Process Equipment And Plant Design PDF

PROCESS EQUIPMENT AND PLANT DESIGN d. 10 to 15 11. In case of a shell and tube heat exchanger, the minimum shell thickness for SECTION 1...

PROCESS EQUIPMENT AND PLANT DESIGN d. 10 to 15 11. In case of a shell and tube heat exchanger, the minimum shell thickness for SECTION 1 carbon steel (inclusive of corrosion allowance) depends on shell diameter and 1. Fresh water carrying pipelines in chemical industries are coloured with is in the range of __________ mm. _______ color. a. 3-5 a. sea green b. 5-11 b. brown c. 8-15 c. yellow d. 12-18 d. red 12. The stress developed in a material without any permanent set is called the 2. Which of the following material is seldom used for pressure vessel a. ultimate stress construction ? b. yield stress a. Rimmed still c. elastic limit b. Mild steel d. breaking stress c. Killed steel d. Semi-killed steel 13. In a shell and tube heat exchanger, the 'tube pitch' is defined as the a. O.D. of the tube for square pitch. 3. The ratio of shear stress to shear strain is called b. shortest distance between two adj acent tube holes. a. bulk modulus c. shortest centre to centre distance between adjacent tubes. b. shear modulus d. none of these. c. modulus of rigidity d. modulus of elasticity 14. Which of the following is not a valid assumption in continuous binary distillation for calculating the number of equilibrium stages by Mc-Cabe- 4. 25 per cent cut segmental baffle means that the baffle Thiele's method ? a. height is 75% of the I.D. of the shell. a. Sensible heat changes for vapour & liquid are negligibly small. b. height is 25% of the I.D. of the shell. b. Reflux is not a saturated liquid. c. spacing is 75% of its height. c. Molar latent heat of the two components are equal. d. width is 25% of its height. d. Heat of mixing of normal liquid is assumed to be zero. 5. Liquid/petroleum fuel storage tanks are built underground (as in case of 15. Overall distillation column efficiency for most of the refinery columns can petrol pumps), when the storage capacity is less than ______ kilolitres. be given by (for μ = 0.07 - 1.4 cp and relative volatility < 4) (where η = overall a. 20 column efficiency, % μ = molal average viscosity of feed at average column b. 30 temperature and pressure, cp Δp = pressure drop per tray, psi) c. 45 a. η = 17 - 61.1 log μ d. 85 b. c. η = 1.66 - 0.25 log μ 6. for fully open globe value may be around d. η = 0.25 log μ - 1.67 a. 10 b. 25 16. The value of fouling factor depends upon the c. 75 a. characteristic of process fluid. d. 300 b. velocity of process fluid containing suspended solids. c. suspended solids in the fluid. 7. Lug support is d. all (a), (b) and (c). a. the most suitable for thick vertical vessel. b. same as bracket support. 17. In case of bubble cap distillation column of diameter greater than 1.2 metres, c. provided usually for vessels of much smaller height than skirt the cap diameter is roughly about __________ cms. supported vessels. a. 10 d. all (a), (b) and (c). b. 20 c. 30 8. Pick out the wrong statement pertaining to the use of valve tray, seive tray d. 35 and bubble cap trays in continuous distillation column. a. Bubble cap trays though most expensive are the best in situations, 18. Tube side pressure drop in a 1-2 heat exchanger (for turbulent flow of fluids where low vapour rates is to be handled and a positive liquid seal is through the tubes) is about __________ times, that in a 1-1 heat exchanger essential at all flow rates. having the same size & number of tubes and operated at the same liquid flow b. Murphree efficiency of all the three trays are nearly equal, however rate. the peak efficiency is generally higher for seive and valve trays than a. 2 the bubble cap. b. 1/2 c. Maintenance cost for valve and seive trays are comparatively more c. 4 than bubble cap tray due to their relatively complicated construction d. 8 features. d. Valve trays have the highest turn down ratio (i.e. the ratio of the 19. To keep the power input constant for a stirred vessel operating under fully highest to the lowest vapour flow rates) and thus provides the developed turbulent flow conditions (constant power number), if the impeller maximum flexible operating range. diameter is increased by 20%, the impeller speed should be decreased by a factor of 9. With increase in the number of shell passes, the value of FT a. (1.2)3/2 a. increases b. (1.2)3/5 b. decreases c. (1.2)2/3 c. remains same d. (1.2)5/3 d. remains same, only if the number of tube passes does not change. 20. In a heat exchanger, shell side fluid velocity can be changed by changing 10. Holes of a sieve tray are arranged in triangular pitch of __________ times the tube the hole diameter. a. layout a. 1.5 to 2 b. pitch b. 2.5 to 5 c. both (a) & (b) c. 5 to 10 d. neither (a) nor (b)  c. 60° d. 80° 21. Where does the maximum tensile strength occur in a thick cylindrical vessel subjected to internal pressure ? a. At the inner surface. 32. Smaller sized packings are generally dumped to the packed columns, and b. At the mid thickness of the cylindrical wall. the large ones of size greater than __________ mm are stacked individually, c. At the outer surface. which provides better control over bed porosity and offers lower gas pressure d. None of these. drop. a. 25 22. It is not desirable to design a heat exchanger for LMTD correction b. 50 factor, FT, of less than c. 75 a. 0.99 d. 150 b. 0.95 c. 0.80 33. Shell side heat transfer co-efficient in case of square pitch as compared to d. 0.55 the triangular pitch under similar condition of fluid flow and tube size is a. more 23. A rivetted joint does not fail by __________ of rivets. b. same a. tearing c. less b. shearing d. twice c. tearing of the plate across a row d. none of these 34. Correct use of 'factor of safety' is very important in equipment design. It is defined as the ratio of the 24. Triangular pitch tube layout as compared to square pitch in a shell and tube a. ultimate stress to breaking stress. heat exchanger b. ultimate stress to working stress. a. permits the use of less tubes in a given shell diameter. c. working stress to ultimate stress. b. facilitates comparatively easier external cleaning because of large d. none of these. clearance. c. permits the use of more tubes in a given shell diameter. 35. The operating velocity in the absorption tower is usually 40-50% of the d. both (b) and (c). flooding velocity. Packed absorption towers are normally designed for a pressure drop of about __________ mm of water column per metre height of 25. Bracket supports are the most suitable for supporting __________ vessels. packing. a. thick walled vertical a. 1-5 b. horizontal b. 20-40 c. thin shperical (e.g. Horton sphere) c. 100-150 d. none of these d. 1000-1500 26. In a multipass shell and tube heat exchanger, the shell side cross flow area 36. __________ tray arrangement is recommended for distillation column does not depend upon having diameter upto 4 ft. a. baffle spacing a. Radial flow b. clearance b. Cross flow c. pitch c. Split flow d. none of these d. Cascade 27. Two iron pipes of the same nominal diameter but different schedule 37. What is the value of 'q' for saturated liquid feed to a distillation column ? numbers will have the same a. 0 a. inside diameter b. 1 d. none of these 38. In perforated plate towers, the 28. Steam side heat transfer co-efficient for design consideration under ordinary a. hole sizes may be around 1/8" or 3/16". condition can be assumed to be about __________ kcal/hr.m2.°C. b. total hole area may be around 6 to 15% of tower cross-sectional area. a. 1250 c. pressure drop is less compared is similar bubble cap towers. b. 2500 d. all (a), (b) and (c). c. 7500 d. 15000 39. The main purpose of providing stepping on the trays is to a. increase the residence time. 29. Pick out the wrong statement b. decrease the pressure drop. a. For all the cylindrical process vessels operating above atmospheric c. facilitate handling of large flow rate of liquid. pressure, formed heads are used for closing the vessel. d. improve the flow condition. b. Fouling factor of river water is less than that of sea water. c. Risers provided in bubble cap trays in the distillation column 40. The operating pressure drop range in a bag filter is about __________ mm facilitate the flow of both liquid and vapor. water gauge. d. both (b) and (c). a. 50-150 b. 5-10 30. Lessing ring is formed by the addition of a partition across the centre of a c. 500-1500 raschig ring, which results in an area increase of about __________ percent. d. 1500-2500 a. 5 b. 20 41. The ends of a cylinderical vessel can be closed by a head, which can be one c. 35 of the four shapes. For the same thickness, choose the one which can withstand d. 55 the highest pressure. a. Flat plate 31. In chemical process equipments, the conical bottom heads used, usually has b. Hemispherical an apex angle of c. Torispherical a. 20° d. Ellipsoidal b. 40°  SECTION 2 42.For laminar flow (NRe < 2100) in steel pipe, the optimum inside pipe 1. Needle valves are generally not used for diameter is given by a. very large diameter pipes. a. Di, opt = 3 Q0.36 ρ0.18 b. high pressure throttling service. b. Di, opt = 3.9 Q0.45. ρ0.23 c. very accurate flow control. c. Di, opt = 7.6 Q0.36. ρ0.9 d. smaller sizes of pipe. d. Di, opt = 3 Q0.36. ρ1.86 μ0.08 43. Pick out the correct statement. 2. Height equivalent to a theoretical plate (HETP) is the height of packing that a. When highly corrosive fluids are to be handled, the plate towers will give the same separation as one theoretical plate in gas-liquid mass transfer prove to be cheaper and easier to construct than packed tower. operations like distillation, absorption/stripping and b. Packed towers are generally preferred over plate towers, if the humidification/dehumidification. HETP which is experimentally determined, liquids have a foaming tendency. depends upon the c. The pressure drop through the packed towers is generally more than a. flow rates of each fluid. the pressure drop through plate towers designed for same duty. b. type and size of packing. d. none of these. c. concentration of each fluid. d. all a, b & c. 44. Wall thickness of schedule 40 pipe as compared to that of schedule 80 pipe is 3. Pick out the wrong statement. a. more a. Safety valves are provided in heat exchangers for removal of non- b. less conden-sables. c. same b. Liquid metals and dowtherm are used for very high temperature d. cither (a) or (b); depends upon the I.D. of the pipe heating. c. In a shell and tube heat exchanger, high pressure fluid is generally 45. Pick out the wrong statement pertaining to the design of a basket type routed through the tube. evaporator. d. A loop seal or U-seal is provided in a vertical condenser sub-cooler a. It is used for high viscosity liquor having large rate of scaling. to prevent quick draining of the condensate. b. The tube bundle is suspended on bracket. c. There is no central downtake. 4. With increase in gas flow rate to fabric surface area ratio (Nm3/hr/m2 fabric d. Downtake is formed by the annular space between the bundle and surface area), the size & the cost of a bag filter the shell. a. increases b. decreases 46. Pick out the wrong statement pertaining to the design of the bubble cap tray c. remain unaffected of a distillation column to give stable operation and even vapour distribution. d. none of these a. The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation. 5. A head comprises of straight flange section, corner torus, section and central b. Tendency towards stable operation is increased by increasing the dished section. Crown radius and knuckle radius in a head is related respectively skirt clearance of the caps, lowering the rate of liquid flow per unit to the plate width or increasing the spacing between the caps. a. central dished section and corner torus section. c. The dimensionless ratio of liquid gradient to pressure drop head b. corner torus section and central dished section. caused by the bubble cap assembly should be less than 0.4. c. central dished section and straight flange section. d. none of these. d. straight flange section and corner torus section. 47. Speed of the drum of the rotary vacuum filter normally ranges from 6. Number of evaporators which can be used in service in a multiple effect __________ rpm. evaporation system is limited by the a. 0.1 to 2 a. practical limit reached, due to low heat transfer rate because of b. 5 to 7 inadequate temperature difference. c. 3 to 8 b. economic limit reached, when the plant cost exceeds the saving of d. 8 to 15 steam. c. both (a) & (b). 48. A stuffing box is used for d. neither (a) nor (b). a. absorbing the contraction/expansion of pipeline due to temperature changes. 7. Which of the following is used to set the diameter of the distillation column? b. prevention of fluid leakage around moving parts. a. Number of theorectical plates. c. facilitating smooth opening and closing of a valve. b. Static submergence. d. reducing the resistance of fluid flow. c. Allowable vapour velocity. d. Length of straight rectangular weir on cross-flow tray. 49. Pressure drop (Δp) and the superficial gas mass velocity (G) in case of packed absorption tower operating in the preloading range are related as 8. Ponchon Savarit method is based on the use of enthalpy concentration a. Δp = G diagram, which contains the bubble point curve (saturated liquid curve), dew b. Δp = G0.5 point curve (saturated vapour curve) and equilibrium tie lines. As compared to c. Δp = G2 McCabe-Thiele's method, this method a. is more accurate in finding the number of equilibrium stages. b. accounts for the enthalpy changes in the process. c. facilitates direct calculation of heat load on reboiler & condenser d. from, the diagram used in this method. 50. Pick out the wrong statement. In an agitated vertical cylinderical reaction d. all 'a', 'b' & 'c'. vessel, the a. ratio of liquid depth to tank diameter (i.e. the filling ratio) 9. The optimum size ratio for two mixed reactors in series depends on the recommended for most purposes is 1. kinetics of the reaction and the conversion level. For reaction orders more than b. filling ratio for dispersing gas in a liquid is 2 for sufficiently long one, the contact period. a. equal sized reactors are the best. c. flat bottom and conical bottom vessels have low agitation efficiency b. smaller reactor should come first. for agitation of heavy solids in liquids. c. larger reactor should come first. d. dished bottom vessel has very high power consumption. d. none of these. 10. In a shell and tube heat exchanger, tube side __________ of the mass b. -q/(1-q) velocity. c. -q/(q-1) a. heat transfer co-efficient is proportional to 0.8th power d. none of these b. pressure drop is proportional to the square c. both 'a' & 'b' 21. Speed of industrial paddle agitator ranges from __________ rpm. d. neither 'a' nor 'b' a. 1 to 5 b. 20 to 100 c. 500 to 750 d. 1000 to 2000 11. Which of the following is not a graphical method (but is an analytical 22. method) for the calculation of theoretical number of stages in case of continuous __________ strain is measured using a 'strain rosetter'. binary distillation? a. Volumetric a. Sorel-Lewis method. b. Shear b. McCabe-Thiele's method. c. Linear c. Ponchon-Savarit method. d. none of these d. none of these. 23. Thin spherical shells subjected to internal pressure, develop __________ 12. Saddle supports are used for supporting __________ vessels. stresses. a. horizontal cylinderical a. radial b. tall vertical b. circumferential c. thick walled vertical c. both (a) & (b) d. thick spherical d. neither (a) nor (b) 13. The diameter of a propeller agitator used in agitation tank ranges from 24. With increase in the reflux ratio for a fixed production from a continuous __________ percent of the tank diameter and its peripherial speed is normally binary distillation column, the __________ decreases. 300 to 500 metres/minute. a. fixed charges initially a. 5 to 10 b. running cost of cooling water for condenser b. 15 to 30 c. vapour & liquid load both c. 40 to 50 d. running cost of steam for reboiler d. 55 to 75 25. The slope of operating line in the rectifying section of a distillation column 14. In packed towers provided with saddle packing, liquid redistributors are is unity, if the reflux ratio is positioned at every __________ times column diameter or 6 metres whichever a. 0 is less. b. ∞ a. 2-3 c. 1 b. 5-8 d. minimum c. 10-15 d. 20-25 26. Vertical vessels are not supported by a. brackets 15. Optimum reflux ratio in a continuous distillation column is determined by b. skirts the c. columns a. maximum permissible vapour velocity. d. saddles b. flooding limit of the column. c. total cost consideration (fixed cost of the column plus the cooling 27. With increase in pressure drop (for a given particle size), the dust collection water & steam cost). efficiency of a cyclone separator will d. none of these. a. increase b. decrease 16. Cooling water fouling factors vary in the range of 0.001 to 0.003 c. remain unaffected a. (BTU/hr.ft2. °F)-1 d. increase or decrease depending on the nature of the dust. b. (kcal/hr.m2.°C)-1 c. (W/m2.°K)-1 28. Spherical shaped pressure vessel is considered to be the most ideal, because d. (kcal/hr. m. °C)-1 it can a. withstand higher pressure for a given metallic shell thickness. 17. Minimum recommended baffle spacing in a shell and tube heat exchanger b. be fabricated very easily. is about (where, D = shell diameter ) c. be designed without wind load considerations. a. 0.2 D d. be supported very easily. b. 0.5 D c. 0.66 D 29. An adequate clearance between the tray and the shell wall of a distillation d. 0.80 D column is provided to a. drain the liquid from the tray when the unit is not in operation. 18. The maximum liquid gradient over a tray must not exceed b. allow for thermal expansion and facilitate installation. a. 0.5" -1.25". c. avoid back-trapping. b. 2"-3.5". d. none of these. c. 5". d. half the tray spacing. 30. Overall tray efficiency of a distillation column is the ratio of the number of a. overall gas transfer units to the number of ideal trays required. 19. An underdesigned steam trap will b. ideal trays required to the number of real trays required. a. waste steam. c. real trays required to the number of ideal trays required. b. destroy itself of acceleration wear due to rapid recycling. d. none of these. c. back up condensate and cause water hammer in steam line. d. none of these. 31. Pick out the wrong statement about the design of a sieve plate column. a. An increased weir height improves the tray efficiency at the cost of 20. The slope of the feed line in distillation opeartion is given by (where, q = high plate pressure drop; optimum wear height being 40-90 mm for fraction of the feed stream that is liquid.) column pressure above atmospheric and 6-12 mm for vacuum a. -q columns.  b. For segmental downcomers, the chord length is 60-80% of the c. around 7. column diameter. An initial value of downcomer area of 12% is d. both (b) and (c). taken in the design. c. Width of the calming section provided at the inlet and outlet sides 40. LMTD correction factor is used in heat exchanger design for of the plate is 75 mm for column diameter below 1.5 metres and 100 a. double pipe heat exchanger. mm for larger diameter columns. b. multipass shell and tube heat exchanger. d. Minimum recommended downcomer residence time for the c. fouling fluids. disengagement of entrained vapour is the same for both foaming and d. counter flow of hot and cold fluids. non-foaming liquids, which is about 20 seconds. 41. Floating head heat exchangers are used for the 32. Generally, no corrosion allowance in wall thickness of a part is required, if a. heat transfer between corrosive fluids. the thickness is more than __________ mm. b. cases where temperature difference between the shell and the tubes a. 10 is more (>50°C). b. 20 c. co-current heat transfer systems. c. 30 d. counter-current heat transfer systems. d. 5 42. The most common standard size of bubble caps used in industrial operation 33. Multiple blade paddle agitator is used for mixing high viscosity is liquids/paste in which the paddle diameter is commonly 0.8 times the tank a. 1" dia cap with 0.5" dia riser. diameter. However, the width of the blade is in the range of __________ times b. 6" dia cap with 4" dia riser. the paddle diameter. c. 8" dia cap with 1" dia riser. a. 0.1 to 0.25 d. 4" dia cap with 8" dia riser. b. 0.3 to 0.5 c. 0.5 to 0.6 43. Compensation against openings in process vessels for giving inlet and outlet d. 0.65 to 0.80 connections, for providing sight glasses and manholes etc. is provided for strength and rigidity. The most efficient type of compensation is of __________ 34. In a __________ rivetted joint, the rivets in the various rows are opposite type. to each other. a. nozzle or rim a. zig-zag b. flared out b. chain c. fluid in c. diamond d. ring plate d. none of these 44. In case of a continuous distillation column, increase in reflux ratio may 35. Pick out the wrong statement: result in the a. The tensile strength of a brittle material is less than its compressive a. lower fixed charges for the column. strength. b. greater cost for the reboiler heat supply. b. The compressive strength of a ductile materia] is less than its tensile c. greater cost for the condenser coolant. strength. d. all (a), (b) and (c). c. In a thick cylindrical shell, the hoop stress is maximum at the inner radius. 45. In a distillation column, the minimum residence time for liquid in the d. The value of crushing load is more than that of buckling load for downspout is about __________ seconds. long colmns. a. 1 b. 8 36. Generally, elliptical dished heads c. 80 a. are manufactured on 2:1 ratio of major to minor axis and is d. 180 recommended to be used for pressure vessels operating above a pressure of 1.5 MN/m2. 46. Thickness of the frame of a plate and frame filter as compared to that of b. resist half the pressure rating compared to hemi spherical head plates is provided on the cylindrical shell of the same thickness and diameter. a. less c. are approximately as strong as seamless cylindrical shell having the b. same corresponding I.D and O.D. c. more d. all (a), (b) and (c) d. either (a) or (b) 37. Pick out the wrong statement pertaining to the comparative evaluation of 47. Which of the following factors affect the pressure drop in a co-current gas- performance of the packed tower and the plate tower. liquid absorption packed tower ? a. Plate tower is perferred, if interstage cooling is required to remove a. Size, shape, orientation and surface of the packing particles. heats of reaction or solution. b. Density and viscosity of fluids. b. Plate tower is preferred over packed tower, if the operation involves c. Fluid flow rates. liquids containing dispersed solids. d. All (a), (b) and (c). c. The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty. 48. The thickness of heat transfer plates used in the plate type heat exchanger d. In operations involving large temperature changes. (e.g. ranges from __________ mm, pressed in a single piece provided with grooves distillation), plate towers are preferred over packed towers as the & corrugations. packing may be crushed due to large temperature changes. a. 0.3 to 0.8 b. 1.25 to 3.125 38. The circumferential (hoop) stress in a thin walled cylinderical vessel under c. 3.5 to 7.0 internal pressure is d. 8-12 a. pd/2t b. pd/4t 49. Rivets are generally specified by the c. pd/t a. head diameter d. pd/3t b. shank diameter c. overall length d. none of these 39. for fully open gate valves would be 50. Length to diameter ratio of most rotary driers is in the range of a. much more than that for fully open globe valves. a. 1 to 2 b. much less (say 2% than that for fully open globe valves).  b. 4 to 10 c. remains same throughout. c. 10 to 20 d. may decrease or increase upwards depending upon whether vacuum d. 20 to 30 or positive pressure would be maintained inside the shell. SECTION 3 1. Tube wall thickness depends on the cor-rosiveness of the fluids and their 11.In the design of a paddle agitator, the ratio is normally taken as operating pressure & temperature and is specified by Birmingham wire gauge a. 0.1 (B.W.G)-a number which varies from 8 to 18 with the numbers 14 and 16 being b. 0.8 more commonly used. Outside diameter of tubes varies from about 15 to 50 c. 0.25 mm; however a tube of less than __________ mm outside diameter is generally d. 0.5 not recommended for fouling fluids. a. 16 12. The design stress, which is more than the damaging stress, is the least unit b. 19 stress that will render a member unfit for service before the end of its normal c. 28 life. The design stress factor or factor of safety indicates the margin between d. 38 design stress and the __________ stress. a. working 2. Angled baffles are preferred in the agitation tank to control the swirling b. damaging action; if the viscosity of the liquid to be mixed is about 200 poise. However, c. allowable the baffle may be completely eliminated for mixing liquids having viscoisty d. none of these above __________ poise. a. 300 13. b. 600 Hole diameter of the seive trays in the distillation column ranges from c. 1000 __________ mm. d. 1500 a. l to 3 b. 4 to 8 3. Ratio of tube length to shell diameter for a shell and tube heat exchanger is c. 3 to 12.5 a. 8 : 1 to 12 : 1 for both liquid-liquid and gas-gas heat exchangers. d. 12.5 to 18.5 b. 4 : 1 to 8 : 1 for liquid-liquid exchanger. c. < 4 : 1 for gas-gas exchangers. 14. Factor of safety (i.e., overdesign factor) in heat transfer equipments is about d. both(b) & (c). __________ percent more than the actual/theoretical design factor. a. 5-10 4. The dust collection efficiency of a cyclone separator b. 15-20 a. decreases with increase in gas flow rate. c. 30-35 b. is inversely proportional to the mass of the dust particle. d. 35-40 c. is directly proportional to the radius of the dust particle path. d. none of these. 15. For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is 5. In a shell and tube heat exchanger, the overall heat transfer co-efficient is proportional to the tube side (volumetric flow rate)0.8. This is valid, only when the ratio of the tube side film resistance to the total resistance is almost equal to a. , , a. ∞ b. 1 c. 20.8 d. 2 b. 6. Which of the following types of reactors is the safest from operation point of view ? c. a. A vapor phase reactor. b. Pot type reactor. c. A liquid phase reactor. d. d. A liquid phase catalytic reactor. 7. In a bag filter, the pressure drop increases directly as the 16. In actual operation of distillation column, the vapour is not distributed a. density of the gas, but is independent of the viscosity of the gas. uniformly among the bubble caps, primarily because of the b. density of the gas and inversely as viscosity of the gas. a. liquid gradient on the tray. c. viscosity of the gas and inversely as density of the gas. b. lower skirt clearance. d. none of these. c. lower static submergence. d. small downcomer liquid seal. 8. The LMTD correction factor (FT) is applied in __________ heat exchangers. a. cocurrent 17. The minimum shell thickness for tank ≤ 15 metres diameter is limited to b. double pipe __________ mm, for reasons of elastic stability. c. all multipass a. 2 d. all (involving liquid/liquid heat transfer) b. 5 c. 10 9. Movement of pipeline caused by thermal expansion is taken care by d. 15 providing a. expansion joint. 18. If 'D' is the inside diameter of the shell of a shell and tube heat exchanger, b. changes in its direction. then the baffle spacing is usually in the range of c. change in the shape of pipeline. a. D/2 or minimum 2" to 5D. d. all (a), (b) and (c). b. D/5 or minimum 2" to 5D. c. D/5 or minimum 2" to D. 10. For a cylindrical shell, (subject to the thickness of uppermost course being d. none of these. more than the minimum for diaofthe tank in question), the thickness of the courses of shell 19. Brass valves are usually made for pipe sizes __________ inches. a. decreases upwards. a. ≤1 b. increases upwards. b. ≤2  c. >2.5 28. Steam is preferred to be used as a heating medium in heat exchangers, d. >3.5 because of its a. low cost. 20. At the following point for a given packing and set of fluids, the pressure b. high latent heat. drop per metre of packed height, with variation in fluid rates and operating c. non-corrosive condensate. pressure d. high film co-efficient. a. increases b. decreases 29. __________ shapedroof is the most commonly used roof for cylinderical c. remains same storage tanks. d. may increase or decrease depending upon the solubility of the gas in a. Conical the liquid b. Flat c. Dome 21. In a shell and tube heat exchanger, triangular pitch arrangement as d. Umbrella compared to square pitch arrangement a. results in higher shell side pressure drop. 30. Pick out the wrong statement pertaining to 'Horton sphere' used for the b. can accomodate less number of tubes for a given shell diameter. storage of liquid ammonia. c. facilitates easier shell side cleaning; hence is more suitable for a. Diameter of Horton sphere is normally 6 to 25 metres and it is handling high dirt factor shell side fluid. supported by 6 to 12 nos. tubular or rolled section column. d. creates relatively lower turbulence on the shell side resulting in b. Thickness of spherical shell is half that of the cylinderical vessel lower shell side heat transfer co-efficient. under same operating pressure condition. Besides, the ratio of surface area to volume is less for sphere than any other shape ; hence 22. Pick out the wrong statement about routing of fluids in a shell and tube heat insulation required is less. exchanger. c. Horton sphere is used for the storage of gases and volatile liquid at a. The corrosive and fouling fluid should be preferably routed through a moderate pressure of 1 to 10 kg/cm2. the tubes. d. Horton sphere is used for the storage of liquid at sub-zero b. The viscous fluid should be routed through the shell side. temperature at very high pressure upto 200 kg/cm2. c. Lower flow rate fluid should be routed through the shell side. d. Higher pressure fluid stream should be routed through the shell side. 31. Value of Peclet number = ∞, is the representative of a. laminar flow. 23. The necessary wall thickness for a metallic storage vessel is a function of b. complete back mixing, the c. plug flow. a. ultimate tensile strength (or yield point) of the material and d. eddy diffusivity = 0. operating temperature. b. operating pressure and welding/joint efficiency. c. diameter of the vessel. d. all (a); (b) and (c). 32. for a Tee (used as elbow, entering branch) would be a. less than that for Tee (used as elbow, entering run). 24. In a multiple effect evaporator system having 'n' effects, the amount of water b. more than that for Tee (used as elbow, entering run). evaporated per unit surface area in approximately equal to __________ times c. around 90. that in a single effect. d. both (b) and (c). a. 'n'th b. (1/n)th 33. In most of the shell and tube heat exchangers, the tube pitch is generally c. 0.5 nth __________ the tube diameter. d. 1.5 nth a. less than b. 1.25-1.50 times 25. Pick out the wrong statement c. 2.5 times a. In a flanged and standard dished head, the crown radius is ≤ shell d. one-fourth of outside diameter. b. In a flanged and shallow dished head, the crown radius is > shell 34. In a distillation column, bubble caps are located on trays with a pitch of outside diameter. __________ times the outside diameter of the caps. c. Flat head covers are most suitable for larger vessels operating at very a. 1.3 to 2 high pressure. b. 1.6 to 2 d. Flanged only head is a type of flat head in which gradual change in c. 2.5 the shape at the centre results in reduced local stresses. d. 1.5 to 3 26. Pick out the wrong statement pertaining to the design of a horizontal tube 35. 1.2 to 3.8 cms is the value of the evaporator. a. downcomer liquid seal in case of a balanced tray design. a. It is unsuitable for concentrating those liquids, which form a scale b. static submergence in case of a bubble cap tray for column operating or deposit salt. under pressure (≥ 1 atm.). b. It is suitable for process, in which the final product is a liquor instead c. skirt clearance for bubble caps. of solid. d. all (a), (b) and (c). c. Its usual dimensions are: tube dia = 2-3 cms; evaporator body dia = 1-4 metres and evaporator height = 2.5-4 metres. 36. Accidents in chemical plants are mostly due to d. Liquor flows inside the tube, while the steam is outside submerging a. inadequate equipment design. the tube. b. faulty operating procedures. c. improper layout of the equipments. 27. Weep holes provided in the plates of a distillation column d. failure of equipments. a. facilitate draining out liquid from a tray when the unit is not in operation. 37. For identical operating conditions, the pressure drop over __________ tray b. are normally located near the overflow weir so that any delivery of is the highest out of the following. liquid during operation follows approximately the same path as the a. sieve overflow fluid. b. valve c. must be large enough (usually 1/4" to 5/8" dia) to prevent plugging c. counterflow but should not deliver excessive amount of fluid during operation. d. bubble cap d. all (a), (b) and (c). 38. A perforated plate has holes of diameter dn arranged in a pitch ph. Each hole has a tube of I.D. dt passing through it. The ligament efficiency is given by  a. (ph - dh)/ph b. (ph - dh. dt/2)/ph 49. High pressure fluid in a shell and tube heat exchanger should preferably be c. (ph - dt)/ph routed through the d. (ph - dh)/dh a. tubes to avoid the expansion of high pressure shell construction. b. shell side for smaller total pressure drop. 39.__________ is the determining factor for the number of bubble caps to be c. shell side, if the flow is counter-current and tube side if the flow is used per tray. co-current. a. Permissible slot velocity d. shell side for large overall heat transfer co-efficient. b. Tray diameter c. Liquid load 50. Bubble cap tray is the most commonly used tray in large distillation column, d. Vapor load because a. of its flexibility and nearly constant efficiency under varying 40. Pick out the wrong statement about distillation operation conditions of operation. a. Distillation under vacuum is a substitute for steam distillation. b. it incurs less pressure drop as compared to any other try designed b. In differential (simple) distillation, the vapour is removed as soon as for the same duty. it is formed without appreciable condensation. c. it eliminates the foaming and entrain-ment tendency during c. In flash (equilibrium) distillation, a definite fraction of liquid is operation. vaporised in such a way that the evolved vapour & residual liquids d. none of these. are in equilibrium with each other. d. Flash distillation, differential distillation & steam distillation are all continuous distillation processes. 41. 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 SECTION 4 b. 450 1. In common bubble cap distillation column design practice, riser area is c. 650 approximately equal to (where, Aa = Annular passage area, and Sa = Slot area) d. 750 a. Aa = S a b. 1.2 Aa = 1.2 Sa 42.Which of the following is the best tube material from thermal conductivity c. Sa = 1.5 Aa point of view alone? d. Aa = 1.5 Sa a. Aluminium b. Stainless steel 2. c. Copper Heat transfer co-efficient, hG(Kcal/hr.m2.°C) and mass velocity of d. Carbon steel air, G (kg/hr.m2 ) for air flow parallel to the surface in case of constant drying rate in batch drying is related as hG = 0.0176G0.8. But when the flow of air 43. Normal screwed fittings are used for pipes upto a diameter of __________ perpendicular to the surface is encountered, this equation changes to inches. a. hG = 1.004G0.37 a. 1.5 b. 1.004G0.8 b. 3 c. hG = 0.0176G0.37 c. 5 d. 0.0176G1.37 d. 7 3. In the agitators, the power required will be changed with the increase of 44. In a shell and tube heat exchanger, the clearance of the tube is generally diameter of agitator (D) as a. not less than one-fourth of the tube diameter or 3/16". a. D2 b. more than the tube diameter. b. D5 c. equal to the tube diameter. c. D d. more in case of triangular pitch as compared to the square pitch tube d. D9 layout. 4. Apex angle of conical heads used in the bottom heads of chemical process 45. Diameter of the seive tray column is determined by the equipments is usually a. lower limit of vapour velocity. a. 30° b. upper limit of the vapour velocity. b. 45° c. hole diameter of the seive tray. c. 60° d. height of the plate spacing. d. 75° 46. For a given fluid, as the pipe diameter increases, the pumping cost 5. Pressure drop due to pipe fittings can be estimated by the equation, a. decreases. b. increases. c. remains unaffected. , where, Le = equivalent length of straight pipeline d. may increase or decreaes depending upon whether the fluid is which will incur the same frictional loss as the fitting and D = diameter of the Newtonian or non-Newtonion. 47. Maximum acceptable total liquid gradient over a tray is about __________ mm. fitting. The value of (dimensionless) for 45° elbow and 180° close return a. 5.5 bends would be respectively around b. 12.5 a. 5 and 10 c. 30.5 b. 45 and 75 d. 45.5 c. 180 and 300 d. 300 and 500 48.In case of a 'thin' pressure vessel, the ratio of its diameter to wall thickness is 6. A pressure vessel is said to be made of 'thick' shell, if the ratio of its diameter a. < 10 to wall thickness is b. > 10 a. 10 c. > 20 b. 10 d. 30 c. 20  d. 20 a. minimum cleaning lane of 6.5 mm is provided, when tubes are on a square pitch. 7. Rate of filtrate delivery is inversely proportional to the b. minimum tube sheet thickness (in which tubes are fixed) is equal to a. filtering area & the pressure difference driving force. the O.D. of the tube upto 15 mm tube diameter; and for > 15 mm b. viscosity of filtrate. tube diameter, tube sheet thickness is smaller than tube diameter. c. cake & filter medium resistance. c. O.D. of the tube is 6 to 40 mm while the tube lengths used are 0.5, d. both (a) and (b) 2.5, 3.0, 4.0, 5.0, 6 metres. d. all (a), (b) & (c). 8. Tube side heat transfer co-efficient for turbulent flow of liquid through tubes is proportional to 17. In a cylinderical vessel subjected to internal pressure, the longitudinal stress a. G0.2 σL and the circumferential stress, σn are related by b. G0.5 a. σh = 2 σL c. G0.8 b. σh = σL d. G1.5 c. σh = σL/2 d. no relation exists 9. Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure 18. Nominal size of a pipe is an indication of its __________ diameter. is __________ the longitudinal stress. a. inner a. half b. outer b. equal to c. approximate c. twice d. none of these d. eight times 19. Excessive liquid gradient on a tray may result in the 10. The dust collection efficiency of electrostatic precipitator increases with a. maldistribution of gas. increase in the b. back trapping. a. gas flow rate. c. gas blowing beneath cap skit. b. electrode area. d. all (a), (b) and (c). c. both (a) & (b). d. neither (a) nor (b). 20. 11. For storing hazardous chemicals in large storage tanks, the minimum safe The ratio of tube length to shell diameter in case of liquid shell and tube heat distance between the two tanks should range between __________ times the exchanger ranges from tank diameter. a. 2 to 3 a. 1 to 1.5 b. 3 to 5 b. 2.5 to 3.5 c. 4 to 8 c. 4 to 5 d. 6 to 12 d. 6 to 8 21. In a double pipe concentric heat exchanger, the equivalent diameter of 12. Which of the following factors determine the amount of entrainment in a annulus for heat transfer would be (where, D1 and D2 are I.D. of inner and outer distillation column? pipes) a. Plate spacing. b. Depth of liquid above the bubble cap slots. c. Vapour velocity in the volume between the plates. a. , , d. All (a), (b) and (c). b. D2 - D1 13. The absorption factor is defined as (where, S1 = slope of the equilibrium curve, S2 = slope of the operating line) c. a. S1/S2 d. none of these b. S1.S2 c. S2/S1 22. What is the slope of the operating line in the stripping section of a d. 1/S1.S2 distillation column ? a. 0 14. In shell and tube heat exchangers, straight tie rods are used to b. ∞ a. hold baffle in space. c. >1 b. fix the tubes in position. d. < 1 c. account for thermal strain. d. none of these. 23. __________ shaped roof is most commonly used for cylindrical tanks. a. Cone 15. In a rotary drier, the average retention time of solid is(where Z = length of b. Dome the drier, metres ρ = apparent solid density, kg/m3 L = flow rate of dry solids, c. Umbrella kg/see. m2 drier cross-section H = hold up of solid.) d. Flat a. , , 24. In a thin cylindrical shell, the hoop stress is __________ stress. a. radial b. circumferential tensile c. compressive b. d. longitudinal 25. Commercial packed scrubbers are normally designed for a pressure drop c. range of __________ mm water coloumn per metre of packed height. a. 4-8 b. 17-34 d. c. 52-68 d. 88-105 16. In case of design of a shell and tube heat exchanger, 26. The retention time of material in a rotary dryer depends upon its  a. rpm d. Risers are generally not connected to the plate in a distillation b. slope & length coloumn by bolts, rivets or welding. c. flights arrangement d. all (a), (b) and (c) 37. "A claming section" before the liquid flows into the downcomer is privided to 27. In actual operation of a bubble cap distillation tower, the __________ at the a. permit release of entrained vapour in the liquid. bottom of the tower is more than that at the top of the tower. b. reduce the discharge fluctuation. a. molal flow rate of vapour c. ensure better vapour-liquid contact. b. vapour molecular weight d. cool the liquid before it flows down. c. pressure and temperature d. all (a), (b) and (c) 38. The units of Young's modulus of elasticity and __________ are the same. a. strain 28. Rotary driers are most economically designed for the number of heat b. stress transfer units (HTU) from c. modular ratio a. 0.01 to 1 d. none of these b. 1.5 to 2.5 c. 5 to 10 39. In the design of a shell and tube heat exchanger, the corrosion allowance d. 10 to 20 a. need not be provided for non-pressure parts like tie rods, spacers, baffles, supports etc. 29. The difficulty of liquid distribution in packed towers is accentuated, when b. for carbon steel and cast iron pressure parts is 1.5 mm (except for the ratio of tower diameter to packing diameter is tubes) and for severe conditions it is 3 mm. a. < 30 c. for internal cover and tube sheet is provided on both the sides. b. < 7 d. all (a), (b) & (c). c. 7 < 15 d. 20 < 50 40. Vertical condenser is advantageous to the horizontal condenser from operation point of view, when 30. A forced circulation long tube vertical evaporator as compared to the natural a. hydrostatic head is required for refluxing the condensate. circulation evaporator b. only the function of condensation is to be carried out. a. is economical in operation. c. sub cooling of condensate is desired. b. employs high velocity, high heat transfer rate and less heating d. both the functions of condensation & sub cooling are carried out in surface requirement. a single unit. c. employs a centrifugal pump placed between external downtake from vapor drum and inlet to tube bundle. d. both (b) & (c). 41. Hazards associated with the relief valve leakage for extremely hazardous material storage can be taken care of by providing 31. An increase in the liquid resistance to interphase mass transfer and a a. rupture diaphragm resultant reduction in plate efficiency is caused by b. dikes a. an increase in liquid viscosity. c. surge chamber b. an increase in relatived volatility for rectification columns. d. none of these c. decrease in gas solubility for absorbers. d. all (a), (b) and (c). 42. Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to 32. In the design of a bag filter, the gas temperature is an important a. 5 cms consideration, as it affects the b. 40% of the I.D. of the shell a. gas density c. 25 cms b. gas viscosity d. I.D. of the shell c. fibre selection d. all (a), (b) & (c) 43. __________ liquor is best handled in a long tube vertical evaporator. a. Foamy 33. With increase in temperature drop (in a shell and tube heat exchanger), b. Scaling the LMTD correction factor, FT c. Viscous a. decreases very rapidly d. Salting b. increases very rapidly c. remains constant 44. Theoretically calculated diameter of the stripping section of the continuous d. increases linearly rectification column is __________ that of the enriching section. a. less than 34. The normal range of velocity of steam in pipes is __________ m/sec. b. more than a. 0.1-0.5 c. same as b. 1-5 d. either more or less (depending upon relative volatility) c. 10-20 d. 80-100 45. Hold up of material in a operating rotary drier is in the range of a. 0.05 to 0.15 35. __________ dished head is the strongest of all. b. 0.25 to 0.50 a. Hemispherical c. 0.5 to 0.8 b. Elliptical d. 0.8 to 0.9 c. Torispherical d. none of these 46. A binary liquid azeotropic mixture has boiling point higher than either of the components, when it shows __________ deviation from Raoult's Law. 36. Pick out the correct statement. a. positive a. It is preferred to use a vertical condenser for condensation of vapor b. negative from a distillation column without sub-cooling c. no b. Draining of residual liquid on tray during shut down of distillation d. none of these column is facilitated by weep holes. c. Random packing a packed tower offers the advantage of lower 47. The testing pressure of storage tanks and pressure vessels designed as per pressure drop and higher throughput of fluids as compared to Indian standard codes should be about __________ times.the design pressure. regular/stacked packing. a. 1.5 to 2  b. 3 to 4 a. U-bend c. 4 to 5 b. floating head tube sheet d. >5 c. either (a) or (b) d. neither (a) nor (b) 48. Flanges are connected to pipes by a. screwing 9. In a shell and tube heat exchanger, the shortest centre to centre distance b. welding between the adjacent tubes is c. brazing a. called tube pitch. d. all (a), (b) and (c) b. called tube clearance. c. always less than the diameter of the tube. 49. The ratio of down take area to cross-sectional area of the tube, for calendria d. none of these. type evaporator ranges from a. 0.5 to 1 10. Any shell opening greater than 5 cms for a storage tank must be reinforced b. 1 to 1.5 for reason of c. 1.5 to 2 a. preventing the local overstressing of the shell around the opening. d. 2 to 2.5 b. reduction of discontinuity in shape at the junction. c. making the joint leak proof. 50. Shortest distance between two tubes is d. none of these. a. called tube pitch. b. called tube clearance. 11. Minimum tube pitch recommended for shell and tube heat exchangers is c. more in case of triangular pitch as compared to square pitch of tube about __________ times the outside diameter of the tube. layout. a. 1.25 d. none of these. b. 1.75 c. 2.5 SECTION 5 d. 3.5 1. __________ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids. 12. Liquid redistribution should be done in a packed tower packed with raschig a. Sieve plate rings every 6 metres or __________ times the column diameter, whichever is b. Packed lower. c. Bubble cap plate a. 2.5-3.0 d. None of these b. 5-7.5 c. 10-12.5 2. At equal mass velocities, the values of film co-efficients for gases as d. 15-20 compared to that for liquids are generally. a. higher 13. Slope of countercurrent flow rotary drier is in the range of __________ b. lower meter/metre. c. same a. 0 to 0.08 d. unpredictable b. 0 to 0.8 c. 0 to 1.5 3. The ratio of the largest load in a test to the original cross-sectional area of the d. 0 to 2.2 test specimen is called the __________ stress. a. yield point 14. In case of saddle packing (e.g., berl and intralox saddles), the maximum size b. breaking of the packing should not exceed __________ of the column diameter. c. ultimate a. l/5th d. none of these b. l/15th c. l/30th 4. Baffle spacing is generally __________ the I.D. of the shell. d. l/50th a. more than b. not greater than 15. Seamless pipe is made c. not less than one fifth of a. from rolled strips formed into cylinders and seam-welded. d. both (b) and (c) b. by extrusion & casting into static and centrifugal molds. c. by forging a solid round, piercing it by simultaneously rotating & 5. The wall thickness of thin cylindrical shell with hemispherical ends is forcing it over a piercer point and further reducing it by rolling gas __________ that of the spherical ends. drawing. a. equal to d. both (b) and (c). b. more than c. less than 16. The thermal stress in a metallic bar does not depend upon the d. either (b) or (c); depends on maximum permissible internal pressure a. changes in temperature. b. cross-sectional area. 6. A 'rupture disc' is provided in chemical equipments as an accessory meant c. both (a) and (b). for d. neither (a) nor (b). a. relieving excess pressure. b. creating turbulence. 17. The minimum baffle height should be c. enhancing mixing rate. a. equal to the impeller diameter. d. avoiding vortex formation. b. twice the impeller diameter. c. twice the tank diameter. 7. In a vertical short tube evaporator (Calendria type), the d. 3/4 of the tank height. a. tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylinderical drum dia of 1-6 metres are normally used. 18. For turbulent flow (NRe > 2100) of low viscosity fluid (μ > 20cp) in steel b. area of central downtake is equal to 40 to 100% of total cross- pipes, the optimum inside pipe diameter is given by(where, Q = fluid flow rate, sectional area of the surrounding tube. ft3/sec.ρ = fluid density, lb/ft3 μ = fluid viscosity, centipoise Di = optimum c. liquor is inside the tube while the steam is outside the tube. inside pipe diameter, inches) d. all (a), (b) & (c). a. Di, opt = 3.9 Q0.45 ρ0.13 b. Di, opt = 3.9 Q0.45. μ0.95 8. In a multipass shell and tube heat exchanger, the problem of differential c. Di, opt = 4.7 Q0.36. μ3.2ρ0.13 expansion between the shell and tube passes is taken care of by using a d. Di, opt = 3 Q0.36. μ0.88  c. bolts 19. To avoid the tearing off the plate of an edge, the margin (i.e., the minimum d. both (b) and (c) distance from the centre of the rivet hole to the nearest edge of the plate) should be equal to 29. The buckling tendency of compression members is always in the direction a. 0.5 d of the b. d a. least radius of gyration. c. 1.5 d b. axis of the load. d. 2.5 d c. perpendicular to the axis of the load. d. none of these. 20. The normal range of velocity of water in pipes is __________ m/sec. a. 0.1-0.5 30. In case of plain carbon steel, butt welded joints are used for shell plate b. 1-2 thickness ≤ __________ cms. c. 10-50 a. 1.2 d. 15-30 b. 0.5 c. 3.8 21. Baffles are provided in a shell and tube heat exchanger to increase the d. 6.8 turbulence and velocity of the shell side fluid. Which of the following shaped baffles does not fall in the category of transverse baffle ? 31. The average velocity in the tubes of a 1-4 heat exchanger is __________ a. Segmental baffle times that in 1-1 heat exchanger having the same size & number of tubes and b. Flat plate extending across the wall operated at same liquid flow rate. c. Disk type baffle a. 2 d. Helical type baffle b. 1/2 c. 4 22. A certain pressure vessel manufacturer avoids doing reinforcements d. 1/4 calculations for openings by always providing a reinforcing pad extending upto double the diameter of the opening and of the same material and thickness as 32. Hoop (circumferential) stress induced in a thin walled 'Horton Sphere' used that of the shell wall. If area compensation is accepted as a code guideline, his for the storage of liquid ammonia under pressure is approach leads to safe design a. only if the opening is on spherical vessel. b. only if the opening is on a vertical cylinderical vessel. a. , , c. only if the opening is on a horizontal cylinderical vessel. d. irrespective of the shape of the vessel. 23. In a __________ rivetted joint, the number of rivets decreases from the b. innermost row to the outermost row. a. chain b. diamond c. c. zig-zag d. none of these d. 24. Large process vessels operating under extreme temperature and pressure conditions are normally clad/ lined with materials like stainless steel, 33. When one of the fluids is highly corrosive and has fouling tendency, it aluminium, nickel & its alloys, copper & its alloys and titanium. The cladding should thickness is generally about __________ percent of the total thickness. a. preferably flow inside the tube for its easier internal cleaning. a. 1 to 5 b. perferably flow outside the tube. b. 10 to 20 c. flow at a very slow velocity. c. 30 to 40 d. flow outside the tube, when the flow is counter-current and inside d. 40 to 50 the tube when the flow is co-current. 25. Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is a. same 34. The raio, is normally taken as b. less a. 0.15-030 c. about 3 times b. 0.5-0.65 d. about 0.33 times c. 0.75-0.85 d. 0.60-0.90 26. Pick out the wrong statement pertaining to the design of the distillation column. 35. A/an __________ is used for changing the direction of a pipeline. a. Generally, a skirt clerance of 0.5" to 1.5' is recommended to prevent a. elbow plugging of the slots by residue build up. b. union b. The purpose of the slot is to disperse the gas into the liquid in the c. flange form of small bubbles. d. disc compensator c. If sufficient slot area is not provided, the gas may pass through the skirt clearance. 36. Maximum plate efficiency is achieved in case of __________ flow. d. none of these. a. split b. cross 27. The longitudinal stress induced in a thin walled cylinderical vessel under c. cascade internal pressure is d. reverse a. pd/2t b. pd/4t 37.