，4.5，和2.7秒，颗粒收缩的发病。考虑表面积影响的烧结模型与硫酸化模型的耦合允许通过Ca（OH）2注入来预测锅炉炉膛中的SO2捕获效率。为了使烟气脱硫的成本最小化并增加工业污染控制的选择范围，正在评估基于注入石灰石衍生吸附剂的几种工艺。这种方法似乎是最有效的一个应用到现有的工厂，因为它的改造相对容易。几种替代的吸收剂和注入模式正在试验中;这里感兴趣的一种是在高达1230 C的温度下注入到炉中，其中颗粒在短停留时间（约1000 ° C）内膨胀，CaO与SO2反应。2 s），然后温度冷却并停止反应。成功地将该过程应用于不同设计的锅炉，每个锅炉在不同的条件下运行，需要一个预测模型，该模型考虑了所涉及的速率过程。先前的工作已经表明，小CaCO 3颗粒的煅烧产生高初始表面积的新生CaO（Borgwardt，1985），并且当颗粒足够小以使孔扩散阻力最小化时，该CaO的SO2反应速率与其比表面积强烈相关（Borgwardt和布鲁斯，1986）。
The effects of water vaporand C02 on the sintering rate of nascent calcium oxide were measured as a function of partial pressure and temperature using CaO prepared by rapid decomposition of CaC03 and Ca (OH) 2. Each gas strongly catalyzed the sintering process, and their combined effects were additive. The model formulated by German and Munir, which describes surface area reduction by a single mechanism, is empirically modified to account for catalytic effects of the gas phase. Although multiple sintering mechanisms are apparently operative in the presence of C02 and/or H20, the empirical model correlates isothermal surface area reduction as a function of time over the temperature range 380-1150 C and partial pressures of 39 Pa to 15 kPa. Porosity reduction was also accelerated by the presence of H20 or C02 in the sintering atmosphere. In an atmosphere of simulated flue gas, porosity reduction followed theCoble logarithmic law during sintering at 800, 900, and 1000 C with induction periods of 6, 4.5, and 2.7 s, respectively, for the onset of particle shrinkage. A coupling of the sintering model with a sulfation model that accounts for the effects of surface area allows the prediction of S02 capture efficiencies in boiler furnaces by Ca (OH) 2 injection.In an effort to minimize the cost of flue gas desulfurization andincrease the range of options available to industry for pollution control, several processes based on the injection of limestone-derived sorbents are being evaluated. This approach appears to be the most effective one for application to existing plants because of its relative ease of retrofit. Several alternative sorbents andmodes of injection are under trial; the one of interest here is injection into thefurnace at temperatures up to 1230 C where the particles calcine and the CaO reacts with S02 during the short residence time (ca. 2 s) before the temperature cools and reaction ceases. Successful application of this process to boilers of varied design, each operating at different conditions, requires a predictive model that accounts for the rate processes involved. Prior work has shown that the calcination of small CaC03 particles produces a nascent CaO of high initial surface area (Borgwardt, 1985) and that the S02 reaction rate of this CaO is strongly related to its specific surface area (Borgwardt and Bruce, 1986) when the particles are sufficiently small to minimize pore dif-fusion resistance.