𝗙𝗿𝗼𝗺 𝗖𝗵𝗿𝗼𝗻𝗶𝗰 𝗙𝗮𝗶𝗹𝘂𝗿𝗲𝘀 𝘁𝗼 𝗦𝘁𝗮𝗯𝗶𝗹𝗶𝘁𝘆: 𝗘𝗻𝗵𝗮𝗻𝗰𝗶𝗻𝗴 𝗖𝗼𝗺𝗽𝗿𝗲𝘀𝘀𝗼𝗿 𝗥𝗲𝗹𝗶𝗮𝗯𝗶𝗹𝗶𝘁𝘆

𝗞𝗘𝗬 𝗦𝗣𝗘𝗖𝗜𝗙𝗜𝗖𝗔𝗧𝗜𝗢𝗡𝗦:
𝘚𝘱𝘦𝘦𝘥: 9750 RPM
𝘊𝘰𝘯𝘧𝘪𝘨𝘶𝘳𝘢𝘵𝘪𝘰𝘯: Single casing, straight-through with 5 impellers
𝘗𝘳𝘦𝘴𝘴𝘶𝘳𝘦𝘴: Suction (P1) = 30 psig, Discharge (P2) = 300 psig
𝘉𝘦𝘢𝘳𝘪𝘯𝘨𝘴: 5-pad Tilting pads bearings (LBP)
𝘚𝘦𝘢𝘭𝘴: Dry gas seals
𝘋𝘳𝘪𝘷𝘦: 4000 HP, 3550 RPM motor with gearbox
𝘉𝘢𝘭𝘢𝘯𝘤𝘦 𝘋𝘳𝘶𝘮: Rotating labyrinth and abradable stationary seal
𝗣𝗥𝗢𝗕𝗟𝗘𝗠 𝗗𝗘𝗙𝗜𝗡𝗜𝗧𝗜𝗢𝗡:
𝙄𝙨𝙨𝙪𝙚: Sub-synchronous vibration at 3600 cpm close to rotor’s 1st mode on start-up post-2004 overhaul
𝙊𝙗𝙨𝙚𝙧𝙫𝙖𝙩𝙞𝙤𝙣: Cascade plot indicates subsynchronous peak at higher speeds, suggesting 1st critical excitation
𝘾𝙤𝙧𝙧𝙚𝙡𝙖𝙩𝙞𝙤𝙣: Vibration closely tracked with discharge pressure
𝗖𝗛𝗥𝗢𝗡𝗜𝗖 𝗛𝗜𝗦𝗧𝗢𝗥𝗬:
𝙍𝙚𝙘𝙪𝙧𝙧𝙞𝙣𝙜 𝙄𝙨𝙨𝙪𝙚: Abradable balance drum seal failures every 3-4 years since 1991
𝙋𝙧𝙚𝙫𝙞𝙤𝙪𝙨 𝙁𝙞𝙭𝙚𝙨: Increased end gap between seals post-2001 failure; further increased during 2004 overhaul due to multiple past failures
𝗦𝗧𝗔𝗕𝗜𝗟𝗜𝗧𝗬 𝗔𝗡𝗔𝗟𝗬𝗦𝗜𝗦:
𝙍𝙤𝙩𝙤𝙧 𝙈𝙤𝙙𝙚𝙡: Built using a sophisticated program to evaluate the problem
𝙁𝙞𝙣𝙙𝙞𝙣𝙜𝙨: Compressor showed a low margin of stability with the balance drum seal identified as the root cause
𝗢𝗣𝗧𝗜𝗠𝗜𝗭𝗔𝗧𝗜𝗢𝗡 𝗦𝗧𝗘𝗣𝗦:
𝘽𝙚𝙖𝙧𝙞𝙣𝙜𝙨: Optimized by increasing L/D, changing the configuration to LOP, and lowering preload
𝙄𝙢𝙥𝙧𝙤𝙫𝙚𝙢𝙚𝙣𝙩: Calculated 1st mode log dec increased from 0.05 to 0.2, indicating better damping
𝗖𝗢𝗡𝗖𝗟𝗨𝗦𝗜𝗢𝗡:
𝙎𝙤𝙡𝙪𝙩𝙞𝙤𝙣: Installed modified LOP bearing configuration
𝙍𝙚𝙨𝙪𝙡𝙩: Significant reduction in sub-synchronous vibrations
𝘿𝙖𝙩𝙖: BODE data shows a lower Amplification Factor, softer peak, and gradual phase change
This enhancement resolved chronic issues and improved the overall stability and performance of the centrifugal compressor at the propylene export facility. This is a great example of how meticulous analysis and targeted modifications can lead to substantial operational improvements! 📈🔍