Fluid Fine Tunes VOC Heat Recovery
	It takes arresting design and lively colors to move consumer goods packaged in paperboard boxes from supermarket shelves to shopping carts. The Jefferson Smurfit plant in Stone Mountain, Ga., should know. It prints tons of eye-catching, high consumer appeal paperboard annually. The paperboard is run through eight different presses, each with a different ink or coating. Approximately 450 cartons are converted every minute on 55-in.-wide web presses. To avoid smudging, the inks and coatings printed on each pass must be dried almost instantly. A year ago, the plant redesigned and improved the process whereby the solvent-laden exhaust gases from its printing presses provide the energy required to heat the dryers. A heat recovery process designed by Thermo Wisconsin using Paratherm heat transfer fluid generates about 85 percent of the hot air needed to dry the printed paperboard. Organic solvents facilitate the high-speed drying of the inks and coatings used by JSC, but federal and state regulations limit the release of VOCs to the environment. The best solution for JSC is to burn them. The system starts with the ductwork at the top of the eight printing units designed to capture the VOC-laden gases and send them to a Thermo Wisconsin Titan recuperative thermal oxidizer (Model 2270). The 150°F incoming gases are preheated to 1,000°F by the primary heat exchanger. At that point, they pass through the burner where processed VOCs and natural gas are used to increase the temperature of the gases to the desired combustion temperature. Once VOC oxidation is complete, the gases are returned to the primary heat exchanger at 1,400°F to preheat newly arriving VOC-laden gases. The clean air then leaves the oxidizer and enters an air-to-oil heat recovery coil, which extracts energy from the clean oxidizer exhaust gases and uses it to heat thermal oil. The thermal oil is then returned to the process dryers, supplying nearly all of the heat required. JSC selected Paratherm NF® as the heat-transfer fluid for the new system because of its environmental and safety characteristics. "We did not want a big clean-up problem if there was a leak or spill," says Melvin Johnson, plant engineer. When the VOC capture system was designed by Thermo Wisconsin, the physical properties of the NF fluid were used to calculate heater size, pressure drop and other system design considerations. The ink drying application required heat-transfer fluid heated to 400°. The NF fluid is "nonfouling" and will not cause hard carbon formation to build on heated surfaces - even when overheated. Moreover, it reportedly has one of the lowest viscosity ratings of any high-temperature heat-transfer fluid. This becomes increasingly important when the primary heat-transfer fluid loop is a long one - such as at JSC. Johnson says the Paratherm NF® fluid is performing well and passed the company's regularly scheduled testing and evaluation with consistently high marks. A Thermo Wisconsin oil economizer is installed in the stack of the thermal oxidizer. When supply temperatures fall below required levels, reserve is provided by a fully modulating 6 MM Btu/hr thermal fluid heating system. All temperatures are controlled and monitored at each press by CNC controls outside the pressroom. The air heated for the drying operation is drawn from ambient air in the plant. Return to page index From Converting Magazine, November, 1998.
	Recommended Hot Oil System Components
	In designing and constructing a thermal oil system, attention must be paid to the selection of appropriate components. If care is not taken, poor operation, system failure and fires can result. Pipe Welded and flanged throughout. Specify schedule 40 ASTM A 106 Grade B seamless carbon steel tubing. We strongly recommend the use of materials and methods to minimize entry of weld spatter and slag into the pipe, and to assure strong and leak-free welds. Pipe should be free of mill scale, welding flux, quench oils and lacquers. Note: Threaded connections are NOT recommended.1 Do NOT use copper or copper bearing materials in hot oil systems. Flanges/Fittings Must be rated for 600°F (316°C) service. For optimum service we recommend 300 lb. forged steel, 1/16" raised face, schedule 40 bore (ASTM-A 181). Studs/Nuts Continuous threaded, alloy steel (ASTM A 193, Grade B7), with heavy hex nuts (ASTM A 194, Grade 2H). Gaskets/Packings Flange gaskets: Spiral-wound type (FlexitallicTM, Garlock FlexsealTM, or equal). Valve stem packing: Rings of die formed graphite foil (GrafoilTM PalfoilTM or equal). Pump packing: End (non-extrusion) rings of braided carbon yarn (PalmettoTM #1585, GarlockTM #98 or equal), center (sealing) rings of die-formed graphite (GrafoilTM, PalfoilTM or equal). Elastomeric O-Rings/Seals For service to 400°F (204°C): Fluoroelastomer (VitonTM, FluorelTM) For higher temperature service, specify perfluoroelastomer rubber: To 450°F (232°C): ChemrazTM or equal. To 480°F (249°C): ZalakTM or equal. To 600°F (316°C): KalrezTM or equal. Insulation2 2" thick 900°F (482°C) rated cellular glass (Pittsburgh-Corning FoamglasTM or equal). Heat loss value not to exceed 80 BTU/ft. Valves 300 Ib cast or forged steel, or nodular (ductile) iron3 rated for 600°F (316°C) continuous service minimum, with steel or stainless steel trim (LunkenheimerTM 1110-W1 or equal; WorcesterTM 4446XM or equal ball valves-- specify for thermal oil application). For optimum service, bellows valves may be considered (ARITM or equal). Note: Install valves stem sideward 2 Pumps Centrifugal: Cast carbon steel, carbon/tungsten carbide metal bellows mechanical seals (Dean BrothersTM R-400 or equal); magnetic drive--KontroTM, DickowTM or equal, “canned” (Sunstrand or equal). Positive displacement: Alloy steel, (VikingTM Pump Division or equal). Flexible connections at inlet and outlet should be used. Pressure Gauges/Thermometers Ratings to 100 psi, 650°F (343°C). Temperature range of 300°F to 600°F; thermometers should be calibrated to provide accurate readings in this range. Expansion Joints We suggest you provide for an expansion growth of 4" per 100 ft. minimum. Both loops and joint expansion devices are acceptable. Either must be high-temperature rated and must be considered part of the piping system. Strainers While many systems are supplied with 60 mesh mechanical screens (casings of forged or cast steel), we generally recommend 20 mesh for 1/4" to 3" pipe, and .045" perforations for 4" diameter pipe and above. Strainer Removal Note: In new or significantly remodeled thermal fluid systems, once the "logs" are filtered from the system, many start-up technicians remove inline strainers entirely. They do this to eliminate restrictions that would reduce flow to the heater(s). Reduced flow to the heated surfaces can be the cause of severe fluid overheating and possibly even subsequent system damage. Sealants Customers report satisfactory service with LoctiteTM PST to 400°F, and Fel ProTM HPS Sealer and Jet LubeTM TFW to 600°F. For permanent installations, satisfactory service has been reported with X-pandoTM. Flow Protection Most systems utilize a pressure differential switch to provide a method of shutting the system down when fluid flows drop below set limits. Another method used by some manufacturers is to provide flow switches which control flows independently through each branch of the heater. Some systems are equipped with flowmeters in addition to the pressure differential switches. While this is an acceptable "belt and suspenders" technique, if the heat transfer fluid deteriorates, flow meters can provide false readings. These false readings can result from significant changes in the fluid's physical characteristics that occur with thermal degradation and normal aging. Notes: Contractors must apply all national and local codes for thermal applications. Thermal heater room must be provided with a 2-hour fire rated enclosure. Full pump capacity must be maintained at all times when heater is in operation. 1. Due to the expansion and contraction of components in the typical thermal oil system, and the low viscosity, high lubricity and low surface tension of heat transfer fluids, threaded joints and compression fittings will often leak regardless of the type of sealant employed. We suggest that you back (or seal) weld all threaded connections. Return to Article 2. Hot organic heat transfer fluid permitted to wick through porous insulation will oxidize and decompose at system temperature. This oxidation process creates extra heat. Confined within the insulation, the heat has little chance of escaping. Temperatures within the insulation can rise dramatically, and in some cases will exceed the autoignition temperature of the heat transfer fluid. With the entry of fresh air, there is a hazard of fire (spontaneous combustion.) Repair all leaks, and replace oil-soaked insulation immediately. Mount all valve stems facing sideward, and leave potential leak points un-insulated. Return to Article 3. Ductile iron only. We do not recommend the use of cast iron in thermal oil systems. Return to Article Return to page index
	Ideas for a Cleaner World
	At the office If you're in charge of purchasing office supplies, choose stationery and other office supplies with the maximum post-consumer recycled content available, at least 20%. And buy the lightest-weight paper possible for the job. Publish or distribute documents electronically wherever possible. If you have a web site, make your publications available for viewing and download. Assemble e-mail lists and send an e-mail version instead of hard copies of publications. An added benefit is that e-mailed publications can readily be distributed by the recipient to additional recipients, thereby easily spreading your work. If more than one person needs to look at the same document, when possible, place a routing slip on the document instead of making copies. Ask for cleaner, greener printing. Tell your printers you want a product with minimal environmental impact and work with them to design it. Ask them what they are doing to minimize air and water pollution, energy use, and chemical waste. The more printers hear about your concerns the sooner they will make improvements. For more ideas on steps to conserve forest resources, log on to: www.edf.org/pubs/Brochures/BuyRecycled/b_labels.html Return to page index
	Paratherm's Web Site Makes Top Ten List In Nationwide Study and Awards Program
	Paratherm Corporation has one of the 10 best-designed Web sites among mid-market manufacturers, according to a nationwide study and awards program conducted by RSM McGladrey, Inc. RSM McGladrey is one of the largest accounting, tax and business consulting firms in the U.S., and is a recognized authority on Web site design, presentation and usage. McGladrey recently conducted the Outstanding Web Sites Mid-Market Businesses Study to identify industry Web sites which reflect excellence in content, technique, and execution. The study and awards program were co-sponsored by AT&T and the National Association of Business Manufacturers. For the first annual Outstanding Mid-Market "Manufacturing" Web Site Awards, judges reviewed the web sites of nearly 1,000 manufacturers. In judging the web sites, they evaluated how well the sites met criteria in five major categories considered crucial to developing and maintaining an outstanding presence on the Web. The categories are information, customer service, design and layout, quality, and connectivity. Paratherm's Web site (www.paratherm.com) successfully meets the study's criteria, in part, by ensuring easy accessibility and convenience for the user, including such areas as download time. The Web site judges deemed the information provided on Paratherm's Web pages as timely, accurate and substantial in the quality of its content. Paratherm's Web site includes comprehensive product specifications, technical data comparing Paratherm's heat transfer fluids to competitive products, user benefits, safety and maintenance tips, company news and case histories, company history and other information. The Web site's design allows for seamless navigation to any desired point of reference. Interactive tools are also available to the user, and purchases of heat transfer fluid can be made immediately on-line. Return to page index
	Heat Transfer Fluid Tips (Continued from previous "In The Loop")
	Leak Testing/Prevention Pressurize the system with inert gas and use soap bubble fluids at potential leak points. Heat transfer fluid can leak through gaskets, seals and packing if they're not properly installed. Draining Your System Bring the oil temperature up to about 225°F, and circulate the fluid until you are assured of thorough mixing. At this temperature the fluid will be less viscous, and many solids will be suspended. Thoroughly drain using valves at the system's low points. As the fluid drains, it's best to observe what comes out. If you see chunks of carbon and other solids, you should consider flushing with the heat transfer fluid you intend to use. Call us for additional information. Note: We suggest that you consider cleaners other than water-based types. Water is difficult to remove, and can itself cause corrosion. Charging Your System Connect a small positive displacement pump to a system low-point valve. A convenient place to fill is through the blow-down valve which is many times located on the strainer. The strainer is usually located upstream of pump suction. Bottom-filling can substantially reduce the entrainment of air, a common cause of both pump cavitation and fluid oxidation. And, bottom-filling allows the system to vent normally as the fluid enters. You may wish to consider purging the system with inert gas prior to charging. Inert gas forces the air out, and can assist with the removal of water vapor as well. And once the system is brought up to temperature, inert gas bubbles will not contribute to fluid oxidation. Preventing Oxidation All organic heat transfer fluids--whether natural or synthetic--will oxidize in contact with air. Oxidation can begin as low as 250°F, and will double with every 20°F rise in bulk fluid temperature. Oxidation will cause the fluid to thicken and to become acidic and corrosive. And the fluid can become more susceptible to thermal degradation. If your system is not equipped with a cold-seal tank, and the temperature of the fluid in the expansion tank runs hotter than 200°F, we strongly suggest you consider blanketing the tank with inert gas (nitrogen is inexpensive and readily available). We also suggest that you purge the system with inert gas prior to charging. This, coupled with the inert gas blanket will not only protect the fluid against oxidation, but will assist in keeping contamination and water vapor out. Note: If your system employs a deaerator/cold-seal expansion tank, insulate the deaerator portion only, leaving the remainder bare. Cold Weather Deliveries During shipment, air bubbles can be entrained in the fluid. If the cold fluid is immediately pumped into the system, the air bubbles can cause pump cavitation. It's best that the fluid be as near room temperature as possible prior to charging the system. You might store the drums in a warm room, or employ drum warmers to bring the fluid up to room temperature. The warmer the fluid, the more easily it will flow into your system. Return to page index
	Ask George! Got any questions about the stories featured here, or on our products? Please contact George Wilt at: Tel: 800-222-3611 Fax: 610-941-9191 E-mail: info@paratherm.com Return to page index