Heat is required for many industrial processes. For drying and curing, for example, facilities traditionally rely on large natural gas-fueled convection ovens that heat the air that then carries the heat to the product.
A more efficient heating mechanism, though, is infrared. Infrared works by transmitting heat via radiation through electromagnetic waves. Infrared is not new to industrial settings — its use dates to the 1930s — but only more recently has it been employed in a wider range of applications.
Here’s how it works. Infrared radiation travels out from an emitter until it strikes a workpiece. The infrared energy is then either reflected from the surface of the workpiece, transmitted through the workpiece with little or no effect or absorbed by the workpiece, with its energy converted to heat.
Market Segments and Applications
Infrared technology can be used in a host of industries, from food to lumber and wood, textiles, fabricated metals, paper and printing, and more. It is typically applied in processes that involve heating, drying or curing:
- Thermal forming
- Liquid paint drying
- Powder paint curing
- Textiles and apparel dyeing and coating drying
- Food processing
- Polyvinyl chloride waterproofing
- Glass and glass product manufacturing
- Plastic molding
- Machinery and computer product manufacturing
- Metal joining
Infrared technology is growing in popularity thanks to the many benefits it offers.
- Speed: Infrared equipment can achieve full output in seconds.
- Efficiency: Infrared can be up to 90% more efficient than conventional heating.
- Flexibility: Infrared emitters and configurations can match particular applications and accommodate changing products and processes.
- Maintenance: Infrared systems require little maintenance and have relatively long lives.
- Productivity: Faster equipment and higher heating rates mean more products in less time.
- Safety: No open flames, reduced emissions and less dust provide a safer environment.
- Cleanliness: Reduced airflow means less dirt and dust contamination, and operating on electricity means no on-site emissions (though emissions from process chemicals can still occur).
- Product Quality: Consistent process heating and controls produce more even coloring and coating.
- Size: Infrared ovens are compact and save floor space.
Areas for Improvement
Despite its advantages, infrared does have some limitations. For example, infrared systems can have difficulty uniformly treating products with complex shapes or hidden surfaces, and capital costs can be higher than for conventional ovens. In addition, some vendors may warrantee their product only if it is cured for a set period of time at a particular temperature (i.e., with natural gas convection), so manufacturers may be hesitant to change their process without first getting vendor approval.
Example Cost Comparison
|Infrared Heating (Electricity)||Conventional Drying (Gas)|
|System Size||450 kW||2.0 MMBTU/Hour|
|Annual Energy Usage||2,541,176 kWh||44,000 MMBTU|
|Annual Scrap Losses||$100,000||$200,000|
|Annual Maintenance Labor Cost||$13,500||$54,000|
|Total Annual Operating Cost||$410,400||$557,000|
A textile company had been experiencing delays and quality issues on its production line for coating woven textile cloth.
Woven textile fabrics require coatings on both the finished and back sides of the cloth. Typically, the finished-side coating is a stain guard, and the back-side coating helps the cloth adhere to a substrate, like a foam cushion, during final assembly. The speed in linear yards per minute to coat and dry this cloth is key in profit margins.
The company was facing a problem with the moisture content of the coating material, and the plant was forced to run all double-coated cloth through a natural gas convection drying oven two times, once for each coated side. This setup required overtime shifts, extra oven runtime and double handling of the cloth — equating to more money spent and energy used.
Advanced Energy visited the site and evaluated potential solutions, eventually recommending that an infrared booster oven be added between the two coating stations. The infrared heat would kick-start the drying process. The first coating would be applied; the first coated side would pass through the booster oven and start drying; the second coating would be applied; and finally, the double-coated cloth would move through the drying oven just once. This new arrangement would cut drying time in half for all double-coated products.
The company was able to acquire a used infrared booster oven that produced immediate results. The reduced runtime of the existing drying oven resulted in an estimated 65,000 kWh of electricity savings and 6,500 dekatherms of natural gas savings per year, or around $47,000. The plant’s energy intensity in kWh per linear yard of cloth dropped by 12%, and project payback took just four months.