Experience with a new type of reactor for Fischer-Tropsch synthesis

Circulating fluidised bed (CFB) reactors have traditionally been used for the high temperature Fischer-Tropsch synthesis-Synthol process. A development program undertaken by Sasol with the assistance of The Badger Company recently led to the successful commissioning of a commercial scale conventional, fixed fluidised bed (FFB) reactor as an alternative to the CFB reactor.Work was done in a small pilot plant which was followed by work in a 1 m diameter semi-works pilot plant operated in parallel with one of the commercial CFB reactors. Based on the positive results obtained, it was decided to build a commercial scale FFB reactor with a capacity similar to existing commercial reactors at Sasol One. This reactor was successfully commissioned and has been in operation since May 1989.The reactor is easy to operate and can withstand major plant instabilities. A techno-economic analysis and comparison between the Synthol-CFB and Synthol-FFB reactors indicates significant advantages for the Synthol-FFB reactor, both with respect to capital and operating costs. The results of this analysis and comparison are presented and the significance of the findings discussed in terms of future plants for the conversion of synthesis gas to liquid fuels.