KHAI THAC

Cau1: dac tinh dco la gi?su phoi hop ctac giua dco voi cahn vit dc the hien tren dthi dac tinh ntnao?

TL: dtinh dco la moi qhe giua csuat dco voi vquay cua dco khi luong nhlieu cung cap cho chu moi chu trinh cotac ko thay doi(luong nhlieu phun vao buong dot ko doi)

Su phoi hop ctac giua dco voi cvit:

a. Khi dieu kien khthac ko thay doi:ve dothi dac tinh. Voi Co, Cv=const,diem N la diem phoi hop ctac giua dc ova cvit. Trong khthac thuong sdung dac tinh khthac vat hap hon dac tinh dinh muc: Nk=(0,85-0,95)Nn.

- Phan csuat giam di dung de du tru de khac phuc khi phu tai dco tang, dong thoi de tang tuoi tho dco.

- Khi dco da cu hoac mot vai xilanh hong hoac khi dieu dong tau ra vao cang thi phai thay doi tay ga tuc la thay doi luong nhien lieu cung cap cho moi chu trinh. De co dc csuat hop ly va diem phoi hop ctac se la diem I. tai I co e= 0.55-0.95, la he so giam csuat.

Ketluan: trong dkien kthac ko thay doi ta co the thay doi diem phoi hop tac giua dc ova chan vit bang cach thay doi tay ga de co diem phoi ctac ma tai do cac tso ctac toi uu cua dco.

b. Khi dk khthac thay doi: Co thay doi> Cv thay doi, Mk=0.9Mn

Gia su dco trang bi BDT luc nay diem phoi hop ctac giua dco va cvit se la K1, K2, K3... tai cac diem phoi hop ctac khac nhau ca tso cua dco cung se thay doi. Ket luan: khi dk kthac thay doi thi diem phoi hop ctac giau dco va cvit cung tahy doi theo. Do vay trong qua trinh kthac chung ta phai chu y den su qua tai cua dco, trong 1so truong hop phai giam tay ga.

c. Su phoi hop ctac giua dc ova cvit trong thuc te kthac: trong thuc te kthac dco co lap BDT nhieu che do. Thong thuong cac dco diesel lai cvit thuong dc trang bi BDT nhieu che do. Do vay trong dk kthac thay doi nguoi van hanh phai dat vi tri tay ga nhat dinh nhung do phu tai thay doi lam cho diem ctac cua dco thay doi, trong nhung truong hop do BDt se tac dong vao co cau dieu chinh de tang hay giam luong nhien lieu vao dco de duy tri va on dinh diem phoihop ctac.

Cau2: pham vi ctac cua dco va cvit dc the hien tren dothi dac tinh ntnao? Khi dco cang cu thi.....

TL: a. ve do thi dac tinh(dung la Ni, nam la n) gom cac duong:Cu, hmax,hn, hkt,hmin, n , nmax,nmin

Pham vi ctac cua dco lai cvit dinh buoc dc the hien tren dthi dac tinh n-Ni gom gioi han cua cac duong dac tinh sau:

- Cu: dac tinh cvit khi thu tau tai ben.

- Hmax: dtinh csuat lon nhat cua dco

- Hn: dtinh csuat dinh muc

- Hkt: dtinh csuat khia thac cua dco

- Nmax: gioi han vquay lon nhat

- Nmin: gioi han vquay toi thieu on dinh cua dco.

Nhu vay: pham vi ctac chinh la phan dien tich cua 3 vung:1+2+3 trong do

- vung1: dc gioi han boi cac duong Cu, hkt, Nn, hmin,van min. trong vung nay dco thuongh hdong co cac che do nho tai nhu khi khoi dong dco, khi tau chay trong luong lach, haoc dco qua cu

- Vung2: dc gioi han boi cac duong: Cu, hn, nn, hkt. Day la vung the hien kha nang va csuat toi uu cua dco. Khthac vung nay se cho hieu qua kte cao nhat. Thong thuong chi khi dco con moi, dk kthac thuan loi

- Vung3: dc gioi han boi cac duong: Cu, hmax, nmax,hn. The hien khnang phat ra csuat lon nhat. Vung nay chi kthac khi thu tau, va trong cac truong hop can thiet: tranh bao, giay can...

Khi dco qua cu thin en kthac o vung 1. Vi khi dco cang cu this u lviec cau cac hthong nhu: nhien lieu, boi tron lam mat... hthong nap,xa se lviec kem. Ngoai ra voi nhieu nam kthac se lam cho vat lei che tao xuat hien ung suat vamoi. Neu kthac dco o vung 2 se ko kinh te vi suat tieu hao nhien lieu lon ma dco ko phat ra dc csuat nhu mong muon va dco de bi ung suat co va ung suat nhiet

Cau3: neu trong qua trinh kthac ta do dc cac tso: csuat, vquay, van toc tau ta co the xdung dc do thi dac tinh csuat dco ko?

Trong qtrinh kthac ta do dc cac tso: csuat,vquay, van toc cua taut hi ta co the xd dc do thi dac tinh cong suat cua dco dua vao phtrinh dac tinh ngoai: N-a.n va Phuong trinh dac tinh chan vit: Ne=c.n³

Trong do : c la he so luc can, n la vquay. Do vay khi co 1 gia tri vong quay ta se co mot gia tri cong suat: N1=a.n1> a=N1/n1 ma N=a.n vi vay Phuong trinh dac tinh ngoai la: N=N1.n/n1. Khi do cac gia tri n khac nhau ta tim dc cac gia tri cua N khac nhau. Va Ne=c.n1³ ma c ko doi nen moi gia tri khac nhau cua n ta se co cac gia tri khac nhau cua Ne. vay khi biet van toc V1, vquay n thi ta biet dc Ne tren do thi N-V.

Cau4: neu cac pp xdinh tuieu hao nhlieu trong kthac?

Tl: lap ke hoach chuyen di(so ngay chay, lam hang, neo, cho hang...)va luong tieu hoa nhien lieu dinh muc cau tung thiet bi, tu do tinh dc so gio lam viec cua tung tbi:

1. Tinh tieu hao nhien lieu cho 1 ngay dem:

G24=Gn[(1/1-0,25(T/To - 1)]x[(n/n)³.t1 + K2.t2] + C.[K3.t3 + k4.t4](kg)

Trong do: Gn tieu hao nhien lieu dinh muc cua he dong luc tinh bang kg/g/ T: trong luong hang chuyen cho tinh bang tan/To: trong luong theo thiet ke//.no,n: la vquay dinh muc va thuc te cau dco//t1: tgian lam viec cau may tinh tu luc lviec on dinh// t2: tgian lv cua may tu luck dong den luc tang toc// t3: tgian tau do ben co can cau lv//t4: tgian tau do ben ko co can cau lviec//k2: hso tinh toan tuong khi may kdong va tang toc// k3:hso tinh toan tuong ung khi cac can cau lv//t4: hs tinh toan khi cac can cau ko lv//c:hso dac trung cho mua

2. Tinh luong nhien lieu cho 1chuyen di khep kin:

B=G9t+t1.φ1+t2.φ2.n)+G1.t'1.φ'1 + G2.t'2.φ'2+..(tan). Trong do G1,G2,G3: luong tieu hao nhien lieu dinh muc cua may chinh va cac may phu.//t,φ: tgian va hso sdung cong suat cua M/E khi lviec on dinh// t1,φ1: tgian v ahs sd csuat khi M/E mano// t2,φ2: tg v ahs sd csuat khi M/E kdong//n: so lank dong//t1,φ'1,t'2,φ'2,t'3,φ'3: la tgian v ahs sd csuat cua cac may phu.

3. Tinh luong nhien lieu theo ty trong va quang duong 1000tan/1km: B=100(1+k)ge.φ.Ne/w.α.β.v (kg)

Trong do: ge: suat tieu hao nhien lieu dinh muc//φ: hs sd csuat khi tau hanh trinh//α: hs sd trong tai khi tau hanh trinh//β: hs sd quang duong//w: hs suc cho thiet ke trend vi(tan/maluc)//k: hs tinh den anh huong cua cac dkien khthac(khi hau, tgian lviec, chieu sau luong lach)

4. Tinh tieu hao nhien lieu theo ket qua de tai cua bo GTVT ap dung cho cty VOSCO: G∆=Gn-Gtt. Trong do Gn: tieu hao nhien lieu dinh muc/ Gtt tieu hao nhien lieu thcu te tinh toan. Khi ∆G.G: bieu thi su tiet kiem nhien lieu.

Cau5: neu nhung uu nhuoc diem cua truyen dong truc tiep, gian tiep?

1. Truyen dong truc tiep:la cvit dc noi truc tiep voi dco ko qua 1tbi trung gian nao ngoai tru cac duong truc: Np=Ne.ȵtrd-ȵe(trong do ȵtrd=1)

Uu diem: ton that truyen dong nho~1. Ket cau don gian truc ngan nen de van hanh khthac, it hong hoc, chi phi khthac, bduong schua nho.

Nhuoc diem: kho khan trong viec mano dieu dong

2. Truyen dong gian tiep: cv noi voi dc qua hop so, bo ly hop, hop giam toc va cac dg truc: Np=Ne.ȵtrd.ȵe - i.ne(I ty so truyen).

Pham vi ap dung: dco cao toc, co csuat vua van ho, dung cho tau kthac o nhieu che do(dan khoan, tau danh ca, tau cong trinh)

Uu diem: co the thay doi toc do va ca chieu quay cvit nhanh chong ma ko can thay doi toc do va chieu dco nen thaun tien trong mano dieu dong/co the thay doi ty so truyen de dam bao khthac dco o che do toi uu/ co the cat tai khi kdong cai thien dang ke che do kdong

Nhuoc diem: ton that truyen dong lon/ ket cau phuc tap, nguoi van hanh kthac pahi co trinh do/ hay hong hoc, chi phi bduong, schua cao

Khi khthac he truc cvit co kieu lam kin dang "SIMPLEX"thi can chhu y nhung diem sau:

- Muc dau o ket cap vao boi tron cho ong bao truc chan vit

- Muc dau, nhiet do o ket dau boi tron cho bo "SIMPLEX"

Cau6: nhung luu y khi khthac he dong luc co gia tai may phat dien dong truc:

- May phat dong truc chi dc dua vao khthac o che do on dinh(cac tso dco da on dinh o che do chay bien ko tranh va, bien yen song gio)

- Canh bao cho sy quan boong biet rang dnag dung may phat dong truc

- Phai luon co 1may phat do diesel dco lap lai o che do san sang tu dong kdong va hoa vao mang khi co su co voi may chinh hoac may path dong truc

- Ngat may phat dong truck hi dua may chinh vao che do ma no

Cau7: lam the nao de biet dc dco diesel dang lv voi cs phat ra o cac xilanh ko deu nhau? Cho biet cach can bang cong suat cac xilanh

Nhung dau hieu chung to cong suat phat ra o cac xilanh ko deu nhau"

- Vi tri thanh rang nhien lieu khac nhau nhieu

- Goc phun som cua cac xilanh khac nhau

- Do chenh nhiet do khi xa va nhiet do nuoc lm giau cac xilanh lon va khac nhua nhieu so voi che do kthac truoc day

- Vong quay dco hoi dao dong mac du yen song gio

- Do Pc,Pz thay khac nhau nhieu so voi ca clan do truoc

Anh huong cua su chenh lech Tkx, Pc,Pz giua cac xilanh den dco: khi cac tso tren chenh lech nhau se lam cho dco lv ko deu, luc tac dung len truc co ko deu gay ra ung suat uon truc, xoan truc dco lv rung dong. Momen cua cac ctiet chuyen dong ko deu, cac o do, be do chiu nhung luck o deu se gay hu hong. Su chenh lech nhiet do khi xa cua cac xilanh co the gay ra ung suat nhiet.

Can bang cong suat giua cac xilanh:

- Tao su dong deu thong so cuoi qtrinh nen bang cach: dbao khe ho piston-xecmang-somi, vsinh cac cua nap, can chinh dung pha phan phoi khi

- Dam bao dong deu qua trinh cap nhien lieu: tinh trang kthuat cac BCA, vi tri thanh rang, apsuat va chat luong cua voi phun, goc phun va do maim on donmg deu bien dang cac cam nhien lieu.

Cau8: truong hop phai cat dau or treo BCA cho 1 hoac2 xilanh thi che do lv dco phai thiet lap ntnao?

Khi cat dau or treo BCA cua 1or 2 xilanh dco xay ra cac hien tuong sau:

- Csuat, vquay dco giam mac du tay ga vna giu nguyen. Voi dco co BDT thi de gay ra hien tuong qua tai o cac xilanh con lai

- Su mat can bang trong 1 chu ky sinh cong gay ra luc tac dung ko deu len truc khuyu, gay rung dong cho dc ova vo tau

- Gian doan luu luong khi xa gay anh huong lon choc ac dco co tuabin kieu xung ap

Trong truong hop nay co the xem dac tinh Nm ko thay doi so voi ban dau va co the xd Ne'

Ne'= N1'-Nm trong do Ni'= (i-1).N1/i

Minh hoa tren dothi N-n ac dac tinh Ne,N1,Nm, Ne', N1'

De dam b ao kthac an toan thi phai giam tay ga nhien lieu. Diem khai thac moi se phu thuoc vao ty so xilanh lam viec va bi cat, su rung dong cau dong co va hdong cua tuabin tang ap.

Cau9: trong truong hop tuabin tang ap dco bi hong thi che do dco phai dc thiet lap ntn?

Khi to hop tuabin-maynen bi hong thi se gay anh huong den qua trinh cong tac cau dco:

- Luong kk nap se bi giam dang kelam cho he so du luong kk α giam qua trinh chay xau di, anh huong xau den cac tso ctac cua dco

- Chat luong qua trtinh quet giam, hso khi sot tang, o dco 2ky quet vong co the ko thcu hien dc qua trinh trao doi khi

- Suc can va phan ap xa tang len dang ke

Thiet lap che do khai thac khi tuabin su co:

- Dung may de co dinh or tut roto(bit ngan cach 2khoang may ne va tuabin)

- Mo tat cho kk khi nap ko phai qua sinh han gio tang ap

- Chay may nen co khi neu dco co trang bi

Minh hoa tren do thi N-n diem phoi hop cong tack hi chua xay ra su co va khi xay ra su co.

Cau10: hay cho biet muc dich thu tau tai ben va thu tau duong dai. Gia tri cong suat lon nhat co the sdung trong 2truong hop nay la bao nhieu?

Muc dich cuaviec thu tau tai ben de ktra su lap rap dco, su hdong cua cac he thong phuc vu, ht dg truc... de chuan bi khau tiep theo la thu tau duong dai. Co dang kiem giam sat

- tso thu nu=(0.50-0.65)nn va Nu=(0.30-0.45)Nn

- Thoi gian thu ko qua 10h

Muc dich cau viec thu hanh trinh: trong chuyen hanh trinh dau tien sau ha thuy dong moi hay schau lon phai thu tau duong dai nham danh gia kha nang di bien cua con tau. d/v bo phan may thuong bao gom: ktra kha nang tang toc sao khoang tgian nhat dinh, kha nang dao chieu trong truong hop su co(tu het may tien sang het may lui va nguoc lai)kha nang be lai trong khoang tgian cho phep, theo doi tinh nang hdong va do tin cay cua tat ca trthiet bi, ht buong may. Co ky thuat vien giam sat. tso thu: nv=nmin den nn/ va No=(0.85-0.90)Nn

Cau11: khi hanh trinh trong song or luong lach hep van toc luon phai thay doi. Khi phu tai cua dco co thay doi ko?visao?

Khi tua hanh trinh trong song, luong lach can suc can cua than tau chuyen dong trong nuoc tang len do:

- Tac dung dong chay cua ban than luong lach

- Tac dung cau dong chay roi cua lop nuoc xung quanh than tau

- Han che kha nang dap nuoc cua chan vit

Trong dieu kien nay dco thuong kthac o vong quay thap. Neu nhu can phai tang toc do taut hi can phai gia tang mot luong cong suat dieu nay dan den dco hay bi qua tai ve nhiet va co

Cau12: hay neu pp co the lam giam suc can va phan ap cho dco trong qua trinh khai thac?

1. Trong khai thac suc can tren duong ong nap thuong gay ra boi: ban phin loc gio, may nen , khoang gio quet, cac van 1chieu o cua nap(dco2ky)or bi tac ban cac hoc xupap nap, pha nap bi thay doi(dco 4ky)

- Tac hai: lam giam luong kk nap, α giam anh huong toi qua trinh chay. Csuat dco giam, cac tso cong tac xau di

- Khac phuc: dinh ky ve sinh ktra va chinh pha phoi khi

2. Trong khai thac phan ap tren duong ong xa thuong gay ra boi: tac ban cau thai cac hoc xupap xa, tuabin, noi hoi kinh te or pha thai bi thay doi, hoac cac tbi tan dung nhiet bi hu hong

- Tac hai: lam tang luong khi sot chiem cho va gian no vi nhiet, lam giam luong kk nap, thieu oxy dan den chay rot, chay ko het nhien lieu, chay tren duong gay hu hong thoi xupap, hu hong cac tbi tan dung nhiet. Tham chi khi xa co the bi thoi nguoc ve cua nap gay chay khoang gio quet, chay cac van 1chieu

- Khac phuc: dinh ky vsinh nhat la tuabin va noi hoi kinh te, ktra va chinh pha phoi khi

Cau13: khi tang cao nhiet do nuoc lam mat dco(trong gioi han cho phep)thi co the cai thien dc cac tso ctac. Vi sao?

Uu diem khi tang cao nhiet do nuoc lam mat trong gioi han cho phep:

- Giam nhiet luong truyen cho nuoc lam mat nhat la o xung quanh buong dot do do tso chi thi dco tot len

- Cai thien che do khoi dong

- Giam cong chi phi co gioi nen lam tang cong suat co ich

- Giam ung suat nhiet cho cac chi tiet buong chay

- Tang nhiet do cuoi qua trinh nen, giam thoi gian tri hoan chay dco chay mem hon, tso chi thi tot len

- Kha nang tan dung nguon nhiet nuoc lam mat mang ra(may chung cat)

Nhuoc diem: tang nhiet do kk nap lam giam trong luong rieng hay hay giam luong oxy can cho qua trinh chay, hieu suat chi thi giam

Noi chung khi tang T nuoc lm thi lam tang cac tso chi thi cua dc ova tang kha nang tan dung nguon nhiet cua nuoc lam mat mang ra.

Cau14: hay cho biet cach xdinh nhiet do khi xa cua dco trong cac dieun kien khai thac khac nhau(theo dac tinh chan vit va phu tai)

- Khi dco lviec theo dac tinh cvit(dco lai cv): Tkx=Tkxⁿ.(n/nn)ͫ¹

- Voi dco 4ky ko tang ap: m1=2,05

- Voi dco 4ky co tang ap: m1=1,80

- Voi dco 2ky co tang ap: m1=1.40

Khi dco lviec o che do phu tai(n=const)

Tkx=Tkxⁿ.(a+b.Ne?Neⁿ) void co tang ap: a=0,07; b=0,93; m= -0,68

Voi dco ko tang ap: a=0,12; b= 0,88; m= -0,95

Cau15: tsao can tan dung nang luong thai tren tau? Luu y khi tan dung nhiet khi xa cua dco diesel?

Tan dung nguon nag luong thai tren tau nahm nang coa hieu suat toan bo HDL tao ra nguon nhiet phuc vu ham say or nguon nuoc phuc vu sinh hoat ma ko ton them nguyen nhien lieu, tham chi o cac tau co HDL cuong saut lon co the bien doi nang luong thai de tao ra nang luong dien phuc vu cho con tau, or dung tuabin khi xa quay lai cap nang luong cho chan vit

Cac nguon nhiet co the tan dung:

- Nguon nhiet tu khi xa: tan dung de lai tuabin tang ap cho dco, ham say sinh hoi o noi hoi kinh te

- Nguon nhiet tu nuoc lam mat: chung cat nuoc sinh hoat tu nuoc bien

- Nguon nhiet tu khi tang ap: ham nuoc cap noi hoi

Nhung luu y khi tan dung nguon nhiet tu khi xa:

- Gay phan ap tren duong xa, nhat la che do khoi dong

- Hien tuong an mon diem suong o cac tbi tan dung nhiet cuoi duong xa.

Cau16: ung suat co cua dco diesel la gi? Can cu vao dau de biet dco dang lv voi ung suat co qua muc cho phep? Neu pp xu ly

Ung suat co cua dco dc dac trung bang gia tri va su thay doi cua ung suat, bang su bien dang, su tang ap suat rieng trong cac ctiet, cac co cau dong, cac khau lien ket cua dco. Kha nang lam viec cua cac ctiet cac o do, su maim on su xuat hien moi cua vat lieu deu phu thuoc vao chi tieu ung suat co.

De do dc ung suat , su bien dang cau cac ctiet, ap suat rieng gap nhieu kho khan. Trong khai thac nguoi ta ktra gian tiep thong qua cac tso kthac, cac tso do phan anh chinh xac ung suat co trong dco. Cac tso do la: luck hi chay trong xilanh, luc quan tinh, momen quan tinh cua cac khoi chuyen dong. Cac tso phan anh la:

- Ap suat chay cuc dai Pz

- Ty so tang ap suat λ=Pz/Pc

- Toc do tang ap trung binh: ∆P/∆φ

- Vong quay cua dco : n

- Muc do dao dong cua dco

De biet dc dco dang lam viec voi ung suat co qua muc cho phep can cu vao:

- Ap suat khi chay cuc dai Pz

- Nhiet do khxa: Tkx

- Vong quay dco

- Su lam viec ko dong deu giua cac xilanh cua dco co the gay nen hien tuong moi, xoan truc do luck hi chay tac dung len truc khuyu ko deu nhaulam cho ddco lv rung dong

- Toc do tang ap suat khi chay trung binh ∆P/∆φ lon

Bien phap xu ly:

- Dieu chinh thoi diem cap nhien lieu va luong nhlieu cap vao moi chu trinh cua dco cho phu hop

- Giam vong quay dco

- Dieu chinh luong nhien lieu cho moi xilanh deu nhau

Cau17: can bang csuat cho cac xilanh trend co ntn? Tai sao ko can chinh csuat dco o che do phu tai nho?

Can bang cs choc ac xilanh cua dco;

Dua vao asuat Pz, nhiet do kxa cua cac xilanh de danh gia su lv dong deu giua cac xilanh va de csuat phat ra cua cac xilanh tuong duong nhau can can bang csuat choc ac xilanh:

- Dam bao cho bo hoi cua cac xilanh phai tot, dieu chin hap luc BCA, voi phun cho dat ycau cho tat ca cac xilanh

- Cho dco hdong voi vong quay khai thac sau 1-2h, ktra apsuat khi chay Pz, nhiet do khi xa tung xialnh xem co deu nhau ko. Neu ko deu thi dieu chinh luong nhien lieu cap vao tung xi lanh sao cho phu hop.

Ko nen can chinh csuat dco o che do phu tai nho vi:

- Day la che do dco lv voi tgian ngan

- O che do nay cac tso: Pc,Pz, Tkx, Tlm, Tdn, Ptap ko on dinh la do: thay doi luong nhien lieu cap vao cho xilanh thay doi lien tuc, ap luc gio tang ap giam, phan ap tren dg xa- nap.