15.3. Unit Operations Not Previously Covered

In this text, we have covered the control of a few unit operations but have not discussed control structure determination in detail. In this section, we first discuss the two major structures for maintaining material balance control, and then we discuss the control of some typical unit operations that occur in a process flow sheet.

Supply-Side vs. Demand-Side Control of Production

Material balance control can be accomplished using two approaches: supply side (direction of flow) and demand side (direction opposite to flow). A simple surge tank level example is shown in Figure 15-10. The level controller manipulates the flow out of the vessel in supply-side control, while the level controller manipulates ...

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