Lubrication of screw machines
AssigneeCity University
InventorsIan Kenneth Smith, Nikola Rudi Stosic
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Abstract
A screw machine for use with a working fluid with a liquid phase present comprises rotors having meshed, lubricated helical formations. The rotors have an ‘N’ profile as disclosed in WO 97/43550. In use, lubrication of the helical formations of the rotors and optionally of the rotor bearings is achieved substantially exclusively with the liquid phase of the working fluid.
Claims18
A screw expander for use with wet steam as a working fluid, the expander comprising two or more rotors having meshed, lubricated helical formations, wherein the rotors have an ‘N’ profile as defined herein and, in use, water entrained in the wet steam working fluid is substantially exclusively responsible for lubricating the helical formations of the rotors.
The expander of any preceding claim, wherein the rotors are supported by at least one bearing that is also substantially exclusively lubricated, in use, by water.
The expander of any preceding claim, wherein the rotors are synchronised by synchronising torque transmitted from one rotor to another via their meshed helical formations.
The expander of any preceding claim, further comprising a thrust piston acting against axial loads on a rotor.
The expander of any preceding claim, wherein the lubricating water entrained in the wet steam working fluid is derived from the wet steam entering the expander, substantially without prior addition of further water to the wet steam.
A method of lubricating a screw expander when using wet steam as a working fluid, the expander comprising two or more rotors having meshed, lubricated helical formations, the rotors having an ‘N’ profile as defined herein, wherein the method comprises lubricating the helical formations of the rotors substantially exclusively with water entrained in the wet steam working fluid.
Dependencies are inferred from the claim text.