operation of urea fertilizers plant
TRANSCRIPT
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
R-1E-1 MV-2 V-1 MV-32
POINTS TO DISCUSS
� START UP
� SHUT DOWN
� TROUBLE SHOOTINGS
R-1E-1 MV-2 V-1 MV-33
� Initial start up
� Cold start up
� Hot start up
Start Up
R-1E-1 MV-2 V-1 MV-34
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.
R-1E-1 MV-2 V-1 MV-35
START UP
� CLEARANCE TO BE TAKEN FROM
1. MECHANICAL
2. ELECTRICAL
3. INSTRUMENT
� CLEARANCE TO BE TAKEN FROM
1. AMMONIA-II
2. UREA-I
R-1E-1 MV-2 V-1 MV-36
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.
R-1E-1 MV-2 V-1 MV-37
Sealing Tests Of All Sections
� Purpose
– To eliminate leaks, if any, before charging process
fluids.
R-1E-1 MV-2 V-1 MV-38
Sealing Test
� Fluid
– Steam condensate.
� Temperature
– Ambient (cold test)
� Pressure
– Operating value
R-1E-1 MV-2 V-1 MV-39
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.
R-1E-1 MV-2 V-1 MV-310
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.
R-1E-1 MV-2 V-1 MV-311
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.
R-1E-1 MV-2 V-1 MV-312
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.
R-1E-1 MV-2 V-1 MV-313
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
R-1E-1 MV-2 V-1 MV-314
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%
R-1E-1 MV-2 V-1 MV-315
Plant Heating Before Start Up
� Purpose
� Whenever start-up is to be performed with the unit emptyand at ambient temperature the equipment shall bepreviously heated in order to bring them to the bestconditions to feed the process fluids to the aboveequipment.
� This is to avoid:� Thermal stresses on the material
� Possibility of crystallization of products in cold piping and walls
R-1E-1 MV-2 V-1 MV-316
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)
R-1E-1 MV-2 V-1 MV-317
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
R-1E-1 MV-2 V-1 MV-318
Conditions Before Ammoniation
� M.P. section charged and pressurized by ammonia with NH3
booster pump running in closed recycle to Ammoniareceiver.
� L.P. section charged with NH3 solution and M.P. carbonatesolution pump(P-3) running in circulation to Carbonatereceiver(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.
R-1E-1 MV-2 V-1 MV-319
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.
R-1E-1 MV-2 V-1 MV-320
Ammoniation
� The main steps are:
1. Start the pressurization of the Synthesissystem by sending NH3 via Ammonia booster(P-5) to Start-up line, leaving opened thesuction and delivery valves of H.P.Ammoniapump (P-1).the NH3 is vaporized in the jacketline.
2. Control that the NH3 vapor temp is over140°C.
R-1E-1 MV-2 V-1 MV-321
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.
R-1E-1 MV-2 V-1 MV-322
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.
R-1E-1 MV-2 V-1 MV-323
Plant Preparation for Start Up(section by section)
� M.P. & L.P. section preparation
� Ammonia has been fed into NH3 receiver andboth sections (M.P. & L.P.section) arepressurized with ammonia vapors at 15kg/cm2g and 3 kg/cm2g respectively.
� MP carbonate solution pump (P-3) is runningwith a weak ammonia solution in recycle toCarbonate solution accumulator (via MPcondenser & MP absorber).
R-1E-1 MV-2 V-1 MV-324
Plant Preparation for Start Up(section by section)
� M.P. & L.P. section preparation
� To increase the ammonia content into thissolution, feed a small reflux flow to MPabsorber keeping the MP carbonate solutionpump (P-3) running in recycle.
� Stop the ammonia reflux to MP absorber (C-1)top only when the Carbonate solutionaccumulator analysis indicates an ammoniacontent of 35% by wt.
R-1E-1 MV-2 V-1 MV-325
Plant Preparation for Start Up(section by section)
� M.P. & L.P. section preparation
� Feed steam into shell sides of the M.P. andL.P.decomposers by opening the relevantcontrol valves of the 10 – 15 % and heat upthese equipment's by sending HW/LW at theinlet. Keep a level on the M.P. & L.P.decomposer holders.
� Put the steam tracing in service in all theprocess lines.
R-1E-1 MV-2 V-1 MV-326
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).
R-1E-1 MV-2 V-1 MV-327
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)
R-1E-1 MV-2 V-1 MV-328
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.
R-1E-1 MV-2 V-1 MV-329
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
R-1E-1 MV-2 V-1 MV-330
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.
R-1E-1 MV-2 V-1 MV-331
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.
R-1E-1 MV-2 V-1 MV-332
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
R-1E-1 MV-2 V-1 MV-333
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).
R-1E-1 MV-2 V-1 MV-334
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.
R-1E-1 MV-2 V-1 MV-335
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.
R-1E-1 MV-2 V-1 MV-336
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.
R-1E-1 MV-2 V-1 MV-337
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.
R-1E-1 MV-2 V-1 MV-338
M.P./L.P. sections going to receive urea solution
� As soon as urea from R-1 enters the E-1, a decreasein steam pressure in the shell will be noticed.Adjust the MS flow to E-1 according to E-1 bottomtemperature.
� Feed Carbamate to R-1
� Urea solution from E-1 bottom passes to MPdecomposer, then to LP decomposer and initiallyto V-5 ( after stabilization, passes to vacuumsection).
R-1E-1 MV-2 V-1 MV-339
� Slightly open manually FV-102 sending NH3 to thetop of the C-1 and keep recirculation of carbonatesolution from V-3 to C-1 controlling bottom leveland temperature.
� Send condensate to top of C-3 so as to absorb NH3
present in the inert gas when level is establishedat the E-11 bottom start P-7 and send sol. to C-1and control the level.
M.P./L.P. sections going to receive urea solution
R-1E-1 MV-2 V-1 MV-340
� 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
M.P./L.P. sections going to receive urea solution
R-1E-1 MV-2 V-1 MV-341
NH3 and CO2 Feed in
H.P. loop heating (including hot
bolting)5 to 8 hours
Condensate draining before
pressurization½ hour
Pressurization with NH3 Via start
up line3½ hours
NH3 and CO2 to reactor until
overflow occurs2 to 3 hours
Stabilization of running condition 1 hour
UREA REACTOR AND HP SEPERATOR
STRIPPER AND HP CONDENSER
AMMONIA START UP LINE
HIC4
MP DECOMPOSER & AMMONIA ABSORBER
R-1E-1 MV-2 V-1 MV-346
R-1E-1 MV-2 V-1 MV-3
R-1E-1 MV-2 V-1 MV-348
R-1E-1 MV-2 V-1 MV-349
R-1E-1 MV-2 V-1 MV-350
AMMONIA RECEIVER
LP SECTION
R-1E-1 MV-2 V-1 MV-353
Shut Down
� Flushing
� Short shut down
� Long shut down
� Emergency shutdown
R-1E-1 MV-2 V-1 MV-354
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
R-1E-1 MV-2 V-1 MV-355
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.
R-1E-1 MV-2 V-1 MV-356
HP Flushing system
� Before injecting flushing water confirm V-2 temp>60-70oC and drain the water first to make theflowing water hot.
� Close the drain tightly and inject water.
� Check the KW pressure.
� Check if pressure has dropped or not. If pressurehas dropped that means line is clear.
R-1E-1 MV-2 V-1 MV-357
HP Flushing system
� If pressure has not dropped it means flushing hasnot taken place.
� De-choke the line immediately and then do theflushing.
� During HP loop flushing remember one thing
– Do not open water simultaneously at numerous points.
– Do flushing at one point at a time.
R-1E-1 MV-2 V-1 MV-358
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
R-1E-1 MV-2 V-1 MV-359
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.
R-1E-1 MV-2 V-1 MV-360
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.
R-1E-1 MV-2 V-1 MV-361
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 for10 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 inline).
� Close HV-2.
� Stop P-2 (Carbamate pump).
� Close HV-6 & its I/V. Open FV-34.
R-1E-1 MV-2 V-1 MV-362
Short Shutdown Procedure
� Close PV-7A (if pressure is not getting hold, closeits I/V ).
� Close LV-02 & HV-05 after bringing down stripperlevel to minimum.
� Increase HV-03 opening.
� Check P-10, P-6, P-11 (flushing pumps) arerunning.
– P-11 discharge pressure 170Kg/cm2.
R-1E-1 MV-2 V-1 MV-363
Short Shutdown Procedure
� Divert prilling to V-5 via HV-132.immediatelyafter feed cut .
� Open PIC-140 & 141 first & second vacuumpressure 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 Ureasolution in the vertical line.
R-1E-1 MV-2 V-1 MV-364
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.
R-1E-1 MV-2 V-1 MV-365
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.
R-1E-1 MV-2 V-1 MV-366
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.
R-1E-1 MV-2 V-1 MV-367
Short Shutdown Procedure
� Flush PV-07A open KW between I/V & control valve.
� Flush towards MV-1 then flush through PV-7A by closingisolation valve & opening PV-7A.
� After flushing close PV-7A control valve.
� Flush HV-6 towards E-5 (Carbamate condenser) by openingisolation 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 getpressurized open HV-6 check pressure has come down toconfirm flushing to E-5.
R-1E-1 MV-2 V-1 MV-368
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 opendrain that water is clear of Carbamate.
R-1E-1 MV-2 V-1 MV-369
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.
R-1E-1 MV-2 V-1 MV-370
Short Shutdown Procedure
PLEASE REMEMBER :
� Open KW only one point at a time.
� Confirm KW flushing by checking reduction in KWpressure.
� Close the process isolation valve first & then thewater injection valve.
� HW & LW can be opened at various pointsimultaneously.
R-1E-1 MV-2 V-1 MV-371
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 drainline is clear.
R-1E-1 MV-2 V-1 MV-372
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.
R-1E-1 MV-2 V-1 MV-373
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
� LV-3 ~10% open.
� I/V of HV-102 open.
� PV-7A I/V close.
� HV-140 and its I/V open.
R-1E-1 MV-2 V-1 MV-374
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.
R-1E-1 MV-2 V-1 MV-375
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.
R-1E-1 MV-2 V-1 MV-376
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.
R-1E-1 MV-2 V-1 MV-377
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.
R-1E-1 MV-2 V-1 MV-378
� 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.
Long Shutdown Procedure (HP loop draining)
R-1E-1 MV-2 V-1 MV-379
� 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)
R-1E-1 MV-2 V-1 MV-380
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
� 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.
R-1E-1 MV-2 V-1 MV-381
Long Shutdown Procedure (HP Loop Draining)
� When the synthesis loop pressure and the pressure of themedium pressure section are equal:
� Cut HP loop from MP by closing HV-1, HV-4, HV-5. and washall lines and equipment of the high pressure sectiondraining to the closed drain.
� Start depressurization of HP loop to BD header through PV-7B.
� Shut the steam to the decomposers, open the washing onthe outlet line bottom solution stripper, bottomdecomposer M.P. and L.P. and flush together with 2decomposers.
R-1E-1 MV-2 V-1 MV-382
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-102 in manual
control.
R-1E-1 MV-2 V-1 MV-383
Long Shutdown Procedure (HP loop draining)
� Stop the ammonia booster pump and close the suction anddelivery valves.
� Send washing water to the top of C-1 for few minutes.
� Drain the liquid of the C-1 to the carbonate tank throughHV-102 when washing is finished. Shut off the water anddrain the column to the closed drain.
� Isolate the NH3 tank and absorber from the other mediumpressure equipment, leaving the pressure control inautomatic position.
R-1E-1 MV-2 V-1 MV-384
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.
R-1E-1 MV-2 V-1 MV-385
Long Shutdown Procedure (HP loop draining)
� Stop the vacuum section circulation after MV-7 level comesto 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.
R-1E-1 MV-2 V-1 MV-386
Long Shutdown Procedure (HP loop draining)
� After depressurization and close draining of HP loop is overopen LP steam to reactor for 3-4 hrs.
� Cut steam to reactor/HP loop.
� Open MP washing water to HP loop through 3” quick fillingline at reactor bottom with HV-1 open PV-7B open, HV-3sample point drain open and HV-2 close.
� Filling completion of reactor is indicated by water comingout from HV-3 sample point, close it.
� Filling completion of HP loop total is indicated by rise inPV-7B pressure.
R-1E-1 MV-2 V-1 MV-387
Long Shutdown Procedure (HP loop draining)
� If vessel man entry is to be permitted then overflow HPloop through PV-7B for 7-8 hrs. Other wise 3-4 hrsoverflow 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 pointdrain, open reactor drain through HV-1 I/V gradually to fullopen condition.
� Total draining normally takes 8-10 hrs.
R-1E-1 MV-2 V-1 MV-388
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 bedepressurized & drained to enhance cooling.
� Either steam circuit should be depressurized or alltracing / jacket steam should be closed andstripper shell side should be depressurized.
R-1E-1 MV-2 V-1 MV-389
Long Shutdown Procedure (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-390
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.
R-1E-1 MV-2 V-1 MV-391
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-392
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-393
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-394
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-395
� 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-396
� 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-397
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-398
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-399
Electric Failure
� Then the plant must be stopped following theinstructions shown here under. Introducewashing water to the following points :
� Introduce washing water to the followingpoints :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-3100
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-3101
� Now proceed as described for normal
shutdown.
Electric Failure
R-1E-1 MV-2 V-1 MV-3102
� 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-3103
� 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-3104
� The main machines must immediately betripped :
1. CO2 compressor,
2. P-1A/B NH3pump, and
3. P-2A/B Carbamate pump.
� Column C-1 shall be recycled to V-3 anddiluted, sending water to P-3A/B deliveryline. Wash and dilute all lines of the highpressure section.
Steam Failure
R-1E-1 MV-2 V-1 MV-3105
� 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-3106
� 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-3107
Cooling Water Failure
� The plant equipment employing coolingwater. Principal users are:– CO2 compressor (inter-stage cooler)
– Condensers , coolers and the pump coolers.
� Lack of this service causes a pressureincreases in the medium and low pressuresystem for lack of condensation in therespective condensers and vacuum loss inthe vacuum evaporation section.
R-1E-1 MV-2 V-1 MV-3108
Cooling Water Failure
� 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-3109
Cooling Water Failure
– 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-3110
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-3111
Instrument Air Failure
� 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-3112
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.
R-1E-1 MV-2 V-1 MV-3113
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-3114
Important Checks
Check both P-11 are available.
Keep P-11 running before feed cut.
Before shutdown R-1 drain line & E-5 drainlines to be checked for any choking, clearthese lines if found choked.
Before shutdown HIC-102 line to be checkedfor any choking, clear these lines if foundchoked
R-1E-1 MV-2 V-1 MV-3115
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-3116
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-3117
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-3118
� 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-3119
� 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-3120
� 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-3121
� 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-3122
� 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-3123
� PV-108 should be open full during filling.
� Allow the water to over flow through PV-108for some time.
� Stop filling, start draining through all drainsincluding P-5 suction strainer flange.
� After draining is completed, V-1& C-3/E-11can be handed over to maintenance foropening.
V-1 Handing Over
R-1E-1 MV-2 V-1 MV-3124
� Keep V-3 level minimum before feed cut.
� After reactor draining through MP & LP is over, flushthe LP section thoroughly.
� Isolate V-3 from E-8(liquid & vapor line both) if V-3 isnot to be opened.
� Depressurize and drain ME-3-E-3-MV-3 & E-8completely through the open to atmosphere vent.
� Fill flush overflow & drain the system.
� During draining vent should be confirmed to be opento atmosphere.
L P Loop Handing Over
R-1E-1 MV-2 V-1 MV-3125
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-3126
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-3127
� 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-3128
� For E-1 shell side pressure testing give SWPto blind following points, check steam circuitto MV-4 has been depressurized anddrained.
�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-3129
� Check E-5 is isolated depressurized anddrained from shell side.
� After filling tube side and draining E-5second time with water check ammonia indrain sample.
� Check start-up line both E-1 side valvesclosed.
� E-1 vapor line to E-5 is also blinded.
E-5 Handing Over
R-1E-1 MV-2 V-1 MV-3130
� 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-3131
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-3132
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-3133
� 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-3134
� 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 streamdrain. Check HV-3 is removed
R-1 Handing Over
R-1E-1 MV-2 V-1 MV-3135
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-3136
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-3137
For any type of queries
Please contact to
Prem Baboo
Mob-+919425735974
+918718870316