Process Dynamics and Control 3rd Edition solutions

Process Dynamics and Control 3
Which of the following statements are true? (a) Feedback and feedforward control both require a measured variable. (b) The process variable to be controlled is measured in feedback control. (c) Feedforward control can be perfect in the theoretical sense that the controller can take action via the

Process Dynamics and Control 3
The distillation column shown in the drawing is used to distill a binary mixture. Symbols x, y, and z denote mole fractions of the more volatile component, while B, D, R, and F represent molar flow rates. It is desired to control distillate composition y despite disturbances in feed flow rate F. All

Process Dynamics and Control 3
Two tanks are connected together in the following unusual way in Fig. E2.3. (a) Develop a model for this system that can be used to find \(h_{1}\), \(h_{2}\), \(w_{2}\), and \(w_{3}\) as functions of time for any given variations in inputs. (b) Perform a degrees of fre

Process Dynamics and Control 3
An electronic PI temperature controller has an output p of 12 rnA when the set point equals the nominal process temperature. The controller response to step change in the temperature set point of 3 rnA (equivalent to a change of 5F) is shown below: t, s p,mA 0- 12 0+ 10 20 9 60 7 80 6 Determine the c

Process Dynamics and Control 3
A completely enclosed stirred-tank heating process is used to heat an incoming stream whose flow rate varies. T; w--~ Heating coil Figure E2.2 Q The heating rate from this coil and the volume are both constant. (a) Develop a mathematical model (differential and algebraic equations) that describes the

Process Dynamics and Control 3
A perfectly stirred, constant-volume tank has two input streams, both consisting of the same liquid. The temperature and flow rate of each of the streams can vary with time. Tl Stream 1 ------,1 wl '+' T2 Stream 2 w2 T3 Stream 3 w3 Figure E2.1 (a) Derive a dynamic model that will describe transient o

Process Dynamics and Control 3
Consider a home heating system consisting of a natural gas-fired furnace and a thermostat. In this case the process consists of the interior space to be heated. The thermostat contains both the measuring element and the controller. The furnace is either on (heating) or off. Draw a schematic diagram f

Process Dynamics and Control 3
Consider the blending system shown in Fig. E12.10. A feedback control system is used to reduce the effect of disturbances in feed composition x1 on the controlled variable, product composition, x. Inlet flow rate w2 can be manipulated. Do the following: (a) Draw a block diagram of the feedback contr

Process Dynamics and Control 3
A thermocouple has the following characteristics when it is immersed in a stirred bath: Mass of thermocouple = 1 g Heat capacity of thermocouple = 0.25 cal!g oc Heat transfer coefficient = 20 cal!cm2h oc (for thermocouple and bath) Surface area of thermocouple = 3 cm2 (a) Derive a transfer function m

Process Dynamics and Control 3
A surge tank in Fig. E4.8 is designed with a slotted weir so that the outflow rate, w, is proportional to the liquid level to the 1.5 power; that is, w = Rh15 where R is a constant. If a single stream enters the tank with flow rate wi, find the transfer function H'(s)!W'(s). Identify the gain and all

Process Dynamics and Control 3
An electrically heated process is known to exhibit second-order dynamics with the following parameter values: K = 3 C/kW, T = 3 min,~ = 0.7. If the process initially is at steady state at 70 oc with heater input of 20 kW and the heater input is suddenly changed to 26 kW and held there, (a) What will

Process Dynamics and Control 3
The liquid storage tank shown in Fig. E2.13 has two inlet streams with mass flow rates w1 and w2 and an exit stream with flow rate w3. The cylindrical tank is 2.5 m tall and 2 m in diameter. The liquid has a density of 800 kg/m3. Normal operating procedure is to fill the tank until the liquid level r

Process Dynamics and Control 3
A composition sensor is used to continually monitor the contaminant level in a liquid stream. The dynamic behavior of the sensor can be described by a first-order transfer function with a time constant of 10 s, c:n(s) C'(s) 1 lOs + 1 where C' is the actual contaminant concentration and C'm is the mea

Process Dynamics and Control 3
A process instrumentation diagram for a flash drum is shown in Fig. E9.2. Steam is condensed in a steam coil to vaporize a portion of the liquid feed, and the liquid product is removed by a pump. There are control valves for the steam flow, vapor product, liquid product, feed flow, and steam chest (w

Process Dynamics and Control 3
A jacketed vessel is used to cool a process stream as shown in Fig. E2.8. The following information is available: (i) The volume of liquid in the tank V and the volume of coolant in the jacket V1 remain constant. Volumetric flow rate qp is constant, but q1 varies with time. (ii) Heat losses from the

Process Dynamics and Control 3
A stirred-tank blending system initially is full of water and is being fed pure water at a constant flow rate, q. At a particular time, an operator shuts off the pure water flow and adds caustic solution at the same volumetric flow rate q but with concentration c;. If the liquid volume V is constant,

Process Dynamics and Control 3
A control system has Gv = Gm = 1 and a second-order process Gp with Kp = 2, r 1 = 4 min, and r 2 = 1 min, which is to be controlled by a PI controller with Kc = 2 and r1 = r 1 = 4 min (i.e., the integral time of the controller is set equal to the dominant time constant). For a set-point change (a) De

Process Dynamics and Control 3
A closed stirred-tank reactor with two compartments is shown in Fig. E2.6. The basic idea is to feed the reactants continuously into the first compartment, where they will be preheated by energy liberated in the exothermic reaction, which is anticipated to occur primarily in the second compartment. T

Process Dynamics and Control 3
A stirred-tank blending system can be described by a firstorder transfer function between the exit composition x and the inlet composition x1 (both are mass fractions of solute):

Process Dynamics and Control 3
The contents of the stirred-tank heating system shown in Figure E4.10 are heated at a constant rate of Q(Btu/h) using a gas-fired heater. The flow rate w(lb/h) and volume V(ft3) are constant, but the heat loss to the surroundings QL(Btu/h) varies with the wind velocity v (ft/s) according to the expre