Don't get me wrong... I believe in our industry and the people in it.
But when I see things that don't make good sense, I have to speak my mind.
Please beware of so-called "expert" advise.
In the March 2009 issue of 'Textile Rental', the CEO of American Laundry
Systems recommends the use of coaxial ducting for laundry dryers. In his words..."Using this method, you can achieve
5%-10% increases in efficiency". The photo included with this statement shows one of
the few industrial dryer designs that still uses a Hi Fire/Low Fire gas system, with the reported co-axial ducting applied.
This makes little sense to me.
High-end industrial dryers use programming techniques to modulate a butterfly valve
on the gas train, which reduces the amount of gas used to maintain the desired temperatures. Without this, the dryer
gas system must operate on High Fire (full blast) or on Pilot, just like the original industrial dryer designs of
Regarding coaxial ducting, I'd suggest you put your hard earned
dollars toward more productive and efficient dryers or toward improvement of your current processes, and forget about trying
to save through some expensive heat recovery system whose ability is theoretical, at best.
So, I'm at the Clean Show in New Orleans (a subject all on its own). "Low
and behold", I see the answer to all of our drying efficiency woes! It's a magic box that saves
fuel by 50%, no matter what dryer is used or what the drying conditions are.
The Thermal Recycle literature suggests that your dryers use about 1800 to 2900 btu's
per lb. of LINEN processed. Given that the moisture content of a load after extraction is 0.5 lbs. H2O / lb.
of linen, under the best conditions, they're also suggesting that your dryers use 3600 - 5800 btu's per lb. of
H2O removed. If so, boy are you in trouble.
It's typical for industrial dryers to operate with efficiency numbers ranging
from 1600 - 2500 btu's per lb. of H2O removed. The high enders are consistantly at 2200 btu's and below.
Commercial equipment can yeild higher btu's per pound, due to their smaller loads and longer dry times, but you're typically looking
at 2500 - 3500 btu's/lb. of H2O, since their burners are also much smaller.
Let's be very clear, this equipment may very well improve dryer efficiency
by some %. I have no real data to dispute them. nor am I attempting to. However, I can't help but question
the data that they provide. If your dryers truly are getting only 4000 btu-6000 btu / lb. of H2O removed, as the literature
suggests, you need new dryers.
Their advantage... without a gas meter on your dryer, you'd never know, anyway.
Co-axial ducting and recirculation systems can be quite expensive to buy and even more expensive to install. Do
your homework. Visit laundries using these systems in conjunction with the same type of equipment that you are using.
Ask about installation issues and the related costs. Are they metering their dryers, so they can prove the benefits
to efficiency? Are there any adverse effects to dryer productivity, which could be caused by unwanted back pressure of limited
These systems cost a lot of money, up front, so be certain that you will reap the promised benefits without loss of production.
new dryers be a better investment?