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

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
by

1 Answer

Answer :

(C) Number of plates required will be maximum

by

Related questions

As the reflux ratio in a distillation column is increased from the minimum, the (A) Slope of the operating line in stripping section decreases (B) Number of plates decreases very slowly first and then more and more rapidly (C) Total cost first decreases and then increases (D) Liquid flow increases while the vapor flow decreases for a system

Description : As the reflux ratio in a distillation column is increased from the minimum, the (A) Slope of the operating line in stripping section decreases (B) Number of plates decreases very slowly first ... decreases and then increases (D) Liquid flow increases while the vapor flow decreases for a system

Last Answer : (C) Total cost first decreases and then increases

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

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

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 At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state, (A) Composition of vapors and that of liquid do not vary throughout the column (B) Reboiler load and condenser load are minimum (C) The top and bottom compositions are unchanged with and without total reflux (D) The top and bottom compositions correspond to the maximum enrichment available

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

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

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

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 (above the minimum reflux ratio), the fixed cost of the distillation column first increases and then decreases (C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux (D) Kremser-Brown-Souder's equation is used to calculate the efficiency of a plate tower

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

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

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

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 suitable membrane is called dialysis (C) Freeze drying is used for the drying of fish (D) Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition

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

At what value of reflux ratio, number of theoretical plates in a distillation column is minimum? (A) 0 (B) 1 (C) ∞ (D) < 1

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) ∞

The operating cost of a distillation column at minimum reflux ratio is (A) Minimum (B) Maximum (C) Infinite (D) Zero

Description : The operating cost of a distillation column at minimum reflux ratio is (A) Minimum (B) Maximum (C) Infinite (D) Zero

Last Answer : (A) Minimum

Can the efficiency of a plate in the distillation tower be greater than 100%? (A) Yes (B) Normally not; but is possible if infinite number of plates are put(C) Never(D) Yes; if the reflux ratio is maximum

Description : Can the efficiency of a plate in the distillation tower be greater than 100%? (A) Yes (B) Normally not; but is possible if infinite number of plates are put (C) Never (D) Yes; if the reflux ratio is maximum

Last Answer : (C) Never

At __________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation. (A) Operating (B) Total (C) Minimum (D) Maximum permissible

Description : At __________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation. (A) Operating (B) Total (C) Minimum (D) Maximum permissible

Last Answer : (B) Total

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-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)

Last Answer : (D) All (A), (B) and (C)

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

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

Pick out the wrong statement. (A) With decrease in feed temperature, the number of plates required for binary distillation decreases for a given ‘L/V’ ratio (B) The extraction per unit of total height for a short packed column is more effective than for a tall column, in case of liquid-liquid extraction(C) Natural draft cooling towers are made of ferroconcrete and its cross￾section is wider at the bottom(D) Vander wall adsorption is also called chemisorption

Description : Pick out the wrong statement. (A) With decrease in feed temperature, the number of plates required for binary distillation decreases for a given L/V' ratio (B) The extraction per unit ... and its cross￾section is wider at the bottom (D) Vander wall adsorption is also called chemisorption

Last Answer : (D) Vander wall adsorption is also called chemisorption

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 theoretical plate calculation for distillation column (C) Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column (D) Even a forced draft cooling tower cannot cool water below the wet bulb temperature

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

Pick out the wrong statement. (A) In solvent extraction, the distribution co-efficient should be as large as possible for solvent economy (B) With increase in pressure, the solubility of gases in solvent increases at a fixed temperature (C) Decrease in Murphree plate efficiency is an indication of entrainment in distillation column (D) The capacity of a distillation column is maximum at total reflux

Description : Pick out the wrong statement. (A) In solvent extraction, the distribution co-efficient should be as large as possible for solvent economy (B) With increase in pressure, the solubility of ... in distillation column (D) The capacity of a distillation column is maximum at total reflux

Last Answer : (D) The capacity of a distillation column is maximum at total reflux

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

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

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 small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency (C) For Laminar flow over a plate of length L, the local mass transfer co￾efficient 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 (D) The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity

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 co￾efficient 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

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 : 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

Last Answer : (A) Of the assumption that vapour and liquid leaving the reboiler are in equilibrium

According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the column. (A) 5 (B) 9 (C) 12 (D) 28

Description : According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a ... in the column. (A) 5 (B) 9 (C) 12 (D) 28

Last Answer : (C) 12

For a fixed number of ideal stages in a distillation column, as the reflux ratio is increased, the difference in composition between the top and bottomproduct streams(A) Increases(B) Decreases(C) Remain unaffected(D) Passes through a maximum

Description : For a fixed number of ideal stages in a distillation column, as the reflux ratio is increased, the difference in composition between the top and bottom product streams (A) Increases (B) Decreases (C) Remain unaffected (D) Passes through a maximum

Last Answer : (A) Increases

. 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

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

Total reflux in a distillation operation requires minimum (A) Reboiler load (B) Number of plates (C) Condenser load (D) All (A), (B) and (C)

Description : Total reflux in a distillation operation requires minimum (A) Reboiler load (B) Number of plates (C) Condenser load (D) All (A), (B) and (C)

Last Answer : (B) Number of plates

In McCabe-Thiele method, at infinite reflux ratio (A) Number of plates is maximum (B) Overhead product is maximum (C) Both the operating lines coincide with the diagram (D) None of these

Description : In McCabe-Thiele method, at infinite reflux ratio (A) Number of plates is maximum (B) Overhead product is maximum (C) Both the operating lines coincide with the diagram (D) None of these

Last Answer : (C) Both the operating lines coincide with the diagram

At minimum reflux ratio for a given separation (A) Number of plates is zero (B) Number of plates is infinity (C) Minimum number of the theoretical plates is required (D) Separation is most efficient

Description : At minimum reflux ratio for a given separation (A) Number of plates is zero (B) Number of plates is infinity (C) Minimum number of the theoretical plates is required (D) Separation is most efficient

Last Answer : (B) Number of plates is infinity

For the same process conditions, the reflux ratio of an unlagged distillation column (A) Decreases in winter (B) Increases in winter (C) Increases in summer (D) None of these

Description : For the same process conditions, the reflux ratio of an unlagged distillation column (A) Decreases in winter (B) Increases in winter (C) Increases in summer (D) None of these

Last Answer : (B) Increases in winter

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 with the material being vaporised is not so intimate asto result in equilibrium condition(D) Saturated steam is used for steam distillation

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

Overall efficiency of the distillation column is (A) The ratio of number of ideal plates to actual plates (B) The ratio of number of actual plates to ideal plates (C) Same as the Murphree efficiency (D) Always more than the point efficiency

Description : Overall efficiency of the distillation column is (A) The ratio of number of ideal plates to actual plates (B) The ratio of number of actual plates to ideal plates (C) Same as the Murphree efficiency (D) Always more than the point efficiency

Last Answer : (A) The ratio of number of ideal plates to actual plates

As the reflux ratio decreases, the (A) Separation becomes more efficient (B) Number of plates increases (C) Column diameter increases (D) None of these

Description : As the reflux ratio decreases, the (A) Separation becomes more efficient (B) Number of plates increases (C) Column diameter increases (D) None of these

Last Answer : (B) Number of plates increases

The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is (A) 2 (B) 0.5 (C) 50 (D) 150

Description : The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is (A) 2 (B) 0.5 (C) 50 (D) 150

Last Answer : (A) 2

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

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

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

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

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

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

Pick out the correct statement. (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas (B) The 'Hatta number' is important in problems involving gas absorption without chemical reaction (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion (D) Total reflux in case of distillation operation requires infinite number of plates for a binary system separation

Description : Pick out the correct statement. (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas (B) The 'Hatta number' is ... reflux in case of distillation operation requires infinite number of plates for a binary system separation

Last Answer : (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion

In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of (A) Area between operating line and 45° diagonal x-y diagram (B) Condenser and reboiler surfaces (C) Tower cross-section (D) None of these

Description : In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of (A) Area between operating line and 45° diagonal x-y diagram (B) Condenser and reboiler surfaces (C) Tower cross-section (D) None of these

Last Answer : (A) Area between operating line and 45° diagonal x-y diagram

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

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

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)

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)

. For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will (A) Increase (B) Decrease (C) Remain same (D) Data insufficient, can't be predicted

Description : . For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will (A) Increase (B) Decrease (C) Remain same (D) Data insufficient, can't be predicted

Last Answer : (A) Increase

Tower diameter may be decreased by (A) Using higher reflux ratio (B) Use of increased tray spacing (C) Increasing the liquid flow rate (D) Increasing the vapour flow rate

Description : Tower diameter may be decreased by (A) Using higher reflux ratio (B) Use of increased tray spacing (C) Increasing the liquid flow rate (D) Increasing the vapour flow rate

Last Answer : (B) Use of increased tray spacing

In an operating distillation column, the (A) Vapors and liquids are at their dew point and bubble point respectively (B) Driving force for the liquid flow is its specific weight (C) Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column (D) Highest temperature is encountered at the top of the column

Description : In an operating distillation column, the (A) Vapors and liquids are at their dew point and bubble point respectively (B) Driving force for the liquid flow is its specific weight (C) Driving force for ... bottom to the top of the column (D) Highest temperature is encountered at the top of the column

Last Answer : (C) Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column

Inside the distillation column, the (A) Driving force for the vapour flow is the pressure drop (B) Liquids are not always at their bubble points (C) Pressure increases gradually from bottom to the top of the column (D) None of these

Description : Inside the distillation column, the (A) Driving force for the vapour flow is the pressure drop (B) Liquids are not always at their bubble points (C) Pressure increases gradually from bottom to the top of the column (D) None of these

Last Answer : (A) Driving force for the vapour flow is the pressure drop

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

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

In McCabe-Thiele method, at infinite reflux ratio (A) The overhead product is minimum (B) Both the operating lines coincide with diagonal (C) Both (A) and (B) (D) Neither (A) nor (B)

Description : In McCabe-Thiele method, at infinite reflux ratio (A) The overhead product is minimum (B) Both the operating lines coincide with diagonal (C) Both (A) and (B) (D) Neither (A) nor (B)

Last Answer : (A) The overhead product is minimum

For water-ethanol system, the minimum reflux ratio (A) Is computed from the slope of the upper operating line that is tangent to the equilibrium curve (B) Is computed from the intercept of the operating line (C) Cannot be computed (D) Is the optimum reflux ratio

Description : For water-ethanol system, the minimum reflux ratio (A) Is computed from the slope of the upper operating line that is tangent to the equilibrium curve (B) Is computed from the intercept of the operating line (C) Cannot be computed (D) Is the optimum reflux ratio

Last Answer : (A) Is computed from the slope of the upper operating line that is tangent to the equilibrium curve

When a multistage tray tower uses a minimum reflux ratio, it implies (A) Infinite trays and maximum reboiler heat load (B) Infinite trays and minimum reboiler heat load (C) Minimum trays and minimum reboiler heat load (D) Minimum trays and maximum reboiler heat load

Description : When a multistage tray tower uses a minimum reflux ratio, it implies (A) Infinite trays and maximum reboiler heat load (B) Infinite trays and minimum reboiler heat load (C) Minimum trays and minimum reboiler heat load (D) Minimum trays and maximum reboiler heat load

Last Answer : (A) Infinite trays and maximum reboiler heat load

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

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

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) shows negative deviation from ideality (C) Mixture (to be separated) shows positive deviation from ideality (D) Multi-component distillation is involved

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

For a binary mixture with low relative volatility, continuous rectification to get pure products will require (A) Low reflux ratio (B) Less number of trays (C) Small cross-section column (D) High reflux ratio

Description : For a binary mixture with low relative volatility, continuous rectification to get pure products will require (A) Low reflux ratio (B) Less number of trays (C) Small cross-section column (D) High reflux ratio

Last Answer : (D) High reflux ratio