Process Equipment and Plant Design MCQs

Free 367+ Process Equipment and Plant Design MCQs for PPSC, FPSC, NTS, and Pakistan government job tests. Practise below with answers and explanations.

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Process Equipment and Plant Design

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1.Identify the incorrect statement from the following options:

In real-world applications, distillation columns with diameters ranging from 3 to 6 meters use bubble caps approximately 15 cm in diameter.The packing height in packed columns is roughly three times the column diameter for Raschig rings and between five to ten times the diameter for saddle packings.For a sieve tray, the smallest hole diameter matches the thickness of the tray itself.In stainless steel sieve trays, the minimum hole diameter is ten times greater than the thickness of the plate.

2.Identify the incorrect statement from the following:

Plate efficiency improves as the superficial vapor velocity rises, up to the entrainment threshold.Increasing the liquid depth around the slots enhances plate efficiency, especially when the liquid depth is less than 1 inch.If the vapor velocity exceeds the permissible limit, having very narrow plate spacing may reduce efficiency.None of the above statements are incorrect.

3.Identify the incorrect statement from the following options:

Riveting is not a method for creating a permanent joint.A joint formed by overlapping one plate over another and fastening them with two rows of rivets is known as a 'double riveted butt joint'.The rivet's shank diameter must be smaller than the hole drilled in the plate for proper riveting.The efficiency of a riveted joint is defined as the ratio between the joint's strength and the strength of a solid plate.

4.Identify the incorrect statement from the following:

Brittle materials have lower tensile strength compared to their compressive strength.Ductile materials exhibit lower compressive strength than their tensile strength.In thick cylindrical shells, the hoop stress reaches its peak at the inner surface.For long columns, the buckling load exceeds the crushing load.

5.Identify the accurate statement regarding distillation column components and operation.

A vertical condenser is typically chosen for condensing vapor from a distillation column without any sub-cooling.Weep holes help in removing leftover liquid from trays when the distillation column is shut down.Using random packing in a packed tower results in reduced pressure drop and increased fluid capacity compared to structured packing.Risers in a distillation column are usually not fastened to the trays using bolts, rivets, or welding.Sub-cooling is essential in all types of condensers used in distillation columns.

6.Identify the incorrect statement regarding the design features of a basket type evaporator.

It is designed for processing high-viscosity liquids that tend to cause heavy scaling.The tube assembly is supported by a bracket.A central downtake is absent in its design.The downtake is created by the annular space between the shell and the tube bundle.

7.Identify the incorrect statement regarding shell and tube heat exchangers:

Baffle spacing should not be less than 50 mm.The largest allowable baffle spacing matches the shell's inner diameter.Typically, the maximum unsupported tube length is around 75 times the tube diameter, but for aluminum, copper, and their alloys, it decreases to approximately 60 times.The disk and doughnut type baffle is the most frequently utilized baffle design.

8.Identify the incorrect statement regarding an agitated vertical cylindrical reactor vessel.

For most applications, the recommended liquid depth to tank diameter ratio (filling ratio) is 1.A filling ratio of 2 is suggested when dispersing gas into liquid to ensure adequate contact time.Vessels with flat or conical bottoms exhibit poor agitation efficiency when stirring heavy solids in liquids.Dished bottom vessels consume an exceptionally high amount of power during agitation.

9.Which of the following statements is accurate?

Plate towers are more cost-effective and simpler to build than packed towers when dealing with highly corrosive fluids.Packed towers are usually favored over plate towers when the liquid tends to foam.Packed towers typically experience a higher pressure drop compared to plate towers designed for the same operation.None of the above.

10.Identify the incorrect statement from the following options:

All cylindrical process vessels operating above atmospheric pressure are sealed with formed heads.The fouling factor for river water is lower compared to that of seawater.Bubble cap trays in distillation columns use risers to assist the movement of both vapor and liquid.Both statements B and C are correct.

11.Identify the incorrect statement regarding the application of valve trays, sieve trays, and bubble cap trays in continuous distillation columns.

Although bubble cap trays are the costliest, they are ideal when handling low vapor rates and require a reliable liquid seal at all flow conditions.The Murphree efficiency values of valve, sieve, and bubble cap trays are almost the same, but sieve and valve trays usually achieve higher maximum efficiency than bubble cap trays.Valve and sieve trays incur higher maintenance expenses compared to bubble cap trays because of their more complex design features.Valve trays offer the greatest turn-down ratio, meaning the widest range between maximum and minimum vapor flow rates, allowing for the most flexible operation.

12.Identify the incorrect statement regarding the design features of a sieve plate column.

Raising the weir height enhances tray efficiency but increases the pressure drop across the plate; ideal weir heights are 40-90 mm for columns operating above atmospheric pressure and 6-12 mm for vacuum columns.In segmental downcomers, the chord length ranges from 60% to 80% of the column diameter, with the initial downcomer area typically set at 12% during design.The calming section width at the inlet and outlet of the tray is 75 mm for columns under 1.5 meters in diameter, and 100 mm for those with larger diameters.The minimum downcomer residence time recommended for separating entrained vapor is identical for both foaming and non-foaming liquids, approximately 20 seconds.

13.Identify the incorrect statement from the options below:

Safety valves in heat exchangers are installed to eliminate non-condensable gases.Liquid metals and Dowtherm serve as heat transfer fluids for extremely high temperature applications.In shell and tube heat exchangers, the fluid at higher pressure is typically passed through the tubes.A loop or U-shaped seal is used in vertical condenser sub-coolers to avoid rapid condensate drainage.

14.Identify the incorrect statement regarding the Horton sphere, which is utilized for storing liquid ammonia.

The Horton sphere typically has a diameter ranging from 6 to 25 meters and is supported by 6 to 12 tubular or rolled section columns.The spherical shell thickness is approximately half that of a cylindrical vessel operating under the same pressure, and since a sphere has the lowest surface area to volume ratio, it requires less insulation.Horton spheres are designed to store gases and volatile liquids at moderate pressures between 1 and 10 kg/cm².Horton spheres are used to store liquids at extremely low temperatures and very high pressures, up to 200 kg/cm².Horton spheres are constructed exclusively from reinforced concrete for enhanced durability.

15.Identify the incorrect statement regarding distillation processes:

Vacuum distillation can be used as an alternative to steam distillation.In simple (differential) distillation, vapor is promptly removed without significant condensation.Flash (equilibrium) distillation involves vaporizing a portion of liquid so that the vapor and remaining liquid are in equilibrium.Flash distillation, differential distillation, and steam distillation are all types of continuous distillation methods.

16.What is the primary purpose of weep holes in the trays of a distillation column?

To allow liquid to drain from the tray when the column is shut downThey are typically positioned near the overflow weir to ensure liquid flow during operationThey need to be sufficiently large (generally 1/4" to 5/8" diameter) to avoid clogging but should not release excessive fluidAll of the above statements are correctNone of the above