Co-Firing of Kerosene and Biodiesel With Natural Gas in a Low NOx Radial Swirl Combustor

Abstract

Co-firing of biodiesel with natural gas, using a low NOx gas turbine combustor was investigated and compared with the equivalent natural gas and kerosene co-firing. The work was carried out at atmospheric pressure with 600K air inlet temperature and used an 8 vane radial swirler. Well mixed natural gas combustion was achieved using radially inward gas fuel injection through the wall of the swirler outlet throat. The biofuel was injected centrally using an eight hole radial fuel injector. This central fuel injector location forms a good pilot flame for natural gas low NOx combustion and was the only fuel injection location that biodiesel combustion could be stabilised. This was because central fuel injection was into the hot recirculating gases on the centreline that is a feature of radial swirl lean low NOX combustion. The biodiesel results were compared with equivalent tests for kerosene as the central injection fuel. Co-firing was investigated with a low level of main natural gas combustion that was held constant and the equivalence ratio was increased using the central injection of biodiesel or kerosene. Operation on kerosene with no acoustic problem was demonstrated up to Ø = 0.95. Three natural gas initial equivalence ratios were investigated with co-firing of liquid fuels, Ø = 0.18, 0.22 and 0.34. A key benefit of operating with hotter premixed combustion with natural gas was that the overall Ø at which stable low CO and HC operation could be achieved with biodiesel was extended to leaner overall Ø. The NOx emissions in this co-firing mode were remarkably low for relatively rich overall mixtures, where conventional single fuel main injection on natural gas gave higher NOx emissions.

Mini Review of Current Combustion Research Progress of Biodiesel and Model Compounds for Gas Turbine Application

“…They explained that the stratification of fuel mixture can contribute to global inhomogeneous mixing, which results in high CO emission. Altaher et al 99 investigated the combustion characteristics of kerosene, biodiesel produced from waste cooking oil, and their blends with natural gas. Unlike the above studies, natural gas was injected at the swirler outlet plane, resulting in partially premixed natural gas with air.…”

Dual-Fuel Operation of Biodiesel and Natural Gas in a Model Gas Turbine Combustor

“…It is envisaged that the concept of dual-fuel operation can be extended to stationary combustion system, such as the gas turbine system for power generation purpose. In fact, there has been some researchers investigating the combustion performance of dual-fuel operation under continuous swirl flame conditions, such as those conducted in a gas turbine combustor equipped with a radial swirler operating with biodiesel/natural gas [12]. It has been demonstrated that biodiesel/natural gas combustion resulted in higher NO than neat natural gas by an average of 10 ppm at fuel-lean conditions.…”

“…In fact, there have been some researchers investigating the combustion performance of dual-fuel operation under continuous swirl flame conditions, such as those conducted in a gas turbine combustor equipped with a radial swirler operating with biodiesel/NG. 12 It has been demonstrated that biodiesel/NG combustion resulted in higher NO than neat NG by an average of 10 ppm at fuel-lean conditions. Further, the dual-fuel combustion also led to higher CO than NG by roughly 60 ppm when compared under the same equivalence ratio.…”

Effects of swirler vane angle on palm biodiesel/natural gas combustion in swirl-stabilised gas turbine combustor

“…Nonetheless, CO emissions from 22/58/20 glycerol/NG/hydrogen combustion were higher than for neat NG by 400 ppm at φ = 0.5. Altaher et al [15] also studied co-combustion characteristics of biodiesel and NG with model gas turbine swirl burners equipped with a radial swirler. Their study showed that biodiesel/NG combustion resulted in higher NO than for neat NG by averaging ppm from φ = 0.25 to 0.65.…”