Aerzen Positive Displacement Blowers for oil-free conveying of air and gases

Aerzen Positive Displacement Blowers (of the "Roots" type design) have been manufactured since 1868 and today are highly developed standard production machines designed and adapted to find use in a wide variety of applications.

Here some examples of applications for Aerzen Positive Displacement Blowers:

Pneumatic conveying of bulk materials

In suction- or discharge pressure. Machine sizes range from small blowers installed in tank vehicles to very large ones used in pneumatic elevators for vacuum operated ship unloaders. The hourly capacity of such unloading installations is up to 1000 tons at present.

Pressurized aeration of basins in sewage treatment plants

Filter flushing blowers in drinking water production plants

Gas boosting blowers rated for internal static pressures of up to 25 bar.

Steel production

Application in direct-reduction plants.

High vacuum boosters

are equipped with special shaft seals.

Conveying of pratical all gases

found in the chemical, petrochemical, and metallurgical industries. Special designs are available to handle aggressive gases. Machines used in both conventional and nuclear power plants comply with the various categories of safety regulations

Operating principle

Two symmetrical rotors convolute in opposite directions. The medium to be conveyed flows into the housing surrounding the rotors, and is displaced in a positive manner from the inlet to the discharge side via the chambers formed between the rotors and the housing. At the very moment the rotor tip clears the edge of the pre-inlet channel, the volume of the gas displaced is compressed by the backflow of the pressurized gas present in the conveying piping at the discharge socket. The final pressure automatically adjusts itself to the pressure level in the downstream piping and components. The flow required to convey all types of gases under various operating conditions can be calculated once specific blower data are known. Each rotor revolution results in the displacement and compression of the so-called scoop volume qo (litre/revolution).

Operating reliability and safety

Aerzen positive displacement blowers are produced by highly skilled and experienced professionals, and are not delivered prior to having been thoroughly tested. Each and every blower is subjected to a test run lasting several hours under conditions of increased load. A test record is prepared with all data which will still be available years later.

Oil-free conveying

The fact that Aerzen positive displacement blowers convey the medium oil-free is a decisive advantage in pneumatic conveying, in water filtration plants, and in the food and chemical industries. Since the rotary pistons revolve without making contact with each other and the housing, no lubrication is required in the conveying chamber, which guarantees that the medium conveyed remains free of contamination from lubricants and wear particles.

Wide range of selection

The extensive number of models and sizes available facilitates the selection of the optimal machine for any given application. Machines handling capacities ranging from approx. 30 m³/h to approx. 84000 m³ /h in either vertical or horizontal flow configuration can be supplied.

Drive types

Blowers are driven by electrical motors, internal combustion engines, hydraulic or compressed air motors via flexible coupling (arrangement 4, DA), flanged motor B 5 (for HV-blowers) V-belt drive (arrangement 5, FA) Reducer drive, shift gear transmission or variable speed drive (arrangement 6,6h).

Conveying based on the positive displacement principle

The inlet flow volume varies only slightly in response to changes in back pressure. Blower output can be adapted in the swept volume to the operating conditions simply by varying its speed.

High mechanical efficiency

Since the rotary pistons revolve without making contact, mechanical power losses are generated in the bearing and timing gear assemblies only. The use of ball and roller bearings as well as tempered and ground timing gears reduces these losses to an absolute minimum. Furthermore it is advantageous that the helical gearing offers a running of low noise.

High volumetric efficiency

The rotary pistons and casing components are manufactured using modern CNC-controlled precision machine tools, guaranteeing exact tolerances even in the large scale production of standard components. This is reflected in the minute clearances both between the rotors as well as between the rotors and the housing, resulting in very high degrees of volumetric efficiency.

Construction and design - Aerzen Positive Displacement Blowers

Are twin shaft rotary machines. The two rotors are placed axially parallel to each other and centered within the housing. Timing gears ensure that the rotors revolve without making contact. The rotors are supported on ball and roller bearings. In order to achieve a high efficiency the clearance between the rotors is kept to a minimum and is based on the pressure differential and thermal load expected under operating conditions. In case of larger blowers the roller bearing clearances and the shaft deflection have an influence on the clearance. Larger clearances between the rotors and the end plates compensate for axial thermal expansion at the floating bearing end.

Housing

The housings are made of high quality grey cast iron (GG 20). The blower housing requires no additional cooling, even at high loads. Up to the size GM 80L, the blower feet are bolted on.

Sealing configuration, series GL and GM

These models are designed to convey air or neutral gases. The conveying chamber is sealed from the oil chambers by means of an oil slinger in conjunction with piston ring labyrinth type seals featuring a generously dimensioned central vent chamber (condensate channel), and which plays a crucial role in ensuring that the medium conveyed remains clean and oil-free. The drive shaft is sealed by means of a radial seal ring installed in the housing cover.

Special designs possible at any time.

Rotors

The rotors are dynamically balanced. Smaller blowers of the sizes GM 3 S - GM 80 L feature steel rotors and shafts (C 45 N), drop-forged in one single piece. Sizes GM 90 S and larger are constructed with pistons made of GGG 40 and steel shafts (C 45 N). Where contamination particles are likely to accumulate during operation, the cavities of the cast iron rotors are capped.

Timing gears

The helical timing gears are tempered, and then ground to an exacting degree of precision. The positioning and fastening of the gears onto the shafts takes place via taper interference fit, guaranteeing both excellent concentricity and reliable adherence.

Special materials

Non-standard materials such as nodular graphite cast iron (GGG 40), cast steel (GS - C 25) and CrNi - cast steel are available for special applications. Special requirements, however, must be clarified with the manufacturer in advance!

Accessories

Our blower units normally include the standard accessories for continuous operation. The installation is effected on flat, load bearing surfaces, elevated floors or steel structures, a rigid installation on concrete foundations is also possible. In most cases the blowers are driven by a three-phase asynchronous motor and - for adjustment of the volume flow - a belt drive. Upon demand special designs as direct coupling, intermediate spur gear or special materials are also available.