Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency

Garcia, Eduardo; Liu, Hao

Abstract

Co-firing coal and biomass has the potential to reduce GHG emissions. However, high levels of alkali and alkaline metals in biomass ash can bring additional issues to the operation of coal-fired boilers. This study investigates the effects of ilmenite as the bed material on CO and NOx emissions and combustion efficiency of a coal and biomass blend, and the agglomeration tendency of the bed material with a pilot-scale (30 kWth) bubbling fluidised bed combustor. The experiments were carried out at 900 °C using a bituminous coal blended with wheat straw pellets at 40 wt% as the fuel and silica sand as the baseline bed material. Samples of agglomerates collected from the combustor and cyclone ash were characterised by SEM-EDS, XRD, and XRF. The results revealed that ilmenite could reduce the level of excess air required to achieve complete combustion due to lower CO emissions and less efficiency loss compared to silica sand. However, ilmenite increased NOx emissions. Furthermore, the characterisation of the obtained agglomerates and cyclone ash showed that ilmenite could hinder the K-rich molten substance attachment to the bed material, leading to significantly smaller agglomerates and hence less tendency towards defluidisation in comparison to silica sand.

Citation

Garcia, E., & Liu, H. (2022). Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency. Energy, 239, Article 121913. https://doi.org/10.1016/j.energy.2021.121913

• Journal Article Type: Article
• Acceptance Date: Aug 25, 2021
• Online Publication Date: Sep 3, 2021
• Publication Date: Jan 15, 2022
• Deposit Date: Sep 23, 2021
• Publicly Available Date: Sep 4, 2022
• Journal: Energy
• Print ISSN: 0360-5442
• Electronic ISSN: 1873-6785
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 239
• Article Number: 121913
• DOI: https://doi.org/10.1016/j.energy.2021.121913
• Keywords: General Energy; Pollution; Mechanical Engineering; Building and Construction; Electrical and Electronic Engineering; Industrial and Manufacturing Engineering; Civil and Structural Engineering
• Public URL: https://nottingham-repository.worktribe.com/output/6297013
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0360544221021617?via%3Dihub
• Additional Information: This article is maintained by: Elsevier; Article Title: Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency; Journal Title: Energy; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.energy.2021.121913; Content Type: article; Copyright: © 2021 Elsevier Ltd. All rights reserved.