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

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
by

1 Answer

Answer :

(C) Total cost first decreases and then increases
by

Related questions

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

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

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

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

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

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

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 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

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

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

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) ∞

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)

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

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

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

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

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 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

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

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

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

In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed (A) q > 1 (B) q < 1 (C) q = 1 (D) q = 0

Description : In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed (A) q > 1 (B) q < 1 (C) q = 1 (D) q = 0

Last Answer : (C) q = 1

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 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

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

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) 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

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 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

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

When the feed to a distillation column is a saturated liquid, slope of thefeed line is(A) Zero(B) Unity(C) Infinity(D) None of these

Description : When the feed to a distillation column is a saturated liquid, slope of thefeed line is (A) Zero (B) Unity (C) Infinity (D) None of these

Last Answer : (C) Infinity

Pick out the wrong statement (A) Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance (B) In case of gas absorption, HETP is equal to HTU, when both the operating line & the equilibrium lines are parallel (C) Hatta number is important in case of gas absorption with chemical reaction (D) In actual practice, absorption is an endothermic process, while stripping is an exothermic process

Description : Pick out the wrong statement (A) Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance (B) In case of gas absorption, HETP is ... reaction (D) In actual practice, absorption is an endothermic process, while stripping is an exothermic process

Last Answer : (D) In actual practice, absorption is an endothermic process, while stripping is an exothermic process

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 batch distillation with constant reflux, overhead product composition __________ with time. (A) Increases (B) Decreases (C) Does not vary (D) May increase on decrease, depends on the system

Description : In batch distillation with constant reflux, overhead product composition __________ with time. (A) Increases (B) Decreases (C) Does not vary (D) May increase on decrease, depends on the system

Last Answer : (B) Decreases

With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease; depends on system

Description : With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease; depends on system

Last Answer : (B) Decreases

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

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

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

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

. 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

With increase in steam pressure, its specific volume decreases (A) Rapidly first and then slowly (B) Linearly (C) Slowly first and then rapidly (D) Exponentially

Description : With increase in steam pressure, its specific volume decreases (A) Rapidly first and then slowly (B) Linearly (C) Slowly first and then rapidly (D) Exponentially

Last Answer : Option A

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

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

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

A reversible liquid phase endothermic reaction is to be carried out in a plug flow reactor. For minimum reactor volume, it should be operated such that the temperature along the length (A) Decreases (B) Increases (C) Is at the highest allowable temperature throughout (D) First increases and then decreases

Description : A reversible liquid phase endothermic reaction is to be carried out in a plug flow reactor. For minimum reactor volume, it should be operated such that the temperature along the length (A) ... Increases (C) Is at the highest allowable temperature throughout (D) First increases and then decreases

Last Answer : (C) Is at the highest allowable temperature throughout

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

With increase in the liquid flow rate at a fixed gas velocity in a randomly packed counter current gas-liquid absorption column, the gas pressure drop (A) Decreases (B) Remains unchanged (C) Increases (D) Decreases exponentially

Description : With increase in the liquid flow rate at a fixed gas velocity in a randomly packed counter current gas-liquid absorption column, the gas pressure drop (A) Decreases (B) Remains unchanged (C) Increases (D) Decreases exponentially

Last Answer : (C) Increases

The minimum liquid rate to be used in an absorber corresponds to an operating line (A) Of slope = 1 (B) Of slope = 0.1 (C) Tangential to the equilibrium curve (D) None of these

Description : The minimum liquid rate to be used in an absorber corresponds to an operating line (A) Of slope = 1 (B) Of slope = 0.1 (C) Tangential to the equilibrium curve (D) None of these

Last Answer : (C) Tangential to the equilibrium curve

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

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

Cox chart, which is useful in the design of distillation column particularly for petroleum hydrocarbons, is a plot of (where, P = vapor pressure, T = temperature). (A) log P vs. T (B) log P vs. log T (C) T vs. P (D) P vs. log T

Description : Cox chart, which is useful in the design of distillation column particularly for petroleum hydrocarbons, is a plot of (where, P = vapor pressure, T = temperature). (A) log P vs. T (B) log P vs. log T (C) T vs. P (D) P vs. log T

Last Answer : (A) log P vs. T