Patent ID: 7531135

Claim:
In a system for recovering sulfur from a process gas stream initially comprising an amount of a hydrogen sulfide containing gas and an amount of an oxygen containing gas, the system comprising a thermal reaction apparatus, a catalytic reaction apparatus downstream of the thermal reaction apparatus, a source of the oxygen containing gas and a flow control apparatus associated with the source of the oxygen containing gas, the thermal reaction apparatus comprising an inlet and an outlet, the catalytic reaction apparatus comprising an inlet and an outlet, a control system comprising: (a) a first analyzer for analyzing a composition of the process gas stream at a first location between the inlet of the thermal reaction apparatus and the outlet of the catalytic reaction apparatus; (b) a first controller associated with the first analyzer and operatively connected with the flow control apparatus, for controlling the amount of the oxygen containing gas having regard to the composition of the process gas stream at the first location; (c) a second analyzer for analyzing a composition of the process gas stream at a second location downstream of the outlet of the catalytic reaction apparatus; and (d) a second controller associated with the second analyzer and operatively connected with the flow control apparatus, for controlling the amount of the oxygen containing gas having regard to the composition of the process gas stream at the second location.