ENGINEERING, SUPPLY AND SUPERVISION

ELBE-STAHLWERKE FERALPI GMBHFirst waste heat boiler applied on an electric arc furnace.

THE PROJECTThe Feralpi Group, continuously striving to improve the operations in productivity, energy effi ciency and environmental performance of its facilities, started considering the possibility to install a waste heat recovery system with power production at one of their electric steelmaking plants back in 2008. The objective was to further im-prove energy effi ciency of scrap based steelmaking, lowering theEAF specifi c electric energy use and CO2 emissions, with no re-duction in overall plant availabil-ity and no additional personnel cost.

OUR SOLUTIONThe fi rst iRecovery system instal-lation with the heat recovery for the complete waste gas line; downstream the steam generat-ing waste gas duct a horizontal type compact waste heat boiler is connected. Special focus of this project is the cooling speed inside the waste heat boiler, which is in parallel to the existing quenchingtower, in order to avoid de novo synthesis (recombination of dioxinsand furans).

The boiler is equipped with econo-mizer, evaporator and superheat-er bundles. Superheated seam

is required to avoid condensation in a 1.500 m long steam pipe line to an external consumer. During tapping (when no thermal power is coming from the furnace) an electrical superheated takes over the task.

The produced steam is brought to two different consumers. One part is used in a nearby tire plant.

The process steam produced in natural gas fi red boiler is replaced by the steam coming from the melt shop. The remaining steam is con-verted in an ORC (Organic Rank-ine Cycle) into electric energy.

ABOUT THE CUSTOMERESF Elbe-Stahlwerke Feralpi GmbHproduces reinforcing steel in the form of bars and coils.

The ESF steel plant consists of a steel-shop for steel billets as semi-fi nished product and a hot rolling mill for further processing of steel billets to re bars and coils. ESF produces up to 1,000,000 metric

tons of Steel billets and up to 800.000 tons of reinforcing steel per year.

The feedstock for steelmaking at ESF is steel scrap, which is mel-ted in an Electric Arc Furnace at approximately 1.600 °C to raw iron that is cast to billets in a continuo-us casting machine. The hot rol-ling mill includes a walking beam

furnace that reheats the steel billets up to rolling temperature of approximately 1.200°C.

The reheated billets are passed to the rolling mill that can either pro-duce round steel or wire rod by varying number of rolling stands, cylinders and choosing different paths of cooling and tying (as coilsor bundles).

Tenova Metals Deutschland GmbH Am Lichtbogen 29 – 45141 Essen, Germany www.tenova.com

FACTS AND FIGURES:

CONTACT ATTENOVA METALS DEUTSCHLAND GMBHAm Lichtbogen 2945141 Essen, GermanyFon: +49(0)201/1891 729Fax: +49(0)201/1891 470servicegermany@tenova.com www.tenova.com

ENGINEERING, SUPPLY AND SUPERVISION

Furnace type: 100 t/h EAF

Heat recovery system: ECS Duct + Waste heat boiler

Average steam production: 30 t/h

Operating parameters: 29 – 42,5 bar(g); 234 – 255 °C

Consumer: External industrial consumer; ORC module

Electric power generation: 2,6 MW

Start-up: 2014

CUSTOMER`S ADVANTAGEApart from the main advantage of transforming waste energy into usable energy the iRecovery® sys-tem has more positive operation aspects:

• Normal working temperature at the internal surface of the off gas duct and waste heat boiler bundles is high and far above dew point; therefore ducts and heat exchangers are protected against acid corrosion.

• All cooled parts are continuous-ly at the same nominal temper-ature or exposed to a low vari-ation of temperature. Constant, uniform temperature minimizes thermal mechanical stress.

• Through the evaporation of water, the system absorbs easily energy peaks