Vertical Turbo-Generators

Progress, Volume VIII, Issue 8, 1 April 1913, Page 429

Vertical Turbo-Generators

To illustrate the advantages of the Vertical Turbo-Generator, the results of their introduction at the city of Bradford’s electric works, England, will prove interesting. The local authority of Bradford were among the first to give a supply of electricity from a munici-pally-owned statoin, having commenced supply as far back as 1889. The present station, viz., Valley Hoad, was opened in 1897, and epitomises the growth of electric supply from that year down to the present time. The earliest generating units consisted .of Willan’s triple expansion engines and Siemen’s bipolar generators of some 300 k.w., and these still do good service. Among the more recent additions are four 1000 k.w. units, driven by Musgrave and Cole Marchant, and Morley engines, two by each firm. There was still room for another set of the same size, but this would have filled another building. The growth of the demand has, however, been so rapid that provision had to be made for a greater capacity than this, and on the space originally intended to be occupied by a 1000 k.w. set no less than three vertical turbo alternators, having a capacity of nearly 10,000 k.w., have been erected; indeed so conservative is the rating of these units at 3000 k.w. each that the rating may be said to be 10,500 k.w. Put another way, floor space originally intended to hold a 1600 h.p. vertical steam engine is now occupied by steam turbines of 15,000 h.p. The essential features of the two sets are set forth in the accompanying table, which emphasises the change which has taken place in electric power station design during the last few years.

Each generating unit has a sub-base, which contains the condensing plant; this is of the Wonttington type, and will maintain a vacuum of 2Tin. when dealing with 72,000 lb. of steam ’per hour, 27|in. when dealing with 60,000 lb. of steam, and 27|in. when dealing with 49,000 lb. of steam. The cooling surface is 8200 ft. A feature of this plant is the twin circulating pump, which will deliver 8000 gals, of water per minute against a head of 60ft. It is separately driven by a 200 h.p. Curtis steam turbine, running at 1700 revs, per min. This method of driving the auxiliaries by steam turbines is becoming popular because the auxiliary plant, besides being as easily started as an elec-trically-driven auxiliary, occupies a smaller amount of space, and the exhaust steam from them may be profitaby utilised in a feed water heater. The steam is supplied as to the reciprocating sets at 180 lbs. per sq. inch superheated about 100 degrees F.

Ver'ical Steam Turbine Vertical Reciprocating Steam Engine (Cross Compound) Output in kilowatts of dynamo 3,000 1,000 Brake horsepower of prime mover 5,000 1,600 Revolutions per minute 1.500 85 Floor space occupied square feet - 57 683 Diameter of largest rotating piece 6ft. 4in. 20 ft. Weight of rotating parts 15 tons 103 tons Weight of plant complete - 60 tons 193 tons Steam used per hour - 48,000 lbs. 20,000 lbs. Coal used per hour ... 2.6 tons 1.1 tons Steam consumption per unit 16 lbs. 20 lbs.