6 The Following Flash Drum Is Used To Separate Component A From Water Here Z T X T And Y T Represent The Mole Fra 1 (152.52 KiB) Viewed 55 times
6. The following flash drum is used to separate component A from water; here, z(t), x(t) and y(t) represent the mole fraction of component A in the feed, liquid and vapor streams. V kmoles/s y(t) F kmoles/s zlt) M kmoles x(t) LC L kmoles/s alt) A level controller is used to make sure that M is constant, manipulating L only (V is constant), hence F = V + L. Furthermore, relative volatility = a = y/x constant. The process is operated at the (1-y)/(1-x) following conditions: M= 500 kmoles, F = 10 kmoles/s, L = 6 kmoles/s, a = 2.5, x = 0.45.
a) What is the purpose of this process unit, and does it achieve its purpose? (Please do not write down a “tale” of flash drums; your explanation should be concise and based on a mathematical model). b) Determine the time constant and steady state gain (with correct units) of the 1st order time domain representation relating r(t) to x(t). Determine the corresponding transfer function in Laplacec domain. c) If a change equal to -0.10exp(-t/10)H(t) is employed on z(t) for t> 0, determine the time domain response of x(t). Furthermore, sketch the approximate time trajectory of x(t).
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