2. Chemical Reactors
• An industrial chemical reactor is
complex device in which heat transfer,
mass transfer, diffusion and friction may
occur along with chemical reaction with
provisions of safety and controls.
• Are vessels designed to contain
chemical reactions.
3. These are the two main basic
vessel types:
•tank
•pipe
4. Basic Principles:
• All chemical processes are centered
in a chemical reactor. The design of a
chemical reactor Is the most
important factor in determining the
overall process economics.
5. At the start the design work , the following
information is presumably available:
. Reaction Type
. Need for catalyst
. Phases involve
. The mode of temperature and
pressure control, and
. Production capacity
6. Reaction Types
• Direct Combination or Synthesis
Reaction
A + B = AB
• Chemical Decomposition or
Analysis Reaction
AB = A + B
7. • Single Displacement or
Substitution Reaction
A + BC = AC + B
• Metathesis or Double
Displacement Reaction
AB + CD = CB
8. In addition to the basic data, include:
• A heat and mass transfer characteristics
• Physical, chemical and thermodynamic
properties of components taking part in the
reaction.
• CORROSION- erosion characteristics of any
potential hazard associated with reaction
system.
• Reaction Rate
15. Material Balances
• Also called mass balance.
• Is an application of conservation of
mass to the analysis of physical
systems.
• The mass that enters a system must,
by conservation of mass, either leave
the system or accumulate within the
system .
16. Mathematically the mass balance
for a system without a chemical
reaction is as follows:
•Input = Output +
Accumulation
18. Applications of Differential
Mass Balance
• Ideal (stirred) Batch reactor
• Ideal tank reactor, also named
Continuous Stirred Tank Reactor
(CSTR)
• Ideal Plug Flow Reactor(PFR)
19. Mass Transfer
• Is the phrase commonly used in
engineering for physical processes
that involve molecular and
convective transport of atoms and
molecules within physical system.
• Transfer of mass from high
concentration to low concentration.
20. Heat Transfer
• Is the transition of thermal energy
from a heated item to a cooler
item.
• Transfer of Thermal Energy
21. Modes Of Heat Transfer
• jacket,
• internal coils,
• external heat exchanger,
• cooling by vapor phase
condensation
• fired heater.
27. Chemical Reactor can be
operated in:
1. Batch Modes
2. Semi Continuous Modes
3. Continuous Modes
28. BATCH REACTOR
•One in which feed material
is treated as a whole for a
fixed period of time.
29. Types of Cooling
Jacket:
Single External Jacket
• Consists of an outer jacket which
surrounds the vessel.
• Heat transfer fluid flows around the jacket
and is injected at high velocity via nozzles.
• The temperature in the jacket is regulated
to control heating or cooling.
31. • The half coil jacket is made by welding a half
pipe around the outside of the vessel to create a
semi circular flow channel.
•A large reactor may use several coils to deliver
the heat transfer fluid.
Half Coil Jacket
33. •Has a series of 20 or more small jacket
elements.
•The temperature control valve operates by
opening and closing these channels as
required.
Constant Flux Cooling Jacket
43. • Residence time – average amount
of time a discrete quantity of
reagents spend inside the tank
• Residence time = volumetric flow rate
volume of the tank
47. • The reaction proceeds at the reaction
rate associated with the final (output)
concentration.
• Economically beneficial to operate in
series or in parallel
48. • Small CSTR operating in
series would be equivalent to a
PFR.
74. Kinds of Catalyst
• Strong Acids
• Base Catalysis
• Metal oxides, Sulfides, and Hydrides
• Metal and Alloys
• Transition-metal Organometallic
Catalysts
76. Base Catalysis
• Is most commonly thought of as an
aqueous substance that can accept
protons.
• Base the chemical opposite of acids.
• Often referred to as an alkali if OH−
ions are involved.
78. Metal and Alloy
• Metal is a chemical elements whose
atoms readily lose electrons to form
positive ions (cations), and form metallic
bonds between other metal atoms and
ionic bonds between nonmetal atoms.
• The principal industrial metallic catalyst,
are found in periodic group VII
89. SPRAY TOWER
• Are a form of pollution control
technology.
• Consist of empty cylindrical vessels
made of steel or plastic and nozzles
that spray liquid into the vessels
90. Two types of Spray Towers:
1.Cocurrent Flow
-are smaller than countercurrent-flow
spray towers
2.Crosscurrent Flow
- the gas and liquid flow in directions
perpendicular to each other.
92. Two-Phase Flow
• occurs in a system containing
gas and liquid with a meniscus
separating the two phases.
93. Two-phase flow may be
classified according to the
phases involved as:
• gas-solid mixture
• gas-liquid mixture
• liquid-solid mixture
• two-immiscible-liquids mixture
Catalysts generally react with one or more reactants to form an intermediate that subsequently give the final reaction product, in the process regenerating the catalyst. The following is a typical reaction scheme, where C represents the catalyst, A and B are reactants, and D is the product of the reaction of A and B: