Industrial combustion is front and center in this issue of Process Heating. First up is “Considerations for Regenerative Combustion Systems,” in which Michael Cochran of Bloom Engineering explores how using regenerative burners in pairs, along with a bed of ceramic or metallic media, can capture heat that would otherwise be lost from the process. This captured heat can be used to preheat incoming air or elsewhere in the process. Cochran looks at control methods and media bed choices that can optimize the process.
Another approach for multiple-burner systems is pulse firing. In pulse firing, the heat input is controlled on each individual burner by modulating the frequency of the high and low firing ranges, says Frank Wallace and Katie Huller of CEC Combustion Safety LLC in their article. Among the benefits of pulse firing are the potential for extended equipment life, fuel savings and reduced emissions. In “Pulse Firing Doubles Capacity and Cuts Fuel Costs,” Wallace and Huller describe pulse firing and share a case history that demonstrates one company’s success with pulse firing.
Industrial ovens and furnaces often rely on direct-fired burners to provide the heat needed for thermal processing. Of course, once you’ve created the heat in the combustion chamber, it is important to transfer that heat to the product with as little loss as possible. Wall, conveyor and radiant losses are a given in any industrial oven, but poor airflow and air balancing can cause you to lose even more heat out the openings of your oven. In “Balancing Industrial Oven Operation,” Peter Caine and George Urban of HeatTek Inc. note that an out-of-balance oven will consume an excessive amount of energy and can create potentially unsafe operating conditions. Moreover, proper — or improper — oven balancing has a direct influence on the quality, function and appearance of your finished product.
While oven balancing and effective combustion control are important for all industrial ovens, ovens used to dry and cure finishes on wood products have special requirements. Some wood products such as wood and cement-board siding, moldings and trim are prefinished by the manufacturer prior to sale. This finish coating must be durable enough to withstand the manufacturing, delivery, purchase and installation processes before providing years of appealing appearance in homes and businesses. The coating, curing and drying approaches used with the trim products depend on their size and profile, says Mike Grande of Wisconsin Oven in “Specifying Wood Drying Ovens.”
Of course, burners are not only used for industrial ovens and furnaces. In “Combustion Controls for Boilers,” Brett Barnes of Nationwide Boiler Inc. explains the typical combustion control schemes used with watertube and firetube boilers. Three choices — single-point positioning, multiple-point positioning and metering — provide increasingly tight control (and higher costs). As Barnes notes — and as can be said for all industrial combustion heating systems — selection of the burner control system can affect equipment operation, maintenance and efficiency. With this lineup of articles, you are better prepared to select well.