Currently, in Pakistan, there are six major producers of fertilizers which include Fauji Fertilizer, Engro Fertilizer Company, Dawood Hercules, and Fatima Fertilizers. Media reports suggest that the Chinese government is keenly looking for avenues to enter Pakistan's agriculture and fertilizer sector. The two types of fertilizers - inorganic and organic. In the broadest sense, all types of fertilizers include any substance, living, or inorganic which aids in plant growth and health. We exclude water, CO2, and sunlight.

1. Internship
Report
ENGRO FERTILIZERS LIMITED |
DAHARKI INTERNSHIP 2019

2. Prepared by Younas Chandio
Operations (URUT III) Intern
Dawood UET Karachi (DUET)
Email:
Younas_Chandio@yahoo.com
Contact: 0336-7199973
August 2019
2

3. CONTENTS
1.Aknowledgement
2.Contents
3.Introduction
4.Assignment: Heat duty calculation of E-22
5.Assignment: Poly tropic Efficiency of Compressor K-01
6.Introduction to CO2 compressor K-01
7.Why do we Calculate Poly tropic Efficiency
8.Process flow Diagram
9.Project: process Evaluation of Cooling Tower 4

4. A C K N O W L E D G E M E N T
I am thankful to Allah Almighty, For His boundless blessings
and bounties, And for keeping me sound and successful; My
parents and friends, For all their support and trust in me and
my aims; My teachers and guides, And last and the most
important Management and Employees of Engro Fertilizer
Limited. And all the Sics, SS’, board men and area operators
at Plant II For their utmost help, guidance and time which
made me make most out of my internship at plant site.

5. INTRODUCTION
“ Y O U C A N N O T C R E A T E E X P E R I E N C E ,
Y O U M U S T U N D E R G O I T ”
Industrial internships are incomparable experience for an
undergraduate student. With fertilizer industry holding the
maximum learning potential for a chemical engineer,
Engro leaves an impact of its own. The six week
internship experience is unique in every sense of the
word. The learning opportunities and industrial exposure
at the EFERT made not just possible to relate the book
knowledge to field application but also in developing a
thorough understanding of industrial practices and
operating concepts.

6. Assignment: Heat duty of E-22
Definition: The Heat duty can be
defined as the amount of heat
needed heat needed to transfer
from a hot side to the cold side over
a unit of time.

7. Calculation
Formula to find the Heat duty of E-
22 is :
Q = mCpΔT
Here Q is denote the Heat Duty
symbol & mCpΔT is the Sensible
heat.
Putting all values in above formula
Q = mCpΔT
=(69746)(4.2)(105.9-76.6)
=7001103.48 kJ/hr.
Heat duty of E-22

8. ASSIGNMENT: POLY TROPIC EFFICIENCY OF COMPRESSOR K-01
I N T R O D U C T I O N T O C O 2 C O M P R E S S O R K - 0 1 :
K-01 is a 4-stage centrifugal compressor used for compressing CO2 coming
from the ammonia section before it enters the High Pressure Urea reactor
R-01. K-01 takes in the gas at a very low pressure of 0.58 kg/cm 2 (g) and
discharges it a high pressure of 160 kg/cm 2 (g). The compressor consists
of two casings. The first two stages are incorporated in a horizontally
split casing and the latter two in the vertically split casing. The first two
stages consists of 3 impellers each, and the latter two have 4 and 2
impellers respectively. Inter stage coolers are installed for removing the
heat energy due to compression. The compressor shaft is coupled with the
steam turbine TK-01 which rotates it by producing mechanical work. To
avoid damage to the compressor by surging, it is protected by an anti-surge
valve located at the discharge of the compressor.

9. The calculated efficiency corresponds to the operating parameters of the
compressor K-01 on July 2, 2019 at
10:05 am.
1 S T S T A G E ( 2 M C L ) E F F I C I E N C Y :
The conditions for 1st stage of the Compressor are as follows:
The Formula for efficiency calculation is:
Efficiency=ƞ=(K-1)/K (ln Pd/Ps)/(ln Td/Ts)
Putting all values in above formula we get
ƞ=(1.266-1)/1.266 (ln 7.1/1.53)/(ln 465.75/313.55)=81.34%

10. Efficiencies of K-01 Compressor in Normal Condition
W h y d o w e C a l c u l a t e P o l y t r o p i c E f f i c i e n c y ?
For a multistage centrifugal compressor we usually calculate the
polytropic efficiency because the process is neither irreversible nor
isentropic. Further we also remove the heat of compression by using the
interstage coolers. As the pressure is increased gradually in stages it
favors the calculation of polytropic efficiency as compared to other
efficiencies. For a very very small stage the polytropic efficiency is
almost equal to adiab-atic efficiency.

11. PROCESS FLOW DIAGRAM

12. C O O L I N G T O W E R E F F E C T I V E N E S S & B L O W D O W N
R E D U C T I O N
I N T R O D U C T I O N T O C T - 0 4
CT-04 is a mechanical draft induced-counterflow type of cooling tower
which consists of 14 cells, each of which contains 900 nozzles for water
distribution. It contains 4 submersible pumps one of which is
on standby.
The design specifications of CT-04 are:
Flowrate = 48458 m3/hr
Wet Bulb = 29 C
CWR temperature = 44 C
CWS temperature = 34 C
Range = 10 C
Approach = 5 C

13. E F F E C T I V E N E S S C A L C U L A T I O N

14. Key Performance Parameters:
The key parameters in the performance evaluation of a cooling tower are:
Range: This is the difference between the cooling tower water inlet and outlet temperature.
A high CT Range means that the cooling tower has been able to reduce the water
temperature effectively, and is thus performing well. The formula is:
𝑪𝑻 𝑹𝒂𝒏𝒈𝒆 (°𝑪) = 𝑪𝑾 𝒊𝒏𝒍𝒆𝒕 𝒕𝒆𝒎𝒑 (°𝑪 𝑪𝑾 𝒐𝒖𝒕𝒍𝒆𝒕 𝒕𝒆𝒎𝒑 (°𝑪)
Approach: This is the difference between the cooling tower outlet coldwater temperature
and ambient wet bulb temperature. The lower the approach the better the cooling tower
performance; although, both range and approach should be monitored, ‘Approach’ is a
better indicator of cooling tower performance.
𝑪𝑻 𝑨𝒑𝒑𝒓𝒐𝒂𝒄𝒉 (°𝑪) =𝑪𝑾 𝒐𝒖𝒕𝒍𝒆𝒕 𝒕𝒆𝒎𝒑 (°𝑪 𝑾𝒆𝒕 𝒃𝒖𝒍𝒃 𝒕𝒆𝒎𝒑 (°𝑪)
Effectiveness: This is the ratio between the range and the ideal range (in percentage), i.e.
difference between cooling water inlet temperature and ambient wet bulb temperature, or
in other words it is = Range / (Range + Approach). The higher this ratio, the higher the
cooling tower effectiveness.
𝑪𝑻 𝑬𝒇𝒇𝒆𝒄𝒕𝒊𝒗𝒆𝒏𝒆𝒔𝒔 (%) =(𝑪𝑾 𝒕𝒆𝒎𝒑 – 𝑪𝑾 𝒐𝒖𝒕 𝒕𝒆𝒎𝒑) / (𝑪𝑾 𝒊𝒏 𝒕𝒆𝒎𝒑 – 𝑾𝑩 𝒕𝒆𝒎𝒑) ×𝟏𝟎𝟎
Cooling load: The heat rejected in GCal/hr, given as a product of mass flow rate of water,
specific heat and temperature difference.

15. Evaporation loss: This is the water quantity evaporated for cooling duty. Theoretically
the evaporation quantity works out to 1.8 m3 for every 1,000,000 kCal heat rejected. The
following formula can be used (Perry):
𝑬𝒗𝒂𝒑𝒐𝒓𝒂𝒕𝒊𝒐𝒏 𝒍𝒐𝒔𝒔 (𝒎𝟑/𝒉)= 𝟎.𝟎𝟎𝟎𝟖𝟓 × 𝟏.𝟖 × flowrate × Range
Cycles of concentration (C.O.C): This is the ratio of dissolved solids in
circulating water to the dissolved solids in makeup water. Blow down losses
depend upon cycles of concentration and the evaporation and is given by
formula:
𝑩𝒍𝒐𝒘 𝒅𝒐𝒘𝒏 (𝒎𝟑/𝒉𝒓 ) = (𝑬𝒗𝒂𝒑𝒐𝒓𝒂𝒕𝒊𝒐𝒏 𝑳𝒐𝒔𝒔)/(𝑪.𝑶.𝑪.− 𝟏)
Cooling water Treatment System
All cooling water programs address four issues; the importance of each will vary depending
on the plant. The four, potential water related concerns for cooling water systems are
shown below, along with the major factors that influence them:
i) CORROSION
• Saturation and/or Stability Index and pH
• Oxygen
• Chlorides/Sulphates
• Suspended Solids
• Microbiological Activity

16. ii) SCALING AND DEPOSITION
• High Heat Exchanger Skin Temperatures
• Alkaline Cooling Water pH
• Calcium Level
iii) SUSPENDED SOLIDS
• Makeup Water
• Airborne Solids
• Corrosion Products
• Hardness Precipitates
iv) BIOLOGICAL
• Interference with the Normal Function of the Corrosion Inhibitor(s)
• Growth of Anaerobic Bacteria
• Flow and Heat Transfer Restriction
CORROSION
The corrosion potential of a cooling water system is influenced by several operating
Conditions:
Saturation (Stability) Index and pH
The application of the Saturation Index in determining if a cooling water has scale forming
or corrosion tendencies is determined by the Langelier Index (LSI). This index takes into
account:
pH
calcium level
total alkalinity (M alk.)
total dissolved solids
temperature

17. Suspended solids: The deposition of suspended solids on a metal surface can result in
under deposit type corrosion. This type of corrosion will occur, regardless of the
corrosion inhibitor being used or its concentration, since the treatment is unable to
penetrate the deposit in order to provide a protective film on the metal surface.
Microbiological Activity: The primary corrosion causing organisms are anaerobic bacteria.
They grow beneath deposits and are protected from oxygen present in the cooling water.
Sulphate-reducing bacteria (SRB’s) are very corrosive to metals. Since the corrosion
inhibitor cannot penetrate through the deposit to protect the metal surface, it will not
provide protection against this type of organism.
SCALING & DEPOSITION
Formation of calcium and magnesium scales is the result of several controlling factors:
High heat exchange skin temperatures: High heat exchange surface temperatures
combined with low flow rates through the tubes results in the formation of carbonate in
the cooling water. This thermal decomposition reaction will result in the formation of
calcium carbonate scale. A low water velocity also reduces the “flushing” effect and
increases the tendency for newly formed deposits to adhere to the tube walls and begin
the scale growth process.
Alkaline pH values
As the pH increases above 7 and particularly in the 8 to 9 range, bicarbonate (HCO3) is
converted to carbonate (CO3), which in turn permits to the formation of insoluble calcium
carbonate and/or calcium and magnesium silicate.
Saturation level for calcium sulphate or calcium phosphate
If the cycles of makeup water in the cooling water are allowed to exceed the solubility

18. limit for calcium sulphate (about 1800 ppm), then calcium sulphate deposits will
form. Similarly, calcium phosphate scales can form. Its solubility is controlled by
temperature, pH, calcium level and the ortho-phosphate concentration. If cycles
of concentration are allowed to exceed the calcium phosphate solubility limit,
deposits will form.
SUSPENDED SOLIDS
Suspended solids are objectionable in a cooling water system since they:
Interfere with corrosion inhibitor film formation.
Allow the formation of under-deposit type corrosion cells.
Provide the opportunity for the growth of anaerobic bacteria such as SRBs.
Can restrict or plug condenser tubes and impede heat transfer.
May interfere with the normal operation of valves, orifices, strainer etc..
Suspended solids may originate from any of the following sources:
Makeup Water.
Corrosion products; the insoluble reaction products of corrosion such as iron
and copper
oxide.
Precipitated hardness; calcium carbonate or calcium phosphate found in the
Suspended solids. Also treatment components, such as phosphonates or
polyphosphates can
degrade to give phosphate, which can then in turn react with calcium.

19. By maintaining cooling water on the slightly alkaline side (pH of 8.2 to 8.6), its corrosivity is
substantially reduced while the scaling tendency is increased. Typically, a water with a pH in
the range of 8.2 to 8.8 would have a LSI above 2.0 and commonly around 2.5.
Cooling water can be maintained in this alkaline pH range by:
Allowing makeup water to concentrate
Supplementing with sodium carbonate (soda ash) or sodium hydroxide (caustic soda)
Feeding sulphuric acid to reduce pH of highly alkaline water.
Scale is prevented from forming under alkaline conditions by:
limiting the calcium concentration
controlling the pH (M alk.)
use of scale inhibiting chemicals
If the pH value falls below 4.5, then free mineral acidity (FMA) is present and corrosion will
occur regardless of the corrosion inhibitor being used or its concentration. This condition
occurs when the acid (usually sulphuric acid) being applied to the condenser system, for
alkalinity and pH control, is overfed.
Oxygen
Passing cooling water over a cooling tower saturates it with oxygen. Oxygen is an integral
part of the corrosion process, hence a corrosion inhibitor is required to protect both the
ferrous and non-ferrous metals from corrosion attack.
Chlorides/Sulphates
Concentrating the makeup water in the cooling water increases the total dissolved solids
(conductivity). In particular, as the chloride and sulphate ions present in the raw water are
concentrated, this results in an increase in the corrosivity of the cooling water. Of the two
anions, chloride has the greatest impact on mild steel corrosion rates.

20. Sand, silt, etc. (usually silica and aluminium silicate)
Organic matter (leaves, weed, etc.)
Biomass; both living and dead.
Airborne Solids
Dust
Inorganic and insoluble organic matter
BIOLOGICAL
Biological growth is detrimental to a cooling water program for several reasons.
Interferes with the normal function of the corrosion inhibitor(s) The formation of
bacterial slimes and deposits on the metal surfaces inhibits the development of a
strong corrosion inhibitor film. In addition, the slimes can serve to bind inorganic
debris, which fosters the development local concentration cells. Growth of
anaerobic bacteria Anaerobic bacteria may develop under deposits since they cannot
exist in the presence of oxygen. Sulfate-reducing anaerobic bacteria (SRB’s) are very
destructive to metal. Frequently, it is difficult for biocides to penetrate deposits to
reach these organisms.
Flow and Heat Transfer Restriction
Biological matter will develop and grow on metal or wooden surfaces to an extent
that it can interfere in the normal operation of a cooling water system. These deposits
will restrict flow and/or plug heat exchange equipment piping, orifices, valves,
strainers, etc. Also, the biomass acts as an insulator on the heat exchange surface and
impedes heat transfer rates.

21. A F F E C T O F M I C R O B I O L O G I C A L G R O W T H
The problems caused by bacteria, algae and fungi are different. Each one grows in a
different area of the cooling water system. Micro biological growth can cause the
other major cooling
water problems:
Corrosion
Scaling
Fouling
CHEMICAL TREATMENT WITH BIOCIDES
A good chemical program is critical to controlling microorganisms. Three general
classifications of chemicals are used for the control of microorganisms:
Oxidizing Biocides
Non-Oxidizing Biocides
Bio dispersants
OXIDIZING BIOCIDES
This group of biocides includes:
Chlorine
Bromine
Chlorine dioxide
Ozone
Sodium Hypo chlorite
Chlorine and bromine slow release compounds. These compounds get their name from
the way they (Oxidized) or (Burn up) any microorganisms with which they come into
contact.

22. N O N - O X I D I Z I N G B I O C I D E S
This is a group of organic compounds which are toxic to microorganisms. They are
generally applied at moderate to high dosages and require a minimum amount of
contact time to kill. Most of them kill by interfering with the metabolism of the
microbe or destroying the cell wall.
BIODISPERSANTS
Bio dispersants do not kill microorganisms, but they are very effective at helping both
oxidizing and non-oxidizing biocides to work more effectively. Bio dispersants work in
two ways:First, where there are existing deposits of microorganisms, they break up
the deposit and expose more of the bio mass to the biocide. Second, they make it
more difficult for microorganisms to attach themselves to metal surfaces. Dispersants
prevent microbe buildup. Proper monitoring and control is important for effective
applications of a biocide program. Oxidizing biocides can be directly tested for
available oxidant level in the cooling water. There is no practical method of directly
testing the amount of nonoxidizing biocide.
The effectiveness of a particular biocide dosage can be indirectly measured using two
methods. Cooling water can be measured for micro bio culture counts. If the count is
too high, the biocide dosage is adjusted. Another method is the bio fouling monitor.
This allows measurement of bio film formation on a tube surface.

23. C H E M I C A L S U S E D I N T H E C O O L I N G W A T E R

24. Issues regarding our current System:
Manual arrangement leading to safety concerns
Wastage of Dosing Chemicals
Operations individual overtime
High chlorides in the system leading to high blow down
High chemical consumption cost
R E F E R E N C E S
1)Cooling water treatment manual Buck-man
laboratories Asia
2)An introduction to cooling tower water
treatment J. Paul Guyer, P.E., R.A., Fellow
ASCE, Fellow AEI
3)Dr. Meherwan P. Boyce. (1993). Principles of
Operation and Performance estimation of
Centrifugal Compressors.
4)Jalal Engineering. (2006). Cooling Tower
Basics and Common Misconceptions.
5)Thomas Elliot, Kao Chen, Robert Swanekamp.
(1997). Standard Handbook of Power plant
Engineering (2nd Edition).

25. OCCUPATIONAL HEALTH & SAFETY
Occupational safety and health (OHS) is a multidisciplinary field concerned
with the safety, health and welfare of people at work. These terms also
referred to the goals of this field, so their use in the sense of this article
was originally an abbreviation of occupational safety and health
program/department etc.
The goal of occupational safety and health programs include to foster a
safe and healthy work environment. OHS may also protect co-workers,
family members, employers, customers and many other who might be
affected by the workplace environment.

26. In conclusion we benefited a lot in the field
attachment in a way that we managed to apply our theoretical knowledge from
the university into practice through many activities/observation/experiments
we was instructed to do.
Finally, the internship was both fruitful and
fun for us and we would encourage the other students to apply here for the
internship and to avail the opportunity of doing internship in this company to
clear their concepts and knowledge related to their field by observing things
practically, that were taught to them theoretically in the university.
CONCLUSION