PdM centralization for significant energy savings

Dale P. Smith
Tags: energy management, predictive maintenance, condition monitoring

All facilities lose energy dollars through overheated electrical distribution systems and overloaded and misaligned rotating assets, as well as lose expensive compressed air and steam through leaking pipes/fittings. Couple this with the increasing pressures of global competition, a thinning workforce and budget constraints, and you have significant issues/opportunities. A remedy is to improve equipment reliability by fully leveraging predictive maintenance (PdM) technologies.

This paper focuses on how the successful integration of standard PdM technologies along with centralized reporting can capture significant energy savings and simplify ROI calculations. By the way, any associated benefits of increased safety, reliability and enhanced facility capacity is purely coincidental.

Matching Knowledge and Information
Bailouts, barrels of oil at $150 per barrel, boom and bust of the housing markets, wars, elections, and the gloomy global economy have forced hard decisions for many. For example:

  1. Rising fuel costs force airlines to get creative and pass the costs to flyers such as charging for food, leg room, checked luggage and even pulling wires to reduce weight.
  2. Even one man’s trash is another’s treasure. For years, no one wanted sawdust. Now it is up to $50 per ton or $1,200 per truck. One may say “we are being forced to get everything out of the pig except the squeal.”

These types of external pressures are squeezing all corporate profits, sustainability goals and affecting maintenance organizations which are:

  • already thinly staffed with backlogs exceeding available hours;
  • very reactionary;
  • and relegated to keeping the existing systems as good as possible.

How will you get creative to save money and add back to the bottom line or protect whatever reliability team is still standing? This is difficult since many facility maintenance departments are caretakers of older equipment and systems which were not designed for energy conservation.

Let’s pretend you are making the big bucks with few headaches as the director of facilities at a large pharmaceutical company, overseeing a reliability program of 24,000 assets at 10 plants in the eastern United States. In the last six months, more than 3,000 positions have vanished and the buzz is that there are more layoffs coming, less overtime and a 15 percent cost reduction mandate across the board. Forget getting the capital for improvements; you are trying to keep your reliability program staffed and sustaining production.

Where are you going to find some money?

The good news is that in most cases, the energy savings can be found within your existing processes. Your organization has the knowledge to address the issues but may lack the information to pinpoint the cause and implement timely and cost-effective repairs.

The great news is that you have a centralized enterprise asset management (EAM) system that will help mine and trend information that can identify systems with the highest probability of providing energy savings. You were told the information is there, so it time to start making this system pay off.

A quick search of the EAM platform shows that infrared thermography of your electrical systems has identified 793 temperature anomalies totaling 44,300 degrees Fahrenheit over OEM heat curves and a potential savings in the next year of $94,353.

Just like a crime scene investigator, you have followed the clues to find the bad actors. Now that you have the information, applying your knowledge is easy and determines the direction and proactive strategies. Using a rule of thumb that 70 percent of electrical thermal issues are caused by loose connections, cross-referenced with your top 10 components (blue highlights), the list starts to become a little more manageable with 521 items worth $80,000 in savings (blue highlights).

Your plan of action is twofold. Issue work orders to critical systems with connection issues or the highest paybacks and establish a connecting torque program during the annual infrared inspections. Successfully eliminating these poor/loose connections items eliminates 30,000 degrees F in excessive temperatures (bright yellow highlights) and the associated fire and safety risks.

If you are lucky, you could pick up more savings by using the EAM platform to cross-tie the next bad actor cause category of internal flaws with components already being addressed or near these systems. You are confident since this energy-saving opportunity doesn’t include motor systems, compressed air, steam, etc.

Realities of Knowledge and Information Gaps
Most organizations are in some mode of not having perfect information, trying to add a technology and/or trying to build a critical mass of data that can be mined for asset/financial information which will get them a voice for more funding and support for reliability programs. If any of these fit your situation, the following steps and calculations can help guide you through typical facility systems, PdM technologies that can identify issues and basic energy-saving calculations.

Step 1 – Build an Inventory of Your Assets
It is crucial to gain a complete picture of all assets within a reliability program, or at least the equipment targeted in your pilot project. If you are very, very lucky, your computerized maintenance management system (CMMS) may have some or all of this information. Depending upon your resource strategy (i.e. all in-house, all outsourced to third parties or hybrid), the challenge is always having the resources/time to work through a mix of report types such as spreadsheets, PDFs, databases, Word documents, and proprietary software and the inconsistencies associated with each.

If you are at the early stages, grab a simple facility layout drawing and notebook and start walking the facility to capture nameplate data.

Step 2 – Get the Energy Bill
This step requires work with the energy manager to review two to three years of bills and energy patterns. If you don’t have an energy manager, your utility suppliers can help explain the billing and any calculations. Using the following sample bill and formula, you are working toward some amount per kilowatt hour that can be applied to your calculations. 

Step 3 – Follow the Money to Prioritize Your Efforts
A simple prioritization approach is to divide the gas, electric and oil bills into two usage categories: by building type and use, and by equipment types which are common to a variety of process and applications (compressed air, pump and fan systems, etc.).

The challenge for most organizations is to determine which systems will provide the biggest payback based upon the specific technologies. The four following facility systems and ideal PdM technologies can help identify opportunities specific to your organization. Each organization has a different profile. For example, industrials have a higher number of motors; pharmaceuticals more HVAC loads; and commercial buildings more focus on the electrical, HVAC and roofing systems.

  1. Electrical distribution – Infrared thermography
  2. Motor-driven systems – Vibration analysis, infrared and motor circuit testing
  3. Compressed air – Ultrasound
  4. Steam – Ultrasound and infrared

Remember, you have a limited number of attempts to gain or keep support, so make sure you are focusing those items with the best probability of showing savings. The intent of this paper and the following examples is to provide basic calculations to establish a concept and “ballpark figure” for electrical and steam energy savings.

Electrical Savings
The key process is capturing power consumption measurements taken before and after placing a piece of three-phase equipment back into service. The two-step process is as follows:

1. Power Calculations

  • kW – kilowatt
  • Volts – voltage used in the application
  • Amps – difference in amperage (before – after)
  • pf – power factor
  • 1000 – takes the total watts and by dividing makes it kilowatts
  • 1.732 – square root of 3 for three-phase power; eliminate this number for single-phase systems.
  • 4.2 = average number of cfm/break horsepower (bhp); this is based on manufacturers’ equipment data

2. Annual Savings

Once the kW is determined, a second formula is required to determine the annual savings:

Annual savings = hours x kW x cost / kW

Energy-saving Assumptions for Calculations:

  • Hours of operation = 8760
  • Cost per kWh = $.08
  • Equipment is fully loaded
  • Motor efficiency factor = .90
  • Power factor = .87
  • 100-horsepower motor
  • Average power requirement in kW per brake horsepower (bhp) to generate one bhp = 0.746
  • Compressed air pressure = 100 PSIG

Steam Calculations
Steam calculation requirements go beyond the intent of this paper due to collecting numerous items such as boiler efficiency, loading, number of boilers, fuel cost per 1,000 BTUs, steam pressures, water treatment chemical costs, labor burden, etc. Depending upon the size of your facility, the boiler plant team will have the cost per 1,000 pounds of steam. The facility energy manager or the boiler manufacturer can help.

Opportunity #1: Electrical Distribution
Electricity and electrical distribution systems are the backbone of how we live and what drives most of our nation’s commercial progress. The issue at hand is that much of the nation’s electrical generation and distribution systems are more than 40 years old. Many have surpassed their designed life and are more susceptible with safety and supply variables. These power issues, such as the following, are often hidden and problematic to equipment:

  • Unstable utility supply / line surges
  • Lightning strikes / transient voltage
  • Unbalanced and overloaded transformer bank
  • Short circuits
  • Unidentified single-phase ground faults
  • Faulty power factor correction equipment
  • Expertise and staffing shortages

These variables are often hidden but can manifest themselves as single-phasing, shorted windings, overheated transformer banks and partially tripped-over current protection.

The Risk and Insurance Perspective

Zurich Insurance Risk Engineering reports identify that 30 percent of all large fire losses are caused by electrical failures (includes all cases and unknown). The following graphic drills down to the component level and shows the percentage of electrical losses caused by lack of maintenance.

Now that we have an inventory road map, we can take a tour of all transformers, switch gear, disconnects, distribution panels and contactors, relays, breakers, etc. Infrared thermography captures thermal anomalies and variances in temperatures. It is ideal for capturing high-resistance, overloaded, phase imbalance and loose electrical connections that cause overheating and waste energy. Scan while equipment is under load and hit critical transformers/connections during high-temperature periods.

During your infrared survey, a 480-volt, three-phase breaker is found to be operating at a temperature of 171 degrees F. The measured ambient temperature is 73 degrees F. The breaker is rated at 100 amps, but the actual load is measured at 38 amps. The anomaly is determined to be a loose connection and requires cleaning and tightening to be returned to a precise state.

Numerous ways exist to calculate the cause/effects of the higher temperatures and energy being wasted (i.e. heat curves, amp draw differences and voltage drop). The following example uses the amp draw difference between pre- and post-repair amp readings. In this case, the amps before were 38 and amps after the successful repair were 35.5, with a resulting difference of 2.5 amps.

Potential annual savings by repairing the loose connection:
            kW = (480 volts x 2.5 x .87 x 1.732) / 1,000 = 10.84
             = 8,760 x 11.21 x $0.08
             = $7,603.15

Opportunity #2: Motor-Driven Systems
In the U.S., motors -driven systems such as pumps, compressors and materials processors (grinders, mixers, crushers, sizers, etc.) consume an average of 63 percent of the electricity in the industrial sector.


Graphic 3. Motor Systems Energy Use by Equipment Type

Graphic 3 identifies how this segment is broken down by energy use, which can provide some prioritization of your energy efforts. There are many opportunities since many sites have to live with low-cost purchasing practices or older, less efficient motors, but there is room for improvement. For example, an older 100 HP motor with low efficiencies (Pre-EPAct of 1992) costs approximately $35,000 per year and $525,000 for 15 years in energy costs. A staggering 95 percent of this motor’s life cycle costs (LCC) is consumed by electrical costs, so reclaiming just a few efficiency points with PdM can add significant savings to your bottom line.

A key ingredient in motor life is the insulation system used in the motor. Aside from vibration, moisture, chemicals, voltage irregularities, dirt and other non-temperature related life-shortening items, the key to insulation and motor life is the maximum temperature that the insulation system experiences and the temperature capabilities of the system components.

Motors can have hundreds of electrical connections that can become loose or faulty. Motors are rated by class for their maximum operating temperature. Temperatures in excess of these maximum ratings will cause damage to insulation on the windings, greatly shorting the life of the motor.

Heat is probably the biggest insulation killer. For example, a rise in temperature of 50 degrees F (10 degrees Celsius) reduces insulation resistance and useful life by 50 percent. Using infrared thermography, your team scans motors, pumps and compressors looking for temperature changes/hot spots among motors, bearings, couplings, etc.

IR Survey: Your team identifies one phase/leg of a fully loaded, 100 hp motor as being 95 degrees F higher than the other two. A thorough investigation is required to determine the root cause such as voltage imbalance.

Troubleshooting Scenario #1 – The hot leg was drawing 45 amps and the others are at 30 amps each. This 15-amp differential is wasting $5,045 annually.

Troubleshooting Scenario #2 – Troubleshooting identifies a voltage imbalance of 466, 458 and 445. A simple voltage balance formula helps us determine that the voltage unbalance is 2.5 percent.


Table 3. Motor Efficiency Under Conditions of Voltage Unbalance

Use the following formula to calculate each of the motor costs at efficiencies of 93 percent and 94.4 percent.

Subtract the two numbers to generate an annual savings of $832.98by working to balance the voltages.

Opportunity #3: Motor-Driven Compressed Air Systems
Compressed air often viewed as the fifth utility, accounts for a significant percent of the energy consumption and can have efficiencies as low as 10 to 20 percent. This opportunity area involves the optimization of motor-driven compressed air systems by eliminating leaks to the atmosphere, reducing demand and run time on compressors. Ultrasound technology picks up sound waves above 20 kilohertz (kHz). This is beyond human hearing. The detector picks up ultrasounds and transposes them into an audible range for the operator who is using a headset device.

Compressed Air Survey: Before you start your leak management program, it is recommended that you determine the best route use a drawing or a simple sketch of the compressed air system. Breaking the system down into inspection zones makes the process more manageable. Start at the compressor (i.e. air end) and work outward. Hang a tag at each leak and update your drawing. Be sure to record the decibel (dB) levels as this will help streamline the work order ranking process later. Also record the instrument used and the number of inches or feet away from the leak when identified. Take a picture of the location.

Look for and tag valves left open, rags over pipes to reduce noise on large leaks, unattended machines left on and blowing air. Check and repair drain traps and don’t leave them cracked open. Check for defective tools and quick connects.

During the survey of your 100 PSIG system, you identify 20 problems equally split between 20 and 30 dB. Use the following shortened look-up decibel and air loss table and calculation to calculate the cfm losses at each decibel level.


Table 4: Example table of decibel (dB) and system pressures (PSIG)

These leaks are wasting $3,096 energy dollars annually.

Opportunity #4: Steam Trap Programs
Within steam systems are two types of leaks – internal when a trap blows through and steam leaking to the atmosphere out of the pipe.

Traps are mechanical valves that return condensate back to the boiler for reuse. Failed traps either fail closed or open. A trap failed in the closed position not only reduces efficiency but prevents return of the condensed water vapor; this can sit and corrode pipe/components. A trap failed in the open position sends steam back to the condensate tank, preventing useful work.

Steam can be a very expensive resource, ranging from $5 to $15 per 1,000 pounds of steam, which includes the boiler fuel costs, labor, water treatment, etc.

Rules of Thumb for Number of Traps Blowing Live Steam

  • 50 percent if no steam trap survey or maintenance program
  • 25 percent with annual program
  • 12 percent with semi-annual program
  • Even newer systems can have failed or failing traps as high as 30 percent within the first three to five years.

Steam Trap Survey: Since you have a wealth of PdM technologies and no capital dollars, your goal is to reduce failed traps to less than 5 percent and fix 75 percent of the piping leaks. During your steam trap survey, perform visual inspections and be on the lookout for the performance of discharge valves, rust/corrosion, hissing, etc. Use the same tagging and documenting technique explained in the compressed air section. Add up all of the losses; multiply the steam loss by hours of operation, steam cost (usually between $5 and $15 per 1,000 pounds) and by the number of failed traps and/or piping leaks. Some facilities can have 500 to 1,000 traps alone!

In this example, ultrasound and thermography identify a failed trap blowing 300 PSI with a 3/16-inch orifice (see the following graphic for an example of how the dual technologies supported a final recommendation). Using the following look-up tables and calculations, you can find the amount of wasted steam and the financial impact.

  • 268 pounds of wasted steam per hour
  • Average cost of $12 per 1,000 pounds of steam
    • $77.02 / day (24 hours)
          • $28,110.82 / year (8,760 hours)
       


Table 5: Steam flow (pounds/hour) through orifices at specific steam pressures:

The U.S. Department of Energy has numerous steam system optimization resources, larger look-up tables and additional calculations supporting the tables.


Graphic 4: Trap blowing through, stuck in the open position. Decibel level on the
steam trap was a constant 52 dB and normal expected level should be in the
20 to 30 dB range when operating. Pressure at trap was 30 PSI.

Closing the Deal
These examples are only scratching the surface as there are many more energy-saving opportunities with additional PdM technologies such as vibration monitoring/alignment strategies, motor circuit and motor current analysis, lube oil analysis/optimization, and aerial infrared surveys for roof moisture saturation.

As mentioned earlier, most organizations have the knowledge but lack the information to make the right decisions in a timely manner. Once you have solid results, your goal is to provide simple communications that gain support for your reliability and energy-saving efforts.

The first recommendation is to have centralized information which is easily accessed, extracted and understood. This can be done in a simple spreadsheet or database or with off-the-shelf packages.

Second, learn how to “blow your own horn” to gain support for your initiatives by publishing a regular savings and energy report. Keep the message simple, be specific in your arguments and have documentation in order to put a scale to the benefits and costs. The message should be financially based and not too technical, with numerous discussions and calculations about gallons, kilowatts and amperages. The medium could be a few PowerPoint slides or a spreadsheet. Always have backup document and calculations that support the savings accumulate and trend the results.

In addition to the energy wasted and now being saved moving forward, calculate the corporate financial benefit such as the cost of downtime avoided.

Good luck.

About the author:
Dale P. Smith, CMRP, is the corporate programs manager with Predictive Service. Dale has more than 18 years of experience within the engineering and reliability consulting industries designing, implementing and running successful multi-site corporate safety, reliability and energy programs for medium, large and Fortune 500 companies.

Predictive Service ( PSC), headquartered in Cleveland, provides a fully integrated mix of predictive maintenance (PdM) technologies and delivers all information via a centralized, Web-based software management system, ViewPoint . PSC helps all types of global corporations ensure reliable, safe and cost effective facility capacity.

For more information, e-mail dsmith@pscorp.com or visit www.predictiveservice.com.

References

1. In preparation for this article, the author collected data from Predictive Service’s ViewPoint database of data collected during reliability field services with a specific search on electrical infrared inspections. This data spanned a cross section of seven industry segments and the following summaries:

Note: facilities averaged shifts of six days per week and 16 hours per day. Electrical average across sites is $0.07 per kWh.

2. For the purposes of this document, most of the energy savings are calculated using electricity as the base (other than steam generation which includes natural gas, water treatment, etc.). Additionally, the approach is in general terms. Numerous additional factors can impact or fine-tune each calculation.

3. U.S. Industrial Motor Systems Market Opportunities Assessment, Xenergy for Oak Ridge National Laboratory and the U.S. Department of Energy, 1998.

4. Energy Use, Loss and Opportunities Analysis, Energetics, Inc and E3M, Inc for the U.S. Department of Energy, November 2004.

5. Motor Planning Kit 2.1: Strategies, Tools and Resources for Developing a Comprehensive Motor Management Plan. Consortium for Energy Efficiency, Inc.

6. Boosting your Bottom Line: Plug into Programs. Lubrication Management & Technology page 6. March / April 2008.


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