Thrust equalizing mechanism for cryogenic turbine generator

摘要

An improvement for a turbine generator or pump having main bearings separated by a span of shaft and a thrust equalizing mechanism adjacent one of said main bearings, the improvement comprising a stationary length compensator interposed between the thrust equalizing mechanism and its adjacent main bearing to reduce the span between said main bearings. Preferably the length compensator is composed of material that shrinks less than the shaft of the generator, and the height of the length compensator, i.e., the compensating dimension, is selected according to desired thrust equalizing mechanism operating parameters over a temperature range.

主权项

1. A thrust equalizing mechanism for use with a hydraulic turbine-electrical power generator in a vertical orientation with vertical rotational axis mounted on a single shaft as a shaft assembly and a ball bearing mounted intermediate the turbine and power generator in a common housing except the turbine runner is mounted on the shaft outside the common housing adjacent the ball bearing, and a containment vessel enclosing the common housing and the shaft in a spaced relationship therewith,
said ball bearing having an inner race secured to said shaft and an outer race loosely mounted against the common housing with a bearing clearance for permitting the shaft to move axially, bidirectionally, a predetermined axial distance, said thrust equalizing mechanism comprising a stationary thrust plate ring means mounted to said housing between the housing and said turbine runner, said runner means including throttling ring means constructed and defined integrally with said runner means on one side thereof for coaction with the thrust plate ring means for defining a substantially fixed orifice for receiving a portion of a high velocity hydraulic turbine flow coupled to impinge on said runner means and a variable orifice defined between the throttling ring means and the thrust plate means and varying in size in accord with said movements of said shaft and receiving the hydraulic fluids at said variable orifice from said fixed orifice, said variable orifice opening being initially greater than said fixed orifice opening, the arrangement and construction of the variable orifice and said thrust plate ring means permits the hydraulic fluid to be conveyed through said ball bearing and through said common housing, said thrust equalizing mechanism further including first ring wear means secured to said common housing and spaced from said throttling ring means and second wear ring means secured to said containment vessel adjacent said fluid discharge end of said runner means, the arrangement and construction of the diametrical spacing of said first wear ring means is defined to be larger than the diametrical spacing of said second wear ring means for creating thrust forces effective to cause the shaft assembly to move axially in the direction of the thrust forces until said thrust plate ring means engages said throttling ring means whereby the variable orifice is closed thereby throttling the hydraulic fluid flow into the variable orifice, said closed condition of said variable orifice defines a chamber between said first ring means and the closed variable orifice allowing fluid pressure to build up therein so when the pressure is build up in said chamber to a preselected level for offsetting the thrust forces created and leading to a movement of said shaft assembly away from said fluid throttling condition and thereby resulting in a continuous fluid flow into the variable orifice and the reduction of the pressure built up in said chamber whereby the balancing of the generated thrust forces occur gradually and smoothly and without overshoot with the continuous bidirectional, alternate axial movements of the shaft assembly, conduit means coupled to said housing for conveying said portion of the fluid in the housing to adjacent the fluid discharge side of said runner means; and a stationary spacer composed of material having low thermal linear contraction such that the stationary spacer shrinks less than the shaft of the generator interposed between the thrust plate and the bearing blocks of its adjacent main bearing to reduce the span between said main bearings, the height of the spacer selected such that it is operative between 70 K and 140 K, the operating temperature range of the cryogenic liquid turbine generator.