The capacity of double-effect evaporator is less than half of the capacity of two single effects, each of which is operating over same terminal temperature difference, when the (A) Solution has an elevation of boiling point (B) Evaporators operate under vacuum (C) Evaporators operate at atmospheric pressure (D) None of these

The capacity of double-effect evaporator is less than half of the
capacity of two single effects, each of which is operating over same terminal
temperature difference, when the
(A) Solution has an elevation of boiling point
(B) Evaporators operate under vacuum
(C) Evaporators operate at atmospheric pressure
(D) None of these
by

1 Answer

Answer :

(A) Solution has an elevation of boiling point
by

Related questions

Pick out the wrong statement. (A) The value of hydrostatic head increases with increase in vacuum in the effect in a multiple effect evaporator system (B) Entering velocity of the liquid in the tubes of natural circulation evaporators is in the range of 0.3 to 0.9 metre/second (C) Duhring's plot is used for calculating the concentration of solution (D) In a multiple effect evaporation system, the number of effects is limited by the total boiling point rise

Description : Pick out the wrong statement. (A) The value of hydrostatic head increases with increase in vacuum in the effect in a multiple effect evaporator system (B) Entering velocity of the liquid in ... a multiple effect evaporation system, the number of effects is limited by the total boiling point rise

Last Answer : (C) Duhring's plot is used for calculating the concentration of solution

. A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because (A) Total heat transfer area of all the effects is -less than that in a single effect evaporator system (B) Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect (C) Boiling point elevation in a single effect system is much higher than that in any effect in a multi-effect system (D) Heat transfer co-efficient in a single effect is much lower than that in any effect in a multi-effect system

Description : . A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because (A) Total heat transfer area of ... in a single effect is much lower than that in any effect in a multi-effect system

Last Answer : (B) Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect

Pick out the wrong statement: (A) The capacity of an evaporator is reduced by the boiling point elevation (B) Corrosive liquid is normally passed through the tubes in a shell and tube heat exchanger (C) Steam jet ejector is used for vapor compression in a thermal recompression evaporator (D) Heat sensitive materials should be concentrated in high pressure evaporators

Description : Pick out the wrong statement: (A) The capacity of an evaporator is reduced by the boiling point elevation (B) Corrosive liquid is normally passed through the tubes in a ... recompression evaporator (D) Heat sensitive materials should be concentrated in high pressure evaporators

Last Answer : (D) Heat sensitive materials should be concentrated in high pressure evaporators

Pick out the wrong statement. (A) Economy of a multiple effect evaporator is not influenced by the boiling point elevation (B) Two identical cubes of iron and copper will have the same heat content under the same conditions of temperature (C) Double pipe heat exchangers are mostly used in the field of refrigeration (D) Finned tube heat exchangers are suitable for heating air by steam

Description : Pick out the wrong statement. (A) Economy of a multiple effect evaporator is not influenced by the boiling point elevation (B) Two identical cubes of iron and copper will have the same heat ... in the field of refrigeration (D) Finned tube heat exchangers are suitable for heating air by steam

Last Answer : (B) Two identical cubes of iron and copper will have the same heat content under the same conditions of temperature

In a multiple effect evaporator, the effect of boiling point elevation is to (A) Reduce the capacity (B) Reduce the economy (C) Increase the economy (D) None of these

Description : In a multiple effect evaporator, the effect of boiling point elevation is to (A) Reduce the capacity (B) Reduce the economy (C) Increase the economy (D) None of these

Last Answer : (A) Reduce the capacity

case of condensers & evaporators operating under given terminal conditions, LMTD (logarithmic mean temperature difference) for counter flow as compared to that for parallel flow is (A) More (B) Less (C) Equal (D) Much more

Description : case of condensers & evaporators operating under given terminal conditions, LMTD (logarithmic mean temperature difference) for counter flow as compared to that for parallel flow is (A) More (B) Less (C) Equal (D) Much more

Last Answer : Option C

In case of evaporators, liquid entrainment results primarily due to (A) High vacuum in the evaporator (B) High evaporation rate (C) Foaming of the solution (D) High heat transfer rate

Description : In case of evaporators, liquid entrainment results primarily due to (A) High vacuum in the evaporator (B) High evaporation rate (C) Foaming of the solution (D) High heat transfer rate

Last Answer : (C) Foaming of the solution

Optimum number of effects in a multiple effect evaporator is decided by the (A) Cost benefit analysis (B) Floor area availability (C) Terminal parameters (D) Evaporation capacity required

Description : Optimum number of effects in a multiple effect evaporator is decided by the (A) Cost benefit analysis (B) Floor area availability (C) Terminal parameters (D) Evaporation capacity required

Last Answer : (A) Cost benefit analysis

Optimum number of effects in a multiple effect evaporator is decided by the (A) Cost benefit analysis (B) Floor area availability (C) Terminal parameters (D) Evaporation capacity required

Description : Optimum number of effects in a multiple effect evaporator is decided by the (A) Cost benefit analysis (B) Floor area availability (C) Terminal parameters (D) Evaporation capacity required

Last Answer : (A) Cost benefit analysis

Black liquor generated during paper manufacture is concentrated in a (A) Single effect evaporator (B) Single effect evaporator followed by a crystalliser (C) Multiple effect evaporator (D) Multiple effect evaporators followed by a crystalliser

Description : Black liquor generated during paper manufacture is concentrated in a (A) Single effect evaporator (B) Single effect evaporator followed by a crystalliser (C) Multiple effect evaporator (D) Multiple effect evaporators followed by a crystalliser

Last Answer : (C) Multiple effect evaporator

The actual temperature drop across the heating surface of an evaporator depends on the (A) Liquid depth over the heating surface (B) Solution being evaporated (C) Pressure difference between the steam chest and the vapor space above the boiling liquid (D) All (A), (B) and (C)

Description : The actual temperature drop across the heating surface of an evaporator depends on the (A) Liquid depth over the heating surface (B) Solution being evaporated (C) Pressure difference between the steam chest and the vapor space above the boiling liquid (D) All (A), (B) and (C)

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

Vacuum is generally maintained in the vapour space of an evaporator mainly to (A) Get economical temperature difference by using moderate pressure steam (B) Facilitate forward feeding in multiple effect evaporation (C) Concentrate heat sensitive materials (D) Achieve very high concentration of the final product

Description : Vacuum is generally maintained in the vapour space of an evaporator mainly to (A) Get economical temperature difference by using moderate pressure steam (B) Facilitate forward ... (C) Concentrate heat sensitive materials (D) Achieve very high concentration of the final product

Last Answer : (A) Get economical temperature difference by using moderate pressure steam

Boiling point elevation of a solution of NaOH (A) Increases rapidly with temperature rise (B) Is almost independent of temperature (C) Is almost independent of pressure (D) Both (B) and (C)

Description : Boiling point elevation of a solution of NaOH (A) Increases rapidly with temperature rise (B) Is almost independent of temperature (C) Is almost independent of pressure (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

Boiling point elevation of an ideal solution (A) Increases rapidly with temperature rise (B) Decreases rapidly with temperature rise (C) In independent of pressure (D) Both (B) and (C)

Description : Boiling point elevation of an ideal solution (A) Increases rapidly with temperature rise (B) Decreases rapidly with temperature rise (C) In independent of pressure (D) Both (B) and (C)

Last Answer : (A) Increases rapidly with temperature rise

or the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is (A) 3 (B) 0.33 (C) 1 (D) 1.33

Description : or the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is (A) 3 (B) 0.33 (C) 1 (D) 1.33

Last Answer : (C) 1

. Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water. (A) Boiling point (B) Dynamic viscosity (C) Kinematic viscosity (D) Density

Description : . Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water. (A) Boiling point (B) Dynamic viscosity (C) Kinematic viscosity (D) Density

Last Answer : (A) Boiling point

The advantage of backward feed multiple effect evaporators over forward feed units is that (A) Heat sensitive material can be handled (B) There is no additional cost of pumping (C) Most concentrated liquid is at highest temperature (D) Equal heat transfer co-efficients exist in various effects

Description : The advantage of backward feed multiple effect evaporators over forward feed units is that (A) Heat sensitive material can be handled (B) There is no additional cost of pumping ... liquid is at highest temperature (D) Equal heat transfer co-efficients exist in various effects

Last Answer : (C) Most concentrated liquid is at highest temperature

For concentrating an aqueous solution of a material like anhydrous Na2SO4, whose solubility decreases with rise in temperature, the most suitable evaporator is a __________ evaporator. (A) High pressure (B) Vacuum (C) Backward feed (D) None of these

Description : For concentrating an aqueous solution of a material like anhydrous Na2SO4, whose solubility decreases with rise in temperature, the most suitable evaporator is a __________ evaporator. (A) High pressure (B) Vacuum (C) Backward feed (D) None of these

Last Answer : (B) Vacuum

Reason for operating an evaporator in multiple effects is to secure (A) Increased steam economy (B) Decreased steam consumption (C) Both (A) and (B) (D) Increased capacity

Description : Reason for operating an evaporator in multiple effects is to secure (A) Increased steam economy (B) Decreased steam consumption (C) Both (A) and (B) (D) Increased capacity

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

Higher boiling fractions like atmospheric residue is distilled under vacuum at low temperature because at high temperature, there is a tendency of the predominance of(A) Thermal cracking(B) Gum formation(C) Coking(D) Discoloration

Description : Higher boiling fractions like atmospheric residue is distilled under vacuum at low temperature because at high temperature, there is a tendency of the predominance of (A) Thermal cracking (B) Gum formation (C) Coking (D) Discoloration

Last Answer : (C) Coking

Economy of a multiple effect evaporator is not influenced much by the (A) Boiling point elevations (B) Temperature of the feed (C) Rate of heat transfer (D) Ratio of the weight of the thin liquor to thick liquor

Description : Economy of a multiple effect evaporator is not influenced much by the (A) Boiling point elevations (B) Temperature of the feed (C) Rate of heat transfer (D) Ratio of the weight of the thin liquor to thick liquor

Last Answer : (A) Boiling point elevations

A multiple effect evaporator as compared to a single effect evaporator of the same capacity has (A) Lower heat transfer area (B) Lower steam economy (C) Higher steam economy (D) Higher solute concentration in the product

Description : A multiple effect evaporator as compared to a single effect evaporator of the same capacity has (A) Lower heat transfer area (B) Lower steam economy (C) Higher steam economy (D) Higher solute concentration in the product

Last Answer : (C) Higher steam economy

Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator? (A) Long vertical evaporator (B) Horizontal tube evaporator (C) Agitated film evaporator (D) Calandria vertical tube evaporator

Description : Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator? (A) Long vertical evaporator (B) Horizontal tube evaporator (C) Agitated film evaporator (D) Calandria vertical tube evaporator

Last Answer : (C) Agitated film evaporator

It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is (A) 3.06 × 10 5 (B) 6.12 × 10 5 (C) 7.24 × 10 5 (D) 9.08 × 10

Description : It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of ... 3.06 10 5 (B) 6.12 10 5 (C) 7.24 10 5 (D) 9.08 10

Last Answer : (A) 3.06 × 10

LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow. (A) Parallel (B) Mixed (C) Counter flow (D) Same in either 'a', b' or 'c'

Description : LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface ... Parallel (B) Mixed (C) Counter flow (D) Same in either 'a', b' or 'c'

Last Answer : (D) Same in either 'a', b' or 'c'

In a forward feed multiple effect evaporator, the pressure is (A) Highest in last effect (B) Lowest in last effect (C) Same in all effects (D) Dependent on the number of effects

Description : In a forward feed multiple effect evaporator, the pressure is (A) Highest in last effect (B) Lowest in last effect (C) Same in all effects (D) Dependent on the number of effects

Last Answer : (B) Lowest in last effect

A dephlegmator is a (A) Total condenser (B) Vacuum evaporator (C) Partial condenser (D) Double pipe heat exchanger

Description : A dephlegmator is a (A) Total condenser (B) Vacuum evaporator (C) Partial condenser (D) Double pipe heat exchanger

Last Answer : (C) Partial condenser

Pick out the wrong statement. (A) Bubble size increases with the dynamic viscosity of the liquid in case of nucleate pool boiling (B) Thermal conductivity of a dry material is more than that of the damp material (C) Ratio of its capacity to economy equals the steam consumption in kg/hr in an evaporator (D) Vaporisation of organic substances in evaporator mostly causes foam formation

Description : Pick out the wrong statement. (A) Bubble size increases with the dynamic viscosity of the liquid in case of nucleate pool boiling (B) Thermal conductivity of a dry material is more than ... in kg/hr in an evaporator (D) Vaporisation of organic substances in evaporator mostly causes foam formation

Last Answer : (B) Thermal conductivity of a dry material is more than that of the damp material

Multiple effect evaporators ar used to (A) Increase the steam economy & decrease the capacity (B) Increase the steam economy & the capacity (C) Decrease the steam economy & the capacity (D) Decrease the steam economy & increase the capacity

Description : Multiple effect evaporators ar used to (A) Increase the steam economy & decrease the capacity (B) Increase the steam economy & the capacity (C) Decrease the steam economy & the capacity (D) Decrease the steam economy & increase the capacity

Last Answer : (B) Increase the steam economy & the capacity

Pick out the wrong statement. (A) In a static mass of liquid, the pressure at a point is the same for all liquids (B) Pressure decreases exponentially with elevation in an isothermal atmosphere(C) Atmospheric pressure = absolute pressure ‒ gage pressure(D) As per Pascal's law, the pressure at a point in a static or uniformlymoving fluid is equal in all directions

Description : Pick out the wrong statement. (A) In a static mass of liquid, the pressure at a point is the same for all liquids (B) Pressure decreases exponentially with elevation in an isothermal atmosphere (C) ... s law, the pressure at a point in a static or uniformly moving fluid is equal in all directions

Last Answer : (A) In a static mass of liquid, the pressure at a point is the same for all liquids

01. When the pressure intensity at a point is less than the local atmospheric pressure, then the difference of these two pressures is called vacuum pressure. A) Agree B) Disagree

Description : 01. When the pressure intensity at a point is less than the local atmospheric pressure, then the difference of these two pressures is called vacuum pressure. A) Agree B) Disagree

Last Answer : Option A

Pick out the wrong statement. (A) Heat transfer from a hot body to cold body by the emission of heat waves is called radiation (B) Filmwise condensation takes place on non-wettable surfaces (C) The boiling point of a solution is affected by liquid head as well as boiling point elevation (D) None of these

Description : Pick out the wrong statement. (A) Heat transfer from a hot body to cold body by the emission of heat waves is called radiation (B) Filmwise condensation takes place on non-wettable surfaces (C) The ... of a solution is affected by liquid head as well as boiling point elevation (D) None of these

Last Answer : (B) Filmwise condensation takes place on non-wettable surfaces

Low-temperature ____ evaporators are used for heat-sensitive foods. a. ultrafiltration c. vacuum b. osmosis d. drum

Description : Low-temperature ____ evaporators are used for heat-sensitive foods. a. ultrafiltration c. vacuum b. osmosis d. drum

Last Answer : c. vacuum

Evaporation of 1kg of water from a solution in a single effect evaporator requires about __________ kg of steam. (A) 0.4 - 0.6 (B) 1-1.3 (C) 1.8-2 (D) 2 - 2.4

Description : Evaporation of 1kg of water from a solution in a single effect evaporator requires about __________ kg of steam. (A) 0.4 - 0.6 (B) 1-1.3 (C) 1.8-2 (D) 2 - 2.4

Last Answer : (B) 1-1.3

Increasing the liquor level in the evaporator results in the (A) Decreased capacity (B) Increase in liquor film co-efficient (C) Decreased effect of hydrostatic head (D) Increased true temperature drop

Description : Increasing the liquor level in the evaporator results in the (A) Decreased capacity (B) Increase in liquor film co-efficient (C) Decreased effect of hydrostatic head (D) Increased true temperature drop

Last Answer : (A) Decreased capacity

. In a backward feed multiple effect evaporator (A) Feed is introduced in the first effect (B) Feed flows from low pressure to high pressure (C) No pumps are required between successive effects (D) None of these

Description : . In a backward feed multiple effect evaporator (A) Feed is introduced in the first effect (B) Feed flows from low pressure to high pressure (C) No pumps are required between successive effects (D) None of these

Last Answer : (B) Feed flows from low pressure to high pressure

Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger calculations (Δt) weighted is used in place of Δt, when it involves more than one sequence of heating or cooling i.e., desuperheating & condensation or condensation & sub-cooling (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted (D) In case of short tube vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Description : Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger ... vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Last Answer : (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

Steam distillation is not recommended to be used, if the (A) Azeotropic mixture is to be separated and the final product is miscible with water (B) Liquids decompose, if distilled directly at atmospheric pressure (C) Material cannot be distilled by indirect heating even under low pressure, because of the high boiling temperature (D) Material to be distilled is thermally unstable or has the tendency to react with other components associated with it, at the boiling temperature

Description : Steam distillation is not recommended to be used, if the (A) Azeotropic mixture is to be separated and the final product is miscible with water (B) Liquids decompose, if ... unstable or has the tendency to react with other components associated with it, at the boiling temperature

Last Answer : (A) Azeotropic mixture is to be separated and the final product is miscible with water

In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator. (A) Increases (B) Decreases (C) Remain constant (D) May increase or decrease, depends on the vacuum

Description : In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator. (A) Increases (B) Decreases (C) Remain constant (D) May increase or decrease, depends on the vacuum

Last Answer : (A) Increases

Boiling point of water gets lowered at high altitudes (e.g., hills), because (A) Temperature is low (B) Atmospheric pressure is low (C) Atmospheric pressure is high (D) None of these

Description : Boiling point of water gets lowered at high altitudes (e.g., hills), because (A) Temperature is low (B) Atmospheric pressure is low (C) Atmospheric pressure is high (D) None of these

Last Answer : Option B

The separation of liquid droplets from the vapor is done by a/an __________, in the evaporators. (A) Steam ejector (B) Entrainment separator (C) Compressor (D) Vacuum pump

Description : The separation of liquid droplets from the vapor is done by a/an __________, in the evaporators. (A) Steam ejector (B) Entrainment separator (C) Compressor (D) Vacuum pump

Last Answer : (B) Entrainment separator

Let’s say we are flying over a large, flat part of Africa. Half of the area is hotter than the other half. The surface pressure is 1000 hPa everywhere. If we fly over at an elevation of 500 m above the surface, in which area does the pressure gauge (altimeter) in our plane read the lowest pressure? (a) The cold part. (b) The hot part. (c) The gauge reads the same pressure everywhere. (d) The gauge varies with the latitude and the temperature of the surface.

Description : Let's say we are flying over a large, flat part of Africa. Half of the area is hotter than the other half. The surface pressure is 1000 hPa everywhere. If we fly over at an elevation ... reads the same pressure everywhere. (d) The gauge varies with the latitude and the temperature of the surface.

Last Answer : (a) The cold part.

Water-ethyl alcohol solution can be concentrated (in respect of alcohol concentration) by __________ distillation. (A) Atmospheric (B) Vacuum (C) High pressure (D) None of these

Description : Water-ethyl alcohol solution can be concentrated (in respect of alcohol concentration) by __________ distillation. (A) Atmospheric (B) Vacuum (C) High pressure (D) None of these

Last Answer : (B) Vacuum

Inside an aeroplane flying at a high altitude, (a) the pressure is the same as that outside (b) normal atmospheric pressure is maintained by the use of air pumps (c) the pressure inside is less than the pressure outside (d) normal humidity and partial vacuum are maintained

Description : Inside an aeroplane flying at a high altitude, (a) the pressure is the same as that outside (b) normal atmospheric pressure is maintained by the use of air pumps (c) the pressure inside is less than the pressure outside (d) normal humidity and partial vacuum are maintained

Last Answer : Ans:(b)

During a slow decompression, passengers will occur: a. The cabin temperature will fall as pressure reduces b. Body cavities (sinuses, ears, etc.) will become pressurised and may require assistance in venting c. As soon as the pressure falls, the oxygen drop-out system will operate d. No contra effects, as slow decompression has no effect on the human body

Description : During a slow decompression, passengers will occur: a. The cabin temperature will fall as pressure reduces b. Body cavities (sinuses, ears, etc.) will become pressurised and may require assistance in ... will operate d. No contra effects, as slow decompression has no effect on the human body

Last Answer : b. Body cavities (sinuses, ears, etc.) will become pressurised and may require assistance in venting

Heat sensitive materials can be concentrated in an evaporator employing (A) Vacuum (B) High pressure (C) High residence time (D) None of these

Description : Heat sensitive materials can be concentrated in an evaporator employing (A) Vacuum (B) High pressure (C) High residence time (D) None of these

Last Answer : (A) Vacuum

Heat sensitive materials can be concentrated in an evaporator employing (A) Vacuum (B) High pressure (C) High residence time (D) None of these

Description : Heat sensitive materials can be concentrated in an evaporator employing (A) Vacuum (B) High pressure (C) High residence time (D) None of these

Last Answer : (A) Vacuum

Tabular bowl centrifuges as compared to disk bowl centrifuges (A) Operate at higher speed (B) Employ bowl of larger diameter (C) Can’t be operated under pressure/vacuum (D) Can’t be used for separation of fine suspended solids from a liquid

Description : Tabular bowl centrifuges as compared to disk bowl centrifuges (A) Operate at higher speed (B) Employ bowl of larger diameter (C) Can’t be operated under pressure/vacuum (D) Can’t be used for separation of fine suspended solids from a liquid

Last Answer : (A) Operate at higher speed

A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides (A) Higher economy (B) Lower capacity (C) Both (A) & (B) (D) Lower economy

Description : A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides (A) Higher economy (B) Lower capacity (C) Both (A) & (B) (D) Lower economy

Last Answer : (A) Higher economy