Fluid Catalytic Cracking (FCC) is a refining process used to convert heavier crude oil fractions into usable products such as gasoline, jet fuel, and diesel. In the reactor vessel feed oil is mixed with catalyst particles at high temperatures 900°F (482°C) to 1000°F (538°C), breaking the hydrocarbons into smaller particles. During the FCC reaction coke builds up on the catalyst, limiting its ability to carry out the reaction. The spent catalyst in the reactor chamber is then transferred to the regenerator to burn off the residual coke. Then the regenerated catalyst is transferred back to the base of the reactor riser to be used again.

The key to success of this application is Spent and Regenerated Catalyst Slide Valve actuators that provide both reliable positioning accuracy and fast response to the abnormal pressure disturbances that may occur. The valve stroke lengths are typically 8in (20cm) to 24 in (61cm). The Regenerated Catalyst Slide Valve regulates the flow of the regenerated catalyst to the riser, maintaining the pressure head in the standpipe and protecting the reactor from a flow reversal. Maintaining a proper differential pressure is critical for smooth operation. Too high of a pressure difference can lead to excessive catalyst carryover, while too low of a pressure difference can result in poor catalyst circulation. The Spent Catalyst Slide Valve controls the stripper catalyst level, regulates flow of spent catalyst to the regenerator and protects the reactor and main fractionator from a flow reversal. The Spent Catalyst Slide Valve plays a crucial role in maintaining a catalyst barrier, which stops hydrocarbons within the reactor from entering the regenerator. If mixed with oxygen, these hydrocarbons in the regenerator or flue gas train are a safety risk of an explosion. Poor valve performance can create pressure unbalances, which can lead to an inefficient hydrocarbon cracking process. If this condition worsens, it creates potential for unit shutdown and expensive downtime.