This case study examines a stress analysis conducted in accordance with ASME VIII Division 1 Boiler and Pressure Vessel Code for a main burner system. The burner in question features a vessel with an air inlet nozzle and connects to a “gun” with both a fuel gas inlet and an acid gas inlet. Within the vessel, the waste gas (acid) is ignited and combusted in a chamber linked to the burner. The design requirements for the burner include handling temperatures up to 350˚C and internal pressures of 5 barg.
Assessment
The burner design provided by the client was evaluated for compliance with ASME VIII Division 1 Boiler and Pressure Vessel Code. The analysis involved translating the nozzle loads from the air inlet, fuel inlet, and gas inlet to determine the loads on the connection flanges. These flanges connect the gun to the burner and the burner to the combustion chamber. The flanges were selected and/or sized based on the equivalent pressure loads.
To thoroughly assess the transition areas between different burner components, a finite element model was utilized. These transition interfaces were identified as critical due to potential stress concentrations.
Results
The design-by-rules analysis revealed that the saddle base plate had inadequate thickness, necessitating an increase to meet safety standards. Additionally, the flanges for the acid gas and fuel inlets exhibited insufficient blade thickness for the specified design conditions. Rather than increasing the blade thickness, a review of the design conditions was conducted. It was determined that the design temperature for these components could be reduced. This adjustment was feasible because the inlet flanges experience gases entering the burner at approximately 60˚C. By adopting a reduced design temperature, both the costs and lead time for the burner were effectively minimized.
Conclusion
The comprehensive stress analysis of the main burner led to crucial design modifications. The findings underscored the importance of accurate component sizing and material selection to meet operational requirements while optimizing cost and efficiency.
