Industry managers are being challenged to trim costs and remain competitive with the expanding global market. Heat treaters are seeking new technologies to help alleviate their growing expenses. It would be great if it were as simple as putting a lock on the thermostat and asking employees to wear warmer clothes. Natural gas is an essential component of the heat-treat industry. This is not a small concern or even a passing one. Fossil fuels are a finite resource. As our economics professors taught us, as demand increases and resources dwindle, prices inevitably rise. Currently, new sources for fuel are being explored. The needs of heat treaters are pressing, however, and an answer is needed as soon as possible.

Alternative Energy Solutions Technology

Steeltech has developed Alternative Energy Solutions technology – known as AES – for radiant-tube assemblies used in heat-treatment furnaces. AES has been shown to save up to 20% on natural gas costs. AES tubes use less fuel, take less time to ramp-up from ambient to cycle temperature and last twice as long as standard alloy tubes. This is due to the optimal tube design in combination with the choice of material. Double the life means less costly replacements and downtime. A shorter ramp-up time generates savings with reduced labor and equipment operating hours.

Fig. 1. Performance of conventional vs. AES radiant tubes

Customer Experience with AES

Actual customer experience with AES tubes confirms the practical benefits of this technology. An operations manager from a western Michigan company says, “The radiant tubes that we purchased have already exceeded twice the life of tubes we have purchased in the past. The AES tubes currently show no distortion as compared to the standard alloy tubes. More importantly, we have seen in excess of 20% reduction of natural gas consumption. Gas prices continue to rise. In the future we will replace our tubes with AES energy-efficient tubes due to both the extended life and fuel savings.” See the sidebar for another testimonial.

Fig. 2. AES savings for a single batch furnace

Field Study Results

A field study was conducted over two years with two three-leg radiant-tube assemblies in two common 30x48-inch batch furnaces. One furnace had standard alloy, and the other had AES. The tubes ran five four-hour cycles per day, five days a week, at 1450-1900°F (788-1038°C). The AES tubes used 538 less Therms per month – a savings of $7,998 per month at the time of the study. This heat treater was able to see 15% savings on fuel alone with just one furnace. The results of the study are shown in Figs. 1 and 2.

Laboratory Study Results

An independent, third-party laboratory mirrored the operating conditions for the field study to thoroughly examine the performance of AES. Both the AES and standard tubes were fired with 28% excess air (5% O2 in the exhaust) to extend the rise time, assure the experimental precision was sound and to capture any significant differences between the tubes.

The observation of the radiant tubes’ performance was twofold. First measured was the time it took – with a 200,000 BTU/hr firing rate – to raise the test chamber temperature from ambient to 1800°F (982°C). The second measurement was the energy required to maintain that 1800°F chamber temperature for a six-hour hold. The AES tube took only 35½ minutes during ramp-up, while the standard radiant tube took 52 minutes – a 32% reduction. For six hours, the total energy used to maintain a steady 1800°F (982°C) chamber temperature was measured. The AES tubes used 79,680 less BTUs than the standard tube. Table 1 illustrates the laboratory study results.

Practical Considerations

In both studies, the AES radiant tubes used less fuel than standard radiant tubes due to more efficient heat transfer. Moreover, the lab study also showed that the AES reduced ramp-up time by 17 minutes. Let’s look at the impact of this over a month’s time:

5 cycles/day x 17 minutes = 85 minutes x 5 days/week = 425 minutes x 4 weeks/month = 1,700 minutes/month

Nearly 30 hours a month are banked for each batch furnace equipped with AES tubes. A 30-hour-per-month reduction in equipment operating expenses and a commensurate labor savings are excellent ways for an operations manager to cut costs. An additional 30 hours per month could also be used to run six extra heat-treat cycles, yet another way to increase profitability every month.

As demonstrated in the results above, heat treaters have seen up to 20% savings in fuel costs. Finally, there is good news about your gas bill. The price of gas will continue to rise for everyone, but the data shows that AES will result in clear and immediate savings. In addition to the fuel savings, operating and labor costs see a substantial decrease as well. With AES in your furnace, you have the potential of an extra 30 hours per month for every batch furnace in your facility. Whether you choose to cut costs or increase profits with more cycles, the additional 30 hours goes right to your bottom line.

Another area of savings AES provides is in the form of tube life. In the field, AES tubes have lasted twice as long and in some cases even longer. Double the life means fewer furnace shutdowns and more product throughput. You can perform more heat-treating cycles and meet your customers’ critical delivery times. All of the results show AES saves money and time, and time – in any industry – equals money.

Summary

Heat treaters are facing numerous challenges with today’s global economy. They look for help to stay competitive by reducing expenses and increasing efficiency. Steeltech has developed a technology that aids you and your company with fuel conservation and cost-reduction strategies. AES can potentially deliver up to 20% fuel savings as well as reduced operating and labor expenses. Our success depends upon your success, and that is why we provide materials like AES – another opportunity to improve your bottom line. IH

For more information and other cost-saving ideas, contact a Steeltech customer service representative at 1-800-897-7833 or e-mail us at alloys@steeltechltd.com

Additional related information may be found by searching for these (and other) key words/terms via BNP Media SEARCH at www.industrialheating.com: natural gas costs, radiant tube, heat distortion, firing rate