A. Relative volatility is close to one (e.g., separation of close boiling isomers)
B. Feed is not at its bubble point
C. Number of equilibrium stages in only stripping section is to be calculated
D. Number of equilibrium stages required is likely to be very small
Related Mcqs:
- Which of the following is not a graphical method (but is an analytical method) for the calculation of theoretical number of stages in case of continuous binary distillation ?
A. Sorel-Lewis method
B. McCabe-Thiele’s method
C. Ponchon-Savarit method
D. None of these - Souders Brown equation given by, U = Kv √(ρl – ρv)/ρv, is used for the calculation of the ______________ in a continuous distillation column?
A. Diameter of the bubble cap column
B. Diameter of the sieve plate column
C. Tray pressure drop
D. Residence time in the downcomer for the disengagement of entrained vapour - With increase in the reflux ratio for a fixed production from a continuous binary distillation column, the ______________________ decreases?
A. Fixed charges initially
B. Running cost of cooling water for condenser
C. Vapour & liquid load both
D. Running cost of steam for reboiler - Overall distillation column efficiency for most of the refinery columns can be given by (for μ = 0.07 – 1.4 cp and relative volatility < 4) (where ε = overall column efficiency, % μ = molal average viscosity of feed at average column temperature and pressure, cp Δp = pressure drop per tray, psi) ?
A. η = 17 – 61.1 log μ
B. η = 24.6 (Δp/μ)
C. η = 1.66 – 0.25 log μ
D. η = 0.25 log μ – 1.67 - Optimum reflux ratio in a continuous distillation column is determined by the__________________?
A. Maximum permissible vapour velocity
B. Flooding limit of the column
C. Total cost consideration (fixed cost of the column plus the cooling water & steam cost)
D. None of these - In case of a continuous distillation column, increase in reflux ratio may result in the______________?
A. Lower fixed charges for the column
B. Greater cost for the reboiler heat supply
C. Greater cost for the condenser coolant
D. All A., B. and C. - In a continuous distillation column, the optimum reflux ratio ranges from _______________ times the minimum reflux ratio?
A. 1.1 to 1.5
B. 1.6 to 2
C. 2.2 to 2.6
D. 2.7 to 3 - Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column ?
A. Bubble cap trays though most expensive are the best in situations, where low vapour rates is to be handled and a positive liquid seal is essential at all flow rates
B. Murphree efficiency of all the three trays are nearly equal, however the peak efficiency is generally higher for sieve and valve trays than the bubble cap
C. Maintenance cost for valve and sieve trays are comparatively more than bubble cap tray due to their relatively complicated construction features
D. Valve trays have the highest turn down ratio (i.e. the ratio of the highest to the lowest vapour flow rates) and thus provide the maximum flexible operating range - Mc Cable Thiele method used for finding theoretical stages in a distillation column assumes that the_____________________?
A. Sensible heat differences are small, because the temperature changes from tray to tray is small
B. Trouton’s rule is applicable
C. Liquid/vapor loading across the column remains constant
D. All A., B. and C. - For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is_________________?
A. d1/(d1 + d2)
B. d2/(d1 + d2)
C. (d1 + d2)/d1
D. (d1 + d2)/d2
