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.

First things first: Congratulations to BNP, Linda and all the gang atProcess Heatingfor 10 years of a first-class publication. May there be many more!

When Linda asked me to write an extended column about the last 10 years' worth of trends in this part of the industry, I had to stop and think, because nothing really dramatic jumped out. It's a little like watching your kids grow -- it happens in such a gradual and subtle way, you don't notice any great changes until you look at some old photos or videos of them.

And so it's been in the world of fuel-fired heating processes. Change has been incremental, but that's nothing new. This has always been a stronghold of evolutionary changes unless some crisis -- usually environmental or energy- related -- kicks the pace up a notch.

So let's take a look back at where we were 10 years ago, where we are now, and where the trends may take us.

New Technologies and Equipment

As I mentioned, ours is an evolutionary industry; radically new technologies don't burst on the scene, making everything else obsolete. Nevertheless, there has been a steady stream of product modernizations and new developments.

In the realm of process control, more plants are linking the heating equipment with plant-wide control and data-gathering systems. For the most part, this has been limited to monitoring process flows through various pieces of heating equipment and gathering operating data from those processes. Functions like burner ratio control and safety monitoring continue to be done at the local level, and this isn't expected to change very much in the foreseeable future.

Variable-speed drives for fans are making inroads due to their more efficient use of electrical energy, but this has been primarily in the area of recirculating, exhaust and other process fans. For the most part, combustion air blowers continue to be constant-speed units, and flows are regulated by motor-driven valves.

Gas and air flow-control equipment has been heavily influenced by European developments. In gas trains, compact, multifunction valves are becoming popular. These valves, many of which are modular, may combine one or two safety shutoff valves, regulators, gas strainers and pressure switches in a single unit, permitting a more compact installation and less piping labor.

More and better diagnostic tools are available today. Ten years ago, traveling dataloggers and thermal imaging scanners were curiosities in most plants. Now they're in wide use, helping to eliminate a lot of the time-honored guesswork about how our process heating equipment is really working.

In the world of burners, much of the past 10 years' development energy was focused on lowering NOX emissions. However, we've also seen a resurgence in the use of infrared process heating, including flameless catalytic heaters. The rapid growth of powder coating has played a big part in this turnabout.


Environmental standards in the United States tend to follow political cycles: A push for lower emissions will be followed by a cooling-off period, where the government stands pat or even backs off some previous standards, especially in a slow economy. Then, after a rest of a few years, demands for cleaner air, soil and water will shift the regulatory process back into gear.

NOX. Ten years ago, the push was on for reducing nitrogen oxides (NOX), and combustion equipment manufacturers were trying to find ways to drive emissions down without sacrificing the good performance features of their burners. As with any technology in its early stages, there was a lot of experimentation to find the keys to lower NOX emissions without generating high levels of carbon monoxide and without sacrificing the flexibility of established designs. Some of these early attempts were complex, touchy to set up and run, and had a propensity toward self-destruction, but as burner designers learned what worked and what didn't, their designs grew in reliability, sophistication and the ability to hold emissions at consistently low levels. For the most part, today's generation of low NOX burners can satisfy current air-quality standards, and the standards themselves have entered a period of stability.

Carbon Dioxide. The air-quality debate has shifted focus to carbon dioxide emissions, which many finger as a major contributor to global warming.

The U.S. government has refused to sign the Kyoto Protocol, arguing (probably rightly) that the bye given some developing nations on CO2 emissions, along with their lower labor costs, gives them an unfair competitive advantage in world markets. Regardless of how this plays out, the solution will not be another cycle of burner and control developments. For a given choice of fuel and a specified heat output, a combustion system produces a fixed amount of CO2, and no technological improvements can change that. One way to reduce emissions is to switch to a fuel containing less carbon, but natural gas, the fuel of choice in our industry, has the lowest CO2-to-energy ratio of all the commonly used industrial fuels. Hydrogen has no CO2 emissions, but its wide use as an industrial energy source is years off.

Lowering CO2 emissions without switching fuels requires operating more efficiently to generate a smaller amount of exhaust gases per unit of oven or furnace production. As long as the United States continues to stonewall Kyoto, there's not much incentive for companies to attack CO2 emissions through efficiency improvements. It may come about anyway, but for a different reason -- energy costs.


Natural gas has become industry's fuel of choice. Among the common industrial fuels, it is the most widely available, requires the least preparation and handling, burns the cleanest and is the most forgiving of lapses in burner tuning and maintenance. In some areas with stringent air-quality standards, it has become the default fuel because none of its competitors can match it for low NOXemissions.

Success extracts a price, however. Because of all its advantages, especially environmental, more and more natural gas is being consumed for electrical power generation. This is creating a sellers' market as the power and manufacturing industries vie for available supplies. We saw a hint of this a couple of winters ago, when gas prices spiked. That price surge faded amid charges of market manipulation, but there's no question that gas supplies are becoming tighter, prices are climbing, and concerns are developing about possible supply curtailments. In most regions, alternate fuels like liquid propane (LP) and oil are not the solution. Supplies of these fuels aren't abundant enough to carry us through a major interruption and, in the case of fuel oil, the supply infrastructure withered away when natural gas became dominant. To that, add that the most recent generation of combustion equipment was designed with no thought of making it able to burn fuel oil.

Widespread conservation may be the only long-term solution to this problem. The nice part of it is that the reduction in CO2 emissions will come as a throw-in.

Process Efficiency

Improving process efficiency is like Mother, apple pie and the flag -- everyone is for it. However, Mother didn't have to show an attractive payback to justify her existence, like most efficiency improvements do. Consequently, industry's commitment to regular tuneup schedules and energy-saving equipment often has been sporadic and half-hearted. Energy costs usually have been the main factor in determining whether more efficient process or equipment changes get management's blessing. With fuel prices continuing to rise, expect to see renewed interest in analyzing the energy efficiency of industrial heating processes, along with a greater resolve to improve it.

Knowledge Base

Technology upgrades are only the first part of gaining lasting improvements in heating process efficiency, productivity and reliability. The second, and in my opinion, more important, part is knowing how to set up that equipment properly and keep it running correctly. Over the past 10 years, we've had a highly mixed record in this area. For example, we've turned to computers and solid-state controllers to monitor more process parameters, so we're getting more -- and more accurate -- feedback on how our systems are running. However, the heating equipment itself is one of the least likely oven subsystems to be tied to a central processor. In addition, there's been a noticeable decline in the depth of knowledge of how heating systems work and how to tune and troubleshoot them. On the average, the present generation of plant operating and maintenance people have more information than ever on how their heating processes are running and less understanding and knowledge of what's required to keep burner and heat transfer systems at peak efficiency.

Process documentation disciplines like ISO 9000 have been used to enforce regular monitoring and adjusting of heating systems. That's good, where it is being done, but in all too many plants, it seems like ISO 9000 and its counterparts have simply had the effect of embalming poor operating and maintenance practices.

One promising development in the area of analyzing process heating efficiency is the Process Heating Assessment and Survey Tool (PHAST). Developed by the U.S. Department of Energy in cooperation with the Industrial Heating Equipment Association, this software package allows you to conduct an efficiency analysis of industrial heating processes based on operating data measurements you collect. In essence, it's a heat balance, and once you have run it, you can play “What if?” games to evaluate the effectiveness of various changes in equipment and operating practices. If you'd like to learn more about it, check out DOE's Office of Industrial Technologies web site at

Dick Bennett sums up his prognostications in a simple chart, where the lines and arrows suggest how the trends have played out in the past 10 years and where they may be headed.

Report Card

I've tried to sum all this up in a simple chart, where the lines and arrows suggest how the trends have played out in the past 10 years and where they may be headed.

For the next three or four years, at least, I expect to see no significant change in the environmental demands placed on U.S. industry; some states, though, may decide to hold themselves to a higher standard than the federal government. Natural gas prices will continue to rise, and at an average rate higher than we're used to seeing. Expect occasional price spikes, especially in winter, and periodic supply pinches. Localized curtailments of industrial gas supplies aren't out of the question.

Interest in employee training, fairly dormant for the past couple of years, is starting to revive, and should continue to grow in direct proportion to energy prices. This will go hand-in-hand with renewed interest in new technologies for reducing energy consumption in process heating equipment.

Apart from efficiency-related improvements in combustion equipment and their controls, I don't expect to see any drastic changes in heat-generation technologies. Refinement and steady improvement will be the bywords. Truth is, many plants could make substantial efficiency improvements by updating to equipment that already has been around for the past five or 10 years. There's no need to wait for the next generation of hardware.

I want to point out that this is my guess based on what I've seen. Things may look entirely different from a different vantage point. It also should be apparent that the world economic and political situation is the elephant in our bed. One little twitch, and all these carefully wrought forecasts go out the window. Now I know how the weatherman must feel.