Niagara Falls 100.000-Hp. Development

Niagara Falls 100,000 Hp. Development [19 ure if large amounts of ice should be flowing in the basin. It was assumed that very little ice would be carried into the forebay as the velocity of the water in the basin is about 4.5 ft. per sec. and the water going through the ice boom from the basin is 2 ft. per sec. This was very well proved by the experience of last winter. By the construction of the ice boom system off Port Day in the Niagara River, it was believed that there would be very little trouble from ice in the forebay, but there will always be some ice form in the canal and there will always be the possibility that an ice boom might break and a large quantity come down the canal. To take care of this a spillway and ice chute has been constructed. The old Station No. 3 had ice gates and an ice run running from the outside of the curve shown on the accompanying plan. This old ice run curved at a right angle and discharged into what had been the abandoned wheelpit of a large flour mill. This pit extended 70 ft. down from the top of the cliff, where the water and ice were discharged on the site of the new power house. It therefore became necessary to build a new ice run running directly from the old spill- way gates, to the river and passing under the new power house. Its location is shown also on the plan. It is a concrete lined chute 20 ft. wide and 15 ft. deep, inclined at an angle of 60 deg. with a horizontal with a parabolic curve at the top and bottom to connect the horizontal sections with the slope section. The concrete lining of the chute was intended to be 18 in. thick, but it over ran this as part of the excava- tion was in shale which disintegrated after being exposed to the air. A concrete roof has been placed upon this chute and will later be covered with rubble stone masonry to look like the natural cliff. The hori- zontal part of the chute which passes underneath the power house is carried 60 ft. west of the power house so that the water, ice and débris will discharge into deep water of the river. Details of Turbine Settings Hydraucone and Center Cone Draft Tubes Used with Vertical Type Unit—Main Foundation Slab is 11 Ft. Thick By Louis S. Bernstein Designing engineer Niagara Falls Power Company THE hydraulic efficiency of the waterwheel unit was the governing feature of the design and for this reason and the fact that the size of the machines are larger and of different type than any in present use, radical departures were made as compared with the existing plants of the company. The fundamental features of the changes are as follows: (1) The ver- tical shaft type unit was adopted. (2) The usual bent tube type of draft tube was abandoned for the more efficient ones known as the “hydraucone” and the “cen- ter cone,” respectively. In plants where the combination of a moderate dis- charge and the bent-tube type of draft tube exists, the problem of supporting the turbine and generator is comparatively simple, as the loading is usually small and the natural arch of the bent tube acts as the support on one side, and the concrete mass foundation as the sup- port on the other side. It can readily be seen that as FIG. 26—VERTICAL SECTION THROUGH TWO TURBINE SETTINGS the unit becomes larger and both the clear span of the tailrace and the load to be supported becomes greater, if the arch type of construction is not available, the problem of supporting the unit becomes more compli- cated; in special cases, where the turbine and genera- tor are of extreme size and weight, special provision must be made to take care of the vibration of the ma- chine as well as the superimposed loads. There are two types of units, one being installed by the Allis-Chalmers Co., and the turbine of the other by the I. P. Morris Co. The draft tube of the Allis- Chalmers unit is known as the “Hyrdauconp ” whilp FIG. 27—ICE CHUTE BEFORE COVERING that of the I. P. Morris is known as the “center cone.” In each case tne clearances of the tailrace and the other hydraulic features of the draft tube were determined by the makers of the respective turbines and the hy- draulic engineer of the power company. Details of the machines and their appurtenances will appear in a later article. The draft tube of the Allis-Chalmers unit consists of a horizontal reinforced-concrete plate supported by three reinforced-concrete walls, the entire structure being centered in the tailrace directly under the di»-