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 3 rd Engine ORC Consortium Workshop September 14-16, Belfast, Northern Ireland
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. Industrial waste heat • Exhaust flue gases from an Electric Arc Furnace source thermal and energetic valorization. • A 16MW th demonstration plant was performed in a steel mill from ORI MARTIN in Brescia (Italy). Residential area Start-Up: January 2016 • The plant produces hot water (10 MW th ) for feeding a DH network in wintertime (October-April) and produces electricity (1,8 MW e ) in summer season ( May-September) for plant self-consumption. 3rd EORC workshop, Belfast, 2016
PITAGORAS project Consortium members 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 BRESCIA CITY INFRASTRUCTURE cold water steel charge EAF steel molten DH DEMO PLANT DH system hot water Incomes exhaust gases from heat (hot) steam supply STEAM ORC unit steam WHRU steam water ACCUM. exhaust gases (cold) electricity Savings in electricity purchase ORI MARTIN STEEL MILL 3rd EORC workshop, Belfast, 2016
Demo-plant location • ORI MARTIN premises in Brescia (Italy). District Heating system Electric Arc Furnace Heat recovery system ORC unit Quenching Tower 3rd EORC workshop, Belfast, 2016
Plant scheme Feed Water Tank Steam Accumulator 6 WHB ORC unit 4 3 2 EAF 1 DH system 5 3rd EORC workshop, Belfast, 2016
Electric Arc Furnace (EAF) 1 • 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 Nm 3 /h of fumes are directed to the WHRB. Quenching Tower EAF 3rd EORC workshop, Belfast, 2016
Waste Heat Recovery Boiler 2 • 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 MW th • Flue gases inlet/outlet temperature: 440ºC/ 180ºC. • A pneumatic system to remove dust cake has been installed to maintain tubes clean. WHRB + Steam Drum 3rd EORC workshop, Belfast, 2016
Steam Accumulator 3 • 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: 3MWh th. Steam Accumulator 3rd EORC workshop, Belfast, 2016
ORC unit 4 • 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). 3rd EORC workshop, Belfast, 2016
District Heating system 5 • Hot water generation during wintertime for a local district heating supply. • The DH system is composed by: Heat Exchanger 1 & 2 – Two circuits: steam/condensate; cold/hot water to DH. – Two heat exchangers. – Flash Tank + Condenser. Flash Tank & Condenser – Circulating pumps. • DH heat capacity: 10 MW th . • Average hot water supply temperature to DH: 95-120ºC. • Expected thermal energy generation: 44.700 MWh th /year (during 7 months). 3rd EORC workshop, Belfast, 2016
Feed Water Tank 6 • 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. FW Tank & Deaerator BFW Tank 3rd EORC workshop, Belfast, 2016
3. TECHNICAL & SOCIO-ECONOMIC DATA (I) TECHNICAL DATA • Average flow rate of flue gases (dry) 120.000Nm 3 /h • Average inlet/ outlet operating temperature : 440ºC/200ºC WHRU • Nominal thermal capacity: 16MW th • Expected generation 92.800MWh th /year. • Operating pressure and temperature: 10 - 24 barg /185 - 224ºC. STEAM ACCUMULATOR • Storage capacity of 3MWh th • Thermal power at Evaporator inlet: 10,42 MW th • Expected efficiency to be achieved: 18%. ORC • Nominal output power: 1.800kWe. • Expected electricity generation: 5.745 MWh/year (Summer season) • Thermal power to DH network: 10MW th • Supply /return water temperature to DH: 95-120ºC/ 60-85ºC DH SYSTEM • Expected thermal energy generation: 44.700 MWh th /year (Winter season) 3rd EORC workshop, Belfast, 2016
3. TECHNICAL & SOCIO-ECONOMIC DATA (II) SOCIO-ECONOMIC DATA 12M € where: • WHRU: around 75% TOTAL INVESTMENT • ORC: around 20% • DH system: around 5% OPERATION & MAINTENANCE COST 3-5% of the total investment (*) HEAT PRICE 10-15 € /MWh th supplied EMPLOYEES 4 (FULL TIME) (*): ESTIMATION. ONLY 8 MONTHS OF PLANT RUNNING. 3rd EORC workshop, Belfast, 2016
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 kW e and a target efficiency of 18%. • DH system works in wintertime, having an average capacity of 10MW th and a hot water supply of 44.700 MWh th /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 € /MWh th ) 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 CO 2 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
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