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 | Thar’s Gold in Thet Thar Stack!
With most plants now searching for ways to
minimize energy waste, one of the most common questions I hear is whether
there’s enough heat in an oven or furnace exhaust stream to make it worth
recapturing. Obviously, everything has to be approached on a case-by-case
basis, but here are some facts, figures and guidelines that may help you make
an informed decision.
by Dick Bennett
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 | Purple Polka Dots and Other Random Thoughts
Over the years of writing columns for Process Heating, I’ve had a number of items worth communicating
that are just too brief to fill an entire column. This is a collection of those
little bits and pieces. Just because something is small doesn’t mean it
shouldn’t see the light of day.
by Dick Bennett
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 | What's Needed in the Future?
In
2006, as part of its “Save Energy Now” program, the U. S. Department of Energy
funded “Energy-Savings Assessments” of process heating applications in many
industrial plants. The assessments are conducted by engineering professionals
who have completed the DOE’s training to become BestPractices Qualified
Specialists.
by Dick Bennett
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 | Efficiency: A Quick Review
Over the last few columns, I’ve beaten the energy conservation drum pretty hard. But energy costs remain fairly high, and many companies are still struggling with their impact on profitability, so please indulge me one more swing of the drumstick. This time, I’ll look at some ways to quickly assess efficiency and energy savings in process heating equipment.
by Dick Bennett
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 | Just How Efficient Are You?
The definition of oven or furnace efficiency is pretty straightforward -- it’s the thermal energy put into the product, divided by the total thermal energy consumed to carry out the process.
by Dick Bennett
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 | When is a Cubic Foot Not a Cubic Foot?
We all know that in convection ovens and furnaces, air is heated by a burner or electrical elements and then is pushed or pulled over and through the workload by a circulating fan. Coming into contact with the workpieces, the air transfers some of its heat to the product before going out the exhaust or being recirculated to the heating chamber.
by Dick Bennett
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 | Excess Air: Is it Such a Big Deal?
It’s a well-established fact that setting up combustion systems for too much excess air (or dilution air) wastes fuel. You can use this relationship to calculate just how much you can save by decreasing excess air:
% Fuel Savings = 100 x [1- (Available Heat, High XS Air/Available Heat, Low XS Air)]
by Dick Bennett
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 | Diagnosis: Institutional Amnesia
Visits to a number of plants this year have identified a common problem when it comes to energy conservation in their ovens and furnaces. They’ve got institutional amnesia -- as organizations, they don’t remember what they need to do to keep their equipment running at top efficiency.
by Dick Bennett
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 | Energy Conservation
Over the past few months, I’ve been involved in a number of plant process energy assessments. The results have been a mixed bag -- confirmation of prior expectations, some surprises and an exposure to a wide spectrum of attitudes toward energy conservation.
by Dick Bennett
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 | Hit or Miss-ivity
With energy costs in an upward Death Spiral, everybody’s getting
serious about monitoring their energy use. For many plants, a big part
of this is surveying their ovens and furnaces to identify areas for
improvement.
One of the most basic of these tasks is collecting data on the shell temperatures of heating equipment.
by Dick Bennett
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 | Let’s Get Organized, Part 4
OK, suppose you've done or
looked at all these things and have come to the conclusion they just
don't deliver the efficiency you need. This might not be due to
obsolescence or any fundamental shortcomings in your ovens or furnaces
-- perhaps your product's cost structure simply needs a greater cut in
its energy cost component. What now?
by Dick Bennett
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 | Let’s Get Organized, Part 3
This is the third in a series of steps to get the maximum energy efficiency from your ovens and furnaces. The first two dealt with optimizing scheduling, loading, operation and maintenance. Now it’s time to look at equipment improvements.
by Dick Bennett
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 | Let's Get Organized, Part 2
In Let's Get Organized, Part 2, combustion expert Dick Bennett explains how to bring your heat processing equipment up to the operating specifications it had when it was first commissioned.
by Dick Bennett
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 | Let’s Get Organized, Part 1
Over the years, I’ve discussed many of the factors affecting energy
consumption and what you can do to improve the situation, but I’ve done
it in sort of a random fashion. I’m going to go through it again, but
this time in an organized, systematic way to give you a framework for
analyzing and improving your process heating operations.
by Dick Bennett
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 | Urban Myths and Misconceptions
Every industry has its equivalent of those urban myths, and ours is no
exception. And like the stories that circulate over the Internet, some
of them seem to have nine lives, resurfacing time and again to lead
another generation astray.
by Dick Bennett
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 | Win-Win…And Win…And Win…
Choosing to give your heat processing equipment regular maintenance and
tuneups is not a win-lose decision. It’s time we rewrote it to reflect the
real world.
by Dick Bennett
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 | Bigger Isn't Necessarily Better
Maybe it's the Fireplace Mentality. Not warm enough? Make the fire
bigger. That's fine for relatively low temperature processes, but when
you get to extremely high temperatures, you need a hotter flame.
Otherwise, you can build a fire big enough to burn the place down, and
the product will still be standing, unchanged, amid the ashes.
by Dick Bennett
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 | How Did They Figure That?
Calculators at the ready, one equation will do for most -- but not all -- air and gas flow calculations.
by Dick Bennett
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 | Recycle?
The point of this is not to turn the fate of a cardboard box into one
of your life's Great Decisions -- it's to illustrate how complex the
decision can be. Let's see how this can apply to the issue of waste
energy, something all process heating operations have in abundance.
by Dick Bennett
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 | Taking the Long Look
Sometimes, after a while studying the trees, it’s a good idea to step
back and look at the forest. I’ve done a lot of columns on the
specifics of saving energy in process heating. This might be a good
time to look at how those specifics fit together.
by Dick Bennett
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 | Those Mystery Shutdowns
"I don't know what happened. We just opened the door, and the burner went out." It's a common refrain. Unfortunately, it's rarely right.
by Dick Bennett
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 | Is It 1990 Yet?
Combustion expert Dick Bennett cautions that when it comes to oven safety, some of us are living in the past, and it can be dangerous.
by Dick Bennett
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10 Years and Still Heating
Combustion expert Dick Bennett notes that the fuel-fired process heating arena typically experiences evolutionary changes unless some crisis, usually environmental or energy-related, kicks the pace up a notch. Bennett looks back at where we were 10 years ago, where we are now, and where the trends may take us.
by Dick Bennett
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 | The Special Situations
Combustion expert Dick Bennett continues his two-part series on calculating load heating requirements.
by Dick Bennett
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Crunch Time?
Dick Bennett suggests that you repare for potential energy curtailments now.
by Dick Bennett
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 | Burner History 105
Combustion expert Dick Bennett concludes his five-part series on Burner History with a look at today's generation of burners.
by Dick Bennett
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| Burner History 104
The nozzle mix burner has the spotlight in Dick Bennett's class this month.
by Dick Bennett
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| Burner History 103
Part 3 of the five-part Burner History series offers one more lesson on premix burners.
by Dick Bennett
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| Burner History 101
Combustion expert Dick Bennett begins a five-part series on how modern industrial
burners developed.
by Dick Bennett
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 | Is It Time to Experiment?
Why experiment? To improve your process, that's why. Reduce production costs, speed up
manufacturing schedules, improve product quality, raise productivity
and reduce scrap and rework -- you name it.
by Dick Bennett
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 | It Takes Two to Tango (Radiation, Part 2)
In my last column,
I began describing radiation heat transfer and the factors affecting
it. Radiation is a more complex phenomenon than it appears at first
glance, so it's necessary to carry on the discussion to give you a
complete picture of what it is and how it behaves.
by Dick Bennett
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 | Radiation, Part 1
In my last two columns, I've investigated convection and conduction heat transfer, so now I'll look at the third member of the heat transfer triumvirate -- radiation.
by Dick Bennett
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 | Conduction
I guess it's inevitable. Start talking about one phase of heat
transfer, and you feel obligated to rattle on about the others, too.
Just as you can't picture Larry without Curly and Moe, my last
column's discussion of convection begs for followups on conduction
and radiation. I'll take on conduction first.
by Dick Bennett
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 | Convection
It seems incredible that in seven-and-a-half years of writing this
column, I've never gotten into a discussion of convection heat transfer. After all, it is the way most ovens and dryers heat the products they contain. Well, better late than never.
by Dick Bennett
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 | Winning the Fan Shell Game
Remember the shell game, where the guy
puts a pea under one of three walnut shells, shuffles them around and
lets you guess (for a fee, naturally) which shell hides the pea? The
game is fixed, of course, and after a couple of easy guesses, you're
lured into putting down a bigger bet. Suddenly, the pea isn't where you
expected. How could that be? You're sure you kept your eye on the right shell. I had the same feeling when I first got into oven and dryer heating systems years ago.
by Dick Bennett
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