Introduction:
The purpose of this report is to show an upgrade of a distributed control system (DCS). This upgrade is made necessary by the need of a custom shutdown system for a hydrocracking reactor, which requires high temperatures and pressures. The balance of these high internal values is imperative for safety and proper operation of equipment. Added control of temperature and pressure will further increase safety, as well as reduce the need for any emergency shutdown.
In order to perform these tasks, the provided CASCADE model was modified with the transfer functions gain, time constants, damping coefficient and time delays provided in the process dynamics for the necessary temperature and pressure control system. The PLC design required an array of thermocouple reading a minimum value along with minimum temperature and pressure controllers to meet certain logical operating conditions to ensure the system was running at the desired values. If these conditions were not meet (a pressure above 400 psig or temperature below 250 F), the bypass from the PLC would be read by the process responses and in turn signal the temperature and pressure PID controllers.
 
Recommendations:
The following bullet points summarize what is recommended (including scopes) for the given project:
· Cascade control loops are used in the project. It should be noted that the primary controller is being used for temperature control and the secondary controller is being used for pressure control see figure 1.
· Recommended tuning constants for the reactor inlet temperature controller (primary) would be 0.5 for gain (proportional, P), 0.04 for integral (I) and 0.001 for derivative (D).
· Recommended tuning constants for the heater fuel gas pressure controller (secondary) would be 1.6 for gain (proportional, P), 0.35 for integral (I) and 0.001 for derivative (D).
· A Simulink model of the reactor inlet temperature and heater fuel gas pressure control loops have been designed. See figure 1.
· A Simulink model of the recommended logic diagram showing the shutdown loop of the designed reactor inlet temperature and heater fuel gas pressure control loops is attached. See figure 2.
· A Simulink model of the full recommended design of the control loops diagram is attached. See figure 3.
· Scopes the for primary temperature controller are attached. See figure 4.
· Scopes the for secondary pressure controller are attached. See figure 5.
· Scopes the for shutdown loop when the bypass is on are attached. See figure 6.
· Scopes the for shutdown loop when bypass is off are attached. See figure 7.
· There are no additional calculation required for this project.