Mechanical Technology

Mechanical Technology — July 2015

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Hydraulic and pneumatic systems

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“

erzen Airgas offers highly-

efficient equipment that

can assist operations in

considerably reducing

energy bills,” begins Stubel, admitting,

however, that the initial purchasing cost

is a dominant factor in the decision mak-

ing process.

“This makes the introduction of more

expensive but efficient equipment chal-

lenging. Understandably, buying equip-

ment at the lowest price makes financial

sense, but the misconception lies in the

fact that cost saving decisions are based

primarily on short-term financial goals,”

he says.

Stubel points out that purchasing

Rising electricity costs and unreliable supply from the national grid are prompting

industrial operations to seek more energy-efficient

equipment. However, the major challenge in South

Africa still lies in the market’s reluctance to focus

on long-term investment, by spending more on the

initial purchase price to ensure future savings, according

to Aerzen Airgas marketing co-ordinator Andreas Stubel (left).

The Delta Hybrid is

designed to be an optimised com-

bination between a blower and screw

compressor, and makes use of a patented

twisted rotor profile.

In conjunction with new machine sales, Aerzen Airgas offers numerous after sales services including field

service, repairs and overhauls to the entire range of Aerzen blowers and compressors.

Compressor investments, long-term

standard or cheaper equipment does not

save money, and may in fact cost more

in energy consumption and maintenance

in the long run. “Bearing this in mind,

Aerzen Airgas offers the local market the

Aerzen Delta Hybrid rotary lobe compres-

sor, an oil-free air conveying alternative

to standard roots blowers,” he continues.

The Delta Hybrid is designed to be

an optimised combination between a

blower and screw compressor, and makes

use of a patented twisted rotor profile. It

is designed for a variety of applications

where air and neutral gases must be

conveyed oil-free. These include; waste-

water treatment plants, the chemical

industry, power plant technology and for

the pneumatic transport of powder and

granulate goods.

The Delta Hybrid is available in four

models: L, S, H and E. The L model has

been designed for pressure ranges of up to

800 mBar; the S model for 1 000 mBar

and the H model for pressures of up to

1 500 mBar at sea level. The E model

is a vacuum machine with a maximum

negative pressure of -700 mBar. The

Delta Hybrid is effectively an in-between

solution, as it crosses the pressure range

between roots blowers and low-pressure

screw compressors.

“The Delta Hybrid is a compres-

sor designed from the bottom up with

energy-efficiency in mind. As a result, it

is up to 15% more energy-efficient when

compared to standard positive displace-

ment blowers. It has an optimised fluidic

design of inlet and discharge ports to

provide for ideal flow conditions and

reduced slippage,” Stubel explains.

The inlet air is sucked in on the cold

side of the unit and a specially designed

discharge silencer increases the compres-

sion efficiency. What’s more, the belt-

driven Delta Hybrid offers the significant

advantage of exact sizing for customer

requirements.

For demonstration purposes, an

Aerzen Delta Hybrid D 24 S was tested

alongside a standard positive displace-

ment blower, both fitted with 37 kW

IE2 motors. Both machines were con-

figured to produce a system pressure of

900 mBar and an intake volume flow

of 1 000 m³/h at sea level. The Delta

Hybrid consumed 27,5 kW to produce

these figures, while the blower consumes

32,3 kW for the same performance. “On

average, therefore, the Aerzen Delta

Hybrid is 14% more efficient than the