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Fluidized Catalytic Cracking and Alkylation

Cat Cracker

The FCC Unit is one of the most dynamic and complex processes in a refinery.  The reactor-regeneration configuration and the tons of catalyst flow per minute means the unit can quickly become unstable requiring immediate operator interaction.  With elevated temperatures and severe operating conditions, field instrument measurements are essential to understanding how the process is performing at any given moment.  As the traditional heavy oil conversion unit (upgrading low value oil into higher value fuel products) in a refinery, the overall refinery suffers significant financial impact if the FCC unit experiences an unscheduled shutdown.


One main challenge for an FCC unit is to avoid a catalyst reversal in the reactor-regenerator section.  Ensuring the differential pressure measurement is working properly is crucial, as the impulse lines for this application tend to plug.  In addition, the main fractionator bottoms is severe requiring correct selection and installation of field instruments to ensure true measurements.


Utilizing Rosemount’s 3051S differential pressure transmitter with statistical process management can detect line plugging and give adequate time to act before a reversal of catalyst incident occurs.

Alkylation UnitThe Alkylation Unit is a primary process unit to elevate the gasoline octane pool with iso-octane product.  With the inherent dangers associated with alkylation units (both Sulfuric and HF), this is one process unit with restricted access.


Because of the restricted access, normal manual checks in the unit are difficult.  A refiner wants to minimize time in the unit by all personnel, yet they still want to detect problems in the alkylation unit before they escalate into a safety or environmental incident.


Utilizing online diagnostics from smart instruments allows maintenance and operations the information from outside the unit.  This information allows diagnosis outside the field, thus reduces the amount of time required in the hazardous area.