Efficiency improvement and emissions reduction in refinery boilers and furnaces

This paper presents the fundamentals and results of the application of a novel technological approach called 'Controlled Furnace' to the combustion efficiency improvement and emissions reduction (CO2, CO, NOx) in refinery boilers and furnaces. Controlled Furnace technology relies on the adequate closed-loop control of local combustion conditions, by means of advanced monitoring and optimised regulation of combustion units. These Controlled Furnace conditions avoid not desired combustion imbalances, and make possible the application, with maximum safety and profitability, of efficiency improvement and emissions controlling strategies. Controlled Furnace technology has proved to be an advantageous alternative and an essential complement in case of the previous application of larger revamps to the unit combustion systems. This novel technology, qualified as Best Available Technique at the European IPPC Directive, has been applied to more than 30 combustion units, including large utility boilers for power generation. Main results obtained in the particular application of this technology to the CH1-B crude oil furnace of CEPSA-La Rabida Refinery are: - Improvement of unit combustion efficiency resulting in fuel consumption savings above 5% (with equivalent CO2 and SOx emission reductions). - Simultaneous reductions in total NOx emission (t/h) of up to 50%. - Control of unburnt fuel and CO emissions, resulting in negligible CO levels even for the most stringent low excess air scenarios (optimised excess O2 around 2%). - A clear improvement in combustion control making feasible higher unit reliability, reductions in maintenance costs and safer operation. Besides efficiency increase, those important emission reductions achieved through the application of Controlled Furnace strategies, could make feasible the authorisation of new projects involving extension of facilities or increase in capacity, even in the case of pollution saturated zones.