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

2012 ◽  
Author(s):  
Mohamed A. Altaher ◽  
Hu Li ◽  
Gordon E. Andrews
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Liquid Fuels ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Combustion ◽  
Swirl Combustor ◽  
Low Nox Combustion ◽  
Natural Gas Combustion

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.

Effects of Swirler Configurations on Flow Structures and Combustion Characteristics

2004 ◽  
Author(s):  
Guoqiang Li ◽  
Ephraim J. Gutmark
Keyword(s):  
Fuel Injection ◽  
Vortex Breakdown ◽  
Swirling Flow ◽  
Combustion Characteristics ◽  
Pollutant Emissions ◽  
Flow Structures ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Atmospheric Conditions ◽  
Fuel Injector

Modern gas turbine combustion technologies are driven by stringent regulations on pollutant emissions such as CO and NOx. A combustion system of multiple swirlers coupled with distributed fuel injection was studied as a new concept for reducing NOx emissions by application of Lean Direct Injection (LDI) combustion. The present paper investigates the effects of swirler configurations on the flow structures in isothermal flow and combustion cases using a multiple-swirlers fuel injector at atmospheric conditions. The swirling flow field within the combustor was characterized by a central recirculation zone formed after vortex breakdown. The differences between the tangential and axial velocity profiles, the shape of the recirculation zones and the turbulence intensity distribution for the different fuel injector configurations impacted the flame structure, the temperature distribution and the emission characteristics both for gaseous and liquid fuels. Co-swirling configuration was shown to have the lowest NOx emission level compared with the counter-swirling ones for both types of fuels with lower inlet temperature. In contrast to this, the swirl configuration had less effect on the combustion characteristics in the case of gaseous fuel with high air inlet temperature. The differences in NOx emissions were shown to be closely related to the Damkohler number or the degree to which the flame resembled well-mixed combustion, which is the foundation for LDI combustion.

Modeling of Post-Combustion in an Electric Arc Furnace

2017 ◽  
Author(s):  
Guangwu Tang ◽  
Wenjie Liu ◽  
Armin K. Silaen ◽  
Chenn Q. Zhou
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Arc Furnace ◽  
Cfd Model ◽  
Gas Combustion ◽  
Heat Transfer Efficiency ◽  
Operation Process ◽  
Natural Gas Combustion

In the electric arc furnace (EAF) process, post-combustion (PC) technology is applied to utilize the chemical energy in the CO and H2 evolving off of the steel bath through the injection of oxygen. PC technology also improves productivity and helps to optimize the benefits of oxygen and fuel injection. In order to obtain insight on the characteristics of PC inside an electric-arc furnace, a computational fluid dynamics (CFD) model was developed to investigate the combustion characteristics in the EAF with a flat bath assumption. The natural gas is used in EAF operation process, however, the natural gas combustion is not included in this CFD model to simplify the model towards examining the effect of CO post-combustion. The eddy-dissipation (ED) was employed to model the combustion reactions. The CFD model was validated with literature on the flow velocity and temperature profiles. The effects of CO post-combustion and the oxygen mass flow rate on the furnace heat transfer efficiency in the EAF were studied.

Nox emission control in gas turbines for combined cycle gas turbine plant

1997 ◽  
Vol 211 (1) ◽  
pp. 43-52 ◽  
Author(s):  
M J Moore
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Catalytic Reduction ◽  
Water Injection ◽  
Emission Control ◽  
Combined Cycle ◽  
Liquid Fuels ◽  
Gas Combustion ◽  
Natural Gas Combustion

The increase, in recent years, in the size and efficiency of gas turbines burning natural gas in combined cycle has occurred against a background of tightening environmental legislation on the emission of nitrogen oxides. The higher turbine entry temperatures required for efficiency improvement tend to increase NOx production. First-generation emission control systems involved water injection and catalytic reduction and were relatively expensive to operate. Dry low-NOx combustion systems have therefore been developed but demand more primary air for combustion. This gives added incentive to the reduction of air requirements for cooling the combustor and turbine blading. This paper reviews the various approaches adopted by the main gas turbine manufacturers which are achieving very low levels of NOx emission from natural gas combustion. Further developments, however, are necessary for liquid fuels.

scholarly journals Ultra Low NOx Emissions for Gas and Liquid Fuels Using Radial Swirlers

1989 ◽  
Author(s):  
H. S. Alkabie ◽  
G. E. Andrews
Keyword(s):  
Gas Turbines ◽  
Fuel Injection ◽  
Air Flow ◽  
Combustion Efficiency ◽  
Liquid Fuels ◽  
Inlet Temperature ◽  
Flame Stability ◽  
Nox Emissions ◽  
Gas Oil ◽  
Industrial Gas Turbines

Curved blade radial swirlers using all the primary air were investigated with applications to lean burning gas turbine combustor primary zones with low NOx emissions. Two modes of fuel injection were compared, central and radial swirler pássage injection for gaseous and liquid fuels. Both fuel systems produced low NOx emissions but the upstream mixing in the swirler passages resulted in ultra low NOx emissions. A 140mm diameter atmospheric pressure combustor was used with 43% of the combustor air flow into the primary zone through the radial swirler. Radial gas composition measurements at various axial distances were made and these showed that the flame stability and NOx emissions were controlled by differences in local mixing at the base of the swirling shear layer downstream of the swirler outlet. For radial passage fuel injection it was found that a very high combustion efficiency was obtained for both propane and liquid fuels at 400K and 600K inlet temperatures. The flame stability, although worse than for central fuel injection was considerably better than for a premixed system. The NOx emissions at one bar pressure and 600K inlet temperature, compatible with a high combustion efficiency, for propane and kerosene were 3 and 6 ppm at 15% oxygen. For Gas Oil the NOx emissions were higher, but were still very low at 12ppm. Assuming a square root dependence of NOx on pressure these results indicate that NOx emissions of 48ppm for Gas Oil and less than 12ppm for gaseous fuels could be achieved at 16 bar pressure, which is typical of recent industrial gas turbines. High air flow radial swirlers with passage fuel injection have the potential for a dry solution to the NOx emissions regulations.

Radial Swirlers With Peripheral Fuel Injection for Ultra-Low NOx Emissions

1990 ◽  
Author(s):  
H. S. Al Kabie ◽  
G. E. Andrews
Keyword(s):  
Natural Gas ◽  
Recirculation Zone ◽  
Fuel Injection ◽  
Air Flow ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Gas Oil ◽  
Primary Zone ◽  
Wall Injection

A 76mm outlet diameter radial swirler with a dump expansion into a 140mm diameter combustor was investigated with a simulated 43% primary zone air flow at a 600K inlet temperature and one bar pressure. Two modes of peripheral fuel injection were investigated: at the 76mm swirler outlet and at the 140mm combustor wall just downstream of the swirler. This 140mm wall injector resulted in fuel injection into the swirler expansion outer recirculation zone. It was shown that the 140mm wall injection gave much higher NOx emissions than for the 76mm swirler outlet injector. These results were compared with other methods of fuel injection and the 76mm peripheral injection was shown to have superior NOx emissions than vane passage injection for all fuels except gas oil. Ultra low NOx emissions of 1ppm with 20 ppm CO, both at 15% oxygen, were demonstrated for propane and natural gas.

Influence of Fuel Injection Location in a Small Radial Swirler Low NOx Combustor for Micro Gas Turbine Applications

2019 ◽  
Author(s):  
Gordon E. Andrews ◽  
Su Kim
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Micro Gas Turbine ◽  
Optimum Position ◽  
Pilot Fuel ◽  
Wall Injection ◽  
Injection Location

Abstract The influence of fuel injection location in a low NOx (1) micro-gas turbine [MGT] in the ∼50kWe (kW electric) size range was investigated, for NG and propane, to extend the power turn down using a pilot fuel injector. The low NOx main combustor (1) was a radial swirler with vane passage fuel injection and had ultra-low NOx emissions of 3ppm at 15% O2 at 1800K with natural gas, NG at a combustion intensity of 11.2 MW/m2bara (MW thermal). This was a 40mm diameter outlet eight bladed radial swirler in a 76mm diameter combustor, investigated at 740K air temperature at atmospheric pressure. However, power turn down was poor and the present work was undertaken to determine the optimum position of pilot fuel injection that would enable leaner mixtures to be burned at low powers. Central injection of pilot fuel was investigated using 8 radial outward holes. This was compared with pilot fuel injected at the 76mm wall just downstream of the 40mm swirler outlet. It was show that the central injection pilot was poor with a worse weak extinction than for radial passage fuel injection. The 76mm outlet wall injection was much more successful as a pilot fuel location and had a weak extinction of 0.18Ø compared with 0.34Ø for vane passage fuel injection. NOx emissions were higher for wall fuel injection, but were still relatively low at 16ppm at 15% oxygen for natural gas. This indicates that wall fuel injection could be combined with vane passage fuel injection to improve the micro-gas turbine low NOx performance across the power range.

Experimental Study on Low Load Operation Range Extension by Autothermal On-Board Syngas Generation

2018 ◽  
Author(s):  
Max H. Baumgärtner ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Mass Flow ◽  
Power Output ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
Nox Emissions ◽  
Gas Combustion ◽  
Low Load ◽  
Natural Gas Combustion

Volatile renewable energy sources induce power supply fluctuations. These need to be compensated by flexible conventional power plants. Gas turbines in combined cycle power plants adjust the power output quickly but their turn-down ratio is limited by the slow reaction kinetics which lead to CO and unburned hydrocarbon (UHC) emissions. To extend the turn-down ratio, part of the fuel can be converted to syngas, which exhibits a higher reactivity. By an increasing fraction of syngas in the fuel, the reactivity of the mixture is increased and total fuel mass-flow and the power output can be reduced. An Autothermal On-board Syngas Generator in combination with two different burner concepts for natural gas/syngas mixtures was presented in a previous study [1]. The study at hand shows a mass-flow variation of the reforming process with mass-flows which allow for pure syngas combustion and further improvements of the two burner concepts which result in a more application-oriented operation. The first of the two burner concepts comprises a generic swirl stage with a central lance for syngas injection. Syngas is injected with swirl to avoid a negative impact on the total swirl intensity and non-swirled. The second concept includes a central swirl stage with an outer ring of jets. For this burner, syngas is injected in both stages to avoid NOx emissions from the swirl stage. Increased NOx emissions produced by natural gas combustion of the swirl pilot was reported in last year’s paper. For both burners, combustion performance is analyzed by OH*-chemiluminescence and gaseous emissions. The lowest possible adiabatic flame temperature without a significant increase of CO emissions was 170 K – 210 K lower for the syngas compared to low load pure natural gas combustion. This corresponds to a decrease of 15–20 % in terms of thermal power.

Liquid Fuelled Low NOx Radial Swirlers With Central Pilot Combustion

2007 ◽  
Author(s):  
Gordon E. Andrews ◽  
M. N. Kim ◽  
Mike C. Mkpadi ◽  
Sheriff A. Akande
Keyword(s):  
Natural Gas ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Liquid Fuels ◽  
Lean Combustion ◽  
Auto Ignition ◽  
Primary Zone ◽  
Low Nox Combustion ◽  
The Difference ◽  
Injection Location

Radial swirlers have proved effective in achieving low NOx using natural gas and this work investigates their use with kerosene with and without a central NG pilot. Two kerosene fuel injection locations were compared: at the inlet to the vane passages on the centreline with co-flow injection and 20mm downstream of the 76mm diameter swirler exit through the wall of a 76mm diameter 40mm long discharge duct. Flash back and auto ignition problems cannot occur with the downstream wall fuel injection location. All configurations were also tested with natural gas so that the difference in emissions due to the change from gas to liquid fuel could be established. The results show that ultra low NOx emissions can be achieved for kerosene with vane passage injection and that the use of a central pilot increases the NOx but improves the flame stability and power turndown. However, on liquid fuels the pilot to main flame propagation was not as good as when natural gas was used as the main fuel. Liquid fuel injection at the radial swirler wall outlet was effective but had slightly higher NOx for lean mixtures and worse HC and CO emissions. However, for richer primary zone mixtures the NOx was lower than for vane passage injection and this indicated that rich/lean combustion was occurring, without the uniform mixing and low NOx combustion that occurred with natural gas injection at this location.

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