ORC Turbine and Generator, And Method Of Making A Turbine

Abstract

A turbine-generator device for use in electricity generation using heat from industrial processes, renewable energy sources and other sources. The generator may be cooled by introducing into the gap between the rotor and stator liquid that is vaporized or atomized prior to introduction, which liquid is condensed from gases exhausted from the turbine. The turbine has a universal design and so may be relatively easily modified for use in connection with generators having a rated power output in the range of 50 KW to 5 MW. Such modifications are achieved, in part, through use of a modular turbine cartridge built up of discrete rotor and stator plates sized for the desired application with turbine brush seals chosen to accommodate radial rotor movements from the supported generator. The cartridge may be installed and removed from the turbine relatively easily for maintenance or rebuilding. The rotor housing is designed to be relatively easily machined to dimensions that meet desired operating parameters.

What is claimed is: 
     
         1 . A system for converting heat energy into electricity, comprising:
 a turbine having an inlet, an outlet, a stator and a turbine rotor, wherein said turbine is configured to receive a first volume of working fluid via said inlet and to exhaust said first volume of working fluid via said outlet, wherein said turbine rotor rotates about a rotational axis; and   a generator coupled with said turbine, said generator having a stator and a generator rotor, said generator rotor being coupled with said turbine rotor so as to be rotatably driven by said turbine rotor about said rotational axis, said generator including a gap between said generator rotor and said stator for receiving a second volume of said working fluid, said gap having an entrance port and an exit port, wherein said generator is designed so that, in operation, said second volume of working fluid present in said gap cools said generator rotor and said stator.   
     
     
         2 . A system according to  claim 1 , further including a vaporizer for receiving said second volume of said working fluid and vaporizing said second volume before introduction into said entrance port of said gap. 
     
     
         3 . A system according to  claim 1 , further including an atomizer for receiving said second volume of said working fluid and atomizing said second volume before introduction into said entrance port of said gap. 
     
     
         4 . A system according to  claim 1 , wherein said turbine includes a hood with a backplate and said exit port includes a plurality of orifices positioned in said backplate. 
     
     
         5 . A system according to  claim 1 , wherein said turbine has a through flow rate and said second volume of said working fluid travels through said gap with a flow rate, further wherein said second volume of said working fluid is introduced into said gap to have a flow rate of no more than 50% of said through flow rate. 
     
     
         6 . A system according to  claim 1 , further including a condenser and a pump, wherein said condenser is fluidly coupled with said outlet of said axial turbine to receive and condense said first volume of working fluid into said second volume of working fluid and to exhaust said second volume of working fluid into said pump, wherein said pump is coupled with said entrance port so as to deliver said second volume of working fluid to said gap in said generator. 
     
     
         7 . A turbine cartridge, comprising:
 a plurality of rotor plates, each having a centerline, a first contact surface and a second contact surface contacting said first contact surface, said first and second contact surfaces being substantially parallel and each of said first and second contact surfaces being flat in the range 0.00005″ to 0.020″, wherein said plurality of rotor plates are positioned proximate one another so that said centerlines of said rotor plates are mutually coaxial;   a plurality of stator plates, each having a centerline, a first contact surface and a second contact surface contacting said first contact surface, said first and second contact surfaces being substantially parallel and each of said first and second contact surfaces being flat in the range 0.00005″ to 0.020″, wherein said plurality of stator plates are positioned proximate one another so that said centerlines of said stator plates are mutually co-axial; and   wherein said plurality of rotor plates are positioned in alternating relationship with corresponding respective ones of said plurality of stator plates so as to define a multi-stage rotor assembly with an upstream direction, further wherein at least one of said plurality of rotor plates includes a first plurality of vanes with an axial chord and an adjacent one of said plurality of stator plates includes a second plurality of vanes with an axial chord, wherein said first plurality of vanes is axially spaced from said second plurality of vanes to define a space having an axial dimension that is no more than two axial chords to ¼ of 1% of an axial chord, as measured with respect to the axial chord of the one of said rotor plate and stator plate immediately upstream of said space.   
     
     
         8 . A turbine cartridge according to  claim 7 , wherein said space has an axial dimension that ranges from ⅓ to 1 of said axial chord of the one of said rotor plate and stator plate immediately upstream of said space. 
     
     
         9 . A turbine cartridge according to  claim 7 , wherein said plurality of rotor plates are secured with respect to one another and said plurality of stator plates are secured with respect to one another and positioned relative to said plurality of rotor plates so as to form a unitary cartridge system. 
     
     
         10 . A turbine cartridge according to  claim 9 , wherein said unitary cartridge system is designed to be releasably coupled to a turbine housing. 
     
     
         11 . A system for conversion of heat energy into electricity, the system comprising:
 an electric generator having a proximal end, a distal end, a generator rotor and a stator, said generator rotor being disposed for rotational movement within said stator about a rotational axis, said generator also including a first magnetic radial bearing positioned adjacent said proximal end and a second magnetic radial bearing positioned adjacent said distal end, said first and second magnetic radial bearings surrounding said generator rotor and retaining said generator rotor, during operation, in substantially coaxial alignment with respect to said rotational axis; and   a turbine having at least one stator and at least one turbine rotor supported for rotational movement within said at least one stator about said rotational axis, said at least one turbine rotor being coupled with said at least one generator rotor so as to rotationally drive said generator rotor, said at least one turbine rotor being attached to said proximal end of said generator in an overhung configuration such that no radial bearings are included in said turbine for radially supporting said at least one turbine rotor for rotational movement, said at least one turbine rotor having a radially outermost surface and said at least one stator having a radially innermost surface, said turbine further including at least one seat, a first brush seal engaging said radially outermost surface of said at least one rotor, and a second brush seal engaging said at least one seat.   
     
     
         12 . A system according to  claim 11 , wherein said generator rotor is free to move a first radial distance out of coaxial alignment with said rotational axis when said first and second magnetic radial bearings are not activated to radially support said generator rotor, further wherein said first brush seal and said second brush seal have a radial length and rigidity selected to support said turbine rotor so that said turbine rotor, and in turn said generator rotor coupled to said turbine rotor, do not deviate more than a second radial distance out of co-axial alignment with said rotational axis, said second radial distance being less than 0.8 times said first radial distance. 
     
     
         13 . A system according to  claim 12 , wherein said first brush seal is spaced 0.0000″ to 0.010″ from said radially outermost surface and said second brush seal is spaced 0.0000″ to 0.010″ from said seat. 
     
     
         14 . A system according to  claim 12 , wherein said second radial distance is 0.3 to 0.6 times said first radial distance. 
     
     
         15 . A method of making a turbine for driving a generator, said turbine having a power output sufficient to drive the generator to produce electric power in the range 50 KW to 5 MW, the method comprising:
 providing a universal turbine hood having a floor with a first thickness;   providing a rotor stage having a radial height, the rotor stage positionable in the turbine hood; and   machining material away from the hood to decrease the thickness of the floor and machining material away to decrease the radial height of the rotor stage, said machining performed so as to produce a turbine having a power output sufficient to drive the generator to produce a maximum electric power output at a target value in the range 50 KW to 5 MW.   
     
     
         16 . A method according to  claim 15 , wherein said providing a universal turbine hood step includes providing a turbine hood that includes a backplate, and further including the step of selecting the backplate to have a configuration that permits attainment of said power output sufficient to drive the generator to produce said maximum electric power output at the target value. 
     
     
         17 . A method according to  claim 15 , wherein said providing a universal turbine hood step includes providing a nose piece proximate said floor of said turbine hood, said nose piece having a configuration selected to permit attainment of said power output sufficient to drive the generator to produce said maximum electric power output at the target value. 
     
     
         18 . A method according to  claim 15 , wherein the universal turbine hood includes a backplate opposite the floor and a diffuser exit passage between the backplate and the floor, the diffuser exit passage having a width l1, the universal turbine hood further including a hood wall that is axially spaced a distance l4 from the backplate, further including the step of forming the backplate so the distance l4 ranges from one half to four times the width l1. 
     
     
         19 . A method according to  claim 16 , wherein the backplate used in said providing step is separate from, and releasably attachable to, the turbine hood. 
     
     
         20 . A system according to  claim 19 , wherein said backplate covers an opening in said turbine hood, and said machining material away from said hood is performed using a machining tool sized to fit through said opening so as to remove material from said floor of said hood.