Log mean temperature difference in case of multi-pass shell and tube heat exchanger is always_________________?

More than arithmetic mean value

Less than arithmetic mean value

More than arithmetic mean value

LMTD correction factor is used in heat exchanger design for____________________?

Multipass shell and tube heat exchanger

Counter flow of hot and cold fluids

Liquid gradient over the tray results due to the___________________?

Resistance offered to flow of liquids by caps & risers and the flow of gas

Liquid gradient over a tray can be minimised by________________?

Providing a higher skirt clearance or a higher weir

Decreasing the number of rows of caps through which the liquid flows or by decreasing the velocity of liquid flow past the caps or by reducing the dis

Using split flow, radial flow or cascade flow for column diameter large than 4 ft

(Le/D) for fully open gate valves would be __________________?

Much more than that for fully open globe valves

Much less (say 2% than that for fully open globe valves)

(Le/D) for a Tee (used as elbow, entering branch) would be ____________________?

Less than that for Tee (used as elbow, entering run)

More than that for Tee (used as elbow, entering run)

Larger depth of liquid on the trays of a distillation column_________________?

Results in higher pressure drop per tray

In the design of a shell and tube heat exchanger, the corrosion allowance ____________________?

Need not be provided for non-pressure parts like tie rods, spacers, baffles, supports etc.

For carbon steel and cast iron pressure parts is 1.5 mm (except for tubes) and for severe conditions it is 3 mm

For internal cover and tube sheet is provided on both the sides

In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference ______________________?

Is always more than arithmetic mean value and the geometric mean value

Is always less than arithmetic average value

Is always more than arithmetic mean value and the geometric mean value

Is always less than arithmetic mean value, but more than geometric mean value

May be either more or less than geometric mean and arithmetic mean value depending upon whether the flow of stream is co-current or counter-current

In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a __________________?

Cap pitch of 1.3-2 times the cap diameter

In case of design of a shell and tube heat exchanger___________________?

Minimum cleaning lane of 6.5 mm is provided, when tubes are on a square pitch

Minimum tube sheet thickness (in which tubes are fixed) is equal to the O.D. of the tube upto 15 mm tube diameter; and for > 15 mm tube diameter, tube

O.D. of the tube is 6 to 40 mm while the tube lengths used are 0.5, 2.5, 3.0, 4.0, 5.0, 6 metres

In case of a continuous distillation column, increase in reflux ratio may result in the______________?

Lower fixed charges for the column

Greater cost for the reboiler heat supply

Greater cost for the condenser coolant

324 + Mcqs in Process Equipment & Plant Design for Chemical in Chemical Engineering Page 4 McqOptions

151.	Maximum acceptable total liquid gradient over a tray is about _______________ mm?
A.	5.5
B.	12.5
C.	30.5
D.	45.5
Answer» C. 30.5

152.	Lug support is meant for supporting _______________ vessels?
A.	Large horizontal cylindrical
B.	Tall but empty
C.	Small
D.	Thick walled tall
Answer» D. Thick walled tall

153.	Low pressure steam (with saturation temperature between 105 to 120°C) is usually used in the vacuum evaporators, which normally employ a vacuum of about _______________ mm Hg (referred to a 760 mm mercury barometer)?
A.	250
B.	450
C.	650
D.	750
Answer» D. 750

154.	Longitudinal stress induced in a thin walled cylindrical storage vessel is __________________?
A.	pD/2t
B.	pD/4t
C.	pD/3t
D.	pD/6t
Answer» C. pD/3t

155.	Log mean temperature difference in case of multi-pass shell and tube heat exchanger is always_________________?
A.	Less than arithmetic mean value
B.	More than arithmetic mean value
C.	More than geometric mean value
D.	Both B. & C.
Answer» B. More than arithmetic mean value

156.	LMTD correction factor is used in heat exchanger design for____________________?
A.	Double pipe heat exchanger
B.	Multipass shell and tube heat exchanger
C.	Fouling fluids
D.	Counter flow of hot and cold fluids
Answer» E.

157.	________________ liquor is best handled in a long tube vertical evaporator ?
A.	Foamy
B.	Scaling
C.	Viscous
D.	Salting
Answer» B. Scaling

158.	Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than ______________ kilolitres?
A.	20
B.	30
C.	45
D.	85
Answer» D. 85

159.	Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or ______________ times the column diameter, whichever is lower?
A.	2.5-3.0
B.	5-7.5
C.	10-12.5
D.	15-20
Answer» B. 5-7.5

160.	Liquid gradient over the tray results due to the___________________?
A.	Resistance offered to flow of liquids by caps & risers and the flow of gas
B.	Low gas velocity
C.	Large plate spacing
D.	Large reflux ratio
Answer» B. Low gas velocity

161.	Liquid gradient over a tray can be minimised by________________?
A.	Providing a higher skirt clearance or a higher weir
B.	Decreasing the number of rows of caps through which the liquid flows or by decreasing the velocity of liquid flow past the caps or by reducing the dis
C.	Using split flow, radial flow or cascade flow for column diameter large than 4 ft
D.	All A., B. and C.
Answer» E.

162.	Length to diameter ratio of most rotary driers is in the range of____________________?
A.	1 to 2
B.	4 to 10
C.	10 to 20
D.	20 to 30
Answer» C. 10 to 20

165.	(Le/D) for couplings and unions would be_______________?
A.	60
B.	200
C.	350
D.	Negligible
Answer» E.

168.	Le/D) for 90° elbow (medium radius) and 90°square elbow would be respectively around___________________?
A.	25 and 60
B.	3 and 5
C.	100 and 250
D.	250 and 600
Answer» B. 3 and 5

170.	Large process vessels operating under extreme temperature and pressure conditions are normally clad/ lined with materials like stainless steel, aluminium, nickel & its alloys, copper & its alloys and titanium. The cladding thickness is generally about ______________ percent of the total thickness?
A.	1 to 5
B.	10 to 20
C.	30 to 40
D.	40 to 50
Answer» C. 30 to 40

163.	(Le/D) for fully open gate valves would be __________________?
A.	Much more than that for fully open globe valves
B.	Much less (say 2% than that for fully open globe valves)
C.	Around 7
D.	Both B. and C.
Answer» E.

164.	(Le/D) for fully open globe value may be around__________________?
A.	10
B.	25
C.	75
D.	300
Answer» E.

166.	(Le/D) for a Tee (used as elbow, entering run) would be around _______________________?
A.	5
B.	60
C.	160
D.	200
Answer» C. 160

167.	(Le/D) for a Tee (used as elbow, entering branch) would be ____________________?
A.	Less than that for Tee (used as elbow, entering run)
B.	More than that for Tee (used as elbow, entering run)
C.	Around 90
D.	Both B. and C.
Answer» E.

169.	Larger depth of liquid on the trays of a distillation column_________________?
A.	Leads to high tray efficiency
B.	Results in higher pressure drop per tray
C.	Both A. & B.
D.	Neither A. or B.
Answer» D. Neither A. or B.

171.	Lap joints are preferred for plates having thickness _______________ mm?
A.	< 12.5
B.	> 3
C.	> 5
D.	5-10
Answer» C. > 5

172.	Joint efficiency (J) for a seamless pipe is_______________?
A.	1
B.	0.85
C.	1.5
D.	< 0.5
Answer» B. 0.85

173.	It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than _________________?
A.	0.99
B.	0.95
C.	0.80
D.	0.55
Answer» D. 0.55

174.	____________ is the determining factor for the number of bubble caps to be used per tray?
A.	Permissible slot velocity
B.	Tray diameter
C.	Liquid load
D.	Vapor load
Answer» B. Tray diameter

175.	In the downcomer of a distillation column, the minimum recommended residence time is about _______________ seconds?
A.	2.5
B.	5
C.	12.5
D.	17.5
Answer» C. 12.5

Explore topic-wise MCQs in Chemical Engineering.

Maximum acceptable total liquid gradient over a tray is about _______________ mm?

Lug support is meant for supporting _______________ vessels?

Low pressure steam (with saturation temperature between 105 to 120°C) is usually used in the vacuum evaporators, which normally employ a vacuum of about _______________ mm Hg (referred to a 760 mm mercury barometer)?

Longitudinal stress induced in a thin walled cylindrical storage vessel is __________________?

Log mean temperature difference in case of multi-pass shell and tube heat exchanger is always_________________?

LMTD correction factor is used in heat exchanger design for____________________?

________________ liquor is best handled in a long tube vertical evaporator ?

Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than ______________ kilolitres?

Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or ______________ times the column diameter, whichever is lower?

Liquid gradient over the tray results due to the___________________?

Liquid gradient over a tray can be minimised by________________?

Length to diameter ratio of most rotary driers is in the range of____________________?

(Le/D) for fully open gate valves would be __________________?

(Le/D) for fully open globe value may be around__________________?

(Le/D) for couplings and unions would be_______________?

(Le/D) for a Tee (used as elbow, entering run) would be around _______________________?

(Le/D) for a Tee (used as elbow, entering branch) would be ____________________?

Le/D) for 90° elbow (medium radius) and 90°square elbow would be respectively around___________________?

Larger depth of liquid on the trays of a distillation column_________________?

Large process vessels operating under extreme temperature and pressure conditions are normally clad/ lined with materials like stainless steel, aluminium, nickel & its alloys, copper & its alloys and titanium. The cladding thickness is generally about ______________ percent of the total thickness?

Lap joints are preferred for plates having thickness _______________ mm?

Joint efficiency (J) for a seamless pipe is_______________?

It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than _________________?

____________ is the determining factor for the number of bubble caps to be used per tray?

In the downcomer of a distillation column, the minimum recommended residence time is about _______________ seconds?

In the design of a shell and tube heat exchanger, the corrosion allowance ____________________?

In the design of a paddle agitator, the ratio (paddle dia/tank dia) is normally taken as___________________?

In the design of a bag filter, the gas temperature is an important consideration, as it affects the___________________?

In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference ______________________?

In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a __________________?

In sieve plate column, holes are drilled or punched in sizes ranging from 2.5 to 12 mm (5 mm being widely used). The hole pitch is normally ______________ times the hole diameter to give the required hole area?

In shell and tube heat exchangers, straight tie rods are used to_________________?

In packed towers provided with saddle packing, liquid redistributors are positioned at every _______________ times column diameter or 6 metres whichever is less?

In packed towers provided with pall rings liquid redistributors are positioned at heights of every 6 metres or 5-10 times the column diameter, whichever is less. Maximum size of the pall rings should not exceed _______________________ of the column diameter?

In packed absorption tower, onset of flooding usually occurs at a pressure drop of about ______________ mm of water column per metre height of packing?

In most of the shell and tube heat exchangers, the tube pitch is generally ______________ the tube diameter?

In hydrostatic testing of welded pipe (for leakage, strength etc.) the ratio of minimum hydrostatic test pressure to internal design pressure is around __________________?

In distillation columns, bubble caps are held in place over trays by ________________?

In condenser, the cooling water is passed in the tube side in a pass arrangement, because________________?

In common bubble cap distillation column design practice, riser area is approximately equal to (where, Aa = Annular passage area, and Sa = Slot area) ?

In case of saddle packing (e.g., berl and intralox saddles), the maximum size of the packing should not exceed ______________ of the column diameter?

In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ _____________ cms?

In case of design of a shell and tube heat exchanger___________________?

In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about _______________ cms?

In case of a ‘thin’ pressure vessel, the ratio of its diameter to wall thickness is_________________?

In case of a shell and tube heat exchanger, the minimum shell thickness for carbon steel (inclusive of corrosion allowance) depends on shell diameter and is in the range of ________________ mm?

In case of a shell and tube heat exchanger, the effect of L/D on inside film heat transfer coefficient (hi) vanishes after a Reynold number of_____________?

In case of a continuous distillation column, increase in reflux ratio may result in the______________?

In case of 1.5″ heat exchanger tubes, the inside flow area _____________ with decrease in BWG?

In actual operation of distillation column, the vapour is not distributed uniformly among the bubble caps, primarily because of the_______________?

176.	In the design of a shell and tube heat exchanger, the corrosion allowance ____________________?
A.	Need not be provided for non-pressure parts like tie rods, spacers, baffles, supports etc.
B.	For carbon steel and cast iron pressure parts is 1.5 mm (except for tubes) and for severe conditions it is 3 mm
C.	For internal cover and tube sheet is provided on both the sides
D.	All A., B. & C.
Answer» E.

177.	In the design of a paddle agitator, the ratio (paddle dia/tank dia) is normally taken as___________________?
A.	0.1
B.	0.8
C.	0.25
D.	0.5
Answer» C. 0.25

178.	In the design of a bag filter, the gas temperature is an important consideration, as it affects the___________________?
A.	Gas density
B.	Gas viscosity
C.	Fibre selection
D.	All A., B. & C.
Answer» E.

179.	In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference ______________________?
A.	Is always less than arithmetic average value
B.	Is always more than arithmetic mean value and the geometric mean value
C.	Is always less than arithmetic mean value, but more than geometric mean value
D.	May be either more or less than geometric mean and arithmetic mean value depending upon whether the flow of stream is co-current or counter-current
Answer» B. Is always more than arithmetic mean value and the geometric mean value

180.	In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a __________________?
A.	Clearance of 25-75 mm
B.	Cap pitch of 1.3-2 times the cap diameter
C.	Either A. or B.
D.	Neither A. nor B.
Answer» D. Neither A. nor B.

181.	In sieve plate column, holes are drilled or punched in sizes ranging from 2.5 to 12 mm (5 mm being widely used). The hole pitch is normally ______________ times the hole diameter to give the required hole area?
A.	0.5 to 1.5
B.	2.5 to 4.0
C.	5 to 10
D.	10 to 15
Answer» C. 5 to 10

182.	In shell and tube heat exchangers, straight tie rods are used to_________________?
A.	Hold baffle in space
B.	Fix the tubes in position
C.	Account for thermal strain
D.	None of these
Answer» B. Fix the tubes in position

183.	In packed towers provided with saddle packing, liquid redistributors are positioned at every _______________ times column diameter or 6 metres whichever is less?
A.	2-3
B.	5-8
C.	10-15
D.	20-25
Answer» C. 10-15

184.	In packed towers provided with pall rings liquid redistributors are positioned at heights of every 6 metres or 5-10 times the column diameter, whichever is less. Maximum size of the pall rings should not exceed _______________________ of the column diameter?
A.	1/10-1/15th
B.	1/5-1/10th
C.	1/20-1/30th
D.	1/2 to 1/4th
Answer» B. 1/5-1/10th

185.	In packed absorption tower, onset of flooding usually occurs at a pressure drop of about ______________ mm of water column per metre height of packing?
A.	25-50
B.	50-75
C.	200-250
D.	750-1000
Answer» C. 200-250