Internship Report FFC

AN INTERNSHIP At FAUJI FE RTILIZER COMPANY 

Internship Report M UHAMMAD H A  AS SSAN Seat No: D_10_ES_1050 Final Year ( Electronics Engineering) Dawood University of Engineering & Technology Internship Duration ( 14 February 2013 to 7 March 2013)

Submitted to  to:: Technical Training  enter  (TTC) (TTC) Mirpur Mathailo 

D A W O O D U N I V E R S I T Y O F E N G I N E R I N G & T E C H N O O G Y K A R A C H I

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 Acknowledg ment  Ultimately, I have completed my report with all the hard work which I have been oing for the last six weeks. First and foremost, th ank you Almighty Allah for giving me the strengt to finish up this report. Without Your Willlingness I would not have been able to complete ny work. I would never forget to mention the names, which played a great role in the succe ssful completion of this project, and helped me, whenever I required any guidance from them, pr ovided me with books for assi tance and gave me ideas on different thoughts. I would like to take this oppo tunity to express my deepest gratitude to Mr.A if JAMAL & encouragement constructive a vises and their Mr.Anjum Beig who have given me their constant encouragement patience in monitoring my progress. I am also grateful to my coordi ators Mr. Muhammad Fahad Sayeed & Mr. Umair Akbar Khan who were a great help for me by monitoring my learning and helping me understan d the process in numerous interactions. Finally, I ould like to extend my sincere gratitude to Mr. Aftab Ahmed Mazari for his helpful nature and valuable guidance provided time and again. Without your willingness, sugge stions and insights, this project would not have b een completed.

I am very much thankful to FFC which provided me a chance to integrate my clas room knowledge with industrial practical knowled ge in a 6 weeks internship program. I would not f rget to mention about all the kind panel boardm n and operators who had been a very useful guid e in the Central Control Room and on the plant site, respectively. At last, I can say that my work was just an effort but wouldn’t have been an eff ort discernibly without the support of all acknowledged people.

PREFACE The purpose of this report is to exp lain what I did and learned during my internship internship period with the Fauji Fertilizer Company Mirpur Mathelo . The report is also a requirement for the partial ful fillment of FFC MM internship program. The repor t focuses primarily on the assignments handled, wo rking environment, environment, successes and shortc omings that the intern did encounter when handlin g various tasks assigned to him by the coordinator .Because the various parts of the report reflect the intern’s shortcomings, successes ,observati ns and comments, it would be imperative that the

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recommendations recommendations are also given. T herefore the report gives a number of comments a d recommendations recommendations on the internshi program. It is hoped that this report would serve s a cardinal vehicle to the improvement of the iinternship program.

INTRODUCTI  N TO FFC  For an agricultural country like Paki stan, Urea carries a paramount importance. Keepin this in view Fauji Fertilizer Company (FFC) was inc rporated in 1978 as a private limited company with a vision to acquire self - sufficiency in fertilizer productiion in the country. This was a joint venture between Fauji Foundation (a leading charitable trust in Pakist n) and Haldor Topsoe A/S of Denmark of Denmark.Fauji .Fauji Fertiilizer Company Ltd is the leading urea producing c ompany in the Pakistan, with brand name “S NA UREA”.FFC UREA”.FFC commenced commercial productio

of urea in 1982 with annual capacity of 570,000 metric tons. First

plant of the FFC is located at GOTH MACHI in SADIQABAD. After the excellent performance a nd the successful achievements of the first plant, FFC installed the second plant at the same place in the year 1993. First plant is called the BASE UNIT and the second plant is called the EXPANSION UNIT. This enhanced Production capacity with a nnual capacity of  635,000 metric tons of urea. In the year 2002, FFC acquired e

Pak Saudi Fertilizers Limited (PSFL) Urea Pla t situated at

Mirpur Mathelo, District Ghottki fr om National Fertilizer Corporation (NFC) through privatization process of the Government of Pak istan. It has annual production capacity of 574,00

metric tons

urea which has been revamped to 18,000 metric tons urea in 200

 SAFETY TRAI  ING  FFC produces about 60 % of m rket’s urea production. Not preparing for plant afety may not only result in decrease of company production and sale but also in shortage of f ertilizer in market. This may affect the cou try’s agriculture growth and thus shortage of food for public followed by price hiking. FFC ensures safe work environ ent by providing safety training to all personnel on plant. As per th company policy all news personnel on plant receive safet training prior taking charge of their  responsibilities The training comprised of:

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Importance of Safety at Plant

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Use of Personal Protec ive Equipment

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Use of Fire Extinguishers

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Ammonia Disaster 

PERSONAL PROTECTIVE E UIPMENT Personal protective equipment (P.P.E) must not be regarded as a substitute for safe w rking practices. Minimum personal protective equipment is as follow. •

Safety Helmet

•

Safety boot/shoes

•

Escape respirator (Half Fac e Mask)

•

Ear protection (designated areas)

•

Safety Spectacles.

“Your life is precious”

The correct use, care an regular cleaning of the above equipment is the responsibility of each in ividual.

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INSTUMENTAT ON & CONTROL ORIEN  ATION TOPIC 

Introduction to inst umentation & control.

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Sample Control Lo p.

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Introduction to Documentation, Drawings, P & I’s.

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Types of instrumen s.

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Introduction to Intrinsic Safety.

CO-ORDINATOR ENGR. MU MU AMMAD SAEE  E  A MMAD FAHAD SAE  E 

INSTRUMENTATION Instrumentation is the art of measur ing the value of some plant parameter Pressure, flo , level or  temperature to name a few and supplying a signal that is proportional to the measured arameter. The output signals are standard signal a nd can then be processed by other equipment to pr  vide indication, alarms or automatic control. There re a number of standard signals; however, those m ost common in the plant are the 4-20 mAmps Electroni c signal and 3-15 psi pneumatic signal.

CONTROL TECHNOLOGY  Control of the processes in the plant is an essential part of the plant operation. There m ust be enough water in the boilers to act as a heat sink for the reactor but there must not be water flowing out the top of  the boilers towards the turbine. The level of the boiler must be kept within a certain range. The heat transport pressure is another criticall parameter that must be controlled. If it is too high t e system will

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burst, if it is too low the water will b il. Either condition impairs the ability of the heat tra sport system to cool the fuel. The usual objective of control theor  is to calculate solutions for the proper corrective a tion from the controller that result in system stabi lity, that is, the system will hold the set point and no oscillate around it. The first automatic feedback controlller used in an industrial process was James Watt’s lyball governor, developed in 1769 for controlling th speed of a steam engine.

CONTROL LOOP A control system consists of subsys tems and plants(processes) assembled to control o tput of process.   A si mp le co nt ro l lo o p

A simple closed loop control re q uires feedback; information sent back direc t from the process or system to a controlller which manipulates it keeping set point in view and produces the corresponding ou tput to control final control element. Feedback control is a fundamental act of modern industry and society. Driving an auto obile is a pleasant task when the auto respon ds rapidly to the driver’s commands. Many cars have power steering and brakes, which utilize hydraulic mplifiers for amplification of the force to the brakes or the steering wheel.

A simple block diag am of an automobile steering control system is sho n,

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The desired course is compared wit h a measurement of the actual course in order to ge nerate a measure of the error .This measurement is o tained by visual and tactile(body movement) feedb ck. There is an additional feedback from the feel of  the steering wheel by the hand (sensor) A basic, manually controlled closed loop system for  regulating the level of fluid in a tank is shown in Figure .The input is a reference level of fluid that the operator is instructed to maintain.(This referen e is memorized by the operator.) The power amplifier is th operator, and the sensor is visual .The operator comp ares the actual level with the desired level and opens or  closes the valve (actuator), adjusting the fluid flow o t, to maintain the desired level.

Introduction to Document  tion, Drawings, P & I's: Documentation is done to keep the record of all the things, instruments & Chemical being used in plant. All t he departments in the industry have their own literature about their concern things and they go through the literature of all the things that they need to use, to re air or install. Here in instrument department all th instruments have their records collected in files with t eir vendor's name and specifications. In industry we keep the records of f  llowing:  History cards (Switches, Tr  nsmitters, Valves, P SV's).  Calibration cards.  Warehouse Documents whiich includes MOR (Manual Order  Request), MRF (Material Reservati n Form), MIV (Material Issue Voucher), MWR (Maintenance Wo k Request).  Set point changing form  Cabinet daily monitoring for m  Power supply load checkin  DCS vibration probe histor  etc. In industries there are some field p laces where the loops of a system is long Enough o understand .For  this purposed designers make draw ings on big Sheets that shows all the process and i struments involve in those processes. A line diagram that helps us to understand the whole process in cluding function of  each instrument is called Process & Instrument diagrams.

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TYPES OF INSTRUMENT Here in FFC MM we use several t pes of instruments that have their specific function and use according to the requirements .The major inst uments which we use here are: Transmitters, Thermocouples, E / P, Speed Probes, Vibration Probes, Pressure ga uges, Controllers, Recorders, Indicators, Switches, T mperature Indicators local, Petitioners’, Pressure s itches Analyzers, SOV's, Tachometers.

FIEL

INSTRUMENTATION

TOPIC 

Level, Flow, Pressure &Temperature measuring techniq es & instrument being us ed.

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Switches (Level, Fl w, Temperature & Pressure)

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Float type level indi cator 

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Transmitters Transmitter s & I/P’s

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SOV’s

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Analyzers

CO-ORDINATOR ENG E   NG .UMAIR AKBAR  E  

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PRESSURE Pressure is probably one of the mo t commonly measured variables in the Power plant.. It includes the measurement of steam pressure; fe ed water pressure, condenser pressure, lubricating oil pressure and many more. In many ways, pressure is the prim ry element in many of the process measurement, s ch as: 

Flow (measuring pressure drop across restriction by creating differential press re)  Level (measuring the pres ure created by vertical fluid column) “Pressure is the force exerted by  fluid or gas and it is transmtted in all directions throughout the fluid /gas.”  Pressure acts on surface area of ve ssel or chamber in which it is confined. Mathematically Pressure is actually the measurem nt of force acting on area of surface. We could repr  sent this as: Force = Pressure / Area

Pressure scale Pressure varies depending on altitu de above sea level, weather pressure fronts and oth er conditions. The measure of pressure is, therefore, r elative and pressure measurements are stated as either gauge or  absolute. Gauge pressure is the uni t we encounter in everyday work (e.g., tire ratings a e in gauge pressure). A gauge pressure device will indicate zero pressure when bled down to atm spheric pressure (i.e., gauge pressure is referenced t o atmospheric pressure). Absolute pressure include s the effect of  atmospheric pressure with the gaug e pressure. An absolute pressure indicator would in dicate atmospheric pressure when comple tely vented down to atmosphere - it would not indic te scale zero. Absolute Pres ure = Gauge Pressure + Atmospheric Pressure

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PRESSURE MEASURING EVICES 

BAROMETER: For measuring atmospheric pressure.

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MANOMETER: An instrument that measures pressure in terms of height of a col mn of liquid. It

has three types: a) U-shaped Manometer  b) Inclined Manometer  c) Ring Shaped Manometer 

BOURDON TUBES: Bour  on tubes are circular-shaped tubes with oval cross sections. T he pressure of the medium acts on the inside of the tube. The outward pressure on the oval cross section forces it to become rounded. Because of the curvature of the tube ring, the bourd on tube then bends as indicated in the direction of the arrow.

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BELOWS : Bellows type lements are constructed of tubular  membranes that are convol uted around the circumference. The membrane is attached at o e end to the source and at the other end to an indic ating device or  instrument. The bellows ele ment can provide a long range of motion (stroke) in the direction of  the arrow when input press ure is applied.

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DIAPHARAM: A diaphr  gm is a circular-shaped convoluted membrane that is attached to the pressure fixture around the circumference. The pressure medium is on one sid and the indication medium is on the other. The deflection that is created by pressure in he vessel would be in the direction of the arr ow indicated.

PRESSURE TRANSMIT  ERS  Most pressure transmitters are built around the pressure capsule concept. They are us ally capable of  measuring differential pressure (that is, the Note difference between a high pressure in ut and a low pressure input) and therefore, are u sually called DP transmitters or DP cells.

Capacitance Type

ressure Transmitter 

A capacitance cell measures chang es in capacitance. The capacitance of  the capacitance of a capacitor is dir ectly proportional to the area of the metal plates and inversely proportio nal to the distance between them. It also depends on a characteristic of  the insulating material between them.

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This characteristic, called permittivit y is a measure of how well the insulating material in creases the ability of the capacitor to store charge. C=E A / D Two capacitors are joined together iin such a way that they have one plate in common hich is actually a diaphragm. High and low pressures are applied at the two sides of the diaphragm whic causes it to deflect from high to low pressure si e. This deflection causes a change in the capacitan ce of the capacitors. Thus difference of press ure is converted into difference of capacitance.

Potentiom tric Pressure Transmitter  It also works on the similar principle but uses a variable resistor to measure pressure instead of capaciitance. Two chambers are joined with a common diaphragm and appllied with high and low pressure. Difference of pressure causes diap ragm to move a little towards lower pressure side. As a result ne dle attached with it, moves over a potentiometer changing its resistan e between electrical contacts. Thus difference of pressure causes a corresponding change in the resistance. Figure shows a similar  ssembly where a spring is used to produce a constant pressure on on side of diaphragm.

Linear Variable diff  rential Transformer  LVDT also works on the similar principle for measuring differential pressure. Diaphragm is connected t o an extension rod. The extension control rod is made f a metal suitable for acting as the movable core of a transformer. oving the extension between the primary and secondary windings of  a transformer causes the inductance between the two windin s to vary, there by varying the output voltage proportional to the p sition of the control rod extension.

FLOW “The quantity of fluid pas ing a given point in a specific period of  ime is called  its flow rate.”  BASIC FLOW MES  RING METHOD There are various methods used to measure the flow rate of steam, water, lubricants, air, etc., in a nuclear generating station.

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Rate of flow is measured by the diff erential pressure method. Some form of restriction i placed in the pipeline to create a pressure drop. he pressure before the restriction is higher than aft r restriction or  downstream. Such a reduction in pr essure will cause an increase in the fluid velocity because the same amount of flow must take place bef  re the restriction as after it. Velocity will vary directl with the flow and as the flow increases a greater pres sure differential will occur across the restriction. So by measuring the differential pressure across a restric tion, one can measure the rate of flow.

ORIFACE PLATE  An Oriface plate is used to make a abrupt change in the pipe area and simply consist of circular plate usually inse rted between pipe flanges. This produces a pressur  differential which is usually measur  d at upstream trapping and downstream trapping. The downstream pressure is lower  han the upstream pressure; the orifice causes permanent loss in pressure called t e head loss. This can be as high as 50% of  upstream pressure. In application w here this cannot be tolerated, a venture tube is used.

The high and low-pressure taps of t he primary device (orifice type shown) are fed by sensing lines to a differential pressure (D/P) cell. The output of the D/P cell acts on a pressure to milliamps transducer, which transmits a variable 4-20 ma signal. In actuality the differential press re increases in proportion to the square of the f  ow rate. We can write this as:

∆P ∝ Q2

In other words the flow rate (Q) is proportional; to the square root of the differential pres sure. olumetric Flow Rate = Q ∝ α ∆P To convert the signal from the flow transmitter, to one that is directly proportiona l to the flow-rate, one has to obtain or extract the s quare root of the signal from the flow transmitte r. The square root extractor is an electronic (or pneum atic) device that takes the square root of the signal f rom the flow transmitter and outputs a correspon ding linear flow signal.

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Flange Taps : Flange taps are the most widely used pressure tap ping location for orifices

A three-valve manifold ha to be used to protect the DP capsule from being overranged.

Orifice Plate w ith Flange Taps and Three Valve Manifol d

VENTURI TUBE The orifice plate produces a large h ead loss. If this is unacceptable a venturi tube can b e used. Because of its gradually curved inlet and outl et cones, almost no permanent pressure drop occur s. This design also minimizes wear and plugging b y allowing the flow to sweep suspended solids thro gh without obstruction.

The Venturi tube normally uses a s ecific reduction in tube size, and is not used in larg r diameter pipes where it becomes heavy and exces sively long. The advantages of the Venturi tube are iits ability to handle large amounts of suspended solids, it creates less turbulence and hence less insertion l oss than the orifice plate. The differential pressu e taps in the Venturi tube are located at the minimum and maximum pipe diameters. The Venturi tube h s good accuracy but has a high cost.

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PITOT TUBE  Pitot tubes also utilize the principles captured In Bernoulli’s equation, to measure flow. Most pitot tubes actually consist o f two tubes. One, the low pressure tube measures the static pressure in the pipe. The second, the high press re tube is inserted in the pipe in such a way that the flo ing fluid is stopped in the tube. The pressure in the high -pressure tube will be the static pressure in the syst m plus a pressure dependant on the force required sto pping the flow. Pitot tubes are more common me suring gas flows that liquid flows. They suffer from a co ple of problems. The pressure differential is usually small and hard to measure. The differing flow velocities acros s the pipe make the accuracy dependent on the flow p rofile of the fluid and the position of the pitot in the pipe.

 ANNUBAR An annubar is annubar  is similar to a pitot tub used to measure the flow of gas or liquid in a pipe. The pitot tube measures the difference between t e static pressure and the flowing pressure of the m dia in the pipe. The volumetric flow is calculated fro m that difference using Bernoulli's principle and taki ng into account the pipe inside diameter, The biggest difference between an annubar and annubar  and a pitot tube is that an annubar takes ultiple samples across a section of a pipe or duct. I this way, the annubar averages the differential pre ssures encountered accounting for variatio ns in flow across the section. A pitot tube will give a similar reading if  the tip is located at a point in the pi e cross section where the flowing velocity is close t the average velocity.

LEVEL BASIC FLOW MESURING

ETHOD

Very simple systems employ extern al sight glasses or tubes to view the height and hen e the volume of  the fluid. Others utilize floats conne ted to variable potentiometers or rheostats that will change the resistance according to the amount of motion of the float. This signal is then inputted to transmitters that send a signal to an instrument calib rated to read out the height or volume. The level of liquid inside a tank can be determined from the pressure reading if the weight density of the liquid is constant. Differential Press re (DP) capsules are the most commonly used devices to measure the pressure at the base of a tank.

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Glass Level Gauge

The glass level gauge or sight glass is to liquid level measurement as manometers are t pressure measurement: a very simple and ef  ective technology for  direct visual indication of process le vel. In its simplest form, a level gauge is nothing more than a clear tube through which process li uid may be seen. The following photograph shows a imple example of a sight glass level gauge: 

Bubbler Level Measure ent System

If the process liquid contains suspe ded solids or is chemically corrosive or radioactive, it is desirable to prevent it from coming into direct contact with the level transmitter. In these cases, a bubbler level measurement syste , which utilizes a purge gas, can be used. As shown in Figure, a bubbler tube is i mersed to the bottom of the vessel in which the liquid level is to be measured. A gas (called purge gas) is allowed to pass through the bubbler tube. Consider  that the tank is empty. In this case, the gas will escape freely at the end of the tube and therefore the gas pressure inside the bubbler tube (called back pressure) will be at atmospheric pressure. However, as the liquid level inside the tank incre ses, pressure exerted by the liquid at the base of the tank (and at the opening of th e bubbler tube) increases. The hydrostatic pressure of the liquid in effect acts s a seal, which restricts the escape of, purge gas from the bubbler tube. As a res ult, the gas pressure in the bubbler tube will continue to increase until it just bala nces the hydrostatic pressure (P = SXH) of the liquid. At this point the backpressur  in the bubbler tube is exactly the same as the hydrostatic pressure of the liquid an d it will remain constant until any change in the liquid level occurs. Any excess supply pressure will es ape as bubbles through the liquid.

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Ultrasonic Level Tra nsmitter

Ultrasonic level instruments measu e the distance from the transmitter  (located at some high point) to the urface of a process material located further below. The time-of-light for a sound pulse indicates this distance, and is interpreted by the transmitter  electronics as process level. These transmitters may output a signal co responding either to the fullness of the vessel (fillage) or the amount of em pty space remaining at the top of a vessel (ullage).         

The instrument itself consists of an electronics module containing all the power, comp utation, and signal processing circuits; plus an ultraso ic transducer to send and receive the sound wave s. This transducer  is typically piezoelectric in nature, eing the equivalent of a very high-frequency audio speaker. Besides sound waves, radio frequency and l aser are also used to measure level in a tank.

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Capacitive Level Me surement 

Capacitive level instruments measu re electrical capacitance of a conductive rod inserte vertically into a process vessel. As process level in reases, capacitance increases between the rod an the vessel walls, causing the instrument to output a reater signal. The basic principle behind capacitive level instruments is the capacitance 

 

The amount of capacitance exhibite d between a metal rod inserted into the vessel and he metal walls of  that vessel will vary only with chang es in permittivity (ε), area (A), or distance (d). Since A is constant (the interior surface area of the vessel is fixed, as is the area of the rod once installed), only changes in ε or d can affect the probe's capacitance.

Open Tank Level Measurement  The simplest application is the fluid level in an open tank. Figure shows a typical open t ank level measurement installation using a pr essure capsule level transmitter. If the tank is open to atmosphere, the high-pressure side of the level t ansmitter will be connected to the base of the tank hile the lowpressure side will be vented to atm sphere. In this manner, the level transmitter ac ts as a simple pressure transmitter. We ha e:           Differential pressure ∆        The level transmitter can be calibra ed to output 4 mA when the tank is at 0% level a nd 20 mA when the tank is at 100% level.

Closed Tank Level Mea surement  Should the tank be closed and a ga s or vapors exists on top of the liquid, the gas pressure m ust be compensated for. A change in the gas pressure w ill cause a change in transmitter output. Moreover, the pr essure exerted by the gas phase may be so high that the ydrostatic pressure of  the liquid column becomes insignifi ant. Compensation can be achieved by applying the ga s pressure to both the high and low-pressure sides of the level transmitter. This cover gas pressure is thus used as a back pressure or  reference pressure on the low pres ure side of the DP cell. We have:          

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Differential Pressure ∆        

The effect of the gas pressure is ca ncelled and only the pressure due to the hydrostatic head of the liquid is sensed. When the low-pressure i pulse line is connected directly to the gas phase a ove the liquid level, it is called a dry leg.

Dry Leg System A full dry leg installation with three- alve manifold is shown in Figure. If the gas phase i condensable, condensate will form in the low pres sure impulse line resulting in a column of liquid, which exerts extra pressure on the low-pressure side f the transmitter. A technique to solve this problem is to add a knockout pot/condensing bottle bel w the transmitter in the low pressure side. Periodic draining of the condensate in the knockout pot will ensure that the impulse line is free of liquid.

Wet Leg System In a wet leg system, the low-pressure impulse line is completely filled with liquid (usuall the same liquid as the process) and hence the nam e wet leg. A level transmitter, with the associated th ee-valve manifold, is used in an identical ma ner to the dry leg system. At the top of the low pressure impulse line is a small catch tank. The gas phas e or vapors will condense in the wet leg and the cat h tank. The catch tank, with the inclined interconnecti g line, maintains a constant hydrostatic pressure o the low-pressure side of the level transmitter. This pr  ssure, being a constant, can easily be compensate d for by calibration.

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TEMPERATURE Measurement & control of temperature are possibly the most common operation in process control. PRINCIPLES OF TEMP  RAURE MEASUREMENT  There in general four types of temp rature sensor based on following physical properties, which are temperature dependent: •

• • •

Expansion of substance ith temperature, which produces change to len th, volume & pressure. In this simplest for this is the common in glass thermometer. Changes in electrical resi stance with temperature, used in thermostats and RTD’s. Change in contact potent ial between dissimilar metals with temperature, t hermocouples. Change in radiated energ with temperature optical & radiation pyromete s.

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REISTANCE TEMPERATU RE DETECTERS (RTD): For most metals the chan ge in electrical resistance is directly propor tional to its change in temperature and is linear ove a range of  temperatures. This constan t factor called the temperature coefficient of electric l resistance. The RTD can actually be re garded as a high precision wire wound resistor whose resistance varies with temperature. temperature. Th e Platinum RTD’s are constructed with a resista ce of 100 ohm at 0 Celsius and are often reoffered to as PT-100 sensors.

a)RTD using Wheatstone Bridge To detect the small variations of  resistance of the RTD, a temperatu e transmitter in the form of a Wheatst one bridge is generally used. The circuit compares the RTD value with three known and highly accurate resistor  . In this circuit, when the current flow in the meter is zero (the voltage at point A equals the voltage at point B) the br idge is said to be in null balance. This w uld be the zero or set point on the RTD temperature output. As the RTD temperature increases, the voltage read by the voltmeter increases. If a volt ge transducer replaces the voltmeter, a 4-20 mAm s signal, which is proportional to the temperature ran e being monitored, can be generated. b) Three Wire RTD A problem arises when the RTD is installed some distance away from the transmitter. Since the connecting wires are long, resistance of the wires changes as ambient temperature fluctuates. The variations in wire resistance would introduce an error in the transmitter. To eliminate this problem, a three-wire RTD is used. The connecting wires (w1, w2, w3) are made the same length and therefore the same resistance. The power supply is connected to one e nd of the RTD and the top of the Wheatstone bridge. It can be seen that the resistance of the right leg o the Wheatstone bridge is R1 + R2 + RW2. The resiistance of the left leg of the bridge is R3 + RW3 + RT . Since RW1 = RW2, the result is that the resistan es of the wires cancel and therefore the effect of th e connecting wires is eliminated. Failure Modes: • An open circuit in the RTD or i the wiring between the RTD and the bridge will ca se a high temperature reading. • Loss of power or a short within he RTD will cause a low temperature reading.



THERMOCOUPLE WORKING PRINCIPLE:

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When two dissimilar metals are twis ted together at one end and if this end is heated to emperature T1 & other end are ket at lower temperat re T2, the current will flow around circuit. The current depends on the metals and the temperatures T1 & 2.This phenomenon is known as SEE BACK EFFECT. Device using this effect are called THERMOCOUPLES. The end that is in contact with the process is called the hot or  measurement junction. The one tha t is kept at constant temperature is called cold or refere ce junction. The relationship between total circ it voltage (emf) and the emf at the junctions is: Circuit emf = Measurement emf - Reference emf  If circuit emf and reference emf are known, measurement emf can be calculated and th relative temperature determined. To conver t the emf generated by a thermocouple to the stand rd 4-20 mA signal, a transmitter is needed. Failure Modes: •

•

An open circuit in the thermocouple detector means that there is no path for cu rent flow, thus it will cause a low (off-scale) emperature reading. A short circuit in the thermo couple detector will also cause a low temperature r  ading because it creates a leakage current p ath to the ground and a smaller measured voltage.

When thermocouple is expos ed to atmosphere it will show zero voltage beca se there is no difference of temperature. Thermal Wells The process environment where te perature monitoring is required is often not only hot, but also pressuri ed and possibly chemically corrosive or radioactive. To facilitate removal of the temperature sensors (RTD and TC), for examina tion or replacement and to provide mechanical protection, the sensors are usually mounted inside thermal wells. Thermocouple types



Bimetallic Thermometer  A bimetallic strip is constructed by bonding two metals with different coefficien s of thermal expansion. If heat is applied to o ne end of the strip, the metal with the higher  coefficient of  expansion will expand more readily than the lower  one. As a result, the whole metalli strip will bend in the direction of the metal ith the lower  coefficient. One main advantage o f the bimetallic

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strip is that it can be used to opera te over a range of temperatures when the strip is f ashioned into a coil (for larger swing) and placed on an adjustable pivot. Another common confi uration of the bimetallic strip is coiled in a helix t increase the swing or displacement similar to the coil above. In this shape, the strip is more rugged and less subject to vibration. 

Thermostat Like the RTD, the thermistor is also a temperature sensitive resistor. Of the major categories of  sensors, the thermistor exhibits by far the largest parameter  change with temperature. Thermistors are generally compos d of semiconductor materials. Although positive temperature coef  icient units are available, most thermistors have a negative temperature coefficient (TC):i.e. their resistance decreases with increasing temperature. The negative TC can be as large a several percent per degree Celsius, allowing the thermistor circ uit to detect minute changes in temperature which could not be observed with an RTD or  thermocouple circuit. The price we pay for this increased sensitivity is loss of linearity. The thermistor is an extremely non-linear device.



PYROMETERS

Pyrometer, an instrument for meas uring temperature. Two common types of pyrometers are the optical pyrometer and the radiation pyrome ter. A heated object gives off electromagnetic radia ion. If the object is sufficiently hot, it will give off visible light, ranging from dull red to blue-white. Even if t e object is not hot enough to glow, however, it gives o f infrared radiation. An optical pyrometer determines th temperature of a very hot object by the color of the visible light it gives off. The color of the light can e determined by comparing it with the color of an electrically heated metal wire. In one type of pyromete r , the temperature of the wire is varied by varying th strength of the current until the operator of the inst ument determines that the color of the wire matche the color of the object. A dial, operated by the curre nt that heats the wire, indicates the temperature. A radiation pyrometer determines t e temperature of an object from the radiation (infrar ed and, if present, visible light) given off by the object. The radiation is directed at a heat-sensitive elemen such as a thermocouple, a device that produc es an electric current when part of it is heated. The otter the object, the more current is generated by th thermocouple. The current operates a dial that ind icates temperature.

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VIBRATIO & SPEED MONITO ING TOPICS 



Measuring Metho s.



Study of Different Monitoring Equipment.



(Bentley Nevada-3 500 & 7200)



Study of Loop Dra wings & Installations at FFC-MM p ant.

CO-ORDINATOR ENGR.UMAIR AKBAR 

INTRODUCTION TO VIBRATION MONITORING S STEM Most of us are familiar with vibratio ; a vibrating object moves to and fro, back and forth. A vibrating object oscillates. Vibration amplitude may be measur ed as a displacement, a velocity, or acceleration. Vi ration amplitude measurements may either be relati e, or absolute. MEASUREMENT OF VI  ERTION  Unlike most process measurement , the measurement of a rotating machine’s vibration is primarily for the benefit of the process equipment ra ther than the process itself. Vibration monitoring on a compressor, for 

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instance may very well be useful in extending the operating life of the compressor, but little to the benefit to the control of the process. PARAMETERS TO MEA SURE  

Radial Vibration

Shaft dynamic motion or casing vib ation which is measured in a direction perpendicula r to the shaft axis, often called lateral vibration. 

Thrust Position

The average position, or change in position, of a rotor in the axial direction with respect to some fixed reference. Typically, the reference i s the thrust bearing support structure or other casin member to which the probe is mounted. The probe m ay observe the thrust collar directly or some other integral, axial shaft surface, as long as it is within about 305 mm (12 inches) of the thrust bearing. Vibration measuremen technique 

Non-contact Method a) Eddy current probe/ proxi mity probe (displacement transducer)



Contact method

b) Velocity probe (LVDT: Velocit transducer) c) Acceleration probe (accelero

eter: piezoelectric device

PROXIMITY PROBE  Proximity transducer converts the mechanical vibrations to an electrical signal that is proportional to displacement of vibration. The pro imity transducer is used to directly measure rotor  movement in both axial and radial planes. Vibration measurement units at the output of the proximitor are expressed in mils or  micrometer peak to peak. The standard Bently N vada Corporation proximity transducer scale fac or is 200mV/mil (7.87V/mm) for the 8mm 3300 syst m. This system consists of three indivi ual parts:   

Probe Extension Cable Proximity Driver Driver)

(Oscillator

Demodulator 

The proximity driver is an electronic device that performs two basic functions:

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• •

Generates the radio freque cy (RF) signals using an oscillator circuit Conditions the RF signal to extract usable data using demodulator circuit

Once proximitor power up, it will ge nerate a RF signal at specific frequency. This frequ ency is dependent on the of the probe coil and capaci ance value of extension and probe cable. The RF ignal emitted from the probe coil, which creates a R field around the probe tip. The RF field is prop rtional to the coil diameter in the probe tip and input oltage to the proximitor. When conductive material is prese nt in RF field, eddy current flows in the surface o that material. RF amplitude is at maximum when di tance between probe and material is minimum a d vice versa. The rapid movement of the target caus s the RF signal to modulate. The demodulator circ uit deals with slow or fast changing amplitude in the sa me way.

FAMILIZATION TO BEN TLY NEVADA Bentley Nevada thrust & vibration m onitoring system was originally manufacture by ben tly Nevada & is in use in large number large industrial turbine installation around the world. The 7200 Series monitoring system was BENTLY NEVADA’S full-featured "flagship" m nitoring system from 1975 until the introduction of t e 3300 Series System in 1989. The system has no reached “phase 5” obsolescence which means it is o longer supported by the manufacturer. However, Paramount Electronics will be able to continue o repair these units for many years to come. The same is true for the 1800, 2201 , 5000, 7000, 9000, 11000 Series Monitor Systems

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HONEY  ELL ESD SYSTEM

TOPICS 



Familiarization with Honeywell FSC PLC.



Troubleshooting PL CO-ORDINATOR ENGR   NGR . SYED SYED UMAIR HUSSAIN E E   NGR   

PR OGRAMMABLE LOGIC CONTROLLER  Programmable logic controllers (PL Cs) are the control hubs for a wide variety of auto ated systems and processes. Programmable logic co ntrollers are used extensively in diverse industrial a plications ranging from machining to automated assembly. They were designed to replace the necessa ry sequential relay circuits for machine control. PLCs have been gaining popularity on the factory floor  and will probably remain predominant for some time to come. Other areas of application of PLCs are in ustrial automation and control of industrial equipment. Most of this is because of the advantages they offe :   

Cost effective & Flexible Computational abilities Troubleshooting aids

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

Reliable components

One may very correctly ask that w y not to use a personal computer for these tasks in place a specialized PLC. The answer is ver  simple; PLC      

Is intended for use on factory floors & in harsh environments Is more durable & Less ex ensive Can be placed in remote or  rugged industrial locations Can perform at a high level for many years. Can withstand shock, vibra ion, humidity, EMI, RFI, dust, mist, and splash Can also be used for compiling data coming from many sources and uploading on a computer  network STANDARD PLC VS IN  USTRIAL SAFETY PLC 

There are three fundamental differences between a safety PLC and a standard PLC in erms of  architecture, inputs, and outputs. 

ARCHITECTURE

A PLC has one microprocessor w hich executes the program, a Flash area which st ores the program, RAM for making calculations, port for communications and I/O to detect and contr  l the machine. In contrast, a safety PLC has redund nt microprocessors, Flash and RAM that are conti nuously monitored by a watchdog circuit and a synchr  nous detection circuit. 

INPUTS

Standard PLC inputs provide no i nternal means for testing the functionality of the input circuitry. By contrast, Safety P LCs has an in ernal ‘output’ circuit associated with each input f or the purpose of  ‘exercising’ the input circuitry. Input s are driven both high and low for very short cycle during runtime to verify their functionality. 

OUTPUTS

The PLC has one output switching evice, whereas a safety PLC digital output logic cir cuit contains a test point after each of two safety switc es located behind the output driver and a third test point downstream of the output driver. E ach of the two safety switches is controlled by a unique micropr  cessor. If a failure is detected at either of the two safe ty switches due to switch or microprocessor failure, or at the test point downstream from the output driver, the operating system of a safety PLC will automatically acknowledge system failure. At that time, a safe y PLC will default to a known state on its own, fa ilitating an orderly equipment shutdown. EMERGENCY SHUTDO WN SYSTEM  Emergency shut-down system (E designed to respond to conditions i could eventually give rise to a h hazardous consequences or preve

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D) or Safety Instrumented Systems (SIS) is def ined as a system the plant which may be hazardous in them or, if n action was taken, zard. The ESD must generate the correct outputs to mitigate the t the hazard.

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Safety instrumented systems are s eparate and independent from regular distributed c ontrol systems but are composed of similar elemen ts, including sensors, logic solvers, actuators and support systems. Failure and/or spurious trips could r esult in expensive procedural and downtime conse uences. Thus, the reliability on safety and availability, need to be tested periodically before the next maintenance, but not interrupt the operation. Due to the ritical nature of such systems ESD system are typi cally composed of  sensors, logic solvers and final co ntrol elements. The actuated shutdown valve is e xpected to remain static in one position for a long p riod of time and reliably operate only when an e ergency situation arises, i.e. to spring into safe mode position. Emergency Shutdown

ystem at FFC 

The ESD system installed at FFC plant is manufactured by Honeywell which they c alled as Fail Safe Control (FSC) FSC) system. This system satisfies SIL3 standard. The Honeywell Fail Safe ontrol system is a highly reliable, high-integrity safety system for safety-critical control applications. As art of Honeywell's Total Plant Solution (TPS) syste , integrated into Plant Scale, or in stand-alone ap lications, the FSC system forms the basis for functio al safety, thus providing protection of persons, pl nt equipment and the environment combined with opti mum availability for plant operation. HONE   WEL  WELL L FA IL-S IL-SAFE AFE CON CONTROL TROL

(FSC) (FS C)

BASIC ARCHITECTUR  The basic architecture of the FSC s ystem. Two major system parts can be distinguishe : the Central Part, and The Input/output interfaces. • •

Basic Architecture of FSC 

Central Part The Central Part (CP) is the heart f the FSC system. It is a modular microprocessor  system specifically designed for safety-critical applicati ons which can be tailored to the needs of any appllication. The most important Central Part modules are: a) Control Processor: reads t he process inputs and executes the control program as created by the user in graphical Functional Logi c Diagrams (FLDs). The results of the control program are then transmitted to the output interfaces.

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b) Watchdog: monitors the o peration and the operating conditions of the Cont ol Processor. The operation of the processor i s monitored by verifying if the processor executes a ll its tasks within a pre-calculated time frame, which depends on the configuration. The op erating conditions monitored include the data integrity of the processor memory and the voltage r ange of the supply power (both under voltage and overvoltage). If the Watchdog detects a fault iin the operation of  the Control Processor or  its operating conditions, it will deactivate the safety-critical output interfaces of the FSC syste m, independent of the Control Processor status. c) Communication Process or: allows the FSC system to exchange infor  ation with other  computer equipment via s rial communication links (uses RS232, RS485 pro tocols). Dedicated modules are also available which provide communication capabilities with othe systems. 

Input/output Interfaces The FSC system provides a wide range of digital and analog input and output int rfaces, each with different characteristics to meet the demands of a wide range of field equipment.

There are two plant control syste ms: 1) DISTRIBUTED CONTROL SYS EM 2) EMERGENCY SHUT DOWN SY TEM Distributed control system works u der normal process conditions & ESD system brin s the plant in safe shutdown conditions in case the pr  cess parameters go beyond their control limits.

TYPICAL LOOP OF ESD:

PLC PROGRAMMING

Functional Logic Diagr  m (FLD)

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The FSC system's safety-critical co ntrol functions are determined by the safety functions assigned to the system for the specific application. The FSC user software supports the design of the ontrol program by the user. The control functions ar  defined via graphical Functional Logic Diagrams (FLD). Functional Logic Diagram, which demonstrate s the flexibility of the programming technique used in FSC Navigator. FLD programming includes the facil ity of encapsulation or modularization using functio blocks, which are comparable to subroutines in high-llevel programming languages. This allows function blocks to be used to create complex functions. Functi n blocks only need to be tested once and can then be reused without the need for testing them again.

Functional Logic Diagram An FLD is split into four main areas: the information area (bottom) the input area (left), the control function area (cente ) the output area (right) The FLD control function area, w ich is the central area of the FLD, contains the act al implementation of the control function. The function is realized by interconnecting predefined symbol s which provide a variety of functions including logic al, numerical and time-related functions. Apart from these standard functions, user-definable blocks are supported: Function Blocks — standard FL Ds for repetitive use within the control program Equation Blocks — for tabular definition of complex functions, e.g. non-linear equati ons • • • •

• •

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OKOGAWA DCS  TOPICS 



Familiarization with DCS hardware, software & architecture.



Developing control lgorithms



Training & simulati n using test function(troubleshooting CO-ORDINATOR ENGR.SYED UMAIR HUSSAIN

Dist  ibuted control system A distributed control system (DCS) r efers efers to a control system usually of a manufacturin system, process or any kind of dynamic system, in w hich the controller elements are not central in locati n (like the brain) but are distributed throughout the s stem with each component sub-system controlled y one or more controllers. The entire system of co trollers is connected by networks for communication and monitoring. DCS is a very broad term used in a variety of industries, to monitor  and control distributed equipment. A Distributed Control System is a part of manufacturing industry. DCS is used in industrial and civil engineering applications to monitor and control distributed equipment with remote human intervention. A DCS typically uses custom designed processors as controllers and uses both proprietary interconnections and communications protocol for  communication. Input and output modules form component parts of t e DCS. The processor receives information from in ut modules and sends information to output module s. The input modules receive information from input instruments in the process (or field) and transmit instr  ctions to the output instruments in the field. Compu er buses or  electrical buses connect the proces sor and modules through multiplexer or de-multiplex ers. Buses also

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connect the distributed controllers ith the central controller and DCS typically contain one or more computers for control and mostly us e both propriety interconnections and protocols Dist ributed Control System (DCCS) in general provides : for communication. YOKOGAWA DCS ARC  ITECTURE  Presently, FFC is using DCS syste manufactured by Yokogawa a Japanese company. G eneral architecture of  Yokogawa CS3000 is described as follows. It consists of the following main parts: 1. FCS cabinets 2. Human interface machines (HIM) 3. Engineering work station (EWS) All transmitters installed all over the plant sent their information in the form of current signal to the DCS system. All the field wires terminate at the nest which c ntains the I/O cards. Four of  the nest then connects to the one n ode interface unit (NIU). These nodes then connect to the c ntral processing unit called Field Control Unit (FCU) through RI /O buses. Vnet cables provide interface between FCS cabiinets and to the Human Interface Unit. HMI are also connec ted to each other over  Ethernet and also to Engineering w rk station (EWS). The following completely illustrate the whole systems and connections between different parts of it. FIELD CONTROL STATION (FCS) The FCS controls the plant. By th difference of used I/O modules, there are two models of the FCS; namely the FCS for FIO and the F S for RIO. In addition to the above models, there is the Compact type FCS. FCS for RIO This FCS uses the Remote I/O ( RIO) modules, which have many installation bas es and M4 screw terminals to connect signal cables. According to the application capacity, there are t e standard model and the enhanced model.

Human Interface Statio (HIS) The HIS is mainly used for oper  tion and monitoring – it displays process variables, control param eters, and alarms necessary for  users to quickly grasp the oper  ting status of the plant. It also

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incorporates open interfaces so t hat supervisory computers can access trend dat a messages, and process data. • Console Type HIS This is a new console type human i nterface station, at which a general purpose PC is i stalled. There are two types of console type HISs: on is enclosed display style, the appearance of which is usual style, and another is open display style, the c nfiguration of which is selectable. • Desktop Type HIS This HIS uses a general purpose P

CON ROL VALVES & PSV's TOPICS 

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

Types and Terminology’s.



Testing and calibrat  on procedures.



Control Valves posit  oned, actuators & accessories.

CO-ORDINATOR

E   SYED SYED UMAIR HUSSAIN E NGR.  

Control Valves Control valves are valves used to c ontrol conditions such as flow, pressure, temperature, and liquid level by fully or partially opening or closi g in response to signals received from controllers t at compare a "set point" to a "process variable" whose value is provided by sensors that monitor  changes in such conditions. The opening or closing of control valves is done by means of electrical, hydraulic or pneumatic systems. Positioners are used to control the opening or closi ng of the actuator based on Electric, or Pneumatic Signals.. These control signals, traditionally based on 3-15psi (0.2- 1.0bar), more common now are 4-20mA signals for industry. Types of Control Valve Bodies 1. Gate Valve A Gate Valve is mainly use for on/o f control. It opens by lifting a round or rectangu lar  gate/wedge out of the path of the fl id. The distinct feature of a gate valve is the sealing surfaces b tween the gate and seats are planar. The gate faces can form a wedge shape or they can be parallel. Gate valves are someti es used for regulating flow, but many are not suited for th t purpose, having been designed to be fully opened or clos d. When fully open, the typical gate valve has no obstruction in the flow path, resulting in very low friction loss . Gate valves are characterized as ha ving either a rising or a nonrising stem. Rising stem provide a visual indication of valve position. Nonrisi ng stems are used where vertical space is limited o underground. 2. Globe Valve Globe valves are named for their s pherical body shape. The two halves of the valve b ody are separated by an internal baffle which has an o pening forming a seat onto which a movable disc ca n be screwed in to close (or shut) the valve. In globe valves, the disc is connected to a stem which is perated by screw action. When a globe valve is ma ually operated, the stem is turned by a hand whe el. Although globe

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valves in the past had the spherica l bodies which gave them their name, many mode rn globe valves do not have much of a spherical shap , but the term globe valve is still often used for val es that have such an internal mechanism. Globe valves are used for applicati ns requiring throttling and frequent operation. 3. Butterfly Valve A butterfly valve is a particular t pe of valve that uses either a circular vane or a disc as the shut -off mechanism. Butterfly valves have a quick opening/closing qua rter-turn mechanism that is used to control the flow of liquid through a iping system. They typically pivot on axes perpendicular to the directio n of flow inside the flow chamber. Compared with ball valves, butterfl y valves do not have pockets to trap fluids when the valve is in the c losed position. Butterfly valves are frequently used as throttling devic es, controlling the levels of flow in various positions: entirely closed, ntirely open or partially open. They can control various substances of  air, liquid or solid currents and are situated on a spindle that allows for  flow in a single direction. 4. Ball Valve A ball valve (like the butterfly valv , one of a family of valves called quarter turn valv es) is a valve that opens by turning a handle attache d to a ball inside the valve. The ball has a hole, o r port, through the middle so that when the port is in line with both ends of the valve, flow will occur. hen the valve is closed, the hole is perpendicular to the ends of the valve, and flow is blocked. The han dle position lets you "see" the valve’sposition. Ball valves are durable and u ually work to achieve perfect shutoff even after  ears of disuse. They are therefore an excellent ch oice for shutoff  applications (and are often pref  rred to globe valves and gate valves for this pur pose). They do not offer the fine control that may e necessary in throttling applications but are som times used for  this purpose.

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Ball Valve

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Solenoid Operated Valve (SOV) Solenoid valves are electrically oper  ted devices that control the flow of liquids. Solenoid valves are electromechanical devices that use a wire coil and a movable plunger, called a solenoid, to control a articular valve. The solenoid controls the valve during eith er the open or closed positions. Thus, these kinds of va lves do not regulate flow. They are used for the remote co ntrol of valves for directional control of liquids. Solen id valves have two main parts: the solenoid and the valve. After the coil receives a current, the actuating magnetic field is created. The magnetic field acts upon the plung r, resulting in the actuation of the valve, either op ning or closing it. There are two general types of solenoi d valves: direct-acting and pilot-operated. Direct-acting a plunger that is in direct contact with the primary opening in the body. This plunger is used t orifice. The pilot-operated solenoid va ve works with a diaphragm rather than a plunger. This v  pressure to control the flow of fluids. he air-venting valve is opened to allow the pressure to the fluids to flow through.

olenoid valves have open and close the lve uses differential equalize and permit

Check Valves/Non-return Valves ( RV) Check valves, also referred to as "no -return" or "one-way directional" valves, are very simp le valves that allow fluid, air or gas to flow in only one dire ction. When the fluid moves in the pre-determined direct ion, the valve opens. Any backflow is prevented by the mov able portion of the valve. A swinging disc, ball, plunger  or poppet moves out of the way of the original flow. Sin e these devices are slightly larger than the through h ole, the pressure of   backflow will cause them to tightl y seal, preventing reversal of flow. Gravity or a spring assists in the closing of the valve.

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Positioner Positioner is a device used to position a valve with regard to a signal. The positioner  compares the input signal (3-15 psi) wi th a mechanical feedback link from the actuator. then produces the force necessary to move the actuator output until the mechanical output position feedback corresponds ith the pneumatic signal value. There are three modes of a positioned that it can be set: • Fail to close • Fail to open • Last position

It

Regulator A regulator is a device that regulates the supply of air from the supply line to some device, e.g from 7 kg to 1.4kg.Regulato r has two main parts •

•

Regulation Part: This inclu es a spring, compressed valve, diaphragm and feedback system needed for re gulation.

the

Filter: This is the filtering par t on the input used to filter any dust particles or moisture in the air.

Pressure Safety Valve (PSV) A pressure safety valve is a valve valve mechanism for the automatic release of a substance fro m a boiler, pressure vessel, or other system when the press re or temperature exceeds preset limits. It is a mechanic l safety and last line of protection against disaster in case  both DCS and ESD system fails. These are used to pr otect vessels, tanks, compressors, pumps, etc from over pr  ssure and from rupturing by bleeding the extra pressur  on the atmosphere. Its simplest example is the weight PSV on the pressure cooker used in homes for cooking.

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AN INTERNSHIP At FAUJI  FERTILIZER COMPANY 

ersonal Feedback  This six week internship at producti n unit FFC MM developed an understanding of ure fertilizer  production especially to the field ins trumentation and control technology. Experience an d exposure was not only limited to process flow but as widened to operating logics, process control & roduction techniques and problem handling a d troubleshooting. The plant division and design, man gement and operation enhanced the concept and p erspective about safe and smooth process. Literature review from TTC library, tudy of technical data and manuals of different equi pments, discussion with engineers and tech ical staff and visit to plant site added a sound knowledge. The cooperative coordination of manag ment and staff raised the morale in the journey of Lifelong learning period. Although, the internship program w s good but I think there are some areas which can till be improved. Schedule for entire internship shoul d be planned on daily basis. Office and work enviro ment exposure would help interns to build a profes ional attitude and eliminate the feeling of being left alone. Frequent plant visits can make the Internship Program more Intriguing and help the interns to explore industry. Library at Technical Training Cente should be equipped with a computer section where Interns should be provided with internet facility.

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Dawood University of Engineering &

echnology