Dry gas seal failures permanently eliminated

A major natural gas provider in North America was experiencing frequent dry gas seal failures on one of their pipeline compressors. This interrupted gas transportation, causing challenges to meet customer demands, along with unplanned and costly maintenance.

The pipeline company builds and operates, safe and reliable energy infrastructure, which includes a 93,300 km (57,900 miles) natural gas pipeline network. This network provides more than 25% of the clean-burning natural gas consumed daily across North America for heating homes, fueling industries, and generating power.

One compressor in the network was having challenges to meet the required uptime. Several seal failures had occurred which led to a gas supply interruption. On top of this the seal failures were costly due to seal repairs, manpower and consequential compressor damages.

As­sess­ing the sit­u­a­tion there were two concerns iden­ti­fied by the user: One was the seal gas supply loss during pres­sur­iza­tion and standby op­er­a­tion. The second concern was the high con­t­a­m­i­na­tion content in the seal gas, which was over­bur­den­ing the existing seal gas filters. 

In search of a solution, the pipeline company‘s tech­ni­cians turned to EagleBurgmann’s com­pres­sor sealing experts. After jointly re­search­ing and in­ves­ti­gat­ing the causes, it was decided to im­ple­ment the RoTech­Booster, an elec­tri­cally driven seal gas booster to remedy the sit­u­a­tion. A proven seal gas booster that keeps dry gas seals reliably clean not only during standby con­di­tions, but any time in­suf­fi­cient seal gas flow occurs. The rotating design includes the ability to maintain an un­lim­ited pres­sur­ized hold.

A suitable RoTech­Booster model was selected ac­cord­ing to the pre­vail­ing op­er­at­ing con­di­tions. The high seal gas con­t­a­m­i­nant content was managed with a co­a­lescer filter with the ad­di­tional of a cyclone to remove most of the debris and liquids. This allowed the co­a­lesc­ing filter to manage the re­main­ing fine debris and aerosols more ef­fec­tively.

A skid was designed with these re­quire­ments in mind for de­liv­er­ing the most ef­fec­tive solution. As the seal gas system in­cor­po­rated fixed orifices for con­trol­ling seal gas flow during normal op­er­a­tion, they produced too much re­stric­tion for the RoTech­Booster to deliver suf­fi­cient seal gas flow when op­er­at­ing. The RoTech­Booster system was designed to bypass these orifices to ensure suf­fi­cient seal gas supply (6 AM3/H) to the seals. The system was designed for the required con­di­tions and man­u­fac­tured by EagleBurgmann.

In June of 2019 the RoTech­Booster with the ad­di­tional fil­tra­tion was in­stalled at the site. As there was no major re­stric­tion in the seal flow path (fixed orifices bypassed) when the RoTech­Booster was op­er­at­ing, the flow produced was 10 Am3/h. The flow was man­age­able by the filters and the ad­di­tional con­sis­tent flow provided in­creased as­sur­ance the dry gas seals weren’t exposed to dirty process gas.

The RoTech­Booster ensures abundant, reliable, and con­sis­tent seal gas flow, through fluc­tu­at­ing op­er­at­ing con­di­tions; thus, clean and dry gas is supplied to the gas seal in every sit­u­a­tion.

• Simple to set-up, easy to operate
• High reliability and availability
• Unlimited continuous operation
• Avoid seal failures
• Low maintenance costs
• Energy efficient
• Eliminates the concern of unreliable external seal gas source

Result

After 2 years of com­pres­sor op­er­a­tion, numerous stops and starts and over 5,000 RoTech­Booster op­er­at­ing hours no change in seal leakage has occurred, in­di­cat­ing the dry gas seals are con­t­a­m­i­na­tion free.

The seal gas filter in­spec­tion verified they were in ex­cel­lent con­di­tion, which is a big dif­fer­ence from in­spec­tions previous to the RoTech­Booster skid in­stal­la­tion. All pipeline con­t­a­m­i­nants were ef­fec­tively being removed with the cyclone added to the fil­tra­tion system.