Multiple Choice Questions and Answers Chemical Engineering Process Equipment and Plant Design
01. In a multipass shell and tube heat exchanger, the problem of differential expansion between the shell and tube passes is taken care of by using a
(A) U-bend
(B) Floating head tube sheet
(C) Either (A) or (B)
(D) Neither (A) nor (B)
Answer: Option C
02. Vertical storage vessels are never supported by __________ support.
(A) Bracket
(B) Saddle
(C) Skirt
(D) Lug
Answer: Option B
03. The LMTD correction factor (FT) is applied in __________ heat exchangers.
(A) 1-1 concurrent
(B) Double pipe
(C) All multipass
(D) All (involving liquid/liquid heat transfer)
Answer: Option C
04. The minimum baffle height should be
(A) Equal to the impeller diameter
(B) Twice the impeller diameter
(C) Twice the tank diameter
(D) 3/4 of the tank height
Answer: Option B
05. What is the value of ‘q’ for saturated vapor feed to a distillation column? (where q = fraction of the feed stream that is liquid.)
(A) 0
(B) 1
(C) < 0
(D) > 1
Answer: Option A
06. In actual operation of distillation column, the vapour is not distributed uniformly among the bubble caps, primarily because of the
(A) Liquid gradient on the tray
(B) Lower skirt clearance
(C) Lower static submergence
(D) Small downcomer liquid seal
Answer: Option A
07. 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: Option B
08. Pick out the wrong statement pertaining to shell and tube heat exchanger.
(A) Clearance between shell & baffles and between tube & baffles should be minimum to avoid by-passing of the fluid, but it should be enough to permit the removal of tube bundle
(B) Baffles are supported independently of the tubes by tie rods and positioned by spacers
(C) Tie rods are fixed at one end in the tube sheet by making blind holes and the minimum number of tie rods is 4 with at least 10 mm diameter
(D) Bracket supports are used for horizontal shell, while saddle support is used for vertical shell
Answer: Option D
09. Pick out the wrong statement pertaining to the design of a horizontal tube evaporator.
(A) It is unsuitable for concentrating those liquids, which form a scale or deposit salt
(B) It is suitable for process, in which the final product is a liquor instead of solid
(C) Its usual dimensions are: tube dia = 2-3 cms; evaporator body dia = 1-4 metres and evaporator height = 2.5-4 metres
(D) Liquor flows inside the tube, while the steam is outside submerging the tube
Answer: Option D
10. In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ __________ cms.
(A) 1.2
(B) 0.5
(C) 3.8
(D) 6.8
Answer: Option C
11. Practical dividing line between a ductile and brittle materials is suggested, when the ultimate elongation is about 5%. Generally, larger the knuckle radius, stronger is the corner torus section of a head. The knuckle radius provided should be less than __________ of the head.
(A) 6% of I.D.
(B) 3 times the thickness
(C) Either (A) or (B), whichever is larger
(D) Either (A) or (B), whichever is smaller
Answer: Option C
12. In a distillation column, bubble caps are located on trays with a pitch of __________ times the outside diameter of the caps.
(A) 1.3 to 2
(B) 1.6 to 2
(C) 2.5
(D) 1.5 to 3
Answer: Option A
13. The LMTD correction factor (FT) is defined as the
(A) Ratio of true temperature difference to the LMTD
(B) Ratio of LMTD to the true temperature difference
(C) Differenced of true temperature difference and the LMTD
(D) Geometric mean of the true temperature difference and the LMTD
Answer: Option A
14. __________ closure is the weakest enclosure for cylindrical vessels.
(A) Hemispherical
(B) Torispherical
(C) Conical or flat plate
(D) Elliptical
Answer: Option C
15. Which of the following is the best tube material from thermal conductivity point of view alone?
(A) Aluminium
(B) Stainless steel
(C) Copper
(D) Carbon steel
Answer: Option C
16. Coming soon.
17. Power required for agitation depends upon the
(A) Height & properties of the liquid
(B) Agitator type & speed of agitation
(C) Size of agitator & the tank
(D) All (A), (B) and (C)
Answer: Option D
18. High pressure fluid in a shell and tube heat exchanger should preferably be routed through the
(A) Tubes to avoid the expansion of high pressure shell construction
(B) Shell side for smaller total pressure drop
(C) Shell side, if the flow is counter-current and tube side if the flow is co-current
(D) Shell side for large overall heat transfer co-efficient
Answer: Option A
19. Stage efficiency for packed tower varies with the
(A) Type & size of packing
(B) Fluid rates and fluid properties
(C) Operating pressure and column diameter
(D) All (A), (B) and (C)
Answer: Option D
20. What is the slope of the feed line, if the feed to a distillation column is a saturated liquid?
(A) 0
(B) ∞
(C) > 1
(D) < 1
Answer: Option B
21. Tube wall thickness depends on the corrosiveness of the fluids and their operating pressure & temperature and is specified by Birmingham wire gauge (B.W.G)-a number which varies from 8 to 18 with the numbers 14 and 16 being more commonly used. Outside diameter of tubes varies from about 15 to 50 mm; however a tube of less than __________ mm outside diameter is generally not recommended for fouling fluids.
(A) 16
(B) 19
(C) 28
(D) 38
Answer: Option B
22. __________ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids.
(A) Sieve plate
(B) Packed
(C) Bubble cap plate
(D) None of these
Answer: Option B
23. In hydrostatic testing of welded pipe (for leakage, strength etc.) the ratio of minimum hydrostatic test pressure to internal design pressure is around
(A) 0.5
(B) 1.5
(C) 2.5
(D) 3.5
Answer: Option B
24. For a cylindrical shell, (subject to the thickness of uppermost course being more than the minimum for dia of the tank in question), the thickness of the courses of shell
(A) Decreases upwards
(B) Increases upwards
(C) Remains same throughout
(D) May decrease or increase upwards depending upon whether vacuum or positive pressure would be maintained inside the shell
Answer: Option A
25. In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is
(A) Called tube pitch
(B) Called tube clearance
(C) Always less than the diameter of the tube
(D) None of these
Answer: Option A