Multistage centrifugal biogas blowers CM series

Multistage centrifugal blowers for biogas and natural gas

Construction in aluminium alloy or cast iron body
For multistage model, impeller in spark proof
Aluminium alloy, high speed v-belt drive, easy
installation, low noise level, no vibration,
pulsation free discharge, minimal maintenance.

Flowrate up to 3,600m3/h
Pressure up to 950mbar(g)
Vacuum up to 450mbar(g)

Principle of operation

One stage of a MAPRO® multistage centrifugal blower is generally made of:

An intake duct conveying the gas to the impeller inlet, which is coaxial to the shaft
A closed impeller with axial flow inlet and radial flow exit;
A radial diffuser, whose aim is to convert kinetic energy into static pressure at the impeller exit
A discharge volute

Actually, a centrifugal blower is always used in the multistage configuration. The gas is sucked into the first stage through an inlet volute, every next single stage is linked to the former one through a return channel, and a discharge volute collects the gas from the exit of the last stage delivering it to the outlet pipe.

The impellers are built with radial exit blades or backward facing blades. The radial blades allow the achievement of a higher compression ratio, whilst the impellers with backward facing blades, at fixed speed of rotation and for the same differential pressure, produce a characteristic curve with a much wider stable range.

cm principle

Generalities and construction features in conformity with the 2014/34/EU Directive (ATEX)

The MAPRO® multistage centrifugal blowers, CM Series, to be used for extraction or compression of combustible gases, such as biological or natural gas, have been designed in order to fall within the Equipment- Group II as required by the 2014/34/EU Directive, Category 2 both for the surrounding area conditions and for the internals of the machines.

Main construction features:

Heads, intermediate sections, bearing housings and caps made of cast iron; shaft in carbon steel; impellers made completely of spark proof aluminium alloy
Heads and intermediate sections sealed
Shaft sealing by special double-lip seals which do not require lubrication

The blowers are always coupled to the electric motor via belt drives and the safety drive guards are made from spark-free material.

The combination of different impeller types, the possibility to match several stages in series, and the wide speed of rotation range allow to cover, with only one machine frame, a very large range of duty.

Electric motors are flameproof, type of protection “d”, with specific marking Ex II 2 G, additional marking Ex-d IIB T3. If the area surrounding the equipment is classified as Zone 2, where, for the Group II, Category 3 equipments are accepted, the driving electric motors could be non-sparking, type of protection “n”, with specific marking Ex II 3 G, additional marking Ex-nA II T3.

In some particular cases, the multistage centrifugal blowers can be fitted with lip seals in pairs, with a barrier fluid in between. Besides, all the static parts wetted by the gas can be treated with a protective coating using a nickel-plating chemical technique and the impellers can be treated with anodic oxidation.

Advantages

The main advantages of using MAPRO® multistage centrifugal
blowers are:

Easy installation
Low noise level
No vibration
Pulsation free gas flow
No gas contamination
Minimal maintenance

The most common fields of application

Landfill biogas recovery to feed torch or burner;
Tank, plant or contaminated soil gas recovery to feed torch or burner.

The typical “flow rate – pressure” curve is much more flat than the performance curve of a side channel blower and this peculiarity makes the MAPRO® multistage centrifugal blowers the ideal machines for the above listed applications in which the gas flow rate to be extracted could vary, even considerably, in time. In short, the operating point moves by simply following the internal characteristic curve of the blower.

Complete range of accessories: