Chemical Engineering Research and Design最新文献

We experimentally studied the kinetics of methane hydrate formation from stirred aqueous NaCl solutions. The studies were carried out with pure water and aqueous solutions in which the mass fractions of NaCl were 0.2, 0.5, 1.5, 3.0, 5.0, and 7.0%. In all our kinetic experiments, there was the same initial mass of liquid water, a similar temperature, and a similar driving force for gas hydrate formation in terms of pressure. Under these conditions, the values of the rate of change in the mass of liquid water during the initial stage of methane hydrate formation from stirred aqueous NaCl solutions were determined. It has been found that if the mass fraction of NaCl in an aqueous solution is less than 1.0%, then methane hydrate is formed more rapidly from this solution compared to pure water, and if the mass fraction of NaCl in an aqueous solution is greater than 1.0%, then methane hydrate is formed more slowly from this solution compared to pure water. It has also been found that the presence of NaCl in an aqueous solution has little effect on the kinetics of methane hydrate formation from this solution. Additionally, we experimentally determined the phase equilibrium points for methane hydrate in the pure water–methane and 3.0 wt% NaCl solution–methane systems.

An electrostatic precipitator (ESP), which filters the fine particles present in the exhaust gas generated from a power plant, has a better particle-collection efficiency when there exists a uniform flow in the dust collection chamber. However, most former investigations examined the flow distribution via numerical approaches that modeled the perforated plates within the inlet diffuser as porous media, which have not been adequately validated. Therefore, the aim of this study was to examine the performance of the porous media model for simulating the flow through perforated plates of an ESP diffuser by numerical simulation and experiment. Simulation results using the porous media model were compared with those obtained with a fully resolved mesh precisely describing the complete geometry of the entire perforated plate. The results obtained with both these methods were consistent with experimental results obtained upstream of the inlet diffuser, but the porous media model could not accurately simulate the flow distribution across the perforated plates. Overall, this model failed to predict the deflection of incoming flow on the solid bars and the wakes behind the bars, and could not reflect the vena contracta phenomenon occurring within the holes of the plate. As a result, the simulated flow distribution at the entrance of the main dust-collection chamber differed from that observed in the experiment, which resulted in poor prediction of the flow field inside the chamber. Therefore, this porous media model requires further improvement for wide-scale adoption in industrial practical applications, e.g., ESP for flue gas treatment in power plants.

Despite being a technology of several decades, high pressure homogenization (HPH) remains widely used in food and pharmaceutical industries, often as an essential unit operation in liquid product processing. Continual advances in the technology are made on multiple fronts, on equipment innovations by the manufacturers, new applications by users, and advances in process understanding by multidisciplinary scientists alongside subject matter experts amongst industry practitioners. While HPH is comparatively simple conceptually, the homogenization process involves complex engineering physics which is influenced by the varied processing conditions and highly diverse inputs with each use-case requiring its own treatment. The successful application of a HPH process indubitably requires practitioners to draw upon insights from multiple domains and the optimization for each case. Thus, this timely review aims to outline the more recent trends and advancements in HPH process understanding and novel applications involving HPH from both academic and industrial perspectives.