Sustainable Burner Design

Motivation

(why energy?)

August 2003 Blackout

(You were 3.  I was in grad school.)

It started here in Ohio.

August 2005 — Katrina

• Natural gas spot price doubles (we don't really have reserves)

The need for workable energy options is perhaps the greatest single challenge facing our nation and the world in the 21st century.

- MIT Energy Research Council

   July 2006

I graduate 2006

• About 250 people.
• Formed after the oil crisis.
  (Was 3× bigger in the 70's-80's.)
• Serves the natural gas industry at all points
  in the value chain.
• Members + Govt. + Industry pay for our research.

+ join the Gas Technology Institute

Industrial Process Heat

burner design for industry

Engineering design PSA

• Know the Principles.
• Understand the Situation.
• Apply the Principles to the Situation.

Principles:  Combustion Triangle

The combustion triangle names the necessary things for combustion.

Oxidizer

Fuel

Heat
(ignition)

Principles: Methane Combustion

Principles: Methane Combustion

Ideal gas law:   Pressure ≈ Number of Moles if T constant

Principles: Methane Combustion

Things we can vary

CH4  +  9.7 Air →  Heat  +  CO2  +  2 H2O  + 7.6 N2 + stuff

• Why not ditch the N2?

=

2 O2 + 7.6 N2 + stuff

Situation: Glass + Oxy-Fuel burners

CH4

2O2

prototype burner in a GTI test furnace

• Also the oxygen lance.
  (enhances luminosity)

Principles: Heat Transfer

Only three ways to get heat to the load.

Ideas?

Principles: Heat Transfer

Eclipse thermal radiation burners.

(Possible use: industrial cooking.)

Eclipse high velocity nozzle mix burner.

(Possible use: steel reheat.)

Example burners

Things we can vary

source: John Wagner's report on oscillting combustion (PDF) for the Department of Energy

Principles for efficient design

Types of burners

(that our team has worked on)

All shapes and sizes: for cooking, chemicals, melting, boiling...

Flame shooting out the sides!
Wasted heat...

Situation: Wok burners

• Restaurant margins are razor thin (3-5%).
   
• It's 2007. Gas prices are still very high.
   
• Our commercial / food service burner expert is approached by a chain to reduce their energy cost.

Existing design: Deep brick-lined well to absorb and radiate heat. Nice. ✔

Situation: Wok burners

Existing design:

Little nozzles are like tiny blowtorches that blast a ton of energy into the wok. You do not need this much energy to cook food, so it will be wasted. ✘

Principles: Wok burners

• We are cooking chicken, not
  melting steel: infrared heat
  is just fine.
   
• Angled walls reflect
  more heat up to the wok.
   
• Slower inlet velocity ⇒ longer residence time.
  The exhaust lingers instead of shooting out, adding more heat.

From US Patent 7926479 (2011)

Wok burner performance

More than double the efficiency of existing burners:
​this should use about half the fuel.

From US Patent 7926479 (2011)

Situation: Glass melter

• Burners fire over a pool of molten glass
• Lifespan is about 20 years, afterward left with a lake of solid glass.

Principles: Glass melter

• Because the outlet is at the bottom, you can empty the whole thing.
   
• Direct flame impingement ⇒ tons of conductive + convective heat transfer.
  (Enough to allow air
  feed instead of O2.)
   
• Bonus: the temperature
  drop in the glass is sharp and
  swift enough to prevent NOx
  formation when using air.

From US Patent 20110236846A1 (2011)

Glass melter performance

• 5-7% fuel savings when using oxy-fired combustion.
• Up to 23% fuel savings when using air-fired combustion.

From US Patent 20110236846A1 (2011)

Situation: Boiler heat recovery

DOE challenge for efficiency led to a 2008 Chicago Innovation Award for the boiler team and Cleaver-Brooks.

Low pressure exhaust

Transport membrane condenser

Humidifying air heater

High pressure exhaust

Images are from a super boiler presentation to the DOE (PDF)

GTI's new invention

Situation: The boiler design

In a fire tube boiler you combust in the big hole and the exhaust travels through the little tubes to give it time to boil the water.

Images are from a super boiler presentation to the DOE (PDF)

Extruded aluminum inserts in the fire tubes - for heat transfer like in a car radiator.

Boiler cross section.

Principles: Boiler design

Images are from a super boiler presentation to the DOE (PDF)

• We are boiling water, not melting steel. So like with the wok, even under pressure, we don't need super high temperatures.
   
• Recirculation ⇒ more
  residence time*.
  (more heat transfer)
  
  
   
• Staged combustion ⇒
  lower maximum temperature.
  (less NOx)

*Dimensions for a design like this must be calculated using CFD.

Situation: Heat recovery (prior art)

All drawings from U.S. patent 7066396 (2004)

• There is one water loop.
   
• The steam loop (orange) circulates hot steam to the downstream process.
   
• The air is piped through the exhaust to recover some of the leftover combustion heat.
   
• The air + fuel (clear) pass through the system and out the flue.

Situation: Heat recovery (prior art)

All drawings from U.S. patent 7066396 (2004)

• There are two water loops.
   
• The steam loop (orange) circulates hot steam to the downstream process.
   
• The condensate loop (purple) condenses out steam from the combustion exhaust, using it to humidify the incoming air.
   
• The air + fuel (clear) pass through the system and out the flue.

Principles: Heat recovery (new idea)

All drawings from U.S. patent 7066396 (2004)

• There are two water loops.
   
• The steam loop (orange) circulates hot steam to the downstream process.
   
• The condensate loop (purple) collects steam from the exhaust via the membrane.  It contributes make-up steam* and humidifies the air.
   
• The air + fuel (clear) pass through the system and out the flue.

*condensate could not be used in make-up steam until now because it was not pure H2O and would gunk up the process.

Photos of the membrane bundle

Images are from a super boiler presentation to the DOE (PDF)

First generation

Second generation

A membrane is a surface with micropores. Exhaust flows through these bundles, and the water molecules pass through the micropores in the walls to enter the condensate loop.

Superboiler performance

Data from Rick Knight's talk at the University of Texas

Principles for mid-90% efficiency

• Heat transfer:
  • Recirculation ⇒ more residence time.
  • Humid ⇒ better heat transfer.
  • Heat recapture ⇒ more efficient.
  • New technologies (membranes)
    can squeeze more performance
    out of existing ideas.
  • Fins in the fire tubes
    ⇒ huge surface area
    for heat transfer.

• Combustion:
  • Staged combustion ⇒ lower peak temperatures ⇒ less NOx.
  • Humidification also lowers peak flame temperatures.

+

+

=

Solar supplemented water heating

Solar heating control panel

Equinox solar-assisted tankless water heater

California Energy Commission report on solar-assisted industrial heating

California Energy Commission report on solar heating for food processors

The boiler team won a contract from California to combine the best tech for water heating. This is from a report in 2013. It was field-tested in a small winery.

Solar supplemented water heating

This is the one from the report

This one is for a boiler.

From Dave Cygan's 2015 report to the California Energy Commission

This is the test installation at GTI's facility near Chicago.
The tubes are slanted so that the water will drain out of them when not in use (to prevent burst from freezing).

Solar supplemented water heating

From Dave Cygan's 2015 report to the California Energy Commission

About 40-50°F gain in July; about 10-20°F in December.

Inlet

Outlet

Principles + situation: solar preheat

Principles

• Using heat from the sun saves gas.
• Combining efficient technologies (+tankless) can yield extra efficiency that's worth the cost.

​

Situation

• Water heaters don't require a huge temperature gain. In your house the recommended water heater temperature is 120°F.
• The cost of the solar installation may not be enough for a residence, but a small commercial application can benefit.

Recent developments

• A current photo on GTI's webpage shows a more efficient solar collector that's being tested for use in natural gas power generation.
   
• The principle,
  preheating the water,
  is the same.
   
• The solar collector is
  different so it can
  capture more solar
  radiation.

Photo from GTI press release.

Context matters

(Things that are unrealistic in one situation could be fantastic in another.)

People use what they've got

https://www.eia.gov/state/maps.php

Portable natural gas liquefaction

Hydrogen fuel cells

PlugPower's GenDrive forklifts

(July 2017 article about them at Walmart)

Why power companies ❤ efficiency

Data: PJM hourly load data for each market.

Questions?