Direct Fired Oxy-Fuel Combustor for sCO2 Power Cycles

Jacob Delimont, Ph.D.Nathan Andrews, Craig Nolen, Carolyn Day

Southwest Research Institute

Marc PortnoffLalit Chordia, Ph.D.Thar Energy L.L.C.

Wenting Sun, Ph.D., Tim Lieuwen, Ph.D.Ben Emmerson, Ph.D.

Georgia Tech

Subith Vasu, Ph.D. University of Central Florida

Paul Hsu, Ph.D., Sukesh Roy, Ph.D.Spectral Energies

Keith McManus, Ph.D.GE Global Research

Work supported by US DOE under DE-FE002401

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HEAT SOURCE

PRECOOLER

LOW TEMP RECUPERATOR

HIGH TEMPRECUPERATOR

EXPANDER

COMPRESSOR

RE-COMPRESSOR

P6 P7a P8

P1

P2

P3

P5

P7b

P7

P4

P4b

COOLING OUT COOLING IN

P4a

Outline

• Background• Project Objectives• Combustor Design• Test Loop Design• Future Work

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Why sCO2 Power Cycles?

• Offer +3 to +5 percentage points over supercritical steam for indirect fossil applications

• High fluid densities lead to compact turbomachinery

• Efficient cycles require significant recuperation

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Third Generation 300 MWe S-CO2 Layout from Gibba, Hejzlar, and Driscoll, MIT-GFR-037, 2006

ThermalInput

CoolerRecuperater

Turbine

Compressor

Pump

What is Direct Fired Oxy-Fuel Combustion?

• Oxygen + fuel + CO2• Designer can choose

the O2/CO2 ratio, unlike typical gas turbine combustors

• ASU to produce oxygen

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Water Removal

Excess CO2 Removal

O2

Fuel

CO2 from Recuperator

CO2 + Water

Direct Fired Oxy-Combustor

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Why Direct Fired Oxy-Fuel Combustion?

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HEAT SOURCE

PRECOOLER

LOW TEMP RECUPERATOR

HIGH TEMPRECUPERATOR

EXPANDER

COMPRESSOR

RE-COMPRESSOR

P6 P7a P8

P1

P2

P3

P5

P7b

P7

P4

P4b

COOLING OUT COOLING IN

P4a

• Capture 99% of carbon dioxide• Higher turbine inlet

temperatures possible• Limiting component is the

recuperator, not the heater

CO2

Project Objectives

Design a 1 MW thermal oxy-fuel combustor capable of generating 1200°C outlet temperature

• Manufacture combustor, assemble test loop, and commission oxy-fuel combustor

• Evaluate and characterize combustor performance – Optical access for advanced diagnostics

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ScheduleCombustor & Associated

EquipmentTest Loop & Associated

Hardware

Oct 2017

Jan 2018

Apr 2018

July 2018

Combustor Design

Quotes for Combustor

Continuation Report

Combustor Casing

Mechanical Design Test Loop

Design

Fuel System Design

Quotes for Test Loop Hardware

Outline

• Background• Project Objectives• Combustor Design• Test Loop Design• Future Work

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Combustor Design

• Mechanical casing• Fluid flow path• Fuel injector• Oxygen injection• Combustor liner thermal management• Optical access• Instrumentation• Design for additive manufacturing

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Conceptual Combustor Design

Cooling CO2

FuelO2

CO2

Cooling CO2

700 °C

375 °C

1600 °C >1200 °C 400 °C

Cooling CO2

Cooling CO2

Design Pressure: 250 barTemperature: 375-700 °C

Cooling CO2

Computational Modeling

Goals• Rapid solution times• Iterate on geometry• Inform liner thermal

model• Reduce risks in a variety

of areas prior to combustor manufacturing

Modeling• RANS simulations by

SwRI• Relatively course mesh• Variety of reduced

chemical mechanisms• LES simulations

performed by others• Well over 100 cases run

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Knowledge Base

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CO2 concentration

PressureCurrent Application

P up to 200 barxCO2 up to 0.96 (mostly as diluent)

Well-Developed MechanismsP up to 20 bar

xCO2 < 0.10 (mostly as product)Sparse data at low pressure, high CO2

Sparse data at high pressure, low CO2

Knowledge front

Limited data available – Current UCF and Georgia Tech projects

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Injector Geometry• 16 straight swirler passages, 40°

radial swirl w/ 10°down angle• 8 fuel injectors inject fuel midway

through swirler passage

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40° Radial

10° Radial

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Combustor Geometry• Effusion cooling on combustor

head and liner between head and dilution holes

• 0.05” wide dilution cooling slots, 1” apart

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200 barOperating Pressure

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Effusion Type Boundary Condition

• Effusion boundary condition created by mass source in first near wall element

• Energy source also used to make fluid injection temperature

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Design and Off-design CFD Boundary Conditions

• Design point simulations• Off-Design: Unique problem of sCO2 oxy-

fuel combustion is the cold startup case– Roughly order magnitude change in density

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Design Point Cold Start

Fast Start Ramp

CO2 Mass Flow (kg/s) 1.53 1.02 1.02Pressure (bar) 200.00 133.33 133.33CO2 Inlet Temp (°C) 700 50 150CO2 Density (kg/m^3) 104.2 649.4 203.5O2 Mass Flow (kg/s) 0.0806 0.0806 0.1360CH4 Mass Flow (kg/s) 0.0200 0.0200 0.0338

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Temperature Predictions

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30°

40° Coarse

40° Fine

50°

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CO Concentrations

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Light Purple zones are for mole fraction CO=0.008

30°

40° Coarse

40° Fine

50°

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Selected Results with Dilution• Fairly strong recirculation zone• High temperature near walls

– Adiabatic wall boundary conditions– Additional cooling

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Cold Start Case

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Desig

n Po

int

Cold

Sta

rt C

ase

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Possible Flame Holding Concerns

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• Fuel injected within swirlerpassage

• Startup case where velocity is much lower than design point

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Collaboration on Combustor Modeling with Others

• Work with several small companies interested in modeling direct fired sCO2 combustion

• Universities interested in geometry

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Cascade Technologies

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Shunn, sCO2 Oxy-combustion Working Group, Aug 2018

Convergent Science

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Outline

• Background• Project Objectives• Combustor Design• Test Loop Design• Future Work

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Sunshot Test Loop

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• The project will use the “Sunshot” loop currently being commissioned at SwRI

• Sunshot turbine will be replaced with letdown valve

Combustion Loop P&ID

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Closed Test Loop Built to Minimize New Piping

• Combustor to be closely coupled with existing “Sunshotheater”

• Connecting pipes made from Inconel 740H

• Addition of water separation in the heat rejection portion of the loop

• Quotes obtained for all major and minor hardware and fixtures needed for testing

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Outline

• Background• Project Objectives• Combustor Design• Test Loop Design• Future Work

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Next Steps

• Place major component orders• Assemble test loop• Assemble combustor• Instrumentation and DAQ• Commissioning – End 2019, Early 2020• Test Campaign – 2020

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QUESTIONS?

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ThermalInput