NITRATES FEOM ATMOSPHERE SCOTT. 369 



It would appear that the Birkeland-Eyde furnace is preferred to 

 the Schonherr, because it is more compact and cheaper to build. The 

 Schonherr furnace has to be built very high in order to increase its 

 output, and this introduces constructional difficulties: also the diffi- 

 culty of keeping the arc from striking into the side of the tube. 



The present plant consists of 10 generator turbines of 14,450 horse- 

 power each, 5 of which were constructed by J. M. Voith, of Heiden- 

 heim, 5 by Escher Wyss & Co., of Zurich, and 1 exciter turbine of 

 1,000 horsepower by Kriierner Brug, of Christiania. The 3-phase 

 electrical generators coupled to the Voith turbines were made by 

 the Allmanna Svenska, of Vasteras, Sweden, and those driven by 

 the Escher Wyss turbines were supplied by Brown, Boveri & Co., of 

 Baden. The whole of the switchboard equipment was installed by 

 the Westinghouse Co. 



The turbines are fed by individual pipe lines of 1,250 millimeters 

 inside diameter at the top end and 1,000 millimeters inside diameter 

 at the bottom end. The length of each pipe is 720 meters (2,360 feet) ; 

 the upper 300 meters consist of riveted pipes, and the longer lower 

 part for higher pressure consists of welded pipes. The riveted 

 pipes were supplied by Frederikstad's mek. Verksted, Frederikstad, 

 Norway, and the welded pipes by Actiengesellschaft Ferrum, Zawod- 

 zie near Kattowitz, Germany. The supply and laying out of all of 

 the pressure pipe lines was done under the superintendence and on 

 tlie responsibility of J. M. Voith. 



Each turbine is designed to work with a net head of 274 meters, 

 and a normal output of 13,000 horsepower, when running at a speed 

 of 250 revolutions per minute. The output may be increased to 

 14,450 horsepower. 



The main sluice valve of 1,000 millimeters is fitted on a taper con- 

 necting pipe and the valve is operated by hydraulic pressure by means 

 of a cylinder with piston and a distributing valve. The piston rod 

 carries a relay which connects it to the valve, thus preventing the 

 latter opening or closing too quickly and insuring perfect safety. 

 The distributing piston is designed and dimensioned to allow the 

 valve being opened or closed under full pressure. This valve is 

 provided, however, with a by-pass valve 150 millimeters inside 



diameter. 



The turbines are provided with twin Pelton Avheels, each of which 

 is driven by two nozzles. In the Escher Wyss turbine the lower jet 

 does not strike the buckets until the latter have cleared the upper 

 jet. Each of the rimner wheels, which are mounted 1,800 millimeters 

 apart on a horizontal steel shaft, consists of a separate hub of cast 

 steel, and on the circumference of each 22 cast-steel buckets are 

 fastened. The buckets are held by means of two rings, which pro- 



4486.'?''— SM 1918 24 



