Horizontal heater treaters are commonly used to separate oil/water emulsions from enhanced oil recovery in heavy oil reservoirs. Conventional burners used in these heaters can cause hot spots that result in coking of the viscous emulsion on the outer surface of the firetube. This coking layer acts as an insulator and results in high tube wall temperatures, leading to an early failure of the firetube. The problem may be exacerbated when using polymer injection in the recovery fluid due to increased viscosity of the fluid and thermal breakdown of the polymer which creates a thicker insulating layer along the firetube.
To prevent this coking and tube-failure process, an all radiant, distributed flux burner distributes the heat over a much larger area with a very uniform flame shape compared to a conventional burner. The distributed flux burner has a porous ceramic cylindrical surface that provides surface-stabilized premixed combustion, such that combustion characteristics at every point along the cylindrical burner surface are nearly identical. This significantly reduces peak heat flux surrounding the combustion zone, reducing likelihood of hot spots and potential for coking compared to conventional burners. At the same time, more heat is distributed further down the length of the firetube, increasing heat transfer in the rear section of the heater and improving its overall performance and efficiency. Firetube life is increased because of the lower peak wall temperatures, and because less heat is needed to achieve the required process throughput and water cut.
In this follow up paper to SPE 166261-MS presented in October 2013, key operating data is provided from a recent burner retrofit of a horizontal heater treater at the Canadian oil sands field in northern Canada. The retrofit was completed in a two day effort. Operating data presented includes heater firing rate and tube wall temperatures over time. Based on the recent field data, thermal analysis, and measurements made in lab tests, the distributed flux burner is compared to a conventional burner with respect to thermal efficiency, process throughput, oil/water separation performance, and tube wall temperatures.