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Thermal storage for process steam generation: The TESIN project Maike Johnson IEA Working Party on Energy End-Use Technologies Garching – March 1, 2016

> Thermal storage for process steam generation ̶ The TESIN project > Johnson • EUWP Workshop > 01.03.2016 DLR.de • Slide 1

DLR German Aerospace Center

• Research Institution • Space Agency • Project Management Agency



Locations and employees

8000 employees across 33 research institutes and facilities at 16 sites.

Offices in Brussels, Paris, Tokyo and Washington.

Köln

Oberpfaffenhofen

Braunschweig

Göttingen

Berlin

Bonn

Neustrelitz

Weilheim

Bremen Trauen

Lampoldshausen

Hamburg

Stuttgart

Stade

Augsburg

Jülich


Energy Research Program Themes

• Efficient and environmentally compatible fossil-fuel power stations (turbo machines, combustion chambers, heat exchangers)

• Solar thermal power plant technology, solar conversion

• Energy storage (thermal, chemical, electrical)

• High and low temperature fuel cells • Systems analysis and technology

assessment

Institute of Engineering Thermodynamics Prof. André Thess

Thermal Process Technology Dr. A. Wörner

Electrochemical Energy Technology

Prof. A. Friedrich

System Analysis and Technology Assessm. Dr. Schillings/C.Hoyer-Klick

„... scientific pathfinder for the storage industry...“

Computational Electrochemistry

PD Dr. A. Latz


Core Technologies for Thermal Process Technology

• High temperature heat exchangers • Sensible thermal energy storage

• Concrete • Regenerator type • Molten Salt

• Latent heat energy storage with salts • Thermochemical systems (utilization of reversible gas-solid-reactions) • Techno-economic evaluation of processes for the generation of fuels


Competences in Thermal Process Technology

• Characterization and synthesis of storage materials

• Detailed modelling of physical and chemical phenomena

• Design and fabrication of innovative storage concepts and components

• Operation and experimental investigation of prototypes in relevant scale (140-1000 °C, 1-1000 kW)

• System analysis and integration of thermal energy storage


Thermal Energy Storage as a Cross-Sectoral Technology


Key Performance Indicators o Storage density (system)

o System cost (CAPEX, OPEX)

o Space needed

o CO2-mitigation potential

o Operating characteristics …

Storage Technology

Thermo-chemical

Latent Heat

Sensible Heat

Application Storage Requirements

o Temperature level o Heat transfer fluid o (Dis-) Charging characteristics o Storage capacity o Power density

Storage Concepts

liquid solid/liquid

Salts, solid-liquid Salts, solid-solid

Gas-solid reaction Sorption

solid Sensible

Heat

Latent Heat

Thermo-chemical


Storage Concepts

20 – 100 kWh/m³ (depending on temperature difference)

Energy density [kWh/m3]

low Sensible

Heat

Latent Heat

Thermo-chemical

50 – 150 kWh/m³ (for minimal temperature difference)

100 – 400 kWh/m³ (depending on driving temperature or pressure gradient)

Development status high

high low


• Energy efficiency potential in electric steel processes of BSE/BSW • analysis of thermal energy storage integration • economic potential

• Applicability of thermal storage in • heating stations and • combined heat and power stations with the project partner SNE

• Development and test of a latent heat storage for cogeneration plant • high temperature • high heat rate • produce superheated steam

• Software tool for the assessment of industrial processes • thermal storage integration • energy efficiency

TESIN: Thermal Energy Storage for Increasing Energy Efficiency in Cogeneration Power Plants and Electric Arc Steel Plants


TESIN: Application in cogeneration power plant

Challenge • Process steam for foil production plant • Constant steam conditions mandatory ⇒ Currently: continuous operation of gas burners for emergency case ⇒ Introduction of latent heat storage to cover start-up time of gas burners ⇒ Reduction of primary energy needs

Requirements for latent heat storage • Temperature 300 ºC • Heat rate 6 MWth • Storage capacity 1,5 MWth ⇒ Extremely high power density


TESIN: Integration in the cogeneration plant


G

HRSG

Gas turbine

Waterinjection

Steam mainto customer

Feedwatertank

Stack

PCMstorage

Stack

Back-upboiler

Latent heat storage Phase change material (PCM) aspects


0

50

100

150

200

250

300

350

400

100 150 200 250 300 350Temperature [°C]

Enth

alpy

[J/g

]

KNO3

NaNO3NaNO2

KNO3-NaNO3

LiNO3-NaNO3

KNO3-LiNO3

KNO3-NaNO2-NaNO3

LiNO3

0

50

100

150

200

250

300

350

400

100 150 200 250 300 350Temperature [°C]

Enth

alpy

[J/g

]

KNO3

NaNO3NaNO2

KNO3-NaNO3

LiNO3-NaNO3

KNO3-LiNO3

KNO3-NaNO2-NaNO3

LiNO3

• Nitrate salts are possible PCMs for applications above 100 °C • Important PCM criteria are melting enthalpy and melting temperature, as

well as thermal stability, material costs, corrosion and hygroscopy

solidified NaNO3

liquid NaNO3

Phase Change Storage Current Status

• Finned tube storage concept demonstrated: • graphite fins / horizontal tubes => T <250 ºC • aluminum fins=> T <350 ºC

• radial / vertical tubes • extruded / vertical tubes

• 5 test modules with 140 - 2000 kg PCM • Large scale storage with 14t/700 kWh tested • 4 salt systems demonstrated

• NaNO3 - KNO3 - NaNO2 142 ºC • LiNO3 - NaNO3 194 ºC • NaNO3 - KNO3 222 ºC • NaNO3 305 ºC


solid

liquid

Fluid

solid

liquid

Fluid

• Heat transfer is dominated by the thermal conductivity of the solid PCM

• Low thermal conductivity is bottleneck for PCM Heat carrier: water/steam

Phase Change Material (PCM)

Tube

Fins

Simplified PCM-storage concept

Finned Tube Design effective k > 10 W/ (mK)

Latent heat storage concepts


solid

liquid

Fluid

solid

liquid

Fluid

Further development of the extended fin concept

• Axial fins provide a channel for liquid salt convection and expansion

• Simplified assembly through automation


TESIN: Storage design

• First large-scale high temperature PCM storage to use extruded aluminum fins

• Storage medium: NaNO3 • Melting temperature: 306 °C • Design mass: ~30 t

• Heat transfer fluid: Steam/Water

• Power level: 6 MW • Capacity: >1.5 MWh

• Dimensions: 2 m x 1.5 m x 8 m • Approx. 850 finned tubes


• Large scale high temperature latent heat storage being integrated into a running co-generation plant by summer of 2016

• First large scale application of extruded aluminum fins in realization

• High power levels (6 MWth) and production of superheated steam

• Replacement of standby-operation of back-up boiler, thereby reduction of fossil fuel use

• Valuable data will be collected during operation in 2016 and 2017

Conclusions & Outlook


Discussion

Maike Johnson [email protected] + 49 711 6862 344

The TESIN project, within which this research is being conducted, is partly funded by the German Ministry of Economic Affairs and Energy under the contract number 03ESP011A-C. This is a cooperative project together with STEAG New Energies GmbH, Badische Stahl-Engineering GmbH, F.W. Brökelmann Aluminium GmbH & Co. KG and Badische Stahlwerke GmbH.

Back-up: Material Properties


Property [Unit] ↓ / Material →

Steel tube

Aluminum fin

NaNO3 PCM, ave.

Effective material

Density [kg/m3] 7850 2700 2010.5 2114.5

Spec. heat capacity [J/(kg K)]

554 1020 1655 1532.8

Heat conductivity [W/(m K)]

45 210 0.55 0.12…169

Latent heat [kJ/kg]

- - 178 143.73

Simulated temperatures in the storage and heat transfer medium during discharging


Feedwater inlet

Steam outlet

Temperature distribution T and liquid phase fraction f in the 70mm diameter fin geometry during charging

17.6 %


75.9 % 98.9 % State of Charge:

• Analysis: over 200 plant profiles, categorized in 6 groups by heat source, client structure and payment model.

• Potential for high temperature storage in the ‘Biomass’ and ‘Industry’ groups.

TESIN: Market Potential for Storage Integration in Cogeneration Plants and Back-up Processes


• Potential: efficiency increase through load compensation, MRL and SRL, minimizing start-up time

• Integration possibilities have been demonstrated

• limitations due to constraints in turbine operation (pressure reduction)

• Profitability of retrofit is critical

• Integration in new plants with optimized process configuration

Energy End-Use in Germany in 2010


Overall Industry

Source: AGEB 2012

Lighting

Hot water

Information and Communication Tech.

Mechanical Energy

Refrigeration and Air Conditioning

Process Heat

Space heating

• Almost 57 % of all energy is used for supply of heat. • 70 % of the energy in industry is used for process heat.

• Reduce energy and resources consumption within the existing installed base of industrial processes by more efficient use.

• Re-use waste streams and energy within and between different sectors, including recovery, recycling and re-use of post-consumer waste

• Replace current feedstock by integrating novel and renewable feedstock. Replace current inefficient processes.

• Reinvent materials, products and processes to have a significant impact on resource and energy efficiency over the value chain.

Future Vision for the Process Industry


Source: SPIRE Roadmap 2013

• Reduce – increase energy efficiency by integration of thermal energy storage i.e. for batch processes

• Re-use – utilize process waste heat for re-integration into the process, generation of power or cold

• Replace – Power-to-heat on higher temperature levels

• Reinvent – Thermal energy storage materials, process design with thermal energy storage

Possible Thermal Energy Storage Contribution


Source: SPIRE Roadmap 2013