Methanol-Xuyenlo Diendandaihoc.vn 05321024042011

8/4/2019 Methanol-Xuyenlo Diendandaihoc.vn 05321024042011

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n mn hc GVHD: Thy MaiThanh Phong

Trang 3

LI M U

Cng ngh ha hc l mt trong nhng ngnh ng gp rt ln trong s phttrin ca nn cng nghip nc ta.Trong ngnh sn xut ha cht cng nh s dngsn phm ha hc, nhu cu s dng nguyn liu c tinh khit cao phi ph hp viqui trnh sn xut hoc nhu cu s dng.

Ngy nay, cc phng php c s dng nng cao tinh khit l: chng ct,trch ly, c c, hp thu .Ty theo c tnh sn phm m ta la chn phng phpthch hp. H methanol nc l 2 cu t tan ln hon ton, ta dng phng phpchng ct nng cao tinh khit cho methanol.

n mn hc Qu trnh v Thit b l mt mn hc mang tnh tng hp trong qu

trnh hc tp ca cc k s ho- th c phm tng lai. Mn hc gip sinh vin giiquyt nhim v tnh ton c th v: yu cu cng ngh, kt cu, gi thnh ca mt thitb trong sn xut ho cht - thc phm. y l bc u tin sinh vin vn dngnhng kin thc hc ca nhiu mn hc vo gii quyt nhng vn k thut thc tmt cch tng hp.

Em chn thnh cm n thy Mai Thanh Phong v cc qu thy c b mn My &Thit B, cc bn sinh vin gip em hon thnh n ny. Tuy nhin, trong qu trnhhon thnh n khng th khng c sai st, em rt mong qu thy c gp , ch dn.

Tp HCM, ngy 18.1.2010


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CHNG 1

Tng quan

I. Gii thiu v nguyn liu1. Methanol

Methanol cn gi l ru g, c cng thc ha hc CH3OH. L cht lngkhng mu, d bay hi v rt c. Cc thng s ca methanol:

- Phn t lng: 32,04 g/mol.- Khi lng ring: 0,7918 g/cm3.- Nhit nng chy: -97oC (176K).- Nhit si: 64,5oC ( 337,8K).- nht: 0,59 Ns/m2 20oC.

1.1. ng dng

Methanol c dng lm cht chng ng, lm dung mi, lm nhin liucho ng c t trong, nhng ng dng ln nht l lm nguyn liu sn xut cc hacht khc.

Khong 40% metanol c chuyn thnh forml dehyde, t sn xut racht do, snCc ha cht khc c dn xut t metanol bao gm dimeylete

1.2. Sn xutMethanol c sinh ra t s trao i cht ym kh ca 1 vi loi vi khun.

Kt qu l 1 lng nh hi methanol c to thnh trong khng kh. V sau vi ngykhng kh c cha methanol s b oxy ho bi O2di tc dng ca nh sng chuyn thnhCO2 v H2O theo phng trnh:

2CH3OH + 3O2 2CO2 + 4H2O

Hin nay methanol c sn xut bng cch tng hp trc tip t H2 v CO,gia nhit p sut thp c mt cht xc tc.

2. NcTrong iu kin bnh thng: nc l cht lng khng mu, khng mi, khng

v nhng khi nc dy s c mu xanh nht.Khi ha rn n c th tn ti dng 5 dng tinh th khc nhau.

Tnh cht vt l:- Khi lng phn t : 18 g / mol- Khi lng ring d4

oC : 1 g / ml

- Nhit nng chy : 00C- Nhit si : 1000 C

Nc l hp cht chim phn ln trn tri t (3/4 din tch tri t l nc bin) v rtcn thit cho s sng.

Nc l dung mi phn cc mnh, c kh nng ho tan nhiu cht v l dung mi rtquan trng trong k thut ha hc.

3. Hn hp Methanol-ncTa c bng cn bng lng-hi cho hn hp methanol-nc 1 atm

Bng 1


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Trong sn xut thng dng nhiu loi thit b khc nhau tin hnh chng ct.Tuy nhin yu cu c bn chung ca cc thit b vn ging nhau ngha l din tch b mttip xc pha phi ln, iu ny ph thuc vo mc phn tn ca mt lu cht ny volu cht kia. Nu pha kh phn tn vo pha lng ta c cc loi thp mm, nu pha lngphn tn vo pha kh ta c thp chm, thp phun, y ta kho st 2 loi thng dngl thp mm v thp chm.

- Thp mm: thn thp hnh tr, thng ng pha trong c gn cc mm c cu to khcnhau, trn pha lng v pha hi c cho tip xc vi nhau. T y theo cu to caa, ta c:

- Thp mm chp : trn mm b tr c chp dng trn, xupap, ch s- Thp mm xuyn l: trn mm c nhiu l hay rnh

- Thp chm (thp m): thp hnh tr, gm nhiu bc ni vi nhau bng mt bch hayhn. Vt chm c cho vo thp theo mt trong hai phng php: xp ngu nhin hayxp th t.

So snh u nhc im ca cc loi thp:

Thp chm Thp mm xuyn l Thp mm chpu

im

- Cu to kh n gin.- Tr lc thp.- Lm vic c vi cht lng bn.

- Tr lc tng i thp.- Hiu sut kh cao.

- Kh n nh.- Hiu sut cao.

Nhcim

- Do c hiu ng thnh nn hiusut truyn khi thp.- n nh thp, kh vn hnh.- Kh tng nng sut.- Thit b kh nng n.

- Khng lm vic cvi cht lng bn.- Kt cu kh phc tp.

- C tr lc ln.- Tiu tn nhiuvt t, kt cuphc tp.

Trong bo co ny ta s dng thp mm xuyn l chng ct h methanol - nc.

CHNG 2

Quy trnh cng ngh

1. Thuyt minh quy trnh cng ngh:Hn hp methanol - nc c nng nhp liu methanol 10% (theo phn hi lng),

nhit khong 280C ti bnh cha nguyn liu (13) c bm (1) bm ln bn cao v (2).T c a n thit b trao i nhit vi sn phm y (12). Sau , hn hp c


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gia nhit n nhit si trong thit b un si dng nhp liu (3), ri c a vo thpchng ct (5) a nhp liu.

Trn a nhp liu, cht lng c trn vi phn lng t on luyn ca thp chyxung. Trong thp, hi i t di ln gp cht lng t trn xung. y, c s tip xc vtrao i gia hai pha vi nhau. Pha lng chuyn ng trong phn chng cng xung dicng gim nng cc cu t d bay hi v b pha hi to nn t hi nc c cptrc tip vo y thp li cun cu t d bay hi. Nhit cng ln trn cng thp, nn khihi i qua cc a t di ln th cu t c nhit si cao l nc s ngng t li, cuicng trn nh thp ta thu c hn hp c cu t methsanol chim nhiu nht (c nng 95% phn khi lng). Hi nyi vo thit b ngng t (7) v c ngng t hon ton.Mt phn ca cht lng ngng t c hon lu v thp a trn cng. Phn cn li clm nguin 400C, ri a v bnh cha sn phm nh.

Mt phn cu t c nhit si thp c bc hi, cn li cu t c nhit si caotrong cht lng ngy cng tng. Cui cng, y thp ta thu c hn hp lng hu ht lcc cu t kh bay hi (nc). Hn hp lng y c nng methanol l 1,5% phnkhi lng, cn li l nc. Dung dch lng y i ra khi thp i vo thit b trao i

nhit vi dng nhp liu, ri c a qua bn cha sn phm y (11).H thng lm vic lin tc cho ra sn phm nh l methanol. Sn phm y l ncsau khi trao khi trao i nhit vi dng nhp liu c thi b nhit 600C.Ch thch cc k hiu trong qui trnh:

1. Bn cha nguyn liu2. Bm3. Bn cao v4. Thit b trao i nhit.5. Thit b un si dng nhp liu6. Lu lng k.7. Thp chng8. Thit b un sn phm y

9. Bn cha sn phm nh.10. Thit bngng t sn phm nh11. Thit b lm ngui sn phm nh12. By hi13. Bn cha sn phm y


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CHNG 3

TNH TON S B

I. Cc thng s ban u:- Chn loi thp l thp mm xuyn l. Thit b hot ng lin tc.- Khi chng luyn dung dch metanol th cu t d bay hi l metanol.- Hn hp:

+Methanol: CH3OH, MR = 32 (g/mol)+Nc: H2O, MN = 18 (g/mol)

Nng sut nhp liu: GF = 1000 (l/h) Nng nhp liu: Fx = 10% (kg Methanol/ kg hn hp)

Nng sn phm nh: Px = 95% (kg Methanol/ kg hn hp) Nng d sn phm y: Wx = 1,5% (kg Methanol/ kg hn hp)

Chn: - Nhit nhp liuban u: tB = 28oC

- Nhit sn phm nh sau khi lm ngui: tPR = 60oC

- Nhit dng nc lnh i vo: tV = 28oC

- Nhit dng nc lnh i ra: tR = 40oC

- Trng thi nhp liu vo thp chng ct l trng thi lng si. Cc k hiu:

GF, F: sut lng nhp liu tnh theo kg/h, kmol/h. GP, P: sut lng sn phm nh tnh theo kg/h, kmol/h.GW, W: sut lng sn phm y tnh theo kg/h, kmol/h. L : sut lng dng hon lu, kmol/h.xi, ix : nng phn mol, phn khi lng ca cu t i.

II. Cn bng vt cht:1. Nng phn mol ca Methanol trong thp

0588.018/)1.01(32/1.0

32/1.0

/)1(/

/

NFRF

RFF MxMx

Mxx

9144.018/)95.01(32/95.0

32/95.0/)1(/

/

NPRP

RPP MxMx

Mxx

0085.018/)015.01(32/015.0

32/15.0.0/)1(/

/

NWRW

RWW MxMx

Mxx

T s liu ca bng 1 ta xy dng th t-x,y cho h Methnol- nc


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60

65

70

75

80

85

90

95

100

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0x,y

t0C

hi

long

th 1 th t-x,y cho h Methnol- nc

Do ta chn trng thi nhp liu vo thp chng ct l trng thi lng si nn t th1 trn, ti xF = 0.0588 ta ni suy ra nhit nhp liu vo thp chng ct l

TF = 91,50C

Tra bng 1.249, trang 310, {1} ta c N = 964,25 kg/m3

Tra bng 1.2, trang 9, {1} ta c R = 722.19 kg/m3

Suy ra khi lng ring ca hn hp khi nhp liu vo thp

3

10.072,125,964

1.01

19,722

1.011

N

F

R

F

F

xx

0.933F kg/m3

Suy ra GF = 933,0 kg/h

Ta c 4,1918).1,01(32.1,0).1(. NFRFF MxMxM kg/kmol


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Trang 10

Nn 093,484,19

0,933

F

F

M

GF kmol/h

2. Sut lng mol ca cc dng

- Phng trnh cn bng vt cht cho ton thpF = P + WF.xF = P.xP + W.xW

- Th cc gi tr vo ta c h phng trnh sau

0588,0.093,480085,09144,0

093,48

WP

WP

P = 2,67 kmol/hW= 45,42 kmol/h

- Li c30,3118).95,01(32.95,0).1(. NPRPP MxMxM kg/kmol

21,1818).015,01(32.015,0).1(. NWRWw MxMxM kg/kmol- Suy ra

GP = P.MP = 2,67.31,30 = 83,57 kg/hGW = W.MW = 45,42.18,21 = 827,1 kg/h

3. Cc phng trnh lm vic- T bng s liu 1 ta xy dng th cn bng pha ca h Methanol-nc

p sut 1atm- Vi xF = 0,0588 ta ni suy t th 2 c *Fy = 0,295

+ T s hon lu ti thiu

Rmin 62,20588,0295,0

295,09144,0

*

*

FF

FP

xy

yx

+ T s hon lu lm vic:R = 1,3Rmin + 0,3 = 1,3.2,62 + 0.3 = 3,71

+ Sut lng mol tng i ca dng nhp liu

01,180588,00588,0

0085,09144,0

WF

WP

xx

xxf

Phng trnh ng lm vic ca phn chng:

`031,0.61,40085,0.171,3

01,181.

171,3

01,1871,3

1

1

1

xxxR

fx

R

fRy W

Hay `031,0.61,4 xy

Phng trnh ng lm vic ca phn luyn:

194,0.788,09144,0.171,3

1.

171,3

71,3.

1

1

1

xxx

Rx

R

Ry P

Hay 194,0.788,0 xy


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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

y

th 2: th cn bng pha ca h Methanol-nc p sut 1atm

CHNG 4:


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Trang 12

Thit k ch to thp chng ctI. ng knh thp:

1. Phn luyn:

a. Khi lng ring trung bnh ca pha lng trong phn luyn:

- Nng phn mol trung bnh ca pha lng trong phn luyn:

4866,02

0588,09144,0

2

FPL

xxx mol

- Ni suy t th 1 ta c nhit trung bnh ca pha lng trong phn luynTLL = 73,4

oC- Nng phn khi lng trung bnh ca pha lng trong luyn:

525,02

1,095,0

2

FPL

xxx

- Tra bng 1.249, trang 311, [1]Khi lng ring ca nc 73,4oC: N = 975,76 kg/m

3- Tra bng 1.2, trang 9, [1]

Khi lng ring ca metanol 73,4oC: R = 739,77 kg/m3

- p dng trong cng thc (1.2), trang 5, [1]

310.196,176,957525,01

77,739525,011

N

L

R

L

LL

xx

LL = 835,78 kg/m3

b. Khi lng ring trung bnh ca pha hi trong phn luyn:- Nng trung bnh ca pha hi trong phn luyn:

yL = 0,788xL + 0.194 = 0,788.0,4866 + 0.194 = 0,5775 Nhit trung bnh ca pha hi trong phn luyn: THL = 81,6

oC

- Khi lng mol trung bnh ca pha hi trong phn luyn:MHL = yL. MR + (1 yL). MN = 0,5775.32 + (1 0,5775). 18 = 26,085 kg/kmol- Khi lng ring trung bnh ca pha hi trong phn luyn:

3/8965,0)2736,81(

2734,22

085,26.1mkg

RT

PM

HL

HLHL

- Chn khong cch mm h = 250 mm- Tra hnh 2.2, trang 42,[6]: C = 0,028- Vn tc pha hi i trong phn luyn

smCHL

LLL /855,08965,0

78,835028,0

Lu lng pha hi i trong phn luyn ca thp:

smTM

TRGQ

oP

HLPV /102,03600.273.3,31

)2736,81.(4,22).71,31.(57,833600..

.4,22).1.( 3

ng knh on luyn


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Trang 13

mQ

DL

VL 390,0855,0.14,3

102,0.4

.

.4

2. Phn chng:

a. Khi lng ring trung bnh ca pha lng trong phn chng:- Nng phn mol trung bnh ca pha lng trong phn chng:

034,02

0085,00588,0

2

WFC

xxx (mol metanol/mol hn hp)

- Nhit trung bnh ca pha lng trong phn chng: TLC = 94,6oC

- Nng phn khi lng trung bnh ca pha lng trong luyn:

0575,02

015,01,0

2

WFC

xxx kg metanol/ kg hn hp

- Tra bng 1.249, trang 311, [1]Khi lng ring ca nc 94,6oC: N = 962,78 kg/m

3- Tra bng 1.2, trang 9, [1]

Khi lng ring ca metanol 94,6o

C: R = 719,18 kg/m3

- p dng trong cng thc (1.2), trang 5, [1]

310.059,178,962

0575,01

18,719

0575,011

N

C

R

C

LC

xx

LC = 941,39 (kg/m3).

b. Khi lng ring trung bnh ca pha hi trong phn chng- Nng trung bnh ca pha hi trong phn chng

yC = 4,61xC - 0,031 = 4,61.0,034 0,031 = 0,126 Nhit trung bnh ca pha hi trong phn chng:

THC = 96,4oC

- Khi lng mol trung bnh ca pha hi trong phn chng

MHC = yC. MR + (1 yC). MN = 0,126.32 + (1 0,126). 18 = 19,76 kg/kmol- Khi lng ring trung bnh ca pha hi trong phn chng:

3/566,0)2734,96(

2734,22

76,19.1mkg

RT

PM

HC

HCHC

- Chn khong cch mm h = 250 mm- Vn tc pha hi i trong phn chng:- Tra hnh 2.2, trang 42,[6]: C = 0,028

smCHC

LCC /142,1566,0

39,941028,0

- Lu lng pha hi i trong thp:

smTM

TRGQ

oP

HCPV /106,03600.273.3,31

)2734,96.(4,22).71,31.(57,83

3600..

.4,22).1.( 3

- ng knh on chng


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Trang 15

Vy s mm trong thp l 9 mm, trong + S mm phn chng l 5+ S mm phn luyn l 4

2. Xc nh s mm thc t ca thpa. Hiu sut trung bnh ca thp

+ V tr nhNng phn mol: xP = 0,9144 tsi = 65,8

oC*y = 0,972

bay hi tng i:

250,39144,0).972,01(

)9144,01.(972,0

*).1(

)1.(*

xy

xy

Tra bng 1.104, trang 96, [1] nht ca nc mN = 0,432 cPDng ton 1.18, trang 90, [1] nht ca metanol mR = 0,325 cPCng thc (I.12), trang 84, [1] nht ca hn hp lng: lgmhh = x1lgm1 + x2lgm2

Nn: lgmhh = 0,9144.lg0,325 + (1 0,9144).lg0,432 = -0,478 mhh = 0,333 cP aLmL = 3,250.0,333 = 1,082

Tra hnh IX, trang 171, [2] E = 46%

+ V tr nhp liuNng phn mol: xF = 0,0588 tsi = 91,5

oC*y = 0,305

bay hi tng i:

025,70588,0).305,01(

)0588,01.(305,0*).1(

)1.(*

xyxy

Tra bng 1.104, trang 96, [1] nht ca nc mN = 0,312 cPDng ton 1.18, trang 90, [1] nht ca metanol mR = 0,245 cPCng thc (I.12), trang 84, [1] nht ca hn hp lng: lgmhh = x1lgm1 + x2lgm2



+ V tr y:Nng phn mol: xP = 0,0085 tsi = 98,5

oC*y = 0,052

bay hi tng i:

40,60085,0).052,01(

)0085,01.(052,0

*).1(

)1.(*

xy

xy

Tra bng 1.104, trang 96, [1] nht ca nc mN = 0,289 cP


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Trang 16

Dng ton 1.18, trang 90, [1] nht ca metanol mR = 0,215 cPCng thc (I.12), trang 84, [1] nht ca hn hp lng: lgmhh = x1lgm1 + x2lgm2



+ Hiu sut trung bnh ca thp

%3,433

434146

tbE

b. Chiu cao thp- S mm thc t ca thp

21433,0

9

tb

lt

tt E

NN mm

Trong

12433,05

tb

CttC E

NN mm

9433,0

4

tb

LttL E

NN mm

- Chiu cao ton thp: S dng cng thc IX.54, trang 169, [2]Hthp = Ntt.(hmm + d ) = 21.( 0,25 + 0,002 ) + 0,8 = 6,092 m

- Chn y (np) tiu chun c 25,0t

t

D

hsuy ra ht = 0,25.D = 0,25.0,4 = 0,10 m

- Chn chiu cao g: hg = 25 mm = 0,025 m- Chiu cao y (np): Hn = ht + hg = 0,1 + 0,025 = 0,125 m

Kt lun: Chiu cao ton thp: H = 6,34 m

III. Tr lc thp:Cu to mm l:+ Chn thp mm xuyn l c ng chy chuyn vi:

- Tit din t do bng 8% din tch mm.- ng knh l dl = 3 mm = 0,003 m- Chiu cao g chy trn: hg= 30mm = 0,03 m- Din tch ca 2 bn nguyt bng 20% din tch mm.

- L b tr theo hnh lc gic u.- Khong cch gia 2 tm l bng 15 mm.- B dy mm bng 2 mm- Mm c lm bng thp khng g X18H10T.

+ S l trn 1 mm:

N =22

003,0

4,0.08,008,0

%8

l

t

l

m

d

D

S

S= 1422 l

Gi a l s hnh lc gic.


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Trang 17

p dng cng thc (V.139), trang 48, [2]: N = 3a(a-1) +1Gii phng trnh bc 2 a = 22,3 23 N = 1519 lS l trn ng cho: b = 2a - 1 = 43 l

2. Trlc ca a kh:p dng cng thc (IX.140), trang 194, [2]:

2

.'P H

2

k

i vi a c tit din t do bng 10% din tch mm th x = 1,822.1. Phn luyn

Vn tc hi qua l: 15,1008,0

812,0

%8' LL

m/s

Nn: DPkL = 05,842

8965,0.15,10.82,1

2

N/m2

2.2. Phn chngVn tc hi qua l: 55,10

08,0

844,0

%8' CC

m/s

Nn: 33,572

566,0.55,10.82,1

2

kCP N/m2

3. Tr lc do sc cng b mtV a c ng knh l > 1mm Ap dng cng thc (IX.142), trang 194, [2]:

2lolo d08,0d3,1

4P

3.1. Phn luyn

Ti nhit trung bnh ca pha lng trong phn luyn TLL = 73,4oC th: Tra bng 1.249, trang 310, [1] Sc cng b mt ca nc sNL = 0,6334 N/m Tra bng 1.242, trang 300, [1] Sc cng b mt ca ru sRL = 0,0184 N/mAp dng cng thc (I.76), trang 299, [1]:

21

21

21

111

0179,00184,06334,0

0184,0.6334,0

LL N/m

36,18003,008,0003,03,1

0179,042

LP N/m

2

3.2. Phn chngTnh ton tng t nh phn luynTi nhit trung bnh ca pha lng trong phn luyn TLL = 94,6

oC th: Tra bng 1.249, trang 310, [1] Sc cng b mt ca nc sNL = 0,5964 N/m Tra bng 1.242, trang 300, [1] Sc cng b mt ca ru sRL = 0,0160 N/mAp dng cng thc (I.76), trang 299, [1]:


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Trang 18

21

21

21

111

0126,00160,05964,0

0160,0.5964,0

LL N/m

92,12003,008,0003,03,1

0126,042

LP N/m

2

4. Tr lc thy tnh do cht lng trn a to ra:Ap dng cng thc trang 68, [3]

DPb = 1,3hbKrLgVi: hb = hg+ Dhl

3/2

g

Ll

KL85,1

Qh

Trong :

Lg: chiu di ca g chy trn, mK = rb/rL : t s gia khi lng ring cht lng bt v khi lng ring ca cht

lng, ly gn bng 0,5.

L

LLL

MnQ

. : sut lng th tch ca pha lng, m3/s.

Tnh chiu di g chy trn:

Ta c: Squt - SD = Sbn nguyt

22

2

%20

2cos

2sin

2

1.2

2RRR

R

a - sina = 0,2pDng php lp a = 1,627 rad = 93,32o

Nn Lg= mDt 290,0)2

32,93sin(.4,0)

2sin(.

4.1. Phn luyn:Khi lng mol trung bnh ca pha lng trong phn luyn:MLL = 0,4866.32 + (1 0,4866).18 = 24,81 kg/kmolSut lng th tch ca pha lng trong phn luyn:


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Trang 19

QLL =510.17,8

3600.78,835.30,31

81,24.71,3.57,83

.

.. LLP

LLP

M

MRG

m3/s

0045,05,0.290,0.85,1

10.17,83/25

lLh m

Cho ta: DPbL = 1,3.(hg+ DhlL).KrLLg= 1,3.(0,03 + 0,0045). 0,5. 835,78. 9,81 = 183,86 N/m2

4.2. Phn chngTnh ton tng t nh phn luynKhi lng mol trung bnh ca pha lng trong phn luyn:MLC = 0,034.32 + (1 0,034).18 = 16,54 kg/kmolSut lng th tch ca pha lng trong phn luyn:

QLC = 510.83,43600.39,941.30,31

54,16.71,3.57,83

.

.. LCP

LCP

M

MRG

m3/s

0032,05,0.290,0.85,1

10.83,4

3/25

lCh m

Cho ta: DPbC = 1,3.(hg+ DhlC).KrLCg= 1,3.(0,03 + 0,0032). 0,5. 941,39. 9,81 = 199,29 N/m2

5. Tng tr lc thu lc ca thpTng tr lc ca 1 mm trong phn luyn ca thp l:

DPL = DPkL + DPsL + DPbL = 84,05 + 18,36 + 183,86 = 286,27 N/m2

Tng tr lc ca 1 mm trong phn chng ca thp l:DPC = DPkC + DPsC + DPbC = 57,33 + 12,92 + 199,29 = 269,54 N/m

2Kim tra hot ng ca mm:

- Kim tra li khong cch mm h = 0,25m m bo cho iu kin hotng bnh thng ca thp: h >

g

P

L

8,1 ( trang 70, [3] )

Vi cc mm trong phn luyn tr lc thu lc qua 1 mm ln hn tr lc thu lcca mm trong phn chng, ta c:

063,018,9.78,835

27,2868,18,1

g

P

LL

L

m

iu kin trn c tha.

-Kim tra tnh ng nht ca hot ng ca mm.T cng thc trang 70, [3] Ta c vn tc ti thiu qua l ca pha hi vmin cho

cc l trn mm u hot ng:vmin = 0,67 822,8

8965,0.82,1

)0045,003,0.(78,835.81,967,0

HL

bLLLhg

m/s < 10,15 m/s

Cc l trn mm u hot ng.Kt lun:

Tng tr lc thy lc ca thp:DP = NttL.DPL + NttCDPC = 9. 286,27 + 14. 269,54 = 6350,0 (N/m

2)


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Trang 20

6. Kim tra ngp lt khi thp hot ng:Khong cch gia 2 mm: Dh = 250 mmB qua s to bt trong ng chy chuyn, chiu cao mc cht lng trong ng chy

chuyn ca mm xuyn l c xc nh theo biu thc (5.20), trang 120, [3]:hd = hg + Dhl + DP + hd ,mm.cht lng

Trong :+ hg: chiu cao g chy trn ,mm+ Dhl : chiu cao lp cht lng trn mm ,mm+ DP: tng tr lc ca 1 mm ,mm.cht lng+ hd : tn tht thy lc do dng lng chy t ng chy chuyn vo mm,

c xc nh theo biu thc (5.10), trang 115, [3]:2

d

L'd

S.100

Q.128,0h

,mm.cht lng+ QL: lu lng ca cht lng (m

3/h).+ Sd : tit din gia ng chy chuyn v mm.

Sd = 0,8 . Smm = 0,8.4 .0,42 = 0,10 m2

thp khng b ngp lt khi hot ng th: hd 2

1Dh = 125 mm

6.1. Phn luynDhlL = 0,0045. 1000 = 4,5 mm

DPL = 92,34100081,9.78,835

27,2861000

27,286

gLLmm.cht lng

4

252

' 10.11,110,0.1003600.10.17,8

.128,0.100

.128,0

d

LLLd S

Qh mm.cht lng

Nn: hdL = 30 + 4,5 + 34,92 + 1,11.10-4

= 69,42 mm < 125 mmVy: Khi hot ng th mm phn luyn s khng b ngp lt.

6.2. Phn chngDhlC = 0,0032. 1000 = 3,2 (mm)

DPC = 02,40100081,9.39,941

54,2691000

54,269

gLCmm.cht lng

5

252

' 10.89,310,0.100

3600.10.83,4.128,0

.100.128,0

d

LCCd S

Qh mm.cht lng

Nn: hdC = 30 + 3,2 + 40,02 + 3,89.10-5 = 73,22 mm < 125 mm

Vy: Khi hot ng th mm phn chng s khng b ngp lt.Kt lun: Khi hot ng thp s khng b ngp lt.

IV. B dy thp :1. Thn thpV thp hot ng p sut thng nn ta thit k thn hnh tr bng phng php hn

h quang in, kiu hn gip mi 2 pha. Thn thp c ghp vi nhau bng cc mi ghpbch.


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m bo cht lng ca sn phm ta chn thit b thn thp l thp khng g mX18H10T.

1.1. Cc thng s cn tra v chn phc v cho qu trnh tnh tonNhit tnh ton: t = tmax= 100

oCp sut tnh ton: v thp hot ng p sut thng nn: P = Pthy tnh + DP

Khi lng ring trung bnh ca pha lng trong ton thp:

rL = 85,8882

78,83539,941

2

LCLL kg/m3

Nn: P= rLgH + DP = 888,58. 9,81. 5,17 + 6350,0 = 51416.7 N/m2

= 0,0514 N/mm2H s b sung do n mn ha hc ca mi trng:

V mi trng c tnh n mn v thi gian s dng thit b l trong 20 nm Ca = 1 mm

ng sut cho php tiu chun:V vt liu l X18H10T [s]* = 142 (N/mm2) (Hnh 1.2, trang 16, [7])

H s hiu chnh:

V thit b khng bc lp cch nhit h = 1 (trang 26, [7])ng sut cho php: [s] = h [s]* = 142 (N/mm2)H s bn mi hn:

V s dng phng php hn h quang in, kiu hn gip mi 2 pha jh = 0,95 (Bng XIII.8, trang 362, [2])

1.2. Tnh b dy

Ta c: 84,244395,00552,0

142][hP

> 25

S = 077,095,01422

0514,0400

][2

h

tPD

mm S + Ca = 0,077 + 1 = 1,077 mm

Quy trn theo chun: S = 2 mm (Bng XIII.9, trang 364, [2])B dy ti thiu: Smin = 2 mm (Bng 5.1, trang 94, [7]) B dy S = 2 mm

1.3. Kim tra bn

iu kin: 1,0

aCS 1,010.5,2400

12 3 (tha)

Nn: 673,0)12(400

)12(95,01422

)(

)(][2][

at

at

CSD

CSDP

> P = 0,09 (tha)

Kt lun: S = 2 mm

2. y v np:Chn y v np c dng hnh ellip tiu chun, c g, lm bng thp X18H10TChn b dy y v np bng vi b dy thn thp: S = 3 mm.Kim tra iu kin:


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Trang 22

P)CS(R

)CS(][2]P[

125,0D

CS

at

ah

t

a

V y v np c hnh ellip tiu chun vi 25,0t

t

Dh Rt = Dt

iu kin trn c tha nh kim tra phn thn thp.

Kt lun: Kch thc ca y v np:ng knh trong: Dt = 400 mmht = 100 mmChiu cao g: hg= 25 mmB dy: S = 2 mmDin tch b mt trong: Sb mt = 0,2 m

2 (Bng XIII.10, trang 382, [2])

V. B dy mm :1. Cc thng s cn tra v chn phc v cho qu trnh tnh ton

Nhit tnh ton: t = tmax = 100 (oC)

p sut tnh ton: P = Pthy tnh + PgChn b dy g chy trn l 3mm.Th tch ca g chy trn: V = 0,29.0,03.0,003= 2,61.10-5 m3Tra bng XII.7, trang 313, [6]: Khi lng ring ca thp X18H10T l: rX18H10T = 7900 kg/m

3Khi lng g chy trn: m = V.rX18H10T = 2,61.10

-5.7900 = 0,2062 kgp sut do g chy trn tc dng ln mm trn

60,11

44,0.14,3

81,9.2062,0

4

22

t

g

D

mgP

N/m2

Khi lng ring ca cht lng ti y thp:Ta c xW = 0,0085 suy ra TW = 98,5

oC- Tra bng 1.249, trang 311, [1]

Khi lng ring ca nc 98,5oC: N = 959,22 kg/m3

- Tra bng 1.2, trang 9, [1]Khi lng ring ca metanol 98,5oC: R = 715,08 kg/m

3- p dng trong cng thc (1.2), trang 5, [1]

310.045,122,959

0085,01

08,715

0085,011

N

W

R

W

LW

xx

Suy ra rLW = 956,44 kg/m3

p sut thy tnh:Pthy tnh = rLWg(hg+ DhlC)

= 956,44. 9,81. (0,03 + 0,0045)= 326,75 N/m2

P = 326,75 + 11,06 = 337,81 N/m2


21/54


Trang 23

H s b sung do n mn ha hc ca mi trng:Thi gian s dng thit b l trong 20 nm

Ca = 1 mmng sut cho php tiu chun:V vt liu l X18H10T [s]* = 142 N/mm2 (Hnh 1.2, trang 16, [7])

H s hiu chnh: h = 1 (Trang 19, [7])ng sut cho php: [s] = h [s]* = 142 N/mm2Mun n hi: E = 20.106 N/cm2 (Bng 2.12, trang 45, [7])

H s Poisson: m = 0,33 (Bng XII.7, trang 313, [2])H s iu chnh: jb = 0,571

2. Tnh b dy:i vi bn trn c ngm kp cht theo chu vi:

ng sut cc i vng chu vi:2

max 16

3

S

DP (Cng thc 6.36, trang 100, [8])

i vi bn c c l: ][163

2

maxmax

SDP

bbl

S 354,0571,014216

10.81,3373400

][16

3 6

bt

PD

mm

Nn: S + Ca = 1,354 mmChn S = 2 mm

Kim tra iu kin bn:

vng cc i tm:T

o D

PRW

64

4

(Cng thc 6.35, trang 100, [8])

i vi bn c c l:Tbb

olo D

PRWW 64

4

Vi:)1(12 2

3

ESDT

3

24

3

24 )1(.

16

3

64

)1(12

ES

PR

ES

PRWW

bbb

olo

m bo iu kin bn th: Wlo < S

050,02200000571,0

)33,01(20010.811,337.

163

3

246

loW < 2S

1,0

B dy S chn tha iu kin.Vy: S = 2 mm

VI. Bch ghp thn y v np :Mt bch l b phn quan trng dng ni cc phn ca thit b cng nh ni cc b

phn khc vi thit b. Cc loi mt bch thng s dng:Bch lin: l b phn ni lin vi thit b (hn, c v rn). Loi bch ny ch yu

dng thit b lm vic vi p sut thp v p sut trung bnh.


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Trang 24

Bch t do: ch yu dng ni ng dn lm vic nhit cao, ni cc b bngkim loi mu v hp kim ca chng, c bit l khi cn lm mt bch bng vt liu bn hnthit b.

Bch ren: ch yu dng cho thit b lm vic p sut cao.Chn bch c ghp thn, y v np lm bng thp CT3, cu to ca bch l bch lin

khng c.

Tra bng XIII.27, trang 417, [2],ng vi Dt = f = 400 (mm) v p sut tnh ton P =0,055 (N/mm2) chn bch c cc thng s sau:

Dt D Db Dl Do hBu lng

db Z(mm) (ci)

400 515 475 450 411 20 M16 20

Tra bng IX.5, trang 170, [2], vi Dh = 250 mm khong cch gia 2 mt bch l 1000

mm v s mm gia 2 mt bch l 4. S mt bch cn dng ghp l: 21/4 + 2 = 8 bch kn ca mi ghp bch ch yu do vt m quyt nh. m lm bng cc vt liu

mm hn so vi vt liu bch. Khi xit bu lng, m b bin dng v in y ln cc chg gh trn b mt ca bch. Vy, m bo kn cho thit b ta chn m l dyaming, c b dy l 3mm.

VII. Chn thp :1. Tnh trng lng ca ton thp:

Tra bng XII.7, trang 313, [2]:

Khi lng ring ca thp CT3 l: rCT3 = 7850 kg/m3

Khi lng ca mt bch ghp thn:

mbch ghp thn = 97,12785002,040,0515,04

...4

223

22

CTt hDD kg

Khi lng ca mt mm:

mmm = THXmmtD 10182 %)10%8%100(

4

=

4

.0.402.0,002.0,82.7900 = 1,63 kg

Khi lng ca thn thp:

mthn =4

.(D2ng D

2t).Hthn . rX18H10T = 56,1007900.042,5.40,0404,0.

422

kg

Khi lng ca y (np) thp:my(np) = Sb mt .dy . rX18H10T = 0,20 . 0,002 . 7900 = 3,16 kgKhi lng ca ton thp:

m = 8 mbch ghp thn + 21 mmm + mthn + 2 my(np)= 8.12,97 + 21.1,63 + 100,56 + 2.3,16 = 243,43 kg

2. Tnh chn thp:Chn chn : thp c trn bn chn.Vt liu lm chn thp l thp CT3.

Ti trng cho php trn mt chn: Gc = 01,5974

81,9.43,243

44

mgPN


23/54


Trang 25

m bo an ton cho thit b, ta chn: Gc = 1000N

Tra bng XIII.35, trang 437, [2] chn chn c cc thng s sau:

L B B1 B2 H h s l d70 60 60 90 150 105 4 30 14

Khi lng mt chn : mchn = 3,32 kg

VIII. Tai treo thp :Chn tai treo: tai treo c gn trn thn thp gi cho thp khi b dao ng trong

iu kin ngoi cnh.Chn vt liu lm tai treo l thp CT3.Ta chn bn tai treo, ti trng cho php trn mt tai treo: Gt = Gc = 1000

(N).

Tra bng XIII.36, trang 438, [2] chn tai treo c cc thng s sau:

L B B1 H S l a d80 55 70 125 4 30 10 14

Khi lng mt tai treo: mtai treo = 0,53 kg

IX. Ca ni ng dn vi thit b- bch ni cc b phn ca thit b vng dn:

ng dn thng c ni vi thit b bng mi ghp tho c hoc khng tho c.Trong thit b ny, ta s dng mi ghp tho c.

i vi mi ghp tho c, ngi ta lm on ng ni, l on ng ngn c mt

bch hay ren ni vi ng dn:Loi c mt bch thng dng vi ng c ng knh d > 10mm.Loi ren ch yu dng vi ng c ng knh d 10mm, i khi c th d ng vi d

32mm.ng dn c lm bng thp X18H10T.Bch c lm bng thp CT3 , cu to ca bch l bch lin khng c.

1. ng nhp liu:Khi lng ring ca hn hp: rF = 933,0 kg/m

3Chn loi ng ni cm su vo thit b.Chn vn tc cht lng trong ng ni l vF = 1 m/sng knh trong ca ng ni:

Dy = 0188,010,9333600

0,933.43600

.4

FF

F

vG m

Chn ng c Dy = 20 mmTra bng XIII.26, trang 409, [2] Cc thng s ca bch ng vi P = 0,055 N/mm2 l:

Dy Dn D Dd Dl h Bu lng


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Trang 26

db Z(mm) (ci)

20 25 90 65 50 12 M10 4

2. ng hi nh thp:- Nng trung bnh ca pha hi nh thpyP = xP = 0,9144

Nhit trung bnh ca pha hi nh thp: THP = 67,8oC

- Khi lng mol trung bnh ca pha hi trong phn luyn:MHL = yL. MR + (1 yL). MN = 0,9144.32 + (1 0,9144). 18 = 30,80 kg/kmol

- Khi lng ring trung bnh ca pha hi trong phn luyn:

3/101,1)2738,67(

273

4,2280,30.1

mkgRT

PM

HL

HLHL

Chn vn tc hi ra khi nh thp l vHD = 50 m/sng knh trong ca ng ni:

Dy = 023,050.14,3.101,1.3600

57,83.4

3600

.4

HDHD

HD

v

G

m

Chn ng c Dy = 25 mmTra bng XIII.32, trang 434, [2] Chiu di on ng ni l = 90 mmTra bng XIII.26, trang 409, [2] Cc thng s ca bch ng vi P = 0,055 N/mm2 l:

Dy Dn D Dd Dl hBu lng

db Z(mm) (ci)

25 32 100 75 60 12 M10 43. ng hon lu:- Nng trung bnh ca pha lng nh thp

xP = 0,9144 Nhit trung bnh ca pha hi nh thp: THP = 65,8

oC- Tra bng 1.249, trang 311, [1]

Khi lng ring ca nc 65,8oC: N = 981,2 kg/m3

- Tra bng 1.2, trang 9, [1]Khi lng ring ca metanol 65,8oC: R = 752,8 kg/m

3- p dng trong cng thc (1.2), trang 5, [1]

3

10.30,12,981

95,01

8,752

95,011

N

C

R

C

LC

xx

LC = 768,1 kg/m3

Chn loi ng ni cm su vo thit b.Chn vn tc cht lng trong ng ni l vLD = 0,5 m/sng knh trong ca ng ni:

Dy = 017,05,01,7683600

71,3.57,83.4

3600

.4

LPLP

LP

v

Gm


25/54


Trang 27

Chn ng c Dy = 20 mmTra bng XIII.26, trang 409, [2] Cc thng s ca bch ng vi P = 0,055 N/mm2 l:


db Z(mm) (ci)

20 25 90 65 50 12 M10 4

4. ng hi y thp:- Nng trung bnh ca pha hi y thp

yW = xW = 0,0085 Nhit trung bnh ca pha hi y thp: THP = 99,6

oC- Khi lng mol trung bnh ca pha hi trong phn luyn:

MHW = yW. MR + (1 yW). MN = 0,0085.32 + (1 0,0085).18 = 18,12 kg/kmol- Khi lng ring trung bnh ca pha hi trong phn luyn:

3

/593,0)2736,99(273

4,22

12,18.1

mkgRT

PM

HW

HW

HW

Chn vn tc hi vo y thp l vHW = 120 m/sng knh trong ca ng ni:

Dy = 064,0120..593,0.3600

1,827.4

3600

.4

HWHW

HW

v

Gm

Chn ng c Dy = 70 mmTra bng XIII.32, trang 434, [2] Chiu di on ng ni l = 110 mmTra bng XIII.26, trang 409, [2] Cc thng s ca bch ng vi P = 0,055 (N/mm2) l:


db Z(mm) (ci)

70 76 160 130 110 14 M12 4

5. ng dn lng ra khi y thp:- Nng trung bnh ca pha lng y thp

xW = 0,0085 Nhit ca pha lng y thp: TLW = 98,5

oC- Tra bng 1.249, trang 311, [1]

Khi lng ring ca nc 98,50C: N = 959,2 kg/m3

- Tra bng 1.2, trang 9, [1]

Khi lng ring ca metanol 98,5oC: R = 716,8 kg/m3- p dng trong cng thc (1.2), trang 5, [1]

310.05,12,959

015,018,716

015,011

N

W

R

W

LW

xx

LW = 954,4 kg/m3

Chn vn tc cht lng trong ng ni l vLW = 0,5 m/sng knh trong ca ng ni:


26/54


Trang 28

Dy = 025,05,0..4,954.3600

1,827.4

3600

.4

LWLW

LW

v

Gm

Chn ng c Dy = 25 mmTra bng XIII.32, trang 434, [2] Chiu di on ng ni l = 90 mm

Tra bng XIII.26, trang 409, [6] Cc thng s ca bch ng vi P = 0,055 N/mm2 l:


db Z(mm) (ci)

25 32 100 75 60 12 M10 4


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Trang 29

CHNG 5:

Tnh thit b ph

I. THIT B UN SI Y THP :Chn thit b un si y thp l ni un Kettle.

ng truyn nhit c lm bng thp X18H10T, kch thc ng 38 x 3:ng knh ngoi: dn = 38 mm = 0,038 mB dy ng: t = 3 mm = 0,003 mng knh trong: dt = 0,032 m

Hi t l hi nc 2,0 at i trong ng 38 x 3. Tra bng 1.251, trang 314, [1]:Nhit ha hi: OH2r = rn = 2208 kJ/kg

Nhit si: OH2t = tn = 119,6oC

Dng sn phm ti y c nhit :Trc khi vo ni un (lng): tS1 = 98,5

oCSau khi c un si (hi): tS2 = 99,6 oC

1. Sut lng hi nc cn dng:Cn bng nhit cho ton thp:

Q + GFhFS = (R+1) GDrD + GDhDS + GWhWS + QmGi s Qm = 0,05Q 0,95Q = (R+1) GDrD + GD(hDS hFS) + GW(hWS hFS)

hFS = cF.tFS = [ AFNF c)x1(cx ]tFS

hWS = cW.tWS = [ AWNW c)x1(cx ]tWS

hPS

= cP.t

PS= [

APNPcxcx )1( ]t

PS

rD = ADND r)x1(rx

Vi xF = 0,0588 tFS = 91,5oC

xW = 0,0085 tWS = 98,5oC

xP = 0,9144 tPS = 65,8oC

1.1. Nhit dung ring:Tra bng 1.249, trang 310, [1] Nhit dung ring ca nc 91,5oC = 4,210 kJ/kg.K Nhit dung ring ca nc 98,5oC = 4,218 kJ/kg.K Nhit dung ring ca nc 65,8oC = 4,184 kJ/kg.K

Tra bng 1.154, trang 172, [1] Nhit dung ring ca methanol 91,5oC = 2,920 kJ/kg.K Nhit dung ring ca methanol 98,5oC = 2,958 kJ/kg.K Nhit dung ring ca methanol 65,8oC = 2,788 kJ/kg.K

1.2. Enthalpy:


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Trang 30

hFS = (0,1. 2,920 + (1 - 0,1). 4,210). 91,5 = 373,41 kJ/kghWS = (0,0085. 2,958 + (1 - 0,0085). 4,218). 98,5 = 414,42 kJ/kghPS = (0,9144. 2,788+ (1 - 0,9144). 4,184). 65,8 = 191,31 kJ/kg

1.3. Nhit ha hi:Tra bng 1.250, trang 312, [1] Nhit ha hi ca nc 65,8oC = rN = 2344,8kJ/kgDng ton 1.65, trang 255, [1] Nhit ha hi ca methanol 65,8oC = rR = 330,5 Kcal/kg = 1383,74 kJ/kgNn: rP = APNP rxrx )1(

= 0,95. 2344,8 + (1 - 0,95). 1383,74 = 2296,75 kJ/kg

1.4. Tnh lng hi nc cn dng:Nhit lng cn cung cp:

Q =95,0

)()()1( FSWSWFSPSPPP hhGhhGrGR

=95,0

)41,37342,414.(1,827)41,37331,191.(57,8375,2296.57,83).171,3(

= 971300.88 kJ/h

Nu dng hi nc bo ha (khng cha m) cp nhit th: Q = OH2G . OH2r

Tra bng 1.251, trang 314, [1] Nhit ha hi ca nc 2,0 at = OH2r = 2208 kJ/kg

Vy:2208

88,971300

2

2

OH

OH r

QG = 440,0 kg/h

2.

Hiu s nhit trung bnh:Chn kiu truyn nhit ngc chiu, nn:

6,996,119

5,986,119ln

)6,996,119()5,986,119(log

t = 20,545 K

3. H s truyn nhit:H s truyn nhit K c tnh theo cng thc nh i vi tng phng:

S

t

n

1r

1

1K

,W/m2.K)

Vi: n : h s cp nhit ca hi t,W/m2.K. S : h s cp nhit ca sn phm y, W/m2.K. rt : nhit tr qua thnh ng v lp cu.

3.1.Nhit ti qua thnh ng v lp cu:

t

2w1wt

r

ttq

, W/m2

Trong :


29/54


Trang 31

tw1 : nhit ca vch tip xc vi hi t (trong ng),oC

tw2 : nhit ca vch tip xc vi sn phm y (ngoi ng),oC

21

t

tt rrr

B dy thnh ng: t = 0,003 mH s dn nhit ca thp khng g:t = 16,3 W/mK (Bng XII.7, trang 313, [6])

Nhit tr lp bn trong ng:r1 = 1/5800 m

2.K/W (Bng 31, trang 419, [4])Nhit tr lp cu ngoi ng:

r2 =1/5800 m2.K/W

Nn: rt = 5,289.10-4 m2.K/W

3.2.Xc nh h s cp nhit ca dng sn phm y ngoi ng:p dng cng thc (V.89), trang 26, [2]:

S = 7,77 . 10-2. 0,37s

0.11745,0

0,775,00,3330,033

h

h

T.c.q...r.

Nhit si trung bnh ca dng sn phm ngoi ng:

2

6,995,98

221

SSS

ttt = 99,05 oC

TS = 99,05 + 273 = 372,05 KTi nhit si trung bnh th:- Khi lng ring ca pha hi trong dng sn phm ngoi ng:

05,372.273

4,2212,18.1

S

HWh RT

PM = 0,594 kg/m3

- Khi lng ring ca nc:N = 959,2kg/m

3 (Bng 1.249, trang 310, [1])- Khi lng ring ca methanol:

R = 715,0 kg/m3 (Bng 1.2, trang 9, [1])

Nn:

2,959

015,010,715

015,011

A

W

R

W xx

1,05.10-3

= 954,3 kg/m3- nht ca nc:

N = 2,85.10-4 N.s/m2 (Tra bng 1.104, trang 96, [1])

- nht ca methanol:A = 2,45.10

-4 N.s/m2 (Dng ton 1.18, trang 90, [1])S dng cng thc (I.12), trang 84, [1]suy ra nht ca hn hp lng:

lgmhh = x1lgm1 + x2lgm2Nn: lgmhh = 0,0085.lg(2,45.10

-4) + (1 0,0085).lg(2,85.10-4) mhh = 2,846.10

-4 N.s/m2

- H s dn nhit ca nc:N = 0,680 W/mK (Bng 1.249, trang 310, [5])

- H s dn nhit ca methanol:


30/54


Trang 32

R = 0,188 W/mK (Bng 1.130, trang 134, [5])p dng cng thc (1.33), trang 123, [5]):

= )).(1.(.72,0)1.(. RNWWWNWR xxxx = 0,667 W/mK

- Nhit dung ring ca nc:cN = 4219,2 J/kgK (Bng 1.249, trang 310, [1])- Nhit dung ring ca methanol:

cR = 2906,0 J/kgK (Bng 1.154, trang 172, [1])Nn: c = cR Wx + cN. (1 - Wx ) = 4199,3 J/kgK

- Sc cng b mt ca nc:N = 0,59022 N/m (Bng 1.249, trang 310, [1])

- Sc cng b mt ca methanol:A = 0,01578 N/m (Bng1.242, trang 300, [1])

Nn:AN

AN

= 0,0158 N/m

- Nhit ha hi ca nc:rN = 2262,2 kJ/kg (Bng1.250, trang 312, [5])

- Nhit ha hi ca methanol:rR = 1032,3 kJ/kg (Ton 1.65, trang 255, [5])

Nn: r = rR Wx + rN.(1 - Wx ) = 2243,8 kJ/kg

3.3.Xc nh h s cp nhit ca hi t trong ng:p dng cng thc (3.65), trang 120, [4]:

4

trW1nn

3n

2nn

n

).dt-.(t

.g..r725,0

Dng php lp: chn tW1 = 119,4oC

Nhit trung bnh ca mng nc ngng t: tm =

2

tt W1n 119,5 oC

Ti nhit ny th:- Khi lng ring ca nc: n = 943,4 kg/m3- nht ca nc: n = 2,33.10

-4 N.s/m2- H s dn nhit ca nc: n = 0,685 W/mK

Nn: n = 31342 W/m2K qn = n (tn tW1) = 6268,4 W/m

2 qt = qn = 6268,4 W/m

2 (xem nhit ti mt mt l khng ng k)

tw2 = tw1 - qtrt = 116,08 oCS = 362,84 W/m

2K (vi q = qt) qS = S (tW2 tS) = 6126,5 W/m

2Kim tra sai s:

=n

Sn

q

qq 100% = 2,26% < 5% (tha)

Kt lun: tw1 = 119,4oC v tw2 = 116,08

oC


31/54


Trang 33

3.4.Xc nh h s truyn nhit:

84,326

110.289,5

31342

11

4

K = 301,5 W/m2K

4. B mt truyn nhit:B mt truyn nhit c xc nh theo phng trnh truyn nhit:

F =545,02.5,013.3600

1000.713009. log

tK

Q = 43,56 m2

5. Cu to thit b:Chn s ng truyn nhit: n = 217 ng. ng c b tr theo hnh lc gic u.

- Chiu di ng truyn nhit: L =

2tn dd

n

F

= 1,83 m chn L = 2 m

Tra bng V.II, trang 48, [2] S ng trn ng cho: b = 17 ng- Bc ng: t = 1, 2dn = 0,046 m- ng knh trong ca thit b(p dng cng thc (V.140), trang 49, [2])

D = t.(b-1) +4dn= 0,934 m

II. THIT B NGNG T SN PHM NHChn thit b ngng t v ng loi TH, t nm ngang.ng truyn nhit c lm bng thp X18H10T, kch thc ng 38 x 3:- ng knh ngoi: dn = 38 mm = 0,038 m- B dy ng: t = 3 mm = 0,003 m

- ng knh trong: dtr = 0,032 mChn:

-Nc lm lnh i trong ng vi nhit vo tV = 28oC v nhit ra tR = 40

oC.- Dng hi ti nh i ngoi ng vi nhit ngng t tngng = 65,8

oC

1. Sut lng nc lm lnh cn dng :Cn bng nhit: Qnt = (R + 1).GP.rP = GN.cN.(t2 t1)rD: nhit lng ring ca hi nh thp:

rD = x .rR + (1 - x ).rNrR, rN : nhit lng ring ca cu t ru v nc nh, J/kg.x phn khi lng ca cu t ru trong pha hi nh.

Tra bng 1.213, trang 256, [1] :rR = 675,2 kcal/kg = 2826,25 kJ/kg

Tra bng 1.250, trang 312, [1] :rN = 559,5 kcal/kg = 2341,96 kJ/kg

Suy ra: rD = 0,95.2826,25 + (1 - 0,95).2341,96 = 2801,1 kJ/kg Qnt = (1 + 3,71).83,57.2801,1 = 1102,55 kWNn: Qnt = (R + 1).DcP = 1102,55 kW


32/54


Trang 34

Lng nc cn dng: 4,79221)2840.(5,4175

10.3600.55,1102

.(

3

)12

ttc

QG

N

ntN kg/h

Nhit dung ring ca nc cN c o nhit 342

4028

2

RVf

ttt oC

2. Hiu s nhit trung bnh :Chn kiu truyn nhit ngc chiu, nn:

408,65288,65

ln

)408,65()288,65(log

t = 31,42 K

3. H s truyn nhit:H s truyn nhit K c tnh theo cng thc:

ngng

t

n

1r

1

1K

,W/m2.K

Vi:n : h s cp nhit ca dng nc lnh ,W/m

2.Kngng : h s cp nhit ca dng hi ngng t ,W/m

2.Krt : nhit tr qua thnh ng v lp cu.

3.1.Xc nh h s cp nhit ca nc i trong ng :Nhit trung bnh ca dng nc trong ng: tf= 34

oCTi nhit ny th:

- Khi lng ring ca nc: n = 994,42 kg/m3

- nht ca nc: n = 7,23.10-7 m2/s

- H s dn nhit ca nc: n = 0,626 W/mK- Chun s Prandtl: Prn = 4,9Chn vn tc nc i trong ng: vn = 1 m/s

S ng:1.032,0.

4.

42,9943600

4,79221

..

4.

3600 22

ntrN

n

vd

Gn = 27,53

Tra bng V.II, trang 48, [2] chn n = 37 ng Vn tc thc t ca nc trong ng:

22 032,0..37.42,994.3600

4,79221.4

3600

4

trn

nn dn

Gv = 0,744 m/s

Chun s Reynolds :

7.

10.23,7032,0.744,0Re

n

trnn

dv

= 32929,5 > 104 Ch chy ri

p dng cng thc (1.74), trang 28, [5] cng thc xc nh chun s Nusselt:25,0

2

43,08,0

Pr

Pr.PrRe..021,0

P

nnnlnNu

Trong : 1 h s tnh n nh hng ca h s cp nhit theo t l gia chiu d i Lv ng knh d ca ng.


33/54


Trang 35

Tra bng 1.1, trang 29, [5] chn 1 = 1

H s cp nhit ca nc i trong ng trong: n =tr

nn

d

.Nu

3.2.Nhit ti qua thnh ng v lp cu :

t

2w1wt

r

ttq

,W/m2

Trong :tw1 : nhit ca vch tip xc vi hi ngng t,

oCtw2 : nhit ca vch tip xc vi nc lnh,

oC

21

t

tt rrr

B dy thnh ng: t = 0,003 mH s dn nhit ca thp khng g: t = 16,3 W/mKNhit tr lp bn trong ng: r1 = 1/5000 m

2.K/WNhit tr lp cu ngoi ng: r2 =1/5800 m2.K/WNn: rt = 5,565.10

-4 m2.K/W

3.3.Xc nh h s cp nhit ca hi ngng t ngoi ng :iu kin:

-Ngng t hi bo ha.- Khng cha khng kh khng ngng.- Hi ngng t mt ngoi ng.- Mng cht ngng t chy tng.- ng nm ngang.

p dng cng thc (3.65), trang 120, [4]i vi ng n chic nm ngang th:

4

nW1ngng

32

1).dt-.(t

.g.r.725,0

Tra bng V.II, trang 48, [2] vi s ng n = 37 th s ng trn ng cho ca hnh 6cnh l: b = 7

Tra hnh V.20, trang 30, [2] h s ph thuc vo cch b tr ng v s ng trong midy thng ng l tb = 0,72 (v xp xen k v s ng trong mi dy thng ng l 7)

H s cp nhit trung bnh ca chm ng: ngng = tb1 = 0,721

Dng php lp: chn tP1 = 59,0oC

Nhit trung bnh ca mng cht ngng t: tm = (tngng + tW1) = 62,4oC

Ti nhit ny th:

Khi lng ring ca nc: N = 982,0 kg/m3

Khi lng ring ca methanol: R = 753,5 kg/m3

Nn khi lng ring hn hp l

310.31,10,982

95,01

5,753

95,011

N

P

R

P xx

= 762,4 kg/m3


34/54


Trang 36

nht ca nc: N = 4,496.10-4 N.s/m2

nht ca methanol: R = 3,424.10-4 N.s/m2

Nn: lg = xPlgR + (1 xP)lgN

= 0,9144.lg(3,424.10

-4

) + (1 - 0,9144).lg(4,496.10

-4

)= -3,45 = 3,50.10-4 N.s/m2

H s dn nhit ca nc: N = 0,661 W/mK H s dn nhit ca methanol: R = 0,205 W/mKNn: = )).(1.(.72,0)1.(. RNPPPNPR xxxx = 0,212 W/mK

Nhit ngng t ca dng hi: r = rD = 2801100 J/kgNn: 1 = 4295,4 W/m

2Kngng = 3092,7,3 W/m

2K qngng = ngng (tngng tP1) = 21030,3 W/m

2 q

t= q

ngng= 21030,3 W/m2 (xem nhit ti mt mt l khng ng k)

tP2 = tP1 - qtrt = 46,35 oC PrP2 = 3,90 Nun = 161,5n = 1700,2 W/m

2K qn = n (tP2 tf) = 20998,7 W/m

2

Kim tra sai s:

=ngng

nngng

q

qq 100% = 0,15% < 5% (tha)

Kt lun: tP1 = 59,0oC v tP2 = 46,3

oC


2,17001

10.565,54,4295

11

4

K = 726,0 W/m2K


F =42,31.0,726.3600

.10001102550

. log

tK

Qnt = 13,4 m2

5. Cu to thit b:S ng truyn nhit: n = 61 (ng). ng c b tr theo hnh lc gic u.

Chiu di ng truyn nhit: L =

2

ddn

F

trn = 3,3 m chn L = 4 m

S ng trn ng cho: b = 7 ngBc ng: t = 48 mm = 0,048 m


35/54


Trang 37

p dng cng thc (V.140), trang 49, [6]:

ng knh trong ca thit b: D = t(b-1) + 4dn = 0,44 m

III. THIT B LM NGUI SN PHM NH :

Chn thit b ngng t v ng loi TH, t nm ngang.ng truyn nhit c lm bng thp X18H10T, kch thc ng 38 x 3:- ng knh ngoi: dn = 38 mm = 0,038 m- B dy ng: t = 3 mm = 0,003 m- ng knh trong: dtr = 0,032 mChn-Nc lm lnh i trong ng trong vi nhit vo tV = 28

oC v nhit ra tR = 40oC.

- Sn phm y i trong ng ngoi vi nhit vo tPS = 65,8oC v nhit ra tPR =

35oC.

1. Sut lng nc lm lnh cn dng:Cn bng nhit: Q = GP(hPS hPR) = Gn (hR hV)

Nhit dung ring ca nc 35oC = 4,178 kJ/kg.KNhit dung ring ca methanol 35oC = 2,645 kJ/kg.KNn: hWR = (0,05. 4,178 + 0,95. 2,645). 35 = 95,26 kJ/kg

Enthalpy ca nc 28oC = hV = 117,3 kJ/kgEnthalpy ca nc 40oC = hR = 167,6 kJ/kg

Lng nhit trao i: Q = GW(hWS hWR) = 8040,4 kJ/h

Sut lng nc cn dng:VR

nhh

QG

= 159,9 kg/h

2. Hiu s nhit trung bnh:Chn kiu truyn nhit ngc chiu, nn:

2835

408,65 )2835()408,65(log

Lnt = 14,40 K


W

t

n

1r

1

1K

,W/m2.K

Vi: n : h s cp nhit ca dng nc lnh, W/m

2.K. W : h s cp nhit ca dng sn phm y, W/m2.K rt : nhit tr qua thnh ng v lp cu.

3.1.Xc nh h s cp nhit ca nc trong ng:Kch thc ca ng trong: ng knh ngoi: dn = 38 (mm) = 0,038 m B dy ng: t = 3 (mm) = 0,003 m ng knh trong: dtr = 0,032 m


36/54


Trang 38

Nhit trung bnh ca dng nc trong ng: tf= (tV + tR) = 34oC

Ti nhit ny th: Khi lng ring ca nc: n = 994,34 kg/m

3 nht ca nc: n = 7,39.10

-7 m2/s

H s dn nhit ca nc:

n = 0,624 W/mK Chun s Prandtl: Prn = 5,004Vn tc nc i trong ng:

22 032,0..994.3600

9,159.4

3600

4

trn

nn d

Gv = 0,056 m/s

Chun s Reynolds :

7.

10.39,7

032,0.056,0Re

n

trnn

dv

= 2424,9 < 104 : ch chy qu

p dng cng thc V.44,trang 16, [2] cng thc xc nh chun s Nusselt:

25,0

2

43,0

1

)Pr

Pr.(Pr..

w

n

non

kNu

Trong : 1 h s tnh n nh hng ca h s cp nhit theo t l gia chiu d i Lv ng knh d ca ng. Tra bng V.2, trang 15, [2] . Chn e1 = 1

ko h s ph thuc Re, tra bng trang 16, [2]. Chn ko = 1

H s cp nhit ca nc trong ng: n =tr

nn

d

.Nu

3.2.Nhit ti qua thnh ng v lp cu:

t

2w1wt

r

ttq

, W/m2

Trong : tP1 : nhit ca vch tip xc vi sn phm y (trong ng trong),oC

tP2 : nhit ca vch tip xc vi nc lnh (ngoi ng trong),oC

21

t

tt rrr

B dy thnh ng: t = 0,003 m H s dn nhit ca thp khng g: t = 16,3 W/mK Nhit tr lp bn trong ng: r1 = 1/5000 m

2.K/W Nhit tr lp cu ngoi ng: r2 =1/5800 m

2.K/WNn rt = 5,565.10-4 m2.K/W

3.3.Xc nh h s cp nhit ca dng sn phm y ngoi ng:Kch thc ca ng ngoi: ng knh ngoi: Dn = 57 mm = 0,057 m B dy ng: t = 3 mm = 0,003 m ng knh trong: Dtr = 0,051 mNhit trung bnh ca dng sn phm y ngoi ng:

tP = (tPS + tPR) = 50,4oC

Ti nhit ny th: Khi lng ring ca nc: N = 987,9 kg/m

3


37/54


Trang 39

Khi lng ring ca methanol: R = 764,6 kg/m3

Nn:9,987

95,01

6,764

95,011

N

P

R

P xx

= 773,4 kg/m3

nht ca nc: N = 5,46.10-4 N.s/m2

nht ca methanol: R = 3,19.10-4 N.s/m2Nn: lg = xPlgR + (1 xP)lgN = 0,9144.lg(3,19.10

-4) + (1 - 0,9144)lg(5,46.10-4) = 3,343.10-4 (N.s/m2)

H s dn nhit ca nc: N = 0,647 W/mK H s dn nhit ca methanol: R = 0,207 W/mKNn: = )).(1.(.72,0)1.(. RNPPPNPR xxxx

= 0,214 (W/mK) Nhit dung ring ca nc: cN = 4178,2 J/kgK Nhit dung ring ca methanol: cA = 2716,8 J/kgKNn: c = cN Px + cA. (1 - Px ) = 2789,8 J/kgKp dng cng thc (V.35), trang 12, [6]:

cPr = 4,365

Vn tc ca dng sn phm y ngoi ng:

)038,0051,0.(.4,773.3600

57,83.4

)(3600

42222

ntr

P

dD

Gv = 0,0346 m/s

ng knh tng ng: dt = Dtr dn = 0,051 0,038 = 0,013 mChun s Reynolds :

410.343,3

4,773.013,0.0346,0Re

tvd = 986,8 < 2300 : ch chy mng

p dng cng thc (V.45), trang 17, [2] cng thc xc nh chun s Nusselt:25,0

1

43,01,033,0

PrPr

.Pr..Re..015,0

PlP GrNu

Trong : 1 h s tnh n nh hng ca h s cp nhit theo t l gia chiu d i Lv ng knh d ca ng.

Tra bng V.2, trang 15, [2] chn 1 = 1

Chun s Grashof

2

32

.

tlgGr

l = dtd =0,013 mb = h s dn n th tch

H s dn nhit ca nc: bN = 4,514.10-4 1/K

H s dn nhit ca methanol: bR = 1,322.10-4 1/K

Dt = chnh lch nhit gia thnh ng vad dng sn phm yDt = tP1 - tP ,

oC

H s cp nhit ca dng sn phm y ngoi ng: P =t

P

d

Nu .


38/54


Trang 40

Dng php lp: chn tW1 = 43,3oC

Ti nhit ny th: nht ca nc: N = 6,167.10

-4 N.s/m2 nht ca ru: R = 4,322.10

-4 N.s/m2Nn:lgP1 = xPlgR + (1 xP)lgN = 0,9144.lg(4,322.10-4) + (1 - 0,9144).lg(6,167.10-4)W1 = 4,50.10

-4 N.s/m2 H s dn nhit ca nc: N = 0,639 W/mK H s dn nhit ca ru: R = 0,208 W/mKNn: ))(1.(72,0)1(.1 RNPPDNDRP xxxx = 0,214 W/mK Nhit dung ring ca nc: cN = 4178,0 J/kgK Nhit dung ring ca ru: cR = 2865,0 J/kgKNn: cP1 = cR Px + cN. (1 - Px ) = 2759,5 J/kgK

p dng cng thc (V.35), trang 12, [2]:1

111Pr

P

PPP

c

= 5,73

Gr = 1020040,5Nn NuP = 10,45 aP = 171,8 W/m

2K qP = aP (tP tP1) = 1217,98 W/m

2 qt = qP = 1217,98 W/m

2 (xem nhit ti mt mt l khng ng k) tP2 = tP1 - qtrt = 42,622

oC PrP2 = 5,796 Nun = 7,32 an = 142,78 W/m

2Kqn = an (tP2 tf) = 1231,2 W/m

2

Kim tra sai s:

=W

nW

q

qq 100% = 1,085% < 5% (tha)

Kt lun: tw1 = 43,3oC v tP2 = 42,6

oC


78,1421

10.565,58,171

11

4

K = 74,73 W/m2K


F =074,73.14,4.3600

1000.4,8040

. log

tKQ

= 2,075 m2

5. Cu to thit b:Chn s ng truyn nhit: n = 19 ng. ng c b tr theo hnh lc gic u.


39/54


Trang 41

- Chiu di ng truyn nhit: L =

2tn ddn

F

= 0,966 m chn L = 1 m

Tra bng V.II, trang 48, [2] S ng trn ng cho: b = 5 ng

- Bc ng: t = 1,2dn = 0,046 m- ng knh trong ca thit b(p dng cng thc (V.140), trang 49, [2])D = t.(b-1) +4dn= 0,336 m

IV. Thit b trao i nhit gia sn phm y v nhp liu:Chn thit b ngng t v ng, t ngangng truyn nhit c lm bng thp hp kim X18H10T, kch thc ng 38 x 3:ng knh ngoi: dn = 38 mm = 0,038 mB dy ng: dt = 3 mm = 0,003 mng knh trong: dtr = 0,032 mNhit tr lp bn trong ng: r1 = 1/5000 m

2.K/WNhit tr lp cu ngoi ng: r2 =1/5800 m

2.K/W

Chn:Nhp liu i ngoi ng vi nhit vo tFV = 28

oC v ra nhit Sn phm yi trong ng vi nhit tv = 98,5

oC, tr = 65oC.

1. Nhit ra ca dng nhp liu :Cn bng nhit: Q = GF.cF.(tFr tFv) = GW.cW.(tWv tWr) nhit trung bnh t = 81,75oC, th:Nhit dung ring ca nc: cN = 41,95 J/kgKNhit dung ring ca ru: cR = 28,32 J/kgKNn: cW = cR Wx + cN.(1 - Wx ) = 41,75 J/kgK

Q = 827,1.41,75.(98,5 65) = 115,7 kW

28o

C, th:Nhit dung ring ca nc: cN = 4181,48 J/kgKNhit dung ring ca ru: cR = 2610 J/kgKNn: cF = 3596,89 J/kgK

tFr = FvFF

tcG

Q

.60,0 oC

2. Hiu s nhit trung bnh :Chn kiu truyn nhit ngc chiu, nn:

75,37

0,280,65

0,605,98ln

)0,280,65()0,605,98(log

t K


ngng

t

n

1r

1

1K

,W/m2.K)Vi:


40/54


Trang 42

an : h s cp nhit ca dng nc lnh, W/m2.K

angng : h s cp nhit ca dng hi ngng tu, W/m2.K

rt : nhit tr qua thnh ng v lp cu.

3.1. Xc nh h s cp nhit ca sn phm yi trong ng :Nhit trung bnh ca dng nc trong ng: tf= (tV + tR) = 81,75 oCTi nhit ny th:Khi lng ring ca nc: rn = 970,2 kg/m

3Khi lng ring ca ru: rR = 731,3 kg/m

3

Nn:2,970

0085,01

3,731

0085,011

N

W

R

W xx

r = 967,5 kg/m3 nht ca nc: mN = 3,348.10

-4 N.s/m2 nht ca ru: mR = 2,552.10

-4 N.s/m2Nn: lgm = xWlgmR + (1 xW)lgmN = 0,015.lg(2,552.10

-4) + (1 - 0,015).lg(3,348.10-4) m = 3,33.10-4 N.s/m2

H s dn nhit ca nc: lN = 0,679 W/mKH s dn nhit ca ru: lR = 0,200 W/mKNn: )).(1.(.72,0)1.(. RNWWWNWR xxxx = 0,675 (W/mK) (cng

thc 1.37, trang 124,[1])Nhit dung ring ca nc: cN = 41,95 J/kgKNhit dung ring ca ru: cR = 28,32 J/kgKNn: cW = cR Wx + cN.(1 - Wx ) = 41,75 J/kgK


cPr = 2,03

Vn tc thc t ca sn phm y trong ng:

016,0032,0..19.18,964.3600

1,827.4

.3600

422

trW

Ww

dn

Gv m/s

Chun s Reynolds :

0,147010.27,3

18,964.032,0.016,0.Re

4.

W

WtrWw

dv

< 2300 : ch chy tng


2

1,043,033,0

Pr

Pr..PrRe..15,0

w

nnnlw GrNu

Trong : e1 h s tnh n nh hng ca h s cp nhit theo t l gia chiu di Lv ng knh d ca ng.

Tra bng 1.2, trang 31, [5] chn e1 = 1Chn t2 = 8,25

oC tw2 = 81,75 + 8,25 = 90oC

Ti nhit ny: nht ca nc: mN = 3,276.10

-4 N.s/m2 nht ca ru: mR = 2,3.10

-4 N.s/m2Nn: lgm = xWlgmR + (1 xW)lgmN = 0,015.lg(2,3.10

-4) + (1 - 0,015).lg(3,276.10-4)


41/54


42/54


Trang 44

mdnD

dnDd

ot

ottd 076,0032,0.1277,0

032,0.1277,0

.

. 2222

Vn tc thc t ca dng nhp liu i ngoi ng:

3

2222 10.57,3)032,0.1277,0.(.5,962.3600

1000.4

).(3600

4

ot

F

F dnD

G

v m/sChun s Reynolds :

9,71010.22,5

5,962.076,0.10.57,3.Re

4

3.

F

FtdFF

dv

< 2300 : ch chy tng.

p dng cng thc (V.56), trang 20, [2] cng thc xc nh chun s Nusselt:

64,2543,4.9,710.108,0.16,1

PrRe..16,133,06,06,0

33,06,06,0

DDtdD dNu

Chn t1 = 18oC

H s cp nhit ca dng nhp liu ngoi ng:

aF = 43,114108,0

482,0.64,25.

td

FF

d

Nu

W/m2

qF = aF. t1 = 112,75.18 = 2059,7 W/m

2

Kim tra sai s:

e =W

FW

q

qq 100% = 2,92% < 5% (tha)

3.4. Xc nh h s truyn nhit:

85,75

43,114

110.565,5

20,257

11

4

K W/m2K


F = 41,4075,37.85,75

1000.7,115. log

tKQ

m2

5. Cu to thit b:S ng truyn nhit: n = 127 ng. ng c b tr theo hnh lc gic u.


2trn ddn

F

= 2,51 (m) chn L = 2,5 m

Sng trn ng cho: b = 13 ngBc ng: t = 48 (mm) = 0,048 m

p dng cng thc (V.140), trang 49, [2]: ng knh trong ca thit b: D = t(b-1) + 4dn = 0,7 m.

V. Thit b un si dng nhp liu:Chn thit b ngng t v ng, t ngang.


43/54


Trang 45

ng truyn nhit c lm bng thp hp kim X18H10T, kch thc ng 38 x 3:ng knh ngoi: dn = 38 mm = 0,038 mB dy ng: dt = 3 mm = 0,003 mng knh trong: dtr = 0,032 mNhit tr lp bn trong ng: r1 = 1/5000 m

2.K/WNhit tr lp cu ngoi ng: r2 =1/5800 m2.K/W

Chn:Nhp liui trong ng vi nhit vo tV = 60,0

oC v nhit ra tR = 68,5oC.

Dng hi ngng ti ngoi ng vi nhit ngng t tngng = 126,25oC, c p sut 2at,

n nhit ha hi r = 2189500 J/kg.

1. Lng hi nc cn dng :Cn bng nhit: Q = GF.cF.(tr tv) = Gn.rn nhit trung bnh ttb = 64,25

oC th:Nhit dung ring ca nc: cN = 41,83 J/kgKNhit dung ring ca ru: cR = 28,20 J/kgK

Nn: cF = cR.xF + cN. (1 xF) = 41,02 J/kgK Q = 1000.41,02.( 68,5 - 60) = 34,87 kW Gn = 15,93 (kg/h)2. Hiu s nhit trung bnh :Chn kiu truyn nhit ngc chiu, nn:

15,62

5,6825,126

0,6025,126)5,6825,126()0,6025,126(

log

Lnt K


ngng

t

n

1r

11K

,W/m2.KVi:an : h s cp nhit ca dng nc lnh, W/m

2.Kangng : h s cp nhit ca dng hi ngng tu, W/m

2.Krt : nhit tr qua thnh ng v lp cu. B dy thnh ng: t = 0,003 m H s dn nhit ca thp khng g: t = 16,3 W/mK Nhit tr lp cu trong ng: r1 = 1/5800 m

2.K/W Nhit tr lp cu ngoi ng: r2 =1/5800 m

2.K/W

Nn: rt = 5,289.10-4 m2.K/W

3.1. Xc nh h s cp nhit ca dng nhp liui trong ng :Nhit trung bnh ca dng nhp liu trong ng: tf = (tV + tR) = 64,25

oCTi nhit ny th:Khi lng ring ca nc: rN = 979,8 kg/m


3


44/54


Trang 46

Nn:8,979

1,01

2,746

1,011

N

F

R

F xx

r = 950,06 kg/m3

nht ca nc: mN = 3,88.10-4 N.s/m2

nht ca ru: mR = 3,12.10-4 N.s/m2

Nn: lgm = xF.lgmR + (1 xF).lgmN m = 3,65.10-4 N.s/m2H s dn nhit ca nc: lN = 0,661 W/mKH s dn nhit ca ru: lR = 0,105 W/mKNn: l = )).(1.(.72,0)1.(. RNFFFNFR xxxx = 0,569 W/mK (cng thc

1.37, trang 124,[1])Nhit dung ring ca nc: cN = 41,83 J/kgKNhit dung ring ca ru: cR = 28,20 J/kgKNn: c = cR.xF + cN. (1 xF) = 40,475 J/kgK


cPr = 2,60

Vn tc thc t ca dng nhp liu trong ng:

003,0032,0..127.06,950.3600

1000.4

3600

422

trF

FF

dn

Gv m/s

Chun s Reynolds :

0,25010.65,3

06,950.032,0.003,0.Re

4.

F

FtrFF

dv

< 2300 : ch chy tng


2

1,043,033,0

Pr

Pr..PrRe..15,0

w

nnnlw GrNu

Trong : e1 h s tnh n nh hng ca h s cp nhit theo t l gia chiu d i Lv ng knh d ca ng.Tra bng 1.2, trang 31, [5] chn e1 = 1

Chn t2 = 20oC tw2 = 84,25oCTi nhit ny: nht ca nc: mN = 3,03.10

-4 N.s/m2 nht ca ru: mR = 2,26.10

-4 N.s/m2Nn: lgm = xFlgmR + (1 xF)lgmN

m = 2,98.10-4 N.s/m2H s dn nhit ca nc: lN = 0,677 W/mKH s dn nhit ca ru: lR = 0,178 W/mKNn: l = )).(1.(.72,0)1.(. RNFFFNFR xxxx = 0,595 W/mK (cng thc

1.37, trang 124,[1])Nhit dung ring ca nc: cN = 4201,8 J/kgKNhit dung ring ca ru: cR = 2922,0 J/kgKNn: c = cR. xF + cN.(1 xF) = 4126,5 J/kgK


cW 2Pr = 2,067


45/54


Trang 47

6

23

323

13

2

23

10.4,193)10.298,0(

20.10.96,2.06,950.032,0.81,9

10.96,227325,64

11

....

Gr

KT

tdgGr o

NuF = 11,4H s cp nhit ca dng nhp liui trong ng trong:

aF = 0,212032,0

595,0.4,11.

tr

FF

d

Nu W/m2

qF = aF. t2 = 212,0.20 = 4240,0 W/m2

3.3. Xc nh h s cp nhit ca hi ngng t ngoi ng :

p dng cng thc (1.110), trang 38, [5] i vi ng n chic nm ngang th:4

nW1ngng

32

1).dt-.(t

.g.r.725,0

Tra bng V.II, trang 48, [2] vi s ng n = 127 th s ng trn ng cho ca hnh 6cnh l: b = 13

Tra hnh V.18, trang 19, [4] h s ph thuc vo cch b tr ng v s ng trong midy thng ng l etb = 1,1

H s cp nhit trung bnh ca chm ng: angng = etba1 = 1,1a1Chn t1 = 0,2

oC tW1 = 126,05oC

Tra cc thng s ca hi ngng t:Khi lng ring ca hi: rN = 939,16 kg/m

3

nht ca hi: mN = 2,28.10-4

N.s/m2

H s dn nhit ca hi: lN = 0,686 W/mK a1 = 19886,13 W/m

2K an = 21874,74 W/m

2K qn = an (tn tW1) = 4374,94 WKim tra sai s:

e =n

Fn

q

qq 100% = 3,08% < 5% (tha)

3.4. Xc nh h s truyn nhit:

0,188

74,21874

1

10.565,50,212

11

4

K W/m2K


F = 36,115,62.0,188

1000.93,15

. log

tK

Qnt m2

5. Cu to thit b:


46/54


Trang 48

S ng truyn nhit: n = 127 ng. ng c b tr theo hnh lc gic u.


2trn ddn

F

= 0,09 (m) chn L = 0,1 m

Sng trn ng cho: b = 13 ngTra bng trang 21, [3] Bc ng: t = 48 mm = 0,048 m

p dng cng thc (V.140), trang 49, [2]: ng knh trong ca thit b: D = t(b-1) + 4dn = 0,7 m.

VI. Bn cao v:1. Tn tht ng ng dn:Chn ng dn c ng knh trong l dtr = 80 mmTra bng II.15, trang 381, [1] nhm ca ng: e = 0,2 mm = 0,0002 mTn tht ng ng dn:

g

v

d

lh F

2.

2

11

111

m

Trong :l1 : h s ma st trong ng ng.l1 : chiu di ng ng dn, chn l1 = 30 md1: ng knh ng dn, d1 = dtr = 0,08 mx1 : tng h s tn tht cc b.vF : vn tc dng nhp liu trong ng dn

1.1. Xc nh vn tc dng nhp liu trong ng dn :Cc tnh cht l hc ca dng nhp liu c tra nhit trung bnh:

tF =2

8,6528

2

FSFV tt = 46,9 oC

Ti nhit ny th:Khi lng ring ca nc: rN = 989,2 kg/m


3

Nn:2,989

1,01

4,768

1,011

N

F

R

F

F

xx

rF = 961,6 kg/m

3

nht ca nc: mN = 5,15.10-4 N.s/m2

nht ca ru: mR = 3,75.10-4 N.s/m2Nn: lgmF = xFlgmN + (1 xF)lgmA

mF = 4,65.10-4 N.s/m2

Vn tc ca dng nhp liu i trong ng:

22 08,0..6,961.3600

1000.4

3600

4

trF

FF

d

Gv = 0,057 m/s


47/54


Trang 49

1.2. Xc nh h s ma st trong ng ng :Chun s Reynolds :

410.65,4

6,961.08,0.057,0Re

F

FtrFF

dv

= 9429,9 > 4000 : ch chy ri

Chun s Reynolds ti hn: Regh = 6(d1/e)8/7

= 5648,513Chun s Reynolds khi bt u xut hin vng nhm:Ren = 220.(d1/e)

9/8 = 186097,342V Regh < ReF < Ren ch chy ri ng vi khu vc qu .

p dng cng thc (II.64), trang 379, [1]: l1=25,0

1 Re

100.46,1.1,0

Fd

= 0,035

1.3. Xc nh tng h s tn tht cc b :Ch un cong :

Tra bng II.16, trang 382, [1]:Chn dng ng un cong 90o c bn knh R vi R/d = 2 th xu1(1 ch) = 0,15.

ng ng c 6 ch un xu1 = 0,15. 6 = 0,9Van :

Chn van cu vi m hon ton th xvan(1 ci) = 10.ng ng c 2 van cu xvan = 10. 2 = 20

Lu lng k : xl1= 0 (coi nh khng ng k).Vo thp : xthp = 1Ti ming ra ca bn cao v: Tra bng 10, trang 385, [1]: x = 11

Nn: x1 = 33,05

Vy:81,9.2

057,0.05,33

08,0

30.035,0

2

1

h = 7,65.10-3 (m)

2. Tn tht ng ng dn trong thit b trao i nhit gia dng nhp liu vsn phm y:

g2

v.

d

lh

2

22

2

222

mTrong :l2 : h s ma st trong ng ng.l2 : chiu di ng ng dn, l2 = 2,5 md2: ng knh ng dn, d2 = dtr = 0,032 mx2 : tng h s tn tht cc b.v2 : vn tc dng nhp liu trong ng dn

2.1. Vn tc dng nhp liu trong ng dn :v2 = 3,57.10-3 m/s

2.2.Xc nh h s ma st trong ng ng:Chun s Reynolds : Re2 = 710,9 < 2300 : ch chy tng. nhm: e = 0,0002

p dng cng thc (II.64), trang 379, [1]: 09,09,710

64

Re

64

2.3.Xc nh tng h s tn tht cc b :


48/54


Trang 50

t thu :

Tra bng II.16, trang 382, [1]: Khi2

2

1 08,0

032,0

F

Fo = 0,160 th xt thu 2 (1ch) = 0,458

C 1 ch t thu xt thu 1 = 0,458

t m:Tra bng II.16, trang 382, [1]: Khi

2

2

1 08,0

032,0

F

Fo = 0,160 th xt m 2 (1ch) = 0,708

C 1 ch t m xt m 2 = 0,708

Nn: x2 = xt thu 2 + xt m 2 = 1,166

Vy: 323

2 10.68,081,9.2

)10.57,3(.166,1

032,0

5,2.09,0.127

h m

3. Tn tht ng ng dn trong thit b un si dng nhp liu:

gv

dlh 2.

2

33

3

333

,m

Trong :l3 : h s ma st trong ng ng.l3 : chiu di ng ng dn, l2 = 0,5 m.d3: ng knh ng dn, d3 = dtr = 0,032 m.x3 : tng h s tn tht cc b.v3 : vn tc dng nhp liu trong ng dn

3.1. Vn tc dng nhp liu trong ng dn :v2 = 0,003 m/s3.2. Xc nh h s ma st trong ng ng :Chun s Reynolds : Re2 = 250 < 2300: ch chy tng nhm: e = 0,0002

p dng cng thc (II.64), trang 379, [1]: 256,0250

64

Re

64

3.3. Xc nh tng h s tn tht cc b :t thu :

Tra bng II.16, trang 382, [1]: Khi2

2

1 08,0

032,0

F

Fo = 0,160 th xt thu 3 (1ch) = 0,458

C 1 ch t thu xt thu 3 = 0,458t m:

Tra bng II.16, trang 382, [1]: Khi 2

2

1 08,0032,0FF

o = 0,160 th xt m 3 (1ch) = 0,708

C 1 ch t m xt m 3 = 0,708Nn: x3 = xt thu 3 + xt m 3 = 1,166

Vy: 32

3 10.30,081,9.2

003,0.166,1

032,0

5,0.256,0.127

h m


49/54


Trang 51

4. Chiu cao bn cao v:Chn :Mt ct (1-1) l mt thong cht lng trong bn cao v.Mt ct (2-2) l mt ct ti v tr nhp liu thp.Ap dng phng trnh Bernoulli cho (1-1) v (2-2):

z1 +g

P

F.1

+

g

v

.2

21 = z2 +

g

P

F.2

+

g

v

.2

22 +hf1-2

z1 = z2 +g

vv

g

PP

F .2.

21

2212

+hf1-2

Trong :z1: cao mt thong (1-1) so vi mt t, hay xem nh l chiu cao bn cao v Hcv =z1.z2: cao mt thong (2-2) so vi mt t, hay xem nh l chiu cao t mt t n vtr nhp liu:z2 = hchn + hy + (nttC 1).Dh

= 0,105 + 0,02 + (12 1).0,25 = 2,875 mP1 : p sut ti mt thong (1-1), chn P1 = 1 at = 9,81.10

4 N/m2P2 : p sut ti mt thong (2-2)Xem DP = P2 P1 = nttL .DPL = 9. 286,27 = 2576,4 N/m

2v1 : vn tc ti mt thong (1-1), xem v1 = 0 m/sv2 : vn tc ti v tr nhp liu, v2 = vF = 0,057 m/shf1-2 : tng tn tht trong ng t (1-1) n (2-2):hf1-2 = h1 + h2 + h3 = 8,63.10

-3 m

Vy:Chiu cao bn cao v: Hcv = z2 +g

vv

g

PP

F .2.

21

2212

+hf1-2

= 2,875 + 81,9.2

0057,0

6,961.81,9

4,2576 2

+ 8,63.10

-3

= 3,16 m

Chn Hcv = 5 m

VII. Bm:1. Nng sut:Nhit dng nhp liu l tF = 28

oC.Ti nhit ny th:Khi lng ring ca nc: rN = 996,3 kg/m


3

Nn:3,9961,01

8,7841,011

N

F

R

F

F

xx

rF = 970,2 kg/m3

nht ca nc: mN = 8,36.10-4 N.s/m2

nht caru: mR = 0,51.10-3 N.s/m2

Nn: lgmF = xF.lgmN + (1 xF).lgmA mF = 7,35.10

-4 N.s/m2Sut lng th tch ca dng nhp liu i trong ng:


50/54


Trang 52

2,970

1000

F

FF

GQ

= 1,03 m3/h

Vy: chn bm c nng sut Qb = 2 m3/h

2. Ct p:Chn :Mt ct (1-1) l mt thong cht lng trong bn cha nguyn liu.Mt ct (2-2) l mt thong cht lng trong bn cao v.p dng phng trnh Bernoulli cho (1-1) v (2-2):

z1 +g

P

F.1

+

g

v

.2

21 + Hb = z2 +

g

P

F.2

+

g

v

.2

22 +hf1-2

Trong :z1: cao mt thong (1-1) so vi mt t, chn z1 = 1m.z2: cao mt thong (2-2) so vi mt t, z2 = Hcv = 5m.P1 : p sut ti mt thong (1-1), chn P1 = 1 at.

P2 : p sut ti mt thong (2-2), chn P2 = 1 at.v1,v2 : vn tc ti mt thong (1-1) v(2-2), xem v1= v2 = 0 m/shf1-2 : tng tn tht trong ng t (1-1) n (2-2).Hb : ct p ca bm.2.1. Tnh tng tr lc trong ng:Chn ng knh trong ca ng ht v ng y bng nhau: dtr = 50 mmTra bng II.15, trang 381, [1] nhm ca ng: e = 0,2 mm = 0,0002Tng tr lc trong ng ht v ng y

hf1-2 =g

v

d

ll Fh

tr

h

2.

2

Trong :

lh : chiu di ng ht.Chiu cao ht ca bm: Tra bng II.34, trang 441, [1] hh = 4,2 m Chn lh = 6 ml : chiu di ng y, chn l = 8 mxh : tng tn tht cc b trong ng ht.x : tng tn tht cc b trong ng y.l : h s ma st trong ng ht v ng y.vF : vn tc dng nhp liu trong ng ht v ng y m/s

283,0050,0..3600

2.4

3600

422

tr

bF d

Qv m/s

11 Xc nh h s ma st trong ng ht v ng y :Chun s Reynolds :

410.05,8

2,970.05,0.283,0Re

F

FtrFF

dv

= 17053,8 > 4000 : ch chy ri

Chun s Reynolds ti hn: Regh = 6(dtr/e)8/7 = 3301,065

Chun s Reynolds khi bt u xut hin vng nhm:Ren = 220(dtr/e)

9/8 = 109674,381V Regh < ReF < Ren ch chy ri ng vi khu vc qu .


51/54


Trang 53

p dng cng thc (II.64), trang 379, [1]: l =25,0

Re

100.46,1.1,0

Ftrd

= 0,033

12 Xc nh tng tn tht cc b trong ng ht :

Ch un cong:Tra bng II.16, trang 382, [1]: Chn dng ng un cong 90o c bn knh R vi R/d = 2

th xu1(1 ch) = 0,15.ng ht c 2 ch un xu1 = 0,3

Van :Chn van cu vi m hon ton th xv1(1 ci) = 10.ng ht c 1 van cu xv1 = 10Nn: xh = xu1 + xv1 = 10,3

13 Xc nh tng tn tht cc b trong ng y : Ch un cong:

Tra bng II.16, trang 382, [5]: Chn dng ng un cong 90o c bn knh R vi R/d = 2th xu2(1 ch) = 0,15.

ng y c 4 ch un xu2 = 0,15. 4 = 0,6 Van :

Tra bng 9.5, trang 94, [1]: Chn van cu vi m hon ton th xv2(1 ci) = 10.ng y c 1 van cu xv2 = 10

Vo bn cao v : xcv = 1Nn: x = xu1 + xv1 + xcv = 11,6

Vy: hf1-2 =81,9.2

283,0.6,113,10

05,086

033,02

= 0,127 m

2.2. Tnh ct p ca bm:Hb = (z2 z1) + hf1-2 = ( 5 1) + 0,127 = 4,127 m

3. Cng sut:Chn hiu sut ca bm: hb = 0,8.

Cng sut thc t ca bm: Nb =8,0.3600

81,9.5,970.127,4.2

.3600

.

b

Fbb gHQ

= 27,3 WKt lun: m bo thp hot ng lin tc ta chn 2 bm li tm, c:

Nng sut: Qb = 2 m3/h

Ct p: Hb = 4,127 mCng sut: Nb = 27,3 W


52/54


Trang 54

CHNG 6:

Tnh kinh tLng thp X18H10T cn dng:

M1 = 21mmm + mthn + 2my(np) = 243,43 kgLng thp CT3 cn dng:

M2 = 8mbch ni thn + mbch ghp ng lng + mbch ghp ng hi+ 4. mchn + 4. mtai treo + 4. mtm lt = 163,82 kg

S bulng cn dng:n = 164 (ci)

Chiu di ng 38 x 3mm:

L1 = 837mChiu di ng 70mm: Chn tng chiu di ng dn lng vo thp l 10m.Chiu di ng 150mm: Chn tng chiu di ng hi nh thp v ng hi ythp l L4 = 10m.Chiu di ng 50mm: Chn tng chiu di ng chy trn v ng x y t bn caov, ng nhp liu v ng hon lu l 40m.Bm ly tm: chn 2 bm ly tm Nb = 2. 27,3 = 54,6 W

Vt liu S lngn gi

Thnh tin ()

Thp X18H10T 243,43 (kg) 50000 (/kg) 12171500Thp CT3 163,82 (kg) 10000 (/kg) 1638200Bulng 164 (ci) 2500 (/ci) 410000ng dn 38 x 3mm 837 (m) 50000 (/m) 41850000

ng 70mm 10 (m) 100000 (/m) 1000000ng 150mm 10 (m) 100000 (/m) 1000000ng 50mm 40 (m) 100000 (/m) 4000000Bm ly tm 54,6 (W) 700000 (/Hp) 56000p k 2 (ci) 200000 (/ci) 400000Nhit k 3 (ci) 150000 (/ci) 450000Lu lng k ( 50mm) 2 (ci) 1000000 (/ci) 2000000

Tng chi ph vt t 64975700

Vy tng chi ph vt t l 65 triu ng.Xem tin cng ch to bng 200% tin vt t.Vy: tng chi ph l 195 triu ng.


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CHNG 7:

Kt lunVi h thng chng ct metanol - nc dng thp mm xuyn l nh thit k, ta

thy bn cnh nhng u im cng cn c nhiu nhc im. Thit b c u im l nngsut v hiu sut cao nhng thit b cn rt cng knh, i hi phi c s vn hnh vi chnh xc cao. Bn cnh , khi vn hnh thit b ny ta cng phi ht sc ch n vn an ton lao ng trnh mi ri ro c th xy ra, gy thit hi v ngi v ca.

Ti liu tham kho[1]. S tay Qu trnh v Thit b Cng ngh Ha hc Tp 1, HBK H Ni.


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[2]. S tay Qu trnh v Thit b Cng ngh Ha hc Tp 2, HBK H Ni.[3]. V Vn Bang, V B Minh, Qu trnh v Thit b trong Cng Ngh Ha Hc

Tp 3: Truyn Khi, Nh xut bn i hc Quc gia TpHCM, 2004.[4]. Phm Vn Bn Nguyn nh Th, Qu trnh v Thit b trong Cng Ngh Ha

Hc Tp 5: Qu trnh v Thit b Truyn Nhit, Nh xut bn i hc Quc giaTpHCM, 2002.

[5]. Phm Vn Bn , Qu trnh v Thit b trong Cng Ngh Ha Hc Bi tpTruyn nhit, Nh xut bn i hc Quc gia TpHCM,2004.

[6]. Trnh Vn Dng , Qu trnh v Thit b trong Cng Ngh Ha Hc Bi tpTruyn khi, Nh xut bn i hc Quc gia TpHCM,2004.

[7]. H L Vin, Thit k v Tnh ton cc thit b ha cht, Nh xut bn Khoa hcv K thut, H Ni, 1978.

[8]. Nguyn Minh Tuyn, C s Tnh ton My v Thit b Ha cht Thc phm,Nh xut bn Khoa hc v K thut, H Ni, 1984.

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