electrical_group_1(awais, haseeb, ather)
TRANSCRIPT
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INTERNSHIP REPORT
IBRAHIM FIBRES LIMTED
BATCH-1(2015)
ELECTRICAL ENGINEERING STUDENTS
GROUP MEMBERS:
AWAIS ALI UET, LHR.
ABDUL HASEEB SHAHBAZ LUMS
MUHAMMAD ATHER TAYYAB GIKI
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Abstract
Industry is the best tool to learn and practice the knowledge learned. It attracts the best
and most talented minds, providing thousands of jobs and playing a pivotal role in the economy
of the country. Through the output of the industries, the welfare of country and its people is
estimated. With the advancements in technologies, the equipment used in the industries is
becoming more modern. And with the aim to keep the industry running and fulfilling the
consumer demands, owners of industries are always updating their equipment.
Considering this, we joined Ibrahim Fibers Limited – Polyester Plant to gain the
knowledge of Electrical and Instrumentation equipment along with power generation used in it.
At the end of my internship, we can confidently say that we have learnt a lot about motors,
generators, DCS and PLCs along with the office environment in this highly advanced and
competitive industry.
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ACKNOWLEDGEMENTS
“All and every kind of praise to be for Almighty ALLAH, who guides us from darkness to light
and help us in difficulties”.
First of all we would like to thank Almighty Allah, who give us brain to think, eyes to see
ears to hear and many other blessings with whose blessings, we were able to present this report
in final shape.
There are several people who enrich and enhance one’s personal, professional as well as
educational life, my parents; teacher and friends are among those people. We thank our parents
whose prayers and encouragement were a great source of strength for me. We are deeply
indebted to all my teachers during this internship especially who encouraged, motivated and
guided me throughout my stay at IFL - Polyester Plant.
We are especially thankful to Mr. Waleed from T&D department who allowed me to
work in both Electrical and Instrumentation departments.
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Aim
The aim of this internship was to learn about the Electrical and Instrumentation part of
the Industry by applying the knowledge learned during graduation. Through this Internship, we
familiarized ourselves and understood the modern practices and trends regarding Electrical,
Instrumentation and Power generation and distribution applied in industries and standard
procedures followed.
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Table of Contents
Chapter 1 Safety 5
Chapter 2 Utility 9
Chapter 3 Polymer 16
Chapter 4 S/F 20
Chapter 5 Electrical 21
Chapter 6 Instrumentation 28
Chapter 7 DCS 34
Chapter 8 PG-1 37
Appendix A Metering 52
Appendix B NGR 54
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Chapter 1
Safety
1.1 Introduction
Safety is the state of being "safe" the condition of being protected against physical,
social, spiritual, financial, political, emotional, occupational, psychological, educational or other
types or consequences of failure, damage, error, accidents, harm or any other event which could
be considered non-desirable. This can take the form of being protected from the event or from
exposure to something that causes health or economic losses. It can include protection of people
or of possessions.
1.2 Types of Safety
It is important to distinguish between products that meet standards, that are safe, and
those that merely feel safe. The highway safety community uses these terms:
Normative safety is a term used to describe products or designs that meet applicable
design standards.
Substantive safety or objective safety means that the real-world safety history is
favorable, whether or not standards are met.
Perceived safety or subjective safety refers to the level of comfort of users. For example,
traffic signals are perceived as safe, yet under some circumstances, they can increase
traffic crashes at an intersection. Traffic roundabouts have a generally favorable safety
record, yet often make drivers nervous.
1.3 Different Safety Permits
There is different type of safety permits issued while carrying out a certain job in IFL. They are
mentioned below along with brief description:
Cold Permit is given to carry out normal routine tasks which involve no danger.
Hot Permit is issued if to carry out task which involve some sort of risks.
Excavation Permit is issued when there is a job carried out which includes digging.
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1.4 Safety Measures
Safety measures are activities and precautions taken to improve safety, i.e. reduce risk related
to human health. Common safety measures include:
o Root cause analysis to identify causes of a system failure and correct deficiencies.
o Visual examination for dangerous situations such as emergency exits blocked because
they are being used as storage areas.
o Visual examination for flaws such as cracks, peeling, loose connections.
o Chemical analysis
o X-ray analysis to see inside a sealed object such as a weld, a cement wall or an airplane
outer skin.
o Destructive testing of samples
o Stress testing subjects a person or product to stresses in excess of those the person or
product is designed to handle, to determining the "breaking point".
o Safety margins/Safety factors. For instance, a product rated to never be required to handle
more than 200 pounds might be designed to fail under at least 400 pounds, a safety factor
of two. Higher numbers are used in more sensitive applications such as medical or transit
safety.
o Implementation of standard protocols and procedures so that activities are conducted in a
known way.
o Training of employees, vendors, product users
o Instruction manuals explaining how to use a product or perform an activity
o Instructional videos demonstrating proper use of products
o Examination of activities by specialists to minimize physical stress or increase
productivity
o Government regulation so suppliers know what standards their product is expected to
meet.
o Industry regulation so suppliers know what level of quality is expected. Industry
regulation is often imposed to avoid potential government regulation.
o Self-imposed regulation of various types.
o Statements of Ethics by industry organizations or an individual company so its employees
know what is expected of them.
o Drug testing of employees, etc.
o Physical examinations to determine whether a person has a physical condition that would
create a problem.
o Periodic evaluations of employees, departments, etc.
o Geological surveys to determine whether land or water sources are polluted, how firm the
ground is at a potential building site, etc.
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1.5 Different Safety Signs
Safety signs are used for indication of the hazard involved while carrying out the certain
action. They are very helpful in for the subject as they give clear guideline about the hazard that
one could face at the site where they are erected. Some different safety signs are:
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Chapter 2
Utility Department
The power requirements along with maintenance of different machinery parts in IFL-PP
are carried out by UTY/PG-2 department.
During the visit of UTY/PG-2, we were given familiarization with the Ring Main
System, Power Distribution, Star Delta Drawing & Utilities Process. A brief overview is given
below. The tour of UTY/PG-2 was given by Mr. Fehmeed.
2.1 Gas Turbine
2.1.1 Overview:
A gas turbine, also called a combustion turbine, is a rotary engine that extracts
energy from a flow of combustion gas. It has an upstream compressor coupled to a
downstream turbine, and a combustion chamber in-between. (Gas turbine may also refer
to just the turbine element.)Energy is added to the gas stream in the combustor, where air
is mixed with fuel and ignited. Combustion increases the temperature, velocity and
volume of the gas flow. This is directed through a nozzle over the turbine's blades,
spinning the turbine and powering the compressor. Energy is extracted in the form of
shaft power, compressed air and thrust, in any combination, and used to power aircraft,
trains, ships, generators, and even tanks.
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Fig. 2.1 A gas turbine
2.1.2 Purpose in IFL-PP
The power plant of Polyester Plant, Ibrahim Fibers Limited is capable of
producing up to 73MW. This total capacity comes from two power plants operating there,
Gas Turbine Power Plant 15MW and HFO (heavy furnace oil) Power Plant 58.3 MW.
In PG-2 the Gas Turbine runs synchronous generator to produce electricity. The
wires containing power are than fed to the panels situated along with the feeder lines
coming from the HFO plant.
The GT is used as a source of creating power with output capacity mentioned
above. The Gas Turbine runs on gas which is used as a fuel along with air. The diesel is
also used as an alternative. It runs at 11200rpm. The temperature inside combustion
temperature of GT is 790C. Turbine has two bearings and the exhaust of turbine has
temperature of about 530C.
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2.2 Gas Turbine
Inside PG-2, there are many panels each assigned for different purpose. In/Out Plant
Breaker takes wires from the feeder line with a VCB breaker built in it for protection. Bus Riser
Panel is used to match the two different buses. Bus coupler Panel couples different panels to
each other. Dummy Panel is also used for coupling and act as a tie point for connecting panels
that can be installed in future. The wires through some panel go to Transformer Room where the
voltage is stepped down from 11KV to 440V. From there the wires are fed to other panels for
further use. MLDB panel is used for controlling lights in plant. 1AGT1 panel is a process panel
used for controlling and processing GT parameters. There is another panel 1CAC & Fire Control
which is a control panel used to process these parameters and it has built in connectors along
with fire extinguishing system to carry out the commands issued through 1AGT1 panel. Steam
Boiler panel is used for controlling boiler process, commands are issued through it and then
process is carried out through another panel which has built in connectors and pumps. Gas
Compressor 01 and Gas Compressor 02 are used for controlling operations related to gas
compressor.
Load Shedding Panel performs load shifting on the basis of assigning critical loads and
less critical loads. Further it senses the fault on the basis of frequency, as soon as the frequency
deviates from 50Hz it trips and shifts the load accordingly. Rectifier Panel is used as a backup, as
it contains UPS to be used in the case of emergency. Starting Panel GT1 controls two DC motors
to give initial torque to GT. Soft Starter panels are used to tackle the high current and torque
requirement as they increase the rpm of the motors gradually. NGR (neutral to ground resistance)
panel consists of resistances connected in zigzag form to provide 63.5 ohm of resistance for
connecting neutral to ground. Lightning Resistor Panel is used in case the plant is hit by
lightning. It acts in such a way that resistance decreases with increase in voltage. So, if lightning
strikes, it acts as short circuit and all the current is passes through it, adding to the safety of the
plant.
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2.3 Utilities
The utilities section provides maintenance along with various water treatment and
auxiliary things for processes used all over IFL-PP.
Water Treatment Plant
There are six raw water turbines which fetch water for processing in water
treatment plant. There are 6 other water turbines on standby. There are different qualities
of water being produced at this plant. The details are as follows.
Chemical Dozing Unit
Chemical used in different processes in water plant are transferred from tankers
through pumps in the desired areas.
Blower
They regularly filter air so that dust particles are removed from it.
Soft Water
Fresh raw water is pumped from ground and is transported to the water plant. In
plant they are further pumped to gravel bed in a closed vessel. Small portions of Hydro-
chloric acid (HCl) are added to the filtered water kill bacteria and to lower pH value.
Then it passes through bag filter which consists of series of fibers to deposit gravel on
them. The water that passes the laboratory test is termed as Soft water, and this is the
major production of plant. The soft water produced is then decarbonized.
Decarburization is a process in which air is pumped into water to remove carbon content.
Daemon Water
The soft water is passed through the bed of mixed cation and anion bed and it
becomes demineralized. Daemon water is then stored in another vessel (4010-V05).
Daemon water is used in chilled water circuit, boiler house etc.
Drinking Water
Soft water from the storage vessel and some small amount of raw water is passed
through the bed of calcium hydrolith. Drinking water produced is then stored in drinking
vessel.
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2.4 Boiler
Boiler house have 3 boilers. All boilers are of fire tube types having three passes and a
super heater. Water is accumulated in the shell and it surrounds the tubes. Fire is passed through
first pass where combustion take place, from there it enters the second pass from behind, leave
the second pass from front and the fire rises to the super heater then it enters the third pass,
exhaust gases leave the boiler at boiler rear face to the exhaust chimney erected outside the boiler
house.
Definition
A boiler is a closed vessel in which water or other fluid is heated. The heated or
vaporized fluid exits the boiler for use in various processes or heating applications.
Fig. 1.2 : A boiler
Applications
Boilers have many applications. They can be used in stationary applications to provide
heat, hot water, or steam for domestic use or in generators and they can be used in mobile
applications to provide steam for locomotion in applications such as trains, ships, and boats.
Using a boiler is a way to transfer stored energy from the fuel source to the water in the boiler,
and then finally to the point of end use.
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Purpose in IFL
The exhaust of the Gas Turbine has a temperature of around 550C; this is used to boil the
water for industrial purpose. Water is pumped into economizer section, from there on it is
brought in boiler section and then finally into super heater where the temperature of the water
reaches up to 230C and it is maintained at 25bar of pressure. This water, which is now converted
into steam is then used as per requirement.
2.5 Nitrogen Generation
Nitrogen being inert serves as a very useful gas than air. Nitrogen is used in transporting
PTA which is in white powder form and highly combustible. Nitrogen is also used in cleaning
PTA residue from pipes.
2.6 Chillers
At Ibrahim fibers there are four vapor compression chillers. Chilled air is supplied to
AHU (air handling units). In case of central air conditioning chilled water from absorption
chillers is taken to AHU.
Cooling Tower
The chilled water is reused and is dropped from height which results in decrease in
temperature of around 7C to 8C.
Compressed Air
Air from atmosphere is taken and compressed to 25bar. At Ibrahim fibers 5 air
compressors.
Instrument Air
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Compressed air without humidity along with oil is used for creating instrument air. Its
purpose is to prevent corrosion in the instruments.
Heat Transfer Medium
It is oil which is run between pipes and insulation to keep the PTA in molten form. If
PTA cools down and turns into solid, it will result in damaging the pipes. The temperature of
HTM is around 300C. There are three furnaces for HTM in Polymer 1 and three furnaces for
HTM in Polymer 2.
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Chapter 3
Polymer Department
3.1 Introduction
Polymer creation is the very first and the most important part in the creation of polyester.
IFL-PP is for the continuous production of polyethylene terephthalate (PET).
The tour of Polymer 1 & 3 was given by Mr. Fuad Arshad & Mr. Zubair. During this, we
were introduced to Polymer Process in IFL-PP. The brief overview is given below.
3.2 Piping and instrument Diagram
Every engineer who enters the IFL polyester plant is given a P&I Diagram to make him
familiar with the architecture of the system. A piping and instrument diagram is a kind of map of
the whole industry in the form of legends. These legends are the symbols of various devices like
pumps, motors and sensors.
3.3 Terephthalic Acid
Overview
Terephthalic acid is the organic compound with formula C6H4(CO2H)2. This colorless
solid is a commodity chemical, used principally as a precursor to the polyester PET, used to
make clothing and plastic bottles. Several billion kilograms are produced annually.
Purpose in IFL-PP
It is used as a starting product for the production of polyester. Stored in silos, it is fed to
polymer process plant along with ethylene glycol for creating the product.
3.4 Ethylene Glycol
Overview
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a
precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet tasting liquid.
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Purpose in IFL-PP
It is used in the production of polyester. Stored in silos, it is fed to polymer process plant
along with ethylene glycol for creating the product.
3.5 Grinding Of PTA
PTA is grinded using Pearl Mill and further Centrifuge is used for removing any
impurities from the PTA.
3.5.1 PTA Silos
There are three silos outside Polymer plant, where PTA is stored. There are two lines
coming out Polymer 1 and 5 lines out of Polymer 2 with only 3 used and 2 for standby purpose.
3.6 Polymer Process
The whole reaction for the completion of polyester is completed in five stages. Coming to
the process, in the first stage, PTA is brought into Polymer process plant and is weighted using
PTA measuring system called Schenk system. Secondly, there is a paste preparation vessel also
called Paste Tank, where paste is prepared. The reaction contents are:
PTA + MEG + Antimony Triacetate
Initially, PTA is in powder form, MEG in liquid form. There are three lines going out of
this tank. One contains water vapors, other is ethylene glycol recovery line and last one product
line. Also, the agitation motor performs the mixing.
Second stage of the process is called Esterification-I. Here, slurry is heated at high temperature,
91% of the reaction is completed and the product is in the monomer form.
Esterification-II is the next stage where 95% of the reaction is completed. TDO (dulling agent)
is mixed with the polymer paste. Dual winding motor is used here.
Pre Poly Condensation I– is the third stage of polymer process. The reaction completed in this
stage is from 96% to 98%. No motor is used in this stage, only heating is done.
Fourth stage is called Pre Poly Condensation – II. Here, Jet system is used to maintain vacuum.
The motor is used for agitation purpose and reaction completed is 97%.
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The final stage is called Disc Ring Reactor or DDR. Here 100% of the reaction is completed.
The product is now polymer, and it is fed to spinning for further use.
Star valve is used to take final polymer product to spinning and chip cutter.
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Fig. 3.1: Polymer Process Flow chart
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Chapter 4
Spinning & Draw Line
4.1 Introduction
The tour of S/F-3 was given by Mr. Naeem and Mr. Usman. During the visit of this
department, we were familiarized with Power Distribution, Draw Line Process Orientation, UPS
System & Distribution and Battery Maintenance. A brief overview is given below.
4.2 Spinning
The polymer is coming from the star valves enters the spinning section. There is a heat
exchanger present in the start where HTM is coming from one side, and polymer is coming from
the other side. Temperature sensors (RTD) are present before and after the heat exchanger, which
measure the previous and settled temperature. The polymer is now divided into 32 lines, for
further processing. In the start of each line, a pump is there which fetches the polymer from heat
exchanger. Quench air and SF oil are mixed to the polymer. SF oil is used to remove the static
charges from the polymer for making TOW. The polymer is now passed through the spinneret
plate. Here, very small holes are there, typically 7500 or 5250 in a plate, which make fine threads
of TOW. The TOW is then collected and after passing through a number of rollers, sent to the
TOW cans.
4.3 Draw Line Process
The polyester coming from Spinning is in a rubber like form. We can expand it to
increase the material. For this, polyester is first passes through TOW, and then it is passed
through SF Oil tray which is for shinning and strengthening purpose. Then it is passed through
steam chamber because if tried to expand without, it will break. After passing through TOW
again it is passed over Stream drums for further expansion, and then it is cooled down and passed
through Crimper which converts it in the form like cotton. Dryer removes any water content
present in polyester. The next step is cutting of the polyester into small pieces which is
accomplished using Cutter and then Bailer makes bales. These bales are then sent to the store
houses for storing and transportation.
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Chapter 5
Electrical Department
5.1 Introduction
Electrical maintenance and power distribution department is the most important and
critical part of IFL. We will first discuss power distribution network through LVDs (Low
Voltage Distribution). Afterwards, Electrical maintenance techniques will be taken into account.
5.2 Distribution Network in IFL
IFL employs power distribution in ring main network system for greater reliability. The
transmission system from PG-1 to the LVDs is in XLPE underground cables.
5.3 Ring main
In electricity supply, a ring final circuit or ring circuit (informally also ring main or just
ring) is an electrical wiring technique developed that provides two independent conductors for
live, neutral and protective earth within a building for each connected load or socket.
A ring main wiring circuit is the alternative to a radial wiring circuit. In a radial wiring
circuit, the wiring starts at the circuit breaker and connects to each device on the circuit (fans,
outlets, lamps, etc) in turn. When it reaches the last device, the wiring simply ends. Ring main
wiring goes one step further: instead of ending the wiring at the last device, it pulls more wiring
back from the last device to the circuit breaker, completing a loop. Ring main wiring is required
in some places, and illegal in others. Modern homes in the United Kingdom tend to have a ring
main setup.
The main advantage to a ring main system is smaller wiring. Since each device on the
ring has two hot wires connecting it to the circuit breaker (one on each side of the loop), smaller
wiring can be used to safely carry the electric current. Smaller wire is both cheaper and easier to
work with -- it bends more easily, can be pulled around corners with less effort, and is easier to
fit into the screws and connectors you need to attach it to. One other advantage is wiring
distance. Wire has some small amount of resistance, and the longer the wire goes to reach the
device it is powering, the more resistance it has. This results in a voltage drop over the length of
the wire run (by Ohm's Law), which could affect the operation of your electrical devices if it
drops too low. The maximum distance from the circuit breaker around the ring is the midpoint of
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the ring, while the maximum distance in a radial circuit is the end of the chain. In this manner,
the ring setup effectively cuts the distance to the farthest device in half.
Diagram explaining Ring Main System
Purpose in IFL:
Ring Main System is employed in IFL-PP as it provides better safety in case of
shutdown of one feeder; the system can use the other feeder line to meet the required power
demands and hence load sharing is made possible
5.5 Power Distribution
There are eight low voltage distribution panels in IFL. Seven of them are in Ring main network,
while LVD 8 is out of the main system. The structure of general LVD in ring main is discussed
as under.
LVD-2 description:
Two feeders (feeder number 4 and 11) coming out of PG-1 are terminated in two separate
HT panels. Their voltage is 11kv. These are separated by a VCB (Vacuum Circuit Breaker)
panel. These feeders then go to the transformer panels, two for each. The description of TRAFOs
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will be provided later. From secondary side of the TRAFO, the lines now enter the LT panels,
which are four in number. The voltage here is now 415V AC. This is then fed to power factor
improvement plants (PFIP). Here, power factor is improved and taken to almost .95-.97. It is
then fed to different loads.
5.6 Transformers
Almost all the transformers are of 2500KVA, 11KV/415V. There is a tripping gauge at
the transformer. If the temperature rises, it trips the power supply, thus protecting the
transformer. Grills are there to circulate the transformer oil to air cool it. Transformer oil is for
cooling and insulation purposes. A bucked relay is there to trip the transformer in case of
moisture. If moisture contents are high, an alarm operates and it trips the transformers.
Conservative tank is also there to store the oil.
The connections of most of the transformer are Delta/Star, however some
Delta/Star/Delta are also used, sharing 1250 KVA each.
5.7 Vacuum Circuit Breaker
Overview:
With rated current up to 3000 A, these breakers interrupt the current by creating and
extinguishing the arc in a vacuum container. These are generally applied for voltages up to about
35,000 V, which corresponds roughly to the medium-voltage range of power systems. Vacuum
circuit breakers tend to have longer life expectancies between overhaul than do air circuit
breakers.
Purpose in IFL-PP:
These breakers are used for primary safety purpose in Ring Main System. The feeder
lines are protected using VCB breaker and the panels connected in HT room are also protected
through it.
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5.8 ACB Breaker
Overview:
Rated current up to 10,000 A. Trip characteristics are often fully adjustable including
configurable trip thresholds and delays. Usually electronically controlled, though some models
are microprocessor controlled via an integral electronic trip unit. Often used for main power
distribution in large industrial plant, where the breakers are arranged in draw-out enclosures for
ease of maintenance.
Air circuit breakers may use compressed air to blow out the arc, or alternatively, the
contacts are rapidly swung into a small sealed chamber, the escaping of the displaced air thus
blowing out the arc.
Purpose in IFL-PP:
They are used for secondary safety purpose. Panels to which 440V is coming are
protected through ACB’s in case of short circuit or high current flow.
5.9 UPS System & Distribution
The purpose of UPS in IFL-2 is to provide power for control supply. There are two types
of UPS, one which has AC supply connected to its one end and driving the necessary circuitry,
while getting charged at the same time. When AC supply is cut off, the UPS charging provides
the necessary power. The other type is which gets charged only and doesn’t supply as long as
there is main supply available, as soon as the main supply is cut off the UPS provides the supply.
The UPS employed in IFL-2 are of this type.
5.10 Battery Maintenance
The lifters used in the warehouse of IFL-3 are battery powered. The reason for this is that
polyester is flammable, that’s why diesel engines are not used. The batteries of lifters have 24
cells with each cell producing 2V along with 690Ah of battery capacity.
S/F – 3 (Electrical)
Spinning & Drawline-3 is part of IFL-3. Constructed in 2012, it is capable of producing 600 Ton
Polyester per day.
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During the visit of S/F - 3, we were given familiarization with the power distribution
system and power factor control. A brief overview is given below. The tour of S/F 3 was given
by Mr Waqas (Sen. Engr) & Mr. Farhan.
5.11 Power Distribution at S/F-3
The power is brought to S/F -3 through feeder lines coming from PG2 at 11KVA. There
are four feeder lines coming into the Substation built at S/F -3. Two of them are coming from
PG-1(feeder #9 & 10) and the other come from Gas Turbine. These feeder lines are fed to the
feeder panels situated there which is connected to each other with bus couplers along with VCB
breakers. From there, these lines are fed to Transformer Room where the voltage is stepped
down from 11KVA to 415V. The lines from the transformers are fed to LVD Room in the form
of bus wires. The bus wires are fed to the panels in LVD Room where the panels are connected
in the form of Ring Main System along with Power Factor Control and ACCB Breakers for
safety purpose. From there, the power is supplied further as per requirement.
5.12 MCC Room
MCC Room or Motor Control Center where different motors in the SF-3 are controlled.
The purpose of this room is to control the speed of the motors hence controlling the output of the
SF-3 section. The speed is controlled through inverters which in turn are controlled through
PLCs via Control Room.
The explanation of different terms and the equipment mentioned above will be explained after
giving the summary of each section.
Machine Control:
There are four methods for machine control and protection. The current taken by the
machines is in hundreds of Amperes, so it is quite an important task to control the current and set
protective measures.
1- Simocode (Siemens motor control devices)
2- Inverter
3- Soft starters
4- Star-Delta starters
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5- Direct online (DOL)
Simocode:
These are basically protective devices, giving protection of over-current, over-voltage,
under- voltage etc. There are different kinds of fuses, tripping systems and connectors. Inrush
current is controlled by this device.
2- Inverter
Overview:
An inverter is an electrical device that converts direct current (DC) to alternating current
(AC); the resulting AC can be at any required voltage and frequency with the use of appropriate
transformers, switching, and control circuits.
A variable-frequency drive controls the operating speed of an AC motor by controlling
the frequency and voltage of the power supplied to the motor. An inverter provides the controlled
power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the
inverter can be provided from main AC power. Since an inverter is the key component, variable-
frequency drives are sometimes called inverter drives or just inverters.
Purpose in IFL-PP:
Inverters are employed to control the speed of the motor. This control of speed in turn
helps in controlling the plant output and efficiency.
3- Star delta starters:
These starters are for over current protection. In the beginning when motor starts, it takes
too much current because starting torque is too high. Star has higher resistance, so it takes less
current and the opposite is in delta system. Hence, in the start of the motor, we start it on star
configuration and then converted to delta when it smoothens.
4- Soft starters:
These devices are another manner of starting the machine. Soft starters also limit the
current in the beginning by the help of different modules in it.
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5- Direct online:
It is the simplest way of starting the motor with simple over-current fuses.
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Chapter 6
Instrumentation Department
6.1 Introduction
The purpose of visiting Instrumentation Department in IFL-PP was to get familiarized
with the PLCs, DCS and their use in industry.
The tour of Instrumentation Department was given by Mr. Hammad and Mr. Furqan. During the
visit of this department, we were given familiarization with the PLCs basics and their purpose in
IFL-PP. A brief overview is given below.
6.2 PLC
PLC is composed of three parts:
1) CPU
2) Input/output Module
3) Power Supply
CPU stands for central processing unit at it is the brain of PLC as it performs all the
processing required. I/O Modules are used for connecting the input and output parameters to the
PLC. And power supply is for providing the necessary power for PLC to carryout required
operations.
There are basically for languages which are used for programming PLCs.
1) Ladder Logic
2) Functional Block
3) STL or Structured Text Language
4) Sequential Function Chart
Ladder Logic and Functional Block lacks features related to mathematical modeling. To
overcome this, Statement text language is used. But STL has a problem of its own; the code
written in STL is sometimes lengthy and complex. To tackle this, Continuous Function Chart are
used which have built in functions, all we need to do is pass them parameters. Further, there is
S7 Graph which is used in problems where if-else statements like problem are at hand. Protos is
other language which gives graphic capabilities like joining different parts visually to write a
program.
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There are different models of PLCs available each differing on the basis of number of I/Os.
In IFL-PP, models used are:
Fiber Line-I S5 135U
Spinning-I S5 115U
Baler-I S5 95U + S5 115U
Fiber Line-II S7 300
Spinning-II S7 400
Baler-II S7 300
Further, there are communication processors which are used for interfacing different
things with PLCs like printer or connecting two PLCs together for communication between
them.
In IFL-PP, the visual panels employed by PLCs are OP5 and OP15 for PLCs of S5 model
and OP7, OP17, OP27, PP27 and MP217 for S7 model. The purpose of PLCs is to control the
speed of motor and operation of Baler. The general overview of PLCs in IFL-PP can be summed
up as:
OCS
PLCs
Inverter
TACHO
Motors
30
6.2 Utility
All the minor materials that are needed to run an industrial process are termed as utility. In
IFL-1, following elements are regarded as utility:
Purified and Distilled water
Soft Finish Oil (SFO)
Quench air
Chilled and hot water
6.3 Control Systems in Utility area
Although the whole plant is controlled through DCS, yet utility processes are mainly
handled by their separate PLCs. Not the whole data goes to the central control station. Just few
inevitable sensor data is sent to OCS. This data can only be viewed from OCS, but one cannot
make any change in the controlling factor through OCS monitor. The controlling factors are
changes and processed only in its separate control room.
Introduction to PLC
Hardware
IFL polyester plant is using the PLCs of Siemens S7. It has two major components:
1- Power Supply
2- CPU
In Siemens S7, there are two DPs. One port is called MPI port. It is used for short
distances only. Through this port, we can connect it to devices that are at a short distance
(10m) from the PLC like HMI (Human Machine Interface) or a PG, which is a laptop like
device especially designed to view, download and process the data of a PLC. S7 has an
interface module which is used to connect it to the distributed I/Os. There are various
cards in the interface module like Digital Input, Digital Output, Analog Input and Analog
Output.
Software
The software which we use in PLC is Sematic Manager 5.5. The programming of
a PLC is quite simple and easy. There is a hierarchical in its coding. The hierarchy is as under:
1- Organization Block
In this block, all the functions of a program are called in a sequence.
31
Function Block
All the data which is needed to be added in the program is interpreted and
transferred in this level.
2- Data Block:
It takes all the data of timers and records.
Similarly, STL, Ladder Logic and FBD (Function Blok Diagram) are the approaches of
programming employed in it. In STL, programming is just like assembly language, with its own
syntax. Ladder Logic is simple and diagram based programming. FBD uses function blocks to
implement its logic.
User interface
PLCs may need to interact with people for the purpose of configuration, alarm reporting
or everyday control. A Human-Machine Interface (HMI) is employed for this purpose. HMIs
are also referred to as MMIs (Man Machine Interface) and GUI (Graphical User Interface). A
simple system may use buttons and lights to interact with the user. Text displays are available as
well as graphical touch screens. More complex systems use a programming and monitoring
software installed on a computer, with the PLC connected via a communication interface.
Communications
PLCs have built in communications ports usually 9-Pin RS232, and optionally for RS485
and Ethernet. Modbus, BACnet or DF1 is usually included as one of the communications
protocols. Others' options include various fieldbuses such as DeviceNet or Profibus. Other
communications protocols that may be used are listed in the list of automation protocols. Most
modern PLCs can communicate over a network to some other system, such as a computer
running a SCADA (Supervisory Control and Data Acquisition) system or web browser.
Programming
PLC programs are typically written in a special application on a personal computer, then
downloaded by a direct-connection cable or over a network to the PLC. The program is stored in
the PLC either in battery-backed-up RAM or some other non-volatile flash memory. Often, a
single PLC can be programmed to replace thousands of relays.
32
Fig. 6.1: A PLC
How things work in a PLC room
A PLC control room is made of a number of panels, invertors, HMIs and data input
devices like keyboards. All the readings of the sensors are being shown on the screen. If a
parameter is not right, the operator applies the relevant change in the data, so that the conditions
may match the set point.
6.4 Sensors
Introduction
Being a highly automated plant, IFL has employed high level sensors and detectors with
its devices. Some major sensors used in the field are discussed as follows:
RTD:
It is resistance temperature detector. As the temperature increases, there is a change in the
resistance, which is recorded and processed to get the corresponding temperature.
Pressure Transmitter:
This device controls the pressure in a vessel. It is of Diaphragm type.
33
Level switches:
There are a number of level switches used. Some of them are as follows:
Float Type
Magnetic
Motor controlled
Ultrasonic
Radioactive
Radioactive level sensors are employed in large silos and tanks, where it is difficult to
measure the level of polymer paste due to lack of physical contact, and viscous material.
Flow Sensors:
Three kinds of flow sensors are used in the field:
Micromotion
Rota meter
Venturay
Proximity Switches:
These are of two types.
1- Capacitive Proximity switches:
These are used to detect the non-metals.
2- Inductive Proximity Switches:
These are for metal detection.
Wrap Detectors:
When TOW is being drawn before crimping machine, there are wrap sensors to detect if
TOW is wrapped at the rollers.
Load Cells:
These are used to measure the weight of anything. When polyester is bailed in 350kg
bales, load cells measure its weight.
34
Chapter 7
Distributed Control System
7.1 Introduction
IFL has the most modern of control systems available here in Pakistan. The system used
is of Emerson Company situated in Germany. It uses Plant web architecture. Emerson control
system has DeltaV software for data interpretation and HMIs, and AMS (Asset management
system) for engineering station.
7.2 Communication Protocols:
HART protocol is most widely used protocol for communication in the controlled
systems. But, only HART is not beneficial. One has to decide for a blend more than one
protocols for efficient, intelligent, speedy, low cost and safe data transmission and receiving. In
plant web architecture, following protocls are used for special purposes:
AS-I for cost sensitive instruments
DeviceNet for motor stator integrated circuits
Profibus-DP for master slave networks
Protocol Intelligence Ease of
Installation
Savings Acceptability
AS-I Normal High Normal Normal
DeviceNet Normal Normal Normal Normal
Profibus
DP/PA
Normal Normal Normal Normal
Ethernet Low Normal High High
HART Low Normal Low Normal
Table: Comparison of different Protocols
35
General communication in DCS system
A Simplified Topology
8
Field Sensors
Data Conversion to optic
Fibre cables
8TX simple cables to the
primary convertor
(MCC)
PSU (Containing power supply,
input/ output ports and data
redundancy systems etc.)
24 TX patch boxes for
long distance
36
To DCS Room, DCS
panels
Conversion from Optic to
simple cable
To application System,
Engineering station, and
OCUs
37
Chapter 8
PG- 1
8.1 Introduction to power sources
IFL has wisely devised its power generation plan. The capacity to provide power is
almost three times the requirement. The reason is that polymer process is quite critical and we
cannot afford its unscheduled shut down for more than fifteen minutes. Otherwise, PTA and
MEG paste hardens and sticks in the pipes, thus blocking and causing severe problems. That is
why, there are a number of power sources in IFL including power generation with Nigata
engines from furnace oil (HFO) and a gas turbine. A coal fired plant is also being erected. In
addition to this, IFL has also arranged a grid station which can provide up to 14 MW of
electricity whenever required.
8.2 PG-1
The major power source at IFL is from PG-1, which supplies power to almost 90% of the
load in all polyester and textile plants. Its installed capacity is 58.5 MW, which is divided in
three phases. The detail is as follows:
Phase-1:
There are four Nigata engines in phase 1, each having a capacity of 5.3 MW. Hence the total
capacity of phase 1 is 21.2 MW.
Phase-2:
There are two Nigata engines in phase 2, each having a capacity of 5.3 MW. Hence the total
capacity of phase 1 is 10.6 MW.
Phase-3:
There are five Nigata engines in phase 3, each having a capacity of 5.3 MW. Hence the total
capacity of phase 1 is 26.5 MW.
38
8.3 HFO processing
All of these phases are connected by bus couplers, which are normally open. In this way,
load can be shared between them whenever required.
The Complete Process:
1- HFO Storage:
The HFO which is brought in the tanks from refinery is off loaded and stored in three
tanks each having a capacity of (2500 tons). These are capable of providing the fuel for
one month. There are two pumps, which transfer HFO to the storage tank, one at a time
and other is at standby.
2- HFO purifier:
Now, HFO is purified by a number of stages, the first one being through settling
of impurities in settling tank. In this tank, heaters are used to remove sludge and Sulpher
contents along with other heavier impurities. Oil is cleaned to some extent in this stage,
and is sent to the clean tank with the help of pumps. The capacity of these two tanks is 16
tons per tank.
3- Centrifugal purifiers:
The somewhat clean HFO is then taken to centrifugal purifiers, where it is cleaned
to greater extent by the Centrifuge Principle.
4- Clean tank:
The HFO from the centrifuge tanks comes to the clean tanks. Heaters are present
here to settle down the remaining impurities.
5- Circulation Pump:
This is the heart of power house. From here on in, HFO is sent to the common
header, where different feeders are present to divide this HFO to all engines.
39
6- Common Header:
There is a changeover at each feeder from the common header. There are three
valves at the changeover. One is for Diesel, the other for HFO and the third one is for
outlet to the engine. HFO is too viscous that if turn off the engine and let the fuel in the
pipes, it sticks to them, reducing its diameter. Therefore, whenever an engine is to stop,
we run it on Diesel, so that the pipes may not get stuck due to viscous HFO.
7- Mixing Bottle:
The HFO which is not used by the engine comes back to a mixing bottle. Its
temperature is different from that of fresh HFO. The mixing bottle settles its temperature
to a certain level. Similarly, the diesel is present at the roof is also at atmosphere
temperature, its temperature is also settled in this bottle.
8- Fuel oil Field Pump:
Here, pressure of the fuel is increased to about 5-6 kg/cm3.
9- Filters:
The fuel is then passed from a set of filters which are called primary, secondary
and fine filters. Difference is in the sizes of siege holes.
10- Viscosity Controllers:
HFO is viscous oil. It is necessary to establish its thickness to a reasonable level.
Viscosity controllers are automated and can be controlled via display panels. There are
viscosity motors, which take some fuel from the line, measure its viscosity and then give
back to the line.
11- Accumulating Bottle:
To save from bubbling due to different firing order, the fuel is stored for some
time in accumulating bottle. There are eight fuel injection pumps on both sides of the
engine, which work according to the order. The firing order allows one injection pump to
open at a time. Firing order is as follows, the numbering is of fuel pump numbers
40
First side: 1, 3,2,5,8,6,7,4
Second Side: 8, 6,7,4,1,3,2,5
12- Fuel pumps
Sixteen fuel injection pumps increase the pressure of fuel to 1100 kg/cm3. It then
sprays on piston heads.
8.4 Air Compressors
Air is needed by the Nigata engines for combustion. In order to provide compressed air,
air compressors are there which increase the pressure up to 28 Kg/cm3. There is a safety valve at
30kg/cm3.Through main starting valve, it goes to the pilot valves. Now, there is a moving disc,
which opens the pilot valve of one duct out of total eight ducts on each sides, according to the
firing order.
8.5 Governor and its Working
It is present alongside the engine to control the speed of the shaft. Speed is directly
proportional to the amount of fuel. There are fuel racks attached to the governor. Whenever more
speed is needed, governor tends to pull the racks inside, thus injecting fuel with more flow rate.
Hence, speed is increased.
A fly weight is also there to symbolize the speed of the shaft. It works on the centrifuge
principle. When speed is slow, it tends to rotate at lesser height than standard. To maintain its
height, governor operates the fuel racks for more fuel.
A governor motor is also there to increase the speed accordingly. Whenever it is needed
to increase the speed by us, regardless of the load, governor motor is used. Two heavy springs
are present below the motor, and above the fly weight. When Speed is to increase, motor is
rotated, which affect the position of the springs. These springs, in turn, tend to apply pressure on
fly weight. When fly weights are down, governor pulls the fuel racks for more combustion, more
speed and hence, fly weights come to their set point height.
41
Fig.8.1 : Phase 1 and phase 2 facts and figures
42
Fig.8.2 : The complete process from HFO processing to feeder distribution
43
8.6 Generator
Overview:
Synchronous generators are the primary source of all electrical energy and commonly
used to convert the mechanical power output of steam turbines, gas turbines, reciprocating
engines, hydro turbines and wind turbines into electrical power for the grid. These generators are
known as synchronous generators because they operate at synchronous speed. The speed of the
rotor always matches supply frequency.
The rotor is mounted on a shaft driven by mechanical prime mover. A constant rotating magnetic
field is produced in the rotor by the permanent magnets. An AC voltage is induced in the three-
phase armature winding in the stator to produce electrical power. The electrical frequency of the
three phase output depends upon the mechanical speed of the prime mover and the number of
poles.
Fig. 8.3 A synchronus generator
Purpose in IFL-PP:
Power in PG-2 is produced with the help of synchronous generator which is run by GT,
both mounted on the same shaft. The speed of the generator is 1500rpm whereas the speed of GT
is 11200rpm; the decrease in speed of generator is achieved through gears.
44
Fig. 8.4: Specification of generators
45
Fig.8.5 : Specifications of exciter
8.7 Permanent Magnets:
Permanent magnets are used to supply field current. These are controlled by PGAVR.
The procedure of starting of field circuit is quite critical and it is done in three stages. In the first
stage, permanent magnet is used to generate only 30% of the set point voltage.In generator
control unit (GCU). It is then converted to DC and fed to AVR. If the conditions are not worse,
AVR decides to now take the 85% of the set point voltage. The process of feeding to the AVR is
repeated. Similarly, the third stage is to get a voltage of 115% of the set point voltage. However,
not all 115% is used, which is 215 volts. We only use a fraction of it according to current
demand.
The first stage is for control voltage. It depends on the load. If we have no load, 36V is
generated. For 3MW load, 54 volts are generated. It means, the voltages fed to AVR in the first
stage are just control voltages.
46
8.8 Power Produced:
The 11kV voltages established at the stator are taken in the form of three phases four wire
system. The generated wires are connected in star configuration. It is then converted to Delta for
transmission.
There are two armature terminals, with three phases. One is given to the bus bar, and the
other one to NGR.
Fig.8.6 : Specification of Permanent magnet
47
8.8 Station Transformers:
The electricity generated is used to run the MCC and other auxiliary panels of the power
house. This is done by the station transformers. These transformers step down the voltage to 415
volts and supply the energy demand of the power house.
Fig. 8.7 : Specifications of transformers
48
49
8.9 Auxiliary Supply
Battery Room:
There is an emergency supply system, based on battery storage. There is a capacity of 130volt
batteries with one cell of 1.2 volts. These are charged in three manners:
1- Manual
2- Floating
3- Equalizer
In manual mode, we can give the voltages according to our own choice. Floating and exciter
modes are automatic. Whenever we are not taking any current from the battery, it is on floating
mode, thus providing 130 volts each time. When any drip comes, it automatically shifts on the
next mode, which is equalizer . Here, 150 volts are being supplied. Now, there is a timer at the
equalizer. If voltage drop is more than 20% of the battery voltage, this mode works for 10 hours.
Otherwise, it works for 5 hours.
50
Fig.8.8 : Starting of an engine
51
Fig.8.9: Excitation of a generator
52
Appendix A
Relay Logic and Metering
A-1.1 Types of Relays in Relay Logic Control
Thermal Relay:
It works on bi-metallic strip. Due to heat generated, the strip reverses the
connection. Normally open and normally close are the two contacts of the relay.
Magnetic Relay:
It works on the magnetism principle. Due to magnetism, contacts are energized
and change the connections.
A-1.2 Metering in Panels
Transducers:
The major purpose of the transducers is to convert the voltage and current of a
power source to some control value. CTs and PTs are employed for this. There are
different kinds of transducers. Some of them are listed as under:
Watt Transducer
Power Factor Transducer
Demand Transducer
VAR Transducers
All of these transducers give the value in the form of current and voltage. For
example, for pF transducer:
Unity power factor: 0V
Lagging pF (max.): +5V
Leading pF (max.): -5V
53
CT (Current Transformers):
These are used to measure the AC current by scaling it down. Moreover, to use
the current for control purposes, CTs are used to step down the current.
NOTE
Never leave the two output wires of the CT open. Either pass it through some
load, ammeter or simply short circuit it. It becomes a step up transformer otherwise.
Shunt Resistance:
To measure the DC current, shunt resistance is used. The resistance and voltage is
known, so current is easy to measure.
Timers:
These are used to set the specific time for a process. On delay and off delay are
the two terms associated with the timers. On delay is used for the first or running application,
and off load is used for the application needed to start after the set time.
Alarms:
These are used for different purposes, like for increase of load from a specific
value.
54
Appendix B
NGR and Normal Critical Points
B-1.1 Protection
Protection is the most important and critical part of a power system. There are over
current, under current, under and over frequency, and ground over current relays. The final
protection is of NGR, which will be discussed here.
All the generators are connected to a common bus through heavy bus coupler. The other
side of generators is made common, to form star configuration. Before joining, each phase is
passed through an over current relay. The neutral point is given to the NGR through a connector.
All the connectors are open except one.
Not all the neutrals of the generator are connected to the NGR. Just one generator is
necessary to connect. Otherwise, huge fault current will circulate through the circuit. NGR is
actually a resistor with its value more than the armature resistance.
B-1.2 Critical Points
If one of the generator, shares more reactive power, power factor of other generators is
improved.
If power factor is too low, generator winding may burst.
If frequency is high, speed at no load increases.
Common bus never reduces the frequency of the system nor the terminal voltage, it just
shares the power to all generators.
If frequency of one generator tends to be high, load capability is increased, while
frequency of system remains the same.
However, if there is too much increase in load, or too much load shedding, the system
may go to the under voltage (8kV) or over voltage (13 kV) condition.
55
The following relations should be kept in mind for power generation control:
Frequency is directly proportional to the active power.
Voltage is directly proportional to the reactive power.
Speed is directly proportional to the generator frequency.
To share the reactive power of two generators, increase the exciter current.