Applied Chemistry - Lec 1 - Introduction.pdf
- 1. APPLIED CHEMISTRY • Applied Chemistry is the scientific field for understanding basic chemical properties of materials and for producing new materials with well-controlled functions. 1
- 3. UNIT OPERATIONS • A unit operation is defined as a process which does not involve any chemical reaction. • Unit operations only deal with physical changes of the materials involved in the process. • They are equipment which cause the materials to undergo physical changes. 3
- 4. • The physical changes are carried out for variety of purposes. • Generally, unit operations steps are carried out before subjecting the materials to chemical reactions so that chemical reactions happen smoothly. • The physical changes can imply phase changes such as; evaporation, condensation, crystallization etc. • Thus, Distillation is a unit operation step because condensation and evaporation happens inside the column. 4
- 5. • Evaporators, and crystallizers are also unit operations equipment. • Unit operation equipment are also responsible for mechanical operations which involves size reduction, physical separations, mixing, and grinding. • The mass transfer, heat transfer process all may happen together. • Chemical reaction doesn’t happen. 5
- 6. The unit operations are classified in the following manner: • Fluid flow operations: Pumping, compression, and fluidization. • Mechanical operations: Size reduction, size enlargement, mixing, agitation, blending, filtration, classification- separation, etc. • Mass transfer: Distillation, evaporation, crystallization, leaching, absorption, adsorption, extraction, etc. • Heat transfer: When materials are handled the heat transfer can take place by any fundamental mechanism; conduction, convection, or radiation. 6
- 7. UNIT PROCESS • Chemical reaction is at the heart of the unit processes. • A chemical reactor is an equipment which falls under the category of unit processes. • Literal chemical change takes place inside the equipment wherein the chemical structure of the material changes and it transforms and forms an entirely new material. 7
- 8. • All kinds of chemical reactions carried out in industrial equipment comes under this category. • Some examples of such chemical reactions are; sulphonation, nitration, halogenation, alkylation, hydrolysis, hydrogenation, polymerization, oxidation, reduction, etc. • The examples can be innumerable as there can be innumerable compounds which can be formed by reaction of two or more materials or by decomposition of the material itself. • Thus, classification can be similarly endless. 8
- 9. • Most of the chemical reactions are irreversible in nature. • A chemical reaction step in a process forms the heart of the process, often governing the economics of the entire process. • Thus, the unit processes are often subject of optimization. 9
- 10. • Often unit operations must be carried out before unit processes to give proper shape to the materials so that they will be able to react optimally. • Also, unit operations are often needed even after the chemical reaction has happened, they are needed for the purpose of separation of the primary product from the secondary or tertiary products. • All the unit operation processes wherein chemical reaction is made to take place to improve the efficiency of the equipment also falls under unit processes. • For example, reactive distillation, reactive extraction, reactive absorption, etc. 10