NGHIEN ClTU THU'C NGHIEM BQ XU" LY XUC TAC CHON LOC KHU* NO, LAP TREN XE TAI HANG NHE
NGUYEN TUNG LAM Trucmg Dgi hgc Giao thdng Van tdi NGUYEN M A N H DUNG Trudng Bgi hgc Cdng nghiep Hd Ngi P H A M MINH TUAN
TRAN QUANG VINH Trudng Bgi hgc Bdch khoa Hd Ngi
Tdm tdt: Dd cd nhiiu nghien ctru gidm phdt thdi NO:, tu ddng ca diesel lap tren cdc phuang tiin giao thdng cd trung binh vd ldn, trong do bg xu ly xiic tdc kieu chgn lgc sir dung urea rdl dtrgc quan tdm. Bdi bdo trinh bdy kit qud nghien ciru tinh todn vd thtr nghiim bg xu ly khi thdi vdi bd xd ly xtic tdc kieu chpn Ipc sir dung urea (urea-SCR) cho dpng ca diesel xe tdi hang nhe. Tir cdc thong so cua dong ca mdu - dgng ca diesel D243, cdc tdc gid dd tinh todn thiet ke bp urea-SCR bao gdm loi, vd xue tdc vd bp dieu khien phun urea. Sau dd, bg xir ly xue tac dd che tgo dugc ldp ddt vd thu nghiem tren bdng thir ddng ca nhdm ddnh gid hiiu sudt khie NOx cua bd urea-SCR & dgc tinh ngodi dgng ca. Kit qud thu nghiem cho thdy hi^u sudt khu trung binh dgt dugc Id 87,3%.
Summary: To reduce NO^ emission from medium and heavy duty trucks, the urea selective catalytic reduction (urea-SCR) systems have been much studied previously This paper presents the calculating process and experimental results, using the urea-SCR for diesel engines of light trucks. From the specifications of the sample engine D243, the authors have designed and manufactured the urea-SCR, including filter core, housing and urea injection control system. Then the urea-SCR has been installed and tested on the engine test bench. The NOj, reduction performance of the urea-SCR system has been measured and evaluated under fiill load conditions. The experimental results show that the average NO, removal efficiency is
87.3%.
I. D A T V A N D E
Ca che hinh thanh vd cac n h a n Id a n h h u d n g d i n n d n g dd phat thai NOx tien d d n g c a ddt trong d u g c phdn tich va danh gid d rat n h i l u c d n g bd [4]. V d n d l x u ly NOx d a d u g c cac nhd nghien c u u tiong [ 1 , 6] va ngoai n u d e [2, 3] rdt quan tam. H a n niia, quy dinh khdt khe h a n v l phat thai tren p h u a n g lien giao t h d n g d a d u g c b a n hanh. N g a y 1/9/2011, Thii t u d n g Chinh phii dd ra Q u y l t dinh so 4 9 / 2 0 1 1 / Q D - T T g [7], q u y dinh Id tiinh ap d u n g lieu chudn khi thdi, cac loai xe d Id san xudt, lap rap va nhap khdu m d i phai dp d g n g tieu chuan khi thai mirc 4 (Euro 4) tu ngdy 1/1/2017 va miic 5 (Euro 5) tir ngay 1/1/2022.
V d i tieu e h u i n khi thai miic 4 tiii l u g n g NO^ trong khi thai d d n g c a tiong khoang: 2-3,5 g/kWh. V d i tieu chudn khi thdi n h u vay, da sd cdc xe san xudt, ldp rap trong n u d e hien tgi chua dap ling d u g c . H o n nira, d l dat miic d o phat thai dap iing tieu chudn Euro 4 thi bdt h u g e phai xir
146 Tap chi KHOA HQC GIAO THONG VAN TAI So dSic biet - 11/2015
dung cac bidn phap xu ly khi thai phia sau cua thai (after-tieatment). Trong cac giai phap giam phat thai NO^ thudng dung, gdm luan hdi khi thai (EGR), bay hdn hgp ngheo (LNT), xii ly xiic tac chgn lgc (SCR) thi bien phap xu ly xue tac chgn Igc cd uu the vugt tidi vl chi phi va hieu suat khu NOx [6]. Yeu cdu thuc tiln dat ra la nghien ciiu, tmh toan che tao thu nghiem he thdng SCR tren bang thir ddng ca de danh gia hieu suat khii, xay dung cac bai loan tdi uu de cd the dua vao san xuat san phdm thuang mai dap iing nhu cau trong nude nhirng ndm ldi.
Mdt he thdng SCR co ban gdm cac bd phan: loi bd xiic tac, vd bdo ve vd he thdng phun urea. Trong nghien ciiu [I], nhdm lac gia da dua ra va phan tich cac phucmg an cho bg xii ly khi thai diesel gdm ba cum: bd xiic tac d-xi hda (Diesel Oxidation Catalyst-DOC) de xii ly CO va HC, bg xir ly xiic tac chgn lgc SCR de khu NOx va bg lgc DPF de xii Iy thanh phdn PM, theo hai each bd tii la DOC-SCR-DPF va DOC-DPF-SCR Phuang an da dugc lira chgn vdi muc dich se lap dat tren cac xe lai hang nhe dang luu hdnh la he thdng xii ly xiic tac dugc bd tri theo trinh tu DOC-DPF-SCR (tir tiai sang phai, bdt dau tu vi tri gdn ciia xd).
Trong bd xu ly xiic tac chgn lgc urea-SCR, NOx tii khi thai ddng ca diesel dugc khii bdi cac phan ung hda hgc cd su tham gia cua chat khii la ammonia (NH3) va xiic tac boat hda.
Trong qua trinh khii NOx thi NO2 ludn la tac nhan boat dgng, NO2 se phan iing true tiep vdi NH3, tiong khi NO se bi oxi hda mdt phan thanh NOi va tdc do cua qua trinh dgt cao nhat khi ti le NO:N02:NH3 tiong hdn hgp la 1:1:2. Trong nhiing ket qua nghien ciiu mdi nhit ciia Nguyen Le Phiic [2, 3] cung cho thay sii dung NH3 cd tdc do khu NO, rat nhanh, dam bao cho viec xir ly NOx tren dudng thai ddng ca ddt trong.
II. THIET BI VA PHirOfNG PHAP THU NGHIEM 2.1. Cff Sff khu- NO, bdng NH3
Cac phan irng khd NOx li^ng NH3 tien dudng xa vdi he xiic tdc vanadi:
Phan ung chudn: 4NH3 +4NO+O3 ^ 4 N , +6Hp (1) Phdn ling nhanh: 2 N H 3 - H N O + N 0 3 ^ 2 N , + 3 H , 0 (2) Phan ling chgm: 8NH3+6NO,^7Nj+12H20 (3) Tren thuc ll thi phat thai cua ddng ca diesel thi lugng NO chilm 90% nen khii NO^ phan
Idn dugc thuc hien theo phan ung chudn, cdn phan iing cham vdi ty le NO2/NO > 1 thi thudng khdng xay ra. Vdi phan iing nhanh va chuan thi ta xac dinh dugc ty le moi tuang ung:
^NH /m = 1' ^^^ P^^^ "^8 ^'^^ ^ ' ^ S *°"S ^dp nhu sau:
4NH3 +4N0, +(3-2x)03 ^ 4 N , -heHjO (4) Trong do: x thi hien tiianh phdn NO vd NOj cd tiong hdn hgp khi NOx-
Tuy nhien, viec su dung true tilp NH3 lam tac nhdn khu NOx ti-ong dieu kien thuc te gan nhu la khdng thi do viec luu trii NH3 la rdt khd khan. Dd la ly do ngudi ta phdi tao ra NH3 mdt each gian tilp tu phdn ung tiiiiy phdn va phan hiiy urea, va qua tiinh tao NH3 tiimg gian nay cung lam gidm hogt tinh chuyen hda NO^ [3].
Phdn ling thuy phdn urea: (NH2)2CO->NH3+HNCO (5) HNCO-^Hp^NH3+CO, (6) Tgp chi KHOA HQC GIAO THONG VAN TAI S6 d a c biet - 11/2015 147
2.2. Sff do he thdng xir ly xiic tac urea-SCR
He thdng xii ly xiic tac kieu chgn lgc lam viec theo nguyen ly trinh bay tren hinh I. Bom hiit dung dich urea cd ndng do 32,5% vd dua den vdi phun. Khi cd tin hieu dilu khien tii ECU, vdi phun phun dung dich urea vao dng thuy phan tren dudng thai ciia ddng ca, hda trgn va nhgn nhiet ciia khi thai. Khi nhiet do khi thai tien 200''C thi urea thiiy phan thanh amoniac va nude.
Sau dd, amoniac thuc hien khii NOx vdi he xiic tac vanadi.
Hinh 1. Sa do he thdng xu ly xue tdc urea-SCR 2.3. Doi tugng v^ phuong phap thu nghiem
Ddng ca thu nghiem Id dgng ca diesel D243 4 xy lanh, 4 ky khdng tang dp cd cac tiidng si CO ban trinh bay tiong bang 1. Ddng ca dugc dat tren bang thii dgng luc hgc APAIOO tai PTN Dgng CO ddl tiong, Tnrdng Dgi hgc Bach khoa Ha Ndi. Thii nghi8m tren dac tinh ngoai, do d cac chi do tdc do 1000, 1200, 1400, 1800, 2000, 2200 v/ph. CJ mdi chi dd tdc dd khac nhau dugc tien hanh do 3 lan, rdi lay gia tri trung binh ciia cac Idn do.
Trong nghien ciiu nay, cac tdc gia thuc hien thu nghiem tren dgc tinh ngoai, vdi yeu cau phun urea theo ty le moi r„^ ^^^ =\. Thuc hien dieu khien phun urea theo kieu vdng hd vdi so dd nhu da trinh bay tren hinh 1.
Bang 1. Cdc thdng Thdng so Kieu ddng ca Dudng kinh x hanh trinh
Dung tich xy lanh Cdng suit ldn nhat
Ty sd nen
so ca ban cua ddng ca D243 Gia tri 4 xy lanh, thang hdng
llOmmx 125mm 4,75 dm^
80 HP /2200v/ph 16:1 III. ECET QUA THU'NGHIEM
K8t qua do cdng sudt Ne va sudt tieu hao nhien Ii6u g^ dugc thi hi^n tien hinh 2. Cd thi thdy rdng cdng sudt cua dgng ca khi ldp bd xu ly khi thai DOC-DPF-SCR cd giam chiit it Tuy nhien, sudt tieu hao nhien lieu giam khdng dang kl.
148 Tap chi KHOA HOC GIAO THONG VAN TAI So dac biet - U/2015
Hinh 2. Ket qud do cdng sudl vd sudl tieu thu nhien lieu cda dpng ca D243 Tai gia tri cdng suit ldn nhdt thi cdng sudt giam 1,45%) khi cd lap bg DOC-DPF-SCR. Nhu vdy, khi sii dimg he thdng xii ly khi thai DOC-DPF-SCR thi khdng lam anh hudng den tinh nang ky thuat cua ddng ca. Dgng ca khi lap bd xiic tac dugc thii nghiem chay b8n lOOh, khi dd cd su suy giam cdng suat ldn hem do cd mgt sd hien tugng lac cue bg loi xiic tac, ldi Igc.
Kit qua phdt thai NOx dugc the hien tien hinh 3, trong dd hieu suat khu NOx dugc dinh nghia nhu sau:
C V O , . ™ - C N C
fiSK^,o_ - - - 100% (V)
VdiCN, ^ la ndng dg NO^ tiong khi xa di vdo va ra bd xu ly xue tdc (ppm).
IIUII
1000 1600 leOO 2000 2200
T6c dfrd^ng co (v'pii)
• • N b i Q 0 ^ NCB k i r t c U i i l i p D O C J X > F ^ C R (rfKTi)
^ N b q a » N O l Eau Uu 1 ^ [XXMJFF.SCR (ppm) a t i e u s i A l d i i J N O i (%)
Hinh 3. Ndng dd vd hiiu sudt khu NO,, trin ddc tinh ngodi cua ddng c Mat khac, hieu sudt khii NOx cd ihl tinh loan bang bieu thiic:
Vdi V:^: thi tich ldi xue tac (cm^); k: hdng sd tdc do phan iing (lis); Gx: luu luang khi xa (cmVs).
Kit qua tien hinh 3 the hien ndng dg phat thai NOx khi thii nghiem ddng co D243 nguyen ban va ddng ca cd Idp bd xu ly khi thai DOC-DPF-SCR. Khi dgng co cd ldp them bg xii ly khi thai thi ndng do NO, giam 87,3%i so vdi ddng ca nguyen ban tiSn dgc tinh ngoai ddng ca. Trong Tgp chi KHOA HQC GIAO THONG VAN TAI So dac biet • 11/2015 149
dd, tai sd vdng quay 1600 - I800v/ph, hieu suat khii NOx dgt cao nhdt 89%). Dilu nay hoan toan phii hgp vdi cdng thiic (8), vi theo cdng thiic nay, hieu suit khii ty le nghich va phg thugc nhieu hon vdi ndng do nita dxil. Ddng thdi ciing ty le nghich nhung phu thudc it han vdi luu lugng khi xa ma luu lugng khi xa ty le thuan vdi tdc do ddng ca. Vay nen tgi miic tdc do trung binh nay thi hieu suat khir Idn nhat.
Khi tdc do ddng ca tdng tii 1000 den 1600 v/ph thi luu lugng khi xa Gx tdng, ndng do nita dxil CNOX tiong khi xa gidm thi hieu suat khii NO, tang len. Vdi tdc do tang tii 1800 den 2200 v/ph thi ndng do nita dxil thay ddi it cdn luu lugng khi xa tang nhanh lam giam thdi gian luu trii ciia khi xa tien be mat ciia vat lieu xiic tac nen hiSu suat khii NOx giam manh.
IV. KET LUAN
Tii cac ket qua nghien ciiu thuc nghiem danh gia miic do giam phat thai khi su dung bd xu ly xue tac urea-SCR da trinh bay d tien, cd the dua ra mgt sd kel luan nhu sau.
- Ket qud thuc nghiem tren ddng ca D243 da cho ket qua khd quan vdi hieu suat khu tnmg binh ldn d che do dgc tinh ngoai. O cac che do tai cue bd, vdi ndng do NOx thap han, luu lugng khi thdi thdp hon thi hieu sudt khii NOx se cao hon. Vdi bd xii Iy xiic tac chgn Igc lap tren dgng CO D243 thi ddng ca dd cd Ihl dap irng dugc tieu chudn khi thai miic 4.
- Vdi lugng cung cap urea cho he thdng SCR theo ty le moi r.^.^, ,^Q = I thi lugng amoniac dl ra ngoai mdi tnrdng cdn Idn. Vi vay de nghien cim can tiep tuc phat trien theo hudng tdi uu hieu sudt khd vdi dieu kien phat thai amoniac trong gidi han hien hanh (ndng do amoniac C N H 3 < lOppm).
Ngay nhan bai l^n d i u : 24/9/2015 Ngay nhan bai sua: 4/10/2015 Ngay chap nhan ddng bai: 1/10/2015
Tdi lieu tham khao
[!]• l^guyen Mgnh Diing, Phgm Minh Tudn, Pham Hiru Tuyin, Trdn Quang Vinh (2015). "Thilt kl, chi tao bg xij ly khi thai kSt hgp DOC-DPF-SCR cho dong co diesel ldp tren xe tai". Tap chi Khoa hoc Cong nghfi Truong Dai hoc Cong nghiep Ha Noi, s6 27 thang 4/2015.
[2]. Nguyin Le Phiic, X. Courtois, F. Can, S. Berland, S. Royer, P. Marecot, D. Duprez, "A study of the ammonia selectivity on Pl/BaO/A1203 model catalyst during the NO, storage and reduction process". Catalysis Today, In Press, Corrected Proof, 27 November 2010.
[3]. Nguyen Le Phuc, X Courtois, F Can, S. Royer. P Marecot, D. Duprez, "NOj removal efficiency and ammonia selectivity during the NO^ storage-reduction process over Pt/BaO (Fe, Mn, Ce)/AI203 model catalysts. Part II: Influence of Ce and Mn-Ce addition", Applied Catalysis B' Environmental, Volume 102, Issues 3-4,22 February 2011, Pages 362-371.
[4], Dinh Xuan Thdnh, Le Anh Tudn, Pham Vdn Thi, Khdng VU Qudng. "Nghifin ciiu giai phap giam phat thai NO, va khoi den cho dong co diesel ldp tren xe buyt". Tap chi Khoa hoc va Cong ngh?, Trudng DHCN Ha Noi 2011; ISSN 1859-3585; No. 5.
[5]. Phgm Huu Tuyen. Nguyen Thi Lirang. Le Anh Tudn, Dd Thanh Hdi (2013). "Nghien cihi tinh toan litgng ure cung cap cho bg khii NO, bang xue tac c6 chon loc ldp tr^n dong co xe buyt". Tap chi Ca khi Viet Nam, thing 10/2013.
[6]. Trdn Quang Vinh, Pham Minh Tudn, Nguyin Mgnh Dung. "Sir dung bo xiic tac chgn lgc SCR kit hop vdi cym DOC-DPF d l xir ly khi xa dflng co diesel". Tap chi Co khi Viet Nam, s6 dac bi|t 2014.
[7]. Thii tuong Chinh phii, Quylt djnh VS viec quy djnh lg trinh ap dimg tieu chuin khi thai d6i voi xe 6 t6,xe mo tfl hai banh san xudt, 15p rap v a n h | p khdu moi, s6 49/2011/QD-TTg, ngay 01 thdng 09 nam 2011 •
Phan hien: Ngo Van Thanh, Pham Tat Thing
