Reboiler is considered as one theoretical plate, because
(A) Of the assumption that vapour and liquid leaving the reboiler are in
equilibrium
(B) Vapour is recycled to the column
(C) Reboiler itself contains one plate
(D) None of these
Description : Pick out the wrong statement. (A) Different solids have different equilibrium moisture curves (B) Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of ... (D) Even a forced draft cooling tower cannot cool water below the wet bulb temperature
Last Answer : (C) Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column
Description : Pick out the wrong statement: (A) Reboiler is not used in open steam distillation (B) The separation of solutes of different molecular sizes in a liquid solution by use of a ... is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition
Last Answer : (D) Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition
Description : For a distillation column operating at minimum reflux, the (A) Concentration of liquid and vapour leaving a plate will be same (B) Reflux ratio will be maximum (C) Number of plates required will be maximum
Last Answer : (C) Number of plates required will be maximum
Description : In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapour, because (A) Temperature is less (B) Total pressure is less (C) Mixing of steam ... not so intimate as to result in equilibrium condition (D) Saturated steam is used for steam distillation
Last Answer : (C) Mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition
Description : Which of the following is considered equivalent to one theoretical stage in Mc-Cabe Thiele's method? (A) Partial condenser (B) Total condenser (C) Reboiler (D) Both (B) and (C)
Last Answer : (D) Both (B) and (C)
Description : A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are ... and without total reflux (D) The top and bottom compositions correspond to the maximum enrichment available
Last Answer : (D) The top and bottom compositions correspond to the maximum enrichment available
Description : In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalent to a theoretical plate HTUOG = overall gas phase height of a transfer unit). (A) Straight (B) Parallel (C) Both (A) & (B) (D) Neither (A) nor (B
Last Answer : (C) Both (A) & (B)
Description : In McCabe-Thiele method of theoretical plate calculation for a distillation column, the operating lines of stripping and rectifying sections coincide with the diagonal at __________ reflux. (A) Total (B) Minimum (C) Operating (D) Maximum permissible
Last Answer : (A) Total
Description : Pick out the correct statement. (A) The slope of the stripping line is always less than unity (B) For a given separation in a binary distillation column, with increase in reflux ratio ( ... (D) Kremser-Brown-Souder's equation is used to calculate the efficiency of a plate tower
Last Answer : C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux
Description : . In a distillation column, with increase in the reflux ratio, the heat removed in the cooler (A) Increases (B) Decreases (C) Remains unaffected (D) And the heat required in reboiler decreases
Last Answer : (A) Increases
Description : An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are ... (D) More number of trays are required and the residue composition is more dilute in methano
Last Answer : (A) Less number of trays are required
Description : Minimum reflux ratio in a distillation column results in (A) Optimum number of trays (B) Minimum reboiler size (C) Maximum condenser size (D) Minimum number of trays
Last Answer : (C) Maximum condenser size
Description : On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in (A) Greater degree of separation with a fixed number of trays (B) Increased reboiler load
Last Answer : (C) Increased reflux ratio
Description : In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads? Reflux conditions: (i) Reflux stream is completely liquid ... D) Both condenser and reboiler loads are higher in case (ii) as compared to case (i)
Last Answer : (D) Both condenser and reboiler loads are higher in case (ii) as compared to case (i)
Description : In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of (A) 1.5 (B) -0.6 (C) -1.5 (D) 0.6
Last Answer : (C) -1.5
Description : In saturated gas, the (A) Vapour is in equilibrium with the liquid at the gas temperature (B) Vapour is in equilibrium with the liquid at the room temperature (C) Partial pressure of vapour equals the vapour pressure of the liquid at room temperature (D) None of these
Last Answer : (A) Vapour is in equilibrium with the liquid at the gas temperature
Description : Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture. (A) Bound (B) Unbound (C) Critical (D) None of these
Last Answer : (A) Bound
Description : In Azeotropic mixture, the equilibrium vapour composition is (A) More than liquid composition (B) Less than liquid composition (C) Same as liquid composition (D) Independent of pressure
Last Answer : (C) Same as liquid composition
Description : Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture. (A) Unbound (B) Critical (C) Free (D) Bound
Last Answer : (A) Unbound
Description : When liquid and vapour phase of multi-component system are in equilibrium (at a given temperature and pressure), then chemical potential of each component is (A) Same in both the phases (B) Zero in both the phases (C) More in vapour phase (D) More in liquid phase
Last Answer : (A) Same in both the phases
Description : If the vapour pressure at two temperatures of a solid phase in equilibrium with its liquid phase are known, then the latent heat of fusion can be calculated by the (A) Maxwell's equation (B) Clausius-Clapeyron Equation (C) Van Laar equation (D) Nernst Heat Theorem
Last Answer : B) Clausius-Clapeyron Equation
Description : When liquid and vapour phases of one component system are in equilibrium (at a given temperature and pressure), the molar free energy is (A) More in vapour phase (B) More in liquid phase (C) Same in both the phases (D) Replaced by chemical potential which is more in vapour phase
Last Answer : (C) Same in both the phases
Description : A reasonably general expression for vapour-liquid phase equilibrium at low to moderate pressure is φi yi P = Yi xifi° where, Φ is a vapor fugacity component, Yiis the liquid activity co- ... and liquid composition xi only (D) Temperature, pressure, liquid composition xi and vapour composition yi
Last Answer : (C) Temperature, pressure and liquid composition xi only
Description : The number of degree of freedom for an Azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is (A) 3 (B) 1 (C) 2 (D) 0
Last Answer : B) 1
Description : What is the degree of freedom for a system comprising liquid water equilibrium with its vapour? (A) 0 (B) 1 (C) 2 (D) 3
Description : Theoretical head developed by a centrifugal pump does not depend upon the __________ the impeller. (A) Radius of (B) Speed of (C) Fluid velocity leaving (D) None of these
Last Answer : (D) None of these
Description : In case of a centrifugal pump, the theoretical head developed is dependent on the __________ the impeller. (A) Speed of (B) Diameter of (C) Fluid velocity leaving (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In ... layers over a flat plate are of equal thickness, if Schmidt number is equal to unity
Last Answer : (C) For Laminar flow over a plate of length L, the local mass transfer coefficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s
Description : Plate efficiency (A) Is a function of the mass transfer between liquid and vapour (B) Increases due to foaming (C) Increases due to liquid entrainment (D) Increases due to weeping and dumping of liquid
Last Answer : (A) Is a function of the mass transfer between liquid and vapour
Description : Back-trapping in a distillation column (A) Increases tray efficiency (B) Decreases tray efficiency (C) Reduces pressure drop (D) Is desirable, as it provides improved vapour-liquid contact
Last Answer : (B) Decreases tray efficiency
Description : The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will (A) Increase (B) Decrease (C) Remain same (D) Depend on saturated boiling point; may increase or decrease
Last Answer : (A) Increase
Description : In stripping section of continuous distillation column, the (A) Liquid is stripped of high boiler (B) Liquid is enriched with high boiler (C) Vapour is stripped of low boiler (D) None of these
Last Answer : (B) Liquid is enriched with high boiler
Description : In rectifying section of a continuous distillation column, the (A) Vapour is enriched with low boilers (B) Vapour is enriched with high boilers (C) Liquid is stripped of high boilers (D) None of these
Last Answer : (B) Vapour is enriched with high boilers
Description : Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates ... (except the first one) is involved in each of the evaporation process (D) None of these
Last Answer : (B) There is no dynamic equilibrium between successive layer
Description : Pick out the wrong statement. (A) Critical moisture content is not a property of the material itself (B) A sharp increase in pressure drop gives an indication of the flooding in a ... unity (D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum
Last Answer : (D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum
Description : Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty? (A) Sieve plate column (B) Bubble cap column (C) Randomly packed column (D) Wetted wall column
Last Answer : (D) Wetted wall column
Description : __________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids. (A) Wetted wall (B) Packed (C) Plate (D) Spray
Last Answer : C) Plate
Description : Pick out the correct statement. (A) For identical gas flow rates, less pressure drop occurs through a plate tower than through a packed tower (B) Plate column can handle greater liquid loads without flooding than packed ... duty, plate columns weigh less than packed columns (D) All (A), (B) and (C)
Description : Flooding in a distillation column is detected by a sharp (A) Increase in Murphree plate efficiency (B) Decrease in pressure drop (C) Decrease in liquid hold up in the column (D) Increase in pressure drop
Last Answer : (D) Increase in pressure drop
Description : Plate efficiency in a distillation column is reduced due to the __________ of liquid. (A) Entrainment (B) Foaming (C) Weeping & dumping (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : Which of the following equipments is used for liquid dispersion? (A) Packed column (B) Venturi scrubber (C) Bubble cap plate column (D) Wetted wall column
Last Answer : Option B
Description : For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause __________ plate requirement. (A) No change in theoretical (B) Marginal decrease in the number of (C) Major decrease in the number of (D) None of these
Last Answer : (B) Marginal decrease in the number of
Description : The minimum number of theoretical plates is required for achieving a given separation in distillation column with (A) No reflux (B) Total reflux (C) Zero reflux ratio (D) Minimum reflux ratio
Last Answer : (B) Total reflux
Description : Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for (A) Constant molal overflow (B) Total reflux (C) Constant relative volatility (D) All (A), (B) and (C)
Description : Fenske equation determines the (A) Maximum number of ideal plates (B) Height of the distillation column (C) Minimum number of theoretical plates (D) Optimum reflux ratio
Last Answer : (C) Minimum number of theoretical plates
Description : At what value of reflux ratio, number of theoretical plates in a distillation column is minimum? (A) 0 (B) 1 (C) ∞ (D) < 1
Last Answer : (C) ∞
Description : Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the (A) Relative volatility is reasonably constant (B) Mixture (to be separated) ... (to be separated) shows positive deviation from ideality (D) Multi-component distillation is involved
Last Answer : (A) Relative volatility is reasonably constant
Description : In Designing A Clutch Plate, What Assumption Is Made?
Last Answer : Uniform wear condition is assumed because it leads to safer design.
Description : Consider the following assumption made in the analysis of a jet impinging normally on a moving plate to introduce the principle of moment of momentum: 1. Friction between jet and plate is neglected. 2. Flow is steady 3. Impinging momentum of ... b) 1, 2 & 3 only (c) 2, 3 and 4 only (d) 1, 2, 3 & 4
Last Answer : (a) 1, 2 & 4 only
Description : If a flat plate with a circular hole is subjected to tensile force, then its theoretical stress concentration factor is? a) 2 b) 3 c) 4 d) 1
Last Answer : b) 3