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

State-of-the-Art Review of Fluid Catalytic Cracking (FCC) Catalyst Regeneration Intensification Technologies

Fluid catalytic cracking (FCC) is the workhorse of modern crude oil refinery. Its regenerator plays a critical role in optimizing the overall profitability by efficiently restoring the catalyst activity and enhancing the heat balance in the riser reactor. Improvement in the device metallurgy and process operations have enabled industrial regenerators to operate at high temperatures with a better coke burning rate and longer operating cycle. Today, the carbon content of regenerated catalyst has drastically reduced to less than 0.1 wt.%. However, the unit is still plagued with operational complexities and insufficient understanding of the underlying dynamic, multiscale intricacies. Recent process-intensification strategies provide insights into regenerator performance improvement potentials. In this review, the importance of the uniform distribution of spent catalysts through structural modification and operational manipulations of the catalyst distributor is discussed. The knowledge of the role of baffles in enhancing excellent gas–solid interaction has been increasing, but skepticism due to its complex hydrodynamic effects on gas–solid flows fends off operators from its application, a critical evaluation of its implication in the regenerators is covered. The understanding of the contribution of air/steam distributor design and feed gas injection techniques for even contact with spent catalyst leading to the improvement in FCC performance is also investigated. The reliability of FCC components is equally a big concern, as unplanned shutdown and enormous economic losses are being witnessed due to device failure. To this end, mitigation approaches to damaging afterburn and high-temperature erosion problems with respect to process control and geometric adjustment in the bed, freeboard, cyclone separators and collection ducts are explored. Emission limits for fluid catalytic cracking unit (FCCU) and products are consistently ratcheting downward; the commingled turnkey solutions to reducing pollutants generation are also reviewed.

A review on modeling and control of olefin polymerization in fluidized-bed reactors

This is a detailed review on olefin polymerization models, and the most recent process control approaches used to control these nonlinear systems are presented. Great focus has been given to the various approaches of fluidized-bed reactor (FBR) modeling. Currently, there has yet to be a single model that blends these modeling aspects together into one single formulation. In this article, the classification of models works by looking at their assumption in considering the phases inside the system. Researchers have been unraveling vast information to narrate in detail the relations between various variables that can be found in FBRs. Although it is not difficult to understand about the basics of modeling polymer properties, a gap exists for future researchers to justify in detail the phenomena and reduce the gap between model predictions and the actual data. The various controlling approaches to control these FBRs have also been reviewed and categorized depending on the method they used to control significant parameters of this nonlinear system. The progress that can be expected in this field leads to the creation of more efficient reactors and minimizing waste.