Book of abstracts of the 3rd Annual Engine ORC consortium workshop
for the automotive and stationnary engine industries
September 14-16, 2016, BELFAST, U.K.
InDUSTRIAL WASTE HEAT FOR ELECTRICITY AND DISTRICT HEAT PRODUCTION: DEMONSTRATION PLANT IN A STEEL MILL BASED ON ORC TECHNOLOGY FOR USING ELECTRIC ARC FURNACE FUMES
P. Aguirrea, M. Gómez de Artechea, M. Epeldea, M. Ramírez a and U. de Mirandab
a Tecnalia Research and Innovation
C/ Parque Científico y Tecnológico de Bizkaia
C/Geldo, Edificio 700.
E-48160 Derio (Bizkaia)
Spain
; ; ;
www.tecnalia.com
b Ori Martin Steel Mill, Brescia, Italy
Via C. Canovetti, 13
25128 Brescia (Italy)
www.orimartin.com
Highlights: A large scale pilot plant based on ORC technology has been built and commissioned for electricity and heat production using waste heat from fumes of an electric arc furnace (EAF) in a steel mill in Brescia (Italy). The plant, commissioned in June 2016, has a recovery potential of 16MWth and produces electricity in summer (1.800 kWe) and district heat in winter (10MWth).
Key words: ORC, industrial waste heat, EAF, waste heat recovery, district heating
EXTENDED ABSTRACT
Introduction
In the frame of the European funded Pitagoras project (FP7, Smart Cities Programme) waste heat from fumes of an EAF in a steel mill has been recovered to produce electricity and district heat based on a seasonal operation mode. Waste heat is used to produce steam in a Waste Heat Recovery Unit (WHRU), which feeds both the ORC and the heat exchangers to deliver heat to the District Heating network.
Methods, approach and results
The main objective of the Pitagoras project is the design, implementation, commissioning and optimization of a large scale pilot plant based on ORC technology for electricity and district heat production from industrial waste heat in a steel mill. Theoretical investigations have been carried out to optimize the design of the different subsystems, which have been mainly focused on the ORC and its integration with the WHRU. The pilot plant has been built and commissioned and it is in regular operation since June 2016. Currently a comprehensive monitoring campaign is being carried out, according to the monitoring plan previously developed. First monitoring data is now being collected and analysed. Comprehensive data about a sufficiently representative period of time in regular operation will be available towards beginning of 2017.
Main investigations have been focused on the analysis of the best heat carrier (thermal oil or saturated steam) and the best ORC working fluid (cyclopentane, CP and hexamethyldisiloxane, MM), considering their thermal properties, ORC efficiency and cost-effective results, with the aim of maximizing electricity production during summertime.
The results obtained conclude that out of the considered alternatives the working fluid MM, either with steam or oil as heat carrier, is the most suitable one. Even the latter option seems to be slightly more effective, the potential risk involved for operators on working with thermal oils in a steel mill at high temperatures (additional insurance costs, safety equipment, etc.) supported that the use of steam was chosen. This resulted in the following plant design specifications:
Brief description / Technical dataWHRU / Heat exchange between flue gases and water. Composed by one Economizer (water preheat) and four Evaporators (saturated steam generation). On the top of the WHRU, a Steam Drum is installed. / Average flow rate of flue gases (dry) 120.000Nm3/h. Average operating temperature 440ºC/200ºC (inlet/outlet). Nominal capacity 16MWth, expected generation 92.800MWhth/year.
Steam Accumulator / Due to the discontinuity of the EAF operation, a Steam Accumulator is needed to handle fluctuations. / Operates between 10 and 24 barg and 185 and 224ºC. Storage capacity of 3MWhth.
ORC / Designed to maximize electricity production. ORC supplied by Turboden. Heat carrier: saturated steam. Working fluid silicone oil (MM). / Thermal power evaporator: 10,42 MWth. Average net efficiency 18%. Nominal output power: 1.800kWe. Expected electricity generation: 5.745 MWh/year.
Heat delivery to DH network / Main components: two equal steam-water heat exchangers and Flash Tank. / Thermal power to DH network: 10MWth.
Conclusions
Within the Pitagoras project a large scale ORC plant has been built and commissioned, which is currently under a comprehensive monitoring campaign. It is one of the few installations in Europe which couples electricity production by an ORC unit with heat delivery to a DH network. The different subsystems as well as the whole system have been optimized to maximize the plant performance. Monitoring operation data will be relevant for the replication of this kind of plants for other diverse applications, i.e., cement, glass and chemical industries, oil & gas sector or gas compressor stations.
Background of the research and development team
The Efficient Energy and Industrial Sustainability Area of Tecnalia deals with waste heat recovery from industries, design of thermal equipment and energy management at industrial facilities.
Acknowledgement
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.