A temperature control system and method controls temperatures of front and
back ends of a shift reactor. Front and back end temperature sensors
sense temperatures of the front and back ends of the shift reactor and
generate front and back end temperature signals. An actuator injects
fluid into the front end of the shift reactor. A controller communicates
with the front end temperature sensor, the back end temperature sensor
and the actuator and controls the temperature of the front end and the
back end. The controller includes primary and secondary control loops.
The secondary control loop communicates with the back end temperature
sensor. The primary control loop communicates with the front end
temperature sensor. The secondary control loop generates a temperature
setpoint for the primary control loop. The secondary control loop has a
slower response time that the primary control loop.