Combustor Designs for Small-Scale CHP Systems - ARPA-E · Combustor Designs for Small-Scale CHP...

1LAWRENCE BERKELEY NATIONAL LABORATORY

Combustor Designs for Small-Scale CHP Systems

Dr. Peter Therkelsen

Lawrence Berkeley National Laboratory

ARPA-E GENSETS Annual Review Meeting

December 14, 2016

Denver, CO


Agenda

1. Combustion

at Berkeley

National Lab

2. Combustion

Challenges

In Small-Scale

CHP

3. Lean Pre-

Mixed

Combustion

4. Low Swirl

Burner and

Grid Burner


Lawrence Berkeley National Laboratory


• Combustion Chemistry

• Experimental and

Computational Study of

Premixed Turbulent Flames

• Technology Development— Ultra-low emission fuel-flexible

gas turbines and industrial

boilers

— Carbon neutral fueled systems

— Small-scale combustion

systems

— Ultra-clean home appliances

— Bio-fuel fingerprinting

Combustion Research at LBNL


• High efficiency

— Combustion efficiency already ~100%. Effective heat transfer is a function of flame shape and combustion product flow field design.

— Remove parasitic losses associated with hot zone degradation.

• Cost

— Inability to rely upon exotic materials and coatings.

— Pre and post combustion treatment are negatives.

• Emissions

— Ultra-low emissions due to probability of systems being located in urban areas.

• Small footprint and weight

— Non linear scaling.• Volumetric L3 vs surface area L2

— Pre and post combustion treatment are negatives.

• Lifespan

— Decrease hot zone degradation – manage the flame.

Requirements of a Small-Scale CHP Combustion Systems


• Advantages

— Low emissions

— Potential for complete combustion

• Disadvantages

— Instabilities

— “Low” flame temperatures

• Where do you see it now?

— Low emissions continuous combustion

appliances

— Some intermittent combustion systems

Lean Pre-Mixed Combustion – System Performance without After Treatment

Fuel/Air RatioMore Fuel

“Fuel Rich”

More Air

“Fuel Lean”

Combustible Fuel/Air Mixture

Φ < 1 < Φ𝜆 > 1 > 𝜆

COHC

NOx


• Developed for basic studies of flame/turbulence interactions

• Adapted from 1kW to 200 MW systems

— Residential furnaces & water heaters

— Commercial & industrial heaters

— Gas turbines operating on natural gas, digester gas, syngases & H2

— Petroleum refining process heaters

• Enabling technology for next-generation advanced combustion systems

— Combined heat and power

— High efficiency combined cycle systems

— Advanced control systems integration with combustion technologies

Low Swirl Burner –Combustion Science to Commercial Product


Low SwirlHigh Swirl

High swirl

injector uses

a central

recirculation

zone (CRZ)

to stabilize

flames.

Low swirl

injector

stabilizes

flames

along the

shear

layers as

the central

divergence

zone

(CDZ)

expands.

High Swirl vs. Low Swirl Lean Premixed Combustor Stability


• Low NOX

• High turndown with

no staging or

multiple port design

• Detached flame,

reducing hardware

degradation

• Fuel flexible

• Scalable

Benefits of the LSB and Prior System Development Efforts


• Historic LSB operation conducted outside GENSETS design target

More turbulent flow regimes

Larger scales

• GENSETS design target to test

limits of turbulent flow field development

Divergent flow field flame stabilization principle

LSB Operational History and Design Challenge for GENSETS

GENSETS

target


LSB is highly-stable, short, and symmetrical with no flashback, less than 1%

pressure drop, and NOx and CO emissions nearly half of GENSETS target.

~10mm diameter LSB

In the open With 30o quarl

quartz enclosure

LSB Burner for Small-Scale Systems

Integrated

LSB combustor

NOx emissions

Operating point


• High efficiency

— Heat transfer mediums can be shaped to “mate” with the compact stable bowl shaped flame.

— Flame does not touch stabilizer reducing need for active cooling.

— High level of turndown provides ability to match demand.

— No parasitic loads associated with after treatment.

• Cost

— Standard materials can be used due to the lifted flame.

• Emissions

— Ultra-low emissions due lack of high temperature recirculation zone.


— Compact heat release.

— Ultra-low emissions negate need for after treatment.

• Lifespan

— Lifted flame does not degrade combustor compared to high swirl systems.

LSB and the Requirements of a Small-Scale CHP Combustion Systems


• Developed and used by LBNL for NASA’s

microgravity combustion program.

• Scaled down and adapted for use with

multiple appliances.

LBNL Grid Burner – Distributed Thermal Lean Premixed Combustion


Grid Burner NOx Emissions

5kW Burner


• High efficiency

— Evenly distributed flame across a wide surface area.

— High level of turndown provides ability to match demand.

— No parasitic loads associated with after treatment.

• Cost

— Simple fabrication with standard materials.

• Emissions

— Ultra-low emissions due lack of high temperature recirculation zone.


— Ultra-low emissions negate need for after treatment.

• Lifespan

— Simple design minimizes parts.

Grid Burner and the Requirements of a Small-Scale CHP Combustion Systems


• Small-scale CHP systems pose difficult challenges to

combustion systems.

— High efficiency

— Cost

— Emissions

— Small footprint and weight

— Lifespan

• Lean pre-mixed combustion offers ways to meet these

challenges.

• LBNL Low Swirl Burner and Grid Burner technologies

are lean pre-mix combustion technologies with proven

track records to meet the challenges facing small-scale

CHP systems.

Conclusions


Contact Information

Dr. Peter Therkelsen

[email protected]

(510) 486-5645

Thank you

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