Document vBYmkjwbZopV1Z9Gozb5VXJ79

Two pumps are motor driven, and one U dual driven. The latter connect# solidly to the driving motor on one end and through o clutch-type coupling to o turbine drive on the other end. The clutch-type coupling allows the turbine ' to remain at rest when the motor drives the pump, but engages automatically as the turbine comes up to speed. The 'boiler-feed-pump turbine operates in emergencies only, exhausting to the deaerating heater. The boiler feed pumps discharge through tho 14th, 10th and ?th stage heaters and feedwater regulators to the economirers and superheat-control con* denaera in the saturated-steam headers of the superheaters. From here the feedwater passes into the boiler drum for evaporation. Atr-Oes Cycle. One vane-controlled 3000-KW TUBBINfi-CIHIRATOR lokes high-presuiro stcom ond exhoush it tonah in existing 325-pslp totton. Cxhoust helps develop lull output oi l-p turbine. forced-draft fan serves eaeh boiler, dis charging through a regenerative oir pre heater. Air leaving the preheater at about 510 F passes to the burners as secondary air with a small percentage going to the pulverisers to servo as pri mary olr. A tempering fan between the two pulverisers of each boiler supplies tempering sir to the primary air at the pulverizer inlet. Primary olr passes through the pulverizers and exhausters to the burners, mixing with the secondnry air as it enters the furnace. Flue gas leaving the boiler passes through the economizer and air pro heater before entering electrostatic pre cipitators at about 310 F. - The precipitators, which have a guar anteed Ayash-removal efficiency of 94%, ere used both to minimize induced-draft fan erosion and eliminate, os much as possible, any smoke nuisance. Smoke would be particularly objectionable to the Middletown airport adjacent to the station. Cos leaving the precipitator passes through one indueed-droft fan for eaeh boiler to a single reinforced concrete chimney common to both boilers. Each i-d fan has a double-extended shaft with a 500-hp 900-rpm motor on one end and a 250-hp 720-rpm motor on the other. Flexible couplings attach both motors rigidly to the fan. The 72(Vrpm motor may rotate at 900 rpm without ill effects. These 2-speed fans have inlet- vane controls. Fuel-Ash Cycle. Coal is delivered on a double railroad aiding, which passes through a new track-hopper house. Cer-ihswing equipment coosisting of four pits, each with tvo o3 burners, precedes the track hopper house. Cars entering the house ire spotted over either of two 70-ton cod' hoppers. A car vibrator carried eter these hoppers by a small overkead osae speeds up coal-car emptying. Sis rw ciprocating feeders remove cos) frets the hoppers at 300 tons per hr feeding It to a flight conveyor, which discharges to a 2-roll crusher. After reducing coal to 1%-ln. disthc crusher discharges it to a grsdry-dto charge elevator carrying ii to efthet is inclined belt conveyor for muupctU* tion to a transfer tower, or to a iwbih type stockipg-out chute. A bulidow moves coal to the slock pile ^hea needed the`bulldozer moves it bsek tss reclaiming hopper ot the track bopp* house. An aprbn feeder then mores it aawtjfrht to the crusher Inlet from where il e* either pass through or around B* ^)| SdiOW !bj*r____ crusher to the gravity-diichnrgs, .**' Ll32.5Z * Bcdtr and tconomittr Net dolto* heat 10,990 6tu per kwtr Surga 'tank r-7aws"-i0E2lLvJLvri vator. Coal delivered to the transfer discharges either to a second belt carrying it to the new conl-toff*" room, or to a revcrsiblo-fiight delivering to the bunkers to to, section of the plant- This conveyer be fed ot the opposite end by , valors in the existing plant, ] pair of the gravity-discharge d ^ Finn I 1 t . _ ----f.--I-?" Flight conveyor, when ope**" verse, discharges at the T-' to the inclined belt serving - bunker room. Coal entering bunker, room discharges ts CONSTANT-PRESSURE DEAERATOR receives steam from three sources, the output.of, one evoporotor, IOth turbine'stage at ftghr-f^od?, 14th stops during, heovy loods horizontal belt conveyor, .-jib. reversible shuttle belt convFyw*\^ distributff .liie.coal through -,i_ '_ bunker seol to the new bunker*: < 66 (672) POWER J 0X1 OUAL-DAIVIM AND TWO MOTOA-ORIVCN feedwater pumps for the hlgh-presr jy,, dollars ore loeoted on the moln turblno-room floor level near backpressure unit Coal tearing the bunkers passes through two feeders per boiler to its respective Herding pulverizers and ex hausters lo the burners. Each boiler has siz burners horizontally opposed, *)! three in front and three in rear of each {furnace. This type firing was selected oa lbs basis of results si tho Gilbert, (Wot' Reading and Wcstover Stations, which indicated the effectiveness of op posed firing in lowering carbon losses fa the flysth. Mew furnaces at Growlord are provided with overfire air aezzles so this feature may be added si a later date if considered necessary .t improve operation. . Hydraulic jets remove ash from the holier ash hoppers, the ash then aluices .to a clinker grinder mounted over an kih lump. A vacuum system, which collects soot hoa the chimney base and precipitator tappers, mixes it with water when pass- a* through an ejector immediately {*we^`nl the aab samp. Soot from the r** P8**** of the boilers flows by grov"T to the ash hoppers. .. Either of two rubber-lined centrifugal Waps passes the ash and soot from the tump to a settling bosio adjacent itotioo. **^*P' ^*r for makeup from the Susquehanna River &**eli * mcc^Qn'cal trash rake ond screen, ond is chlorinated. 4tu n8lCf '*tl,cn Pulped to a Spsulj^jJsPtecIpitBior where chemicalcoagu- zhrmi/0" c,nr,fic*ion ore effected by Foljow,u,n #ulphote and soda ash. filters T Pr0CCM grovity-type lag. F;omPjeto the mechanic^ filter- pnnB. 9n> fillered-woler clear well, out^ w*ter through fully outo- softeners to o deaerating- I 6 Vy e g L-, * 19-tfl typo evaporator preheater. Part of the vopor from tho No. 2 evaporator heats water in the tray-typo deaerating pre heater. Makeup water flows by gravity from the evaporator preheater to the shells of two evaporators. One receives its besting steam from the lOth-stoge bleed and discharges all its vapor to tho de aerators in the old plant. The second evaporator, No. 2, takes its steam from either the 10th- or 14th-toge blood, depending on the load the turbine car ries. Part of the vapor goes to the evap orator preheater for heating - as men tioned, and the remainder 'flows to the new deaerating healer where it .joins the cycle feedwater. Continuous blowdown lines maintain boiler-drum concentration at a level not exceeding 500 ppm. Cooling Woter. Circulating water from the Susquehanna enters an intake channel with its mouth slightly'down stream from the screen houses. This forces ihe water to make a turn of about 130 degrees when leaving the river, in this manner keeping a large percentage of tlte large pieces of floating debris and ice cakes from entering the channel. A bypass channel with an adjustable weir connccla the discharge channel with the mouth of the intake channel. The weir level is lowered during periods when needle ice forms in the river. This recirculation has proved very successful in minimizing difficulties encountered from tee in the intake channel and in the screen houses. A mechanical trash rake clears the trash rack, composed of wrought iron bars on 4-in. centers, during floods or when the river is filled with leaves dur ing the fell of the year. After passing through the trash rack, water flows through two traveling screens. These screens have segregat ing sluice gstes so either screen well may be pumped out and the screen r* paired without use of stop logs and without interfering with operation of the other screen. Each screen has a screen-wash pump and a differentialpressure switch. The latter automatic ally starts the proper screen-washing pump when the woter-pmsure drop across the screen exceeds 2 In. of water. The pump builds up pressure and pro vides a cleaning spray for tho screen. A pressure switch connected to the spray line automatically starts the screen ro tating. A time-delay relay prevents the pump from stopping before the screen has made ot least one complete revolu tion during an operation. Intermittent chlorination of tho water leaving the ocreens prevents organic growth fn the tunnels, pumps and con denser. Water flows through two hori zontal centrifugal circulating pumps to two MoeNeiO reversing valves, ond then proceeds through the 2-pass surface condenser, which Is equipped with in ternally bronze-sprayed welded^teel divided water boxes, to the discharge tunnel; end over a sealing-chamber weir to the river. The MacNeill reversing valves, which aro motor operated, allow the condenser to be backwashed without interfering with normal operation. Summary. Crowlord .Station was de signed for reliable, troublefree, efficient operation et reasonable cost It was necessary to balance these items against each other; reliability and low mainte nance were given primary consideration. This procedure was responsible for the decisions to (1) equip all closed feedwater heaters with drain cooler sections to minimize flashing of heater drips and resulting higher maintenance (2) select closed heaters in place of open (3) select 94% efficient precipitators to minimize i-d fan erosion and amoke nuisance (4) select e coal-handling system that serves the entire plant and can be fed by two independent sets of elevators (5) select a makeup system that provides distilled makeup for the old plant as well as the new, since the cycles will be interconnected. This station lays no elatm to the low est heat rate on record, nor to the lowest cost per kw Installed capacity, but engi neers end operators will consider the project well worthwhile il it proves reli, able in operation, requires a minimum o! maintenance, is simple to operate at reasonable cost. CeiHanad on poga 95 (673) 67