Jan 30, 2007

Helping to Meet EPA Emissions Standards

A New Mexico refinery was mandated by the U.S. Environmental Protection Agency to reduce their pump emissions to 500 ppm or less. The current 1950’s vintage NRC FCC pumps were Pacific Model SVE internally-sealed pumps with no stuffing box covers. Not only was the mechanical seal technology obsolete, the pumps did not have conventional stuffing box covers. These pumps were also a high maintenance item. Every few weeks one of the pumps in each set failed.
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 for this customer.

A field service ITT PRO Services professional was sent to the customer’s site to supervise pump removal and dimension taking, 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 customer pulled one unit of each pump set and sent them to ITT PRO Services Center in Houston. The service center had only 36 hours to turn around the work (receive the pumps, perform the API retrofit upgrade, and deliver the unit back to the customer).

There were eight pumps involved. All of the units were successfully upgraded and delivered on time.

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, as it offers seven bearing frame sizes for OH2 pumps, while the bearing housing offerings of other OEMs would have required moving drivers and enlarging the base plates. This simply was not an option for the customer.

The 9th pump, on this LDAR/HRVOC project, required a hydraulically re-rated “Custom Drop In” pump to match the hydraulics of two existing pumps.

The customer had two Pacific 4x10-1/2 SVE’s and one smaller Pacific 4x7 SVE, but wanted all three pumps to perform the same service. This was not possible as the smaller Pacific SVE could not produce the same head and flow as the larger Pacific SVE’s. 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 4x10-1/2 SVE was received for a 9th Edition API retrofit, the casing was sent to the ITT ProCast facility to be duplicated. The casing was then sent back to the Houston PRO Service center for completion of the retrofit.
  2. A field service technician was sent to the customer’s 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 determine modifications required to make the larger SVE fit into the envelope of the smaller SVE. ProCast then proceeded to make a 3D design and model, generate a rapid pattern prototype, 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 that the new pump would match the existing piping and the new baseplate would fit onto 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, new motor, coupling and coupling guards were also provided.
  8. The new custom “Drop-In” replacement pump was designed, manufactured and shipped on time within 16 weeks.
  9. Another advantage to this custom “Drop-In” replacement pump was that all the parts - including the impeller, mechanical seal, power frame and coupling - are interchangeable with the two existing larger Pacific SVE’s, thus reducing the customer’s spare parts inventory.

Accomplishments
This PRO Services project resulted in lower overall cost, less completion time and increased process reliability.
The refinery was able to reduce switchover downtime to 36 hours, reducing expense versus new equipment, eliminating all field machining, and not having to move drivers.

This approach saved 60% over the cost of new equipment.

Moreover, downtime has been reduced by 75% compared to other alternatives.

Piping was not changed at all, thus making this custom “Drop-In” replacement pump a viable method to achieve the objectives while reducing total overall project costs with minimum downtime.

The eight pumps with the retrofits have proved extremely reliable. They have been in service since August 2005 with no failures.

This is an improvement over the original two weeks between failures. The customer stated that they were extremely happy with the power end retrofits and look forward to other LDAR-HRVOC or plant turn-around projects.

About the author

Howard Goehring is the ITT PRO Services Upgrades Engineering Supervisor. Curt Roberts is with the ITT PRO Services in Houston.</p><p>

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