Methods relating to downstream fuel and air injection in gas turbines

Patent metadata

Field	Value
Publication number	US-9482434-B2
Application number	US-201313837186-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 15, 2013
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

A method for use in a gas turbine engine. The method includes the steps of: configuring a downstream injection system within the interior flowpath that includes two injection stages, a first stage and a second stage, wherein the first stage and the second stage are each axially spaced from the other; and circumferentially positioning the injectors of the first stage and the second stage based on: a) a characteristic of an anticipated combustion flow occurring just upstream of the first stage during a mode of operation; and b) the characteristic of an anticipated combustion flow just downstream of the second stage given an anticipated effect of the air and fuel injection from the first stage and the second stage.

First claim

We claim:

1. A method for use in a gas turbine engine that includes: a combustor coupled to a turbine that together define an interior flowpath, the interior flowpath extending rearward about a longitudinal axis from a primary air and fuel injection system positioned at a forward end of the combustor, through an interface at which the combustor connects to the turbine, and through at least a row of stator blades in the turbine, the method including the steps of:
configuring a downstream injection system within the interior flowpath that includes two injection stages, a first stage and a second stage, wherein the first stage and the second stage are each axially spaced along the longitudinal axis such that the first stage comprises an axial position that is aft of the primary air and fuel injection system and the second stage comprising an axial position that is aft of the first stage, wherein each of the first stage and the second stage include a plurality of injectors, each injector configured to inject air and fuel into a combustion flow through the interior flowpath;
circumferentially positioning the injectors of the first stage and the second stage; and
injecting air and fuel from each of the injectors of the first stage and the second stage during operation;
wherein immediately aft of the primary air and fuel injection system, the interior flowpath includes a primary combustion zone defined by a surrounding liner and, immediately aft of the liner, the interior flowpath includes a transition zone defined by a surrounding transition piece;
wherein the transition piece is configured to fluidly couple the primary combustion zone to an inlet of the turbine while transitioning a flow through the transition piece from an approximate cylindrical cross-sectional area of the liner to an annular cross-sectional area of the inlet of the turbine, the transition piece including an aft frame that forms the interface between the combustor and the inlet of the turbine;
wherein the first stage is positioned aft of a longitudinal midpoint of the interior flowpath within the combustor, and wherein the first stage is positioned within the transition zone; and
wherein the second stage of the downstream injection system is positioned within or aft of the aft frame.

2. The method of claim 1 , wherein the step of circumferential positioning the injectors of the first stage and the second stage is based on a characteristic of the combustion flow.

3. The method of claim 2 , wherein the characteristic comprises a reactant distribution; and
wherein the circumferential positioning the injectors is based upon making the reactant distribution more uniform in the combustion flow.

4. The method of claim 2 , wherein the characteristic comprises a temperature profile;
wherein the circumferential positioning the injectors is based upon making the temperature profile more uniform in the combustion flow.

5. The method of claim 2 , wherein the characteristic comprises a carbon monoxide (“CO”) distribution;
wherein the circumferential positioning the injectors is based upon making the CO distribution more uniform in the combustion flow.

6. The method of claim 2 , wherein the characteristic comprises an unburned hydrocarbon (“UHC”) distribution;
wherein the circumferential positioning the injectors is based upon making the UHC distribution more uniform in the combustion flow.

7. The method of claim 2 , wherein the characteristic comprises a NOx distribution;
wherein the circumferential positioning the injectors is based upon making the NOx distribution more uniform in the combustion flow.

8. The method of claim 2 , wherein the characteristic includes a cross-sectional distribution of a flow property within the combustion flow and wherein the circumferential positioning of the injectors of the first and the second stage is based on making the cross-sectional distribution of the flow property more uniform downstream of the second stage.

9. The gas turbine of claim 8 , wherein the flow property comprises at least two of the following: reactant distribution; temperature profile; CO distribution; UHC distribution; and NOx distribution.

10. The method of claim 2 , wherein each of the plurality of injectors at each of the first stage and the second stage are positioned on a common injection plane, each common injection plane aligned approximately perpendicular to the longitudinal axis of the interior flowpath;
wherein each of the first stage and the second stage comprise between 3 and 10 injectors; and
wherein the step of circumferentially positioning the injectors includes circumferentially staggering the injectors of the first stage relative to the injectors of the second stage.

11. The method of claim 2 , further comprising the steps of:
directing injectors of the first stage and the second stage so that, in operation, each injector injects air and fuel in a direction between +30° and −30° to a reference line that is perpendicular relative a predominant direction of the flow through the interior flowpath;
configuring the first stage to have between 3 and 6 injectors; and
configuring the second stage comprises between 5 and 10 injectors.

12. The method of claim 2 , wherein the primary air and fuel injection system and the first stage and the second stage of the downstream injection system are configured such that the following percentages of a total fuel supply are delivered to each during operation: between 60% and 75% delivered to the primary air and fuel injection system; between 20% and 30% delivered to the first stage; and between 2% and 10% delivered to the second stage;
wherein the primary air and fuel injection system and the first stage and the second stage of the downstream injection system are configured such that the following percentages of a total combustor air supply are delivered to each during operation: between 75% and 85% delivered to the primary air and fuel injection system; between 15% and 25% delivered to the first stage; and between 1% and 5% delivered to the second stage.

Assignees

• Gen Electric

Inventors

• Davis Jr Lewis Berkley
• Venkataraman Krishna Kumar
• Graham Kaitlin Marie

Classifications

• F23R3/286

  having fuel-air premixing devices (F23R3/30 takes precedence) · CPC title

• F23R3/346 Primary

  for staged combustion · CPC title