Free Pistons Engines

8/11/2019 Free Pistons Engines

1/8

Ct

e dnswer

to

your

power problern

FREE.PISTON

ENGI]tIES

1,000

ro

3O,OO0 kW

per

set

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SOCTETE

INDUSIRIELLE

GENERALE

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MCCA

TOUE

APPLIOUEE

.

S. .G.Jvl.A


2/8

GS

34

iree

pslon qasifiel

S.

G.

M

A. free

p

ston eng

nes

of

producing

energy

that has undergone

cons derable

deveopment over

the

past

few

years

ln

a

wde

variety

of

fields, lncluding

electrc

power

stations.

compressors and

pumps,

ships and combined

power

and heai

product

on.

ln

such equipment, the

usefu

energy is

produced

by an expans

on turbine

led

at

ow

plessure (3

bar

gauged)

and

low tenrperature

(450"

C)

by free-piston

gasiiiers,

the

number

of

wh

ch

depends or

the

power

of

the turbine.

S.LG.

lvl.

A.

are

lhe

first

Company

to

have

pul

this type

ol

engine

into

ndlstral

production.

The

frst

installtion

came nto service n

November, 195T,

and

by

the beginnlng

of

1967 the total

power

of currenlly used engines

construcled

by S.

L

G. M A.

and their

cence-ho

ders

hd risen to

over

600,000

h.

p.

At ihe

sarne date.

these

gasfiers

had

recorded more

thn

6

mil on

running hours,

and some

eng nes had

run

for over

60,000

houls

since they

were first

started

up.

Ihe normal working range of

S. l.

G.

M.

A.

engines extends frorn about

1,000 kW to 30,000

kW

S.

l. G.

lvl.

A.,

who

have registered offices

ln

Paris and factories at V6nissieLrx

and

Vil eurbanne

(Rhne),

employ some

2,000

people,

including about

a

hundred

eng

neers

and

sen

or

staff.

The

f

rm hs

large research and developn-rent

departments, togeiher

with

well equipped

workshops and

englneering

departments

capable of designing

and

producing

compleie installations.

(

))

g,G'm*o,*,.

A

d

;"

GAS FIE

RS

N

SERVICE

N

1S67

iv


3/8

Basically, a

S.

l.

G.

M.

A.

free-piston

engine consists

of a

turbine

fed

by several

gasifiers

mounted

in

palallel,

piping

connecting

the

gasifiers

and turbine, auxiliaries,

control

devices

and,

if

required, a reduction

gear

between

the turbine and the driven

machine

OPERATING

PB IN

C IPI.E

The

heat

from

the

fuel

intro

duced into

the enqine is

trans-

formed

into useful work in

two

stages. First,

the

heat released

during combustion

raises

the

tem-

perature

and

pressure

and,

as a

result,

the

potential

energy

of the

gases

escaping

from

the

gasifiers.

This energy

is then

harnessed

by

the

blades

of

the

turbine

and

trans-

'ormed

into

mechanical energy

vacting

on the

shaft

of

the

machine.

The figure

opposite shows

the

basic layout and energy diagram

of

a

free-piston

installation.

This sys-

lem

is

original in that

it combines

the high

efiiciency

of

the

diesel

cycle

with

the excellent reliability,

availability

and

flexibility

oI the

low

temperature

and

low-pressure

turbine.

Another advantage of

these

groups

is that

they can

use a

wide

variety

of liquid

and

gaseous

Iuels,

including

gas-oil,

crude

petroleum,

natural

gas,

etc.

This

makes

them suitable

for

use

in

light,

small-size ins-

tallations,

that do not

transmit

vibiation,

have

a

high

effi-

-

;iency,

operate

flexiblv

and

-reliablv

and are

easv to

main-

tain.

GASI

FIERS

Each

gasifier

comprises

a

pow-

er

cylinder and

two

compressor

cylinders,

housing

two

identical

sets

of

moving

parts

each consist-

ing

of

a

power piston

and a corn

The

power

cylinder is

located

in a

casinq

which acts as

both

frame and air

tank,

The

two com-

pressor

cylinde

are

ser

on

either

side

of the

casing

and are divided,

by

the

cornpressor

pistons,

into

two variable-volume chambers.

The outer chamber,

sealed off by

5.

Othe.

losses

(radirion,

6.

lJsefu

power

de

ive/ed ro shail

a cylinder head,

forms

the

cushion

which stores the

energy

during

the

"outward'

stroke of the

piston,

The

inner chamber,

closed

by a

plate

carrying the

discharge valves,

constitutes the

compressor

proper

in which the

air is

compressed.

Freshairisdrawninthroughtheinletvalvesduringthe'outward

"

stroke

and

is delivered through

the

discharge valves

durjng

the

The

fuel is introduced

jnto

the

power

cylinder through

injectors

at the

centre

of

the

machine,

The

combustion

gases,

mixed with

a

large excess

of

air, escape

through

ports

into a

piping

system and are admitted into the turbine

which

produces

the useful energy.

The

stroke

of the

pistons

is

free

because it

is not

geometrically

restricted. lt therefore varies

in

propoltion

to the

power

requirements.

AUXI LIABI ES

The

purpose

of the

auxiliary equipment

is

to

provide

the

fuel

supply,

to cool the

various

parts

of

the machines with water or oil,

and

to

provide

the air

for starting.

The

total

power

that they absorb does not exceed

2%

of the

useful

power

of the sets,


4/8

Turbo-alternalor

room

(Balea,ic

at

rhe

lbiza

Power siarion

TURBINE

The turbine uses the

gases produced

by the

gasifiers

and drjves th f inal

machine

either direcdy or via a reduction

gear.

Because

of

the low temperatute and

pressure

of rhe

gases

at the inlet,

and the

absence

of sub

atmospheric

stages, these

turbines are simpler and even sturdier than

low-pressure steam turbines.

The

illusnation on

the

left shows

two

of the four

'1.500

kW turbo

allernators

in the Spanish

Electricity

authority's

power

station

t lbiza

(Balearic

lslands).

CONTROLS

These

machines

are

generally

regu-

lated by a

modulated

oil circuit controlling

rhe injeclron

pump

of the

gasifiers.

anc

hence the

quantity

of

fuel injected, through

a device

governed

by the value

to

be ad

justed,

which

may

be

the

speed

ol

the

nrbo-alterntor in the

case of

an

electric

generator

set

or delivery

pressure

rn

the

case of a

pump

or

compressor,

MAIN

FEATUBES

The

graph

opposite

shows

the

approximate curves

of

gas

temperature

and

pressure

at

the

turbine

inlet at

different loads; specific fuel

consump-

tions

are also

given.

T

=

Temperature at turbine inlet.

P

=

Pressure

at iurbine

inlet

CB

=

Specific consumption

at

the al

ternator terminals in

g/kwh

where the tubine

is

driving an

CM

=

Specific

consumption

at

the

tur-

bine shaft in

g/hp.h.

Specific

oil

consumption

for

lubri-

cating the

gasifiers

and renewing the

cooling and lubricating

oil

for

the turbo-

alternator

does

not

exceed

2

g/kwh

on full load.

The

time-lag

between

starting the

first

gasifier

and full-load operation of

the entire set is usually

fifteen

minutes,

and

this can be reduced in

certain


5/8

Gasifler room

l rhe

compressor slation

of

the

Sociate

Savoisienne

de

Produits

Cryogdniques

(Sainr

El

enne

Fn.e)

ELECTBICITY

GENERATING

STATIONS

APPTICATIONS

S.

l.

G. M.

A.

gasifiers

have

Proved

their advantages

for many

purposes,

including

the

generation

of electricity,

driving air and

gas

compressors,

pumping,

the

propul,

On

1st January,

1967,

more

than

600

qasifiers

were

in operat on

in

the

following

sets,

whh unit

Powers

ranqing from 600

to

20,000

kw:

78

generating

plants;

-

3 compressor

plants

i

3

pumping

installations

l

3 combined

electricitv

and

heat

generating

plants;

I

suction

dredgers;

-

42

fiatine

power

units.

A

large

numbel of free

piston

engine

sets are used

for

the

generation

of

electricity for borh

pubtic

utitities

and

a

wide variety

of industrial firms.

The essentjat

advanrages

of

these engines

make rhem

economical

for

both

continuous

operation and

daily or seasonat

peak

service.

Sets

like

those t

the

lbiza

power

srarron,

already

mentioned, or at

the

power

station

at

Jarry

(cuadetoupe),

which

is shown

below from

the outside while

still under construction,

are

the

main

producers

of elecrriciry

in the

islands where

they are

installed.

They

provide

a continuous

suppty under toads

that

vary according to

demand.

Furthermore,

they have the

reserve

capacity

considered

necessary

to

ensure this kind

of

seruice. At

lbiza

there is

stand-by

gasifier

common

to two 1,500

kW sets

and

at

Jarry

one

for

each

of rhe iwo 6,300 kW sets.

ln

neither

case is

there

a reserve rotary installation,

for

these machines

operate for long

periods

without

requiring

any

inspection

or

maintenance.

S.Pl_DEC

oowe'

Srdriol

d Jd.'y (cJadF

oLpF/

fiir

-.flilflmltln

-rr

P-TIIirtt

I

ii..d


6/8

C.E L. Power Station at Acajltla

(El

Salvador)

Other

power

stat

ons

are

con-

nected to

larger

qrids

and

are

used

in

parallel

l

-

either

with more

powerful

Lrnits,

when they serve

as boosters

at

peak

hours. This ls the

case

at

the

Chartres

stat on,

which com-

prises

a 20 MW set installed for

Electricit6

de

France.

Thls

plant

is

designed

mainly lor

peak'hour

ser

vice in winter

and s

requ

red to

start up

several times a dayl

or

with

hydraulic units,

which depend

on seasonal

rainfall

or the meltinq of the

snows,

and

have

to

be supplemented

by ther

ml

units

in dry

seasons.

The Aca-

juda

station, the

exterior

of

which

is

shown

in the

photograph

above

lorms

part

of

such a network.

Many industrial

concerns, in-

cluding

phosphate,

nickeL

and dia-

mond mines,

cement

works,

PaPer

mills,

oil companles,

etc.,

also

se

elecvical

generator

sets

on a

wide

variety of systems

and

usuallY

ge'

nerate

their

own current

ai very

economical

prlces.

COMPRESSOR

AND PUMPING

SETS

Free-piston sets

can also

be

used directlv

for drivinq

PUmPs

or

compressors

for a

,r'ide var ety

of

purposes,

e.

g.

ifligation and

water

sLooles.

o

I

oumP

nq

rh

Petro

chemical.

metal

urgcd

ron

and

sleel,

cryogenic

and

other ndus

tries, suction

dredger

PUmPs,

etc.

W th a turbine

dr

ve,

power

can be

kept

virtually constant

on

the

PUmP

or

compressor shaft

over

a

lairY

For thls type

of

serv

ce

where, in

most cases,

continuous operation

and a

high

degree

of

reliab

lhy are requ

led,

a series

of

gasfiers

suppying

a

gas

collectol

connected

to

several turbo-pumps

or

turbo

compressors

offers

a very reliable and flexible sol tion

nd, moreover, does nol require

heavy cap tal

investment

The

photograph

above

shows the turbo

compressor room in an installation

provided

for

lmperial

Chemical

lndustries at their

Wihon factory in Britain. This station,

which ws commlssioned

in T959

works

completely

continuousy

on

full

load

for

periocls

of

two

to three

yeals,

with short

pauses.

lt

comprses

sixteen

tvpe GS34

free

piston

gasifiers,

fourteen operating

permanenily

and two

kept n

reserve,

feed

ng six turbo-compressors

for diflerent

sases

used

rn

processing

olefines.

A similar but lower

powered

installation

is

in use

at

the Sa nt-Etienne

(France)

factory

of the Soc

616

Savoi-

slenne de

Produits

Cryog6n

ques.

This iactorY

mainly

produces

the

oxygen used

n a

stee

works.

Turbo-compressor rom at the

.

c. l.

compressor

slat

of

at Wiho.

(Great

Bilain)


7/8

SHIP PROPULSION

EOUIPMENTS

t

'|

S.

l.

G.

M.

A.

propul-

sion

units

have

all

the

usual advantages

of

free

piston

machines,

but

cer-

tain

features are here of

special mportance, as for

example, ease

of instal-

lation.

small

bulk and low

welght

compared

with

conventional

engines, the

absence of vibration. relia-

bility, etc.

Reversing is

gene-

rally

effected by

means

of

a

reverse

turbine

incor-

porated

in

the

mln tur

bine. A three-way

valve

allows all or

part

of

the

gases

to

pass

to

one tur-

bine

or the other. On

"

stop

",

the torques

pro-

duced

by

each

of

ihe

two turbines cancel out

and the drive line

comes

to

rest. The

problem

of

control

can

aso be

sol-

ved with a

variable

pitch

Cargo vessel

Mezerles (U.S

S

R)

S.l.c.M.A. have

buih rhe

16,000

hp.

twln-shaft

power

patrol

escort

ressel

Commandant

Bory,

ol

the

French

Navy.

unit

for the

MIXED

GAS"STEAM

CYCLES

l\,4any

industrial installations

and

public

ulilities

require

not only

electrical

energy

but

also heat

in the

form

of steam

or hot water.

Electricity and heat

can

be

generated

simultaneously

by a combina

ion

of

free-piston

sets

with

boilers, ln

vwhich

lhe

heat

from the turbine exhaust

gases

ls

recovered

in

the

manner

shown

in

the diagram

opposlte

This

syslem has

great

advantages

over

more

convenrional methods

llke

back-pressure

stearn iurbines, viz.

:

More

electric

power

can

be

sup,

plied

for

rhe

sarne

volume

of

steam

-

ln

a

given

insiallation,

the

pro-

ductlon of elecflicity

can be varied inde,

pendendy

of the

generation

of heat,

whlle

retaining

excellent

overall efflciencv.


8/8

-

o

a

ADVANTAGES OF FREE-PISTON SETS

I - FLEXIBILITY AND

RELIABILITY

a Great

reliability

thanks to

the simplicity

of

the

gasifiers

nd

the

robustness

of the tulbine,

due

to

the

low

gas

input temperature.

a

Availability

over 98 %,

because the

gasifiers

arc mounted

in

palallel

and

work

independently,

so

that any one

can

be

taken out of

seruice

without stopping

production.

Full

power

can be maintained

by installing

one

or

two

reserve

units nd

taking

each

gasifier

out

of service

in turn for routine

maintenance.

o

Ouick starting and

instantaneous

load variation are

possible

because

working temperatures

aIe

relatively

low and

little

energy

is

stored.

LOW CAPITAL OUTLAY

Foundations

are

light

because there

is no

vibratjon;

the

gasifiers

are

balanced

and

have

no

crankshaft.

Turbine torque

is

regular.

The

machines

can be

installed exactly as

rcquiled

in each

particular

case because there

are

no

mechanical

Iinks between the

gasifiers

and the

turbine.

a

All

set components

are

light

and thercfore cheap

to

transport

and

assemble.

a

With

independent gasifiers,

capital cost

on

reserue

capacity

is

low.

t

-

LOW FUEL

COrS

o

All liquid

fuels,

including

very heavy types can

be used owing to the size of the

motor

cvlindel

and the

tem-

peratures

and

pressures

at

which the

sets

work.

a The

gasifiers

work equally

well with

light

(Sahara)

or heavy

(Califolnian)

crudes.

a

They also

work

with

natural

gas

or

a combination

of

the two

types

of fuel in

any

proportion

IV.

GHEAP

AND

EASY

MAINTENANCE

a Spares

are

small and can

easily

be carried by air

anywhere in the world.

o

Only a

few, light

parts are

liable

to

wear.

They

are easily

accessible and completely interchangeable,

and

can

be fitted without further

machining

or adiustment.

S.

I.

G.

M.

A. TECHNICAT ASSISTANCE

Twiceayears.

l.G.M.A. holds courses

lasting a

fo(night

at

the

V6nissieux

factory'

Thev cover

both

practical

and theoretical

aspects

and

are intended

for

all engineers and technicians

intelested

in

free

pistons,

nd

particularly

for the stafls

of

client

companies.

S. L G.

l\rl.

A. will accept trainees

for

longer

periods

in its

assembly shops,

design

departments

and testing

shops

where

they

can

learn more about the company's

techniques and machines,

An efficient

Atter-Sales

Service

despatches engineers

and fitter-instructors

without

delay

to

any

pa(

of

the

world

to investigate

and resolve

all

kinds

of operating

problems.

Documnr

no 9236

a

3000

10

67

Free Pistons Engines

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