Everllence

Type RC

Dewatering under vacuum Specially suited as a one blower for all vacuum levels.

Benefits at a glance

• Widest operating range
• Environmentally friendly
• Low space requirement
• No seal water consumption

Characteristics
RC type blowers can generate up to four different vacuum levels with up to 75 kPa. The blower characteristic is flat and allows suction volumes to vary widely without noticeable changes in vacuum levels. Thanks to its good part load behavior, power consumption of the blower is proportional to the suction volume.

Operation
The RC multi-stage blower can be driven by electric motor or steam turbine drive. The air/white-water mix aspirated from the paper machine at various vacuum levels is collected in separators where water, particles and fiber solids are removed. Air from the highest vacuum level is compressed in the first stage of the blower and ducted via diverter channels to the second stage where it is mixed with air from the medium vacuum level. This process is repeated in the third and fourth stages. The design is such that four different vacuum levels can be generated in one unit. The compressed air exits the blower at a temperature of approximately 160 °C. This thermal energy can be recuperated for processes such as water heating, heating air for the paper machine pocket ventilation system, space heating, etc. Noise emissions can be attenuated to any desired levels.

Design
The horizontally-split casing has four integrated suction and one discharge branch, all downfacing in the lower casing half. The blower can thus be opened without disassembly of the piping. The rotor is supported by two white metal pedestal bearings bolted onto the lower casing half. One of the bearings is a combined axial for absorbing residual axial thrust not compensated by the balance piston. The impellers are shrunk onto the shaft; the complete rotor is then over-speed and dynamically balanced.

Control system
Two fully automatic control loops ensure operational safety and reliability. Overload protection Throttle valves in the suction duct close, simulating the flow resistance of the missing paper sheet, thus preventing air inrush and drive motor overload.

Antisurge protection
When operated below minimum flow level, the blower will surge. To avoid this, an automatic valve bleeds air into the first suction branch until stable operation is restored.

Lubricating oil system
The blower bearings, the gear and, if required, the motor bearings are oil-lubricated. An electrically driven auxiliary oil pump provides lubrication during start-up and shut-down. During operation the main mechanical lube oil pump (flange mounted to the gear unit) takes over the oil supply. This combination, provides maximum operational security, whereby the electric unit acts as stand-by during normal operation.