5. Computer for Engineers
• Uses of Laptop?
• Computer Applications in Chemical Engineering
• Use of Excel & Matlab: Use of these software for problem
solving plotting, fitting data, building new functions and
making interactions and loops. Ordinary differential
equations. Engineering graphics.
• Numerical Methods: Numerical methods involving
computers to solve ordinary differential equations, partial
differential equations, matrices and its application,
Numerical Integration, differentiation, interpolation and
solution of Algebraic & Transcendental Equations, roots of
equations, roots of polynomials, Applications in chemical
engineering.
8. Course Objectives
Discuss with the help of relevant flow diagrams,
equations, operating conditions and equipment
principles, the manufacture of …..
• Knowledge of manufacturing processes of
products as described in syllabus
• Must be able to read/understand
process flow sheet diagrams.
• Must be able to draw process flow sheet
diagram
11. CPI
• Processes / routes for manufacture of a
product
• Raw materials
• Unit operations / Unit processes
• Chemical reactions
• Description of Process
• Process flow sheet diagram/description
12. Syllabus of CPI-1
CHE115 Chemical Process Industries-I
Introduction and Historical development of Chemical Process Industry in Pakistan;
its nature, size, number of units, location, investment and number of employees;
Basic Industries:
Silicate and allied products,
Glass, Ceramics and Cement;
Phosphorus,
Soap and Detergents,
Sugar,
Paints and Varnishes;
Heavy Chemicals:
Sulfuric Acid,
Nitric Acid,
Sodium carbonate and sodium hydroxide soda-chlor industry;
Water conditioning: Water purification for steam raising and for other industrial
purposes
13. CHE 224 Chemical Process Industries II
• Fertilizer Industries: Urea manufacture, Ammonium
Nitrate manufacture, Di-ammonium phosphate
manufacture, Super phosphate manufacture.
• Pulp & Paper Industries: Chemical pulping methods,
Paper making machine, Environmental concerns of pulp &
paper industries.
• Leather Industries: Vegetable & chemical tanning
processes, Environmental concerns of leather industries.
• Polymer Industries: Manufacturing of at least two different
types of polymeric products & their utilization, Plastic
Industries, History, Types of plastic resins & their
manufacture, Synthetic fiber manufacture.
• Biotechnological Industries : Sugar Industry, Fermentation
and production of Industrial alcohol, Biomass processing.
14. Resources/Books
• Austin George T. (1997), “Shreve’s Chemical Process Industries” 6th Ed. McGraw-Hill
International Edition.
• Alan Heaton (1994), “The Chemical Industry” 2nd Ed. Published by Blackie Academic
& Professional
• Haidari Iqbal (1992), Chemical Industry in Pakistan”, Industrial Research Service
Karachi.
• Pandey G. N. (2000), “A Textbook of Chemical Technology” 2nd Ed. Vol-I & II Vikas
Publishing House (Pvt) Limited.
• Kirk Othmer (1999), Encyclopedia of Chemical Technology” Wiley Inter Science
Publishers.
• Government of Pakistan. (2003), “Prospects of Chemical Industry in Pakistan” Expert
Advisory Cell, Ministry of Industries and Production, Islamabad.
• Moulijn Jacob A, Makkee Michiel, Diepen Annelies Van, (2007), “Chemical Process
Technology:” John Wiley & Sons, Ltd.
• James A. Kent (2003), “Riegels Handbook of Industrial Chemistry”, 10th Ed.
Springer/Van Nostrard Reinhold
URL: http://www.cheresources.com
Description: Cheresources.com has been providing content and tools to chemical
engineers all over the world. The site has many free chemical engineering resources as
well as premium content and software for visitors to choose from Some of the free
articles are targeted for students.
wiser
15. How various chemicals are produced on
industrial scale?
• Sequence of Operations.
• What are Unit Operations and Unit Processes?
• How to describe the method of production?
• How to read the Production process.
• Pipelines, Vessels, reactors, crushers, grinders,
Heaters, Coolers, Compressors, Pumps etc.
20. Pipelines, Vessels, reactors, crushers, grinders, Heaters,
Coolers, Compressors, Pumps.
• What is a Block Diagram?
• Showing the sequence of operations for a
product
• What is a process flow sheet diagram?
21. Types of Flow sheets
• Block Diagram
• Process Flow-sheet or Flow Diagram
• Piping Flow-sheet or Mechanical Flow Diagram
• Combined Process and Piping Flow-sheet or
Diagram
• P&I (piping/process and instrumentation)
diagrams
• Utility Flow-sheets or Diagrams
• Simulations (windows assisted)
25. Description of process by Drawing
• Units
• (Storage Tanks, Heat Exchangers, pumps,
compressors, evaporators, filters, Drying
equipment, Crushers, Grinders etc.)
• How to show the units by drawing? By the
help of symbols.
34. How Process flow diagrams are drawn
with the help of Computer?
• With The help of drawing soft-wares?
• What are the technical soft-wares, and how to
use them for drawing a process flow diagram
36. Standard Symbols
• For a Process Flow Diagram, each unit operation
or unit process is carried in a specific type of the
equipment.
• For Example: Heating can be done in
Plate type heat exchangers,
Shell and tube type heat exchangers,
Evaporators etc.
Therefore it is necessary to set a symbols for each
type of equipment.
37. Symbols for Flow sheets
• To reduce detailed written descriptions on flowsheets, it is usual practice to
develop or adopt a set of symbols and codes which suit the purpose.
Flowsheet symbol standardization has been developed by various professional
and technical organizations for their particular fields. The American National
Standard Institute (ANSI) has also adopted most of these symbols. The
following symbol references are related and useful for many chemical and
mechanical processes:
1. American National Standard Institute (ANSI) (www.ansi.org)
2. American Institute of Chemical Engineers (AIChE) (www.aiche.org)
(a) Letter Symbols for Chemical Engineering, ANSI Y10.12
3. American Society of Mechanical Engineers (ASME) (www.asme.org)
4- British Standards
5- Title: Process Flow Diagrams
URL: http://commons.wikimedia.org/wiki/Category:Process_flow_diagrams
Description: This website exclusively deals with process flow diagrams, other
technical diagrams and photographs of industrial equipment and plants.
38. Sources for Standard Symbols
• Coulson & Richardson’s “Chemical
Engineering” Vol-6 (Appendix-A)
• Perry’s Handbook of Chemical Engineers
64. Fertilizers
Any substance either organic or inorganic of
natural or synthetic origin, which is applied to
a soil to supply certain essential elements for
the plant growth and nutrition.
66. Fertilizers
• Urea (AMMONIA)
• Ammonium Nitrate
• Super phosphate
• **************************
• Fertility of Soil yield of crops per unit AREA
67. Classification
Based on manufacturing method
Natural Fertilizers
Synthetic Fertilizers
Based on Chemical Source
Organic Fertilizers
Inorganic Fertilizers
Based on Nutrients content
Nitrogenous , Phosphoric, Potash
68. Classification of Fertilizers
• Direct Fertilizers
That make part of the food of the plants
• Indirect Fertilizers
• That improve the conditions/environment for
better growth. involving salinity water logging
removal.
79. Essential Plant Nutrients
16 essential elements
– C, H, O – air and water, photosynthesis
– N, P, K, -- major elements
– Ca, Mg – lime elements
– Fe, Mn, B, Mo, Zn, Cu, Cl, Na – micro or minor
elements
80. Plants growth is affected by the food intake by
the plants called as Nutrients.
Plant Nutrients may be classified in to
Macro nutrients
Micro Nutrients
96. Process
• Natural Gas
• Knock Out
• Hydro treatment unit
• Desulphuriser
• Reformer (Primary , Secondary)
• Shift Conversion / CO2 separation
• Methanator
• Ammonia Convertor
97. H2S + ZnO → ZnS + H2O
* Catalytic steam reforming of the sulfur-free feedstock is then used to form hydrogen
plus carbon monoxide:
CH4 + H2O → CO + 3H2
* The next step then uses catalytic shift conversion to convert the carbon monoxide to
carbon dioxide and more hydrogen:
CO + H2O → CO2 + H2
* The carbon dioxide is then removed either by absorption in aqueous ethanolamine
solutions or by adsorption in pressure swing adsorbers (PSA) using proprietary solid
adsorption media.
* The final step in producing the hydrogen is to use catalytic methanation to remove any
small residual amounts of carbon monoxide or carbon dioxide from the hydrogen:
CO + 3H2 → CH4 + H2O
CO2 + 4H2 → CH4 +2H2O
121. REMOVAL OF SULPHUR:
10ppm of organic Sulphur is present in the feed
gas coming from the battery limit, this Sulphur
must be removed before sending it to the
reforming section to avoid the poisoning of
catalyst in the reformer. To achieve this it is
first converted to Hydrogen sulphide by adding
to it a hydrogen rich stream from another part
of the process in a reactor known as
hydrogenator in a ratio of 1:14 in the presence
of CoMo (cobalt molybdenium) catalyst and
the temperature required is around 399oC at a
pressure of 40Kg/Cm2.
122. STEAM REFORMING
• Primary Reforming:
• Partial reforming of the hydrocarbons present in the purified gas is
carried out in this section by the use of heat and steam. Primary
reformer has two sections.
• · Convection Section
• · Radiant Section
• In the convection section the desulfurized gases are mixed with steam
and after preheating in the mixed feed coil in the convection section of
the primary reformer the mixture is then distributed to the catalyst
tubes suspended in the radiant section of the primary reformer. The
vertical tubes are packed with a metallic Nickel catalyst and the
reforming reaction temperature is 820oC. medium pressure steam is
provided here at 350oC and at a pressure of 40Kg/Cm3.
123. Secondary Reformer:
• The secondary reformer is a refractory lined vessel
packed with a metallic nickel catalyst.
• Compressed air and the steam which has been pre
heated in the convection section of primary reformer are
introduced into the process gas and the mixture is burnt
here. This rises the temperature sufficiently high for
further reforming to take place. Also air provides sufficient
nitrogen for the conversion reaction of ammonia to take
place at later stages of the process.
• Secondary reforming taking place here will reduce the
methane contents to 0.3-0.4%. the reaction over nickel
bed is strongly heat absorbing and the temperature of
gases leaving is only around 1000oC.
124. High Temperature Shift Converter:
• Here in the first reactor, the carbon
monoxide content is reduced to 3.1 % over
a catalyst of Reduced Iron at 370˚C. The
reaction is exothermic and outlet
temperature of gas is about 430˚C.
125. Low Temperature Shift
Converter:
Gas enters the low temperature shift
reactor at 242˚C and leaves at 255˚C.
This converter uses Copper catalyst.
Since the catalyst is very sensitive
towards sulfur compounds, so it is
protected by a guard bed of Zinc Oxide
in the reactor top section. The carbon
monoxide content is reduced here to
about 0.5%.
126. CO2 Removal:
• There are many processes for the carbon
dioxide removal and the one chosen here is the
CATACARB system.
• Most of CO2 is removed by its absorption in
potassium carbonate solution in an absorber.
• Here the carbon dioxide content, which has now
risen to 17.5 %, is reduced to 0.1 %.
• The gas is first cooled down, saturated with
water and carbon dioxide removal is carried out
in two absorption stages, by counter current
contacting the gas with catacarb solution in a
packed bed absorber. The catacarb solution
flows downwards by gravity while the gas flow
upwards through the tower.
127. Contd.
• The catacarb solution consists of an aqueous
solution containing the equivalent of 25%
potassium carbonate which combines
chemically with carbon dioxide.
• The “rich” catacarb solution, from the bottom
of the absorber is regenerated by, flashing
under low pressure into stripping tower and by
heating. The carbon dioxide is driven off and
the regenerated catacarb solution from the
bottom of stripping tower is returned to the top
of absorber for re-use.
128. Methanator:
• The catalyst used for ammonia conversion is
very sensitive to the oxides of carbon but the
raw synthesis gas still contains a small
percentage (0.6%) of carbon monoxide which
was not oxidized in the shift reaction, and a
small percentage (0.1%) of carbon dioxide
which was not removed by catacarb solution.
These gases are now removed by reaction
with hydrogen to form methane and steam
over a Nickel catalyst.
129. Gas Compression
• For conversion to ammonia the pressure is
required to be high. So in order to bring the
synthesis gas up to reaction pressure it is
necessary to compress it up to 147 kg/cm2. this
is carried out in two case barrel type
compressors.
• In the first case, the raw synthesis gas is
compressed from 26 kg/cm2 up to 70.4 kg/cm2.
it is then cooled to 8˚C and enters the second
casing where it is compressed to 154 kg/cm2.
130. Ammonia Converter
• This is highly exothermic reaction which
takes place over a Reduced Iron catalyst
which has been modified by Aluminum,
Potassium and Magnesium Oxides.
132. UREA
• Urea also referred to as carbamide, is a white,
crystalline, organic, water-soluble fertilizer. It
contains around 46 % nitrogen, the highest N
percentage any solid fertilizer can have.
• Apart from its major use as a fertilizer, urea is
also employed in the manufacture of paints,
glues, plastics, paper, textiles, feed and weed
control chemicals as well as a source of non-
protein nitrogen.
133. • Urea, although an excellent fertilizer, have following
drawbacks:
• (i) When applied to a bare soil surface, urea hydrolyzes
rapidly and loses a significant quantity of ammonia by
volatilization. Such losses vary from soil to soil and are
greater for urea in a pellet form rather than in a solution
form. Burning residues on the field is suggested as a
practical means to control the ammonia loss because the
burning reduces the concentration of the enzyme urease in
plants.
• (ii) Rapid hydrolysis of urea in soils can cause injury to the
seedlings by ammonia, if large quantities of the fertilizer
are placed too close to the seeds.
• (iii) The fertilizer grade urea may contain toxic biuret which
is formed during urea manufacture by an excessive temperature rise.
134. • A large concentration of biuret in urea ( > 2 %)
causes injury Feed-grade urea is sometimes
referred to by the number 262 which is the
product of its nitrogen content (42%) multiplied
by 6.25, the latter being the factor used by
chemists to convert nitrogen to its protein
equivalent.
• Urea is sometimes phytotoxic when placed close
to seeds or seedlings. The phytotoxicity is caused
by high local concentrations of ammonia during
the hydrolysis stage or by accumulation of nitrite
during the nitrification
• step. Another possible cause is the presence of
biuret impurity in urea. to plants
135. Urea Reactors
• Chemistry of the Reaction
• Formation of Ammonium Carbamate
(Fast)
• Carbamate conversion to urea.
136. Urea Reaction
• NH3+CO2 NH4COONH2……….1
• NH4COONH2 NH2CONH2+H2O…2
• First reaction is instantaneous, and practically
complete, with evolving considerable amount of
heat. The major part of this heat is utilized in
raising the temperature of the reactants up to 375
–380F and the remaining smaller part of heat is
used to supply the heat of formation of Urea.
137. • High Pressure promotes production of
Urea because high pressure forces
gaseous Ammonia and CO2 to form
Carbamate. High Temperature, However
adversely affects the first reaction,
because it causes decomposition of
Carbamate back to Ammonia and CO2.
138. • A small excess of Ammonia in the reactor
promotes the first reaction, whereas the large
excess reduces the formation of CO2 into
Carbamate.
• The second reaction of Urea formation is
relatively slower, incomplete and requires
heat. It takes about 25-30 minutes to convert
75% of total Carbamate (Fresh feed+recycle)
into Urea.
• High Excess ammonia promotes the
conversion of Carbamate into Urea and vice
versa.
139. • During conventional Urea manufacturing
method, all stoichiometric CO2 required is
fed to reactor at high pressure.
• There may be different method to deliver
CO2 needed to produce Urea (i.e. 60-65% of
required CO2 directly to the reactor at high
pressure, The remaining 35-40 % of CO2 at
medium pressure ) thus absorbing excess
heat of Carbamate formation reaction.
142. • Urea solution from decomposition section is
then pumped to the prilling tower.
• Urea solution is concentrated by a multiple
effect heat exchanger (evaporators) up to
98.5%
• Concentrated Urea solution solidifies in form
of prills, when it is showered from top of
prilling tower in form of drops, and air is
blown counter current.
143. Factors affecting formation of Urea
1- Temperature (180-210 C)
2- Pressure (140-250 atm)
3- Mole ratio of (NH3/CO2 3to4:1)
4- Retention Time (25 -30 Minutes)
151. • Based on the recycle principle, the total-recycle processes
are classified into five types:
• (a) hot-gas mixture recycle,
• (b) separated-gas recycle,
• (c) slurry recycle,
• (d) carbamate solution recycle, and
• (e) stripping.
• All the first four types use carbamate decomposition
similar to the once-through or partial recycle processes.
The stripping process is, however, completely different
and will be treated separately.
152. CO2
165 kg/cm2
AMMONIA
EJECTER
CARBAMATE
Recovered
REACTER -1
T=170 -80 C , P=150 kg/cm2
STRIPPER
T=206 C , P=145 kg/cm2
M P Decomposer
T=150 C, P=16 kg/cm2
LP Decomposer
T=140 C, P=3.5 kg/cm2
1st Stage EVAPORATOR
T=124 C , P=0.3 Ata
2nd Stage EVAPORATOR
T=140 C , P=0.03 Ata
PRILLIUNG
BAGGAGE/
/STORAGE
32% urea
46% urea
63% urea
70% urea
95.6% urea
99.7% urea
UREA PLANT
