Case Studies

Analysis & Engineering Upgrades Solve Ring Section Pump Failure

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A major power plant in the United States experienced high vibration and recirculation issues with several ring section (BB4) boiler feed pumps, resulting in multiple catastrophic failures and unplanned outages. This case study details one of the pumps that was shipped to an aftermarket pump service center for a full analysis, troubleshooting, repair plan, rebuild and performance testing.

In combined-cycle plants, the demand for robust, yet expensive, barrel pumps diminished as the industry moved toward less expensive segmental rings pumps. Due to the recent shifts in the power industry, operators often face a shorter mean time between repair (MTBR), internal wear and high vibration issues on newly installed units.

After experiencing numerous boiler feed pump performance and reliability issues at their power plant, the plant owner opted to pursue a comprehensive root cause analysis and repair plan with an aftermarket pump service center in Los Angeles, California. The investigation ultimately revealed a series of underlying issues linked to the performance problems and unexpected pump failures.

Video: https://vimeo.com/452266877

Source: https://www.pumpsandsystems.com/analysis-engineering-upgrades-solve-ring-section-pump-failure

diagram, engineering drawing

Wireless Sensor Data Integration Into Existing Plant Historian

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A large American energy company wanted a new data collection system to be integrated into its site historian along with process trending software to better diagnose system-related issues that can lead to maintenance issues.

Thanks to the help of an aftermarket service company, the energy company combined multiple sources of data and can now view complex mechanical vibration phenomena in parallel with plant process data. By comparing the two sets of data side by side, plant personnel will correlate process conditions with mechanical vibration data.

The service provider’s history of pump and rotating equipment knowledge helped to provide actionable analysis of pumps and other rotating equipment health—and a mechanism to provide additional engineering solutions to complex problems. Combined with the energy company’s focus on reliability and a history of maintaining their equipment, this system provided an improved method of data collection and analysis.

Source: https://www.pumpsandsystems.com/wireless-sensor-data-integration-existing-plant-historian

Re-engineering System Reliability

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A US fertilizer plant was experiencing recurring reliability problems with its horizontal multistage boiler feed pumps. The series of repeat failures motivated the owner plant to consult with a widely-known unbiased ­­­­aftermarket pump service provider. Previous experience with this company’s Texas facility gave the plant confidence that they had the capability to troubleshoot the problem and provide a solution. This type of supplier has been classified as a “CPRS”— Competent Pump Repair Shop, because their worldwide affiliates are staffed by specialists who have the fullest support of pump engineers at the company headquarters.

The aftermarket pump service provider performed a failure modes and effects analysis (FMEA) that took into consideration historical failure information and included an independent engineering analysis of the operating conditions. A review of the system history uncovered that the fertilizer plant had originally been designed with two 100% pumps. When the system was uprated, increased output requirements necessitated that both pumps operate in parallel to meet the new demand. Based on this information, the FMEA determined that the most probable failure mechanism was discharge recirculation caused by low flow operation.

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Unearthing the Root Cause of Vibration Issues

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A recently constructed fertilizer plant was experiencing significant vibration problems on their brand new UAN Solution pumps. This vibration forced the plant to take the equipment out of service.   

The site was unable to diagnose the root cause of this problem on their own and the unreliability and resulting unavailability of this critical equipment was causing significant stress on the new plant. They heard through another fertilizer plant that a global aftermarket pump service provider had been able to diagnose and remediate their pump problems with great success. The site reached out to this aftermarket pump service provider to help identify the issue and provide solutions.   

The pump was shipped to the aftermarket pump service provider’s Chicago repair shop to perform a thorough disassembly, cleaning, and inspection (DCI). The service provider’s engineering team reviewed the original pump design and historical vibration information provided by the plant. Between this review and the DCI results, sufficient evidence was gathered to perform a root cause analysis (RCA) that explained the aberrant behavior of the problem pumps. The pumps were then re-engineered to eliminate the diagnosed problem and provide the plant with reliable operation.   Continue reading →

The Hidden Dangers of Shaft Stiffness

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The pump shaft is the central component of the rotating element and is responsible for transmitting energy to the rotating components. The shaft carries the impellers, sleeves and couplings for the rotating element assembly. The stiffness of the combined assembly is responsible for ensuring that the pump stationary components do not come into contact with the rotating components.

Unfortunately, this is not always achieved and many pump rotors cannot be described as classically stiff. This can have dire consequences for machine reliability, particularly if, during the rotor build process, the technicians are not aware of the subtleties of the machine design.

Source: https://www.pumpsandsystems.com/hidden-dangers-shaft-stiffness