11 Nov 2024
Increasingly the world is trying to decarbonize and for the aviation sector this is an important goal. Unfortunately, aviation is also one of the hardest sectors to decarbonize since batteries nor hydrogen are anywhere near practicality for commercial aviation. The weight to power ratios are far too low. Previously we at Amar blogged about the general approach for SAF (Sustainable Aviation Fuel) and one of the strategies is Fischer Tropsch Synthesis. This blog post tries to dig deeper into Fischer Tropsch Synthesis (FTS) and the different types of Fischer Tropsch Reactors used in this process. The Figure above shows the Shell Pearl GTL plant in Qatar. This uses Fischer Tropsch Synthesis but starting from natural gas. Much of the recent work targets conversion of the feedstock to bio-based sources, e.g. municipal waste or biomass, and that creates many challenges for designing efficient Fischer Tropsch Reactors.
The Figure below (Ref. NETL US DOE) shows a schematic of the typical traditional Fischer Tropsch Synthesis process. For SAF applications, although there are several variations in the approach and flowsheet, a typical product may shoot for the ASTM D7566 standard which applies specifically to “Aviation Turbine Fuel Containing Synthesized Hydrocarbons”.
Fischer Tropsch Synthesis has been around for a long time, more than 100 years, however, the needs of SAF are often different from traditional applications which were run to optimize for product distribution in the vehicular fuel domain. Hence substantial new technology is being developed to produce SAF at price points which are competitive. E.g. Velocys is one such company. Often these are start-ups and extensive pilot plant work is needed before large investments are made. The image below shows a state-of-the-art Fischer Tropsch Synthesis pilot reactor by Sasol in collaboration with Ineratec Germany. Clearly these pilot plants use advanced Fischer Tropsch Reactors that are at the high end of complexity and price.
Fischer Tropsch Synthesis has substantial challenges both in catalysts as well as Fischer Tropsch Reactors design. Historically, plants have used fixed bed reactors, fluidized beds, and even slurry mode operations as types of Fischer Tropsch Reactors. Clients increasingly come to us at Amar since we have past experience in providing all three types of Fischer Tropsch Reactors. Contact us for more details.
Coming to catalysts, Fe is the dominant catalyst choice although Cobalt can work but is much more expensive. Catalyst design is an active area of work to optimize product distributions in Fischer Tropsch Synthesis. All of this requires high throughput screening of catalysts. Initial work may be in lab/batch mode but eventually a flow mode continuous pilot plant is needed for proving long-term viability of the catalyst inside Fischer Tropsch Reactors. We at Amar manufacture a range of equipment for parallel screening of catalysts (in general, not specific to FTS) [React - 7] and also flow mode. The below image is a high throughput multi-tube fixed bed reactor system for catalyst screening manufactured by Amar.
From a customer point of view, it is important to design a pilot plant that allows tight control of conditions and acquisition of detailed data. Most plants are fully automated and highly instrumented. Although this can be expensive, it is much cheaper than the hundreds of millions of dollars invested into large-scale Fischer Tropsch Synthesis plants using commercial-scale Fischer Tropsch Reactors. Our experience is that disaster comes for clients who are penny wise pound foolish. Fischer Tropsch Synthesis is not the sort of pilot plant project where you can afford to cut corners. Capex is huge and margins small so any errors at pilot plant scale get magnified to a large project which can even kill the entire project. The trick lies in finding a vendor with a lower cost of execution (of course, with competence and experience) which allows complex pilot plants and Fischer Tropsch Reactors to be built without compromising on instrumentation etc. This is a sweet spot for us at Amar.
Some of our past work is highlighted by Tennassine, our excellent representatives in Brazil. Brazil has been a hub for both Fischer Tropsch Synthesis and SAF work and events such as the Brazil SAF summit are crucial forums for many of our customers. The Government of Brazil has recently announced 1 Billion USD worth of support for SAF projects and that is driving a lot of business for Amar in the Fischer Tropsch Synthesis domain.
Again, we recommend customers to contact us for a confidential consultation.
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