(142276387) 102336953 Training Report at Nfl Panipat

8/13/2019 (142276387) 102336953 Training Report at Nfl Panipat

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INTRODUCTION OF NFL

National Fertilizer Limited was established in 23th August 1974, to set up

two fuel oil based plants at Bhatinda(Punjab) and Panipat (Haryana). Both of

them were commissioned in 1979. The Nangal fertilizer plant of fertilizer

corpoartion ofIndia (FCI) has been merged with NFL in 1978 on the

recoganition of FCI and NFL group of companies. Later NFL executed its gas

based plant at Vijaipur(MP) on HBJ gaspipe line.Vijaipur plant had gone in

commercial production in july,1988. NFL is now operating three fuel oil based

plants located at Panipat, Bhatinda, Nangal and gas based plant at

Vijaipur.

NFL prod uce s two popular brands of chemical fertilizer i.e. Kisan Khad (Calcium

A mmonium Nitrate-CAN) and Kisan Urea. Besides the fertilizers it manufacturesand mar ets the industrial products(Liquid Oxygen, Liquid Nitrogen, Nitric

Acid, Methanol, Argon) and byproducts (Sulphur). NFL had signed a mamorandum

of Understanding with the governmet of India in 1991 -92 all the years,

after signing the MOU , government has rated the performance of the

company as Excellent. Comapany has been performing at high level of capacity

utilization over the years.

FERTILIZER, INDUSTRIAL PRODUCTS AND SERVICES

Kisan Urea and Kisan Khad :- NFLs popular brands are sold over a large

marketing territory spanning the length and breadth of the company. The

company also manufactures and markets Biofertilizers and a wide range of

industrial products like Methanol, Nitric Acid, Sulphur, Liquid Oxygen etc.

Kisan

Urea

Kisan Urea is a highly concentrated solid nitrogenuous fertilizer, containing

46.0%. It is completely soluble in water hence nitrogen is easily available

to crops. It contains Nitrogen in amide form which changes to ammonical


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forms and is retrieved by soil collides for longer duration. Urea is avilable

in Granular form and can be applied by drill and broadcasting. Kisan Urea is

ideally suited for all types of crops and for foliar spray, which instantly

removes nitrogen deficiency. Kisan Urea also has a strong and long lasting

effect on crop resulting in bumper crops.

NATIONAL FERTILIZER LIMITED

INTRODUCTION OF PANIPAT UNIT

The panipat unit if NFL is situated on National Highway no 1 and Delhi-

Amritsar railway trunroute. Panipat city is about 90 Km from Delhi and is

covered in National Capital Region. Panipat is a historical city , which was

the scene of historical battles.

Government of India passed a project on 10/2/1975 and contruction was

started fr om 30/4/75. The project was completed on 2/9/78 i.e in 40

months. TOYO Engineering Corporation, Japan and Engineers India Limited was

the main con tractors. Total expense on the project was of 221.33 crores of

which 56.45 crores was in t he form of forgien investment. Urea production

was started from 1/9/79. Till now NFL has produced 85 La h Metric Tons KisanUrea.

Performance of the unit in all the areas of its performance has also been

acknowledged. It has won number of awards and recoginition in the field of

production, safety, innovation, environment protection, s ill etc. The unit

is well known for its commitment towards environment protection and social

welfare in the region.

The brand name of Urea produced is KISAN UREA

Plant capacity of NFL Panipat is of 5,11,500 tons Kisan Urea (46.5% N) PA.

Capacity of Ammonia plant is 900 metric tons per day.

Capacity of Urea plant is 1650 metric tons per day.


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RAW MATERIAL REQUIRED

For the production of 900 Metrictons/day of Ammonia and 1650 Metrictons/day

of Urea following raw materials are required.

FUEL OIL : 910 metrictons/day

COAL : 1650 metrictons/day

WATER : 17 metrictons/day

ELECTRICITY : 26 MWH

Feed stock (Fuel oil ) is obtained from the refineries like IOCL Panipat and

IOC L Mathura

VARIOUS SECTIONS OF PANIPAT UNIT ARE

AMMONIA PLANT

UREA PLANTARGON RECOVERY PLANT

SULPHUR RECOVERY PLANT

DM PLANT

EFFULENT PURIFIER PLANT

CAPTIVE POWER PLANT

The plant is equipped with latest Mechanical and Electrical control system inwh ich microprocessors are used.

AMMONIA PLANT

The Amonia plant is based on fuel oil as feed stoc and is designed to

produce 900 MT/ DAY of ammonia. The Fuel Oil are low sulphur heavy sto e (LSHS)

is partially oxidized in the Gasification Reactors at 1350 0C by shell

gasification process. The raw gas produce in the reactors mainly consist of

H2, CO , CO2, and H2S. The heat generated in the process is recovered in the

waste heat boilers to produce high pressure steam at 100 Kg/Cm2. About 80 %

of the carbon produced in the Gasification Reactors is recycled along with

the feedstock.Hydrogen Sulphide (H2S) in the raw gas is removed by the

absorption in cold Methanol in Desulphurisation Section of Rectisol. The

Carbon Monooxide in the desulphurised gas is converted to carbon dioxide by

double stage CO - shift conversion. The CO2 is later removed from the


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process gas in Decarbonation section of the rectisol. H2S and CO2 from the raw

gas are removed by low temp methanol in the rectisol and both gases are

recovered by the regeneration of methanol at low pressure. H2S in the form

of clause gas is sent to Sulphur Recovery plant for the recovery of sulphur.

The CO2 gas is sent to the Urea plant for synthesizing with ammonia to

manufacture Urea. An absorption refrigeration unit provides refrigera

tion in the rectisol section.

The process gas from the rectisol section is sent to the nitrogen wash

unit to

remove the traces of impurities by liquid nitrogen wash. Nitrogen is

further a

dded to the process gas to obtain a ratio of 3:1 of N2 and H2. This synthesis

ga

s mixture is compressed to 230 Kg/Cm2 pressure and synthesis of N2 and H2 is

car

ried out in the Haldor Topsoe Loop in a radial flow Ammonia Convertor and

Ammo

nia is produced. Oxygen requirement and Nitrogen requirement is met by an

air se

paration unit. In ASU the atmospheric air is compressed in HP and LP

distilation


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columns at cryogenic

temperatures. SULPHUR RECOVERY PLANT

Sulphur is present in the fuel oil used as feedstoc for the manufactureof

ammo nia. Clause gas rich in hydrogen sulphide is obtained in the rectisol

section of the Ammonia plant. Clause gas is sent to sulphur recovery plant

and is burnt an

d partialy oxidised to SO2 in Acid Gas Heat Exchanger. It is followed by

reactio n between H2S and SO2 to form elemental sulphur. After separating

sulphur by con densing the residual H2S reacts with SO2 to form more sulphur

in two catalytic r eactors in series. The unconverted waste gas is burnt in

the incinerator and hea t is removed in heat recovery exchanger, where low

pressure steam is produced. T he sulphur recovery plant serves the double

purpose i.e. to recover costly sulph ur and to prevent pollution.

UREA PLANT

Urea plant is designed to produce 1650 TPD based Mitsui Toatsu Total Recycle C

Imp roved process. The Ammonia and Carbondioxide produced in Ammonia plant are

press urised to about 250 Kg/Cm2. Synthesis ta es place in the Urea reactor,

where Amm

onia and CO2 reacts at 250 Kg/Cm2 pressure and 200 0C temperature to

produce Ure a. The reactor outlet products are then decomposed . The urea

solution produced in this process is crystallised in vacumn crystallizer.

Crystal slurry is centri fugated to separate crystals, which are then dried

in the dryer and pneumaticall y conveyed to the top of Prilling Tower. Urea

crystals are melted in the Melter and the molten urea is sprayed through

Acoustic Granulators from 68 meter high p rilling tower.Urea in the form of

prills is collected at the bottom of the towe r on CFD bed, where it is

cooled by air. Product Urea is then sent to bagging pl ant and bagged in 50

Kg bags.

CAPTIVE POWER PLANT


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Due to improper supply from northern grid the plant was facing the shortage

of e lectricity, resulting in the loss of production. To overcome this

problem a Capt ive Power plant was made.

The capacity of each boiler of power plant is 210 tons/hr. Each generator

has pr oduction capacity of 15 MWH. Stable electricity supply has resulted in

increased production. The plant is now self dependent in this field.

SALIENT FEATURES OF THE PLANT

ANNUAL CAPACITY

511500 MT IN TERMS OF UREA

235290MT IN TERMS OF AMMONIA

ANNUAL REQUIREMENT OF RAW MATERIAL FUEL

OIL/LSHS : 3,00,000 MT

COAL : 5,45,000 MT

POWER : 2,18,000 MWH

WATER : 5,630 MILLION GALLONS

ESTIMATED COST Rs 182.88 CRORES

FOREIGN EXCHANGE Rs 56.45 CRORES

LAND 442 ACRES-PLANT

131 ACRES - TOWNSHIP


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PLANTS AND THEIR CAPACITIES

PLANT CAPACITY

AMMONIA PLANT 900 MT per day

UREA PLANT 1550 MT per day

SULPHUR RECOVERY PLANT 26.5 MT per day

STEAM GENERATION PLANT 3 x 150 MT per hour

CAPTIVE POWER PLANT 2 x 15 MWH

COAL HANDLING PLANT 150 & 250 MT per hour

BAGGING PLANT 4000 MT per hour

EFFLUENT TREATMENT PLANT 200 cubic meter per hour

RAW WATER PLANT 2400 cubic meter per hour

PLANT LAYOUT:-

AMMONIA PLANT

PROCESS DESCRIPTION: -

The plant has a production capacity of 900 metric Tons per stream day

of liquid ammonia by one train based on the SHELL Gasification Process for

gasific ation of heavy oil and carbon recovery, LURGI-Rectisol Process for

desulphurizat ion and carbon dioxide removal and Ammonia synthesis process

starting with heavy oil feedstoc and consists of the following section.

1. Air separation section

2. Shell gasification and carbon recovery section

3. Desulphurization section (Rectisol process)

4. Shift conversionsection

5. CO2 removal section (Rectisol process)


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6. Nitrogen washing section

7. Ammonia synthesis section including refrigeration section

Air Separation Unit: -

There are theoretically three methods of obtaining oxygen

-Electrical : Water electrolysis

-Mechanical : Air centrifugation

-Chemical : Solubility in various liquids separation by passing through

p

orous

Materials.

But the only one which up to now is used on an industrial

scale i s the one consisting in extracting oxygen from air by low-pressure

distillation column.

This section explains the various parts of the plant, which

shall be described in the following section.

Air composition:-

Air is generally a mixture of 2 gases: Oxygen and Nitrogen in the

follo


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wing proportions in the volume:

-1/5th Oxygen (O2), exactly 20.93%

-4/5th Nitrogen (N2), exactly 78.03%

It also comprises various other components which are present in

constant

proportions such as the 5 rare gases:

Argon (Ar) 0.93%

Neon Ne 1/60 000 0.0015%Helium (He) 1/200,000 about 0.0005%

Krypton (Kr) 1/1,000,000 about 0.0001%

Xenon (Xe) 1/11,000,000 about 0.000008%

And in variable quantities:

Water vapors (H2O)

Carbon dioxide (CO2: about 0.03%)

Hydrocarbons, acetylene (C2H2)

Ozone (O3).

Lastly traces of hydrogen and of oil if the air has been handled by lubricated

m

achines.

Air separation unit is provided for getting oxygen gas and nitrogen

gas from air. Produced oxygen gas is led to the reactors in SHELL Gasification

proc ess where it contributes to Partial oxidation of feed oil. On the other

hand nit rogen gas after being liquefied is mainly sent to Nitrogen Washing

Unit to purif y synthesis gas. Some of the nitrogen gas is also used as

utility, e.g. as compr essor sealing gas. Air chiller further cools the feed

air first cooled by precoo ler, which is an evaporator of refrigeration unit

in this Air Separation Unit. T hen the air passes throughair dryers filled

with molecular sieves and alumina g el for drying by adsorbent down to

extremely low dew point and also for complete

removal of CO2. The absorbersare alternately used two at a time with the

other going through a desorption process for regeneration by the dry waste

gas extract ed from the unit. After removal of water and CO2 by the

absorbers, the air is fe


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d into cold box.

The cold air is liquefied in the liquefiers by heat exchange with

the

waste N2, O2 and pure N2 streams from the rectifying columns, and then is led

to

the lower rectifying column. The air for the expansion turbine is extracted

fro

m air heat exchanger and combined with cold air from lower rectifying column.

Before combined with the air from air heat exchanger the air from recti

fying column is warmed by heat exchanger with pure nitrogen gas from the N2

Wash

ing Unit. Because the turbine can be operated at rather higher temp. The

expansi

on turbines wor effectively and provide necessary refrigeration for the

unit.

The exhaust air from the expansion turbine is led to the middle part

of

upper rectifying column. The rectifying column comprises a lower column wor ing

at about 6 g/cm2G and upper column wor ing at about 0.8 g/cm2G and a main

cond

enser. Air from the air heat exchanger first enters the bottom of lower

rectifyi

ng column and reaches the main condenser after rising up through the lower

colum

n.

At the lower column, air is preliminarily separated to the N2 and O2

rich

liquid air. At the main condenser, N2 is liquefied by heat exchanger with theli

quid O2. As a result, liquid air of about 40% O2 purity is obtained at the top

a

nd middle of the lower column.

The liquefied air and N2, thus obtained by preliminary separation in the

lo

wer column, are sent respectively at the liquid state to the upper column.


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The liquefied air withdrawn from the bottom of lower column passes

through o

ne of the two alternately operating hydrocarbon absorber and liquid air

filters

to remove any possible contamination of hydrocarbon. It is then super cooled

aga

inst waist N2 from the upper column in the liquid air super cooler before

being

expanded top the pressure of the upper column through the expansion valve

which

automatically controls the liquid level at the bottom of lower column and fed

to

the upper column.

Liquid N2 withdrawn form the middle of the lower column is fed to the

upper


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column through the expansion valve. Liquid N2 withdrawn from the top of

lower c olumn is super cooled in the N2 super cooler and fed to the upper

column through the expansion valve.

These liquid air and liquid N2 that are fed to the upper column are

rectifi ed further by repeated rectifying operation. Finally, liquefied O2 of

a specifie d purity us obtained in the main condenser.

A part of the liquid O2 continuously circulated by liquid O2 pump inorder to remove remaining hydrocarbons in circulating absorbers. The waste

N2 was is w ithdrawn from the middle part of upper column and warmed in the

liquid air super cooler and air heat exchanger then extracted from cold box.

SHELL GASIFICATION AND CARBON RECOVERY PROCESS: -

The raw synthesis gas is produced by gasification of the heavy oil with

O2 and steam in three parallel oil gasification reactors, using the shell

parti

al oxidation

process.

Desulfhurization

process:

This process is done to remove the sulphur compounds, as they are

har mful in next processes. Therefore we remove sulphur which is in the form

of H2S and COS from the raw gas which are purified by LURGI-RECTISOL physical

absorptio n process which is carried out at low temperature and high

pressure in the prese nce of an organic polar solvent, methanol. The raw gas

from the shell gasificati on process enters desulfurisation section of

Rectisol process at about 48 g/cm2

G and at

45C.

After cooling to about -22C in H2S absorber feed/effluent heat exchanger A-

EA201A

, B and H2S absorber feed NH3, chiller A-EA202 with cold gas and evaporating

NH3


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, the gas charged to H2S absorber A-DA201 where H2Sand COS are reduced to 0.4

pp

m by being washed with methanol. The desulfurised gas after being heated in

H2S

absorber feed/effluent heat exchanger A-EA201A,B is sent to shift

conversion.

The lean methanol solvent for desulfurisation is ta en from the N2 stripping

fro

m CO2 regeneration A-

DA402.

From the bottom of the upper part of H2S absorber the fat methanol solvent

passe s to H2S flash column A-DA202 where it is flashed in two pressure

stages.

A split flow of regenerated methanol from the vacuum stage of CO2 regenerator

A- DA402 is charged to the top of H2S flash column by low-pressure methanol

pumps a nd to free the off gas to the incinerator at the sulfur recovery

unit up to 1000 ppm H2S, so that the methanol will be enriched with H2S.

Then the methanol solvent is supplied to H2S hot regenerator after being

warmed up in lean/semi lean methanol heat exchanger. After complete

regeneration the le an solvent is pumped through lean/semi lean methanolHeat exchanger, lean methanol NH3 chiller and lean methanol heat exchanger

where it is cooled down and is fed bac to the top of CO2 absorber A-DA401

for CO2 fi ne wash.

The flash gas of the first let down stage of H2S flash column and CO2

regenerato r are combined and recompressed by recycle gas compressor into

the raw gas. On t he other hand H2S rich gas is withdrawn from hot

regenerator reflux drum and sen t to the sulfur recovery plant to recoverthe sulfur as element.

CO-SHIFT CONVERSION PROCESS: -

In the shift conversion section, CO off desulfurisation process

ga s reacts with stem to produce H2 and CO2. the shift reaction ta es place


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under t he proper tem. And pressure conditions in the presence of suitable

catalysts, ac cording to the following equation.

CO + H2O H2 +CO2

Excess stem is to be introduced to prevent the carbon formation and also

to a

chieve higher reaction efficiency to the right hand side of the above

equation b

ut there is a certain limit of

the


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range in the quantity of the excess steam, as the time of contact between

gases and catalyst is reduced if too much excess steam exist.

This reaction is reversible. Equilibrium towards H2 production is favored by

lo w temperature, while reaction rate is favoredby high temperature. The

actual sh ift reaction ta es place at 350 to 500C in the presence of iron

chromium catalyst

.

In actual processing, the desulfurisation process gas from the

desulfurisatio

n section enters the Humidifier A-DA301, where it contacts hot water by counter

flow and is saturated with steam at 210C, the gas is heatedup by No.1 and No.

2

shift converter feed gas heaters A-EA301 and A-EA302A,B.

Then in order to achieve proper steam to dry gas ratio superheated steam

and

process condensate are injected into this gas before being introduced to the

shi

ft converter A-DC301.

The shift reaction proceeds in two stages of the shift converter at the

outle

t of the first stage CO content in the gas is reduced to 12 to 13%.

Hot gas from the outlet of the first stage is sent to No.2 shift

converter fe

ed gas heater to be cooled till 360C, which is suitable for second stage

reaction

.

The second stage inlet temperature is controlled by the heat exchanger

bypas s and/or process condensate quench.

In the second stage, the shift reaction is further promoted until the CO

cont ent in the gas is decreased up to3.5 volume%.

The outlet gas from the shift converter enters No.1 shift converter feed

gas heater whereit

heats up shift converter feed gas, and is fed to the


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humidifier feed water heater A-EA303 and then to the dehumidifier A-DA302

where it is coole d down to about 186C after contact with water by counter

flow.

The outlet gas from the dehumidifier is sent to the absorption

refrigeration until to be utilized as a heating source of the NH3 desorber.

Further more, thi

s gas is used to generate the 3 g/cm2 G steam in the low-pressure boiler and

the n heat up boiler feed water in the shift converter effluent economizer

A-EA306 a nd finally is cooledby cooling water in the shift converter

effluent cooler. The converted gas, after being cooled to ambient

temperature is send to the Decarbonationprocess.

CO2 Removal Process: -

The CO2 of CO shift effluent gas is purified by LURGI-RECTISOL phy

sical absorption process, which is carried by the same methanol solution as

desu lfurisation process but at rather lower temperature. The gas from shift

conversi

on enters the CO2 removal section at about 45C. after cooling to app. -25C in

CO2 absorber feed ammonia chiller A-EA 402 with purified gas from N2 washing

unit, C

O2 gas and evaporating ammonia, the gas is charged to CO2 absorber where

CO2 is reduced to 10 ppm by absorption in the methanol at low temperature.

The lean methanol regenerated at H2S hot regenerator is fed to the top

of CO2 absorber for fine absorption at low temperature and the methanol

partly rege

nerated in the N2 stripping section of CO2 regenerator is charged to the

middle of CO2 absorber. In the lower part of CO2 absorber the heat of

absorption is ta en away in CO2 absorber circulation chiller.

The loaded methanol from the bottom of CO2 absorber is flashed in two

pressu re stages and finally stripped with pure N2 in CO2 regenerator.


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In the first bottom flashed stage of CO2 regenerator, the CO absorbed

noble hydrogen gas flashes and after washed by a small load of lean methanol

from N2 s tripping section to absorb the CO2 content of the expanded gas,

returns to the c rowd gas by recycle gas compressor together with the flash

gas from H2S flash co lumn.


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Approximate 25800 Nm3/hr of CO2 gas is sent to urea plant and the CO2 removal

se ction shall be capable of producing 10% additional CO2 over and above that

requi re for production of 1550 MT/ day urea. The quality of this additional

CO2 gas s hould be same as required for the production of Urea.

The low temperature in the Rectisol plant is maintained by the no. of

ammoni a chillers, the required ammonia absorption refrigeration unit is

operatedon th e waist heat of CO shifted gas.

To eliminate icing of the water vapor in the raw gas below 00Cat the

cooling down stage will the absorption temperature, a little methanol

injected into the respective gas streams. The

Nitrogen washing

unit

The CO contained about 5.2% in the CO2 absorption effluent raw gas,

is washed by liquid N2 at N2 washing unit. And also the N2 required for NH3

synthes is is mixed here.

The raw gas from the CO2 removal section first enters molecular sieves

adsorb er unit, where residual CO2, CH3OH are removed to prevent plugging in

the proces s.

Principle: -

Raw synthesis gas coming from Rectisol decarbonation section at 39.5

gs/cm2 and 55 C contains following impurities.

CO 5.21 vol.%

Ar 0.38 vol.%

CH4 0.50 vol.%

CO2 10 ppm

CH3OH 100 ppm

NOX 0.02 ppm

Purification of raw SYN gas is done in following steps: -

1. Purification by adsorption on molecular sieves- CO2, CH3OH and active

ca

rbon (NO, NO2).

2. Cooling down by countercurrent heat exchange with product gas coming

out


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of N.W.U and there by condensing some of the impurities (CO, H2S and COS) at

1900C.

3. Purification by washing with liquid N2 in a distillation

column.

In the cold box the raw gas goes in first and second raw gas heat

exchanger

and made of aluminum plates. The raw gas has a temperature of about 190C at

the ou

tlet of the second raw gas heat exchanger and is fed to the N2 washing

column.

In the N2 washing column, impurities such as CO, Ar, CH4 are liquefied and

t

a en out as tail gas, since feed gas is washed by super cooled liquid N which

sp

ray from the top of column. The purified gas, which is mixture of H2 and N2,

can

be obtained from the top of the N2 washing column and gives it coldness to

the

raw gas and N2 gas while passing heat

exchanger.Before leaving the unit, purified gas is added to N2 to ma e the

proportion o

f H2 and N2 ratio 3:1 and fed to NH3 synthesis

section.

In this process, the purified gas is also used to compensate the frigory

of t

he Rectisol section. The residual condensate liquid in the N2 washing columnflo

ws into second and first tail gas heat exchanger and be sent out as tail

gas to

the steam super heater for fuel through HCN stripper. Waist gas blower and

waste

gasholder are provided in tan yard, for buffering.


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The liquid N2 which had been liquefied and super cooled during the heat

excha

nging in the first and second tail gas heat exchangers meet the liquid N2 for

co

ld compensation coming from the air separation unit and both are supplied,

as wa

shing liquid to the top of N2 washing column. The pressurized N2 gas by the

N2 c

ompressor is sent to the tail gas heat exchanger and also used for

adjusting the

mixing ratio. A part of N2 passing through the first tail gas heat

exchanger is

cooled to saturated gas temperature as low as app. 137C and sent to the air

separ

ation

unit.

The N2 gas is liquefied through N2 liquefier, the tubes mounted in the

main c


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ondenser and N2 super cooler of the air separation unit and returns to N2

washin g unit as a state of super cooled liquid N2 with a temperature of -

190C.

To reactivate the molecular sieves in adsorber the N2 gas is introduced

from air separation unit. Reactivation heater heats up one part of

introduced N2. For adsorber regeneration and other part are cooled by

reactivation cooler for abso rber cooling.The N2 washing unit is based on the following design condition.

1). Raw gas: -

Quantity design

Normal pressure 40.5 +- 2.0 g/cm2 A

Temperature -55C

Composition

H2 93.62 vol.%

N2 0.29 vol.%

CO 5.21 vol.%

Ar 0.38 vol.%

CH4 0.50 vol.%

CO2 10 ppm

CH3OH 100 ppm

NOX 0.02 ppm

2). Product gas: -

Design Quantity

Normal pressure 99186 Nm3/hr

Temperature 33C

Composition

H2 75 vol.%

N2 25 vol.%Ar 50 m


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O2 2 mCO 5 mCH4 1 ppm

Nitric oxide in the raw gas forms gums and deposits at feed gas side

of N2 washing column inlet heat exchanger. The accumulated gums cause heavy

explosi on at the following stage for plant shut down even under N2

atmosphere.

The NOX gum accumulation is limited up to 0.02 ppm of 1 year, and the process

sh all be subject to the acetone cleaning if the counted accumulation

exceeds this limit. The NOX content shall never exceed 0.2 ppm even on pea

and also not exce ed the 0.02-ppm over than total 1 month per year. If the

NOX content exceeded th e above value, the plant shall be shutdown.

Ammonia synthesis process: -

SYNTHESIS CATALYST OPERATION & ECONOMICS

1. Chemistry and Brief description of plant

Le ChateliersPrinciple - The principle states that if any of the RXN

parameter (T, P and Conc.) were changed in RXN equilibrium, then the RXN will

proceed in t hat direction, where the change in the parameter is

counteracted.

This principle can be used to discuss the Amm. Synth.RXN


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N2 (g) + 3 H2 (g) = 2 NH3 (g) H =750 .Cal/ g.

This RXN is exothermic and moles of product are less than the sum of moles of

Re

actants. Then according to the above

principle: -

a) Increase of temp will shift the RXN in the reverse direction which isen dothermic i.e. heat is absorbed.

b) Decrease of temp. will shift the RXN in forward RXN and so that conc.

of ammonia will increase at the cost of decrease of conc. of N2 and H2.

c) Increase of Pr. will shift the RXN in the forward direction when the

No moles in product are less than that of Reactants. Hence this will

increase the conc. of Ammonia. And decrease the conc. of H2 & N2.

d) Increase of conc. of N2 and H2 will ma e the RXN to ta e place in the

fo rward direction where the added material is consumed.

e) Removal of ammonia formed after condensation with water cooler and

ammon ia chiller as early as possible increase the RXN. If products formed

are not re moved, then the RXN will not ta e place.

The syn gas from N2 washing unit is compressed from 37 g/cm2 G to 231

g/cm

2G in the centrifugal type synthesis gas compressor. Before compression the

ma e

up gas is mixed with flash gas from the product let down tan . After

compressio

n to 218 g/cm2 G , the total ma e up gas is mixed with the recirculation gas

th

e NH3 separator and the mixture is finally compressed to 231 g/cm2 in the

last

casing of synthesis gas compressor.


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The gas leaving synthesis gas compressor enters the synthesis hot

exchanger

A-EA602, where it is heated to the converter inlet temperature by heat

exchanger

with the hot effluent gas from the synthesis economizer A-EA601 A, B.

At the outlet of the ammonia converter A-DC601 the gas contains about 16% of

NH3

.

A considerable part of the heat content of the converter effluent gas is

util

ized in the synthesis economizer A-EA601A, B and then cooled down to about 71

oC

in the synthesis hot exchanger A-EA602.

The cooling of the gas continues first in the synthesis water cooler A-

EA603,

in which a substantial part of the ammonia is condensed. At the outlet of

the s

ynthesis water cooler the temperature is about 400C. The gas then passes

the syn

thesis cold exchanger A-EA604, in which it is cooled to about 330C by heat

excha

ngers with the recirculation gas coming from the ammonia separator. Finally,

the

gas is cooled to 100C in the Ammonia cooled condensorA-EB601. The mixture of

sy

nthesis gas and liquid ammonia is passedon to the ammonia seperatorA-FA601,

in

which the liquid ammonia is separated.The gas which separates the ammoniatill

4.92% is heated to about320C in the synthesis of cold exchanger, and enters

the

last casingof the synthesis gas compressor as recycle after mixed with ma e

up

synthesis gas. The liquid ammonia separated in the ammonia separator is

depress


26/52

urized to 45 g/cm2G and ta en to the product let down tan in which

considerabl

e part of the gases dissolved in the

Ammonia is released. This gas is recycled to the synthesis gas compressor

suctio n and reused in the synthesis loop.

The liquid ammonia from product let down tan delivered and led to the

urea pl ant under normal operation. The ammonia converter is the TOPSOE

radial flow type converter. It consists of a pressure shell and a bas et.

The bas et is divided into a lower heat exchanger and a catalyst section

consisting of two beds. A cen tral tube passes through the catalyst section.

The main stream of the synthesis gas is introduced into the converter

through two main inlets at the top and passes downwards through the annular

space betwe en the bas et and the pressure shell, eeping the later

cooled. At the bottom of converter, the gas enters into the shell side of

the lower exchanger, in which

it is heated to the reaction temp. By heat exchanger with gas leaving the

conver


27/52

ter. This reaction temp. can be adjusted by means of a cold bypass

introduced th rough the bottom nozzle of the converter.

The gas leaving the lower exchanger goes to the upper catalyst bed

through a transfer pipe placed inside the central tube in the lower bed.

The gas passes th e upper bed in radial direction and the reaction ta es

place. The distribution i s ensured by means of perforated plate placed in

the catalyst bed wall.The react gas in the upper bed enters the lower bed through the

outer a nnular space surrounding catalyst bed. The temp. Outlet of the upper

bed is abou t 5000C. This temp. is reduced to about 4050C before entering

into lower bed by addition of quench gas. The rxn. Gas passed the lower bed

in the radial directio n enters in to the lower exchanger through the

annular space between the inner b ed wall. The gas flow distribution on lower

bed is also ensured by the perforate d plate.

The outlet temp. of the gas from the lower bed is about5100C. The gas

passe d through the tube side of the lower exchanger and leaves the

converter through the bottom of the pressure shell. The refrigeration

system consist of the ammoni a cooled condenser and the ammonia

refrigerator which consist of the ammonia com pressor, the ammonia

condenser, the ammonia receiver.

The compressed ammonia vapor leaving the ammonia compressor is condensed

in t he ammonia condenser. The liquid ammonia is vaporized in the ammonia-

cooled cond enser at 3.9

g/cm2G, there by providing the cooling capacity necessary for cooling and

conde nsing the product ammonia.

The vaporized ammonia gas enters the suction of the ammonia compressor

for co mpression to about 16 g/cm2 G.


28/52

GAS COMPOSITION

Particulars Inlet Converter Outlet converter

Feed gas 395515 NM3 340377 NM3

Temp. 1200C 3180C

Ammonia 3.12% 17.8%

H2 71.99% 60.05%

N2 24,0% 20.0%

Ar.+CH4+He 0.89 1.03%

CO+2xCO2+H2+2xO2 2ppm max.

CATALYST TEMP.

Particulars Max.design condition Prevailing

Ist bed-Inlet(Centre) 390oC 380 oC

In the bed 495 oC

O/L 522 oC 518 oCIId Bed Inlet 405 oC 390 oC

T.C in bed 450 oC

O/L center tube 505 oC 454 oC

1). H2/N2 ratio in the ma e up gas

H2 / N2 ratio 3:1 is maintained in loop. If H2/N2 ratio is below

2.

5:1 or higher than 3:1 reaction speed in the converter will decrease,

temp.will

tend to decrease and pressure of the loop increases. Some gas must be

purged th


29/52

rough loop vent to maintain ratio in the loop. Preferred ratio is

2.88.because

N2 is a limiting reactant in the reaction.

2). High inerts in the loop:-

Inerts in the loop > 1.26% increases the loop pressure but

the e

ffective pressure of H2 & N2 in the loop decreases and reaction velocitydecreas

es,. Hence inerts level shouldbe controlled to optimum.

3) Ammonia Conc. At Converter

inlet:-

Increase of Ammonia conc. In the converter inlet gas

reduce

d the reaction rate and decrease of Ammonia con. Inlet to converter

increases th

e reaction rate. GC-601 and EB 601 chiller operation should be adjusted to

main

tain Ammonia con. In the inlet to optimum level. GC-601suction pressure

should

be 3.8K

4). Circulatingrate:

Increase of circulating rate of gas reduces the pressure of

the lo

op. Though load on the circulating compressor and refrigeration compressor

incr

eases. However, the loop pressure decreases and consequently load on the

main c

ompressor reduces.

5). Pressure:

According to Le-Chattier principle, High pressure favors the

forwar

d reaction. But pressure increases in the loop due to following factors:

a) Increase of ma e up gas quantity

b) Decrease of circulating rate


30/52

c) Increase of inert level

d) Ammonia content increase in the converter inlet

e) H2/N2 ratio not proper

f) Reduction of catalyst activity due to poisoning or aging of catalyst.

Pressure rise due to point No.a) i.e increase of ma e up gas favors the

forward reaction but other factors b) to f) retard the reaction and steps

should be ta e n to control these parameters.

TYPE OF COMPRESSOR

PLANT COMPRESSOR:

1. OXYGEN COMPRESSOR 4. REFRIGERATION COMP.2. AIR COMPRESSOR 5. SYNTHESIS COMPRESSOR3. NITROGEN COMPRESSOR

Reciprocating compressors

Animation of reciprocating compressor

A motor-driven six-cylinder reciprocating compressor that can

oper

ate with two, four or six cylinders.

Main article: Reciprocating compressor

Reciprocating compressors use pistons driven by a cran shaft. They can be

either


31/52

stationary or portable, can be single or multi-staged, and can be driven by

ele

ctric motors or internal combustion engines.[1][4][5] Small reciprocating

compre

ssors from 5 to 30 horsepower (hp) are commonly seen in automotive

applications

and are typically for intermittent duty. Larger reciprocating compressors

well o

ver 1,000 hp (750 W) are still commonly found in large industrial and

petroleum

applications. Discharge pressures can range from low pressure to very


32/52

High pressure (>6000 psi or 41.4 MPa). In certain applications, such as air

comp ression, multi-stage double-acting compressors are said to be the most

efficient compressors available, and are typically larger, noisier, and more

costly than comparable rotary units.[6]

Rotary screw compressors

rew

compressor

Main article:

Diagram of a rotary sc

Rotary screw compressors use two meshed rotating positive-

disp

lacement helical screws to force the gas into a smaller space.[1][7][8] These

ar

e usually used for continuous operation in commercial and industrial

application

s and may be either stationary or portable. Their application can be from 3

hors

epower (2.2 W) to over 1,200 horsepower (890 W) and from low pressure to very

high pressure (>1200 psi or 8.3 MPa).

Rotary vane compressors

See also:

Rotary vane compressors consist of a rotor with a number of blades

inserted in radial slots in the rotor. The rotor is mounted offset in a

larger h

ousing which can be circular or a more complex shape. As the rotor turns,

blades

slide in and out of the slots eeping contact with the outer wall of the

housin

g.[1] Thus, a series of decreasing volumes is createdby the rotating blades.

Ro


33/52

tary Vane compressors are, with piston compressors one of the oldest of

compress

or technologies.

With suitable port connections, the devices may be either a compressor or avacu

um pump. They can be either stationary or portable, can be single or multi-

stage

d, and can be driven by electric motors or internal combustion engines. Dry

vane

machines are used at relatively low pressures (e.g., 2 bar) for bul

material movement whilst oil-injected machines have the necessary volumetric

efficiency to

achieve pressures up to about 13 bar

Scroll compressors

Main

article:

Mechanism of a scroll pump

A scroll compressor, also nown as scroll pump and scroll vac

uum pump, uses two interleaved spiral-li e vanes to pump or compress fluids

such

as liquids and gases. The vane geometry may be involutes, Archimedean

spiral, o

r hybrid curves.[9][10][11]They operate more smoothly, quietly, and reliably

th

an other types of compressors in the lower volume range

Often, one of the scrolls is fixed, while the other orbits eccentrically

without

rotating, thereby trapping and pumping or compressing poc ets of fluid or

gas b

etween the scrolls.


34/52

(NITROGEN COMPRESSOR)

GENERAL DESCRIPITION

NITROGEN GAS COMPRESSOR IS OF TYPE driven by steam turbine, both of m/s mitsui s

hip building & engineering co. ltd. This compressor has he under mentioned

constr


35/52

uction features:

1. Casing can be horizontally split for easy maintenance. The lower half

is provided with the gas inlet and outlet connection.

2. it consists of two casing with different rotational speed (LPC&HPC)

and four stages .

3. Diaphragm coupling is used to minimize thrust force caused by thermalex pansion of the rotor.

4. Labyrinth type gas seal is used.

TECHNICAL DATA:

Specification of the compressor at normal condition (100% flow)

1. capacity ( g/hr)day 34,082

2. relative humidity(%) 0

3. molecular weight 28.01

4. cp/cv( 1) 1.4

5. compressibility 1.0

6. speed(rpm) 8000/11435(LPC/HPC)

7. Max. continuous r m 86508. t e of driver extraction steam9. DRIVE RATED (HP)

OXYGEN COMPRESSOR DESCRIPSTION

OF THE SYSTEM

THE oxygen compressor is suppliedby DEMG COMPRESSOR WEST GERMANY. It is

a two casting multistage turbo-compressor of single shaft construction. The

c ompressor is driven directly by a steam turbine supplied by compressor. A

reduct ion gear is provided b/w LP and HP compressor. Each casing has 6

impeller.


36/52

The compressor is designed to supply 24970 NM3/hr of minimum 98%

oxygen gas at 63.03 g/cm2 G and final disch. Temperature of 450c to the

gasifiers.

The casing of the compressor is a pressure tight and dimensionally stable

horiz ontally split. The impellers are shrun on the shaft. These impellers

are so arr anged on the shaft that the longitudinal thrust is partially

cancelled out and i nternal lea age is minimized.

A dummy piston has provided to reduce the longitudinal thrust causing by

the impeller arrangement down to a value permissible for thrust

bearing.

Drain holes for lea age oil and condensate have been provided in the spares

betw een casing and bearing trestles to prevent liquid from entering the

machine.

A fire wallhas been provided around the oxygen compressor to confine the

danger to this area in case any explosion occurs in the oxygen compressor.

No operating personnel should be allowed to enter this area while the

compressor is running .s

Specification

COMPRESSOR DETAILS


37/52

1. type 10MH 6C 6MH 6C2. no. of impeller 6 63. no. ofprocess stage 1 1

Casing stage LPC HPC

4. Gas handled 98.00%o2. 0.70% 1.5% argon

5. s eed normal 9500 13598Maximum 19975 14278Tri 10973 157071st critical 3950 59002nd critical 14100 25300Prohibited range 3550 to 5140 (turbine

speed)

Description :-It is a centrifugal compressor having 3 casing driven by steam turbine with a

speed a 11100 rpm at 100% capable of compressing 99,960 NM3/ hr of systhesis ga

s and t builtup pressure from 37.5 g /cm2 to 221 g/cm2 G . in the ma e up s

tage and then finally upto 235ata in last stage which act as recirculator .

GAS FLOW:-

The purified gas available from nitrogen wash unit after removal of

carbonmonoxide and other impurities and after the addition of ma e up nitrogen ,

enter

the suction of first casing of sys . gas compressor at 37.5 ata pressure

. i

t is compressed to 81.6 ata in the first stage then passes to second stage

an

d is compressed to 148.5 ata pressure . the gas then enter the suction of the

r

ecycle stage casing and gets mixed with the recycle gas is compressed to 235 ata

pressure . it then goes to the synthesis section .

Inter cooler for cooling the gas to nearly 410c have been provided between the f

irst and second casing and second and third casing and after cooler has been p

rovided for cooling the ma e up gas 450c before it enter the suction of the re

cycle stage.


38/52

The released separated from ammonia flash drum of systhesis section also

enter the suction of 5he compressor after the main isolation value for

utilization i n this section . there is a provision for controlling the

capacity of the recyc le stage by adjustable guide vanes provided on the

casing .

Nitrogen connections have been provided in the suction line after the main

iso lation valve for supply of nitrogen for purging the loope during shut

down.

Ammonia refrigeration compressor :-

Ammonia refrigeration compressor is a centrifugal machine catering to refrigera

tion requirement , of ammonia synthesis loop. Also this can handle the air sepa

ration units refrigeration load in case of emergencies . the compressor is

design

ed to compress 31.4Te/m of ammonia to 17.0 ata a from 4.7 ata . The compressor

is drivenby a steam turbine , the turbine is an extraction cumcondensing

type, t

he inlet pressure being 40ata and extraction pressure being 9ata .The unit is s

upplied by M/S BHEL HYDERABAD.


39/52

AIR COMPREESOR

Axial compressors are rotating, aerofoil based compressors in which the wor

ing fluid principally flows parallel to the axis of rotation. This is in

contrast wi th other rotating compressors such as centrifugal, axe-

centrifugal and mixed-flo w where the air may enter axially but will have a

significant radial component o n exit. compressors

Axial flow compressors produce a continuous flow of compressed gas, and have

the benefits of high efficiencies and large mass flow capacity, particularly in

rel ation to their cross-section. They do, however, require several rows of

aerofoils to achieve large pressure rises ma ing them complex and expensive

relative to o ther designs (e.g. centrifugal compressor).

Axial compressors are widely used in gas turbines, such as jet engines, high

spe ed ship engines, and small scale power stations. They are also used in

industria l applications such as large volume air separation plants, blast

furnace air, fl uid catalytic crac ing air, and propane dehydrogenation.


40/52

Axial compressors, now n as superchargers, have also been used to boost the

power of automotive recipro cating engines by compressing the inta e air,

though these are very rare. A good example of an axial supercharger is the

aftermar et Latham type built between 1955-65 which were used on hot rods

and ai r-cooled Vol swagens at that time, but these didn t catch on

Description

Axial compressors consist of rotating and stationary components. A shaft drives

a central drum, retained by bearings, which has a number of annular aerofoil row

s attached. These rotate between a similar number of stationary aerofoil rows

at

tached to a stationary tubular casing. The rows alternate between the rotating

a

erofoils (rotors) and stationaryaerofoils(stators), with the rotors

imparting en

ergy into the fluid, and the stators converting the increased rotational inetic

energy into static pressure through diffusion. A pair of rotating and

stationar

y aerofoilsis called a stage. The cross-sectional area between rotor drum and

ca

sing is reduced in the flow direction to maintain axial velocity as the fluid is

compressed.

Diagram of an axial flow compressor

Design

The increase in pressure produced by a single stage is limited by the relative v

elocity between the rotor and the fluid, and the turning and diffusion capabilit

ies of the aerofoil. A typical stage in a commercial compressor will produce a p


41/52

ressure increase of between 15% and 60% (pressure ratios of 1.15-1.6) at

design conditions with a polytrophic efficiency in the region of 90 -95%. To

achieve di fferent pressure ratios, axial compressors are designed with

different numbers o f stages and rotational speeds.

Higher stage pressure ratios are also possible if the relative velocity

between fluid and rotors is supersonic,however this is achieved at the

expense of effic iency and operability. Such compressors, with stage

pressure ratios of over 2, a re only used where minimizing the compressor

size, weight or complexity is criti cal, such as in militaryjets.

The aerofoil profiles are optimized and matched for specific velocities and

turn ing. Although compressors can be run at other conditions with different

flows, s peeds, or pressure ratios, this can result in an efficiency penalty

or even a pa rtial or complete brea down in flow ( nown as compressor stall

and pressure surg e respectively). Thus, a practical limit on the number of

stages, and the overal l pressure ratio, comes from the interaction of the

different stages when requir

ed to wor away from the design conditions. These off-design conditions can be

mit igated to a certain extent by providing some flexibility in the compressor.

This

is achieved normally through the use of adjustable stators or with valves

that can bleed fluid from the main flow between stages (inter-stage bleed).

Modernjet enginesuse a series of compressors, running at different

speeds; to supply air at around40:1 pressure ratio for combustion with

sufficient flexibil ity for all flight conditions.

Development

Early axial compressors offered poor efficiency, so poor that in the early 1920s

a number of papers claimed that a practical jet enginewould be impossible

to c

onstruct. Things changed dramatically after A. A. Griffith published a seminal p

aper in 1926, noting that the reason for the poor performance was that existing

compressors used flat bladesand were essentially "flying stalled". He showed th

at the use of airfoils instead of the flat blades would dramatically increase ef

ficiency, to the point where a practical jet enginewas a real possibility. He c

oncluded the paper with a basic diagram of such an engine, which included a seco

nd turbine that was used to power a propeller.


42/52

Real wor on axial-flow engines started in the late 1930s, in several efforts th

at all started at about the same time. In England, Haine Constant reached an agr

eement with the steam turbine company Metropolitan Vic ers (Metrovic ) in 1937,

starting their turboprop effort based on the Griffith design in 1938. In 1940, a

fter the successful run of Whittle s centrifugal-flow design, their effort was r

e-designed as a pure jet, the Metrovic F.2. In Germany, von Ohain had produced

several wor ing centrifugal engines, some of which had flown including the world

s first jet aircraft (He 178), but development efforts had moved on to Jun

ers

(Jumo 004) and BMW (BMW 003), which used axial-flow designs in the world s first

jet fighter (Messerschmitt Me 262) and jet bomber (Arado Ar 234). In the

United

States, both Loc heed and General Electric were awarded contracts in 1941 to

de

velop axial-flow engines, the former a pure jet, the latter a turboprop.

Northro

p also started their own project to developa turboprop, which the US Navy event

ually contracted in 1943. Westinghouse also entered the race in 1942, their proj

ect proving to be the only successful one of the US efforts, later becoming the

J30.

By the 1950s every major engine development had moved on to the axial-flow type.

As Griffith had originally noted in 1929, the large frontal size of the

centrif

ugal compressor

caused it to have higher drag than the narrower axial-flow type.

Additionally th e axial-flow design could improve its compression ratio

simply by adding additio nal stages and ma ing the engine slightly longer. Inthe centrifugal-flow design the compressor itself had to be larger in

diameter, which was much more difficu lt to "fit" properly on the aircraft.

On the other hand, centrifugal-flow design s remained much less complex (the

major reason they "won" in the race to flying examples) and therefore have a

role in places where size and streamlining are no t so important.


43/52

AIR COMPRESSOR

INTRODUCTION:-

The air compressor supplied by MITSUI SHIPBUILDING and ENGG.CO. Of Japan is of a

mult8i stage axial flow type consisting of low &high pressure casing with an

ex

ternal intercooler. The drive a steam turbine connected directly with a gear

cou

pling is MITSUI BROWN BOXER single cylinder impulse type condensing turbine.

Adjustable stator blades are

provided f

or all stage of both the LPC and HPC of comp. to control its capacity. This

comp

. has a pressure ratio control device which server to eep the proper

pressure r

atio of the LPC and HPC.

The design condition of feed air at the battery limit of ASU is:-

Quantity : 140000NM3/hr.

Pressure : 7.0 g/CM2

Temp. : 450c

Relative humidity : 100%

Composition

CO2 : 500PPM(MAX.)

C2H2 : 0.45 mg/M3

CmHn : 0.7 mg/NM3

NH3 : 10mg/NM3

No+NO2 : 1.27mg/NM2

Dust : 1mg/NM3

47


44/52

Spools

All compressors have a sweet spot relating rotational speed and pressure,

with h

igher compressions requiring higher speeds. Early engines were designed for

simp

licity, and used a single large compressor spinning at a single speed. Later

des

igns added a second turbine and divided the compressor into "low pressure"

and "

high pressure" sections, the latter spinning faster. This two-spool design

resul

ted in increased efficiency. Even more can be squeezed out by adding a third

spo

ol, but in practice this has proven to be too complex to ma e it generally

worth

while as there is a trade off between higher fuel efficiency and the higher

main

tenance involved pushing up total cost of ownership compared to a two spool

desi

gn. That said, there are several three-spool engines in use, perhaps the

most fa

mous being the Rolls-Royce RB.211, used on a wide variety of commercial

aircraft

.

Bleed air, variable stators

As an aircraft changes speed or altitude, the pressure of the air at the

inlet t

o the compressor will vary. In order to "tune" the compressor for these

changing

conditions, designs starting in the 1950s would "bleed" air out of the

middle o

f the compressor in order to avoid trying to compress too much air in the

final


45/52

stages. This was also used to help start the engine, allowing it to be spun

up w

ithout compressing much air by bleeding off as much as possible. Bleed

systems w

ere already commonly used anyway, to provide airflow into the turbine stage

wher

e it was used to cool the turbine blades, as well as provide pressurized air

for

the air conditioning systems inside the aircraft.

A more advanced design, the variable stator, used blades that can be

individuall

y rotated around their axis, as opposed to the power axis of the engine. For

sta

rtup they are rotated to "open", reducing compression, and then are rotated

bac

into the airflow as the external conditions require. The General Electric

J79 w

as the first major example of a variable stator design, and today it is a

common

feature of most military engines.


46/52

Closing the variable stators progressively, as compressor speed falls,

reduces t he slope of the surge (or stall) line on the operating

characteristic (or map), improving the surge margin of the installed unit.

By incorporating variable stat ors in the first five stages, General Electric

Aircraft Engines has developed a ten-stage axial compressor capable of

operating at a 23:1 design pressure ratio. Bypass

For jet engine applications, the "whole idea" of the engine is to move air

to pr ovide thrust. In most cases, the engine produces more power to move

air than its mechanical design actually allows. Namely, the inlet into the

compressor is sim ply too small to move the amount of air that the engine

could, in theory, heat a nd use. A number of engine designs had experimented

with using some of the turbi ne power to drive a secondary "fan" for added

air flow, starting with the Mestro vic F.3, which placed a fan at the rear of

a late-model F.2 engine. A much more practical solution was created by Rolls-

Royce in their early 1950s Conway engine

, which enlarged the first compressor stage to be larger than the engine

itself. This allowed the compressor to blow cold air past the interior of

the engine, s omewhat similar to a propeller. This technique allows the

engine to be designed to produce the amount of energy needed, and any air

that cannotbe blown through the engine due to its size is simply blown

around it. Since that air is not com pressed to any large degree, it is

being moved without using up much energy from the turbine, allowing a

smaller core to provide the same mass flow, and thrust, as a much larger

"pure jet" engine. This engine is called a "turbofan."

This technique also has the added benefit of mixing the cold bypass air with

the hot engine exhaust, greatly lowering the exhaust temperature. Since the

sound o

f a jet engine is strongly related to the exhaust temperature, bypass also

drama tically reduces the sound of the engine. Early jetliners from the 1960s

were fam ous for their "screaming" sound, whereas modern engines of greatly

higher power generally give off a much less annoying "whoosh" or even

buzzing.

Mitigating this savings is the fact that drag increases exponentially at high

sp eeds, so while the engine is able to operate far more efficiently, this


47/52

typicall y translates into a smaller real-world effect. For instance, the

latest Boeing 7

37 s with high-bypass CFM56 engines operates at an overall efficiency about

30% better than the earlier models. Military turbofans, on the other hand,

especiall y those used on combat aircraft, tend to have so low a bypass-

ratio that they ar e sometimes referred to as "lea y turbojets."

Energy exchange between rotor and fluid

The relative motion of the blades relative to the fluid adds velocity or

pressur

e or both to the fluid as it passes through the rotor. The fluid velocity is

inc

reased through the rotor, and the stator converts inetic energy to pressure

ene

rgy. Some diffusion also occurs in the rotor in most practical designs.

The increase in velocity of the fluid is primarily in the tangential direction (

swirl) and the stator removes this angular momentum.

The pressure rise results in a stagnation temperature rise. For a given

geometry

the temperature rise depends on the square of the tangential Mach number

of the

rotor row. Current turbofan engines have fans that operate at Mach 1.7 or

more,

and require significant containment and noise suppression structures to

reduce

blade loss damage and noise.

Velocity diagrams

The blade rows are designed at the first level using velocity diagrams. A veloci

ty diagram shows the relative velocities of the blade rows and the fluid.The axial flow through the compressor is ept as close as possible to Mach 1 to

maximize the thrust for a given compressor size. The tangential Mach number

dete

rmines the attainable pressure rise.

The blade rows turn the flow through an angle ; larger turning allows a higher

te

mperature ratio, but requires higher solidity.


48/52

Modern blades rows have low aspect ratios and high solidity.

Compressor maps

A map shows the performanceof a compressor and allows determination of

optimal

operating conditions. It shows the mass flow along the horizontal axis,

typicall

y as a percentage of the design mass flow rate, or in actual units. The

pressure


49/52

rise is indicatedon the vertical axis as a ratio between inlet and exit

stagna tion pressures.

A surge or stall line identifies the boundary to the left of which the

compresso r performance rapidly degrades and identifies the maximum

pressure ratio that ca n be achieved for a given mass flow. Contours of

efficiency are drawn as well as performance lines for operation at

particular rotational speeds.

Compression

stability

Operating efficiency is highest close to the stall line. If the downstream

press

ure is increased beyond the maximum possible the compressor will stall and

becom

e

unstable.

Typically the instability will be at the Helmholtz frequency of the system,

ta i

ng the downstream plenum into

account.

Benefit

s

The benefits of this technology included reducing power cost, reducing power

sur

ges (from starting AC motors), and delivering a more constant pressure. The

down

side of this technology is the heavy expense associated with the drive, and

the

sensitivity of these drives - specifically to heat and moisture.

Compressed

air

Compressed air is air which is ept under a certain pressure, usually

greater th

an that of the atmosphere. In Europe 10 % of all electricity used by

industry is


50/52

used to produce compressed air. This amounts to 80 terawatt hours per

year.[1]

Dangers

A blast of air under 40 psi (pounds per square inch) from 4 inches away ca

rupt

ure an eardrum or cause brain damage.[citation

needed]

Directed at the mouth, compressed air can rupture the lungs.[citation

needed]

Uses:-

Compressed air can be used in or

for:

Pneumatics, the use of pressurized gases to do wor . See compressed a

energy s

torage

.

vehicular transportation using a compressed air

vehicle

Scubadiving, to inflate

buoyancy devices. Seealso: Breathing

gas

Cooling using a vortex

tube.

Gas dusters for cleaning electronic components that cannot be cleaned wi

water

. These are also called "canned air", however this is a misnomer because thepro

pellant is not air, but rather a hydro fluorocarbon which poses a health

ris if

inhaled.

air bra e (rail)

systems


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air bra e (road vehicle)

systems

air bra e (air vehicle)

systems

compressed air breathers (such as Suisse Air)[citation

needed]

paintball ammunition

propulsion

airsoft ammunition

propulsion

ECONOMICS

1. High pressure favors the reaction but operation at less pressure for

the same production rate lowers load on the syn.gas compressor and thus

saving of s team, which cost at Rs. 600/Te.

2. Temp. Poisoning and permanent poisoning of the catalyst reduces the

life

of catalyst and catalyst fresh is forced to be changed earlier- Loosing Companys

money and production loss occurs.To avoid temp.poisoning - The ma e up gas should be pure, oxygen compound

such a

s CO, H2), CO2 in the gas should be limited. N2 purity should be


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und abnormal.

4. On changing of the bas et S-1to S-200, 5-6 Te./hr steam is saved which

in

turn reduces the energy consumption of 0.12 mmKcal/Te. of ammonia produced.

5. Optimum temp.operation in the catalyst increases the life

PRODUCTION PERFORMANCE

RECORDS : Pea s in Production Scale

Highest Production of

Ammonia on single Day : 1041 MT (on 02.01.1998)

(against 900 MT/Day rated Capacity)

Highest Production of

Urea on single day : 1918 MT (on 17.12.2000)

a ainst 1550 MT/Da rated Ca acit Hi hest Annual Productionof Ammonia : 316619 MT 97-98 a ainst 297000 MT rated Ca acit

Hi hest Annual roduction ofUrea : 562250 MT (97-98)

Documents

(142276387) 102336953 Training Report at Nfl Panipat