Rotary valves are adapted to replace traditional slide valves in fluid catalytic cracking units (FCCUs) such as regenerated catalyst valves, spent catalyst valves, cooled catalyst valves, and recirculation catalyst valves. The rotary valves as discussed herein are significantly more compact than a slide valve having a similar flow capacity. The rotary valve is better adapted to provide flow control or throttling than slide valves are. Flow control or throttling occurs with greater response and precision in response to control inputs and rotation. In addition to the size reduction achieved with the rotary valve, the required controls and/or hydraulic fluid necessary to achieve flow changes are significantly reduced, further saving costs for the valve, as hydraulic power units are not required. The omission of a hydraulic power unit also reduces the size of the valve and/or its accompanying structures within the FCCU.