Grant: Discovery Grants Program - Individual

In many gas-solid processes, electrostatic charge is generated during solids handling, transport (e.g., pneumatic conveying), and processing (e.g., gas-solid fluidization) due to contacts among solids, and solids and the container walls. Charge build-up results in solids-wall adhesion, agglomeration, and generation of high-voltage electrical fields that can cause explosions. The adverse impact of electrostatics has been reported in industries including petrochemical, pharmaceuticals, chemicals, etc. In the petrochemical industry, a wall fouling (known as "sheeting") incident in polyethylene gas-solid fluidized bed reactors could result in major economic losses of nearly $2.0M/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. Another example is in solids pneumatic conveying in which among all industrial powder operations, due to high flow velocities, is known to lead by far to the greatest electrostatic charge levels. In addition to electrostatic discharge that could cause dust explosions, solids may deposit on the conveying pipes surfaces causing partial blockage, loss of valuable material, and potentially leading to deviations from the system stable operation. Therefore, there is a great deal of need to determine ways to prevent, mitigate or eliminate generation of electrostatic charge in industrial processes including 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. The goals of the proposed research program are: (a) to use a state-of-the-art pressurized pilot plant gas-solid fluidization infrastructure (able to operate at high pressures of up to 2500 kPa, 60°C and houses a novel electrostatic charge measurement technique) to determine the effects of the presence of catalyst as well as various fluidization gases on the degree of reactor wall fouling; (b) to provide a thorough understanding of solids charging due to pneumatic conveying including the impact of catalyst electrostatic charging while being injected into a polyethylene fluidized bed reactor; and (c) to develop an Euler-Euler Computational Fluid Dynamic (CFD) models enabling the prediction of particle charging in various gas-solid processes including those of fluidized beds and solids pneumatic conveying. The results obtained in this research program could ultimately be applied to any gas-solid process facing challenges from electrostatic phenomena. 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.