Abstract: A rotary regenerative heat exchanger includes a rotor having primary vanes 14 extending between the hub and the periphery of the rotor, and additional secondary vanes 15 between said primary vanes and extending over an outer annulus of the rotor. Such an arrangement facilitates having several of the primary and secondary vanes sealed with respect to a sector plate over the outer annulus as compared with the number of primary vanes sealing with the same sector plate over the inner annulus.

Abstract: A fan is modified by replacing its rigid rotor shaft by a flexible shaft so the normal operating speed range is above the first transverse critical speed. During run-up, the assembly of the fan impeller 12 and the drive shaft 11 is accelerated rapidly through the first critical speed at which the peak transverse vibrations could be encountered, and during run-down the shaft 11 is braked to minimize the same exposure to transverse vibrations. The use of a more flexible fan drive shaft of smaller diameter, allows a higher fan operating speed to be used without risk of detrimental shaft aerodynamic chokage effects, and the utilization of the existing fan foundation.

Abstract: A connector sleeve 17 secured to the backing plate 7a of a wear-resistant liner 7 facilitates attachment of the liner 7 to the body9 of a rotor blade by virtue of welding of a thrust collar 20 to a portion of the connector sleeve 17 projecting past a bore 18 in the blade body 9. Removal of the liner later for replacement is possible by burning off the welds connecting the thrust collar to the connector sleeve. A clamping tool 22 comprising a tubular body 23 and a bolt 24 can be used to hold the thrust collar firmly against the back of the blade body 9 during the welding operation.