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Gnireenigne lacimehc > EBP (Day 2) > Flashcards

EBP (Day 2) Flashcards

1
Q

Which of the following are valid assumptions of Fourier’s Law?

i. Material is homogeneous and isentropic
ii. Boundary surface are isothermal
iii. There is constant temperature gradient
iv. There is internal heat generation

A. I and IV only
B. II and III only
C. I, II and III only
D. II, III and IV only

A

C. I, II and III only

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2
Q

Dittus-Boelter equation used for the determination of heat transfer co-efficient is valid
A. for fluids in laminar flow
B. for fluids in turbulent flow
C. when Grashoff number is very important
D. for liquid metals

A

B. for fluids in turbulent flow

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3
Q

The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is
A. 1.66
B. 88.66
C. 3.66
D. 2.36

A

C. 3.66

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4
Q

Which tube arrangement in a heat exchanger would facilitate highest heat transfer rate?
A. Square pitch
B. Triangular pitch
C. Diagonal square pitch
D. None of these.

A

B. Triangular pitch

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5
Q

What is the minimum recommended ligament for square pitch arrangement of heat exchangers?
A. 6.5 cm
B. 6.5 mm
C. Equal to tube D2
D. Equal to tube D0

A

B. 6.5 mm

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6
Q

In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to
A. twice the velocity head.
B. half the velocity head.
C. square of the velocity head.
D. four times the velocity head.

A

D. four times the velocity head.

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7
Q

The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface)
A. K/h0
B. 2K/h0
C. h0/K
D. h0/2K

A

B. 2K/h0

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8
Q

Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is _________ law.
A. Kirchoff’s
B. Wein’s
C. Planck’s
D. Stefan Boltzmann

A

B. Wein’s

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9
Q

Which of the following materials has the highest emissivity?
A. Charcoal
B. Chromium
C. Copper, polished
D. Cast iron, oxidized

A

A. Charcoal

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10
Q

Which of the following is TRUE for opaque objects?
A. reflectivity + absorptivity = 1
B. absorptivity + emissivity = 1
C. reflectivity + transmissivity = 1
D. transmissivity + emissivity = 1

A

A. reflectivity + absorptivity = 1

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11
Q

The relation, Sc = Pr = 1, is valid, when the mechanism of __________ transfer is same.
A. mass and momentum
B. heat and mass
C. momentum and heat
D. heat, mass and momentum

A

B. heat and mass

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12
Q

Experimental determination of mass transfer coefficient is done using __________.
A. wetted wall column method
B. inclined plate method
C. spinning disk method
D. parabolic velocity method

A

A. wetted wall column method

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13
Q

According to the film theory of mass transfer, the mass transfer coefficient is proportional to
A. D
B. D^2
C. D^0.5
D. 1/D

A

A. D

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14
Q

Creeping flow around a sphere is defined, when particle Reynold number is
A. < 2100
B. < 0.1
C. > 2.5
D. < 500

A

B. < 0.1

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15
Q

A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of material A is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is

A. 24°C
B. 18°C
C. 6°C
D. 12°C

A

D. 12°C

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16
Q

Compute the volumetric heat (kW/m³) generated by a steel wire with thermal conductivity 370 W/m²-K, diameter of 20 cm, center temperature of 500K and surface temperature of 200K.

A. 44.4x10^6
B. 11.1x10^6
C. 44.4x10^3
D. 11.1x10^3

A

C. 44.4x10^3

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17
Q

A 60 mm thickness large steel plate (k = 42.6 W/m·°C, α = 0.043 m²/hr) initially at 440°C is suddenly exposed on both sides to an environment with convective heat transfer coefficient of 235 W/m²·°C, and a temperature of 50°C. Determine the temperature inside the plate 15 mm from the mid-plane after 4.3 minutes.
A. 251°C
B. 289°C
C. 277°C
D. 262°C

A

C. 277°C

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18
Q

Benzene (A) diffuses into air (B) at a pressure of 2 atm and temperature of 293K. Estimate the diffusivity coefficient (DAB) in cm²/s using Fuller-Schettler-Giddings empirical equation.
A. 0.02
B. 0.04
C. 0.09
D. 0.11

A

B. 0.04

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19
Q

A sintered, solid slab of silica 2.0-mm thick is porous, with a void fraction of 0.30 and a tortuosity of 4.0. The pores are filled with water at 298 K. One face of the slab is in contact with a stirred aqueous potassium chloride (KCl) solution with a concentration of 0.10 mol/L. Fresh water flows rapidly past the other face of the slab. The diffusivity of KCl in water in this concentration range is 1.87 x 10^-9 m²/s. Neglecting any other resistance but that in the porous solid, calculate the steady-state diffusion flux (mol/m²-s) of KCl through the silica slab.
A. 5.4 x 10^-6
B. 4.8 x 10^-6
C. 7.1 x 10^-6
D. 6.9 x 10^-6

A

C. 7.1 x 10^-6

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20
Q

Solutions to the problem of forced convection mass transfer during creeping flow about a spherical particle have been developed. What would happen to the mass flux when the particle diameter is doubled?
A. 2.83
B. 0.36
C. 1.59
D. 0.63

A

D. 0.63

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21
Q

It is the basis of the filtration equations. Oct 2022
A. Hagen
B. Ruth
C. Kremser
D. Poiseuille

A

B. Ruth

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22
Q

Brackish water can be purified by the ________ process. Oct 2023

A. Reverse osmosis
B. Sand filter
C. Lime soda
D. Permutit

A

A. Reverse osmosis

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23
Q

In filtration, the use of ‘filter aid’ helps in (Oct 2023)
A. Reducing the filtration pressure
B. Accelerating the rate of filtration
C. Deplugging the filter medium
D. Enhancing the cake porosity in case of a dense impermeable cake

A

C. Deplugging the filter medium

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24
Q

The ratio for the rate of washing to the final rate of filtration in a washing type of plate and frame filter is (Oct 2023)
A. 0.25
B. 0.50
C. 0.75
D. 1.25

A

A. 0.25

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25
Q

Estimate the terminal settling velocity for 80-to-100 mesh particles of limestone (density = 2800 kg/m³) falling in water at 30 °C. (May 2022)
A. 0.14
B. 0.014
C. 14
D. 1.4

A

B. 0.014

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26
Q

Arrange the following stages of fluidization in the increasing order of gas flow.
i. Bubbling regime
ii. Turbulent regime
iii. Slugging regime
iv. Fast fluidization
A. i, ii, iii, iv
B. i, iii, ii, iv
C. i, iv, iii, ii
D. i, iv, ii, iii

A

B. i, iii, ii, iv

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27
Q

A dilute slurry contains small solid food particles having a diameter of 5x10-2 mm which are to be removed by centrifuging. The particle density is 1050 kg/m³ and the solution density is 1000 kg/m³. The viscosity of the fluid is 1.2x10-³ Pa.s. A centrifuge at 3000 rev/min is to be used. The bowl dimensions are b = 100.1 mm, r₁ = 5.00 mm, and r₂ = 30.0 mm. Calculate the expected flow rate in m³/s just to remove these particles.
A. 2.1x10-⁴
B. 3.50x10-⁵
C. 5.83
D. 8.76x10-⁵

A

D. 8.76x10-⁵

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28
Q

_____ moisture content refers to the moisture limit in which a solid can be dried at specific temperature and pressure. (May 2023)

A. free
B. bound
C. critical
D. equilibrium

A

D. equilibrium

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29
Q

The substance moisture exerts equilibrium vapor pressure equals to vapor pressure of liquid is.
A. Bound moisture
B. Unbound moisture
C. Equilibrium moisture
D. None of the mentioned

A

B. Unbound moisture

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30
Q

A solid contains 20% moisture content in wet basis. What will be its value in dry basis?
A. 20%
B. 25%
C. 75%
D. 80%

A

B. 25%

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31
Q

Find the period if the initial and the final moisture content are 50% and 20%. Also the critical moisture content is 30%.
A. Constant rate period
B. Falling rate period
C. Saturated period
D. None of the mentioned

A

B. Falling rate period

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32
Q

A certain amount of wet material (42% moisture) enters a two-stage drier per hour. After the first stage, the moisture is reduced to 25% d.b. How much moisture (wet basis) remains if it is required to recover 90 kg/h of product after the second stage? The total water removal rate of the two-stage drier is 48 kg/h.
A. 9.31%
B. 11.07%
C. 14.55%
D. 18.28%

A

B. 11.07%

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33
Q

What is the relative humidity of the air if the partial pressure of water vapor is 17.65 mm Hg at 25°C?
A. 74%
B. 78%
C. 82%
D. 86%

A

A. 74%

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34
Q

If the specific heats of a gas and a vapor are 0.2 kJ/kg·°K and 1.5 kJ/kg·°K respectively, and the humidity is 0.01; the humid heat in kJ/°kg. is
A. 0.31
B. 0.107
C. 0.017
D. 0.215

A

D. 0.215

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35
Q

At 10:00 AM of a sunny day, Ofelia observed an air temperature of 34°C with 59% relative humidity. At 4:00 PM, rain started. After raining for 1 hour, the clouds lost 20% of its original moisture content. Find the temperature after the rain.
A. 21.0°C
B. 18.0°C
C. 24.0°C
D. 26.0°C

A

A. 21.0°C

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36
Q

Which one of the following is not a type of evaporator?
A. Forced Circulation
B. Natural Circulation
C. Nucleate Boiling
D. Gasketed evaporators

A

D. Gasketed evaporators

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37
Q

The mass in grams of potassium chloride can be dissolved to a liter of 1.5 M KCl solution to reach saturation at 30° is closest to. (May 2022)
A. About 333
B. About 258
C. About 300
D. None of these

A

B. About 258

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38
Q

Which type of evaporator wherein steam enters the tubes and the liquor is heated outside? (Oct 2022)
A. horizontal tube
B. long vertical tube
C. short vertical tube
D. none of the above

A

A. horizontal tube

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39
Q

The purpose of providing a ‘catchall’ in the vapor line of an evaporator is to (May 2023)
A. Create vacuum
B. Regulate the vapor flow
C. Vent the non-condensable gases
D. Arrest the entrained liquid

A

D. Arrest the entrained liquid

40
Q

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

A

A. Decreased capacity

41
Q

Boiling point elevation causes the driving force of evaporation in the fluid to
A. Decrease
B. Increase
C. Remain same
D. Increase tenfold

A

A. Decrease

42
Q

During crystallization, formation of crystal can occur in (May 2023)
A. Saturated solution only.
B. Supersaturated
C. Undersaturated
D. All of the above

A

B. Supersaturated

43
Q

What is the most ideal gas?
A. hydrogen
B. helium
C. neon
D. oxygen

A

B. helium

44
Q

A sample of natural gas containing 80% methane (CH4) and rest nitrogen (N2) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is:
A. CO2: 6.26, CO: 1.56, O2: 3.91, H2O: 15.66, N2: 72.60
B. CO2: 7.42, CO: 1.86, O2: 4.64, N2: 86.02
C. CO2: 6.39, CO: 1.60, O2: 3.99, H2O: 25.96, N2: 72.06
D. CO2: 7.60, CO: 1.90, O2: 4.75, N2: 85.74

A

B. CO2: 7.42, CO: 1.86, O2: 4.64, N2: 86.02

45
Q

A hydrocarbon is burnt with excess air. The Orsat analysis of the flue gas shows 10.81% CO2, 3.78% O2, and 85.40% N2. Calculate the atomic ratio of C:H in the hydrocarbon.
A. 1:2
B. 1:3
C. 1:4
D. 1:5

A

B. 1:3

46
Q

Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO2, 20%CO and 10%O2. The percent excess oxygen used is
A. 20
B. 12.5
C. 0
D. 10

A

C. 0

47
Q

All of the following are assumptions in ideal leaching EXCEPT?
A. The inert solid is not dissolved in the solvent.
B. Sufficient contact time is provided so that all solute is dissolved in the solvent.
C. The concentration of solution in the final stage and in the initial stages are equal.
D. The solute is infinitely soluble in solvent.

A

C. The concentration of solution in the final stage and in the initial stages are equal.

48
Q

In a single stage extraction process, 10 kg of pure solvent S (containing no solute A) is mixed with 30 kg of feed F containing A at a mass fraction xf = 0.2. The mixture splits into an extract phase E and a raffinate phase R containing A at xE = 0.5 and xR = 0.05 respectively. The total mass of the extract phase is (in kg)
A. 6.89
B. 8.89
C. 10
D. 8.25

A

B. 8.89

49
Q

The buoyant force experienced by a body immersed in a fluid is equivalent to
A. The volume of the displaced fluid
B. The weight of the displaced fluid
C. The pressure applied by the displaced fluid
D. The mass of the displaced fluid

A

B. The weight of the displaced fluid

50
Q

The Darcy friction factor is ____ times greater than Fanning friction factor.
A. two
B. three
C. four
D. five

A

C. four

51
Q

What is the friction due to an unseparated boundary layer?
A. Skin friction
B. Friction factor
C. Belt friction
D. Pressure friction

A

A. Skin friction

52
Q

The energy loss over a length of pipeline according to Darcy-Weisbach equation for pipe flow is _____ the mean velocity of flow.
A. Directly proportional to the square of
B. Directly proportional to
C. Inverse proportional to
D. Inverse proportional to the square of

A

A. Directly proportional to the square of

53
Q

A pressure head of 320 meters of water in meters of CCl4 (SG = 1.6) will be
A. 100
B. 200
C. 320
D. 160

A

B. 200

54
Q

Pulverized coal passing through 200-mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 screen will have a dia of ________ mm.
A. 0.007
B. 0.30
C. 50
D. 0.014

A

B. 0.30

55
Q
A
56
Q

A mole of which gas has the smallest volume at 0°C and 1 atm?
A. He
B. CO2
C. SO2
D. Xe

A

C. SO2

57
Q

For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system:
A. decreases as its mole fraction increases
B. increases
C. remains same
D. decreases linearly

A

B. increases

58
Q

It is defined by setting the fixed numerical value of the Boltzmann constant to be 1.380649 x 10-23 J/K units and that is equal to 1/273.16 scale of the triple point of water.
A. Celsius
B. Kelvin
C. Fahrenheit
D. Rankine

A

B. Kelvin

59
Q

A gas is confined in a cylinder by a piston. The initial pressure is 7 bar and the volume is 0.10 m³. The piston is held in place by latches in the cylinder wall. The whole apparatus is placed in a total vacuum. What is the energy change of the apparatus if the restraining latches are removed so that the gas suddenly expands to double its initial volume, the piston striking the other latches at the end of the process?
A. 0 J
B. 70 kJ
C. 140 kJ
D. 200 kJ

A

A. 0 J

60
Q

A mass of air at 330 °C, contained in a cylinder expanded polytropically to 5x its initial volume and 1/8th its initial 1-bar pressure. What is the value of the expansion index?
A. 1.229
B. 1.292
C. 2.192
D. 2.219

A

B. 1.292

61
Q

The rate at which a chemical substance reacts is proportional to its
A. Active mass
B. Molecular weight
C. Equivalent weight
D. Atomic weight

A

A. Active mass

62
Q

With increase in the order of reaction (for all positive reaction orders), the ratio of the volume of mixed reactor to the volume of plug flow reactor (for identical feed composition, flow rate and conversion)
A. increases
B. decreases
C. remains same
D. increases linearly

A

A. increases

63
Q

Which of the following thermocouples is incapable of measuring sub-zero temperatures?
A. chromel-alumel
B. iron-constantan
C. platinum-rhodium
D. copper-constantan

A

C. platinum-rhodium

64
Q

Consider a gas stream at 15°C and 105 kPa that flows through a duct and contains 1.2% CO2 by volume. Pure CO2 is also supplied in the duct at a rate of 0.0917 m3/min at 7°C and 131 kPa. Upon exiting, the gas contains 3.4% CO2. Assume that the inlet and outlet gas have the same condition. What is the volumetric flow rate of the inlet stream (m3/min)?
A. 4.2
B. 5.2
C. 8.2
D. 8.7

A

B. 5.2

65
Q

A coal sample (CV: 32.5 MJ/kg) has 22% VCM, 64% FC, 4% M, 1.4% N, and 1.6% S. It is burned using dry excess air at 28 °C and 1 atm. The stack gas that leaves at 250 °C, 740 mmHg and contains 8.37% CO2, 4.19% CO, and 2.51% H2. What is the mol of dry stack gas for a 100 kg fuel?
A. 23.2
B. 36.3
C. 47.4
D. 52.5

A

D. 52.5

66
Q

A coal sample (CV: 32.5 MJ/kg) has 22% VCM, 64% FC, 4% M, 1.4% N, and 1.6% S. It is burned using dry excess air at 28 °C and 1 atm. The stack gas that leaves at 250 °C, 740 mmHg and contains 8.37% CO2, 4.19% CO, and 2.51% H2. What is the percent excess oxygen?
A. 30
B. 40
C. 50
D. 60

A

B. 40

67
Q

A 100 g ice cube at 0°C is dropped in a kilogram of water at 20°C. Assuming there is no heat transfer with the atmosphere, what is the final temperature of the initial water-ice mixture?
A. 0°C
B. 2°C
C. 11°C
D. 12°C

A

C. 11°C

68
Q

A 900-g ball, initially at 120°C, is submerged in 250 g of water at 20°C and kept inside a coffee-cup calorimeter with a calorimeter constant of 160 J/K. If the temperature of the water rose by 25°C, what is the heat capacity (J/gK) of the ball?
A. 0.39
B. 0.45
C. 0.77
D. 0.83

A

B. 0.45

69
Q

A ton of refrigeration is equivalent to heat removal of ___________.
A. 50 kcal/h
B. 200 BTU/h
C. 200 BTU/min
D. 200 BTU/day

A

C. 200 BTU/min

70
Q

Which of the following has higher isentropic work than the actual?
A. turbine
B. pump
C. compressor
D. condenser

A

A. turbine

71
Q

While holding other factors as constant, what happens to the instantaneous conversion as time progresses if the reaction order is greater or equal to one?
A. increases constantly
B. increases at first then plateaus
C. decreases constantly
D. decreases at first then plateaus

A

B. increases at first then plateaus

72
Q

The buoyant force exerted on an object immersed in fluid is equivalent to __________.
A. Weight of the object
B. Volume of the fluid displaced by the object
C. Weight of the fluid displaced by the object
D. Volume of the object

A

C. Weight of the fluid displaced by the object

73
Q

Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if
A. Mass transfer is accompanied by reaction
B. diffusion of A is in stagnant medium B
C. molecular mean free path is high
D. there is equimolar counter diffusion

A

D. there is equimolar counter diffusion

74
Q

A wall has two layers of materials A and B, each made of a different material. Both the layers have the same thickness. The thermal conductivity of material A is twice that of B. Under the equilibrium, the temperature difference across the layer A is:
A. 6°C
B. 12°C
C. 18°C
D. 24°C

A

B. 12°C

75
Q

When a system considers very thick-walled cylinders, use the ____ mean radius in computing for heat flow.
A. arithmetic
B. logarithmic
C. geometric
D. either b or c

A

B. logarithmic

76
Q

In a heat exchanger, floating head and baffles are provided to _____ and _____ respectively.
A. easily clean the exchanger; relieve stresses caused by thermal expansion
B. relieve stresses caused by thermal expansion; enhance turbulence
C. increase the driving force of heat transfer; easily clean the exchanger
D. enhance turbulence; increase the heat transfer area

A

B. relieve stresses caused by thermal expansion; enhance turbulence

77
Q

Heat transfer co-efficient equation for forced convection, Nu = 0.023Re^0.8Pr^n, is not valid, if the value of:
A. n = 0.4 is used for heating
B. n = 0.3 is used for cooling
C. Reynolds number for the flow involved is > 10000
D. Reynolds number for the flow involved is < 2100

A

D. Reynolds number for the flow involved is < 2100

78
Q

According to Kirchhoff’s Law, for a gray body, the ______ and __________ are equal even if the body is not in thermal equilibrium with its surroundings.
A. absorptivity, reflectivity
B. absorptivity, emissivity
C. emissivity, thermal conductivity
D. reflectivity, thermal conductivity

A

B. absorptivity, emissivity

79
Q

What is the value of Stefan Boltzmann constant in SI units?
A. 5.67 x 10^-8
B. 5.67 x 10^-4
C. 0.1713 x 10^-8
D. 0.1713 x 10^-4

A

A. 5.67 x 10^-8

80
Q

The flow of filtrate through the cake in plate and frame filter press follows a laminar flow. With this, which of the following will be valid?
A. Kozeny-Carman equation
B. Hagen-Poiseuille equation
C. Burke-Plummer equation
D. Fanning’s equation

A

A. Kozeny-Carman equation

81
Q

Which of the following represents the plot of filtrate volume versus time for constant pressure filtration?
A. Parabola
B. Straight line
C. Hyperbola
D. Exponential curve

A

A. Parabola

82
Q

When the solvent dissolves very little of solute, then
A. solvent of low latent heat of vaporization should be used
B. solvent of low freezing point should be used
C. large quantity of solvent is required to extract the solute
D. very small quantity of solvent is required

A

C. large quantity of solvent is required to extract the solute

83
Q

The distribution coefficient of a solute A between solvents B and S is given by Y = 3.2X where Y = mass of A/mass of S in extract and X = mass of A/mass of B in raffinate. S and B are mutually immiscible. A solution containing 30% A in B is to be extracted in a single stage with recovery of 90%. How much S must be supplied per 100 kg of solution to attain the required condition?
A. 175.86 kg
B. 168.75 kg
C. 187.65 kg
D. 196.875 kg

A

D. 196.875 kg

84
Q

Which of the following sets of equipment is not used in liquid-liquid extraction?
A. Pachuka tank
B. Centrifugal extractors
C. Agitated vessels
D. Packed towers

A

A. Pachuka tank

85
Q

The rate determining step in leaching is the _____________.
A. dissolution of solute in solvent
B. diffusion of solvent into the solid particles
C. diffusion of solute towards the surface of the solid
D. diffusion of the solute from the surface towards the bulk of the solvent

A

C. diffusion of solute towards the surface of the solid

86
Q

Diameter to height ratio for a Raschig ring is
A. 1
B. 0.5
C. 2
D. 8

A

A. 1

87
Q

Flooding in a column results due to
A. High pressure drop
B. Low pressure drop
C. Low velocity of the liquid
D. High temperature

A

A. High pressure drop

88
Q

In packed column gas absorption, a transfer unit means that the
A. mole of solute is transferred in a unit height.
B. mass transfer coefficient will approach unity.
C. average driving force is equal to unity.
D. concentration range is equal to average driving force.

A

D. concentration range is equal to average driving force.

89
Q

Which tray type is the cheapest and has the lowest pressure drop?
A. Sieve Tray
B. Bubble-Cap Tray
C. Valve Tray
D. Packed Column

A

A. Sieve Tray

90
Q

Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout). For 98% recovery of acetone, the number of trays required is/are:
A. 7
B. 8
C. 9
D. 10

A

C. 9

91
Q

A gas absorption tower needs to remove 99% of N2O4 in air. The packing will be 16-mm Pall rings. The gas enters at a rate of 1 lbm/s and contains 1.0 weight% N2O4 and 99% air at 300 K. The absorbent consists of water entering at 0.2 lbm/s. The N2O4 reacts readily with water. Assume Kya = 100 lbm N2O4/h-ft^3-atm-ΔY and the capacity of the column at the flood point is 1,000 lbm gas/h-ft^2. The units of y are lbm N2O4/lbm air. Suppose 75% of the flood point is use as operating gas mass velocity, find the diameter of the column.
A. 2.47 ft
B. 3.03 ft
C. 5.31 ft
D. none of these

A

A. 2.47 ft

92
Q

A gas absorption tower needs to remove 99% of N2O4 in air. The packing will be 16-mm Pall rings. The gas enters at a rate of 1 lbm/s and contains 1.0 weight% N2O4 and 99% air at 300 K. The absorbent consists of water entering at 0.2 lbm/s. The N2O4 reacts readily with water. Assume Kya = 100 lbm N2O4/h-ft^3-atm-ΔY and the capacity of the column at the flood point is 1,000 lbm gas/h-ft^2. The units of y are lbm N2O4/lbm air. Calculate the height of a theoretical stage (Hog) and the number of theoretical stages (Nog) assuming that all interface concentration is zero.
A. 5.4 ft, 6.69
B. 6.4 ft, 5.48
C. 7.4 ft, 4.61
D. none of these

A

C. 7.4 ft, 4.61

93
Q

A gas absorption tower needs to remove 99% of N2O4 in air. The packing will be 16-mm Pall rings. The gas enters at a rate of 1 lbm/s and contains 1.0 weight% N2O4 and 99% air at 300 K. The absorbent consists of water entering at 0.2 lbm/s. The N2O4 reacts readily with water. Assume Kya = 100 lbm N2O4/h-ft^3-atm-ΔY and the capacity of the column at the flood point is 1,000 lbm gas/h-ft^2. The units of y are lbm N2O4/lbm air. What is the height of the column?
A. 34.1 ft
B. 35.1 ft
C. 36.1 ft
D. none of these

A

A. 34.1 ft

94
Q

A gas absorption tower needs to remove 99% of N2O4 in air. The packing will be 16-mm Pall rings. The gas enters at a rate of 1 lbm/s and contains 1.0 weight% N2O4 and 99% air at 300 K. The absorbent consists of water entering at 0.2 lbm/s. The N2O4 reacts readily with water. Assume Kya = 100 lbm N2O4/h-ft^3-atm-ΔY and the capacity of the column at the flood point is 1,000 lbm gas/h-ft^2. The units of y are lbm N2O4/lbm air. The total weight of the Pall rings is ___ lbs.
A. 3204
B. 4204
C. 5204
D. none of these

A

C. 5204

95
Q
A

Gnireenigne lacimehc (7 decks)

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