internship report of line 2 urea process formation at nfl,vijaipur
Post on 30-Nov-2015
201 Views
Preview:
DESCRIPTION
TRANSCRIPT
1
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)
2
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.
3
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
4
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.
5
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.
6
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
7
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
8
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
9
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.
10
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
11
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.
12
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.
13
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
14
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
15
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
16
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.
17
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.
18
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
19
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
20
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.
21
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
22
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.
23
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.
24
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
25
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.
26
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
27
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.
28
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.
29
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.
30
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.
top related