Process flow sheet synthesis: Systems-level design applied to synthetic crude production

Abstract This paper showcases a novel approach for designing concepts for process flow-sheets at the “systems-level”. A graphical technique, called the “GH-space”, is used to analyze the flows of heat and work within a process to provide insight into the interactions of various process units within the process. Any unit process, which interacts with the surroundings by transferring heat and work, can be represented as a vector on the GH-space. By manipulating these vectors, a process can be designed to meet certain design criteria or constraints. While material and energy balances are normally performed on a flowsheet, this vectored approach allows the material and energy balances to be used to construct a flowsheet. This paper focuses on the design of a flow-sheet for the production of synthetic crude oil by way of Fischer-Tropsch hydrocarbons. It was shown that a process could be designed that not only produced the desired product but could also be thermodynamically reversible and carbon neutral. The goal of this work is not to present a final optimized design but rather to call attention to the possibilities that could lead to potential solutions to the most challenging problems facing the newest generation of design engineers. Perhaps the greatest strength of the GH-space technique is that it tends towards the “best” thermodynamic solution. It may not be possible to achieve this best solution, in a practical sense, but it is invaluable in providing a basis for comparison.