Hamad, Natalie (2011-12). Safety and Techno-Economic Analysis of Solvent Selection for Supercritical Fischer-Tropsch Synthesis Reactors. Master's Thesis.
Fisher-Tropsch Synthesis is a primary pathway for gas-to-liquid technology. In order to overcome commercial problems associated with reaction and transport phenomena, the use of supercritical solvents has been proposed to increase chemical conversion and improve temperature control. One of the major challenges in designing the supercritical FTS systems is the solvent selection. Numerous alternatives exist and should be screened based on relevant criteria. The main aim of the thesis was to develop a safety metric that can be incorporated in the selection of an optimal supercritical solvent or a mixture of solvents. The objective was to minimize the cost while satisfying safety constraints or to establish tradeoffs between cost and safety. Hydrocarbons from C3 to C9 were identified as feasible solvents for FTS purposes. The choice of these solvents is dependent on their mixture critical temperature and pressure requirements that need to be satisfied upon entry into the FTS reactor. A safety metric system was developed in order to compare the risk issues associated with using the aforementioned solvents. In addition, an economic analysis of using the different solvents was performed. Finally, a case study was solved to illustrate the use of the proposed metrics and the selection of solvents based on safety and techno-economic criteria.