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Kiln Connection: Investing in Energy Savings

August 1, 2005
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Invest in energy conservation now, and get an advantage that will provide a continuous cost savings.

Business has picked up, at least judging from my telephone and travel schedule. I have never worked on so many projects at one time, nor have I ever traveled as much. Two areas showing the most activity are energy reduction and investment (often related to energy).

If you have read my columns in the past, you know that I advocate the development of a cohesive energy program. Defining how much energy your kilns use-and comparing it to other kilns in the industry firing similar loads, temperatures and cycles-will give you an idea of the efficiency of your operations. The brick industry is the leader here; many of these folks can tell you how many BTUs/pound (or a similar mass-based measurement) their plants and many others use. If you leave the brick business, though, things get a little fuzzy-and yet understanding your energy usage is the starting point for the evaluation of your energy operations. The rest of the ceramic industry needs to keep up.

I often talk to people who think that the current energy price climb is an aberration. They are hoping that costs will go down soon, that the near quadrupling of the price of natural gas over the past five years has been just a "bubble." These are the same people who would now be accruing great savings had they aggressively invested in fuel saving technology several years ago.

Unless some startling new supply is discovered, and becomes available quickly, it is far more likely that the price will continue to go up. This isn't rocket science. Worldwide demand is increasing, and the only thing that could slow down long-term energy costs would be a large reduction in demand. Barring a global recession, which would cause its own problems, this just isn't too likely. Invest now, and get an advantage that will provide a continuous cost savings.

Roadmap for Savings

The best way to achieve savings is to figure out where the energy in your kilns is going. For example, one plant manager has watched his company's energy expenditure rise from 6% of the total manufactured cost to 24%. As profits dwindle, he wonders what to do. This company is struggling with unfair trade and doesn't have a lot of cash to invest. What can he do? Well, he needs a roadmap. The old saying, "If you don't know where you are going, any road will take you there," is doubly true in energy.

You first need to figure out how efficient your operation is. Determine the fuel consumption on the basis of BTUs/pound of ware fired, and then compare it to others in your industry that fire similar products. If your energy consumption is high (which it probably is if you don't know what it is to start with), then you simply have to figure out where all that energy is going. Analyze the firing system completely by looking at:

  • Cycle time. Shorter cycles are more economical.
  • O2 content during the cycle. The lowest oxygen content consistent with acceptable processing saves fuel.
  • Burner setup and firing system design. Excess air systems fired with fixed air/variable fuel are hard to justify except in some special cases, because they simply use too much fuel.
  • Air infiltration into the kiln. If the O2 levels are higher than a few percent, and the burners are set up close to stoichiometric, too much air is probably leaking in.
  • Wall losses. Take a look at refractory surface temperatures and start to worry if they are hotter than 250°F.
  • Wall heat storage (periodic kilns). Lightweight materials save a lot of energy.
  • Furniture and kiln car weight are critical. Look into low mass systems.


Take Action

One great resource is the U.S. Department of Energy (DOE) website at http://www.dow.gov. Currently, the DOE will help pay for 50% of your energy evaluations, and there may even be government funding that could help pay for some improvements.

More than half the time, saving significant energy is as simple as reducing the volume of air being heated. Determining where the air is coming from, and what can be done to eliminate it, is usually pretty easy, since it has only two sources-infiltration and kiln combustion setup. Many kilns run slightly negative in pressure relative to the factory atmosphere, and the air load to be heated can be phenomenal. Use of excess air is wasteful under ordinary circumstances and should be corrected.

Further down the line, investing in better systems for combustion-pulse firing-and employing preheated air can provide savings ranging from 10 to 50%. Start today and accrue some great savings tomorrow!

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