CASTING INNOVATIONS
Nitrogen Delivery System Slashes Cost for Automotive Metalcaster Tis year, Honda
of America Mfg. Inc. is celebrating the 30th year of operations for its manufacturing facility in Anna, Ohio, the com- pany’s largest automotive engine plant in the world. With complete melting, casting, machining and heat treatment capa- bilities, the Anna Engine Plant (AEP) produces a variety of components, using domestic and globally sourced parts, for Honda’s new V-6 Earth Dreams Technology Engines, including cylinder sleeves, connection rods, camshafts and crankshafts. In its production of cast components, AEP uses a significant amount of nitrogen for isothermal annealing and ferritic nitrocarburizing. Te facility also uses nitrogen as a pressurizing gas during pouring and as a blanket gas to prevent oxidation during heat treatment. AEP was using 72 million cu. ft. of
nitrogen per year from an 18,000-gallon liquid tank, which was filled three times a week. Te annual cost of this liquid nitrogen system—including tank rentals, hazardous material charges, delivery fees and the cost of liquid nitrogen—ex- ceeded $250,000. Recently, engineers began investigat- ing possible upgrades to the nitrogen delivery system to improve performance, reduce consumption and minimize maintenance. First, the team had to choose between the two types of com- mercial nitrogen generating systems: • Membrane separation mechanically separates nitrogen from oxygen and other molecules without a chemical process with a system including an air compressor, dryer, filters, pre-storage tank, nitrogen membrane and nitrogen storage tank.
• Pressure swing adsorption (PSA) sys- tems are vessels filled with a carbon molecular sieve that is pressurized with air. Oxygen, carbon dioxide and other molecules are captured while nitrogen is drawn into a receiving
The schematic for updated nitrogen system includes a compressor, air dryer, generator and nitrogen receiver tank.
tank. Depressurizing the sieve bed then flushes the trapped gases and regenerates the sieve. Honda engineers chose to pursue the
installment of a PSA system because of its longer life expectancy, increased flow rates and a potential return on investment of two years. Honda selected to partner with its vendor based on its two-year system warranty; 24-hour technical support; performance certi- fication of the system purity, flow and pressure requirements; and the quality of the sieves in its systems. A review of Honda’s compressed air
system determined there was enough open capacity for the nitrogen genera- tor’s needs. An investment in a com- pressor system wasn’t necessary, which reduced overall costs and maintenance concerns. Te project then was quoted utilizing Honda’s shop air system, though a filter and refrigerate drying system needed to be added to ensure air quality. Te nitrogen quality verification was integrated into the system via an oxygen analyzer. Te final consideration was achiev- ing 100% uptime because the PSA sys- tem would shut down in the instance of a power outage and the compressed air feed would be too much for a back-up generator. Engineers re- tained the liquid nitrogen tank as a backup system. Te PSA system then was placed in line between the liquid nitrogen tank and the nitrogen users. If the nitrogen generator went offline
or failed to meet the nitrogen supply needs, the pressure would drop and an inline pressure regulator would supply nitrogen from the liquid nitrogen tank to provide 100% uptime reliability. Te last step prior to installation
was evaluating the business case for a change to the nitrogen system. Te case would be evaluated against a SEQCDM model: • Safety: Te back-up system functioned correctly 100% of the time with no nitrogen outages experienced.
• Environmental: Te average daily tank draw dropped from 18.8% to 0.5%. Liquid nitrogen deliveries went from three times a week to once or twice a year.
• Quality: Gas quality goal was met and maintained.
• Cost: Compressed air usage was monitored and was found to meet the 4:1 ratio that was expected. Te cost reduction was determined to be 76%.
• Deliverables: All purity, flow and pressure requirements were met and maintained in service.
• Morale: No maintenance was added. Monitoring of the system is performed once a day and re- corded on a check sheet by Honda associates.
Tis article is based on the paper, “Industrial Applications for Generated Nitrogen Gas at Honda of America, Mfg. Inc.” by Aaron Flesher, Honda of America, and Daniel H. Herring, Te Herring Group Inc.
September 2015 MODERN CASTING | 43
Courtesy of South-Tek Systems,
southteksystems.com.
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