ICAS-PAT manual for Design of process monitoring and ... - CAPEC

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3.8.3.1. Click on the command button, “Select the control parameters” and select the controller parameters from the drop-down list. A message box, asking whether the user wants to select the default value of the controller parameters will appear, on selection of controller parameters. The value of controller parameters will be assigned automatically, if the user will accept the default option. Otherwise the user needs to type the value of the controller parameters in the provided text box. Note that only a PI & on-off controller is implemented at this moment, so the derivative controller constant K D is always set equal to zero. For on-off controller K switch =0 means open loop and K switch =1 means closed loop. 3.8.3.2. Click on the command button, “Activate the loop”. Similarly the command button “Deactivate the loop” can be used to deactivate the unwanted control loop. 3.8.3.3. Repeat the above steps 3.8.2-3.8.3 for all control loops (as a rule of thumb, the number of control loops should be equal to the number of critical process variables). 3.8.4. Click on the command button, “Solve the closed loop model”. 3.8.5. Click on the command button, “Load simulation result”. 3.8.6. Click on the command button, “Select variable” and select a critical process variable that you want to plot. Also select the corresponding set point and actuator. 3.8.7. Click on the command button, “Operational limit of selected variable”. This command will provide the lower and upper limit of the critical process variable (note that the user can modify this limit). The user can also specify the limit of the actuator in the cells allocated for that information. 3.8.8. To see the result, click on the command button, “Plot”. The closed loop response of two variables (dissolved oxygen and pH) are shown in Figure 18 as an example. Actuator plots are not shown. 3.8.9. To analyze the variable, click on the command button, “Analyze the selected variable” and follow the instructions. If the set point of the controlled variable is achieved and the actuator is within the limit, then this control variable-actuator pair can be selected for the final design. As shown in Figure 18 dissolved oxygen 23
and pH are within the limits and corresponding actuators are also within the limits (not shown). 3.8.10. Repeat steps 3.8.6-3.8.9 for all critical process variables involved with the selected critical process point. 3.8.11. Sensitivity verification: to analyze the relative sensitivity of the controlled variable follow the following steps (see Figure 19): 3.8.11.1. Click on the command button, “Select objective function” and select the operational objective from the adjacent list box (for instance cell growth rate (mue) is selected as the operational objective in fermentation process). 3.8.11.2. Click on the command button, “Select control variable (set point)” and select the controlled variables (set points) from the adjacent list box (for instance dissolved oxygen (DO_set), pH, pH_set, and temperature (T_set) are selected as the controlled variables). 3.8.11.3. Perturbation setup: type the values of the lower and upper bound as well as the step for perturbing the control variables (set points) (an example is given in Figure 19, where the lower bound of the perturbation corresponds to -4% and the upper bound corresponds to +4%, whereas the step size for modifying the perturbation is 2%). 3.8.11.4. Click on the command button, “Sensitivity verification”. This command will perturb the controlled variables (set points) and record the effect of the perturbation on the objective function. 3.8.11.5. Click on the command button, “Select objective function”, and select the objective function from the drop-down list. 3.8.11.6. Click on the command button, “Result” , to see the result (in table form). To plot the result click on the command button, “Plot” and analyze the result. If the sensitivity of the proposed controlled variable is negligible then it should not be included in the final list of the PAT system. Figure 19 shows the relative sensitivity of the cell growth rate (objective function) w.r.t. dissolved oxygen, pH and temperature (controlled variables). The Figure shows that the cell growth rate is most sensitive for dissolved oxygen followed by pH and temperature. 24
Page 1 and 2: ICAS-PAT manual for Design of proce
Page 3 and 4: 1. Introduction 1.1. Prerequisites
Page 5 and 6: Figure 2: Find applications of moni
Page 7 and 8: Figure 3: Knowledge/data retrieval
Page 9 and 10: Figure 4: Problem specific interfac
Page 11 and 12: 3.1. Product quality specifications
Page 13 and 14: Equipments Operations Main stream i
Page 15 and 16: • Click on the command button, fi
Page 17 and 18: Figure 12: MoT model interface 3.5.
Page 19 and 20: Data management (interdependency an
Page 21 and 22: 3.6.3. Grading of monitoring tools:
Page 23: 3.7. Proposed process monitoring an
Page 27 and 28: Figure 19: Sensitivity verification
Page 29 and 30: Feed Mixing tank Mixing time Homoge
Page 31 and 32: Cell mass 30 900 kg Foaming level 0

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