The operation of dry processes for acid gas removal from flue gas in waste-to-energy plants based on the use of calcium hydroxide as a solid sorbent generates a solid waste stream containing fly ash, unreacted calcium hydroxide, and the products of its reaction with acid pollutants in the flue gas (HCl and SO₂). To date, the fate of the solid waste stream is to be put into a landfill in the absence of commercially viable recycling approaches. The present study investigates the potential of these residues as CO₂ sorbents in the calcium looping process. Samples collected in different waste-to-energy plants were tested over multiple carbonation–calcination cycles, comparing their performance to that of limestone. Although inferior, the CO₂ sorption capacity of the residues resulted in values comparable to that of limestone and that steadily increased for a significant number of cycles. This peculiar behavior was attributed to the presence of a chlorinated phase, which enhances the CO₂ uptake in the diffusion-controlled stage of carbonation by reducing the product layer resistance to CO₂ diffusion. No significant release of acid gases was observed at the characteristic temperatures of calcium looping carbonation.

中文翻译：

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反复碳酸化-煅烧循环中Ca基空气污染控制残渣的CO ₂吸收潜力

使用氢氧化钙作为固体吸附剂，在垃圾发电厂中进行干法去除烟气中酸性气体的过程会产生包含飞灰，未反应的氢氧化钙及其反应产物的固体废物流。烟气中的酸性污染物（HCl和SO ₂）。迄今为止，在没有商业可行的回收方法的情况下，固体废物流的命运将被放入垃圾填埋场。本研究调查了这些残留物在钙环化过程中作为CO ₂吸附剂的潜力。在多个碳酸化-煅烧循环中测试了在不同的垃圾发电厂中收集的样品，并将其性能与石灰石进行了比较。虽然劣质，但CO ₂残留物的吸附容量可得到与石灰石相当的值，并且在许多循环中稳定增加。这种特殊的行为归因于氯化相的存在，该氯化相通过降低产物层对CO ₂扩散的抵抗力而增强了碳酸扩散控制阶段的CO ₂吸收。在钙环碳酸化的特征温度下未观察到酸性气体的显着释放。