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Literature Abstracts

 1522.    HUTCHISON, W. K.  A Plant for the Removal of Sulfur Compounds by Oil Washing.  Inst. Gas Eng., Copyright Pub. 175/64, 1937, pp. 8-44, 51-64; Gas Jour., vol. 220, 1937, pp. 475-476, 479-485, 667; Gas World, vol. 107, 1937, pp. 379-383, 471-476, 563; Chem. Abs., vol. 32, 1938, p. 6437.

        S was determined by drawing products of combustion of a free-burning flame of gas in purified air through an accurately neutralized solution of H2O2 of about 5 vol. strength and titrating H2SO4 formed with standard alkali with methyl red indicator.  S compounds likely to be present in purified coal gas are CS2, COS, thiophene and its homologs, mercaptans, sulfides and disulfides, the last 3 representing less than 5% of the total S.  As much as 18% of S in some coal gas is in a compound completely absorbed by alcoholic KOH, similar to CS2 but more volatile, perhaps COS.  Methods for determination of each are described, and analyses of 9 coal gases are tabulated.  Partition factors for benzene and CS2 were determined for 10 oils; this factor is largely instrumental in determining the quantity of oil to circulate.  Sludge formation increased rapidly with temperature but varied widely in different oils, gas oils being most unstable.  Washing with 80% H2SO4, followed with 10% NaOH and distilling greatly reduced sludge formation in gas oil.  Specific gravity of oil used should be far enough from H2O to reduce likelihood of emulsion formation.  Viscosity should be as low as possible; doubling viscosity will increase the size of heat exchangers one-third and increase back pressure one-half.  The mean boiling point should be high and distillation range narrow.  The relations between rate of oil circulation, partition factor, and the characteristics of the washing plant; the conditions governing the performance of the stripping plant; and the effect of individual efficiencies of the two parts on the performance as a whole are analyzed.  Some of the features of the plant are described, including power and heat, pumps, vacuum system and heat exchangers.  The process differs from others in the larger quantity of oil circulated and lower ratio of steam to oil in stripping.  The most favorable stripping conditions were distillation at 80° and 20 mm. abs. pressure; exhaust steam at a m. pressure can be used at this temperature.  After 7 months’ operation, total S removal is 70-76%.  CS2 removal is 90%.