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Saving Energy with Bearing Isolators
Saving Energy with Bearing Isolators
David C. Orlowski, Inpro/Seal Company
Non-contacting labyrinth seal bearing isolators for industrial rotating equipment can be a key to energy conservation — and saving money. By changing from contact lip seals to non-contact seals in industrial rotating equipment, the U.S. could save billions of dollars in electrical power costs and conserve over 5,500-MW of energy each year.
38 million contacting lip seals are used in U.S. industrial applications, including pumps, gearboxes, fans, paper machine rolls, and other types of rotating equipment. Each lip seal consumes an average of 147-watts of power and has a 100 percent failure rate.
After approximately 2,000 hours of operation (or 2.7 months), a lip seal will fail, lose contact with the rotating shaft, and stop consuming power. When a lip seal fails, it must be replaced or the rotating equipment will operate until the bearings become contaminated or run out of oil. This is akin to running your car on a flat tire until it self-destructs.
Contacting seals, including magnetic face seals, account for 6000-MW of power consumption — assuming they are functioning and effectively sealing. To add to the problem, industrial electric motors were, for a long time, manufactured and placed into severe duty services without adequate bearing protection. Only a close clearance between the shaft and end-bell served to limit contamination ingress into the bearing environment. Reliability suffered as life cycle costs for energy and maintenance had significant negative impact on the process industries’ production members.
However, some relief has come in the way of industrial electric motors. In 1994, the Institute of Electrical Engineers introduced their IEEE-841 Motor, a unit designed to improve reliability, efficiency, performance, and energy consumption. One year later, a process plant that switched to 2,000 of these new motors discovered $5 million in savings through efficiency and enhanced reliability.
A good deal of the savings in the IEEE-841 comes from its use of non-contact seals, or bearing isolators, as part of its specification.
Invented in the 1970s, the bearing isolator is a non-contacting labyrinth seal, which provides permanent bearing protection and eliminates the need for continual maintenance.(1) The non-contact situation between the unitized rotor and stator result in no consumption of energy. In addition, bearing isolators never wear out, so they can be used over and over for many years.
The IEEE-841 and the NEMA Premium motor both are available with bearing isolators to enhance reliability and reduce MTBF (mean time between failures). Documentation calculates an internal rate of return of more than 100 percent.
Approximately 40 million industrial-grade electric motors are in use in the U.S. On average, these motors will last 5.7 years before they need to be repaired or replaced. The vast majority of the time, the root cause of electric motor failures is mechanical rather than electrical. Pure and simple, bearing-protected motors have proven to last at least twice as long as the motors that they replaced, because the major documented cause of motor failure remains bearing deterioration.
The insulation on the windings could be good for 130 years because it is designed for severe resistive heating that does not present itself in the modern day super efficient motor.
If the 38 million contacting lip seals in the U.S. were replaced with non-contacting, non-energy consuming bearing isolators, the net energy savings in the U.S. would be about 5,586-MW, or the equivalent of 10 fossil fueled power plants.
Tons of carbon dioxide, said to be a major contributor to global warming, would no longer be produced. The economic savings would also be substantial — the process industries would save over $3.7 billion per year in electrical power costs. Bearing isolators have been known to stay in service for at least 20 years, eliminating the duty cycle and replacement expense and stabilizing operating costs. The benefits would be innumerable.
Expert troubleshooters have a good understanding of the operation of electrical components that are used in circuits they are familiar with, and even ones they are not. They use a system or approach that allows them to logically and systematically analyze a circuit and determine exactly what is wrong. They also understand and effectively use tools such as prints, diagrams and test instruments to identify defective components. Finally, they have had the opportunity to develop and refine their troubleshooting skills.
Expert troubleshooters have a good understanding of the operation of electrical components that are used in circuits they are familiar with, and even ones they are not. They use a system or approach that allows them to logically and systematically analyze a circuit and determine exactly what is wrong. They also understand and effectively use tools such as prints, diagrams and test instruments to identify defective components. Finally, they have had the opportunity to develop and refine their troubleshooting skills.
Semiconductor devices are almost always part of a larger, more complex piece of electronic equipment. These devices operate in concert with other circuit elements and are subject to system, subsystem and environmental influences. When equipment fails in the field or on the shop floor, technicians usually begin their evaluations with the unit's smallest, most easily replaceable module or subsystem. The subsystem is then sent to a lab, where technicians troubleshoot the problem to an individual component, which is then removed--often with less-than-controlled thermal, mechanical and electrical stresses--and submitted to a laboratory for analysis. Although this isn't the optimal failure analysis path, it is generally what actually happens.
Semiconductor devices are almost always part of a larger, more complex piece of electronic equipment. These devices operate in concert with other circuit elements and are subject to system, subsystem and environmental influences. When equipment fails in the field or on the shop floor, technicians usually begin their evaluations with the unit's smallest, most easily replaceable module or subsystem. The subsystem is then sent to a lab, where technicians troubleshoot the problem to an individual component, which is then removed--often with less-than-controlled thermal, mechanical and electrical stresses--and submitted to a laboratory for analysis. Although this isn't the optimal failure analysis path, it is generally what actually happens.
In an ideal world, multiple components could be produced in a single piece, or coupled and installed in perfect alignment. However, in the real world, separate components must be brought together and connected onsite. Couplings are required to transmit rotational forces (torque) between two lengths of shaft, and despite the most rigorous attempts, alignment is never perfect. To maximize the life of components such as bearings and shafts, flexibility must be built in to absorb the residual misalignment that remains after all possible adjustments are made. Proper lubrication of couplings is critical to their performance.
In an ideal world, multiple components could be produced in a single piece, or coupled and installed in perfect alignment. However, in the real world, separate components must be brought together and connected onsite. Couplings are required to transmit rotational forces (torque) between two lengths of shaft, and despite the most rigorous attempts, alignment is never perfect. To maximize the life of components such as bearings and shafts, flexibility must be built in to absorb the residual misalignment that remains after all possible adjustments are made. Proper lubrication of couplings is critical to their performance.
The key to realizing greater savings from more informed management decisions is to predetermine the "True" cost of downtime for each profit center category. True downtime cost is a methodology of analyzing all cost factors associated with downtime, and using this information for cost justification and day to day management decisions. Most likely, this data is already being collected in your facility, and need only be consolidated and organized according to the true downtime cost guidelines.
The key to realizing greater savings from more informed management decisions is to predetermine the "True" cost of downtime for each profit center category. True downtime cost is a methodology of analyzing all cost factors associated with downtime, and using this information for cost justification and day to day management decisions. Most likely, this data is already being collected in your facility, and need only be consolidated and organized according to the true downtime cost guidelines.
I use the term RCPE because it is a waste of good initiatives and time to only find the root cause of a problem, but not fixing it. I like to use the word problem; a more common terminology is Root Cause Failure Analysis (RCFA), instead of failure because the word failure often leads to a focus on equipment and maintenance. The word problem includes all operational, quality, speed, high costs and other losses. To eliminate problems is a joint responsibility between operations, maintenance and engineering.
I use the term RCPE because it is a waste of good initiatives and time to only find the root cause of a problem, but not fixing it. I like to use the word problem; a more common terminology is Root Cause Failure Analysis (RCFA), instead of failure because the word failure often leads to a focus on equipment and maintenance. The word problem includes all operational, quality, speed, high costs and other losses. To eliminate problems is a joint responsibility between operations, maintenance and engineering.
The potential-to-functional failure interval (P-F interval) is one of the most important concepts when it comes to performing Reliability-Centered Maintenance (RCM). Remarkably, the P-F interval is also one of the most misunderstood RCM concepts. The failure mode analysis becomes even more complicated when you are dealing with several P-F intervals for one failure mode. This paper will help clarify the P-F interval and the decision-making process when dealing with multiple P-F intervals.
The potential-to-functional failure interval (P-F interval) is one of the most important concepts when it comes to performing Reliability-Centered Maintenance (RCM). Remarkably, the P-F interval is also one of the most misunderstood RCM concepts. The failure mode analysis becomes even more complicated when you are dealing with several P-F intervals for one failure mode. This paper will help clarify the P-F interval and the decision-making process when dealing with multiple P-F intervals.
As many of us strive to improve the reliability of our plants, several comments bemoan how challenging that is to do in an era of continuous deep cost cutting. They say that in their operation, maintenance is seen as a cost, and is one of the first things to arbitrarily cut. Some think their operations have cut too far! What they seek is a way to justify a strong maintenance capability. I submit that one approach is to speak of maintenance as an “investment in capacity.” Use the language that plant managers, controllers and senior management understands: capital investment and return on investment (ROI).
As many of us strive to improve the reliability of our plants, several comments bemoan how challenging that is to do in an era of continuous deep cost cutting. They say that in their operation, maintenance is seen as a cost, and is one of the first things to arbitrarily cut. Some think their operations have cut too far! What they seek is a way to justify a strong maintenance capability. I submit that one approach is to speak of maintenance as an “investment in capacity.” Use the language that plant managers, controllers and senior management understands: capital investment and return on investment (ROI).