PE 2

• Needle valves are generally not used for very large diameter pipes
• wrong statement.

  A. Safety valves are provided in heat exchangers for removal of non-condesables.

  B. Liquid metals and dowtherm are used for very high temperature heating.

  C. In a shell and tube heat exchanger, high pressure fluid is generally routed through the tube.

  D. A loop seal or U-seal is provided in a vertical condenser sub-cooler to prevent quick draining of the condensate.
• With increase in gas flow rate to fabric surface area ratio (Nm3/hr/m2 fabric surface area), the size & the cost of a bag filter decreases
• A head comprises of straight flange section, corner torus, section and central dished section. Crown radius and knuckle radius in a head is related respectively to the central dished section and corner torus section
• Allowable vapour velocity is used to set the diameter of the distillation column
• For reaction orders more than one, the smaller reactor should come first in a series of two mixed reactors
• Sorel-Lewis method is an analytical method, not a graphical method, for the calculation of theoretical number of stages in case of continuous binary distillation
• Saddle supports are used for supporting horizontal cylindrical vessels
• The diameter of a propeller agitator used in agitation tank ranges from 15 to 30 percent of the tank diameter and its peripheral speed is normally 300 to 500 metres/minute
• In packed towers provided with saddle packing, liquid redistributors are positioned at every 5 - 8 times column diameter or 6 metres whichever is less
• 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)
• Cooling water fouling factors vary in the range of 0.001 to 0.003 (BTU/hr.ft^2 . °F)^-1
• Minimum recommended baffle spacing in a shell and tube heat exchanger is about 0.2 D (where, D = shell diameter)
• The maximum liquid gradient over a tray must not exceed 0.5" - 1.25"
• An underdesigned steam trap will back up condensate and cause water hammer in steam line
• The slope of the feed line in distillation operation is given by -q/(1-q) (where, q = fraction of the feed stream that is liquid)
• Speed of industrial paddle agitator ranges from 20 to 100 rpm
• A Linear strain is measured using a 'strain rosetter'
• Thin spherical shells subjected to internal pressure, develop radial stresses
• With increase in the reflux ratio for a fixed production from a continuous binary distillation column, the fixed charges initially decreases
• The slope of operating line in the rectifying section of a distillation column is unity, if the reflux ratio is ∞
• Vertical vessels are not supported by saddles
• With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will increase
• Spherical shaped pressure vessel is considered to be the most ideal, because it can withstand higher pressure for a given metallic shell thickness
• An adequate clearance between the tray and the shell wall of a distillation column is provided to allow for thermal expansion and facilitate installation
• Overall tray efficiency of a distillation column is the ratio of the number of ideal trays required to the number of real trays required
• wrong statement:

  A. An increased weir height

  B. For segmental downcomers

  C. Width of the calming

  D. Minimum recommended downcomer residence time
• Generally, no corrosion allowance in wall thickness of a part is required, if the thickness is more than 30 mm
• 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 0.1 to 0.25 times the paddle diameter
• In a chain rivetted joint, the rivets in the various rows are opposite to each other
• wrong statement:

  A. The tensile strength

  B. The compressive strength

  C. In a thick cylindrical shell

  D. The value of crushing
• wrong statement:

  A. Plate tower is preferred,

  B. Plate tower is preferred

  C. The total weight of a

  D. In operations involving large temperature
• The circumferential (hoop) stress in a thin walled cylindrical vessel under internal pressure is pd/2t
• Le/D for fully open gate valves would be much less (say 2%) than that for fully open globe valves
• LMTD correction factor is used in heat exchanger design for multipass shell and tube heat exchanger
• Floating head heat exchangers are used for the cases where temperature difference between the shell and the tubes is more (>50°C)
• The most common standard size of bubble caps used in industrial operation is 6" dia cap with 4" dia riser
• The most efficient type of compensation against openings in process vessels is of nozzle or rim type
• In a distillation column, the minimum residence time for liquid in the downspout is about 8 seconds
• The thickness of the frame of a plate and frame filter is more compared to that of plates