A Fischer-Tropsch synthesis reactor model framework for liquid biofuels production.

Abstract

Fischer-Tropsch synthesis (FTS) is an attractive option in the process of converting biomass-derived syngas to liquid fuels in a small-scale mobile bio-refinery. Computer simulation can be an efficient method of designing a compact FTS reactor, but no known comprehensive model exists that is able to predict performance of the needed non-traditional designs.This work developed a generalized model framework that can be used to examine a variety of FTS reactor configurations. It is based on the four fundamental physics areas that underlie FTS reactors: momentum transport, mass transport, energy transport, and chemical kinetics, rather than empirical data of traditional reactors.The mathematics developed were applied to an example application and solved numerically using COMSOL. The results compare well to the literature and give insights into the operation of FTS that are then used to propose a new reactor concept that may be suitable for the mobile bio-refinery application. 4 AcknowledgementsI am deeply grateful to the Sandia LDRD office and the ECIS investment area for sponsoring this project.I would also like to thank the following people who participated in this project:• Chris Shaddix for his mentorship, both technically and personally, throughout the project.• Hank Westrich and Sheri Martinez at the LDRD Office for their assistance and encouragement.• Daniel Dedrick for his work in forming the concept of this LDRD topic.• Blake Simmons for providing project management so I could focus on the technical challenges.• Deanna Agosta for financial planning.• Tiffany Vargas and Karen McWilliams at the CA Technical Library for providing and/or helping me find the countless papers and texts used to develop my understanding of everything from the detailed theory to the history and applications of FTS. 5 SummaryLiquid fuels synthesized from renewable CO and H 2 could displace petroleum-based fuels to provide clean, renewable energy for the future. Small scale (<20 bbl/day) reactors for synthetic liquid fuels production are an emerging development area that may enable mobile biomass-to-liquids plants suited for on-demand liquid fuel production from diverse, underutilized, local resources. The design of such a "mobile bio-refinery" is a significant departure from the traditional large-scale industrial designs and requires predictive tools such as computer models to efficiently produce a successful facility. Because existing models inherently incorporate the empirical results of the traditional designs they are not suitable for this application. The need for a model that can examine the drastic design changes and innovations needed for the mobile bio-refinery is clear.The goal of this work was to create a gas-to-liquids synthesis model with the minimum amount of empiricism and assumptions allowed by the current state of the theory, through integrated physics component models across varying length scales, with the ultimate purpose being to enable design of efficient, durable, and flexible small scale and/or novel re...

Temperature stabilisation in Fischer–Tropsch reactors using phase change material (PCM)

“…The heat from the reaction is removed by surrounding cooling, saturated water. It is assumed the water is circulated at a rate high enough as to maintain the outer tube wall at constant temperature [3,7]. The FBR has been selected for this study principally because it presents the greatest challenge in terms of heat rejection [5][6][7][8][9][10][11].…”

“…diesel, petrol and linear α-olefins) as a result of an aggregate of surface polymerisation reactions occurring in situ, on active sites of catalysts (Co, Ni, Fe and Ru). The availability of a wide variety of feedstock, increasing requirement for cheaper and sustainable sources of energy, and the need to monetize smaller and/or stranded pockets of natural resources (through the use of smaller and more compact reactors) altogether have lent momentum to the process in recent times [1][2][3][4][5][6]. In fact, it has been estimated that by 2015, the global annual production rate of liquid fuels and chemicals from the FTS would be approximately 30 million tonnes [1].…”

“…It is thus crucial to ensure that the FT reactor has a welldesigned heat rejection method [3,6]. This requirement for excellent heat rejection has inspired the wide variety of FT reactor designs available on the market today such as: the fluidised bed (circulating and fixed), slurry phase, and fixed bed reactors (FBR), etc.…”

“…This requirement for excellent heat rejection has inspired the wide variety of FT reactor designs available on the market today such as: the fluidised bed (circulating and fixed), slurry phase, and fixed bed reactors (FBR), etc. [3,[9][10][11][12][13]. The FTS is broadly classified into two categories namely: the Low Temperature …”

“…(1) For a full kinetic description of the process, the methane synthesis is considered as a separate reaction [1][2][3] (2) Lastly, on a Fe-based catalyst, the undesirable water-gas shift reaction, producing CO 2 as a diluent, plays an important role: The objective of this paper is to present a 2-dimensional pseudo-homogeneous, steadystate model of a Fe-catalysed LTFT FBR with temperature modulation using the combined effect of the PCM and jacket cooling liquid. To the best of our knowledge, this has not been previously done in open literature.…”