A convection style direct fired heater offers the user the benefits of a direct fired heater, while eliminating some of the drawbacks associated with radiant heat transfer. Radiant heat transfer can be undesirable in certain temperature sensitive applications, as radiant heat transfer tends to be more intense and unevenly distributed around the coil surface. Sigma Thermal's convection style direct fired heater utilizes a separate combustion chamber and flue gas recirculation to reduce combustion chamber temperatures to 1,400F, thereby minimizing the impact of radiant heat transfer to the process coil.

Coil configurations and metallurgy are selected based on each customers’ process requirements. Sigma Thermal has extensive experience in process coil design for multi-phase fluids, viscous hydrocarbons, suspended solids, and various gaseous mixtures. We also utilize a highly accurate row by row sizing method, which allows us to accurately predict and control heat flux and film temperatures on each individual row of tubes.