Search

The main objective of this work was to experimentally and numerically investigate the Liu Shu River oil shale drying by the means of flue gas in a fluidized bed dryer. Several experiments were performed under different temperatures conditions. The moisture content of oil shale was measured during the experiments. The two-stage drying model was incorporated in computational fluid dynamics (CFD) package FLUENT via user-defined functions (UDF) and utilized for simulation of heat and mass transfer of oil shale drying in the fluidized bed dryer. The simulation results for solid moisture content agreed well with experimental data. The effects of the temperature and velocity of flue gas, initial bed height, and the particle size on the drying characteristics were predicted and analyzed. It is shown that the gas temperature and velocity are the important parameters in the whole drying process. The particle size has more obvious influence in the falling drying period than the constant drying period. The temperatures of gas and solid phases were monitored. It is shown that the so-called “near gas distributor zone” is the most effective heat transfer zone, which agrees well with the calculated value. The system quickly reached thermal equilibrium, characterizing a nearly isothermal bed. The developed model provides a very good demonstration to describe the oil shale drying in the fluidized bed dryer, and may provide important information for design, optimization of operation conditions. [ABSTRACT FROM PUBLISHER]

Magnesium hydroxide precipitate was prepared using magnesium chloride and urea as starting materials via a homogenous precipitation method. Before it was calcined to obtain magnesium oxide nanoparticles, the precipitate was pretreated and dried using different pretreatments and drying methods. The as-prepared magnesium oxide nanoparticles were characterized by transmission electron microscope and X-ray diffraction. The results show that when drying methods (except for supercritical CO2 extraction drying) are the same, grain diameters and agglomeration of magnesium oxide nanoparticles exhibit a similar trend and depend on pretreatment. The agglomeration of magnesium oxide nanoparticles is relevant with drying methods when pretreatments are same. The agglomeration of magnesium hydroxide particles is mostly induced by capillary pressure or surface tension. [ABSTRACT FROM AUTHOR]

Production of nanomaterials is becoming increasingly important as a result of diverse industrial applications. Nanomaterials can be prepared by a dry process or a wet process; the latter involves drying, which affects the quality of the products. This article presents an overview of recent research and development activities in drying of nanomaterials. Current drying methods for such applications are classified and compared with the help of some examples. Selection criteria for drying methods as well as future research requirements are suggested. [ABSTRACT FROM AUTHOR]