Dr. Poupak Mehrani
Chemical and Biological Engineering Department
University of Ottawa
Fluidized beds including those of gas-phase are widely used in industry due to their excellent features including providing high degree of mixing, heat transfer, mass transfer, to just name a few. In this talk a brief summary of research presently carried out by my research team in the areas of polymerization and clean energy, where fluidized bed reactors are employed, will be presented. (i) In petrochemical industry fluidized bed reactors are adopted for gas-phase ethylene polymerization to produce polyethylene. However, in such processes electrostatic charges are generated, resulting in the adhesion of polyethylene and catalyst particles to the reactor wall. This in turn causes long shut down periods for reactor clean-up and significant economic losses. At the University of Ottawa, a comprehensive experimental program has been established to better understand this occurrence underlying mechanisms. A new online charge measurement technique has been developed that allows the quantification of the degree of fluidized bed fouling. This method has been implemented in a pilot-scale atmospheric and a high-pressure fluidization facility (built in-house). The later system enables the study under industrially-related operating conditions of polyethylene reactors (25 atm and 100°C). (ii) In recent years, the dependence of world energy on fossil fuel sources has been diversified towards clean, renewable alternative sources such as biomass. However, conversion technologies are required for producing energy from biomass and in order for bioenergy to enter the energy market such as those of the transport fuel. Two conversion methods of biomass gasification (to produce syngas) and pyrolysis (to produce bio-oil) are currently being investigated in pilot-scale gas-phase fluidized bed reactors. The goal of this research is to evaluate the reactor performance by investigating the effects of reactor scale and feedstock properties on the products yield. (iii) The negative environmental effects of CO2 emissions represent a growing problem as the utilization of fossil fuels such as coal is increasing and can be expected to do so for the future. Therefore, technologies associated with CO2 capture and storage are found to be essential to reduce these emissions. Research is underway to investigate a new process for CO2 capture for post combustion and in-situ pre-combustion/gasification. The research is focused on integration of fluidization processes of calcium looping (CaL) and chemical looping combustion (CLC) into in a new process and to develop composite materials combining the CaL and CLC sorbents into a single composite.