Results of experimental and numerical investigations of wood chips drying are described in the paper. Experiments are carried out on two test facilities: a small laboratory rig and a larger pre-prototype dryer. Both facilities are thorough-circulation convective air dryers. The first one is a batch dryer, whereas the second one is a continuous dryer with wood chips flowing down by gravity from a charging hopper to a gutter with the aid of screw-conveyor. The latter is considered a half scale model (preprototype) for professional drying installations. A low feeding rate of wood chips into the pre-prototype dryer makes the process quasi-stationary and the difference between it and a batch drying is negligible. So, most experiments at this facility were carried out as batch dryers with non-agitated packed beds. The investigations exhibit the same linear correlation between the mass of evaporated water from the packed bed and the drying air velocity for both facilities. Numerical analysis of the drying process is conducted using the Ansys Fluent software enriched in drying capabilities by means of self-written procedures – user defined functions. Simulations confirmed a phenomenon of a drying front observed in the small laboratory rig. A thin layer of wood chips comprises the whole heat exchange and moisture evaporation phenomenon. The drying front travels downstream in the course of the process separating the already dried layer and still wet layer.

The objective of this research was to evaluate the adsorption capacity of the shell biomass ( Dioscorea rotundata), taking into account the impact of temperature, bed height, and particle size on the removal of nickel(II) ions in aqueous solution in a continuous fixed-bed column system; performing the modelling of the break curve. The biomass was characterised by SEM-EDS analysis. The analysis found that it represents a rough, heterogeneous structure, rich in carbon and oxygen, with mesopores, and is suitable for removing heavy metals. It also determined the optimum parameters of the bed height, particle size, and temperature, keeping the pH and the initial concentration of the solution constant. The results revealed that the bed height and the particle size are the two most influential variables in the process. Ni(II) removal efficiencies range between 85.8 and 98.43%. It was found that the optimal conditions to maximise the efficiency of the process are temperature of 70°C, 1.22 mm particle size, and 124 mm bed height. The break curve was evaluated by fitting the experimental data to the Thomas, Adams–Bohart, Dose–Response, and Yoon– Nelson models, with the Dose–Response model showing the best affinity with a coefficient of determination R2 of 0.9996. The results obtained in this research showed that yam shell could be suggested as an alternative for use in the removal of Ni(II) ions present in an aqueous solution in a continuous system.

Process intensification is one of the key branches of process engineering. High gravity equipment achieves intensification by substituting gravity with much higher centrifugal force. Rotating Packed Bed is the leading example of high gravity solutions, strongly facilitating gas-liquid mass transfer. However, cylindrical packings come with certain drawbacks, such as dry spots, that can be overcome with new solutions, such as baffle-based packing geometries. However, when baffles are arranged too close to each other, liquid bridges are formed between them, which may lead to decrease in mass transfer efficiency. This work is concerned with improvement of a Zickzack-like internal by the means of visual studies with the use of high-speed camera. According to measured ligament break-up length, two new packings were designed for particular rotational speeds and tested experimentally for effective mass transfer area and wet pressure drop.

It is known that external diffusional resistances are significant in immobilized enzyme packed-bed reactors, especially at large scales. Thus, the external mass transfer effects were analyzed for hydrogen peroxide decomposition by immobilized Terminox Ultra catalase in a packed-bed bioreactor. For this purpose the apparent reaction rate constants, kP, were determined by conducting experimental works at different superficial velocities, U, and temperatures. To develop an external mass transfer model the correlation between the Colburn factor, JD, and the Reynolds number, Re, of the type JD = K Re(n-1) was assessed and related to the mass transfer coefficient, kmL. The values of K and n were calculated from the dependence (am kp-1 - kR-1) vs. Re-1 making use of the intrinsic reaction rate constants, kR, determined before. Based on statistical analysis it was found that the mass transfer correlation JD = 0.972 Re-0.368 predicts experimental data accurately. The proposed model would be useful for the design and optimization of industrial-scale reactors.

The principle of work of many metallurgical shaft furnaces is based on the flow of reaction gas through the descending packed bed composed of metallurgical materials. Hot gases flow up the shaft furnace through the column of materials, give their heat to the descending charge materials. At the same time due to their reducing nature they interact chemically, causing the reduction of oxides inside the charge. In real conditions, during the course of the process, the powder is generated, the source of which is the batch materials or it is introduced into the as part of the process procedure. The powder in the form of thin slurry is carried by the stream of flowing gas. Such multiphase flow might considerably affect the permeability of the charge due to the local holdup of powder. The holdup of solid phase in packed beds of metallurgical shaft furnaces leads to radial changes in bed porosity. Radial changes in bed porosity uneven gas flow along the radius of the reactor and negatively affect the course and efficiency of the process. The article describes the model studies on radial distribution of carbon powder holdup in the packed bed composed of metallurgical materials. The powder was divided into fractions – “static” and “dynamic”. Large diversity of carbon powder distribution was observed in the function of the radius of reactor in relation to the bed type, apparent velocity of gas carrying powder and the level of bed height.

Simplified optimization method using the MATLAB function fminbnd was adopted to determine the optimal feed temperature (OFT) for an isothermal packed-bed reactor (PBR) performing hydrogen peroxide decomposition (HPD) by immobilized Terminox Ultra catalase (TUC). The feed temperature was determined to maximize (minimize) the average reactant conversion (reactant concentration) over a fixed period time at the reactor outlet. The optimization was based on material balance and rate equation for enzyme action and decay and considered the effect of mass-transfer limitations on the system behavior. In order to highlight the relevance and applicability of the work reported here, the case of optimality under isothermal operating conditions is considered and the practical example is worked out. Optimisation method under consideration shows that inappropriate selection of the feed temperature may lead to a decrease in the bioreactor productivity.