Mass Transfer In Chemical Engineering Mass Transfer Operations

CONTENT INTRODUCTION DEFINATION OF MASS TRANSFER OPERATION IN MASS TRANSFER SOLVENT IN GAS ABSOROTION

INTRODUCTION Mass Transfer is the net movement of mass from one location usually meaning stream phase fraction or component another. Mass transfer occurs in many process such as absorption, drying, evaporation, distillation.

MASS TRANSFER Definition :- The process of transfer of mass as a result of the concentration difference of the component in a mixture is called as a mass transfer. or Transfer of mass from one body to another body due to concentration difference at molecular scale is called mass transfer.

Operation In Mass Transfer Types Of Operation In Mass Transfer Absorption Drying Distillation Evaporation

ABSORPTION Absorption is a physical or chemical phenomenon or a process in which atoms molecules or ions enter some bulk phase –liquid or solid material.

DRYING Drying is gas solid operation. In general it means the removal of a relatively small amounts of water from a solid material in case of drying there are two phases and three components.

DISTILLATION Distillation is a gas-liquid operation it is a method of separating the components of a liquid mixture by use of thermal energy. The difference in vapour pressure of different component is responsible for such a separation is also called distillation.

EVAPORATION Evaporation is a type of vaporization that occurs on the surface of a liquid as it is change into the gaseous phase.

Solvent in gas absorption The solubility of the solute gas in solvent should be high so that less amount of the solvent will be required for a given absorption duty In general for good solubility of the solvent chemical nature should be similar to that of the solute

VOLATILITY:- As the gas living the an absorption in unit it generally saturated with the solvent there will be a loss solvent with the gas living the unit operation Hence to minimize the solvent lose .The solvent should be as for as possible less volatile.

CORROSING NATURE The solvent should be non crossing toward common material of the construction .So that construction material for an absorption in an equipment will not be to expansion.

VISCOSITY The solvent should have low viscosity for rapid absorption rates low pumping cast and better heat transfer. MISCELLANEOUS The solvent should be non toxic non flaming non flammable and chemically stable foam handling storage point of view

GAS ABSORPTION EQUIPMENT MECHANICAL AGITATED VESSEL Used in small scale industry. This unit gives performance equivalent to one thermal stage. It consist of baffled vessel usually incorporating an open or disc flat blade turbine type agitator as it maintained very large discharge velocities normal to the gas flow.

TOWER PACKING Many types are packing are in use ranging from simple to complex geometric shapes packing are made of ceramics metals and plastic and vary in size from 6to7 mm.

TYPES OF PACKING RANDOM PACKING REGULAR PACKING The individual piece are not arranged in any particular pattern. In case of randomly packed installation for obtaining high and uniform voyage and preventing breakage tower is first filled with liquid and packing are then dumped in to it.

REGULAR PACKING :- The individual piece are arranged in regular pattern In case of regularly pattern installation for high obtaining and uniform voyage are preventing breakage tower is first with liquid packing are then dumped in to it.

LAWS USE IN MASS TRANFER HENRY LAW ROAULT’S LAW :- HENRY LAW - It state that he mole fraction of a solute gas dissolve in a liquid is directly proportional to the equilibrium partial pressure of the solute gas above the liquid surface. P = H Xa

ROAULTS LAW :- It states that given temperature the partial pressure of a component A of a solution in the vapour phase is equal to the product of the mole fraction of the component A in the liquid phase and the vapour pressure of the component A in the pure state mathematically. Pa = P*Xa

FICK’s LAW :- The flux of diffusing component of a in z direction in a binary mmixture is directly proportional to the molar concentration gradient. JA = -DAB dca/dz

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