Operation of urea fertilizers plant

R-1E-1 MV-2 V-1 MV-3
SYNTHESIS SECTION
SAIPEM PROCESS
PRESENTED BY
Prem Baboo
National fertilizers Ltd. India.
An Expert for
www.ureaknowhow.com
Fellow of Institution of Engineers
India.
Plant & Equipment's Designer

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POINTS TO DISCUSS
START UP
SHUT DOWN
TROUBLE SHOOTINGS

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Initial start up
Cold start up
Hot start up
Start Up

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Start Up
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.

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

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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.

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

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Sealing Test
Fluid
– Steam condensate.
Temperature
– Ambient (cold test)
Pressure
– Operating value

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Sealing Test Conceptual Procedure
Admit the fluid from the lowest points and keep the
vent at highest points opened.
Slowly increase the pressure to the test value.
Check all flanges and connections in order to identify
leaks and eliminate them.
If the pressure does not fall appreciably after 4 hours
the test can be considered satisfactory, otherwise it
will be necessary to look and to eliminate them and
then repeat the test.

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Very Important
Keep the highest point vents in open position
during section emptying
Reactor draining to be started after completion
of draining of Carbamate condenser. This is to
avoid bulging of reactor lining.

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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.

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Purging By N2 - Conceptual Procedure
Admit Nitrogen keeping the pressure
controller in automatic mode.
When N2 comes out from drain close block
valves.
Depressurize the system up to positive
pressure of about 0.5 kg/cm2
Analyze the gas outlet. If O2 content is 0.1% by
vol. The purging is performed.

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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

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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%

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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

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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)

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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

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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.

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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.

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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.

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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.

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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 P1pump 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.

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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).

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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.

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Feed steam into shell sides of the M.P. and
L.P.decomposers by opening the relevant
control 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.

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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).

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Process water treatment section
The process water treatment section is running
water that from distillation tower (C-2)

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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.

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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

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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.

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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.

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NH3 and CO2 Feed in
After about 10 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

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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.Carbamate solution to the
Carbamate condenser by opening the relevant valves
(HV-6).
– Monitor pump amperage
(pump P-2 already running in circulation to C-1).

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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 207°C.

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NH3 and CO2 Feed in
The bottom pressure and temperature of reactor
shall be increased and maintained at about 179°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.

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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.

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NH3 and CO2 Feed in
As a guide, the weight ratio NH3/CO2 to
reactor should be around 1.15~1.2 during this
phase.
The M.P. section is going to receive urea
solution.

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M.P./L.P. sections going to receive urea
solution
As soon as urea from R-1 enters the E-1, a decrease
in steam pressure in the shell will be noticed.
Adjust the MS flow to E-1 according to E-1 bottom
temperature.
Feed Carbamate to R-1
Urea solution from E-1 bottom passes to MP
decomposer, then to LP decomposer and initially
to V-5 ( after stabilization, passes to vacuum
section).

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Slightly open manually FV-102 sending NH3 to the
top of the C-1 and keep recirculation of carbonate
solution from V-3 to C-1 controlling bottom level
and temperature.
Send condensate to top of C-3 so as to absorb NH3
present in the inert gas when level is established
at the E-11 bottom start P-7 and send sol. to C-1
and control the level.
solution

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Maintain MP/ LP urea holder temperature
Maintain MP /LP section pressure By putting PIC-
108 / PIC-133 on auto mode
Pre concentrator level and start the pump
Preconcentrator pump(P-50) and ww water
pump(P-52).Vacuum ejectors also to be taken in
line
solution

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NH3 and CO2 Feed in
H.P. loop heating (including hot
bolting)
5 to 8 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 1 hour

MP DECOMPOSER & AMMONIA ABSORBER

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Shut Down
Flushing
Short shut down
Long shut down
Emergency shutdown

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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

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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.

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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.

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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.

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

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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.

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Plant shutdown
1. Short shutdown means:
– HP loop hold up.
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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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 towards HV-4.
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.

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(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.

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(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
LV-3 ~10% open.
I/V of HV-102 open.
PV-7A I/V close.
HV-140 and its I/V open.

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(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.

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(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.

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(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.

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(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.

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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.
(HP loop draining)

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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.
(HP loop draining)

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(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
After feed cut and before depressurization of HP loop close
air to reactor weep holes
Confirm that draining is over, when LV-101 & LV-131 gets
almost closed.

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(HP Loop Draining)
When the synthesis loop pressure and the pressure of the
medium pressure section are equal:
Cut HP loop from MP by closing HV-1, HV-4, HV-5. and wash
all lines and equipment of the high pressure section
draining to the closed drain.
Start depressurization of HP loop to BD header through PV-
7B.
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.

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(HP loop draining)
Close the delivery valve and stop P-3A/B.
Stop NH3 at the top of C-1 by FIC-102 in manual
control.

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(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.

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(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.

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(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.

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(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.

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(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.

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88
(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.

R-1E-1 MV-2 V-1 MV-3
89
(HP loop draining)
When water stops coming out from HV-3 sample
point reactor top manhole cover should be opened
to enhance draining & cooling.
When water stops coming out from HV-3 sample
point, HV-3 may be handed over to maintenance, if
required.

R-1E-1 MV-2 V-1 MV-3
90
(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.

R-1E-1 MV-2 V-1 MV-3
91
EMERGENCY SHUT DOWN
The emergency situations which are likely to arise
are several and extremely variable as to duration
and seriousness.

R-1E-1 MV-2 V-1 MV-3
92
EMERGENCY SHUT DOWN
Principal causes:
1. Process reasons:
Considerable pressure and / or temperature increases
Pipe line clogging because of crystallization
2. Sudden failure of services
3. Fires, and / or ruptures with uncontrollable losses of
toxic gasses.

R-1E-1 MV-2 V-1 MV-3
93
EMERGENCY SHUT DOWN
Safety interlocks
Based on the above emergency causes, an interlock
trip system has been provided for the protection of
personal and equipment initiating an automatic
shut down system

R-1E-1 MV-2 V-1 MV-3
94
EMERGENCY SHUT DOWN
Safety interlocks
For point No. 3 (if occur) push buttons are
provided on urea desk to stop the principal
machines. The valves which isolate the synthesis
loop & NH3 to P-1will than be closed.

R-1E-1 MV-2 V-1 MV-3
95
The evaluation of the seriousness of an emergency
situation and there fore the decision of how to shut
the plant down is a matter of the operators’
experience. He should take prompt and corrective
action.
However, the inter lock system is designed to
minimize the number of manual operations.
EMERGENCY SHUT DOWN

R-1E-1 MV-2 V-1 MV-3
96
Should the point no. 1 occur lines and equipment
should be washed, the trip causes eliminated
EMERGENCY SHUT DOWN

R-1E-1 MV-2 V-1 MV-3
97
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.

R-1E-1 MV-2 V-1 MV-3
98
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.

R-1E-1 MV-2 V-1 MV-3
99
Electric Failure
Then the plant must be stopped following the
instructions shown here under. Introduce
washing water to the following points :
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.

R-1E-1 MV-2 V-1 MV-3
100
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).
Electric Failure

R-1E-1 MV-2 V-1 MV-3
101
Now proceed as described for normal
shutdown.
Electric Failure

R-1E-1 MV-2 V-1 MV-3
102
The plant uses steam at 23 kg/cm2g in
stripper E-1.
Failure of this service also involves the
failure of the condensate from the stripper
which feed the MP decomposer E-2 &
subsequently the Carbamate condensers
E-5.
Steam Failure

R-1E-1 MV-2 V-1 MV-3
103
The main plant and the ammonical water
treatment section should be shutdown since
there will be no steam production at
4.5kg/cm2g.
Steam Failure

R-1E-1 MV-2 V-1 MV-3
104
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

R-1E-1 MV-2 V-1 MV-3
105
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

R-1E-1 MV-2 V-1 MV-3
106
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

R-1E-1 MV-2 V-1 MV-3
107
Cooling Water Failure
The plant equipment employing cooling
water. Principal users are:
– CO2 compressor (inter-stage cooler)
– 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.

R-1E-1 MV-2 V-1 MV-3
108
Proceed as follows :
– Open E-41,E-9,E-7 top cooling water vents
– Stop feeding to the reactor. Trip compressor,
P-1,P-2 and all the pumps except for the washing
pumps must be stopped.
– Close LV-2,HV-5 and closing the steam valve
(PV-14) to the stripper

R-1E-1 MV-2 V-1 MV-3
109
– Close the steam valve to the E-2,E-3,to both
vacuum evaporators and to the column C-2 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.

R-1E-1 MV-2 V-1 MV-3
110
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.

R-1E-1 MV-2 V-1 MV-3
111
As soon as the instrument air is lacking, the
operator must switch to manual control all
instruments on DCS at zero signal position.
So that, when air gets in again, the valves do
not move.

R-1E-1 MV-2 V-1 MV-3
112
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.

R-1E-1 MV-2 V-1 MV-3
113
Important Checks
Communicate to the followings before S/D:
urea-I
Ammonia-II
Bagging
Check reverse rotation if any, for K-1.
Before shut down keep V-1, V-3 level at
minimum.

R-1E-1 MV-2 V-1 MV-3
114
Important Checks
Check both P-11 are available.
Keep P-11 running before feed cut.
Before shutdown R-1 drain line & E-5 drain
lines to be checked for any choking, clear
these lines if found choked.
Before shutdown HIC-102 line to be checked
for any choking, clear these lines if found
choked

R-1E-1 MV-2 V-1 MV-3
115
Important Checks
After shutdown do proper flushing of 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.

R-1E-1 MV-2 V-1 MV-3
116
Important Checks
After feed cut and before depressurization of
HP loop close air to reactor weep holes.

R-1E-1 MV-2 V-1 MV-3
117
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.
Isolate MV-8 and depressurize MV-8 after
compressor tripping. Flush MV-8.

R-1E-1 MV-2 V-1 MV-3
118
Depressurize MP loop
– E-9 should be kept isolated from V-1.
– MV-2, E-7, C-1 & E-9 through 2” BD header on
C-1.
– HP loop should be kept isolated from MP loop.
– Steam / MP steam condensate should be cut to
E-2.
MP Loop Hand Over

R-1E-1 MV-2 V-1 MV-3
119
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

R-1E-1 MV-2 V-1 MV-3
120
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

R-1E-1 MV-2 V-1 MV-3
121
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.
V-1 Handing Over

R-1E-1 MV-2 V-1 MV-3
122
E-11 cooling water should be open during
depressurization.
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

R-1E-1 MV-2 V-1 MV-3
123
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

R-1E-1 MV-2 V-1 MV-3
124
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

R-1E-1 MV-2 V-1 MV-3
125
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.

R-1E-1 MV-2 V-1 MV-3
126
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.

R-1E-1 MV-2 V-1 MV-3
127
Slip plate E-1 vapor line to E-5 (8” flange).
Check whether MV-4 has been
depressurized and drained.
E-1 Handing Over

R-1E-1 MV-2 V-1 MV-3
128
For E-1 shell side pressure testing give SWP
to blind following points, check steam circuit
to MV-4 has been depressurized and
drained.
MS steam inlet flange -10”.
Condensate outlet flange to MV-4 -6”.
MV-4 balance line- 2”.
PSV-5 flange- 6”.
E-1 Handing Over

R-1E-1 MV-2 V-1 MV-3
129
Check E-5 is isolated depressurized and
drained from shell side.
After filling tube side and draining E-5
second time with water check ammonia in
drain sample.
Check start-up line both E-1 side valves
closed.
E-1 vapor line to E-5 is also blinded.
E-5 Handing Over

R-1E-1 MV-2 V-1 MV-3
130
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

R-1E-1 MV-2 V-1 MV-3
131
4. Line from
1. MV-4 –6”
2. Steam outlet flange 2 no.-20”
5. PSV flanges
1. 2 no. –6”.
2. E-5 shell side drain one no. 3”
Total 8 blinds. LT tapping 2no.
E-5 Handing Over

R-1E-1 MV-2 V-1 MV-3
132
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

R-1E-1 MV-2 V-1 MV-3
133
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

R-1E-1 MV-2 V-1 MV-3
134
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

R-1E-1 MV-2 V-1 MV-3
135
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

R-1E-1 MV-2 V-1 MV-3
136
11. Tracing drains are open. Steam of circuit is
in depressurized condition.
12. Arrange to get R-1 top sample analyzed
with a blower and PVC piping arrangement.
R-1 Handing Over

R-1E-1 MV-2 V-1 MV-3
137
For any type of queries
Please contact to
Prem Baboo
Mob-+919425735974
+918718870316
Prem.baboo@nfl.co.in
pbaboo@hotmail.com

Operation of urea fertilizers plant

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