Tag Archives: hydraulic

Hydraulic Rerate Proven in Performance Test Lab

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Custom Hydraulics for the Midstream Market

This summer, Hydro completed a hydraulic rerate project for a major US midstream pipeline. The project was completed through Hydro South, Hydro’s southeastern US service center in Alpharetta, Georgia. The project was completed with testing support from the Hydro Performance Test Lab, Hydro’s 5000 HP test facility located in Chicago, IL, with engineering direction from Hydro Global Engineering, based in Manchester, UK.

The pipeline originally used two booster pumps and the use of a Drag Reducing Agent (DRA) to achieve the desired flow rate. To increase the overall flow capacity of the line and remove the need for the DRA, the end user specified a pump to be added to the system downstream of the booster pumps.

The pump performance specifications were developed by system engineers and communicated to Hydro. The pump’s original design condition was modified to provide the necessary differential pressure required for the desired flow rate – for today and in the future. This will be achieved without the use of DRA or with little added to the system.

Hydro modified an existing pump casing provided by the pipeline and designed new impellers to meet the specific hydraulic performance requirements. Using computational fluid dynamics and advanced modeling, the new impellers were manufactured and installed by Hydro, then sent to Hydro’s test facility for hydraulic performance testing.

To provide an exact performance match, a larger impeller diameter size was selected for the first test and subsequently trimmed to meet performance within API 610 tolerances. Along with the hydraulic performance test, the mechanical integrity of the pump was measured with a vibration test, mechanical resonance test, and a bearing housing temperature stabilization test. All this information validates the quality of the rebuild and ensures a reliable machine.

The pipeline has a limited ‘budget’ of DRA concentration allowed pipeline wide. This concentration is measured in part per million (ppm). By adding the hydraulically rerated pump to the branch line, the DRA ppm budget can be allocated elsewhere in the pipeline. This will add efficiency and increase overall throughput.

Hydro is very fortunate to support critical industries like midstream pipelines in ensuring safe, reliable, and cost-effective pumps and rotating equipment.

Learn more about Hydro’s Performance Test Lab and Engineering Services

Corroded Steel

Fertilizer Focus: Volute Reprofiling Resolves Vane Pass Vibration

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A hot potassium carbonate pump at a nitrogen fertilizer plant had been experiencing elevated vibration at vane pass frequency. Recognizing that this vibration likely contributed to shortened equipment life, the end user partnered with Hydro to investigate the root cause of the vibration and modify the pump as necessary to remove it.

When the vibration and performance indicated that it was time to take the pump out of service for refurbishment, it was sent to Hydro’s Chicago service center for inspection and analysis. The inspection showed significant damage caused by component contact and erosion.

After reviewing the inspection data, an engineering analysis was completed on the design to determine what could be done to eliminate the vibration. The engineering team determined that the vane pass vibration was related to shock waves caused by the high energy fluid impacting the volute lip. This was intensified in the first stage, where the 4-vane impeller was discharging into a dual volute. The volute lip was reprofiled to reduce this impact and provide a smoother transition from the impeller exit into the volute passage.

The upgraded design was tested in Hydro’s performance test lab. This gave the end user confidence that the hydraulic performance of the pump had not been negatively affected by the volute lip geometry modification. It also verified that the vibration amplitudes had been reduced. After successful testing, the modified pump was returned to the field, where it continues to run smoothly.

chart, bar chart

1. Reduced Vane Pass Vibration Observed During Testing

The Dangers of Operating Pumps at Low Capacity

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Operating at low flow places the machine under a great amount of duress. It is always wise to have a mental picture of what is happening within the passages of the machine to understand why this is the case.

The days have long passed where pump vibrations were viewed as a matter of mechanical balance. Now, we recognize that even if the pump had perfect mechanical balance, it would still exhibit vibrations.

The intensity of this remnant vibration turns out to be flow related with its minimum level being at or around best efficiency point (BEP).

Source: https://www.pumpsandsystems.com/dangers-operating-pumps-low-capacity

Wear in Centrifugal Pumps

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Illustration of wear at the volute lip.

Centrifugal pumps are sometimes used in environments where the pumped product contains suspended solids. While some pumps are specifically designed for solid handling or slurry applications, normal centrifugal pumps do not contain features to prevent performance degradation from the impact of solids.

There are a few key signs that a conventional centrifugal pump is suffering from erosive and abrasive wear. Here are assessment and mitigation strategies to be considered and applied when this occurs.

Particles are a problem in a centrifugal pump due to the way the machine adds velocity to the liquid as it passes up the impeller channels. In general, the higher the speed at the tip of the impeller, the more energy that is imparted to any particle that is suspended within the liquid. This energy can then cause damage to anything it impacts.

Source: https://www.pumpsandsystems.com/wear-centrifugal-pumps 

Root Cause Analysis Uncovers Casting Defects

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Efficiency and reliability are at the forefront of a successful pumping system. As such, unplanned outages can be a detrimental disturbance to the overall operation. In this case, the end user’s high pressure multistage  BB5 barrel pump was experiencing severe vibration, unstable performance, and failure in the field leading to unit shutdown.

This particular unit, used in boiler feedwater operations, is critical to the plant’s uptime and throughput. Furthermore, continued failures can cause growing costs due to inevitable maintenance and repairs, often overlooking a long term solution. With each unplanned outage, the plant could face a significant loss in capital.

Previously, the pump had been running for six months before experiencing catastrophic failure, requiring a shutdown and removal for further analysis. Initially, the unit’s damaged components were repaired by welding, and the volute was reassembled and installed for use. Upon its installation, the power plant placed the unit back into service but encountered a second emergency shutdown after two months in operation.

Video: https://vimeo.com/362808909

Source: https://www.pumpsandsystems.com/root-cause-analysis-uncovers-casting-defects-critical-boiler-feedwater-unit