HANDOUTSSubject: CPI

Faculty: Ms. Nikita P. Chokshi

Lecture 1,2,3:Unit 1: Introduction

Objective: In this chapter we will see the importance of chemical industries. Different types of processes, basic laws which governing any chemical process and different symbolic representation of unit operations and its applications.

Introduction to Chemical Process Industries:

Chemical industries and it's importance Every product from chemical industries is combination of different unit operations and unit

processes. Unit Operations: The operation in which physical change takes place is defined as unit

operations. For e.g. mass transfer operations like distillation, absorption, leaching; solid fluid operations like size reduction; fluid flow operations etc.

Unit processes: The processes in which chemical changes are taken place are known as Unit processes. Like Nitration, Hydrolysis, Combustion, Sulfonation etc.

Classification of chemical processes:

The chemical processes are classified on the basis of introduction of raw materials in the operating system and the way the product is removed. The classification as :

a. Batchb. Continuousc. Mixed.

The batch or periodic process is practiced when the production is small or where handling of small quantities at one time is desirable for the sake of safety.

When the market enlarges, the changes are made to continuous processing. In continuous processing, the introduction of initial materials & withdrawal of product is continuous. In the mixed process, the reacting material is fed continuously while the product is withdrawn periodically.

Batch Vs Continuous processing:

Batch Process Continuous Process

Small quantities to handle per day. Large quantities to handle.

Poor parametric control. Precise parametric control

Non uniform product quality. Uniform product quality.

Do not need more concise control of flows and parameters

Needs more concise control of flows & parameters, hence needs quality

instrumentation

More man power requirement Less man power requirement

Large size equipment are required for desired production capacity, result in higher equipment cost.

Smaller size equipment are required for the desired capacity.

Poor housekeeping Better house keeping

Flow – sheeting:-

The uses of flow sheets allow a great deal of information to be collected and examined in the small space. The flow sheet is the key document in the process design. It shows the arrangement of the equipment selected to carry out the process, the stream connections, stream flow rates and compositions and operating conditions.

Process flow sheet = a diagrammatic model of the process.

The flow sheet is drawn using standard equipment symbols and using material balance & energy balance made over the process & service equipments.

Types of Flow sheets:-

1. Block Diagrams: - A block diagram is the simplest form of presentation each block represents a single piece of equipment or a complete stage of process. They are useful for showing simple processes.

2. Process Flow Diagrams (PFDs):- The PFDs are used for design and operation. The equipments are shown in pictorial form. The data on the PFD may include various information and represented by various forms.

Essential information: - Stream composition, flow rate, stream temperature, operating pressure.

Optional information: - Molar percentage, physical property data, stream name, enthalpy etc. The laws:-

i) Law of conservation of Mass.ii) Chemical kineticsiii) Laws of chemical equilibriumiv) Laws of thermodynamics.

Law of conservation of Mass:-It is used in chemical engineering to calculate the amount of materials resulting form a process as well as the amount of starting material. The accounting of all mass & energy is referred to as material & energy balance.

The accumulation within the system = ( total mass entering the system – total mass

leaving the system)

When there is no accumulation in the system,

Total mass entering the system = total mass leaving the system.

Chemical kinetics:-Chemical kinetics is the study of rates of chemical reactions, the factors which affect the rate and the intermediate steps or mechanism of a reaction.

Factors affecting reaction rates:-1. Nature of Reactants2. Temperature: Most chemical reactions are accelerated by increase in temperature. An

increase in temperature causes the reaction rate to increase in two ways. As the temperature rises, more molecules gain the minimum energy necessary for the reaction to occur when they collide.

3. Catalyst: - A substance which accelerates or retards a chemical reaction by its mere presence and remains unchanged in composition and in weight at the and of reaction is called a ‘catalyst ‘.

4. Concentration or pressure: - if all other condition is the same, the rate of a given reaction depends mainly upon the concentration of reacting substance. Due to increase in the concentration of reactants, the rate of reaction increases.

5. Particle size and physical state of reactants. Chemical equilibrium:- Transformation of substances from one form into another is known as reaction. Chemical

reactions are of two types. Either heat energy is given out or heat is absorbed. During a chemical reaction when heat energy is given out, the reactants lose heat energy and

changes into product. These types of reactions are known as ‘exothermic reactions’. Chemical reactions accompanied by the absorption of heat are called ‘Endothermic

Reactions’. Reactions in which the reactants & products are in the same state and are completely miscible

into each other forming a homogeneous mixture are called ‘homogeneous reactions’.N2 + 3H2 2NH3

Reactions in which the reactants & products are in the different states & are not miscible into each other are called ‘heterogeneous reactions’.

C + O2 CO2

Solid Gas

Reversible & Irreversible reaction: A reversible reaction in which the forward and backward reaction proceeds with the same

rate is called a equilibrium reaction or balanced reaction. The chemical equilibrium is attained at a particular temperature, pressure and concentration.

Any change in these condition shifts equilibrium. Effect of temperature on equilibrium:- Generally, the velocity of chemical reaction increases with a rise in temperature and

decreases with fall in temperature. In reversible reaction one of the reaction as exothermic, while the other is endothermic.

Experimentally it has been prove that any rise in temperature of a system in equilibrium shifts the equilibrium in the direction of the endothermic reaction. In the other words, the reaction in which heat is absorbed is favored by increasing the temperature.

e.g. 2SO2 + O2 2SO3 + heat

It is reversible reaction in which the forward reaction is exothermic and the backward reaction is endothermic. Thus, rise in temperature favors endothermic i.e. backward reaction. So, a decrease in temperature, will favor the forward reaction.

Effect of pressure on equilibrium:- Changes in pressure have hardly any effect on reactions, taking place in solid or

liquid state. But pressure changes are playing an important role in gaseous reactions. As a general rule “if the pressure on the system in equilibrium is increased the

reaction which involves the decrease in volume is forward.N2 + 3H2 2NH3

1 3 2

From the above equation, the forward reaction takes place with a decrease in volume. So, an increase in pressure favors the forward reaction. Le – Chatelier Theorem:- In 1888, a French chemist, Le – Chatelier stated his theorem which enables us to

predict the effect of change of temperature, pressure and concentration on equilibrium reaction.

The theorem states as: “whenever a system in equilibrium is subjected to any change in temperature, pressure or concentration, the equilibrium shifts in such a direction so as to minimize the effect of the change imposed”.

Reference Books:1. G. F. Austin, ‘Shreve’s Chemical Process Industries’, 5th Ed., McGraw Hill Pub.2. M.Gopala Rao  & Marshell Sitting,’Drydens outlines of chemicals Technology’,2nd Ed.,

East West  Publications3. M.V. Naik, Chemical Process Technology, Nirali prakashan.

Lecture 3: Classification of Chemical process industries. Introduction and symbolic representation of Unit operation and Unit Process.For e.g.

Drying of solids

a. Spray dryer

b. Rotary dryer

c. Tunnel dryer

Suitable for large capacity operation on liquid feed to give powdered, spherical, free flowing product.

Suitable for drying free- flowing granular solids which do not dust or stick, high temperature

Applicable to drying pastes or powders in trays, also used to dry leather, lumber etc. in sheet or shaped forms

Evaporation

Open Pan

Used for small batches, often of viscous materials, such designs are easy to clean

And discuss other unit operations with their symbols and applications.

Lecture 4, 5:Unit 2: Fertilizer Industries

Introduction to Fertilizer Industries:

Major constituent NPK essential in fertilizer and its role.Synthesis gas: What is Synthesis gas? Explain different way of getting synthesis gas.Explain steam reforming and partial oxidation process in detail with major engineering

problems.Next after synthesis gas explain uses of synthesis gas.

Lecture 6, 7:

Ammonia Production: Most of the ammonia is used on site in the production of urea. The remainder is sold domestically for use in industrial refrigeration systems and other applications that require anhydrous ammonia. The urea is used as a nitrogen-rich fertilizer and as such is of great importance in agriculture.

Properties and uses of Ammonia, manufacturing of Ammonia and explain major engineering problems related to ammonia production.

Give emphasis on Ammonia converter as auto thermal reactor.

Lecture 8, 9:

Urea production: Urea [CO (NH2)2], also known as carbamide or carbonyl diamide, is marketed as a solution or in solid form. Most urea solution produced is used in fertilizer mixtures, with a small amount going to animal feed supplements. Most solids are produced as prills or granules, for use as fertilizer or protein supplement in animal feed, and in plastics manufacturing. About 85 percent Urea was used in fertilizers (both solid and solution forms), 3 percent in animal feed supplements, and the remaining 12 percent in plastics and other uses.

Major engineering problems in Urea production.

In the process, ammonia and carbon dioxide are fed to the synthesis reactor which operates around 180-210oC and 150 bar pressure. The reaction mixture containing ammonia, ammonium carbamate and urea is first stripped of the ammonia and the resultant solution passes through a number of decomposers operating at progressively reduced pressures. Here the unconverted carbamate is decomposed back to ammonia and carbon dioxide and recycled to the reactor.The urea solution is concentrated by evaporation or crystallisation, and the crystals can melted to yield pure urea in the form of prills or granules. Prills are made by spraying molten urea from the top of a high tower through a counter current air stream. Granular urea is formed by spraying molten urea into a mixture of dried urea particles and fines in a rotating drum.Lecture 10, 11: Overview of biofertlizers

Lecture 12, 13:Unit 3: Inorganic Chemical Industries

Sulfur and Sulfuric acid:

Properties and Uses of Sulfur Frasch process, Finnish process, Oxidation reduction of H2S three different processes for

Sulfur production. FRASCH PROCESS:

Discuss the major engineering problems of each process in detail. Discuss the oxidation reduction of H2S process in detail. Properties and uses of Sulfuric Acid

Lecture 14, 15:

Discuss the Finnish process in detail and explain major engineering problems.

Lecture 16, 17:

Contact process for Sulfuric acid production: Mainly three steps,

1. makes sulphur dioxide,2. converts the sulphur dioxide into sulphur trioxide (the reversible reaction at the

heart of the process),3. Converts the sulphur trioxide into concentrated sulfuric acid.

Major engineering problems related to process.Lecture 18, 19: Introduction to Chlor-Alkali Industry: Chorine, Caustic soda, Soda Ash production,

Properties and Uses of each. Soda Ash: Soda ash is used in many industrial processes like Glass making, Water treatment,

Paper making, Soaps and Detergents etc.

Soda Ash production by Solvay process: The Solvay process, also referred to as the ammonia-soda process, has been the major industrial process used in the production of soda ash (sodium carbonate) for nearly 125 years. Soda ash itself is among the most important products produced by the chemical industry, and is used in enormous quantities to manufacture glass and other products. The ammonia-soda process was developed into essentially its modern form by Ernest Solvay in the 1860's. The ingredients for this process are readily available and inexpensive: salt brine (from inland sources or from the sea) and limestone (from mines).

Chemical reactions of Solvay process

Major Engineering problems of Solvay process Dual process Ammonia recovery unit.

Lecture 20: Caustic Soda solutions are produced as a co-product with Chlorine electrolytically by three

technologies: mercury cells, membrane cells, and diaphragm cells. Each of these processes utilizes NaCl salt as the primary raw material. The salt is electrolytically split using direct current (DC) electricity, resulting in Chlorine and an available sodium ion (Na+) that is reacted with water in the cell to make Caustic Soda and by-product Hydrogen. The hydrogen by-product produced is used as a fuel source, sold to hydrogen customers, or to produce high purity (burner grade) Hydrochloric Acid.

Explain construction and working of Diaphragms cell, Membrane cell, Mercury cell in detail with advantages and disadvantages.

Diaphragm Cell:

Membrane Cell:

Mercury Cell:

Comparison of Diaphragms cell, Membrane cell, Mercury cell

Lecture 21:

Electrolysis process for Caustic chlorine production.

Major engineering problem of Electrolysis process

Lecture 22, 23:

Production of phosphorus

Phosphoric acid production:

Lecture 24, 25:

Pulp and paper industry, Different processes for pulping Chemical wood pulping involves the extraction of cellulose from wood by dissolving the

lignin that binds the cellulose fibers together. The 4 processes principally used in chemical pulping are Kraft, sulfite, neutral sulfite semi chemical (NSSC), and soda. The first 3 display the greatest potential for causing air pollution. The Kraft process alone accounts for over 80 percent of the chemical pulp produced. The choice of pulping process is determined by the desired product, by the wood species available, and by economic considerations.

Kraft Process: The process name is derived from German kraft, meaning strength/power. The Kraft process (also known as Kraft pulping or sulfate process) is used in production of paper pulp and involves the use of caustic sodium hydroxide and sodium sulfide to extract the lignin from wood chips.

Explain the Kraft process for pulping in detail.

Lecture 26:

Explain chemical recovery from black liquor:

Lecture 27:

Explain second method for pulping Sulfite process. Comparison of sulfate and sulfite process: Kraft process differs from the sulfite process by

using alkaline solution, which is less corrosive to the equipment. Sulfite process cannot process pulp from all wood species, for example from pine. Kraft process is also more

efficient than the sulfite process. It produces stronger fiber, however the fiber is also rougher and darker that makes it somewhat more challenging to bleach.

Lecture 28: Paper production:

Additives used in paper industries

Handout 29: Carbohydrate Industries

Manufacturing Of Sugar:

Methods of production:a. Extraction of sugar cane to produce crystalline white sugar.b. Extraction sugar cane to produce gur, a dark brown sugar concentrate.c.

Major Engineering Problems:a. Extraction of juice form caneb. Choice of flocculation agentsc. Evaporation and crystallizationd. Separation of crystals from syrupe. Inversion of sugar

Handout 30Starch:

Starch is a high polymer carbohydrate occurring in grains and roots in the form of granules of 3-100µ size. These granules can be extracted from the grains by water hydration of the cells. Starch Derivatives:

1. Dextrin: Heat and acid depolymerization yields a water soluble carbohydrate gum which is used in adhesives and gums. There are two methods use for

production of dextrin are batch heating in scraping type autoclave units and fluidized hydrolysis.

2. Dialdehyde starch: An oxidized form of starch which is used in the paper industry as a wet strength additive and in adhesives.

Manufacturing of Sugar

Manufacturing of starch

Handout 31: Fermentation Industry

Fermentation processes utilize microbiology in producing chemical compounds but have a history similar to all natural product processing. Those processes yielding simple

structural chemicals, e.g. ethanol, butanol are gradually being replaced by synthetic processes with cheap and abundant raw materials. Fermentation processes are still useful for production of complex organic chemicals such as medicinals, antibiotics and for chemicals of more complexes structure such as citric and lactic acids derived from low-cost carbohydrate source.Manufacturing of Ethyl Alcohol:

Handout 32, 33: Oil, Soap and Detergent

Solvent Extraction of oil:

Handout 34, 35:

Soap:

Handout 36, 37:

Production of cement:

Handout 38-42:

Unit 5: Overview of petroleum refining and petrochemicals

Overview of petrochemical industry:

Handout 43-45:

Polymerization Industries

Types of polymers on the basis of origin

Polymerization Techniques

Bulk Polymerization Solution Polymerization Emulsion Polymerization Suspension Polymerization