NFL Training Report

Six Months Industrial Training File Including Project Report

Degree :Mechanical Engg

College :Global college of engineering and technology khanpur khui ( Ananadpur sahib )

Working in an industry provides us a practical approach to our theoretical basis of knowledge acquired in our class room. It has been a great pleasure; training at NATIONAL FERTILIZERS LIMITED, NAYA NANGAL. This industry helped me to boost up my practical skills correlating the theories of book into actual work environment.

A TRANING REPORTOnSix Month Industrial TrainingAtNATIONAL FERTILIZERS LIMITEDNANGAL UNITSubmitted toPUNJAB TECHNICAL UNIVERSITY, JALANDHARIn partial fulfillment of the requirements for the award of Degree of Bachelor of TechnologyInMechanical EngineeringByRAJAT KUMAR100331130054Under the guidance ofEr.VISHAL JASWAL A.K. SAINIAcademic Tutor Industrial TutorDepartment of Mechanical Engineering Global College of Engineering & TechnologyAnandpur SahibINDEXSr.No. TOPICS PAGE NO.1 PREFACE 32 ACKNOWLEDGEMENT 43 INTRODUCTION TO N.F.L 54 NAYA NANGAL UNIT 95 N.F.L AT A GLANCE 126 MECHANICAL WORKSHOP 137 UREA PLANT 338 STEAM GENRATION PLANT 509 PROJECT 6610 HOW INDUSTRIAL TRAINING IS USEFUL8511 REFERENCE 86LIST OF FIGURESSR. NO. DESCRIPTION PAGE NO.1. NFL PLANTS LOCATION 52. FRODUCTION SHARE OF NFL IN COUNTRY 63. LATHE MACHINE 154. PARTS OF LATHE MACHINE 175. SLOTTER MACHINE 386. SHAPER MACHINE 407. PARTS OF SHAPING MACHINE 468. PARTS OF MILLING MACHINE 519. GRINDING MACHINE 5410. PLANNER MACHINE 55PREFACEMechanical is a multidiscipline subject, which embraces physics, metallurgy thermodynamics, mechanics fluid, chemistry and electrical principles and as such is an interesting and often stimulating area of engineering.Working in an industry provides us a practical approach to our theoretical basis of knowledge acquired in our class room. It has been a great pleasure; training at NATIONAL FERTILIZERS LIMITED, NAYA NANGAL. This industry helped me to boost up my practical skills correlating the theories of book into actual work environment. The following implants training report presents all my observation, analysis made during my training period of 6 weeks. The report concerns with the workshops, ammonia plant, steam generation plant, urea and begging plant and section where I have been deputed in the training.The information and data furnished in the context are on the basis of my information collected through interaction with the Engineers, Technocrats, Technicians, and Workers working in the firm. Despite taking every effort to procedure an error free report, I apologize for any mistake in the context on my part.The main objective of industrial training is to enable the students to apply the theoretical knowledge to practical situations &to expose themselves to the industrial environment. It helps the students to understand the importance of discipline, punctuality & teamwork & also cultivates a sense of responsibility in them. With the help of training students get exposed to the current technological developments & also understand the psychology of the workers.ACKNOWLEDGEMENTOut of deep sense of gratitude I express my sincere thanks to Mr.N.K Gupta (Sr. manager, HRD deptt.), Mr. Umesh Kumar (Ammonia II workshop) and Mr. Ram Prasad,(mechanical workshop) for timely helping me in the technical and operational aspectI sincerely express my thanks to Training and placement incharge, Global College, Anandhpur Sahib for providing me this opportunity.I express my sincere thanks to Mr. N.K.Gupta (Sr.Manager,HRD Dept. NFL Nangal) for their timely help. I am equally thankful to Mr. Tara Chand (Manager Mechanical Workshop), Mr. S.K.Negi (Manager Ammonia), Mr. K.P.Singh (Manager SGP) & Mr. Amrit Lal (Manager Urea & Begging) for helping me with the technical and operational .This project would not have been a success without my dear friends in this department. I am grateful to each and every one of them for their love and affection extended to me.Without the support and wishes of my parents, I could have never completed my project work. From depth of my heart, I acknowledge them with regared and affection.RAJAT KUMAR100331130054INTRODUCTION TO N.F.L.Today, NFL stands for hope, prosperity and growth. It has succeeded in enthusing its people with a sense of dynamism and pride by developing a work culture, where team spirit takes precedence over personal factors. NFL is already geared up to meet the challenges of 21st century. National Fertilizers Limited has been established as a conglomerate of fertilizer units on 1st April 1978. Presently, 5 world scale fertilizer plants and a bio-fertilizer plant are under the ambit of NFL operating in different parts of the country.They are: NFL Nangal unit(Punjab) NFL Bathinda unit(Punjab) NFL Panipat unit(Haryana) NFL Vijaypur 2 units(Madhya Pradesh) Bio-fertilizers Indore unit(Madhya Pradesh)NFL is the largest producer of Nitrogenous Fertilizers in the country with installed capacity of 13.70 lakh tons of N per annum i.e. 28.5 tones ofUrea and 3.18 lakh tones of CAN (calcium ammonium nitrate). The average contribution of nitrogen fertilizer during the preceding five years has been around 13.5%. The name and address of the industry is as:National Fertilizers Limited(A Govt. Of India Undertaking)Nangal unit,Naya Nangal,Dist. Ropar,Punjab.Pin-140126.Brief History of NFL, Nangal UnitThe decision to establish a fertilizer factory at Nangal was taken in 1954 by the Fertilizer Production Committee, Govt. of India.Reasons for Setting up Fertilizer Plant (i.e. Calcium Ammonium Nitrate (CAN) Fertiliser) and Heavy Water Plant at Nangal: The main factors responsible for setting up these plants at Nangal were:1) The availability of cheap and abundant power from nearby Bhakra Dam2) Inter-dependence of the process for the production of Heavy Water (a key material used in the production of nuclear power) & CAN Fertilizer3) Suitability of CAN fertilizer to the northern zone4) Good rail & road communication facilities and5) Availability of cold water from Sutlej River near the factory.CAN Fertilizer Plant was commissioned in February 1961 and Heavy Water Plant in August, 1962.For the establishment of these plants at Nangal, a company in the name of Nangal Fertilizer and Chemicals Pvt. Ltd. was incorporated on February 17, 1956. Subsequently when the work of setting up of a project at Trombay was further entrusted to this company, its name was changed on July 15, 1959 to Hindustan Chemicals and Fertilizer Ltd. Again, when the Govt. of India decided to amalgamate all the existing fertilizer factories under its control to form one corporation, the name was changed on January 1, 1961 to FCI (Fertilizer Corporation of India).NFL (National Fertilizers Ltd.) was incorporated on 23rd August, 1974 for setting up of two Urea fertilizer plants (along with Steam Generation Plant & Fuel Oil based Ammonia Plant) i.e. one plant at Bathinda (Punjab) and the other one at Panipat (Haryana) having an annual installed production capacity of 5.11 lakh MT of Urea each. The commercial production of Urea in these plants was achieved in 1979.In 1977-78, at Nangal, one Urea Plant (along with Steam Generation Plant & Fuel Oil based Ammonia Plant) having an annual installed production capacity of 3.30 lakh MT of Urea was erected and commissioned. On 1st April, 1978, Nangal Group of Plants of FCI were transferred to NFL upon reorganization of NFL & FCI.In 1984, NFL started to set up its 4th Urea Fertilizer Plant at Vijaipur (Distt.- Guna) in Madhya Pradesh, having an annual installed production capacity of 7.26 lakh MT of Urea. The commercial production of Urea at Vijaipur was achieved w.e.f. 01.07.1988. Later on expansion of Vijaipur Plant by setting up another Urea Plant having similar capacity of 7.26 lakh MT of Urea adjacent to the existing plant was taken up in 1993 for doubling its annual production capacity. The commercial production of Urea from Vijaipur Expansion Plant was achieved w.e.f. 31.03.1997. Later on, the Deptt. Of Fertilizer revised the annual installed urea production capacity of Vijaipur Plants (1 & 2) from 7.26 lakh MT to 8.64 lakh MT of Urea of each plant w.e.f. 1st April, 2000. Each plant (i.e. Vijaipur Plant-1 & 2) comprises of one stream of Ammonia Plant and two streams of Urea Plant with one Periling Tower.Present Installed Annual Urea Production Capacity of Nangal Unit: 4.785 lakh MT of Urea. In Feb, 2001, Urea plant at Nangal was revamped to increase its annual installed production capacity from 3.30 lakh MT of Urea to 4.785 lakh MT of Urea.Present Installed Annual Urea Production Capacity of NFL: 32.31 lakh MT of Urea.NAYA NANGAL UNITThe Nangal unit of NFL acted as a paragon of excellence in the field of development of the fertilizer industry in India. It has about 1600 employees working in different plants of the organization. Nangal unit began with the commissioning of the first fuel oil based fertilizer plant in India with rated capacity of 900MT/day Ammonia and 1000MT/day Urea. The adoption of versatile technology and desire for related diversification led to the manufacture of various products and by-products like Nitric acid, Ammonium Nitrate, Liquid Nitrogen, Liquid Oxygen, Industrial gases, etc.LOCATION OF THE FACTORYThe factory is located near Nangal Dam and 8kms from Bhakra Dam. The nearest railway station is Nangal Dam which is connected with Delhi and Saharanpur via Ambala Cant. Shivalik hills of the great Himalayas are situated 10 km different the area of Punjab and Himachal Pradesh from the factory and differentiae area of 7X2 sq.km including its township for employees. The one side of the factory touches another factory of the state govt. PACL (Punjab Alkalis and Chemicals Limited). The availability of cheap and heavy amount of power from Bhakra is due to the direct convenience through both, road and sail and large amount of water from river Satluj. Good weather conditions and cheap labor is another advantage. The location of NFL Naya Nangal is really unique.VARIOUS PLANTS OF N.F.L. Ammonia Plant Steam Generation Plant Urea Plant Bagging Plant Nitric acid Plant Methanol PlantPRODUCTS MANUFACTUREDNangal unit offers following industrial products: Nitric acid (54%) Anhydrous Ammonia Ammonium nitrate Liquid & Solid Methanol Urea Mill Rejected Coal Carbon Slurry Ash Slurry Element Sulpher Nitrogen Liquid Hydrogen Liquid Oxygen Liquid Carbon Dioxide Liquid (98%)BI-PRODUCTS Sodium Nitrate Sodium NitriteNATIONAL FERTILIZERS LIMITED AT A GLANCE Cost (in crores): Urea plant 132.00 Industrial Capacity (in tones) Urea plant 330000.00 Raw Material Requirement Electricity 40 MW Water 80 M Gallon/day Fuel oil 720 tons/day Coal 900 tons/day Naphtha 180 tons/day Total Production Urea 1450metric tones/day Methanol 67 tons/day Ammonia 900 tons/dayMECHANICAL WORKSHOPMechanical workshop at NFL unit mainly committed to the maintenance and repair work. Various maintenance jobs are done here as per the job orders given by different plants of NFL unit. The mechanical department has futher different workshops namely-: Machine shop Fabrication shop Fitting shop Earthmoving shop Refrigeration shopDetails of the different workshops is given as following. Machine shop Fitting shop Fabrication shop Earthmoving shop Refrigeration shopMachine shopMachining of a material involves repeated removal of material from the job to give away the required shape and size.Machine shop has various machines that are being used for the machining processes of the jobs from the plant. Some of the machines in the shops areSLOTTER MACHINELATHE MACHINEGRINDER MACHINEBORING MACHINEDRILLING MACHINEMILLING MACHINEPLANNER MACHINESHAPER MACHINESHEARING MACHINESHEET CUTTING MACHINELATHE MACHINELathe is a power driven, genral purpose machine used for producing mostlycylindrical jobs or work pieces. As the piece of metal to be machined is rotated on the lathe, a single point cutting tool is advanced racially in to the workpiece,removing the metal marterial in forms of chips.Main difference betweenlathes where as in the the other machines cutting tools is moved an the workpiece remains stationary.Parts of Lathe MachineHISTORY OF LATHEMost versatile machine tool in the machine shopOldest ancestor is the potters wheel(4000B.C)Next came pole latheThis was developed into current lathe which are able to make threadsFather of modern lathe HENRY MAUD SLAYSTypes of lathe machines found in the NFL mechanical workshop-Central latheTurret latheCapstan latheCentre lathe or engine latheIt is most important and widely used machine in the lathe family.its name is derived from the fact that the earliermachine tools were driven by separate engines or from the central engine with over head belt and shafts .The stepped cone pulley or gear head are often used for varying the speed of the lathe machineTurret latheIt is a production machine used to perform a lot of task or operation on a single job with minimum wastage of time.Indexable square tool is Provided on the cross slide or the mounting turning and parting of tool. The Turret usually accommodates tools for different operations like drilling ,counter sinking etcCapstan latheThese are similar to turret lathe and incorporate capstan slide which moves on a clamped in any position.It is the best suited for the large scale production of small parts because of its light weight and short stroke of capstan slideSLOTTER MACHINESlotter machine is also called as vertical shaper machine .the difference being that the ram is in vertical direction instead of horizontal position.Also the table or bed is mounted on a heavy base and provided with mechanism that make possible forward backward and side to side movement . it also has adjusted head mechanism .Advantages of vertical shaper or slotter machine :-1. Setting of the job is more convenient because it is easier to see, align, measure, clamp2. Press generated by the cutting stroke is better supported by the table bed3. Circular and hollow jobs can be worked upon4. Ram of vertical shaper can be adjusted up to 10 degrees.Main functions of slotting machine :- Internal key ways Tapered key ways Slots Centric slots Internal gearSHAPER MACHINEShaping machine is generally called as shaper. Shaper is being used for bothproduction and tool room work. The shaper can machine a flat surface on ahorizontal , vertical , angular plane. On this tyoe of machine ,many types of work pieces can be machined depending upon the tools used and the manner ofadjusting the various parts of the machine . Size of the shaper is determined bythe largest sized cube that can be machined on it. Working principal is quickreturn mechanism and forward stroke is cutting stroke and backward is idlestroke.Difference in shaper and lathe machine :-In shaper straight cutting is done where as in lathe circular cutting is done In shaping machine the tool moves in reciprocator fashion whereas in the lathe machine the tool remains stationary and the work piece moves.Parts of Shaping Machine are :-BASE : it is the reservoir for supply of oil circulated to the moving parts of machineARPON: it supports the tableRAM: It is the main moving part of the shaper machine. It holds anddrives the cutting tool back and forth across the work .This is attached to rocker arm which is given an oscillating motion byturning of a large driving gear .this also has an adjustable pin attached todriving gear which acts as a crank which determines the length of the ramTOOL HEAD: it holds the cutting tool. it is attached to the front of theram. Tool post is fastened to the clapper boxMain functions of the shaping machine :Making slotsTapered slotsexternal key on shaftHexagonal nut headsSquare nut headMILLING MACHINEMilling machine is one of the most versatile and widely used machine tool fortool room and production purposes.Milling is the process of removal of the material with the help rotating multiple cutting tools called as milling cutter. In general the work piece is fed into the rotating milling cutterParts of the milling machine :-ColumnKneeSaddleTableSpindleOver armCOULMN: It includes the base which I the main casting which supports the other parts of machine . The front of the column, the column face is machined to provide an accurate guide for the vertical travel of the kneeKNEE: It supports the saddle .feed change gearing is enclosed within theknee.knee can be raised or lowered on the column face.it is supported and canbe adjusted with a elevating screw.SADDLE: It supports the table . It is supported by the surfaces of the kneeTABLE: It holds the workpiece. It has T-slots and is used to hold thejods .bolts fit loosely in the T-slots and are used to clamp the vice.SPINDLE: it holds and diverts various cutting tools.it has the shaft mountedon the bearing supported by the column.OVER ARM: it is mounted on the top of the column. It is guided by themachined dovetail surfacesGRINDING MACHINEGrinding is the process of finishing surface by means of revolving abrasive wheelIn order to finish the job piece efficiently one must not only be able to operateThe grinder but also understand abrasive and grinding wheels ,their shapes andsizes for different type of workABRASIVE: An abrasive is any material that can wear material softer thanitself .sand and sandstone are perhaps the oldest abrasives known to mankind.Abrasives can be natural or manmade.Natural Abrasives: Emergy and corundum are two commonly used in theIndustry to sharpen tool edge They occur as a miner deposit in the earth crust .Aluminum oxide is the best suited for grinding material that has high tensile strength such as high spee steel and high carbon steel.Man made Abrasives: these are better than natural ones because in thesepurity and grain size can be controlled.GRINDING WHEELS: Grinding wheel are formed by using a suitable material to cement, bond, abrasives grains together in the desired shape and size. Hardness of the wheel is dependent upon the amount and kind of bindingmaterial being used. Hardness of wheel is always understood by means ofstrength of bond.TYPES OF GRINDING MACHINES Surface Grinder Cylindrical Grinder Internal Grinder Thread GrinderSURFACE GRINDER: Surface grinding is the process of producing a finished flat surfaces by means of grinding machine employing revolving abrasive wheel. Surface grinder machine consist of spindle mounting a grinding wheel and table or magnetic chuck for holding the work pieceUses of Abrasive Grinding : - Sharpening cutting Snagging FinishingPLANNER MACHINEPlaner is one of the basic machine tools used in machine shop. Main function isto produce flat surface on piece of work. The main difference between planerand shaper is that in planer machine the work piece moves In reciprocatingmotion while tool is fixed where as in the shaper machine it is other wayround. It can be distinguished in two either Hydraulic or Mechanical.Main parts of Planer Machine are: Bed Table Saddle Tool headFABRICATION The process of joining metals or non-metal to from an object which has specific shape .This process is known as fabrication. Different types of machines and welding are used in the fabrication process or to fabricate an object.THE WORKDONE AT THE SHOP ARE CLASSIFIED AS :1) Metal cutting method :-Oxy fuel gas cuttingPlasma cutting2) Metal joining method :-Oxy-acetylene weldingArc weldingTungsten inert gas weldingOxy-acetylene Gas welding: This process is particularly suitable for joining metal sheet and plates and having thickness 2 to 50mm. The filler metal is the addition metal, which is added to weld in the form of welding rod. The composition of the filler rod is usually the same or nearly the same as that of the part being welded. To remove the impurities and oxides present on the metal to be joined and to obtain stationary bond flux is always implied during the welding expect sheet. Various gas combustions can be used for producing a hot flame for welding metals. Common mixture of gases oxygen and other fuel gases. The oxy-acetyl welding mixture is used to a much greater extent than other in the welding industry. The temperature of this welding flame in its hottest region is about 3200 C.CaC2 + 2H2O C2H2 + Ca(OH)2ARC WELDING METHODSMetal arc welding: In the arc welding metal rod is used as an electrode,while the work being welded is used as another electrode. The temperatureproduced is about 2400C and 2600C on the ve and +ve electroderespectively. During the welding operations, this metal electrode is meltedby the heat of the arc and is fused with the base metal, thus forming asolid union after the metal has been cooled. Both AC and DC can beused .Adjusting the machine to correct amperage, which is determined bythen size of the rode to be used ,start the welding operations. The correctwelding speed is important.SPECIFICATION OF ELECTRODES:Where1. E is used for covered electrode that is for coated electrode.2. Next two XX multiplies with 1000spin shows the tensile strength.3. Next X shows the position of joint to be welded in current condition i.e. it may horizontal, vertical or inclined4. Last X shows the types of coating.UREA PLANTUrea plant has a rated capacity of 1550Te/day of prilled urea produced in a single stream plant employing MITSUI TOATSU TOTAL RECYCLE C IMPROVED PROCESS.Features of the plant are as under:-Sl no. Features MTC-C-IMPROVED1. Type of process Conventional2. Molecular ratioNH3 : CO2H2O : CO24:10.544:13. Conversion percentage 70%4. Reactor conditionsPressure kg/cm2Temperature 0C2502005. Reactor lining Titanium6. Reactor features Hollow7. Excess NH3 recycle As liquid NH38. Decomposition stages 1st: 17.5kg/cm22nd : 2.5 kg/cm2 ( 5% CO2 fed to 2nd decomposer)3rd: 0.3 kg/cm29. Heat recovery in carbonate condenser For supplying heat to crystallization to urea slurry and heating hot water.10. Sp. Cons.Te NH3/Te ureaTe CO2/Te ureaPower /Te urea KWHSteam /Te urea0.580.7686.41.2411. No. of conc. Stages One12. Type of prilling tower Induced draft13. Approx. prilling height 40M14. Salient features a.) power saving as 5% CO2 is fed to LDb.) P.T. height is less cause of cooler at bottom.c.) Low biuretd.) Because of Ti lining in reactor corrosion rate is less and thinner liner.e.) Water recycle is less due to counter current flow of liquid and vapour in decomposers.The plant is divided into four sections:1. Synthesis section.2. Decomposition section.3. Crystallization and prilling.4. Recovery.5. The brief description of various sections is given as under:SYNTHESIS SECTIONIn MITSUI TOATSU TOTAL RECYCLE C IMPROVED PROCESS liquid ammonia is recycled since it is easier to handle but require equipments like rectification column storage tanks etc. and higher capacity liquid ammonia pumps.Recycling of carbamate requires higher capacity carbamate pumps.CO2 is received from ammonia plant at a pressure of 0.2 kg/cm2 and 200C and is compressed in a centrifugal booster compresser,UGB-101 to 32 kg/cm2 in 3 stage unit. The compressor supplied by M/S BHEL has a normal capacity of 25256NM3/hr and has 2 barrels 2 M.C.L. 805 and MCL 455. The drive of the compressor is an extraction and condensing type by steam turbine supplied by M/S BHEL. The turbine is driven by 40K super heated steam and has a rated output of 5792KW.UREA SYNTHESIS2NH3 + CO2 NH2CONH4, H = -37.64Kcals 1NH2CONH4 NH2CONH2+ H2O, H = 6.32Kcals 2Where as reaction 1 is an exothermic and rapidly goes to completion of 2 and is endothermic and is always incomplete. The overall reaction is exothermic and hence heat has to be removed continuously for the equilibrium reaction to proceed. The conversion of ammonium carbamate to urea depends upon:1. Reaction temperature.2. Mol. Ration of NH3/CO2, H2O/CO2 of the feed reactants.3. Residence time.The conversion increases with the increase in temperature, NH3/CO2 ratio and residence time and decreases with H2O/CO2 ratio since the presence of water tends to shift reaction 2 in the backward direction. The pressure employed depends on the reaction temperature and has to be kept higher than the dissociation pressure of ammonium carbamate at that temperature. Further since the dehydration of ammonium carbamate to urea takes place in liquid phase only. The pressure employed must also be higher than the vapour pressure of ammonium carbamate which is rather high.High ratio of NH3/CO2 increases conversion and helps to minimize corrosion. As this ratio increases the load on recovery section increases since excess NH3 over stoichiometric requirement has to be recovered and recycled back to reactor. This excess ammonia can either be recycled as liquid NH3 or carbamate. In each case it becomes necessary to inject CO2 into carbamate condensers.The compressed CO2 is washed with water in a packed bed tower called methanol absorber for removal of entrained methanol in CO2 which is normally 100ppm. The washed CO2 is further compressed to a pressure of 260kg/cm2 in a two stage compressor, UGB-102 supplied by M/S KOBE STEEL, JAPAN. This reciprocating compressor has a normal capacity of 26260NM3/hr and is driven by a 2.2MW synchronous motor. Anti corrosion air at the rate of 120NM3/hr is fed to CO2 at the suction of centrifugal CO2 booster compressor.Liquid ammonia at 110C and 18kg/cm2 pressure is received in the ammonia reservoir, UFA-401 from the Horton sphere. Ammonia booster pump UGA-404A&B boost the pressure of the feed ammonia to 24kg/cm2 and feeds at the suction of plunger type ammonia feed pumps UGA-101A-D. the ammonia feed pumps are of URACA MAKE driven by 3.3kV/450KW and have capacity of 53.2M3/hr, 178RPM and 89% efficiency. The ammonia preheater UEA-101 and 102. The preheated ammonia at 85.30C is fed to the urea reactor at bottom.The recycled carbamate solution of CO2 concentration, 7.5 lit per 25ml, at 1050C and 260kg/cm2 pressure is delivered to the urea reactor at bottom by recycle carbamate solution pumps UGA-102A&B. these pumps are centrifugal type and are driven by back pressure steam turbine, supplied by M/S EBARA,JAPAN and have a capacity of 81M3/hr.The three feeds i.e. CO2 liquid ammonia and recycled pump solution are fed to a Ti lining multi layer urea reactor. The reactor is a 12 layered C.S vessel with Ti liner thickness of 5mm, 4mm and 3mm for the 1/6th, 1/6th and 2/3rd of total height of the reactor from bottom. The reactor top temperature is maintained at 2000C maximum. The effluents from urea reactor from top are let down to 17.5kg/cm2 pressure through a pressure control valve PCV-101 and fed to the high pressure decomposer at 1240C.DECOMPOSITION SECTIONMITSUI TOATSU TOTAL RECYCLE C IMPROVED PROCESS is a conventional process.The decomposition reactionNH4COONH2 2NH3 + CO2Is favored by lower pressure of system or by low partial pressure of one of the reaction products i.e. NH3 and CO2. Conventional process means the process where the decomposition is affected by lowering in pressure in successive stages followed by indirect heating whereas the processes where decomposition takes place by lowering the partial pressure of either NH3 or CO2 followed by indirect heating are called STRIPPING PROCESSES.The reactor effluents at 17.5kg/cm2 and 1240C enters the part of high pressure decomposer U-DA-201 having sieve trays at upper and falling film heater at lower section. The flashed gases go up and liquid flows down through sieve trays. On trays the high temperature gas from reboiler,U-EA-201 and falling film heater contacts with the liquid flowing down. The sensible heat of gas and heat of condensation of water vapour are used to evaporate the excess ammonia and to decompose the carbamate.This helps in minimizing water evaporation and thus reducing water recycle to reactor. The reboiler further heats the liquid by 12kg/cm2 steam to release excess ammonia and carbamate gases. The temperature at middle is maintained at 1510C by a temperature control valve TCV-201. The temperature at bottom is maintained at 1650C through TCV-202. The falling film heater is used to minimize residence time in order to reduce biuret formation and hydrolysis of urea.Anti corrosive air is fed to high pressure decomposer and reboiler through air compressor UGB-201@ 2500ppm as air. Overhead gases from HD are absorbed in HAC(high pressure absorber cooler). The bottom liquid flows to L.D. (low pressure decomposer) at 2.5K, 1450C,upper part, having 4 sieve trays. A similar phenomenon occurs in the low pressure decomposer. The reboiler U-EA-202 provides heat using 7kg/cm2 steam for decomposition and hot stream from H.D heats up the solution from L.D in an exchanger before entering the upper part. The temperature is maintained at 1300C at middle by TCV-203. Small amount of CO2 is fed below packed bed for improved stripping of decomposed gases. The overhead gases from low pressure decomposer are absorbed in low pressure absorber U-EA-402. Bottom liquid flows to 3rd stage of decomposer called gas separator U-DA-203. The upper part of gas separator operates at 1060C, 0.3K and lower part with packed bed operates at 1000C and atmospheric pressure. The sensible heat of solution from low pressure decomposer is enough for evaporating the overhead gases. In the lower part, air containing trace amounts of NH3 and CO2, is blown under the packed bed, by off gas recycle blower UGB-401. The urea solution is concentrated to 70-75% and sent to crystallization section.CRYSTALLIZATION AND PRILLING SECTION :The urea solution obtained from the last decomposition stage i.e. gas separator contains 25% H2O since every mole of urea one mole of H2O is formed. Urea has to be concentrated to 99.5% before prilling.MTC-C-IMPROVED PROCESS employs crystallization-remelt prilling route and uses spray nozzles for prilling. The prilling tower is of induced raft type.The solution from gas separator enters lower part of crystallizer, U-FA-201. The upper part is vaccum concentrator with two stage ejectors and barometric condenser.In vaccum concentrator. Operating at 75mm of Hg and 600C, water is evaporated and supersaturated urea solution comes down through barometric low into the crystallizer, where urea crystals grow. The heat required for water evaporation comes from:1. Sensible held of feed urea solution.2. The heat of urea crystallization.3. Heat recovered by urea slurry circulated through high pressure absorber.The crystallizer is operated at 600C and atmospheric pressure, so the slurry leaving the bottom contains 30-35% urea crystal by weight.Hot water from hot water pump is used in jackets of crystallizer and pipe to avoid crystal build up on vessels walls which may cause choking otherwise. The urea slurry is pumped from crystallizer bottom to centrifuges U-CF-201A-E (1000RPM, 43Te/hr of slurry) maintaining minimum recirculation to crystallizer to prevent choking of lines.Biuret remains with mother liquor, which after separation from urea crystals in the centrifuges is recycled back to the system. Because of excess ammonia in reactor biuret, thus recycled is converted back to urea.NH2CONHCONH2 +NH3 2NH2CONH2Urea crystals separated from slurry with 2-4% moisture are discharged to fluididsing dryer UFF-301 at 1100C. The mother liquor flows down to mother liquor tank, provided with steam coils. Mother liquor is pumped back to crystallizer via LCV-207. a part of mother liquor going to low pressure absorber has been cutoff and instead dust chamber overflow solution has been lined up.Air is blown from blower U-GB-301(82360NM3/hr) and heated to 1000C in air heater. This hot air droes the crystals to 0.1% to 0.3% moisture content. Dried crystals are conveyed by a pneumatic duct to cyclones at the prilling tower top. The collected crystals are melted in melter (1370C) and urea melt is sprayed through 12 nos. acoustic granulators. Prills are cooled in fluidizing bed called CFD,installed at the prilling tower bottom. Air/cyclone scrubbed for urea dust separators. Air containing urea dust from P.T column is scrubbed with water and passed through 144 sets of poly urethane filters before exhaust to atmosphere to reduce air pollution.RECOVERY SECTIONThe gases from gas separator are condensed in off gas condenser UEA-406 to 620C and enter the bottom of off gas absorber DA-402(OGA). Condensed liquid flows down to off gas absorber tank UFA-203. After cooling to 360C, liquid is sent to top portion of OGA as absorbent. OGA bottom fluid is recycled as absorbent at OGA middle position (2nd bed).Air from top of OGA is blown to gas separator by GB-401 blower. The gases from low pressure decomposer are absorbed in low pressure absorber (EA-402) bubbling a sparger. Dust chamber over flow solution (10-15% urea) is used as absorbent. Low pressure absorber temperature is controlled at 450C and CO2 concentration 2.2 lit/2.5ml.Solution from LA is pumped by GA-402A/B to high pressure absorber (DA-401) middle through mixing cooler where liquid ammonia is mixed and serves as medium in the absorber.The gases from HD top are bubbled through a sparger in high pressure absorber cooler EA-401, where 65% of CO2 is absorbed. Remaining gases from HAC go to HA and are cooled down to 800C max. in middle cooler at the bottom of HA 35% of CO2 is absorbed in packed bed by a mixture of lean carbamate from low pressure absorber through FCV-401 and liquid ammonia from GA-404A/B( temp. max 600C) through FCV-402. the scrubbed gas then passes through five nos. of condensers(EA-404A-E) and purge condenser EA-403. Liquid ammonia flows down to ammonia reservoir FA-401. Non-condensable gases flow to ammonia recovery absorber. Recovery loop pressure is controlled by PCV-405 at top of EA-405 lV. Cold steam condensate is fed for absorption. Aqueous ammonia is with drawn from recovery absorber bottom by GA-405A/B.OFFSITES AND UTILITIES PLANTSThe 0&U group of plants consist of the following sections : -i) Raw Water Plant.ii) D.M. Water Plant.iii) Instrument .Air Compressor House.iv) Cooling Tower.a) RAW WATER FILTERATION PLANTThis water treatment plant has a design capacity to treat 2400 NM3/hr of raw water into portable occasional over lead of 20%. The plant consists essentially of flash Mixers Clarifloculators, rapid gravity filters and a chemical House comprising of Alum tanks, lime tanks and a chlorine room etc.The raw water from the pumping main is received by the inlet of the RCC Ventury flume. In the ventury flume the calculated amount of alum solution is closed for mixing with the raw water. The chemically treated water then flows to clarifloculators. The pludge thus formed after chemical treatment settles down in the clarifloculator where from it is expelled out while the clear water overflows to the launder leading to filter beds. The filter water is disinfected with the addition of chlorine and then collected in filter eater sump.b) D.M. WATER PLANTD.M. water plant was supplied by M/s Ion Exchange (India) Ltd. It consists of cation units, Degasser Towers, An-ion units. Mixed bed units No.l&2. Filtered water coming from raw water filtration plant is received in filter water reservoir. From reservoir filter water passes through a strongly acidic cat-ion exchange resin where cat-ions like Ca, Ng & Na are removed, the water passes through degasser tower where dissolved, Ce2 is removed. Then water passes through Anion exchange resin and Anion like CI, S, Se4 and silica, are removed in this unit. Free from cations and anions water passes through mixed bed unit No.l, where further removal of cations and anions takes place. Then treated water coming out from MB, unit goes to DM water tank.Return condensate from Ammonia and Urea Plants is collected in D.M. water tank after treatment in cat-ion unit No.2. Then D.M. water is pumped from DM water tank to mixed bed No.2(MB) for further polishing and collected in polish water tank, which is supplied to boilers through Ammonia Plant.INSTRUMENT AIR COMPRESSORS HOUSEThe purpose of this section is to supply instrument air and service air to all the plants. The instrument air compressor house consists of three instrument air compressors and one service air compressor. One is kept in line generally. The compressed air from instrument air compressors at 9.3 kg/cm2 absolute pressure passes through two sets of dryer, which is filled with silica-gel for removal of moisture. Air coming out from dryer is sent to instrument air feeder for supplying to different plants through instrument air receiver in order to drive various valves and instruments.(iii) COOLING TOWERSThe cooling water system provided in NFL, Bathinda is closed re-circulating system supplying cooling water to various consumers in the plant. The system mainly consists of cooling towers, cooling water re-circulation pumps, supply & return headers and cooling water treatment facility.There are three cooling water systems : -C.W. system supplies cooling water to Ammonia Plant.Urea Plant and Boilers, Instrument -Air Compressor, Caustic dissolving facilities & Sulphur Recover Plant.C.W. system supplies cooling water to Crystallization section of Urea Plant.D.M. WATER PLANTWater in its natural form contains no. of dissolved salts such as sulphates, chlorides and nitrates of calcium magnesium and sodium. If water is used as such in the boilers for raising steam, these salts will form scale on the tubes, which in addition to heat losses lead to many other many problems. Hence, removal of these salts from the water becomes quite essential. Ion exchange resign are used for this purpose of salt removal.The de mineralizing water plant of NFL Bathinda was supplied by M/s ION exchange (India) ltd Delhi.It consisted of three units each of cation, anion, mixed bed, four secondary mixed bed and three units of condensate cation. At the time of setting up of a captive power plant, another stream to augment the existing capacity of polish water generation was by M\s BPMEL. It consisted of one unit each of cation, anion, primary mixed bed, two secondary mixed bed and two condensate cations.Filtered water is received from raw water filtration plant into two filtered water reservoir feed water pumps discharge water from these reservoir tom cation units. These are total five feed pumps each having a capacity 0f 130m3/hr and four cation units. Three of these are charged with 13125L of cation resin and fourth unit is having 11900 0f resins. Cation like Na+, Ca++, and Mg++ present in the water are removed in the cation unit once exhausted, these units are regenerated with the counter current flow of dilute sulphuric acid.The present day resins are made of cross linked polystyrene and cross linking is done by di vinyl benzene.Cation resins are made of sulphonated polystyrene SO3H can be represented by as RH.anionic resin is similarly made but is chloromethylated and then is animated. The final product is quaternary ammonium compound a strong base and is represented by ROH.CATION UNIT:In the cation units free H+ ion of the resin is replaced by Ca and Mg or Na ions as per the following reactions.RH + NaCl---------------RNa+ HCl2RH + MgSO4--------------------- R2Mg + H2SO42RH + Ca (HCO3)2---------------------------R2Ca +2CO2 + 2H20Natural salts are converted into respective mineral acid and alkaline salt split into carbon dioxide. The outlet water has low pH.DEGASSER:From the cation units water move to the degasser. Here the free CO2 content of the water is splitted off with the help of air by passing the water over by the rasching ring packed bed. Water from the degasser is received into three Nos. degasser water sump each of having a capacity 40m3 from these sump degassed water pumps discharge water into the anion units. There are total five Nos of pumps each having a capacity of 150M3/ hr.ANION UNITS:Anionic impurities of water beside CO2 and silica are removed in the anionic unit. There are total four No of anionic units. Two anionic units having a capacity 7920L of resin while the two are 5965 and 8400L of resin.