Application of a Novel Low NOx Combustion System to an Oil Field Steam Generator

Abstract

For several years low NOx operation of oil field steam generators has been accomplished through the use of flue gas recirculation (FGR). FGR technologies can be easily retrofitted to existing steamers burning natural gas to achieve NOx emission levels between 25–30 ppmvd @ 3% O2. While fairly cost effective to install, FGR systems further incur an increase in operating costs due to the additional fan horsepower required for the flue gas supply. As permissible stack emission levels continue to decrease, alternative technologies must emerge which address the non-FGR NOx formation rate without risking loss of burner stability or unreasonably increasing combustion system operating costs. North American Mfg. has combined its own patented ultra low NOx burner and control technology with Shell Oil's patented combustion process and installed the system on an oil field steam generator. The resulting combustion system produces 13 –17 ppmvd @ 3% O2 of NOx while firing natural gas without the use of FGR. Further development of the technology may provide NOx emission performance approaching selective catalytic reduction (SCR) levels at a greatly reduced cost. Introduction Thermally enhanced oil recovery techniques have been used for decades as a means of increasing the removal efficiency of heavy crude oil from reservoirs. The objective of this process is to inject a steam-water mixture into the oil bearing strata. This mixture contains a considerable amount of heat that can be transferred to the oil sands to heat, thin, and provide added volume to displace viscous crude. The crude oil is then flooded to production wells where it can be pumped to the surface by conventional means. The use of thermally enhanced oil recovery is now widespread, with steamer units operating around the world. Enhanced oil recovery in the southern California region began in the early 1960's and its use has increased to its peak in the early 1980's.