Powder bed coating of bitumen with asphaltenes to obtain solid prills for midstream transportation

Abstract

A continuous increase in the global demand for liquid fuels has led to increased reliance on unconventional sources of fossil fuels such as bitumen. The extraction, midstream transportation, and ultimate processing of heavy oils presents a distinctive set of challenges. For example, the high viscosity of bitumen poses a challenge to its transportation through conventional transportation systems such as pipelines. Conventional approaches to address the challenging rheological properties of bitumen involve dilution of bitumen with natural gas condensates, addition of surfactants, ultrasonic heating, thermal jacketing of pipelines, and high pump pressures. These solutions require considerable investments in infrastructure, frequent inspection and maintenance, and pose a risk of spillage to vulnerable environments. As such, much interest has focused on the design of solid-state transportation methodologies. In this article, we propose a viable and safe transportation alternative wherein bitumen is reconfigured such that the droplets of lighter fractions of bitumen (saturates, aromatics, resins) are encapsulated within conformal shells of asphaltenes. The tendency of asphaltenes to aggregate has been exploited to obtain cross-linked shells without requiring the use of extraneous chemical additives. Thermally mediated crosslinking of the asphaltenes shells allow the microcapsules to hold their form and result in the emergence of mechanical strength. The stress-withstanding abilities and velocity impact resistance of these microcapsules have been studied to establish their viability for industrial use, and demonstrate that microcapsules with diameters of ca. 1.25 mm can withstand stresses as high as 576 kN/m2. Since the bitumen microcapsules have been formulated by simply reconfiguring the intrinsic components of bitumen, they can be readily fluidized by mechanical means to recover the encapsulated lighter fractions. The solid microcapsules demonstrate the viability of solid-state transportation of bitumen via roadways or marine tankers, thereby mitigating a primary impediment to the utilization of viscous oils.