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 2012

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)

Elbe-Stahlwerke Feralpi, Germany: Product and Technology

Heat recovery to power means:

4

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

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

5

Energy flow of typical EAF today

Typical energy balance for top charged scrap based EAF (Tenova)

Electricity

Fossil fuels

Metal oxidation**

Liquid steel and slag

Off gas and dust

Water cooling

Electrical losses

Other losses

361

(50%) 221

(30%) 144

(20%)

726 (100%)

455

(62%)

197

(27%)

49

(7%)

13

(2%)

12

(2%)

EAF off gas typically represents more than 25% of the total energy input

6

Heat recovery system: objective

Lower energy cost through an heat recovery system with no additional personnel

Heat to power system

Thermal user

Industrial heat recovery source

Power

Cooling system

Heat carrier loop Saturated steam

7

Task 1: Heat to power system choice

Steam Turbine

Tem

per

atu

re

Entropy

Tem

per

atu

re

Entropy

Organic Rankine Cycle (ORC)

• High enthalpy drop

• Superheating needed

• Risk of blade erosion

• Small enthalpy drop

• No need to superheat

• No risk of blade erosion

Thermodynamic

features

• Water treatment required

• High skilled personnel

• High pressures and temperatures

• Non oxidizing working fluid

• Minimum personnel

• Completely automatic

Operation and

maintenance costs

• 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

Other features

8

Task 2: heat carrier choice

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)

Flammable

Steelshop operators usually not familiar with thermal oil

Simple technical solution (low temperature, no change of phase)

Many application in ORC (waste to energy, geothermal plants, etc.)

Lower ORC efficiency (e.g. 16% with 350 °F hot water)

Medium ORC efficiency (~20 % with 380 psig steam)

Complex system (e.g. water quality control)

Steam engineer necessary

Good experience of EAF steam heat recovery system at GMH steel shop (Tenova-Germany)

EAF

Heat Exchanger

Thermal user ORC

Drivers for ESF choice:

Need of saturated steam for nearby Goodyear Dunlop Tires plant

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Turboden ORC references worldwide

Application Size Plant in Operation Heat carrier

MW no. MW

Wood Biomass 0.3 - 6.5 201 214 • Thermal oil

Geothermal 1.0 - 6.0 6 19 • Hot water

Combined cycle

(bottoming of gas turbines or

reciprocating engines)

0.5 - 4.5 12 13 • Thermal oil (10)

• Direct heat exchange (2)

Industrial Heat Recovery

(Cement, Glass, Steel, etc.) 0.5 - 7.0 7 16

• Thermal oil (4)

• Hot water (1)

• Saturated Steam (1)

• Direct heat exchange (1)

Waste to Energy 0.5 - 6.0 4 10 • Thermal oil (3)

• Hot water (1)

Total Turboden Plants 230 272

Last Update: April 2014

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Start up:

December 2013

Electric Arc Furnace

(EAF)

Heat exchangers

+ steam drum

Industrial thermal user

~ 30 t/h steam

Exhaust gases

ORC 3 MWe

Electric energy

Reduce consumption

33% 67%

ESF: Waste Heat to Power scheme

Steam and condensate return pipeline

Distance between steel shop and thermal user: 0.8 miles

ESF: Waste Heat to Power layout

0

ORC Unit

Steel Shop

Evaporative Cooling System

0

Thermal user: tire plant

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

ESF: European Union support

CO2 reduction in electric steelmaking

EAF Heat Recovery: EAF Design Data

EAF

Heat Exchanger

Thermal user ORC

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 – 140,000 Nm3/h

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EAF

Heat Exchanger

Thermal user ORC

EAF Heat Recovery: EAF Melting cycle

Melting Phase Power-On

[min] Power-Off

[min] AVG Power

[MW]

1st scrap bucket charging 2 -

Melting 10 70

2nd scrap bucket charging 3

Melting 10 70

3rd scrap bucket charging 3

Melting & refining 13 70

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

EAF Heat Recovery: Evaporative Cooling System (1/4)

EAF

Heat Exchangers

Thermal user ORC

Thermal users

Electricity

Water cooling

Electricity + Fossil Fuels

+ Metal Oxidation

Electric Arc

Furnaces

Metal Scrap Melting

Fumes

ORC

Losses

Radiation

Heat

Exchanger

Steam

Steam

accumulator

Fumes

Steam

Fumes

Baghouse

Filter

Steam

Convective

Heat

Exchanger

Stack

Steam

Evaporative Cooling System

Steam Accumulator

Feed Water Tank

Steam Drum

EAF

Heat Exchangers

Thermal user ORC

EAF Heat Recovery: Evaporative Cooling System (2/4)

EAF

Heat Exchangers

Thermal user 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 45 bar (640 psig)

Water content cooling system (pipes + tank) approx. 37 m3

Capacity of steam accumulation of cooling system 1442 kg

Steam drum glide upper limit 19 bar (260 psig)

Capacity of steam accumulator (water content) 76 m3

EAF Heat Recovery: Evaporative Cooling System (3/4)

EAF

Heat Exchangers

Thermal user ORC

Waste heat steam generator rendering and installed equipment at ESF plant, Riesa

EAF Heat Recovery: Evaporative Cooling System (4/4)

EAF

Heat Exchangers

Thermal user ORC

Heat recovery system supplier Tenova

(Comeca subcontractor for heat exchanger parts)

ORC supplier Turboden

Hot source Saturated Steam at 27 bar(a) (380 psig)

Inlet thermal power to the ORC 13,517 kW

Steam temperature In to ORC 228÷245°C (442÷473°F)

Condensate temperature Out from ORC 100°C (212°F)

Thermal power to the cooling water 10,640 kW

Cooling water temperatures (in/out ORC) 26°C / 44°C (79°F / 111°F)

Gross electric power output 2,680 kW

Net electric power output 2,560 kW

EAF Heat Recovery: ORC power unit (1/2)

EAF

Heat Exchangers

Thermal user ORC

Turboden unit installed

EAF Heat Recovery: ORC power unit (2/2)

ORC control system

Project timeline

June 2014

Expected end of

commissioning

Dec. 2011:

ORC Order

2011 2012

Feb. 2013:

ORC delivered

at ESF waiting

for EAF annual

maintenance

shutdown

2012:

ORC components

design, manufacturing

and assembly

2013

Aug. 2013:

- convection

heat exchanger

installed

- ORC cold test

Jun. 2013:

ORC cabling and

erection

completion

Nov. 2013:

radiation heat

exchanger

installed

2014

18th Dec. 2013

ORC first parallel

19th Dec. 2013

nominal power

(2.6 MW) achieved

2014:

commissioning

First start up result

100% Nominal power output achieved

225°C

2,671 kW

20 ton/h

410 m3/h

GEN POT Gross electric Power

TT100 = Steam inlet temperature

HWF =Cooling water flow

HCP = Steam flow

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

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

alessandro.foresti@turboden.it

electricity

heat

Biomass

Waste-heat

Geothermal

Solar

Turboden designs and manufactures ORC turbogenerators…

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.

Organic Rankine Cycle turbogenerators

Sizes range: from 200 kW to 15 MW on a single turbine*

* Larger systems can be obtained trough modular design

Video

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… 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 90-180 °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

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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

’60-’70 1980-1999 2000-2009 2009-2013 2014…

1980 – 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)

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

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

MHI acquires the majority of Turboden. Italian quotaholders stay in charge of management

Today - Over 270 ORC plants in the world, 230 in operation

Turboden has more than 30 years of experience: born in academia and evolved into an

international industrial group

Turboden – a Group Company of MHI

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Energy Aircraft Ship & Ocean Space

Transportation Material Handling Environment Automotive

Industrial Machinery Infrastructure Living & Leisure Defense

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 air-conditioning systems.

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Turboden in 2010

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Application Size Plant in Operation Under Construction Total

MW no. MW no. MW no. MW

Wood Biomass 0.3 - 6.5 201 214 40 68 241 282 Geothermal 1.0 - 6.0 6 19 2 9 8 28 HR: Reciprocating Engines 0.5 - 4.5 11 12 1 1 12 13

HR: Oil&Gas 1.0 - 3.0 1 1 2 5 3 6 HR: Cement and Refractories 1.0 - 7.0 4 12 0 0 4 12 HR: Metallurgy 0.7 - 2.7 2 3 1 2 3 5

HR: Float Glass 0.5 - 2.0 1 1 0 0 1 1

HR: Waste incineration 0.5 - 6.0 4 10 2 8 6 18

Total Turboden Plan 230 272 48 93 278 365

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

Turboden has currently more than 270 reference plants worldwide

A typical heat recovery plant scheme

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ORC battery limit

Heat-Carrying Loop (1)

Cooling system or cogeneration Electric Power Output

Source of Waste Heat

(reciprocating engine and gas turbine exhaust, cement, steel, glass

production processes, etc.)

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

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Turboden Heat Recovery Reference: Steel - Direct exchange

4th Direct exchange ORC unit in operation

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

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Heat recovery system: objective

Lower energy cost through an heat recovery system with no additional personnel

Traditional water-steam Rankine cycle systems are typically employed in industry for plants over 10 MW and extending up to 50 MW and above. Superheated steam cycles are seldom convenient for WHTP plants below 15-20 MW. Feralpi decided to employ to Turboden ORC technology mainly for the following reasons: - Proven high reliable technology in Europe (mostly

in biomass based generation and in geothermal applications)

- Experience in other energy intensive industries (such as cement plant).

- Suitable technology to handle the discontinuous, extremely variable waste heat of the EAF exhaust gases

- Ease of operation and minimum O&M.

Simplified cogeneration ORC based waste heat recovery scheme, as applied in Riesa.

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Task 2: Heat to power system choice

Cycle it is a thermodynamic cycle

Rankine it is theoretically given by 2 isobar and 2 adiabatic thermodynamic transformations

Organic it exploits an organic working fluid

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)

CONDENSER

FEED PUMP

EVAPORATOR

EXPANDER

Water / Steam

Tem

per

atu

re

Entropy

Tem

per

atu

re

Entropy

Organic fluid

Operating Data – Commissioning

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 ?)

Power output: 2,058 kW gross (nominal power 2,680 kW gross).

Conclusion

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 ?)

Power output: 1972 kW gross achieved on March 27 th (nominal power 2,680 kW gross).