Investigation of electrostatic charging in various gas-solid processes including fluidization and pnumatic conveying

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In many gas-solid processes such as fluidization, pneumatic conveying, grinding, mixing, etc., electrostatic charges are generated during particle handling, transport and processing in which resulting in particle-wall adhesion, particle agglomeration, and generation of high-voltage electrical fields causing explosions. The significant negative impact of electrostatic phenomenon has been reported in various industries. In the petrochemical industry, a fouling incident in polyethylene gas-solid fluidized bed reactors could result in major economic losses of nearly $1.0M/day. In the case of pharmaceuticals, drug powder agglomeration and deposition occurs inside dry powder inhalers (used by those who suffer from lung illnesses such as asthma) which in turn reduces the efficiency of the inhaler by limiting the emitted dose. In the chemical industry, during grinding of solids such as cement or minerals a considerable amount of charge is generated leading to particle agglomeration which is quite undesirable because finely ground particles appear larger than they actually are, appreciably reducing grinding efficiency of the process. ******There is a great deal of need to determine ways to prevent or eliminate generation of electrostatic charges in industrial polyethylene gas-solid fluidized bed reactors, as well as shed some light on particle charging mechanisms in different gas-solid processes such as those of pneumatic conveying and grinding. The proposed research program will (a) use a state-of-the-art pressurized pilot plant gas-solid fluidization infrastructure that is able to operate at high pressures of up to 2500 kPa, 110C and houses a novel electrostatic charge measurement technique to determine the effects of fluidization temperature and presence of catalyst on the reactor fouling; (b) provide a thorough understanding of solids charging due to pneumatic conveying including the impact of catalyst electrostatic charging while being injected into the polyethylene fluid bed reactors; (c) develop an Euler-Euler Computational Fluid Dynamic (CFD) model enabling the prediction of particle charging in various gas-solid processes including those of fluidized beds; and (d) provide a comprehensive study of solids charging in grinding process to improve the grinding efficiency in the chemical industry. The anticipated impact of the research program is to assist industries including petrochemical and chemicals, sectors of vital importance to the Canadian and world economies, to gain a better understanding of the electrostatic charging mechanisms and to reduce operational challenges faced by these industries.******