This paper investigates issues related to metallurgical specification for Waste Heat Recovery superheater coils in a Sulphur Recovery Unit Thermal Incinerator as part of a Sour Gas Processing Facility for energy efficiency and environmental benefits.

This paper looks at the various operating scenarios for Waste Heat Recovery steam superheater coils in a Sulphur Recovery Unit Thermal Incinerator package and assesses the areas of concern regarding material specification related to corrosion resistance and design temperature. Several materials were identified that could be operated at the high flue gas temperature, but these were found to be unsuitable from a corrosion resistance perspective. Materials that are adequately corrosion resistant do not have a sufficiently high design temperature to allow sustained operation at the normal operating temperature of the Thermal Incinerator.

In liaison with specialist vendors, it was identified that to have corrosion resistant material for the superheater coils, the normal process scheme and start up and shutdown operating philosophy of the unit had to be modified to ensure a continuous flow of steam to the superheater coils. This minimum flow of steam inside the coils acts as a cooling medium and ensures the superheater coils will not exceed their design temperature. The paper acknowledges that to achieve the energy efficiency gained through operating superheater coils in a Sulphur Recovery Unit Thermal Incinerator a Process scheme must be developed that can allow corrosion resistant materials to operate safely without exceeding their design temperature, despite normal operating temperature of the Thermal Incinerator exceeding the material design temperature.

This paper will be of interest to any operator of a Sulphur Recovery unit who is looking for energy efficiency improvements, or operators of Thermal Incinerators with existing superheater coils who are experiencing asset integrity issues with their operation.

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