In thermochemical biomass conversion processes, especially gasification, the tar content, and composition is a major subject. Because of the various processes examined at VUT, this work picks up the opportunity to compare the different tar amounts and its composition at different temperatures and process parameters. Gasification of biomass was carried out at the 100‐kW steam‐blown dual fluidized bed gasifier pilot plant III (800–870°C) and the 70‐kW air‐blown pressurized research unit (800–900°C; 1–5 bar) at VUT. Olivine is a catalyst for tar conversion; hence it was used as bed material in steam gasification and also in pressurized air gasification. For better understanding of tar formation during thermochemical conversion of biomass, the tar content and composition in the producer gas were analyzed with a gas chromatograph coupled with a mass spectrometer.Basic differences between the two thermochemical conversion processes occurred especially at higher temperatures or higher pressures. The tar composition was shifted to higher molecular tars such as polyaromatic hydrocarbons. Decreasing tar amounts were found at higher temperatures or higher pressures. Therefore, in future, an optimization of gasification processes should be easier to accomplish, which means lower tar content in the producer gas, which results in a better utilization of the biomass. © 2009 American Institute of Chemical Engineers Environ Prog, 2009

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This work investigates the application of static mixers (SMs) in precipitating environments as present in certain pharmaceutical processes, in which the undesired side effect of precipitation of the residual dissolved fraction leads to equipment fouling and process stability challenges. The tests were conducted using saturated suspensions mixed with an anti-solvent to challenge the system with a step change of solubility in the presence of seeds and SMs. Various equipment configurations such as co-axial vs perpendicular mixing, different equipment dimensions, plastic vs metal SM, or ultrasound (US) irradiation were investigated, and fouling probability and stability were analyzed for different precipitation rates by monitoring the pressure level. The process stability was highly influenced by the setup configuration. The most stable and satisfactory process was achieved by co-axial mixing of the fluids before the SM plus using US irradiation. With this setup a run time of 5 h was achieved, continuous processing beyond 5 h could be realized by parallel arrangement of SMs, in which the process is switched from one SM to another after a pressure threshold is triggered. Furthermore, the particle size in various feed and outlet suspensions was analyzed, and correlations between the amount of suspended particles and the particle growth were determined. The highest initial solids in the feed suspension (30 wt%) resulted in the smallest growth of the particles in the outlet suspension (d 50 increased by 17.7%) after anti-solvent addition.

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This work focuses on the comparison of two different thermal conversion processes with respect to different tar amounts and tar compositions at different temperatures and process parameters. Steam gasification experiments were carried out in a 100 kW dual fluidized bed steam gasifier at a temperature range of 700 to 870 °C with straw and wood. Pyrolysis experiments were conducted in a rotary kiln reactor at temperatures between 600 and 630 °C and straw as fuel. For better understanding of tar formation during thermo-chemical conversion of biomass, the tar content and composition in the product gas were analyzed with a gas chromatograph coupled with a mass spectrometer. The main observation was that at higher temperatures the tar composition is shifted to higher molecular tars such as polyaromatic hydrocarbons (PAH). Key tar components at lower temperatures (pyrolysis) are phenols. The tar content and composition in the product gas of steam gasification of straw and wood as well as the tar yields and composition of low temperature pyrolysis of straw are presented in the following work.

Continuous manufacturing of pharmaceuticals offers such benefits as production flexibility, reduced drug product costs, and improved product quality. Moving toward continuous manufacturing requires suitable small-scale equipment, either by development of new equipment or optimization of existing equipment. In primary manufacturing, particle properties are often altered during crystallization and have to be restored during subsequent processing. Drying a crystallized product is one of the most challenging steps, especially since attrition and agglomeration can occur. To that end, we investigated the drying behavior of a crystalline model compound with moisture levels of up to 10 wt % in a corotating twin-screw extruder. The feed mass flows on a piece of small-scale equipment used for pharmaceutical production varied between 0.5 and 2.0 kg/h. Experiments were conducted to evaluate the drying performance in various process settings. Because of a very narrow and consistent residence time distribution, extrusion drying has the potential for pharmaceutical compound drying. In our study, we successfully accomplished drying of a crystalline product with very little agglomeration and/or attrition in some process settings while preserving a crystal size similar to that of the raw material. The reduction in particle size occurred as a result of long residence times (low extruder screw speed) and a decrease in the residual moisture of the product. The aim of our work was to show the potential of extruder drying as a novel continuous manufacturing process for pharmaceuticals and to enable further process development.