A common problem with oil-water separation in horizontal heater treaters processing heavy oil is thermal deformation and failure of the heater fire tube. Several factors contribute to the cause of the failure including presence of polymer in the water used for oil recovery, solids content in the oil, and design of the heater treater tank and controls. A key aspect of the tube failure is related to the internal heat transfer from the burner to the fire tube wall. Heat flux typically is concentrated around the burner flame with a resulting hot zone that forms a coking, insulating layer on the outside of the tube. Eventually the fire tube overheats and fails either by collapse or rupture.
Distributed flux burners have been installed to prevent the concentrated hot zone of the tube wall by improving temperature uniformity over the length of the tube. The distributed flux burner utilizes premixed surface stabilized combustion to extend the flame zone over the length of the fire tube, thereby reducing peak wall temperatures while increasing the effective heat transfer to the emulsion. The burner consists of a porous cylindrical ceramic matrix which provides infra-red radiation heat transfer to the fire tube wall to help maximize heat flux uniformity. The burner has been in commercial use for asphalt tank heating and fragile fluid heating for many years and recently has proven to be ideal for effective heating of heavy oil in heater treaters.
As a continuation from results presented in SPE-170172-MS in June 2014, we review recent field experience in heater treaters processing heavy oil at various locations. Improvements in life of the fire tube, throughput of the emulsion and sales oil, and thermal efficiency relative to conventional burners are presented. This paper also describes new specifications and criteria for proper sizing and operation of the distributed flux burner for retrofit of heater treaters.