4.6. Discuss the proposed cascade control designs. In particular, apply the cascade control criteria to each proposed design, and estimate whether the cascade design would provide better performance than single-loop for disturbance response. Consider each of the disturbances separately. To assist in the analysis, prepare a block diagram for each process showing the appropriate cascade control systems. (a) Jacketed stirred-tank reactor in Figure 14.20; disturbances are (1) coolant pressure, (2) coolant temperature, (3) recycle pump outlet pressure, (4) reaction rate (e.g., feed concentration), and (5) feed flow rate. (b) Furnace coil outlet temperature control in Figure 14.15; disturbances are (1) fuel pressure, (2) fuel density (composition), (3) valve sticking, and (4) feed temperature. (c) Repeat (b) with the temperature controller cascaded to a valve positioner, without the flow controller. (d) Figure Q1.9a modified for cascade control with a level to flow to valve control structure; disturbances are (1) pump outlet pressure and (2) second outflow valve percent open. (e) Analyzer to reboiler flow cascade for distillation in Figure Q14.6; disturbances are (1) heating medium temperature, (2) feed temperature, (3) tower pressure, and (4) heating medium downstream pressure. FIGURE 14.20 Cascade control for a stirred-tank reactor with cooling jacket. temperature. FIGURE Q1.9