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Technical Note

Cold Box issues Issues, remedial actions and prediction for future performance

Prepared by: Brijesh Goel Process !n"" #uperintendent$, %ith &ield Inputs from Carey#%anson BGP 'perations #uperintendent$

(ate: )* th +pril ) -

Cold Box Issues:

Cold Box has ) main issues: Icin" and .ercury/ In this note, icin" related issue isdiscussed since it %as the cause of recent BGP shutdo%n0increasin" trend of do%ntimeas hi"hli"hted by our partner, Petronas email dt 12 th +pril 31 from Pa4 5ahi6an +hmadto .r/ 5#7 .ohan$/ .ercury issue is a separate issue for %hich separate short term andlon" term action plan has been prepared0in pro"ress/

Icin" Issue: Chronolo"y of e8ents and actions ta4en/15 th Jan 2010 In the molecular sieves regeneration system, it was detected that the sequencing valve

695- !-15" was #assing$ %his resulted in regeneration gas &rom the 'aste (eat)ecovery *nit +'()* to y#ass .ol /ieve towers causing end o& heatingtem#eratures to e lower than normal$

1 th Jan 2010 - )emoved 695- !-15" to re#air lea $ %o avoid a 34 acility shutdown, 7#erations 8e#thad to manually ad ust the : sor#tion timer &or the .ol /ieve tower &rom 1020 minutesto 1200 minutes$ It is sus#ected this is when the initial moisture rea through occurred$

25 th Jan 2010 It was noted that the #ressure di&&erential +d across the ;old 3o< #ass= was slowlyincreasing +&rom 20 #si to >0 #si which ty#ically indicates increasing icing?hydratede#osits in the a&&ected #ass$ It was decided to lower the : sor#tion %imer in .ol sievesystem &rom 1020 min to 960 min$

.oisture analy@er not wor ing &or three months already due to unavaila ility o& #ro ewhich has een on order$

" th e 2010 - /hutdown the A4B )ecovery *nit &or 5 hours to &low hot gas through ass = to thaw theice uild-u#$ %he thaw o was success&ul$ /till waiting &or moisture analy@er #ro e$

1Cth e 2010 - ;old 3o< ass = showed low d s until 34 7#erations introduced A4 sales gas into34 Ds molecular sieve system$ +Aote - A4 sales gas was routinely introduced to 34mol sieve system #rior to icing issue, &or enhanced liquid recovery &rom A4 sales gas $

8ue to &low o& an e

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down due to high 4(! o& /ales gas$ A4B )ecovery /ystem was warm ut did not hel# tothaw the ice$ .ethanol in ection was also tried ut did not hel#, #ro a ly due to normalo#erating #ressure o& 600 #si on ass = was not low enough to remove hydrates &romthe system$ %he online cleaning #lan was a andoned and it was decided to shut down34 to clean #ass= $ In addition, it was also agreed to install isolation valve around #ass= so that in &uture, methanol dum#ing and hot &uel gas could e introduced without total#lant shutdown$

.oisture analy@er #ro e was changed with a new one$

Engineering drawings were #re#ared, material #rocured and #rocedures written toim#lement the #ro#osed modi&ications$

29 th .ar 2010 - 34 acility was shutdown &or C0 hours to install isolation valve downstream o& ass= $ :ll #roduction was shutdown to decrease &lare header #ressure$ %heoretically, thehydrate melts at #ressure elow 50 #sig and 7#erations rought the o#erating #ressurearound the #ass =F to almost atmos#heric #ressure #rior to re-starting the #lant$ *#on#lant re-start, it was noted that the cold o< d was still high and required to e cleaned

again$

/ee attached FI8 +:s 3uilt &or modi&ications im#lemented during 34 shut down$

1> th :#ril 2010 'ith the isolation valves in #lace, online cleaning o& the #ass= was attem#ted$ 34#roduction was decreased y 5 ..sc&d to ee# sales gas 4(! within s#ec a&ter mi

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7#tical technology ased moisture analy@er design to re#lace the e