Towards an understanding of hydrogenenriched natural gas combustion inindustrial gas turbinesJENNY LARFELDT - SIEMENS INDUSTRIAL TURBOMACHINERY AB, FINSPONG

ELNA HEIMDAL NILSSON - COMBUSTION PHYSICS, LUND UNIVERISTY

Outline

1. Hydrogen as a fuel

2. Full scale experiments at Siemens,Finspong

3. Modeling of combustion chemistry

4. Moving towards an increasedunderstanding: the way ahead

Hydrogen (H2) as a fuel

• Future energy carrier that can buffer energyproduction capacity and energy need

• Waste gas in some industries

• Can be fed into natural gas grid

• ”Zero emission”

• Technical challenges: diffusivity, volume

H2 combustion:Effect on combustion properties

• Increased flame speed – improved flamestability

• Increased flame temperature – risk of NOxproduction

• Decreased ignition delay time – flashback

• Increased flammability range

• High energy content

H2 combustion:A chemical perspective

• Overall reaction: 2H2 + O2 → 2H2O

• Intermediate steps:

H2 + OH → H + H2O

H2 + O → H + OH

H + O2 → OH + O

H + HO2 → H2 + O2

→ OH + OH

Significant radical production – chain branching!

H2 combustion:Gas turbines

• Gas turbines commonly fueled by natural gas

• H2 cofiring increase flame speed

• Risk of flash-back

Full scale experiment:Testing in a Siemens gas turbine

• Purpose: find the maximum concentration of hydrogen in natural gasthat Siemens gas turbines SGT-700 and SGT-800 can handle withstandard combustion system and increase our knowledge on what issetting this limit

• Testing: a standard SGT-700 in Finspong with so called “single burnerfeed” of natural gas was operated with increasing amount of hydrogen

• Parameters evaluated: emissions, flame position, combustiondynamics and temperatures

• Funding: Swedish Energy Agency via the SGC AB, Siemens and Infraserv GmbH & Co.Höchst KG in Frankfurt am Main

• Report: Co-firing with hydrogen in Siemens industrial gas turbines, Mats Andersson, JennyLarfeldt and Anders Larsson, SGC rapport 2013:256

Restricted © Siemens Industrial Turbomachinery AB 2013 All rights reserved.

Results 1(3): Stable operation at near 40 % byvolume H2 demonstrated

Based on the test Siemens

has increased the allowed

hydrogen content in the

standard SGT-700 and SGT-

800 today to 15 vol-% H2.

Jenny LarfeldtSiemens Industrial Turbomachinery AB

Restricted © Siemens Industrial Turbomachinery AB 2013 All rights reserved.

Results 2(3): Tendency to flame shifting observedand our understanding has increased

0vol% H2 30vol% H2 60vol% H2 100vol% H2

Atmospheric

combustion

test rig

0% pilot

0vol% H2 20vol% H2 32vol% H2

In SGT-700

engine 30 MW

load

6% pilot

Jenny LarfeldtSiemens Industrial Turbomachinery AB

Restricted © Siemens Industrial Turbomachinery AB 2013 All rights reserved.

Results 3(3): The stability of the feeding system wasnot as accurate as desired… Improvements neededfor higher hydrogen contents

Jenny LarfeldtSiemens Industrial Turbomachinery AB

Chemical kinetics modeling:Motivation

• Detailed models increase fundamentalunderstanding but are computationallyexpensive

• Reduced models can be used forComputational Fluid Dynamics simulations

• A ”cheap” way to investigate a wide range ofparameters

Chemical kinetics modeling:Aim

Develop a tool based on combustion simulations to enableprediction of flame speeds of gas mixture relevant for gasturbines

• This tool will enable optimization of the operation of thegas turbines at different fuel compositions, with respect tonatural gas composition and hydrogen content

• It is impossible to investigate a large enough parameterset using full scale experiments

• Up to 60% hydrogen

• Pressures up to 20 bar

Chemical kinetics modeling:Preliminary results

• text

GRI mechanismUsed forsimulation oflaminar flamespeed

Chemical kinetics modeling:Further work

• Evaluation of detailed kinetic models to use asbenchmark (laboratory flames)

• Evaluation of existing reduced models (laboratory flames)

• Development of understanding of high pressurechemistry; what is required for a model to work for highpressures

• Development of reduced kinetic model

• Use reduced model for simulation of gas turbines

Future work

• Laboratory studies of flames, from laminar toturbulent, at pressures up to 20 bar

• Development of reduced chemical kineticsmechanism suitable for gas turbineconditions

• CFD modeling of gas turbines

• Improved full scale experiments

Thank you for your attention!