RECUPERATION GURUS :  

EDDIE BERNARD  HUGH JENKINS  &  CHARLIE CORRELL
share their recuperation results here.  As each shop is different there is not one answer for everyone, but there are certainly steps one can take to start saving fuel today!

Feel free to contact any of these guys directly for quotes on retrofitting your existing equipment or building new furnaces.

 

EDDIE BERNARD  of Wet Dog Glass and Star Glassworks of NC  has a formula for finding recuperation savings and also to minimize NOx emissions: The formula for determining fuel consumption reduction with a given air preheat temperature is as follows:

1-   %availablea
       %availableb 

 For example:  let’s compare 70˚F combustion air to 800˚F combustion air.  With an exhaust temperature of 2200˚F using  70˚F combustion air at 10% excess air, available heat is 37%.  Using 800˚F combustion air at 10% excess air increases available heat to 52%.  This 15% increase in available heat translates to 29% fuel savings as per the equation.

1-   37  = 1- 0.70 = 0.29 = 29% fuel savings
      52

These formulas can be used to determine fuel savings on other recuperators in our art glass industry.  Glory holes in general fluctuate drastically as the doors are open and closed, so it’s best to tune them with doors in their most common position, which hopefully is closed.

We have now built recuperators for Glory Holes  in GH15 double-ended, GH18, GH21 and GH24 sizes since 2008.  They all get temperature control, auto-ignition and flame supervision.  We have recently developed a ribbon shaped burner tile that adapts to a commercial nozzle mixer so we can still get great heat distribution with a long flame path through the glory hole which makes ideal use of the heat in the flame.  Our air piping from the recuperator gets insulated to avoid losing heat on its way to the burner.   

Typically we shoot for a preheat air temp of 600F.  Above this temperature nitrous oxide (NOx) levels tend to rise dramatically.  We also use burners designed to minimize NOx emissions.  At 600F combustion air is doubled in volume as described by the following equation: [(preheat air temp + 460)/ 530].  Preheating the air to 600F with 10% excess air reduces fuel consumption by 26% while keeping NOx emissions from getting out of hand.

These formulas can be used to determine fuel savings on other recuperators in our art glass industry.  Glory holes in general fluctuate drastically as the doors are open and closed, so it’s best to tune them with doors in their most common position, which hopefully is closed.

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HUGH JENKINS  from Big Island Glass :

“I can confirm that recuperated glory holes can be 50% more efficient than unrecuperated. ”

 

My fu rnace, is 130lbs. (59kg), and runs on 5 1/2 gallons of propane a day or 5 gallons of veg oil.  My previous, 80lb. ( 36.2kg)  furnace  operated  on 15 gallons of propane a day.

I think even better results are possible with tighter door systems.   I also suggest to have an automatic burner control to compensate when the doors are open for any period of time.

Hugh recently  retrofit a 240 lb.  furnace in  San Diego  that created savings of  $1000 a month

Another glory hole retrofit in California reduced the use of  10 gallons of propane a day with a recuperated glory hole compared to its predecessor.

 

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CHARLIE CORRELL  from Correll Glass Studio in Massachusetts

Charlie has literally cut his fuel consumption in half with his products.  Based on his documentation of just putting a recuperation system on his existing glory holes in his studio the numbers are quite impressive!  Charlie has done the work for us with a fuel calculator located on his website.  http://www.correllglassstudio.com/fuelcalcs.htm

RESULTS:   before :  14″ Glory Hole w/ Pine Ridge Burner 186,000 BTU/hr.   reduced  to:  93,000 BTU/hr.   with a Correll Recuperator/Burner

 before:  8″ Glory Hole w/ Giberson Burner 89,000 BTU/hr.  reduced to 45,000 BTU/ hr.  with Correll Recuperator/Burner