Zorana Arsenijević

Drying of Slurries in Fluidized Bed of Inert Particles

Abstract A fluid bed dryer with inert particles was used for drying of slurries. Experiments were performed in a cylindrical column 215 mm in diameter and 1200 mm in height with glass spheres as inert particles. Slurries of Zineb fungicide, copper hydroxide, calcium carbonate, and pure water were used as the feed material. The effects of operating conditions on dryer throughput and product quality were investigated. Main performance criteria, i.e., specific water evaporation rate, specific heat consumption, and specific air consumption, were quantified. Temperature profile along the bed was mapped, and nearly isothermal conditions were found due to thorough mixing of the particles. The material hold-up and residence time were determined. Simple heat and mass balances predict the dryer performance quite well.

Removal of volatile organic compounds from activated carbon by thermal desorption and catalytic combustion

The thermal desorption of saturated activated carbon discharged from an industrial adsorber and catalytic oxidation of desorbed products over a Pt/Al2O3 catalyst were investigated. The activated carbon is almost completely regenerated by flushing with air at 200°C for 30 min. Desorbed products are fully oxidized over the Pt/Al2O3 catalyst above 275°C.

Experimental investigation of heat transfer in three phase fluidized bed cooling column

In this study, a three-phase (gas-liquid-solid) fluidized bed was used to study the heat transfer characteristics of the system. The system consisted of low density (290 kg/m3) spherical particles of the diameter of 2 cm in 0.25 m cylindrical column with the countercurrent flow of water and air. The experimental investigation and mathematical modeling of heat transfer between the hot air and the cooling water was carried out. The experiments were conducted for the variety of different fluid flow rates and inlet air temperatures, while the air flow rate was kept constant. Based on the obtained experimental results a new correlation for heat transfer in three-phase fluidized system was proposed. The mean percentage error between the experimental and the correlated values of the jHp obtained was 1.69%. The hydrodynamic parameters of the system were also calculated according to the available literature correlations. [Projekat Ministarstva nauke Republike Srbije, br. ON172022]

Prevention and control of dimethylamine vapors emission: Herbicide production plant

The widely used herbicide, dimethylamine salt of 2,4-dichlorophenoxy acetic acid (2,4-D-DMA), is usually prepared by mixing a dimethylamine (DMA) aqueous solution with a solid 2,4-dichlorophenoxy acetic acid (2,4-D). The vapors of the both, reactants and products, are potentially hazardous for the environment. The contribution of DMA vapors in overall pollution from this process is most significant, concerning vapor pressures data of these pollutants. Therefore, the control of the air pollution in the manufacture and handling of methylamines is very important. Within this paper, the optimal air pollution control system in preparation of 2,4-D-DMA was developed for the pesticides manufacturing industry. This study employed the simple pollution prevention concept to reduce the emission of DMA vapors at the source. The investigations were performed on the pilot plant scale. To reduce the emission of DMA vapors, the effluent gases from the herbicide preparation zone were passed through the packed bed scrubber (water scrubbing medium), and the catalytic reactor in sequence. The end result is a substantially improved air quality in the working area, as well as in the urbanized areas located near the chemical plant.