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Corrosion in Refinery UnitsGVHD: Ph.D Huynh QuyenSVTH: Pham Tin (7140054)Phan Tan Thanh (7140036)LOGO

INTRODUCTION1Cc thit b tn cha in hnh2Kim tra k thut trc vn hnh6Cc phng php thi cng4Cc thit b ph tr3Cc nh hng ln bn b cha5

Corrosion in Refinery Units1. INTRODUCTIONRefineryTanksCrudeOilProductStorageTanksPurpose of this presentation to show the causes of corrosion that can occur in the various refinery units, and methods corrosion prevention.

Corrosion in Refinery Units2. Phn loi:

Corrosion in Refinery Units1. INTRODUCTIONPetroleum refining is the separation of petroleum into fractions and the subsequent treating of these fractions to yield marketable products through the use of a series of unit processes in which each unit process carries out a separate function.The issue with corrosion in the refinery is that there is not one singlesource of corrosion, but many:

Corrosion in Refinery Units

7Corrosion in Refinery UnitsHydrocarbon phase Not normally corrosive at temperatures experienced in production systems Corrosivity depends on extent and distribution of the aqueous and hydrocarbon phases.Aqueous phase Responsible for corrosionCorrosion exacerbated by acid gases & organic acidsCO2, H2S and O2 are the most aggressive species Chlorides increase corrosionGenerally,no water, no corrosion

Internal corrosion

8Internal (process-side) damage mechanismsH2SCO2Solids & velocity effectsChlorides pitting, stress corrosion crackingOxygen (crevice / under deposit / differential aeration)Galvanic corrosionPreferential weld corrosion (PWC)ChemicalsInternal (process-side) damage mechanisms

9Internal (process-side) damage mechanismsTYPICAL REACTIONS



Corrosion in Refinery Units2. DESALTINGAs a first step in the refining process, to reduce corrosion, plugging, and fouling of equipment and to prevent poisoning the catalysts in processing units, contaminants must be removed by desalting (dehydration).Inorganic salts That cause fouling or hydrolyze and form corrosive acids.Demulsifiers to break the oil/water emulsion. The efficiency of the desalting operation is often directly related to the occurrence of corrosion in the distillation unit(s) as well as in other parts of the refinery.

Corrosion in Refinery Units2. DESALTING

14Decreases the amount of bottom sediment and water in the crude oil and the amount of suspended metal compounds going to downstream units.

Desalting chemicals Demulsifiers, caustic soda + Neutralize acidic components+ Excess of caustic formation of soap-type products due to the presence of fatty acids: the soap-like products stabilize the oil-water mixture and obstruct the separation process.


15Heavy Crude Oil (15 - 250 API)

High solids levels, unstable asphaltene constituents, nonextractable chlorides, naphthenic acids, sulfur, and metalsNon-water extractable chlorides that are not removed during desalting operations are typically defined as organic or inorganic chlorides that are not dissolved in emulsified water. High potential for system corrosion


16Ethanolamine (monoethanolamine), one of the most commonly used amines, readily forms an aminechloride salt in the atmospheric tower. These salts deposit in the upper sections and, often, under-deposit corrosion is the major cause of failures in process systems because in the tower the under-salt corrosion rates can be 10-100 times faster than a general acidic attack. Mitigation strategies include: + (1) controlling chloride to minimize the chloride occurrence in the tower overhead.+ (2) acidifying the desalter brine to increase removal of amines into the water phase.


17Separation of crude oil into various fractions: Gases, light distillates, middle distillates, gas oils, and residuum.The concentration of certain constituents by the distillation process can cause corrosion and sediment fouling, and can affect flow rates.

However, corrosion agents can still appear in various streams during post-desalting.(Blanco and Hopkinson, 1983; Piehl, 1988)Corrosion in Refinery Units3. DISTILLATION

18In the distillation unit, acid gases are formed, of which hydrogen sulfide is notorious.Steam, which is injected into the crude tower to improve the fractionation, condenses in the upper part of the unit. The hydrogen sulfide dissolves in the condensate and forms a weak acid that is known to cause stress corrosion cracking in the top section of the tower and in the overhead condenser. This may lead to frequent replacement of the tubing of the condenser andin severe casesto the replacement of the entire crude tower top.Corrosion in Refinery Units3. DISTILLATION

19Corrosion in Refinery Units3. DISTILLATION

20Corrosion in Refinery Units3. DISTILLATION

Typically, corrosion inhibitors and neutralizers, such as caustic soda or ammonia, are injected with the aim of increasing the pH of the sour water.

21Corrosion in Refinery Units3. DISTILLATIONHydrogen Chloride/Hydrogen Sulfide CorrosionCorrosion in the atmospheric crude distillation unit from the presence of hydrogen chloride. (HCl)

Decomposition of sodium chloride (NaCl), calcium chloride (CaCl2), and magnesium chloride (MgCl2) at temperatures exceeding1200C (2500F), as well as from the decomposition of any organic chlorides.

22Corrosion in Refinery Units3. DISTILLATIONHydrogen Chloride/Hydrogen Sulfide Corrosion

23Corrosion in Refinery Units3. DISTILLATIONHydrogen Chloride/Hydrogen Sulfide CorrosionHCl(aq) + NH3(aq) NH4Cl(aq)HCl(aq) + RNH2(aq) RNH2HCl(aq)

In situations in which the water returns to the vapor state, solid deposits of ammonium chloride form. This creates the potential for under-deposit corrosion.

TNG QUANPHN LOI THEO P SUT

TNG QUANPHN LOI THEO VT LIU

BN CHA LNPCC THIT B TN CHA IN HNH

CC THIT B TN CHA IN HNH

TU VN CHUYN LNP

CC THIT B TN CHA IN HNHBN CHA LPG


CC THIT B TN CHA IN HNHBN CHA XNG


CC THIT B TN CHA IN HNHBN CHA BITUM

CC THIT B TN CHA IN HNHXE CH BITUM

CC THIT B TN CHA IN HNHCC BIN PHP GIM HAO HT TRONG TN CHAMi che

Sn trng

Van th

CC THIT B PH TR1. Bm:

Bm ly tmBm cnh trt

Bm pistonBm trc vtCC THIT B PH TR

2. Van:Van chn:

Van cng hay van ca (gate valve)CC THIT B PH TR

Van cu (globe valve)

Van iu chnh:

Van mng (diaphragm valve)CC THIT B PH TR

Van Bi:

Van Kim:

CC THIT B PH TR

Van bm:

Van iu khin bng kh nn:

CC THIT B PH TR

Van an ton, x p:

3. Thit b o:

Nhit k lng kim

Nhit k p sut l xo

CC THIT B PH TR

4. Cc thit b ph tr khc:- Cu thang- L nh sng- Ca ngi- L ly mu- ng thng hi-ng tip nhn cp pht- H thng tip a- Thit b o mc cht lng trong bn b-Thit b cu ha- H thng ti mt- H thng thot ncCC THIT B PH TR

PHNG PHP THI CNG BN CHAPhng php hn hon thin v ghp dn (Progressive Assemply and Welding)2. Phng php hn gin on v lp ghp tng th (Complete Assembly followed by Welding of Horizontal Seams)3. Phng php nng kch bn (Jacking-up Method)4. Phng php ni ( Floation method)

Cc nh hng ln bn b cha du kh1. Tc ng bn ngoi

a, Tc ng ca gi Gi c th tc ng n bn, nh hng n n nh ca bn, lm cho bn b un cong hay tc ng n hnh dng ca bn

b, Tc ng ca t y l tc ng hy hu, khng c phng n chng li. Tuy nhin khi xt n phng n ny, ta ch d on v ch m bo cho cc sn phm khng b tht thot ra ngoi, nhng vic ny cng khng th chc chn c

a, p sut lm vic cc i- L p sut ln nht cho php ti nh ca bn cha v tr hot ng bnh thng ti nhit xc nh i vi p sut .- Nguyn tc: p sut lm vic cho php ln nht ca mt phn ca bn cha l p sut trong hoc ngoi ln nht bao gm c p sut thy tnh nu trn cng nhng nh hng ca tt c cc ti trng kt hp c th xut hin cho vit thit k ng thi vi nhit lm vic k c b dy kim loi thm vo bo m n mn

b, Ti trng gi

c, Dung tch cha ln nht cho bn

2. Cc nh hng thy lc n bn chaCc nh hng ln bn b cha du kh

3. nh hng ca n mn bn b cha

- Cc b cha c bo v chng n mn bng:+ sn ph+ phng php bo v catt

K hiu trn hnh v:Active Metal (Anode) = Kim loi hot tnh (ant)Protected Metal (Cathode) = Kim loi c bo v (catt)

Bo v bng dng in cng bc (dng in ngoi)Cc nh hng ln bn b cha du kh

a, Bo v catot cho b ngm Bo v catt lmtty chnbo vmtbchangm(BCN) khi b n mn.Chailoih thngbo vcatt:anodehy sinhdng in cng bc (dng in ngoi)

Bo v bng ant hy sinhElectrical Isolation (Bushings) = Cch in (Tm lt)Dieletric protection coating = lp ph bo v in miCathodic Protection (Anode) = Bo v catt (ant)

Cc nh hng ln bn b cha du kh

Bo v catt bng dng in cng bc (dng in ngoi)Cc nh hng ln bn b cha du kh

b, Bo v catot cho b cha nm trn mt t

n mn bn ngoi y b chan mn pin in do vt liu bn ngoi trong ct mCc nh hng ln bn b cha du kh

n mn do thot nc kmThp mi v thp c kt hp vi nhauCc nh hng ln bn b cha du kh

Bo v catt kiu pin in (Galvanic)

Bo v catt bng dng in ngoi


4. S bay hi trong bn b

a, Ngn chn s bay hib, Gim thiu s bay hic, Thu hi li thnh phn nh

5. Bo qun bn b chaSn bn, bnh k bo dng bn, b


1. Kim tra knKim tra kn y b Phng php thuc th- Ngi ta dng thit b gi l ra th chn khng, l mt hnh hp mt mt trng, mt i din c knh v cc ng ni n my ht chn khng v n p k.- Ngi ta t thit b ln mt on ng hn cn th, trt matit xung quanh, dng bm chn khng ht khng kh trong hp to chn khng trong hp. Nu ng hn khng kn th x phng bi trn ng hn s c bong bng, ta phi nh du li, tuy vy cng c th nc khi thng s c tm kh ni ln.Phng php chn khng -Ngi ta p t xung quanh thnh b ngn khng cho kh thot ra, kh nn vo y b, chiu cao t p khong 100mm. Ngi ta a 3 4 vi bm kh amoniac vo y b vi p sut d 8 9 mm ct nc di y b. Trn ng hn c nh sch ngi ta qut dung dch phenolphtalein. Nu thy ch no chuyn mu ta ghi li. Cn nu dng dung dch axit HNO3 2,5% th qut dung dch ln vi mn hoc giy bn ph ln ng hn, ch no thng cht ch th ng mu en

Kim tra k thut trc khi a vo vn hnh

b.Kim tra kn thnh b - Cc mi hn thnh b kim tra kn bng cch qut hoc phun du ha pha trong, pha bn ngoi qut nc vi hoc qut phn. Qut 2 ln du ha cch nhau 1 pht sau theo di nu khng c vt du loang coi nh l c

c.Kim tra kn mi b - Th bng phng php nn kh trong b v bi nc x phng ln ng hn mi b, tn gip thnh b. Nu ng hn khng kn bt x phng s ni ln( p sut th bng 15% p sut lm vic b). - C th th kn mi b bng cch phun du ha vo phn tip gip mi ngoi b v pha ngoi b, trn ng hn ta bi phn hoc qut nc vi ri quan st theo di xem lp vi c qut c b thm t hay khng.Kim tra k thut trc khi a vo vn hnh

2.Th bn ca ba) Th cng ca b Th cng ca b bng cch bm y nc vo b cha trong b t 3 - 7 ngy nu ln ca b khng ng k, b khng b bin dng th c th kt thc vic th, coi nh l tt. Cn nu b c s bin dng ln th phi tm cch khc phc.

b) Th bn mi b Th bn ca b l th 2 ch p sut, p sut dng v p sut chn khng bng cch : bm nc hoc nn kh vo trong b, hoc rt nc khi phi c van khng ch p sut trong b v p k theo di. p sut khng ch nh phn th kn nhng thi gian gia 2 p sut l 2 3 gi.Kim tra k thut trc khi a vo vn hnh

3. Th ln bPhn loi cc dng ln b v nguyn nhn

Ln u Hin tng ln u ch yu l do nn t khng chu lc, m vic gia c mng b khng m bo nn thng xy ra ln hoc do thay i cc yu t thy vn nh mc nc ngm t nhin ln cao mt thi gian di cng lm cho b b ln.

Ln lch Hin tng ln lch l do x l nn mng khng u ch m k, ch m khng k hoc mng b thi cng mt phn t nn mt phn trn lng t mn phi m nn. Trong qu trnh cha du s gy nn ln lch. Cng c th mng b xy trn nn t p nhng chu lc khc nhau cng gy ra ln lch b. Kim tra k thut trc khi a vo vn hnh

b) Kim tra ln theo chu vi b

Vic kim tra ln y b c th thc hin bng cc phng php sau :-Phng php o thy chun xung quanh chu vi ca b.-o nghing lch ca b bng phng php dy di. B o thy chun c ng cao su vng chu vi bNhng quy nh v cch o :-Ty theo chu vi b m chia cc im o xung quanh b nhiu hay t s im o nhng khng c nh hn 8 im v khong cch gia cc im khng nh hn 6m.-Vi b 2000 3000 m3 sau 4 nm s dng chnh lch hai im o cnh nhau khng qu 40mm, hai im i din nm trn ng knh khng qu 180mm. Nu b s dng qu 4 nm chnh lch cho php ln lt l 60mm v 150mm.-Nhng b b 400 500 m3 chnh lch cao bng 50% gi tr ca b ln.Kim tra k thut trc khi a vo vn hnh

c) Kim tra ln trong nn b C th nc vo y b cho ph khp c ni cao nht sau o chiu cao nc nhng ch lm. Hoc c th o kh y b bng phng php thy chun s im.-S o phi ln hn 8 im trn b mt.-Chiu cao vt li lm trn y b khng c li qu 150mm, din tch vt lm khng qu 2m2d) X l ln b Vic x l ln b ty theo mc ln, nguyn nhn ln ta c cch x l khc nhau : Nu do nn t c chu lc khng tt m ln b th c th phi kch b o mng b ln, ng cc cc tre, cc g, cc b tng hoc cc cc ct xung li mng b l cng vic kh phc tp v tn nhiu cng sc. Nu do ln cc b th ta c th ch cn kch phn ln qu nhiu tin hnh ng cc, lm li nn mng, gia c cc ct... phc hi li phn mng b l c.


4. Bo qun b cha Sn b

Ty thuc vo v tr t b cha du m ngi ta sn cc loi sn khc nhau, c th sn c trong b v ngoi b chng n mn thnh b. B t ngoi tri ngoi vic sn chng n mn cn phi sn thm lp sn chng trng phn x nh sng mt tri nhm gim thiu tn tht hao ht v cht lng v s lng xng du cha trong b.

Vic sn pha trong b lp sn chng n mn thng phi tin hnh sn b khi mi bt u a b vo s dng. i vi bn ngoi b thng sn mt lp chng g, kh lp sn ny sau mi sn cc lp sn v nh khc.Kim tra k thut trc khi a vo vn hnh

b) nh k bo dng b * Cc kho tn cha xng du cn c k hoch xc ra b cha xng du mt cch nh k c nin hn. Tuy nhin trong cc trng hp sau cn nht thit phi xc ra b cha xng du nhm m bo cht lng xng du tn cha khng b nh hng v mt cht lng.Khi a b mi vo s dng, do b mi thi cng nn c th b bn t bm vo, cc r st, cc mu que hn... do vy cn phi xc ra bnh tht sch trc khi a vo s dng.Khi thay i chng loi du cha trong b.Khi b b h hng phi xc ra b cha trc v sau khi sa cha


* Thi gian cn thit phi xc ra b cha xng du. Ty theo tng loi xng du cha trong b, tnh cht ca kho ta nh ra thi gian cn thit cn phi xc ra b cha :t nht 1 nm 2 ln i vi b cha nhin liu dng cho ng c phn lc , xng my bay, du m dng cho ngnh hng khng.t nht mi nm 1 ln i vi cc b cha nhin liu pha ph gia, cc b cha ph gia, cc loi xng t v du m dng cho t.t nht 2 nm 1 ln i vi cc b cha du nhn, du FO, du DO...

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