a b s t r a c tA 3D Computational Particle Fluid Dynamic (CPFD) model is validated against experimental measurements in a lab-scale cold flow model of a Circulating Fluidized Bed (CFB). The model prediction of pressure along the riser, downcomer and siphon as well as bed material circulation rates agree well with experimental measurements. Primary and secondary air feed positions were simulated by varying the positions along the height of the reactor to get optimum bed material circulation rate. The optimal ratio of the height of primary and secondary air feed positions to the total height of the riser are 0.125 and 0.375 respectively. The model is simulated for high-temperature conditions and for reacting flow including combustion reactions. At the high temperature and reaction conditions, the bed material circulation rate is decreased with the corresponding decrease in pressure drop throughout the CFB for the given air feed rate.

The reaction kinetics for carbonization of biogas slurry and the influence of diffusion for high-density feedstocks (pistachio shell) were investigated. The experiments were carried out with a 1.5 L batch reactor for hydrothermal carbonization at reaction temperatures of 190, 200, and 220 °C and a residence time of 0–160 min. The obtained hydrochar samples were dried and analyzed via scanning electron microscopy and a C, H, and O elemental analyzer. It was found that the average activation energy of the biogas slurry is 50.7 kJ/mol. In the case of the diffusion experiments, Thiele moduli of 1.21–1.61 were found, which indicates an influence on diffusion for the hydrothermal carbonization of pistachio shells.

This paper deals with marine plastic debris and its collection and recycling methods as one possible answer to the rising amount of plastic in marine environments. A novel approach is to use energy recovery, for example pyrolysis of marine plastic debris into high-energy products. Compared to other thermal processes, pyrolysis requires less technical effort and the end products can be stored or directly reused. In order to design such an onboard pyrolysis reactor, it is necessary to know more facts about the feedstock, especially the thermochemical behaviour and kinetic parameters. Therefore, a thermogravimetric analysis was carried out for three selected plastic sizes with a temperature range of 34-1000 °C. The results obtained from TGA showed the same curve shape for all samples: single stage degradation in the temperature region of 700-780 K with most of the total weight loss (95%). Small microplastics had an average activation energy of 320-325 kJ/mol.

The fluid-dynamic behavior of a circulating fluidized bed pilot plant for oxyfuel combustion was studied in a cold flow model, down-scaled using Glicksman's criteria. Pressures along the unit and the global circulation rate were used for characterization. The analysis of five operating parameters and their influence on the system was carried out; namely, total solids inventory and the air velocity of primary, secondary, loop seal and support fluidizations. The cold flow model study shows that the reactor design allows stable operation at a wide range of fluidization rates, with results that agree well with previous observations described in the literature.

Although numerous bioaerosol samplers for counting and identifying airborne microorganisms are available, the considerably high purchase and maintenance costs for the sampler often prevent broad monitoring campaigns for occupational or environmental surveillance of bioaerosols. We present here a newly developed simple adapter and filter system (TOP filter system) designed to collect bioaerosol particles from a defined air volume using conventional vacuum cleaners as air pumps. We characterized the physical properties of the system using air flow measurements and validated the biological performance. The culture-based detection capacities for airborne fungal species were compared to a standard impaction sampler (MAS-100 NT) under controlled conditions in a bioaerosol chamber (using Trichoderma spores as the test organism) as well as in the field. In the chamber, an overall equivalent detection capacity between all tested filters was recorded, although a significant underrepresentation of the TOP filter system for Trichoderma spores were seen in comparison to the MAS-100 NT. In a comparative field study (n = 345), the system showed similar biological sampling efficiencies compared to the MAS-100 NT impactor, only the diversity of identified fungal communities was slightly lower on the filters. Thus, the system is suitable for large-scale environmental sampling operations where many samples have to be taken in parallel at a given time at distant locations. This system would allow endeavors such as antibiotics resistance monitoring or hygiene surveys in agricultural or occupational settings.