DESIGN FEATURES OF THE EXPERIMENTAL UNIT AND NUMERICAL STUDIES OF BIOMASS THERMOCHEMICAL PROCESSING PART 5 PYROLYSIS OF FINE BIOMASS PARTICLES IN AN UPWARD FLOW

• Datum: 2025
• Hauptverfasser: Rokhman , B., Kobzar , S., Chetveryk , H.
• Format: Artikel
• Sprache: Ukrainian
• Veröffentlicht: Institute of Renewable Energy National Academy of Sciences of Ukraine 2025
• Schlagworte: upward flow; biomass; Bagasse; pyrolysis; conductive; radiant; heat exchange; gas; temperature.
• Online Zugang: https://ve.org.ua/index.php/journal/article/view/540
• Назва журналу: Vidnovluvana energetika

A model of polydisperse ensemble of biomass particles pyrolysis in an upward high-temperature flow of pyrolysis gas is constructed. The model includes radiant and convective heat exchange of particles with the pyrolyzer wall and gas, heat exchange with the wall and pyrolysis gas, drag and gravity forces, kinetics of thermolysis reactions: three parallel reactions of decomposition of the active part of biomass into primary pyrolysis gas, tar and char and secondary reactions of tar transformation into light gas and char. Analytical expressions for gas velocity, phase temperatures, gas density and pressure are derived, which can be used at each step of integration of the system of equations describing the pyrolysis process in an upward gas-disperse flow. An iterative cycle designed to calculate the pressure drop of pyrolysis gas at each step of integration has been developed. Using the model, numerical studies of the pyrolysis process of three Bagasse particles fractions with diameters of 0,9 mm, 0,95 mm and 1 mm were carried out in a plant with a biomass throughput of 66 kg/h in the medium of recirculating dry pyrolysis gas in the amount of 164,6 kg/h. This provided detailed information on the design and physico-chemical process parameters required for the development of the design documentation of the pyrolyzer. Two pyrolyzer designs were considered: cylindrical with a diameter of 200 mm and a height of 5 m, and with an expanding cone: inlet diameter 200 mm, outlet diameter 340 mm. The expanding cone was made in order to increase the particles and gas residence time in the pyrolyzer required for complete tar cracking. This made it possible to reduce the height of the pyrolyzer by 2 m compared to the cylindrical design.