FCCU MODEL DEVELOPMENT

The simulink block for the FCCU obtainable from cpc_fcc.mdl is to be used for development of transfer is to be used for development of transfer function models between the outputs and the inputs of the process. The specifications for the process are given below:

Inputs (Manipulated variables)

Regenerated catalyst feed rate (Fs) : steady state value = 294 kg/s

Air flow rate (Fa) : steady state value = 25.35 kg/s

Measured Outputs

Riser outlet temperature (T1) : steady state value = 776.9 K

Regenerator cyclone temperature (Tcy) : steady state value = 988.1 K

Regenerator bed temperature (Trg) : steady state value = 965.4 K

You should attempt to develop transfer functions between each of the inputs and the outputs, i.e. six transfer functions in all. The control problem involves the control of two outputs by manipulating the two inputs. Suggested outputs for control are T1 and Tcy. Trg should also be monitored during the control phase of the project. For SISO control, develop four controllers based on input-output combinations with T1 and Tcy being the controlled outputs, and Fs and Fa being the manipulated variables. Each controller will be run on the plant in isolation.

You will develop transfer functions by running step tests, one input at a time, and observing the output responses. You will then attempt to fit the observed response to a transfer function model, and comment on the goodness of fit. Note that the step inputs in the simulink file have initial values set at steady state values, so that you will have to input the final values of the steps in physical variables (and not deviation variables). This is because the simulink block has been set up to accept inputs in physical variables. Outputs are also available as physical variables.

The simulink block has measurement noise built into it, so that you will obtain a noisy response to your step inputs. In order to maintain a reasonable ratio of the true value to the magnitude of the noise for the output responses, it is recommended that you use a step of magnitude 10 kg/s for the input Fs (regenerated catalyst flow rate) and a step of magnitude 1 kg/s for the input Fa (air flow rate).

The next step is to design SISO controllers for each input-output combination (T1 controlled by manipulating Fs, T1 controlled by manipulating Fa, Tcy controlled by manipulating Fs, Tcy controlled by manipulating Fa). Implement these SISO controllers one at a time on the plant, and run simulations for setpoint changes of the order of 10 degrees C.

Submissions for this stage of the project must include the transfer functions you develop, and plots of all the output step responses (the actual plant responses and your model's fit). Be sure to specify the magnitude of the step in the input (especially if it is not a unit step) for each case.Also present results for control with all four SISO controllers. For the control results, be sure to include plots of the uncontrolled output along with the plots of the controlled output and the manipulated variable. Attach a memo with your work consisting of a description of the procedure you followed for model development and controller design, and a discussion of your results.