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Active magnetic bearings

Active magnetic bearings is a device supporting the rotor of compressor without mechanical contact using magnetic attraction and active control system with sensors, electric magnets, power amplifier, power supply unit, and controllers.

A set of a magnetic bearing manufactured by Kazancompressormash consists of two parts:

  • Mechanical elements of journal (radial) bearing, trust (axial)
    bearing, and auxiliary bearing
  • Automatic control system in a cabinet

Stator (non-rotating) parts are supplied as a complete set ready for installation into compressor casing.

Up-to-date magnetic bearing technology provides load capacity of up to 105 N in any conditions:

  • Low and high temperatures (from -250 °C to +450 °C)
  • Vacuum or aggressive corrosive environment (air, helium, hydrocarbon, vapor, uranium hexafluoride, sea water, liquid oxygen and hydrogen)
  • High rotation speed of centrifugal compressors up to 12000 rpm
  • High pressure up to 25…50 bar

DESIGN FEATURES AND ADVANTAGES

Active magnetic bearings provide increased technical and operation efficiency of compressors in comparison with traditional mechanical support systems based on sleeve or ball bearings:

  • Complete elimination of mechanical friction of components thereby significantly reducing energy losses of equipment.
  • Complete absence of the lube oil system (oil pumps, filters, injection units, oil coolers), as well as associated initial and operation expenses.
  • Increased reliability and operational lifetime (over 1000 000 hours) of bearings and significantly (by a decade) decrease maintenance cost during equipment operation.
  • Increased operation and environmental safety of equipment due to absence of the lube oil vapor in the compressor installation premises.
  • Elimination of the process gas contamination by liquid or grease lubricants.
  • Complete solution of the rotor’s dynamic problem related to control of admissible vibration in supports in transient and steady operation modes.
  • Exclusion of necessity to center the bearing units in compressors with more than two bearings for a single rotor.
  • Minimal influence of compressors parts thermal expansion.
  • In-process control of magnetic bearings (vibration, temperature, currents in electromagnets, axial forces and others) using devices built in the bearings, without additional measuring equipment.

Kazancompressormash manufactures and supplies the compressors with magnetic bearings for 4, 6.3, 8, 12 and 16 MW gas compression systems with the following parameters:

NC-4
NC-6,3
NC-8
NC-12
NC-16
5GC2-
300/4,5-64
4GC2-
124/14-79

Drive power, MW

4
6,3
8
12
16
12
8

Capacity at standard conditions,
million Nm3/day

6,5
10,2
13
18
32,4
2,0
2,3

Discharge pressure, MPa (bar)

5,48 (56)
7,45 (76)
7,45 (76)
5,48 (56)
7,45 (76)
6,27 (64)
7,74 (79)

Compression ratio

1,26;
1,44
1,44
1,44
1,44
1,44
14,2
5,64

Rated rotation speed, rpm

8200
8200
8200
6500
5300
8900
8200

Polytropic efficiency

0,85
0,85
0,85
0,85
0,85
0,75
0,75

Weight, kg

10000
12000
14000
15000
17000
16000
14250

Dimensions, mm
length
width
height

 

2100
1400
1400
 

1560
1800
1500
 

1560
1800
1500
 

2000
1800
1600
 

2200
2000
1700
 

2700
2000
2300
 

2840
1400
1440

Total service life, hours

100 000
100 000
100 000
100 000
100 000
100 000
100 000

Specialists of NIIturbokompressor provide a full range of services on engineering, manufacturing supervision, installation, commissioning, and maintenance of the active magnetic bearings for centrifugal compressors including:

  • Engineering of design and composition of the active magnetic bearing according to specific customer requirements
  • Calculations of radial and axial electromagnets, optimized by design and electric characteristics
  • Engineering of the rotor systems design, optimized by vibration properties in operation and transient modes of rotating machines
  • Engineering of the automatic control boards for active magnetic bearings
  • Investigation of the optimal settings for existing and newly designed active magnetic bearings systems
  • Engineering and manufacturing supervision of the active magnetic bearings components including electromechanical parts and control electronics
  • Maintenance of the active magnetic bearings at the sites of operation
  • Consultations on theoretical and practical aspects of the active magnetic bearings engineering