Implementation of Best Practices for Improvements in Reformer Performance and Reliability

Ya,a imernationai operates manu/acluring/acilities globally which include twelve operating ammonia plants. Ya,a has developed a global best practice document which outlines the important

parameters to be used in managing the reform ers within these plants for efficient, safe, and reliable operation. Quest Integrity has assisted Yara in the implementation of elements o/Steam Reformer Best Practice to have Q l..'onsistent approach to the strategic management o/their sleam reformers

worldwide.

This paper discusses the best practice elements of the Yara Reformer Catalyst Tube Lifecycle Management and the management process used to implement these objectives. Included in the paper are examples offacility training performed for plant operators and reliability groups, implementation of reformer tube temperature management, and performance and reliability of monitoring performed

for steam reformers. The paper will conclude with the short and long-term benefits to Yara as realized through tlris implementation.

Giuseppe Franceschini Process Owner Inspection, Yara International

Giuseppe.Franceschini@yara.com

James R. Widrig Manager, Advanced Engineering, Quest Integrity, LLC

J .Widrig@Questlntegrity.com

Introduction

The implementation of a best practice for the life cycle management of reformer tubes was an enterprise-wide goal for Yara International. Yara management

recognized that they operated a large number of steam-methane reformers (refonners) globally and the management of these assets was not uni-

2015 115

fonn and could be improved. The number and frequency of tube failures occurring at some of the sites was indicative of the improvement op­portunity. More efficient, safe and reliable opera­tion of these assets was viewed as criti cal to the company's success and reason for the focus on a specific best practice. Quest Integrity was recog­nized by Yara for their reliability expertise in the ammonia and broader syngas industry, specific service and technology for reformers, and as a

AMMONIA TECHNICAL MANUAL

provider of world class products and services. Together, Yara and Quest Integrity developed a project scope and a plan to provide training for operators and reliability groups, implementation of tube temperature management, and reformer performance and reliability surveys of this global set of assets. These best practice program ele­ments of Reformer Care were implemented for all of the Yara International reformer assets dur­ing the time span ofmid-20l3 to early 20 15.

Overview of Yara Reformers

Yara has 12 operating ammonia plants located worldwide. These ammonia plants and reformers vary in process technology, reformer design, ca­pacity, and age as well as production efficiency and reliabi lity. The reformers are a combination of Top-Fired, Side-Fired and Terrace Wall de­signs (Table I). The oldest reformer in the sys­tem is the Yara Le Havre, France, reformer commissioned in 1967 and the newest reformer is the Yara Tertre, Belgium, reformer commis­sioned/rebuilt in 20 I 0 following a firebox explo­sion. There are a total of 3, 180 tubes in these 12 reformers. The oldest tubes were installed in 1977 in Porsgrunn, Norway, and Ferrara, Italy. The average age of the installed reformer tubes is around 20 years.

Yea. '"~ '"~ TuIHMa· HOof R. Io ...... '''' ~~n Design

buill P {MP'I ter1a l TulH.

Bell. Pial .... '- m, ." 4.16 "' ". 036001 ,,- Modified

F. rrara . Side· 1975 '" 3.73 HK40 '" B201 ,,-L"Hn ·r •• Side·

,~. '" 3.80 "' ,~

FlIOI ,,- Modified

Pilbara, '- - ~, 4.01 "' ,~

101-MP FIIlId Modlfifll

P ..... gNnn , '- ,,~ '" 3.30 "' '" F201 ,,- Modified

Slul. kll. Side· m' ". ,.g "' '" H301 ,,- Modified

Slul. kll. Side· 1983 ". 3.62 "' ". H401 " .... Modified

Slul. kll. Side· 1987 ". 3.62 "' ,~

"~, ,,- Modified

T. r1 .. , '- - ." ,.~ "' '" BIOI " .... Modified

Tr1nldad, Terrace

"" '" 3.79 "' '" H2030 W.II Modified

Tr1nldad, Terrace 1986 ~, 3.76 "' '" "'" W. II Modified

Trinidad, Terrace

"" '" '" "' ". H901D Wall Modified

Table I. OvervIew ofYara reform ers

AMMONIA TECHNICAL MANUAL 116

Basic Elements of Yara Catalyst Tubes Management Best Practice

Reformer catalyst tube reliability involves the whole Production Facility Organization (Inspec­tion, Production, and Maintenance) in order to systematically address all the phases of the tube life-cycle. Yara' s approach to the life cycle man­agement of reformer tubes, as documented in the best practice document Yara BP63 (BP63), in­volves training of personnel at both an operating and management level to ensure that they have an understanding of materials, common damage mechanisms, and inspection and monitoring techniques. This knowledge is used to evaluate manufacturing or fabrication deficiencies, deteri­oration or damage in service and the life cycle ef­fects of operation deviations. The goal is to make optimum use of the refonuer tubes (plus the pig­tai ls and headers) over the expected li fe and avoid untimely and costly premature failures.

Specific steps are defined and accomplished to manage reformer tubes over each operating cycle for the reformer. The operating cycle is defined as the period of time between two consecutive turnarounds, typically 4 or 5 years (Figure I). These asset management steps include an initial survey of the reformer conditions during opera­tion soon after start-up, continuing visual inspec­tion and tube temperature surveys on a regular basis, life assessment of reformer tubes and components prior to a scheduled turnaround, in­spection and assessment during a turnarounds, and careful observation and execution of start-up and commissioning (Table 2). The cycle of the activities is then repeated.

1.Operlltion: Start-up Acfivilies: " 2

5. T/A e.>tecution 2. Operation: lew weeks after

Acfivilies: B, 9, 10, 11, 12, 13, 14 start-up

Activities: 14

... Operation: TlA preparation J. Operation: NNormal" (typica lly 1 yearbelore TIA) Acfiviries: 6, 7 Acfiviries: 5

Figure I. Catalyst tube operating cycle

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Pha5e Activity Respon5ible

1.0peratioo: 1. Regular and frequent vlSlJallnspeclions of the tube to avoid over-flring during start-up

1. 2 First Line Maintenance Start-up

2. If the local firing is reduced (to bealty decrease the tube temperature) it is advisable not (operational personnel. Production) increasing the general level of fi ring in order to avoid the "wind-6own" effect

3. On-line reformer survey few weeks after TIA

a. Physical condition of the bume.-s b. Bowing evidence and colour variation between the rerom-tubes c. RefractO!)' condition d. Reformer operaUng parameters as compared to the design basis

2. Operation: e. Maximum allowable temperature (MAT) calculation 3, 4. First Line Maintenance few weeks after f. Tube metal temperature meaSlJrements Vs MAT (operational personnel. Production)" start-up g. Temperature spread between reformer tubes Extemal Specialized Contractor

h. Carbon formation margin , Monrtoring catalyst performance· activity and pressure drop are within expectations for a catalyst of a given age

j . Combusbon survey

4. Fumace balancing

5. On-line inspection and monitoring:

a. Visua l inspecUon (every sh ift) ·

L SignifICant colour variations or presence of hot bands Sa. First Line Maintenence ii Tubes away from each other, tube bowing (operational personnel , Production)

iii. SignifICant tube bent resuHing in a horizontal displacement 3. Operation· " Burner. evidence of backfiring. fou ling or deposit 5b. First Line Maintenance "Normal" " Refractory damage (operational personnel. Production)

b. Tube temperature measurement with an optical pyrometer (every month) 5c Inspection

c. Tube temperature analysis and operation recommendation development (every month)

L Temperature spread among the tubes Vs maximum recommended spread (50"C) ii Maximum skin metal temperature values Vs MAT

6. Preliminary tube residual me assessment. damage ctass projection. prel iminary lubes re-tirement planning (preliminary estimation of the number of tubes 10 be replaced at next TIA)

4. Operation: TIA preparation 7. Tube purchasing: Quality Control 6.7. Inspection and Maintenance (typOcally 1 year before TIA) a. Accurate Manufacturer selection

b. Certificate and NOT report revKiw c_ Workshop visrt d.IO Lase~ baseline meaSlJrement

8_ TIA catalyst tube inspection· 8_ Maintenance. Inspection +

a.lf catalyst is replaced (10 access) 10 Laser Profile + EC Extemal SpecialiZed Contractor

b_11 catalyst is not replaced. (00 access): 00 Laser Profile + EC 9. Inspection ..

9. Reformer tubes cond ition assessment: coupling inspection and residua l life calculation, Extemal Specialized Contractor

damage class projection at the next operating period, applying retirement criteria 10_ Inspection +

10. Reporting reformer tubes condition assessment results: reformer tubes creep damage Extemal Specialized Contractor

5_ TIA execution class mapping

" Maintenanoe

" Tubes replacement according to assessment results at point 10 above 12: Inspection +

" Metallurgical analysis of retired tube samples to oonfirm the creep damage class Extemal Specialized Contractor

" Cil-l<Il~1 <;hil-rging: pressv~ QrQP meil-"I,"ement Qf Ci!-lil-I~t in e~ t\lbe with PQrtil-ble 13: First Line Maintenance (operational personnel. Production) + instrument Extemal Specialized Contractor

14 Burners: visuil-I inspection. maintenance il-nd testing beforE! sl<lrt-up to avoid Ioc<II over-14. Maintenance healing due to burners malfunctioning

Table 2. Catalyst tubes management actlvlfles

2015 117 AMMONIA TECHNICAL MANUAL

Reformer Survey and Cost-Benefit Analysis - Why Yara asked for assistance for its BP63 implementation

In 2013, two years after the development of BP63, Yara performed a survey on all of the re­former assets. From the survey, Yara recognized that the management of these assets was not uni­fonn and could be improved (Table 3). The cata­lyst tubes failure history data included in the sur­vey detennined that an average of 8 tube failures every 3 years were occurring (not inc luding tube fai lures due to incidents/trips), It was also clear that the a reas with the greatest room for im­provement were the temperature monitoring pro­gram and the residual life assessment of the cata­lyst tubes.

Table 3. Yara reformer survey result

AMMONIA TECHNICAL MANUAL 118

During the 201 3 survey, a Cost-Benefit analysis was performed to estimate the potential benefit of a full and unifonn implementation of BP63. This analysis was executed according to API 581 [2] ca lculating the tube probabi lity of failure due to creep in the following 2 conditions:

• Full implementation of Yara BP63: "highly effective" inspection, monitoring and assessment program

• 2013 Basis or actual situation: "fairly ef­fective" inspection, monitoring and as­sessment program

The result of the analysis showed a significant potentia l benefit (Table 4).

Number of fa ilures il J yeiltS {cillcuJarion ilccot;(/ing 10 AP1581 : comlf'mH( illhe ilClUillslluarion, by retexmer survey)

CalOJlaled failulefreQl.Jl!ncy. lf2 [n'oflailures /(years • n' of tubes)]

Full implemenla~c:noIYara SP63 (high ty ellective inspection 5.84E.()4 ITKInnoringandassessmel1) •

CalOJlaled failureheQUency.1f1 (n' of failures /{years 'n' oltubes)]

2013, Actual situabon (fairly effective inspection, monitorl1g and 2.77E'()3 assessment)

Tolal number of tubes 3180

EsUmaled number of tubes with ITKIre than 25 years 01 service, n ,5< TIme period forthe Cost.senelit analysis, t [Years] 3

Tube failures in 3years, F2 ,,112' t ' n U

Full implemenlatic:noIYaraSP63

Tube failures in 3years, Fl - fll' t' n 7.'

2013,Actual situation

Tube failures lHferenee in 3 years , F2-FI 6.3

Cos/.Bener-/f analysis rex 12 Ammooia Unirs

Economic COnSeQIIJence 01' Failure, COF [I(E I Failure) 1000

Inspection, MoMoring,Assessment Cost Estimation for 12 Ammonia Units in3years, C2 [k€) 1434 Full implemenlatic:noI YaraBP63

Inspection, Monnoring,Assessment Cost Estimation for 12 Ammonia Units in3years , CI [k€) 360 2013,Actual situation

Cost 2"· (F2'COF + C2) [k€J ·3134

Full implementatiooolYaraBP63

Cost 1 ". (FI'COF" CI ) [k€I -il260

2013,Actual situation

Benefil in J years, (CosI2 COSlf) {I!€} 5126

Annual bener-If, (Cosr 2 - Cosr 1)1 J {Iff} 1708

Table 4. BP63 lmplementatron: Cost-Benefit

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Based upon the 2013 reformer survey and the es­timated potential benefit , Yara selected Quest In­tegrity to assist with the global implementation of BP63 through a specialized program of "Re­former Care" with the ultimate objective to re­duce the number and frequency of catalyst tube failures.

"Reformer Care"

Quest Integrity's "Reformer Care" includes data analysis, remaining life assessment, and engi­neering solutions. These services can be applied individually to address a specific issue or may be grouped to together to apply to a wide-range of integrity issues.

These services offer a unique solution to attain operational safety and reliability goals, enable proactive decision making, eliminate premature harvesting of reformer tubes, improve knowledge of turnaround requirements and reduces costs with proper planning, increase the understanding of reformer operation and limitations, and ad­dresses all reformer systems.

Yara selected a sub-set of these "Reformer Care" services or program elements to assist with their global implementation of BP63. This set provid­ed Yara with a specialized program of "Reformer Care" to assist with the strategic management of the twelve reformers located in eight production complexes around the globe. These key elements included:

•

•

•

•

•

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Training for operators on visual inspec­tion of reformers including tubes condi­tions, burner operation, and general con­dition Training for operators on tube tempera­ture measurement practices Implementation of reformer tube temper­ature correction procedures Recommendations for maximum allowa­ble tube metal temperatures Reformer Performance Monitoring to evaluate the current condition in service

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and identity and recommend performance and reliability strategies for improvement

These elements were chosen by Yara to close the gaps (against BP63) identified during the 2013 reformer survey, with particular focus on Maxi­mum Allowable Temperature (MAT) determina­tion, temperature monitoring and residual life as­sessment of the catalyst tubes.

"Reformer Care" Implementation Example

The implementation of the "Reformer Care" ser­vices was accomplished according to a schedule developed by Yara. The schedule was based up­on Yara's evaluation of several factors including the turnaround timing of the reformers, histOIY of operational and reliability issues, age of reformer tubes and planned replacements, and availability of site personnel.

The Yara Global Inspection Group had the over­all responsibility for coordinating on-site training activities and coordination of information about the reformers to Quest Integrity ahead of the on­site work. Information exchanged included oper­ating and design information, inspection results, and fai lure and replacement history. This infor­mation was used to develop specific training ma­terials for each of the reformers, provide back­ground information for evaluation of the reformers, and to customize the temperature cor­rection software application for each reformer. Site work and training was completed in 4-5 days per reformer.

Training

The on-site training for Yara personnel was ac­complished in both a classroom and field envi­ronment. Typical training attendance was 10-20 people and a mixture of operation, reliability, and inspection personnel. Quest Integrity senior en­gineers delivered the training, performed equip­ment field surveys, demonstrations and practical application of methods presented in the class­room. The training classroom and field applica-

AMMONIA TECHNICAL MANUAL

tion portions of the work were accomplished in 2-days and split between reformer performance monitoring and reformer tube temperature meas­urement and corrections.

Reformer Performance Monitoring

The topics covered in the training included back­ground information on reformer reliability man­agement, recognition and troubleshooting of re­former performance issues, reformer tube damage mechanisms and inspection, fitness-for­service and remaining life of reformer tubes, and how to recognize, troubleshoot and prevent

common reformer tube fai lures. This training in­cluded normal and abnormal tube conditions, bowed tubes, hot spots, bulges, cold tubes, and conditions due to catalyst damage and poisoning. Training specific to burners in operation was in­cluded to address burner characteristics and de­sign, correct operation of the burner, adjust­ments, maintenance, and troubleshooting. Practical training on tube and reformer visual in­spection during operator rounds was discussed in the classroom and then practiced in the field by participants using specifically prepared check list (Figure 2).

A MONITORING CHECKLIST Q/tJ:!:::;,;::..:::::::

REFORMER PERFORMANCE TO BE PERFORMED EVERY SHIFT

TI\RGET ...cTUAL

c::::J c::::::J DRAFT c::::::J c::::::J O2ICO/NOX

c::::J c:::::::J BRIOGEWALL TEMPERATURE

c::::J c:::::::J STACK TEMPERATURE c::::J c:::::::J FUEL PRESSURE c::::J c::::::J PILOT FUEL PRESSURE

c::::J c::::::J PREHEAT AIR TEMPERATURE

c::::J c:::::::J PROCESS INIOUT TEMPERATURE

c::::J c::::::J STEAM TO CARBON RATIO

BURNER INSPECTION TO BE PERFORMED EVERY SHIFT BURt£RNO.

UNSTABLE FLAME ~~

____ BAD FLAME PATIERN (1"-0_ .. ..,. .• _ .... )

____ PLUGGED TIPS

____ COOL BURNER TILE

____ PILOT TIP NOT GLOWING

PILOT AIR NOT WORKING

____ AIR REGISTER STUCK

OR NOT WORKING ____ AIR REGISTER OPEN

WHILE BURNER OFF ____ FUEL VALVE PINCHED

FIRE BOX INSPECTION TO BE PERFORMED EVERY SHIFT

RADIANT SECTION o TUBE BULGING. BOWING. HOTSPOTS

o TUBE COlOR o TUBE EXTERNAL SCALING o CATALYST ISSUES o REFRACTORY COLOR

o FLOOR REFRACTORY o WALL REFRACTORY

o TUNNEL REFRACTORY o ROOF REFRACTORY

EXTERNAl T"mparal"" Color Guida • ......... RUI 0 IN/OUT PIGTAILS

-_. 0 TUBE HANGER/SPRINGS

• :,\'::f 0 CONVECTION/DUCTS _ r,:=:", 0 Io/FD FANS .--.;oo.,)OOf

• ~..., TRAMP AIR '- -' 0 TUBE PENETRATIONS . ="_"'t' 0 SIGHT PORTS FUNCTIONAL (SEAL)

• ~"F 0 EXPLOSION DOORS, FLANGES, HOLES, LEAKING AIR IN BOX

Figure 2. Tube and reformer visual inspection check list

AMMONIA TECHNICAL MANUAL 120 2015

Reformer Tube Temperature Management

Accurate measurement of reformer tube-skin temperatures is a crucial input to a tube life pre­diction model (not directly based upon measured creep damage) and is also critical in optimizing productivity and ensuring optimum reformer op­eration. Radiation thermometry is a practicable and reliable method for determining tube-skin temperatures in reformers provided certain measurement corrective practices are used. Radi­ation thermometry in reformers is prone to a number of errors arising principally from the ef­fects of tube emissivity, reflected radiation and flue gas (Figure 3). Radiation thermometer read­ings and thermal images must have corrections applied in order to obtain the tme tube-skin tem­peratures. These corrections depend in a complex way on the geometry of the reformer, the tem­perature distribution of objects surrounding any individual tube, and the location of that tube in the reformer. The corrections also depend on the operating characteristics of the radiation ther­mometer or thermal imager used to make the measurements.

~ r " T " ... , ,

~ ~ .. ···::::'·········· 1 ~........... . ................ I

Figure 3. Radiation thermometry errors: effects o/tube emissivity, reflected radiation and flue

gas

The second day of classroom and field training was dedicated to the Infrared Radiation (IR) temperature measurement theory and techniques for reformer tubes. The classroom training dis­cussed the application of IR pyrometers and im­aging cameras for monitoring reformer tube tem­peratures along with the operator techniques

2015 121

required to obtain consistent temperature meas­urements. The classroom training was followed by practical application of the techniques to gain familiarity and a level of proficiency with the IR measurement instruments. Temperatures record­ed in the field were then corrected through demonstration and practical experience with Quest Integrity's CorrectIR™ software applica­tion.

Temperature Correction - CorrectlRTM

As an element of the Reformer Care implementa­tion, Yara implemented an lR temperature cor­rection program to establish the actual reformer tube metal temperatures. In order to determine the true tube temperatures, corrections must be made to the thermometer readings based on the geometry of the furnace, the emissivity of the tube material, atmospheric effects, and knowledge of the operating characteristics of the thennometer itself. The correction of refonner radiance temperature readings (measured without correction) to corrected temperatures is accom­plished using Quest Integrity's CorrectIR™ software (Figure 4) and method. The methodolo­gy and software is based upon the work of Dr. Peter Saunders. CorrectIR ™ accomplishes:

1. Corrects radiance measurements for cali­bration, size of source effect, flue gas emissions and other instrument and envi­ronmental errors

2. Calculates the uncertainty associated with individual factors

3. Calculates the effective background tem­perature taking into account rigorous ge­ometry for each tube

4. Calculates the Tube Corrected "true" tube temperature and the total uncertainty

A sample output of the temperature corrections performed using CorrectIR™ is shown in Figure 4. Tubes are referenced by the Tube Row, Tube Number, Height (location of the temperature measurement point from the reformer floor) , and Sight Door from which the temperature was measured. The Tube Reading is the uncorrected

AMMONIA TECHNICAL MANUAL

temperature measured by the IR instrument. Cor­rectIR ™ performs the calculation of the Tube Corrected "true" temperature and the total uncer­tainty for the "true" temperature.

I) Cotr«t1R • North Zo<w 1 Rl CoI.ot

fiIt.~~J:!<Ip

o ~ B .. . I'uwf __ T a.dvoord c.... 1 TIbo."....... I

0 1..,._(5_/Io>; .. T ......... )

0 """"," T..,.I....,. (1<81 ""'tnJouI...-;-,gj

O~ldrn.Ii«"' __

Implementation of the CorrectLR™ across the twelve (12) reformers in the Yara system is a key reliability element to sustaining reformer tube life and optimization of the assets.

" i Row T_ to ..... boo. Ho:/oIIt (m) ... '- T_R.~""f ea ..... .... c-.:t ... · r T .... o:o..«t.oI · f T ..... I T ..... """""' ......

'0 0.76 "" ,~, 1520.91 1471.14 15.97

" , 0.76 "" "., 154o.a6 14'>4.B9 14.n

" , 0.76 ""

,~, 1533.17 14B!i.72 15.5]

" 0.76 "" "" 154'.22 1~.~7 14.58

" 0.7f> "" 1591 1542.22 14%.82 15.03

" 0.76 "" ,~ 1554.16 1512.05 14.2

" " 0.76 "" 1591 1541.86 1496.116 15.26

" B 0.7f> "" ,~ 1S58.C] 1516.156 14.41

" " 0.7f> "" ,~o 1533.15 1484.74 If>.16 ., " 0.76 "" ,,~ 1545.21 14~.7S 15.41

'" " 0.76 "" ,~, 1552.23 1~.156 14.92

" , " 0.76 "" ,~, 1556.18 151U2 ".,.

" , " 0.76 "" ,~, 153S.Oti 1487.~ 16.07 ,., V 0.76 "" "" 1546.17 1500.98 15.45

'" U 0.76 "" 1574 1527.22 1476.73 "n ., " 0.76 "" ,~ 1540.22 1493.21 15.17

'" ~ 0.76 "" "" 1549.16 lS04.76 15.2 ., " 0.76 "" ,~ 1554.05 1511.44 14.7

'" " 0.76 "AA 1611 1560.'" 1518.12 14.49 . , .. 0.7f> "AA ,~ 1~7U.18 )jU.ll 14.01

" , " 0.7f> "AA If>10 155'.21 1511.18 14.71

T..,.o. .. • V .. ,.T .....

Figure 4. Results of Temperature Correction with Quest Integrity's CorreclfRTM software

Baseline Reformer Tube lR Survey and Tube Wall Temperature Limits

As an element of Reformer Care, Quest Integrity completed reformer tube temperatures surveys of each of the Yara refonners. These surveys were conducted using IR Imaging Cameras and in some cases IR pyrometers.

The surveys provided Yara with a baseline sur­vey of tube metal temperatures which were cor­rected using CorrcctIR™. The corrected tube wall temperatures (TWT) were lower than the measured radiance temperatures. In many in-

AMMONIA TECHNICAL MANUAL 122

stances when compared to operating temperature limits, these corrected "true" temperatures would allow for increase firing and ammonia produc­tion currently.

Quest Integrity also provided recommended TWT limits (Maximum Allowable Temperature, MAT) for each of the Yara reformers. Quest In­tegrity has developed a unique creep material model for HP Alloys that accounts for material aging and creep strain rate with respect to stress, temperature and time. This proprietary creep ma­teria l model is called LifeQuest™ Refonner. LifeQuest™ Refonner was used to defi.ne Relia­ble and Safe tube metal temperature operating

2015

limits for the Yara reformers. The main differ­ence between the original design life estimates provided by the tube manufacturer or the furnace designer and the Quest Integrity service life es­timate is that for the original design the tubes are assumed to have retained their original mean or lower bound as manufactured creep properties whereas the Quest Integrity model takes into ac­count that the creep properties will progressively degrade (Figure 5). This information was also provided as a creep rupture life curve for each re­former.

LMP Parameter

- HPNb

-HP micro

- Lower bound eJ(·service

... As cast

• Ex-service

Figure 5. As Cast and Aged Reformer Tube Material Properties

The creep rupture life curve for the reformer tubes are used to assess the life impact from changes in operating conditions. With a corrected tube metal temperature (plus uncertainty) value above the Safe limit, the creep rupture life could potentially be extremely short resulting in tube failure during the operating period.

Finally, during a reformer shutdown, the actual consumed creep life may be measured and calcu­lated by utilizing Quest Integrity's proprietary inspection tools, LOTIS® and MANTIS™ and the Level 3 LifeQuest™ Reformer assessment program.

Performance and Reliability Monitoring

Quest Integrity perfonned a Reformer survey to evaluate each of the Yara reformers. The primary objective of the work was to observe the reform-

2015 123

er in operation to assist with balancing the re­fonner firing and to deliver a reliability strategy to ensure the safe and reliable long term opera­tion of the reformers. The survey and reliability strategy included the following essential ele­ments to achieve optimum performance and reli­ability of the reformers.

1. Safety and Environmental 2. Operating Performance 3. Reliability Issues 4. Reformer Tube Condition 5. Reformer Mechanical Condition 6. Burner Mechanical Condition 7. Recommended Corrective Actions for the

Reformers

The issues found during the survey (examples are shown in the figures from 6 to 12) as well as oth­er industry best practices are were addressed by a set of corrective actions. Principled execution towards accomplishing these strategic actions will lead to a higher level of performance and re­liability with respect to the reformer.

Figure 6. fara Sluiskil H50J reformer: external scale on upper tubes

AMMONIA TECHNICAL MANUAL

Figure 7. Yara Sluiskil H501 reformer: tube ap­pearance as "Hot" due to external scale

Figure 8. fara Tertre BIOI reformer: flame pat­tern with baking soda test

AMMONIA TECHNICAL MANUAL 124

Figure 9. Yara Ferrara B201 reformer: bowed tubes; uneven tube colour; flame impingement on

tubes; tramp air entering/rom burners out-of service with air registers open

Figure Yara Ferrara out 0/ service with both primary and secondary

air register open causing tramp air

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flashback

Figure J 2. Yara Ferrara B201 reformer: thermal image of external hot spot at edge of sight door

Conclusions

Quest Integrity Group and Yara International worked together to deliver a set of "Reformer Care" services to Yara's Production Facilities. The overall objective was to reduce the number and frequency of catalyst tube failures.

2015 125

Reformer catalyst tube reliability involves the whole Production Facility Organization (Inspec­tion, Production, and Maintenance) to systemati­ca lly address all the phases of the tube life-cycle. Each phase of the tube li fe-cycle includes several specialist activities which are described in detail in Yara Best Practice document BP63. Together, and only if properly executed, a ll these activities reduce the probability of failure of catalyst tubes with a positive impact on plant reliability.

Although is too early to evaluate the real benefit (reduction of tube fai lure frequency) of BP63 implementation through the "Reformer Care" program, one significant result has already been achieved: operation, reliability~ inspection and management personnel have now a clear under­standing of the service related tube damage mechanisms, of the effects of excursions from design conditions, and, finally, of the monitoring and inspection techniques that have to be applied in order to avoid premature tube failures.

Proper implementation with a structured ap­proach, as described in Yara BP63, requires spe­cialised technical support and personnel training. For this reason Yara selected Quest Integrity to develop together a program of "'Reformer Care" to assist with the strategic management of the twelve Yara reformers.

The full set of Quest Integrity Group "Reformer Care" services can be applied individually to ad­dress a specific issue or may be grouped to to­gether to apply to a wide-range of integrity is­sues. Yara selected a sub-set of these "Reformer Care" services or program elements to specifical­ly assist with their global implementation of Yara BP63.

References

[1 ] Yara Best Practice BP63, Life-cycle management of reformer catalyst tubes (Yarn Internal Document)

[2] API Publication 581 First Edition, May 2000

AMMONIA TECHNICAL MANUAL

AMMONIA TECHNICAL MANUAL 126 2015