Having an effective Condition Monitoring Program CdM on your large assets has been proven in one way or another to be valuable on our clients Reciprocating Compression fleets. Recently a client of ours had reported low flow rates to their sales meter from a pair of compressors at a large facility. This was concerning as the potential flow loss would equate to a loss of $2000 per day even at the lower gas costs of today’s markets.
Within minutes of evaluating each machine, our analysts identified that the units compression health was acceptable and that the combined flow from the compressors was well above the metered flow coming out of the combined discharge meter. As an additional service, we completed an ultrasonic survey of any potential re-circulation or leak points such as process drain valves, flare valves, bypass valves or vents from vessels between the meter and the compressor to ensure there were no potential leakage or re-circulation sources.
The compressor health was verified, the leakage points were verified, and the overall flow rate for the compressors were deemed to be within the acceptable range for the units known load. With that information in hand the next step was to verify the plant flow meter for these units. There were multiple in process live checks and online drains made to the meters while the units were in service with no change in results. It wasn’t until the meter was serviced during a plant outage that the discrepancy was found with the calibration and corrected.
Currently the metered flows match the compressors calculated flows from the analysis data and the estimated loss of flow was near $400,000 for the time between the first reporting of the flow loss and the service of the meter system. Up to the service, the compressor flow was not deemed incorrect and there must be some issue with the compressors performance.
In the modern age, there is a lot of trust placed on electronic reporting systems without first ensuring that the systems are correct. From past experience it is good practice to first assume that there is a “cable issue” (to use an old term) as what you see on the screen is not always what is reality. The ability to have the access to data has given all of us a false sense of security to deem that data as credible. We are entering an era where the DRIP (Data Rich Information Poor) syndrome is taking hold and we are left to weed through the data to find the truth. In this case, the data reported from the meters systems were deemed the truth when in actual fact, it was far from that.