This paper focuses on the effects of exothermic reactions during torrefaction, a mild heat treatment process in the temperature range 200 to 300 °C. Three different scales are considered, the micro‐particle (powder scale), the macro‐particle (woodchips or larger) and the thick fixed bed (pilot reactor) together with three wood types, spruce, beech and locust. At the powder scale, TGA‐DSC tests indicate that exothermic reactions are noticeable principally during the first stages of torrefaction. The mass loss kinetics are used to evaluate parameters for a DAEM (Distributed Activation Energy Method) model. At the macro‐particle scale, temperature measurements within wood planks heated in an oven depict the presence of temperature overshoots due to the exothermic reactions that lead to unevenly treated particles. At the reactor scale, a large fixed bed of wood chips is heated in the same oven by an up‐flowing recirculated mixture of inert gas and volatiles. The exothermic reactions are found to generate a heat wave that propagates up the bed. Total mass losses are found to largely exceed those predicted with the DAEM model based on recorded bed temperatures. This means that, in order to reach the measured mass yields, the inner core temperatures of the wood chips must be higher than those of their outer surface and of the gas flow. Multi‐scale modelling approaches are therefore required to take into account the combined exothemicity and diffusional limitations within the wood chips and at their exchange surfaces.

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Soot formation during partial oxidation is a major issue for hydrogen production from liquid hydrocarbon fuels. Measurements were made to investigate the sooting behavior of diesel fuel under variation of the main operating parameters temperature (T = 800 to 1300°C), pressure (p = 1 to 3 bar), equivalence ratio (U =1 to 3), and steam ratio (H 2 O/C = 0.2 to 0.6) at constant residence time. The experimental setup was a perfectly stirred/plug flow reactor (PSR/PFR system) providing conditions close to reality. The study proves that soot growth rate strongly depends on temperature, pressure, and equivalence ratio while adding water has a minor effect on soot growth. Experimental results were compared with a kinetic model developed by the Institut Français du Pétrole (IFP), predicting soot formation during the partial oxidation of liquid hydrocarbon fuels. The calculated amount of soot shows good agreement with the measured data.

The explosion behaviour of CH,/air mixtures inside a closed 0.065 m3 spherical and a 1 m3 cylindrical vessel was investigated to determine the effect of turbulence on the structure and propagation rate of transient turbulent flames for different initial turbulence levels generated by 4 ventilators installed inside the equipment. Laser-Doppler and hot wire anemometry were used to measure the turbulent motion. It was found that fairly uniform turbulence could be achieved in the central zones of the vessels and that the RMS-values of flow velocity were proportional to the ventilator speed. The evaluation of burning velocity from the pressureltime records showed that, starting from an initial burning velocity which depends on the initial turbulence level, the flame accelerates as a result of pressure, temperature and turbulence effects. Maximum burning velocity coincides with the inflexion point of the pressureltime curve, and is followed by a rapid deceleration of the flame front. A linear relationship between burning velocity and measured RMS-velocity is recognized in the observed range of RMS-values.