CG4008: Consider a well-stirred vessel shown In Figure 1. The temperature of the liquid In this vessel is controlled by steam condensing In a coil placed in the vessel: Process Troubleshooting Assignment, UOL, Ireland

Consider a well-stirred vessel shown In Figure 1. The temperature of the liquid In this vessel is controlled by steam condensing In a coil placed in the vessel. The proportional controller Is used to manipulate the steam flow rate using the temperature sensed by the thermocouple.

The mass of liquid in the vessel is maintained constant with the help of a level controller

• Define appropriate variables (and symbols) and formulate equations for the temperature of the liquid in the vessel, the temperature of the thermowell, the temperature of the thermocouple, and the steam flow rate. Make suitable assumptions. Solve the governing equations to obtain transient profiles of these variables using the initial conditions as T= 80 C. The steam temperature may be assumed as 100 C. Other data is:

Calculate transient profiles of temperature for two values of controller gains (steam flow rate = controller gain x temperature difference between the set point and thermocouple) as 2 and 6 in appropriate units. Discuss the implications of larger CI or C2 and what will happen if the existing thermo well is replaced by a larger thermowell. Discuss possible ways of reducing the response time of the temperature controller.

Assume a simple endothermic first-order reaction taking place in the described vessel. The reaction is to be carried out at 90 C. Formulate model equations for a simulating concentration of reactant, product, and temperature of the reactor contents. The inlet temperature may be assumed to be 50 C. Simulations should be carried out for two values of controller gains used in part 1. Make suitable assumptions about activation energy, the reaction rate constant, and the inlet concentration of the reactant. Discuss the roles of Kp, activation energies, and thermo-well characteristics (C1 and C2) on transient profiles of temperature and concentrations.