Urea Process description of Nangal Plant

1. R-1 LP R-2 1
NFL NANGAL & BATHINDA
Urea Plant
Presented By
Prem Baboo
Sr. Manager(Prod)
National Fertilizers Ltd, India

2. 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.

3. 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.

4. 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.

5. 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

6. 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

7. R-1 LP R-2 7
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

8. R-1 LP R-2 8
 NEW COMPRESSOR:
No. of Stages 4
Capacity 9500 Nm3/hr.
Suction/Discharge press. 1.5/220 Kg
RPM 350
Motor Power 2400KW
Oxygen content 3500ppm

9. R-1 LP R-2 9
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

10. R-1 LP R-2 10
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 pre
heated up to 80°C.

11. R-1 LP R-2 11
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.

12. R-1 LP R-2 12
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

13. R-1 LP R-2 13
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

14. R-1 LP R-2 14
New Reactor
 Fresh ammonia & carbon dioxide are fed to
mixer, then to carbamate condenser, where
ammonium carbamate is formed. Heat of
reaction is taken out in the form of 6 .0 ata
steam generation. The hot carbamate flows to
reactor R-2 where residence time is enough
to get 69% conversion.It is once through
reactor, no carbamate solution is fed to it.

15. R-1 LP R-2 15
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.

16. R-1 LP R-2 16
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 2.75
H/C 0 0.7
Conversion (%) 69 55

17. R-1 LP R-2 17
Conventional Process
 Decomposition:
NH4COONH2 +Heat = 2NH3 + CO2

18. R-1 LP R-2 18
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%

19. R-1 LP R-2 19
Recovery Section
 Pressure 1.5 Kg/cm2
 Temperature 125OC
 Outlet conditions
 NH3 0.04%
 Urea 1.0%

20. R-1 LP R-2 20
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%

21. R-1 LP R-2 21
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

22. R-1 LP R-2 22
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%

23. 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/cm2
 Hydrolyser temp. 1980C

24. 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

25. R-1 LP R-2 27
Plant Start up
 Reactor is filled with dilute solution.
 In case of empty reactor, it is to be filled with
start up solution.
 In case of cold start up, reactor solution is
first heated up to 125 OC .
 First stage{70ata} remain by passed.

26. R-1 LP R-2 28
 Plant is started in once through operation.
 Once through operation means the solution is
send to urea solution tank and Carbamate is
send to start up solution tank from 2nd stage.
 Ammonia feed to reactor and pressure is
maintained at 150ata for 5 minutes and then
CO2 is send to reactor.
Plant Start up

27. R-1 LP R-2 29
 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, start
the Carbamate pump and feed Carbamate to the
reactor.{known as total recycle}.
Plant Start up

28. R-1 LP R-2 30
 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

29. 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.

30. R-1 LP R-2 32
Revamping
 Project Cost; Rs.161Crores
 Project executed by; M/s. Urea Casale
Switzerland.

31. 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}

32. R-1 LP R-2 34
 Additional vacuum condenser.
 New circular Prilling tower.
 High efficiency trays in old urea reactor.
Major equipment added:

33. R-1 LP R-2 36
Urea Quality After Revamping
 Over size reduced to nil.
 Temperature in summer reduced from 90OC
to 55OC.
 Crushing strength increases from 350
gm/prill to 650 gm/ prill.
 Urea dust emission reduced . Now it is
< 50mg/nm³.

34. R-1 LP R-2
Urea casale’s high efficiency tray

35. R-1 LP R-2