Application of high-frequency alternating-current principles to develop practical induction well bore heaters for in-situ thermal ground remediation

加拿大政府列出了全加拿大23，670处土壤和水中的污染物已经得到补救或需要补救的地点。仅在阿尔伯塔，1990年至2012年期间，约有648万升碳氢化合物液体泄漏到土壤和水中。目前正在使用一些电气和化学方法来修复这些碳氢化合物泄漏附近的污染土壤。电气方法涉及使用插入地面的大型电极对受污染的土壤和水进行电热或电加热，这些电极由地面上的大型交流电源驱动。电热加热提供了解吸土壤中的碳氢化合物污染物而不添加二次化学污染物的优点。受污染土壤电热加热的挑战来自功率损失和渗透性较低的土壤类型中有限的热渗透距离。最近，行业合作伙伴（McMillan-McGee Corp.）也开发了配备有线圈的感应加热器，该线圈产生远高于60 Hz的AC频率的磁场，以在周围的钢井筒管套管的壁中感应热量。更有效地加热土壤。与传统的60 Hz电极不同，表征和减轻高频下的这些损耗甚至更具挑战性，因为预期损耗不仅是由于线圈导体损耗，而且还由于线圈的电场和磁场与周围井眼管道的相互作用，并且在较小程度上与周围地层的相互作用。对于电热应用，这些损耗中的一些被转换为热量并辅助电加热过程，但其他损耗抑制了电力沿线圈的沿着传递和传输。McMillan-McGee和卡尔加里大学已经形成了一个研究合作，以研究和表征McMillan-McGee新型高频电热感应加热器中的高频电损耗。在电热修复过程中，将10-80 kW的功率水平发送到加热器中，表征和最小化这些损失对于更快地净化土壤和节省更多能源变得重要。

The Government of Canada lists 23,670 sites Canada-wide where contaminants in soil and water have been remediated or are in need of remediation. In Alberta alone, roughly 6.48 million liters of hydrocarbon liquids have leaked onto soil and water between 1990 and 2012. A few electrical and chemical methods are currently in use to remediate the contaminated soil in the vicinity of these hydrocarbon leaks. Electrical methods involve electro-thermal or electrical heating of contaminated soil and water using large electrodes inserted into the ground, which are driven using a large AC power source on the surface. Electro-thermal heating offers the advantage of desorbing hydrocarbon contaminants in soil without adding secondary chemical pollutants. Challenges with electro-thermal heating of contaminated soil come from power losses and limited heat penetration over distance in less permeable soil types. More recently inductive heaters fitted with coils that produce magnetic fields at AC frequencies much higher than 60 Hz to induce heat in the walls of surrounding steel wellbore pipe casings have also been developed by the industry partner (McMillan-McGee Corp.) for heating soil more effectively. Unlike conventional 60 Hz electrodes, characterizing and mitigating these losses at high frequencies is even more challenging since losses are expected to be due to not just coil conductor losses but also due to the interaction of the coil's electric and magnetic fields with the surrounding well-bore pipe, and to a lesser extent on the surrounding ground formation. For electro-thermal applications, some of these losses get converted to heat and assist with the electrical heating process but others inhibit electrical power transfer and transmission along the coils. McMillan-McGee and the University of Calgary have formed a research collaboration to study and characterize these high frequency electrical losses in McMillan-McGee's new higher frequency Electro-thermal inductive heaters. With power levels of between 10-80 kW sent down hole into the heaters during the electro-thermal remediation process characterizing and minimizing these losses becomes important for quicker decontamination of soil and saving more energy.