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A CASE STUDY OF CO2 REMOVAL SYSTEMPROBLEMS/FAILURES IN AN AMMONIA PLANT
The paper addresses the various problems/failures experienced in the CO2 removalsystem of an Ammonia Plant in a short span operation of less than one year. Probable causesof failures and the corrective steps taken to avoid such failures in future, have also beendiscussed.
V.K. BALI and A.K. MAHESHWARI
IFFCO Aonla Unit, Bareilly Uttar Pradesh, India
INTRODUCTION
Located at Bareilly, Uttar Pradesh in India, Indian Farmers Fertiliser Cooperative Ltd,operates two Ammonia plants, each with a name plate capacity of 1350 MTPD of ammonia.Both of these plants have been designed based on Haldor Topsoe technology with steamreforming of natural gas and/or naphtha. Ammonia-1 is designed for natural gas feed stockand was commissioned in 1988. Ammonia-2 was commissioned in December,1996 and isdesigned for both Natural Gas & Naphtha feed stocks. The Benfield process was selected forthe CO2 removal system of Ammonia-1 which has been converted into Giammarco- Vetrocoke(GV) dual activator system in April,1997 for achieving lower CO2 slip and energy savings.For Ammonia-2 plant, the GV dual activator low energy process has been selected for CO2removal system from the design stage. The paper describes the problems/failures experienced inthe CO2 removal system of Ammonia-2 plant during very first year of its operation.
PROCESS TECHNOLOGY ADOPTED FOR CO2 REMOVAL SYSTEM
CO2 removal system of Ammonia Plant has a conventional design based on the GV dualactivator process. The process comprises of single stage absorption and two stageregeneration. Figure-1 shows the CO2 removal system flow sheet.
Carbon dioxide is removed by absorption in hot aqueous potassium carbonate solutioncontaining approximately 30 wt% potash (K2CO3) partly converted into bicarbonate(KHCO3). The solution further contains dual activators to effectively improve the overallperformance of the system . Vanadium oxide is used as corrosion inhibitor.
The process gas from the shift reactors is passed to the Vetrocoke Absorber whichcontains stainless steel packing material distributed in 5 beds. The absorption is carried out inone stage. The major part of the circulating solution is fed without cooling to the middle ofabsorber at about 241° F (116 °C). The remaining solution is fed to the top of absorber aftercooling to about 140° F ( 60 °C). In the lower zone of absorber, the bulk of the CO2 is
absorbed. In the upper zone,the reduced stream of cold solution is used to get low CO2slippages due to the low CO2 vapour pressure of the dual activated solution.
The solution leaving the absorber bottom, loaded with CO2 is called the rich solution. Therich solution is transferred to a two stage regeneration system operating at low pressures. Therich solution is depressurised through the hydraulic turbine and is sent to the top of the 1stRegenerator operating at 14.2 psig (1.0 Kg/cm2g) pressure. A stream of rich solution extractedfrom the top of 1st Regenerator is depressurised through a control valve and enters the top ofthe 2nd Regenerator,working at low pressure of 1.42 psig (0.1 Kg/cm2g).
CORROSION CONTROL IN CO2 REMOVAL SYSTEM
GV solution along with CO2 at boiling temperature is very corrosive and would normallyrequire stainless steel equipment. However, carbon steel equipment with passivationlayers (oxidation layers) are being used successfully. The desired passivation layer isformed by controlled passivation in two phases called static passivation & dynamicpassivation. The layer formed is tight, magnetic & tenacious and protects the carbon steelsurfaces from corrosion. However, rubbing with hard sharp edges can scratch the layer. The GVsystem uses vanadium as corrosion inhibitor. The recommended concentration of totalvanadium is around 0.5% by weight as V2O5.
The hot potassium carbonate inhibited with vanadium can be safely operated, but is verysensitive for corrosion. In order to maintain the electro-chemical potential required forprotection of passivation layer of metallic surfaces, it is necessary to keep 30 to 40% of thetotal vanadium in the pentavalent form and never be allowed lower than 20% . This ratio is keptby means of the oxidation unit which treats a side stream solution with air.
Hence, formation of proper passivation layer and its protection is very essential to avoidcorrosion in the GV system equipment. Any damage to the passivation layer can cause very fastcorrosion & subsequent leakages.
PROBLEMS/FAILURES EXPERIENCED
The various problems faced in the CO2 removal system of Ammonia Plant have beenpresented. Each problem/failure has been dealt with separately specifying the problem/failurefaced, cause of the problem and various corrective steps undertaken to avoid such occurancein future.
2nd Regenerator
The 2nd Regenerator is a carbon steel tower provided with stainless steel internals andoperating at a pressure of 1.42 psig (0.1 Kg/cm2g). It is a packed tower having 129 inches (3230mm) diameter, 1643 inches (41075 mm) height and contains stainless steel packing materialdistributed in two beds. Broad specifications and the general arrangement drawing of 2ndregenerator are shown at figure-2.
Problem/failure description
Based on the failure history of this equipment in other plants, it was decided to measure thethickness of 2nd Regenerator shell in the failure prone zones after about 9 months ofoperation. While the thickness measurement was in progress between A-2 and A-7 nozzles, aleak was observed on the other side of the shell on 11.9.97. This leak was located approximately6 inches (150 mm) above the A-2 nozzle and 88 inches (2200 mm) circumferentially towards M-3 manhole. Initially, a hole of approximately 0.8 inches (20 mm) diameter was observed whichenlarged to a bigger size "Eye shaped" hole within 2 hrs of start of leakage as shown infigure-3.
Thickness measurements were carried out around the leaking hole to ascertain the extent ofthining in shell. No thinning was found even around the hole, leading to the conclusion thatthe failure was localized as shown in figure 4. The area of leakage was covered and weldedwith SS-304, 8" sch 10 pipe with blind and a vent to arrest the leakage. The whole exercisewas carried out while the plant was in operation and the equipment was in line.
As a preventive measure, it was decided to carry out thickness measurements around theeffected area of the shell on a regular basis. It was observed that the thickness had been reducedto as little as 0.56 inches (14 mm) around the 8" stainless steel pipe, which had been welded tocontain the leak. Stainless steel pads were welded around the 8" stainless steel pipe tostrengthen the shell. The 2nd Regenerator was opened for inspection in October,1997. Ahole of approximately 12 inches (300 mm) diameter was observed from inside. Welding of thecleat between SS 304 shroud and the vessel was also found broken.Photograph (PH-1) showsthe damaged 2nd Regenerator shell.
In addition to the leakage in the shell,the following upset conditions of a minor nature were alsoobserved in the 2nd Regenerator. • Three segments of the steam distributor above the chimney at elevation of 644 inches
(16100 mm) were found lifted from their support beam by about 6 to 8 inches (150 to200 mm ) as shown in Figure-5. Photograph (PH-2) shows the disturbed internals of thesteam distributor.
• The bed no.1 liquid re-distributor (Norten type) at elevation of 26750 mm was found
lifted from its support ring by about 50 mm on one side as shown in Figure-5.
Cause of the problem
The mechanical design of the fluid entry zone of 2nd Regenerator was found to beinadequate.
The support design of the stainless steel protective shroud was inadequate for the dynamicloads. This resulted in the shroud supports cracking and allowing the cleats of the shroud to hitthe wall which broke the protective vanadium layer on the carbon steel shell. This allowedrapid corrosion of the shell and subsequent failure of pressure vessel (Figure 6).
Upon investigation, it was also discovered that the material of the cleats was carbon steel ratherthan the stainless steel material specified on the approved drawings. Also the number of cleatsprovided were at variance with the approved drawings.
It was further concluded that an internal annular passage should be avoided if possible to safeguard the installation against even the slightest possibility of any means of damaging thepassivation layer. The welding of cleats to the shell to support the annular passage which islikely to have some degree of vibration due to the process conditions, was identified to presentsuch a possibility.
Various design options
Design problems in the fluid entry zone of 2nd Regenerator were reported in 1993 in a 900MTPD ammonia plant operating in southern part of India. The flow was directly hitting thechimney which broke off and rubbed against the tower wall. This resulted in damage to thepassivation layer and caused corrosion which, in a short period of time, resulted in equipmentfailure. Another operating problem experienced in this equipment, was the difficulty inmaintaining the proper solution level.
During the engineering and procurement phase of IFFCO-Aonla Unit,it was decided toreengineer the inlet arrangement using a Norton type inlet arrangement and providing anannular passage . The inlet arrangement was designed to divert the flow in two directionshorizontally to avoid direct impingement on the chimney. A stainless steel annular passage wasprovided to prevent liquid impingement on the shell and possible disturbance of thepassivation layer which could cause excessive corrosion . An annular passage was providedwith an annular ring at the lower end to limit the disturbance of the surface i.e. to improvelevel measurement. The above arrangement is shown in Figure-7. Photograph (PH-3) showsthe original inlet distribution arrangement.
However, ammonia plant of Aonla Unit and other similar plants based on above design havereported failures in this equipment in the fluid entry zone.
Yet another design option has been considered which has now been adopted and is describedseparately in the paper.
Repairs/modifications • The area of 24 inches x 24 inches (600 mm x 600 mm) which was patched up from outside to
arrest leakage while the plant was in operation, was removed. A new matching plate ofthe same size was welded into the shell.
• The existing nozzle entry configuration and stainless steel shroud was dismantled and
removed. • A new arrangement of the distributor and supporting arrangement as shown in
Figure-8 was provided. This arrangement removes the possibility of damaging thepassivation layer. At the same time, it ensures that the GV solution is uniformlydistributed throughout the circumference of 2nd Regenerator and does not hit thechimney and the surface of the tower.
Vetrocoke Absorber
The Vetrocoke Absorber is a carbon steel tower with stainless steel internals operating at 398psig (28 Kg/cm2g) pressure. It contains stainless steel packing material distributed in fivebeds. Liquid distributors and redistributors (called LRD) of stainless steel material have alsobeen provided. Broad specifications and the general arrangement drg.of Vetrocoke Absorberis presented as figure-9.
The overall performance of Vetrocoke Absorber was satisfactory as the CO2 slip at theAbsorber exit was less than the design figure of 300 ppm. However, a detailed analysis ofthe performance of each bed conducted in August,1997, indicated that the second bed was notperforming satisfactorily. Maldistribution of GV solution at top of the 2nd bed was thought to bethe probable cause and it was decided to open the Absorber at the earliest opportunity.
Problem/failure description
The Ammonia plant was shutdown in October,1997 and this opportunity was utilised toopen the various manholes of Absorber for inspection. The following failures were found asobserved from various manholes.
Location : M3 manhole
This manhole is located between bed No.2 and bed No.3 at an elevation of 1056 inches(26400 mm).
The Bed no.2 liquid redistributor (Norton type) called LRD located at elevation of 1030 inches(25750 mm ) was found buckled at the top and the J-bolts supporting the distributor had gotsheared. The LRD was raised about 6 to 8 inches (150 to 200 mm) from its support ring.
Further upward movement of the LRD was restricted by the semi-lean solution distributionparting boxes placed above it, and by the semi-lean solution distribution pipes of nozzles A2and A3 located at elevation of 1066 inches (26640 mm).
The distance between the LRD and the bed no.3 containing IMTP 40 stainless steel packing,had been reduced to around 24 inches (600 mm). A few loose rings were also found at the top ofthe LRD.
The parting box was also found damaged and buckled at the ends.
A few 8 inches NB nipples attached with the semilean solution distributor pipes of A2 &A3 nozzles were also found twisted.
The details indicating the above failures are given in figure - 10.
Location : M4 manhole
This manhole is located between bed no.1 & 2 at an elevation of 631 inches (15780 mm).
The Bed no.1 liquid redistributor (Norten type) called LRD located at elevation of 610 inches
(15250 mm) which should have been below the M4 manhole level, was found hanging atapproximately 20 inches (500 mm) above the top of the manhole. The LRD was found indistorted condition and its middle portion had taken convex shape viewed from bottom.
The whole bed no.1 had lifted up by approximately 64 inches (1600 mm) from its originalposition. Loose IMTP 50 packing of Bed No.1 were found all around the M4 manhole.Photograph (PH-4) & Photograph (PH-5) indicate the disturbed beds of Absorber.
The support beam of bed no.1 LRD with its ends distorted was found loose above manhole M4and being stuck up at ring support of Bed No.2.
The multi-beam support plate of bed no.2 along with its supporting beam was not clearlyvisible. The beam had sheared from its support bracket and entered in the IMTP 40 packing ofbed no.2 after leaving its original position.
Probable causes • The possibility of construction defects and weak structure of the tower internals were
considered to be probable causes of the failure. The plate thickness used for bed supportsand clamps was only 2 mm. The extent of damage, however suggested that forces ofgreat magnitude acted in the upward direction in the Absorber. Hence the cause of thefailure can not be attributed only to the weak design . Further, Absorbers of the samedesign have been reported operating satisfactorily in other plants without anyproblems.
• The other possibility could be some sudden upward gas surge through the 1st & 2nd bed of
Absorber which caused the upheaval of these beds and buckling of LRDs.
The process gas entering at the bottom of Absorber might have flowed backwards throughthe semi-lean inlet line via the ARC-NRV circulation line back to the solution draw -offtray in the 2nd Regenerator. The upward lifting of the steam distributor above thechimney in the semilean solution draw off tray and also the uplifting of the 1st bed LRD ofthe 2nd Regenerator seems to support this view.
However, the above back flow could take place through this route only when bothARC/NRV valves & the solenoid operated valves are not holding.
A study of the construction of the ARC/NRV valves indicated that a large quantity of gaspassing backward through the NRV portion and then through the ARC portion couldbe possible only if the internals of the valve were severely damaged. These valves wereopened to check their condition. The springs of these valves were found broken. The discsof these valves were also getting stuck up. The above conditions were creating possibilitiesof back flow.
Each semi-lean pump had a solenoid valve at the discharge which closes when the pumptrips via the interlock I-301 A/B/C. For back flow to take place, these discharge valvesmust be in open position . This can take place if the discharge valve does not close duringthe tripping of the pumps, due to failure of the interlock I-301. Mal-functioning of thisinterlock, however could not be confirmed.
Further, the back flow through the above route may result in reverse rotation of the semi-lean pumps. However, no damage to these pumps due to reverse rotation was observed.However, the absence of a reverse rotation of the semi-lean pump could be explained bythe reasoning that the liquid passing in back flow through the valve was prevented by themotion of the decelerating machine.
• Another probable cause for the damage in the Absorber could be the fast depressurisation of
the Absorber by sudden opening of vent valve (PV-60) located downstream of the Absorber.This could have occured during start up/shutdown of the plant. However,depressurisation through this route could have resulted in the failures of 3rd and 4th bed aswell. No failure in these beds, however, were found. This could be explained because the3rd and 4th beds are inherently stronger than the 1st & 2nd beds as the diameter there is99 inches (2480 mm) compared to 150 inches (3750 mm) at the 1st & 2nd beds, eventhough the internals & fittings are of the same thickness.
Repairs/modifications
The following corrective actions have been suggested based on all probable causes of failuresas discussed above - • All damaged internals will be replaced with next higher thickness. • In order to prevent back flow, the solenoid valves should be interlocked with low speed of
turbines of the semilean solution pumps and lean solution pumps so that before all theliquid is drained off, the valve would have completely closed.
• The semi-lean flow control valve (FV-22) and the lean solution flow control valve
(FV-23) should close shut on very low solution flow. • Extreme care should be taken to ensure that the downstream vent valve (PV-60) is not
opened suddenly under any circumstances. • An additional NRV on each of the common headers of the semilean solution line and the
lean solution line should be provided.
Hydraulic Turbines
The rich GV solution at high pressure coming from the bottom of the Absorber is let down andflashed in the upper portion of the Ist Regenerator operating at low pressure. This let down inpressure is carried out through hydraulic turbines to supply power to turbine driven GVsolution pumps and thus reduce the steam consumption of turbines.
Problem/failure description
It was observed that the hydraulic turbine was not developing power as per design andthus the steam consumption of steam turbines was high. On inspection, the casing vanes ofhydraulic turbines were found to be eroded.
Probable causes
Butterfly control valves have been provided at the inlet nozzle of the hydraulic turbine. Theshaft pins of these valves have also been found to be broken probably due to flashing. Thesudden increase in volume and the two phase flow at the turbine inlet nozzle were theprobable causes of the damage to the hydraulic casing vanes.
Repairs/modification
The butterfly control valves have now been shifted away from the inlet nozzle of hydraulicturbine to achieve laminar flow to the turbine inlet as shown in figure-11.
1st Regenerator
The 1st Regeneator is a carbon steel tower provided with stainles steel internals withoperating pressure of 14.2 psig (1 kg/cm2g). It is a packed tower having 147 inches (3680mm) diameter, 1855 inches (46375 mm) height and contains stainless steel packing materialdistributed in three beds.
Problem/failure description
The rich solution line (20") carrying rich solution from the bottom of the Absorber to the topof 1st Regenerator through two inlet nozzles, was vibrating heavily. Frequent leaks wereobserved at the welding joints at the upstream stub end of the butterfly valves provided in theinlet lines & these leakages were recurring frequently.
Probable causes
The rich solution line is divided with two branches near the 1st Regenerator and hence entersthe vessel at two points. In both the branches, butterfly valves have been provided near the 1stRegenerator. These valves were causing restriction in the flow & hence the vibration in thelines. Vibration resulted in the increased load on the welding joints and the failure of the joints.
Repairs/modifications
Both the 20" butterfly valves and flanges were removed and the gaps were filled by providing20" SS-304 spool pieces.
GV Regenerator
The GV Regenerator in CO2 removal system of Ammonia-1 has been in operation since 1988.The plant was originally built with the Benfield process and was converted to the GV dualactivator process in 1997.
The Regenerator is a carbon steel tower provided with stainless steel internals andoperating at 14.2 psig (1.0 Kg/cm2g) pressure. It is a packed tower having 196 inches (4900mm) diameter, 1796 inches (44900 mm) height and contains stainless steel packing materialdistributed in three beds. Rich solution to the regenerator is fed through two tangentialenteries (called a necklace) as shown in figure-12. The above two inlet nozzles are welded to the8 mm thick stainless steel liner provided to protect the carbon steel shell from severe inlet flow
conditions. Broad specifications and the general arrangements drawing of GV regenerator arepresented in Figure-12.
The CO2 removal system of Ammonia Plant has been operating normally except that theCO2 slip was high at around 1400-1600 ppm. A consultants' expert in these systems , was calledin the last week of September,1997 to analzse the problem of high CO2 slip. Following therecommendations of this consultant , various chemicals were added to the system to increase theconcentration of chemicals in the solution.
Only marginal advantage in the reduction of CO2 slip was observed. However, it was observedthat the iron content in the solution was increasing. The iron content in the solution hadincreased from 67 PPM on 30 September,1997 to 127 ppm on 15 October,1997 in a very shortspan of two weeks time and was a clear cut indication of heavy corrosion taking place in thesystem.
V+5 to total V ratio was being maintained at the same level of around 15% as was maintainedwith Benfield system. KNO2 and V2O5 however, were added to increase the ratio of V+5/Vto stop further corrosion. But iron level continued to increase in the solution.
It was observed on 18 October,1997 that GV Regenerator had started leaking from the top,resulting in continuous GV solution droplets falling down. The leaking zone wasthoroughly inspected and the leak was arrested by welding. On 21 October ,1997 another leakwas observed about 180 Degree opposite the previous leak. An attempt was made to arrestthe leakage by providing a box around it. This was not possible as the vessel thickness had beenreduced by corrosion to the extent that welding was impossible. Thickness measurementsshowed patches of reduced thickness. It was decided to shutdown the plant and carryouta thorough inspection and repair.
Problem/failure description
The Ammonia Plant was shutdown in October ,1997 to carryout thorough inspection andrepair of GV Regenerator. On opening the Regenerator, the following observations were made. • Black colour deposition was found above the shroud. • Both the necklace weld joints with liner were found cracked at two places in each joint. The
length of crack was about 12 inches (300 mm). • The liner plate had got deformed and was touching the Regenerator main shell at several
places as shown in figure-13 . The gap between the liner and the shell should be 10 mm asper design ( figure-14).
• Heavy corrosion on the shell near and including the tray support ring was found at three
places as shown in figure-15. • Corrosion of the shell at several places just below the lower edge of SS liner were also
found as shown in figure-15. • Lower cleats welding with liner were found cracked.
• Some of the weldings of end plates of Omega trays were found broken. At two places, end
plates were missing. A broken piece of 690 mm x 280 mm was also found loose.
Probable causes
The following reasons put together can be attributed to the fast corrosion in the GVRegenerator and its subsequent leakage. • The stainless steel liner plate became deformed and was touching the shell at various
places. Cleats of the liner were also found cracked. Also there is two phase flow at theinlet. This must have resulted in vibrations in the liner and damaged the passivationlayer. The places where there was no gap between shell & liner corrosion could be due tostagnated solution.
• V+5/V ratio was slightly on the lower side at around 15% in comparison to the consultants
recommendations of minimum value of 20% and probably was not sufficient to give thedesired protection to carbon steel shell.
• Increase in concentration of chemicals further aggravated the situation for corrosion.
Repairs/modifications
• It was decided to cut the liner by about 8 inches (200 mm) from the bottom at the placeswhere there were no gaps between the liner and the shell to check for further damageto the shell. After cutting, it was discovered that some of the shell areas and thecircumferential seal welds behind the liner were found badly corroded. Another 18 incheswide by 80 inches long (450 mm x 2000mm) section of liner was removed to inspect thecondition of the shell. No further corrosion was observed on the shell behind the liner.
• A total of about 35 stainless steel cleats were welded behind liner to maintain a uniform
gap between the liner and the shell throughout the periphery .This was done to ensure nofurther contact between the liner and shell in the future to avoid damage to thepassivation layer and to avoid stagnation of the solution.
• Some of the welding of end plates of omega trays which was found to be broken, was
rewelded. • All the corroded areas of shell were repaired by filling material with welding. All the
repair welds were ground finish and DP tested. The 18 inches (450 mm) width liner wasrewelded in position.
• The cracks on both necklace to liner joints were also repaired & DP tested.
CONCLUSION
The failure presented in the paper were caused by a number of different factors includingdesign deficiencies,defects introduced during manufacturing or fabrication, service relateddeterioration , and upsets during plant operation etc.
The cases presented do not indicate that a particular system or design is more prone to failuresthan others. Instead,these examples must be carefully analysed to prevent their occurance inother plants.
The awareness of the conditions which produce failures, helps the plant personnel to reduce thepotential for failures. This also helps in purchasing the most suitable equipment for a givenoperation and ensuring proper design & fabrication of the equipment.
70 27.7
70
106
127
124
1. 2
CO2 GAS
1. 0 0. 1
1ST REGENERATOR CO2 GAS
2ND REGENERATOR
PROCESSGAS OUT
VETROCOKE ABSORBER
HYDRAULIC
TURBINE
10128PROCESS GAS IN
CO2 REMOVAL SYSTEM FLOW SHEET
112
2
1
32
1
0. 2
2
1
5
4
3
106
LEGEND
TEMPERATURE (DEG. C)
PRESSURE (KG/CM2G)
Figure-1
GAS OUTLET B1
A2LEAN
SOLUTION INLET
BED - 2
BED - 1
B2SEMI- LEAN SOLUTION OUTLET
2nd REGENERATOR
SEMI-LEAN SOLUTION INLET
B3 LEAN SOLUTION OUTLET
A3
A1RICH
SOLUTIONINLET
BED VOLUME (M 3) TYPE
1
2
81.9 IMTP 50
81.9 IMTP 50
PACKING DETAILS
Figure-2
1800 1300 1030 900
CIRCUM WELD SEAM
APPROX. 2200 M M
A-2
HOLE
2nd REGENERATORLEAKAGE IN SHELL DUE TO CORROSION
15945
1510014200 M-3
430 M M
(Development Of Shell)
Figure-3
3000 2850 1800 1300 1030 900
A-2
M-3
CIRCUM . WELD SEAM
THICKNESS MEASUREMENT WAS CARRIED OUT IN THE HATCHED AREANO REDUCTION, EXCEPT FAILURE, WAS OBSERVED
HOLE
14200A-7
15945
151001485014000
2ND REGENERATORLEAKAGE IN SHELL DUE TO CORROSION
15530
15930
Figure-4
2ND REGENERATOR
BED NO. 1
16100M M
CHIMNEY
BED LIM ITER
LIQUI D REDISTRIBUTOR FOUNDLIFTED BY 50 M M ON ONE SIDE
M ULTI-BEAM SUPPORT PLATE
STEAM DISTRIBUTOR ( 3 SEGM ENTSFOUND LIFTED FROM ITS SUPPORTBEAM BY ABOUT 150 M M )
15100 M M
A2
M ULTI- BEAM SUPPORT PLATE
26750
IMTP 50PACKING
FAILURE OF LIQUID REDISTRIBUTORAND STEAM DISTRIBUTOR
BED NO. 2
Figure-5
CLEATS
SHROUD
SHELL
CHIMNEY
48 NOS. 20 Φ HOLES10 MM GAP
2ND REGENERATOR
SOLUTION INLETNOZZLE
IMPINGEMENT PLATE
Figure-6
2ND REGENERATOR(Original Arrangement)
SOLUTIONINLET NOZZLE( A 2 )
IMPINGEMENT PLATE
900 φ φ CHIMNEY
10 M M GAPSHELL (25 M M THK )
LINER ( 8 M M THK )
48 NOS. 20 Φ HOLES
Figure-7
2ND REGENERATOR(Modified Arrangement)
SOLUTIONINLET NOZZLE( A 2 )
900 φ φ CHIMNEY
496 Φ X 10 THK
SHELL (25 M M THK )
Figure-8
2480 MM.
3750 MM.
BED NO. 1
BED NO. 2
BED NO. 5
BED NO. 3
BED NO. 4
M1
M2
M3
M4
M5(A 4)
(A 2 & A 3)
(A1)
LIQUID REDISTRIBUTOR PLATES BENT UPWARDS
MULTI BEAM SUPPORT GOT DISPLACED FROM T.S.R.
L.R.D. WAS DAMAGED & LIFTED ABOVE M - 4
LEAN SOLUTION INLET
MULTI-BEAM SUPPORT
SEMI -LEANSOLUTIONINLET
PROCESS GASINLET
VETROCOKE ABSORBER
BED VOLUME (M3) TYPE1234
5
104. 9 IMTP 50104. 9 IMTP 4048. 3 IMTP 40
48. 3 MELLAPACK 250 Y
11. 0 IMTP 70
PACKING DETAILS
(B2) RICH SOLUTION OUTLET
Figure-9
PACKING BED NO. 2 MULTI-BEAM SUPPORTOF BED NO. 2 LYINGLOOSE IN THE BED.
DISTORTED / DISPLACEDLRD OF BED NO. 1
PACKING MATERIALOF BED NO. 1
DOUBLE C - BEAMLYING LOOSE
T.S.R. OF LRD
PACKING BED NO. 1
MANHOLE ( M 4 )
VETROCOKE ABSORBER
T.S.R. OF MULTI-BEAMSUPPORT
Figure-10
RICH GV
SOLUTION
762762
2618 2618
USV126
HIC 18
HIC 18
ER 14” x 8”
1070
70
1070
1100
ER 14” x 8”
ORIGINAL MODIFIED
8” HYDRAULIC TURBINEINLET NOZZLE
RICH GV
SOLUTION
8” HYDRAULIC TURBINEINLET NOZZLE
USV126
HYDRAULIC TURBINE INLET PIPING
Figure-11
GAS OUTLET B 1
A1-2 RICH SOLUTION INLET
4900 M M
BED - 3
BED - 2
BED - 1
B 2-3
B 4
SOLUTION OUTLET
SOLUTION OUTLET
4490
0 M
M
GV REGENERATOR
LEAKAGE FROM C - SEAMWELD JOINT
(Old Plant)
BED VOLUME TYPE (M 3)
1
2
172.5 SLOTTED RINGS
PACKING DETAILS
172.5 SLOTTED RINGS
172.5 SLOTTED RINGS3
Figure-12
NECKLACENOZZLE
M2NECKLACENOZZLE
0 DEG 180 DEGNORTH SOUTH SHELL
SHROUD
CIR.SEAMWELD
TRAY SUPPORT RING
SHROUDLOWEREDGE
DEVELOPMENT OF SHELL AND SHROUDSHOWING AREAS OF CORROSION
GV REGENERATOR
AREAS OF CORROSION ON SHELL
Figure-15
SHROUD
LIQUID DISTRIBUTOR
SUPPORTINGSTRIPS
BED LIMITER GRID
PACKING BED NO 3
BED SUPPORT
TRAY SUPPORT RING
8 NOS. SUPPORT CLEATS
CIR. SEAM OF SHELL
8 MM. THICK SHROUD
SHELL (16 MM THK)
10 MM GAP
10 NOS. SUPPORT CLEATS
GV REGENERATORSECTIONAL VIEW
2 NOS.INLETNOZZLES180 DEGAPART
Figure-14
0 DEGNORTH SOUTH
NECKLAC ENOZZLE
NECKLACENOZZLE
M2180 DEG
GV REGENERATORDEVELOPMENT OF LINER
LINER GAPEXISTS
LINER GAPEXISTS
LINER GAPEXISTS
NO LINER GAP
NO LINER GAP
Figure-13
PH-1:2ND REGENERATORDamaged Shell Near Solution Inlet
PH-2:2ND REGENERATORDisturbed Steam Distributor
PH-3:2ND REGENERATORSOLUTION INLET (Original Arrangement)
PH-4:VETROCOKE ABSORBERDisturbed Bed
PH-5:VETROCOKE ABSORBERDisturbed 1st Bed Liquid Redistributor
