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Gas Electric Partnership - Technology UpdateA Brief Overview on Coupling Selections

Engineered by NEA Group, Inc.

Referencing “Pros and Cons of Various Coupling Types for Reciprocating Compressor Installations”

by:

Gerhard Knop / Dr. Klaus Hoff

Central Division of Technology

Neuman & Esser GmbH & Co. KG

Übach-Palenberg

Germany

5th Conference of the EFRC

March 21th / 23th, 2007, Prague

NEUMAN & ESSER USA, INC.

Abstract:

Various coupling types are used for reciprocating compressor installations Rubber-In-Sheer (High-Flexible Elastomeric Couplings) Rubber-In-Compression Metal-Disc (Steel Disk Pack Coupling) Diaphragm Rigid Flange

They all have their individual advantages - otherwise they would not exist -however, experience shows that some types bear much higher risks in terms of drive train vibration problems than others.

This report compares common coupling types on the basis of many years of experience.

It evaluates different aspects but has a special focus on torsional vibration issues like height of natural frequencies, reliability of stiffness values and load capacity.

NEUMAN & ESSER USA, INC.

NEUMAN & ESSER USA, INC.

Rigid Flange

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Steel Disk Pack

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Rubber-In-Sheer Coupling

NEUMAN & ESSER USA, INC.Application benefits

Rigid Flange These couplings are traditionally used for large compressor

installations. As they are rigid in all directions, they do not compensate shaft misalignment. Therefore, most users require single bearing motors for the drive.

Steel Disk Pack Coupling All steel disc type couplings are torsionally rather rigid and

flexible in radial, axial and angular direction.

Rubber-in-sheer couplings These couplings are also referred to as ‘high-flexible’ couplings

because of their very low torsional stiffness.

NEUMAN & ESSER USA, INC.

Comparing Rigid Flange vs. Flexible Couplings Used in Electric Motor VFD Applications

The main advantages of the direct flange coupling would be:

Direct flange is stiffer than flexible which leads to higher torsional natural frequencies which are situated above the main compressor harmonics. See Tab. 1 in the attachment.

Rigid flange couplings provide much more certainty about its torsional stiffness. Therefore more safety in terms of torsional vibrations. See Fig. 8 in the attachment.

Rigid flange couplings provide much higher dynamic load capacities and are much more robust than flexible couplings. See paragraph 3.4 in the attachment.

All this applies in general. In terms of VFD, the last aspect about dynamic load capacity is a point because we always have resonances which the drivetrain must be able to handle.

Gerhard Knop

Zentralbereich Technik ZT / Central Division of TechnologyNEUMAN & ESSER GmbH & Co. KG

NEUMAN & ESSER USA, INC.

Project Examples5000 HP @ 720RPM Single Stage Pipeline Compressor

NEUMAN & ESSER USA, INC.Project Examples

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