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# Unit 4 - Introduction to Chemical Engineering - HISTORY :- Historical Development - Scope of Chemical engineering - Almost every industry requires chemical processing - air/water pollution - cosmetics industry - pharmaceutical in...

# Unit 4 - Introduction to Chemical Engineering - HISTORY :- Historical Development - Scope of Chemical engineering - Almost every industry requires chemical processing - air/water pollution - cosmetics industry - pharmaceutical industry - food industry - dying & textile industry - Semiconductor - Role of chemicals engineers in Industry & Society - Control chemical Reaction while they are processing - Reactor - Where "R" gets mixed - Requirements - vol, size, shape, speed - Arrangements - Agitator - Rn mixing - Heating & Cooling Rn. - Thermo couples - measure temp of inside & outside of Reactor - Adding catalyst and zeolites. - Cleaning - Manual - by hand - Mechanical - high pressure pump (eg. water servicing) - Chemical - by using appropriate solvent - Distillation - mass transfer operation (thermal energy) heating - vapours → Primary operation involves diffusion. - Aimost 100% pure product in single step - Separation of solute & solvent - Low BP + volatility - Separation of lig mixture into its components at its BP - High BP + volatility - History - (around 19th century) - Ayurveda - Volatility - Pottery - partially - alcohol making - ABenzene & soluble in water - Use - for - fake tooth making - Bewater (Acetic Acid) miscibl. - eye lens - 20Awator immisable (mixing) - bone joints - Bikeroseneg noe mix - Aceton - 1 - History, evolution, & Scope of Chemical Engg. - Developed Industrial chemistory in the lake igth century. - Role of chemical Engineers in industry & Society - OVERVIEW: - of Chem. Engg. disciplines (process, engineering, biochemical Engineering, Polymer/Plastics Engg, composites, blends etc). - Introduction to various different chemical industries - Prepared (straining) - Solid - Liquid / Extraction - Leaching - A+C → Feed Solvent - B- Extract, ORExtracting solvent - Liquid-liquid Extraction - A+B+C→ BCA - C-solute - B + C → B + C - Distillation - Crystallization - Supersaturation - codling substance, Evaporation → resimula/10/24 - Chemical Engineering - The production & manufacturing of products through chemical processes. This includes equipment designs, new systems, processess of retining raw materials, for mixing, compounding & processing chemicals - Chemical Engineering is as old as process industries. Its heritage dates from the fermentation & Evaporation processes operated by early civilization. Modern chem. Engg. emerge with the development of large Scale chem. manufacutring operations in the 2nd half of 19th century. - Father of Chem Angg - George Edward Lewis (1850-1907) - Is regarded as the founding father of the discipline of chemical.engg. - What is Role of Chem Enggineering? - Chem Engg deals with the application of chemistry & other natural sciences to manufacturing processes. - It focuses on using the safest & most efficient ways to make products. - Chem Engg. may be applied to any product that involves chemicals or chem. R's. including food medicine, cosmetics, perfumes, colours, surfare paints coating, plastic polymer, pharmaceutical - Chem Engg Operations - Mechanical - crushing, grinding, sedimentation,(use of mech force) agitation - Chemical-hydrolisist drying, absorption, distillation, extraction & solid, liquif fertilization - What is chem Engineer? - A chem engineer is an engineer who focuses on making industrial & consümer product through chem. methods. - Plastic: The material being moldige under pressure. - Fiber: (strongest material among there. - Melt spinning - Dry Spinning = Solution spinning - Wet spinning = gives bath and solvent remove other to prisolvent. - Rubber is elastically strong but less strong than plastic & fiber - SBR is copolymer due to having two monomer. - Impact Strength - butadene is responsible for Impact Strengthan - Discuss preparation properties application Metal & Non metal - TOPIC - Material angineering, Polymer, Plastic - METAL: gold, silver, aluminium, Copper, mild steal - NON METALA: plastic, rubber, polymer, composing lead - POLYMER: - many parts/units - plastics rubber fibre - natural synthetic - eg. Sis-polyisoprene (man-made) monomer → polymer, monomer → polymer - eg. SBR (Styrene butadine rubber), PBR, Nitrile rubber, butyl rubber - ABS-PVC - ABS-PS - Oil (petroleum) - Petrochemical - Organic substance derived from petroleum - petroleum → mineral oil - composite obtain from many dissimilar material or combination of dissimilar material - natural composites: bones, hair, skinwood - synthetic composites plywood. - Strongest Material → Fiber > Plastic > Rubber - Mass transfer - equimolar counter diffusion A ↔ B (bidirectional diffu.) - High to low volatiles → (distillation) - unidirectional diffusion A→B (gas absorption) - MASS TRANSFER - Transfer of moleculestromnigh to low conc. to minimise conc. difference - process will continue tll conc gradient becomes zero - to minimise temp diff or gradient - What is Mass Transfer? What is driving force of MT? - Types of Mass Transfer operations. - Diffusion, Mass Transfer - 1. Ordinary diffusion- Takes place in all types of Mass Transfer, 2. Thermal diffusion, 3. Pressure diffusion, 4. Forced diffusion - Convective Mass Transfer - convection manner zig zag Randomessta speed - What is Mass Transfer ? what is driving force of Mass Transfer? - Mass transter occurs due to conc. ordensity diff - There is a natural tendency for mass to be transferred, minimising the conc diff. within the mixture. - M.T. is strongly affected by molecular spacina - MT types - DIFFUSION MASS TRANSFER - Diffusion MT is classified into 4 types - DIFFUSION MASS TRANSFER - In MT, component diffuses through of stagnent liquid: - Diffusion MT is independentot of any convection current within the system. - Mol. diffusion can be further classified asini - Ordinary diffu. (due to conc. diff) - Thermal diffy. (due to temp diff) - Pressure diffusion (due to Hydrostatic pressure, acting as a driving force) - Forced diffusionCdue to action of external forces) - DMI can occur either by molecular diffusion or Eddy diffusion in gases or liquids - In mol. diffu. the transfer of matter occurs on a microscopic level as a result of diffusion from the zone of higher conc. to a zone of lower conc. in gas of liq or. a mixture of gaser & liquid - various egs of mol diffusion are:- - humidification of air in coolers, cooling towers - FA dissolution of sugar or salt & uniform spreading in water. - spreading of fragrance of perfume or flowers in surrounding - drying or clothes or timber - Evaporation of petrol inengine corporator - diffusion of neutron in nudecor reactor - diffu. of smoke from chimney into atmospheric air - In Eddy diffusion, one of the diffusing fluids need to be in turbulent motion, due to turbulence, rate of diffy increases as a result rate of MT increases. - What is Mass transfer ? - Factors affecting a mass transfer. - What is interphase and interphase mass transfer? - Expression of moleular diffusion - Na = - DAB dCA / dy Interms of Partial 'Pressure diffusion - NA=-DAB dPA / dy turbulenced rate - Na= no. of moles of A per unit area dy - DAB = diffusion coefficient (diffusibility) - CA = Molar Concentration 220M - y= direction/distance ( -ve sign be to reduce the conc.) ball - Molar concentration ==nA / V - PV=nRTPEN=CAGRONO - CA = Mass concentration 22AM - CA = MA / V - S = CA = MA / V - Factors affecting rate of mass Transfer:- - 1. Concentration Difference - 2. Temperature Difference. - 3. Degree of Turbulance - 4. Pressure Difference - Physical Properties - 1. Viscosity - 2. Density - 3. Diffusion Coefficient - Interphase & Interphase Mass transfer - Mass / Molecule transfer takes place from one phase to another phase across the boundry is called interphase. This process is called Mass Transfer. - Some common terms cused in Mass Transfer Process:- - MASS CONCENTRATION (C) - In a gas of liq mixture contains one or more components, then conc. is defined as mass of spacies of specific component per unit vol. of mixture. It is also called as density in kg/m³. So mass conc. (SA)or((A) - Mass Conc= S(A) = mass of component A / vol of mixture - Mass conc is denoted by (C) - MOLAR CONCENTRATION - It is defined as no. of moles of a specific component per unit vol of the mixture. It is also called as molar density. - Molar conc = No. of moles of component / voln of mixture - No. of moles of A = mass of comp A / mol weight of component A - Therefore, molar conc= mass of compAX 1 / vol of Mixture - Molar conc. = density of A / mol wt of A - MASS FRACTION - It is defined as conc. of comp. A to the total mass conciutaiom - Mass fractionsCA of öüconc of A / C... total conf - MOLE FRACTION - the no. of motes of comp A to the total no. of moles in the mixture - mole fraction = nA / NA + B = nA / total no. of n # Chemical Engineering Operations - 1. Chemical engineering operations due to chem Rn - 2. Mechanical Engineering Operations due to mech.forke - CHEMICAL ENGINEERING OPERATIONS - 1 Liquid Liquid Extraction (LLE) - A - Feed solvent - B- Extracting solvent - C- Solute - extract (from A By using B) - F-Feed - Atc - to keepreconomic - Ultimate Aim- Recovery of Solvent - evaporation distillation of solent - B+C → F - Pair-1 (P)) (extract phase) - A+C -P2 (Raffinate Phase) - A+B -P3 - Separation of phases onthe basis of density, solubility: - always lighter Phase - always heavier phase - 2 Drying - Removal of moisture into the atmosphere due to diffusion - Criteria for selection of solve - solubility - selectivility (β) - 1-B = y z + B >1 - non corrosive solvent towards the appratiy - low viscosity - Viscosity high, good Stability, chemically inert - low volatile - easily availabe, difficult to Stur, Plon high heat transfo - economically good -non flamable - Distillation - Selectivity, B=1, then distillation is not possible - If B>1, then easier will be the separation by distillation - Relalility = Volatility of A / Volatility of B - If 271 then easier will be the separation by distillation - Methods of distillation - Simple or differential & carry out - Flash or equillibrium, Swithout Reflera - Continuous rectification carory out with Reflux (Fractionation) - This above reaction distinguish on the basis of Reflux. - Use in distillation avai - F=D+W - Feed distillate Residue - Bottom Product produd - Fxf = Dyo + Wxw - where, oxy = mate fraction of feed - yo mole fraction of top product - nw = mole fraction of Bottom product. - Mechanical Operations - Crushing & Grinding (size reduction) - deje to mechanical force. - converting largesize into small size particles - Screening operation (separation of Solids from solids) गाळणी - finerparticles, undersized - Filtration Method. - larger particle Lover sized - Agitation & Mixing - Size Reduction. - It refers to the operation where particles of solids are cut or broken into smaller pieces. - In the chemical industry this operation is usually carried out in order to increase a surface as in most chemical reactions. - & unit operations (eg. leaching) involving solid particles. The Tate increases by virtue of increase of area of contact between the solid and the second phase. - Other reasons for carrying out size reduction include to effect the separation of two constituents when one is dispersed in small isolated pockets, to meet stringent Specificiton regarding size of commertial products, to achieve intimate mixing of solids in solid Solid operation as mixing is more complete if the particle size is small - Size reduction machines - more commonly, reduce the size of solids by - 1) compression - 2) impact - 3) rubbing or abbrition. - 4) cutting - In general compression is used in case of coarse reduction of hard solids to yield relativily few files - Impact yields coarse, medium or fine products. - Abbrition gives very fine produd from soft (non abbrazive materials). - Cutting produces a product of a definite particle size and sometimes a definite particle shape with few or more fines. - Types of Jaw crushers - The 2 distinct types of jaw crushers - i) Blake jaw crushers - iⅱ) The dodge jaw crushers. - is separation of wolids from solids - Solids may be separated by Solids in dry state by screening, Magnetic separation, electrostatic separation, etc. - Solids may be separated by Solids by method in which fur fluid motion is used in effect separation of solid purticles from each other. - Eg. Classification Hydraulig fig Tubling - This method depends upon differences in the behaviour of the particles in a moving fluids - The screening method dependsilab primarily on the size of the particles. In case of methods using fluid motion, the size & density of particles are the most important factors. - Other methods of separation make use of differences in electrical properties of material (electrostatic separation) magnetic properties of material (magnetic separation) & surface properties of material (froth food flotation) - What is Screening? - The method of separating particles according to size alone is called screening. - In industrial screening the solids (a mixture of maarious Sizes of grains) are dropped on a screening surface acting as a multiple go & nogo gaze gauge. cage - The material passing through the screen opening is called undersize or fines. while the material retained on a given screening surface is callerd. oversise, - A single screen can make single separation of the material charged into two fractions. These are called unsized fractions as only the upper or lower limit of particle sizes, they contain is known & other limit is not Known. The material is separated into sized fractions ie. The fractions in which both maximum & minimum particle sizes are known by passing it through a series of screens of different sizes.. - Screening is much more commonly adopted for dry particulate solids & occasia Occasionally for wet particulate Solids. - In this topic wew Types of Screening equipments. The screening equipments can be classifirect based largly on the size of the material as the screens may be called upon the passed grains. ranging upon several inches in diameter down to 200 mesh. 1) Grizzlies (fixed inclined screen) 2) Trommels crevolving screen) 3) Shakingand vibrating screen 4) Oscillating screen - may sulphate watere solubility → solute solvent temp - chemical engineering operations - psugar industry - 1 Crystallization - types - Mechanism of Crystallization - (ⅰ) Nucleation - (ii) Crystal Growth, - crystal - (ⅰ) Nucleation - nuclea Pormation of microsize or nanosize - growth of nuclea (size increa - Crystallization from liquid Solution: - It is a unit operation in which solid particles are formed from a liquid solutio. - Crystallization involves simultaneous & mass transfer. - Crystalliza is a solid lig operation used to separate solute from solution in the form of crystals - It is normally carried out in Process industry either from solution or polymer melt. - This operation gives almost pure product from relatively impure solutions in a single processing steps in the form of crystals of the desired size & is generally carried out at relatively low temp... - From energy point of view Crystallisation requires much low energy for separatio (solidfrom lig) as compared to distillation(1919) - Crystallization usually involves:- - (by evaporating apart of Solvent) - (ii) Cooling of solution until the conc of solute becomes greater than its solubility at the prerelling temp - Then the solute precipitate in the form of pure crystals - Significance - (ⅰ) It is more convinent to use any material in the crystalline form because it facilitates storage & packing - The performance of crystallization i's evaluated in terms of size • shape, yield, structure & purity of crystal.le - Squillibrium data (Solubility) - In crystallization process the equillibrium will be reached when the soin is saturated.& the equillibrium data will be given in the form of solubility. Curve - Solubility - The solubility of a solute in iven solvent is the conc of solute in a saturated sol at a given temp. - The solubility of solute in a given solutesolvent depends on nature of solute, nature of solvent and the prevailing temperature. - Saturation - Consider a process of dissolving Ammonium sulphate in water (solven) at a given temp. Initially when some amount of ammonium sulphate is added all of it get dissolved in water forming the sol" of ammonium sulphate in illi 115 water. - Additional amt can be dissolved further till a stage comes when no more ammonium sulphate can be dissolved ind given amount of solvent. At this stage the sol is called as a saturated sol" - Super Saturation will - Consider an equillibrium sol", if we disturb this equillibrium either by cooling the som or evaporating a part of the solvent a quantity of dissolved Solid solute will exceed the havlos equillibrium conc. and the system will try to attain a new state of equillibrium by precipitating excess solid solute present in it in form of crystals. The resulting process is called crystallization from the cone gradient driving force is called super saturation. - Unit II :- Adsorption pirying and humidification Adsorption :- - adsorption isotherms - Langnuir Isotherms - Selection criteria of adsorption - ①Adsorbent - ② Adsorbate / solute - ③ Freandlich Adsorption Isotherm- - If pressure & is high it is favourable condition for adsorption - Selection Criteria of adsorbtion - Characteristic & property of adsorbtion - The following three important attribute of an adsorbant make it suitable & effective for selection of a mixture. - it Selectivity - ⅱr Adsorption Capacity - ⅱik Reversibility of Adsorption - An adsorption must selectivily bind the target components. For the same adsorbant selectivity is guarded by the difference in affinity of the target molecule of from that of a other molecular form from active side of adsorption - Adsorption being highly porous substances, selectivity due to difference in the rate of diffusion and adsorption in same time is called Kinetic selectivity. - Further the molecular size and shape of the components in a mixture vary. Thus some of the components may not enter the porous of and adsorbant of particle in the molecular size is larger than the pour porous size. - The above three factor, Affinity, intrapartide diffusion rate & size determine the selectivity induvisaly or collectivily - The other imp characteristics of adsorbtion are - ⅰ) Particle size & its distribution - ⅰ ⅱ) Pourocity & pour size distribution.. (good adsorbtion) (ii) Poorocity must have haigh & narrow size distribution - ims specific surface area - IM Live Structural strength & stability - Common Commertial adsorbtions are - i> activated carbon - & zeolites - hiiesilica gel - ive Actived alumina - Moisture - Content on dry basis = xxx / 1 - Moisture Content on wet basis = 20 / 1+x - Humidity = Kg of moisture / kg of dryair - Beam Bin system of level measurment by. bubb.er system. - Pressure = well manometer, bellows pressure element - Weight of drying - Significance of unit & dimension - Molarity (M) = Moles of dissoned solute / liters of solution - Molality (m) = moles of solute / Kg of solvent - Normality (N) = no of gm equivalent of solute / volume of soln in liter - Motes = Mass / Molecular weight - component 'A'= moles of A / -11- B - Total moles = moles of A + moles of B - Mole fraction of A = moles of A / ma total mass - -11- B = -11B / total mass - Moisture content on dry x=x / 1 = kg of moisture / kg of dry solid = 2×100%・ - Equillibrium moisture content - The moisture content of a solid material that is in thermodynamically equillibrium with its vapour ( giver particle pressure of vapour) in the gas phase under the Specified humidity & temp of the hot gas or air is an as equillibrium moisture content (x*) - Bound Moisture Concent - It is that moisture in a solid material which extract a vapour pressure less "than that of pure liquid at the same temp - Unbounded moisture content - It is the moisture held by a solid material in excess of the equillibrium moisture content corresponding to saturation humidity. - It is primarily held in the voids of solid - excess equillibrium - Free Moisture Content - It is the moisture content by a solid material in excess by the equillibrium moisture content (x-x*) - At a given temp & humidity, it is the moisture content of a material that can be removed by drying. It may include bound & unbound moisture - Critical Moisture content - The moisture content of a material at which the constant rate period & the following rate period starts is called as critical moisture content - It is a fee function of the constant drying rate, material properties & particle size - Consent Constant Rate Period - It is the part of the drrying process. during which the rate of drying express as the moisture evaporated per unit time, per unit area of drying surface the main constant - Following Rate period - - It is that part of the drying process during which the rate of drying varies with time & the instantaneous drying ratet continuously decreases ming th - yaxis - falling 4 period - Rate of drying - moisture content - → warmind period - constant rate of drying period - Humidity (H) = Kg of water vapour / kg of dry air - Relative Humidity (RH) = PA (100) / PAo - where, PA = Partial pressure of water vapour in the mixture - PAo = vapour pressure of pure water - Dry bulb temp: - The temp of vapour gas mixture recorded by a thermometer whose bulb is kept dry is called as dry bulb temp. - Wet bulb temp: - The temp recorded by a thermometer whose bulb is kept wet by wrapping a wet cloth in the openair is Called wet bulb temp. - dea point temp - humid heat & humid volume