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Westinghouse -Leblanc CondenserStanda rd J et Type

D r iven by Westinghouse Steam Turbine

7 J s$y

R elative si"es,air and circulating e"uipments of l ike capacity

The Westinghouse-Leblanc Condenser

The Westinghouse-Leblanc Condenser representsone of those developments in engineering that

owes its stimulus to a radical improvement in another branchof the art .

The Type

The steam turbine revolutionized steam engineeringpractice in half a dozen years . The Leblanc Condenser bearsthe same relation to the familiar type of condensing apparatusthat the steam turbine does to the reciprocating engine . Itis in fact a turbine type condenser . Like the turbine itoccupies only a small fraction of the space formerly allotted .

Like the turbine it develops superior efficiency,not by the

multiplication of parts,but through a simple appl ication of

rotary motion,with no reciprocating or rubbing parts and

no valves of any description .

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R ecent At the time of the introduction of the steamD evelop turbine by the Westinghouse M achine Company

,

mentsas announced that a very high vacuum would

unproy e tn“ 0 nom i es to an extent hitherto impossible

when applied to meiprocating engines . This condition naturally created an era of development among the condenserdesigners .

It became evident at once that the old types that were

good enough for 25 or 26” vacuum would be practically

useless where the requirements called for a vacuum of 28 ” or

Whil e many refinements thus far have been made in

all features of condenser desig n, they have been generally

along the lines of former practice . The principal improve

ment adopted by practically all manufacturers has been toapply a separate dry vacuum pump for the removal of airand non - condensible vapors .

The dry vacuum pump,as commonly constructed

,is a

direct steam driven reciprocating unit,with its air cyl inder

and valve mechanism designed to reduce as far as possiblethe return to the condenser of the compressed air from the

SCREEN S F O R EXCLUSIONO F ALL F OREIGN SU"STANCES SucuS

‘

n cx

Westinghouse-Leblanc Condenser serving a Curtiss Turbine at the plant ofThe H a rwood Power Co .

,H arwood

,P a .

A cool ing pond with Koerting sprays is used for cooling the in"ection water

clearance spaces . When it is realized that the air following back from the clearance will exceed many times theoriginal volume

,it becomes evident that the ideal vacuum

will never be reached by the reciprocating type of pump .

In the effort to overcome these inherent defects,builders

have resorted to numerous refinements . Air cylinders arewater-j acketed to prevent overheating . M echanically operatedair valves are introduced. to prevent the building up of a highback pressure in the condenser sufficient to l ift voluntaryvalves from their seats . Two air cylinders are sometimes putin series

,

‘which manifestly improves the effi ciency . Anadditional set of "ash ports i s sometimes introduced

,which

permits the air compressed in the clearance to be almost instantaneously discharged , not into the condenser , but into theopposite end of the cylinder j ust before the suction valvesopen . This l ast expedient would at first blush seem to goa long way toward removing the bad effect of clearance

,if it

did not in a measure defeat itself .

The sudden expansion resulting from this action causesa re-evaporationof the moisture always present on the wall sof the cylinder

,and hence

,no air can enter from the con

denser until the piston has traveled far enough to equal izethe pressure .

The net result of the combination of such expedients isto impose a burden of first cost and maintenance that willoverbalance the doubtful benefits to be secured by extremecomplication .

The most striking feature of the Leblanc systemof condensation is its compactness and simplicity .

While it employs the excellent feature of separate removal of water and air

,its functions are performed

by a pair of small turbine type rotors on a common shaft,

m a single unit casing,which is integral with the lower por

tion of the condensing chamber .

The condensing chamber is of small diameter,being but

sl ightly l arger than the exhaust opening of the engine .

These elements are all discernible at a glance,but the

pre-eminent superiority of the Leblanc system over all otherslies in the practically perfect removal of air and non-conden

sible vapors .

The detailed description of the air pump on the following page shows how this result is obtained by a mechanismthat is practically indestructible .

sscnon N .

— N .

THROUGH A lR PUMP.

CHARGE .

DISCHARGE

SEQTION M .

- M .

THROUGH WATER P UMP .

Sectional views of the standard Westinghouse -Leblanc

Condenser are shown 0 11 the opposite page . Exhaust steamenters at D and cooling water entering through pipe A i sproj ected downward through spray nozzles " . The inj ectionwater and condensed steam "ow to the centrifugal dischargepump M under a head of 2 or 3 feet

,which insures positive

filling of the pump . The exhaust steam is drawn downwardand condensed by the water spray . The space E abovethe water is occupied by water vapor plus the air releasedfrom the inj ection water and from the exhaust steam . Thisspace communicates with the air pump N through pipe K .

The principle is ‘

entirely new ,and it differs from

all ej ector type pumps which depend on frictionfor the entrainment of air .

The Leblanc pump proj ects a series of water pistons throughthe discharge nozzles

,each one of which forces ahead of it

a small pocket of air .

This air,of course

,mingles with the water in the lower

portion of the nozzle,but the speed is such that no part of it

ever finds its way back toward the condenser . In other words,

there is no leakage past the pistons . The initial pocketingof the air between the successive layers of water is positiveand

,as will readily be seen

,the neutralizing eff ect of clear

ance is entirely eliminated . The water supply for the airpump may be taken from the main water inlet or a supply maybe placed in a tank and used over and over in the air pump .

Since the air pump water is in communication with the condenser

,it is drawn by suction into an annular chamber G

,

which is overhung by the buckets of the pump rotor P .

The water passes out of the chamber through the ports Hand is proj ected downward in a rapid succession of waterpistons . At the lower end of the air pump nozzle is placedan auxiliary ej ector nozzle L

,to which is connected a steam

pipe . In starting up the condenser,steam is turned into this

auxiliary nozzle for a few moments,thus creating a sufficient

vacuum to start the regular "ow of water through the air pump .

Where the level of the cold well is 3 or 4 feet above thebasement "oor

,the air pump may be started without the use

of steam .

As will be seen from the illustration,the air pump rotor

P and the main pump runner F are enclosed in a commoncasing and mounted on the same shaft . There are only twobearings and the shaft glands are made air- tight by water seals .

Power The pumps are usually driven by a WestinghouseR e"uire steam turbine

,and under ordinary conditions re

ments quire from 2 to 3 per cent of the power generatedby the main engine .

The exhaust from the condenser turbine is utilized forheating feed water

,and when combined with the exhaust of

other plant auxiliaries,the quantity is j ust about suffi cient to

maintain a feed temperature of 212 degrees F ahrenheit .

In cases where economizers are used,or where there may

be extra sources of exhaust steam,it would be advisable to

operate either the condenser pumps or the exciter by means

of an electric motor . The main pump is commonly designed

to discharge against only a few feet head sufficient to overcome friction in the discharge

‘

line . If it is desired to elevate the water to the top of cooling towers

,or other moderate

elevations,the pump can readily be mod ified to meet the

additional duty .

This i s the only moving element in the condenser

Turbine driven condenser at the plant ofthe B r istol G as E l ectr ic Co . ,

Br istol,Tenn .

M otor driven condenser at

the M unicipa l Lighting Plant of the City of Cl eveland

This condenser serves a 1000 kw . Westinghouse Turbine , in"ection water beingcooled in a -acre pond with Koerting sprays— 27%-inch vacuum

is ma inta ined at ful l load during summer

10

Counter This term is often used in connection with variousCurrent apparatus whose functions involve a transfer ofP r1nc1p1e heat . Aside from its application to surface con

densers,it is generally ignored by j et condenser builders

,

although sometimes vaguely referred to . In general terms,

it may be said that counter current principle as appl ied to acooling process consists in so disposing the cooling mediumthat the substance being cooled will at the instant of withdrawal be subj ected to the full effect of the lowest temperature . Thus

,in a surface condenser the water is introduced

at -the top and the steam at the bottom,the steam

,rising to

the top,i s exposed to the entering cold water . The air

,which

is always present,being non -condensible

,is little aff ected by

this final cooling,but the eff ect on the final volume of steam

is remarkable,a much greater proportion of it being condensed

in the cooler region and the air pump,instead of handling

a certain volume of air plus a relatively large volume ofsteam

,is enabled to draw out a mixture from which a l arge

part of the steam as such has been eliminated . This lawmay be illustrated arithmetically as follows

CASE I. Slight Counter Current Effect.

A ssume init ial temperature in"ect ion waterTemperature at which air is removedVacuum "temperatureWeight of air enteri ng condenser per minute I

In this case,owing to an excess of cool ing water as ordin

arily supplied , the mixture of air and vapor‘ is taken

‘off in

a partly cooled condition,i . e .

,from degrees "the hot

test point"to 90 degrees . At this temperature and pressurethe volume of the pound of air alone is 221 cubic feet

,while

the volume of the steam is 539 -cubic feet. Therefore,the air

pump,in order to extract a pound of air per minute

,must

have an eff ective displacement of 221 cubic feet plus 539 2 750cubic feet per minute .

CASE II . F ull Counter Current Effect.

A ssume ini tial temperature in"ect ion waterTemperature at which air is removedVacuum "temperatureWeight of air enteri ng condenser per minute

1 1

In this case,the full counter current eff ect is real ized

,the

mixture of air and steam being taken off at 70 degrees tem

perature "a cool ing of degrees below the hottest part".

At 70 degrees the volume of one pound of air alone is 213cubic feet

,while the volume of steam in the mixture is only

1 25 cubic feet,making a total of 338 cubic feet for the air

pump to handle,or less th an half the size required for case I .

These relationships remain the same whether the coolingis done in a surface or a j et condenser

,and the Leblanc air

pump,as applied to either type

,combines in its cold circula

ting water both the means of expelling the air and simul

taneously cool ing the mixture to the point of minimum volume .

Small F or units smaller than 300

Si"es horse power,it i s customary

to eliminate the main condensing chamberand pass all of the exhaust steam as wellas the air through the air pump only .

F or this service,the air pump is slightly

modified,a relatively greater amount of

water being used,which serves both to

expel the air and condense the steam inone operation . The sectional cut illustrates a complete condenser of this type .

The same high effi ciency is maintainedand the apparatus occupies scarcely morespace than that required for the exhaustpipe alone . The accompanying cut illustrates a vertical steam engine equippedwith one of these small condensers .

13

F LOOR

D|SCHAROE TOH OTWE LL

F or use with surface condensers,both stationary

and marine,and for appl ication to barometric and

other types of j et condensers,evaporating pans

,

etc .

,the air pump is furnished separately . Embodying , as it

does,the vital element of the Leblanc system

,its application in

any situation requiring an effi cient vacuum will insure a markedimprovement in the effectiveness of the entire equipment .

SeparateA ir Pumps

In the case of new installations of surface condensers,

the air pump and the circulating pump may be combined ina single compact unit substantially as shown by the cut below .

It is not always logical to refer to European praeSuccess

ti ce as a cri teri on to be preci sely followed inAbroad

Ameri ca,for the reason that labor cost i s lower

and fuel cost much higher and,therefore , warrant the use of

expensive and elaborate equipment which would fail torealize any ultimate economy when transplanted in the regionof lower fuel cost and

"

higher labor . In the present instance

,however

,where the whole tendency is in the direction

of simplicity and ease of handling,the fact of the rapid

adoption of the Leblanc system in England and on the Con

tinent possesses a useful significance for American practice .

There are upwards of 400 installations in E urope , aggregating one-half million horse power

,many of the most prominent

engine and turbine builders,including P rof . R ateau

,having

abandoned the older types formerly manufactured by themselves and are installing the Leblanc system exclusively

M r . "alcke,of "ochum

,G ermany

,probably the largest con

14

denser builder in Europe , i s now turning out the Leblanc typeexclusively

,under a l icense arrangement . N aturally

,the

majority of these installations are in connection with steamturbines of various makes

,but a considerable proportion is

applied to stationary reciprocating engines,marine engines

,

vacuum pans,etc .

The F irst At the present writing there has already been" ear s contracted for in this country over 60 LeblancShowmg Condensers

,aggregating horse power . M ost

of these serve turbines of various types,while a few

,espe

cially in small sizes,are used with reciprocating engines .

R esults obtained from some of these plants are set forthin the following tables .

E fficiency is here expressed by the percentage of an ideallyperfect vacuum actually obtained . F or instance

,if the dis

charge temperature is 100 degrees F ahrenheit,the corres

ponding ideal vacuum would be inches . If,however

the observed vacuum is inches,the efficiency percentage

would be

ENG INE R O OM "LOO R LINE .

EXH AUST TOATM O SP H ERE

REL IEF VA LVEAT E VA LVE

WATER AND

VACUUM P UMP

DISCH AR GE TOH 0T weLL

SU"M ERGED N OT

INLE T TO WEL LE S S TH AN 3 F T.

1 5

Shop Test— East P ittsburgN o. 12 Condenser— Capacity and Effic iency

S team Conden sed Tempera ture s Vacuum R e ferred P er Cen t o fLb s . P er H our t o a 30"

" arome ter Idea l VacuumIn"ec t ion D i s ch arge

J ersey Central Traction Company, Keyport, New J ersey

No. 5 Condenser— Capacity and Efficiency"R a ted cap ac i t y 8380 lb s . s team condensed a t 27 vacuum and 90 deg rees i n"ec t ion tempe ra ture"

Steam Condensed Tempe ra tures Vacuum R e ferred P er Cen t o fLb s . P er H our t o a 30"

" arome ter Idea l VacuumIn"ec t ion D i sch arge

Union Sand and M aterial Company

N o . 5 Condenser— Efficiency O nly

Tempera ture Vacuum R e ferred P er Cen t o fD i sch arge to a 30” " arome ter Idea l Vacuum

75

80

82

78

"Pract ica l l y fu l l l oad wa s ma i n ta ined dur ing the above read ing s , v i" . , from 450 to 525 k i l owa t t s ou the turb i ne"

J acksonville O il M ill Co . , J acksonville , A la .

No. 1 condenser— Efficiency O nly

P er Cen t o fD i sch arge Idea l Vacuum

16

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R elation between temperature and pressure of saturated steam

The above vacua are referred to a barometer of 30 inches .

In taking vacuum readings,a barometer reading at the same

level as the condenseri

should be obtained,and in comparing

temperatures allowance should be made for the barometer,

adding or subtracting,as the case may be

,the diff erence

between the barometer readings and 30 inches . Thus,if the

barometer reading is inches,for example

,subtract

inches from the vacuum reading to get the correct vacuum .

If the barometer reads for example,then add to the

vacuum reading to get the correct vacuum .

R elative volumes of air in a saturate mix ture —

at various

temperatures — corresponding'

to different observed vacua

Pound s per S"uare Inch Ab solu te.49 y .98

Inche s Vacuum R e ferred to a 30" " arometer

P er Cen t Vo lume o f S a tura ted A ir Presen t i n a M ix ture o fA ir and Vapo r o f Wa ter

19

An Inter esting Insta l lation

A 1000 kw . Westinghouse E x haust Steam Turbin e , with a Leblanc Condenser workingin conn ection with a cool ing tower at the p lant of the Colorado Spr ings

E l ectr ic Company ,Colorado Spr ings , Col .

20

Cool ing tower used in connection with the low pressure turbine and

Westinghouse-Leblanc Condenser shown on the opposite pageIt is needless to remark tha t the fr ee use o f a rtifi cia l cooling devices is made a

commercia l success only by combining with a highly efficient condensing e"uipment

21

A typica l instal lation of a SOO-kilowattWestinghouse-Leblanc turbine-dr iven condenser

22

The Westinghou se M achine Company

G enera l O ffices , Wo rks and Labora tory

East P ittsburg, P a .

SA LE S O F F ICE S

N EW " O RK 165 BRO ADWA"

ATLANTA

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PH ILADEL P H IA 1003 N . AM ERICAN BU ILDING

ST. LO U IS CH EM ICAL BU ILDING

G . O . BRAN IF F Co . CIT" or M E x rco

24

CANDLER BU ILDING

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