Hydraulic Rerates & Pump Efficiency

During a mechanical seal replacement at a major gas plant, a reliability engineer identified that their API OH2 centrifugal pump was operating below the Minimum Continuous Stable Flow (MCSF).

In this case, Hydro Rocky Mountain partnered with HydroTex Deer Park‘s engineering team to provide the customer with an innovative solution by utilizing the existing casing and providing a redesigned impeller to optimize the overall efficiency and life cycle of the unit.

Watch as Ares Panagoulias and Glen Powell, of Hydro’s test lab, examine the historic operating conditions in regard to the pump’s best efficiency point (BEP) and provide a performance test to validate the upgrades and modifications.

Case Study: Hydraulic Rerates & Pump Efficiency from Hydro, Inc. on Vimeo.

Read the technical article on World Pumps: worldpumps.com/ancillary-products/features/seal-replacement-reveals-causes-of-vibration/

Finding flaws with Forensic Analysis

A fertilizer plant in the Gulf of Mexico experienced a suction cavity high pressure ceiling leakage in one of their BB5 boiler feed pumps. By utilizing a forensic analysis, Hydro discovered a simple shortcut in the manufacturing process was costing thousands of dollars in repairs and great inconvenience.

Written by: Pete Erickson and  Todd Soignet
Published by: World Pumps

A BB5 barrel pump at a fertilizer plant along the Gulf of Mexico experienced reduced capacity due to suction cavity high pressure sealing leakage. This was not the first time their boiler feed pumps had experienced a loss of capacity. The pumps were only about a year and a half old and were part of a major expansion project at the plant.

Due to high lead times, the plant decided not to continue repairs, but instead do a simple swap out, when a Hydro service center was recommended by the client’s sister plant as a credible supplier who had the technical and engineering expertise needed to rebuild pumps to the highest quality standards.

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Close Inspection Solves High Thrust Bearing Temperature Problem

Careful analysis identified the issue with this multistage, oil transfer pump.

Written by: Gary Dyson (Hydro, Inc.)
Publisher: Pumps & Systems / August 2014

 

A multistage BB5 diffuser machine in oil transfer service in the Middle East had been in operation for many years without problems. After a routine maintenance strip down and rebuild, the pump experienced a high thrust bearing temperature of 105 C, which caused it to alarm and shut down. The temperature range had previously been 75 C to 85 C.

This case study describes the method used to solve the high bearing temperature problem and outlines the flow physics that contributed to the high thrust bearing temperature. The customer contacted an engineering services company after the original pump manufacturer failed to remedy the problem.

The company’s forensic approach to this problem involved two distinct methodologies:

  • Diligent and in-depth analysis of site data relating to 
the problem
  • Rigorous scrutiny and analysis of the pump geometry and build against the background

The engineering services company identified several scenarios that could cause this temperature rise, then narrowed down the list to establish a root cause.

Site Data Analysis

The behavior of thrust bearing pads during startup is seldom investigated. The temperature rise of the pads can be attributed to two distinct causes—thrust developed during startup and environmental and oil conditions (see Figure 1).

thrust-bearing-pad-behavior

Figure 1. Behavior of thrust bearing pads based on thrust and environmental conditions (Article images and graphics courtesy of Hydro Inc.)

The significant finding from this data was the temperature rise associated with thrust. The pump could not achieve the temperatures measured prior to maintenance in its current condition. The total thrust bearing temperature includes the oil temperature and environmental conditions.

Based on comparisons with previous site data, both the thrust and oil cooling had altered. Analysis of the temperature data at the motor bearings, which were experiencing oil temperature increases of 10 to 15 C, further supported the conclusion. Continue reading