Evaluation of different alternatives for increasing the reaction furnace temperature of Claus SRU by chemical equilibrium calculations

Application of different alternatives for increasing the reaction furnace temperature of Claus sulfur recovery units (SRUs) are investigated by chemical equilibrium calculations. The Gibbs free minimization method based on Lagrangian multipliers is used for formulating the problem. The usefulness of different techniques such as fuel gas spiking, indirect air and/or acid gas preheating, oxygen enrichment, acid gas enrichment and direct air preheating for increasing the furnace temperature are determined by the proposed algorithm. In the case of lean feed acid gases, it may be necessary to use a combination of methods in order to attain the minimum furnace temperature required for flame stability and complete destruction of acid gas hydrocarbon contaminants. It is found that the acid gas enrichment is a reliable technique for providing the required reaction furnace temperature when a high flow of too lean acid gas is to be processed in a Claus unit. The predicted reaction furnace temperatures are in good agreement with the measured experimental values.