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

1 Answer

Answer :

(C) Heat removal load on cooler remains constant, even with increase of the
reflux ratio in a distillation column

Related questions

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 : Pick out the wrong statement pertaining to the cooling towers. (A) In case of induced draft cooling tower, the fan is placed at the top of the tower (B) Effectiveness of ... Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature

Last Answer : (D) Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature

Description : In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when (A) Saturated feed is not used (B) An azeotrope forms (C) The latent ... vaporisation of the more and less volatile components are greatly different (D) A total condenser is used

Last Answer : (D) A total condenser is used

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

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Description : Pick out the correct statement. (A) Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of ... Flash distillation is suitable for separating components which have very close boiling temperature

Last Answer : (A) Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non￾ideal binary system by distillation

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

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 : 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

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 : 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 : Design calculation for multiple component distillation is done by (A) Ponchon-Savarit method (B) McCabe-Thiele method (C) Enthalpy concentration method (D) Tray to tray calculations

Last Answer : (D) Tray to tray calculations

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

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

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

Description : Which of the following assumes constant molal vaporisation and overflow? (A) McCabe-Thiele method (B) Ponchan-Savarit method (C) Enthalpy concentration method (D) Plate absorption column

Last Answer : (A) McCabe-Thiele method

Description : In a forced draft cooling tower, water is cooled from 95 to 80°F by exposure to air with a wet bulb temperature of 70°F. In this case, the (A) Range is 15°F (B) Approach is 10°F (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

Description : In a forced draft cooling tower, water is cooled from 95 to 80°F by exposure to air with a wet bulb temperature of 70°F. In this case, the (A) Range is 15°F (B) Approach is 10°F (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

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

Description : Pick out the wrong statement (A) A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity (B) When water is cooled from 80 to 70°C by exposure ... & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

Last Answer : (D) Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

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

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

Description : McCabe-Thiele method of binary distillation does not assume that the (A) Sensible heat changes are negligible compared with latent heat changes (B) Molar latent heats of all components are equal (C) Heat of mixing is negligible (D) None of these

Last Answer : (D) None of these

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

Description : Can a cooling tower cool water below the wet bulb temperature of inlet air? (A) Yes (B) No (C) Yes; but height of cooling tower will be prohibitively high (D) Yes; but the air flow rate should be excessively high

Last Answer : (B) No

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)

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 : Which one of the following is true to estimate the range of cooling tower? a) Range = cooling water inlet temperature - wet bulb temperature b) Range = cooling water outlet temperature - wet bulb temperature ... = heat load in kcal per hour / water circulation in lines per hour d) None of the above

Last Answer : Range = heat load in kcal per hour / water circulation in lines per hour

Description : Which of the following faction affect the cooling tower performance? • The range • Heat load • Wet bulb temperature • All of the above

Last Answer : All of the above

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

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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 : Pick out the wrong statement. (A) The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation ( ... in a heat exchanger is controlled by the value of the film co-efficient, which is higher

Last Answer : (D) Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film co-efficient, which is higher

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

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

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Description : Pick out the wrong statement. (A) In case of heat transfer by purely forced convection, GR /Re 2 ≤ 1 (B) The equivalent diameter of heat transfer for a duct of ... nucleate boiling depends basically on the ease with which the bubbles are formed and detached from the heating surface

Last Answer : (B) The equivalent diameter of heat transfer for a duct of square cross￾section (having each side as 'x') is equal to 4x

Description : Equilibrium-moisture curves of different solids (A) Are different (B) Are same (C) Depend on the humidity of the gas (D) None of these

Last Answer : (A) Are different

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

Description : Which of the following remains constant during evaporative cooling process with recirculated water supply? (A) Relative humidity (B) Partial pressure of vapour (C) Wet bulb temperature (D) None of these

Last Answer : (C) Wet bulb temperature

Description : During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the __________ remains ... pressure of water vapor (C) Relative humidity (D) None of these

Last Answer : (A) Wet bulb temperature

Description : When the temperature and humidity of air is low, we usually use __________ draft cooling tower. (A) Natural (B) Forced (C) Induced (D) None of these

Last Answer : (A) Natural

Description : During sensible cooling of air, its wet bulb temperature (A) Decreases but dew point remains constant (B) Increases but dew point remains constant (C) Increases & the dew point decreases (D) Decreases & the dew point increases

Last Answer : (B) Increases but dew point remains constant

Description : __________ remains constant during the adiabatic cooling of moist air. (A) Wet bulb temperature (B) Dry bulb temperature (C) Relative humidity (D) Specific humidity

Last Answer : Option A

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 : Pick out the wrong statement: (A) Change in barometric pressure does not affect the relative humidity (B) In case of a packed tower, the operating velocity is about half of the ... (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

Last Answer : (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

Description : If f = moles of vapour present per mole of feed, then the slope of feed line is (McCabe-Thiele method) (A) (1 - f)/f (B) - (f - 1)/f (C) -1/f (D) -f/(1 - f)

Last Answer : (C) -1/f

Description : McCabe-Thiele method (A) Uses molal units for material and energy balance (B) Uses weight fractions to express liquid and vapour composition (C) Can use any type of units (D) Is more accurate than Ponchon-Savarit method

Last Answer : (A) Uses molal units for material and energy balance