Plant Differs from the Ordinary Commercial Boller-Room.
The steady growth of a tall creamcolored chimney at the northerly end of the "new site of the Massachusetts Institute of Technology marks where the new boile:-hou.sc is being buP.t, ami with such rapidity that a month hence will see it in commission. The strain will then be available for drying the plastering that is being applied in quantity to the walls of the offices; study rooms and laboratories. The now plant will at the beginning develop about 2.00Q horse-power In steam. It is modelled on the lines of a very modern power hoqse but unusually condensed, being ten feet narrower than any other station of similar capacity. This narrowness Is because the building lies in the 90 foot strip belonging to Technology between Vassar street and the railway.
Thi latter affords economical delivery of coal in large quantities, and witli mechanical stokers and otlfer appliances the coal is not handled by men at any stagre of its use. The boilei s lie transverse to the street and railway, being so placed in order to make more easy the addition of other boilers as the future needs of the growing Institute may demand. There will be 1,650 horse-power of new boiler. 1 - and 4(HI i emoved from Trinity place, the new ones being of the Babuock and Wilcox pattern, with HI ley stokers and working under forced draught. one especial feature will be that the boilers will be equipped for heavy overloading, which Is not to be taken In the sense that they will be other than exceedingly safe, but that they will be able bo evapoiate water to an almost unlimited extent in ratio to the Combustion.
When not in demand any boiler will be automatically slowed down. There are features In this plant that make It different from ordinary commercial boiler rooms.* It will itself be a laboratory for the use '""of students, it will care for lighting, heating and power and will be built on the lines of a big central station. The laboratory use likely to demand a high peak fHad, which tlie establishment must be able, to care for, but at the same time, the load factor is comparatively low.
The location of the plant, besides affording th" convenience and economy of direct coal (t-elive: ;-. is sullieiently fa: from *he educational and student portions ol the TechnMsffy assemblage <il structures to be no 'nuisance In point of dust, while the chimney will group Itself with the nearby commercial chimneys of the busy city The boilers are of the wrought-steel. Water-tube type, designed for 175 deg: ees working pressure and superbeating the steam 100 degrees F, an Important economy in the use of the steam turbine.
Tlie stack measures t ■■< feet in Its bore and IS feet in outside diameter and when the enpping Is placed will stand 180 feet above Its base. To convey steam to the buildings .■ml laboratories where it will be needed a subway of re-in forced concrete is being built, about seven feet Square In Inside measurememts and 626 feet long. It Is to connect with the educational group bhrOUgih the administration building and from this the steam will be distributed to the points where it Is needed.
For the present the supply will be a 20-lnch pipe for Utilitarian purposes, a ten-inch pipe for l'u*:Dishing the laborntories and n flw-inch return for water from condensation. For furnishing condensing water for the turbines a concrete main lias been laid. Thin conduit Is 30 inches in diameter, running back from thi' Charlei River BaSlll along Ule western edge of the great court. It will be above a quarter of a mile In length, and In rainy weather it will collect the rainfall of the area and turn It tn for condenser water. The e'eotrical outfit is an Interesting one since the engine room will serve for sub-station as well as for central station. The initial equipment will include three turbines direct-connected to generators, one of 780 kilowatts, a second of 500 kilowatts and the third of ISO kilowaittJs, furnishing threephase current at 2,300 volts. There will then be one 150 k. w. turbine mil two 150 k. w. motor generators furnishing direct current at IHi and 2 20 volts, and tw,» 35 k. w. exciters, >ne each steam and turbine driven. The current In various voltages will be conducted to the buildings and labuato; les In lead-covered cablet* running In a special conduit. The steam laboratory itself Is to be located In the long building near nnd parallel to Massachusetts avenue. High pressure steam coming through the inbway will be distributed to twt,
mains below the ceiling of the first floor. There will be a superheater he.c connected at will Wifeth the machines where experiments are to be itiado, The condensers of the various engines] in this laboratory are tn the basement nnd take the cooling water from one of the large hydraulic canals, passing the warmed water into a hot wate ■ return. In the Imsemetu there will be apparatus for determining the flow of superheated steam through orifices or turbine nozzles. On the first floor of this building will be loea-ted the engines which make a formidable showing. There will be a Curtis turbine of about 75 kilowatt capacity, a 30 horse-power CorllSß with dynamometer attached to Hie 11 y wheel, a 336 horse-power McEwen tandem compound, n compound and generator of the same make of 250 horsepower, and a triple expansion Corliss. These engines will be • anged along the western wall of the building. On the opposite side of the great laboratory will be a Rrown engine driving a three-stage compressor which compresses air to 2,500 lbs. per ■q.UAI*S Inch. There will be two or three other compi essors, and a few miall engines to Illustrate different types.