GB669209A - Improvements in or relating to a method of and apparatus for recovering sulfur values from acid sludge from petroleum refining - Google Patents

Abstract

<PICT:0669209/III/1> Sulphur values are recovered from acid sludge from petroleum refining, by feeding the sludge which may be preheated to about 87.5 DEG C. on to an incandescent bed of coke maintained at such a temperature that the mixture of sludge and coke is above 260 DEG C. agitating the coke bed and pyrolyzing the sludge to obtain sulphur dioxide which may be scrubbed, dried and catalytically converted to sulphur trioxide for sulphuric acid manufacture. The sulphur dioxide gas may also be treated after scrubbing by passage through a further incandescent coke bed at 650-760 DEG C. to obtain a sulphur containing vapour which may be employed for the production of carbon disulphde or the sulphur recovered therefrom. Liquid sulphur, spent alkylation acid or hydrocarbon may be mixed with the sulphur dioxide prior to reduction in the second coke bed and the effluent containing sulphur, sulphur dioxide and hydrogen sulphide may be subjected to catalytic conversion employing alumina catalyst to obtain further sulphur. Alternatively the reduction is omitted and hydrogen sulphide from an extraneous source is mixed with the sulphur dioxide prior to entering the catalytic converter. The hydrogen sulphide may also be formed by mixing the sulphur dioxide with oil vapour and subjected the mixture to partial combustion, preferably to form a gas having a hydrogen sulphide/sulphur dioxide ratio of two to one, which is then fed to the catalytic converter. Apparatus suitable for carrying out the pyrolysis of the sludge is shown in Fig. 1 where sludge is fed through heat insulated pipe 49 on to an incandescent coke bed 35 stirred by rotating arms 19 with fingers 33. Air is admitted from pipes 41, 43, 45 and the sulphur dioxide formed withdrawn at 53. For discontinuous operation air is periodically shut off and purging steam admitted through pipe 47. If sulphur vapour is required, a double bed kiln may be employed the sulphur dioxide and coke from the upper bed passing to the lower bed when the sulphur dioxide is reduced to elemental sulphur.