The course and effects of syngas production from beechwood and RDF in updraft reactor in the light of experimental tests and numerical calculations

The article presents results and characteristics of the solid fuel gasification process in an updraft reactor, as well as describes main physicochemical phenomena. The experimental part includes multivariant gasification tests of beechwood and refuse derived fuel (RDF), as well as their mixtures. The result of these tests was the composition of gasification products, including tars, and temperature distributions in the reactor in different operating conditions. The experiments showed that syngas from beechwood gasification had higher LHV (5.3 MJ/Nm3) than the RDF syngas, the LHV of which was equal to 4.5 MJ/Nm3. Moreover, syngas obtained from RDF contains smaller amounts of heavy tars (31 g/Nm3) than that obtained from beechwood (82 g/Nm3). Since the gasification phenomenon is extremely complex, due to solid phase-gas interactions, an additional goal of the research was explaining key effects of the gasification phenomenon using a relatively simple mathematical model. Essential elements of gasification modelling, which are additionally difficult to determine, are solid fuel characteristics within the full temperature range. The article suggests determining density and specific heat based on properties of unprocessed fuel and char, and on the fuel conversion degree. The calculated results have revealed high temperature and velocity differences between the two phases.