Show NOVEL HYDRO PNEUMATIC PLANT installation made for the snowstorm mining company of idaho A novel hydro pneumatic installation has recently been made by the snowstorm mining alining company operating in the coeur d dalene alene district idaho the plant consists of a horsepower air compressor rope driven by a pelton water wheel and an induction motor direct coupled and working either independently or in parallel with the water wheel unit when the latter rotates at R P 21 due cue to the variable water supply available for the wheel and the continuous continuo 1 us operation required of the compressor it was necessary to install a horsepower elec trie motor to help out during the period that the water wheel was unable from lack of water to drive the compressor at the required load and speed current for the motor is secured from a transmission line of a commercial plant supplying the district mounted on the electric motor shaft is a 46 inch diameter rope sheave which drives a fourteen foot sheave on the compressor the compressor sheave is grooved for nineteen one and a quarter inch diameter manila ropes and the sheave is east cast with sufficient weight to permit obtaining the requisite flywheel fly wheel effect for the compressors operation the american can system of rope transmission is employed the tension sheaves and rew reminders winders re inders being placed above the driving ropes and located in such a manner as to cona conserve erve floor space and head room to the greatest extent the water wheel equipment consists of a twin runner pelton doble tangential water wheel unit one runner being approximately forty four inches in diameter and is capable of developing horsepower when running at a speed of R P M this speed also coincides with the full load speed of the induction motor the other wheel is approximately two inches in diameter and develops horsepower at a speed of R P rim IM both water wheels are keyed on the same shaft which is extended and coupled to the electric motor shaft carrying the driving s sheave heave one of the other wheel must develop the requisite power when running at its correct speed in this event the idle wheel the pressure water being shut off from same simply r rotates on the shaft without performing useful work other than providing additional fly wheel effect for the installation both wheels never develop power at the same time T the he requirements or of the plant call for foil the highest eff efficiency over a wide range of operating conditions involving a per cent fluctuation of the power water supply and a variation of the compressor speed hence the power required tor for same depending upon the demands or the ehe air line it is necessary during certain times lines that horsepower be delivered to the compressor sheave when the latter rotates at 95 R P CM if there is sufficient water available the 44 inch P pelton elton wheel develops this power without assistance from the electric motor should the water supply be insufficient current is applied to the electric motor to supply the deficiency at other times and over a period of several hours duration per day the compressor output is reduced to an amount corresponding to 58 R P INT in this event the water for the 44 inch pelton wheel is shut off and it rotates idly while the 72 inch pelton wheel is allowed to develop the power without assistance from the motor while either wheel may develop its full power when operating at its correct normal speed of R P P 31 for the 44 inch wheel and R P ar for the 72 inch wheel quite a wide variation of speed below normal may be secured hence a most flexible installation has been secured the novelty of this plant consists of th application of a variable speed variable power tangential water wheel unit to a constant speed induction motor driving a compressor the plotted efficiency ncy curves of the water wheels is quite flat for a range of power between and 30 0 horsepower for the 44 inch wheel when rotating at R P AT and for the 72 inch wheel between and horsepower output at 11 R P al for slight reductions of speeds below normal the efficiency holds up remarkably well as was predicted these results are obtainable from the type of ellipsoidal water wheel buckets employed in conjunction with needle regulating nozzles the latter discharge a perfectly circular solid jet under variations corresponding to full load of the respective wheels down to about ten per cent of the maximum load the hydraulic surfaces of the water wheel buckets are ground and sharpened and the whole water wheel unit especially developed for this particular plant to safeguard the water wheels from rupture due to centrifugal force they are designed to operate under emergency runaway conditions of double the normal speed without stressing the i parts beyond their elastic limit the hydraulic apparatus was designed and constructed in the san francisco works of the pelton water wheel co |