review of low grade thermal energy sources and...

Low grade thermal energy sources and uses from the process industry

in the UK

Yasmine Ammar, Sharon Joyce, Rose Norman, Yaodong Wang, Anthony P. Roskilly

Sustainable Thermal Energy Management in the Process Industries International Conference (SusTEM2011)

Newcastle upon Tyne, UK 25-26 October 2011

25 - 26 October 2011 Newcastle Upon Tyne SusTEM2011

Outline • Past and current drivers to recover heat.

• Low grade heat definition

• Low grade heat sources in the UK and potential market for this energy

• Thermodynamic constraints on low grade heat recovery and potential end-users

• Factors influencing the decision process for stakeholders of low grade heat recovery projects


Incentive to Save Energy

Fuel price indices for the industrial sector

Coal

Gas

Electricity Oil

1973

1986

2005

75

245


Europe wide drive for CO2 reduction has lead to legislation (UK Governmental target is a reduction of 80% by 2050 )

• Climate Change Levy • Emissions Trading • Carbon Reduction Commitment • IPPC

A new Incentive to Save Energy

Source: UK NAEI (2004)

CO2 emissions by energy use

Newcastle Upon Tyne SusTEM2011 25 - 26 October 2011

Industrial heat use

22% of the total energy use in the UK

Source: UK NAEI (2004)


Common heat recovery applications in the process industry


Source : Econotherm

Pre-heating feed water for a boiler pre-heating combustion gas for aluminium furnace

Research area

• Heat exchanger selection for heat recovery

• Intensified heat and mass transfer (compactness/ performance)

• Fouling and ageing of heat exchangers

• Heat exchanger network and retrofits

• Process intensification (pinch analysis, total site analysis)

• Improved combustion for fired heaters, boilers, furnaces

25 - 26 October 2011 SusTEM2011 Newcastle Upon Tyne

Energy management in the Process Industry


Experienced Engineer

has rules of the thumb

State of the art, Best practice, energy monitoring

(energy use/ tonne of products)

Optimisation/intensification tool, Modelling, CFD simulation, entropy generation minimisation

algorithm

What do we mean by low grade heat?

Products


Low grade heat sources available for

over the fence recovery solution

Process

optimisation and

heat integration

Low grade heat sources from main

process industrial sectors

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Glass Steel Chemical Oil

Process industrial sector

0

2000

4000

6000

8000

10000

12000

Carbon trust (2010)

Government’s Office of Climate Change (2008)

Mc Kenna (2009)

Low

gra

de

he

at (

MW

)

Sources

Estimation of the industrial low grade heat rejected to the environment in the

UK (MW)

(Source: Institution of Electrical Engineers, 1994)

Estimation of the industrial low grade heat per sector(MW)


Examples of low grade heat sources

gas (30-220°C)

30%

Steam (200°C)

40%

Water (35-50°C)

30%

Low grade heat sources identified in a steelworks

Steam (50°C)

3%

water (35-50°C)

60%

moist air (50-109°C)

37%

Low grade heat sources identified in a papermill with integrated CHP

Low grade temperature between 30 °C and 250 °C


30 50 150 250

Temperature (°C)

Maximum energy available for recovery

Challenges for low grade heat recovery

• Energy available for work production decreases with source temperature


Applications for low grade heat

Biomass drying

Heating building

Greenhouses

Biogasification

Desalination

Hydrogen production

Ammonia production

Synergy Energy storage Power

production


Low grade heat sources from Process

Industry

Recovering heat from flue gas

• Gas to gas heat exchanger

Heat pipe schematic representation Source : Econotherm design


Recovering latent heat from flue gas

• Flue gas to water heat exchanger

25 - 26 October 2011 SusTEM2011

Newcastle Upon Tyne

Indirect contact flue gas condenser Direct contact flue gas condenser

Flue gas inlet

Water return

Shell and tube

Packed bed

HEX

Power production

• Rankine Cycle (RC) principle

Source: SINTEF energy research (2010)


Heat Exchanger

Flue Gas

Turbine

Pump

Condenser

Power processes and working fluids

250°C

90°C

70°C

RC •Water/steam

ORC •Hydrocarbons •HFC

Kalina •Ammonia/water

Transcritical cycle •CO2

R&D


+20-50%

Efficiency

Low grade heat temperature

Reusing heat for domestic heating or cooling applications


Heat exchanger Rankine cycle Heat pump

Heating/Cooling domestic demand

Flue gas

Working fluid

Remaining heat

Using low grade heat to produce fresh water


Criteria for low grade heat recovery (Reay,1980)

• Low grade heat is available at a useful temperature at the sink

• Low grade heat can be economically transferred from the source to an identified end-user sink

• Coincidence of heat supply and demand occurs.



Potential heat sinks: example of Port Talbot

Heat consumers 25 km 9 km 1 km Public Buildings (MW) 2.141 0 0

Commercial Offices (MW) 0.757 2 0

Hotel and Catering (MW) 2.642 0 0

Other Services (MW) 1.025 8 0

Retail (MW) 2.518 5 0

Sport and Leisure (MW) 0.613 0 0

Small Scale Industrial (MW) 41.991 0 0

Domestic (MW) 100.72 3 0.2

Schools (MW) 0.866 0 0

Hospitals (MW) 0.675 0 0

Warehouses (MW) 1.775 0 0

Total (MW) 155.7 18 0.2

Economic distance from the source to the end-user site

50 km 30 km 5 km

Steam at 250 °C:

Water at 150°C

Water-Ammonia pair

(Generation temperature~100°C)

Which transportation radius to look at low grade heat end-users?

Long distance transportation system- Lin et al (2010) 500 MW transported over 50 km with a payback period < 3

years (China nuclear waste heat transportation)

It depends on: -Type of transport media -Temperature of transport fluid -Pipe insulation efficiency and pipe material - cost invested in heat transportation


Upgrading the economics of heat recovery project with heat storage

400kWh thermal capacity solid-media storage unit

Cylindrical capsules filled with phase-change material are integrated into a pressure vessel

heat exchanger for the latent-heat storage unit, with fins made of graphite foil, before integration of phase-change material between fins.

Source: Institute of Technical Thermodynamics, German Aerospace Center (DLR), Stuttgart, Germany


Maximising energy savings and mitigating environmental impacts thanks to a holistic approach

Solid/water waste

HEAT BUS FOR T<Teco

HEAT BUS FOR T>Teco

Steel

Pulp & Paper

Chemical

Cement

Food & Drink

Cooling water

Transport

Finished products

Wind farm

Water filtering

Raw materials

Non recyclable by-products

Recycling unit

LOW GRADE HEAT RECOVERY

Fossil energy

Electricity



Example of a holistic approach: Cryogenic electricity storage system

(copyright: Highview Power Storage)

Barriers/obstacles • Economic: high payback period • Difficulty of data collection from heat suppliers and

technology manufacturers • Risk for the heat supply provider/ end-user with

reliability of the source as main obstacle • Corrosive nature of the heat as low temperature

implies an extra cost • Organisational structures: energy project considered of

second importance and consequently poorly monitored

• Need of governmental policy and regulation incentives


review of low grade thermal energy sources and...

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