AERZEN turbo blowers with air bearings

Aeration tanks for wastewater treatment must be continuously provided with large air volumes, with turbo blowers offering an energy-efficient solution for this process. AERZEN’s fast-rotating turbo blowers are based around the addition of air bearings.

The construction of the turbo blowers is simple: a blade wheel, aerodynamically optimised and located directly on the motor shaft, rotates in a spiral housing, thus generating the volume flow. The technology has a high speed range from 20,000 to 70,000 rpm.

Besides special motors and a frequency converter, the shaft bearing is an important issue. Standard industrial roller bearings are not appropriate for the occurring loads. AERZEN has found an optimal solution for this problem: the two radial bearings of the drive shaft and the thrust bearing for absorbing axial forces have contact-free air bearings. The shaft rotation generates as the turbo blower is started, creating an eccentric circular motion in the air gap between shaft and bearing through natural imbalance, compressing the air in the gap. With increasing speed, the axis centres itself and is held in contact-free position by air pressure over 30 bar.

The system is completed by a two-component coating, free of maintenance, which serves as friction partner between the highly finished surfaces when the turbo machine is started; the air cushion is formed within fractions of a second. The PTFE layer provides good sliding properties, lubricant-free. A sheet of steel, when rolled into an undulating shape, supports the lubricating layer of the bearing and absorbs vibrations to protect the housing.

Turbo blowers from other manufacturers use magnetic bearings, which work similarly to air foil bearings but have many disadvantages. The solenoids, arranged circularly, require a highly complex control system and an uninterrupted power supply, meaning more maintenance is required. The complex system of magnetic bearings is also likely to be more subject to errors than the air foil bearing system. The air bearing principle does not require any electrical, mechanical or pneumatic controls. The system is of simple design, works efficiently and requires only low maintenance.