Soda-based sorbents for HCl removal in the DSI system for agricultural biomass Co-combustion at an industrial scale

Abstract

One of the significant issues of agricultural biomass combustion is its higher chlorine content that can lead to exceeding the emission limits. Dry-sorbent-injection (DSI) systems based on acid-gas sorption enable efficient acid-gas removal, and there are several types of commercially available sorbent that can be used in this technology. This article focusses on evaluation of the performance of soda-based sorbents for the removal of chlorine from the flue gas from agricultural biomass co-combustion and demonstrates their advantages over commonly used hydrated lime sorbents. Analysing both the operational efficiency and the potential for optimization, this research contributes valuable information to the development of more sustainable and cleaner biomass combustion technologies. The article includes a comparison of soda-based sorbents and their use for the removal of chlorine from flue gas and compares with previous findings on hydrated lime sorbents. The samples were determined in detail in a laboratory. The core of the article is based on full-scale industrial testing on a commercial 140 t/h CFB heating plant boiler. In operational tests, soda-based sorbents achieved, under the same conditions, a higher HCl removal efficiency (90.93 vs. 84.66%) and a lower specific sorbent consumption (0.87 and 0.91 vs. 2.58 and 5.59 m3sorbent·tCl−1 for hydrated lime sorbents. The behaviour of the system during tests has also revealed further possibilities to reduce soda consumption by modifying the control system logic and dosing systems. The results have shown that soda-based sorbents are a promising alternative to commonly used hydrated lime sorbents.