Abstract The experimental characterization of sorbents for Calcium Looping (Ca-L) processes is generally accomplished by thermogravimetric analysis or by using single fluidized bed bench scale reactors. These methods may present limitations, the most significant being the poor ability to reproduce the thermal history that sorbent particles experience in a real Ca-L plant. This limitation may severely affect the correct evaluation of the sorbent behavior in terms of CO 2 capture capacity and attrition. In this study, a purposely developed experimental apparatus is applied for Ca-based sorbent testing under conditions that simulate a realistic thermal history of the sorbent. The apparatus consists of two identical lab-scale bubbling beds (Twin Beds - TB) operated batchwise as the calciner and the carbonator, respectively. The reactors are connected to each other via a rapid solids pneumatic transfer line, designed so as to enable rapid and selective transfer of the sorbent from one reactor to the other at the end of each calcination/carbonation stage. The two beds consist mostly of coarse-grained silica sand, acting as a thermal ballast, to which sorbent samples to be characterized are added. The TB apparatus has been used to investigate the effect of the thermal history on the performance of two limestones, in terms of CO 2 capture capacity and attrition tendency, upon multiple calcination/carbonation cycles under the typical operating conditions of the Ca-L process. The results have been compared with those obtained for the same sorbents carried out in a single lab-scale fluidized bed reactor (SB) and under the same operating conditions. The comparison showed that the CO 2 capture capacity in the TB system is larger than that found in SB tests for both sorbents. On the contrary, the absence of strong thermal shocks in the TB experiments leads in general to a decrease of the attrition tendency, with a reversal in terms of generated fines between calcination and carbonation stages. Indeed, the generation rate of fines measured in the TB tests during carbonation is smaller than that measured in the corresponding calcination stage, which is opposite to what was found during the tests in the SB device. These findings indicate that the sorbent thermal history plays a non-negligible role on its CO 2 capture performance in Ca-L.

中文翻译：

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用新型双床反应器表征钙循环吸附剂

摘要 用于钙循环 (Ca-L) 工艺的吸附剂的实验表征通常通过热重分析或使用单流化床台式反应器来完成。这些方法可能存在局限性，最重要的是重现吸附剂颗粒在真实 Ca-L 设备中经历的热历史的能力较差。这种限制可能会严重影响在 CO 2 捕获能力和磨损方面对吸附剂行为的正确评估。在这项研究中，特意开发的实验装置用于在模拟吸附剂真实热历史的条件下进行 Ca 基吸附剂测试。该设备由两个相同的实验室规模鼓泡床（双床 - TB）组成，分别作为煅烧炉和碳酸化器分批操作。反应器通过快速固体气动传输管线相互连接，该管线设计为能够在每个煅烧/碳酸化阶段结束时将吸附剂从一个反应器快速和选择性地传输到另一个反应器。这两个床主要由粗粒硅砂组成，用作热镇流器，其中添加了要表征的吸附剂样品。TB 装置已被用于研究在 Ca-L 工艺的典型操作条件下多次煅烧/碳酸化循环后，热历史对两种石灰石性能的影响，包括 CO 2 捕获能力和磨损趋势。已将结果与在单个实验室规模的流化床反应器 (SB) 和相同操作条件下使用相同吸附剂获得的结果进行了比较。比较表明，TB 系统中的 CO 2 捕获能力大于两种吸附剂在 SB 测试中发现的能力。相反，在 TB 实验中没有强烈的热冲击通常会导致磨损趋势的降低，在煅烧和碳酸化阶段之间产生的细粉发生逆转。事实上，在碳化过程中 TB 测试中测得的细粉生成率小于相应煅烧阶段中测得的细粉生成率，这与 SB 装置中的测试过程中发现的结果相反。这些发现表明，吸附剂的热历史对其在 Ca-L 中的 CO 2 捕获性能起着不可忽视的作用。TB 实验中没有强烈的热冲击通常会导致磨损趋势的降低，在煅烧和碳酸化阶段之间产生的细粉发生逆转。事实上，在碳化过程中 TB 测试中测得的细粉生成率小于相应煅烧阶段中测得的细粉生成率，这与 SB 装置中的测试过程中发现的结果相反。这些发现表明，吸附剂的热历史对其在 Ca-L 中的 CO 2 捕获性能起着不可忽视的作用。TB 实验中没有强烈的热冲击通常会导致磨损趋势的降低，在煅烧和碳酸化阶段之间产生的细粉发生逆转。事实上，在碳化过程中 TB 测试中测得的细粉生成率小于相应煅烧阶段中测得的细粉生成率，这与 SB 装置中的测试过程中发现的结果相反。这些发现表明，吸附剂的热历史对其在 Ca-L 中的 CO 2 捕获性能起着不可忽视的作用。在碳化过程中，TB 测试中测得的细粉生成率小于相应煅烧阶段中测得的细粉生成率，这与 SB 装置测试中发现的结果相反。这些发现表明，吸附剂的热历史对其在 Ca-L 中的 CO 2 捕获性能起着不可忽视的作用。在碳化过程中，TB 测试中测得的细粉生成率小于相应煅烧阶段中测得的细粉生成率，这与 SB 装置测试中发现的结果相反。这些发现表明，吸附剂的热历史对其在 Ca-L 中的 CO 2 捕获性能起着不可忽视的作用。