Heat Recovery Systems For GenSets: Is It Just A Lot of Hot Air?

17th November 2015Dr. Hezlin Ashraf-BallEngineering Manager

EJ Bowman (Birmingham) Ltd

IntroductionEJ Bowman (Birmingham) Ltd

• Established in 1919 (almost 100 years)• Experts in design and manufacture of

heat exchangers– Marine engines, land based engines, automotive

test facilities, CHP, firepumps, swimming pool and many more

– Shell & tube and plate type heat exchangers

• UK manufacturing facility• ISO 9001:2008 certified• More than 1 million heat exchangers

sold• Export over 70% of all products• Stockists worldwide

Hezlin Ashraf-Ball Engineering Manager• Joined Bowman in August 2015• Understanding of thermodynamics within heat

exchanger systems for Power Generation, Renewable Energy, Automotive Testing and Aerospace Components Icing Test

• Previous experience:– Chief Project Engineer– Heat Exchanger Design Leader– Research Engineer – Awarded PhD in Chemical Engineering from

Birmingham University in 2005

Overview

1. Principles of Combined Heat and Power (CHP)2. Benefits of offering a CHP Solution3. Heat recovery potential from a Genset4. Turning a Genset into a CHP ‘total solution’5. Heat exchanger installations-Genset CHP6. ‘Total solution’ heat exchangers7. Background of shell and tube heat exchangers8. Critical characteristics for heat exchanger selection9. Design and development work10. Products installed for CHP applications

Principles of CHP

* Association of Decentralised Energy

Fuel 100%

Losses 20%

Power 31%

Heat 49%

Combined Heat and Power Generation

80% Usefulenergy

Definition:Simultaneous generation of usable heat and power (usually electricity) in a single process.Examples of applications:• Industrial CHP• Small Scale CHP-Genset• Micro CHP• CHP with district heating

33 to 50 % of the fuel input available as useful heat * Digest of United Kingdom Energy Statistics (DUKES) 2015

CHP – The benefitsBenefits from reciprocating engine perspective*:

• 33 to 50 % of the fuel input available as useful heat • Useful heat at no additional cost in terms of fuel or CO2 generated• Adding waste heat recovery will increase the overall efficiency from

around 31% to 80%*• The waste heat can be used as either

– to provide heating or hot water– to heat up process streams such as hot water, thermal oil, steam

generator– to generate additional electricity or provide

a cooling facility

* Digest of United Kingdom Energy Statistics (DUKES) 2015

CHP – The benefits

Possible financial incentives/ support measures for Good Quality CHP in the UK *:

• Climate Change Levy (CCL) • Carbon Price Support (CPS) • Enhanced Capital Allowances (ECA) for plant and machinery• Business Rates for CHP power generation plant and machinery• Reduction of VAT (from 20 to 5 per cent) on domestic micro-CHP installations• Renewable Obligation Certificates (ROCs) Specific Renewable Heat Incentive

(RHI) for biomass fuelled • Contract for Difference (CFD) • Carbon Reduction Commitment Energy Efficiency Scheme (CRC)

* Digest of United Kingdom Energy Statistics (DUKES) 2015

3

1

Air intake

4

Generator lubrication oil

2

Engine Jacket Water

Exhaust

Exhaust

Useful Heat 12%

Useful Heat 24%

Useful Heat 9%

Useful Heat 55%

Reciprocating engine

Turbocharger

Heat Recovery Potential From Genset

Turning a Genset into a CHP ‘Total Solution’

Reciprocating engine

Turbocharger

3

1

Air intake

4

Generator lubrication oil

2

Engine Jacket Water

Exhaust

Vent/StackExhaust

Useful Heat (50 to 70°C)

Useful Heat (60-70°C)

Useful Heat (70-95°C)

Useful Heat (Up to 110°C)

Individual and/or combination of useful heat can be used for: • Heating (commercial or

domestic buildings) • Process heat from hot

water or thermal oil • Steam generation • Organic Rankine Cycle

(power augmentation option)

• Absorption Chiller

Heat Exchanger

Heat Exchanger

Heat Exchanger

Heat Exchanger

Heat Exchangers Installations-Genset CHP

Reciprocating engine

Turbocharger

3

1

Air intake

4

Generator lubrication oil

2

Engine Jacket Water

Exhaust

Vent/StackExhaust

Exhaust gas heat exchanger – recovers 55% useful heat

Oil Cooler – recovers 9% useful heat

Header Tank – recovers 24% useful heat

Bowman heat exchangers are compact allowing: • Ease of integration

within the engine system

• Minimal cost for re-engineering and/or redevelopmentCharge Air

Cooler – 12%

‘Total Solution’- Heat Exchangers• Exhaust gas heat exchanger

– A high efficiency solution for waste heat recovery from the exhaust stream, suitable for Biogas, Diesel and Natural Gas applications up to 1MW

• Header tank heat exchanger– Unique design combines high efficiency engine

cooling, with long life durability, suitable for engines up to 1400kW

• Charge air cooler– Improves fuel efficiency and enhances engine

performance by cooling turbocharged air, suitable for engines up to 800kW

• Oil cooler– Recovers valuable heat energy from the engines

lubrication system, suitable for applications up to 1900kW

Tubestack Materials Selection • Stainless steel • Cupronickel • Titanium

Body • Aluminium casting (BS EN 1706) • Stainless steel

End Covers • Cast iron, • ‘C’ coat 300 • Composite • Naval brass

Background of Shell and Tube DesignDesign criteria:• One fluid flows on the inside of the

tubes, whilst the other is forced through the shell

• Baffles are introduced to force the flow across the tubes to induce higher heat transfer• Segmental baffles• Disk and donuts

• Head arrangements allow single or multiple tube pass flow

• Trade off between pressure drop and heat transfer is important in the design selection process

Q = U x A x dT Q = Heating/Cooling Duty (kW) U= Overall heat transfer coefficients A = surface area (m2) dT = temperature difference between the two fluids

Critical Characteristics For Heat Exchanger Selections

– Depending on the types of flue gas used in the Genset (sulphur content) different exhaust gas exit temperature will be recommended

– This is to ensure that the heat exchangers are not exposed to the risk of acid dewpoint and fouling

Exhaust Inlet • Fuel type • Mass Flow • & Temperature

Exhaust Exit • Acid dewpoint

limit

Water Inlet • Mass Flow • Temperature

Water Inlet • Not to exceed

110°C

All products are categorised under Standard Engineering Practise under Pressure Equipment Directives (PED 97/23/EC)

Design and Development

• Work with customers to incorporate requirements into our design and development process, wherever possible

• On-going product improvement programme for heat transfer, pressure drop etc.

• Constantly seeking new market applications• In house bespoke computer selection

programs• In-house testing facilities• FEA and CFD capabilities

Bowman CHP solutions around the world

• The British Antarctic Survey – Halley VI Research Station• SSI, Fort Providence – a remote Northern Canadian community• Turnberry Golf & Luxury Resort in Scotland• Grain drying project in Finland• Eco-residential project in Finland• Other waste heat recovery options

– Stirling Engine (additional electricity)– Organic Rankine Cycle (additional electricity)– Absorption Chiller (cooling)

The British Antarctic Survey – Halley VI Research Station

• The station located on the Brunt Ice Shelf Antarctica• Fully operational since 2013• Winter temperatures plummet to -50°C and snow falls for

half of the year • Exhaust gas heat exchangers provide heat to support the

BAS team who live and work at the base all year round.

SSI, Fort Providence, Northern Canada• Winter temperatures can fall to -40ºC• Utility and diesel costs significantly higher, due to

remote location• The community has 800 people, situated on the

McKenzie River in the Northwest Territories of Canada• Installed 150kW Genset based CHP units using Bowman

exhaust gas heat exchangers plus charge air coolers• 60% increase in heat capture from the Bowman units• 52% saving on cost of energy using diesel generators

with CHP

Eco-Residential Project in Finland• Eco residential project• Wood-gas fuelled CHP plant• 5 Exhaust gas units fitted to Sisu Gensets• Application recovers waste heat energy and

cools gas produced by wood burner• Provides heat and power to ten homes

• Exhaust gas units on a heat recovery (heat pump) solution for grain drying  

• Will reduce diesel fuel consumption during the grain drying season on this particular farm by around 18,000 litres 

• This is the first system to be installed in Finland

Grain Drying in Finland

• Application driven by expanding energy demand• Desire to reduce energy costs and CO2 emissions• Bowman exhaust gas units installed on to generators• High efficiency independent CHP solution for heating

requirements

Turnberry Golf Resort in Scotland

• Organic Rankine Cycle (ORC) turbine generator systems• Exhaust gas heat exchanger can supply

hot water (thermal oil) for the evaporation (superheating) of fluid before turbine

• Stirling Engine• Cool Energy utilised waste

heat from a 30kW Genset to produce additional electricity

• The heat is used within their 3kW SolarHeart ® Engine using Stirling Engine Concept

• Absorption chiller • Exhaust gas heat exchanger

can supply hot water to supply heat for refrigerant’s evaporation

Using waste heat to deliver more power

Summary• Up to 49% of waste heat can be recovered and turned into useful heat for:

– Heating for commercial or domestic buildings– Process heat from hot water, thermal oil or steam– Additional electricity –Stirling Engines and Organic Rankine Cycle – Refrigeration option – absorption chiller

• Financial incentives offer viable route for turning a Genset into a CHP solution• Integration of compact heat exchangers into the existing footprints eliminates the need of

re-design/re-development– Selections process focused on heat duty requirement and pressure drop limitations taking into account Genset fuel type

to minimise acid dewpoint fouling• It’s worthwhile looking at recovering heat from all waste source within Genset

– Exhaust gas (55%)– Jacket water (24%)– Charge air (12%)– Engine oil (9%)

• Bowman have vast experience in providing ‘total solution’ for Genset waste heat recovery with clients all over the world

Questions & Answers