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Home Chemical Engineering Process Equipment and Plant Design Comments

  • Question
  • Correct use of 'factor of safety' is very important in equipment design. It is defined as the ratio of the


  • Options
  • A. ultimate stress to breaking stress.
  • B. ultimate stress to working stress.
  • C. working stress to ultimate stress.
  • D. none of these.

  • Correct Answer
  • ultimate stress to working stress. 


  • Process Equipment and Plant Design problems


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    • 1. Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column.

    • Options
    • A. Bubble cap trays though most expensive are the best in situations, where low vapour rates is to be handled and a positive liquid seal is essential at all flow rates.
    • B. Murphree efficiency of all the three trays are nearly equal, however the peak efficiency is generally higher for seive and valve trays than the bubble cap.
    • C. Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features.
    • D. Valve trays have the highest turn down ratio (i.e. the ratio of the highest to the lowest vapour flow rates) and thus provides the maximum flexible operating range.
    • Discuss
    • 2. The ratio of shear stress to shear strain is called

    • Options
    • A. bulk modulus
    • B. shear modulus
    • C. modulus of rigidity
    • D. modulus of elasticity
    • Discuss
    • 3. 25 per cent cut segmental baffle means that the baffle

    • Options
    • A. height is 75% of the I.D. of the shell.
    • B. height is 25% of the I.D. of the shell.
    • C. spacing is 75% of its height.
    • D. width is 25% of its height.
    • Discuss
    • 4. Fresh water carrying pipelines in chemical industries are coloured with __________ color.

    • Options
    • A. sea green
    • B. brown
    • C. yellow
    • D. red
    • Discuss
    • 5. Smaller sized packings are generally dumped to the packed columns, and the large ones of size greater than __________ mm are stacked individually, which provides better control over bed porosity and offers lower gas pressure drop.

    • Options
    • A. 25
    • B. 50
    • C. 75
    • D. 150
    • Discuss
    • 6. Pick out the wrong statement pertaining to the design of the bubble cap tray of a distillation column to give stable operation and even vapour distribution.

    • Options
    • A. The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation.
    • B. Tendency towards stable operation is increased by increasing the skirt clearance of the caps, lowering the rate of liquid flow per unit plate width or increasing the spacing between the caps.
    • C. The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4.
    • D. none of these.
    • Discuss
    • 7. It is not desirable to design a heat exchanger for LMTD correction factor, FT, of less than

    • Options
    • A. 0.99
    • B. 0.95
    • C. 0.80
    • D. 0.55
    • Discuss
    • 8. Bracket supports are the most suitable for supporting __________ vessels.

    • Options
    • A. thick walled vertical
    • B. horizontal
    • C. thin shperical (e.g. Horton sphere)
    • D. none of these
    • Discuss
    • 9. Holes of a sieve tray are arranged in triangular pitch of __________ times the hole diameter.

    • Options
    • A. 1.5 to 2
    • B. 2.5 to 5
    • C. 5 to 10
    • D. 10 to 15
    • Discuss
    • 10. Which of the following is not a valid assumption in continuous binary distillation for calculating the number of equilibrium stages by Mc-Cabe-Thiele's method?

    • Options
    • A. Sensible heat changes for vapour & liquid are negligibly small.
    • B. Reflux is not a saturated liquid.
    • C. Molar latent heat of the two components are equal.
    • D. Heat of mixing of normal liquid is assumed to be zero.
    • Discuss


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