XQ LY CAN LANG DONG TRONG THIET Bl TRAO OOI NHIET CUA PHAN X U O N G CDU NHA MAY LOG DAU DUNG QUAT
BANG HOA PHAM
Tom tSt
ThS. LS Quang HiAig, ThS. Nguyin Thj Mai Li KS. Nguyen Khinh Toin, ThS. NguySn Thj Lan Anh Vien D6U khi Viet Nam
Email: [email protected]
Trong Nhd mdy Lgc ddu Dung Qudt, cac thiet bj trao ddi nhiet thudc cum gia nhi&t nguyin lieu trong phdn xudng' CDU thudngxuyen bi Idng can. Viic nghien cUu sie dung hi hoa pham dexijfl^ Idng can cho cdc thiet bj tren cd^nghk Idn ve mat kinh tedoi vdi nhd mdy. Bdi bdo ndy gidi thieu sd bg vihiin tUdng liing can, tdc hgi ve mat kinh tedo hlin tUdng Idng can gdy ra trong nha mdy lgc ddu va xUly ldng can Men tgi trong Nhd mdy Lgc ddu Dung Qudt. Tren cdsd k^t qud ddnh gid thdnh phdn can ldng dgng, nhom tdc gid nghiin cUu che tgo he hda phdm hda tan can phii hdp. K&
qud cho thdy cdc mdu can trong thiet bj trao doi nhiet cua phdn xUcfng CDU cd hdm lUdng can CCR tU40 - 60%, parafSn tU20 - 24%, ty le C/H tit 5-7. He hoa phdm thiet lap dUdc cd thdnh phdn ty le diesel/ddu thong/chdt hogt dgng be mat/
amin=37,2/55,6/1,8/5,4, ty live khoi lUdng hi dung mdi/cgn Id 8 Idn theo kho'i lddng. Hi hoa phdm sau khi boa tan can phu bdp de sif dung Idm ddu dot lb cho nhd mdy.
TUkhoa: Hien tugng ldng dong can thiet bi trao doi nhiet, ldm sgch thiet bi trao dSi nhiet bang hoa chdt. ^ -
1. Gidi thieu
Lang dgng tren be mat truyin nhiet la mot trong nhflng van de quan trong nhat trong t h i l t bi trao ddi nhiet. Hien tuong lang dgng trong t h i l t bi trao ddi xay ra hau h i t ddi vdi cie nganh cdng nghiep hda chat va dien bao gdm: nha m i y Ige dau, sin xuat giay, n h i m i y dien, nha m i y sin xuat sgi, nha may dam... Hien tugng ddng can tren b l mat truyin nhiet lam giam hieu qua truyin nhiet, tang syt ap va gay ra an mdn. Chi phi p h i t sinh do l i n g dgng can rat cao bdi cae ly do nhU tang ehi phi dau t f l v i can p h i i t i n g dien tfch b l mat thiet bj trao ddl nhiet, tang ehi phi b i o tri do khi lam saeh dng trao ddi nhiet ed t h l bj tray xude hoac cic su cd, g i i m sin lugng sin xuat vi p h i i dflng thiet bi, tang mat m i t nang Iflgng do su truyin nhiet g i i m , tang sUsut i p [1 - 3].
Theo d i n h gia cua mdt sd chuyen gia trong Unh vUc xfl ly lang dgng trong t h i l t bi trao ddi nhiet, l i m saeh lang dgng bSng hda chat chuyen dung se g i i m dflgc hon 70%
chi phi va thdi gian xfl ly nhanh hon so vdi phflong phip CO hoe. Hien nay, mdt sd nha m i y lpc dau tren the gidi nhu Shell, Petronas, ExxonMobil... da ap dung phuong phap lam sach t h i l t bi trao ddi nhiet bang hda chat nham xfl ly ddng d i u be mat t h i l t bj trao ddi nhiet va tang thdi gian gifla hai lan lam saeh lien tiep [4].
Hi§n tflong lang dong anh hudng d i n c i chi phi dau t f l va chi phi van hanh ciia thiet bj trao ddi nhiet. Cic chi phi phat sinh lien quan den hien tflgng lang dong
trong t h i l t bj trao doi nhiet the hien d 4 diem chinh sau [3, 5, 6]:
Chi phi dau t f l eao hon do viee bd sung be mat thiet bi (10 - 50%), chi phi eho khdng gian m d rdng them, tang chi phi l i p dat va van chuyln;
Mat mat nang Iflgng do g i i m hieu q u i truyen nhiet va tang sfl syt ap;
Giam sin lugng do viec dflng nha m i y de lam sach can lang dong;
Tang chi phi bao dUdng.
Theo udc tinh cita Pritehard [7], tdng ehi phi xir ly hien tflgng lang dgng d cac nfldc edng nghiep Idn chiem khoing 0,25% tdng s i n pham qudc ndi (GNP) cua qudc gia do.
Theo Bing 1, chi phi xfl ly hien tflgng lang dgng khi ldn va bat ky sfl g i i m chi phi nao trong sd nay eung mang lai Igi n h u i n va tinh eanh tranh eao hon. Tin suit l i m sach se phy thude vao sfl phflc tap cOa hien tfldng ling dpng, cd t h l la 1 tuan, 1 nam hoae l i u hdn.Tan suat lam sach li^n quan den sfl lap lai ciia viec thao dd va l i p r i p lai t h i l t bj nen se l i m g i i m tudi thg cita t h i l t bj trao ddi nhiet.Trong nha may lgc dau va hda dau, chl phi eho q u i trinh lam sach can lang dgng rat cao do lflu chat sfl dung l i dau thd v i cae loai nhien lieu, dan den hien tflOng l i n g dgng thfldng xuyen hdn, do dd qua trinh van hanh bj g i i n doan, g i i m san Iflgng va tang chi phi b i o tri b i o dfldng.
DAUKHi-sd 7/2016
L i n g dgng la qua trinh ddng hge va khdng dn djnh, trong dd cac thdng sd van h i n h v i thiet ke deu anh hudng d i n qua trinh niy. Cic thdng sd bao gdm: tde do '"'•'''Hlbt ddng lflu chat, tinh chat ddng, nhiet dd be
^ ^ \ mat, cau true hinh hgc be mat, vat lieu b l mat, do cflng b l mat, ndng do va tinh chat cic hat lo Iflng... Theo n h i l u khio sat, cae thdng sd quan trgng nhat bao gdm: tdc dp
""•Jpiti ddng chat Idng, vat lieu be mat, do n h i m b l mat, tinh chat ddng chat ldng, cac tap chat va chat ran lo lifng.
Trong Nha may Lgc dau Dung Quat, hien tflong lang dpng x i y ra chu y l u trong cac thiet bj trao ddi nhiet eiia eie cym phan xudng bao gdm: phan xUdng RFCC, phan xUdng CDU, phan xUdng xfl ly nude chua va phan xudng thu hdi amin. Cic t h i l t bi trao ddi nhiet trong phan xudng CDU thfldng xuyen bi lang can va anh hudng nhieu d i n boat ddng eiia nha may. Phflong p h i p xfl ly dflgc nha thau thi cdng i p dung de lam sach can trong cic thiet bi trao ddi nhiet cho nha may la diing vdi phun nUdc i p Iflc eao. NhUdc d i l m ciia phuang phap nay la lam b l mat kim loai bi am Udt, tao gi cap tinh ngay sau khi khd be mat, tdn thdi gian va chi phi d l thao lap t h i l t bi. Ngoai ra, trong qua trinh phun nfldc thudng vfla phun nudc vfla choc dng de lam dng thiet bi trao ddi nhiet bj m i l mdn, tray xfldc, lam g i i m nhanh tudi tho cita t h i l t bi, Viee sfl dyng he hda pham xfl ly se khdng lam dng t h i l t bi trao ddi nhiet bi m i l mdn, tray xfldc, ddng thdi giam thdi gian va chi phi xfl ly do khdng phai t h i o l i p t h i l t h\.
2. ThtTc nghiem
2.1. Phdn tich thdnh phdn can f-jJ^^-' Mau can phan tich dfldc lay trong yj-^^ dng thiet bj trao ddi nhiet E-1, E-2, E-3 va g ^ " * E-4 thudc phan xfldng CDU va cd ky hieu -fjai^' tflong flng la m i u 1 den mau 4.
It*** ., Theo t f l van ciia Nha may Lpc dau
*^* > Dung Q u i t vj tri lay mau tai nap pic ed the ' ^ V dai dien cho mau can cua t h i l t bj trao ddi V'^^'^' nhi&t. Trong q u i trinh van hanh, ein hinh
Bdng 1. Chi phi hdng nam xiily hien tUang ldng dong dmot sdqudc gia
Quoc gia My Anh Oitc Phap Nhat Ban Australia New Zealand
Chi phi l i n g j
xfl 1]^ hien tugng ong (trieu USD)
14.175 2.500 4 875 2.400 10.000 '463
64,5
Chi phi xfl \yi hien tflong l5ngdong/GNP(%)
0,25 0,25 0,25 0,25 0,25' 0,15 0,15
Nguon: Heat Exchanger fouling-Mitigolion and QeaningTettinologiei
Bdng 2. lAdtioddn vi cung cap dich vu Idm sach thiet bi two doi nhiet bong phuong ptiap hoa hoc tren Ihegidi
10 Petr
1_LL- Exx(
Nha m a y loc d a u Reliance Industries Limited Refinery, Jamnagar, An D o
Pemex Madero Refinery, Mexico Essar Oil Refinery. An D o Pemex Cadereyta Refinery, Mexico Petro Rabigh Refining Complex, KSA Pemex Salina Cruz Refinery, Mexico PEMEX Salamanca Refinery. Mexico Aramco Ras Tanura Re^nery, Saudi Arabia Shell Easter Petroleum
Petronas ExxonMobil
D o n vi cung cap djch v u . l a m sach
TuffChem Corporation
Nalco/Eurotech Naico Nguon Juffctiem, Noka, Eurotecti
Hinh I.Sado phdn bo thiet bi trao doi nhiet cum gio nhiet nguyen iieu ddu vd
lUKHl-SO 7/2016 5 5
thanh trong dfldng dng, dudi t i c dyng ciia ddng chiy, c i n sinh ra bj cudn trdi va ehii y l u bam tren nap pic cua t h i l t bi trao ddi nhiet. Nhiet dd v i n h i n h trong t h i l t bi trao ddi nhiet khdng dii Idn de xiy ra qua trinh cdc hda {> 400''C), do viy, ein bam tren dng trao ddi nhiet khdng xay ra q u i trinh coc hda, tinh ehat can trong dng tflong ddng tinh chat c i n l i n g dgng tren nap pic t h i l t bj trao ddi nhiet.
Nhdm t i c g i i da sfl dung eae phflong phap de phan tich thanh phan m i u can nhfl sau:
Phuang phap xac dinh ham lugng cic kim loai Na, Mg, Ca, Al, Fe, Ni, V: quang phd hap thu nguyen tfl theo TCVN 5384-1991;
Phuang p h i p xie dmh ham Iflong can CCR: ASTM D4503-08;
Phuong p h i p xie dinh h i m lugng asphaltene:
IPI 43-90;
Phuong p h i p xae dinh ham Iflgng paraffin: UOP
Phflong phap xic djnh ham Iflong tro: ASTM D482-07;
Phuong phap xac djnh ham IflOng N: ASTM D3228-01;
Phuang phap xac dinh ham Iflgng C va H: m i y phan tieh nguyen td EURO EA 3000 Single theo hfldng dan ciia hang sin xuat.
2.2. Khdo sdt khd ndng boa tan
Do hda tan dugc thue hien bang phuang p h i p mat khdi lugng. Cdng thfle tinh nhfl sau:
Trong dd:
m,,: Khdi IflOng mau ban dau, g;
m : Khdi lugng mau cdn lal sau khi hda tan, g.
Thdl gian k h i o sat: 2 gid;
Tdc dd khuay: 150 vdng/phiit;
Nhiet do k h i o sit: 2 5 " ^
Luong mau can sfldung trong mdi lan khio sat 5^
Lugng dung mdi sfl dung: 100ml.
Sau q u i trinh hda tan, can cdn lai dugc lgc, rfla va say d nhiet do thich hgp.
2.3. Lap quy hogch thUc nghiim
De tdi uu hda thanh phan he hda pham: muc tieu toi Uu hda la he hda pham cd k h i nang hda tan ldn nhat
Bai t o i n dugc md hinh hda theo thUe nghiem bac 2 t i m xoay, tien hanh tren co sd x i y dUng ma tran quy hoach hda thue nghiem bac 2 t i m xoay. Vdi 3 y l u td khao sit nen sd thuc nghiem gdc l i 8, sd thUe nghiem 6 diem sao l i 6 va t i l n h i n h 3 t h i nghiem d t i m quy hoach can thue hien it nhat la 17 thi nghiem.
2.4. Xdc dinh tinh chdt hda l-f hi hda phdm , Phuang p h i p xic dinh khdi lugng rieng: ASTM D1298;
Phuong p h i p xic dinh do nhdt ddng hoc: ASTM D445;
Phuong p h i p xie dinh nhiet do bat chiy cdc kin:
ASTM D93-2000;
Phuang p h i p xie dinh nhiet do bat chiy cdc hft Do hda tan (%) = (m^ - m ,)/m^
Nhom dung moi hoa tan paraffin Diesel (DO) 2 n-heptane 1 n-hexane 4 di-clometan 5
ASTMD92-2001;
Bang 3. Danh sdch hda chdt duo vdo khao sdt liia chon Nhom dung moi
hoa tan asphaltene Benzene Toluene Xylene Clo-benzene Dau thong {DT)
Chat hoat d6ng be mat EDA SDS LAS NP9 Tween 80
Mu'c tren (+) Mflc CO s6 (0) Mflc dudi (-) Khoang bien thien
Ty le DO/DT 1,5 0,875
0,25 0.625
Chat phu trcr
"HCI HjS04 NaOH N-Butylamine_
Diethanolamine Bong 4. Dieu kien Ihi nghiem toi Uu hda thdnh phdn mdu con CDU
Cac y^ujo^anh h u ^ g
Ham luong LAS (% khdi iugng) Ham lUong amin (% khoi \uqr^
56 DSUKHI-S0 7/2D16
Thanh phan cac nguyen to ' 1 _ I Ham lugng C
2 ' Ham iugng H j 3 Ham luong Na
; 4 j Ham lUong Ca I 5 Ham lUong Mg ' 6 Ham lugng Fe
Ham lugng V Ham lugng Ni Ham luong Al
Bdng 5. Ihdnh phon mau can trong thiet hi trao doi nhiet cua phdn XL
48,65 8,70 0,22 _ 3,16
0,15 7.23 ' 0,04 0,06
10 HamlUdngN , Thanh phaiicacjigp chat I
_1J__ I Ham luong can CCR [gom ei ham luong tro) j 12 Ham lugng paraffin
Ham lugng asphaltene 14 Ham lugng tro
1,8
50,10 24,65 2,64 32,05
45.70 8,60 0.42 5,16 0,21 4,52 0,04 0,05 2,10 0,05 43,50 20,47 2,53 35,72
51,25 7,19 0,12 4,43 0,26 8,13 0,05 0,05 1.85 0.06 57,90 23,47 2,33 40,51
Dan vi'% khoi luang M S U 4
34,32 ~ " j 5,51 " " " I 0,1 i _ j 6,10 \ 0,21 ' 12,40 ,!
0,02 0,01 2,31 0,81 56,15 19,54 4,56_
45,34
Phuong phap d i n h g i i tdc do an mdn dien hda:
ASTM G102.
3. Ket qua va thao luan 3.1. Thdnh phdn mdu can
Qua k i t q u i phan tieh nhan thay, ham luong can CCR trong mau can eiia cae thiet bi trao ddi nhiet trong phan xUdng CDU kha Idn, dao ddng t f l 40 - 60% khdi Iflgng.
H i m Iflgng paraffin trong mau can chiem 20 - 24% khdi Iflgng. Ham lugng tro dao ddng trong khoang 32 - 46%
khdi lUdng, ehfla chu yeu la cic oxide kim loai. Trong can CCR bao gdm ca tro, do viy, thanh phan can CCR theo k i t q u i p h i n tich bao gid eiing chiem ty le Idn. Ham Iflgng asphaltene tflOng ddi thap, dao ddng t f l 2 - 5%. Ngudn dau thd sfl dung trong Nha m i y Loc dau Dung Quat chit yeu la dau thd Bach Hd, l i dau chfla nhieu paraffin, nen trong thanh phan can ed ham Iflong parai^n cao. So vdi ham iflgng can CCR eua dau thd ban dau (theo quy dinh eua nha may, tdi da 4% khdi Iflgng), ham Ifldng can trong cic t h i l t bi trao ddi nhiet da tang d i n g ke.
Thanh phan can gdm cie nguyen t d C, H, cac nguyen td kim loai nhu Fe, Al, Ca... va cd the cd 1 sd nguyen td phi kim nhfl 0, N, S... Nguyen td C, H chu y l u tdn tai trong cic hgp chat hydrocarbon nhfl paraffin, asphaltene, nhua, cdc, polymer... Cac kim loai chit y l u tdn tai dfldi dang eae oxide kim loai, n g o i i ra cd the tdn tai dfldi dang phflc vdi eac hdp chat hflu co (cO - kim). Ham IflOng Fe cd trong mau c i n do mdt phan ed sin trong dau thd, mot phan trong qua trinh tdn chfla, van ehuyen dau thd, gi sat tren thanh be, dfldng dng trdn lan trong dau thd. Ham lugng kim loai Ca tflong ddi cao, mdt phan cd trong dau, mdt
phan do trong qua trinh khai t h i e dau cd sfl dyng nfldc d l bom ep dau nen Ca d dang CaCO^ trong nudc lan vao dau thd,Trong can cd ham lugng Al cao hon so vdi cac kim loai khic, Al thfldng ed trong dung dieh khoan. khi lan vao dau hay tdn tai dang hop ehat vdi silic. cho thay trong dau thd sfl dyng cho nha may cd chfla biin khoan. 0 tdn tai dfldi dang cac oxide kim loai, cic nguyen td phi kim nhu N, S thfldng tdn tai dudi dang eae hgp chat hydrocarbon dj vdng. N ed t h l tdn tai d dang hop chat trung tinh nhu indole, cacbazol, hay cac hop chat cd tinh bazo nhu pyridine, quinoline, acridine, phenanthridine. Luu huynh ed the tdn tai dang mereaptan. sulfur hay thiophene. Ty le C/H trong eae mau can dao ddng tfl 5 d i n 7 ehflng t d ham luong paraffin chilm chii yeu trong cae hgp chat hydrocarbon. Qua danh gia ket qua phan ti'ch. cac mau can trong thiet bj trao doi nhiet cua phan xudng CDU cd thanh phan tflong ddi gidng nhau. Do vay, cd t h l sfl dung 1 he hda pham tdt nhat de xfl ly can cho cac t h i l t bi trao ddi nhiet trong phan xfldng CDU.
Vdl thanh phan can da phan tich d tren, he hda pham du k i l n bao gdm cie thanh phan nhu sau: dung mdi hda tan paraffin, dung mdi hda tan hop chat hydrocarbon maeh vdng, ngoai ra bd sung them chat hoat ddng b l mat, ehat fle che an mdn va chat cd tinh acid nhe.
3.2. Che tgo he boa phdm
Tren eo sd phan tich cac thanh phan can. nhdm t i e g i i lua chon dung mdi phit hgp vdi tinh chat cita mau can trong thiet bj trao ddi nhiet ciia phan xudng CDU (sau day gpi tat la mau ein CDU) gdm 2 nhdm dung mdi hda tan la paraffin va asphaltene.
Diu KHi-SO 7/2016 57
Bdng 6. Dd hdo tan cdn cOa cdc dung mdi
TT
^ 1 i 2
' 3 4 '
; 5 ' " 6
7
\ TT
1 1
2 S - ^
r-:-
1 s
' TT
T l
"" 2 3 4
Loai d u n g moi
D u n g m o i hoa tan paraffin
D u n g m o i hoa tan asphaltene, hydrocarbon thOm
^.=_ . ^
Bdng 7. knh hudng cuo ty le dung D i e s ^ ( D O ) n-hexane n-heptane Toluene Xylene
D o hoa t a n {% khoi lupng)
Can CDU 15.26 12,25 11,74 8,52 10.43 Naphtha aromatic 11.15 D a u t h o n g ( D T ) 12,81
mdl den kha ndng hdo tan mau cdn CDU
Ty le d u n g moi (% khoi lUdng) Oo hoa t a n (% khoi lUong) ' 10%DO + 90%DT
2 0 % D O + ' 8 0 % D T 30%DO + 70%DT i 40%DO + 60%DT 50%DO + 50%DT 1 6 0 % D O + 4 0 % D T
'
11,52 _ 15,3118,92 22.43 21.83 19.27
Bdng 8. Anh hudng cua chdt hoat dong be mat den khd ndng hda ton mdu cdn CDU
Chat hoat d o n g Ty le ch£t hoat dpng b e m a t be m a t (% khoi lUcmg) Tween 80
Tween 60
LAS ' NP9 1 5 5 5 5
D o hba t a n [% khoi lupng)
25,35 31,40 31.15 26,45
Bang 9. Anh hUdng cda tyle chat hoat ddng be mdl/dung mdi den khd ndng hda tan cdn CDU Chat hoat dong T^ le chat hoat dpng be mat
be mat LAS LAS _ LAS
LAS Tween 60 Tween 60 Tween 60
(% khoi IUdng)
Dp hoa tan (% khoi lu'png)
31,73_
34,23 33,52 _ 31.35
31,27 _ 33,28
" 32,85"
Bdng W. Anh hUong tyle hdophdm/cdn khi dd bo sung chat hoot dong be mdt den kha nang hda tan cdn CDU TT Ty le h o a p h a m / c a n ( k h o i lUpng) D p hoa t a n (% k h o i l u t f n g )
1 4 17,62 2 6 22,43 3 8 _ 34,18
4 10 34,23
Bdng n. Anh hi/dng cua acid den I(h6 ndng hoo tan CDU cua he hdo phdm TT A c i d Ty le (% k h o i l u p n g ) O p h o a t a n (% k h o i l U p n g ) ,
1 EDTA 5 34,53 • '!
2 ^ c i d citric 5 34 47
3 H^SOJoang (20%) 3 34^26 4 HCI loang (15%) 3 34j9
58 DSUKH|.S0 7/2016
K i t q u i Bing 6 eho thay, dung moi diesel v i dau thdng cd k h i nang h6a tan cao. Diesel vdl thanh phan chiia ca hydrocarbon maeh t h i n g va hydrocarbon maeh vdng, ngoai viec hda tan ehO yeu cie hgp chat paraffin, cdn cd the hda tan duge cic hdp chat hydrocarbon madi vdng. Dau thdng l i chat cd kha ning hoa tan tdt eac hgp chat maeh vdng, ben canh do cd the hda tan hgp chat hydrocarbon maeh thang. Tfl ket qua Bing 6, nhdm tac g i i lfla ehgn dung mdi diesel (DO) va dau thdng (DT) la 2 thanh phan chinh cua he hda pham v i se tiep tyc nghien cflu ve t^le sfl dung va bd sung them cac thinh phan khic. Bfldc tiep theo la khao sit ty le giils 2 dung mdi i n h hfldng d i n k h i nang hoa tan m i u can.
K i t q u i Bing 7 cho thly, khi tang t$'l|
diesel t f l 10% d i n 40% va dau thdng giam tfl 90% xudng 60% thi khi nang hda tan cua he dung mdi ed xu hudng tang daa N l u t i l p tuc tang ty le diesel len 50%, 60%
thi k h i nang hda tan cd xu hudng giim dl.
Khi lugng diesel it, ham lugng hgp chat hydrocarbon mach t h i n g giam, khdng dd de hda tan h i t luong paraffin trong mau.
M i t khie, ham lugng dau thdng nhilu tiiC l i nhieu mach vdng, gay cin trd q u i trinh t i l p xue gifla cac hdp chat hydrocarbffli mach thang vdi paraffin, dan d i n giam k h i nang hda tan paraffin. Paraffin khong tan gay can trd q u i trinh tiep xuc gifla hgp chat hydrocarbon mach vdng eiia dung mdi vdi phan hydrocarbon mach vdng cua can, cung lam g l i m kha n i n g hda tan. Vfli ty le diesel/dau thdng thich hgp la 40% DO + 60% DT se cho k h i nang hda tan tdt nhat Viec bd sung cic chat hoat ddng be mat se lam t i n g kha nang tham t h i u cua hda pham. K i t q u i khio sit dd hda tan vffi cac chat hoat ddng b l mat khic nhau dugc trinh b i y trong Bang 8.
Trong mau can thfldng chfla nflde, do vay, khi bd sung them chat hoat ddng be m i t se tang k h i nang tham thau, k h i ning tiep xuc ciia dung mdi vdi cae thanh phan hydrocarbon trong mau can, dan den lam
a r t * ' ' "
.;jjjM t l i -
' tang k h i nang hda tan. K i t qua chi ra rang, LAS
" va Tween 60 la 2 chat hoat ddng b l m i t lam
• tang dd hda tan cao nhat.
Khi g i i m Iflgng chat hoat ddng b l mat den
;. mflc nao dd thi kha nang hda tan cua he dung . mdi tang. Vi khi t i n g chat hoat ddng be mat
^ d i n g i i trj nao dd thi k h i nang hda tan dflgc
^ Idn nhat va n l u ed them chat hoat ddng be mat
^ nfla thi cung khdng cai thien dflgc kha nang
^ hda tan, mat khac cdn lam g i i m lugng dung . mdi, VI vay, g l i m kha nang hda tan. Ngoai ra, khi sfl dung Tween 60, Iflgng bot smh ra trong q u i trinh khuay trdn tuong ddi nhieu, can phai _ bd sung them chat khfl bgt de giam mflc dd tao bgt. Ddi vdi LAS, luong bgt khdng d i n g k l , khdng can p h i i sfldung chat khfl bgt va khi sfl dung LAS, he hda pham cd k h i nang hda tan tdt hdn so vdi Tween 60.
Sau khi da bd sung chat boat ddng b l mat vao he hda pham, nhdm t i e g i i d i n h gia lai ty le hda pham/can de tim ty le phii hop.
Khi ty le tang t f l 4 d i n 8 lan thl dp hda tan tang len dang ke t f l 17,62% len 34,18%. Tilp tue tang ty le len 10 lan, do hda tan tang khdng dang k l , luc n i y dung dieh da dat den mflc do bao hda. Viec bd sung chat hoat ddng be mat da lam tang kha n i n g tham thau va kha nang tiep xue ciia dung mdi vdl chat tan. Cd the sfl dung lugng dung mdi it hon de hda tan can ma van d i m b i o dugc kha nang hda tan tdt. Ket qua Bang 10 cho thay ty le phii hgp nhat la 8 lan.Ty le nay se disac sfldung cho phan nghien cflu t i l p theo.
Tiep tuc, nghien cflu bd sung them acid vdi myc dich hda tan cae kim loai, oxide kim loai ed trong mau can. Bang 11 dUa ra ket qua khao sat k h i nang hda tan cua he dung mdi khi bd sung them cac acid hflu cd va vd co.
Khi bd sung them cic acid vd ca dfldi 3%
thi kha n i n g phan tan van tdt, neu tang len nfla, dung djch tao thanh dang nhao, khdng the hda tan duoc. Do khi tang h i m IflOng acid vd ea len, kich cdciia cac mixen se tang dan v i den mflc dd sieu Idn tao thanh diem van due, lam tang do nhdt cua he dung mdi, nhieu diem van due hinh thanh l i m he dung mdi ehuyen sang dang nhao. K i t qua khao s i t cho thay, viec bd sung
Bdng 12. Anh hudng cuo cac chat trung hda den khd ndng hda tan can CDU Chat phu trp Ty le (% khoi lUdng] Dd hoa tan (% khoi IflOng)
6 34,56 Diethanolamine
N-butylamine NaOH Ba(OH), KMnOj
35,24 32,55 33,47 33,82 Bdng 13. Kel qud khdo sdt dnh hUdng cua ty le thanh phdn den do hda tan cdn CDU
(Ihdi gian 2 gid, tdc do khudy 150 vong/phut. nhiet do 25°C) Th
Ty le DO/DT 0,25 0,25 0,25 0,25 0,25 0,875' 0.875 0,875 "
0,875 0,875 0,875 0,875
mh phan he hoa pham
LAS Amin (% khoi lupng) (% khoi lU
1 2
" 4 " 2 1 " "10 4 10 2,5 " 6
1 6 4 6 2,5""'" "" " " 2 "
2,5 10 2,5' 6 2,5 ~6~
2,5 6"
17 1,5 2,5
Dp hoa tan (% khoi lupng)
15,31 '25,35 ' i _ 22,43
31,73 _ " 32,85
" 31,56 _ 35,18 32,48 I, 35,64 33,52 33,96 _ 32.64 "
19,27 26.45 _ _ 27.82
32.73 35.98 them acid vao khdng lam tang kha nang hda tan cita dung djch. Cd t h l do do acid khdng dit manh va cac oxide trong can khd tan. Neu sfl dung acid vdi ham lugng Idn, ndng do cao se gay an mdn manh trong dfldng dng. Cac acid hflu ca cd the hda tan vd han trong dung mdi hflu CO, nhflng dp acid yeu, cung khdng the hda tan dugc cac hgp chat oxide kim loai cd trong can.ThuctI, khi hda tan mau trong mdi trudng aeid manh (HCI, H^SO^ cd ndng dp cao), cung khdng thay cd sU thay ddi, cd the la cac oxide kim loai duoc bao phit ldp cdc hay cac hgp chat hflu CO, nen ngan can qua trinh t i l p xiie gifla acid va oxide kim loai.
Vdl he hda pham nhu tren. nhdm tae g i i t i l n hanh xac djnh tdc do an mdn bang phuong p h i p dien hda. Ket qua cho thay, he hda pham cd kha nang gay an mdn kim loai. Nhdm tac gia nghien cflu bd sung them cac chat cd tinh ktem de d i l u chinh dd pH cita dung mdi ve b i n g 7. Bang 12 dua ra ket qua khao sat dd hda tan khi cho them cae ehat phy trg vao he hda pham.
Qua khao sat, xac dinh duoc lugng can them vao va d i n h gia lai khi nang hda tan eiia dung dich. Ket q u i Bang 12 cho thay, khi them eac hop chat vd co, kha nang hda tan eiia dung dieh khdng bi anh hudng. Ddi vdi eac hgp chat hflu ea, dd hda tan cd t i n g len nhung khdng n h i l u . Vdi ty le N-butylamine la 5%, do hda tan t i n g len khoing 1,8%, day la ehat thich hop nhat d e b d sung vao dung mdi.
niu KHl-SO 7/2016 59
3.3. Toi Uu boa thdnh phdn hi hoa phdm
Myc tieu ciia viec tdi flu hda t h i n h phan he hda pham l i he hda pham ed k h i nang hda tan can Idn nhat.Thanh phan chinh ciia he hda pham l i diesel va dau thdng, d i y l i 2 thanh phan chilm chu y l u trong he hda pham, anh hfldng Idn nhat d i n k h i nang hda tan mau can. Qua khao sit i n h hudng cua ty le DO/DT, ty le LAS trong he dung mdi den kha nang hda tan mau can da dugc trinh bay d tren, nhdm tac g i i lfla chgn khoing biln thien ty le DO/DT = 0,25 -1,5, ham Iflgng LAS tfl 1 -
Hint} 2. Mdt tdi uutyle thanh phdn he hdo phdm hoa tan cdn CDU Bdng 14, Ket qud toi Uu ty le thanh phdn he hda phdm hdo tan cdn CDU
DO/DT 6,6761 0,6156 0,6686 0.6706 1.2690 1,2696 1,2696 1.2696
LAS 2,0249"
1 , 9 1 6 9 ' 1,8597 1.0028 1,0028 "
1,0028 1,0028 1,0028
A m m 5,3528 5,4342 5,1649 8,2279 8,2279 "
8,2279' 8,2279 8,2279
Dohoatancan 35,'7505 34,7814 35,1335 34,0104 17,1494 17.1494 17,1494 17,1494
Iter
" 40 40 41 38 40 40 40 40
Log(D) -0.7301 -0,0594 -0,2483 1,9705 -0,0674 -0,0674 -0,0674 -0,0674
Trang thai
Bdng 15. Tinh chdt hda ly cda he hda phdm
He hoa p h a m hoa t a n can CDU D d n vj tfnh
M U I pH
Nhiet d o c h d p chay coc kin Nhiet d o c h a p chay coc h d P o n h d t 6 40°C Ty t r o n g d 15°C _ N h i e t d o s o i
_An m o n
, KhS nang tan t r o n g nude
6 0 DSUKBI-SO 7/2016
Dang l o n g , m a u v a n g H i c , g i o n g miti dau t h o n g
6 , 5 - 7 4 4
55 1
Khong Tan rat it
4%. Thanh phan N-butylamine trong dung m6i cd vai trd l i hop chat trung hda acid, phu thujc nhilu vao thanh phan LAS, day la ehat tao tra trudng acid. Tren co sd k i t q u i khio sal inh hudng ciia thanh phan LAS v i N-butylamine d i n do pH ciia dung djch, nhdm t i e g i i lua dion khoing bien thien ciia N-butylamine tfl 2 -10%, T i l n hanh tdi flu hda theo phan m ^ thdng ke va k i t q u i quy hoach tdi flu theo phflong i n bac 2. Thdng qua b i n g dinh q\i Anova cho thay do tflOng quan eua phep quy hoach thflc nghiem la 91,7%.
Phflong trinh hdi quy thu trong he toa do thflc dflOc bleu dien nhfl sau:
Y = 35,61 + l,46x^ + 3,50x^ + 3,12x^-2,89Xj- 3,93x^^ - 3,24x^^ - 0,91XjX^ + 0,17XjX^ - 0,38x^^
Phflong trinh nay dflgc t f l ddng kiem tia va danh gia theo chuan Fisher vdl mflc y nghia 0,05% cho thay phuong trinh phit hop vdi thifc nghiem. Sfl dyng phan mem Modde 5.0 ve mat tdi flu (Hlnh 2),
Kit q u i tdi uu nhu sau: Ty le DO/DT la 37,2/55,57 va hoat ddng be mat chilm 1,88%, amin chilm 5,35% se hda tan dflgc 35,75%caa Vdi dieu kien khio sit d 25''C, tdc dp khu^
150 vong/phut va thdi gian 2 gid, thanh phln phil hgp ciia he dung mdi duge xac djnh ty le phan tram theo khdi lugng la: ty le diesf dau thdng/chat boat ddng b l mat/amin = 37,2/55,6/1,8/5,4, ty le ve khdi lUdng he dung mdi/ean khoing 8 lan, khi dd do hda tan 3i\
eao nhat la 35,75%.
3.4. Tinh chdt he hda phdm
K i t qua phan tich tinh chat he hda phSm cho thay, nhiet dd chdp chay cdc kin ciia he hda pham hda tan can CDU la 43,5°C.Vdi nhiel do chdp ehay nay, de d i m b i o an toan ch^y nd trong q u i trinh Iflu trfl, b i o q u i n , can dim b i o gifl nhidt dd mdi trfldng xung quanh diffll nhiet dd chdp chay va nhiet dp v i n hanh diifli 40°C. He hda pham khdng ed tfnh an mdn, ni^
hoan toan khdng g i y hai cho he thdng thiet bi trong nha may.
Phflong phap xfl ly c i n trong t h i l t bi trao ddi nhiet bang hda pham dfl k i l n gdm ck- bfldc sau:
^3^"*?^:^,
, f ^ T O U R '
Bfldc 1: Khao sat hien trang l i n g c i n va xic dmh thanh phan can;
Bfldc 2:Tinh toan Iflgng hda pham can ditng;
Bfldc 3: Tinh toan van tde ddng va luu Iflgng ddng can thiet;
Bfldc 4: Lap dat he thdng va k i l m tra;
Bfldc 5: Bom tuan hoan he hda pham;
Budc 6: Sfldung hoi nfldc qua nhiet va khi khd thdi qua dng trao ddi nhiet;
Budc 7: Xfl ly chat t h a i
Hda pham sau khi xfl ly dflgc phdi trdn vdl dau Mazut, l i m nhien lieu ddt cho nha may.
Can ran dugc thu gom dUa tdi khu chfla ehat thai nguy hai cua nha miy.
Nfldc t h i i dugc thu gom lai, pha loang va dfla vao he thdng xfl ly nude nhiem d i u £TP ciia nha m i y hoac cd t h l dua d i n khu chfla chat thai nguy hai cfla nha miy.
4. Ket luan
Phan tich t h i n h phan mau ein trong cae thiet bi trao ddi nhiet thudc phan xfldng CDU eho thay eac mau can trong thiet bi trao ddi nhiet ciia p h i n xfldng CDU cd ham lugng can CCR tfl40 - 60% khdi IflOng, paraffin tfl 20 - 24%
khdi IflOng, ham Iflgng tro t f l 32 - 45% khdi lugng. Ty sd C/H dao ddng t f l 5 - 7 cho thay ham luong parai^n chiem chu y l u trong cic hgp ehat hydrocarbon.
Ve nghien cflu c h l tao he hda pham, nhdm tae g i i d l xuat thanh phan tdi flu he hda pham xfl ly can trong thiet bj trao ddi nhiet thude p h i n xfldng CDU eiia Nha may Lpe dau Dung Quat nhUsau: diesel/dau thdng/chat hoat ddng
b l mat/amin = 37,2/55,6/1,8/5,4, ty le v l khdi luong he dung mdi/ean la 8 lan theo khdi luong. K i t qua xae dinh ti'nh chat hda ly cita he hda pham hda tan can cho thay he hda pha'm khdng g i y an mdn t h i l t bi, tan rat ft trong nude va nhiet dd chdp chay cdc kin la 44°C.
Tai lieu tham khdo
\. S.N.Kazi. fouling and fouling mitigation on heat exchanger sur faces. \n\ecY\open. 2C^Q^.
2. Mostafa M.Awad. Fouling of heat transfer surfaces.
Intechopen. 2001.
3. Hans Muller-Steinhagen. Heat exchanger fouling - Mitigation and cleaning technologies. Publico Publications.
2000.
4. Mohammad Reza Mozdlanfard, Elaheh Behranvand. A field study of fouling in CDU preheaters at fsftjftan refinery. Applied Thermal Engineering. 10 January 2013; 50(1): p. 908-917.
5. C.Cunault, Y.Coquinot, C.H.Burton. S.Picard.
A.M.Pourcher. Characteristics and composition of fouling caused by pig slurry in a tubular heat exchanger - Recommended cleaning systems. Journal of Environmental Management. 15 March 2013; 117: p. 17 - 31.
6. Mohammad Reza Jafari Nasr, Mehdi Majidi Givi.
I^odeling of crude oil fouling in preheat exchangers of refinery distillation units. Applied Thermal Engineering.
October 2006; 26(14-15): p. 1572 -1577.
7. A.M.Pritehard. The Economics of Fouling. Fouling Science and Technology. L.F.Melo et al. (eds.). Kluwer Academic Publishers, Netherlands. 1988: p. 31 - 45.
Chemical treatment of fouled heat exchangers in Dung Quat Refinery
Le Quang Hung, Nguyen Thi Mai Le Nguyen Khanh Toan, Nguyen Thi Lan Anh Vietnam Petroleum Institute Email: [email protected] Summary
Heat exchangers of CDU in Dung Quat Refinery are frequently fouling. The study and use of chemicals for fouling , treatment are of great economic significance for the refinery. This paper briefly introduces the fouling phenomenon, the ecoitomic effects of fouling in refineries, and current anti-fouling treatment in Dung Quat Refinery. The authors , evaluated the deposit properties and prepared suitable chemical for fouling treatment. The results show that there are about 40 - 60% of CCR deposit and 20 - 40% of paraffin in the fouling deposit, which has a C/H ratio of 5-7. The produced chemical has a diesel oil/turpentine/surfactant/amine ratio of 37.2/55.6/1.8/5.4 and a chemical/deposit weight ratio of 8. The solution after fouling treatment is suitable for use as furnace fueL
Key words: Fouling in heat exchanger; chemical cleaning for heat exchanger.
DAUKHi-S0 7/20ie 61