Tech Briefs

Fugesco provides solution to mechanical seal problem

A pumping storage plant in southern California had a huge problem. The plant’s waterways are exposed to the desert sand blowing into the canals. This sand and silt ends up in the pumps. As a result, the pumps’ spring-energized, conical-wedged mechanical seals were being destroyed within three months of start up. As a result, the pit would flood out.

The existing seal was not the right solution for this particular application. Canadian seal manufacturer Fugesco, known as a leader in mechanical seal technology, was requested to go on site and find a solution for this ongoing situation. The Fugesco crew analyzed the water conditions below the seal, the water supply to the seal, the pressures below the seal as well as the access to the seal area for assembly and disassembly of the seal unit without having to dismantle the entire pump turbine. A FUGESCO axial type F5000 was installed.

But the design alone was not the cure: the material selection was key. This model has an innovative combination of face materials that can withstand severe applications. By blending a mix of conventional metals and composite materials, Fugesco was able to resolve the customer’s problem. The seal has been running for three years with no problems.

The balanced faces are lubricated with clean water and run on a hydrodynamic layer or film that provides minimal wear of the sealing area. This design is fully split. Every component is designed and manufactured to fit together with no additional adjustments, which facilitates the assembly and shortens the unit’s down time.

The new axial seal installed on this pump, at a facility in California, contains an innovative combination of face materials that can withstand severe applications. The old seal had to be replaced every three months; the new one has been in operation for three years.

A FUGESCO mechanical distance-monitoring device was installed in order to verify wear of the sealing faces. After all this time in use, the wear indicator was showing only 4 percent of wear!

A few months later, during a routine maintenance shutdown of the unit, the seal was taken apart to verify if the monitoring device was accurate and functioning properly. The customer was amazed that the unit had run for such a length of time and was able to reassemble and put the unit back into service immediately.

The new mechanical seal F5000 reduced the leakage from the original design from 90 liters a minute to 1 liter per hour. This eliminated the use of three sump pumps running constantly and the fear of flooding out the bearing area.

According to Richard H. Viens, president of Fugesco, his company’s approach to any seal proposal is to study the particular conditions at hand: there usually is no “off-the-shelf” solution. Each turbine or pump tends to have a personality of its own and has to be handled individually, Viens says. All seals – radial seals, axial seals, and packing boxes – each have their place in this industry and that is why Fugesco designs and produces all three types. But, Viens cautions, selecting of one over the other has to be made for the proper reasons. One of the best ways to do this is through an interactive discussion between the seal supplier and the project owner.

IEEE working on standard for calculating greenhouse gas credits

The Institute of Electrical and Electronics Engineers Inc. (IEEE) is working on a standard designed to help owners of hydro and wind project calculate greenhouse gas emissions credits.

The standard is IEEE P1595, “Standard for Quantifying Greenhouse Gas Emission Credits from Small Hydro and Wind Power Projects, and for Grid Baseline Conditions.” The standard is intended to establish an internationally acceptable basis for measuring, evaluating, and quantifying the eligible, real, measurable, verifiable, and unique reduction in carbon dioxide emissions attributable to small hydro and wind, says Karen McCabe, marketing director for the IEEE Standards Association.

The standard also will help provide an answer to the question: How can one country or jurisdiction to a greenhouse gas emissions trade be assured and satisfied that it is getting real and true value for a purchased greenhouse gas emissions credit from another country or jurisdiction?

As its seed documents, the standard will use project protocols established by Natural Resources Canada for small hydro, wind power, and grid baseline, McCabe says.

The Energy Development and Power Generation committee of the IEEE Power & Energy Society is developing this standard.

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