The document provides instructions for starting up a urea synthesis plant from an empty reactor. It describes purging lines with nitrogen, heating sections to avoid thermal stresses, charging ammonia to pressurize sections, and preparing solutions. The initial startup involves ammoniating the high pressure loop for 3 hours. Next, condensate is sent to the reactor for 10 minutes before feeding ammonia for 15 minutes and then carbon dioxide. Parameters like temperature and pressure are stabilized over several hours as carbonate solution and passivation air are also fed in. Flow rates are adjusted to control the reactor bottom temperature and pressure.

1. OPERATION OF SYNTHESIS
SECTION W.R.T TROUBLE
SHOOTING
PRESENTED BY
H G MEENA

2. 2
POINTS TO DISCUSS
• START UP
• SHUT DOWN
• TROUBLE SHOOTING

3. TYPE ITEM SERVICE
HEAT
EXCHANGER
E-52 PRECONCENTRATOR
E- 53 PREDECOMPOSER
EJECTOR EJ-1 CARBAMATE RECYCLE EJECTOR
EJ-53 STEAM BOOSTER EJECTOR FOR PRE-DECOMP
SPECIAL EQUIPMENT ME-51 PRECONC VACUUM SYSTEM
ME-52 PRECONCENTRATOR HOLDER
VESSEL MV-52 PRECONC SEPARATOR
MV-53 PREDECOMPOSER STEAM COND
SEP.
PUMP
P-1C HIGH PRESSURE AMM. FEED PUMP
P-50 A/B VAC CONC. UREA SOL PUMPS
P-52 A/B NEW V-6 FEED PUMPS
TANK V-10 BUFFER WASTE WATER TANK
FROM 31/41 ME-51

5. 5
• Initial start up
• Cold start up
• Hot start up
Start Up

6. STARTUP
• Initial start up means:
–All the sections are depressurized and /or
without process fluids.
• Cold start up means:
–All the sections are pressurized with process
fluids but HP Reactor is empty and HP loop
depressurized.
• Hot start up means:
–All the sections are pressurized with process
fluids and HP Reactor is full and HP loop
pressurized

7. 7
START UP
• CLEARANCE TO BE TAKEN FROM
1. MECHANICAL
2. ELECTRICAL
3. INSTRUMENT
• CLEARANCE TO BE TAKEN FROM
1. AMMONIA-II
2. UREA-I

8. 8
Start Up With Empty Reactor
General
During this phase it has been assumed that all
pre-start operations have been completed
together with Mechanical check of the unit.

9. 9
Sealing Tests Of All Sections
• Purpose
– To eliminate leaks, if any, before charging process
fluids.

10. 10
Purging By N2 Of M.P & L.P
Sections
• Purpose
This operation must be carried out before
plant start-up in order to remove all the O2
present, avoiding any risk of explosive mixture
formation during ammonia charging.

11. 11
Purging By N2 Of M.P & L.P
Sections
• Purpose
This operation must be carried out before
plant start-up in order to remove all the O2
present, avoiding any risk of explosive mixture
formation during ammonia charging.

12. 12
Charging of Ammonia in MP
Section
• Purpose
To have a make-up of NH3 (Raw material)
Pressurize the M.P section
Test H.P NH3 pump
Ammoniation

13. 13
Ammonia Solution Preparation in
V-3
• Purpose
Preparation of L.P section to receive process
fluid
The concentration of NH3 in V-3 solution is
about 30%

14. 14
Plant Heating Before Start Up
• Purpose
Whenever start-up is to be performed with the unit
empty and at ambient temperature the equipment
shall be previously heated in order to bring them to
the best conditions to feed the process fluids to the
above equipment.
This is to avoid:
 Thermal stresses on the material
 Possibility of crystallization of products in cold
piping and walls

15. 15
Plant Heating Before Start Up
• The section of High pressure synthesis shall be
heated up to the temperature of 150 ~ 160°C
before introducing the process fluids.
• Important
The heating rate shall never exceed the values
recommended by the equipment manufacturers
(~ 30°C/hr)

16. 16
Conditions Before Ammoniation
• CO2 compressor ready to be started with high
pressure line heated up.
• Compressor will be put in running before
Ammoniation period.
• High pressure pumps ready to be started.
• High pressure section heated up and ready for
Ammoniation

17. 17
Conditions Before Ammoniation
• M.P section charged and pressurized by ammonia with
NH3 booster pump running in closed recycle to
Ammonia receiver.
• L.P section charged with NH3 solution and M.P
carbonate solution pump(P-3) running in circulation to
Carbonate receiver(V-3) through M.P Absorber.
• Vacuum section ready to be taken in line.
• Prilling system ready to be started
• Waste water section in running condition.

18. 18
Ammoniation
Purpose
 To reach the best conditions to start the reactions inside the
reactor.
Conceptual procedure
 It consists in the pressurization of H.P loop with ammonia vapors up
to 90 kg/cm2
 The “Ammoniation” operation requires about 3 hours and then the
unit can be fed by NH3 and CO2 to Urea Reactor.

19. 19
Ammoniation
• The main steps are:
1. Start the pressurization of the Synthesis system
by sending NH3 via Ammonia booster (P-5) to
Start-up line, leaving opened the suction and
delivery valves of H.P Ammonia pump (P-1).the
NH3 is vaporized in the jacket line.
2. Control that the NH3 vapor temp is over 140°C.

20. 20
Ammoniation
3. When the H.P system reaches the value of
Booster pump delivery pressure, start the
H.P Ammonia pump(P-1) in recycle to
Ammonia Receiver (By opening the relevant
valves) and adjust the ammonia rate by
feeding a small flow to start-up line, so to
gradually increase the pressure of the system
up to about 90 kg/cm2g.

21. 21
Ammoniation
4. When the set value of pressure is reached
(90kg/cm2),stop NH3 feeding to Start-up line
by closing the inlet valves and simultaneously
stop P1 pump then proceed to close steam to
jacket of start-up line and wash this line by
KW for a few minutes.
5. The speed of pressure increasing on H.P
section (PIC-7) has to be maintained at 30
kg/cm2 / hour to arrive at the set of 90
kg/cm2g.

22. 22
Plant Preparation for Start Up
(section by section)
• M.P. & L.P. section preparation
Ammonia has been fed into NH3 receiver and
both sections (M.P. & L.P section) are pressurized
with ammonia vapors at 15 kg/cm2g and 3
kg/cm2g respectively.
MP carbonate solution pump (P-3) is running
with a weak ammonia solution in recycle to
Carbonate solution accumulator (via MP
condenser & MP absorber).

23. 23
Plant Preparation for Start Up
(section by section)
• M.P. & L.P. section preparation
To increase the ammonia content into this
solution, feed a small reflux flow to MP absorber
keeping the MP carbonate solution pump (P-3)
running in recycle.
Stop the ammonia reflux to MP absorber (C-1)
top only when the Carbonate solution
accumulator analysis indicates an ammonia
content of 35% by wt.

24. 24
Plant Preparation for Start Up
(section by section)
• M.P. & L.P. section preparation
Feed steam into shell sides of the M.P. and L.P
decomposers by opening the relevant control
valves valves of the 10 – 15 % and heat up these
equipment's by sending HW/LW at the inlet. Keep
a level on the M.P. & L.P. decomposer holders.
 Put the steam tracing in service in all the process
lines.

25. 25
Plant Preparation for Start Up
(section by section)
• Vacuum evaporation section
The evaporation section is to be put in water
recirculation to the urea solution tank via
vacuum concentrator/separator/urea solution
pump (P-8).

26. 26
Plant Preparation for Start Up
(section by section)
• Process water treatment section
The process water treatment section is
running water that from distillation tower
(C-2)

27. 27
Plant Preparation for Start Up
(section by section)
• CO2 compressor and passivation air system
Start and load the CO2 compressor and
stabilize it venting the CO2 to the atmosphere
from final discharge vent (pressure control
valve) in auto.
Open the passivation air flow and put in
service the O2 analyzer.

28. 28
Initial Start Up (Feed in)
• Following action to be taken for Feed in
– Send condensate to Reactor for 10 minutes.
– Feed NH3 for about 15 minutes.
– Feed CO2 to Reactor
– Feed Carbamate at Reactor overflow
– Start passivation air injection (K-3)
– Parameter stabilization and production started

29. 29
NH3 and CO2 Feed in
• Send condensate to
– Reactor (R-1)
– Carbamate condenser (E-5)
• For about 10 minutes by means of H.P. flushing pump
(KW injection points) and after that close the valves
and close HV1 (CO2 to R1).
• The NH3 present in the Reactor dissolves in the water
releasing heat and causing a temperature increase at
the Reactor bottom.

30. 30
NH3 and CO2 Feed in
• When the NH3 & H2O solution reaches the
saturation and this is shown by Reactor bottom
temperature that stops to increase (After about
10 minutes), proceed to open block valve and
motorized valve on NH3 discharge line and close
Carbonate recycle valve from H.P Separator.
• Then start feeding Ammonia to the Reactor. The
NH3 feeding flow rate must be about 50 rpm of P-
1 ammonia feed pump.

31. 31
NH3 and CO2 Feed in
• After about 15 minutes from introduction of
NH3,proceed to open the valves on CO2 to
Reactor, controlling the reactor bottom
temperature.
• Before feeding CO2 to Reactor, be sure to
inject the passivation air in CO2 stream

32. 32
NH3 and CO2 Feed in
• At the overflow (after about 2 hours since reactor
feed in) of the reactor,
– open Carbamate recycle valve HV-2 from H.P.
Separator,
– start sending the H.P Carbonate solution
(pump P-2 already running in circulation to
C-1)
– to the Carbamate condenser by opening the
relevant valves (HV-6). Monitor pump
amperage.

33. 33
NH3 and CO2 Feed in
• At reactor overflow,
• start opening the motorized valve (HV-5) at
Stripper outlet line and regulate the stripper
level controller (LV-2) in Manual mode.
• On manual mode adjust the opening of the
MS steam pressure control valve (PV-14)
admitting steam to shell side of Stripper,
checking that the bottom temperature never
exceeds 205°C.

34. 34
NH3 and CO2 Feed in
• The bottom pressure and temperature of
reactor shall be increased and maintained at
about 172°C and 155~160 kg/cm2.
respectively.
• As a corrective action the flow rates of NH3
and CO2 can be reduced or increased in order
to adjust temperature and pressure of reactor.

35. 35
NH3 and CO2 Feed in
• Temperature increase:
– The NH3/CO2 ratio is decreasing, with consequent
pressure reduction in the system, it is necessary to
increase NH3.
• Temperature decrease:
– The NH3/CO2 ratio is increasing, the pressure will
tend to rise, it is necessary to decrease NH3 or
increase CO2.

36. 36
NH3 and CO2 Feed in
• As a guide, the weight ratio NH3/CO2 to
reactor should be around 1.2-1.3 during this
phase.
• The M.P section is going to receive urea
solution.

37. 37
NH3 and CO2 Feed in
H.P loop heating (including
hot bolting)
10 to 12 hours
Condensate draining before
pressurization
½ hour
Pressurization with NH3 Via
start up line
3½ hours
NH3 and CO2 to reactor until
overflow occurs
2 to 3 hours
Stabilization of running
condition
2 to 3 hours

38. WEIGHT RATIO AT THE TIME OF EMPTY REACTOR FEED IN
155 160 165 170 175 180
155 160 166 173 163 191
30 min 60 min 90 min 120
90
100
110
120
130
140
150
160
Pressure
(in
ata)
Bottom Temp.
Top Temp.
Time (in min)
CO2:NH3, RATIO
1:3 1:2
PV-7A OPENED
PV-7A/B OPENED
REACTOR OVERFLO
0.0 MIN
K.W. FEED IN
THROUGH HV-1
CO2 FEED IN
NH3 FEED IN
0C
0C
min

41. M.P. SECTION STABLIZATION

42. 48
Shut Down
• Flushing
• Short shut down
• Long shut down
• Emergency shutdown

43. 49
Flushing system
• Urea plant shutdown main hazard is choking
• First and foremost priority is proper flushing
of the lines and vessels.
• There are three tier flushing system
– High pressure system
– Medium pressure system
– Low pressure system

44. 50
HP Flushing system
• Pump is a reciprocating one (P-11). It takes
suction from medium pressure pump
discharge and discharge water to different
high pressure loop washing point.
• Before starting KW washing, the pump
discharge pressure has to be set at 30Kg/cm2
more than that of high pressure loop pressure.

45. 51
HP Flushing system
• Before injecting flushing water confirm V-2
temp >60-70oC and drain the water first to
make the flowing water hot.
• Close the drain tightly and inject water.
• Check the KW pressure.
• Check if pressure has dropped or not. If
pressure has dropped that means line is clear.

46. 52
HP Flushing system
• If pressure has not dropped it means flushing
has not taken place.
• De-choke the line immediately and then do
the flushing.
• During HP loop flushing remember one
thing
– Do not open water simultaneously at numerous
points.
– Do flushing at one point at a time.

47. 53
MP Flushing system
• Pressure 36 kg.cm2 – a centrifugal pump(P-6).
• Water is going to :
– MP section,
– PV-07A D/S pipe
– HV-05 D/S pipe
– P-3 discharge
– P-2 suction
– P-8 discharge

48. 54
Plant shutdown
1. Short shutdown means:
– HP loop draining.
1. Long shutdown means:
– Necessitating HP loop draining.
1. Emergency shutdown
– Due to power failure.
– Due to cooling water failure.
– Due to instrument air failure.
– Due to steam failure.

49. 55
Short Shutdown Procedure
• As soon as CO2 compressor trips HV-1 gets
closed.PV-03 gets open. Close HV-08 and its
I/V.
• If P-1 pump has not tripped, give Ammonia to
Reactor for 10 minutes then stop P-1.
• Close HV-7 and I/V after P-1 has stopped.
• Close 2nd discharge valve of P-1A or B (which
ever is in line).
• Close HV-2.
• Stop P-2 (Carbamate pump).
• Close HV-6 & its I/V. Open FV-34.

50. 56
Short Shutdown Procedure
• Close PV-7A (if pressure is not getting hold, close
its I/V ).
• Close LV-02 & HV-05 after bringing down stripper
level to minimum.
• Increase HV-03 opening.
• Check P-10, P-6, P-11 (flushing pumps) are
running.
– P-11 discharge pressure 170Kg/cm2.

51. 57
LP Flushing system
• Normally low pressure flushing pump (P-10) is
always in line. it is a centrifugal pump with
discharge pressure 15 kg/cm2.
• Water goes to:
– LP section, Vacuum section, C-2 and LTs’ flushing.
• Remember P-8 discharge is having MP
flushing.

52. 58
Plant shutdown
1. Short shutdown means:
– HP loop draining.
2. Long shutdown means:
– Necessitating HP loop draining.
3. Emergency shutdown
– Due to power failure.
– Due to cooling water failure.
– Due to instrument air failure.
– Due to steam failure.

53. 59
Short Shutdown Procedure
• Divert prilling to V-5 via HV-132 immediately
after feed cut.
• Open PIC-140 & 141 first & second vacuum
pressure control valves.
• Divert ME-3 to E-14 (HV-140) towards V-5.
• Open LP flushing water at E-14 inlet.
• Open HW at P-8 discharge to displace the
Urea solution in the vertical line.

54. 60
Short Shutdown Procedure
• Run P-8 on water for at least 5min. on load.
• Be careful enough so that LV-138 at P-8
discharge should not get closed fully.
• P-8 discharge is not having any NRV so that
hold up solution in the vertical line gets
drained to MV-7 easily if LV-138 is open.

55. 61
Short Shutdown Procedure
• Close ME-2 level control valve after ME-2 level
is minimum.
• Check C-1 level. If required drain to V-3 via
HV-102. Close LIC-102.
• Reduce pure Ammonia reflux to C-1 according
to the temp. of C-1 top.
• Open P-3 recycle valve so that P-3 can have
enough recycle flow as auto recycle valve is
not there.

56. 62
Short Shutdown Procedure
• Wash CO2 line towards reactor. Check KW
pressure has reduced to confirm flushing.
• Check physically that HV-1 has opened in field
during flushing.
• Flush ammonia line D/S of HV-7 to reactor.
• Flush HV-2 up stream & down stream.
• Flush LV-2 towards E-1 through the flushing
line between LV-2 & HV-5. Then flush through
HV-5 by closing LV-2.

57. 63
Short Shutdown Procedure
• Flush PV-07A open KW between I/V & control
valve.
• Flush towards MV-1 then flush through PV-7A
by closing isolation valve & opening PV-7A.
• After flushing close PV-7A control valve.
• Flush HV-6 towards E-5 (Carbamate condenser)
by opening isolation valve of HV06.
• Flush P-2 discharge line down stream of NRV
with KW. First flush through FV-34 then close
FV-34. Let the line get pressurized open HV-6
check pressure has come down to confirm
flushing to E-5.

58. 64
Short Shutdown Procedure
• Open HW (MP flushing water) to LV-101 up stream &
down stream.
• Open HW to MV-2 from HV-5 D/S.
• Open HW to PV-7A D/S.
• Open HW in P-3 discharge & flush through LIC-102 to E-7.
• Flush HIC-102 line if C-1 draining is over.
• Open LW (LP flushing water) through ME-3 down stream
line to V-5.
• Open HW in C-1 to P-2 line.
• Flush P-2 (Carbamate pump) from suction thoroughly.
Check in open drain that water is clear of Carbamate.

59. 65
Short Shutdown Procedure
• Open HW (MP flushing water) to LV-101 up stream & down
stream.
• Open HW to MV-2 from HV-5 D/S.
• Open HW to PV-7A D/S.
• Open HW in P-3 discharge & flush through LIC-102 to E-7.
• Flush HIC-102 line if C-1 draining is over.
• Open LW (LP flushing water) through ME-3 down stream line
to V-5.
• Open HW in C-1 to P-2 line.
• Flush P-2 (Carbamate pump) from suction thoroughly. Check
in open drain that water is clear of Carbamate.

60. 66
Short Shutdown Procedure
• Flush and fill MV-8 (CO2 discharge drum)
thoroughly after de-pressurizing vessel.
• Reduce the steam to stripper, MP & LP
decomposer.
• Close PV-14, TIC-102 & its by-pass, TIC-131
& LV-03.
• Shut the reflux to C-1.
• Stop condensate to C-3 & C-4.
• Stop P-7 after E-11 level is minimum.

61. 67
Short Shutdown Procedure
PLEASE REMEMBER :
• Open KW only one point at a time.
• Confirm KW flushing by checking reduction in
KW pressure.
• Close the process isolation valve first & then
the water injection valve.
• HW & LW can be opened at various point
simultaneously.

62. 68
Long Shutdown Procedure
(HP loop draining)
• IF SHUTDOWN IS PRE-PLANNED
– CHECK R-1 DRAIN LINE PRIOR TO FEED CUT.
• Checking of R-1 drain line
 Check KW pressure is about 180Kg/cm2.
 Inject KW through R-1 drain line injection to HV-4 & HV-5.
 Be careful that R-1 open drain & close drain valves are tightly
closed.
 Open HV-4 & let KW to flow through HV-4 & HV-5 towards
MV-2.
 Check KW pressure has dropped to about 50Kg/cm2 to
confirm drain line is clear.

63. 69
Long Shutdown Procedure
(HP loop draining)
If pressure has not dropped, line is in choked
condition.
Do external steam heating U/S of HV-4.
Do pressurization & de-pressurization of line
up to HV-4 repeatedly by keeping HV-4 close.
Check again if drain line has got cleared in the
previous method.
If drain line is clear, start reactor draining.

64. 70
Long Shutdown Procedure
(HP loop draining)
• Keep the following valves conditions as follows;
• I/Vs of HV-6,HV-7and HV-8 close
• LV-2 close.
• HV-2 close.
• I/V of HV-102 open.
• PV-7A I/V close.
• HV-140 and its I/V open.
• Take E-2 steam trap in line

65. 71
Long Shutdown Procedure
(HP loop draining)
• Open Reactor drain I/V towards HV-4.
• Open HV-4 & HV-5.
• Open HV-1 (HV-1 inter lock to be by-passed
from I-1 on ESD)
• Feel the sound of flow.

66. 72
Long Shutdown Procedure
(HP loop draining)
• Check level has come in ME-2 in Control Room
& physically in side glass.
• Control the Reactor draining rate to MP
section using HIC-4 & HIC-1.

67. 73
Long Shutdown Procedure
(HP loop draining)
• Maintain Ammonia reflux to C-1 from P-5 to
maintain C-1 temperature.
• Maintain E-7 outlet temp. with LIC-102
minimum 30% open & with TIC-101 on auto.
• Maintain C-1 level by draining through HIC-
102 to V-3.

68. 74
Long Shutdown Procedure
(HP loop draining)
• Maintain Ammonia reflux to C-1 from P-5 to
maintain C-1 temperature.
• Maintain E-7 outlet temp. with LIC-102
minimum 30% open & with TIC-101 on auto.
• Maintain C-1 level by draining through HIC-
102 to V-3.

69. 75
Long Shutdown Procedure
(HP loop draining)
• Use greater amount of steam to E-2 without
over loading C-1 so that to recover a greater
amount of Ammonia to V-1.
• Check pressure drop is at a rate not more than
30Kg/cm2 per hour.

70. 76
• The temperature and pressure decline in the
synthesis system is controlled by adjusting the
reactor drain rate. The adjustment is made with
HIC-4 on manual control.
• Check the temperature in the low pressure
decomposer in view of getting the maximum
concentration of urea solution and avoiding and
excessive quantity of ammonia being delivered to
the vacuum concentration system.
Long Shutdown Procedure
(HP loop draining)

71. 77
Long Shutdown Procedure
(HP loop draining)
• When no solution is coming out from reactor
at a pressure of about ~40Kg/cm2 drain
Carbamate condenser to MV-2 through HV-4.
• Open HIC-2 and drain MV-1 to MV-2 thru’ HV-
4
• Confirm that draining is over, when LV-101 &
LV-131 gets almost closed.
• Cut HP loop from MP by closing HV-4, HV-5 &
PV-7A.
• Start depressurization of HP loop to BD header
through PV-7B.

72. 78
Long Shutdown Procedure
(HP Loop Draining)
• When the synthesis loop pressure and the
pressure of the medium pressure section are
equal, close the control valve HV-4 at stripper
bottom and wash all lines and equipment of the
high pressure section draining to the closed drain.
• Shut the steam to the decomposers, open the
washing on the outlet line bottom solution
stripper, bottom decomposer M.P. and L.P. and
flush together with 2 decomposers.

73. 79
Long Shutdown Procedure
(HP loop draining)
• Close the delivery valve and stop P-3A/B.
• Stop NH3 at the top of C-1 by FIC-103 in
manual control.

74. 80
Long Shutdown Procedure
(HP loop draining)
• Stop the ammonia booster pump and close the
suction and delivery valves.
• Send washing water to the top of C-1 for few
minutes.
• Drain the liquid of the C-1 to the carbonate tank
through HV-102 when washing is finished. Shut off
the water and drain the column to the closed drain.
• Isolate the NH3 tank and absorber from the other
medium pressure equipment, leaving the pressure
control in automatic position.

75. 81
Long Shutdown Procedure
(HP loop draining)
• Stop the vacuum section circulation after MV-
7 level comes to minimum & after confirming
proper flushing and PIC-140 & 141 open.
• Stop flushing water to E-14 & other points.
• Cut steams to E-14 & E-15.
• Cut the condensate outlet to condensate tank.
• Cut steam to ejectors.
• Cut cooling water to condensers, if required.
• Stop V-9 transfer to V-6 by stopping P-21, if
required.

76. 82
Long Shutdown Procedure
(HP loop draining)
• After depressurization and close draining of HP loop
is over open LP steam to reactor for 3-4 hrs.
• Cut steam to reactor/HP loop.
• Open MP washing water to HP loop through 3” quick
filling line at reactor bottom with HV-1 open PV-7B
open, HV-3 sample point drain open and HV-2 close.
• Filling completion of reactor is indicated by water
coming out from HV-3 sample point, close it.
• Filling completion of HP loop total is indicated by rise
in PV-7B pressure.

77. 83
Long Shutdown Procedure
(HP loop draining)
• If vessel man entry is to be permitted then overflow
HP loop through PV-7B for 7-8 hrs. Other wise 3-4
hrs overflow will do.
• Stop filling water, start draining HP loop from E-1
drain, from LV-2 sample point drain, from E-5 sample
point drain & HV-3 sample point drain.
• When water stops coming out from HV-3 sample
point drain, open reactor drain through HV-1 I/V
gradually to full open condition.
• Total draining normally takes 8-10 hrs.

78. 84
Long Shutdown Procedure
(HP loop draining)
• During HP loop draining, PV-7B should be
open, HV-2 should be close.
• During filling of HP loop E-5 shell side should
be depressurized & drained to enhance
cooling.
• Either steam circuit should be depressurized
or all tracing / jacket steam should be closed
and stripper shell side should be
depressurized.

79. 85
Long Shutdown Procedure
(HP loop draining)
• When water stops coming out from E-5 or E-
1 bottom drains, E-5 or E-1 may be handed
over.
• During condensate draining smell the drain
water for ammonia to have an idea of
atmosphere inside HP loop vessels.

80. 86
Electric Failure
• Should a total failure of electric power occur,
the CO2 compressor and all the pumps of the
unit will stop.
• In this case restart the plant, locally starting
up the machines not re-accelerated.

81. 87
Electric Failure
• If on the contrary, the power failure is more
than momentary, only the pumps of
emergency network will restart automatically.
But, in this case, the cooling water will be
missing and, as a consequence a pressure
increase will occur in the medium and low
pressure sections and vacuum will be lost in
the evaporation section.
• Then the plant must be stopped following the
instructions shown here under. Introduce
washing water to the following points :

82. 88
• Introduce washing water to the following points :
1. Inlet to the concentrator E-14.
2. Bottom outlet stripper and outlet of the medium
and low pressure decomposers.
3. P-3A/B delivery line and C-1 trays.
4. High pressure Carbamate pump suction and
delivery lines.
5. CO2 and NH3 lines to reactor Carbamate to
ejector HV-2 (up streams and down stream).
• Now proceed as described for normal shutdown.
Electric Failure

83. LAST UPDATED ON: Wednesday, February 28, 2007
Priority Merge De-merge Feeders trips through LMS Relief
P1 15 14.7
CPP
11KV T/SHIP FEEDER 1 AND 2, 11KV RAW
WATWR FEEDER 1 AND 2,
11 KV SILO FEEDER 1 & 2
UREA-1
LT FEEDER OF PMCC OF 11&21 STREAMS,
11MP1A/B, 11 MP2A/B, 21MP1A/B, 21MP2A/B,
11MP14A/B, 08MP01A/B/C(ONLY ONE MOTOR)
ALL 5 NOS. OF ID FANS
AMMONIA-1
MK-1801C, LH-1507(IF RUNNING)
UREA-2
MK-4801C
AMMONIA-2
CO2 BLOWER MK3801, MK-3801C, LH-3501(IF
RUNNING), LH -3205(IF RUNNING)
(CT FANS TRIPPED THROU' LMS IN AMM-1,
AMM-2, UREA-1, UREA-2 ARE NOT TO BE
STARTED WHEN ONLY ONE GTG IS RUNNING)
6.5
P2 21.5 21.2
UREA -1 (COOLING TOWER)
08 MP-1 A/B/C (2ND & 3RD MOTOR)
7.7
P3 22 22.5
AMMONIA-1 (CW)
MP-1801-A
(IF MOTOR IS TRIPPED UNDER LOAD
SHEDDING SCHEME, THEN, AUTO START
FROM LMS AFTER 5 MINUTES)
9
P4 22.6 22.3
UREA-2 (31 STREAM)
31MP-1 A/B, 31MP2 A/B
9.975
P5 24 23.7
UREA-2 (CW)
MP-4801 B
CPP
HRU-1/2/3 FD FAN BLOCKING
(SGFM-101, SGFM-201, MK-9901
11.425
P6 25.3 25
UREA-2 (41 STREAM)
41 MP01A/B, 41 MP-2 A/B, 31MP-14A/B
12.4
P7 27.7 27.4
UREA-2 (CW)
MP-4801 C, (MK-4801A, B, D, E)
13.9

84. 90
• The plant uses steam at 23Kg/cm2g in
stripper E-1.
• Failure of this service also involves the failure
of the condensate from the stripper which
feed the medium press. decomposer E-2 &
subsequently the Carbamate condensers E-5.
Steam Failure

85. 91
• The main plant and the ammonical water treatment
section should be shutdown since there will be no
steam production at 4.5kg/cm2g.
• The main machines must immediately be tripped :
1. CO2 compressor,
2. P-1A/B NH3pump, and
3. P-2A/B Carbamate pump.
• Column C-1 shall be recycled to V-3 and diluted,
sending water to P-3A/B delivery line. Wash and dilute
all lines of the high pressure section.
Steam Failure

86. 92
• Wash the medium and low pressure
decomposers outlet lines to avoid
crystallizations.
• Stop and dilute the vacuum evaporation
section following the procedure described for
normal shutdown.
Steam Failure

87. 93
• The plant is thus in a safe shutdown
condition and ready to restart following the
usual restarting procedure, in case of steam
failure and/or long plant shutdown, it is
necessary to further dilute the solution
contained in tanks and apparatuses
recovering it as soon as the steam availability
is assured.
Steam Failure

88. 94
Cooling Water Failure
• The plant equipment employing cooling water.
Principal users are:
– CO2 compressor (inter-stage cooler)
– All plant condensers
– Coolers, and the pump coolers.
• Lack of this service causes a pressure increases in the
medium and low pressure system for lack of
condensation in the respective condensers and
vacuum loss in the vacuum evaporation section.

89. 95
Cooling Water Failure
• Proceed as follows :
– Open one vent at least in the user located at the
highest point so as to avoid vacuum development
in the equipment of the cooling water circuit.
– Exclude from process the main machines and stop
them locally or directly from board if the
emergency case requires it, thus avoiding to
damage them. All the pumps except for the
washing pumps must be stopped. Washed and
emptied.
– Isolate from the board, the high pressure section
from the medium pressure one, after closing the
steam valve to the stripper and condensate valve
to decomposer E-2.

90. 96
Cooling Water Failure
–Switch to manual operation and close the
steam valve also to the medium and low
pressure decomposers, to both vacuum
evaporators and to the re-boiler at the
bottom of the column and the ejectors.
–send washing water to the delivery line of
P-3A/B to the trays of column C-1 to the
condensers E-11 and E-8 absorb NH3 thus
reducing the pressure, Now, proceed as
described for short shutdown.

91. 97
Long Shutdown Procedure
(HP loop draining)
• Gradually depressurize the absorption column and
the medium pressure decomposer through LV-101.
• Take care not to pressurize the low pressure
decomposer.
• Shut the steam to the decomposers E-3.
• Isolate the carbonate tank V-3 from C-1 leaving
pressure controller PRC-133 on auto.
• Dilute MP condenser E-7 and condenser E-11
solutions and drain them out.

92. 98
Instrument Air Failure
• In case off instrument air failure, the control
valves assume such positions as to ensure the
plant safety without the immediate
intervention of the operators, who however,
must be will aware of the general view of
these positions.

93. 99
Instrument Air Failure
• As soon as the instrument air is lacing, the
operator must switch to manual control all
instruments on board at zero signal position.
So that, when air gets in again, the valves do
not move.

94. 100
Instrument Air Failure
• The synthesis loop gets blocked and
automatically is isolated from the rest of the
plant. Shutdown must be actuated following
the same procedure as That described for the
electric power failure, acting however with the
local indicator instruments, since the
pneumatic signals are not available now no
board.

95. TROUBLE SHOOTING
• HIGH PRESSURE AMMONIA FEED PUMP TRIP
• HIGH PRESSURE CARBAMATE PUMP TRIP
• AMMONIA BOOSTER PUMP TRIP
• CARBAMATE PUMP TRIP

96. 102
Important Checks
Before feed cut communicate to Ammonia-II,
Urea-I & Bagging plant.
Check reverse rotation if any, for 31 K-1. High
speed recorder to be provided. Instrument
person should be called before tripping.
Before shut down keep 31 V-1 level at
minimum.

97. 103
Important Checks
Check both P-11 are available.
Keep P-11 running before feed cut.
Start P-10 and P-6 (LP & MP flushing pump)
before feed cut.

98. 104
Important Checks
Before shutdown R-1 drain line & E-5 drain
lines has been checked clear.
Before shutdown HIC-102 line has been
checked clear.

99. 105
Important Checks
After shutdown do proper flushing off HP, MP
& LP lines.
After S/D do proper flushing of vacuum
section with LW at E-14, P-8 circulation.
Confirm P-8 is taking load. Double confirm
vacuum section flushing.

100. 106
Important Checks
HP draining should be lined up without
wastage o time, if required.
After feed cut before depressurization close
air to reactor weep holes, if it is there.

101. 107
Important Checks
Isolate / drain E-7 CW circuit after MP loop
has been depressurized. Put tag on cooling
water I/V P-4 stopped.
Tag on B/L valves of HS line, NH3 line, LS inter
connection, LS export & CO2 line.

102. 108
Important Checks
Keep close check on P-33 level.
Put a fire hose without coupling in R-1 drain
line. Closely monitor B/L analysis.

103. 109
Important Checks
Isolate MV-8 and depressurize MV-8 after
compressor tripping. Flush MV-8.
Operate HV-8 I/V to see that it is fully operable.
After S/D & before start up.
Compressor / Turbine barring should be started
as soon as compressor is stopped. Ensure lube oil
circulation & drain of turbine is open.

104. 110
Important Checks
PV-03 isolation valve should be open before
compressor tripping.
CO2 suction valve should be closed after
compressor tripping.

105. 111
• Depressurize MP loop
–MV-2, E-7, C-1 & E-9 through 2” BD header
on C-1.
–E-9 should be kept isolated from V-1.
–HP loop should be kept isolated from MP
loop.
–Steam should be cut to E-2.
MP Loop Hand Over

106. 112
• After depressurization is complete start filling
water from bottom of vessels with C-1 BD
header valve open and also open vent
isolation valve on MV-2 vapor line open.
• When water starts coming out from MV-2
vent & C-1 BD header let the overflow
continue till the water gets almost clear of
ammonia or for 1-2 hrs.
MP Loop Hand Over

107. 113
• After depressurization is complete start filling
water from bottom of vessels with C-1 BD
header valve open and also open vent
isolation valve on MV-2 vapor line open.
• When water starts coming out from MV-2
vent & C-1 BD header let the overflow
continue till the water gets almost clear of
ammonia or for 1-2 hrs.
MP Loop Hand Over

108. 114
• Then stop filling and start draining from all
drain points.
• BD vent and open to atmosphere vent should
be open during draining.
• After the draining is over the MP loop vessels
barring V-1, E-11 & C-3 can be handed over for
opening to maintenance.
• Cooling water to E-7 and E-9 should be cut
only after depressurization is completed.
MP Loop Hand Over

109. 115
• Bring V-1 level to minimum before feed cut
whenever possible.
• HP loop draining through MP loop is over.
• Transfer V-1 ammonia if provision is their.
MP Loop Hand Over

110. 116
• Continue P-5 (ammonia booster pump) to run on
jacketed recycle with steam to jacket open.
Vaporize out ammonia through PV108.
• Condensate to C-3 should be close.
• E-11 cooling water should be minimize.
• Ammonia in put line to V-1 should be closed.
MP Loop Hand Over

111. 117
• Continue P-5 (ammonia booster pump) to run on
jacketed recycle with steam to jacket open.
Vaporize out ammonia through PV108.
• Condensate to C-3 should be close.
• E-11 cooling water should be minimize.
• Ammonia in put line to V-1 should be closed.
MP Loop Hand Over

112. 118
• V-1 should be tightly isolated from rest MP loop
before MV-2 to E-9 depressurization.
• Continue vaporizing ammonia till P-5 is taking load.
• Stop P-5 when V-1 is empty. Close P-5 discharge
valve tightly.
• Open close drain of V-1 & C-3/E-11.
• Simultaneously depressurize V-1, C-3/E-11 through
PV-108 to BD header.
• When depressurization is completed, start filling
water to V-1, C-3/E-11.
V-1 Handing Over

113. 119
• E-11 cooling water should be open during
depressurization.
• PV-108 should be open full during filling.
• Allow the water to over flow through PV-108
for some time.
• Stop filling, start draining through all drains
including P-5 suction strainer flange.
• After draining is completed, V-1& C-3/E-11
can be handed over to maintenance for
opening.
V-1 Handing Over

114. 120
• Keep V-3 level minimum before feed cut.
• After reactor draining through MP & LP is
over, flush the LP section thoroughly.
• Isolate V-3 from E-8(liquid & vapor line both)
if V-3 is not to be opened.
• Depressurize and drain ME-3-E-3-MV-3 & E-8
completely through the open to atmosphere
vent.
• Fill flush overflow & drain the system.
• During draining vent should be confirmed to
be open to atmosphere.
L P Loop Handing Over

115. 121
E-1 Handing Over
• After filling and draining twice check for
ammonia in E-1 drain and skin temperature.
• While draining 2nd time give SWP to open
alternate bolts.
• If NH3 in the drain sample in too high further
fill E-1 only and drain it.

116. 122
E-1 Handing Over
• If NH3 is not there in drain sample give SWP to
open man holes HV-3, LV-2, E-1 LT tapping
/thermocouple are to be removed.
• Put DM water hose at the top after E-1 top &
bottom cover is opened.
• Put air hose at bottom through LV-2 after it
gets opened.

117. 123
• Slip plate E-1 vapor line to E-5 (8” flange).
• Check whether V-29 has been depressurized
and drained.
• For E-1 shell side pressure testing give A’SWP
to blind following pts check steam circuit to V-
29 has been depressurized and drained.
• MS steam inlet flange 10”.
• Condensate outlet flange to V-29 6”.
• PSV-5 flange 6”.
E-1 Handing Over

118. 124
• Confirm first steam system is in
depressurized condition.
• Give SWP for blinds in following points.
1. Export condensate flange-4”
2. Import line NRV flange-2”
3. LG tapping – upper one LG auxiliaries
should be removed by instrumentation.
E-5 Handing Over

119. 125
4.Line from
•MV-4 –6”
• Steam outlet flange 2 no.-20”
5.PSV flanges
•2 no. –6”.
• E-5 shell side drain one no. 3”
•Total 8 blinds. LT tapping 2no.
E-5 Handing Over

120. 126
Lower LG tapping flange should be connected
with a flanged ½” nipple with isolation valve for air
injection.
• Simultaneously give SWP to open E-5, ME-1 after
confirming no ammonia in drain.
– E-5 manhole is to be opened.
– E-5 bottom and top flanges are to be gapped
so that air circulation can take place in E-5.
E-5 Handing Over

121. 127
• As soon as HV-1, HV-2 are opened put air hose
through the gap in the reactor.
• While giving SWP to open HV-1, HV-2 & PRC-
12.
R-1 Handing Over

122. 128
• Check –
1. R-1 open drains are in open condition.
2. R-1 CD are in closed position HV-4 close.
3. MV-8 is depressurized condition.
4. Confirm all the injections are closed.
5. Confirm P-11 is not running.
6. No water is coming out of HV-2 up stream
drain. Check HV-3 is removed
R-1 Handing Over

123. 129
7. P-1 to HV-7 is in depressurized and flushed
condition.
8. HV-7 isolation valve is in closed condition.
9. P-1 discharge valve is in closed condition.
10.PV-7A isolation valve is in closed condition.
R-1 Handing Over

124. 130
11.Tracing drains are open. Steam of circuit is in
depressurized condition.
12.Open 1 top thermocouples & thermo well
after R-1 first filling and draining.
13.Arrange to get R-1 top sample analyzed with
a blower and PVC piping arrangement.
R-1 Handing Over

125. 131
11.Tracing drains are open. Steam of circuit is in
depressurized condition.
12.Open 1 top thermocouples & thermo well
after R-1 first filling and draining.
13.Arrange to get R-1 top sample analyzed with
a blower and PVC piping arrangement.
R-1 Handing Over

126. Thank you