Vishakapattnam Steel Plan (VSP) is one of the largest public sector steel production major operating from an integrated operational complex. The Nitrogen compressors form a part of the process support equipment supplying compressed (about 14 bar) nitrogen gas. The input pressure to the compressor is at about 6bar and is fed to the compressors through a buffer tank. The compressor by itself is a twin cylinder horizontal throw reciprocating arrangement with a central drive from electric motor.
The reported higher vibrations on the piping and associated structures were investigated with a series of transfer path analysis method combined with reference measurements at the motor and compressor locations; varying load conditions were considered for assessing vibration behaviour. Structural integrity and base frame (foundation) vibration tests were also carried-out to assess the overall contribution of each sub-system for the perceived vibrations.
Upon Data analysis, it is inferred that gas fluid back and differential pressures combined with changes in volumetric compression of gas in each cylinder of the compressor were predominantly contributing to higher vibrations all through the equipment; since the pipe and its support structures are more freely mounted, the displacement responses are showing up more on them.
A series of check and validate action plans have been proposed for the customer to get into the basic operation of the compressor and to tune it for optimum dynamic performance.