Gas Technology: Infrared systems supply process heat – efficiently
New designs improve effectiveness
Process heat applications today benefit from advanced systems for radiant infrared (IR) heat. The advantage of infrared is that it focuses heat on the target objects and not the surrounding air, thus is more efficient than pure convection heating. Further, systems can be designed for specific process needs, whether that is melting cheese, powder painting garden equipment, or drying textiles. Infrared emitters can be placed everywhere in the process line where they are needed.
The traditional design for gas infrared burners involves the flow of fuel through or adjacent to ceramic refractory infrared emitter surfaces. As combustion takes place, the ceramic surface emits a high proportion of the released energy as infrared. The ceramic emitter can be formed in a wide variety of shapes. Some newer designs use porous metallic emitters that have advanced performance characteristics.
Tom Rozek is the CEO of Red-Ray Manufacturing Co., one of the major suppliers of industrial infrared equipment in the U.S. and Canada. He was a presenter at a recent Technology and Market Assessment Forum sponsored by the Energy Solutions Center. Rozek indicates that companies now using atmospheric, convection or ribbon burners can realize gas energy savings of 50% or more by changing to gas-fired infrared burners.
New emitter designs
Rozek indicates that his company has introduced two new emitter designs that are even more efficient than earlier ceramic designs. One contains a metal alloy fiber matrix emitter and the other a metal foam alloy emitter. Rozek explains that the metal fiber product has a high heat flux density and the metal foam emitter has a medium flux density. “Both burners are flat faced so they can be placed 3-4 in. from the product. The effectiveness of IR is inversely proportional to the distance from the product.”
Rozek points out that Red-Ray’s gas impingement ceramic emitters have also been redesigned to increase their efficiency and output. As an example, he says that the aperture in the finned ceramic refractory is a slit as opposed to ported holes in earlier designs, which could become clogged. The ceramic emitters are designed in a modular style, so refractories and side plates can be replaced as needed. He indicates that modern infrared burners are very durable. “Their lifetime is dependent on the application, but is typically 5-10 years.”
Food industry: Moving toward infrared
A large market for Red-Ray is in the processed food industries, where rapid, consistent heat is needed to put a finishing touch on foods. This includes browning snack foods, melting cheese coatings, and similar food processes. The close proximity of the emitters to the food product as it passes below on the line allows for high heating efficiency. In these applications the all-metal, high-efficiency emitters are especially attractive.
Powder paint: An ideal application
Another of the rapidly growing markets for infrared heating is powder painting. Rozek explains that the switch from wet paint systems is driven by the desire to avoid the expense and environmental problems of evaporating, condensing and disposing of solvents. He adds that worker health risks are also reduced by eliminating solvent exposure.
Powder paint curing is an ideal application for infrared systems. Heat energy can be applied directly to the painted objects, and paint tunnels can be designed with heaters specifically arranged in the appropriate directions to heat the intended product flow.
Optimizing system design
Today’s infrared heat designs for powder paint allow great flexibility in adjusting the heat flux to the appropriate stage of production. Variable heat levels can be achieved as the product flows through the treatment area, adjusting heat levels by the distance of the emitter from the product flow, and by selecting emitters with various heat flux levels.
Manufacturers of industrial infrared heaters offer assistance to both equipment manufacturers and end users in assessing the thermal requirements of the design and recommending the type of heat unit that will be most efficient and effective. Rozek says that Red-Ray is accustomed to working with oven manufacturers to optimize the system.
Another major supplier of gas-fired infrared units to industry is Vulcan Catalytic Systems. Vulcan’s President, Mike Chapman, indicates that the company’s catalytic infrared heater is the only natural gas-fired heater that operates in the range of 400-1,000 degrees F. He points out, “The advantage to this unit is that it emits the ideal wavelength of IR that is easily absorbed by surfaces such as paint, water and plastic, and competes well with typical electric IR systems.”
Energy saving over electric
Chapman emphasizes that retrofits from electric systems result in tremendous energy costs savings. “Additionally, it is a flameless gas technology where the catalytic reaction releases over 80% of the fuel as easily absorbed infrared. In other words, the parts being treated heat up quickly.”
Chapman explains that the company’s product applications focus on paint finishing, plastic thermoforming, and drying applications. “For any flat surface that needs up to 500 degrees to cure or dry, catalytic infrared is the most cost-effective heat source.” One important Vulcan application is IR heaters that are used for preheating powder painted parts for 2-3 minutes before they enter a traditional paint convection oven. Chapman says, “This acts to gel the powder on the part before it hits the high velocity air in the oven, avoiding part contamination and added maintenance work on the convection oven from airborne powder paint.”
Vulcan also manufactures complete catalytic infrared powder paint ovens in modular sections and ships them pre-plumbed and pre-wired for fast onsite installation. Vulcan works with the customer in designing ovens for the specific product and type of powder paint application.
Increases quality: While saving energy
Chapman uses as an example of the advantages of powder paint Wesco Industrial Products of Lansdale, Penn. The company had been using a water based paint system with a large curing oven. They had encountered quality problems from paint damage after products were out of the oven and being shipped. By switching to powder paint and an infrared curing oven, they virtually eliminated paint damage.
Further, they reduced their natural gas usage for paint curing by 25%. A catalytic curing oven by Vulcan was installed in modular sections and occupies only 360 sq ft as opposed to 2,500 sq ft for the earlier wet paint oven. The new oven was installed to surround an existing product transport line. Chapman notes that this experience with saving space and energy and getting a better paint coat is not unusual.
Whether your heating need is drying fabric, browning snack foods, curing paint or melting cheese, the infrared option needs to be considered. Systems are available for a wide range of temperatures and installation configurations. This gas-fired technology can help you compete.
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