advance in mass transfer in food application
TRANSCRIPT
05/02/2023
ADVANCE IN MASS TRANSFER IN FOOD APPLICATION
1
Prasented bySwapnil Prashant Gautam15/PFT/007M.Tech (food tech)First Year
05/02/2023
DIFINITION
2
Mass transfer is the net movement of mass from one location, usually meaning stream, phase, fraction or component, to another. Mass transfer occurs in many processes, such as absorption,evaporation,adsorption,drying,precipitation,membrane filtration,and distillation. Mass transfer is used by different scientific disciplines for different processes and mechanisms.
The phrase is commonly used in engineering for physical processes that involve diffusive and convective transport of chemical species within physical systems.
05/02/2023
EXAMPLE
3
Some common examples of mass transfer processes are the evaporation of water from a pond to the atmosphere, the purification of blood in the kidneys and liver, and the distillation of alcohol.
In industrial processes, mass transfer operations include separation of chemical components in distillation columns, absorbers such as scrubbers, adsorbers such as activated carbon beds, and liquid-liquid extraction.
Mass transfer is often coupled to additional transport processes, for instance in industrial cooling towers. These towers couple heat transfer to mass transfer by allowing hot water to flow in contact with hotter air and evaporate as it absorbs heat from the air.
05/02/2023
FUNDAMENTAL OF MASS TRANSFER
4
A group of unit operations for separating the components of mixtures is based on the transfer of material from one homogenous phase to another. The driving force for transfer is a concentration difference or a concentration gradient; much like a temperature difference or a temperature gradient provides the driving force for heat transfer.
These methods, covered by the term mass-transfer operations,include such techniques as indicated below:
• Distillation• Gas absorption• Dehumidification• Liquid extraction• Leaching• Drying
05/02/2023
Distillation
5
The purpose of distillation is to separate, by vaporization, a liquid mixture of miscible and volatile substances into individual components or, in some cases, into groups of components. The separation of a mixture of alcohol and water into its components; of air into nitrogen, oxygen, and argon; and of crudepetroleum into gasoline, kerosene, fuel oil, and lubricating stock are examples ofdistillation
05/02/2023
continue
6
05/02/2023
distillation has many applications
7
In the fossil fuel industry distillation is a major class of operation in obtaining materials from crude oilfor fuels and for chemical feedstocks.
Distillation permits separation of air into its components — notably oxygen, nitrogen, and argon — for industrial use.
In the field of industrial chemistry, large ranges of crude liquid products of chemical synthesis are distilled to separate them, either from other products, or from impurities, or from unreacted starting materials.
Distillation of fermented products produces distilled beverages with a high alcohol content, or separates out other fermentation products of commercial value.
05/02/2023
GAS ABSORPTION
8
Gas absorption (also known as scrubbing) is an operation in which a gas mixture is contacted with a liquid for the purpose of preferentially dissolving one or more components of the gas mixture and to provide a solution of them in the liquid.
05/02/2023
continue
9
The principal requirements of a tower packing are
It must be chemically inert to the fluids in the tower.
It must be strong without excessive weight.
It must contain adequate passages for both streams without excessive liquid holdup or pressure drop.
It must provide good contact between liquid and gas.
It must be reasonable in cost.
05/02/2023
Dehumidification
10
The process in which the moisture or water vapor or the humidity is removed from the air keeping its dry bulb (DB) temperature constant is called as the dehumidification process. This process is represented by a straight vertical line on the psychrometric chart starting from the initial value of relative humidity, extending downwards and ending at the final value of the relative humidity.Dehumidification process along with cooling or heating is used in number of air conditioning applications. Let us see how these processes are obtained and how they are represented on the psychrometric chart
05/02/202311
05/02/2023
Liquid extraction
12
Liquid–liquid extraction also known as solvent extraction and partitioning, is a method to separate compounds based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent. It is an extraction of a substance from one liquid into another liquidphase.
05/02/2023
Leaching
13
Leaching normally refers to the removal of a substance from a solid via a liquid extraction media. The desired component diffuses into the solvent from its natural solid form. Examples of leaching include the removal of sugar from sugar beets with hot water and the removal of nickel salts or gold from their natural solid beds with sulfuric acid solutions.Application:It is used for leaching of gold from its ore by using sodium cyanide solutions.
It is used for extraction of oil from oilseeds such as soyabeans by using hexane or petroleum ether as a solvent.
It is used for extraction of sugar from sugar beats using hot water.
It is used for extraction of tannin from tree barks using water.
It is used for extraction of medicinal compounds from plant roots, leaves and stems.It is used for extraction of perfumes from flowers.
It is also used for preparation of tea and coffee.
05/02/202314
DryingDrying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging productsApplications of drying:Food source:Foods are dried to inhibit microbial development and quality decay. However, the extent of drying depends on product end-use. Cereals and oilseeds are dried after harvest to the moisture content that allows microbial stability during storage. Vegetables are blanched before drying to avoid rapid darkening, and drying is not only carried out to inhibit microbial growth, but also to avoid browning during storageNon food source:Among non-food products, those that require considerable drying are wood (as part of Timber processing), paper, flax, and washing powder. The first two, owing to their organic origins, may develop mold if insufficiently dried. Another benefit of drying is a reduction in volume and weight.
05/02/202315
05/02/202316