New design of a flame-tube steam generator basedon a hot water boiler burning agricultural waste

This paper studies the technical feasibility of a new steam generator based on a hot water boiler of 400 kWt built and operated at Enache Morărit - Husi, Romania with briquettes and pellets of agricultural biomass. The chosen design option was those of “fume tubes”, leading to a minimal size at the same thermal charge, and avoiding the slagging of the ash exhaust section due to the advanced cooling rate of the flame tubes. The combustion is controlled by the grate system, composed by cooled fixed bars alternating to mobile bars. The convective section of the steam generator provided with an ash deposits remover system allows an overall efficiency of about 90 %. The generated steam can be used to power a condensing or a cogeneration steam turbine, in order to meet the local needs of electricity and heat of the farmers. These steam generators can be coupled in parallel configuration, in order to satisfy the energy request of most agro-industrial facilities. According to our knowledge, it is the first attempt in order to transform a hot water boiler into a steam generator.