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Combustion Systems

Del G u asta R o b erto

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Combustion Systems

Introduction and Overview of Products DLN-1 Combustion Systems

Description and Operating Modes

Controls and Accessories

Emissions Performance

Fleet Experience

Appendix - Combustion Physics Flame & Combustor Stability

Emissions Mechanisms

Emissions Control Methods

Contents

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Combustion Systems

What Is Combustion ?

A RAPID EXOTHEMIC PROCESS WHICH

WILL DELIVER HIGH TEMPERATURE

PRODUCTS

What Is A Flame ?

THE ZONE WHICH SEPARATES THE

REACTANTS AND THE PRODUCTS, ANDWHERE THE TEMPERATURE RISE OCCURS

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Combustion Systems

Flame Categorization

Flames

Premixed Flame Diffusion Flame

Laminar Turbulent Laminar Turbulent

- Spark Ignition Engine - Candle

- Oxy-Acetylene Torch - Gas Range

- DLN GT Combustor - Home Heating Furnace

- Conventional GT Comb.

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Combustion Systems

Some Definitions

Stoichiometric Flame

Chemically Correct Amounts of Reactants (Fuel

and Air) Combine to Form Products With No

Reactants Left Over Equivalence Ratio ()

Ratio of Actual f/a Ratio to Stoichiometric f/a

< 1 : Flame With Excess Air

= 1 : Stoichiometric Flame

> 1 : Flame With Excess Fuel

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Combustion Systems

Flammability Limits

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Combustion Systems

Flame Descriptions

Diffusion Flame

A Region of 100% Fuel Is Surrounded By A Region

of 100% Air. The Air And Fuel Diffuse Together

At The Boundary With Reaction Occurring In The

Diffusion Zone At Or Near = 1 .

Premixed Flame

Air And Fuel Are Completely Mixed Upstream OfThe Flame Zone. The Reaction Occurs At The

Mixture .

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Combustion Systems

Diffusion Flame Stability

Overall Reaction Rate Governed By The

Fuel/Air Mass Diffusion Process

Turbulent Wrinkling Of The Diffusion Zone

Increases Area And So Reaction Rate

Problem: Convective Rate Exceeds Reaction

Rate Leading To Flame ExtinctionSolution: Provide A Low Velocity Sheltered

Zone For Reaction To Occur

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Combustion Systems

Premixed Flame Stability

Overall Reaction Rate Governed By Thermal

Diffusion At The Flame Front

Reaction Rate Can Be Visualized As Flame

Front Propagation Speed In A Mixture

Problem: Convective Rate Exceeds Flame

Speed Pushing The Flame Front DownstreamSolution: Provide Stable Hot Recirculation

Zones To Act As Continuous Ignition Sources

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Combustion Systems

NOx Production Rate

GT11657B .ppt

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Combustion Systems

Diffusion Vs. Premixed

Diffusion

Very Robust Stable

Flame

Typically OperableOver a 2000F Temp.

Rise Range

High NOx Emissions

Without Diluent

Low CO Emissions

Premixed

Very Narrow

Operating Window

Typically OperableOver a 200-300F

Temp. Rise Range

Can Achieve Very

Low NOx EmissionsWithout Diluent

Low CO Emissions

Can Be Difficult

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Combustion Systems

Staged Combustors

Plane ofDilution Holes

DilutionAir

Plane of Dilution HolesAir-Staged

Fuel

Fuel

PrimaryAir

SecondaryAir

InletAir

ControlValve

DilutionZone Air

PrimaryZone Air

Fuel-StagedControl Valve

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Combustion Systems

DLN Aerothermal Design - a Four Sided Box

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Combustion Systems

Dry Low NOx Combustor

PrimaryFuel Nozzles

(6)

Lean andPremixing

Primary Zone

Secondary

Fuel Nozzle(1)

End Cover

Venturi

Dilution ZoneSecondary Zone

Centerbody

Outer Casing Flow Sleeve

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Combustion Systems

Fuel-Staged Dry Low NOx Operating Modes

Primary Operation Ignition to 20% Load

Lean-Lean Operation 20 to 50% Load

Second-Stage Burning Transient During Transfer to Premixed

Premixed Operation 50 to 100% Load

Fuel100%

Fuel100%

Fuel70%

Fuel83%

17%

30%

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Combustion Systems

Performance Evaluation Services Combined Cycle Performance Seminar

GT21897A .ppt

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Combustion Systems

Dry Low NOx Gas Fuel System

SRV

GCV

GSVP

S

GTV

Speed/Ratio Valve

Gas Control

Gas SplitterPrimary

Secondary

Gas Transfer

To Purge System

T

GTV

SRV GCV

P

S

GSV

GSV

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Combustion Systems

Typical DLN-1 Fuel Gas Split Schedule

Lean-Lean

Secondary Mode

Premix Mode

202019501600 F

11041066871 C

CombustionReference

Temperature

100

90

0

10

20

30

40

5060

70

80

%PrimaryFue

lSplit

Primary Mode

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Combustion Systems

MS9001E Emissions

Natural Gas Fuel100

90

80

70

60

50

40

30

20

10

0

350

300

250

200

150

100

50

0

ISO Ambient Condit ions

NOx

CO

0 10 20 30 40 50 60 70 80 90 100

CO

(ppmvd)

% Gas Turbine Load

NOx@

15%

O2

( PPm

vd

)