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Unformatted text preview: University of California, Davis Department of Chemical Engineering and Materials Science ECH 157 Process Dynamics and Control Ahmet Palazoglu EXAM 1 / SOLUTION Fall 2010 ( Open book and no notes ) 1. (5 pts) A fired heater (furnace) is used to heat a process stream containing an intermediate product that will be sent to a downstream reactor. It is not only important to maintain a constant outlet temperature but also to keep the furnace temperature below a certain critical value for safety reasons (metallurgical limits of the furnace tubes). A simple schematic representation is shown in the figure below. Process Stream Fuel Flue Gas Heated Process Stream What is the control objective for this process? Identify all external disturbances that could affect the operation of the furnace. Identify all manipulated variables for the control of this unit in the presence of disturbances. Construct a feedback control configuration and a feedforward control configuration that would satisfy the control objectives in the presence of disturbances. Solution: The control objective is to maintain constant temperature of the heated process stream at the desired operating point in the presence of disturbances and safety limits. External disturbances: Fuel flow rate and its heating value (function of composition), inlet process stream flow rate and temperature (and composition). Manipulated variables: fuel flow rate, inlet stream flow rate. A feedback configuration would measure the outlet process stream temperature and adjust the fuel flow rate. 1 A feedforward configuration would measure the inlet process stream flow rate and again, adjust the fuel flow rate. 2. (6 pts) A single equilibrium stage in a distillation column is shown in the figure below....
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This note was uploaded on 04/01/2011 for the course ECH 157 taught by Professor Palagozu during the Spring '08 term at UC Davis.
- Spring '08