a Why gas absorption towers are usually designed based on overall div force for

Question

a Why gas absorption towers are usually designed based on overall div force for gas phase?(296) (b) Why cooling towers are classified as humidification equipment?02%) >Why dryers that exposed the solids to a hot gas are called adiabatic dryers?(296) (d) Why two beds are used for a typical adsorption system?(2%) Show number of transfer units (NTU) for gas absorption tower, cooling tower adiabatic dryer, and adsorber, correspondingly. (8%) For straight operating and equilibrium lines,how to evaluate the driving force for the transfer process by those at the two ends of the column (5%) Show how the design of the equipment can be more appropriate by considering the fact that the equilibrium line is slightly curved. (3%)

Explanation / Answer

a) For the removal of toxic gases from effluent the absorption towers are used. it may consist of many number of plates or different types of Packings. The compostion of gas changes on each plates. but we donot consider, change in composition of gas at the different plates (trays) because they are not in complete equilibrium. so we take initial and final composition of gases on Whole tower. So the over all driving force is taken on whole tower.

b) Cooling tower is used to decrease the temperature of hot water. The water evaporate when it is in contact with dry gas (air) ,hence decrease the temperature of hot water by taking latent heat of vaporization. so on evaporation the air humidify ( water vapor is added in air) thats why it is called humidifying equipment.

c) in drying process the liquid evaporates from solid material. the hot gas is passed through the drier. but it is known as adiabatic drier because there is no supply of heat to the solid material. the total heat of system ( solid + gases) remain conserved. hence it is known as adiabatic drying

d) It is not possible to remove all contaminent from single adsorption system. the removal efficiency increases as the number of bed increases. when we use single bed for adsorption there will be inefficient use of solid bed material ( hence efficiency decreases), adsorption also occure at only on surface , to provide more surface area more beds arebeing used. so more than 1 bed is efficient or 2 beds are being used.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.