Boiler Irony


noun.  An outcome of events contrary to what was, or might have been, expected.


Or in Triangle Biofuels Industries terms, it means the refusal of a DOE grant application for a new boiler at TBI because some pencil pusher at the Department of Energy couldn’t get past one part of the grant requirements that said “improve efficiency”.  We met every other requirement (increasing renewable fuel, renewable energy distribution, employment additions in a distressed county, etc), BUT we didn’t meet the improving efficiency checkbox because I stated that I intended to install a newer, bigger boiler to replace our existing one in order to facilitate the additional heat energy needed to increase biodiesel production capacity.

So, using our own funds, we removed our old 800,000 BTU boiler and installed a 1.9 million BTU boiler, still fueled by biodiesel, and yet our fuel consumption rate has stayed almost identical at about 300 gallons per week.

How is this possible?  Several reasons, but increased efficiency is the main reason.  See, the old boiler was a single pass “water tube” type, meaning the fire goes up the stack by first passing around tubes filled with water being pumped inside to heat the water.  The new boiler is a triple pass “fire tube” type.  Here the water surrounds the fire tubes and gets three chances to absorb the fire heat, which is significantly more efficient.  The kind of efficiency that is measurable even by a lay person (or even a DOE grant supervisor). 

The first measurement?   Our stack temperature went from over 700°F to less than 300°F.  That means more of the heat is going into the water where we need it, instead of up the chimney and outside.

The next measurement?  Our CO and O2 levels dropped dramatically as well, from over 200 ppm CO down to 32 ppm.  And from 12% O2 down to 5%.  This also means we are burning more efficiently…  91% efficient, to be precise.

Given that we are burning biodiesel, our emissions are minimal and there’s really no smoke that comes out, and no sulfur or particulate matter, so our emissions aren’t really that much cleaner from that perspective.  They were already pretty clean.  However, the improved burn efficiency has to help. 

Lastly, the old boiler was simply undersized.  Our previous boiler was running almost 20 hours a day in order to keep up with the demand, and frankly, we could overload it pretty easily and it just couldn’t keep up with the heat requirements we had.  The new boiler gets the entire loop up to temperature from a cold start in less than 30 minutes, and actually cuts off when it gets to working temperature (thus why we are saving fuel).

So was installing a new boiler in our plant more efficient?  Yep, in just about every way we can possibly measure.  More heat for our process, more consistent heat, working in a more efficient load cycle, and burning fuel more efficiently.  We also gain the benefit of internal space heating by the boiler.

The cost?  Well, as always, we buy used when we can.  The cost was almost a wash for selling my old boiler, which sold within two days of removing it.  The ROI would have been met in increased production within a six months anyway, but we got it back in 2 days.  That’s what I call efficient.

Firetube Boiler

Posted in Biodiesel.