Cogeneration with ORC at Elbe-Stahlwerke Feralpi EAF Shop Bause T. Pelz T. Monti N. Campana F. Filippini L. Foresti A. Elbe Stahlwerke Feralpi Riesa, Germany Founded in 1968, Feralpi group produces 5 Mtons of steel per year and employs 1,300 people in Italy, Germany, Czech Republic, Hungary and Romania • Long tradition of steel production in Riesa (since 1843) • Riesa steel plant acquired by Feralpi Group in 1991 • EMAS (Eco Management and Audit Scheme) certification since 2012 2 Elbe-Stahlwerke Feralpi, Germany: Product and Technology ESF Elbe-Stahlwerke Feralpi GmbH produces reinforcing steel in the form of bars and coils Steel shop for steel billets as semi-finished product (up to 1 million tons of steel billets) Hot rolling mill (up to 0.8 million tons of reinforcing steel per year) Why heat recovery system for electricity production ? In Europe the price of energy is very high and CO2 reduction targets have been set by the EU Electricity costs are a significant part of the mini mills final product costs1 Heat recovery to power means: Improve energy efficiency of the industrial plant Lower specific cost of final product Zero CO2 emissions electricity production Environmental friendly image for the company (1) 6 - 8 % according World Steel Dynamic data 4 Energy flow of typical EAF today Electricity Fossil fuels Metal oxidation** 361 (50%) 221 144 (30%) (20%) 726 (100%) 49 455 (62%) 197 (7%) (27%) Off gas and dust Water cooling 13 (2%) 12 (2%) Other Electrical losses losses EAF off gas typically represents more than 25% of the total energy input Liquid steel and slag Typical energy balance for top charged scrap based EAF (Tenova) 5 Heat recovery system: objective Lower energy cost through an heat recovery system with no additional personnel Power Cooling system Thermal user Industrial heat recovery source Heat to power system Saturated Heat carriersteam loop 6 Task 1: Heat to power system choice Steam Turbine Temperature Temperature Organic Rankine Cycle (ORC) Entropy Entropy Thermodynamic features • • • High enthalpy drop Superheating needed Risk of blade erosion • • • Small enthalpy drop No need to superheat No risk of blade erosion Operation and maintenance costs • • • Water treatment required High skilled personnel High pressures and temperatures • • • Non oxidizing working fluid Minimum personnel Completely automatic Convenient for plants > 10 MWe Low flexibility Lower performances at partial load • Other features • • • High flexibility and good performances at partial load Well proven in industrial heat recovery • 7 EAF Task 2: heat carrier choice Heat Exchanger ORC Thermal oil Hot water Saturated Steam High ORC efficiency Simple technical solution Medium ORC efficiency (up to 24 % due to high temperature , 600 F) (low temperature, no change of phase) (~20 % with 380 psig steam) Reliability Many application in ORC (wide spread solution in ORC based heat recovery systems) (waste to energy, geothermal plants, etc.) Flammable Lower ORC efficiency (e.g. 16% with 350 F hot water) Steelshop operators usually not familiar with thermal oil Thermal user Complex system (e.g. water quality control) Steam engineer necessary Drivers for ESF choice: Need of saturated steam for nearby Goodyear Dunlop Tires plant Good experience of EAF steam heat recovery system at GMH steel shop (Tenova-Germany) 8 Turboden ORC references worldwide Application Wood Biomass Geothermal Combined cycle (bottoming of steam turbines or reciprocating engines) Size MW 0.3 - 6.5 1.0 - 6.0 0.5 - 4.5 Plant in Operation no. MW 201 214 6 19 12 13 Industrial Heat Recovery (Cement, Glass, Steel, etc.) 0.5 - 7.0 7 16 Waste to Energy 0.5 - 6.0 4 10 230 272 Total Turboden Plants Heat carrier • Thermal oil • Hot water • Thermal oil (10) • Direct heat exchange (2) • • • • • • Thermal oil (4) Hot water (1) Saturated Steam (1) Direct heat exchange (1) Thermal oil (3) Hot water (1) Last Update: April 2014 9 ESF: Waste Heat to Power scheme Electric Arc Furnace (EAF) Reduce consumption Electric energy Exhaust gases Heat exchangers + steam drum 67% ORC 3 MWe Start up: December 2013 33% ~ 30 t/h steam Industrial thermal user 10 ESF: Waste Heat to Power layout 0 Thermal user: tire plant Steam and condensate return pipeline ORC Unit 0 Steel Shop Distance between steel shop and thermal user: 0.8 miles Evaporative Cooling System ESF: European Union support ESF obtained a small contribution from EU to develop a demonstrating plant for an innovative ORC application First heat recovery to power system from EAF Further development of steam based EAF off gas technology proven at GMH adding a Waste Heat Boiler (convective section) First ORC in steel industry fed with saturated steam CO2 reduction in electric steelmaking EAF EAF Heat Recovery: EAF Design Data Heat Exchanger ORC Heat source Steel production EAF process off-gas 1,000,000 metric tons per year Heats per day (average) 32 EAF hourly production 133 metric tons per hour Tapping weight Tapping temperature Charge weight Average off-gas temperature (core temperature ex EAF) Average off-gas flow rate 100 tons 1600°C (2912°F) 113 tons 1100°C (2012°F) 100,000 – 140,000 Nm3/h Thermal user EAF EAF Heat Recovery: EAF Melting cycle Heat Exchanger ORC Melting Phase 1st scrap bucket charging Melting 2nd scrap bucket charging Melting 3rd scrap bucket charging Melting & refining Tapping & repairing Power-On [min] Power-Off [min] AVG Power [MW] 2 70 10 Thermal user 3 10 70 3 13 7 70 - Values for the fume treatment and waste heat to power system design: • Tap-to-tap time: 48 minutes • Longest Power-Off time: 11 minutes • Average Power during Power-On: 70 MW • Total Power-On time: 33 minutes 14 EAF EAF Heat Recovery: Evaporative Cooling System (1/4) Heat Exchangers ORC Losses Electricity + Fossil Fuels + Metal Oxidation Electric Arc Furnaces Metal Scrap Melting Fumes Radiation Heat Exchanger Fumes Convective Heat Exchanger Fumes Baghouse Filter Stack Steam Steam Steam accumulator Electricity Steam ORC Water cooling Steam Thermal users Thermal user EAF EAF Heat Recovery: Evaporative Cooling System (2/4) Heat Exchangers ORC Steam Drum Feed Water Tank Steam Accumulator Evaporative Cooling System Thermal user EAF EAF Heat Recovery: Evaporative Cooling System (3/4) Heat Exchangers ORC Minimum steam data at steam drum 228°C – 27 bar(a) (442°F - 380 psig) Nominal steam data at steam drum 247°C – 38 bar(a) (477°F – 535 psig) Maximum design steam data at steam drum 252°C – 42 bar(a) (486°F –590 psig) Feed water pressure at steam drum inlet Water content cooling system (pipes + tank) Capacity of steam accumulation of cooling system Steam drum glide upper limit Capacity of steam accumulator (water content) 45 bar (640 psig) approx. 37 m3 1442 kg 19 bar (260 psig) 76 m3 Thermal user EAF EAF Heat Recovery: Evaporative Cooling System (4/4) Heat Exchangers ORC Waste heat steam generator rendering and installed equipment at ESF plant, Riesa Thermal user EAF EAF Heat Recovery: ORC power unit (1/2) Heat Exchangers Thermal user ORC Heat recovery system supplier ORC supplier Hot source Inlet thermal power to the ORC Steam temperature In to ORC Condensate temperature Out from ORC Thermal power to the cooling water Cooling water temperatures (in/out ORC) Tenova (Comeca subcontractor for heat exchanger parts) Turboden Saturated Steam at 27 bar(a) (380 psig) 13,517 kW 228÷245°C (442÷473°F) 100°C (212°F) 10,640 kW 26°C / 44°C (79°F / 111°F) Gross electric power output 2,680 kW Net electric power output 2,560 kW EAF EAF Heat Recovery: ORC power unit (2/2) Heat Exchangers ORC Turboden unit installed Thermal user Project timeline Dec. 2011: ORC Order 2011 Feb. 2013: ORC delivered at ESF waiting for EAF annual maintenance shutdown 2012 2012: ORC components design, manufacturing and assembly Aug. 2013: - convection heat exchanger installed - ORC cold test 18th Dec. 2013 ORC first parallel 19th Dec. 2013 nominal power (2.6 MW) achieved 2014 2013 Jun. 2013: ORC cabling and erection completion Nov. 2013: radiation heat exchanger installed June 2014 Expected end of commissioning 2014: commissioning First start up result TT100 = Steam inlet temperature 225°C 2,671 kW GEN POT Gross electric Power 410 m3/h 20 ton/h HWF =Cooling water flow HCP = Steam flow 100% Nominal power output achieved Conclusion ESF experience confirm validity of EAF off gas treatment with steam based heat recovery and ORC power unit Revenue from heat (steam) supply important for economics in Riesa We open the way for future development in EAF heat recovery with ORC with a particularly challenging application Thank you for your attention [email protected]
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