CITY LIGHTING PLANT.

Dominion, Volume 3, Issue 674, 26 November 1909, Page 5

CITY LIGHTING PLANT.

~...'.■■ •■■..-■ ..-:..-■ '■■' ■-.:■•: T.'-< :: "■.•■ •-.-■■■. /: NEWTTOBIN?.-, qV iThe;,-City Corporation's new turbine plnnl, , .: : s whioh was.;opened".by. the'Mayor.:ion'..Wednes- , '.' , day,.'-is housed fini a?n<s« - building,--.having.'-a■-.;■'': : frontage:! of.'96ft.' ,:to^'Mercer , Street;.-,and" ; ;'ai : : «". depth.of■ 107 ft/ cbrnprißes-a,large;i: : turbine,- room' ' and . boiler-house, '■- the 1, , first- ;,',','■ mentioned;' room' bbirig 52ft. by 38ft., and' ■ 'having*'. ;;K» amployfloor space' for) two' more '; iriaohines :;;;ii; similar!: to;'; the'new ' one.' The 'full. , width': of:': ?. ■ the..turbine, room;:is: not■ available: along ithe■ -,'-! whole' length '•,of' the' building,•:.'owing'"to jthe> ■',■ in oopstrnctioii -of .&' ' lighting, , .area'■;fptf. tho• prei;i niires adjoining , , the-; eastern, wall. :i The;,, walls.';.'o: are. flhished .in'cement, v and.■'■'along.! the , ■■- wall: : 'Vi; senarating:the':boiler-horise a .dado, of'.opahte-.:. : .':S: tiling extends,'.above; the tnrbinp floor; tO.'a!,-:; 1 ' ,height .of; 6ft.;. , .As,,a''.;modern, switchboardifbr. ; : i: -'S controlling:>-.the■'.■ distribjition'' system -will::re-, '; ,; J 'quire-to- be'' instajled "in /the; near' ; ;futire, fa' ■.■•&!; gallery.-.has: been erected 1 for.,its Reception' in : :'.:S.i :the, north-eait. corner.;, of 'the;: turi>in«.""reoini; : v'J;'ft

Toienable tho; Heavy., , parts > of,';the. turbine "lb'v; ;.£|; be.handled'expeditiously, and safely a twenty-;':? I*. ton 6verhe'ad : travelling crane, '\rith'.'a* > s'pan , ; ; ofV' x" 40lt. I .:.haslbMn:'erected/.^Tbe:;boistjng i .:0r6.58; ,, ;.i; 1 ;S traversing, and longitudinal travelling motions- J?.! are all.;actuated', by'. , hand, .fromHhe plntfona -i ';\f ; secured to. the. : : orane. girders. ■!;'.':' , :'. :. ■■■';'■OQ.The..main, unit, consisting- ■ of; a- fete ain ;:tn*- ;: .;:'?j bine,' alternator;•and:exciter.'ijnqnnted on' : shaft,; stands : on tw6;',.'massiye concrete'' blocks, /:-K-j 'which .'rise'•from' , the'■'basement' , floor;'* several hundred "(feet':" below'•■the" 6treet,ilej>ef,'?;',; to'a'height .of' 14ft;, ; . The. condenser;-.which' 'ii:; :.'V of , the 1 surface'.ty.pe, , . with a/vacuum augmentor ?;'•«■! attached,' stands , ohV .the./basement!" floor be-V'Si tween the : two '■' concrete 'piles, 'and *a ,: '- huge ': :; iV. sluice. valve iscinserted between 'the ooiio'entfer.v ;'■';.: and 'the exhaust: pipe' , leadingfrom ;the:;tur-y&e.'*X--':£'v-:'v/:\.:y-: ■;/•■': :-'/; i"S- ---■ -The "working '.portions'' of-the'; turbine', ar«y;;\y completely:.'enclosed,,'"arid whenvin,. operation'- : -$. a'-part'-.of"the'shaft' is. all ,that ; motion. -.-.To' tho 'layman. , :viewingVthe m'aeliiiiji S4 ; •when tho upper % part. jof >the, pasing: -is ■; t^■'•';:■ i nioyedj however, the appearance , , , of ■"■' the iirtor- i ; 'v. nal portion, conveys/the idea a; bog, bristling with. eharp-pointed..'projectioEa.l.S;':S These : . projections are ■ the. .vanes':: or.-.bladeej' sf« which... run , in series of rings round-the 7 drum, J ;'.:!S whioh is secured ."to: the: shaft; ■:■ Similar':yan'oi.>.;?}f, .fitted -to ■ tho: outward "fixed Vcasing.\ ! pro]ect, f; ::S inward betwoen tho6e »cured to .the'diumVi , When: tho .raaobine 'is j running: the? 6team'.'- : ,'i * enters at' one ;end, '■■ passes first through".a "ring X:.;;:•■ of .'fixed "blades,- and; is' 'then ~ proieoted : in;'a' •.'!?■;? rotational direction'upon the .'adjacent ring., of r-y t i!i moviug' blades, imparting-.a.'.rotationttl,;forceS/S' to ; them.; .It: is then;,; thrown 'back:.uponittie.-.'.Afi succeeding ', ring '..of ■ fixod •■ .vanes,' and :;,the'A re-.:' ■'; ; v action'.iupon the-ncxt7 ring ■' of 'moving:' 'vanes , !: I ':* inoreoses the , rotational;. foroe.'-:> This :p'rt'eess!':: f : i ->'; continues ; until the'steam 1 , passes the last >ing ; : .i-SK: of vanes,"■ and. enters :the exhaustV to 'thei'coi'':-: , ";'I

denser. Tho high rotation velocity given to the rings of \anes is eupphed by the energy of the steam in expanding. The steam, on entering tho machine, has a volume of little •-" more'than 2J cubic feet pur pound, but when it reaches the exhaust it has expanded to ' ncarh 400 cubic footi The secret of economy in running a turbine lies in the use of a high vacuum, and to , secure this tho lmcntoi, the Eon C A Parsons, devised vhat is termed a vacuum augmentor This , consists of a small nozz'e, discharging high presuro steam into a. contracted pipe, inserted into a chest on the side of the mam condenser. It is 'anticipated that with, the augmentor in use a vacuum of 29 inches will be maintained with the now plant, and when it is borne in mind that every inch of vacuum obtained above 25 inches will represent a saving of 5 per cent, the \alue,.of nigh vaouum can be appreciated Tho steam entering tho turbine is controlled by an extremely sensitive governor, designed to maintain a speed of ICOO revolutions per minute In the event of the speed rising aljo\6 a predetermined limit an emergency governor will closo the \alvc lndonendontlj of tho governor Oil Iβ kept circulating through all tho bearings by a rotarj pump, and a cooler is provided for keeping down its torn, perature Tho normal full load of tho machine is 2000 h.p. Then supplied with steam it 15(Jlb. per equaro inch, and into a vaouum of 28 mohos TTndor the Rcmo con. dibons it is capable of dealing with an o\<srload of SOOO h p Tho alternator coupled to tlio turbine shaft can give a normah outpnt of 1500 kilowatts at 2200 volts, 80 cvclcs per ecoond single phase A switch for controlling the alternator has beon installed olose to tho main board m tho old works The air pumps of the condensing plant nre driven by a Belhs and Mnrootu enclosed compound engine, '■' running at 600 revolnhons per minute, Altogether, th« machine is a perfect piece of nork. manship, and should repay the oity by the saving it will effect