Group 2

Chemical reaction engineering is that engineering activity which is concerned with the exploitation of chemical reactions on commercial scale.
The areas of different fields of science like:


Oil Refining
Pharmaceuticals
Biotechnology
Chemical Industries
Sustainable Development

1. Contents : Batch Reactor and Plug Flow Reactor by Aamir Shahzad Mixed Flow Reactor by Hafiz Shoaib Munir Reactions by M. Waqas Nawaz Stoichiometry by Ateeq U Rehman

2. MIXED FLOW REACTOR/CSTR

3. Definition The continuous  flow  stirred-tank  reactor  (CSTR), also known as back-mix reactor. In a perfectly mixed reactor , the output composition is identical to composition of the material inside the  reactor , which is a function of residence time and rate of reaction.

4. MFR/CSTR A continues stirred tank reactor(CSTR) is a vessel to which reactants are added and products removed while the contents within the vessel are vigorously stirred using internal agitation. At steady state, the flow rate in is must be equal to flow rate out.

5. Basic Terms Back Mixing :  The tendency of reacted chemicals to intermingle with unreacted feed in reactors, such as stirred tanks, packed towers, and baffled tanks. Residence Time Distribution : The  residence time distribution  (RTD) of a chemical reactor is a probability distribution function that describes the amount of time a fluid element could spend inside the reactor

6. Mole Balance on CSTR

7. APPLICATIONS CSTRs are most commonly used in industrial processing , primarily in homogeneous liquid-phase flow reactions, where constant agitation is required. Fermentors are CSTRs used in biological processes in many industries, such as brewing, antibiotics and waste treatment. In fermenters, large molecules are broken down into smaller molecules, with alcohol produced as a by-product.

8. Methane Gas tank Fermentation tank

9. ADVANTAGES Cheap to construct. Good temperature control is easily maintained. Reactor has large heat capacity. Interior of reactor is easily accessed.

10. DISADVANTAGE Conversion of reactant to product per volume of reactor is small compared to other flow reactors.

11. Batch Flow & Plug Flow Reactor Presented by Aamir Shahzad

12. REACTORS Definition: A reactor is a system (volume) with boundaries. Mass may enter and leave across boundary. Characteristics: System: Closed or intermittent: no mass enters or leaves during reaction(s) are batch or semi-batch reactors Open (control volume): mass enters/leaves during reaction(s) are continuous flow reactors

13. Batch Reactor Introduction: The  batch reactor  is the generic term for a type of vessel widely used in the process industries. Vessels of this type are used for a variety of process operations such as  solids dissolution ,  product mixing, chemical reactions, batch distillation, crystallization, liquid/liquid extraction and polymerization. In some cases, they are not referred to as reactors but have a name which reflects the role they perform (such as crystallizer, or bioreactor).

14. Construction: A typical batch reactor consists of a tank with an agitator and integral heating/cooling system. These vessels may vary in size from less than 1 litre to more than 15,000 litres. They are usually fabricated in steel, stainless steel, glass-lined steel, glass or exotic alloy.  Liquids and solids are usually charged via connections in the top cover of the reactor. Vapours and gases also discharge through connections in the top. Liquids are usually discharged out of the bottom.

15. Heating and Cooling Systems Products within batch reactors usually liberate or absorb heat during processing. Even the action of stirring stored liquids generates heat. In order to hold the reactor contents at the desired temperature, heat has to be added or removed by a cooling jacket or cooling pipe. Heating/cooling coils or external jackets are used for heating and cooling batch reactors. Heat transfer fluid passes through the jacket or coils to add or remove heat. Within the chemical and  pharmaceutical industries , external cooling jackets are generally preferred as they make the vessel easier to clean.

16. Working Principle: A batch reactor has neither inflow nor outflow of reactants or products while the reaction is being carried out. This is an unsteady state operation where composition changes with time. However, it is assumed that at any instant the composition throughout the reactor is uniform (in composition and temperature etc ), because of efficient stirring.

17. Advantages The advantages of the batch reactor lie with its versatility. A single vessel can carry out a sequence of different operations without the need to break containment. This is particularly useful when processing toxic or highly potent compounds.

18. Applications: Batch reactors are often used: In the process industry. In many laboratory applications, such as small scale production and inducing fermentation for beverage products. In medical production. for experiments of reaction kinetics, volatiles and thermodynamics. Highly used in waste water treatment. Effective in reducing BOD (biological oxygen demand)of influent untreated water.

19. Plug Flow Reactor 20 Fluid passes through the reactor with no mixing of earlier and later entering fluid, and with no overtaking. It is as if the fluid moved in single file through the reactor.

20. In an ideal plug flow reactor, it is assumed that there is no mixing of the medium along the long axis (X-axis) of the reactor although there may be lateral mixing in the medium at any point along the long axis ( ie the Y-axis).

21. Assumptions: Plug flow Steady state Constant density (reasonable for some liquids but a 20% error for polymerizations; valid for gases only if there is no pressure drop, no net change in the number of moles, nor any large temperature change) Single reaction occurring in the bulk of the fluid (homogeneously).

22. Applications: Plug flow reactors are used for some of the following applications: Large-scale production fast reactions Homogeneous or heterogeneous reactions Continuous production High-temperature reactions

23. Advantages and Disadvantages of Plug flow Reactor Advantages: Easily maintained as there are no moving parts. High conversion per unit volume. Unvarying product quality. Good for studying rapid reactions. Disadvantages: Poor temp control. Hot spots may occur when used for exothermic reactions .

24. Order of Reaction Presented by M. Waqas Nawaz

25. Order Of Reaction For a general reaction between A and B where ‘a’ moles of A and ‘b’ moles of B react to form ‘c’ moles of C and ‘d’ moles of D . aA + bB cC + dD We can write rate equation

26. R = [A] a [B] b The exponent ‘a’ and ‘b’ gives the order of reaction with respect to the individual reactant. Thus Overall order of reaction = (a+b)

27. Define : The sum of all the exponent to which the concentration in the rate equation are raised.

28. Facts The order of react is an experimentally determined quantity and can not be determined by simply looking at the reaction equation. The sum of exponents in the rate equation may and may not be same as in chemical equation .

29. The Chemical reaction are classified as Zero First Second Third The order of reaction provides valuable information about mechanism of a reaction.

30. Order of Reaction Decomposition of nitrogen pentaoxide involves the following equation 2N 2 O 5 2N 2 O 4 + O 2 Rate = K [N2O5] First Order reaction

31. Hydrolysis of tertiary butyl bromide (CH 3 ) 3 CBr + H20 (CH 3 ) 3 COH + HBr Rate = k [ (CH 3 ) 3 CBr ] pseudo First order reaction

32. Finding order of reaction Method of Hit and Trail Graphical method Differential method Half life method Method of Large Excess