3rd Engine ORC Consortium Workshop September 14-16, Belfast, Northern Ireland

Industrial waste heat for electricity and DH production:

Demonstration Plant based on ORC technology for using EAF fumes

Mercedes G. de Arteche

Miguel Ramirez

Tecnalia Research & Innovation

1. Introduction and objectives.

2. Steel mill & Demo-plant description.

3. Technical & socio-economic data.

4. Conclusions.

3rd EORC workshop, Belfast, 2016

1. INTRODUCTION AND OBJECTIVES • Industrial waste heat recovery for electricity (ORC system) and district

heating (DH) production.

• Exhaust flue gases from an Electric Arc Furnace

thermal and energetic valorization.

• A 16MWth demonstration plant was performed in a

steel mill from ORI MARTIN in Brescia (Italy).

Start-Up: January 2016

• The plant produces hot water (10 MWth) for feeding a DH network in wintertime (October-April) and produces electricity (1,8 MWe) in summer season ( May-September) for plant self-consumption.

3rd EORC workshop, Belfast, 2016

Industrial waste heat

source

Residential area

PITAGORAS project Consortium members

3rd EORC workshop, Belfast, 2016

Project Coordinator

Subcontractors:

PITAGORAS PROJECT IS FRAMED INTO FP7, SMART CITIES PROGRAMME (EUROPEAN UNION FUNDING PROJECT)

3rd EORC workshop, Belfast, 2016

2. STEEL MILL & DEMO-PLANT DESCRIPTION

EAF

WHRU

exhaust gases (hot)

water

exhaust gases (cold)

ORC unit

DH system hot water

cold water BRESCIA CITY

ORI MARTIN STEEL MILL

DEMO PLANT

steel charge steel molten DH

IN

FRA

STRU

CTU

RE Incomes

from heat supply

Savings in electricity purchase

steam STEAM

ACCUM.

electricity

steam

steam

Demo-plant location • ORI MARTIN premises in Brescia (Italy).

3rd EORC workshop, Belfast, 2016

ORC unit

Heat recovery system

Electric Arc Furnace

Quenching Tower

District Heating system

Plant scheme

3rd EORC workshop, Belfast, 2016

EAF

1

Feed Water Tank

WHB

2

Steam Accumulator

3

4

ORC unit

5

DH system

6

3rd EORC workshop, Belfast, 2016

Electric Arc Furnace (EAF) • Mixed EAF: scrap melting (electrodes) + natural gas burners.

• Responsible of the flue gas generation.

• Flue gas flow are partially directed to the WHRB due to a damper. The rest, are conducted to the Quenching Tower.

• Approximately, 120.000 Nm3/h of fumes are directed to the WHRB.

Quenching Tower

EAF

1

Waste Heat Recovery Boiler • Responsible of saturated steam generation due to the thermal exchange

with EAF exhaust gases.

• Formed by 4 Evaporators and 1 Economizer (feed water preheating). At the top, there is a Steam Drum (steam/water reservoir).

• Feed water circulates through vertical tubes inside the WHRB,

absorbing the thermal heat exchanged by the flue gases

circulating through the shell side.

• WHB thermal power (design): 16 MWth

• Flue gases inlet/outlet temperature:

440ºC/ 180ºC.

• A pneumatic system to remove dust cake

has been installed to maintain tubes clean.

3rd EORC workshop, Belfast, 2016

WHRB + Steam Drum

2

3rd EORC workshop, Belfast, 2016

Steam Accumulator • Store the recovered thermal energy from the WHB due to batch operation

of the EAF melting process.

• Two phase (water/steam) vessel with two operating modes (charging/discharging). Pressure modulation.

• Operating pressure and temperature: 10-24 barg / 185-224ºC.

• Store capacity: 3MWhth.

Steam Accumulator

3

3rd EORC workshop, Belfast, 2016

ORC unit • Electricity generation during summertime for plant self-consumption.

• The ORC unit is composed by:

– Evaporator.

– Turbine + Generator.

– Regenerator.

– Condenser.

– Circulating pump.

– LT and HT Preheaters.

– Post-cooler.

• ORC internal fluid: silicone oil (MM).

• ORC system electric capacity: 1,8 MWe.

• Expected average cycle efficiency: 18%.

• Expected electricity generation: near 5.745 MWh/year (during 5 months).

4

3rd EORC workshop, Belfast, 2016

District Heating system • Hot water generation during wintertime for a local district heating supply.

• The DH system is composed by:

– Two circuits: steam/condensate;

cold/hot water to DH.

– Two heat exchangers.

– Flash Tank + Condenser.

– Circulating pumps.

• DH heat capacity: 10 MWth.

• Average hot water supply temperature to DH: 95-120ºC.

• Expected thermal energy generation: 44.700 MWhth/year

(during 7 months).

Heat Exchanger 1 & 2

Flash Tank & Condenser

5

3rd EORC workshop, Belfast, 2016

Feed Water Tank • FW Tank: Stores the condensate water coming from the whole installation

in order to feed the WHRU through a pump (BFW pump).

• Deaerator: removal of oxygen and other dissolved gases from the feed water.

6

FW Tank & Deaerator BFW Tank

3. TECHNICAL & SOCIO-ECONOMIC DATA (I)

3rd EORC workshop, Belfast, 2016

TECHNICAL DATA

WHRU

• Average flow rate of flue gases (dry) 120.000Nm3/h

• Average inlet/ outlet operating temperature : 440ºC/200ºC

• Nominal thermal capacity: 16MWth

• Expected generation 92.800MWhth/year.

STEAM ACCUMULATOR

• Operating pressure and temperature: 10 - 24 barg /185 - 224ºC.

• Storage capacity of 3MWhth

ORC

• Thermal power at Evaporator inlet: 10,42 MWth

• Expected efficiency to be achieved: 18%.

• Nominal output power: 1.800kWe.

• Expected electricity generation: 5.745 MWh/year (Summer season)

DH SYSTEM

• Thermal power to DH network: 10MWth

• Supply /return water temperature to DH: 95-120ºC/ 60-85ºC

• Expected thermal energy generation: 44.700 MWhth/year (Winter season)

3. TECHNICAL & SOCIO-ECONOMIC DATA (II)

(*): ESTIMATION. ONLY 8 MONTHS OF PLANT RUNNING.

3rd EORC workshop, Belfast, 2016

SOCIO-ECONOMIC DATA

TOTAL INVESTMENT

12M€ where:

• WHRU: around 75%

• ORC: around 20%

• DH system: around 5%

OPERATION & MAINTENANCE COST 3-5% of the total investment (*)

HEAT PRICE 10-15 €/MWhth supplied

EMPLOYEES 4 (FULL TIME)

4. CONCLUSIONS • Waste heat recovery takes place in a steel mill to generate steam to feed a DH

network in winter and generate electricity in summer through an ORC unit. • The ORC unit operates during summertime, where heat demand decreases

considerably. This alternative allows electricity production with an average net electric output of 1800 kWe and a target efficiency of 18%.

• DH system works in wintertime, having an average capacity of 10MWth and a hot water supply of 44.700 MWhth/year to the network.

• Total investment is established in 12M€ and O&M yearly costs represents between 3-5%.

• Incomes are expected regarding heat supply to the DH network (10-15 €/MWhth) and savings on electricity related to ORC electricity self-consumption.

• Social and environmental benefits are confirmed regarding employment increment and waste heat recovery in heavy industry. This installation contributes to the decrement of the GHE and reduces CO2 emissions to the atmosphere.

3rd EORC workshop, Belfast, 2016

The research leading to these results has received funding from the European Union Seventh Framework Programme FP7/2007-2013 under grant agreement n° ENER / FP7EN / 314596 / PITAGORAS. This publication reflects only the author’s views and the Union is not liable for any use that may be made of the information contained therein.

3rd EORC workshop, Belfast, 2016

THANKS FOR YOUR ATTENTION!

TECNALIA Thermal Energy Area Energy and Environment Division Área Anardi, 5 E-20730 Azpeitia - Gipuzkoa (Spain) www.tecnalia.com

mercedes.gomezdearteche@tecnalia.com miguel.ramirez@tecnalia.com

3rd EORC workshop, Belfast, 2016