Public Report for ESA-155-2 FINAL
Company Plant Product United States Steel Lorain Tubular Division Seamless steel tubing ESA Dates ESA Type ESA Specialist August 6-8, 2007 Process Heating David Schwam
Brief Narrative Summary Report for the Energy Savings Assessment:
Introduction: U. S. Steel Lorain Tubular Operations (LTO) is situated on approximately 270 acres along the Black River in Lorain, Ohio. It is one of the largest suppliers of seamless steel pipe products in the world. These high performance pipes are used primarily in oil drilling. The facility consists of two operating mills: the No. 4 Seamless Mill utilizes a Mandrel Mill and Stretch Reducing Mill to produce quality seamless pipe from 1.900 to 4.500 inch OD. The No. 3 Seamless Mill utilizes Plug Mills and a Rotary Expanding Mill to produce quality seamless pipe from 10.625 to 26.000 inch OD. Lorain Tubular Operations has a total annual production capacity of over 690,000 tons of finished product. Round billets (solid cylindrical steel bars of varying diameters, lengths, and chemistries) are heated and formed into seamless pipe of varying diameters and lengths. Each mill is equipped with a large rotary hearth furnace. The Rotary Hearth Furnace in Seamless Mill #3 heats the billets to proper piercing temperature. The furnace hearth is donut shaped with an outside diameter of 100 feet and a hearth width of 208 inches. It is a gas-fired furnace with a heating capacity of 85 tons per hour. The billets traverse through five heating zones and one soaking zone during the heating cycle. Each zone within the furnace is computer controlled and monitors fuel usage, air/fuel ratios, temperature set-points, and furnace pressure. Furnace zone temperatures are increased in each successive heating zone as the billet is heated to the desired piercing temperature. Zone temperatures vary between 1850° and 2400° Fahrenheit. The billet temperature varies between 2100° and 2225° Fahrenheit depending on its specifications. Typical billet heating times are from 15 to 20 minutes per inch of billet diameter. The heating and delay management system is computer controlled. The Rotary Hearth Furnace in Seamless Mill #4 is smaller in size but operates in a similar fashion. Both #3 seamless and #4 seamless rotary furnaces have recuperators. Two reheat furnaces are used when it is necessary to maintain temperature uniformity or for temporary in-process storage in case of downstream process interruptions. These are two-zone furnaces, controlled and monitored by the same computer system used at the billet heating operation. The tubes are charged and discharged from the furnace using mechanical pusher mechanisms. Tube exiting temperatures are between 1850° and 2000° Fahrenheit. Furnace residence time is minimized. The furnace is computer controlled for zone setpoints, actual zone temperatures, air/fuel ratios, and furnace pressures. A furnace piece tracking system informs the operator of the number of pieces in the furnace. Finally, a new, highly efficient austenitizing furnace, a gas-fired furnace used for two functions, to uniformly reheat as-rolled pipe prior to sizing and to uniformly reheat pipe for quench and tempering to above the upper critical temperature (fully austenitized). Tubes for heat treating will exit at a temperature of approximately 1600° to 1650° Fahrenheit. The furnace is computer controlled for zone set points. Objective of ESA: raining members of the Energy Team in the use of PHAST software; identify T energy saving opportunities.
Focus of Assessment: Process heating
Approach for ESA: Modification of the reheat furnaces offers the most significant saving opportunity therefore were the focus for this assessment. After a general introduction to Process Heating and the PHAST software, the participants collected data from Reheat Furnace #2. The data was entered into PHAST and subsequently used to demonstrate the capability of the software as well as the potential opportunities for energy savings.
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General Observations of Potential Opportunities: - Note what you would expect would be Near Term, Medium Term, Long Term opportunities. See definitions below:
Near term opportunities would include actions that could be taken as improvements in operating practices, maintenance of equipment or relatively low cost actions or equipment purchases.
The main opportunity that was identified is installation of doors on Reheat #2 and Reheat #1 and reduction of the excess air. According to PHAST keeping the doors closed 70% of the time and reducing excess air from 15% to 2% could cut the natural gas consumption by 2/3. This translates into annual savings of about 24,000MMBtu for Reheat #2. These savings could be roughly doubled if Reheat furnace #1 was modified in a similar manner.
Medium term opportunities would require purchase of additional equipment and/or changes in the system such as addition of recuperative air preheaters and use of energy to substitute current practices of steam use etc. It would be necessary to carryout further engineering and return on investment analysis. Long term opportunities would require testing of new technology and confirmation of performance of these technologies under the plant operating conditions with economic justification to meet the corporate investment criteria.
- Estimate, if possible, % plant natural gas savings from a) Near Term opportunities:2.5%; b) Medium Term opportunities c) Long Term opportunities.
Management Support and Comments: DOE Contact at Plant/Company: (who DOE would contact for follow-up regarding progress in implementing ESA results…)
Mr. John Bilz
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