Date of Graduation
Statler College of Engineering and Mineral Resources
Chemical and Biomedical Engineering
Due to insecurity in the crude oil supply and global warming, various alternative technologies for fuel production are being investigated. In this project, indirect, direct, and hybrid liquefaction routes are investigated for production of transportation fuels from coal and biomass. Indirect coal liquefaction (ICL) and direct coal liquefaction (DCL) technologies are commercially available, but both processes are plagued with high carbon footprint. Furthermore, significant amount of hydrogen is required in the DCL process leading not only to higher cost but resulting in considerable amount of CO2 production. Addition of biomass and application of carbon capture and storage (CCS) technologies are studied for reducing the carbon footprint. However, these two options can lead to higher capital and operating costs. Due to easy availability and low cost of the shale gas in the U.S., utilization of shale gas in the direct and hybrid routes was investigated for producing hydrogen at a lower cost with reduced CO2 emission in comparison to the traditional coal gasification route. Because the quality of the syncrude produced from ICL and DCL technologies vary widely, the hybrid coal liquefaction technology, a synergistic combination of ICL and DCL technologies, is investigated for reducing the penalty of downstream syncrude upgrading unit through optimal blending.;In the indirect CBTL plant, coal and biomass are first gasified to syngas. Then the syngas is converted to syncrude via Fischer-Tropsch (FT) synthesis. CO2 is captured from both raw syngas and FT vapor product. In the direct CBTL plant, coal and biomass are directly converted into syncrude in the catalytic two-stage liquefaction (CTSL) unit by adding hydrogen produced from gasification of coal/biomass/liquefaction residue or reforming of shale gas. Significant amount of CO2 that is generated in the hydrogen production unit(s) is captured to satisfy the target extent of CO2 capture. In the hybrid CBTL plant, pre-processed coal and biomass are sent to either syngas production unit or the CTSL unit. Produced syngas is sent either to FT unit or hydrogen production unit. Naphtha and diesel products from the FT unit and the CTSL unit are blended to reduce the syncrude upgrading penalty. Different CCS technologies are considered and optimized for the indirect, direct and hybrid CBTL plant depending on the sources of CO2 containing stream and corresponding CO2 partial pressure.;While several studies have been conducted for indirect CBTL processes, studies on direct and hybrid CBTL processes at the systems level and investigation of CCS technologies for these processes are scarce. With this motivation, high fidelity process models are developed for indirect, direct, and hybrid CBTL plants with CCS. These models are leveraged to perform comprehensive techno-economic studies. Contributions of this project are as follows: (1) development of the systems-level and equipment-level process models and rigorous economic models in Aspen Plus, Aspen Custom Modeler, Aspen Exchanger Design and Rating, and Aspen Process Economic Analyzer platforms, (2) sensitivity studies to analyze the impact of key design parameters (i.e. biomass/coal ratio, operating conditions of key equipment, extent of CCS, CCS technologies, blending ratio of the syncrude and products in the hybrid route) and investment parameters (i.e. price of coal and biomass, project life, plant contingency and plant capacity) on key efficiency measures, such as thermal and carbon efficiency, as well as economic measures, such as the net present value, internal rate of return and break-even oil price, (3) comparisons and analyses of trade-offs of indirect, direct, and hybrid CBTL technologies.
Jiang, Yuan, "Techno-Economic Studies of Coal-Biomass to Liquids (CBTL) Plants with CO2 Capture and Storage (CCS)" (2017). Graduate Theses, Dissertations, and Problem Reports. 5888.