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 1st 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 1st pass.