Mar 29, 2007

Refined Emissions

When a New Mexico refinery was mandated by the Environmental Protection Agency (EPA) to reduce its pump emissions to 500 parts per million (ppm) or less, it was evident that an upgrade was in order. The current 1950s vintage NRC FCC pumps were Pacific Model SVE internally-sealed pumps with no stuffing box covers. Not only was the mechanical seal technology obsolete, but the pumps did not have conventional stuffing box covers. These pumps were also very high-maintenance; every couple of weeks a pump in each set was failing.

All these circumstances resulted in a Leak Detection and Repair for High Reactive Volatile Compounds (LDAR-HRVOC) project, where reducing downtime to a minimum was critical. A field service ITT PRO Services professional was sent to the site to supervise pump removal and take dimensions, both of which were necessary to engineer new 9th edition API retrofits. This enabled the pumps to go back into service while the engineering was completed and all custom and standard parts manufactured before the pumps were pulled out of service for the final time.
After the engineering was complete and all parts were on hand, the refinery pulled one unit of each pump set and sent them to the ITT PRO Services Center in Houston. The service center had only 36 hours to turn around the work (i.e., receive the pumps, perform the API retrofit upgrade and return the unit). There were eight pumps involved. All of the units were successfully upgraded and delivered on time.

Challenges

Goulds API 9th edition bearing brackets were installed onto the pumps with conventional API 682 seal chambers, which allowed tandem seals to be installed to meet the new EPA emissions requirements. An important requirement was that the refiner did not want to move drivers. Goulds/PRO Services was able to meet this difficult challenge because it offers seven bearing frame sizes for OH2 pumps, while other OEMs’ bearing housing offerings would have required moving drivers and enlarging the base plates.
The ninth pump on this LDAR/HRVOC project required a hydraulically rerated “custom drop-in” pump to match the hydraulics of two existing pumps. The refinery had two Pacific 4x10½ SVEs and one smaller Pacific 4x7 SVE, but wanted all three pumps to perform the same service. This was not possible because the smaller Pacific SVE could not produce the same head and flow as the larger Pacific SVEs. This required the existing smaller Pacific SVE to be replaced with a complete custom designed pump unit that duplicated the
performance of the larger SVE. Another requirement was that the replacement unit had to fit into the same “hole” where the existing smaller SVE was located. The intent was not to make piping or foundation modifications. To accomplish this task, the following steps were performed:
1. When the casing for the existing
Pacific 4x10½ SVE was received for a 9th edition API retrofit,
the casing was sent to the ITT ProCast facility (foundry and reengineering specialists) to be duplicated. The casing was then sent back to the Houston PRO Service center for completion of the retrofit.
2. An ITT PRO Services field
service technician was sent to the site to take dimensions on
the existing smaller Pacific SVE so that the new custom drop-in unit could be designed to fit into the same “hole.”
3. Based on these dimensions, PRO’s Upgrade Engineering team worked with ProCast to deter- mine modifications required to make the larger SVE fit into the envelope of the smaller SVE. ProCast then proceeded to make a 3-D design and model, generate a rapid pattern prototype, and pour and machine the new
casing in a record time of
12 weeks.
4. A new impeller for the larger SVE was also re-engineered.
5. A new baseplate was custom designed and manufactured so
the new pump would match the existing piping and the new baseplate would fit on to the existing foundation pad
and bolting.
6. A new, back pull out 9th edition API assembly was designed in
the same manner as a power
end retrofit.
7. To complete the new unit, a new motor, coupling and coupling guard were also provided.
8. The new custom drop-in replacement pump was designed, manufactured and shipped within
16 weeks and on time.
9. Another advantage to this custom replacement pump is that all the parts including the impeller, mechanical seal, power frame and
coupling are interchangeable with the two existing larger Pacific SVEs, thus reducing the spare parts inventory.

Accomplishments

The final results of this PRO Services project were lower overall cost and increased reliability of the processes. The refinery was able to reduce switch over down time to 36 hours, eliminating all field machining without having to move drivers. This approach saved 60% of the cost of new equipment. In addition, down time has been reduced by 75% versus other alternatives. Piping was not changed at all, making this custom drop-in replacement pump a viable method to achieve the objectives while reducing total overall project costs with minimum down time.
The eight retrofitted pumps have proved extremely reliable. They have been in service since August 2005 with zero failures. This is a tremendous improvement over the original two weeks between failures. The refinery was happy with the power end retrofits and looks forward to other LDAR-HRVOC or plant turnaround projects.

About the author

Howard Goehring is upgrades engineering supervisor and Curt Roberts is sales engineer for ITT PRO Services. Goehring can be reached at 281/504-6334 or by e-mail at [email protected]. Roberts can be reached at 281/504-6307 or by e-mail at [email protected].

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