Turbomachinery and Pump Symposia

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http://hdl.handle.net/1969.1/158832

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Browsing Turbomachinery and Pump Symposia by Author "Adachi, Akira"

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    Overcoming Failure of Synchronous Motor Driven Compressor Train by Application of Controlled Slip Clutch
    (Turbomachinery Laboratory, Texas A&M Engineering Experiment Station, 2020) Adachi, Akira; Oba, Sho
    This case study describes failure incident of a centrifugal compressor, its root cause investigation, and countermeasure implementation. An integrally geared centrifugal air compressor driven by a synchronous motor failed during its initial startup in a newly constructed petrochemical plant. Failure mechanism was identified as torsional resonance during synchronous motor’s startup with stronger torque amplification than the design intention. As a quick yet very effective solution to this problem, a clutch with controlled slip mechanism was applied. Torsional analysis reflecting the clutch mechanism as well as on-site strain gauge measurement verified its effectiveness. After implementation of this clutch, no malfunction or abnormality has been observed in the compressor train.
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    Prediction Of Lateral Vibration Behavior Of Integrally Geared Centrifugal Compressor During Synchronous Motor Startup By Transient Torsional-Lateral Coupled Analysis
    (Turbomachinery Laboratory, Texas A&M Engineering Experiment Station, 2022) Adachi, Akira; Baba, Yoshitaka
    Startup transients of both torsional and lateral vibration behaviors of an integrally geared centrifugal compressor driven by a synchronous motor are examined by transient torsional-lateral coupled analyses, and the numerical calculation results are evaluated using the field measurements as a benchmark. Since linear bearing coefficients are employed in the numerical simulation instead of more sophisticated nonlinear bearing model, bilinear stiffness is additionally considered to reflect the effects of the rotor confinement within the bearing clearance. Moreover, temporary teeth separation of the gear meshing and engagement at the backside during torque reversal is also considered in the numerical calculation. The transient lateral vibration behavior of the pinion rotor during the synchronous motor’s startup is successfully replicated. Both (a) bilinear stiffness of the pinion rotor bearings due to rotor restraint within the bearing clearance, and (b) effect of temporary teeth separation within the backlash and engagement at the backside because of torque reversal, are found to strongly influence the numerical predictions.
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    Torsional Instability Of Cooling Tower Fan During Induction Motor Startup
    (Turbomachinery Laboratories, Texas A&M Engineering Experiment Station, 2016) Adachi, Akira; Murphy, Brian; Turbomachinery Symposium (45th : 2016)
    Torsional instability during starting of an induction motor has caused excessive torque oscillation and eventual failure of gearbox pinion teeth of a cooling tower fan train. A torsional instability appeared due to a steep slope of the induction motor starting torque curve, combined with a torsionally soft driveshaft and a large moment of inertia of the driven fan. In this paper, mechanisms of torsional instability occurrence during startup of an induction motor in a cooling tower fan train are discussed, as well as details of the investigation outcomes of troubleshooting activities, including field measurements. The methods of modeling and analysis are also described. To examine the mechanism of torsional instability occurrence, in addition to transient torsional analysis, the concept of torsional stability analysis is introduced. Practical engineering guidelines to avoid this type of problem, such as a motor selection guideline, are also addressed.
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    Torsional-Lateral Coupled Vibration Of Centrifugal Compressor System At Interharmonic Frequencies Related To Control Loop Frequencies In Voltage Source Inverter.
    (Texas A&M University. Turbomachinery Laboratories, 2009) Tanaka, Kenji; Adachi, Akira; Takahashi, Naohiko; Fukushima, Yasuo; Turbomachinery Symposium (38th : 2009)
    Centrifugal compressor train in a refinery experienced high vibration problem due to torsional resonance. Sidebands in the VFD output current based on VFD control loop frequencies were identified as the root cause. In this VFD, stator current was used for torque and speed control, hence control loop frequencies had a potential to generate such sidebands. Frequencies of this type of sidebands widely vary with the rotation speed (proportional to harmonics of the fundamental frequency), hence it is difficult to avoid resonance at the train torsional natural frequency. In addition, even if a compressor system is proven to have sufficient safety margin against high cycle fatigue failure due to the torque pulsation by this mechanism, such minute torque pulsation may have a potential to excite high lateral vibration at speed adjusting gear. If unpredicted or overlooked during design stage, such high vibration may disturb plant operation. This case study therefore proposes guidelines to predict such vibration levels by a simplified torsional-lateral coupled vibration analysis.
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    Troubleshooting Rotary Blower Recurring Failures in Vacuum Pump Application through Visualization of ODS, Mode Shapes and Pipe External Force Effect
    (Turbomachinery Laboratory, Texas A&M Engineering Experiment Station, 2023) Adachi, Akira; Chimura, Isaku
    A rotary blower (three-lobed roots blower) in vacuum pump application had been repeatedly failing due to high vibrations occurring at 46.6 Hz (lobe pass frequency at 3x shaft rotational speed) and 93.2 Hz (pocket pass frequency at 6x shaft rotational speed)
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    Troubleshooting Rotary Blower Recurring Failures in Vacuum Pump Application through Visualization of ODS, Mode Shapes and Pipe External Force Effect
    (Turbomachinery Laboratory, Texas A&M Engineering Experiment Station, 2023) Adachi, Akira; Chimura, Isaku
    A rotary blower (three-lobed roots blower) in vacuum pump application had been repeatedly failing due to high vibrations occurring at 46.6 Hz (lobe pass frequency at 3x shaft rotational speed) and 93.2 Hz (pocket pass frequency at 6x shaft rotational speed)
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    Troubleshooting Rotary Blower Recurring Failures in Vacuum Pump Application through Visualization of ODS, Mode Shapes and Pipe External Force Effect
    (Turbomachinery Laboratory, Texas A&M Engineering Experiment Station, 2023) Adachi, Akira; Chimura, Isaku
    A rotary blower (three-lobed roots blower) in vacuum pump application had been repeatedly failing due to high vibrations occurring at 46.6 Hz (lobe pass frequency at 3x shaft rotational speed) and 93.2 Hz (pocket pass frequency at 6x shaft rotational speed)