ZS Screw blower
Sittisak.T
ZS Low Pressure Screw blower
Agenda
 Applications
 Products range
 Scope of supply
 Why is the screw so much more efficient?
 ISO1217
2
Low pressure applications
3
Low pressure applications
4
Low Pressure Product Portfolio
(bar(g))
4
ZE/A 2 -6
1.5
ZB+
ZS+
1.0
HSI – MC series
ZS
HSI –HT series
0.5
0
0
2.000
4.000
6.000
8.000
16.000
(m3/hr)
5
5
70.000
Low Pressure screw blower
Scope of supply

Basic
–
–
–
–
–
–
–
–
–
–
Base frame with forklift slots
100% oil free element (Class 0)
Integrated gear-box (no belts)
TEFC IP55 motor
Air-outlet (silencer, BOV)
Oil-circuit (pump and cooler)
Air-inlet (filter)
Discharge pressure gauge
Oil pressure switch
Decoupling between air filter and
element
– Decoupling between element and
pulsation damper
– Comes with fixed speed (Y/Δ) motor
as standard.
 VSD type motor as an option
6
ZS55 basic
ZS Low Pressure screw blower
Scope of supply

Standard
–
Base frame with forklift slots
–
100% oil free element (Class 0)
–
Integrated gear-box (no belts)
–
TEFC IP55
–
Air-outlet (silencer, BOV)
–
Oil-circuit (pump and cooler)
–
Air-inlet (filter)
–
–
Discharge pressure gauge
Oil pressure switch
–
–
Decoupling between air filter and element
Decoupling between element and pulsation
damper
Canopy
–


–
Comes with fixed speed (Y/Δ) motor as
standard.

–
7
78 dB(A) at 1 bar and full speed.
74 dB(A) at 0.6 bar and full speed
VSD type motor as an option
No starter and no Elektronikon
ZS55 standard
ZS Low Pressure Screw blower

Scope of supply
ZS+ VSD
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–
–
–
–
–
–
–
–
–
–
–
8
Base frame with forklift slots
100% oil free element (Class 0)
Integrated gear-box (no belts)
TEFC IP55 Eff 1 motor
Air-outlet (silencer, BOV with pressure
control)
Oil-circuit (pump and cooler)
Air-inlet (filter)
Decoupling between air filter and element
Decoupling between element and pulsation
damper
Elektronikon controller for improved
performance – larger turndown
Improved sound enclosure (72 dB(A))
Integrated VSD converter
ZS37+ VSD
ZS Low Pressure Screw blower
Scope of supply

Air filter
–
Dry paper filter
–
Same as used on ZR/T range
–
Efficiency SAE fine particle size




Air filter differential gauge
–
–

9
0,001 mm 98 %
0,002 mm 99.5 %
0,003 mm 99.9 %
Provides visual view of air filter pressure
differential.
Change air filter when differential reaches
50 mbar
Air discharge pressure gauge
–
50 mm diameter
–
–
Bar and psi display
Dry type
ZS Low Pressure Screw blower
Scope of supply

Flexible hose
– To provide a vibration decoupling between
the element and the filter housing.
– On tri-lobe blowers serious cracking on the
filter housing can occur due to having no
de-coupling
– On ZS it is not a concern but we can use
this feature as a positive design feature
over tri-lobes
10
ZS Low Pressure Screw blower
Scope of supply – compression element

ZS element
– 100% oil free element (Class 0)
– Coated with the same coating as the Z stages
 Coating consists of a teflon & a teflon grahite
layer
– Timing gears like the Z’s but on drive end
– Non-drive end is greased for life bearings
11
ZS Low Pressure Screw blower
Scope of supply – compression element
12

Timing gears on the non-drive end

Lubricated bearings on both drive end and
non-drive end
ZS Low Pressure Screw blower
Scope of supply

Flexible hose
– To provide a vibration decoupling between the
element and silencer
– On tri-lobe units serious failures of the silencers can
occur.
– It is not an issue on the ZS due to the screw element
delivering higher frequency, low pulsation air but let’s
use it to attack lobes.
13
ZS Low Pressure Screw blower
Scope of supply

Gearbox
– Transfers motor power to element more efficiently
than belt / pulley
– Belt / pulley = approx. 93% efficient
– Gearbox = approx. 98% efficient
– No risk of misalignment
– Belts needs to be replaced every year
14
ZS Low Pressure Screw blower
Scope of supply

Start up valve
–
Closes when the pressure builds between 0.1 bar and 0.2 bar (1.5 psi and
3psi)
–
The valve is in the open position when the blower is off.
–
When the blower is started against a counter pressure, the air is blown off
through the main opening of the valve (1).
By increasing the air flow, a slight overpressure is generated in the pipe (2)
and the bellows (3) are filled with air.
When the pressure on the surface of the base plate (5) in the bellows has
become bigger than the pressure on the main opening of the valve (1), the
base plate closes the valve.
–
–
–
The unit is in load status.
2
3
1
5
15
ZS Low Pressure Screw blower
Scope of supply

Start up valve
–
When the unit will be stopped, the air in the bellows will escape through the
pipe. The pressure on the base plate diminishes and the springs (4) will open
the valve.
4
16
ZS Low Pressure Screw blower
Scope of supply

Bursting disc
–
–
–
–
17
The bursting disc is the safety device to
ensure that any over pressure is released
quickly.
It is designed to protect the blower from
over pressure.
The bursting disc is used for PED accuracy
and cost.
Once the disc breaks it has to be replaced
with a new one.
ZS Low Pressure Screw blower
Scope of supply


Check valve
–
Swing type
–
Prevents air from network entering the
element.
–
Low pressure drop design
Silencer
–
–
18
Reduce noise and pulsations generated
by element
Damping material is stainless steel wool
ZS Low Pressure Screw blower
Scope of supply – oil circuit




Oil pump
–
Pumps oil from the tank (15 litre) to the bearings and gears
–
50 Hz: 370 watt; 400V; 3phase
–
60 Hz: 430 watt; 440-460V; 3 phase
Oil filter
–
Filters any particles from the oil
–
Genuine Atlas Copco oil filter
Oil cooler and cooling fan
–
To cool the oil prior to lubrication of gears
–
This is a big selling feature. Cooled oil has a much longer lifetime
–
50Hz: 95 watt; 230V; 1 phase 1690 m3/hr cooling air flow
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60Hz: 94 watt; 115V; 1 phase 1420 m3/hr cooling air flow
Oil type
–
19
Roto Z
ZS Low Pressure Screw blower
Why is the screw so much more efficient?
p
Screw
1bar
Roots
atm
 Working principle and pV-diagram
 Adiabatic efficiency
 Air temperature at outlet
 Pressure pulsations
 Conclusions
20
200m³/h
5000m³/h
flow
Roots blower working principle
Air transport
Air intake at inlet side
Air transport
21
External compression
by back flow
Force out air to
discharge line
Roots blower : pressure-volume diagram
p
3
2
pe
p1 = air intake pressure
pe = working pressure (external system pressure)
Vs = displaced volume
Wt
p1
4
1
Vs
V
4-1 : Air intake; volume increase to Vs
1-2 : Compression by back-flow from receiver to blower
2-3 : Air delivery from blower to receiver
Rectangle area 1-2-3-4 represents the compression work Wt
Power consumption is proportional with blue area 1-2-3-4
22
Working principle
Inlet port
Male rotor
Female rotor
23
Example: B111
Working principle
Volume of inlet chamber increases when rotating the rotors: air is
sucked in
24
Working principle
Volume of inlet chamber increases when rotating the rotors: air is
sucked in
25
Working principle
Volume of inlet chamber increases when rotating the rotors: air is
sucked in
26
Working principle
Inlet port closes: Air is trapped between between rotors and
housing
27
Working principle
Inlet port closes: Air is trapped between between rotors and
housing
28
Working principle
Outlet port:
much larger than
OIS or OFS
When rotors rotate the volume between the rotors decreases :
compression of the air
29
Working principle
When rotors rotate the volume between the rotors decreases
down to the built-in volume ratio : compression of the air
30
Working principle
The outlet ports opens when the volume is reduced: compressed
air is released from between the rotors to the outlet port
31
Working principle
32
Working principle
33
Working principle
34
Screw blower

Working principle : displacement compressor with internal compression

Pressure-Volume diagram
p
3
2
pi=pe
1-2 : internal compression in screwblower
Wt
p1
2-3 : Air delivery from screwblower to receiver
4
1
Vs/vi
35
Vs
V
Screw blower

Working principle : displacement compressor with internal compression

Pressure-Volume diagram
p
3
2
Energy saving due to internal compression
Wt
Power consumption is proportional with blue area
1
V
36
37
38
39
40
41
42
ZS Low Pressure Screw blower
Summary
Roots type blowers
Screw blowers
− Max 0.8 to 1.0 bar(e)
+ 1.25 bar(e) or more
− Poor efficiency, No package
performance warrantee
+ High efficiency (~30% less SER), Package
warrantee
− High outlet temp
+ Lower outlet temp
− High noise level: 75 -90 dB(A)
+ Noise level: 70 -73 dB(A)
− Pressure pulsations
+ Higher frequency pulsations
+ Internal VSD,Large turndown: 200m3/hr to
− External VSD ,Narrow turndown:
1100m3/hr on ZS37+ VSD, VSD’s motor,no
3
3
800m /hr to 1100m /hr, Speed
speed window.
window and high temp
+ Integrated concept: small footprint
− Limited reliability and lifetime
− Installation cost , check valve ,
safety valve , Flexible hose
43
+ Oil cooler: High reliability and lifetime
+ Complete package ,No hidden cost
ISO 1217
44
Committed to
sustainable productivity.
45