Annealing

plex and time-consuming task for an-nealing operators. Entec’s Stacking Model simplifies load-building by al- lowing customers to specify multiple stacking criteria, which are incorpo- rated into the load-building decision algorithm. Typical criteria include maximum coil overhang, allowable cy- cle mixing, and specific equipment or practices for particular products. Also, operators can subdivide the inventory depending upon the current shop con- ditions.The Stacking Model uses an optimi-zation routine to minimize the heating time difference between coils in the load. It also maximizes stacking height, and expedites the most critical coils without violating the shop rules. Stack weights are balanced for multi-stack bases to minimize burner trimming. The use of the Stacking and HeatingModels together make it possible to mix coils of different cycles within one charge. The Stacking Model arranges the coils into the proper positions, and the heating model calculates the chargesetpoints and time to meet the require-ments of each coil.The Heating Model uses annealing-process thermodynamics to determine each coil’s interior temperatures. Radi- ation, conduction, convection, and other components of the process are all modeled for the specific equipment and product in the shop. The hot-spot and cold-spot temperatures of each coil are used to make control decisions. Because every coil of every chargeis analyzed, a closer estimate of the re- quired annealing time is provided. When the model determines that the last coil has met the required anneal- ing temperature, the furnace is auto- matically shut off. This use of the pre- dicted interior temperature producesshorter cycles over traditional soak-type recipes. Shorter cycles mean less furnace fuel is burned—typically the largest utility cost in a batch anneal shop. Less electricity and less atmos- phere gas is used as well. And, the ad- ditional productivity can offset any perceived need for additional anneal- ing equipment. The Cooling Model uses a similarapproach to determine when the an- nealing base can be unpacked. Un-packing the annealing base as soon as the cooling phase has been completed can greatly increase shop throughput while having no negative impact on quality.

CSI REPORTS RECORD QUARTER

n mid-October, California Steel Industries reported its best quarterly resultsever, with net income of $46.1 million on sales of $388.6 million. Quarterly ship- ments of 557,980 net tons are second only to the 566,630 tons shipped in thefirst quarter of 2004.Located in Fontana, CA, CSI is the leading producer of flat-rolled steel productsin the western United States (i.e., the 11 states west of Rockies) based on tonnage billed, with a range of products that includes hot-rolled, cold-rolled, electric-resist- ant-weld pipe, and galvanized coil and sheet. CSI processes steel slab purchasedfrom suppliers around the world, including Brazil, Australia, Japan, Mexico, SouthAfrica, China, Europe, as well as the U.S. It employs about 1,000.By October, year-to-date sales were $910.2 million, on shipments of 1,654,571tons, for a year-to-date net income of $74.2 million. Shipments were 18% higher than in the comparable period in 2003, with net sales running 59% higher. Net in-come also rose significantly.“As with the first half of this year, we continue to be pleased with our results,”commented president and CEO Masakazu Kurushima, who admitted that favorable market conditions had much to do with the record results. CSI realized average sales price increases of 29% compared to second quarter 2004, and of 86% com-pared to third quarter 2003, indicative of the steel market conditions. CSI also ben-efited from higher levels of sales for ERW pipe products. But, Kurushima also credited operating efficiencies and an outstanding team ofemployees for achieving the best quarterly results ever. CSI sits on 450 acres, with approximately 115 acres under roof, about 50 mileseast of Los Angeles.The plant includes an 86-in. hot-strip mill, hot-rolled strip finishing facilities(build-up, shear, and slitter lines), a 62-in. continuous pickling line, a five-stand cold-reduction mill, two hot-dip galvanizing lines, cold-rolling equipment of an-nealing and tempering mills, and an electric-resistance-welded pipe mill.In 1993, the company began a capital expenditure program of some $250 millionto modernize and add operations. Investments included a new walking-beam reheat furnace in the hot-strip mill, a complete modernization of the five-stand cold-reduc- tion mill, and construction of the No. 2 continuous galvanizing line and 62-in. con-tinuous pickle line. Later, CSI completely upgraded its annealing capability by in-stalling the 100% hydrogen anneal shop.

Cleanliness and sticker breaking

Managing Anneal Cycles for More Profit - 21809 I

The Cleanliness Model uses the hot-spot and cold-spot data that are dynam- ically calculated by the Heating model to control processing of each run. The gas stream setpoint is controlled to maintain a hot-spot temperature below the “cracking” temperature of the rolling oil used in cold reduction. The base is held at the hot-spot temperature until the cold spot for that step is reached, indicating that all the oil has been properly volatilized. Most shops use a given practice across their entire facility, regardless of coil weight, coil gauge, load size, or other factors. This practice works, but does not optimize the process. Sticker breaks are characterized bylocalized welding of two strip surfaces within a strip coil, leaving a crescent shaped surface defect. The breaks may be caused by a number of factors, such as strip profile, winding tension, sur- face roughness, or annealing practices. The Sticker Break model uses the ther-modynamic model engine to provide aprofile of temperature gradients during the cycle. This thermodynamic infor- mation is necessary to determine the best control strategy. Typical parame- ters, such as base fan speed, cooler fan speed, bypass cooling rate, and spray water initiation, are controlled in order to maintain an acceptable temperature gradient. Although all of the causes are not related to annealing, modified oper- ation of the annealing equipment can reduce the occurrence of breaks from other factors.

Shop optimization

Entec’s Shop Optimization Modeluses a Global Planning module and a Shop Planning module to maximize throughput. This provides a complete system for optimizing throughput and operating costs in the annealing shop.The Global Planning module maxi-mizes throughput by providing a com- prehensive equipment utilization strat-egy for the shop using a constraint- management methodology. The opti- mization routine considers upstream“supplier” capabilities, downstream“customer” requirements, shop infor- mation, and data from the Budgeting Application. Output from the Global Planning module includes information on the constraint resource, equipment utilization, and loading strategy for the Shop Planning module.The Shop Planning module uses theinformation provided by the Global Planning module to make operating decisions. This module schedules spe- cific charges and equipment for the shop. Charges are built out into the fu- ture and coil load and unload times areestimated for the inventory. The opti- mization routine maximizes through- put by exploiting the constraint re- source of the anneal shop, asidentified by the Global Planning mod-ule. For example, if a shop constraint is the furnace, then the optimization routine will manage all other re- sources to prevent any furnace delays.Other modules offered include theLab Management module, for collect- ing metallographic and mechanical property data during sample prepara- tion and testing; and a Reports module that adds many reports to the existing list of CAPS reports.

The CAPS package’s stacking model uses an optimization routine to minimize heatingdifferences between coils during the annealing cycle. Circle 125on Info Request Card