Internship Report of Line 2 Urea Process Formation at NFL,Vijaipur

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Internship report

On

UREA PROCESS DESCRIPTION

LINE-2 PLANT

Submitted in partial fulfilment

Of the requirement for the award of the degree of

Bachelor of Technology

In

MECHANICAL

By

SHUBHAM RAGHUVANSHI

Submitted to

NATIONAL FERTILIZERS LIMITED

VIJAIPUR, GUNA (M.P.) Mr. D.R CHOWDHURY, Chief Manager (HRD)

Mr. R.P GUPTA, Asst. Manager (HRD)

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CERTIFICATE

This is to certify that the Internship project entitled Internship report on

UREA PROCESS DESCRIPTION LINE-2 PLANT AT NATIONAL

FERTILIZERS LIMITED being submitted by SHUBHAM

RAGHUVANSHI, in fulfilment of the requirement for the award of degree of

Bachelor of Technology in MECHANICAL of engineering, has been carried

out under my supervision and guidance. The matter embodied in this thesis

has not been submitted, in part or in full, to any other university or institute for

the award of any degree, diploma or certificate.

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ACKNOWLEDGEMENT

I am thankful to Mr. D.R CHOWDHURY, Chief Manager (HRD), Mr. R.P

GUPTA, ASST.MANAGER(HRD) NATIONAL FERTILIZERS LINITED,

VIJAIPUR, GUNA (M.P.) for giving me an opportunity of one month Internship

at NFL Plant (UREA-2).

I express my gratitude to Mr. R.P Gupta, Asstt.Manager (HRD), NFL Vijaipur,

Guna for his extremely valuable guidance and constant encouragement in my

work.

I am cordially grateful to Mr. S.K RAI, SR.MANAGER (MECHANICAL) UREA-

2, Mr. DHIRAJ, Asst. Manager (MECHANICAL) UREA-2 & Mr. PANKAJ,

MANAGER (MECHANICAL) UREA-2 NATIONAL FERTILIZERS LTD.

Vijaipur, Guna who has given me valuable time for Urea process description &

for preparation of my project work on said topic.

I am also thankful to other Urea-2 Mechanical staff for their Co-operation

during Internship on urea plant

A special Thank you to Mr. Lakhan Raghuwanshi (Treasurer of the Union) for

arranging Boarding and Lodging.

Thanking you

SHUBHAM RAGHUVANSHI

(MECHANICAL)

SIR PADAMPAT SINGHANIA UNIVERSITY

UDAIPUR

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PROFILE OF THE COMPANY

National Fertilizers Limited, Vijaipur unit is one of the four units of M/S

National Fertilizers Limited, a Government of India undertaking with its

corporate office at New Delhi, The other units are located at Nangal and

Bhatinda in Punjab ant at Panipat in Haryana.

National Fertilizers Ltd, Vijaipur unit is one of the four units of M/S National

Fertilizers Limited. With the commencement of commercial production of the

Expansion project the gas based unit at Vijaipur now comprises of two 1520

ton per day (tpd) Ammonia streams and four 1310 Ton per day Urea streams

and related off-site facilities. The gas is being received from the HBJ gas pipe

line being operated by M/s Gas Authority of India Ltd (GAIL) another

government of India undertaking.

The Ammonia stream completed under the Expansion Project can also be

operated with 50 % feed of Naphtha in case of shortage of the gas supply.

The industry also has 3 power plants each of capacity 17 MW and at a time 2

power plants is used and 1 kept for standby purpose.

The line one plants (one stram of Ammonia and two streams of Urea) were

built with a total cost of Rs 533 Crores and the cost of the line two (one

stream of Ammonia and two streams of Urea) was Rs 1067 Crores.

For Both streams of Ammonia plants the consultant have been M/S Haldor

Topose of Den-Mark and M/S Projects Development India Ltd. (PDIL), and for

all other streams of Urea consultant have been PDIL and M/S Snamprogetti of

Italy.

The line one Plants had gone in Commercial Production w.e.f July 1988 and

the Expansion Unit has started the Commercial Production w.e.f 31 March

1997.

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The line one plant have been consistently operating at above 115% of the

rated capacity. The line two plant is also expected to perform similarly.

Vijaipur unit has won several prestigious awards like Best Implemented

Project award given by Ministry of Programme Implementation GOI, National

Safety awards given by National Safety Council GOI and by National Safety

Council(MP).

Pollution control and energy conservation by International Greenland Society

and by Ministry of Power GOI.

NFL, Vijaipur Unit produces Urea in conformance with the standards as set in

Fertilizer Control Order (FCO) issued by Govt. of India. Vijaipur Unit Urea

product is marketed by NFL‟s marketing division sells and distributes Urea to

Institutional buyers and private dealers, NFL Vijaipur has manpower of 1014.

The main product of this industry is Kisan Urea. The total production capacity

of Kisan Urea is 6,261 Tonnes/day which is the second largest production in

the country.

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INTRODUCTION TO THE PLANT

LAND ACQUIRED 506 HECTARES LAND DEVELOPED 269000 CuM EXCAVATION

1457038 CuM & 64333 CuM

CONCRETING

128935 CuM

STRUCTURAL WORK

6880 MT & 4576 MT

EQUIPMENT ERECTION MECHANICAL

12389 MT & 6445 MT

ELEECTRICAL

536 MOTORS

PIPING

505 Inch.KM & 508 Inch.KM

POWER CABLING

600 KM

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UREA was first synthesised in 1828 from ammonium cynate by WHOLER

In 1870 BASSAROW produced urea by dehydration of ammonium carbamate

which is the basis of present commercially process. There was no

breakthrough in urea production commercially till 1920.

The 1st commercially production of urea was in 1922 by DU Pont from nitro

lime at plant in Canada.

The process route which is adopted by the present day plants, was achieved

by I.G.FARBEN in 1922 at plant in Germany.

Properties of Urea:

Molecular weight: 60.047

Melting point at 1 atm: 132.47ºC

Specific gravity at 20ºC: 1.335

Triple point: 102.3ºC

Nitrogen content: 46.6%

Colour: White

Angle of Repose: 23º

Viscosity(at 132.7ºC): 2.58 CP

Crystal Form: Tetragonal-selano hedral

Advantages of Urea:

Nitrogen content is the highest among various nitrogenous

fertilizers(46%).

Cheapest source from transport point of view.

CO2 which is one of the raw materials for the manufacturing of urea is

available at negligible cost from ammonia plant.

It is not subjected to fire or explosion hazard.

It has got better flowing characteristics.

As such it is not toxic and used in preparation of various types of

medicines and in other industries.

Actual demand for Urea started in 1960’s

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Raw materials used:-

The raw materials for the production of Urea are Ammonia (NH3) and Carbon-

di-oxide (CO2). These are obtained by NG / Naphtha, Power, Water. Water

used here is taken from Sanjay Sagar dam.

The process for the production of ammonia and carbondi oxide are :

(A). Ammonia (NH3):- For Ammonia production, we want Nitrogen (N)

and Hydrogen (H). And Nitrogen is present in the air at surplus amount so

Nitrogen is obtained from air and

Hydrogen is obtained from Methane (CH4) by catalytic reforming which is

obtained from Natural Gas (NG) which contains about 85% - 90%. And

GAIL supply the Natural Gas by HBJ pipeline.

(B). Carbon di-oxide (CO2): - CO2 is obtained from the atmosphere or air.

Manufacturing process:-

Urea is manufactured by reacting ammonia and carbon dioxide in autoclave to

form ammonium carbamate. The operating temperature is 1350C and 35 atm

pressure, the chemical reaction is endothermic reaction and so ammonia is

maintained in excess to shift the equilibrium towards urea formation. Urea

production consists of main two reactions.

1. Formation of ammonium carbamate

2. Dehydration of ammonium carbamate to produce molten urea.

Description or Plant Layout:

1.Ammonia pumping : Liquid ammonia is pumped from the multistage

pump which maintain the reaction pressure in the vertical stainless steel

vessel.

2. Carbon dioxide compression: Ammonia plant directly boosts the

carbon dioxide from the compression section as it readily forms at the CO2

section of ammonia production plant.

3. Urea synthesis tower: It is lined with film of oxides to protect form

corrosion. Catalyst bed is placed in the inner side of the autoclave

structure and 180- 200 atm pressure at temperature about 180-200 deg

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centigrade is maintained. Plug flow operation take places and molten urea

is removed from the top of the tower.

4. Distillation tower and Flash drum: This high pressure slurry is flashed

to 1 atm pressure and distilled to remove excess ammonia and

decomposed ammonia carbamated salts are removed and recycled.

5. Vacuum Evaporator: The solution is fed to vacuum evaporator for

concentrating the slurry.

6. Prilling Tower: It is dryer where the molten slurry is passed from top of

the tower into a bucket which rotates and sprinkles the slurry and air is

passed from the bottom. All the moisture is removed as the urea form into

granules during it journey to the bottom of the tower. These granules are

sent by conveyor to the bagging section.

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PUMP

Pumps are in general classified as Centrifugal Pumps (or Roto-dynamic

pumps) and Positive Displacement Pumps.

Centrifugal Pumps (Roto-dynamic pumps)

The centrifugal or roto-dynamic pumps produce a head and a flow by

increasing the velocity of the liquid through the machine with the help of a

rotating vane impeller. Centrifugal pumps include radial, axial and mixed flow

units.

Centrifugal pumps can further be classified as

end suction pumps

in-line pumps

double suction pumps

vertical multistage pumps

horizontal multistage pumps

submersible pumps

self-priming pumps

axial-flow pumps

regenerative pumps

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Positive Displacement Pumps

A positive displacement pump makes a fluid move by trapping a fixed amount

and forcing (displacing) that trapped volume into the discharge pipe.

or

Some positive displacement pumps use an expanding cavity on the suction

side and a decreasing cavity on the discharge side. Liquid flows into the pump

as the cavity on the suction side expands and the liquid flows out of the

discharge as the cavity collapses. The volume is constant through each cycle

of operation.

A positive displacement pump can be further classified according to the

mechanism used to move the fluid:

Rotary-type positive displacement

Reciprocating-type positive displacement

Rotary-type

Rotary-type internal gear, screw, shuttle block, flexible vane or sliding vane,

circumferential piston, flexible impeller, helical twisted roots (e.g. the

Wendelkolben pump) or liquid ring vacuum pumps.

Positive displacement rotary pumps are the pumps move fluid using the

principles of rotation. The vacuum created by the rotation of the pump

captures and draws in the liquid. Rotary pumps are very efficient because

they naturally remove air from the lines, eliminating the need to bleed the air

from the lines manually.

Positive displacement rotary pumps also have their weakness. Because of the

nature of the pump, the clearances between the rotating pump and the outer

edge must be very close, requiring that the pump rotate at a slow, steady

speed. If rotary pumps are operated at high speeds, the fluids cause erosion.

Rotary pumps that experience such erosion eventually show signs of enlarged

clearances, which allow liquid to slip through and reduce the efficiency of the

pump.

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Positive displacement rotary pumps can be grouped into two main types

Gear pump

Rotary vane pump

Gear Pump

Gear pump are the simplest type of Rotary Pumps, consisting of two gears

laid out side-by-side with their teeth enmeshed. The gears turn away from

each other, creating a current that traps fluid between the teeth on the gears

and the outer casing, eventually releasing the fluid on the discharge side of

the pump as the teeth mesh and go around again. Many small teeth maintain

a constant flow of fluid, while fewer, larger teeth create a tendency for the

pump to discharge fluids in short, pulsing gushes.

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Rotary Vane Pump

It consist of a cylindrical rotor encased in a similarly shaped housing. As the

rotor turns, the vanes trap fluid between the rotor and the casing, drawing the

fluid through the pump

Reciprocating-type

Reciprocating-type, for example piston or diaphragm pumps

Positive displacement pumps have an expanding cavity on the suction side

and a decreasing cavity on the discharge side. Liquid flows into the pumps as

the cavity on the suction side expands and the liquid flows out of the

discharge as the cavity collapses. The volume is constant given each cycle of

operation.

The positive displacement principle applies in these pumps:

Rotary lobe pump

Progressive cavity pump

Rotary gear pump

Piston pump

Diaphragm pump

Screw pump

Gear pump

Hydraulic pump

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Vane pump

Regenerative (peripheral) pump

Peristaltic pump

Rope pump

Flexible impeller

Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, will

produce the same flow at given speed (RPM) no matter what the discharge

pressure.

Positive displacement pumps are “Constant Flow Machines”

A positive displacement must not be operated against a closed valve on

the discharge side of the pump because it does not have a shut-off head

like centrifugal pump. A Positive Displacement Pump functioning against

a closed discharge valve will, continue to produce flow until the pressure in

the discharge line are increased until the line bursts or the pump is

severely damaged-or both

A relief or safety valve on the discharge side of the positive displacement

pump is therefore necessary. The relief valve can be internal or external.

The pump manufacturer normally has the option to supply internal relief or

safety valves. The internal valve should in general only be used as a

safety precaution, an external relief valve installed in the discharge line

with a return life back to the suction line or supply tank is recommended.

TYPICAL RECIPROCATING PUMPS

Plunger pumps

Diaphragm pump

Plunger pumps

A plunger pump consist of a cylinder with a reciprocating plunger in it. The

suction and discharge valves are mounted in the head of the cylinder. In the

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suction stroke the plunger retracts and the suction valves open causing

suction of fluid into the cylinder. In the forward stroke the plunger pushes the

liquid out of the discharge valve.

With only one cylinder the fluid flows varies between maximum flow when the

plunger moves through the middle positions, and zero flow when the plunger

is at the end positions. A lot of energy is wasted when the fluid is accelerated

in the piping system. Vibration and “water hammer” may be a serious

problem. In general the problems are compensated for by using two or more

cylinders not working in phase with each other.

Diaphragm pump

In diaphragm pumps, the plunger pressurizes hydraulic oil which is used to

flex a diaphragm in the pumping cylinder. diaphragm valves are used to pump

hazardous and toxic fluids. An example of the piston displacement pump is

the common hand soap pump

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Ammonia Feed Pump

Ammonia feed pump installed at Vijaipur are triplex reciprocating pumps from

M/S Bharat pumps and Compressor Ltd. The pump is coupled with variable

speed drive unit consisting of 3 phase induction motor, hydraulic torque

convertor and gear reducer. Reciprocating pumps are normally used to

handle low flows. The liquid is driven into the cylinder and then pressurised

against the system discharge valve. These pumps produce pulsation flow.

Pulsation may be reduce by the addition of an accumulator. Large

reciprocating pumps are normally specified in triplicate to reduce pulsation.

Torque Convertor

A Torque convertor is a hydrodynamic transmission.

It consist of an impeller, a turbine, a turbine wheel and a stationary guide

wheel. The guide wheel is equipped with adjustable blades for purposes of

control and regulation.

The bladed wheel together with the convertor bowl, from an oil filled circuit.

The operating pressure is produced by a mechanical gear pump. The impeller

is connected to the motor via the input shaft, the turbine wheel to the driven

machine via the output shaft.

There is no mechanical connection or contact between impeller, turbine wheel

and guide wheel.

The guide blades can be adjusted during operation via control piston.

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COMPRESSOR

Centrifugal Compressor

When gas molecules are forced close together, the result will be increase in

pressure. The Molecules get squeezed into smaller volume because of the

force acting upon them. The above process is known as compression.

Following changes takes place during compression:-

a. Volume is reduced

b. Pressure is increased

c. Temperature of gas increases as a result of heat of compression

d. Density increases as the volume decreases

The energy required to compress a gas is dependent upon the amount of gas

compressed, suction temperature and differential pressure between suction

and discharge.

Energy requirement increases as-

-Gas rate increases

-Suction pressure decreases

-Discharge pressure increases

-Suction temperature increases

Advantages of using Centrifugal compressor are:-

a) The centrifugal compressor offers a relatively wide variation in flow with

relatively small change in head.

b) Lack of rubbing parts in the compression stream enables long runs

between maintenance intervals.

c) Large throughputs can be obtained with relatively small plot size. This

can be an advantage where land is valuable.

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d) When enough steam is generated in this process, a centrifugal

compressor will be well matched with a direct connected steam turbine

driver.

e) Smooth, pulsation free flow is characteristic.

Disadvantages:-

a) Centrifugal compressors are sensitive to the molecular weight of the

gas being compressed. Unforeseen changes in molecular weight an

cause pressures to be very low or very high.

b) Relatively small increases in process system pressure drops can cause

very large reduction in compressor throughout.

c) A complicated lube oil system and sealing system is required.

PARTS OF CENTRIFUGAL COMPRESSORS

1. ROTOR

2. CASING(STATOR)

3. LABYRINTH SEAL

4. OIL SEAL

5. RADIAL OR JOURNAL BEARING

6. THRUST BEARING

Rotor consist of shaft, the impellers balancing drum and the thrust collar of

the thrust bearing. The shaft is made from the heat treated alloy steel on to

which the impellers are hot shrunk.

The shrinking of the impeller is necessary to ensure that the impeller does not

get slackened because of centrifugal forces during normal run of the

compressor which would otherwise result in vibration due to high speed of

centrifugal compressor. The rotor is perfectly balanced during assembly in

shop floor to keep down the vibration level. Each individual element on the

rotor is separately balanced to prevent stresses. The impeller components are

made from solid forgings. Before being mounted on the shaft each impeller is

dynamically balanced and tested at a speed 15%higher than the maximum

continuous speed. The spacer sleeves in between the impellers protect the

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shaft from corrosive fluids and also establish the relative position of one

impeller to other. The sleeves are also hot shrunk on the shaft. The purpose

of thrust collar is to transmit the thrust load of the rotor shaft to the thrust

bearing.

Casing design is normally available in two types. Horizontal split casing and

vertically split casing.

Horizontally split casing design is used for the low working pressure below 40

ata. Horizontal split casing are made out of casting in two halves. Main

nozzles and auxiliary connections are provided in the lower casing and the

upper half serves only as a cover which may be lifted by removing the bolts

on parting plane giving free access to the internals of the compressor.

The working range of the compressor is limited due to the problem of sealing

on parting plane.

Vertically split casing design is made of Barrel type construction closed on the

sides by end covers with the help of studs and bolts. This type of construction

is suitable for pressure up to 750 ata. Sealing is provided between the casing

and end covers with the help of endless „O‟ rings and synthetic material.

Labyrinth Seal is used to reduce gas leakage between areas of different

pressure. The labyrinth seal consist of a ring the periphery of which is shaped

on a series of fins having small clearance with the rotor.

These rings are manufactured in 2 halves as four quarters of as soft alloy

resistant to corrosion to avoid damage to the rotor in the event of an

accidental contact.

Journal bearings

The radial bearing at two ends of a casing which support the rotor of a

compressor are-

i. Elliptical Type

ii. Tilting Pad Type

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Tilting Pad Type radial bearings are suitable for applications requiring more

damping characteristics. When the shaft rotates the Pad adjust to dynamic

forces and oil wedge is formed in the direction of rotation.

The shaft will be floating between all the pads while running at high speed and

there will be minimum or no surface contact. During very slow running oil

wedge formation may not be there. Hence the bottom pads of the bearing are

likely to wear slightly. Running compressor at very low speeds may be

avoided because of these reason. The radial or journal bearings are housed

outside the compressor casing and can be inspected without dismantling the

machine. The housing is generally fitted with an atmosphere vent.

Thrust Bearing

The thrust bearing are designed to support the residual axial thrust operating

on the rotor that is not completely balance by the opposite suction and by the

balance drum. In tilting pad thrust bearings, tilting pad adjust to the surface of

the collar because of curved seat. Normally the thrust developed on any

casing is towards low pressure end. However, most thrust bearings are

designed to absorb thrust on either direction. This is accomplished by using

tilting pads on either side of the thrust collar.

Thrust bearings are also equipped with temperature indicator and flow glass

in return line and pressure regulator on feed lines.

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TURBINE

A Turbine is a rotary engine that extracts energy from a fluid flow and

converts it into useful work.

The simplest turbine has one moving part called a rotor assembly, which is a

shaft or drum with blades attached. Moving fluid acts on the blades so that

they move and impart rotational energy to the rotor. Early turbine examples

are windmills and waterwheels.

Gas, steam, and water turbines usually have a casing around the blades that

contains and controls the working fluid. Credit for invention of the steam

turbine is given both to the British engineer Sir Charles Parsons (1854–1931),

for invention of the reaction turbine and to Swedish engineer Gustaf de

Laval (1845–1913), for invention of the impulse turbine. Modern steam

turbines frequently employ both reaction and impulse in the same unit,

typically varying the degree of reaction and impulse from the blade root to its

periphery.

A device similar to a turbine but operating in reverse i.e. Driven, is a

compressor or pump. The axial compressor in many gas turbine engines is a

common example. Here again, both reaction and impulse are employed and

again, in modern axial compressors, the degree of reaction and impulse

typically vary from the blade root to its periphery.

Claude Burdin coined the term from the Latin turbo or vortex during an 1828

engineering competition. Benot Fourneyron, a student of Claude Burdin, built

the first practical water turbine

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Theory of Operation

A working fluid contains potential energy (pressure head) and kinetic energy

(velocity head).The fluid may be compressible or incompressible. Several

physical principles are employed by turbines to collect this energy.

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Impulse Turbine

These turbines change the direction of flow of a high velocity fluid or gas jet.

The resulting impulse spins the turbine and leaves the fluid flow with

diminished kinetic energy. There is no pressure change of the fluid or gas in

the turbine blades (the moving blades), as in the case of steam or gas turbine,

the entire pressure drop takes place in the stationary blades (nozzle).

Before reaching the turbine, the fluid‟s pressure head is changed to velocity

ead by accelerating the fluid with a nozzle. Pelton wheels and de Laval

turbines use this process exclusively. Impulse turbines do not require a

pressure casement around the rotor since the fluid jet is created by the nozzle

prior to reaching the blading on the rotor. Newton‟s second law describes the

transfer of energy for impulse turbines.

Reaction Turbine

Reaction turbines develop torque by reacting to the gas or fluid's pressure or

mass. The pressure of the gas or fluid changes as it passes through the

turbine rotor blades. A pressure casement is needed to contain the working

fluid as it acts on the turbine stage(s) or the turbine must be fully immersed in

the fluid flow (such as with wind turbines). The casing contains and directs the

working fluid and, for water turbines, maintains the suction imparted by the

draft tube. Francis turbines and most steam turbines use this concept. For

compressible working fluids, multiple turbine stages are usually used to

harness the expanding gas efficiently. Newton's third law describes the

transfer of energy for reaction turbines.

In the case of steam turbines, would be used for marine applications or for

land-based electricity generation, a Parsons type reaction turbine would

require approximately double the number of blade rows as a de Laval type

impulse turbine, for the same degree of thermal energy conversion. Whilst this

makes the Parsons turbine much longer and heavier, the overall efficiency of

a reaction turbine is slightly higher than the equivalent impulse turbine for the

same thermal energy conversion.

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Velocity triangles can be used to calculate the basic performance of a turbine

stage. Gas exits the stationary turbine nozzle guide vanes at absolute

velocity Va1. The rotor rotates at velocity U. Relative to the rotor, the velocity

of the gas as it impinges on the rotor entrance is Vr1. The gas is turned by the

rotor and exits, relative to the rotor, at velocity Vr2. However, in absolute terms

the rotor exit velocity is Va2. The velocity triangles are constructed using these

various velocity vectors. Velocity triangles can be constructed at any section

through the blading (for example: hub, tip, midsection and so on) but are

usually shown at the mean stage radius. Mean performance for the stage can

be calculated from the velocity triangles, at this radius, using the Euler

equation:

Hence:

where:

specific enthalpy drop across stage

turbine entry total (or stagnation) temperature

turbine rotor peripheral velocity

change in whirl velocity

The turbine pressure ratio is a function of and the turbine efficiency.

Modern turbine design carries the calculations further. Computational fluid

dynamics dispenses with many of the simplifying assumptions used to derive

classical formulas and computer software facilitates optimization. These tools

have led to steady improvements in turbine design over the last forty years.

The primary numerical classification of a turbine is its specific speed. This

number describes the speed of the turbine at its maximum efficiency with

respect to the power and flow rate. The specific speed is derived to be

independent of turbine size. Given the fluid flow conditions and the desired

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shaft output speed, the specific speed can be calculated and an appropriate

turbine design selected.

The specific speed, along with some fundamental formulas can be used to

reliably scale an existing design of known performance to a new size with

corresponding performance.

Off-design performance is normally displayed as a turbine map or

characteristic.

Types of Turbines

Steam Turbines

Steam turbines are used for the generation of electricity in thermal power

plants, such as plants using coal, fuel oil or nuclear power. They were once

used to directly drive mechanical devices such as ships' propellers (for

example the Turbinia, the first turbine-powered steam launch,) but most such

applications now use reduction gears or an intermediate electrical step, where

the turbine is used to generate electricity, which then powers an electric

motor connected to the mechanical load. Turbo electric ship machinery was

particularly popular in the period immediately before and during World War II,

primarily due to a lack of sufficient gear-cutting facilities in US and UK

shipyards.

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Gas Turbines

Gas turbines are sometimes referred to as turbine engines. Such engines

usually feature an inlet, fan, compressor, combustor and nozzle (possibly

other assemblies) in addition to one or more turbines.

Transonic

Transonic turbine. The gas flow in most turbines employed in gas turbine

engines remains subsonic throughout the expansion process. In a transonic

turbine the gas flow becomes supersonic as it exits the nozzle guide vanes,

although the downstream velocities normally become subsonic. Transonic

turbines operate at a higher pressure ratio than normal but are usually less

efficient and uncommon

Contra-rotating

Contra-rotating turbines. With axial turbines, some efficiency advantage can

be obtained if a downstream turbine rotates in the opposite direction to an

upstream unit. However, the complication can be counter-productive. A

contra-rotating steam turbine, usually known as the Ljungström turbine, was

originally invented by Swedish Engineer Fredrik Ljungström (1875–1964) in

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Stockholm, and in partnership with his brother Birger Ljungström he obtained

a patent in 1894. The design is essentially a multi-stage radial turbine (or pair

of 'nested' turbine rotors) offering great efficiency, four times as large heat

drop per stage as in the reaction (Parsons) turbine, extremely compact design

and the type met particular success in backpressure power plants. However,

contrary to other designs, large steam volumes are handled with difficulty and

only a combination with axial flow turbines (DUREX) admits the turbine to be

built for power greater than ca 50 MW. In marine applications only about 50

turbo-electric units were ordered (of which a considerable amount were finally

sold to land plants) during 1917-19, and during 1920-22 a few turbo-mechanic

not very successful units were sold.Only a few turbo-electric marine plants

were still in use in the late 1960s (ss Ragne, ss Regin) while most land plants

remain in use 2010.

Statorless

Statorless turbine. Multi-stage turbines have a set of static (meaning

stationary) inlet guide vanes that direct the gas flow onto the rotating rotor

blades. In a statorless turbine the gas flow exiting an upstream rotor impinges

onto a downstream rotor without an intermediate set of stator vanes (that

rearrange the pressure/velocity energy levels of the flow) being encountered.

Water turbines

Pelton turbine, a type of impulse water turbine.

Francis turbine, a type of widely used water turbine.

Kaplan turbine, a variation of the Francis Turbine.

Uses of Turbines

Almost all electrical power on Earth is produced with a turbine of some type.

Very high efficiency steam turbines harness about 40% of the thermal energy,

with the rest exhausted as waste heat.

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Most jet engines rely on turbines to supply mechanical work from their

working fluid and fuel as do all nuclear ships and power plants.

Turbines are often part of a larger machine. A gas turbine, for example, may

refer to an internal combustion machine that contains a turbine, ducts,

compressor, combustor, heat-exchanger, fan and (in the case of one

designed to produce electricity) an alternator. Combustion turbines and steam

turbines may be connected to machinery such as pumps and compressors, or

may be used for propulsion of ships, usually through an intermediate gearbox

to reduce rotary speed.

Reciprocating piston engines such as aircraft engines can use a turbine

powered by their exhaust to drive an intake-air compressor, a configuration

known as a turbocharger (turbine supercharger) or, colloquially, a "turbo".

Turbines can have very high power density (i.e. the ratio of power to weight,

or power to volume). This is because of their ability to operate at very high

speeds. The Space Shuttle's main engines used turbopumps (machines

consisting of a pump driven by a turbine engine) to feed the propellants (liquid

oxygen and liquid hydrogen) into the engine's combustion chamber. The liquid

hydrogen turbopump is slightly larger than an automobile engine (weighing

approximately 700 lb) and produces nearly 70,000 hp (52.2 MW).

Turboexpanders are widely used as sources of refrigeration in industrial

processes.

Military jet engines, as a branch of gas turbines, have recently been used as

primary flight controller in post-stall flight using jet deflections that are also

called thrust vectoring. The U.S. FAA has also conducted a study about

civilizing such thrust vectoring systems to recover jetliners from catastrophes.

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CONCLUSION

NFL is known in the industry for its work culture, value added human

resources, quality management safety, environment, concern for

ecology and its commitment for social upliftment. All NFL plants are

certified under ISO 9001 for compounding international quality

standards and international environmental standards viz. ISO-14001.

NFL is equality concerned about the safety of its plants and people and

accordingly implemented internationally accredited ohsas-18001 safety

standard ISO-9001:2000, NFL has become the first fertilizer company

in the country for total business covered under ISO-9001 certification.

Nfl has well laid policies namely:

a) environment policy

b) quality policy

c) energy policy

d) health and safety policy

Welfare of the employees are given the top most priority in the nfl and

its vibrant cohesive social fabric is one of its most treasured asset.

Apart from producing urea, most popularly known amongst the farmers

by its brand name-“KISAN UREA‟‟, it also produces and markets

number of industrial products like, nitric acid, ammonium nitrate,

sodium nitrite, sulphur, methanol, liquid nitrogen, liquid oxygen, argon

gas etc.

Nfl operates a bio-fertilizer plant of capacity 100 mt/annum at its

vijaipur unit. In this plant three strains of bio-fertilizer namely, psb,

rhizobium and azotobacter are produced.

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Nfl is the first company to be permitted by govt.of india to produce and

market “neem coated urea”. The company is also carrying out research

and development activities is zincated and sulphur coated urea.

Nfl is in the advance stage of implementing mega revamp of its nangal

,bathinda and panipat unit by way of changing over the feed stock from

fuel oil to natural gas.

Because of its excellent track record and outstanding work culture, the

govt. of India has chosen NFL as one of its partners in its decision for

revival of eight closed/sick fertilizer units of fci/hfc plants. As a result,

NFL has already initiated measures relating to barauni and

ramagundom units.

In the financial performance front, NFL has always remained a leader. For

the financial year 2006-2007,profit before tax is about Rs 264 Crore and

sales turnover is about Rs 3866 Crore. And all these achievements are

being realised in a 100% controlled pricing mechanism.