REPORT ONINDUSTRIAL TRAINING

ATNATIONAL FERTILIZERS

LIMITED(AN ISO-14001 UNIT)

BATHINDA

SUBMITTED BY: KAMA

LPREET KAUR UNI. ROLL

NO.: 11402039 E.C.E

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(10 june 2016-15 july 2016) PREFACE

As per the requirements of B-Tech degree course in electronics and communication engineering vocational training has to be undertaken after second year. To fulfill this requirement I took my training from NFL, Bathinda. During this period everything that I learned and studied have:

The report contains all the necessary information of all the plants viz. Ammonia plant, C.P.P., Urea plant, S.G.P. It also contains an overview of the NFL. The information has been prepared to best of data available at that my knowledge and time.

It is pleasure to face the industrial life that helped me to convert my theoretical concepts into practical knowledge.

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ACKNOWLEDGEMENT

I have undergone training at NATIONAL FERTILIZERS LIMITED, BATHINDA. During this training I have learnt a lot for which I pay my heartiest gratitude to all the staff members of NFL Bathinda who helped me in all respects in fulfilling my cherished desired of getting a successful industrial training in an esteemed organization.

I am very grateful to Mr. D.K.BORA (Manager-HRD cum Head of training Department) who deputed me with senior engineers and provided me sound knowledge of various electronics equipments and process details. I pay my sincere thanks to all the supervisors and the other official at the site for providing me complete details of their respective plants..I am very thankful to Mr.SUNIL ARORA (Head of the Electronics and communication Engineering Department) and all the professors and lecturers of Electronics and communication Engineering Department who guided me time to time �

KAMALPREET KAUR

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DEVELOPMENT HISTORY OF THE

ORGANIZATION The rise in fertilizers consumption in India has been quite phenomenal during the past three decades. To meet the rise in consumption of fertilizer , creation of additional capacity was also planned. The change in worldwide energy concept and the rise in oil prices in 1973 forced India to broad base its nitrogenous production by adopting new and sophisticated technology, which could use cheaper sources of raw materials.

It is in this context that National Fertilizers Ltd. (A public sector undertaking) was conceived to plan and implement two modern large capacity single steam nitrogenous fertilizer plants in the predominant fertilizer consuming areas of northern states in India to cater to the ever-increasing demand for fertilizer in the region.

The company was formed and registered on 23rd

August, 1974 to set up two nitrogenous fertilizer plants each with a capacity of 5.115 lac tones per annum of urea at Bathinda and Panipat.

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BATHINDA was basically selected as one of the sites for this fuel oil based plant from the consumption point of view, since Punjab with its well organized agriculture sector, has insatiable demand for fertilizer. This combined with excellent facilities of transport, made behind an excellent choice for this grass root plant.

NFL CORPORATE OBJECTIVE : In terms of memorandum of Association, NFL was setup to manufacture and market Chemical fertilizer, heavy water, other chemical and by products as well as to provide the allies services.

INDUSTRY PROFILE : The Agriculture sector is the backbone of our country. It is the most potent factor of change that could transform the Indian economy Worlds strongest economy.The rise in fertilizers� consumption India has been quite phenomenal during past three decades. To meet the rise in consumption of fertilizers creation of additional capacity was also planned. The change in the world wide energy concepts and rise in oil prices in 1973 forced India to increase its nitrogenous production by doping new and sophisticated technology which could use cheaper sources of new raw material.

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National Fertilizers Limited (NFL) Indias first public� sector fertilizer company was setup 23rd August 1974 to increase the productivity of agriculture sector. On foundation of NFL, two nitrogenous fertilizers plant each with a capacity of 5.11 lakhMT per annum at Bathinda and Panipat to revolutionalize and making the era of change and excellence in Indian Agriculture sector. Both of them were commissioned in 1979. NFL organizes a long way there after and has emerged as one of the fastest growing company in public sector with producing the major product as urea to make healthier the agriculture and Indian economy. It is the second largest company in the country with an installed production capacity of urea is 32.31 lakhT/annum within 32 years. NFL also producing 100T of bio-fertilizer in its Indoor plant.

PRESENT SCENARIO : NFL has performed well during the initial six months of the current financial year. The cumulative production of Urea during this period was 17.61 lakhT, which is 109% of the installed capacity. Company has sold 17.77 lakhT of urea during Kharif 2005-06 against the previous best of 16.51 lakhT. Presently, the company has the lowest urea inventory compared to the last five years. In the first quarter of 2005-06 against the previous best of 16.51 lakhT. Presently, the company has the lowest urea inventory compared to the last five years. In the first quarter of 2005-06 companys produced 8.46 lakhT of urea recording a capacity of� utilization of 104.8%. With this, the company recorded a profit before tax of Rs.22.45 Crores. The demand during Kharif 2005 has lead to a sale of 3.07 lakhT of urea.

PAST PERFORMANCE: In the year 2004-05 the company has achieved superb production performance by producing 34.72lakhT of urea recording a capacity utilization of 106.2%. All the plants of the company have recorded more than 10% capacity utilization. There is 89% of increase in companys net profit. The company� has also done well in production of Bio-fertilizers by producing 124T this year against the installed capacity of 100T. The sales of industrial products also touched new height at

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Rs.114.54Crores compared to 105.08Crores last year. Company made record dispatches of 35.24lakhT of urea

FUTURE SCENARIO: Neem coated urea has brought good results for the company. After this success company developed a new product that is Zincated urea. The company developed three grades of Zincated urea containing 0.5%, 1.0% and 2% have started its trial production at Nangal unit. Furthering its innovation plans, the company has also undertaken a project for developing the manufacturing technique of sulphur-coated urea.

F.Y 2004-05 (NFL):

Production 34.32LakhT/Annum Sales of urea 34.73LakhT/Annum Net profit 160.88 million Rs. Capacity utilization 106.2%

PRODUCTS OF NFL:

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National Fertilizer is producing Kisan Urea, Kisan Khad� and Ankur on commercial scale. NFL is also marketing number� of industrial products as by-products during the formation of Kisan Urea, Kisan Khad and Ankur in its plant itself.� �

FERTILIZERS PRODUCTS:

Kisan Urea Kisan Khad

BY-PRODUCTS:

Nitric Acid(HNO3) Sulphur (S) Anhydrous Ammonia (NH3) Ammonium Nitrate (NH4NO3) Methonal (CH3OH) Nitrogen (N2) Carbon Dioxide (CO2) Sodium Nitrate Oxygen (O2) Carbon (C) from slurry

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REQUIREMENTS OF RAW MATERIAL/INPUTS

FUEL OIL/LHLS 850 MT/DAY:

Coal 1680 MT/Day Water 13 MGD Power 28 MW

PROJECTS BENEFITS:�

Increased Food Output Employment to nearly 6000 persons Both Central and State Government has been benefited by

way of excise duties and other local taxes on raw materials and other products.

Scope for marketing by-products such as Sulphur, CO2, Nitrogen, Oxygen, Carbon etc.

SALIENT FEATURES OF THE PROJECT:

Annual consumption of fuel oil (raw material) 260,000 tones

Annual consumption of coal 320,000 tones Water requirement 4125 million gallons Power requirement 35 MVA Annual nitrogen capacity 236,000 tones Total direct employment 1200 Nos. Expected indirect employment 6000 Nos. Estimated cost of project 188.48 Cr Foreign exchange savings 120 Cr

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BASIC PROCESS:

Urea is in many ways the most convenient form for fixed nitrogen. It has the highest nitrogen content available in solid fertilizer (46%). Urea can be considered the amide of carbonic acid (NHCOOH) or the diamides of carbonic acid {CO(OH)}. At room temperature urea is color less, odourless and tasteless. In the year heating ammonia carbonate in a sealed tube reduced 1870 urea.

Commercially urea is produced by the direct de-hydration of ammoinium carbonate (NHCOONH) at elevated temperature and pressure. Ammonium carbonate is obtained by direct reaction of ammonia and carbon dioxide. The two reactions are usually carried out simultaneously in high pressure reactor. Recently urea has been used commercial as castle feed supplement. Urea is classified as the non-toxic compound, when urea is dissolved in water, it hydrolyses very slowly to ammonium carbonate and eventually decomposes to ammonia and carbon dioxide. This reaction is the basis for the use of urea as fertilizer. The process sequence starts with the partial oxidation of fuel oil in standard shell reactor at 55-kg/cm² pressure followed by waste heat recovery, steam generation and carbon removal. The raw then goes to sulphur removal where cold methanol at about -20ºC to -35ºC washes both the organic and inorganic sulphur. Sulphur free gas is then led to the high temperature shift conversion section where carbon monoxide is converted into carbon dioxide and hydrogen. Again cold methanol at 20ºC to -60ºC is given to remove carbon dioxide. The carbon dioxide and sulphur compounds are removed from the rich methanol solution, which is regenerated and recycled. The gas is then passed to the nitrogen wash cold box where liquid nitrogen wash removes the remaining carbon monoxide and other impurities. Further nitrogen gas is added to adjust the synthesis gas composition. The gas then goes to the centrifugal compressor and is delivered to the synthesis reactor at the pressure of the 231 atm. The daily output of ammonia is 900

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tones. Ammonia is fed to the urea plant, where it is reacted with the recovered carbon dioxide at a pressure of about 250 atm. The urea solution is separated at the top of a prilling tower and collected at the bottom in form of small particles, which is sent to bagging plant and dispatched. The carbonate is decomposed and recycled back to the urea reactor.

INSTRUMENTS USED IN THE FIELD FOR MEASUREMENT

TRANSDUCERS:

It is a device which converts one form of energy into another form i.e. the given non-electrical energy is converted into an electrical energy.

TRANSDUCERS USED FOR PRESSURE MEASUREMENTS:

Absolute pressure sensor

This sensor measures the pressure relative to perfect vacuum

Gauge pressure sensor

This sensor measures the pressure relative to atmospheric pressure. E.g tire pressure gauge.

Vacuum pressure sensor

It measures pressures below atmospheric pressure, showing the difference between that low pressure and atmospheric pressure (i.e. negative gauge pressure), but it may also be used to describe a sensor that measures low pressure relative to perfect vacuum (i.e. absolute pressure).

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Differential pressure sensor

This sensor measures the difference between two pressures, one connected to each side of the sensor.

TRANSDUCERS USED FOR LEVEL MEASUREMENTS:

Non-Contact Ultrasonic Sensors

These sensors incorporate an analog signal processor, a microprocessor, binary coded decimal (BCD) range switches, and an output driver circuit.

Contact Ultrasonic Sensors

A low-energy ultrasonic device within these sensors measures liquid level at a certain point.

Capacitance Level Sensors

Like ultrasonic sensors, capacitance sensors can handle point or continuous level measurement. They use a probe to monitor liquid level changes.

TRANSDUCERS USED FOR FLOW MEASUREMENTS:

Turbine flow meter

The turbine flow meter (better described as an axial turbine) translates the mechanical action of the turbine rotating in the liquid flow around an axis into a user-readable rate of flow (gpm, lpm, etc.)

Thermal mass flow meters

Thermal mass flow meters generally use combinations of heated elements and temperature sensors to measure the difference between static and flowing heat transfer to a fluid.

TRANSDUCERS USED FOR TEMPERATURE

MEASUREMENTS:

Thermocouple

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A thermocouple is a junction formed from two dissimilar metals.  Actually, it is a pair of junctions.  One at a reference temperature (like 0 oC) and the other junction at the temperature to be measured.  A temperature difference will cause a voltage to be developed that is temperature dependent.

Resistance temperature detectors ( RTD s)

Resistance thermometers, also called resistance temperature detectors (RTDs), are sensors used to measure temperature by correlating the resistance of the RTD element with temperature. Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core. The RTD element is made from a pure material which has a predictable change in resistance as the temperature changes. It is this predictable change that is used to determine temperature.

CONTENTS

1. AMMONIA PLANT

2. UREA PLANT

3. STEAM GENERATION PLANT (S.G.P)

4. CAPTIVE POWER PLANT (C.P.P)

5. OFFSITE

6. CONCLUSION

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AMMONIA

PLANT14

Ammonia plant is congregation of several processes working in co-ordination with each other.

SECTION WISE DESCRIPTION:

1. AIR SEPARATION UNIT (A.S.U):

Introduction:

A.S.U and N.W.U have been supplied by m/s HITACHI of JAPAN for Bathinda fertilizer project.

TOTAL AIR SUPPLIED 1,40,000 Nm³/hr

PRESSURE 7 kg/cm²

OXYGEN PRODUCED 26,000 Nm³/hr

NITROGEN PRODUCED 58,000 Nm³/hr

A.S.U can be operated when N.W.U is under shut down. Expansion turbine provides the necessary refrigeration for

A.S.U & N.W.U with both running during cooling down of the unit & one running during normal operation.

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PROCESS: Feed air cooled in pre-coolers from 45ºC to 40ºC & further cooled to 5ºC in chiller. Air is then passed through air dryers. After dryers, it enters the cool box, some of the feed is even utilized in expansion turbine. Feed air then enters the rectification section, which consists of upper, lower column & main condenser in between. The lower column consists of Al containing sieve trays and a bubble cap tray, located at bottom. O2 with about 40% purity is obtained in lower column and gaseous and liquified N2 are obtained at the top & bottom of lower column. The liquified air withdrawn from the bottom of lower column passes through one of the alternately operating HC absorbers,finally liquid air filters to remove contamination of HCs. Then it is super cooled with waste N2 from upper column in liquid air super cooler before being expanded to pressure of upper column. The impure N2 withdrawn from middle of lower column is fed to the upper column whereas the

liquid N2 withdrawn from the top of the lower column is supercooled in liq. N2 supercooler through an expansion valve. The rectification process continues & liquified O2 of atleast 98% purity is obtained in the main condensor which is evaporated there to form the pure O2 product & is withdrawn from the bottom of upper column. Pure N2 is withdrawn from the top of the upper column with purity of maximum 8 ppm. Apart of liq. O2 is continuously circulated by one of two alternately operating liq. O2 pump from condensor to circulating absorbers & liq. O2 filters to remove remaining traces of HCs. The waste N2 is withdrawn from middle part of the upper column & warmed in liq. air supercoolers & air heat exchanger & extracted from cold box.

Cold required for liquification can be produced by either method:

a.) FREE EXPANSION : the gas is expanded at constant enthalpy in an expansion valve. This method requires a h.p. to produce a large qty. of cold.

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b.) EXPANSION WITH EXTERNAL WORK: in this process the gas is expanded at constant entropy.This is a better & cheaper expansion.

BEWARE:

ACETYLENE & HCs can prove explosive, so stopping & warming limits are specified.

HYDROCARBON SOLUBILITY EXPLOSIVE LIMIT

Methane in any proportion 5.4% Ethane 2.5% 4.1% Ethylene 3% 2.9% Propane 6% 2.3%

2.GASIFICATION: It is the process in which partial oxidation of HCs takes place in the presence of oxygen and steam. The reaction involved are :

CnHm + n/2 O2 ------------------------ nCO + m/2 H2 CnHm + nH2O ------------------------ nCO + (m+n) H2 Partial oxidation is preferred to complete oxidation because it is due to

partial oxidation that we get more amount of hydrogen, which is very expensive and desired gas. If complete oxidation been done, we get water and carbon dioxide

which are undesired products and even our motive of getting nitrogen is not achieved.

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This process of gasification can be divided into following parts namely:

a.) HEATING AND CRACKING:

Heating is done in the pre heaters and heat exchangers where as the cracking process takes place in the reactor where the HCs leaving the atomiser to pre-heater temperature are mixed with oxygen and 40 K steam. Prior to combustion they are heated and vaporized by back radiation of flame and the hot reactor wall, the reactor walls have a refractory lining. Cracking of HCs to C, methane and HC radicals take place in the reactor.

b.) REACTION PHASE:

On achieving of the ignition temperature HCs react with oxygen resulting in an exothermic reaction:

Cn Hm + (n + m/4) O2 ---------------- nCO2 + m/4

As equilibrium is far to right practically, all available oxygen is consumed in this phase. The rest of HCs which have not been oxidized react with combustion product & steam resulting in an endothermic reaction:

Cn Hm + nCO2 ------------------------- 2nCO + m/2 H2 CnHm + nH2O ------------------------- nCO + (m/2 + nH2)

To prevent excessive local temp. It is essential that eqn. 3 to 5 are intimately mixed so that exo & endo reactions are balanced. In this way the complex reactions are brought in thermal equilibrium resulting in measured temp. of about 1573 K to 1673 K.

c.) SOAKING PHASE:

This takes place in rest of reactor where gas is still at higher temp. The gas composition changes slightly owing to

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secondary reaction of methane, carbon & shift reaction. Methane content is decreased as under:

CH4 + H2O ----------------------------------- CO + 3H2 CH4 + CO2 ----------------------------------- 2CO + 2H2

The reaction rate is slow than expected at equilibrium, therefore methane content is also low.If sufficient residence time is provided, the C formed can also disappear following:

C + CO2 ------------------------------------- 2CO C + H2O ------------------------------------- CO + H2

2.CARBON RECOVERY UNIT: Carbon recovery has been designed for concentration of 1.5-3.0%. A constant concentration in carbon slurry is essential for smooth operating of palletizing machines which is ensured by operating the plant at constant capacity.

PRINCIPLE OF WORKING: size enlargement phenomena

A phenomena in which small particles are gathered into large masses in which original particles can still be identified. This is carried out rotary drum agglomerators with the help of agglomeration by tumbling method. During ball growth there is balance between destructive forces produced between the charge & cohesive forces holding the pellets together. Pellet strength must be sufficient to withstand these destructive forces. Carbon particles in water suspension are agglomerated & separated from the C slurry with addition of heavy oil which preferentially wets the carbon particles & is immiscible in water. Heavy oil deposits on the larger surface of carbon particles & individual carbon particles agglomerate to form heavier flakes. Under appreciable agitation s.a. rotation of palletizing machines, the flakes are converted to small particles of about 10mm diameter. The palletizing machines are cylindrical vessels of about 13m height. At the level of carbon slurry &

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heavy oil inlet a three legged agitator is provided to disperse the up coming slurry. Above this agitator a cylindrical rotor is provided which rotates the rising water & pallets core flinging them to the vessel where by collision & rotation the spherical pallets are formed.

3.RECTISOL-1 or DESULPHURISATION: The crude gas from C scrubber (in gasification section) enters rectisol-1 at 48 kg pressure & temp. 45ºC containing 97% H2S, 04% CO2. The gas is saturated with water. The entrained condensate is separated in scrubber effluent drum FA-202 & 204 & send to collecting pipe in the C recovery unit, through AFA-113. At the bottom of DA-201, crude gas is cooled with small amount of cold methanol to remove mainly cynogen compounds. The loaded methanol is sent to reflux drum.

The gas reaches the upper portion of DA-201 via chimney tray & here the H2S & all other organic S compounds are removed selectively by cold regenerated methanol from N2 stripping stage of CO2 regenerated down to total S content of .4 p.p.m. The old desulphurised gas leaves H2S absorber at -28ºC through a demister installed at the top of the absorbed thus preventing entrained methanol droplets in the gas. The gas is used for H2S removal section at 35º C & 45 kg pressure.

4.SHIFT CONVERSION: In shift conversion section,S free gas reacts with steam to form H2 and CO2.

CO + H2O ----------- H2 + CO2

Excess steam is used to prevent C deposits and to procure higher rate of conversion. There is a limit of excess steam supplied because too much excess steam reduces the content time between gasses and the catalyst which further reduces the rate of conversion. The reaction is exothermic,then equilibrium is favoured towards H2 formation by low temp but rate constant by high temperature.

CATALYST USED ARE:

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1. iron oxide2. cobalt molybdenum3. copper zinc4. iron chromium(it is used at NFL in temp. ranging between 350ºC and 500ºC)

5.RECTISOL-2 or DE-CARBONATION: 122576m³/hr of converted GSA at 45ºC & 42.5 atm containing 33.72% carbon dioxide enters the section from the shift conversion section. Since the gas is water saturated, entrained condensate is separated in separators FA-404 & 406. The gas is then cooled in three steps:

1. From 45ºC to 27ºC in heat exchanger, EA-401 A with synthesi gas from nitrogen wash unit.

2. From 27ºC to -16ºC in heat exchanger, EA-401 B with synthesis gas from N.W.U.

3. From -16ºC to -25ºC in ammonia chiller EA-402.

In order to avoid formation of ice below freezing point. Methane is injected in covertor gas steam before it enters EA-401 B. The condensate from EA-401 B is passed on to CO2 flash column DA-205 for stripping off CO2 before being sent to

methanol water rectifier DA-204. The converted gas at -25ºC & 404 kg/cm² gas enters the CO2 absorber bottom where all CO2 is removed from the gas by washing with cold regenerated methanol from the sripping stage of CO2 regenerator fed at the tray & finally pure methanol from hot regenerator at the top of the tower.

6.NITROGEN WASH UNIT: Decarbonated gas coming to N.W.U from rectisol 2nd, decarbonation at 39.5kg/cm² & 55ºC containing 5.21%CO, 50% methane, 93.62% of hydrogen, 67% nitrogen & argon CO & methane are undesired components in synthesis as ther act as catalyst poison & inert respectively. They are so removed from gaseous mixture by liquid nitrogen wash. Hydrogen boils at considerably lower temp. than other impurities which are removed by fractional distillation. B.P of hydrogen is -249.4ºC

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nitrogen at -195.8ºC, carbon monoxide at -191.5ºC & methane at -161.5ºC. The methanol content from decarbonated gas is removed by passing through molecular sieve in absorbers beds. After CO2 & methanol removal in absorbers, gases enter the cooled box, where washing with liquid nitrogen from A.S.U is done. Finally purified gas slightly rich in nitrogen, leaves from the top of the tower.

7.AMMONIA SYNTHESIS: Make up gas coming from N.W.U is compressed to around 220kg/cm² press by synthesis compressor. Upto 3 stages of compressor make up gas is compressed, while the suction of 4th

stage or the recycle stage, it is mixed with recycled gas coming from the synthesis section (3rd and 4th stages are housed in a single barrel). Recycled gas goes to ammonia converter, radial type, consisting of 2 beds charged with reduced iron-oxide catalyst.

N2 + 3 H2 -------------------------------- 2 NH3 + heat

Is a reversible reaction. Ammonia produced along with unreacted gases leaves the convertor, it is first cooled in economizer, then in synthesis hot gas exchanger. Ammonia is then liquified & separated, gases from separator are even recycled. Cooling system of ammonia chiller is equipped with refrigeration compressor. Thus the ammonia product being formed is sent to urea plant for storage.

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UreaPlant

As we know that our ultimate aim is to maufacture urea which is achieved by the reaction of ammonia with carbon dioxide. We get ammonia manufactured from ammonia plant which has to combine with carbon dioxide to form carbamate which further changes to the urea. Therefore the manufacture of urea includes following main sections:

1. synthesis section

2. decomposition section

3. crystallization & prilling section

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1.SYNTHESIS SECTION: This is the section in which ammonia is made to react with carbon dioxide to give ammonium carbamate which further changes to urea with removal of water. The two reactions involved finally result into an exothermic reaction. The conversion of ammonium carbamate to urea depends upon:

a. reaction temperature & pressureb. molecula ratio of ammonia/carbon dioxide, H2O/CO2

of the feed reactantsc. residence time

2NH3 + CO2 ------------------------------- NH2COONH4 (ammonia carbonate)

NH4COONH4 ---------------------------- NH2CONH2 + H2O (urea)

The reactions are reversible. The principle variables affecting the reaction are temperature, pressure, feed composition and reaction time.

2.DECOMPOSITION SECTION: MITSUI TOATSU TOTAL RECYCLE C IMPROVED PROCESS is a conventional process i.e. the process where decomposition is effected by lowering in press. In successive stages followed by indirect heating whereas the process where decomposition takes place by lowering the partial pressure of either NH3 or CO2 followed by indirect heating called STRIPPING PROCESS. NH2COONH4 --------------- CO2 + 2NH3

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Decomposition is usually achieved at temperature of 120ºC to 165ºC. Decreasing pressure favours decomposition,as does increasing temperature.

3.RECOVERY SECTION: The gas from the gas separator, goes to off gas condensor, cooled down to 61ºC by C.W. enter in the bottom of off gas absorber O.G.A. consists of 2 packed beds. Some amount of ammonia and carbon dioxide are absorbed and condensed in the lower packed bed by recycle solution which is cooled down in O.G. cooler. In absorbed packed bed, absorbed and condensed are the residual ammonia and carbon dioxide completely by the condensed solution in O.G. Condensor after being cooled down at gas final cooler. The air from top of O.G.A. is blown to gas separator by off gas recycle blower after fresh air being added at suction and pressure is controlled at the discharge.

It is not practical to compress the ammonia-carbon dioxide mixture & return this to urea synthesis reactor. Compression causes the recombination ammonia and carbon dioxide to solid ammonium carbonate and clogging the compressor. The method of recycling the unreacted gas can be :

a. separate and recycle as gasrecycle in solution and slurry form

4.CRYSTALLIZATION AND PRILLING SECTION: The urea solution leaving the de composer is vacuum crystallized and urea crystals are separated by centrifuge. To use efficiency in the heat of crystallization and to evaporate water at lower temperature, vacuum crystallization is often used crystals formed in the vacuum crystallizer are centrifuged and then dried to less than 0.33% moisture by hot air. To keep the bluret content about 0.1% in crystals urea, a certain amount of mother liquor which contains almost all the bluret originally present is recycled to the recovery section as the absorbent liquid for carbon dioxide and ammonia.

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NH2CONHCONH2 + NH3 ---------------------------- 2NH2CONH2 (biuret) (urea)

Dry crystals are conveyed to the top of the prilling tower passing through fluiding dryer. There, the crystals are melted in a specially designed steam heated melted. The molten urea flows through distributors, and thus it is formed into droplets.

Steam generation plant (S.G.P

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Steam generation plant is mainly installed for production of steam and then distributed to various parts of the plant. Here this section of plant installed in national fertilizers limited, bathinda unit produces and supplies steam at 100 kg/cm² pressure and nearly 480ºC temperature to ammonia plant.

In todays world steam has gained importance in� industries. It may be used for power processors and heating purposes as well.

Why and where steam is required????��

As nearly 6-7 tones of steam is required to produce 1 ton of ammonia. This is used:

for driving the turbo-compressor as process steam for various reaction for heating purpose

High pressure turbines are being used where high pressure and temp. is to be maintained so SGP section plays an important role for maintaining the said condition.

There are three boilers (VU-40 type supplied by M/S BHEL) of 150 ton/hr capacity. These boilers are Water Tube Boilers i.e. water is inside the tubes and hot air surrounds it when coal is burnt, this makes the water in the tubes boil and steam formation takes place. In the beginning coal is burnt with fuel oil to get desired temperature.

BENEFITS OF STEAM:

It is colorless, odourless and tasteless. Very economical. Non-polluting. Can be used as heat exchanger. It can be easily distributed to various sections of plant.

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FUELS USED:

COAL:

To obtain steam of desired temperature and pressure, coal is burned to give major source of heat. Initially coal is stored at Coal Handling Plant brought from coal sites. It is this section of plant where coal is crushed by crushers in order to make small pieces of coal, then after crushing it the coal pieces rare passed through heavy electromagnet where iron is separated from coal if present. Coal is then sent to bunkers from where it goes to Grinding mill. Grinding mill is grinding coal into powder form.

Conveyor belts are being used in the whole plant for transportation of coal. The powder form of coal is sent to the boilers through pump as pump sucks the coal from grinding mills and throws it into the boiler for combustion.

» Coal pulverizing in boiler:

Coal is pulverized before firing for achieving a stable and efficient combustion. Many types of pulverizers are used in the boiler by different designers. Pulverizing coal is the most efficient way of using coal in a steam generator. The coal is grind so that about 70% will pass through 200 mesh (0.0075mm) and 99% will pass through 50 mesh (0.300mm). Pulverized coal boiler can be easily adapted for other fields like gas if required later without much difficulty.

»The purpose of pulverizing in a coal fired boiler:

To supply pulverized coal to the boiler. Transport the pulverized coal from the pulveriser to the

boiler in the boiler.

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To remove moisture in coal to an acceptable level for firing in the boiler.

To remove high density in organics from coal during pulveriser.

To classify coal particles to the required level of fineness, normally 70% through 200 mesh and less than 2% on 50 mesh.

FUEL OIL:

As the boilers are designed to wok on both coal as well as Fuel oil so fuel oil can also be pumped to Boiler for combustion.

Generally coal alone is not burnt initially but fuel oil (LSHS) is mixed coal and then sent to the furnace for combustion in order to get desired temperature.

WATER AND STEAM SYSTEM:

As the steam being used should be free from impurities like minerals, silica, oxygen, iron, etc in order to ensure safe and efficient working of steam turbines and boilers. For this purpose raw water is physically and chemically treated and finally supplied to steam generation plant from ammonia plant. This water is called boiler feed water which is further heated to 240ºC by the flue gases and taken to steam drum. Steam drum acts as strong tank and also separates water from the steam at 315ºC and 106kg/cm². Pressure water then enters the ring heater formed at the bottom of outside the furnace and rises by gravity through water wall tubes on all the four sides, takes heat from furnace and enters steam drum as a mixture of steam and water.

FLUE GAS SYSTEM:

The products of combustion in the furnace consists of carbon dioxide, nitrogen, ash, oxygen and sulphur dioxide. After leaving the furnace the heat of these gases called flue gases, is utilised at various levels.

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First the steam from the steam drum is heated in two super heaters to get the required temp. of 495ºC and then feed water in bank tubes is also heated and the gases leave the bank tubes at around 497ºC. next the heat is utilized to heat feed water in the ECONOMISER and gases are cooled down to 320ºC. these gases are further cooled down to 150ºC in ROTARY AIR HEATER where the air is required for combustion and conveying the coal is heated up. Temperature is not reduced further because at lower temp. oxides of sulphur present in flue gases are converted to ACID which damages the down steam equipments. These gases then pass through ELECTROSTATIC PRECIPITATOR (E.S.P) where ash is removed.

Captive

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PowerPlant

(C.P.P)

NFL has set a Captive Power Plant (C.P.P) at there complex at Bathinda, to ensure availability of stable, uninterrupted power and steam to the ammonia and urea plant. This will minimize the tripping of the fertilizer plant due to transit voltage dips and power cuts.

Since inception, Bathinda unit was drawing electric power from Punjab State Electricity Board (PSEB). Electricity is the main driving force after steam in the plant, being used for moving auxiliary equipments. The unit requires 27MW of power per hour when running at full load. There are two 15MW turbo-generators to generate power. Under normal running conditions

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of the plant and healthiness of the PSEB grid, we generally run in synchronism with the grid merely drawing the power corresponding to the minimum charges to be paid to State Electricity Board. In case of any disturbance in the grid, our system gets isolated from the grid automatically. With both generators running, we are able to feed power to the whole plant, thus production is not affected. In case only one turbo-generators is in line and grid cuts-off, urea plant is cut-off automatically to balance the load with one generator. As soon as the grid becomes stable, the generators are again synchronized with it. The power generation of each generator can be varied with 2 MW to 15MW maximum, provision exists to run the generator on 10% extra load continuously for one hour only.

Operation of C.P.P is based upon microprocessor based computerized instrumentation which allows automatic operation, start up, shut down of the whole or part of the plant. It allows controlling process variables like flow, pressure, temperature, power factor, voltage, frequency, etc. There is operator interface unit (I.O.U) like t.v screen on which various parameters can be displayed and controlled.

NEED FOR C.P.P:

It was thought to install a captive power plant in which electric power for our requirement shall be generated in a coal fired boiler. The benefits envisaged were:

1. Any disturbance in the PSEB grid used to trip the whole plant a lot of money was lost, due to this as each re-start up cost around 40-50 lacs rupees. Moreover, frequency trippings had an illeffect on machines and equipments extending the re-�start up period.

2. Three boilers of 150 T/hr steam capacity were initially installed in S.G.P to keep 2 boilers running and 1 stand-by as designed steam requirements was less than 300 T/hr. But in actual operation steam requirement was more and all three boilers had to be run and there was no breathing time for their maintanence. As

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new boiler was to be installed for C.P.P, its capacity was so designed that it could export around 60 ton of steam for process requirement so that only 2 boilers of S.G.P would be run keeping the 3rd as stand-by.

The functioning of C.P.P can be divided into parts:

BOILER: Boiler has been supplied by M/S MITSUI ENGINEERING AND SHIP BUILDING CORPORATION OF JAPAN. It has a capacity to produce maximum230 ton/hr of steam at 105 kg/cm² pressure and 495ºC temp.. 150 T/hr steam is used for power generation if both generators are running at 15 MW each. Around 60 ton steam per hour is drawn for process use and joins with the S.G.P steam header. Main difference between two boilers are :

S.G.P boiler is tangentially fired where as C.P.P boiler is front fired with 6 coal burners and 6 oil gun fixed inside the coal housing.

S.G.P boiler can be loaded upto 30% load with oil firing only where as C.P.P boiler can be fully loaded with oil alone.

height of combustible zone in C.P.P boiler is more and it has residence time of 1.5 sec where S.G.P boiler has 1.0 sec.

due to more resistance time and better polarization the efficiency of C.P.P boiler is about 4% higher.

boiler feed water required for steam generation can be fully generated of C.P.P itself.

TURBO-GENERATORS: CPP is having two number turbo-generators of capacity 15 MW each. These are totally enclosed self ventilated type with two lateral airs to water coolers for cooling. The alternators are able to bear 10% overload for one hour with an increase in temperature of 10ºC while maintaining the voltage as near as possible to the rated one. The exactation is compound and brushless with exciter rotor and rectifier mounted on the extended main shaft on non driving end. The excitation is controlled automatically with automatic voltage regulator and a PLC controller. In case of any distribution in grid, our system

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gets isolated from the grid automatically. With both generators running, we are able to feed power to the hole plant, thus production is not affected. In case only one TG is in line and grid cuts off, urea plant is cut off automatically to balance the load with one generator. As soon as the grid becomes stable, the generator are again synchronized with it.

TURBINE The turbine used is supplied by M/S SGP of AUSTRALIA. It is condensing cum extraction turbine designed as single casing reaction turbine with single control stage and high pressure (HP), mild pressure (MP), low pressure (LP) reaction parts.

The turbine is fed with high pressure steam at 100 kg from the boiler and flows through various control valves for normal and emergency operation. It gets high velocity fixed diffusers thus rotating the turbine. The enthalpy of the steam is utilized in steps. The exhaust steam from the turbine is condensed in a condenser maintained under vacuum to extract maximum steam enthalpy. The output of the turbine depend upon the flow of the steam and heat difference that is on condition of the steam at main steam valve and the pressure at the turbine outlet or condenser pressure. The turbine is connecting to the generator through reducing gears.

The exhaust steam is condensed in a condenser using cooling water. The resulting condensate can be fed back to LP heater but it is normally sent to the polishing water plant.

Various bleeds from the turbine are utilized for heating purpose. HP1 and HP2 are used for heating boiler feed water in HP1 and HP2 heater. Feed water bleeds is used for heating the feed water tank and LP bleed is used for heating the polish water make up to feed water tank.

A lubrication system is also there to lubricate the various bearings of turbine, gears and generator. Normally the oil pump driven by the turbine shaft supplies oil but has been provided for slow cooling of turbine rotor.

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Description:

Making simmering Graz Panker, Austria

Type Multifunctions (28 stages)

RPM 6789 at 50 Hz

Critical speed 3200-3600 RPM

FUEL COAL SYSTEM:

The purpose of fuel coal system is to pulverize coal to dry coal and to convey the pulverized coal from ball tube mill to burners by primary air for coal firing.

Fuel coal system consists of three system:

1. coal supply system2. primary air system3.seal sir system

COAL SUPPLY SYSTEM: COAL COAL CRUSHERS BALLTUBE ------ ------ ------BUNKER FEEDER DRYER MILL

Primary air system:

The primary air system performs two functions. It provides the proper amount of air required to convey the

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pulverized coal to the burners and the heat necessary to dry coal so it can be pulverized and burned efficiently.

Seal air system:

The seal air is distributed to the component by the sealing of the mill by the sealing air fan. The sealing air fan takes suction from silencer and discharges it to a commom header. The controller for each mill system provides a constant diferential pressure to protect against coal leaking into the bearings and seals.

Crush dryer system:

Crush dryer performs the crushing function. Metered coal from the feeders blends with a properly heated amount of air from the primary air fan and enters the crush dryer. Rotating hammers drive the incoming coal against a breaker plate and adjustable crusher block, increasing the surface area of the coal and mixing it with the incoming pre heated air.

Forced draft fan:

The forced draft fan supply the proper amount of secondary air required to support the combustible of the fuel delivered to the boiler.

Induced draft fan:

The induced draft fans control the furnace draft by drawing the gases of combustion through the boiler, regenerative air heater, delivering them to the stacks. Thus the FD fan provides combustion air for the furnace while the ID fan removes flue gases from furnace through chimney.

Power generation:

There are two 15 MW turbine generator sets to generate at 11 kV which is fed into 132kV bus of PSEB and again distribution network.

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DISTRIBUTED CONTROL SYSTEM

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DEFINATION :- A Distributed Control System (DCS) is a control system method that is spread, or distributed, among several different unit processes. Controller elements are not central in location but are dispersed throughout the system with each component sub-system controlled by one or more controllers. The entire system of controllers is connected by a network for communication and monitoring.

It is generally, since the 1970s, digital and normally� consists of field instruments, connected via wiring to computer buses or electrical buses to multiplexer/de-multiplexers and A/Ds or analog to digital and finally the Human-Machine� Interface (HMI) or control consoles. A DCS is a process control system that uses a network to interconnect sensors, controllers, operator terminals and actuators. A DCS typically contains one or more computers for control and mostly use both proprietary inter-connections and protocols for communications.

DCS is a very broad term that describes solutions across a large variety of industries, including:

Electrical power grids and electrical generation plants. Environmental control systems Traffic signals. Water management systems. Refining and chemical plants. Pharmaceutical manufacturing. Water management systems. Refining and chemical plants. Pharmaceutical manufacturing.

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Architecture of DCS

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Slave Module Functions Slave module functions include.

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Range and mode selection. Voltage threshold selection for digital I/O. Response time selection. Signal buffering. Signal conditioning. Signal isolation. Noise rejection. Analog to digital and digital to analog conversion. Cold junction compensation for thermocouples.

C-NET: C-NET is a unidirectional, high speed serial data network that operates at a 10 megahertz communication rate. It supports a central network with up to 250 system NODE connections.

The NIS allows any node to communicate with other node within the symphonysystem.,it to be interface with the nict module over dedicated expander bus.

The NICT module receives command from the host computer,execute it,then reply. The NICT module is single printed circuit board which contains microprocessor. Based communication circuitry that enable to directcommunication with its NIS module, To direct communicate with MPI module.

The IMMPI01 Multifunction Processor Interface module handles the I/O interface between the host computer and NICT module. The IMMPI01 module supports either SCSI parallel port at rates 4M byte/s or RS-232-C serial link at the rates up to 19.2 Kilobaud/s.

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NETWORK 90 SYSTEM OVERVIEW

Network 90 plant control system is a distributed control system. Using a series of integrated circuit, the NETWORK 90 lets the operated monitor and control the process variable such as rate, temperature, pressure etc. according to control configuration that engineer set for the plant.

The major elements of system are:

1. Process Control Unit (PCU)2. Operated Interface Unit (OIU).3. Computer Interface Unit (CIU).4. Management Command System Unit.5. Plant loop to loop gateway.

From these only PCU and OIU are used in NFL Bathinda rest is not being used in this plant. The communication loop (PCL) ties all the nodes together. The PCL enable the communication among the nodes for:

Sharing of control variable among the modules in different PCUs.�

Monitoring operation of the control scheme in the PCUs� with an OIU.

Controlling and process from an OIU. Configuring and maintaining the control scheme of a PCU

from an OIU. Monitoring the status of PCU equipment from an OIU.

NETWORK 90 SYSTEM NODES:

1. Process Control Unit (PCU): NETWORK 90 control and process modules are mounted in standard modules Monitoring Unit (MMU) which are mounted in PCU system cabinets. In the cabinet, power supplies and termination unit are also installed.

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2. Operator Interface Unit (OIU): OIU is a CRT based console, which provides access to entire NETWORK 90 system for plant operation, control engineering and system trouble shooting.

3. Engineering Work Station (EWS): Engineering work station is an integrated hardware/software package that provides remote access to NETWORK 90 system. EWS allows communication with entire NETWORK 90 system through the plant communication loop. With EWS operator engineer can

design, configure, monitor document or troubleshoot NETWORK 90 process activities as designed.

HARDWARE: personal computer 640 K RAM 20MB hard disk 14 CRT with keyboard � Pen plotter

FUNCTIONS: design and configuration with process logic

Control drawing. Symbol of control logic CAD functions for configuration. Monitor & tune of n/w 90 module. Store & load module configuration.

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Advantages of DCS

• Compact system• Can share data over the network• Online programming of the controllers• Hot redundancy of controllers, network and power supplies,

thereby making the system more reliable• System is highly rugged and maintenance free• Trouble shooting is simple and easy due to availability of

trends, operator action logs with time stamping along with user names

• Overall system is cheap for large plants• Different security levels for different users are available. So

same machine can be used for different functions by different users without effecting each others work

• Web monitoring is possible of graphic and trend windows on a general-purpose WWW browser by converting HIS files into HTML files and java applets. Thus making remote monitoring in offices far from the instrument is possible

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OFFSITE

1. It is often referred to OGP meaning offsite group of plants.

DESCRIPTION OF PLANTS:

1.RAW WATER PLANT (R.W.P):

The raw water procured from Bathinda canal is at first stored in reservoir. The procured water has impurities like:

a. SETTABLE: e.g. mud,clay,sand which are settled in reservoirs.

b. UNSETTABLE: these impurities can be either dissolved or suspended. The suspended impurities can be cleaned by method of flocculation in which agglomerates are formed, further water is purified in sand filters installed.

2.DE-MINERALISED PLANT (D.M. PLANT):

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Basic principle of working : ION EXCHANGE

At first come across cation unit in which elements like Ca, Mg, Na are removed. As a result of which HCI & carbon dioxide are formed & even small quantity of carbonates which are removed by DEGASING. In degassing water is sprayed from up & air is supplied from bottom as a result of which gases like carbon dioxide are removed. Further impurities viz. chlorides, sulphates, silicates are removed by passing water ahead through primary mixed bed which contains both cationic A.W.A anionic resins which are regenerated after being exhausted by acid & alkali respectively. Then further water is stored in D.M water tanks passed through secondary mixed bed & finally we get our required polish water.

3.COOLING TOWERS:

These are water towers installed to remove the unwanted heat which as a result increases the efficiency of the plants even individually. There are basically three C.Ts:

C.T-1

In which all the cooling for ammonia plant is done exclusively.

C.T-2

For treating water from urea plant

C.T-3

For water from prilling tower.

4.COMPRESSOR HOUSES:

They have been used to run the whole system under numatic control. In this the compressor sucks in air which is then dried with the help of dryers to remove the moisture content.

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Four lubricating pumps have been installed because we dont want any presence of air which can lead to corrosion.�

Teflon rings are used to have least friction possible. Dew point is maintained at approximately -30º, its good to achieve a bigger negative value. E.g. -55º but not vice-versa.

6. EFFLUENT TREATMENT PLANT (E.T.P):

There are 4 basic types of wastes namely:

a.chemical waste

b.acidic waste

c.alkali waste

d.sewage waste

These wastes are all put in a sump, from were they pass through innumerable process namely aeration, nitrification (to produce bacteria need for decomposition) then denitrification & many more. Therefore at last we achieve a stage where all effluents are removed & the treated water is stored safely in 3 reservoirs , again ready for reuse.

CONCLUSION

After doing my training at NATIONAL FERTILISERS LIMITED, BATHINDA. I felt the importance of training in industry and its practical application. When I was studying the theory of different concepts I was thinking how all these would

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be implemented but after training I learnt that how all these could be put in use. It was the result of training only that I got to see the objects in real and practical use, which I only read.

During my training at NATIONAL FERTILISERS LIMITED, BATHINDA. I got a chance to expose myself to industry culture and work environment. In other words these two months of training at N.F.L. were a real learning experience. All the way these happened due to co-operation of staff and management who helped me in gaining knowledge about whatever I have today about industry. In the end, I would like to conclude that the training is an essential part of the education program. We should always persue for the theoretical as well as practical knowledge, both of which are must for the foundation of the high building.

SAFETY COMES IN CANS� �

I CAN, YOU CAN, WE CAN

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REPORT ON INDUSTRIAL TRAINING AT NATIONAL FERTILIZERS LIMITED (AN ISO-14001 UNIT) BATHINDA

SUBMITTED BY: KAMALPREET KAUR ROLL NO. 11402039 E.C.E

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PUNJABI UNIVERSITY PATIALA (10june 2016-15 july 2016)

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