0% 0 Process Equipment and Plant Design Quiz 4 1 / 50 In the downcomer of a distillation column, the minimum recommended residence time is about ________ seconds? 5 12.5 17.5 2.5 2 / 50 Length to diameter ratio of most rotary driers is in the range of______? 20 to 30 4 to 10 1 to 2 10 to 20 3 / 50 Normally, the ratio of the total riser area to the tower cross sectional area (for bubble cap towers of diameter more than 3 ft) is around________? 0.35-0.75 0.4-0.6 0.1-0.2 0.55-0.85 4 / 50 In packed towers provided with saddle packing, liquid redistributors are positioned at every ________ times column diameter or 6 metres whichever is less? 20-25 8-May 15-Oct 3-Feb 5 / 50 Log mean temperature difference in case of multi-pass shell and tube heat exchanger is always__________? More than geometric mean value Less than arithmetic mean value More than arithmetic mean value Both B. & C. 6 / 50 Maximum plate efficiency is achieved in case of _______ flow? Split Reverse Cascade Cross 7 / 50 Liquid/petroleum fuel storage tanks are built underground (as in case of petrol pumps), when the storage capacity is less than _______ kilolitres? 20 45 30 85 8 / 50 Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter) ? 0.80 D 0.66 D 0.2 D 0.5 D 9 / 50 Maximum acceptable total liquid gradient over a tray is about ________ mm? 12.5 45.5 30.5 5.5 10 / 50 Longitudinal stress induced in a thin walled cylindrical storage vessel is ___________? pD/3t pD/2t pD/6t pD/4t 11 / 50 Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to _______? 25 cms I.D. of the shell 5 cms 40% of the I.D. of the shell 12 / 50 Larger depth of liquid on the trays of a distillation column__________? Results in higher pressure drop per tray Leads to high tray efficiency Neither A. or B. Both A. & B. 13 / 50 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? 2.5 to 4.0 10 to 15 5 to 10 0.5 to 1.5 14 / 50 Multiple blade paddle agitator is used for mixing high viscosity liquids/paste in which the paddle diameter is commonly 0.8 times the tank diameter. However, the width of the blade is in the range of _______ times the paddle diameter? 0.5 to 0.6 0.1 to 0.25 0.3 to 0.5 0.65 to 0.80 15 / 50 Nominal size of a pipe is an indication of its ________ diameter? Inner None of these Approximate Outer 16 / 50 In shell and tube heat exchangers, straight tie rods are used to__________? Hold baffle in space Fix the tubes in position Account for thermal strain None of these 17 / 50 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 Neither A. nor B. Either A. or B. Clearance of 25-75 mm 18 / 50 LMTD correction factor is used in heat exchanger design for______? Double pipe heat exchanger Multipass shell and tube heat exchanger Counter flow of hot and cold fluids Fouling fluids 19 / 50 Overall distillation column efficiency for most of the refinery columns can be given by (for ? = 0.07 ? 1.4 cp and relative volatility < 4) (where ? = overall column efficiency, % ? = molal average viscosity of feed at average column temperature and pressure, cp ?p = pressure drop per tray, psi) ? ? = 24.6 (?p/?) ? = 1.66 ? 0.25 log ? ? = 0.25 log ? ? 1.67 ? = 17 ? 61.1 log ? 20 / 50 Minimum tube pitch recommended for shell and tube heat exchangers is about ________ times the outside diameter of the tube? 1.75 3.5 1.25 2.5 21 / 50 In the design of a paddle agitator, the ratio (paddle dia/tank dia) is normally taken as_____? 0.25 0.1 0.8 0.5 22 / 50 In packed absorption tower, onset of flooding usually occurs at a pressure drop of about _______ mm of water column per metre height of packing? 750-1000 25-50 200-250 50-75 23 / 50 Needle valves are generally not used for_____? Very accurate flow control Very large diameter pipes Smaller sizes of pipe High pressure throttling service 24 / 50 In the design of a bag filter, the gas temperature is an important consideration, as it affects the_____? All A., B. & C. Gas density Gas viscosity Fibre selection 25 / 50 Lap joints are preferred for plates having thickness ________ mm? > 3 < 12.5 10-May > 5 26 / 50 Overall mass transfer co-efficient in case of absorption of __________ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling ? CO2 None of these NH3 SO2 27 / 50 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? 1/20-1/30th 1/2 to 1/4th 1/5-1/10th 1/10-1/15th 28 / 50 Lug support is meant for supporting ________ vessels? Thick walled tall Small Large horizontal cylindrical Tall but empty 29 / 50 Le/D) for 90? elbow (medium radius) and 90?square elbow would be respectively around_____? 100 and 250 250 and 600 3 and 5 25 and 60 30 / 50 Liquid gradient over the tray results due to the_____? Large plate spacing Low gas velocity Resistance offered to flow of liquids by caps & risers and the flow of gas Large reflux ratio 31 / 50 Movement of pipeline caused by thermal expansion is taken care by providing _____? Changes in its direction All A., B. and C. Change in the shape of pipeline Expansion joint 32 / 50 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)? 250 450 750 650 33 / 50 Normally, the plate thickness of the bottoms and roofs of vertically cylindrical storage vessels as compared to that of the cylindrical shell is_____? More or less depending upon the pressure & temperature inside the vessel and the nature of the fluid contained therein More Same Less 34 / 50 Number of evaporators which can be used in service in a multiple effect evaporation system is limited by the___________? Both A. & B. Neither A. nor B. Practical limit reached, due to low heat transfer rate because of inadequate temperature difference Economic limit reached, when the plant cost exceeds the saving of steam 35 / 50 Optimum economic pipe diameter for fluid flow is determined by the______? Density of the fluid Total cost considerations (pumping cost plus fixed cost of the pipe) Viscosity of the fluid None of these 36 / 50 Normally, the length to diameter ratio of rotary dryers varies from 4 to 10 and for its economic operation; the number of transfer units (NTU) for such dryers varies from ? 1.5-2.5 3.5-5.5 15-Oct 7.5-10.0 37 / 50 Normal screwed fittings are used for pipes upto a diameter of ________ inches? 3 1.5 9 5 38 / 50 Of the pressure vessels, with same thickness but different diameters, which one withstands higher pressure ? Larger dia long vessel Smaller dia vessel Larger dia vessel Strength of the vessel is same irrespective of the diameter 39 / 50 Maximum allowable vapour velocity in a bubble cap tower is determined by the ______? None of these Vapour density Entrainment considerations Diameter of the column 40 / 50 Joint efficiency (J) for a seamless pipe is________? 1.5 0.85 1 < 0.5 41 / 50 Mc Cable Thiele method used for finding theoretical stages in a distillation column assumes that the_______? All A., B. and C. Liquid/vapor loading across the column remains constant Trouton?s rule is applicable Sensible heat differences are small, because the temperature changes from tray to tray is small 42 / 50 Most of the storage vessels/tanks are made cylindrical, because of the fact that a cylinder __________? Has greater structural strength Neither A. nor B. Both A. and B. Is easy to fabricate 43 / 50 In which of the following evaporators, steam is fed inside the tube while the liquor is outside the tube ? Horizontal tube evaporator None of these Short tube vertical evaporator Long tube vertical evaporator 44 / 50 It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than __________? 0.95 0.55 0.99 0.8 45 / 50 Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or _______ times the column diameter, whichever is lower? 2.5-3.0 10-12.5 15-20 5-7.5 46 / 50 In the case of a shell and tube heat exchanger, the logarithmic mean temperature difference ________? Is always less than arithmetic mean value, but more than geometric mean value Is always less than arithmetic average value Is always more than arithmetic mean value and the 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 47 / 50 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 distance along the tray through which the liquid must flow Using split flow, radial flow or cascade flow for column diameter large than 4 ft All A., B. and C. 48 / 50 Optimum reflux ratio in a continuous distillation column is determined by the___________? Total cost consideration (fixed cost of the column plus the cooling water & steam cost) Maximum permissible vapour velocity Flooding limit of the column None of these 49 / 50 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? 30 to 40 10 to 20 40 to 50 1 to 5 50 / 50 Maximum size of the raschig rings used in a packed tower is about ________ of the column diameter? 1/10th 1/30th 1/50th 1/20th Provide Your Information Your score is The average score is 0% LinkedIn Facebook Twitter 0% Restart quiz Send feedback Share on facebook Facebook Share on twitter Twitter Share on whatsapp WhatsApp PrevProcess Equipment and Plant Design Quiz 3 Process Equipment and Plant Design Quiz 5Next
