Sasol Technology Proprietary Limited

Alex Philip Vogel

Peter Jacobus Van Berge

Andre Peter Steynberg

Hermanus Gerhardus Nel

A process () to produce Fischer-Tropsch products includes feeding feed synthesis gas () with a substantially constant target feed synthesis gas H/CO ratio to a Fischer-Tropsch synthesis stage (). A portion of the feed synthesis gas () is converted to Fischer-Tropsch products in the Fischer-Tropsch synthesis stage (). The Fischer-Tropsch products () from the Fischer-Tropsch synthesis stage () are withdrawn. A Fischer-Tropsch synthesis stage tail gas () which includes unconverted Hand CO is obtained. The operating conditions of the Fischer-Tropsch synthesis stage () are manipulated to achieve a substantially constant target tail gas H/CO ratio, with the target tail gas H/CO ratio being substantially different from the target feed synthesis gas H/CO ratio.

Fischer-tropsch synthesis

Gaseous reactants () are fed into a slurry bed () of solid catalyst particles in a liquid. The reactants react as they pass upwardly through the bed, thereby forming liquid and gaseous products. In a primary filtration stage (), the liquid product passes through a filtering medium having filtering openings, which have a controlling dimension of x microns, so that large catalyst particles greater than x microns are removed. A primary filtrate containing near-size and fine catalyst particles is subjected to secondary filtration () to remove near-size particles. A cake of catalyst particles forms on the filtering medium. The passage of liquid product through the filtering medium is interrupted, and the filtering medium is backflushed by passing secondary filtrate through it in a reverse direction, to dislodge the cake from the filtering medium.

Process for separating a catalyst from a liquid

A process for producing liquid and, optionally, gaseous products from gaseous reactants feeds ( ), at a low level, gaseous reactants into a slurry bed of solid catalyst particles ( ) suspended in a suspension liquid. The gaseous reactants are allowed to react as they pass upwardly through the slurry bed ( ), hereby to form liquid and, optionally, gaseous products. The reaction is catalyzed by the catalyst particles. Liquid product is separated from the catalyst particles by passing, in a filtration zone ( ) within the slurry bed, liquid product through a filtering medium having a plurality of openings through which the liquid passes. The openings have a controlling dimension of x microns. The proportion of catalyst particles, which have a particle size smaller than x microns, in the slurry bed is less than 18% by volume based on the total volume of the catalyst in the slurry bed.

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Vereeniging, South Africa

Alex Philip Vogel