Document g2O65gOLp7vgrvXRaVwaeRVRN

"33OPIRATING FLOOR OF TWO NEW UNITS In luifeln., boiler ond "' oil orrongod on lomo loyol. K> oponrtor .> mo|or equipment Irom conmjrm STATION P fairly high steam pressure of 1360 palg proves more fAvorsble than the lower pressures; the seven oil burners serv. the ground door between the wayand the boiler*. Salt-waterW01 pumps are in a pump house sdjac ing each boiler furnace have a 20:1 the wall of (be condenser 8fg*--Vj\._ load ratio. Attemperators in the lower Turbine Room. Two 100.000-kwjic boiler drum> serve to prevent excessive with corresponding TSOO-kw. houjZJ'' Pacific Gat and Electric Ca thermal shock on the turbines during periods of quick pickup. bines are being installed. The tw1 compound double-flow mala twfc as well as the auiomaiic-eiiracjJo* erects extension in San Fran The forced* and induced-draft fans denting house turbines, use.^iL., cisco that overshadows exist snd four oi the boiler-iced pump* will operate st ell times at full speed, ready steam at lSOO.psig and 950 iFjSj ing plant. Fast load-pickup needs dictate many design features of two new units for full-capacity demands. Automatio controls provided wherever possible in sure rapid functioning of all .unit ele ments. * Confronted Control. The control room bleed points supply steam to feedwater heaters and ao e**P[ The bouse units provide .^j pendent electric supply'for UUries, and will always be features the general layout; it puts the supplying extraction steam(Stj operator at the key point close to house turbines, boiler feed pumps and main stait S-psig pressure to the d<|L feedwater heaters. Normally,5$!! aerator takes its steam fron?;^ AJ part op tee vast system that serves much ot the suto of California, turbines on one hand, and the boilerroom firing aisle on the other. Tile unit of the corresponding Whenever moderate amounts.]! with hydro stationsas the predominant fundamental plan places the miln-tur- 5-piig steam become ovsilsW# energy source, the duties of the new bine-generators lengthwise in the tur be inducted in the bleed ope&j|j units at Station P differ from most stesm plants. The 215,000-kw extension, scheduled to go into operation in late bine room with the steam ends facing one another. This permits a convenient symmetrical arrangement of main house unit. .irS -The eingie-pasi main ccndeuj-g, 40,000 sq ft -of surface io'.slgSf 1946, will at times run at low loads, steam piping from the steam generators. brass tubes arranged In dlridB and yet may-be called on to develop full - Auxiliary equipment is divided be load in a matter of 20 to SO seconds. tween two levels. Boiler-feed* pump Equipment must be properly selected uni}* and feedwater evaporators are for .this service;, for . Instance, four . In the-turbine,room on.the operating boxes. Steam-jet air ejectofs^S condensers, which have stqrageitjrpe-.hotwell^. Each*. has two 1500-gpm condens1^ -eteast generators are better than two; floor, while all other auxiliaries are on 14 (566) HEAT BALANCE INCLUDES automatic-extraction condensing, house turbine wt supplies the bulk of dcoeratlng steam, obsorbs oxeess l-p st'oom at low loods operate automatically in response to water differential controls. Both Intake tunnels can be used for all units. Steem Generator*. Two radiant boil ers with 475,000-lb-per-hr steam rating and 517,500-lb-per-hr steam capability serve each of the two main turbines and their corresponding house units. Steam generators located outdoors have an umbrella roof, but the firing aisle Is .completely enclosed. This was consid ered necessary in view of the fog snd temperature range prevailing in this area. Each steam generator has a 2-section superheater with intermediate drum-type attemperator, ah economixer and a tubular sir heater. Each of the steam generators has one draft-fan unit consisting of one overhung single-inlet forced-draft fan, one double-inlet induced-draft fan and a 2000-hp 4160-v driving motor on a single shaft. These units are on the east side of eaeh boiler at the operating- floor level. The two boilers of- each unit are served by a single gunito-lined steel stack, 15 ft 4 in. die by 200 ft high. Stacks are self-supporting from tbe ground. Sfracture. Steps had to be taken to guard against the effects of dsrtbqoake' shocks. .In the boiler area tbe lootings are tied together by reinforced concrete beams. The building was designed to resist shocks with a seismie factor of 0.2 C, including half of tbe live loads. While boilers and fans.ere essentially outdoors, the remainder of the equip ment is fully housed In more or less .conventional fashion. Btactrkol System. Each of the 13.8-kv 3-phase 60-cycle main generator*^ connects to a step-up transformer bonk of three 29,800/37^S0-kve tingle-phase 115-13.8-kv transformers. Each 13.8-kv generator lead is tapped te supply a station-service transformer bank of three 3,334/4,444-kva single-phase 13.8-' 4.16-kv transformers. Each main generator hat a 300-kw motor-generator eet for excitation with direct-connected amplidyne; in addi tion, there ia a spare set for emergency. The motor-driven station auxiliaries are supplied at 4160 and 480 v. Motors larger than 125 hp are rated 4160 v, the-smaller motors 480 v. Two trans former banks and the two house units .supply the station auxiliary power. These sources connect to tbe 4160-v switchgear on the ground floor-under the control room. From this same lo cation four roetolclad unit substations supply the circuits running to 480-v load-center switchgear at strategic points throughout the plant. Dry-type transformers operating at 460-208/120 v supply the plant lighting system. A 60-ccll 125-v storage battery and two 25-kw battei7<harglng generator sets provide for eircuit-breaker-conirol circuits, (or valve operation and emer gency lighting. Distribution switchboard is in the central control room. A special onnunciator signal system consists of banks of large light-type indicators mounted above the various control boards and in tbe control-room walls between turbine and boiler rooms. These will prove valuable under emer gency conditions. . Table of principal power-plant equip ment is given on following page. Acknowledgment*. Power is indebted to M W Carty of Stone ft Webster En gineering Corp, and to the Pacific Cas and Electric.Co for this article's data. 1587) n