p&e1198.ppt

Power

and the

EnvironmentP C Ruffles FRS, FEngDirector of Engineeringand Technology, Rolls-Royce plc

The 46th Hatfield Memorial Lecture

at Sheffield University

p&e1198.ppt

Rolls-Royce power

Rolls-Royce provides

power systems for air,

sea and land-based

applications

Gas turbines are our

principle power

generating products

Industrial Aerospace

23% 77%

p&e1198.ppt

Power — Environmental impact

The impact of economic activityon the environment is a majorconcern facing the worldcommunity

Our products convert energy infossil fuels to thrust ormechanical power and emit theircombustion products to theatmosphere

Noise and emissions of NOx,SO2, UHCs and CO at groundlevel are of concern to localcommunities

NOx & SO2 can cause acid rain

CO2 & NOx may effect globalwarming and deplete the ozonelayer

p&e1198.ppt

Aerospace power — Noise

No bypass duct

Low bypass ratio

High bypass ratio

Avon

Conway

Spey

RB211-535 Tay

V2500-524G/H

Trent

1960 1970 1980 1990 2000Entry into service

75%

reduction

Total aircraft noise - Rolls-Royce engines

Low bypass ratio High bypass ratio

Compressor

Turbine & core Turbine & core

Compressor

Fan

Jet

Shock & jet

Engine noise sources

Communities local to airports

are worst affected due to take

off and landing manoeuvres

International and local

regulation impose very

stringent limits

Reductions in aircraft noise

are largely offset by

increased traffic and aircraft

size

Future aircraft must therefore

become even quieter

p&e1198.ppt

Aerospace power — Noise

Noise is controlled by:

Choice of bypass ratio (BPR)

Space between rotating parts

Number and shape of blades

Acoustic lining in inlet & exhaust

Integrated exhaust streams or

advanced nozzles

Component aerodynamics Blade number selection

Mixed-flow exhaust (BPR <6)

Separate jets (BPR >6)

Wide-chord fan

Increased bypass ratio Acoustic liners

p&e1198.ppt

Aerospace power — Noise

In the past, satisfying noise,

fuel burn and range targets

have not been in conflict

However, with current

technology the economic

optimum BPR is around 6

Latest engines (Trent 500)

have higher BPR to reduce

noise

Noise technology must focus

on reducing sources without

compromise to fuel burnBypass ratio3 6 9 12 15

Trent 500Trent 900

Economicoptimum

Fuel burn

Aircraftweight

Operatingcosts

Noise

p&e1198.ppt

Gaseous emissions — Aerospace & energy

Power stations emit UHCs,

CO, CO2, NOx & SO2

Airports are source of emissions,

notably UHCs, CO, CO2, NOx

& smoke

Ground

Acid rain& smog

1km

Ozone

CO2 reflects IR back to earth.

NOx acts as catalyst to

create ozone which reflects

IR back to earth

Global warningAircraft at cruise emit CO2 & NOx

Stratosphere (~20km)

p&e1198.ppt

Gaseous emissions — Environmental impact

Air traffic contributes ~3% of global

CO2 and ~1% of NOx emissions

no significant SO2 emission due to

clean, non-sulphur containing fuel

Air traffic is expected to increase by

5% per annum over next 20 years

future contribution could be ~7% CO2

& ~2% NOx respectively

Power generation produces large

amounts of CO2 (29%), NOx (21%)

and SO2 (58%)

— near term: gas turbines will reduce

emissions due to cleaner fuel and

combustion, and better efficiency

— longer term: more advanced means

of energy conversion are required

Carbon dioxide (CO2)

Nitrogen oxides (NOx)

Sulphur dioxide (SO2)

Waste treatment

Power stations

Industry

Domestic

Other

Road traffic

Agriculture

Other mobile

Solvents

Nature

% of man-made sources - 1995

p&e1198.ppt

Aerospace power — Emissions legislation

Legislation is focused on the

landing/take-off cycle and limit

UHCs, CO and NOx— local impact often provokes

localised legislation

— modern engines have

acceptable UHC, CO and

smoke emission

— future legislation (2002)

requires a 36% reduction of

NOx relative to 1986 limit

(16% at 1996 limit)

More advanced cycles improve

CO2 (fuel burn) but deteriorate

NOx

Current effort is focused on

reducing NOx and CO2

emissions

COHC NOxSmoke

1970-73

1979-83

1985-88

2000

Averageemissions

PredictedNOx

200

100

20

40

Emissions - gm/passenger

SAE smokenumber

1960-70

1980-90

p&e1198.ppt

Aerospace power — Emissions constraints

Primary

zone

Secondary

zone

At idle:Combustor pressure andtemperature are low, andprimary zone is weak

— inhibits chemical reactionwhich creates CO and UHCs

At high power:Combustor temperature andpressure are high and primaryzone is rich

a fuel-rich mixture createssmoke which is burned offby secondary combustionsecondary combustioncreates NOx establishing atrade with smoke

Good compromise is achievedthrough aerodynamic andmechanical design

NOx & smoke reaction rate

10 20 30 40 50

Fuel/air ratio

+ve

-ve

Smoke

NOx

Decreasing temperature

Strutless

pre-diffuser

Cowled head to

ensure full pressure

feed to backplate

Large airspray injectors

for improved mixing

and smoke control

Large primary zone

volume for altitude

re-light

Small total

volume for

NOx control

Lipped cooling rings

for mechanical

durability

Deep annuli for good

aerodynamic feed

to mixing holes

p&e1198.ppt

Aerospace power — Combustion technology

Double annular combustors allow

‘staged’ combustion to optimise

idle and max.power

— pilot chamber operates with

good idle and altitude relight

characteristics

— main chamber is fed with fuel

progressively as thrust increases

Pre-mixed injectors can eliminate

NOx emission by thorough mixing

of air with fuel prior to combustion

— oxygenated mixture gives a more

stable, lower peak temperature

(~2000K)

— NOx is first produced ~2100KPre-mixed double-annular combustor

Pilot

Main

Double-annular combustor (BRR715)

Pilot

Main

p&e1198.ppt

Aerospace power — Fuel burn (CO2)

Fuel burn (CO2 emissions)

- % of Comet 4/Avon

1985 199519751965

80

60

40

20

0

%

100 Fuel burn has decreased by 60%

since the 1960s

— 50% SFC improvement due to

improved engine efficiency

Installed SFC is a function of:

— overall pressure ratio (OPR)

— turbine entry temperature (TET)

— component efficiency

— propulsive efficiency

— installed drag

By 2010 the aim is to reduce

SFC by a further 10% over

today’s best performance

— achieved by increasing OPR to

50:1, TET by a further 100ºC,

and raising the BPR to ~9-16

-8

0

Relative cruise sfc - %

40

5060

30

20

2100

1700

1900

Max.operatingtemp - K

(type test)Overall

pressureratio

1970s

1980s

1990s

2000

Cruise SFC v OPR & TET

p&e1198.ppt

Aerospace power — Turbine temperaturesTET has increased by 300°C

during last 25 years

— 150°C due to improved cooling

design (200°C above melting

point of HP turbine blade

material)

— 150°C due to improved

material and casting technique

(component efficiency

improves with minimum use of

cooling air)

— blade life has doubled over this

period

HP turbine blades require

compressor bled cooling, but

three-shaft engines allow IP

blades to operate uncooled at

1000°C

Type test temperatures of RB211 & Trent HP

turbine blades

TET

ºC

Equiaxed MarM002Directionally-solidified MarM002Single-crystal CMSX-4

B

B2 B4

D4

C2-524G

E4

-524H

T775 T890

T895

T772

1975 2000

1300

1600

HPT IPTGeneral layout ofengine core

p&e1198.ppt

Aerospace power — Turbine materials

Turbine blades have evolved to cope

with increases in TET

wrought Nimonic alloys

equiaxed MarM002

directionally-solidified MarM002

single-crystal superalloys (SRR99,

CMSX-4, RR3000/3010)

Material grain boundaries are a

source of weakness

— directional solidification removes

boundaries which are perpendicular

to strain

— single-crystal growth removes all

grain boundaries and leads to

secondary benefits

DS MarM002

CMSX-4

RR 3010

0

40

80

120

Material temp. increase (°C)

Improvements in

material creep

property

Equiaxed MarM002 baseline

p&e1198.ppt

Aerospace power — The future

The ‘flying wing’ offers

significantly-reduced drag for

high-capacity aircraft

Contra-rotating aft fan concept

can be over-wing mounted and

improves SFC, weight and noise

Pre-mixed, double-annular

combustors will offer reduced

emissions

All-electric aircraft offer future

improvements in fuel burn and

operating cost

Flying wing

Aft-fan

Innovative aircraft and engine designs are required to provide step

improvement in performance

p&e1198.ppt

Industrial power

Rolls-Royce also supplies

power generating products

for the following markets:— small and medium sized

power stations (up to 100

mW)

— oil and gas pipeline pumping

— marine propulsion

Our principle products in

these sectors are:— aero-derivative gas turbines

(3 to 65mW)

— medium size diesel engines

(0.3 to 15mW)

Oil & gas pumping

Marine propulsion

Power

generation

p&e1198.ppt

Industrial power — Gas turbines

Industrial legislation is controlled

locally and is more stringent than

aerospace

Gas turbines offer small/medium

industrial power with distinct

environmental advantages:— they are compact and offer good

efficiency

— they are readily available to

provide power in a distributed

system

— specially-designed combustion

system for low Nox (29ppm

compared with aero 300ppm)

— industrial engines burn cleaner,natural gas rather than kerosene

Industrial Trent is most powerful

and efficient gas turbine of its kind

Aero Trent

New

compressor LP bleed

Dry Low Emissions

combustor LP turbine

& exhaust

redesign

Rear drive

added

Industrial Trent installation

p&e1198.ppt

Industrial power — Trent DLE combustor

Conventional combustion

at low powers for stability

Reverse-flow design

allows easy

maintenance of fuel

injector and combustor

Increased residence

time to control CO

8 combustors designed

for dual fuel operation

Uniform pre-mixed

lean-burn combustion

zones giving uniform

low temperatures

and hence low NOx

Series staging to allow

operational flexibility

with low emissions

over power and

ambient temperature

range

p&e1198.ppt

Industrial power — Cyclic configuration

Combined

cycle

Waste

heat

boiler

Generator

GeneratorGas turbine

Steam

turbine

Electrical power

output

Electrical power

output

Fuel input

An industrial gas turbine can be

configured in one of three ways:

Simple cycle42% thermal efficiency

output at shaft only

Combined cycle58% thermal efficiency

exhaust heat used to power

additional steam turbine

Combined Heat and Power85% thermal efficiency

exhaust energy transferred in

steam for external use

The compact nature of gas

turbines allows installation at point

of consumptionminimising transmission

losses

Combined heat

and powerGeneratorGas turbine

Waste

heat

boiler

Fuel input Electrical power

output

Steam to

process plant

Simple cycle

GeneratorGas turbine

Fuel input Electrical power

output

p&e1198.ppt

Industrial power — Diesel engines

Allen Power Engineering produce

large diesel engines for industrial

and marine use

The recently-launched Allen 5000

is the most efficient (45%) and

powerful diesel engine of its

capacity (500kW per cylinder)

— diesel engines offer the ability to

burn low cost, low grade fuel

— electronic variable fuel injection

enables each cylinder to be

optimised for SFC and emissions

under all conditions

p&e1198.ppt

Industrial power — Fuel cells

Emissions

Conventionalpower station

Experimentalfuel cell

Coal Coal Gas

SO2

NOx

Gas

30

20

10

Combined cyclelocal station

Fuel

Air C T ~

x__

Combinedcycle

schematic

Fuel cells are an emerging future

technology for fossil-fuelled power

stations— they convert fuel energy directly

into electrical power by oxidation

of the fuel

— efficiency of ~70% in combined

cycle, giving significant CO2

reduction

— Nox and SO2 output <1vppm

A fuel cell consists of an ion-

conducting electrolyte between two

porous electrodes— electrolyte separates fuel (anode)

and air (cathode) and mediates

the reaction

— electrons migrate from anode to

cathode, causing an oxygen ion to

migrate through the electrolyte

p&e1198.ppt

Industrial power — Distributed systems

Traditional centralised energy supply is being supplemented by

localised stations

Technology has improved

efficiency of smaller

generators

De-regulation of industry

has removed barriers to

entry

Transmission losses are

minimised

Improved system efficiency

leads to lower cost and

environmental damage

Conventional

supply

Renewables

Fuel

cells

Gas turbinesDemand

Heat to process

plant

p&e1198.ppt

Rolls-Royce power — Summary

Aero engines have reduced emissions and noise dramatically

over the last 25 years

Similar improvements in the future will require modification to

both the engine and the airframe

Gas turbines in simple cycle, combined cycle and CHP

configurations are ideally suited to reduce CO2 and NOx relative

to coal burning power stations

Aero derivative gas turbines are quick to erect and can be

installed at point of energy consumption

Future developments embrace more advanced gas turbine

cycles, fuel cells and other energy converters in a distributed

system

p&e1198.ppt

Power

and the

EnvironmentP C Ruffles FRS, FEngDirector of Engineeringand Technology, Rolls-Royce plc

The 46th Hatfield Memorial Lecture

at Sheffield University