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Multidisciplinary Senior Design ConferenceKate Gleason College of Engineering

Rochester Institute of TechnologyRochester, New York 14623

Project Number: P14453

DRESSER RAND COMPRESSOR BEARING SIMILARITY TEST STAND

Steven LucchesiTeam Leader

Mechanical Engineering

Joshua PlumeauLead Engineer


Luke TrapaniLubrication Engineer


Shawn AveryTeam Facilitator


Steven KaiserProject Engineer


ABSTRACT (Kaiser reviewed)A journal bearing consists of a shaft or journal which rotates freely in a supporting sleeve with lubricant film to provide a low friction surface and is designed for high load-carrying capacity. These bearings are found in many modern rotating equipment solutions for applications in the oil, gas, power, and other industries worldwide. Given their need to handle large dynamic load profiles over long periods of time, active monitoring of the bearing allows us to extend its life expectancy. Isolated data collected from active bearings can be used to apply fault detection methods allowing for the prediction of bearing failure. Dresser Rand, a global supplier of custom-engineered rotating equipment solutions, is supporting faculty and students at the Rochester Institute of Technology (RIT) in the development of a test apparatus that will better assist in the improvement of fault detection methods by isolating the bearing from a reciprocating compressor while simulating active conditions. The objective of this project revolves around the design, validation, and Phase I build of such an apparatus to be used for research initiatives at RIT. The primary customer, Dr. Jason Koldziej, Assistant Professor of Mechanical Engineering at RIT, specified an initial list of needs which were translated in to engineering specifications. In order to ensure efficient completion of all project goals primary responsibilities were delegated to individual team members and the overall scope of the project was divided into various design, build, test, and integration phases. This paper outlines, in detail, the individual systems and phase I build of the test apparatus as well as the phase break down of the project.

Copyright © 2014 Rochester Institute of Technology

Proceedings of the Multi-Disciplinary Senior Design Conference

TABLE OF CONTENT

SABSTRACT...................................................................................................................................................................1

NOMENCLATURE (If Needed?)................................................................................................................................2

BACKGROUND............................................................................................................................................................2

DESIGN PROCESS.....................................................................................................................................................3

Needs & Specifications...........................................................................................................................................3

System Architecture.................................................................................................................................................3

Test Bearing & Housing Design.............................................................................................................................4

Lubrication System Design.....................................................................................................................................5

Drive System Design...............................................................................................................................................5

Load Application System Design...........................................................................................................................5

Structural Support System Design........................................................................................................................6

BUILD & INTEGRATION PROCESS........................................................................................................................6

Structural Support System Manufacturing & Assembly.....................................................................................6

Drive System Manufacturing & Assembly............................................................................................................6

Load Application System Manufacturing & Assembly........................................................................................7

Lubrication System Manufacturing & Assembly..................................................................................................7

Test Bearing & Housing Manufacturing & Assembly..........................................................................................7

RESULTS & DISCUSSION........................................................................................................................................8

CONCLUSION & RECOMMENDATIONS...............................................................................................................8

REFERENCES.............................................................................................................................................................8

ACKNOWLEDGMENTS..............................................................................................................................................8

LIST OF FIGURES (need to update to reflect new figures)Figure 1: Dresser Rand Reciprocating Compressor Test Cell........................................................................................2Figure 2: ESH-1 Dynamic Load Profiles........................................................................................................................3Figure 3: Functional Decomposition of Systems............................................................................................................4Figure 4: Journal Bearing Test Rig System Architecture...............................................................................................6Figure 5: Test Bearing & Housing Cross-Section View.................................................................................................6

NOMENCLATURE (If Needed?)

BACKGROUND (Kaiser reviewed)Dresser Rand is a multinational corporation and global supplier of custom-engineered rotating equipment solutions. With headquarters in Houston, Texas and Paris, France, they provide products which assist applications in the oil, gas, process, power, and other industries worldwide.

In 2011, Dresser Rand donated an ESH-1 reciprocating compressor to RIT to but be used for undergraduate study, and graduate/faculty research in the areas of measurement and controls, and fault detection. Since the installation of the compressor, several RIT Multidisciplinary Senior Design Projects have revolved around the monitoring and improvement of the machines performance.

Copyright © 2014 Rochester Institute of TechnologyFigure 1: Dresser Rand

Reciprocating Compressor Test Cell


The overall objective of this project is to develop a bearing dynamic similarity test machine to more carefully investigate the dynamics of the Dresser-Rand floating ring main compressor bearings. This test apparatus will better assist in the improvement of fault detection methods by isolating the vibrational characteristics of the bearings from that in the overall machine. Currently, there are general bearing test rigs on the market that demonstrate some, but not all, of the desired characteristics, however, none are readily available to either RIT or Dresser-Rand.

Phase one of this this project includes the development of customer needs, engineering requirements, solution exploration, and static loading concept validation. The end goal of phase one is to have a fully functional journal bearing test stand which replicates the Dresser Rand ESH-1 reciprocating compressor in terms of lubrication specifications, rotational speed, and maximum load requirements. It will use a mechanically static loading system to achieve maximum radial load on the test bearing which has been designed for quick change out when compared to the ESH-1 in the lab.

DESIGN PROCESS

Needs & SpecificationsIn order to replicate the bearing dynamics of the ESH-1, a load application system must first be selected to represent the periodic time histories of the main bearing loads, as seen in Figure 2. Since journal bearings operate with pressurized oil, a lubrication system which closely resembles that of the ESH-1 in terms of flow rate pressure at the bearing must also be designed. With these two systems in place, the rest of the apparatus may be designed to support the operation of the similarity systems and facilitate monitoring and interface requirements.

Monitoring requirements ensure that the rig will allow for diagnostic and prognostic analysis while control requirements ensure that the rig will accurately replicate different compressor use scenarios, as well as any other test scenarios that may arise in the future. These requirements, which were provided by the customer and revised by the design team, are as follows:

Control shaft speed (360 RPM minimum, 2,000 RPM desired) Control radial load to the bearing (Max load of 2,000 Lbf) Monitor shaft rotational speed Monitor oil flow rate Monitor oil pressure at the bearing Monitor bearing vibration

One of the advantages of dynamic similarity systems is being able to more easily view and disassemble components that may otherwise be difficult to gain access to on the product itself. In the case of the ESH-1, it takes an experienced technician a full day’s work to access the main crankshaft bearing for replacement. As such, one of the key objectives for this project is to allow quick bearing change out with relative ease.

Concept Generation (MOVE TO AFTER SYSTEM ARCHITECTURE)Before major design work was begun, an overall design concept had to be created. Using a functional decomposition, the parameters that the rig had to achieve were laid out graphically. From this point, the critical subsystems were identified for further analysis.


Figure 2: ESH-1 Dynamic Load Profiles


Figure 3: Functional Decomposition of Systems

Once the subsystems had been identified, each was approached individually. A bevy of ideas for how to handle each system was brainstormed and added to a list. This list was then used to create a morphological chart, which visually displayed each proposed solution. From the morphological chart, full system concepts were created by combining the many options for each subsystem. These concepts were each sketched and then analyzed. The strongest of them were selected for further review.

Add Figures Below?



These concepts were then analyzed using a Pugh chart, which rates them in numerous categories based upon their ability to meet specific requirements. After the completing the initial Pugh chart, it became clear that further concept generation was required in order to arrive at the best possible engineered solution. After a second round of concept generation, in which two ‘hybrid’ concepts were created from previous ideas, a Pugh analysis was again performed, and a final concept was selected.

Once a concept had been selected, significant research was performed in order to identify how to bring the concept to life. Through this research, including discussions with faculty and equipment suppliers, it was determined that Electro-hydraulic Actuators would not be able to capable of performing the task of loading and unloading the system at with the force and level of accuracy that the system required. The focus then shifted to other forms of loading, and Piezo-electric actuators were chosen due to their ability to provide high loads as very high frequencies. This concept also failed when it was realized that the most affordable piezo-electric system was priced at over $20,000, well above the $5,000 budget for the entire process.

Due to the significant issues related to dynamically loading the test bearing, it was determined after the final design review that a static load system would be utilized for the first iteration of this test stand. The static load system allows the equipment to be tested for failures of structural components up to full load criteria, while being much more affordable to integrate. The rest of the design remained unchanged, such that follow on (future) projects will be able to adapt dynamic load systems to the test rig without undue difficulty.

System ArchitectureThe entire dynamic system can be divided into six major subsystems in order to ensure each of the above requirements is met and to allow independent development and testing among the design team. This approach allows for subsystem problems to be encountered and solved prior to the final assembly. The six subsystems are as follows:

1. Load Application System2. Lubrication System3. Drive System4. Structural Support System5. Power System6. Data Acquisition System



The six subsystems interact to achieve the overall system goals. This interaction is outlined below in Figure 3, but the method in which they interact is dependent upon concept selection and component design.

Figure 4: Journal Bearing Test Rig System Architecture

Test Bearing & Housing Design (josh reviewed)The test bearing is a close replica of the ESH-1 main crankshaft bearing in terms of geometry, however, a joint decision was to made between the team and the customer to use a typical journal bearing as opposed to a floating-ring journal bearing in order to simplify the design. A floating ring journal bearing is similar to a standard journal bearing but consists of an additional component (the ring) that floats in the lubricant between the journal and the sleeve creating two lubricant layers. This will not affect any of the other systems since the two styles of bearing are interchangeable.

The bearing was designed to maintain a minimum film thickness based on the maximum load requirement. This analysis resulted in an acceptable range of design clearances from 5µm to 50µm. The bearing was custom manufactured by Bunting Bearing Corp. and is made of C93200 Brass. It consists of two lands separated by an oil groove with an oil feed port as seen in Figure 4. The overall dimensions include a length of 2.75 inches and an outer diameter of approximately 3.129 inches.

The test bearing housing is a single piece seamless housing with three critical features the first of which houses the bearing, the second of which provide two oil exhaust chambers and the third of which allows the installation of two SKF oil seals. Oil is fed through the top of the bearing to the oil port located in the test bearing. Oil is then allowed to flow out either end of the bearing to the oil exhaust chambers where it enters one of two return lines. The oil seals ensure that the return oil will remain contained during operation. In addition, the housing consists of a threaded hole which

allows the load application system to be coupled with the test bearing.


Figure 5: Test Bearing & Housing Cross-Section View


Lubrication System Design

Drive System Design

The drive system for the test rig consists of four major components: an electric motor, a stee l test shaft, shaft support bearings, and a coupling that connects the motor output shaft with the test shaft. Motor selection was based on the criteria of accuracy of shaft speed at low rpm, high torque capability, minimal controls for increased usability, and ease of implementation into the test rig and test lab. To meet these criteria, an electric DC motor was chosen. The motor itself is a Leeson 1/2 HP DC motor with a max speed of 1750 RPM, more than suitable for the 360 RPM operating speed and project requirements. The motor is controlled by a Dart MD10P speed controller. A PhotoCraft encoder is attached to the opposite end of the shaft to provide accurate speed measurement and control.

When designing the test shaft a higher grade steel, AISI 4140 alloy, was chosen for the primary reason that is the same steel that Dresser Rand uses for its manufactured crankshafts. This steel is a harder alloy that has minimal deflection under high dynamic load. The high hardness value also makes the material more suitable for surface grinding, increasing manufacturability. The test shaft also features a step design which was done to reduce the size and cost of the shaft support bearings as well as providing a smaller diameter shaft to insert into the motor-to-test-shaft coupling.

Connecting the motor to the shaft required a coupling of some sort. The coupling is a R+W Bellows coupling with a diameter of 0.625” for the motor and 1”” for the shaft, respectively. This coupling is flexible in that in allows for a 25mm max lateral deflection. This flexibility was desirable to account for any misalignment that could occur between the motor output shaft and test shaft during the assembly or test phases of the manufacturing process. The coupling also has a claimed “zero” rotational slack which will be beneficial for future iterations of the test rig that may feature dynamic loading.

To ensure that the shaft would rotate with minimal resistance, two high grade spherical roller bearings were chosen to support the shaft. These two bearings are of a two piece split housing design, which allows for quicker disassembly and test shaft removal by eliminating the need to remove the bearing base from the bearing risers and test table surface when the test bearing needs to be changed out. The support bearing on the far end of the shaft is an expansion bearing to allow for any potential shaft walk. The bearing closest to the motor is a non-expansion type in order to protect the electric motor and increase the life of the coupling. The inner diameter is 2” which is reflected in a step down from the test bearing size. Due to the design of the test bearing housing, risers were needed to align the


Figure 5: Drive system: including motor, coupler, shaft, and support bearings


support bearings with the test shaft and test bearing assembly. Again speaking to alignment issues, the risers were designed to be ground for flatness.

Load Application System DesignThe objective of the loading system on the journal bearing test rig is to replicate the loads seen by the crankshaft main bearings. This requires that the system be capable of loading and unloading the test bearing in two axes at a minimum of six Hertz with loads up to 2000 lb-f. Due to budgetary constraints, this was not possible in phase one of the project. Because of this constraint, the current loading system has been implemented with two main goals: first, that the applied load replicate the maximum load seen by the compressor crankshaft, thereby proving the ruggedness of the design, and second, that the current system be low cost and have low impact to the testing equipment due to installation so that it can easily be replaced in a follow-on project.

The chosen system is static, using weight plates and a lever arm to provide load. Mounted to the underside of the test surface, the lever arm is designed to load the bottom of the test bearing enclosure, pressing it against the bottom of the shaft. The load point on the lever is three inches from the pivot point on the lever arm, while the supported mass, which creates the load, is suspended off the side of the table 30 inches from the pivot point, allowing for a 10:1 ratio on the lever arm. The load is transferred through a pivot point at the end of the lever, through a load cell, and into the bottom of the test bearing block. The load cell allows the operator to actively monitor the load on the

bearing. To change the load on the bearing assembly, the operator must simply add or remove weight plates until the desired value is reached. Each plate is slotted and slips over a weight strap which is suspended below the end of the lever. Because the system is static, no fasteners are required to hold the weight plates in place. In order to make test setup as simple as possible, a locking pin has been included in the system. This locking pin holds the lever in a fixed position so that the system can be set up and adjusted without having to worry about accidentally applying an unwanted load to the bearing and shaft assembly.


Figure 6: Load System


Structural Support System Design (josh reviewed)

The structural support system consists of the table base and table test surface. It was determined that the table test surface to be made of a strong structural steel and be ground for flatness. The test surface is a one inch thick Blanchard ground plate made of A36 steel, common carbon steel used for structural applications. The material was chosen in order to minimize table deflection under high static load or future dynamic loading. The Blanchard grinding is important for surface flatness as the tolerances within the test bearing are small enough that flat mounting surfaces become crucial for aligning all of the drive system componentry. When designing the layout for the static loading test rig, space on the table was taken into account for a next iteration that will include two axes dynamic loading. The table base is made of three inch by three inch steel tubing welded together. The feet and table mounting pads are 0.375 inch steel plate, with the table surface being bolted down onto the four upper pads, which are tapped to accept 1/2-13 bolts. This feature allows the table top to be removed for

modification. The feet have drilled holes to allow the table to be bolted in place during testing.


Figure 7: Load System. Note the lever and

mounting hardware, Futek load cell, and test

bearing block


BUILD & INTEGRATION PROCESS

Structural Support System Manufacturing & Assembly (josh reviewed)The structural support system consists of the table test surface and table base and designates phase one of the assembly process as it supports all additional componentry for the test rig. The test surface came Blanchard ground at 0.002”/ft spec flatness at a size of 36” by 28.25” with a 1” thickness directly from the manufacturer, Nifty Bar. Due to the number of holes to be drilled and the amount of time necessary for those manufacturing steps, as well as the sheer size of the test table surface, it was determined that machining the piece by hand was simply not feasible.. All of the holes were made using a water-jet machine and later tapped per drawing specs by hand. Due to the importance of the drive system alignment, the water-jet method added another layer of accuracy to the machining process.

The table base was constructed using 3”x3” steel tube stock. The stock was precut to length and welded by a senior lab technician in the machine shop. Welding preparation consisted of sanding all necessary edges and cleaning all the stock of surface oil. Once welded, four holes were drilled in the top of the four table legs (one hole in each leg) for mounting the table base to the test surface. The table base stands roughly three feet high, which is a suitable height for operator access and parts removal or repair. All of the securing bolts were torqued to specification per the assembly instructions.

Drive System Manufacturing & Assembly (josh reviewed)The first component of the drive system to be assembled to the test surface was the DC electric motor. An anti-vibration mat was knife cut to size out of a piece of stock and placed between the motor and test surface to reduce potential overall system vibrations created by the motor during operation. The motor is secured to the test surface with four bolts, all torqued to spec per the assembly instructions. With regards to the electrical connections, the motor was hard wired into the DART motor controller, which was then plugged directly into a wall outlet. All of the securing bolts were torqued to specification per the assembly instructions.

By far the most complex component of the drive system and one of the most critical pieces in the entire system is the test shaft, made of AISI 4140 alloy steel. It was machined and ground by one of the senior lab technicians in the machine shop. The test bearing surface of the shaft was ground to a tolerance design specs of 7.5 microns, which equates to 0.000295 inches. The shaft also had steps machined onto it for fitment of the shaft support bearings, the motor to shaft coupling, and the shaft encoder. The final machined shaft has a finished weight of 36 pounds. The shaft was assembled with the support bearings and test bearing assembly and bolted to the support bearing risers. All of the securing bolts were torqued to specification per the assembly instructions.

The other critical component of the drive system is the matched set of bearing support risers. These are 1018 steel pieces, which were first cut to dimensions of 15” by 2.75” and then ground to a thickness of 0.880’. The next step in the manufacturing process consisted of drilling four holes which were then countersunk. The two smaller holes connect the support bearing to the riser and are tapped to a specification of 5/8 -18 UNF. The two larger holes connect the riser to the test table surface and are thru holes dimensioned to 0.781” to allow for clearance on a ¾ inch bolt.

In addition to the structural members of the drive system, a shaft encoder locating tab was fabricated. This sheet metal tab prevents the shaft encoder from spinning with the shaft. It was made from scrap aluminum sheet and drilled to mount using the support bearing hardware. It features one 90 degree bend with a hole drilled for a bolt between the encoder and the locating tab.

The final assembly steps for the drive system involved attaching the encoder to the 0.375 inch step on the shaft, bolting the encoder locating tab to the far support bearing riser, and connecting the motor output shaft to the one inch step on the shaft with the R+W coupling. The encoder is secured to the shaft with two set screws as well as being bolted to the locating tab, which is secured to the bearing riser with two bolts. The coupling is secured with four Allen screws. All of the securing bolts were torqued to spec per the assembly instructions.


Figure 8: Table Base and Table


Load Application System Manufacturing & AssemblyBecause the load system is static, the parts that constitute it are relatively straightforward. The base of the system is the matched pair of 1018 steel pivot pin mounts that locate the pivot pin for the lever arm. These plates are each bolted to the underside of the table, suspended vertically under the test bearing housing by a pair of 9/16-18 bolts. Their purpose is to provide a pair of holes in which the pivot pin rides. These holes were both drilled with locational accuracy of less than 0.001 inch, and then reamed to a final diameter of 0.500 in order to achieve the best possible finish.

The pivot pin itself is, which rides in the holes mentioned above, is machined of 1018 steel. It is a simple steel pin that was turned on a lathe to a final diameter of 0.499 inches, 0.001 inch smaller than the holes it rides in. On each end of the pin, a cross drilled hole was added. These two holes allow cotter pins to be used to fix the pivot pin in place in the rig.

The pivot pin is used as the fulcrum point for the lever arm. The lever arm itself is a one inch by two inch by 35 inch bar of 1018 hot rolled steel. The only external dimension that has been modified from its as purchased dimensions is the length, which was shortened. The pivot pin hole was drilled and reamed in a process matching that used on the pivot pin locating plates. From this point, a distance of three inches away, a hole was drilled for the load pin. The lever then had a slot milled through it so that the adjustment screw could be installed and adjusted in the load pin. At the other end of the lever, another hole was added in order to bolt on the weight strap support chains. Further, a recess was cut to allow for clearance on the chain links.

The load pin is a ¾ inch diameter pin, one inch long, which was turned on the lathe. Using a knee mill, a cross drilled and tapped 5/16-24 hole was then added. This hole will accept the 5/16-24 by two inch load connector set screw. The other end of the set screw threads into the lever to bearing connector. The connector is a 3/4 inch diameter shaft four inches long which had a threaded hole drilled into one end, which will accept the connector set screw. The other end had a ½ inch long stud turned onto it in the lathe. This stud threads into the load cell, which then threads into the bearing sleeve enclosure.

At the other end of the system, a pair of three link chain sections is suspended. These sections were cut from a length of chain with 0.39 inch diameter links using a hacksaw. At the other end of the chain, a weight strap is bolted. The weight strap is an eighteen inch long piece of one inch wide, 3/8 inch thick piece of 1018 steel with a through hole at each end. One end is bolted to the chain sections, while the other end has a through bolt upon which the weight plates will sit. The weight plates themselves are simply round sections of steel plate of various diameters and thicknesses. Each has a slot cut roughly 3/5 of the way through, a little over 3/8 inch wide, in order to allow it to sit on the weight strap.

The final part of the load application is the locking pin and locking pin tabs. The locking pin itself is a ½ inch diameter clevis pin with a reusable cotter pin, a purchased item. It is held in place by a pair of locating tabs. Each locating tab is made from two inch by two inch steel angle, three inches long. Each has two through holes for ½ diameter bolts drilled into one face. These holes are used to bolt it to the stand. On the other face of each tab is a single hole 9/16 inch in diameter in order to accept the aforementioned clevis pin.

Lubrication System Manufacturing & Assembly

Test Bearing & Housing Manufacturing & Assembly (josh reviewed)The sleeve enclosure locates the bearing on the shaft, allows the load to be applied, and helps to feed oil to and evacuate oil from the test bearing. Machining it was a multi-step process. As received, it was a 6.25 by 6.25 by 6



inch block of 1018 steel. In order to prepare it for final machining, it was first squared in a knee mill. Each of its six faces was machined with a shell mill in order to quickly bring it down to within 0.010” of its final dimensions on each side, with emphasis on ensuring that opposite sides were parallel and all edges formed 90 degree angles. Once this was complete, it was ground on all faces to create an acceptable surface finish with tight parallelism and rectangularity.

With the block prepared, it was then fixtured in a lathe with a four jaw chuck. The center thru hole was then drilled. Using a boring bar, it was then opened up to correct size for the bearing to be pressed in. In addition, the counter bore for the oil drain system and the oil seal were added. The block was then flipped and re-fixtured in the lathe so that the counter bores could be added to the other side. By performing these steps in the lathe, the bearing hole was produced with a high quality surface finish perpendicular to the face of the block.

With the main thru hole finished, the oil feed and drain holes and the load application hole were then added. These were done in a knee mill, with the oil feed hole first being drilled, then drilled with an end mill to ensure accuracy. The block was subsequently flipped so that the oil drain holes and load application hole could be drilled. Once all holes were added, each was tapped, the oil feed hole with a 1 1/8-12 tap and the drain holes with a ¾-16 tap in order to properly interface with the oil lines. The load application hole was tapped to 3/8-24. The load cell threads into this hole and is the link between this system and the load application system.

The test bearing was ordered to specification and required no modification before installation. It was pressed into the test bearing enclosure. An oil seal was then pressed into each side of the bearing, bottoming each on the counter bore for the oil drain. All oil lines were threaded in using Teflon tape on the threads to ensure a good seal. Finally, the Futek load cell was threaded in to the load application hole in order to connect the test bearing assembly to the load system.

RESULTS & DISCUSSION

CONCLUSION & RECOMMENDATIONS

REFERENCES

ACKNOWLEDGMENTSTeam P14453 would like to sincerely thank the following people and organizations for their generous contributions to our project.

Dr. Jason Kolodziej – RIT William Nowak – Xerox & RIT Rob Kraynik - RIT Jan Maneti - RIT Scott Delmotte – Dresser Rand Dresser Rand Corporation


abstract (kaiser reviewed)edge.rit.edu/content/p14453/public/msd ii/technical paper... · web viewa...

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