CONSTRUCTIVE AND ENGINEERING SOLUTIONS FOR A TOP-COMBUSTION SOLID-FUEL BOILER FOR LOCAL HEATING SYSTEMS

The paper considers constructive and engineering solutions for a top-combustion solid-fuel boiler intended for use in local heating systems. The operating principle of long-burning candle-type boilers is analysed, and their main structural features are generalised. Based on this analysis, a solid-fuel boiler design is proposed that is focused on simplified manufacturing, the use of readily available materials, and minimisation of the number of structural elements and welded joints. A schematic representation of the boiler operating principle is presented, the main structural components are described, and the principal stages of manufacturing are outlined. The proposed design incorporates an upper air supply system with a movable distributor positioned above the fuel layer. This arrangement is intended to provide controlled air supply to the active combustion zone as the fuel charge is gradually consumed. An internal screen separates the zone of gaseous product formation from the main heat-exchange volume and creates conditions for combustion of gaseous products of thermal decomposition. Tubular heat-exchange elements are arranged in the flow path of hot combustion products to facilitate heat transfer to the heat carrier. A preliminary assessment of the energy potential of the proposed boiler is performed based on the lower heating value and mass of the firewood charge. The obtained relationships connect the fuel load, its energy potential, and the expected operating duration at a single fuel load. The calculated estimates are considered preliminary, since the actual useful heat output, thermal efficiency, fuel consumption rate, flue gas temperature, and other heat-balance parameters require experimental determination. The proposed design may represent a technically feasible alternative to commercially manufactured long-burning boilers for local heating systems, subject to further experimental validation of its thermal performance and operating characteristics.