Tai Lieu Mon Hoc Ky Thuat Dong Co Su Dung Nhien Lieu Moi (Repaired)

1

Mc lc

CHNG 1: C IM CC LOI NHIN LIU THAY TH ................................... 4

1.1. Mt s thng s c trng ca nhin liu ng c t trong.............................. 4

1.1.1. Ch s cetan. ................................................................................................. 4

1.1.2. Ch s octan. ................................................................................................. 4

1.1.3. Nhit tr ca nhin liu. ................................................................................ 4

1.2. Nhin liu c ngun gc du m ........................................................................ 4

1.2.1. Nhin liu LPG ............................................................................................ 4

1.2.2. Nhin liu CNG ......................................................................................... 10

1.3. Nhin liu c ngun gc sinh hc ..................................................................... 12

1.3.1. Nhin liu biogas ....................................................................................... 12

1.3.2. Nhin liu biodiesel ................................................................................... 19

1.3.3. Nhin liu Ethanol ..................................................................................... 20

CHNG 2: NG C S DNG NHIN LIU LPG-CNG ...................................... 32

2.1. c im chung ca ng c dng nhin liu LPG: ........................................ 32

2.1.1. Momen, cng sut ng c. ....................................................................... 32

2.1.2. Sut tiu hao nhin liu. ............................................................................. 32

2.1.3. Mc pht nhim. ................................................................................ 32

2.1.4. Tnh an ton v tui th ng c. .............................................................. 33

2.2. Phng n cung cp nhin liu LPG cho ng c ............................................ 33

2.2.1. Cung cp nhin liu LPG dng kh dng b ch ha kh .......................... 34

2.2.2. Cung cp nhin liu LPG dng phun nhin liu ........................................ 38

2.3. Cc phng n iu khin cung cp LPG ......................................................... 40

2.3.1. H thng c hc, iu khin in .............................................................. 40

2.3.2. H thng c hc, iu khin in t v cht xc tc. ................................ 41

2.3.3. H thng phun LPG iu khin in t ..................................................... 42

2.3.4. Phun theo chu k c lp ........................................................................... 43

2

2.4. c im kt cu phng n cung cp LPG cho xe my ................................. 43

2.4.1. H thng nhin liu cho xe gn my ch s dng LPG ............................. 44

2.4.2. H thng nhin liu cho xe gn my s dng hai nhin liu (LPG/xng): 46

2.5. c im kt cu phng n cung cp LPG cho t dng hng Ventury ....... 48

2.5.1. S nguyn l ......................................................................................... 48

2.5.2. Cc cm chi tit chnh ................................................................................ 49

2.6. c im kt cu phng n cung cp LPG dng h thng phun iu khin

in t ............................................................................................................................ 54

2.6.1. S nguyn l ......................................................................................... 54

2.6.2. Nguyn l iu khin ................................................................................. 55

2.6.3. Cc chi tit chnh ........................................................................................ 56

2.7. c im kt cu phng n phun CNG iu khin in t ............................ 62

2.7.1. S nguyn l ......................................................................................... 62

2.7.2. Cc cm chi tit chnh ................................................................................ 62

CHNG 3: NG C S DNG NHIN LIU BIOGAS ........................................ 66

3.1. c im ca ng c tnh ti chy bng biogas .............................................. 66

3.2. Cc phng n cung cp biogas cho ng c tnh ti ....................................... 66

3.2.1. Van tit lu c kh ...................................................................................... 66

3.2.2. Van cng sut kiu chn khng ................................................................. 68

3.2.3. H thng hai van chn khng ..................................................................... 69

3.2.4. H thng ba van chc nng vi van lm m kiu c kh ......................... 70

3.2.5. H thng biogas/xng c lp vi b iu tc in t ............................... 71

3.2.6. H thng phi hp xng/biogas vi b iu tc in t ............................ 72

3.2.7. H thng xng/biogas c lp vi van lm m kt hp van cng sut. ... 73

CHNG 4: TNH TON H THNG CUNG CP NHIN LIU DNG NHIN

LIU KH BIOGAS .......................................................................................................... 74

4.1. Tnh ton chu trnh nhit ng c khi s dng lng nhin liu (diesel +

biogas) vi cc % nng lng diesel lm mi ............................................................... 74

4.2. Thit k, tnh ton phng n cung cp biogas cho ng c. ........................... 84

4.2.1. S h thng ........................................................................................... 84

3

4.2.2. Thit k, b tr, tnh ton b ha trn. ....................................................... 84

4.2.3. Thit k, tnh ton van tit lu Biogas. ...................................................... 95

4.2.4. Cc phng n thit k b iu tc biogas .............................................. 100

CHNG 5: TNH TON H THNG CUNG CP NHIN LIU DNG

CN ................................................................................................................................. 110

5.1. Tnh ton nhit khi s dng hn hp cn v xng .......................................... 110

5.1.1. Qu trnh np. ........................................................................................... 110

5.1.2. Qa trnh nn ............................................................................................ 111

5.1.3. Qu trnh chy .......................................................................................... 113

5.1.4. Qu trnh gin n. .................................................................................... 114

5.1.5. Tnh ton cc thng s ca chu trnh cng tc. ........................................ 114

5.1.6. Cc ch tiu c ch. ................................................................................... 115

5.1.7. Kim nghim cng sut ca ng c ....................................................... 115

5.2. Cc phng n dng cn trn xe my ............................................................. 115

5.2.1. ng c xng chy hon ton bng cn .................................................. 116

5.2.2. ng c xng chy bng hn hp cn-xng ............................................ 116

5.3. Tnh ton cc thng s c bn ca B ch ha kh khi dng hn hp cn xng.

..................................................................................................................................... 132

5.3.1. Tnh cc thng s ti hng b ch ha kh ............................................... 132

5.3.2. Tnh cc thng s ca gc l .................................................................... 133

4

CHNG 1: C IM CC LOI NHIN LIU THAY TH

1.1. Mt s thng s c trng ca nhin liu ng c t trong.

1.1.1. Ch s cetan.

S cetan ca nhin liu l s phn trm tnh theo th tch ca cht cetan c trong 1

hn hp nhn to gm cetan vi cht anphamtin naptalin, ni ln kh nng t bc chy

ca nhin liu. Hn hp ny c ch s nn gii hn ging nh ca nhin liu th nghim.

Vic chn la hn hp mu c tin hnh trong cng mt ng c dng xc nh

t s nn i vi nhin liu lm th nghim.

Cetan l cacbua-hydro loi paraphin thng dng C16H34 m s cetan cht ny l

100.

Anphamtin naptalin l mt loi cacbua-hydro thm hai vng c cha nhm mtin

trn ln vi cc nguyn t hydro ( -C10H7CH3), y l mt cht kh bc chy, ngi ta ly s cetan ca cht ny bng 0.

1.1.2. Ch s octan.

Tnh chng kch n l mt trong nhng ch tiu quan trng nh gi cht lng ca

nhin liu ng c t chy cng bc. Khi dng loi nhin liu c tnh chng kch n

khng thch hp vi t s nn, kt cu ca ng c,.v.v..th qu trnh chy trong ng c

s b ph hoi v dn n chy kch n. Tnh chng kch n ca nhin liu c lin quan

cht ch vi tnh t chy ca nhin liu, n ph thuc vo thnh phn ca nhin liu.

Mt trong nhng phng php nh gi tnh chng kch n ca nhin liu c

dng rng ri l ch s octan.

S octan ca nhin liu l s phn trm izo-octan C8H18 tnh theo th tch trong hn

hp vi cht heptan C7H16 tng ng v tnh kch n vi nhin liu th nghim.

Cht izo-octan c dng trong hn hp chun vi tr s octan l 100 cn cht thnh

phn th hai ca hn hp chun l cht heptan, vi s octan coi nh l 0.

1.1.3. Nhit tr ca nhin liu.

Nhit tr l mt c tnh ph bin v rt chung ca nhin liu, n xc nh gi tr

nhin liu dng cho tt c cc loi ng c nhit v cc thit b ng lc khc.

1.2. Nhin liu c ngun gc du m

1.2.1. Nhin liu LPG

1. Tnh cht l ho ca LPG

5

a. Thnh phn ha hc

Kh ha lng LPG l sn phm thu c t qu trnh chng ct du v tinh luyn kh

thin nhin. Thnh phn ch yu l C3H8 (Propan) v C4H10 (Butan) c nn theo t

l phn trm Propan trn phn trm Butan.

nhit v p sut kh quyn LPG dng kh. thun tin v tn cha v vn

chuyn LPG c ha lng. Trong thc t thnh phn hn hp cc cht c trong kh ha

lng LPG khng thng nht. Ty theo tiu chun ca cc nc, khu vc m t l thnh

phn trong LPG khc nhau, c t l gia Propan v Butan l 50/50 hay 30/70. Chu ,

thnh phn nhin liu kh ha lng kh n nh, cha ch yu l Hydrocacbon C4, chng

hn nh Hn Quc ch c Butan l kh ha lng c s dng ph bin. Ngc li

M th ch c Hydrocacbon C3 c s dng.

c bit trong thnh phn kh ha lng LPG cha rt t lu hunh. thng ch cha

(40 60) ppm, thp hn nhiu so vi tiu chun, cho php ca cng ng Chu u (200ppm) mt tiu chun kht khe nht v cc cht ph gia c trong nhin liu. Do ,

ng c dng LPG pht ra rt t cc cht nhim gc lu hunh v hiu qu ca b lc

xc tc c ci thin.

b. Cc tnh cht ca LPG

Do thnh phn ch yu ca LPG l Propane v Butane nn tnh cht ca LPG l tnh

cht ca Propane v Butane.

LPG c c tnh sau:

- L mt cht lng khng mu (trong sut).

- L mt cht lng khng mi, khng v, tuy nhin trong thc t trong qu trnh ch

bin c pha thm Ethyt Mecaptan c mi c trng d pht hin r r. Nng mi

phi nhn ra trc khi chng to thnh hn hp n.

- Bn thn LPG khng c, khng gy nhim mi trng, khng nh hng n

thc phm v sc khe con ngi, tuy nhin khng nn ht vo vi s lng ln, v c

th gy ngt th hay say do thiu xy.

- LPG nng hn khng kh (1,5 2) ln, nh hn nc 0,5 ln v vy nu thot ra ngoi hi LPG s lan truyn mt t v tp trung nhng phn thp nht, nh rnh, h

ga,...tuy nhin n s tn mt ngay khi c gi.

- LPG c tn cha trong cc loi b chu p lc khc nhau, chng tn ti trng

thi bo ho. Gas lng di, hi Gas pha trn theo quy nh an ton cc loi b cha

LPG ch c php nhp (80 85)% th tch, phn cn li m bo cho s gin n v nhit ca LPG.

6

- c trng ln ca LPG khc vi cc loi kh khc l chng tn ti dng bo ha

nn vi thnh phn khng i (70% Butan -30% Propan). p sut bo ha trong b cha

cng nh trong h thng khng ph thuc vo nhit bn ngoi. Thng thng Gas

Petrolimex c p sut 4,5 kg/cm2 7,8kg/cm2 nhit (15 30) 0C.

- LPG c t l gin n ln: mt n v th tch Gas lng bay hi to ra 250 n v th

tch hi, do vy LPG ch thun tin v kinh t khi vn chuyn v tn cha dng lng.

- LPG cn l nhin liu sch: Hm lng lu hunh thp (< 0,02%), khi chy ch to

ra CO2 v hi nc, khng to mui, khng to khi, c bit khng sinh ra kh SO2,

H2S, CO.

- LPG ho lng c nhit tr ring theo khi lng cao, cao hn c xng hay du Diesel

(Bng 1.1). Tuy nhin do khi lng ring ca n thp, nhit tr ring theo th tch thp

hn nhin liu lng khc [6].

Bng 1.1. So snh LPG v cc loi nhin liu c in.

Thng s c

trng

Eurosper Diesel Propane

thng

mi

Butane

thng

mi

LPG

Khi lng

ring (kg/dm3)

0,725

0,78

0,82

0,86

0,510 0,580 0,51

0,58

Nhit tr thp:

- Theo khi

lng (MJ/kg)

- Theo th tch

(MJ/dm3)

42,7

32,0

42,6

35,8

46,0

23,5

45,6

26,4

45,8

25,0

* Ch s Octan:

Nhin liu kh ha lng c c trng bi ch s octan nghin cu (RON) cao, c

th t ti 98. Bng 1.2 gii thiu RON ca cc loi kh khc nhau. Ch s octan ng c

(MON) ca LPG cng cao hn xng.

Bng 1.2 Ch s Octan ca mt s cht.

Cht RON MON

Propane

Propne

n -Butane

Isobutane

But -1 -ne

>100

102

95

>100

(98)

100

85

92

99

80

7

But -2 -ene 100 83

2. So snh tnh nng ca LPG v xng

Bng 1.3. So snh c tnh ca LPG v cc nhin liu khc.

c tnh n v Xng Diesel CNG LPG

Mu, mi

T trng

Nhit tr thp

H s A/F

Ch s Octan

Kg/m3

MJ/kg

C

750

42,9

14,4

85 98

C

860

42,6

14,5

Khng

550

50

17,26

115

Khng

555

46

15,5

110 120

Theo kt qu bng 1.3 ta thy nhit tr ca LPG cao hn xng v hn hn so vi cc

loi nhin liu truyn thng khc. LPG c ch s Octan cao hn nhng lng khng kh

l thuyt cn thit t chy mt n v th tch LPG cao hn xng. LPG d n hn

xng nhng tc chy chm hn xng. Do vy khi ng c lm vic tc cao ng

c s b mt cng sut t (5 8)%. iu ny khc phc bng cch chnh li thi im nh la (3 50), v v LPG c gi r hn nn thc t ngi ta c th chp nhn c. Nhng n c u vit l khng gian tn cha nh gn, lm cho vic vn chuyn c

thun li v kinh t hn. Chnh v nhng u im ca LPG so vi xng nn LPG v s

l loi kh t c ng dng rng ri trn th gii.

Nu LPG lng b r r ra ngoi th ti ch r c nhit thp v xut hin tuyt.

Ngoi ra, hm lng Propane trong thnh phn ca LPG cn quyt nh p sut hi

trong bnh cha LPG. Nu hm lng Propane cng ln th nhit tr cao, p sut hi cng

cao, c th s dng trit LPG trong bnh cha c bit trong iu kin nhit mi

trng thp. Khi s dng mt lu lng ln th bnh s h nhit nhanh, do nu loi

LPG ang s dng c thnh phn Propane thp th khi do p sut hi gim nhanh, lu

lng LPG cung cp c th khng p ng nhu cu s dng.

Hin nay, cc hng sn xut t nh Citroen, Deawoo, Fiat, Ford, Hyundai,

Opel/Vauxhall, Peugoet, Renault, Saab, Toyota v Volvo c nhng mu xe chy hai

nhin liu l LPG v xng. , xng v LPG c th dng thay phin nhau.

Mt s tnh cht ca nhin liu LPG so vi cc loi nhin liu khc c trnh by

trong bng 1.4.

8

Bng 1

.4.

Thnh p

hn t

h

tch

(%

) v

nhi

t tr

th

p

ca

nh

in

li

u k

h.

(i

u k

in

m3 t

iu c

hun c

p

= 7

60m

mH

g v

t

= 0

0C

)

Nh

it

ttr

th

p

Qm

(MJ/

m3 t

iu

chu

n)

34,8

- 3

5,6

30,1

5

41,3

0

68,1

2

62,9

1

57,2

5

16,7

48

3,9

77

6,4

15

5,1

92

4,6

81

* C

2H

4 -

4,5

% ;

C3H

6 -

7,5

% ;

C4H

8 -

6,0

% ;

CnH

m -

6,0

%

**

C2H

4 -

12

,5%

; C

3H

6 -

15%

; C

4H

8 -

6,0

% ;

CnH

m -

5,0

%

Thn

h p

hn

th

tch

O2

-

0,1

5

- - - - -

0,2

0,2

0,2

CO

2

0,0

5

0,7

5,0

0,7

10,4

- -

2,0

8,0

7,0

6,0

11,0

N2

1,3

4

4,4

4,4

0

11

- -

5,0

60,0

46,4

52,0

54,5

H2S

- -

0

2,8

- - - - -

0,2

-

H2

-

1,4

5

-

6,0

7,0

60,0

4,0

15,0

14,0

12,

CO

- - -

0,5

-

5,0

28

,0

28

,0

27

,0

20

,0

CnH

m

0,0

5

0,5

-

1,7

8

,1

24

,0*

38

,5**

3,0

-

0,4

-

0,3

Bu

tan

C4H

10

0,1

0

,6

-

2,7

1

,7

6,0

2,0

- - - -

Pr

pan

C3H

8

0,2

0

,6

3,2

2

0,5

15

,0

6,5

- - - - -

ta

n

C2H

6

0,5

0

,7

-

8,1

1

2

18

,0

14

,0

- - - - -

Mt

an

CH

4

93

,2

98

,3

89

42

,4

71

,9

30

,5

32

,0

25

,0

-

3,0

0,6

2,0

Loi

kh

+ k

h

thi

n n

hi

n

-M k

h

-Kh

b

n

ao

+ K

h

cn

g n

gh

ip

-Kh

d

u m

-Cra

ckin

g n

hi

n l

iu

ln

g

-Cra

ckin

g n

hi

n l

iu

kh

-Lu

yn

c

c

-L

cao

(luyn

gan

g)

+K

h

l g

a

-Th

an b

n

-Th

an

ng

trax

it

-C

i

9

3. Trm np LPG cho xe t:

H thng tn tr v np LPG cho xe t bao gm cc phn chnh: phn bn (hoc

bnh cha) LPG p sut cao, bm v cc thit b vn hnh, tr bm kt ni v bm

vo bn cha trong xe v tnh lng nhin liu bm vo trong xe.

H thng bn cha LPG thng l bn cha thp c dung tch thay i ty theo quy

m ca trm np LPG , thng thng l c sc cha t 2,5 tn n 15 tn. Bn c th t

ni trn mt t hay t chm di mt t. Nu bn t chm di mt t th c th

gim c cc khong cch an ton xung quanh khu vc bn cha. Bn c ch to

theo tiu chun v bn cha p lc ca Vit Nam v quc t.

Cc quy chun p dng cho h thng trm np LPG cho xe t bao gm nh sau:

TRM NP GAS CHO PHNG TIN GIAO THNG NG B

TCN 88:2005

Trm np nhin liu LPG cho cc

phng tin giao thng ng b -

Yu cu thit k, lp t v vn hnh

2005 B thng mi

BNH GAS

TCVN 6153 Bnh chu p lc yu cu k thut an

ton v thit k, kt cu, ch to 1996 B KHCN & Mi trng

TCVN 6154

Bnh chu p lc yu cu k thut an

ton v thit k, kt cu, phng php

th

1996 B KHCN & Mi trng

TCVN 6155 Bnh chu p lc yu cu k thut an

ton v lp t, s dng, sa cha 1996 B KHCN & Mi trng

TCVN 6156

Bnh chu p lc yu cu k thut an

ton v tp t, s dng, sa cha,

phng php th

1996 B KHCN & Mi trng

H thng bm v thit b vn hnh l cc loi thit b chuyn dng do cc nh sn

xut thit b trn th gii sn xut theo cc tiu chun nghim ngt v phng chng chy

n nh: NFPA 58, UL

Hnh 1.1 Hnh nh tr np LPG chung vi trm xng Hnh 1.2.Bn cha LPG t ngm di t

10

H thng tr bm LPG : c rt nhiu loi tr bm LPG s dng rng ri hin nay trn

th gii. Trong c loi thao tc bng tay bn t ng v loi t ng hon ton. D l

loi bn t ng hay t ng hon ton th qu trnh kt ni v thao tc bm phi do nhn

vin chuyn nghip c hun luyn an ton s dng nhm m bo mc an ton cao

trong qu trnh hot ng. Ring loi t ng hon ton c thit k nhm c th tnh

tin thng qua phng php khu tr trn cc loi th np sn, mua trc. Loi ny c

chi ph cao hn loi tnh tin th cng.

Hnh 1.3. Tr np LPG t ni trn mt t

1.2.2. Nhin liu CNG

1. c im

Kh thin nhin l kh c khai thc t cc m kh c sn trong t nhin. Thnh phn

ch yu: Metan (CH4) chim khong 80 90% ty thuc vo ngun khai thc, cn li l

cc hidrocacbon khc nh Etan, propan

2. Tnh cht

Bng 1.5. Tnh cht mt s kh thnh phn trong kh thin nhin

Thnh phn Phn trm th tch (%) Phn trm khi lng (%)

Mtan 92.29 84.37

tan 3.6 6.23

Propan 0.8 2.06

Butan 0.29 0.99

11

Pentan 0.13 0.53

Hexan 0.08 0.39

CO2 1 2.52

Nit 1.8 2.89

Nc 0.01 0.01

Tng cng 100 100

Kh thin nhin nn (CNG): Kh thin nhin c nn p sut cao, cc p sut

thng s dng l 165,5 bar (2400 psi), 206,9 bar (3000 psi), 248,2 bar (3600 psi) cha

trong cc bnh cha cao p mc song song. Cng mt nng lng nh nhau, kh thin

nhin ha lng LNG c th tch v khi lng bnh cha nh hn khi n dng kh CNG

(thng t l 1/3 i vi th tch v 1/3,7 vi khi lng).

CNG c th s dng trn ng c t trong (CT) thay cho nhin liu xng v

diesel, c th s dng c lp hay hn hp a nhin liu trn CT. Trong thc t, cc

ng c t trong hin nay u c thit k s dng nhin liu xng hay diesel, do

vic s dng nhin liu CNG cho CT th khng ph hp. c im chuyn i ng

c dng CNG: ng c diesel chuyn sang s dng hn hp nhin liu kh thin nhin v

diesel: t chy hn hp bng s t chy ca lng nhin liu diesel phun mi (t 5%

n 25% lng nhin liu nh mc).

CNG c nhit tr cao (50,5 MJ/kg), p sut nn cao (200kG/cm2) nn bnh cha gn,

qung ng chy mt ln np nhin liu ln. T trng ca CH4 nh bng 0,5 khng

kh. Do , khi b x hi CH4, khng ng li trn mt t m s bay trong khng kh.

Bng 1.6 So snh tnh cht mt s loi nhin liu

Xng Diezen LPG CNG

1.T trng (lng so vi nc)

T trng (so vi khng kh)

0,73

3,5

0,84 0,5-0,59

1,5-2

0,68

2. Nhit t chy,t0C 340 260 450-550 700

3. Ch s octan 96 - 110 130

4. Gii hn %V bc chy trong khng kh

nhit 250C:

- gii hn di

- gii hn trn

0,7

8,0

0,6

6,5

1,5

9,0

5,0

15

5.im si ti p sut thng t0c 30-220 175-

380

-42 -161

6. T l A/F:

- khi kng

- th tch

14,7

60

14,4

-

15,6

24

17,24

11

12

7. p sut bnh cha (Bar) 1 1 9-12 240

8. Hm lng lu hunh, %KL 0,1-

0,15

0,5-1 Khng

c

Khng

c

9. c hi ca sn vt chy cao cao Thp thp

10. Khi lng ring(Kg/lt),1bar, 15oC 0,74 0,84 0,019 0,00072

11. p sut cha (bar) 1 1 8 200

12. Nng lng (MJ/kg) 43,9 42,9 46,4 47,5

13. Khi lng ring p sut cha (Kg/lt) 0,74 0,84 0,51 0,18

14. Nng lng p sut cha (MJ/lt) 32,4 36,3 23,6 8,5

1.3. Nhin liu c ngun gc sinh hc

1.3.1. Nhin liu biogas

1. Kh biogas l g

Cng nh du thc vt, kh Biogas l nhin liu trung ha CO2 trong kh quyn.

Biogas l kt qu phn hu cc cht hu c trong mi trng thiu khng kh. Cc cht

hu c c th l thc vt (cy ci, rm r) hay ng vt (xc sinh vt, cc cht thi t

qu trnh ch bin thc phm), cc cht thi t qu trnh chn nui Qu trnh dip

lc ho ca thc vt di tc ng ca nh sng mt tri hp th kh CO2. Nu t

nhin liu c ngun t thc vt th CO2 trong kh thi s c cn bng.

Hai ngun biogas chnh l cc hm kh sinh hc v kh pht sinh t cc bi chn lp

rc trong qu trnh ln men him kh ca cc cht hu c. Biogas cha ch yu l CH4

(50-70%) v CO2 (22-50%) v cc tp cht khc nh H2S. Nu kh Biogas c lc sch

cc tp cht ny chng c tnh cht tng t nh kh thin nhin. Cc nc pht trin

hin nay (M, Php, c, an Mch) u s dng kh biogas t cc bi chn lp rc

sn xut in nng. Cng ngh sn xut biogas quy m gia nh c ph bin

rng ri cc nc ang pht trin, c bit l cc nc n v Trung Quc. nc

ta, cc d n sn xut in nng t kh biogas thu c t cc bi chn lp rc cng

c xy dng.

Bng 1.7.Thnh phn ch yu ca kh sinh hc

- Mtan (CH4): l cht kh khng mu,

khng mi, nh gn bng na khng kh v ha

tan trong nc rt t. p sut kh quyn, mtan

ha lng nhit -161,50C.

Mtan l thnh phn chy ch yu ca

kh sinh hc. Hm lng mtan trong kh sinh

hc ph thuc vo loi nguyn liu phn hy v

Thnh phn T l (%)

CH4 50-70

CO2 30-45

N2 0-3

H2 0-3

O2 0-3

H2S 0-3

13

s din bin ca cc qu trnh sinh hc .

Mtan chy thnh ngn la mu l nht, ta nhiu nhit:

CH4 + 2O2 CO2 + 2H2O + 882kJ

- Cacbonic (CO2): l cht kh khng chy, khng mu, khng mi, nng gp ri

ln khng kh. Nu kh ny chim t l cao trong kh sinh hc s lm cho cht lng kh

sinh hc km i.

- Hydro sulfit (H2S): c mi ca trng thi khin cho kh sinh hc cng tr nn

c mi hng, gip ta d dng nhn thy s c mt ca n. H2S l nguyn nhn ch yu

lm cho cc b phn bng kim loi ca h thng b n mn.

2. Cc tnh cht ca Biogas.

Bng 1.8. Mt s tnh cht ca CH4 v CO2

Cc tnh cht vt l Methane (CH4) Carbonic (CO2)

Trng lng phn t 16.04 44.01

T trng 0.554 1.52

im si 259.0 0F (=1440C) 60.80C

im ng -296.6 0F(-164.80C) -69.9 0F (-38.830C)

Khi lng ring 0.66kg/m3 1.82kg/m3

Nhit nguy him 116.0 0F

(=64.440C) 88.0 0F(=48.890C)

p sut nguy him 45.8 at 72.97at

Nhit dung Cp (1atm) 6.962.10-4 J/ kg-0C

T l Cp/Cv 1.307 1.303

Nhit chy 55.403J/kg

Gii hn chy 5-15% Th tch

T l chy hon ton trong khng kh 0.0947 Th tch

0.0581 Khi lng

Mtan tinh khit c nhit tr thp khong (8115.2 Kcal/m3). Do Biogas cha

khong 70-90% mtan nn nhit tr ca Biogas nm trong khong 5480 Kcal/m3.

3. Thit b sn xut kh biogas

sn xut kh biogas, ngi ta xy dng hoc ch to cc thit b KSH. Trong

thc t, hu ht cc thit b KSH c p dng cc nc ang pht trin l nhng thit

14

b n gin, hot ng theo ch np nguyn liu b sung thng xuyn hng ngy.

Cc thit b ny c 5 b phn chnh nh sau:

B phn phn hy: L ni cha

nguyn liu v m bo nhng iu

kin thun li cho qu trnh phn hy

k kh xy ra. y l b phn ch yu

ca thit b. Th tch phn hy ca thit

b l th tch ca b phn ny.

B phn cha kh: Kh sinh ra t

b phn phn hy c thu v cha

y. Yu cu c bn ca b phn ny l

phi kn. Th tch cha kh ca thit b

l th tch ca b phn ny.

Li vo: L ni np nguyn liu

b sung vo b phn hy.

Li ra: Nguyn liu sau khi

phn hy c ly ra qua y

nhng ch cho nguyn liu mi b

sung vo.

Li ly kh: Kh c a t b tch kh ti ni s dng qua li ly kh ny.

a. S sn xut biogas.

b. Nguyn l lm vic ca h thng

Phn ti t chung tri c a vo b lng ct (1) lng , ct ...ri qua ng

dn phn (2) vo b phn hu. b phn hu xy ra qu trnh ln men to kh sinh hc

nh sau:

Sau khi ln men hn hp kh Biogas c dn vo h thng lc kh H2S v CO2, hn

hp c lc cha phn trm H2S v CO2 nh, thnh phn trm CH4 chim khong 80%-

97,9% . Sau hn hp c dn vo bnh cha Biogas (6), cc cht b sau khi phn

hu c dn ra b cha cht thi(6) v c ti cho cy trng.

Hnh 1.4. S h thng sn xut Biogas.

1- B lng ct. 2-ng dn nguyn liu. 3-ng dn b

thi. 4- B ng cht thi. 5- H thng lc H2S v CO2. 6-

Bnh cha kh Biogas sch.

PHN TI

B PHN HUY

B AP SUT

GAS TI U

1

23

4

5 6

15

Hnh 1.5. S nguyn l to Biogas

c. Mt s loi hm kh sinh hc thng dng

c.1. Hm kh sinh hc np ni.

c.2. Thit b kh sinh hc np c nh.

c.3. Thit b kh sinh hc kiu ph bt

Cht bo.

Cc cht

tan

Hu cht bo.

Vi khun phn

Hydrat

cacbon

Vi khun phn

Hu Cenluloza

hu prtin

Prtin Vi khun phn

Vi khun + Axt hu c c

KLPT nh

+ CO2, H2

+ Ancol ...

sinh axt

Giai on

III.

Vi khun

sinh CH4

+ CH4

+ H2S,CO2

Giai on II. Giai on I.

Hnh 1.6. Hm kiu np ni

MT BNG B BIOGAS

MT CT A - A

AA

2

1

5

43

NG DN KH BIOGAS

H THOAT NC

H NAP NGUYN LIU

KHOANG CHA KH BIOGAS

B BIOGAS

54321 1

2

4

35

16

4. Nguyn liu sn xut kh biogas

a. Ngun nguyn liu

V mt l thuyt, mi cht hu c u c th b phn hy, tuy nhin trong thc t,

nguyn liu dng sn xut KSH c chia thnh hai loi: c ngun gc ng vt v c

ngun gc thc vt.

Nguyn liu c ngun gc ng vt: Phn ngi, phn gia sc v phn gia cm l

ph bin.V c x l trong b my tiu ha nn phn d phn hy v nhanh chng

cho kh sinh hc. Tuy vy, thi gian phn hy ca phn khng di (khong 2 3 thng)

v tng sn lng kh thu c t mt kilogam phn cng khng ln. Phn tru b v

phn ln phn hy nhanh hn, phn ngi v phn gia cm phn hy chm hn nhng

cho nng sut kh cao hn.

Nguyn liu c ngun gc thc vt: gm ph phm cy trng nh rm r, thn l

ng, khoai, u, v cc loi cy xanh hoang di nh bo, cc cy c sng di nc,

cc loi cy phn xanh,Cc loi nguyn liu ny c lp v cng rt kh b phn hy.

cho qu trnh phn hy k kh xy ra c thun li, nhng nguyn liu thc vt cn

Hnh 1.7 Hm np c nh Hnh 1.8 Hm ph ph bt

17

c x l trc (cht, bm nh v s b hiu kh) ph v lp v cng v tng din

tch b mt cho vi khun tn cng. Qu trnh phn hy ca nguyn liu thc vt di hn

so vi phn ng vt.

Bng 1.9 c tnh v sn lng kh c th thu c ca mt s nguyn liu thng gp

Loi nguyn

liu

Lng thi

hng ngy

(kg/con)

Hm lng cht

kh (%) t l C/N

Sn lng kh hng ngy

(l/kg nguyn liu ti)

Phn b 15 20 18 - 20 24 - 25 15 - 32

Phn Tru 18-25 16- 18 24 25 15 32

Phn ln 1,2 4 24 33 12 13 40 60

b. Cch np nguyn liu

Np tng m: Ton b nguyn liu c np y vo thit b mt ln, cho thm

cht mi vo v y kn li. Sau mt thi gian nguyn liu phn hy gn ht, ton b

nguyn liu c ly i ch cha li 10 20% lm cht mi v thay bng m nguyn

liu mi. Thi gian mi m thng ko di t 3 n 5, 6 thng. Thng thng cc

nguyn liu thc vt c np theo cch ny.

Np lin tc: Nguyn liu c np y lc mi a thit b vo hot ng. Sau

mt thi gian ngn nguyn liu c b sung thng xuyn. Khi mt phn nguyn

liu phn hy c ly i nhng ch cho phn nguyn liu mi np vo. Cch

np ny ph hp vi iu kin nguyn liu khng sn c ngay mt lc m c thu gom

hng ngy nh phn gia sc.

Trong thc t, nhiu khi ngi ta p dng c hai cch trn: nguyn liu thc vt c

np tng m, cn phn c np lin tc hng ngy.

5. ng dng ca kh biogas

a. un nu

S dng KSH un nu rt tin li: sch s, d s dng. Mi gia nh 4 5 ngi

ch cn xy mt cng trnh c 3 5 m3 vi 10 20 kg nguyn liu np hng ngy c th

thu c 300 500 lt kh un nu thc n v nc ung. Bp KSH gia nh thng

tiu th khong 200 lt kh/gi, t hiu sut 50 60 % (bng 1.9).

Bng 1.10. Lng cc cht t tng ng vi kh sinh hc khi dng un nu

Cht t n v Nhit tr (kcal) Loi bp Hiu sut (%) Lng

tng ng

Kh sinh hc m3 4.700 Bp KSH 60 1m3

18

Rm r kg 3.300 Bp king 11 8,60 kg

Ci kg 3.800 Bp king 17 4,83 kg

Than ci kg 6.900 Bp l 28 1,62 kg

Than cm kg 5.000 Bp l 28 2,01kg

Phn tru b kg 2.100 Bp king 11 12,21kg

Du ha lt 9.100 Bp bc 45 0,76 lt

in kWh 860 Bp in 70 5,18 kWh

Kh ha lng kg 10.900 Bp ga 60 0,48 kg

b. Thp sng

KSH chy cho ngn la xanh l nn khng pht sng. thp sng ngi ta dng

cc n mng (mng sng).

n mng tiu th khong 40 80 lt/gi cho nh sng hn bng n in 25W.

So vi n dng du ha, s dng KSH n gin hn (bng 1.11).

Bng 1.11. So snh n kh sinh hc v n du ha

S dng n KSH khng

nhng phc v sinh hot m cn

phc v sn xut. Trung

Quc, ngi ta dng n KSH

nui tm v chng i hi

nh sng v nhit thch hp.

Chiu sng bng n KSH lm

cho kn hnh thnh sm hn 4

6 ngy, cht lng kn tt hn, nng sut tng khong 30%.

c. Nhin liu cho ng c t trong

Cc loi ng c t trong dng xng hoc du u c th ci to dng KSH thay

th, hoc vn dng xng du nh c. Kh nng ng dng biogas chy ng c t

trong.

C th ni rng ng c t trong s dng Biogas t cc h thng x l rc thi thnh

ph c ng dng trn my chc nm nay v mang li nhng thnh cng nhiu

mc khc nhau. Trong nhng nm tr li y, cng ngh ny c ng dng rng

ri cho cc ngnh sn xut nng nghip v cng nghip di sc p ca vic khan him

nng lng ho thch trong tng lai. Cc ng c nh la cng bc c nh c th

Loi n Sut tiu th

(lt/gi)

Lng kh thay

th du (m3/lt)

n KSH 70.000

n mng du ha 0,125 1,79

n ta ng

Thng Long

0,050 0,72

19

cung cp nng lng cho rt nhiu loi thit b ti bao gm: My pht in, My bm,

My xay xt

Bng 1.12.Lng kh sinh

hc dng chy ng c

t trong

Ngoi ra, Biogas

cng l ngun nng

lng tim nng cung cp cho cc phng tin vn ti nh xe ca, xe ti cng nh cc

thit b cng nghip khc nh my koVic nh gi hiu qu ng dng ca cc h

thng ny s nhm mc ch ti u ho vic ng dng Biogas.

Do vy c th dng KSH pht in, bm nc, ch bin sn phm hoc chy t,

my ko (Bng 1.12).

d. B thi c th s dng lm phn hu c cho trng trt.

Cc cht hu c nh phn ng vt, cc loi cy xanh, sau khi phn hy sn xut

KSH li tr thnh mt loi phn hu c giu dinh dng. Cc nguyn t N, P, K ca

nguyn liu sau khi phn hy hu nh khng b tn tht m li chuyn ha sang dng

phn m cy trng d hp th. B thi ca thit b c phn lng v phn c, khi s dng

bn cy u cho nng sut tng.

6. Li ch ca cng ngh kh sinh hc

a. Li ch v mi trng:

Gim vic s dng nhin liu ha thch.

Gim cc kh gy hiu ng nh knh .

Ci thin v sinh trang tri v h gia nh.

Gim thiu nhim ngun nc t trang tri chn nui.

Cung cp phn bn hu c ci thin t trng trt.

b. Li ch v kinh t

Tit kim chi ph mua nng lng.

Tit kim chi ph mua phn bn.

Thu c quyn pht thi knh gy hiu ng nh knh.

1.3.2. Nhin liu biodiesel

1. c im:

Du thc vt c ngun gc t tt c cc ht, qu ca cc cy ci. Nhng t du thc

vt dng ch cc loi cy cha mt lng du vi chit sut ln nh da (60%), c

Mc ch s dng Lng kh tiu th

Chy ng c xng 0,40 0,50 m3/m lc

Chy ng c diesel 0,45 m3/m lc

Pht in 0,60 0,70 m3/kWh

20

(50%), du thc vt cng c th sn xut t cc ht ca cy ly du nh: ci du, u

phng, u nnh, ht hng dng

2. Tnh cht:

Tnh cht l ha ca mt s du thc vt tham kho theo bng 1.13.

Bng 1.13.Mt s tnh cht c bn ca cc loi du thc vt.

Loi du Khi lng

(g/cm3)

nht

(cst)

Nhit tr

(Mj/kg) Ch s Ctan

Du phng

Du ci

Du da

Du bng

Du c

Du u nnh

Du diesel

0,914

0,916

0,915

0,921

0,195

0,920

0,836

85

77

30 - 37

73

95 - 106

58 - 63

3 - 6

39,33

37.40

37,10

36,78

36,92

37,30

43,80

38 - 41

38

40 - 42

35 40

38 - 40

36 - 38

45 - 50

Biodiesel l ngun nguyn liu c th ti ch, gip gim s ph thuc vo du m bi

vy khi s dng n s lm gim lng kh thi, v biodiesel ch cha cha n 15 phn

triu sunfua, ngoi ra lng kh thi hydrocacbon v cacbonmonooxit (CO) s gim t l

thun vi t l biodiesel.

Mt trong nhng u im ln nht ca ca vic s dng biodiesel th hin ngay

ng c. Biodiesel oxy ha nhanh do c im thnh phn ha hc. Do , kh c th

tch tr loi nhin liu ny lu, cn phi c thm cc cht ph gia lu gi nhin liu

c lu hn v Biodiesel nguyn cht d b ng bng hay c li trong thi tit

lnh ( Vit Nam dng biodiesel c l s khng gp tnh trng ny). Ngoi ra, vic s

dng nhin liu cha nhiu hn 5% biodiesel c th gy cc vn sau:

+ n mn cc chi tit ca ng c v to cn trong bnh cha nhin liu do tnh d b

oxy ha ca biodiesel.

+ Lm h hi nhanh cc vng m cao su do s khng tng thch ca biodiesel vi

cht liu lm vng m. Ngy nay, vic sn xut biodiesel cn gp nhiu kh khn do gi

thnh cc sn phm nng nghip ch bin biodiesel cao, khng li v mt kinh t.

1.3.3. Nhin liu Ethanol

C hai loi cn thng dng: Methanol (CH3OH) v Ethanol (C2H5OH). C hai u c

th dng lm nhin liu. Methanol phn ln c sn xut t kh gaz thin nhin. Cn

ethanol c th sn xut t du m hay th phm ca nng nghip nh: ma ng, c ci

ng hoc l t cc cy c ht nh ng, la mch, la m, c sn. Eco-ethanol l bit

danh ca loi ethanol c gi thnh thp nht, lm t cellulose (rm r, b ma hay cnh

21

nhnh ca cy di) gi chung l th ethanol t bagasse. Ethanol sinh hc l t ch chung

cho cn ethanol khng phi sn xut t nhin liu ha thch. V mc sinh thi-mi

trng th cn ethanol sinh hc l loi nhin liu ti sinh c trong vnh kn tun hon:

trng cy ma, cy sn..v.v... cho cc nhin liu ch bin thnh cn, nhin liu cn khi

b t chy thi ra CO2 v CO2 li c cy ma, cy sn hp th.

Cy ci + CO2 --> Cn --> Nhin liu CT + CO2 --> Cy ci + CO2 -->

Ethanol c sn xut bng c cng nghip ha du, thng qua cng ngh hyrat ha

tylen v theo phng php sinh hc, bng cch ln men ng hay ng cc vi men

ru.

1. Cng ngh sn xut cn

a. Hyrat ha tylen:

Ethanol c s dng nh l nguyn liu

cng nghip v thng thng n c sn

xut t cc nguyn liu du m, ch yu l

thng qua phng php hyrat ha tylen

bng xc tc axt, c trnh by theo phn

ng ha hc:

H2C=CH2 + H2O CH3CH2OH

Cht xc tc thng thng l axt phtphoric, adsorbed trong cc cht c xp cao

chng hn nh iatomit (t cha to ct) hay than ci; cht xc tc ny ln u tin

c cng ty du m Shell s dng sn xut Ethanol mc cng nghip nm

1947. Cc cht xc tc rn, ch yu l cc loi xt kim loi khc nhau, cng c cp

ti trong cc sch v ha hc.

Trong cng ngh c, ln u tin c tin hnh mc cng nghip vo nm

1930 bi Union Carbide, nhng ngy nay gn nh b loi b th tylen u tin c

hyrat ha gin tip bng phn ng ca n vi axt sulfuric m c to ra tyl sulfat,

sau cht ny c thy phn to thnh Ethanol v ti to axt sulfuric:

H2C=CH2 + H2SO4 CH3CH2OSO3H

CH3CH2OSO3H + H2O CH3CH2OH + H2SO4

Ethanol s dng cng nghip thng thng l khng ph hp vi mc ch lm

ung cho con ngi ("bin tnh") do n c cha mt lng nh cc cht c th l c

hi (chng hn mEthanol) hay kh chu (chng hn denatonium- C21H29N2OC7H5O2-l

mt cht rt ng, gy t). Ethanol bin tnh c s UN l UN 1987 v Ethanol bin tnh

c hi c s l UN 1986.

b. Ln men:

Hnh 1.9. Cu trc phn t ca Ethanol

http://vi.wikipedia.org/w/index.php?title=C%C3%B4ng_nghi%E1%BB%87p_h%C3%B3a_d%E1%BA%A7u&action=edithttp://vi.wikipedia.org/w/index.php?title=%C3%8Atylen&action=edithttp://vi.wikipedia.org/w/index.php?title=Men_r%C6%B0%E1%BB%A3u&action=edithttp://vi.wikipedia.org/w/index.php?title=Men_r%C6%B0%E1%BB%A3u&action=edithttp://vi.wikipedia.org/wiki/Du_mhttp://vi.wikipedia.org/w/index.php?title=Ph%E1%BA%A3n_%E1%BB%A9ng_h%C3%B3a_h%E1%BB%8Dc&action=edithttp://vi.wikipedia.org/w/index.php?title=Ph%E1%BA%A3n_%E1%BB%A9ng_h%C3%B3a_h%E1%BB%8Dc&action=edithttp://vi.wikipedia.org/w/index.php?title=%C3%8Atylen&action=edithttp://vi.wikipedia.org/wiki/Nhttp://vi.wikipedia.org/w/index.php?title=Ax%C3%ADt_ph%E1%BB%91tphoric&action=edithttp://vi.wikipedia.org/w/index.php?title=Adsorption&action=edithttp://vi.wikipedia.org/w/index.php?title=%C4%90iatomit&action=edithttp://vi.wikipedia.org/w/index.php?title=Than_c%E1%BB%A7i&action=edithttp://vi.wikipedia.org/wiki/Axt_sulfurichttp://vi.wikipedia.org/w/index.php?title=%C3%8Atyl_sulfat&action=edithttp://vi.wikipedia.org/w/index.php?title=Th%E1%BB%A7y_ph%C3%A2n&action=edithttp://vi.wikipedia.org/w/index.php?title=%C3%8Atylen&action=edithttp://vi.wikipedia.org/wiki/Axt_sulfurichttp://vi.wikipedia.org/wiki/Nhttp://vi.wikipedia.org/wiki/Axt_sulfurichttp://vi.wikipedia.org/w/index.php?title=M%C3%AAtanol&action=edithttp://vi.wikipedia.org/w/index.php?title=Denatonium&action=edithttp://vi.wikipedia.org/w/index.php?title=S%E1%BB%91_UN&action=edithttp://vi.wikipedia.org/wiki/Hnh:Ethanol_-_Space_filling_model.png

22

Ethanol s dng trong ung cha cn cng nh phn ln Ethanol s dng

lm nhin liu, c sn xut bng cch ln men: khi mt s loi men ru nht nh

(quan trng nht l Saccharomyces cerevisiae) chuyn ha ng trong iu kin khng

c xy (gi l ym kh), chng sn xut ra Ethanol v cacbon ixt CO2. Phn ng ha

hc tng qut c th vit nh sau:

C6H12O6 2 CH3CH2OH + 2 CO2

Qu trnh nui cy men ru theo cc iu kin sn xut ru c gi l

ru. Men ru c th pht trin trong s hin din ca khong 20% ru, nhng nng

ca ru trong cc sn phm cui cng c th tng ln nh chng ct.

sn xut Ethanol t cc nguyn liu cha tinh bt nh ht ng cc th tinh bt

u tin phi c chuyn ha thnh ng. Trong vic men bia, theo truyn thng n

c to ra bng cch cho ht ny mm hay mch nha. Trong qu trnh ny mm, ht

to ra cc enzym c chc nng ph v tinh bt to ra ng. sn xut Ethanol lm

nhin liu, qu trnh thy phn ny ca tinh bt thnh glucoza c thc hin nhanh

chng hn bng cch x l ht vi axt sulfuric long, eym nm amylas, hay l t hp

ca c hai phng php.

V tim nng, glucoza ln men thnh Ethanol c th thu c t xenluloza.

Vic thc hin cng ngh ny c th gip chuyn ha mt loi cc ph thi v ph phm

nng nghip cha nhiu xenluloza, chng hn li ng, rm r hay mn ca thnh cc

ngun nng lng ti sinh. Cho n gn y th gi thnh ca cc enzym cellulas c th

thy phn xenluloza l rt cao. Hng Iogen Canada a vo vn hnh x nghip sn

xut Ethanol trn c s xenluloza u tin vo nm 2004.

Vi gi du m tng t nh cc mc gi ca nhng nm thp nin 1990 th cng

ngh hyrat hoa tylen l kinh t mt cch ng k hn so vi cng ngh ln men sn

xut Ethanol tinh khit. S tng cao ca gi du m trong thi gian gn y, cng vi s

khng n nh trong gi c nng phm theo tng nm lm cho vic d bo gi thnh

sn xut tng i ca cng ngh ln men v cng ngh ha du l rt kh.

c. Lm tinh khit:

i vi hn hp Ethanol v nc, im si hn hp (azeotrope) cc i nng

96% Ethanol v 4% nc. V l do ny, chng ct phn on hn hp Ethanol-nc

(cha t hn 96% Ethanol) khng th to ra Ethanol tinh khit hn 96%. V vy, 95%

Ethanol trong nc l dung mi ph bin nht.

Hai hng cnh tranh nhau c th s dng trong sn xut Ethanol tinh cht.

ph v im si hn hp nhm thc hin vic chng ct th mt lng nh benzen c th

thm vo v hn hp li c chng ct phn on mt ln na. Benzen to ra im si

hn hp cp ba vi nc v Ethanol nhm loi b Ethanol ra khi nc v im si hn

http://vi.wikipedia.org/w/index.php?title=Saccharomyces_cerevisiae&action=edithttp://vi.wikipedia.org/wiki/Chuyhttp://vi.wikipedia.org/w/index.php?title=Sacarit&action=edithttp://vi.wikipedia.org/wiki/xyhttp://vi.wikipedia.org/w/index.php?title=Y%E1%BA%BFm_kh%C3%AD&action=edithttp://vi.wikipedia.org/wiki/Cacbon_ixthttp://vi.wikipedia.org/w/index.php?title=Glucoza&action=edithttp://vi.wikipedia.org/wiki/Cacbon_ixthttp://vi.wikipedia.org/w/index.php?title=%E1%BB%A6_r%C6%B0%E1%BB%A3u&action=edithttp://vi.wikipedia.org/w/index.php?title=%E1%BB%A6_r%C6%B0%E1%BB%A3u&action=edithttp://vi.wikipedia.org/wiki/Chng_cthttp://vi.wikipedia.org/w/index.php?title=Tinh_b%E1%BB%99t&action=edithttp://vi.wikipedia.org/w/index.php?title=Ng%C5%A9_c%E1%BB%91c&action=edithttp://vi.wikipedia.org/wiki/Bia_(http://vi.wikipedia.org/w/index.php?title=M%E1%BA%A1ch_nha&action=edithttp://vi.wikipedia.org/w/index.php?title=Enzym&action=edithttp://vi.wikipedia.org/w/index.php?title=N%E1%BA%A5m&action=edithttp://vi.wikipedia.org/w/index.php?title=Amylas&action=edithttp://vi.wikipedia.org/w/index.php?title=Xenluloza&action=edithttp://vi.wikipedia.org/w/index.php?title=L%C3%B5i_ng%C3%B4&action=edithttp://vi.wikipedia.org/w/index.php?title=R%C6%A1m_r%E1%BA%A1&action=edithttp://vi.wikipedia.org/w/index.php?title=M%C3%B9n_c%C6%B0a&action=edithttp://vi.wikipedia.org/w/index.php?title=Cellulas&action=edithttp://vi.wikipedia.org/w/index.php?title=Iogen&action=edithttp://vi.wikipedia.org/wiki/Canadahttp://vi.wikipedia.org/w/index.php?title=%C4%90i%E1%BB%83m_s%C3%B4i_h%E1%BB%97n_h%E1%BB%A3p&action=edithttp://vi.wikipedia.org/w/index.php?title=Ch%C6%B0ng_c%E1%BA%A5t_ph%C3%A2n_%C4%91o%E1%BA%A1n&action=edithttp://vi.wikipedia.org/wiki/Benzen

23

hp cp hai vi Ethanol loi b phn ln benzen. Ethanol c to ra khng cha nc.

Tuy nhin, mt lng rt nh (c phn triu benzen vn cn, v th vic s dng Ethanol

i vi ngi c th gy tn thng cho gan.

Ngoi ra, sng phn t c th s dng hp th c chn lc nc t dung dch

96% Ethanol. Zeolit tng hp trong dng vin trn c th s dng, cng nh l bt yn

mch. Hng tip cn bng zeolit l c bit c gi tr, v c kh nng ti sinh zeolit

trong h khp kn v c bn l khng gii hn s ln, thng qua vic lm kh n vi

lung hi CO2 nng. Ethanol tinh cht c sn xut theo cch ny khng c du tch

ca benzen v c th s dng nh l nhin liu hay thm ch khi ha tan c th dng

lm mnh thm cc loi ru nh ru vang pooct (c ngun gc B o Nha hay

ru vang sherry (c ngun gc Ty Ban Nha) trong cc phng php nu ru truyn

thng.

2. c tnh vt l ha hc ca cn

c tnh ca cn c gc OH, gc ny nh hng quyt nh n tnh cht vt l, ha

hc ca cn.

Cn l hp cht ca gc OH vi gc cacbua-hydr. Cng thc ha hc chung l R-

OH, trong R l gc H-C.

Cn ethanol (C2H5OH) v methanol (CH3OH) l hp cht gia etan (CH4) v metan

(C2H5) vi OH, cng thc ru c th vit nh sau CnH2n+1OH. Phn t methanol v

ethanol c gc R cho nn n thuc v ru bc 1. Vi s nguyn t cacbon nh nhau, so

snh cn vi cacbua-hydro khc th cn c c im: phn t lng, trng lng, im

si, nhit bay hi p sut thng u cao, vi l do nh sau:

- Phn t lng v t trng cao hn l do trong phn t cn c thm nguyn t Oxy.

- im si v nhit bay hi cao hn l do mi lin kt gia Oxy v Hydro. Loi

lin kt gia Oxy v Hydro l loi lin kt hydr hoc l lin kt phn t c cc, do vy

l cho gia cc phn t tn ti lin kt ngc. Qu trnh lin kt phn t c cc s b yu

khi tng nhit . V th nn mun lm bay hi cn th chng ta phi cung cp mt nhit

lng lm yu mi lin kt ny.

- Cn dng lng th hm lng ccbon t, cho nn c th ha tan hon ton trong

nc. S d nh vy l v gia phn t cn v phn t nc c tn ti lin kt phn t c

cc. Nu hm lng cacbon trong phn t cn nhiu th gc R tng ln n s lm cn tr

lin kt phn t c cc gia cn v nc. iu ny dn n vic cn c s lng nguyn

t cacbon trong phn t cng ln th kh nng ha tan vo nc cng gim i. Do vy

nn kh nng ha tan ca methanol trong nc ln hn ethanol. Ngc li nu lng OH

trong phn t cn cng nhiu th i lc lin kt gia cn vi nc tng ln cho nn c th

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24

cng ha tan trong nc. V mt ny th methanol v ethanol ging nhau v cng c mt

gc OH.Nhng c tnh l ha lm cho cn c kh nng thay th xng v du diezel.

Bng 1.14. Mi quan h v c tnh l ha ca cn vi xng v du diezel

c tnh l ho Diezel Xng Ethanol 95% Methanol 95%

Khi lng ring (Kg/dm3) 0,83 0,75 0,78 0,79

Nhit bay hi (KJ/Kg) 230 350 840 1103

1 at, 25oC

Nhit tr (KJ/Kg) 43800 44000 26900 21400

Nhit tr hn hp (KJ/Kg) 2850 2830 2690 2680

Khi lng khng kh cn

14,40 14,60 8,96 6,44 thit t chy nhin liu

(g khng kh/ g nhin liu)

Lng nhin liu cn thit

0,069 0,068 0,111 0,155 ng vi 1 n v khng kh

(g khng kh/ g nhin liu)

Ch s octan (tnh theo

RON 20 98 106 110

Ch s cetan 50 15 5 0

T s nguyn t H/C 1,842 2,035 2,975 3,968

T s khi lng H/C 0,155 0,171 0,250 0,333

T s nhit tr ca H/ nhit

tr nhin liu 0,353 0,376 0,468 0,540

T s nhit tr HH/HC 0,546 0,603 0,881 1,175

Thnh phn ha hc%: H 13,4 14,6 13,04 12,5

C 86,6 85,4 52,18 37,5

O 0,00 0,00 34,78 50

a. Kh nng dng cn thay th cho xng.

Nhit tr khi lng ca cn nh hn xng v du diezel khong 1,64 ln. Nhng

nhit tr hn hp ca cn ethanol+xng+khng kh ch nh hn nhit tr hn hp ca

xng+khng kh khong 5% (do lng khng kh cn thit t chy 1 kg cn t hn

xng khong 38%). V vy xt khi h s d lng khng kh nh nhau th khi dng cn

lm nhin liu ng c gim cng sut rt t. Thc ra khi dng cn bng cch t B ch

ha kh trn ng ng np th nhit n bay hi ca cn ln hn xng 1,67 ln nn nhit

dng kh np thp hn so vi khi dng xng cho nn ta c th np vo xy lanh mt

lng np nhiu hn l khi dng xng, iu ny c th lm ng c c th c cng sut

ln hn khi dng xng.

25

Ch s RON ca cn l 106, ln hn loi xng A83, A92 rt nhiu. R rng cn l

loi nhin liu c tnh cht chng kch n tt cho ng c xng. i vi ng c xng,

pha cn vo xng l mt bin php lm tng tnh chng kch n trong qu trnh chy.

Trc y, ngi ta phi dng xng pha t-tra ethyl ch tng tnh cht ny. Gn y,

ngi ta chuyn sang dng loi xng khng pha ch c tnh chng kch n cao, nhng

li gp rc ri mi l phi dng cng ngh phc tp v t tin hn sn xut xng

hoc phi dng cc thnh phn mi trong xng cng gy c hi khng km g ch.

Ngi ta lm th nghim v thy rng: c pha thm mi 7% cn vo xng th tng t

s RON ln 1,2 n v hoc tng ch s MON ln 1,7 n v. Gii php pha cn vo xng

tng tnh cht chng kch n cho nhin liu c rt nhiu nh khoa hc trong v

ngoi nc ng h v y l mt gii php sch khng gy nhim mi trng. V vy

c th pha cn vo xng l mt bin php chng nhim rt tt. Ch s octan cao ca

ethanol cn cho php tng t s nn ca ng c dng hn hp ngoi ln n 13.

Trong thnh phn cn ethanol ch c 53,8% cacbon v c n 34,75% xy; cn trong

xng c n 86,6% cacbon v lng xy l 0,0%. Do vy, khi b t chy trong bung

chy ca ng c t trong th lng CO trong kh thi trong trng hp dng cn s t

hn so vi xng, kh thi hu nh khng c b hng. Khi dng cn, lng HC c tng

ln do khng kh v thnh xy lanh b thu nhit cc b do cn bay hi, ti nhng ni

lng HC khng chy tng ln. Lng NOx gim khong 5-10%, ch yu l do nhit

chy thp v thi gian nh ngn la ngn.

Lng oxy trong cn kh nhiu nh hng tt n s t chy nhin liu v phn t

cn c oxy ti ch t chy C v H.

Vi nhng c trng nh trn th vic dng cn thay th cho xng l hon ton c th.

Tuy nhin, khi pha cn trc tip vo xng li ny sinh mt vn mi nh sau:

Ti ICAT 99, khi bn lun v vn pha trc tip cn vo xng, cc nh chuyn mn

ngnh xng du cho rng lm nh vy khi tn tr lu ngy s sinh ra hin tng ng

nha trong bn xng.

Do vy, khi dng cn thay th mt phn hoc hon ton th cn phi c nhng ci tin

ph hp i vi h thng nhin liu hoc l kt cu ng c.

b. Kh nng dng cn thay th cho du diesel.

Vn dng cn ethanol trn ng c diesel cha c t ra nhiu so vi dng trn

ng c xng, c l l do tnh cht ca cn ethanol xem ra khng thch hp vi yu cu

ca tnh cht nhin liu dng cho ng c diesel: ch s cetan v nht ca cn ethanol

rt thp, khng th t chy cn ethanol bng phng php t bc chy trong ng c

diesel. Vi cch nhn nhn nh vy lm chng ta b l c hi tng tnh kinh t s dng

ca cn ethanol. Bi v, nh chng ta bit ng c diesel c tnh kinh t nhin liu cao

26

hn ng c xng. Mt khc, dng cn ethanol thay du diesel s gp phn lm gim

nhim mi trng t kh thi ng c diesel: cc ch s HC, CO, khi en u thp

hn so vi khi dng du diesel. S d nh vy l do trong phn t cn ethanol c thnh

phn cacbon t hn vi du diesel.

c th dng c ethanol thay cho du diesel bng phng n kt hp dng cn

ethanol vi du thc vt bng cch to ra loi este du thc vt cho loi nhin liu ny

c cc tnh cht l ha gn nh du diesel. Mt cch khc l dng cht ph gia procetane

lm cho ch s cetan ca n xp x ca du diesel (v d cht procetane nh tri-ethyle

glycole-dinitrate, c tn thng phm l AVOCET, pha cht ny 4% trong ethanol 95%

thun th ch s cetan ca ethanol tng ng du diesel. Cht nitra hexyle vi t l

17,5% pha vo cn ethanol th ch s cetan ca cn ny cng xp x du diesel. Tuy

nhin, to ra este du thc vt i hi phi c cng ngh phc tp, i vi iu kin

ca Vit Nam hin nay th gii php ny cha tht ph hp.

Cn mt phng n na l dng mt gii php cng ngh hi c bit t chy d

dng cn ethanol trong bung chy ng c diesel. Nhm nghin cu Trng i hc

K thut Nng (nay l Trng i hc Bch khoa Nng) p dng nguyn l

t chy cn trong bung chy ng c diesel bng ngn la chy mi ca tia phun

du diesel chim khong 20% n 30% tng lng nhin liu a vo bung chy t

chy 70% n 80% lng c a n bung chy theo ng ng np. Nu mua c

loi vi phun cao p nh th du diesel phun mi c th gim xung cn 5% v khi

lng cn ethanol trong nhin liu chung t n 95%.

ng c diesel lm vic theo nguyn l ny c cc u im:

- ng c lm vic m hn.

- Hiu sut ch th cao hn do ton b thi gian chy (ch yu l thi gian chy

chnh) c rt ngn. Dn n tnh kinh t nhin liu cao hn so vi khi ch dng du

diesel v d nhin l cao hn so vi khi dng trn ng c xng.

- Lng CO, NOx gim. khi en gim hn do lng cacbon trong phn t cn

ethanol chim t l t hn so vi du diesel v trong phn t cn c cha sn nhiu oxy,

lm cho s t chy tt hn. Lng NOx gim khong 5 10% ch yu l do nhit

chy thp v thi gian nh ngn la ngn.

- C th cho ng c diesel tr li lm vic vi 100% du diesel.

Khi dng gii php ny phi tng cng sy nng ng ng np bng nc lm mt

ng c hoc bng nhit bc x t ng thi hoc bng bin php hi lu kh thi lm

bay hi trit cn ethanol sau khi qua b ch ha kh.

Mt s c s nghin cu Trung Quc th nghim dng cn theo nguyn l trn

nhng vi lng nc trong cn n 39%, 50%. Cc kt qu o c ca h cho thy: tnh

27

kinh t nhin liu cao hn, hao mn xylanh tng ln khng ng k so vi khi dng

100% du diesel.

3. c im ng c khi dng hn hp nhin liu cn xng.

a. T s nn ca ng c.

ng c s dng hn hp cn

xng cho php tng t s nn ng

c, mc tng t s nn ng c

ph thuc vo t l cn trong hn

hp. T s nn cho php l t 13

n 14 tng ng vi khi s dng

90% n 100% cn [5]. Bin php

tng t s nn ng c c th l:

Gim chiu dy m quy lt, s

dng xu pp li, s dng piston li

v bin php hn hp.

b. n mn v lm h hi chi tit.

Khi s dng cn hoc hn hp cn xng cho ng c, do s hnh thnh axit hu

c: axit Acetic lm n mn mn cc chi tit kim loi v lm h hi cc chi tit phi kim

loi trong h thng nhin liu. V vy, ng c s dng cn hoc hn hp cn xng cn

phi c bin php lm hn ch n mn v lm h hi chi tit. Tuy nhin chng ta c th

gii quyt vn ny bng cht ph gia pha vo nhin liu. Mt s cht khng ch s

n mn khi s dng trong ng c

nh: Octel DCI-11, Petrolite 3222 v

3224, Nalco 5403, Endcor FE-9730,

MidContinental MCC5011E,

c. c im ng ng np.

Do nhit n ca cn ln, nn

khi s dng hn hp vi t l cn

cao nhit ng ng np rt thp,

iu ny nh hng ln n tnh bay

hi ca nhin liu. V vy, ng

ng np ca ng c s dng cn

hoc hn hp cn xng c t l cn

cao phi c sy nng.

d. Tnh bay hi ca hn hp.

Hnh 1.10 Tr s c tan ca hn hp v t s nn cho

php ca ng c

Hnh 1.11. ng c tnh chng ct ca hn hp cn

thng dng v xng A92

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

0 10 20 30 40 50 60 70 80 90 100

Thnh phn chng ct (%)

Nh

it

(

C

)

10% Cn thng dng

15% Cn thng dng20% Cn thng dng

50% Cn thng dng

80% Cn thng dng

85% Cn thng dng90% Cn thng dng

Mu xng 92

28

Tnh bay hi ca hn hp ph thuc vo t l cn trong hn hp, kt qu phn

tch ti phng th nghim Ha du, Trng i hc Bch Khoa Nng c th hin

hnh 1.11 i vi cn thng dng.

ng cong bay hi ca E10 n E50 c im bay hi 10% gn ging vi xng. iu

ny c ngha l hn hp E10 n E50 c th s dng lm hn hp khi ng. im bay

hi 50% v 100% ca hn hp u thp hn xng, do vy kh nng tng tc v tnh chy

ht ca hn hp cn xng l tt hn xng.

e. T trng v nht hn hp.

T trng v nht ca hn

hp cn xng qua phn tch cho

thy tng theo t l cn trong hn

hp, c th hin trn hnh 1.12

v hnh 1.13.

Do t trng v nht ca

hn hp cn xng cao hn xng,

nn tnh lu ng ca hn hp

cn xng s km hn xng.

xc nh c t l ti u cn m bo tnh khi ng, cng sut v tng tc, cng

sut, tiu hao, nhim, n mn.

Hnh 1.12. T trng v nht theo t l cn thng dng

trong hn hp

0.74

0.75

0.76

0.77

0.78

0.79

0.8

0.81

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

T l cn trong hn hp

T t

rn

g

0

0.2

0.4

0.6

0.8

1

1.2

1.4

nh

t

(cS

t)

T trng (d)

nht (cSt)

Hnh 1.13. T trng v nht theo t l cn k

thut trong hn hp

0.74

0.75

0.76

0.77

0.78

0.79

0.8

0.81

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

T l cn trong hn hp

T t

rn

g

0

0.2

0.4

0.6

0.8

1

1.2

nh

t

(cS

t)

T t rng

nht

Hnh 1.14. Kh nng lm lnh ca hn hp cn xng khi

bay hi

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

0 0.2 0.4 0.6 0.8 1

Nh

it

(

C

)

T l hn hp

29

- Khi ng: ng cong bay hi ca E10 n E50 c im bay hi 10% gn ging

vi xng. Tuy nhin, do kh nng lm lnh ca cn khi bay hi rt ln nn hn hp khi

ng phi nh hn 20%.

- Cng sut v tng tc: do nhit tr ca cn thp, nht cao, khi lng ring ln

nn m bo cng sut v tng tc tt cn phi lm gc l khi s dng hn hp to hn.

Nu s dng gc l v sy nng ng ng np hp l cho php s dng c hn hp

c t l cn cao: 85-100 % cn.

- Tiu hao: do nhit tr ca cn thp nn tiu hao nhin liu khi s dng hn hp

cn xng l cao hn so vi dng xng. Nu gi cn tnh theo gi cn Brasil th khi s

dng hn hp c t l cn cng cao th tnh kinh t cng tt.

- nhim: cc cht nhim thi ra do t chy cn l thp hn xng. Tuy nhin

do kh nng bay hi nhit thp km, cng vi s lm lnh ng ng np trong qu

trnh bay hi cho nn nu hn hp c t l cn ln hn 85% trm kh nng chy khng

ht tng, lm tng cc cht nhim do chy khng hon ton.

- n mn: n mn kim loi (thng cha) xy ra i vi cn k thut do c axit.

i vi cng thng dng n mn kim loi l rt t, do cn thng dng kh axit. Nh

vy, n mn c th c gii quyt trit nu trung ha c nng axit trong hn

hp.

Theo phn tch trn: Chn hn hp khi ng l hn hp c t l cn nh hn

15%, hn hp chy chnh l hn hp c t l cn nh hn 85%.

f. Vn nhim kh thi khi s dng cn lm nhin liu.

Khi dng hn hp xng pha cn th vic thi CO v HC l rt thp v NOx l gn nh

khng i so vi dng thun xng. iu ny c l gii nh sau:

- Trong cn c cha Oxy, do vy khi chy n t cung cp Oxy cho nhin liu lm cho

sn phm chy trung gian CO chuyn thnh CO2 nhiu hn. ng thi, trong nhin liu

c cha nhiu Hydr th lng tng i C s gim.

- Do ng c xng dng hn hp nhin liu xng pha cn th t s nn c th tng

cao, do vy m trng thi nhit ca ng c tng ln. iu ny lm cho s chuyn ha

CO thnh CO2 v H2C thnh H2O d dng hn.

f.1. nhim CO2

nhim CO2 ca ng c Ethanol so vi ng c xng gim khong 9%. S

gim ti a c th n 20%, iu ny c th gii thch l do t l H/C ca ethanol cao

hn so vi xng (3 i vi ethanol v 1,8 i vi xng). Vi d: tc 2000 v/ph, p

sut 2bar, mc CO2 i vi xng l 1,22 v i vi thanol l 1,13g/kWh, gim so vi

xng 7,4%.

30

Mc pht sinh nhim CO2 tnh theo tiu chuu chu u i vi Ethanol v xng

c th hin trn cc hnh 1.16, hnh 1.15.

f.2. nhim HC

nhim HC kh xc nh mt

cch chnh xc vi vic theo di s ion

ha mng la tiu biu s dng ng c

o nhim. HC hnh thnh t nhng

hydrocarbon ca Ethanol b phn hy v

HC c trong Ethanol cha chy. Lng

Ethanol cha chy nhiu hn lng HC

c mt trong kh x.

Hnh 1.19. nhim HC

Hnh 1.18. nhim CO2 theo chu trnh

NEDC ca ng c Ethanol v xng

Hnh 1.16. nhim CO2 (kg/kWh) i vi

ng c s dng Ethanol

Hnh 1.15. nhim CO2 (kg/kWh) i vi ng

c s dng xng

Hnh 1.17. nhim CO2 theo chu trnh NEDC

ca ng c Ethanol v xng

31

f.3. nhim CO

ch tc thp, mc nhim CO vi ng c Ethanol gim mt na so vi

ng c xng. ch ti ln mc nhim CO cng thp hn so vi ng c xng, bi

nhit kh thi thp, c th chy y ti vi hn hp khng giu. C th tc 5250

v/ph mc nhim CO gim 6 ln so vi xng, cng sut v m men cng cao hn so vi

xng.

- Khi dng cn v hn hp xng pha cn th mt mt nhit chy ln nht gim,

mt khc trong hn hp li c giu Oxy. Hai mt ny c tc dng ngc nhau i vi

vic sinh ra NOx trong kh thi. Vy lng NOx sinh ra so vi ng c dng nhin liu

100% xng gn nh l khng i.

ch ti nh, nhim NOx thp hn so vi xng

ch ti ln, nhim NOx cao hn, tuy nhin c th gii quyt vn ny bng

ng x xc tc 3 chc nng.

- C mt iu c bit l khi m chng ta chuyn dng xng sang cn hoc xng pha

cn th lng cn chy cha ht vi lng Fomandehyt tng ln. Hai lng ny c hi

cho sc khe con ngi. Lng dng cn Fomandehyt l thnh phn lm cho kh c mi

thi, cht ny l sn vt trung gian ca qu trnh chy. Cht ny tng ln lm cho qu

trnh chy khng hon ton. Do vy, phi c bin php kh kh ny trong bung chy

ng c hoc l trn ng ng thi. Theo nhiu ti liu th vn kh cht Fomandehyt

trn ng ng thi d dng hn vic kh CO, NOx, HC rt nhiu.

Khi dng cn trn ng c diesel th khi en gim i nhiu, iu ny c th gii

thch nh sau:

- Nu trn ng c dng du diesel v cng trn ng c dng cn ethanol vi

iu kin lng ta nhit nh nhau th khi dng cn phn to nhit ra do t chy hydr

ln hn so vi khi dng du diesel. t chy hydr khng sinh ra khi en, cn t chy

cacbon th sinh ra cc Oxit-cacbon v mui than.

- Do khi dng cn c t ccbon tham gia phn ng nn khi en t hn.

- Do phn t cn c cha oxy nn nu lng khng kh np vo xylanh nh nhau th

h s d lng khng kh thc t khi dng cn l ln hn, iu ny cng lm gim lng

khi en.

- Lng khi en gim cn do nguyn nhn cn hp th lng nhit ln ca khng

kh v ca thnh xylanh nn nhit kh chy gim v thi gian nh ngn la ngn, iu

ny cng lm gim lng mui than trong kh x.

32

CHNG 2: NG C S DNG NHIN LIU LPG-CNG

2.1. c im chung ca ng c dng nhin liu LPG:

2.1.1. Momen, cng sut ng c.

Momen v cng sut ca ng c s dng LPG thp hn khong 10% so vi ng c

xng cng c do cc yu t sau:

+ Nhit tr th tch ca hn hp khng kh/ xng ln hn nhit tr th tch ca hn hp

khng kh/ LPG khong 3% n 5%.

+ c tnh ca h thng cp nhin liu LPG. Khi phun LPG dng kh vo ng np

qua hng Venturi lm gim h s np v gy xo trn ng lc hc trn ng np do

lm gim momen v cng sut ng c. Khi phun LPG dng lng s bc hi trn ng

np lm gim nhit kh np v tng khi lng ring ca hn hp h s np c ci

thin hn do khc phc phn no s gim momen v cng sut ng c.

2.1.2. Sut tiu hao nhin liu.

Sut tiu hao nhin liu tnh theo th tch v theo khi lng nhin liu ca ng c

LPG so vi ng xng nh sau: thc t nu so snh nng lng tiu hao trn 100km hnh

trnh th nhin liu LPG thp hn ng c xng khong vi phn trm. Mt khc, nu

LPG giu Propan(C3H8) vi ch s Octan ca n rt cao do c th tng ch s nn

ng c nn sut tiu hao nhin liu c th gim.

2.1.3. Mc pht nhim.

ng c s dng LPG pht sinh t nhim. y l c im ng ch trong bi

cnh m nh hng ca giao thng vn ti n mi trng sng ngy cng tr nn

nghim trng. Bng 1.10.

S pht sinh nhim trong kh x ng c LPG gim i rt ng k so vi ng c

xng.

Bng 2.1. Mc pht thi nhim ca t chy nhin liu LPG so vi tiu chun nhim hin nay.

Cht

nhim

Gii hn cho php Mc pht nhim

Europe 2000

(g/km)

California

ULEV (g/km)

Chu trnh

Europe (g/km)

Chu trnh FTP75

(g/mile)

CO 2,30 1,70 0,16 0,14

HC 0,20 0,04 0,031 0,032

NOx 0,15 0,20 0,02 0,065

33

ng thi nng NOx gim, c bit khi ng c hot ng khu vc gn y ti,

iu ny l do nhit mng la nhin liu LPG thp hn mng la xng. Cn mc

pht sinh HC thp ch yu do LPG bay hi rt d dng, lng nhin liu bm trn thnh

bung chy thp v lng nhin liu hp th bi du bi trn thp, HC trong kh x ng

c LPG ch yu l Hydrocarbure nh (C3 C4) t c hn Hydrocarbure nng trong kh

x ng c xng v Diesel.

2.1.4. Tnh an ton v tui th ng c.

-Vn an ton: Trong h thng nhin liu LPG c rt nhiu thit b an ton c v

mt c kh ln in t m bo an ton trong khi ng c hot ng ln khng hot

ng v khi xy ra tai nn.

Cc van an ton t ng ng, ngt h thng nhin liu LPG v h thng ny hon

ton b kha kn vi mi trng khng kh bn ngoi.

Cc cuc th nghim thc t ti trung tm nghin cu quc t cho thy khi b tai

nn lt xe, trong khi xng c th tro ra ngoi gy chy th LPG khng th tro ra ngoi

do c cc van an ton. Cc s c r r trn ng ng nu c cng lm ton b h thng

LPG t ng kha kn li.

- Vn tui th ng c: Do LPG c c tnh k thut nh tnh chng kch n cao,

khng c ch, sn phm chy khng c mui than, khng c hin tng ng mng nn

ng c lm vic vi nhin liu LPG t gy kch n hn ng c xng. Do khng c cc

ht ch hoc cc ht mui than ng li trong thnh vch xylanh, ca xupap np, thi nn

khng gy mi mn xylanh, piston, secmng, xupap, xupap. Mt vn quan trng l

ng c xng hay c hin tng hi xng hnh thnh trong bung chy, c tc hi ra

sch cc mng du bi trn v c khuynh hng lt xung cacte lm du bi trn gim

kh nng bi trn, trong khi LPG khng c hin tng ny.

Chnh v nhng l do ny nn LPG cho php ko di tui th ng c hn nhin liu

xng khi s dng ng c cng mt ch hot ng.

2.2. Phng n cung cp nhin liu LPG cho ng c

LPG c th cung cp cho ng c di dng kh hay dng lng. u im ca vic s

dng LPG di dng kh l s ng nht hon ho ca hn hp ga - khng kh v trnh

hin tng t thnh ng ng np bi nhin liu lng, hin tng ny rt nhy cm

khi khi ng v khi ng c lm vic ch chuyn tip. iu ny cho php lm

gim c mc pht sinh nhim. Nhc im ca vic cung cp dng ny l qu

trnh iu khin di v s cung cp ga lin tc lm hn ch kh nng khng ch t l

khng kh/gas, c bit l ch qu ca ng c.

34

H thng cung cp LPG bng cch phun LPG dng lng cho php khc phc nhc

im ca phng php cung cp LPG dng kh. u im ca phng php phun LPG

dng lng l to ra kh nng kim sot c m c mi ln phun vi thi gian rt

ngn v vy c th p dng cc bin php hu hiu nhm gii hn mc pht nhim

khi ng c lm vic ch qu . S bc hi ca LPG lm gim ng k nhit

kh np do lm tng h s np ca ng c. Mt khc, mng nhin liu lng bm trn

ng np khng ng k g so vi khi ng c dng xng. iu ny thun li cho vic

lm gim mc pht sinh HC. Tuy nhin yu cu cng ngh ch to cao.

Trn c s cc phng php to hn hp lm vic cho ng c nh phn tch

trn, ta c th p dng cc phng n cung cp nhin liu sau :

+ Cung cp LPG cho ng c di dng ho kh

+ Cung cp LPG cho ng c di dng lng : phun nhin liu.

2.2.1. Cung cp nhin liu LPG dng kh dng b ch ha kh

C nhiu dng b ch ho kh da trn nguyn tc ng Venturi. Sau y l mt s

dng:

a. B ch ha kh dng mng

S cu to

Nguyn l lm vic : Khi

dng ng c, van C ng ng

thi ng vo ca khng kh v

ca LPG di tc dng ca l xo

R. Mng M chu p sut sau

hng Venturi c truyn qua

nh bn l F. Khi lu lng

khng kh tng dn, van xa dn

khi , to ra mt tit din lu

thng cho bi li nh dng O.

Bin dng ca li ny c xc

nh theo nhit tr ca nhin liu. B phn ny cho php t c hn hp c thnh phn

khng i trong ton b phm vi hot ng ca ng c. S iu chnh tinh c thc

hin nh tc ng ca hai b phn sau :

B gin n trn ng np LPG : Cho php iu chnh p sut ga - khng kh v tc

ng ln m c ca hn hp ch yu ch thp.

Bm V to ra mt tn tht p sut thay i v tc ng ch yu khi cng sut ng

c t cc i.

Hnh 2.1.B ch ho kh dng mng

1 - Bm ga ; M - Mng ; R - L xo ; C - Van ; 5 - ng LPG

vo; 6 - ng khng kh vo ; F-l; O-li nh dng; V-bm iu

chnh

1

5 6

35

Phng n ny phi ch to b ch ha kh dng mng cho h thng cp LPG nn tn

km, phc tp khng ph hp cho xe xng ang s dng b ch ha kh.

Di y chng ta tham kho thm 2 loi b ch ha kh dng mng

Hnh 2.2.S dng b ch ha kh dng mng (loi 2)

A-ng cp LPG dng kh; V-van; S-l xo nh lng; P -bung van; D-mng van; I-vt chnh khng ti

Hnh 2.3. S dng b ch ha kh dng mng

(loi 3-X450)

2-van nh lng; 3-bung trn; 4-bung di; 7-

ca khng kh vo; 8-vng m;

Hnh 2.4.Van nh lng ca b ha kh

dng mng loi 3

LPG dng

kh LPG

dng kh

36

b. B ch ha kh dng Modul ha

S cu to:

Kh LPG c ht vo pha sau bm gas c iu khin bi mt b nh lng 5.

Khi s dng h thng ny trn cc ng c khc nhau ch cn thay i b nh lng v

Jicl tiu chun. H thng ny cho php ng c lm vic lng nhin liu xng v LPG,

b ch ha kh xng c lp pha trc hng gas.

Phng n ny phi ch to b ch ha kh ring cho h thng cp LPG nn tn km,

phc tp khng ph hp cho xe xng ang s dng b ch ha kh

c. S dng b trn

4 2

3 1

5

Hnh 2.5. B ch ho kh dng Modul ho.

1 - Bm ga ; 2 - ng ng phun LPG ;3 - C cu iu khin 4 - ng vo ga ; 5 - B nh lng.

LPG dng

kh

Hnh 2.6. H thng cung cp LPG vo b trn

1-bnh LPG; 2-van in t LPG; 3-b ha hi v gim p; 4-b tit lu; 5-b trn; 6-ng c; 7-

bng theo di; 8-bu lc gi

37

LPG t bnh cha 1 i ti van 2 vo b ha hi 3, ti y LPG c bc hi v h p

sut xung ri c dn vo b trn, ti y n c ha trn vi khng kh theo ng t

l ph hp vi ch ti ca ng c. Ri dn vo xylanh ng c.

Phng php ny phi ch to b trn, lp trn ng np, n ph hp vi loi ng c

phun xng in t, hoc ng c ch s dng mt loi nhin liu LPG hoc ng c c

ming b ch ha kh tiu chun.

d. Dng hng Venturi vn nng

Hng Venturi vn nng c thit k dng cho b ch ha kh hn hp, n ging

nh mt chic m v c th c lp t bt c v tr no trn ng np : gia bu

lc gi v b ch ha kh xng; b ch ha kh, pha trc bm ga.

Phng n ny phi ch to hng Venturi ring cho h thng LPG nn tn km, phc

tp khng ph hp cho xe xng ang s dng b ch ha kh. Tuy nhin n c th lm

mch khng ti kt hp vi n: ng cp gas t vo hng b ch ha kh nguyn thy

Hnh 2.7.Hng Venturi vn nng.

1 - ng gas vo ; 2 - Bulng ; 3 - Mt bch ; 4

L bt bulng.

21 43

Hnh 2.9. Hnh chp hng Venturi vn nng

Hnh 2.8. Hnh chp b trn

38

e. ng cp gas t vo hng b ch ha kh nguyn thy

Dng ci to ny dng hng Venturi nguyn thy ca ng c xng. LPG c mt

ng ng dn ti vng chn khng ca hng, ng ny c th dn theo ng trc ca

b ch ha kh hay vung gc vi ng trc bng cch khoan xuyn qua thnh b ch

ha kh.

Phng n ny kinh t nht v ph hp vi xe xng ang s dng b ch ha kh v

c th kt hp vi phng n: dng hng Venturi vn nng.

Tuy nhin nn xt c tnh ca b ch ha kh, nu hot ng theo b ch ha kh n

gin th nn c mt s c cu iu chnh tr thnht b ch ha kh t ng.

2.2.2. Cung cp nhin liu LPG dng phun nhin liu

Nhin liu LPG c th cung cp cho ng c di dng lng bng h thng phun vo

c gp (phun mt im) hay phun vo trc supap np ca tng xylanh (phun a im).

p sut nhin liu trc vi phun ca hai kiu ny u cao hn p sut kh quyn. Nhin

liu phun vo ng np ng c c th di dng kh hay lng.

Nhin liu LPG di dng lng t bnh cha c ht nh mt bm chuyn v duy

tr p sut d trn ng ng khong 5 bar trnh s bc hi. Nhin liu sau c

a qua b lc v b iu p trc khi dn n vi phun. Vi phun c mt b vi x l

chuyn dng iu khin mt cch t ng. B vi x l ny nhn phn ln cc tn hiu

cn thit t h thng cung cp nhin liu xng c v c b sung thm nhng thng

tin c th khc ca h thng cung cp nhin liu LPG.

Hnh 2.10.To hn hp bng cch dn kh LPG vo hng b ch ha kh nguyn thy.

1 - Bu lc gi; 2 - ng ng dn kh LPG; 3 -Bm ga; 4 - C cu dn ng bm ga; 5 - Hng phun LPG

3

2

4

5

1

39

Phng n ny i hi phi c h thng iu khin in t, yu cu h thng cp

nhin liu chu p sut cao nn ch to tn km.

Di y ta tham kho thm hai s cung cp nhin liu LPG dng phun a im.

Hnh 2.12.H thng cung cp nhin liu phun LPG di dng kh loi a im

1-bnh cha LPG; 2-van in t LPG; 3-b gim p ha hi; 4-bnh lc; 5-gin phun; 6-ng c;

7-ECU LPG; 8-cm bin p sut

Hnh 2.11. H thng cung cp nhin liu LPG di dng lng

40

Phng n t ng cp gas vo hng b ch ha kh nguyn thy l kinh t nht v

ph hp ci to xe xng ang s dng b ch ha kh thnh xe s dng 2 nhin liu

xng/LPG.

2.3. Cc phng n iu khin cung cp LPG

2.3.1. H thng c hc, iu khin in

Mt van in t chuyn i m van cp xng hay cp gas ty ngi li. B ha hi

v iu p s cp gas v c trn vi khng kh ti cacbuarateur v hn hp c a

vo ng c. Loi ny ph hp vi nc khng i hi ngt ngho tiu chun kh thi

t v cng ngh pht trin cha cao.

Hnh 2.14. b tr cc thit b h thng LPG loi 1 trn xe

1-van np LPG; 2-bnh cha LPG; 3-cng tc chuyn i; 4-van in t LPG; 5-b gim p v ha hi; 6-

van in t xng; 7-ng dn LPG

Hnh 2.13.Hnh chp b gin phun LPG loi a im

1-ECU LPG; 2-ECU xng; 3-cng tc chuyn i; 4-b gim p ha hi; 5-cm bin p sut; 6-

vi phun; 7-lc

41

2.3.2. H thng c hc, iu khin in t v cht xc tc.

C cc thit b in t nh lng gas cung cp cho ng c. C s dng cm bin tc

, cm bin lamba gi tn hiu n b iu khin trung tm, b ny pht lnh iu

khin mt bc, iu chnh van cp gas chnh nm gia iu p v b trn iu

chnh hn hp chy.

Phng n ny s dng vi xe c trang b thm b xc tc ba chc nng trn ng

ng x, v yu cu c b iu khin in t, c cc cm bin iu khin qu trnh cp

nhin liu vo ng c.

Hnh 2.15. B tr thit b h thng LPG, loi c hc, iu khin in t v cht xc tc

1-bnh cha LPG; 2-van a cng; 3-ECU; 5-b trn; 6-b ha hi va gim p.

42

2.3.3. H thng phun LPG iu khin in t

Hnh 2.16 S b tr phng n phun LPG

1- Bnh cha nhin liu LPG; 2 Van a cng ca bnh cha; 3 u np LPG; 4 ng dn LPG p lc

cao; 5 Solenoi gas; 6 Cm bin nhit kh gas; 7 Co ng nc lm mt; 8 - B gim p ha hi; 9 ng thng

chn khng; 10 Cng tc chuyn i; 11 - Lc kh gas t b gim p; 12 ng dn kh gas n ng tch tr; 13

Cm bin p sut kh gas; 14 Dn kim phun kh gas; 15 ng tch tr kh gas; 16 Kt nc lm mt; 17 - ng

dn nc lm mt; 18 My tnh ci t phn mm squent 24; 19 Mtor bc; 20 Bm gas; 21 Cm bin v

tr bm gas; 22 - ng gp np; 23 Cm bin v tr bn p gas; 24 B n nh p sut nhin liu; 25 Cm

bin v tr trc cam; 26 B gim chn p sut nhin liu; 27 - ng phn phi nhin liu;28 Kim phun xng;29 -

Cm bin ting g; 30 Cm bin nhit nc lm mt; 31 Cm bin v tr trc khuu; 32 Cm bin xy ; 33

Cm bin nhit kh np; 34 Khay lc gi; 35 u phun kh gas

43

2.3.4. Phun theo chu k c lp

S dng cho xe hng nng chy du izel. Gi nguyn ng c iezel v lp thm

h thng cp gas to hn hp vi khng kh trc khi phun, hn hp c chy trong

xylanh sau khi du iezel c phun, lng iezel s gim, gas thay th ti a khong

40% nhin liu.

*Kt lun: H thng cp kiu c hc, iu khin bng in l kinh t nht v ph

hp ci to xe xng khng c nn in t thnh xe s dng 2 nhin liu xng/LPG

v ph hp vi iu kin Vit Nam.

2.4. c im kt cu phng n cung cp LPG cho xe my

h thng nhin liu LPG ca t, nhin liu ra khi bnh cha di dng lng sau

bc hi b bc hi-gin n v dn n hng Venturi vi p sut thp hn p sut

kh tri. Nhin liu th kh sau c ht vo hng b ch ha kh nh chn khng

ging nh b ch ha kh xng.

ng c xe gn my hai bnh cng sut b, vic xut nhin liu ra khi bnh cha

di dng lng s gy ra s tha nhin liu. Mt khc, khi s dng nhin liu dng lng

chng ta cn phi c b gin n-bc hi, b phn cng knh, khng th lp t trong

khong khng gian hn ch ca xe.

V vy phng n ph hp nht i vi xe gn my l s dng nhin liu ra khi bnh

cha di dng kh c p sut. S cung cp ga vo hng b ch ha kh v vy c thc

hin lin tc v lng ga np vo hng c iu chnh bi p sut trong ng dn ga v

Hnh 2.17. S nguyn l kt cu ca h thng LPG, loi phun iu khin in t

1-bnh cha LPG; 2-van in t LPG; 3-b gim p ha hi; 4-bnh lc; 5-gin phun; 6-ng c; 7-b

ECU LPG ; 8-cm bin p sut

44

chn khng ti hng. K thut iu chnh lu lng ga xut trong cng trnh ny l

dng van tit lu c m t l vi m bm cung cp gi.

2.4.1. H thng nhin liu cho xe gn my ch s dng LPG

S ca h thng c m t trn Hnh 2.18. H thng gm cc b phn sau y:

- Bnh cha LPG bng thp, hnh tr, chu c p sut th 34 bar. Bnh c gn ng

h p sut, ng h o mc nhin liu. ng ly LPG c b tr sao cho nhin liu ly ra

khi bnh dng kh. Khi s dng, khng c np nhin liu LPG lng qu 80% th

tch ca bnh.

- Van: s dng cm van ca bnh ga gia dng np ga vo bnh, ly ga ra s dng.

Van an ton cng l mt b phn ca cm van c p sut tc ng 18 bar.

- B dn n: s dng b dn n ca bnh ga gia dng vi lu lng n nh ti a l

2kg/h p sut sau van l 30 mbar.

Hnh 2.18. H thng nhin liu ca xe gn my ch s dng LPG

- Van in t s dng ngun in mt chiu 12 Volts, ch nhc ln khi cng tc

in ca xe v tr ng. Van in t c th thay th bng mt van chn khng, m nh

45

chn khng ti hng ca b ch ha kh. Mt khc, phng s c ca cc van ni

trn, mt van xoay c kh thng thng c mc song song vi van in t hay van

chn khng.

- Bnh iu ha c dung tch 0,3 lt cung cp n nh lu lng LPG cho ng c,

trnh mch ng trong k np, c bit l khi gia tc.

- B to hn hp: c th s dng mt trong hai phng n sau:

a. Ci to b ch ha kh dng xng nguyn thy sang dng LPG: Trong trng

hp ny h thng cung cp xng chnh c ci to thnh van trt tit lu; vt x xng

v ng xng tro tr thnh h thng khng ti. Khoan thng ng cung cp xng chnh

v ng cung cp xng khng ti. L khng ti khi dng xng tr thnh h thng cung

cp kh LPG cho ng c. Cc ng thng kh b ch ha kh khi dng xng v zicl

khng ti c bt kn. Tho b phao v van kim. Kh LPG c a vo bung phao

theo ng xng c. H thng iu khin ti ng c khng thay i.

Ch to mi b ch ha kh LPG: Trong trng hp ny b ch ha kh LPG c

ch to mi c chiu di bng chiu di ca b ch ha kh xng nguyn thy. ng

knh hng Venturie ca b ch ha kh thay i t 8 n 10,5mm ng vi cc xe gn my

c dung tch xi lanh t 50 n 110cc. Kh LPG c dn n bng cha kh quanh hng

v c ht vo hng qua 6 l xung quanh c ng knh f=1mm. Vic iu chnh lu

lng LPG cung cp cho ng c c thc hin bi van tit lu.

Nguyn l lm vic ca h thng nhin liu LPG nh sau:

Khi bt cng tt in ca xe, van in t 11 nhc ln, (nu s dng van chn

khng 13 thay cho van in t th khi khi ng ng c, van chn khng m) kh LPG

t bnh cha 3 qua van 2, c gim p nh b dn n 1, sau c dn n bnh iu

ha 10 v qua tit lu 7 vo hng b ch ha kh LPG 8. Van tit lu c m ng

b vi bm ga 9 khi thay i ti ng c bng tay ga 6. ch khng ti, van tit lu

ng kn, kh LPG qua l khng ti ca van vo hng. Khi tt kha in (dng ng

c), van in t 11 (hoc van chn khng 13) ng li, khng cho kh LPG thot ra ngoi

m bo an ton. Trong trng hp cn thit, vic ng m ng kh LPG cng c

th c thc hin nh van c kh 12.

Mc nhin liu LPG v p sut kh trong bnh cha c theo di nh ng h o

mc nhin liu 4 v ng h p sut 5.

Nu ci to b ch ha kh dng xng nguyn thy sang dng LPG th kh LPG sau

khi ra khi bnh iu ha c a vo ng xng ca b ch ha kh c, h thng iu

khin ti ng c khng thay i.

46

2.4.2. H thng nhin liu cho xe gn my s dng hai nhin liu

(LPG/xng):

H thng hai nhin liu LPG/xng (hnh 2.19) gm cc b phn sau:

- Bnh cha LPG bng thp, hnh tr, chu c p sut th 34 bar. Bnh c gn ng

h p sut, ng h o mc nhin liu. ng ly LPG c b tr sao cho nhin liu ly ra

khi bnh dng kh. Khi s dng, khng c np nhin liu LPG lng qu 80% th

tch ca bnh.

- Bnh xng t di yn xe, c hnh dng thch hp c th thay vo v tr ca cp

ng ngh.

- Van: s dng cm van ca bnh ga gia dng np ga vo bnh, ly ga ra s dng.

Van an ton cng l mt b phn ca cm van c p sut tc ng 18 bar.

- B dn n: s dng b dn n ca bnh ga gia dng vi lu lng n nh ti a l

2kg/h p sut sau van l 30 mbar.

- Van in t s dng ngun in mt chiu 12 Volts, ch nhc ln khi xe ang s

dng LPG v cng tc in ca xe v tr ng; van v tr ng khi tt kha in hay

khi chuyn sang dng xng. Van in t c th thay th bng mt van chn khng, m

nh chn khng ti hng ca b ch ha kh. Mt khc, phng s c ca cc van

ni trn, mt van xoay c kh thng thng c mc song song vi van in t hay van

chn khng.

- Van chuyn i xng/LPG c gc xoay 90 vi ba v tr: bn phi (dng xng),

bn tri (dng LPG) v chnh gia (kha c hai loi nhin liu).

- Bnh iu ha c dung tch 0,3 lt cung cp n nh lu lng LPG cho ng c,

trnh mch ng trong k np, c bit l khi gia tc.

- Van tit lu l loi van trt, c chc nng cung cp lu lng ga ph hp vi mi

ch lm vic ca ng c t khng ti n ton ti.

- ng dn kh LPG vo hng c a xuyn qua m cch nhit gia ng np v b

ch ha kh xng nguyn thy. B ch ha kh xng vn gi nguyn.

- C cu iu khin ti ng c tc ng ng thi ln con trt ca van tit lu v

qu ga.

47

Hnh 2.19. H thng hai nhin liu LPG/xng

Nguyn l lm vic ca h thng hai nhin liu nh sau:

Khi van 14 v tr tay phi (xng), xng t bnh cha 6 c dn n b ch ha kh

10: xe gn my hot ng nh khi chy bng xng nguyn thy. Khi xoay van 14 v pha

tay tri (LPG), van in t 17 nhc ln, (nu s dng van chn khng 15 thay cho van

in t th khi khi ng ng c, van chn khng m) kh LPG t bnh cha 3 qua van

2, c gim p nh b dn n 1 sau c dn n bnh iu ha 13 v qua van tit

lu 8 vo hng b ch ha kh theo ng dn kh 12. Van tit lu c m ng b

vi qu ga 9 ca b ch ha kh xng 10 khi thay i ti ng c bng tay ga 7. ch

khng ti, van tit lu ng kn, kh LPG qua l khng ti ca van vo hng.

Khi tt kha in (dng ng c), van in t 16 (hay van chn khng 15) ng li,

khng cho kh LPG thot ra ngoi m bo an ton. Vic ng m ng kh LPG

cng c th c thc hin nh van c kh 16 trong trng hp cn thit. Mc nhin liu

LPG v p sut kh trong bnh cha c theo di nh ng h o mc nhin liu 4 v

ng h p sut 5.

48

2.5. c im kt cu phng n cung cp LPG cho t dng hng

Ventury

2.5.1. S nguyn l

Mch xng c kha hon ton (ngt kha xng v chuyn cng tc sang v tr

LPG). LPG lng cao p (7 KG/cm2) t bnh cha i qua van an ton b gim p ha

hi chuyn thnh dng hi LPG p sut 0,5 KG/cm2 v i n b trn. Khi ng c

lm vic, khng kh c ht vo qua b lc kh n b trn kt hp vi hi LPG to

thnh hn hp LPG - Khng kh t l ph hp theo ch lm vic ca ng c.

m bo ng c hot ng tit kim v t cng sut ln nht, h thng cp LPG b tr

thm hai ng cp LPG b sung cho mch lm m ty thuc vo v tr bm ga..

Khi chuyn sang chy xng, m kha xng v chuyn cng tc sang v tr chy xng.

Lc ny ton b h thng LPG b ngt v h thng xng hot ng ging nh nguyn

thy.

Hnh 2.20.S nguyn l h thng cung cp nhin liu song song xng - LPG trn t

Bau gio

Ket nc

ong c

Bnh xang

Van xang ien t

Bo giam ap hoa hi

Van LPG ien t

Bnh LPG

Bo tron

: Chu trnh ien

: Nc

: LPG dang long

: Hi LPG

: Khong kh

: Hon hp LPG - khong kh

Cong tac chuyen oi Hop ieu khien

49

2.5.2. Cc cm chi tit chnh

1. Bnh cha LPG (LPG tank)

C hai loi: loi tr trn v loi bnh xe . Nhim v cha LPG dng lng p sut

cao. Trn bnh c van a cng np LPG, cp LPG v cc van an ton.

Nhin liu LPG thng thng c nn trong bnh c p sut khong 18bar. Bnh

cha dng hnh tr v hai u hnh bn cu, th tch 55 lt. V bnh c ch to bng

thp dy (3-4) mm, thp phi qua x l nhit cho php chu c ko nn v chng nt

ngay c khi b mp lc va

chm. Tt c cc bnh gas

sn xut c kim tra p

sut 45 bar trc khi bn ra

th trng v c s kim tra

v cp giy php s dng ca

cc c quan c chc nng

trong ngnh.

m bo an ton bnh

Gas khng bao gi c

cha 100 % Gas lng, trong

bnh c lp thit b chng

np qua mc cho php (80%

th tch). Trong bnh cha

LPG trng thi hi, p sut hi ny ph thuc vo thnh phn LPG (nhiu Butan hay

Propan) v nhit tn cha. Nhng vi nhit v thnh phn th no th p sut ca

hi LPG vn nh rt nhiu so vi sc chu ng ca bnh.

Hnh 2.21. Bnh cha LPG

Hnh 2.22. Van a cng

50

2. Van in t LPG, van in t xng

Lp trn ng cp LPG v trn ng cp xng. Nhim v l ng, m ng

LPG hoc ng xng.

Van in t c tc dng iu khin, ng m LPG vo t ng ng np ca h

thng cung cp nhin liu. Khi ta m cng tt khi ng my th van ny m cho LPG

thot ra qua ng ng np vo h thng cung cp nhin liu cho ng c. Khi dng li

tt ng c th van in t ng li. Van in t c kt cu:

Hnh 2.24.Kt cu Van in t

1.ng gas vo; 2. van; 3.L xo hi v; 4.Cun dy in; 5.Cht dn hng;

6.ng gas ra.

ng ra LPG

30

40

10

5

40

40

ng vao LPG

25

95 95

16

16

25

8

8

16

Hnh 2.23.Cc van in t

Gas Solenoid-van in t LPG; Petrol Solenoid-van in t xng

51

Van in t c cc c im sau:

- Ph hp vi tt c cc kiu t.

- Bao gm c b lc.

- C kh nng hot ng m bo an ton cao v t tui th lu di.

Van in t hot ng theo nguyn tc cm ng in t, khi ta bt kho khi ng

my s c dng in chy qua cun cm 4, gy ra hin tng cm ng in t iu khin

cc chi tit ca van nng van 2 ln m van cho LPG thot ra, khi ngt dng in di

p lc ca l xo van s ng li.

3. B ha hi-gim p

C nhim v chuyn LPG dng lng thnh dng kh v h p sut LPG dng kh trong

ng cp v mt gi tr nht nh.

Trn hnh 2.26 gii thiu s kt cu b ho hi - gim p. Nhit cn thit cho

ho hi LPG c cung cp nh nc nng t ng ra ca nc lm mt ng c. LPG

lng p sut bnh cha di chuyn qua van in t n hng np 5 v vo bung gim p th nht (A) thng qua van gim p 3. Ti y p sut LPG gim xung cn khong

0,45 0,65 bar. Khi p sut bn trong bung A tng ti gi tr ny, n s truyn qua

bung B, y mng cao su 1 dch chuyn ln trn, thng qua c t 2, mng s nn l xo

v lm cho van gim p ng li, ngn khng cho nhin liu qua ming 4. Khng ch p

sut theo gi tr c nh do s cn bng p sut ca cc bung A, D v l xo ca van 3

cng nh din tch chu p sut pha trn v pha di mng 1.

Sau khi qua bung A, nhin liu tip tc qua bung C thng qua van nh lng 10.

Bung ny c ni thng vi b ch ho kh v hi LPG c ht vo b ch ho kh

khi ng c hot ng. Mng cao su 8 ca bung C c di chuyn bn trong nh sc

ht ng np, s dch chuyn ny lm cho n by m van nh lng 10 hi LPG

Hnh 2.25. B ha hi gim p

52

Hnh 2.28. B cng tc chuyn i

LPG/xng

t bung A vo bung C. Nu vic ht nhin liu tng ln b ch ho kh, th lp tc n

s truyn qua bung C v mng cao su 8, cho php nhiu hi LPG hn i qua ming 11.

Ngc li, nu lc ht b ch ho kh gim xung, do lc y ca l xo 9 iu khin

n by ng dn ming 11, gim lng hi LPG i vo ng c.

Khi ng c khng hot

ng, l xo 9 tc dng ln n

by lm kho cht van nh

lng 10, m bo cho hi LPG

khng i qua ming 11.

4. B cng tc chuyn i

LPG/xng

Nhim v:

- Chuyn i s dng nhin

liu LPG/xng

- Bo mc LPG trong bnh cha

B cng tc c gn gn ch ngi li. N c

3 v tr: chuyn qua chy LPG-Trung gian-Chy

xng.

5. Hp chuyn i m, kha v bo mc LPG

Hnh 2.27. Mt ct ca mt loi b ha hi

Hnh 2.26. S kt cu b ho hi - gim p LPG.

1,8- Mng cao su; 2- C t; 3- Van gim p; 4- Ming van gim p; 5- ng LPG lng vo; 6-

Li lc; 7- Vt iu chnh; 9- L xo; 10- Van nh lng; 11- Ming van nh lng

C

A

D

B

1 2

3

4

5

6789

10

11

ng ga rang ga vao

53

Hp chuyn i m, ng v bo mc LPG gm chc nng: Mch iu khin

chuyn i thc hin m, ng v bo mc LPG (trng hp s dng LPG); cng tc

ng v ngt mch iu khin vi phun v bm xng (trng hp s dng LPG). Mch

iu khin c n bo hiu khi s dng nhin liu LPG do 1 it pht sng mu vng v

bo

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Tai Lieu Mon Hoc Ky Thuat Dong Co Su Dung Nhien Lieu Moi (Repaired)