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Pumping Plant Profit

On-Line Management

and

Control

Stanislav Pejovic PhD

in cooperation with

Electronic Design

1997


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Troubles are repeating every day.

This Software helps you to prevent them.
___________________________________


Address your letter to:

Stanislav Pejovic

E-mail: pejovics@asme.org

stan.pejovic@utoronto.ca

spejovic@ryerson.ca

Website: http://fon.fon.bg.ac.yu/~cane/

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Pumping Plant Profit On-Line Management and Control

Some new features:

Abstract

We propose here a Pumping Plant Profit On-Line Management and Control software of pumping units custom designed to increase profit, to instruct plant and system technical and management staff what to do when selecting the most profitable operating points of the system. Selecting the most profitable plant operation mode so that the system could have the highest efficiency.

We conclude here that by selecting the best exposure rate the profitability and reliability of plants and related subsystems can be increased. Optimizing the pumping system by applying the PP Profit On-Line Management and Control softwares of all critical plant units into the monitoring and control computer system one may increase profitability and minimize energy consumption level.

Selection of input data is based on Standards, Guidelines, Tests, and Technical Literature results. By means of statistical analysis of measured and recorded data, the efficiency of the PP Profit On-Line Management and Control software could be improved

Production Costs

Energy production costs, see Fig. 1, are dependent on vibration intensity and corespondent exposure rate increasing continuously in time. They could be presented in a form dependent to the exposure rate. According to literature and our experience the present chart is constructed. The statistical data on particular unit should and could improve and update application and software data.

Fig. 1. Reference production costs and on-line production costs

Based on fixed production costs cfw (Cent/l) and cost Cpw dependent on exposure rate e, amplitudes A, corresponding frequencies F, Net Positive Suction Head NPSH (cavitation), etc. the profit p (USCents/l) is

Even if the initial cost of a plant is high the balance could be achieved by adequate low maintenance and replacement costs reducing vibrations and exposure rates.

Profit

From the Chart, see Fig. 2, evidently profit could be increased applying PP Profit On-Line Management and Control analyses. The best operating zone is around 20 - 40 l/s. Over load above 60 l/s reduces profit destroying units. Operating discharge smaller than 10 l/s is also inconvenient.

Fig. 2. Reference profit and on-line profit

If a unit operates frequently close to 65 l/s or even over, the system has not enough capacity and new plants and additional units should be built. If a unit frequently operates in zone between 0 to 10 l/s unnecessary large numbers of units of the system are in operation.

Exposure rate

Exposure rate, see Fig. 3, as correlation between the real time and reference time of operation, is the most important characteristic of a unit. It is a statistical data. Some standards, guidelines and technical papers consider vibration of bearings, and correlate them to the exposure rate. The on-line measured data compared to the data measured several hundred hours ago are changing in time. They are highly influenced by real time of operation and exposure rate, corespondent to the operating point. The difference marked by (red) arrows generally increase in time during unit operation. It is proportional to the times of operation and corresponding exposure rates for the particular bearing. Vibrations (amplitudes and corresponding frequencies), intensive cavitation, etc. has strong influence on numerical values of exposure rate. The presented charts are based on the data from technical literature and should be and could be improved for any plant analyzing files of measured and logged statistical data which will improve numerical on-line measured and calculated values.

Fig. 3. Reference exposure rate and on-line exposure rate

Pump Characteristics

If a plant has an acquisition system for flow measurement the pump characteristic curves could be compared to the site measurement and updated. Accuracy of test data could be analyzed and the real machine curves improved.

Fig. 4. Pump characteristic curves

Fourier Analysis of Bearing Vibrations

Fourier analyses, see Fig. 6, of measured bearing displacement, see Fig. 5, is important input data for profit and reliability of plants.

Fig. 5. On-Line measured Displacement of guide bearing

Fig. 6. On-Line or Off-Line Fourier analysis

Comment on these data is very important. These charts for experienced staff could discover very important information on plant and unit itself.

Measured Amplitude of Pump Bearing Vibrations and Previously Measured Characteristics

Statistical vibrating characteristics are based on guidelines and standards, see Figs. 7, 8 and 9. For the Plants with own experience these data could be sometimes more realistic.

Fig. 7. Vibration standard VDI-2056

Fig. 8. Evaluation of shaft vibrations of turbosets. VDI-2059, provided in 1979.

Fig. 9. Vibration amplitude of normal operation and transient state Rund 1980.

Vibration Characteristics of pumps are a typical one and could be easily measured on a pump with PP Profit On-Line Management and Control measuring and acquisition system.

Amplitude of bearing vibrations, see Fig. 10, increases in time. Distance of the measured point from the previously measured amplitude characteristics are proportional to the real time of operation and corresponding exposure rate. Applying this method the time intervals of operation between maintenance and/or replacement of unit components could be estimated. Statistical data, on particular unit and plant, improves the results of analysis reducing operating, maintenance and replacement direct cost.

Fig. 10. Reference amplitudes , and on-line measured amplitude

Limit Values for Trip

Limit values of amplitudes of displacement are stated in standards and guides. For the presented case limits are: excellent 25 mic (microns), good 60 , satisfying 160 mic, and bad over 160 mic, see Fig. 10. When limit good 60 mic is reached, an alarm should be given. The cause for the increased vibrations should be analyzed. If limit satisfying 160 mic is exceeded, damage must be expected. The unit is to be shut down for examination. In the range satisfying, 60 - 160 mic, operation is only permitted under particularly close supervision.

Accuracy

Starting PP Profit On-Line Management and Control system by applying data from standards, guidelines, tests and technical literature the average accuracy could be about 30 % overall. Analyzing experimental measured and logged data together with Pumping Plant technical and management experienced staff errors can be reduced very quickly.

Average accuracy, see Fig. 11, and individual accuracy of measured and calculated values do not effect on profit since this method is a comparative one. If the PP Profit On-Line Management and Control informations are correctly followed the maximum benefit will be achieved and only the total value prediction will be influenced by accuracy. That means that the predicted profit at the beginning of a new time period will differ from the realized profit. Only this difference could be reduced increasing accuracy

Fig. 11. Increasing of accuracy

Appendix

Flow diagram, see Fig A1, as LABTECH CONTROL pro Build-Time shows advantages of data acquisition and Process Control Software. Corresponding PP Profit On-Line Management and Control VISION Widow, see Fig A2, gives information on profit and losses of the unit in operation. Any measured on-line, laboratory tests, and site test data could be put on the screen. Profit versus flow characteristic and on-line measured data suggest the best operating point of the unit. Following instructions PROFIT could be increased approaching the maximum benefits.

With the PP Profit On-Line Management and Control any or all charts and applications could be on-line analyzed and logged in files and later on on-line or of-line replied. Saved data could be very important in the case of incidents and accidents. As a Black Box they could help investigators to discover what really happened.

Fig. A1. Flow chart

Fig. A2. Screens of personal computer


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Troubles are repeating every day.

This Software helps you to prevent them.
____________________________________


Electronic Design has been founded in 1982 by Mr. Slobodan Kotri. In 1985, first in the World, ED had developed the European Format industrial PC. Among World wide customers are SIEMENS and PHILIPS, (World greatest producers of processing systems). ED produces controllers based on PC platform. Mr. Kotri has been in the field for more than 25 years. He has been always on the cutting edge of the technology. He loves ice-cream and enjoys golf.


Troubles are repeating every day.

This Software helps you to prevent them.

Stanislav Pejovic

E-mail: pejovics@asme.org

stan.pejovic@utoronto.ca

spejovic@ryerson.ca

Website: http://fon.fon.bg.ac.yu/~cane/

<All edited and programmed by
Prof. S. Pejovic himself>


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