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

在流化、气力输送、研磨、混合等多种气固工艺中，在颗粒处理、运输和加工过程中产生静电荷，从而导致颗粒-壁粘附、颗粒附聚和产生引起爆炸的高压电场。静电现象的重大负面影响在各个行业都有报道。在石化工业中，聚乙烯气固流化床反应器中的结垢事件可能导致近100万美元/天的重大经济损失。在药品的情况下，干粉吸入器（由患有肺病如哮喘的人使用）内部发生药物粉末凝聚和沉积，这反过来通过限制喷射剂量而降低吸入器的效率。在化学工业中，在研磨固体如水泥或矿物的过程中，产生相当大量的电荷，导致颗粒团聚，这是非常不希望的，因为精细研磨的颗粒看起来比它们实际上大，明显降低了该方法的研磨效率。 在工业聚乙烯气固流化床反应器中，有大量的需要来确定防止或消除静电荷的产生的方法，以及在不同的气固过程中，如气力输送和研磨中的颗粒充电机制。拟议的研究计划将（a）使用最先进的加压中试气固流化基础设施，该设施能够在高达2500 kPa，110 ℃的高压下运行，并采用新型静电荷测量技术来确定流化温度和催化剂存在对反应器结垢的影响;（B）提供对由于气动输送引起的固体装料的透彻理解，包括在被注入聚乙烯流化床反应器时催化剂静电荷的影响;（c）开发一个欧拉-欧拉计算流体动力学模型，以便能够预测各种气固过程中的颗粒充电，包括流化床的颗粒充电;（d）为提高化工行业的粉磨效率提供了一个全面的粉磨过程中固体装料的研究。该研究计划的预期影响是帮助包括石化和化学品在内的行业，这些行业对加拿大和世界经济至关重要，以更好地了解静电充电机制，并减少这些行业面临的运营挑战。

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.