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

Alkabie, H. S.; Andrews, Gordon E.

doi:10.1115/89-gt-322

Cited by 14 publications

(11 citation statements)

References 10 publications

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“…In order to characterize the Company DLE radial swirler, a derived geometrical swirl number S g [4,6] is employed to evaluate the strength of the rotational flow regime provided by the stabilizer. It can be used as a design tool to calculate specific designs of the radial swirler and combustion chamber.…”

Section: Swirl Numbermentioning

confidence: 99%

“…The investigation carried out by Andrews, Alkabie and co-workers [4][5][6][9][10][11][12][13][14][15][16] demonstrated that with more fuel holes located in the upstream region in the passages of the swirler and other stabilizing mechanisms, an improvement in the mixing process could be achieved. In this way more fuel-air uniformity could be achieved to eliminate any local rich zone that may cause a rise in local reaction temperature and hence more thermal NO x emission via the Zeldovich mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…The NO x level exhibited was in the range of 1-3 ppmv (corrected to 15% O 2 ) using the atmospheric rig facility [4,10]. The present work adopted a similar approach to achieve rapid mixing and stability.…”

Section: Introductionmentioning

confidence: 99%

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Design methods of the ABB Alstom Power gas turbine dry low emission combustion system

Alkabie¹

2000

Proceedings of the Institution of Mechanical Engineers, Part A:

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This paper describes the conceptual design and aerothermal approach of the ABB ALSTOM POWER UK Limited (ABB ALSTOM POWER) dry low emission (DLE) combustion system directed towards all current and future power ranges. A set of parameters was employed as a common criterion to design the company's combustion system across the product range. The parameters made it possible to scale the combustion system to operate at any required firing temperature without the penalty of achieving the low emission targets. The logic and sensible air mass mapping and testing management based on a basic knowledge of the aerothermodynamics of the combustion system and its integral parts produced reliable operation and engine results.The combustion system aerothermodynamic design considers the constraints of maintaining combustor specifications while introducing a reliable ultra-low NO x concept with minimal structural change to engine design. Furthermore, the ignition loop, piloting and stability margins were issues continuously assessed through a defined application programme to examine their impact on engine operability at various load conditions. A main radial swirler injector is utilized for both gas and liquid to produce a fuel lean mixture for combustion at full-load operating conditions, while a pilot fuel injector guarantees a local fuel-rich zone to sustain stability at low power conditions. The carefully planned switch-over between the pilot and main swirler provides smooth operation and low emission across the load range conditions. The company combustion system relies upon the principle of aerodynamic variable mixing with a single vortex generator burner. The partial premixing process takes place at the radial inflow swirler slots before the fuel-air mixture is introduced into a prechamber and thereafter into the combustion chamber. For vane passage injection the liquid fuel atomization should be at an optimum and the vane passage and prechamber length set to provide the vaporization period. The impingement cooling scheme aided by a thin layer of thermal barrier coating (TBC) achieved an excellent combustor wall temperature at all operating conditions and across the DLE engines product range. The scheme made it possible to direct a large amount of air towards the swirler to achieve the lean premix combustion. Substantial CO emission reduction at part load was achieved by variable guide vanes (VGV) modulation for the single-shaft engines. This action inhibits NO formation without slowing the CO oxidation process to a frozen condition. The variable mixing regime approach and accurate air management has demonstrated an ultra-low NO x emission of 12-15 and 32-35 ppmv (corrected to 15% O 2 ) at the full-load condition while operating on gas and distillate-2 fuel respectively. Moreover, the system exhibited low CO and dynamics oscillation capability for both gas and liquid fuel operation.At the present time, the one-dimensional analysis has been proved to be a reliable tool for combustion system designers to produce a preliminary ...

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Section: Swirl Numbermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Design methods of the ABB Alstom Power gas turbine dry low emission combustion system

Alkabie¹

2000

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…This type of impingement cooled combustor design with most of the combustion air entering the head of the combustor is ideally suited to lean burning low NOx combustors and to high temperature rise combustors (Alkabie and Andrews, 1989). The type of combustor design envisaged is shown in Fig.l, where a pressure loss of 0.5% of the impingement wall and 3% of the combustor liner are typical pressure loss values.…”

Section: Nomenclaturementioning

confidence: 99%

Full Coverage Impingement Heat Transfer at High Temperatures

Husain

Andrews

1990

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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Transient cooling techniques were developed for the direct simultaneous measurement of full coverage multi-jet impingement heat transfer coefficient and cooling effectiveness under high temperature combustion convective wall heating conditions. A step change in the impingement coolant flow rate was made and the change in temperature recorded as a function of time, from which the heat transfer coefficient was calculated. A comparison between steady state and transient techniques was also made on a conventional low temperature electrically heated test facility and good agreement was found. There was reasonable agreement between the high temperature heat transfer coefficients and the low temperature results, using similar transient cooling techniques. There was little influence of the coolant to wall temperature ratio on the impingement heat transfer coefficient or the cooling effectiveness obtained from the high temperature test rig. The transient technique was used to study the influence of crossflow in the impingement gap on both the cooling effectiveness and the heat transfer coefficient for a range of low pressure loss impingement walls with an X/D of 1.9–11.

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“…This method of fuel injection was found to have a much better weak extinction but worse NOx emissions than for fuel injection in the vane passages or at the swirler periphery. These latter two fuel injection techniques have been shown to result in ultra low NOx characteristics whilst achieving a weak extinction much better than for premixed combustion (Alkabie and Andrews, 1988, 1989, 1990. The aim of the present work was to investigate whether central fuel injection could achieve lower NOx emissions, closer to those of the vane passage or peripheral fuel injection, without the relative poor flame stability of these modes of fuel injection.…”

Section: Introductionmentioning

confidence: 98%

Reduced NOx Emissions Using Low Radial Swirler Vane Angles

Alkabie

Andrews

1991

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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The influence of vane angle and hence swirl number of a radial swirler on the weak extinction, combustion inefficiency and NOx emissions was investigated at lean gas turbine combustor primary zone conditions. A 140mm diameter atmospheric pressure low NOx combustor primary zone was developed with a Mach number simulation of 30% and 43% of the combustor air flow into the primary zone through a curved blade radial swirler. The range of radial swirler vane angles was 0–60 degrees and central radially outward fuel injection was used throughout with a 600K inlet temperature. For zero vane angle radially inward jets were formed that impinged and generated a strong outer recirculation. This was found to have much lower NOx characteristics compared with a 45 degree swirler at the same pressure loss. However, the lean stability and combustion efficiency in the near weak extinction region was not as good. With swirl the central recirculation zone enhanced the combustion efficiency. For all the swirl vane angles there was little difference in combustion inefficiency between the swirlers. However, the NOx emissions were reduced at the lowest swirl angles and vane angles in the range 20–30 degrees were considered to be the optimum for central injection. NOx emissions for central injection as low as 5ppm at 15% oxygen and 1 bar were demonstrated for zero swirl and 20 degree swirler vane angle. This would scale to well under 25 ppm at pressure for all current industrial gas turbines.

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

Cited by 14 publications

References 10 publications

Design methods of the ABB Alstom Power gas turbine dry low emission combustion system

Design methods of the ABB Alstom Power gas turbine dry low emission combustion system

Full Coverage Impingement Heat Transfer at High Temperatures

Reduced NOx Emissions Using Low Radial Swirler Vane Angles

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