b'both the amount and usage of throttling valves can be reduced to a minimum, resulting in energy savings of 30 to 70% when compared with traditional vacuum systems. Figure 2. Operating window comparison. TURBO BLOWER OPERATIONof 30 to 70% when compared withcentrifugal blower. First, air is forced Ecopump turbo blowers are designedtraditional vacuum systems.through the impeller in a radial to operate efficiently across a widedirection due to the centrifugal force. range of vacuum levels and air flows.Single and two-stage turbo blowers areAs the radius of the impeller increases They allow paper mills to optimizeof the generic centrifugal compressorthe magnitude of the centrifugal force vacuum levels whilst taking advantagetype. Air enters a centrifugal fanincreases thus creating a pressure of the higher efficiency a blower hasimpeller axially then passes through thegradient i.e. an increase in the static over a traditional liquid ring pumpimpeller radially. Air is collected in thepressure. Secondly, as the outlet area device. High speed motors, driven byvolute casing and discharged at a rightof the blade passage is larger than frequency converters, allow a typicalangle to the inlet flow. As the impellerthe inlet area the blade passage acts RunEco blower to provide paperrotates, the air contained within theas a diffuser. The relative velocity machine vacuum levels between 30blade passage is forced outwardsdecreases as the air flows through the and 70 kPa. A wider range of impellerby centrifugal force. This processblade passage leading to an additional designs allows highly efficient levelsproduces a continuous flow through theincrease in the static pressure at the across the operating range. This meansimpeller. impeller outlet. Finally, the motion of that both the amount and usage ofthe blades adds rotational momentum throttling valves can be reduced to aSpecifically, there are three stages toto the flow increasing the tangential minimum, resulting in energy savingsthe pressure development through avelocity of the air flow. The increase ofTISSUE TECHNOLOGY INTERNATIONAL29'