Low-speed drying drum pack… · This development opened the possibility to use both SPM HD and HD...

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CASE STUDY

Ultra-long pre-warning time on

Low-speed drying drum with

HD Technology

by

Sami Lehtonen

SPM Instrument Oy, Finland

August, 2017

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Contents

1 Introduction .................................................................................................................................... 32 Conclusion and summary ............................................................................................................... 33 Application description .................................................................................................................. 54 Background .................................................................................................................................... 75 System setup .................................................................................................................................. 8

5.1 Measuring equipment .......................................................................................................... 85.2 Measurement technique(s) ................................................................................................... 95.3 Condmaster setup ................................................................................................................ 9

6 Case description .......................................................................................................................... 107 Economic justification .................................................................................................................. 148 References .................................................................................................................................... 14

8.1 Customer references .......................................................................................................... 148.2 SPM Instrument references ................................................................................................ 14

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1 Introduction

Since 2012, an international chemical company with many sites in Finland has been using the SPM online system Intellinova Compact for monitoring the mechanical condition of slow-rotating drums. The monitoring system utilizes SPM HD measurements and vibration analysis with HD ENV. Condition monitoring of drum applications is quite complex because of the low rotational speed; the support wheels of the drum, for example, run at approximately 15 RPM. The possibility to use all available HD technologies with DuoTech accelerometers still makes preventive condition moni-toring possible, while at the same time saving installation and maintenance costs. Ethernet data connection between the Intellinova Compact measurement units and the Condmaster Ruby 2016 diagnostic and analysis software makes the system easy to use at different company sites and locations, enabling comparison between condition data from similar applications as well as exchange of knowledge. In addition to the online system, the use of the handheld instrument Leo-nova Diamond provides help in difficult maintenance decisions.

2 Conclusion and summary

Condition monitoring of the drums has been ongoing since 2012, implemented on a total of five drums on two different sites. The condition of the drums is monitored with 18-channel Intellinova Compact units. The shock pulse channels are equipped with shock pulse transducers (type 44000) for measurement with SPM HD, and the vibration channels with vibration transducers of type SLD144. In 2016-2017, an additional five drum condition monitoring systems were installed. These systems consist of Intellinova online monitoring units and the recently launched DuoTech accelerometers. This development opened the possibility to use both SPM HD and HD ENV technologies in the same measuring point positions. The company also uses SPM online systems on other applications, such as compressors, crushers, and Nash-pumps, etc. As mentioned, this drum application has been running successfully for many years. The ongoing project has shown the many advantages of condition monitoring systems. Over the past five years, the company has identified several machine faults which they have been able to fix during planned production stoppages. Based on condition measurement information, they have created drum-driving instructions for operators, and have also been able to improve the stiffness of drum foundations to reduce effects of natural frequencies. This case study focuses on the most recent example of extremely long pre-warning time, taken from a bearing on a support wheel in one of the drying drums.

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Image 1. The dismounted support wheel.

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3 Application description

The application in this case is a drying drum. The drums are heated inside and their purpose is to mix ingredients together to make grains, and to cool or dry existing grains. This drying drum is about five meters in diameter and over thirty meters in length. It has support wheels in each corner, and the wheel diameter is 1.7 meters. When in action, the drum weighs up to 150 tons, and the support wheel alone weighs 8.5 tons. The rotational speed of the drum is about 5 RPM and that of the support wheels 16 RPM. The drum has a double drive and a pinion gear. Its rotational speed is measured from the motor shaft. Two Intellinova Compact units are installed, as below.

Fig. 1. Measuring points on Unit 1.

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Fig 2. Measuring points on Unit 2.

Image 2. Position of the damaged bearing.

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4 Background

Plant maintenance personnel performed handheld measurements for a long time before switching to online systems on these applications, having found it very difficult to measure this kind of slow application with portable instruments.

Image 3. The drum has a double drive.

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5 System setup

5.1 Measuring equipment

Measurements on this drum are performed with two eighteen-channel Intellinova Compact units.

Location Measuring equipment

High-speed side, motor + drive end of gearbox 100 mV/g vibration transducers, SLD144

Slow-speed side, non-drive end of gearbox, pinion, support wheels

Shock pulse transducers, 44000

RPM from motor Inductive RPM probe

Image 4. One of the two Intellinova Compact INS18 units.

Image 5. Transducer installation.

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5.2 Measurement technique(s)

The measurement techniques used in this case are as follows:

Location Measurement technique(s) Purpose

High speed side Vibration, VEL RMS Unbalance, alignment, looseness

High speed side Vibration, ACC Acceleration overall, gear shocks

High speed side Vibration, Enveloping Bearing and gear monitoring

Slow speed side SPM HD Bearing and gear monitoring, low RPM

On the high speed side, the HD ENV technology is now implemented as well, using vibration trans-ducers.

5.3 Condmaster setup

The basic measuring point setup in the Condmaster Ruby 2016.3.2 software. The measurement interval is five hours, alarms from HDm and bearing symptoms BPFO + BPFI, average of five measurements. The bearing type is FAG 24164B.

Fig 3. Basic measuring point setup.

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6 Case description

In May 2014, the first indications of outer race damage showed up in the measurements. The development of the damage was monitored over the next three years before the bearing was finally replaced.

Fig. 4 Condition trend and spectrums from the support wheel bearing 24164B. Rotational speed approximately 16 RPM.

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Crisp and clear spectrums, indicating outer race damage. Note the distinctness of the time signal below the spectrums.

Fig. 5 First indication of outer race damage, May 28, 2014.

Fig. 6 Two and half years later, the outer race signals are strong and clear (December 22, 2016).

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This bearing has been in operation since 1998. The drum has four support wheels, one in each corner, and over the past nineteen years only one wheel – on the opposite end of the drum - has ever been changed due to mechanical fault. The plant has a major maintenance stoppage every year in May/June. During 2014-2016, the customer monitored the damage through online measurement, and they also checked the situation occasionally with stethoscope on site, without hearing any sound from the damage. During the three years of monitor-ing the development of the bearing damage, it was found that the drum end with the damaged bearing had never been lifted before, hence the planning to manufacture a “lifting cradle” was started. The cradle was designed by a local engineering office and manufactured according to safety standards for this kind of load. The lifting cradle is used to-gether with some support bars and two 60-80 tons jacks.

Fig. 7 Colored Spectrum Overview graph showing outer race frequencies with harmonics.

Image 6. The tailor-made lifting cradle.

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Using this lifting cradle, the support wheel bearing was replaced during normal summer stoppage in June 2017. Quite serious outer race damage was found, as can be seen below.

Image 7. The outer race damage on the support wheel bearing when dismounted - three years after the online condition monitoring system detected the first indications of a potential problem.

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7 Economic justification

This is a very good example of the benefits of accurate condition measurement data. The mainte-nance department got ample time to schedule the repair, and furthermore: if the customer had not realized the need for a lift device in good time, the bearing replacement stoppage might have tak-en several extra days. Major savings were made, both in repair costs and reduced downtime, since replacement was done during normal stoppage. This kind of result also gives the local maintenance staff more confidence in future condition monitoring-based plans.

8 References

8.1 Customer references

The company’s local condition monitoring expert comments: “Safety, reliability and productivity are important values for us. With SPM online HD measurements on these heavy drums, we have im-proved these values in our production.”

8.2 SPM Instrument references

Sami Lehtonen[Product manager]

[email protected] +358 (0)400 674949 SPM Instrument Oy Kimmeltie 3 | FI-02110 ESPOO | FINLAND T + 358 (0)9 539 133| F +358 (0)9 566 5945

www.spminstrument.fi

Low-speed drying drum pack… · This development opened the possibility to use both SPM HD and HD...

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