Session: 05-06 Other CSP Technologies

Paper Number: 110650

110650 - Concentrated Solar Power as an Energy Source for the Ignition of Self-Sustained Smoldering Remediation of Petroleum-Contaminated Soils 

Smoldering is a common method of remediation for contaminated soil, but the high energy demand is often met with electrical resistance heating, which becomes cost-prohibitive and logistically infeasible in locations without robust electrical infrastructure. This research evaluated the mechanical and economic feasibility of using concentrated solar power (CSP) as a heat source in the ignition of self-sustained smoldering remediation of petroleum-contaminated soil. Using solar collectors consisting of parabolic reflectors to concentrate sunlight and fiber optic bundles to transmit it, we demonstrated effective treatment with CSP. Initially, quasi-one-dimensional proof-of-concept experiments with 750 mL reaction volumes were used to demonstrate that ignition of smoldering remediation could be achieved and detectable hydrocarbons in the soil could be reduced with treatment via CSP. Temperatures in these bench-scale experiments exceeded 400°C before ignition was initiated with aeration. Next, 5 L experiments in a narrow channel were used to optimize the treatment process for larger volumes in quasi-two-dimensional experiments. Fiber optic bundles were linearly aligned and evenly spaced along a narrow thermal receiver at the bottom of the reaction chamber and samples were treated using CSP. Granular activated carbon (GAC) was mixed with clean soil and used as a  cleaner-burning alternative to petroleum-contaminated soil for evaluating treatment feasibility of solar technology. GAC-contaminated soil exhibited similar behavior to petroleum-contaminated soil but required slightly higher ignition temperatures and power outputs. A robust ignition was consistently demonstrated when at least 240 W of concentrated solar power were delivered to the reaction chamber. This was achieved with the use of four solar collectors. Ultimately, three dimensional experiments were performed with soil volumes between 10 and 37 L with the objective of optimizing the propagation of the smoldering front horizontally through the volume of soil and estimating costs of an industrial-scale prototype. Results revealed that once ignition has been achieved with CSP, the smoldering front can be propagated horizontally without additional power input. Further power input can be used to accelerate horizontal propagation velocities but is not required for self-sustained smoldering to continue. Based on these data, the capital cost of solar collectors for an industrial-scale prototype to treat ~85 m³ volumes of soil is estimated to be on the order of $100,000. 

Presenting Author: Corey Trujillo University of Colorado Boulder

Presenting Author Biography: Corey Trujillo recent graduate of the University of Colorado Boulder where he earned his Ph.D. in mechanical engineering. His doctoral work concerns the remediation of petroleum-contaminated soils using concentrated solar power and for this work, he developed and modified solar tracking and delivery technology. Prior to joining the University of Colorado Boulder, he completed his master’s degree at the University of Nevada, Reno where he used computational fluid mechanics to model the thermal and fluid environment in used nuclear fuel canisters. In addition to research, Trujillo he serves as a high performance computing administrator and he enjoys teaching classes and advocating for underserved students.