Comparative technical and economic analysis of innovative methods for waste heat recovery from flue gases for boiler type BKZ 220-100Hristo Beloev, Iliya Iliev, Angel Terziev, Andrey Kibarin and Madina AliyarovaE3S Web Conf., 327 (2021) 01004DOI: https://doi.org/10.1051/e3sconf/202132701004