Tohid Nejad Ghaffar Borhani

QSPR prediction of the hydroxyl radical rate constant of water contaminants.

In advanced oxidation processes (AOPs), the aqueous hydroxyl radical (HO) acts as a strong oxidant to react with organic contaminants. The hydroxyl radical rate constant (kHO) is important for evaluating and modelling of the AOPs. In this study, quantitative structure-property relationship (QSPR) method is applied to model the hydroxyl radical rate constant for a diverse dataset of 457 water contaminants from 27 various chemical classes. The constricted binary particle swarm optimization and multiple-linear regression (BPSO-MLR) are used to obtain the best model with eight theoretical descriptors. An optimized feed forward neural network (FFNN) is developed to investigate the complex performance of the selected molecular parameters with kHO. Although the FFNN prediction results are more accurate than those obtained using BPSO-MLR, the application of the latter is much more convenient. Various internal and external validation techniques indicate that the obtained models could predict the logarithmic hydroxyl radical rate constants of a large number of water contaminants with less than 4% absolute relative error. Finally, the above-mentioned proposed models are compared to those reported earlier and the structural factors contributing to the AOP degradation efficiency are discussed.

Evaluation of hydrodynamic behavior of the perforated gas distributor of industrial gas phase polymerization reactor using CFD-PBM coupled model

Abstract A 2D computational fluid dynamics (Eulerian–Eulerian) multiphase flow model coupled with a population balance model (CFD-PBM) was implemented to investigate the fluidization structure in terms of entrance region in an industrial-scale gas phase fluidized bed reactor. The simulation results were compared with the industrial data, and good agreement was observed. Two cases including perforated distributor and complete sparger were applied to examine the flow structure through the bed. The parametric sensitivity analysis of time step, number of node, drag coefficient, and specularity coefficient was carried out. It was found that the results were more sensitive to the drag model. The results showed that the entrance configuration has significant effect on the flow structure. While the dead zones are created in both corners of the distributors, the perforated distributor generates more startup bubbles, heterogeneous flow field, and better gas–solid interaction above the entrance region due to jet formation.

Chapter 4.5 – Carbon Capture

CO2 is one of the main greenhouse gases that causes global warming, leading to a global detrimental impact on the environment, economy, and society as a whole. Carbon capture is regarded as an important and effective approach to reducing CO2 emissions. This chapter focuses on two major aspects of CO2 capture: carbon capture technologies and carbon capture for industrial applications. Three different carbon capture methods, including postcombustion, oxy-combustion, and precombustion, will be presented. The maturity, advantages, disadvantages, and economy of the three carbon capture methods will be compared. In addition, various industrial applications of carbon capture in different areas, such as cement and clinker production, the iron and steel industry, water desalination, oil refinery, and the gas-to-liquid process will be discussed. Finally, the chapter ends with an outlook into further developments in carbon capture.