XPR - the new performance standard

The first generation of commercial flow driven rotary pressure exchanger arrived more than 15 years ago and became the dominant energy recovery device for SWRO. While retaining the simplicity of one moving part and the durability of ceramics, the new axle based XPR technology brings performance and affordability to a level of its own. 

US - PATENT 7,306,437

AXLE BASED ROTOR POSITIONING

The size of the rotor equals the inside diameter of the pressure vessel.  The rotor has a single row of large ducts with the low flow resistance.  The numbes of ducts can be reduced as there is no optimization of duct geometry towards the cente used by an axle. The design typically yields half of the hydraulic losses at double flow compared to the sleeve based concept.  A large balance pocket under low pressure removes elastic deformations and enables a very narrow clearance resulting in less than 0.5% internal leakage.

US - PATENT 5,988,993

SLEEVE BASED ROTOR POSITIONING

The outer sleeve reduces the size of the rotor diameter to that of the inside diameter of the sleeve.  Flow crossection can only be increased towards rotor center by either extending the duct geometry or introducing a second duct row.  The turbulent flow through the rotor has high resistance due to the small duct size.  The lack of a balance pocket gives large elastic deformation of end cover and sleeve.  The axiel clearance must be larger to avoid lock-up and the internal leakage (lube flow) is substantially higher.