hd technology case study - spm instrument

SPM Instrument Bulgaria ЕOOD [email protected] www.spminstrument.com Str. Hadzhi Stamat Siderov № 35/А Tel.: 052-600 805, 625 080 Company № 1967/1995 9000 Varna, BULGARIA Fax: 052-600 333 © SPM 2017-11

CASE STUDY

HDTechnologyCaseStudy:Bearingmonitoring

ofChemi-WasheratSvilocellEAD,Bulgaria

by

Dobromir Dobrev and Nikolay Nikolaev

SPM Instrument Bulgaria EOOD

November, 2017

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Contents 1 Introduction .................................................................................................................................... 3

2 Conclusion and summary ............................................................................................................... 3

3 Application description .................................................................................................................. 4

4 Background .................................................................................................................................... 5

5 System setup .................................................................................................................................. 5

5.1 Measuring equipment .......................................................................................................... 5

5.2 Measuring technique ............................................................................................................ 5

5.3 Condmaster setup ................................................................................................................ 5

6 Case description ............................................................................................................................ 6

7 Appendix ...................................................................................................................................... 10

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1 Introduction

This case study describes the results from condition monitoring of a bearing on the front reversible roll in a Chemi-Washer in a pulp mill. Taken with the portable machine condition analyzer Leonova Diamond, the condition measurements in this case study clearly indicate an outer race bearing dam-age (BPFO). The pre-warning time in this case was approximately three months. The customer is Svilocell EAD Bulgaria, a producer of bleached kraft pulp and products thereof. The company is a market leader in the country and the region. They monitor approximately eight hun-dred measuring points with Leonova Diamond on a routine basis.

2 Conclusion and summary

The customer purchased Leonova Diamond in November 2015, equipped with the SPM HD and HD ENV condition monitoring technologies. For many years, they had been using the Machine Condi-tion Analyzer A30-3 Expert with the Condmaster Pro 46 software, but the disadvantage was the rel-atively short pre-warning times for deteriorating condition on low-speed applications. If measure-ments with HD technology had commenced earlier, the pre-warning time for this outer race dam-age would most likely have been considerably longer. With Leonova Diamond and SPM HD, they succeeded in catching the bearing damage for measur-ing point ZC-CPC-60110.12, located on the non-drive end (NDE) of front reversible roll on the Chemi-Washer, in time. On the second measurement, taken on February 1st, 2016, they registered a very HDm high level, and the spectrum showed a symptom match with the BPFO bearing symptom. After four months of trending the HDm levels, they decided to replace the bearing on April 20th, 2016. When they dismounted the bearing, they found severe damage to the outer race of the bear-ing. A Svilocell representative stated: "After this case, the management decided to install new 44000 sensors on all bearings which are difficult to access. Furthermore, the measurements are now taken with a more accurate speed input, leading to a smearing-free Colored Spectrum Overview that is significantly easier to analyze correctly."

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3 Application description

The purpose of the Chemi-Washer is to wash and clean the pulp from the chemicals with which it was treated. The Chemi-Washer has six rolls, each with two bearings. Two rolls are driven by hydraulic motors:

- The first drive roll, driven by one hydraulic motor

- The second drive roll, driven by one hydraulic motor

- Three intermediate rolls

- One front reversible roll

The front roll rolls the felt from the front end of the machine back to the drive rolls in the backward direction. The front roll is subjected to high tension/load. The speed is low and variable, approxi-mately 22 RPM. The roll operates in a very harsh environment, with high temperatures and aggressive chemicals. The bearing type is SKF 22228CC.

Fig. 1 Chemi-Washer - front reversible roll, non-drive end.

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4 Background

For the client is important to monitor the trend of the bearing deterioration process, and to accu-rately plan machine stoppage and bearing replacement. They have used A30-3 Expert Analyzer and have previous experience with SPM LR/HR technique and EVAM. Now using Leonova Diamond and SPM HD, the client is very satisfied with the extended prewarning time, which is very helpful when planning maintenance activities.

5 System setup

5.1 Measuring equipment

- Leonova Diamond with the SPM HD Expert module - Remote measuring points with shock pulse transducer SPM 40000

5.2 Measuring technique

Svilocell uses SPM HD to monitor the Chemi-Washer because of the method’s extraordinary suita-bility for low-speed applications, and because they need detailed analysis of shock pulses for accu-rate planning of machine stoppage.

5.3 Condmaster setup

Settings used in Condmaster Ruby 2016.3.2:

- Measuring technique SPM HD

- Measuring time: Same as FFT measurement

- Short/long time memory: Time signal and FFT / Full spectrum

- Upper frequency: 200 orders

- Lines in spectrum: 800

- Symptom Enhancement Factor: 5

- Acquisition time: 91,6 sec.

- Calculation time: 16,2 sec.

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6 Case description

The measurements took place from January 13th, 2016 to April 22th, 2016. The first measurement on January 13th shows low HDm/HDc levels, 19/0 dB, and the SPM HD spec-trum shows a BPFO match with 6 harmonics, but the HDesv scale is low = 14. The time signal shows low-amplitude shocks. From the second measurement, taken on Februay 4th, 2016, and onwards, the HDm/HDc levels are much higher and the spectrum shows a higher number of harmonics in the BPFO match. Further-more, the HDesv scale increased to 400. The level graph in Figure 2 below shows very high HDm levels in the range of 45 and 59 dB, and a high delta value - on average 45 dB:

At the last measurement - taken on April 22nd, 2016, just after replacement of the faulty bearing - the HDm value has dropped considerably.

Bearingreplaced

Fig 2. Graphics showing RPM, HDm/HDc levels – measuring period from January 13th, 2016 to April 22nd, 2016.

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An SPM HD spectrum from the first measurement on the front reversible roll shows high HDesv lev-els and quite clear BPFO indications:

Fig 3. SPM HD Spectrum from the front reversible roll at the first measurement from January 13th, 2016.

Fig 4. SPM HD Spectrum from the front reversible roll on February 11th, 2016, showing very clear symptom matches for outer race damage.

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In the SPM HD Spectrum, the number of BPFO matching harmonics increased from 6 to 31, with the HDesv value increasing from 14 to 400:

In the Time signal and Circular plot graph, slightly over eight shocks per revolution (BPFO 8.21) can be clearly observed:

Fig 5. Enlarged SPM HD Spectrum from the front reversible roll on February 11th, 2016.

Fig 6. Time signal and Circular plot.

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In the Colored Spectrum Overview, there is some mismatch between the harmonic lines, which is the result of non-simultaneous measuring of speed and RPM variation. The BPFO matches can be seen also here:

Fig 7. Colored Spectrum Overview.

Bearingreplaced

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7 Appendix

The following photographs of the dismounted bearing SKF 22228CC, show the outer and inner race bearing damage. The marks on the outer and inner race are the result of chemical corrosion caused by the entering of aggresive chemicals into the bearing housing (see Images 1-4 below).

Img 1. The bearing outer race damage.


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hd technology case study - spm instrument

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