Failures And Solutions For Dry Das Seal Of Natural Gas Compressor

Centrifugal compressor is one of the most important equipment in natural gas chemicals, and shaft seal is one of the most vulnerable parts of compressor. Therefore, more and more Dry Gas Seals are applied on centrifugal compressors for better reliability, which plays a positive role in increasing operation hours and reducing maintenance cost. However, once DGS failed it should be transferred to original manufacturer to repair due to high quality technology so that user can't do the repair by their own. In this case big impact was brought about to user with high repair cost and long time returns.In view of the common failures of DGS and in combination with experience at production site of Yangtze River Acetyls Chemical Co. Ldt. that natural gas compressor DGS failure due to natural gas leak, a new solution has raised to remove failures of DGS and make it run longer. Dry gas seal's failure is not usual caused by the design but by accessory system. The backing pressure of seal changed, in the mean time clean gas supply is changing accordingly to keep constant different pressure between seal gas supply and backing pressure. This will ensure a stable working environment of DGS.Based on basic principle and structure of dry gas seal, it was fully debated and analyzed over seal's accessory and support environment for most appropriate solution effectively. In order to improve DGS reliability, more discussion wascarried out on component on the compressor that effect DGS's performance, and suggestion of change the material of labyrinth seal was admitted with compressor manufacturer. Any factors will affect the performance of DGS was considered by discussion of changing mode of seal and desulfurization process of natural gas..The effect after modification shows excellent with long service life and low maintenance cost. The cost for maintenance and spare part is saved for RMB2,37M. If non-planed shutdown is also considered, the loss would total RMB 48000K/per time. In the meantime, the amount of natural gas venting to flare is avoided with DGS operating at near-failure condition, which not only reduce the power consumption but slowdown the cost of natural gas.In general, the study on the failures of dry gas seal system is of great significance on design and maintenance.