Roller Hearth Furnace for Thin Slabs
Roller Hearth Furnaces are the most effective solution to connect a thin slab caster to the finishing mill achieving the highest production and the best energy efficiency.
Today even more efficient than before thanks to Digital Solutions, New algorithms and Innovative AI models for increased sustainability and profitability of furnace system
Overview
In a new mill layout for strip production, the Roller Hearth Furnaces are the most used solution in which a thin slab caster and finishing mill are connected by an inline tunnel furnace thus achieving the highest production and the best energy efficiency.
The tunnel furnace serves three key purposes. First, the furnace provides a means to convey the thin slabs from the continuous caster to the rolling mill. To accomplish this, the furnace enclosure incorporates in-furnace rolls that are designed to withstand the hot furnace temperatures of 1150 °C to 1220 °C.
Second, the tunnel furnace heats the hot charged slabs to the desired hot rolling temperature. Having just been cast, the thin slabs are generally charged into the furnace at temperatures between 850 °C and 1050 °C and are discharged to the rolling mill at 1150 °C to 1200 °C. Compared to Hot Strip Mill with re-heating furnace, the combination of a hotter charge temperature and a cooler discharge temperature make this layout particularly energy efficient. The hotter charge temperature is due to the close coupling with the caster.
Finally, the furnace is used to provide a buffer between the continuous caster and the rolling mill, so that the caster can continue to cast new steel even while the mill is unavailable due to scheduled or unscheduled delays. For this reason, the furnace is designed with sufficient length that it can store slabs along its length in an oscillating mode, until the rolling mill can once again start processing the slabs.
Combustion systems and burners are specifically designed for a wide variety of fuels, including those ones having a poor Net Heating Value (such as BFG, PG, MG). The use of those fuels optimizes the usage of available utilities and resources at customer’s plant, minimizing the operating costs and improving the overall sustainability.
Technical data
- High productivity: One and Two lines
- Specifically designed depending on the steel grades processed: Low/Medium Carbon Steel, Stainless Steel.
- Slab lengths: 5.000 till 50.000 mm
- Slab thickness: 45 till 90 mm
- Slab width: 800 till 1650 mm
Benefits and profitability
- Low fuel consumption
- Improved reheating quality through buffer handling logic and combustion optimization
Improved Automation between handling logic and heating in accordance with swivel or shuttle solution.
- NOx and CO emissions according to Best Available Technologies
- Tenova in-house developed burner to cope with process requirement and to enhance sustainability
- Hydrogen and hybrid combustion
- Combustion system and burners specifically designed for a wide variety of fuels, including those ones having a poor Net Heating Value such as BFG, PG, MG.
- High plant availability
- Limited oxide scale formation
- Off-Line Roll Cleaning function (patented)
Innovation
Tenova is on the forefront of the innovation: dedicated teams are involving experts for continuous development of advanced equipment, software solutions and models.
All the equipment are designed and verified under dynamic conditions, which simulate the actual operating condition at plant.
- Tenova in-house developed software suite for
- 3D heating process modeling
- Slab properties predictions
- Mechanical and handling design
- Combustion system design
The results have been validated through the years by dedicated tests and field data collection assuring the reliability of the software’s tool.
The online mathematical model Level 2 System is a powerful tool for protecting the environment and raising the gains and the final product quality, by:
- A decrease in fuel consumption by promptly adapting the combustion rate to any production rate
- A decrease in NOx and CO2 emissions
- A decrease in scale production with a valuable effect on product quality and quantity
- A precise control of the required dropout temperature with a massive impact to the rolling mill performance
Tenova has a long tradition in leading edge combustion technology and developed an interdisciplinary design process including Computation Fluid Dynamics (CFD) modeling, industrial scale test and industrial applications.
The above mentioned workflow allows to drastically reduce the time to market for the development of new burners and combustion system.
The Italimpianti furnace department hosts a team of refractory experts which are fully committed to continuously improve the furnace lining performances and reliability by dedicated material selection, relevant engineering, test on field and the release of Tenova’s pre-casted pre-fabricated components.
Safety
Safety is a priority for Tenova. For this reason, the Safety team is directly involved during the engineering and the execution of all the jobs. It performs risks assessment and reduction measures identification detailed processes.
In order to assure the safety of personnel and the protection of the machinery the following solutions are applied:
- Design of machine done to integrate safety solution
- Area segregation (Fixed Fence, interlocked moveable guards with guard locking).
- Safety Automation control with adequate protection against systematic and random faults (Input, Logic and Output of the command circuits compliant to adequate Performance Level)
- Other Specific reduction measures relevant for the identified risks level.
- Information on Residual Risks by means of Safety Instruction, Safety Warnings signs, etc.
Tenova design can be customized and adapted to local safety regulation for manufacturer (EC Declaration of conformity, EAC Declaration of conformity, OSHA 1910, etc.) and relative standards, e.g. (EN, EN ISO, NFPA, etc.)
Automation
Next generation HMI including the following features:
- User-friendly and intuitive HMI with point and click devices
- Diagnostic features allow to immediately recognize the failure and quickly navigate to the failed equipment
The virtualization of the architecture allows the end users to get the following advantages:
- Drastically increased energy savings
- Drastically reduced downtime in case of HMI client substitution
- Get the High Availability (HA) feature for all the servers and all the clients of the while automation architecture
Safety PLC and Safety Field Equipment as implementation of a detailed risk assessment study, that includes:
- Safety functions identification
- Performance Level / SIL assessment
- Safety Function specification
- Verification and validation process
Environment
Energy transition trends push for the steel industry to start decarbonization as soon as possible, besides pollutant emissions have to be considerably reduced. These technical goals are embraced by Tenova with a dedicated Burners Department which through innovation provides for sustainable solutions. Hydrogen burners, high efficiency burners, low NOX and low CO burners are some of the key elements of the Tenova Burner product portfolio which can offer a wide variety of solutions to respect the strictest environmental standard, to lower CO2 emissions allowing for a sustainable production.
The Reheating furnace process and related controls by automation system are designed to effectively minimize the utility and resources consumption.
Digital
Tenova Furnace Digital Packages “Tenova FDP” purposely designed for Roller hearth furnaces shift the furnaces from traditional equipment to more efficient and technological production units.
New algorithms and innovative AI models allow for more profitability of the furnace system as follows:
- Higher plant efficiency
- Reduction of costs related to Fuel
- Improve sustainability
- Condition Monitoring Systems for maintenance
From the synergy of Tenova Digital Teams, IT Teams and domain experts, the Virtual Reality approach is now part of the Tenova job execution from sales and engineering activities till the final user dedicated operation and maintenance training sessions.
Tenova is able to provide for the Real-time navigation for model up to 250 Milions of polygons allowing users to interact with virtualized equipment and machines. The interactive experience can be shared with other teams remotely connected from customers and partners offices or from dedicated VR Rooms available at several Tenova’s offices worldwide.
Tenova adVISOR is your remote mentor on site, guiding you through our experts´remote support, interactive documentation and the use of artificial intelligenc algorithms on real time automation data.
Related Solutions
