3038.     SCHADE, H. A., FORAN, E., AND ALDRICH, R. C.  Fischer-Tropsch Process.  Nat. Petrol. News, vol. 37, No. 45, 1945, p. R924; CIOS Rept. VI-22, X-18, X-22, XV-5, 1944, 25 pp., PB 373; TOM Reel 199; Chem. Abs., vol. 40, 1946, p. 7565.

        Further extract from a study of the Harnes plant in France. The plant capacity was 20,000 ton of liquid products per yr.  One-third of the water gas (CO, 40; H₂, 50; CO₂, 5; N₂ and CH₄, 5%) produced from high-temperature coke in water-gas generators of conventional design was passed over a catalyst of FeO at 500° with steam, giving a product rich in H₂ and CO₂.  This gas was blended with the rest of the original water gas to give a synthesis gas (CO, 27; H₂, 54; CO₂, 14; N₂ and CH₄, 5%).  S was removed in 3 stages:  A countercurrent tower wash with NH₃ water to remove H₂S; passage through purifying boxes containing Fe oxide and sawdust; and removal of organic S by passing over a catalyst of FeO and Na₂CO₃ at 200°-300°. The gas ready for synthesis is compressed to 3 p.s.i. before entering the 24 reactors, all cooled by a hot water-steam system so arranged that each pair of reactors shares a common header and control valve.  A cooling system capable of removing approximately 7,000 B.t.u. of heat per lb.-mol. of liquid product is important for 2 reasons:  The reaction must occur at a definite temperature range (in this case 200°+ or -3°), enough to promote the reaction but not so high as to decompose the products into CH₄, and the catalyst itself is a very poor conductor of heat.  Therefore, to prevent a hot spot in the catalyst bed, the mean path of heat travel from any catalyst particle to the cooling surface is kept below 2 mm.  The reactors are square boxes consisting of 600 thin baffles pierced by 600 tubes filled with hot water.  Each reactor has a total surface of 5,000 m.³ and weights 50 metric tons.  The catalyst fills the voids between baffles and tubes.  The density of the reactor thus filled is approximately 60% of that of solid steel.  Of the 24 reactors, 16 are normally used for the 1^st pass.  The effluent from these is cooled and condensed, and the resulting heavy product is removed.  The gases are sent next to the remaining 8 reactors for the 2d pass, which produces a lighter product than the 1^st pass.