Oxygen Carrier Aided Combustion (OCAC) is a novel combustion concept with the purpose to increase the overall efficiency in conventional circulating fluidized bed (CFB) boilers. By replacing the commonly used bed material with an oxygen carrier (OC), the conceptual idea is to utilize the fluid dynamics in a CFB and the inherent oxygen transport supported by the OC to increase the oxygen distribution within the furnace in time and space. The OCAC concept has been successfully validated and further reached long-term demonstration in full scale operation (75-MW th ). This work presents a first evaluation of how ilmenite particles are affected in regard to mechanical resistance during long-term exposure to OCAC conditions in Chalmers 12-MW th CFB-boiler. A sand and a rock ilmenite are evaluated with regard to their mechanical stability. For evaluation, samples of the fresh materials and samples collected during operation in the Chalmers boiler are investigated. The study shows that the two materials differ in how the mechanical degradation occurs with exposure time. The sand ilmenite form cavities which are held together by an ash layer before they are shattered into numerous pieces, whereas the rock ilmenite develops distinct cracks that cause splitting of the particles.

中文翻译：

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比较长期暴露在燃烧生物质 12 MW th CFB 锅炉中的沙子和岩石钛铁矿的结构发展

载氧体辅助燃烧 (OCAC) 是一种新颖的燃烧概念，旨在提高传统循环流化床 (CFB) 锅炉的整体效率。通过用氧载体 (OC) 代替常用的床层材料，其概念是利用 CFB 中的流体动力学和由 OC 支持的固有氧传输来增加炉内氧在时间和空间上的分布。OCAC 概念已成功验证并进一步在全规模运行（75 兆瓦日）中实现长期示范。这项工作首次评估了钛铁矿颗粒在 Chalmers 12-MW th CFB 锅炉中长期暴露于 OCAC 条件下对机械阻力的影响。评估砂子和岩石钛铁矿的机械稳定性。对于评估，对新鲜材料的样品和在查尔默斯锅炉运行期间收集的样品进行了调查。研究表明，这两种材料在机械退化如何随暴露时间发生方面有所不同。砂钛铁矿形成空腔，在它们被粉碎成许多碎片之前，这些空腔由灰层保持在一起，而岩石钛铁矿则形成明显的裂缝，导致颗粒分裂。