Cogeneration with ORC at Elbe-Stahlwerke Feralpi EAF Shop

Transcription

1 Cogeneration with ORC at Elbe-Stahlwerke Feralpi EAF Shop Bause T. Pelz T. Monti N. Campana F. Filippini L. Foresti A.

2 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

3 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)

4 Why heat recovery system for electricity production? In Europe the price of energy is very high and CO 2 reduction targets have been set by the EU Electricity costs are a significant part of the mini mills final product costs 1 Heat recovery to power means: Improve energy efficiency of the industrial plant Lower specific cost of final product Zero CO 2 emissions electricity production Environmental friendly image for the company (1) 6-8 % according World Steel Dynamic data 4

5 Energy flow of typical EAF today Electricity Fossil fuels Metal oxidation** 361 (50%) 221 (30%) 144 (20%) 726 (100%) 455 (62%) 197 (27%) Off gas and dust 49 (7%) Water cooling 13 (2%) Electrical losses 12 (2%) Other 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

6 Heat recovery system: objective Lower energy cost through an heat recovery system with no additional personnel Power Thermal user Cooling system Industrial heat recovery source Heat to power system Heat Saturated carrier steam loop 6

7 Temperature Temperature Task 1: Heat to power system choice Steam Turbine 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 Other features Convenient for plants > 10 MWe Low flexibility Lower performances at partial load High flexibility and good performances at partial load Well proven in industrial heat recovery 7

8 Task 2: heat carrier choice EAF Heat Exchanger ORC Thermal user Thermal oil Hot water Saturated Steam High ORC efficiency (up to 24 % due to high temperature, 600 F) Reliability (wide spread solution in ORC based heat recovery systems) Simple technical solution (low temperature, no change of phase) Many application in ORC (waste to energy, geothermal plants, etc.) Medium ORC efficiency (~20 % with 380 psig steam) Flammable Steelshop operators usually not familiar with thermal oil Lower ORC efficiency (e.g. 16% with 350 F hot water) 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

9 Turboden ORC references worldwide Application Size Plant in Operation Heat carrier MW no. MW Wood Biomass Thermal oil Geothermal Hot water Combined cycle Thermal oil (10) (bottoming of gas turbines or Direct heat exchange (2) reciprocating engines) Industrial Heat Recovery (Cement, Glass, Steel, etc.) Waste to Energy Total Turboden Plants Thermal oil (4) Hot water (1) Saturated Steam (1) Direct heat exchange (1) Thermal oil (3) Hot water (1) Last Update: April

10 ESF: Waste Heat to Power scheme Electric Arc Furnace (EAF) Start up: December 2013 Reduce consumption Electric energy Exhaust gases 67% Heat exchangers + steam drum 33% ORC 3 MWe ~ 30 t/h steam Industrial thermal user 10

11 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

12 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 CO 2 reduction in electric steelmaking

13 EAF Heat Recovery: EAF Design Data EAF Heat Exchanger ORC Thermal user Heat source EAF process off-gas Steel production 1,000,000 metric tons per year Heats per day (average) 32 EAF hourly production 133 metric tons per hour Tapping weight 100 tons Tapping temperature 1600 C (2912 F) Charge weight 113 tons Average off-gas temperature (core temperature ex EAF) 1100 C (2012 F) Average off-gas flow rate 100, ,000 Nm 3 /h

14 EAF Heat Recovery: EAF Melting cycle EAF Heat Exchanger ORC Thermal user Melting Phase Power-On [min] Power-Off [min] AVG Power [MW] 1st scrap bucket charging 2 - Melting nd scrap bucket charging 3 Melting rd scrap bucket charging 3 Melting & refining Tapping & repairing 7 - 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

15 EAF Heat Recovery: Evaporative Cooling System (1/4) EAF Heat Exchangers ORC Thermal user 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 Steam ORC Electricity Water cooling Steam Thermal users

16 EAF Heat Recovery: Evaporative Cooling System (2/4) EAF Heat Exchangers ORC Thermal user Steam Drum Feed Water Tank Steam Accumulator Evaporative Cooling System

17 EAF Heat Recovery: Evaporative Cooling System (3/4) EAF Heat Exchangers ORC Thermal user Minimum steam data at steam drum Nominal steam data at steam drum Maximum design steam data at steam drum Feed water pressure at steam drum inlet 228 C 27 bar(a) (442 F psig) 247 C 38 bar(a) (477 F 535 psig) 252 C 42 bar(a) (486 F 590 psig) 45 bar (640 psig) Water content cooling system (pipes + tank) approx. 37 m 3 Capacity of steam accumulation of cooling system Steam drum glide upper limit 1442 kg 19 bar (260 psig) Capacity of steam accumulator (water content) 76 m 3

18 EAF Heat Recovery: Evaporative Cooling System (4/4) EAF Heat Exchangers ORC Thermal user Waste heat steam generator rendering and installed equipment at ESF plant, Riesa

19 EAF Heat Recovery: ORC power unit (1/2) EAF Heat Exchangers ORC Thermal user 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) Gross electric power output Net electric power output Tenova (Comeca subcontractor for heat exchanger parts) Turboden Saturated Steam at 27 bar(a) (380 psig) 13,517 kw C ( F) 100 C (212 F) 10,640 kw 26 C / 44 C (79 F / 111 F) 2,680 kw 2,560 kw

20 EAF Heat Recovery: ORC power unit (2/2) EAF Heat Exchangers ORC Thermal user Turboden unit installed

21 ORC control system

22 Project timeline Dec. 2011: Feb. 2013: Aug. 2013: 18 th Dec ORC Order ORC delivered - convection ORC first parallel at ESF waiting heat exchanger for EAF annual maintenance shutdown installed - ORC cold test 19 th Dec nominal power (2.6 MW) achieved June 2014 Expected end of commissioning 2012: Jun. 2013: Nov. 2013: 2014: ORC components ORC cabling and radiation heat commissioning design, manufacturing erection exchanger and assembly completion installed

23 First start up result TT100 = Steam inlet temperature 225 C 2,671 kw GEN POT Gross electric Power 410 m 3 /h 20 ton/h HWF =Cooling water flow HCP = Steam flow 100% Nominal power output achieved

24 Commissioning being completed Corrective actions under way to obtain uninterrupted operation at full power recovery Clean water cooled condenser tubes (oxide fouling) Eliminate waste heat boiler vibrations at full power Correct defective heat exchangers Improve steam control loop

25 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

26 Thank you for your attention

27 Turboden designs and manufactures ORC turbogenerators Organic Rankine Cycle turbogenerators Sizes range: from 200 kw to 15 MW on a single turbine* Biomass Geothermal electricity Solar heat Waste-heat Video Turboden designs and develops turbogenerators based on the Organic Rankine Cycle (ORC). a technology for the combined generation of heat and electrical power from various renewable sources, particularly suitable for distributed generation. * Larger systems can be obtained trough modular design

28 applicable to renewables energy as well as energy efficiency application Biomass Turboden ORC units for combined generation allow to produce electrical and thermal power from wooden biomass with high efficiency Typical sizes for such units are generally in the range 200 kw 10 MW electrical output Waste heat recovery Turboden ORC units allow to recover waste heat from processes and/or in combined cycles, in order to generate electrical power Typical sizes for such units are generally in the range 200 kw 10 MW electrical output Geothermal Turboden ORC and are used for electricity production from low-medium temperature (low enthalpy) geothermal sources, generally in the range C Typical sizes for such units are generally in the range 2 MW 15 MW electrical output Concentrated Solar Power An high efficiency thermodynamic cycle is used to generate electricity from thermal power captured by solar collectors Units size is normally above 1 MW 28

29 Turboden has more than 30 years of experience: born in academia and evolved into an international industrial group Prof. Mario Gaia makes experience in the field of ORC within his research group at Politecnico di Milano 1976 First prototype of a solar thermodynamic ORC Turboden installs ORC biomass plants. especially in Austria. Germany and Italy Turboden plans to enter new markets. with focus on North America First heat recovery applications MHI acquires the majority of Turboden. Italian quotaholders stay in charge of management Today - Over 270 ORC plants in the world, 230 in operation Prof. Mario Gaia founds Turboden to design and manufacture ORC turbogenerators Turboden develops research projects in solar. geothermal and heat recovery applications 1998 First ORC biomass plant in Switzerland (300 kw) 2009 Turboden achieves 100 plants sold United Technologies Corp. (UTC) acquires the majority of Turboden s quota. PW Power Systems supports Turboden in new markets beyond Europe UTC exits the power market forming strategic alliance with Mitsubishi Heavy Industries PW Power Systems becomes an MHI group company 29

30 Turboden a Group Company of MHI Mitsubishi Heavy Industries is one of the world's leading heavy machinery manufacturers. with consolidated sales of over $31.9 billion (in fiscal 2013). MHI's products and services encompass shipbuilding, power plants, chemical plants, environmental equipment, steel structures, industrial and general machinery, aircraft, space systems and airconditioning systems. Energy Aircraft Space Ship & Ocean Transportation Material Handling Environment Automotive Industrial Machinery Infrastructure Living & Leisure Defense 30

31 Turboden in

32 Turboden has currently more than 270 reference plants worldwide Application Size Plant in Operation Under Construction Total MW no. MW no. MW no. MW Wood Biomass Geothermal HR: Reciprocating Engines HR: Oil&Gas HR: Cement and Refractories HR: Metallurgy HR: Float Glass HR: Waste incineration Total Turboden Plan Country plants Country plants Germany 82 North America 6 Italy 74 Russia 7 Austria 32 Turkey 3 Rest of Europe 68 Rest of the world 7 32

33 A typical heat recovery plant scheme Electric Power Output Cooling system or cogeneration Source of Waste Heat (reciprocating engine and gas turbine exhaust, cement, steel, glass production processes, etc.) ORC battery limit Heat-Carrying Loop (1) External heat exchanger (2) Note 1) Heat-carrying loop may be filled with verse media e.g. thermal oil, saturated steam, pressurized water or it can be replaced by a direct exchange between the exhaust and the organic fluid 2) Possibility to exploit multiple thermal sources 33

34 Turboden Heat Recovery Reference: Steel - Direct exchange Billet reheating furnace at steel rolling mill Client: NatSteel Tata Group Site: Singapore In operation since February 2013 Heat source: exhaust gas from a rolling mill Direct exchange between exhaust gas and working fluid ORC electric power: ~ 0.7 MW 4 th Direct exchange ORC unit in operation 34

35 Traditional wate typically employ and extending u Superheated ste WHTP plants be Feralpi decided technology main - Proven high r in biomass ba applications) - Experience in (such as cem - Suitable tech extremely va gases - Ease of opera Heat recovery system: objective Lower energy cost through an heat recovery system with no additional personnel Simplified cogeneration ORC based waste heat recovery scheme, as applied in Riesa. 35

36 Temperature Temperature Task 2: Heat to power system choice Cycle it is a thermodynamic cycle EXPANDER Rankine it is theoretically given by 2 isobar and 2 adiabatic thermodynamic transformations Organic it exploits an organic working fluid EVAPORATOR FEED PUMP Water / Steam CONDENSER The principle is based on a turbo-generator working as a normal steam turbine to transform thermal energy into mechanical energy and finally into electric energy through an electric generator. Instead of the water steam, the ORC system vaporizes an organic fluid, characterized by a molecular mass higher than water, which leads to a slower rotation of the turbine and lower pressure and erosion of the metallic parts and blades Efficiency: 98% of incoming thermal power is transformed, into electric power (around 20%) and heat (78%), with extremely limited thermal leaks, only 2 % due to thermal isolation, radiance and losses in the generator; the electric efficiency obtained in non-cogeneration cases is much higher (more than 24% of the thermal input) Organic fluid Entropy Entropy 36

37 Operating Data Commissioning Power output: 2,058 kw gross (nominal power 2,680 kw gross). Identified problems - The convective heat exchanger is the only one in operation - Fouling problems in the ORC condenser (probably due to a not appropriate cooling water treatment) - Problems on the control system (software or hardware?)

38 Conclusion Power output: 1972 kw gross achieved on March 27 th (nominal power 2,680 kw gross). Identified problems - The convective heat exchanger is the only one in operation - Fouling problems in the ORC condenser (probably due to a not appropriate cooling water treatment) - Problems on the control system (software or hardware?)

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