Design, Development, Scale-up, and Experimental Investigations of an Oil Treatment Reactor using Non-thermal Nanosecond Pulsed Plasma

Abstract

Traditional and non-renewable energy source, mainly conventional oil, is depleting and thus, unconventional energy source such as heavy oil is becoming increasingly crucial to meet rising energy demand. Because unconventional oil resources need more energy to develop, they emit more greenhouse gases (GHG) than conventional oil resources. This dissertation investigates an alternative novel technology that uses non-thermal, non-equilibrium nanosecond pulsed plasma in a multiphase oil treatment reactor to upgrade and refine heavy oil. Using this technology, the multiphase medium containing methane in the gas phase and n-hexadecane as liquid surrogate for heavy oil, interacts with the electrical discharge (plasma) and is converted to value added products such as hydrogen, smaller hydrocarbons in the gas phase and gasoline, diesel range products in the liquid phase. This dissertation focuses on the design, development, scale-up demonstrations, and experimental investigations of the oil treatment reactor. N-hexadecane was treated using the reactor to validate conversion chemistry, and quantify the pathways of vapor, condensate, liquid, and residue mass conversion. liquid and residue mass conversion. A complete mass balance and characterization of all products were determined using gas chromatography, mass spectrometry, thermogravimetric analysis and plasma was characterized using VI data from oscilloscope and power supply. Using 500 kJ/kg-hexadecane energy input this plasma process co-converts 9.36% of the hexadecane and 20% of the methane by mass. Distribution of products are: 2.18% hydrogen, 45.9% C2-C4, 28.9% high octane gasoline (C5-C11), 16.4% diesel (C12-C18), 2.78% heavier hydrocarbons, and 1.7% coke. Further development for the reactor included developing a methodology specifically used for scaling up a multiphase plasma oil treatment reactor using a multicity of reactors. Several reactors were developed to iterate the next generation of flow reactors with up to 13 sparks. A scalability model was also developed with varying number of sparks up to 50 gaps, target energy input up to 3000kJ/kg and target system processing rate of industrial scale up to 1000bbl/day. Next, the changes in gas phase composition that occurs under submerged multi-phase pulsed plasmas in hydrocarbons is investigated. The effect of temperature of liquid at 25oC and 100oC and input carrier gas (Methane and Argon) are also studied. Using methane as a carrier gas at 100oC increased the effectiveness of multiphase plasma and comparison with Argon (Ar) as an inert gas demonstrated that multiphase plasma can interact with both gas and liquid phase. Experiments were also conducted with the primary objective of producing hydrogen. Parametric study of various plasma target powers (0.1W,1W,4W) and capacitances (25pF, 100pF, 440pF) using pure CH4 with n-C16 and pure Ar with n-C16 were conducted. Using a low energy per pulse, high voltage, and low capacitance is optimal for high energy efficient hydrogen gas production (>0.02 kg/KWh) for a nonthermal pulsed plasma batch oil treatment reactor with CH4. Finally, this dissertation also evaluates the energy requirements, associated greenhouse gas emissions, and energy economics of using plasma processing technology (PPT) for heavy oil upgrading in refineries by replacing the fluid catalytic cracker unit using a model called petroleum refinery life cycle inventory model. Implementing PPT increases energy consumption by 18% in the medium refinery and 14% in the deep refinery which translates to <2% energy content of a barrel of oil. The greenhouse gas emissions were reduced significantly with 21% for medium and 35% for deep refinery configuration. Integrating such technology in just 3% of United States refineries can reduce emissions by 2 million metric ton CO2eq/year, a significant milestone toward energy transition. Overall, the reactor demonstrates multiple advantages, and some highlights include high conversion and efficient cracking of heavy oil using low energy cost, operating near ambient pressure and warm temperature, ease of manufacturing and maintenance of the reactor and low emissions.