Pulverizer Monitoring Project

Ameren's Rush Island Plant

1012289

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1338 ▪ PO Box 10412, Palo Alto, California 94303-0813 ▪ USA

800.313.3774 ▪ 650.855.2121 ▪ askepri@epri.com ▪ www.epri.com

Pulverizer Monitoring Project

Ameren's Rush Island Plant

1012289

Technical Update, November 2006

EPRI Project Manager

W. Crawford

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THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM:

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ORGANIZATION(S) THAT PREPARED THIS DOCUMENT

Engineering Consultants Group, Inc.

Electric Power Research Institute (EPRI)

This is an EPRI Technical Update report. A Technical Update report is intended as an informal report of continuing research, a meeting, or a topical study. It is not a final EPRI technical report.

NOTE

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Electric Power Research Institute and EPRI are registered service marks of the Electric Power Research Institute, Inc.

Copyright © 2006 Electric Power Research Institute, Inc. All rights reserved.

iii

CITATIONS This document was prepared by

Engineering Consultants Group, Inc. 1236 Weathervane Lane Akron OH 44313

Principal Investigator M. Santucci

Electric Power Research Institute (EPRI) 1300 W.T. Harris Blvd. Charlotte, NC 28262

Principal Investigator S. Parker

This document describes research sponsored by EPRI.

This publication is a corporate document that should be cited in the literature in the following manner:

Pulverizer Monitoring Project: Ameren's Rush Island Plant. EPRI, Palo Alto, CA: 2006. 1012289.

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ABSTRACT The Roll Bowl COP (RBC) technology was developed to provide specific information for the evaluation of the grinding components of the Alstom Raymond bowl type coal pulverizers. Dynamic and static data acquisition means and procedures were researched, tested and refined over time so that the material condition of the grinding elements and the stress levels of their operating characteristics could be determined. The result of the analysis allowed specific corrective actions and adjustments to be made to uniformly distribute the work contribution of respective rolls and to optimize the stress levels and operational performance. The mills could then be operated with greater availability and reliability and with optimal performance including fineness, load capability and turndown – all at lower life cycle costs.

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ACKNOWLEDGEMENTS The Pulverizer Monitoring Project at Ameren’s Rush Island Plant is being performed by personnel from the Engineering Consulting Group, Inc. and the AmerenUE Rush Island Plant. EPRI would like to thank the following individuals for their contribution to this effort:

AmerenUE Rush Island Plant:

James A. Barnett, P.E. Mechanical Engineer Technical Support

Gregory W. Vasel, P.E. Supervising Engineer Technical Support

David L. Strubberg, P.E., P.M.P Superintendent Technical Support & Maintenance

Engineering Consulting Group, Inc.:

Michael T. Santucci President

Matthew Caesar Development Engineer

Joseph L. Hoffmann, P.E. Mechanical Engineer

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CONTENTS

1 BACKGROUND......................................................................................................................1-1

2 RBC TECHNOLOGY..............................................................................................................2-1

3 RESULTS TO DATE ..............................................................................................................3-3

4 ADDITIONAL WORKSCOPE.................................................................................................4-1

1-1

1 BACKGROUND The Pulverizer Monitoring Project takes place at the AmerenUE Rush Island Plant located in Jefferson County, Missouri on 500 acres on the western bank of the Mississippi River. The plant is located about 40 miles south of downtown St. Louis. The first unit went into operation in March 1976 and the second unit in March 1977.

The Pulverizer Monitoring Project is a 2-year project to demonstrate and to document the Engineering Consultants Group (ECG) Roll Bowl COP (RBC) OnLine real time mill operations and condition monitoring benefits for 2 units (total of 12 mills) with the Alstom RP-903 design pulverizer mills. Each mill is equipped with a displacement transducer and accelerometer on each roll (3 rolls/mill). In addition, accelerometers are placed on the worm gear, thrust bearing, and outboard motor bearing. This is a total of 3 displacement transducers and 6 accelerometers for each mill. Figures 1-1 through 1-4 show the instrumentation installed on each mill.

Figure 1-1. Roll Displacement Transducer and Accelerometer

Journal Accelerometer

Displacement Transducer

1-2

Figure 1-2. Worm Gear Accelerometer

Figure 1-3. Thrust Bearing Accelerometer

Thrust Bearing Accelerometer

Worm Gear Accelerometer

1-3

Figure 1-4 Outboard Motor Bearing Accelerometer

The installation of the RBC OnLine instrumentation and cables began in December 2005 and was completed in February 2006. The instrumentation cables go to a local

RBC DAS (Data Acquisition System) box for signal conditioning and processing and then to the dedicated RBC computer located in the plant’s terminal room. Figure 1-5 shows a typical DAS box serving two adjacent mills.

1-4

Figure 1-5. Unit 1 & 2 Data Acquisition System

After data processing by the RBC computer calculation engine, the data goes to the Plant Information (PI) system server and then to the AmerenUE server for operations and engineering monitoring. The historical data is then available to plant technical personnel and to ECG through an internet connection with Ameren—the parent company of AmerenUE. In this way, the data can be jointly monitored, analyzed, and discussed among remote locations.

Mill A DAS

Mill B DAS

2-1

2 RBC TECHNOLOGY The Roll Bowl COP (RBC) technology has become a valued engineering tool in the preventive/predictive maintenance area of coal pulverizers. The implementation of the RBC technology allows an analysis and engineering evaluation of the coal pulverizer using a tool that is non-intrusive. The data are acquired relatively quickly and the results portrayed in a user-friendly format. Through reference to a library of prior RBC data and analyses, the mill evaluation can be used to prioritize scarce plant resources for best cost / benefit payback.

The RBC data are reviewed in both the time domain and in the frequency domain, the latter using fast Fourier transform (FFT). The time domain is most informative during the initial introduction of the coal to an empty pulverizer mill. The relative behavior and position of the respective journal traces provide indications of conditions in the journal assembly, several that are correctable settings and others that are properties of the components (e.g., wear, spring constant). Time domain information at different loads provides indications for optimization adjustments to attain load capability, fineness, turndown, and appropriate inventory for the pulverizer mill. The time domain is also a resource for detecting short-term events such as tramp material or pluggage.

The frequency analysis is a FFT application to time domain data that meets qualifications for the analysis, specifically data frequency, and sampling duration. The primary interest is in the lower frequency spectrum, 40-600 cycles per minute (CPM) or about 1x bowl to 7x bowl frequency. These graphics provide characteristics distinctive of the bowl and each of the journal rolls. Properties that can be indicated include eccentricity of the bowl or rolls, spalling of weld overlay, mechanical looseness and relative roll diameters. Higher frequency capabilities to about 1300 CPM can be used to detect resonance (not uncommon) and bearing degradation, the latter recommended to be verified with predictive equipment more suitable for the higher frequency spectrum.

The first RBC systems were proven based on snapshot looks at the mill data. This method was most valuable in identification of suspected problems, in post-maintenance verification of the setting and periodic check-ups and trending of overall condition and wear. The adaptation to an RBC OnLine system enables the continuous evaluation of the mills and, with deficiencies identified, the appropriate assignment of the remedial activity. This quantum leap of available information required the development of algorithms and boundaries to identify specific deficiencies and establish alarm levels for operator and/or maintenance attention.

With the RBC OnLine system, the properties of the RBC technology can be applied on a continuous basis to provide to the user the following benefits:

• Prevent or provide early indication of fatigue failures and bearing degradation through balanced loading and optimized stresses.

• Prolong grinding element life and premature failure/replacement through distributed wear and operation within design conditions.

2-2

• Minimize coal spillage through efficient grinding conditions and controlled mill inventory levels for the corresponding load.

• Increase mill availability and reliability by proper set-up of the mill and early detection of problems or off-spec conditions.

• Enhanced performance over the entire load range (full load capability to turn-down) with fineness and capability to address concerns of opacity, LOI, NOX and slagging.

The trending of the mills’ RBC data is available for review on user-friendly trend displays at the plant. This data can be used compare to the data on sister mills in the plant subject to similar operating conditions and known maintenance histories.

The project’s RBC OnLine data availability has been very good. The data is accessed through the Plant Information (PI) system. The hardware used in the RBC technology has been reliable. However, a recent sequence of power supply failures is still under investigation.

Data trending has on several occasions identified gradual degradation of bearings, early detection of roll weld overlay issues, abrupt changes in cyclic fatigue stress and coal hardness variations. These RBC OnLine capabilities have allowed the plant engineering staff to be proactive, enabled maintenance on a scheduled basis, and avoided mill related unscheduled unit derates.

3-1

3 RESULTS TO DATE After six months of the 2-year demonstration project, the RBC OnLine information has provided the plant staff with support for the enhanced performance and availability of the mills.

Some of the mill problems that have been detected are:

• 2A Mill, Roll 2 - Figure 3-1 shows the startup plot of the 2A mill with a large journal head-to-spring gap indicated on the #2 roll. Loose clamp plate studs were found on the #2 journal assembly and repaired.

Figure 3-1 Startup Plot of 2A Mill

• 2E Mill, Roll 3. Part of the roll weld overlay had spalled off. This problem was detected from a roll profile plot from the roll profile data. Figure 3-2 shows the profile plot.

3-2

Figure 3-2 Mill 2E, Roll 3 Profile Plot

• 2E Mill, Roll 1. The roll bearings failure was detected from vibration readings from the roll accelerometer. The plant determined that approximately $21,500 was saved in detecting the roll bearing failure on the 2E1 mill roll. Figure 3-3 shows the trending of the vibration for this roll.

Figure 3-3 2E1 Vibration Trending Chart

• 1D mill - Bowl profile problems detected. Figure 3-4 shows the bowl profile plot.

3-3

Figure 3-4 1D Mill Bowl Profile Plot

Several occasions were notable in the detection of singular events that, if left undetected, could have caused consequential damage, either direct mechanical breakage or the accumulation of cyclic fatigue damage. With the RBC OnLine operator alarm features, isolated events such as tramp iron ingestion, weld hard-face spalling, spring breakage or component loosening (e.g., stop bolt, spring retainer, etc) can be addressed promptly and long-term mill availability assured.

The RBC OnLine trending features have shown degradation trends well before the onset of imminent failure. This is particularly true of the vibration signatures and, with continued degradation, followed in the later stages by indications in the lower frequency domain of the RBC analysis.

4-1

4 ADDITIONAL WORKSCOPE There are 2 topics that have been added to the original workscope. They are:

• ECG is testing the applicability of ultrasonic probes on the coal pipes exiting the mill to trend overall fineness with initial testing showing favorable correlation. Initial testing showed favorable response. During this demonstration it may be determined if ultrasound is a useful method for detecting large particle impacts with the wall in long vertical transport pipes. The goal of the study would be to isolate the effects of varying coal and air flow to correlate sound activity to mean particle size. UE Systems has loaned the plant 6 of their Ultrasonic Testing probes for this testing.

• ECG has developed an RBC Bowl Profiler that was demonstrated on the 1D mill in August 2006. A laser measuring instrument was fixed to the mill housing and a scan taken as the bowl was rotated. Results of the bowl survey scan were graphically displayed and showed the actual contour of the bowl. This information is valuable in verification and enhancement of bowl geometry broadly defined through the frequency analysis. The profiler will also allow determination of the actual bowl angle and if justified, corrections that would provide determination of optimal bowl-to-roll clearance for fineness with load capability.

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800.313.3774 • 650.855.2121 • askepri@epri.com • www.epri.com

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