Consulting-Specifying Engineer - August 2007 - (Page A9)

Secondary Air Flue Outlet u omb lar C Annu stion Zone d Flu e Pr oduc ts rne Retu el ir/Fu ary A Prim The claimed advantages of the RASERT system include more even heat output, substantial energy savings, and longer tube life. The system can be retroﬁt in existing heat treating equipment. Fuel In Combustion Air In Researchers have found ways to increase the percentage of energy the tube actually radiates. One approach to increasing the amount of energy emitted is to install a high-emissivity insert in the exhaust leg. Spinworks LLC has developed a helical silicon carbide insert that causes the exhaust gas to spiral, thereby increasing turbulent heat transfer and forcing the gas to take a long exit path. Another method is encompassed by the Gas Technology Institute’s (GTI) patented reverse annulus single-ended radiant tube (RASERT) design. The RASERT design has coaxial inner and outer tubes, with combustion taking place in the space between tubes, and the exhaust passing through the inner tube. According to Steve Sikirica from GTI, the RASERT has numerous attractive features. The patented RASERT design, developed by GTI and North American Manufacturing of Cleveland, is now being proven in the ﬁeld. It was installed in late 2006 in a steel annealing line at California Steel in Fontana, Calif., and additional operating systems are currently in the planning stages. the need for combustion efﬁciency. The newer generations of combustion tubes are deﬁnitely improving in this area.” Kent says another area where heat treating equipment is improving is in precision of control. “Today, heat treatment specialists need to hold very tight temperature tolerances, and they want furnaces and ovens that maintain those conditions uniformly. Richard Bennett observes that the current generation of radiant tubes produces signiﬁcantly lower levels of NOx than earlier designs. He indicates that this result, coupled with faster payback potential, may ﬁnally lead to preheated air burner systems being considered the default approach to ﬁring radiant tubes. He notes, “Many furnace builders have already taken this step.” FLAMELESS COMBUSTION APPROACH Another signiﬁcant approach in natural gas-ﬁred heat treatment equipment is an advanced combustion system developed by WS Thermal for ﬂameless combustion for heat treatment burners. This technology, termed FLOX®, combined with an advanced ceramic tube material, provides a very long life burner tube with markedly lower NOx emissions. TREATMENT EQUIPMENT CONTINUALLY IMPROVING Whether your business is a specialized shop that does small batch heat treating as a part of the manufacturing process, or a large mill or foundry that heat treats thousand of tons of steel daily, these new technologies hold promise. Now may be time to take that step to newer heat ❮GT❯ treating technology. SINGLE-ENDED DESIGN BY ECLIPSE RASERT DESIGNED FOR RAPID RETROFIT The high efﬁciency of this method of combustion and improved heat transfer can result in fuel savings as high as 50%. The RASERT’s lower inner tube temperature and more uniform outer tube temperature eliminate stress-inducing hot spots, resulting in extended tube life. RASERT is designed for rapid retroﬁt, replacing existing conventional tubes. Another attractive feature of the RASERT, according to Sikirica, is its ability to meet the challenge of reduced NOx emissions through its cool annular ﬂame conﬁguration. Additionally, because it operates at a higher overall efﬁciency, it reduces the generation of CO2. Another signiﬁcant approach in heattreating steel is the AutoRecupe singleended burner design used by Eclipse Inc. in several of its products. Eclipse claims that this burner design is 35% to 50% more efﬁcient than sealed ambient burners and even more efﬁcient over atmospheric burners. A frequent user of Eclipse heat tubes in its products is Wisconsin Oven. According to this ﬁrm’s vice president Jeff Kent, his company has seen steady improvements in combustion tube technology in recent years. “Buyers of ovens expect durability and steady performance over the life of the product. In recent years, they have also been especially sensitive to For More Information Eclipse Inc. www.eclipsenet.com Gas Technology Institute www.gastechnology.org Janus Technology Group, Inc. www.janustechgrp.com North American Manufacturing www.namfg.com Spinworks LLC www.spin-works.com Wisconsin Oven www.wisoven.com WS Thermal www.ﬂox.com A9 http://www.eclipsenet.com http://www.gastechnology.org http://www.janustechgrp.com http://www.namfg.com http://www.spin-works.com http://www.wisoven.com http://www.flox.com

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - August 2007

Contents M/E Roundtable Giants 100 Pullout Poster Giants Stand Tall: CSE Giants 100 Report Electrical Design for Tall Buildings HVAC and Fire Safety for Elevator Systems How to Beat the Codes GAS Technology Supplement Recovering Waste Heat from Boilers New Applications for Tankless Water Heating Systmes Techniques Improve for Powder Coating MDF New Tools Available for Heat Treating Steel Direct Drive Engines

Consulting-Specifying Engineer - August 2007

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