EVALUATING ENERGY CONSUMPTION ON MISALIGNED MACHINES

Transcription

1 EVALUATING ENERGY CONSUMPTION ON MISALIGNED MACHINES Debate surrounds the issue of energy consumption rates for aligned versus misaligned machinery. Some experts maintain that power savings for well aligned machinery lie only in the realm of Reactive Power (KVAR), a value which has no impact on utility rates. Supporters of this philosophy claim your power bill will not reflect higher or lower rates based on the quality of alignment you achieve throughout your plant because electric rates are based on Real Power (kw) consumption. Other experts advise customers as to significant savings realized in utility consumption if they operate well aligned machinery. They claim that well aligned machinery reduces measured Real Power (kw) consumption by reducing shaft energy losses. In other words, proponents of this perspective contend that energy losses occur within a shaft/coupling arrangement depending on existing misalignment (See Figure A). Figure A Return to ALLMAN Beginning 1 Return to ENTERACT 97 Home Page

2 Loaded machine with laser shaft alignment system and vibration transducers mounted. In an attempt to In learn more about these issues, we recently conducted a series of experiments on two machine sets under laboratory conditions and a group of machines selected at random within a factory powerhouse. First we will discuss the laboratory tests. Following that discussion we will present data collected on randomly selected field machinery. One laboratory machine set was coupled, but unloaded. Another set was coupled and loaded to 25 percent. Please refer to the specification details in Tables 1 and 2. Delco Motor Delco Motor Model #: 262T04 Model #: 2G Phase-460 Volts AC 3 Phase-460 Volts AC Horsepower: 3 HP Horsepower: 3 HP Speed: 1765 rpm Speed: 1170 rpm Frame size: 213 Frame size: 215 Amps: 4.16 amps/leg Amps: 4.9 amps/leg Frequency: 60 Hz Frequency: 60 Hz Sperry Vickers Pump Racine Silentvane Pump Model #: PVB15ERSY30CM11 Model #: PSV-PSSF-15DRM- 51 Coupling: Lovejoy; 7/8 Bore; 3 finger aluminum hub, with neoprene insert Coupling: Magnaloy; Model 100; 1¼ X ¾ Bore; Fingered aluminum hub with neoprene insert Base: 1 thick machined and ground steel base. Base: 3 on 12 Sloped wing base;.875 thick machined and ground steel base Unloaded Machine Assembly Specifications Specifications Loaded Machine Assembly Table 1 Table 2 Return to ALLMAN Beginning 2 Return to ENTERACT 97 Home Page

3 Unloaded machine with vibration frequency analyzer. Tests on the machine sets consisted of introducing an arbitrary amount of misalignment to each machine assembly. The amount of misalignment introduced was judged to be typical of many new installations before a precision alignment procedure is performed. A 15 minute spin test was performed on each misaligned machine assembly. Vibration, noise level, horsepower, and real power over time were among the parameters recorded throughout the test cycle. Subsequent to the first spin test, each machine assembly was then aligned and newly measured parameters were obtained during a repeat of the initial spin test. Figures 1 through 8 depict the initial and final alignment conditions existing during the spin tests. Please note that all gap values are based on a ten inch diameter coupling. Return to ALLMAN Beginning 3 Return to ENTERACT 97 Home Page

4 Figure 1: Initial Horizontal Misalignment - Unloaded Machine Figure 2: Initial Vertical Misalignment - Unloaded Machine Figure 3: Final Horizontal Alignment - Unloaded Machine Return to ALLMAN Beginning 4 Return to ENTERACT 97 Home Page

5 Figure 4: Final Vertical Alignment - Unloaded Machine Figure 5: Initial Horizontal Misalignment - Loaded Machine Figure 6: Initial Vertical Misalignment - Loaded Machine Figure 7: Final Horizontal Alignment - Loaded Machine Return to ALLMAN Beginning 5 Return to ENTERACT 97 Home Page

6 Figure 8: Final Vertical Alignment - Loaded Machine Charts 1 through 5 depict test results. One of the most interesting charts illustrates the average amount of accumulated energy expressed in terms of kilowatt-hrs consumed by each of the machine sets. It is noted that apparent energy savings of 2.3% for the loaded machine comparing aligned and misaligned conditions where not as dramatic as the 9.1% difference generated by the unloaded machine. This is easily explained when one considers that efficiency of induction motors increases as percentage load increases. In the foreground is Ludeca s System 2 combination laser shaft alignment, balancing, and vibration analysis system. Pictured in the background is the Dranetz Energy Analyzer. We should expect somewhat smaller energy savings for an induction motor properly loaded between 75% and 100%; perhaps somewhere in the neighborhood of 1%. Nevertheless, a most remarkable finding is there apparently exist measurable differences in Real Power consumption between aligned and misaligned machines. Return to ALLMAN Beginning 6 Return to ENTERACT 97 Home Page

7 Energy Accumulation After alignment Before alignment Loaded Motor-Pump Assembly 1.105kWh kwh.373 kwh 2.3% Energy savings Unloaded Motor-Pump Assembly.339 kwh 9.1% Energy savings Watt Hours Chart 1 A 2.3% saving in energy usage will reveal itself as a tremendous power saving when extrapolated over the course of a machine s life. Chart 2 data illustrates horsepower requirements. The results gleaned from the horsepower measurement process closely support data recorded by the energy analyzer. Considering a 25% load was induced on the loaded machine assembly, one may readily calculate that the data is reasonable for a 3 horsepower motor. Return to ALLMAN Beginning 7 Return to ENTERACT 97 Home Page

8 Horsepower Measurements After alignment Before alignment.75 HP Loaded Motor-Pump Assembly.74 HP 1.3% decrease.46 HP Unloaded Motor-Pump Assembly 8.7% decrease.42 HP Horsepower Chart 2 Vibration and noise data are consistent with expectations. Although the loaded machine set did not yield typical overall amplitudes or spectra, relative vibration and noise reductions between aligned and misaligned conditions are apparent. One reason for this is perhaps the sloped wing base on which the loaded machine is mounted. Charts 3, 4, and 5 summarize overall vibration data as per ISO 2372 and noise levels measured in decibels. For Charts 3 and 4, acronyms are used to describe measuring orientations. The letters M and P refer to motor and pump respectfully. O and I refer to outboard and inboard bearing locations relative to coupling proximity. H, V, and A stand for horizontal, vertical, and axial vibration sensor orientations on the bearing itself. Return to ALLMAN Beginning 8 Return to ENTERACT 97 Home Page

9 Vibration Levels for Unloaded Motor-Pump Assembly POV After alignment Before alignment POH PIV PIH MOV MOH 80.50% average reduction in overall vibration MIA MIV MIH Overall Vibration Velocity RMS Between Hz as per ISO 2372 Chart 3 Vibration Levels for Loaded Motor-Pump Assembly PIA PIV PIH MOV MOH After alignment Before alignment MIA MIV 44% average reduction in overall vibration MIH Overall Vibration Velocity RMS Between Hz as per ISO 2372 Chart 4 Return to ALLMAN Beginning 9 Return to ENTERACT 97 Home Page

10 Noise Levels During Testing 63 db Ambient noise level After alignment Before alignment 69 db Noise level of unloaded machine 73 db 5.4% reduction in overall noise level 72 db Noise level of loaded machine 77 db 6.5% reduction in overall noise level Decibels (db) Chart 5 A few axial measurement positions were unobtainable due to machinery configuration. Several attainable axial positions beautifully portrayed classical misalignment spectra. Figure 9 is a spectrum taken axially on the inboard motor bearing of the unloaded machine set before alignment. Harmonic activity, often associated with misalignment, is clearly visible. The highest amplitude value occurs near 3 times running speed and is severe enough to cause problems. Indeed, in Figure 10, the post-alignment spectrum taken out to 150,000 cpm, shows evidence of bearing damage. Please note in Figure 10 that harmonic activity, while not totally eliminated through alignment, is reduced by about 40 orders of magnitude. As mentioned earlier, the loaded machine did not exhibit expected overall or spectral data. Spectrums collected both before and after alignment failed to yield any specific frequency components above.015 inches per second. We did, however, notice a 44 percent reduction in overall vibration levels as evidenced in Chart 3. Figure 9 Return to ALLMAN Beginning 10 Return to ENTERACT 97 Home Page

11 Various noise levels between aligned and misaligned conditions provided no surprises. The ambient noise level was 63 decibels. However, all experiments were conducted inside an isolated training room. According to OSHA, the maximum permissible level of continuous sound allowed for 8 hours within an industrial setting is 90 decibels. Many plants operate above this range and require hearing protection to be worn at all times. In relative terms, it is Figure 10 noted in Chart 5 that noise levels may be significantly reduced on individual machines which are properly aligned. A comprehensive program of alignment throughout a facility can be expected to reduce the ambient noise level of a factory. Conclusions from laboratory tests point strongly to energy savings when taking lightly loaded and grossly misaligned machinery to a precision aligned condition. The aligned machinery consumed less accumulated electrical real energy than misaligned machinery. This saving directly relates to overall utility rates. However, what about machinery which is more realistically loaded and having a moderate amount of initial misalignment? To explore this possibility further, another series of tests was conducted on randomly selected machines at a factory powerhouse. The test format was altered to allow for two hour spin tests with close monitoring of power factor. Two hour spin tests conducted under non-varying demand and supply conditions were thought to be a much better way to proceed with a fair analysis of power consumption differences between aligned and misaligned machines. Return to ALLMAN Beginning 11 Return to ENTERACT 97 Home Page

12 The following summarized data from the power tests are as follows: Machine Assembly #1 Motor - Delco Model G7054MA, 3 Phase, 460 Volts, 60 HP, 67 Amps/Leg, 60 Cycle, 3560 rpm, SN-B-76 Pump - Ingersol Rand, Type GT, Size 2 GT, 3540 rpm, SN 1187/812 Coupling - Falk 1060T10 Comments: Machine Assembly #1 consists of a motor driven hot water pump. The temperature of the pump varied from 175 to 180 degrees Fahrenheit. Water temperature was measured to be 243 F. A target of.003 inch for the motor (motor 3 mils higher than pump) was provided for the alignment. Hot alignment checks were made and slight variations from the cold positions were noted. Severe misalignment was removed from the assembly. It was noted that the coupling temperature across all bearings changed from 111 F to 97 F before and after the alignment, respectively. It was estimated that the motor was loaded to approximately 75 percent. Vibration and noise data were gathered on the machinery, but considered superfluous to this study. Quite unexpectedly, little change in vibration took place before and after the alignments. Machine Assembly #2 Motor - Delco Frame 445US, 60 Amps/Legs, SN 6466, 460 Volts, 100 HP, 3575 rpm Pump - Ingersol Rand, Model 3GT, 350 gpm, SN Comments: Machine Assembly #2 consists of a motor driven hot water pump. The temperature of the pump varied from 115 to 229 degrees Fahrenheit, depending on the section of the pump where temperature readings were taken. Generally speaking, temperature measurements recorded after the assembly was aligned dropped by an average of 14.3 F across all bearings. No targets were given for Machine Assembly #2. Hot alignment checks were made and variations from cold positions were noted. Moderately high misalignment was removed from the assembly. It was noted that the coupling temperature changed from 97 F to 89 F before and after the alignment, respectively. It was estimated that the motor was loaded to approximately 75 percent. Return to ALLMAN Beginning 12 Return to ENTERACT 97 Home Page

13 Quite unexpectedly, little change in vibration took place before and after the alignments. Machine Assembly #3 Motor-Blower Assembly Comments: Energy consumption data was collected on this unit, but it had to be abandoned. Machine Assembly #3 was not alignable without making major changes in the foundation. Return to ALLMAN Beginning 13 Return to ENTERACT 97 Home Page

14 Machine Assembly #4 Motor - Delco Model B-2495, Code F, SN H56, Design B, 60 cycle, 15 HP, 220 Volt, 1755 rpm, 18.4 Amps/leg, 3 phase, Frame 284-U Pump - Ingersol Rand, Size 3 DMV, SN , 200 gpm Comments: Machine Assembly #4 consists of a motor driven cold water pump. The temperature of the pump varied somewhat, but fluid temperature played no role in these fluctuations. Rather, an average reduction of 12 F across all bearings was observed after a precision alignment was executed. No targets were applicable for Machine Assembly #4. Severe misalignment was removed from the assembly. It was estimated that the motor was loaded to approximately 75 percent. Quite unexpectedly, little change in vibration took place before and after the alignments. Procedure: 1. Connection of Dranetz unit to Motor. Usually, we made connections at the wiring control panel where lockouts are performed. 2. Program the Dranetz analyzer to collect Real Power (kwh) over a two hour period with a printout every hour. Make careful note of Power Factor fluctuations. Use data IFF Power Factor variations remain less than.1 PF. Ideally, You want PF to remain constant. Average data for energy accumulation over 1 hour. 3. Collect Process Parameter data; vibration (overall and spectrum), temp, speed, noise level, pressure, % load. 4. Stop unit and perform alignment to excellent tolerances. 5. Repeat steps 1 through 4. Return to ALLMAN Beginning 14 Return to ENTERACT 97 Home Page

15 Alignment Values MA #1 HA Angularity expressed in Mils/10 inches 18.2 Pre-alignment Post Alignmment Parameter VA HO Tolerance for 3600 rpm: Offset =1 mil Angularity = 2 mils/10inches Offset expressed in Mils VO Note: Excellent tolerances were met at cold condition, however "Hot Quick Check" revealed differences Amplitude Alignment Values MA #2 HA Angularity expressed in Mils/10 inches Pre-Alignment Post Alignment Parameter VA HO Offset expressed in Mils 8.42 Tolerance for 3600 rpm: Offset = 1 mil Angularity = 2 mils/10 inches VO Note: Excellent tolerances were met at cold condition, however "Hot Quick Check" revealed differences Amplitude Return to ALLMAN Beginning 15 Return to ENTERACT 97 Home Page

16 Alignment Values MA#4 HA -3 Angularity expressed in Mils/10 inches Pre-Alignment Post Alignment Parameter VA HO Tolerance for 1800 rpm: Offset = 2 mils Angularity = 3 mils/10 inches Offset expressed in Mils VO Note: Cold water city pump. No hot values Amplitude Real Power Consumption/Energy Accumulation Machine Assembly # % reduction Machine Assembly # % reduction Machine Assembly # % reduction Pre-alignment Post alignment KWH Return to ALLMAN Beginning 16 Return to ENTERACT 97 Home Page