GB722038A - Improvements in or relating to the recovery of sulphur from gases - Google Patents

Abstract

In the continuous recovery of sulphur from hydrogen sulphide-containing gas by passing the gas after partial combustion through a first stage catalyst chamber at a temperature sufficiently high to prevent condensation therein of the sulphur produced, separately condensing the sulphur, and then passing the remaining gases through a second stage catalyst chamber at a temperature such that sulphur condenses on the catalyst, revivification being carried out during the process by employing at least two second stage catalyst chambers and revivifying one while the other is on stream by the passage therethrough of a gas at such a temperature as to vaporize the sulphur and passing the resulting gaseous mixture to the main process stream prior to the sulphur condenser, the ratio of hydrogen sulphide to sulphur dioxide in the gas stream after the sulphur condenser and before the second stage is continuously determined and restored to a predetermined value by adjustment of the total air employed for the partial combination. The ratio is desirably such as to give the optimum yield of sulphur in the overall process, which ratio is found by experiment as that giving the lowest concentration of sulphur dioxide and/or hydrogen sulphide at the outlet of the second stage. Alumina and compounds of titanium are preferably employed as catalysts in the second stage. The catalyst may be present as a static bed, preferably of shaped pieces or broken granules of a size of for example 1/8 to 3/8 inch. Revivification may be effected using an oxygen free gas, for example gas from the main process stream at any point after the sulphur condenser, or by an oxygen-containing gas. In the latter case part of the sulphur is burnt, the heat thereby produced assisting in the vaporization of the remainder, and the resulting gas is returned to the main process stream prior to the first stage. The catalyst bed may be heated during revivification by electric heaters or heat transfer media. In the latter case heat available from the first stage may be employed in the second stage. A jet pump may be employed to recycle the gases for regeneration, using part of the momentum of the gases leaving the first stage reactor. Specifications 622,324 and 695,496 are referred to.