urea plant india
TRANSCRIPT
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R-1 LP R-2 1
NFL NANGAL & BATHINDAUrea Plant
Presented ByPrem Baboo
Sr. Manager(Prod)
National Fertilizers Ltd, India
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R-1 LP R-2 2
Urea Processes used in NFL units
NANGAL: Technimont Total Recycle
Process. BATHINDA & PANIPAT: Mitsu toatsu C
Improved Process.
VIJAIPUR: Snamprogetti ammonia stripping process.
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R-1 LP R-2 3
NANGAL UREA PROCESS
BRIEF DESCRIPTION :It is a Montedison total recycle process.
Plant is installed in April,1978.
Plant capacity is 1450 Te/day.
Commercial production after revamping started on
Feb 1st,2001.
Before revamping its capacity was 1000 Te/day.
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R-1 LP R-2 4
Plant Description
CO2 Compressor & H.P.Pumps
Urea synthesis.
Urea separation.
Recovery section.
Vacuum section.
Prilling section.
Waste water section.
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R-1 LP R-2 5
Specification Sheet
Ammonia at B/L
NH3 99.5% by weight
Water 0.5% by weight
Carbon Dioxide at B/L
CO2 98.99% (Vol.)
H2 0.6 to 1.5% (Vol.)
CH4 0.1 to 0.15% (Vol.) H2S 0.65 ppm (Vol.)
CH3OH 6.00 ppm (Vol.) for old compressor
CH3OH 1000 ppm (Vol.) for new compressor
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R-1 LP R-2 6
Specific Consumption
Ammonia 0.574Te/Te of urea
Carbon dioxide 0.745 Te/Te of urea
Steam 30ata 1.23 Te/Te of urea
Power 135 kwh
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CO2 Compressor
There are two motor driven reciprocating compressors
Old Compressor
No. of Stages 3 Capacity 17510 Nm3/hr.
Suction/Discharge press. 11/220 Kg
RPM 300
Motor Power 2250KW Oxygen content maintained 2200ppm
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NEW COMPRESSOR:
No. of Stages 4
Capacity 9500 Nm3/hr.Suction/Discharge press. 1.5/220 Kg
RPM 350
Motor Power 2400KWOxygen content 3500ppm
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Ammonia feed pumps
There are three reciprocating plunger pumps
Make Peroni
No. of plungers 5
Pulsation dampener nil
Capacity 53NM3/hr. each
Suction pressure. 30Kg/cm2
Discharge pressure 220 Kg/cm2
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Ammonia feed pump
One no. ammonia pump (New) having less
capacity 25NM3/hr.
Two ammonia pumps run at 100% load.
Ammonia is directly taken from ammonia
plant at 30 kg & fed to reactors at
220kg.Before feeding to reactors it is preheated up to 80°C.
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Carbamate feed pumps
There are four reciprocating plunger pumps
Make Peroni
No. of plungers 5 in old & 3 in new
Pulsation dampener only in new pump
Capacity 53M3/hr. each
Suction pressure. 70Kg/cm2 Discharge pressure 220 Kg/cm2
Three pump run at 100% load.
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Urea Synthesis
Urea reactor {Old}
Volume 50M3
No. of trays 14
Type of trays High eff. Casale trays.
Temp. Bott./Top 184/196OC
Pressure 220Kg/cm2
Liner SS 316 L
Thickness 12mm
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Urea Synthesis
Urea reactor {New}
Volume 33M3
No. of trays 9
Type of trays High eff. Casale trays.
Temp. Bott./Top 184/198OC
Pressure 220Kg/cm2
Liner 2RE69
Thickness 6mm
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New Reactor
Fresh ammonia & carbon dioxide are fed tomixer, then to carbamate condenser, where
ammonium carbamate is formed. Heat ofreaction is taken out in the form of 6 .0 atasteam generation. The hot carbamate flows to
reactor R-2 where residence time is enoughto get 69% conversion.It is once throughreactor, no carbamate solution is fed to it.
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Old Reactor
The rest of CO2 & NH3 are fed to old
reactor. All the carbamate sol. of the plant
fed to old reactor.
Both reactor outlet joins & pr. Is controlled
by PRC-1 at 220kg.
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Reactor feeds
The expected best operating condition are:
New sec. Old sec.
Capacity (TPD) 600 1050
Pr. (ata) 220 220
Temp. (ºc) 196 196
N/C 2.9 2.75H/C 0 0.7
Conversion (%) 69 55
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Conventional Process
Decomposition:
NH4COONH2 +Heat = 2NH3 + CO2
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Urea Separation.
1st stage Pressure 70 Kg/cm2
Temperature 185OC
Urea conc. 54.5%
2nd stage Pressure 12 Kg/cm2
Temperature 150OC
Urea conc. 65%
3rd stage Pressure 3 Kg/cm2
Temperature 130OC
Urea conc. 72%
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Recovery Section
Pressure 1.5 Kg/cm2
Temperature 125
O
C Outlet conditions
NH3 0.04%
Urea 1.0%
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Vacuum Section
1st stage vacuum system Pressure 0.35 ata
Temperature 128OC
Urea conc. 95%
2nd stage vacuum system Pressure 0.04 ata
Temperature 138OC
Urea conc. 99.6%
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Prilling Section
Tower
Height 104.5mtr
Free fall ht. 80mtr Diameter 22mtr
Air flow 8,00,000 nm3/hr
Urea in emission 40mg/nm3.
Scrapper type conical
Bucket
Make Tuttle/Simco
Number TX-267, 268 & 130
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Product Quality
Total Nitrogen 46.5%
Moisture 0.35%
Biuret 0.8-0.9%
Mean prill dia 1.75mm
Sieve analysis
Over size nil Proper size 98.5%
Under size 1.5%
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R-1 LP R-2 23
Waste Water Section
Feed at 100% load 35m3/hr
Feed water analysis NH3 3.00%
UREA 1.2%
Hydrolyser pr. 20Kg/cm
2
Hydrolyser temp. 1980C
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R-1 LP R-2 24
Waste Water Section
Distillation tower
Pressure top 4.5Kg/cm2
Pressure bottom 5.5 Kg/cm2
No. of trays 33+12
Outlet water analysis NH3 40 ppm
Urea 35 ppm
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Plant Start up
Reactor is filled with dilute solution.
In case of empty reactor, it is to be filled withstart up solution.
In case of cold start up, reactor solution is
first heated up to 125
O
C . First stage{70ata} remain by passed.
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R-1 LP R-2 28
Plant is started in once through operation.
Once through operation means the solution issend to urea solution tank and Carbamate is
send to start up solution tank from 2nd stage.
Ammonia feed to reactor and pressure ismaintained at 150ata for 5 minutes and then
CO2 is send to reactor.
Plant Start up
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Reactor pressure will increase according to the
temperature and feed ratio.
As the temperature and pressure reaches to the
desired condition then the Carbamate from 2nd stage
is diverted to the 1st stage.
As the level of 1st
stage condenser increases, startthe Carbamate pump and feed Carbamate to the
reactor.{known as total recycle}.
Plant Start up
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After total recycle, temperature and pressure
of each stage are maintained.
The urea solution is sent to vacuum section.
After normalizing vacuum section, melt urea
diverted towards bucket.
Plant Start up
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R-1 LP R-2 31
Objective of revamping
Optimum utilization of ammonia plant capacity.
Increase in urea plant capacity by 450 MTPD.
Improvement in urea prills quality.
Reduction in specific energy consumption for urea
from 10.26 G cal. To 9.4G cal. Per MT of urea.
Reduction in dust emission.
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R-1 LP R-2 32
Revamping
Project Cost; Rs.161Crores
Project executed by; M/s. Urea CasaleSwitzerland.
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R-1 LP R-2 33
Major equipment added:
CO2 compressor.
NH3 pump.
Carbamate pump.
Urea reactor.
Methanol scrubber.
Urea melt pump
New vacuum distiller {HE9}
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Additional vacuum condenser.
New circular Prilling tower. High efficiency trays in old urea reactor.
Major equipment added:
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Urea Quality After Revamping
Over size reduced to nil.
Temperature in summer reduced from 90
O
Cto 55OC.
Crushing strength increases from 350
gm/prill to 650 gm/ prill. Urea dust emission reduced . Now it is
< 50mg/nm³.
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R-1 LP R-2
Urea casale’s high efficiency tray
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