Considerations of Fractionation Plant and Unit Maintenance

Considerations of Fractionation Plant and Unit Maintenance

Jun 2, 2015 | Maintenance, NGL Recovery & Fractionation

Just like cryogenic gas plants, fractionation plants and units are composed of complex components that must be operated in certain ways to ensure not only plant efficiency but also personnel and environmental safety. Systems operate under high temperatures and pressures, and equipment can wear down or fail. Proper hazard evaluations and shut-down processes (when necessary) are only part of the maintenance equation at fractionation facilities. Other important maintenance activities must be included to ensure safe and efficient operation.

In some cases, maintenance activities are planned based on expected degradation of critical equipment before operations even begin. Traditional electrochemical moisture sensors, for example, can still be found at the fractionator inlet or overhead fractionation column streams of some facilities. These sensors are necessary for monitoring streams to ensure moisture content is optimal. However, they are also an important target for maintenance checks as engineers expect in advance that contaminates will hinder their functionality. In some cases, rather than replace the electrochemical sensors regularly, maintenance teams may work with engineers to upgrade moisture analyzers to less corrodible sensors based on technologies like tunable diode laser absorption spectroscopy (TDLAS).

Preventative maintenance is an additional consideration for fractionation facilities. For example, fuel gas flow meters should be checked at least annually to ensure they are calibrated and operating properly. Air and fuel control analyzers are checked and calibrated at least quarterly. Burner tips on hot oil heaters must be cleaned no less than every five years, more often when maintenance or brownfield shutdowns are planned. Thermal and catalytic oxidizers must also be maintained, including the regular change out of catalyst cartridges.

Post-maintenance tasks also factor into team responsibilities. After work is performed on gas compressors or emergency engines, emissions testing must be performed to verify EPA compliance. And finally maintenance teams may be required to work with auditors to ensure the quality and accuracy of fractionator components, including emissions systems. The relative accuracy test audit (RATA) and cylinder gas audit (CGA), for example, both test continuous emissions monitoring systems (CEMS) three or four calendar quarters a year and require maintenance techs on hand to assist with the process. Of course, any type of maintenance performed on facility systems and devices must be documented, stored, and reported on as necessary to comply with local, state, and federal regulations.