E520 Nitric Acid Expander Emergency Breakdown
• May 2014 IR E520 Tail Gas Expander high pressure seal failure
• Emergency breakdown Expander change-out
• Spare E520 Expander sitting idle following multiyear run
• Spare Expander experienced high and unstable shaft vibrations during prior run
• Experienced RMS engineering supervised Expander change-out
• RMS cold alignment, bearing changes, and careful set-up yield low and stable vibration
CHALLENGES & SOLUTIONS
• Train alignment
Solution: RMS developed cold alignment settings that account for the machines’ thermally predicted operating position. RMS shimmed the expander and machined new alignment pin holes on the pedestals to set the expander in its optimum position.
• Shaft Vibration
Solution: RMS modified existing bearings for more stable operation. RMS has extensive
experience with bearing retrofits in nitric acid expanders; however a complete bearing change-out wasn’t possible due to a tight turnaround schedule.
◊ During prior run, vibration levels ranged from 2-3 mils
◊ After reinstallation, vibration level did not exceed 1.06 mils
◊ Lowest historical vibration level for this expander
Axial Compressor Turnaround Overhaul
Rotating Machinery Services, Inc. was recently awarded a project to modify and overhaul a 16,000 horsepower axial compressor for a major Pennsylvania refinery. The work was performed during a major process unit shut-down, which began in early February.
The upgrades and modifications to the equipment required the specialty engineering and shop skills provided by RMS. The major challenge was to complete the work scope in the short time frame allowed to meet the restart deadline. Accomplishing this task required detailed scheduling, engineering, and the preparation of all of the new components required to complete the overhaul.
Once the axial compressor spare rotor arrived at RMS, modification and overhaul work began in earnest. The work scope included disassembling the customer’s spare rotor, machining and replacing the two rotor end-shafts, installing new 1st and 2nd stage discs, restacking the 12-stage rotor, installing new 1st and 2nd stage blades, and balancing the completed rotor assembly.
The full compressor was dis-assembled and inspected. RMS installed new inlet guide vanes, new 1st and 2nd stage stators, modified the bearing assemblies, and performed a precision-grind of the rotor blade tips for an optimum fit to the casing. The machine was then reassembled and shipped to the refinery for reinstallation, supervised by RMS. The project was completed successfully and on-time, meeting all of the customers’ requirements.
RMS strives to continuously increase our capabilities to better serve our customers. We have expanded our machining capabilities, and shop space. The 9,000 square foot expansion of our shop has provided us the ability to work on larger and more complex equipment.