Compression & Solutions
STC-DO Siemens
Turbocompressor
Direct drive, direct drive for municipal
and industrial applications
www.siemens.com/energy/aeration
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Highest efficiency at
High Speed
The Siemens STC-DO unit is the highest efficiency direct
driven centrifugal compressor available today that utilizes
a high-speed motor with the impeller mounted directly on
the motor shaft.
Highlights
Dual PointTM control
Our highly experienced aerodynamicists combined our
unique Dual PointTM control technology with an optimized air path and impeller design using the latest
design software. This allows the highest efficiency
throughout the widest turndown range in the industry.
Siemens single stage direct drive unit (STC-DO) is a stateof-the-art design, specifically tailored to the unique environmental and process needs of the aeration market.
Turndown range down to 35%
Fields of application
Wastewater treatment of:
» Municipal sewage
» Industrial sewage
Low noise level with no pressure pulsation
High-quality components are integrated into a standardized, easily accessible enclosure for reduced
footprint
The only real plug and play machine with fully
enclosed components, easy to install and operate
100% oil free
Low maintenance cost
Electrical filters as standard
Fermentation
» Yeast production
» Enzyme production
» Similar biological processes
Flow and pressure range
1,000 to 13,000 m³/h
Differential pressure up to 1.1 bar
Single stage direct drive centrifugal core compressor with Synchronous permanent magnet motor and airfoil bearings (STC-DO)
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Single point speed control design
Head (%)
120
100
80
Speed 1
Speed 2
Turndown
Speed x
40
60
100
Performance curve
Design point
More efficient
Surge lines
Operational line
Less efficient
Capacity (%)
With Single point speed control, the design point has to be chosen at a considerably higher pressure level which would not be required under normal operating conditions. The design is a trade
off between turndown capability and efficiency.
Dual PointTM speed control
Head (%)
120
100
80
Diffusor
Position 1
Diffusor
Position x
Diffusor
Position 2
Turndown
40
60
100
Performance curve
Design point
More efficient
Surge lines
Operational line
Less efficient
Capacity (%)
With a Dual PointTM speed control the design point can be aligned with required operational conditions,
allowing the blower to work in its highest isentropic efficiency area with the widest regulation range
(up to 35%).
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Efficiency by control
Dual PointTM control
The unique Dual PointTM control process allows to independently regulate the flow and head of the compressor,
giving superior efficiency at design and especially off
design conditions. The control management system operates automa­tically and simultaneously the position of the
variable diffuser vanes as well as the Variable Frequency
Drive (VFD).
The compressor flow function is managed through the
­diffuser vanes, or discharge control vanes, which increase
or decrease the airflow path exiting the impeller wheel,
allowing a step-less turndown range from 100 % to 40 %
or less with almost no efficiency loss. The compressor
head function is controlled by changing the impeller rotational speed through the Variable Frequency Drive (VFD).
The control methodology maintains the isentropic efficiency at its maximum relative value across a wider range
of flow, water depth, and temperature conditions.
Variable Diffuser System
The variable diffuser system controls the flow by adjusting
the angle of the diffuser vanes, which are positioned radially around the impeller.
The vanes are flow-optimized non-symmetrical airfoils,
allowing adjustment of the nozzle area, while still maintaining an excellent efficiency throughout the entire operational range of the compressor.
Variable Frequency Driver (VFD)
The VFD is designed to deliver the required power with
the minimum vibration and electrical noise. The VFD controls impeller speed to obtain highest efficiency even
when the compressor is working under off-design conditions (low temperature and/or pressure).
The VFD System
Siemens offers true plug and play including all required
electrical filters as standard.
The VFD package includes:
VFD drive
Input choke, reduces the input effective current
EMC filter, reduces the interference caused by
­variable speed drives
Sinus filter, reduces the effect of eddy-current
losses in PM rotors
This system enables a longer lifetime, higher efficiency
and reliability.
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Efficiency by design
An Integrated Solution
Impeller
The core of the compressor is the impel-ler, which is
machined from a solid forged piece of high-grade aluminum alloy and is statically and dynamically balanced.
Integrated Package
All components are integrated into a standardized, easily accessible enclosure, resulting in a reduced footprint
solution and true plug and play. The enclosure includes
the inlet filter, inlet silencer, compressor/motor unit,
­variable frequency drive (VFD), discharge cone/silencer,
blow-off valve, cooling system, instrumentation and
local control panel (LCP).
Siemens provides different impeller sizes for the STC-DO
model for customization to client requirements in terms
of flow and ambiant conditions.
Permanent Magnet Synchronous Motor (PMSM)
The electrical motor is a synchronous (permanent magnet) type, with permanent magnet and carbonfiber
sleeves mounted on the steel shaft. The motor is specially designed for high speed operation (speed range
from 13,000 rpm to 41,000 rpm). All components are
rated for continuous duty at the specified conditions.
Advantages of the PMSM
Can operate at high speed and frequency, maintaining high efficiency
Low heat generation
Higher overall efficiency compared to an induction
motor.
Compliant Airfoil Bearings
The application of airfoil bearings results in improved
efficiency, thanks to reduced friction, and exceptionally
long life with minimal maintenance since no lubricating oil is required.
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Easy to install
The enclosure can be fork-lifted and set in place. No
anchoring, or preparation required, simply connect
power and discharge piping, then push the start
button.
Easy to operate
A state-of-the-art, easy intuitive operation control
panel lifts the interfacing to the next level.
Quiet
The sound attenuation is based on years of engineering
knowledge and extensive testing, resulting in a state of
the art acoustic package.
Clean Running
The air is sucked through the air filter to the compressor inlet of which a small part is directed to the enclosure for cooling purpose, whereby the process air and
internals of the enclosure are kept clean and dust free.
Low Maintenance
Airfoil bearing technology eliminates the need for an
oil lubrication system. The air filters are likewise easy to
change. A liquid cooling system for the main crucial
components (motor, VFD) extending their lifespan and
reduce risk of failures.
Complete envelope
Design conditions: 1,013 bar, 80% RH, 20 degree Celsius
1.2
20 30 40 50 60 70
KW KW KW KW KW KW
90
KW
110
KW
130
KW
160
KW
200
KW
max 110
1.1
max 220
STC-DO (5SF-A)
STC-DO (2SF-A)
1.0
STC-DO (1SF-A)
Delta pressure [bar]
0.9
0.8
5-1
5-2
5-3
5-4
5-5
0.7
2-1
2-2
2-3
2-4
0.6
1-1 1-2 1-5
0.5
0.4
0.3
0.2
500
2000
3500
5000
6500
8000
9500
11000
Flow [m /hr]
Flow is defined based on above maximum design conditions
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Range of application:
STC-DO (1SF-A)
(up to 75 kW motor power)
STC-DO (2SF-A)
(up to 110 kW motor power)
STC-DO (5SF-A)
(up to 200 kW motor power)
Siemens’ comprehensive portfolio provides a full range of applications for Wastewater Treatment
and Fermentation with 3 models and 12 customized impeller types of the compressor STC-DO
­corresponding to customer needs in term of air demand.
Testing
Decades of long experience testing thousands of centrifugal compressors have resulted in extensive know-how.
Combined with an advanced test rig this ensures the highest quality control for our Turbomachinery equipment.
Before leaving the factory each compressor is mechanically and functionally tested in our advanced test rig in
accordance with our Standard Shop Test Specification. The
testrigs are certified every year according to ISO 9001 and
the calibration procedures are conducted at regular intervals in accordance with ASME, ISO and API international
standards. All testing is performed in order to measure
operating data for evaluation of conformity with specified
data. The following will be fulfilled during the rigorous
testing:
Provide sufficient test data over the specified operational range for the quality approval procedure and
­certification before delivery
Provide vibration testing data, which is measured
with an accelerometer, with sampling band width of
10–1,000 Hz and 1,000–10,000 Hz in accordance
with ISO 10816
Ensure accurate, safe, and fast registration of all relevant test data in the shortest possible testing time
and at the lowest possible cost
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Published by and copyright © 2012:
Siemens AG
Energy Sector
Freyeslebenstrasse 1
91058 Erlangen, Germany
Siemens AG
Energy Sector
Oil & Gas Division
Wolfgang-Reuter-Platz
47053 Duisburg, Germany
Siemens Energy Inc.
10730 Telge Road
Houston, Texas 77095, USA
Siemens A/S Turbomachinery Solutions
Allegade 4
3000 Helsingoer, Denmark
For more information, please contact
Phone: +45 49 21 14 00
Fax:
+45 49 21 52 25
E-mail: aeration.energy@siemens.com
Oil & Gas Division
Order No. E50001-G420-A121-V1-4A00
Printed in Germany
Dispo 34806, c4bs 7489 P WS 0312
Printed on elementary chlorine-free
bleached paper.
All rights reserved.
Trademarks mentioned in this document are the property of Siemens
AG, its affiliates, or their respective
owners.
Subject to change without prior
notice. The information in this document contains general descriptions
of the technical options available,
which may not apply in all cases.
The required technical options
should therefore be specified in
the contract.