Mechanical Operation

Mechanical Operation is a part of unit operation. It has wide applications from the point of view of chemical engineering. In mechanical operation, there are various operations, that are used in chemical engineering. In this, we study the operations involving solid particles with or without fluid. 

It involves studies regarding particle properties like size and shape of particles, particle size distribution, particle size reduction, separation of different size particles according to size using screens, separation of different particles using elutriation and classification, filtration, fluidisation, transportation of solids using conveyor. .  

Process Calculation: Absolute, Relative and Percentage Humidity

Humidity is a term to represent amount of water vapor in air. It is used in evaporative cooling, to tell weather conditions etc.
Absolute Humidity refers to amount of water vapor present in dry air. This value doesnt provide much information about the condition of air. Like absolute humidity of 0.5, air will have different conditions in summer and winter. We cant tell how close to saturation value.
 To get more information about air condition, we use relative humidity: ratio of amount of water vapor present to the amount of water vapor present if air is saturated with water at that temperature. RH = w(H2O)/w(H2O)sat For example relative humidity of 0.5 shows 50 % water vapor is present as compared to saturated air.
Percentage humidity: Ratio of absolute humidity to absolute humidity at saturation condition. It is slightly less than relative humidity.
PH: [w(H2O)/w(air)]/[w(H2O)/w(air)]sat

Chemical Engineer: An Enterpreneur

Now a days, there are large no of small industries that can be started related to chemical engg. For example one is oil extraction and cattle feed from cotton seed. In this there are conveyors to carry material, a machine to extract oil by squeezing it and refinery to purify oil.The single unit starts around 10 lacs. There are other small industries also like paper plates, plastic glass and various other industries.

Application based Education

In school, I was taught various subjects. After my 10th I opted science, then I thought why did I study social science, sanskrit. It seemed to be useless. But one thing that I understands every subject has its own significance like math improves calculation, ablity to strike the problem faster, social science and sanskrit improves memorization.
But one thing I coulnt undrrstand that likein maths tthere is matrix, differentiation and integration. I was not told their applications. Like matrix is used to solve simultaneous equations, usrd zo enter data in computation like in matlab, intergration is used to find the solution when we have to consider a differential elements. Like these applications can enhance the learning abilities of students.

Mass Transfer: Distillation Process

Distillation is a very important mass transfer operation which is used to separate components on the basis of difference in boiling points. It is mainly used in refineries to distil crude oil into useful petroleum products.
As in distillation, all the components are volatile, so all components will be there in liquid and vapour phase, but the more volatile component (lesser boiling point), has more tendency to be in vapour phase as compared to liquid phase at any temperature. 

Distillation column is divided into 2 sections depending on concentration of more volatile component. The two sections stripping section and rectifying section or extraction and enriching section. These sections are divided based on the location of feed plate.

Above the feed plate, where the more volatile component has higher concentration as compared to other component gets enriched or rectified is rectification/enriching section.

And below the feed plate, where the more volatile component generally has lower concentration as compared to other component gets extracted or stripped from the solution is stripping/extraction section.

In distillation of binary mixture let say benzene (x in liquid, y in vapor) and toluene ;
Let at any plate x = 0.3 and y = 0.6; then how can benzene be transferred from the liquid to vapour phase, that means low concentration (0.3) to high concentration (0.6)? The answer is equilibrium concentration of benzene in liquid and vapor phases.
The concentration can be expressed as pressure of benzene. The saturation pressure of benzene in the liquid phase (ideal) is calculated through Raoult’s law (p_A = x_APv) and vapor phase pressure is calculated by Dalton’s law (p_A = y_AP_T); if the saturation pressure in liquid phase is higher, then the component will go in vapor phase increases till the pressure in vapor phase becomes equal to liquid phase saturation pressure. The equilibrium composition changes with temperature, therefore the temperature increases as we go down the column.
When vapour and liquid streams at different temperatures (not in equilibrium) are brought in contact, more volatile in the liquid phase will vaporise and less volatile from the vapour phase will condense. So, vapour phase will be enriched with more volatile and liquid phase will be enriched with less volatile components.

Fluid Flow: Types of Fluids

Every fluid behaves differently according to particle size, shape, distribution, particle volume fraction, particle-particle interaction. There are some external parameters also that affect the behaviour like type, rate, and time of deformation. The fluids are categorized in time dependent (thixotropic and rheopectic) and time independent (Newtonian and non-Newtonian fluid).  

1. Thixotropic: Viscosity decreases with time of deformation, that does not get thicken with time like paint should be thixotropic

2. Rheopectic: Viscosity increases with time of deformation

3. Newtonian Fluid: Viscosity remains constant with time and rate of deformation

4. non-Newtonian Fluid:

a) Dilatant: Viscosity of fluid increases with rate of shear that doesn't get diluted i.e. shear thickening. These type of fluids can be used to make bullet proof jacket i.e. when force is applied it will behave like a solid. One more application can be in the knee joint, where we need a material that acts like a solid when we rest and act like a lubricant when we move.

b) Pseudoplastic: Viscosity of fluid decreases with rate of shear i.e. shear thinning. Like toothpaste, when we hold it in upside down, it will not come out, but when we apply a force, it starts coming. i.e. viscosity of the paste decreases.

Mini Projects

There are small projects but that can be helpful. like one
1. The timer for the turn indicator in motor bike. When we would like to take a turn, we give indicator. but sometime we forget to switch it off. there can be a timer set for 30 sec or 1 min to switch it off automatically.
2. The temperature of water cooler can be controlled to save electricity.
3. Security system for cycles, motor cycles.
4. The temperature of water in air cooler can be utilized to cool the temperature of water for other applications.
5. The water pump in air cooler can be controlled by the level of water in cooler.
6. The pump used to supply water at higher altitude can be controlled by flow of water inside the pipe.