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THY V VN SIM

\B CNG THNGTRNG I HC CNG NGHIP THC PHM TP.HCM

KHOA CNG NGH THC PHM

((((

THC HNH K THUT THC PHM

GVHD:V VN SIM

SVTH : Nguyn Hong Lm

MSSV:2205115009

LP : 02DHLTP3

Tp.H Ch Minh 07/2013

BI 1: C C

1.1. C S L THUYT

1.1.1. Khi nim chung

nh ngha v c cC c l qu trnh lm tng nng ca dung dch bng cch tch mt phn dung mi nhit si, dung mi tch ra khi dung dch bay ln gi l hi th.

C c l phng php dng nng cao nng cc cht ha tan trong dung dch gm hai hay nhiu cu t. Qu trnh ca dung dch lng rn hay lng lng c chnh lch nhit si rt cao thng c tin hnh bng cch tch mt phn dung mi (cu t d bay hi hn), l cc qu trnh vt l ha l. Ty theo tnh cht ca cu t kh bay hi ( hay bay hi trong qu trnh ), ta c th tch mt phn dung mi (cu t d bay hi hn) bng phng php nhit (un nng ) hay phng php lm lnh kt tinh.Cc phng php c c

Phng php nhit (un nng): Dung mi chuyn t trng thi lng sang trng thi hi di tc dng ca nhit khi p sut ring phn ca n bng p sut tc dng ln mt thong cht lng.

Phng php lnh: Khi h thp nhit n mt mc no th mt cu t s tch ra dng tinh th n cht tinh khit, thng l kt tinh dung mi tng nng cht tan. Ty tnh cht cu t v p sut bn ngoi tc dng ln mt thong m qu trnh kt tinh xy ra nhit cao hay thp v i khi phi dng n my lnh.

C c p sut kh quyn: L phng php n gin nhng khng kinh t. C c p sut chn khng: dng cho cc dung dch c nhit si cao, d phn hy v nhit, C c p sut d: dng cho cc dung dch khng phn hy nhit cao, s dng hi th cho cc qu trnh khc.Mc ch ca qu trnh c c

Lm tng nng ca cht ha tan trong dung dch.

Tch cht rn ha tan dng rn (kt tinh).

Tch dung mi dng nguyn cht (nc ct).

u v nhc im ca qu trnh c c

u im:

D vn hnh, thao tc d dng.

Gi c cht lng, tnh cht sn phm, hay cc cu t d bay hi do dung dch si nhit thp hn.

Nhp liu v tho sn phm n gin, khng cn n nh lu lng.

C th c c n cc nng khc nhau.

Khng cn phi gia nhit ban u cho dung dch.

Cu to n gin gi thnh thp.

Nhc im: Qu trnh c c khng n nh do nhit v p sut khng n dnh, tnh cht ha l ca dung dch thay i lin tc theo nng , thi gian. Nhit hi th thp, khng dng c cho mc ch khc.

Kh gi c chn khng trong thit b.

ng dng ca s c c

- Trong sn xut thc phm, cn c c cc dung dch ng, nc tri cy ,.- Trong sn xut ha cht, ta cn c c cc dung dch: NaOH, NaCl, NaCl2, cc mui v c, .

1.1.2. Cn bng vt cht trong h thng c c mt ni - Phng trnh cn bng vt cht ta c: G = Gc + W (1.1)

G. x = Gc. xc (theo hm lng cht kh trong dung dch)

Trong :

G Khi lng nguyn liu, [kg]; kg/s

Gc Khi lng sn phm, [kg]; kg/s

W Lng hi th, [kg]; kg/s

x Nng % cht kh trong nguyn liu, [phn khi lng]

xc Nng % cht kh trong sn phm, [phn khi lng] Lng hi th trong qu trnh c c W = G

EMBED Equation.3 (1.2)

Hnh 1. M hnh cn bng vt cht

Nng sn phm cui

(1.3)1.1.3. Cn bng nhit lng trong h thng c c mt ni

- Theo nh lut bo ton nhit .

Trong :

Q1: Nhit do dung dch mang vo.

Q2: Nhit do nc nng cung cp.

Q3: Nhit do dung dch sau c c mang ra.

Q4: Nhit do hi th mang ra.

Q5: Nhit do nc ngng mang ra.

Q6: Nhit do qu trnh c c.

Q7: Nhit tn tht ra mi trng.

G.c.t + D.i = Gc.cc.tc + W.i + D.cn.tn + Qc + Qmt (1.4) Vi:

t : Nhit nguyn liu, [].

tc ; Nhit sn phm, [].

tn : Nhit nc ngng, [].

c : Nhit dung ring nguyn liu, [J/kg.].

cc : Nhit dung ring sn phm, [J/kg.]

cn : Nhit dung ring nc ngng, [J/kg.].

i: Hm nhit trong hi t, [J/kg]

i: Hm nhit trong hi th, [J/kg]

Lng hi t tiu tn

D = (1.5) Tnh din tch b mt truyn nhit .

Theo phng trnh truyn nhit.

Q = K.F.(.(hi = D.(i - cn.tn).

Trong :

Q: lng nhit truyn, [J].

K: H s truyn nhit,[ W/m2.].

F: Din tch b mt truyn nhit, [m2].

(: Thi gian c c,[s].

(hi : Hiu s nhit hu ch , []

Rt ra b mt truyn nhit :

[m2] (1.6)1.2. NGUYN LIU, HA CHT, DNG C, THIT B1.2.1 Nguyn liu

ng ct trng: 1kg1.2.2. Ha cht, dng c, thit bA. HO CHT Nhm ln

STTTn ha chtQuy cch/v tnhS lngGhi ch

1

B. DNG C Nhm ln

STTTn dng cQuy cch/v tnhS lngGhi ch

1Brix k0 100 %ci3

2ng ong 1000 mlci2

3Ca nha5000 mlci2

4Cn ng h2 kgci1

5X nha20 ltci1

C. THIT B Nhm ln

STTTn thit bQuy cch/v tnhS lngGhi ch

1Thit b c c ( ph kin km theo )1

1.3. CU TO THIT B C C GIN ON MT NITrong :

1. Ni c c 2 v c cnh khuy.

2. Thit b ngng t ng xon.

3. Bnh cha nc ngng.4. Bm chn khng.

5. p k o p sut chn khng.

6. H thng in.

1.4. THUYT MINH QUY TRNH Bc 1: Chy nc nng Kim tra cc van; m van 6, 10, cc van cn li ng.

M cng tc tng.

Chun b 20 lt nc sch trong x nha.

Ht chn khng khi kim p k ch 0.6 at th tt bm.

M van 1 ht ht nc sch vo trong ni.

Kim tra mc nc trong v o bng cch m van 5.

M cng tc in tr.

M cng tc khuy trn.

Khi nhit nc trong ni t 60oC th x nc bng cch x chn khng van 1 sau m van 4 x nc trong ni ra ngoi.

Tt my khuy trn.

Ra lp ln 2. Bc 2: C c dung dch. Pha 5 lt dung dch ng 15%.

Kim tra cc van, van 6 m, cc van cn li ng.

M cng tc tng.

Ht chn khng bng cch bm chn khng v m van 10 khi kim p k ch 0,60,8 atm th tt bm v kha van 10.

M van 1 ht ht 5 lt dung dch vo trong ni.

M van 9 nc vo ng xon ngng t hi th.

M cng tc khuy trn (5 pht khuy 1 ln, mi ln 1pht).

K t lc dung dch trong ni si (60oC), th c 10 pht ly mu 1 ln o Brix, ly nc ngng t ra o th tch v ghi nhn cc nhit .

Cch ly mu: M van 2 trong thi gian 5 giy sau ng van 2 li, m van 3 ly mu.

Cch ly nc ngng t: ng van 6, m van 7, van 8, ly nc ngng xong thao tc van ngc li tr v trng thi ban u (ch trong lc nuc ngng t khng c ht chn khng).

Dung mi l nc bc hi v thot ra ngoi qua ng dn hi th sau khi qua bung bc v thit b tch git. Hi th c dn qua thit b ngng t. Sau khi ngng t thnh cht lng s chy ra ngoi bn cha.

Khi dung dch trong ni t 500 Brix tr ln th dng qu trnh c c.

M van 1 thng p kh tri.

M van 4 x dung dch sau c c ra ngoi cn khi lng.

Tt my khuy trn.

Bc 3: V sinh thit b Kim tra cc van: van 6,van 10 m, cc van cn li ng.

M cng tc tng.

Chun b 20 lt nc sch trong x nha.

Ht chn khng khi kim p k ch 0.6 at th tt bm.

M van 1 ht ht nc sch vo trong ni.

M cng tc khuy trn trong thi gian 3 pht.

M van 4 x nc trong ni ra ngoi.

Ra lp ln 2.

Tt my khuy trn.

Tt cng tc tng.

1.5. X L S LIUBng s liu th nghim.Thi gian (ph)Nng dung dich (Brix)Lng nc ngng V (ml)Nhit nc vo tv (0C)Nhit nc ra tr (0C)Nhit nc ngoi v tng (0C)Nhit dd tdd (0C)Nhit hi th tht (0C)

01903043817064

10214803049847779

2022,85403049847780

30276553049857678

40317503049847475

50383853050858080

60464103050858080

Th tch dung dch sau qu trnh c c thu c l:

Vc = 1350 (ml) Bx = 68.5 (Tra S tay Cng Ngh Ha Cht tp 1, nhit phng l 300C)

Tnh khi lng dung dch ng nhp liu: Dng nhp liu l dung dch ng c nng cht kh l 19 0Bx c pha t 1kg ng saccharose 99,85 0Bx v dung mi l nc.

Khi lng dng nhp liu:

G = mH2O + msaccharose msaccharose 99,85

19

19 mH2O 0 80,85

Suy ra: G = mH2O + msaccharose = 4,255 + 1 = 5,255 (kg)

Th tch dung dch ng nhp liu Ta c: G = V.( (kg).

V = =

= 4,976 ( lt ) (Khi lng ring dung dch ng nhp liu tra nhit phng ( =1,05598 kg/m3) Tnh lng dung dch ng thc t sau qu trnh c c:

Ta c cng thc:

Gc = Vc * (c

= 1.350 * 1.33681 = 1.805 (kg)

Trong :

Gc : Th tch dung dch ng thu c sau qu trnh thc nghim.

(c : Khi lng ring ca dung dch ng 68.5 Bx

Tnh lng nc ngng thc t trong qu trnh c c:

W* = Vngng. (ngng ( kg)

Vngng = 0 + 480 + 540 + 655 + 750 + 385 + 410 = 3220 (ml) = 3220*10-6 (m3)

W* = 3220*10-6 * 995,68 = 3,206 (kg)

Trong :

Vngng : Tng th tch nc ngng thu c trong sut qu trnh thc nghim.

(ngng : Khi lng ring nc ngng ( kg/m3)

(Nc ngng tra 30 0C (ngng =995,68 kg/m3) Tnh cn bng vt cht v cc i lng cha bit trong phng trnh (1.1)Do lng dung dch c c tht thot qua cc ln ly mu, nn ta gi s lng nc ngng thc t khng tht thot v bng vi lng nc ngng theo l thuyt th ta mi tnh c sai s(lc ny sai s gia nc ngng thc t v nc ngng l thuyt = 0). Vi W = W* Ta c: Gc = G - W = 5,255 3,206 = 2,049 (kg)

xc = G * x/Gc ( x = 19 ) = 5,255 * 19/2,049 = 48,73 (%) Tnh sai s gia l thuyt v thc nghim + Sai s nng cui ca qu trnh

Trong

: Nng % cht kh trong sn phm sau c c theo l thuyt [phn khi lng]. : Nng % cht kh trong sn phm c c theo thc t o bng Bx k, [phn khi lng].Gii thch kt qu sai s

Sai s ca nng tng i khng ln gia thc t v l thuyt, l do l qu trnh thao tc ly mu lm tht thot lng nh dung dch trong qu trnh ly mu.

+ Sai s lng nc ngng thu c trong qu trnh c c:

Gi s Bx o c thc t ng vi Bx theo l thuyt th ta mi tnh c lng nc ngng W v sai s (lc ny sai s ca nng l thuyt v thc t = 0)

Ta c xc = xc* T phng trnh (1.2) v (1.3) Ta c: W = G(1-x/xc); Gc = G * x/xc (%)

Trong W : Lng hi th theo l thuyt, [kg]; kg/s

W*: Lng hi th theo thc t, [kg]; kg/sGii thch kt qu sai s

Sai s ca nng tng i ln gia thc t v l thuyt, nguyn nhn do p sut ht chn khng khng n nh dn n nng khng ng u gia cc giai on gy sai s. Sai s thi gian do qu trnh thao tc. Tnh nng lng v cc i lng cha bit + Tnh cn bng nhit cho thit b ngng t v xc nh lu lng nc s dng trong gii nhit ngng t.

Ta c: r = Cn.tn Vi: Cn l nhit dung ring ca nc ngng 30C = 4200 j/kg.

tn l nhit nc ngng t 30C Bng kt qu tnh cn bng nhit cho thit b ngng t SSTW (kg)Nhit ngng t r (j/kg) *Nhit hi th tht (0C)Lng nhit ngng t QntNhit nc vo tv (0C)Nhit nc ra tr (0C)

10,48012600079604803049

20,54012600080680403049

30,65512600078825303049

40,75012600075945003049

50,38512600080485103050

60,41012600080516603050

Xc nh lu lng nc s dng trong gii nhit ngng t. Theo nh lut bo ton nhit

Ta c: Q1 + Q2 = Q3 + Q4 + Q5 + Q6 + Q7 Do: Q6 + Q7 = 10 % (Q1+Q2)

G.C .t + Gn.Cn.tn = Gc.Cc.tc + W.i+ Gn.Cn.tv + 0.1(G.C.t + Gn.Cn.tn)

=

Vi tv l nhit ti vch thit b (cho gn bng nhit si dung dch ang c c)

tn l nhit nc nng v o ( nhit ci t). + Tnh cn bng nhit cho thit b c c v xc nh lng nhit m ngun nng cung cp.

Nhit dung ring ca dung dch ng:

Trong : t l nhit ca dung dch (0C).

x l nng ca dung dch (%).

Q1 = G.C.t : nhit do dung dch mang vo. Q2 = Gn.Cn.tn: nhit do nc nng cung cp. Q3 = Gc.Cc.tc: nhit lng do dung dch ng mang ra. Q4 = W.i: nhit do hi th mang ra. Q5 = Gn.Cn.tv: nhit cn li sau khi lm nng dung dch ng. Q6 = Qc: nhit do qu trnh c c. Q7 = Qmt: nhit tn tht ra mi trng.1.6. V TH:

+ th biu din quan h gia ch s Bx vi thi gian c c.Thi gian0102030405060

Bx192122,827313846

+ th biu din quan h gia lng nc ngng thu c v thi gian c c.Thi gian0102030405060

Lng nc ngng0480540655750385410

1.7. KT LUN V NHN XT

Thit b c c gin on mt ni s dng trong th nghim c c, gip chng ta thc hnh v hiu v quy trnh cng nh cc cch vn hnh ca thit b c c. Qu trnh lm tng nng ca dung dch bng cch tch mt phn dung mi nhit si trong mi trng chn khng nn nhit si ca dung dch ng gim, lm gim s hao ph nhit nng v gip cho sn phm khng b bin tnh khi nhit cao.

Trong qu trnh thc hnh th nghim s khng trnh khi s sai xt v thng s, nhit , thi gian. Nguyn nhn ch yu: Cch vn hnh my cn chm. Thng s thit b khng n nh. Pha dung dch cha chnh xc. Thi gian khng ng u.Cch hn ch:

Cn nm vng kin thc trc khi thc hnh th nghim. V sinh v khi ng thit b nhit v p sut n nh. Thao tc vn hnh nhanh, pha dung dch phi chun. Tnh ton cn thn v chnh xc.Bi 2: TRUYN NHIT NG LNG NG

1. C s l thuyt

Qu trnh truyn nhit trong thit b dng ng lng ng l mt v d ca s truyn nhit phc tp. y din ra s trao i nhit gia hai lu cht c ngn cch bi vch ngn kim loi, bao gm truyn nhit i lu t dng nng n vch, dn nhit qua thnh ng kim loi v i lu nhit gia dng lnh vi thnh ng.

1.1. Phng trnh cn bng nhit lng cho hai dng lu cht

Q = G1C1 ( tv1 tR1) = G2C2 ( tR2 tv2), W

Trong :

G1, G2 : Lu lng dng nng v lnh, kg/s

C1, C2 : nhit dung ring trunh bnh ca dng nng v dng lnh, J/kg..

tv1, tR1: Nhit vo v ra ca dng nng.

tv2, tR2: Nhit vo v ra ca dng lnh.

1.2. Phng trnh biu din qu trnh truyn nhit

- Lng nhit Q truyn qua tng phng trong 1 n v thi gian

Q = K.F., W

Trong :

K : H s truyn nhit,

F : Din tch b mt truyn nhit,

: Hiu s nhit trung bnh,

H s truyn nhit cho tng nhiu lp theo cng tnh theo cng thc sau :

Vi :

: H s cp nhit ( hai pha ca tng, gia lu th v b mt tng), (W/m2.).

r1,r2: Nhit tr ca cn bn hai pha ca tng,

: Nhit tr ca lp tng th i, m2.K/W.

: B dy lp tng th i, m.

: H s dn nhit tng ng vi lp tng th i, W/m..

Phng trnh truyn nhit qua tng hnh tr nhiu lpQ = KL.L ,(W)

Trong :

KL: H s truyn nhit ca 1m chiu di ng, (W/m.K)

L : Chiu di ng, m

H s truyn nhit KL i vi tng hnh tr c n lp xc nh theo cng thc :

Vi :

: H s cp nhit ( hai pha ca ng, gia lu th v b mt ng, W/m2.K.

r1, r2: Nhit tr ca cn bn pha trong v ngoi ca ng, m2.K/W.

d1 v dn+1: ng knh trong v ngoi ca ng, m.

di v di+1 : ng knh trong v ngoi ca lp th i, m.

: H s dn nhit ca lp tng ng th i, W/m.K.

- bi th nghim ny, ta tin hnh th nghim vi ng truyn nhit, do vy ta xem nh l truyn nhit tng hnh tr 1 lp nn cng thc trn tr thnh :

Q = KL..L

L : Chiu di ng, m.

KL : H s truyn nhit di, W/m.K.

: Chnh lch nhit trung bnh logarit, K.

1.3. chnh lch nhit trung bnh logarit (hiu s nhit trung bnh)

1.4. H s truyn nhit di l thuyt KL

Trong :

dng, dtr : ng knh ngoi v trong ca ng truyn nhit, m.

: H s dn nhit ca ng, W/mK.

rb : Nhit tr ca lp cu.

db : ng knh ca lp cu, m.

bi th nghim ny lp cu coi nh khng ng k, tc l rb/db 0.

1.5. H s cp nhit gia vch ngn v dng lu cht c tnh theo chun s Nusselt

Nu =

Trong :

Nu = A.RemPrn

Cc h s A, n, m, l cc h s thc nghim, ty thuc vo cc yu t sau: Ch chy ca cc dng lu cht.

S tng quan gia dng chy v b mt truyn nhit.

c im b mt truyn nhit ( nhm, hnh dng,)

2. Tin hnh th nghim.

2.1. S nguyn l thit b

S NGUYN L

A. in tr un nc a. Cng tc tng

B.Ni un nc nng b. Cng tc bm

C.Bm nc nng c. Cng tc in tr un nng.

D. Lu lng k d. ng h hin th nhit .

E. TBTN kiu chy ngang

F. TBTN kiu chy dc

V. Cc van

Loi ngKch thc

ng trong

(mm)Kch thc

ng ngoi

(mm)Chiu di

(mm)

Chy dc18/2230/341050

Chy ngang18/2230/341050

2.2. Cc bc thc hin th nghim

2.2.1. Chun b th nghim

1. Kim tra mc nc bn trong ni un

2. Kim tra nc dng lnh trong cc ng

3. M cng tc tng

4. M cng tc gia nhit ni

2.2.2. kho st qu trnh truyn nhit trong ng chy vung gc

1. o lu lng dng nng

M Van 4, Van 5

ng Van 6

M cng tc bm nc nng

Chnh lu lng dng nng bng Van 10

2. o lu lng dng lnh

M Van 6

ng Van 4, Van 5

M Van 2, Van 3

ng Van 1

Chnh lu lng dng lnh bng Van 9 3. o nhit cc dng

- Nhn nt N3 o nhit dng nng vo v ghi nhn tnv Nhn nt N4 o nhit dng nng ra v ghi nhn tnr Nhn nt L1 o nhit dng lnh vo v ghi nhn tLV Nhn nt L2 o nhit dng lnh ra v ghi nhn tLR2.2.3. kho st qu trnh truyn nhit trong ng chy dc

1. o lu lng dng nng

M Van 4, Van 5

ng Van 6

M cng tc bm nc nng

Chnh lu lng dng nng bng Van 10.

2. o lu lng dng lnh

M Van 6

ng Van 4, Van 5

M Van 2, Van 3

ng Van 1

Chnh lu lng dng lnh bng Van 8

3. o nhit cc dng

Nhn nt N5 o nhit dng nng vo v ghi nhn tNV Nhn nt N4 o nhit dng nng ra v ghi nhn tNR Nhn nt L1 o nhit dng lnh vo v ghi nhn tLV Nhn nt L2 o nhit dng lnh ra v ghi nhn tLR2.2.4. Ngng

Xoay cng tc ca GIA NHIT ngc chiu kim ng h. n hot ng (mu ) tt. Cm gia nhit ngng hot ng.

Xoay cng tc ca Bm. Bm nng ngng hot ng.

Tt CB.

ng tt c cc vanI. X L KT QU

1.1. Kho st qu trnh truyn nhit trong ng chy dc

Bng 2.1. Kt qu o cho mt loi ng

Lu lng dng nng (lt/ph)369

Lu lng dng lnh (lt/ph)tv1tR1tv2tR2tv1tR1tv2tR2tv1tR1tv2tR2

3

554730375548303854493038

6

554630375548303853483038

9

554630365447303753473038

1.1.1. Tnh nhit lng Q v tn tht nhit

Dng nng: Q = G1C1(tv1 tr1) , W

Dng lnh: Q = G2C2(tr2 tv2) , W

Tn tht nhit: Q = Q1 Q2 ,W Bng s liu G, C

Dng nng:

GNGN(kg/s)tnvtnrtntbP (kg/m3)C (J/Kg)

30,049554751987,64181

0,049554650,5987,854182,875

0,049554650,5987,854182,875

60,099554851,5987,354183,625

0,099554851,5987,354183,625

0,099544750,5987,854182,875

90,148544951,5987,354183,625

0,148534850,5987,854183,875

0,148534750988,14182,5

Dng lnh:

GLGL (kg/s)tnvtnrtntbP(kg/m3)C(J/kg )

30,0497303733,5993,954176,625

0,0498303834996,24176,5

0,0498303834996,24176,5

60,0997303733,5993,954176,625

0,0996303834996,24176,5

0,0996303834996,2

90,149303633995,94176,75

0,149303733,5994,54176,625

0,149303834994,34176,5

Bng 2.2. Kt qu tnh nhit lng v tn tht nhit

Lu lng dng nng (lt/ph)369

Lu lng dng lnh (lt/ph)Q1Q2QQ1Q2QQ1Q2Q

31638,931453,04185,9122899,252914,8715,623095,883734,01-638,13

61844,651,663,918180,732899,253,327,835428,5853096,074352,22-1260,15

91844,651,663,918180,732898,733,327,835429,1053714,064978,39-1264,33

1.1.2. Tnh hiu nhit trung bnh tlog

Hnh 2.1: S phn b nhit khi truyn nhit qua vch ngn Trng hp ng lng ng song song ngc chiu

3. Nhit trung bnh ca dng nng

4. Nhit trung bnh ca dng lnh

5. Hiu nhit

t1 = tv1 tr2t2 = tr1 tv2Sau khi tnh so snh nu ci no ln hn th l tmax ci no nh hn l tmin6. chnh lch nhit trung bnh logarit

Bng 2.3. Kt qu tnh hiu s nhit trung bnh logarit

Lu lng dng nng (lit/ph)369

Lu lng dng lnh (lit/ph)tlogtlogtlog

317,4917,4917,46

616,9817,4916,45

917,46015,98

1.1.3. Tnh h s truyn nhit di thc nghim

Q = KL. tlog . L

L: Chiu di ng (1050 mm = 1,050 m)

KL: H s truyn nhit di, W/mK.

tlog: Chnh lch nhit trung bnh logarit, K.

Bng 2.4. Kt qu tnh h s truyn nhit di thc nghimLu lng dng nng (lt/ph)369

Lu lng dng lnh (lt/ph)QLtlogKLQLtlogKLQLtlogKL

31432,581,0517,4979,122914,871,0517,49158,723734,011,0517,46203,676

61,663,9181,0516,9893,333,327,8351,0517,49181,214356,221,0516,45252,206

91,663,9181,0517,4690,763,327,8351,050Khng xc nh4978,391,0515,98296,704

1.1.4. Tnh h s cp nhit 1, 2

Xc nh ch chy ca lu cht bng chun s Re.

Trong :

: Vn tc dng, m/s.

v : nht ng hc ca lu cht, m2/s.

l : Kch thc hnh hc c trng, m. l = F : Din tch mt ct (tit din ngang m dng lu chuyn ng qua), m2.

: Chu vi tit din t (chu vi m cht lng tip xc vi b mt trao i nhit), m.

i vi trng hp ng lng ng song song.

Dng nng: y tit din l hnh trn l = dtr

Tnh tc chy ca dng nng:

Bng 2.5: Kt qu tnh chun sRe1

Gn(lt/ph)Fn (m2)dtdn(m/s)ttbnV(m2/s)Re1

32,54.10-40,0180,197510,548. 10-66470,8

51,50,544. 10-66518,4

51,50,544. 10-66518,4

60,39450,50,552. 10-612847,8

51,50,544. 10-613036,8

50,50,552. 10-612847,8

90,59150,50,552. 10-619271,7

50,50,552. 10-619271,7

500,556. 10-619133,1

Dng lnh: tit din l hnh vnh khn.

Tnh tc chy ca dng lnh:

Bng 2.6: Kt qu tnh chun s Re2Gl(lt/ph)Fl (m2)dtdl(m/s)ttblV(m2/s)Re2

33,27.10-48,025.10-30,15333,50,7541628,4

340,7471643,7

340,7471643,7

60,30633,50,7543256,8

340,7473287.3

340,7473287.3

90,459330,7614840,3

33,50,7544885,2

340,7474931

Bng 2.10. Kt qu h s cp nhit ca dng nng 1

ttbnPr1 x 10-3 (N/m2) Prv1Nun(((1

513.5620,5533,2640,860,64911397.873

51,53,5280,54840,880,64971393.25

51,53,5280,54840,880,64971393.25

50,53,6270,563268.520,6492552.01

51,53,5280,54871,170,64972554.04

50,53.6270,563271,110,6492552.01

50,53.6270,563298,360,6493529.66

50,53.6270,563298,360,6493529.660

503.630,562498,330,6483505.32

Bng 2.11. Kt qu h s cp nhit ca dng lnh 2

ttbLPr2Prv2

x 10-3

(N/m2)NuL

Gr

2

33,55,14985.420,769411,3093,441.10-4102799,50,624879,4

345,0830,760711,3063,474. 10-4107317,80,625880,5

345,0830,760711,3063,474. 10-4107317,80,625880,5

33,55,14980,769414,2153,441. 10-4102799,50,6241105,3

345,0830,760714,2123,474. 10-4107317,80,6251106,9

345,0830,760714,2123,474. 10-4107317,80,6251106,9

335,920,88316,2513,408. 10-498457,40,6231261,6

33,55,14980,769416,2513,441. 10-4102799,50,6241263,6

344,0830,760716,1773,474. 10-4107317,80,6251259,9

Bng 2.12. Kt qu tnh h s cp nhitSTTRe1Re21 (W/m2)2(W/m2)

16470,81628,41397,873879,4

26518,41643,71393,25880,5

36518,41643,71393,25880,5

412847,83256,82552,011105,3

513036,83287.32554,041106,9

612847,83287.32552,011106,9

719271,74840,33529,661261,6

819271,74885,23529,661263,6

919133,149313505,321259,9

1.1.5. H s truyn nhit di l thuyt KL

- dtr = 0,018 (m)

- dng = 0,022 (m)Bng 2.13 . Kt qu tnh h s truyn nhit di l thuyt

STT1 (W/m2)2(W/m2)(W/m )KL* (W/m2)

11473,5879,423,233,52

21475,5880,533,56

31475,5880,533,56

42470,51105,346,24

52568,81106,946,88

62563,91106,946,85

73546,41261,656,08

83546,41263,656,14

93539,91259,956,00

1.1.6. Lp bng kt qu tnh h s truyn nhit di thc t v l thuyt theo ch chy dc.

Bng 2.14. Kt qu tnh h s truyn nhit KL v KL*STTRe 1Re 2KL (W/m2)KL *(W/m2)

16470,81628,479.11333,52

26518,41643,790.39633,56

36518,41643,790.55233,56

412847,83256,8162.97846,24

513036,83287.3157.12546,88

612847,83287.3192.22346,85

719271,74840,3203.82356,08

819271,74885,2Khng xc nh56,14

919133,14931296.81456,00

1.1.7. Dng th KL*, KL theo Re.

Hnh 2.2: th KL theo Re

Hinh 2.3: thi KL* theo Re

So snh s sai s gia KL* v KLKLKL*Sai s

79.1233.5245,6

158,7233.56125,16

203,67733.56170,117

93,3346.2447,09

181,2146.88134,33

252,20546.85205,355

90,7656.0840,68

Khng xc nh56.14Khng xc nh

296,70456.00240,704

1.2. Kho st qu trnh truyn nhit trong ng chy vung gc

Nhit trung bnh ca dng nng

Nhit trung bnh ca dng lnh

Hiu nhit

t1 = tv1 tv2t2 = tr1 tr2Sau khi tnh so snh nu ci no ln hn th l tmax ci no nh hn l tmin chnh lch nhit trung bnh logarit

Bng 2.3. Kt qu tnh hiu s nhit tru

Lu lng dng nng (lit/ph)369

Lu lng dng lnh (lit/ph)tlogtlogtlog

316,3716,3716,67

615,6616,3715,61

916,3715,9914,92

1.2.1. Tnh h s truyn nhit di thc nghim

Q = KL. tlog . L

L: Chiu di ng (1050 mm = 1,050 m)

KL: H s truyn nhit di, W/mK.

tlog: Chnh lch nhit trung bnh logarit, K.Bng 2.4. Kt qu tnh h s truyn nhit di thc nghimLu lng dng nng (lt/ph)369

Lu lng dng lnh (lt/ph)QLtlogKLQLtlogKLQLtlogKL

31452.8651,0516,3784.5251660.081,0596.5890.391660.081,0516,6794.843

62905.731,0515,66176.7152885.531,0516,37167.873320.1671,0515,61202.567

93736.691,0516,37217.3954358.5951,0515,99259.6024980.251,0514,92317.902

1.2.2. Tnh h s cp nhit 1, 2Xc nh ch chy ca lu cht bng chun s Re.

Trong :

: Vn tc dng, m/s.

v : nht ng hc ca lu cht, m2/s.

l : Kch thc hnh hc c trng, m.

l =

F : Din tch mt ct (tit din ngang m dng lu chuyn ng qua), m2.

: Chu vi tit din t (chu vi m cht lng tip xc vi b mt trao i nhit), m.

i vi trng hp ng lng ng song song.

Dng nng: y tit din l hnh trn l = dtr

Tnh tc chy ca dng nng:

Bng 2.5: Kt qu tnh chun s Re1

Gn(lt/ph)Fn (m2)dtdn(m/s)ttbnV(m2/s)Re1

32,54.10-40,0180,197510,548. 10-66470,8

51,50,544. 10-66518,4

51,50,544. 10-66518,4

60,39450,50,552. 10-612847,8

51,50,544. 10-613036,8

50,50,552. 10-612847,8

90,59150,50,552. 10-619271,7

50,50,552. 10-619271,7

500,556. 10-619133,1

Dng lnh:

Tit din: FL = l.(D1 d2) = 1,05.(0,030 0,022) = 8,4.10-3 (m2)

l = dtdl = D1 d2 = 0,030 0,022 = 8.10-3 (m).

Tnh tc chy ca dng lnh:

Bng 2.20: Kt qu tnh chun s Re2

Gl(lt/ph)F2 (m2)dtdl(m/s)ttblV(m2/s)Re2

38,4.10-38.10-35,9524.10-333,50,754. 10-663,16

340,747. 10-663,75

340,747. 10-663,75

60,011933,50,754. 10-6126,26

340,747. 10-6127,44

340,747. 10-6127,44

90,0179330,761. 10-6188,17

33,50,754. 10-6189,92

340,747. 10-6191,70

Chn nhit vch ca dng nng l: 530CBng 2.21. Kt qu h s cp nhit ca dng nng 1ttbnPr1prv1Nun(((1

513,4843,37278,3470,64912825.280

51,53,45678,2990,64972826.159

51,53,45678,2990,64972826.159

50,53,512118,8410,6494284.878

51,53,456118,6780,64974283.616

50,53.512118,8400,6494284.842

50,53.512151,5720,6495465.013

50,53.512151,5720,6495465.013

503.54151,6740,6485460.264

Chn nhit vch ca dng lnh l: 280CBng 2.22. Kt qu h s cp nhit ca dng lnh 2

ttbLPr2Prv2NuL

2

33,55,0325,747,1050,624554.190

344,9767,0890,625553.828

344,9767,0890,625553.828

33,55,03210,0450,624783.510

344,97610,0210,625782.891

344,97610,0210,625782.891

335,08712,3480,623961.601

33,55,03212,3200,624960.960

344,97612,2910,625960.234

Bng 2.23. Kt qu tnh h s cp nhit

STTRe1Re21 (W/m2)2(W/m2)

16470,863,162825.280554.190

26518,463,752826.159553.828

36518,463,752826.159553.828

412847,8126,264284.878783.510

513036,8127,444283.616782.891

612847,8127,444284.842782.891

719271,7188,175465.013961.601

819271,7189,925465.013960.960

919133,1191,705460.264960.234

1.2.2. H s truyn nhit di l thuyt KL

- dtr = 0,018 (m)

- dng = 0,022 (m)

Bng 2.24. Kt qu tnh h s truyn nhit di l thuyt

STT1 (W/m2)2(W/m2)(W/m )KL (W/m2)

12825.280554.19023,229,635

22826.159553.82829,622

32826.159553.82829,622

44284.878783.51041,719

54283.616782.89141,691

64284.842782.89141,693

75465.013961.60150,868

85465.013960.96050,842

95460.264960.23450,805

1.2.3. Lp bng kt qu tnh h s truyn nhit di thc t v l thuyt theo ch chy vung gc.Bng 2.25. Kt qu tnh h s truyn nhit KL* v KLSTTRe 1Re 2KL (W/m2)KL* (W/m2)

16470.863.1629.63584.525

26518.463.7529.62296.581

36518.463.7529.62294.843

412847.8126.2641.719176.715

513036.8127.4441.691167.876

612847.8127.4441.693202.567

719271.7188.1750.868217.395

819271.7189.9250.842259.602

919133.1191.7050.805317.902

1.2.4. Dng th KL*, KL theo Re.

Hnh 2.4: th KL

Hnh 2.5: th KL* theo Re So snh s sai s gia KL* v KLKL*KLSai s

84.52529,63554.89

96.58129,62266.96

94.84329,62265.22

176.71541,719135

167.87641,691126.19

202.56741,693160.87

217.39550,868166.53

259.60250,842208.76

317.90250,805267.1

II. Kt lun v nhn xt:

Sau khi tnh ton th tn tht nhit l khng ng k, c khi khng tn tht nhit do chnh lch nhit nh. Da vo bng so snh s sai s gia KL* v KL trn th thy sai s l ng k.

Nguyn nhn: Do cc bc tin hnh th nghim cha nhp nhng , cc ch s trn my khng c nhy, dn n nhit chnh lch ln.

Cch khc phc:

Phi nm vng l thuyt v cc bc tin hnh bi th nghim truyn nhit. Kim tra cc van ng theo trnh t hng dn. c cc thng s cn o chnh xc, ng thi im.BI 3. CHNG CT

PHN I: C S L THUYT.

1. Khi nim chng ct:

nh ngha chng ct:

Chng ct l qu trnh dng tch cu t ca mt hn hp lng cng nh hn hp kh-lng thnh cc cu t ring bit da vo bay hi khc nhau ca cc cu t trong hn hp ( cng iu kin).

Cc phng php chng ct:

- Chng ct n gin: dng tch cc hn hp gm cc cu t c bay hi rt khc nhau.

- Chng ct bng hi nc trc tip: dng tch cc hn hp gm cc cht kh bay hi v tp cht khng bay hi.

- Chng ct: dng tch hon ton hn hp cc cu t d bay hi c tnh cht ha tan mt phn hoc ha tan hon ton vo nhau.

nh lut Henry:

i vi dung dch l tng p sut ring phn p ca kh trn cht lng t l vi phn mol x ca n trong dung dch.

y=H.p

Trong :

H: Hng s Henry. (khi nhit tng th H tng)

nh lut Raoult:

p sut ring phn ca mt cu t trn dung dch bng p sut hi bo ha ca cu t ( cng nhit ) nhn vi nng phn mol ca cu t trong dung dch.

p=pbh.x

Trong :

p: p sut hi ring phn ca cu t trong hn hp hi.

pbh: p sut hi bo ha ca cu t cng nhit .

x: nng phn mol ca cu t trong dung dch.

2. M hnh mm l thuyt:

M hnh mm l thuyt l m hnh ton n gin nht da trn cc c s sau:

- Cn bng gia hai pha lng - hi cho hn hp hai cu t.

- iu kin ng lc hc lu cht l tng trn mm l cho hai pha lng - hi l:

+ Pha lng phi ha trn hon ton trn mm.

+ Pha hi khng li cun cc git lng t mm di ln mm trn v ng thi c nng ng nht ti mi v tr trn tit din.

+ Trn mi mm lun t s cn bng gia hai pha.

( Phn loi qu trnh chng ct

(Chng ct n gin

Dng tch hn hp lc gm cc cu t c nhit si rt khc nhau, thng thng ngi ta s dng chng ct n gin tch hn hp rn l lng trong pha lng.

(Chng ct li cun hi nc.

Dng tch hn hp kh bay hi, cu t c nhit si cao so vi iu kin cu t ny khng tan trong nc. Ngi ta tin hnh chng ct bng cch cho hi nc bo ha li qua hn hp lng cn chng ct cu t no khng tan trong nc s b hi nc li cun ln khi mt thong ca hn hp v i ra ngoi theo ng ng dn sau tin hnh ngng t hi nc bo ha ta s thu c hn hp lng gm nc v cu t cn tch, hai cu t ny khng tan vo nhau nn tch lp v ta d dng thu c cu t cn phn tch.

(Chng ct tinh khit hn hp 2 cu t

tng gi thnh v tinh khit ca dung mi ngi ta s dng qu trnh chng ct tinh khit vi 1 nguyn liu l sn phm ca chng ct n ginS chng ct lin tc hn hp 2 cu t.

3. Phng trnh cn bng vt cht:

F= D+W

F.xF = D.xD + W.xWTrong :

F: Sut lng nhp liu.

D: Sut lng sn phm nh.

W: Sut lng sn phm y.

xF: Nng nhp liu (ca cu t d bay hi).

xD: Nng sn phm nh (ca cu t d bay hi).

xW: Nng sn phm y(ca cu t d bay hi).

4. Hiu sut:

chuyn t s mm l thuyt sang s mm thc ta cn phi bit hiu sut mm. C ba loi hiu sut mm c dng l: Hiu sut tng qut, lin quan n ton thp; Hiu sut mm Murphree, lin quan n mt mm; Hiu sut cc b, lin quan n mt v tr c th trn mt mm.

- Hiu sut tng qut Eo: l hiu sut n gin khi s dng nhng kn chnh xc nht, c nh ngha l t s gia s mm l tng v s mm thc cho ton thp.

Eo = ( s mm l tng)/(s mm thc).

- Hiu sut mm Murphree: l t s gia s bin i nng pha hi qua mt mm vi s bin i nng cc i c th t c khi pha hi ri mm cn bng vi pha lng ri mm th n.

EM = ( yn - yn+1) / (y*n - yn+1)Trong :

yn: nng thc ca pha hi ri mm th n.yn+1: nng thc ca pha hi vo mm th n.

y*n: nng pha hi cn bng vi pha lng ri ng chy chuyn mm th n.

Ni chung, pha lng ri mm c nng khng bng vi nng trung bnh ca ph lng trn mm nn dn n khi nim hiu cc b.

- Hiu sut cc b c nh ngha nh sau:

EM = (y'n - yn+1) / (y'en - y'n+1)Trong :

yn: nng pha hi ri khi v tr c th trn mm n

yn+1: nng pha hi mm n ti cng v tr.

yen: nng pha hi cnbng vi pha lng ti cng v tr.5. Mi quan h gia hiu sut mm Murphree v hiu sut mm tng qut:

Hiu sut tng qut ca thp khng bng vi hiu sut trung bnh ca tng mm. Mi quan h gia hai hiu sut ny ty thuc trn dc tng i ca ng cn bng v ng lm vic. Khi mG/L>1 hiu sut tng qut c gi tr ln hn v mG/L F =0.211 (mol).

D ( sn phm nh) cng lm tng t, th V o c vo:

Vy ta c:

* m1 = D.V = 810 x 5.7 x 10-3 = 4.617 (kg)

n1 = m/M = 4.617 / 46 = 0.1 (mol).

* m2 = D.V = 810 x 5.4 x 10-3 = 4.374 (kg)

n1 = m/M = 4.374/ 46 = 0.095 (mol).

* m3 = D.V = 810 x 5.16 x 10-3 = 4.179 (kg)

n3 = m/M = 4.179 / 46 = 0.091 (mol).

nR = (810*10*10-3)/46 = 0.176 (mol)

* Bng 4.2 Bng kt qu tnh cn bng vt cht.

STTF (mol)D (mol)xD (%mol)xF (%mol)W (mol)xW (%mol)

10.2110.10.630.080.1110.415

20.2110.0950.550.080.1160.305

30.2110.0910.450.080.120.2

- Tnh f: R = 0.176

f1 = 0.211/0.1= 2.11

f2 = 0.211/0.095 = 2.22

f3 = 0.211/0.091 = 2.32

- Tnh cc phng trnh ng lm vic:

Phng trnh ng ct:

Phng trnh ng chng:

Phng trnh ng ct:

Phng trnh ng chng:

Tng t cho nhng stt tip theo, ta c bng tng kt nh sau:

Bng 4.2 Bng kt qu tnh ng lm vic.

STTRfPhng trnh ng ctPhng trnh ng chng

10.1762.11y = 0.15x+0.536y = 1.944x-0.392

20.1762.22y = 0.15x+0.468y = 2.037x-0.316

30.1762.32y = 0.15x+0.383y = 2.122x-0.224

- V v xc nh s mm l thuyt:- Xc nh hiu sut ca qu trnh chng ct.

TNV tr mmL0S mm l thuytHiu sut mm tng qut.

15

23

31

Nhn xt:

Do s liu c c trong thc nghim nh nn qu qu trnh v th xc nh mm khng thc hin c. c bit l Xd s liu qu nh ch t 0,5 tc l ch nm gia th (thng th Xd = 0,7 0,9) nn ng chng v ct nm lt vo trong v ch chim mt phn nh pha trong ng cn bng.

C th do qu trnh thc nghim thao tc khng chun xc hoc do s c thit b nn s liu thu c khng cn chnh xc. Gy kh khn cho vic v th xc nh s mm l thuyt. V tht s th cng khng th xc nh c s mm l thuyt trong bi.

Bai 4: SY I LU

1. MC CH TH NGHIM

Sinh vin bit cch vn hnh thit b sy.

Xy dng ng cong sy v ng cong tc sy

Xc nh cc thng s sy: tc sy ng tc, m ti hn, m cn bng, thi gian sy ng tc v gim tc

nh gi sai s ca qu trnh sy.

2. C S L THUYT

2.1 nh ngha

Sy i lu l qu trnh tch m ra khi vt liu bng cch cp nhit cho m bay hi. Trong , c hai qu trnh truyn nhit v truyn m u c thc hin bng phng php i lu

2.2 c trng ca qu trnh sy

Qu trnh sy din ra rt phc tp, c trng cho tnh khng thun nghch v khng n nh. N din ra ng thi 4 qu trnh: truyn nhit cho vt liu, dn m trong lng vt liu, chuyn pha v tch m vo mi trng xung quanh

2.3 Xc nh tc sy theo cn bng nhit ca qu trnh sy

Lng nhit do dng tc nhn sy cung cp cho khong thi gian d(

(1)

Nhit ny c tiu hao

un nng vt liu:

(2)

Bay hi m v qu nhit hi: [r+Ch(t-th)]dGa

(3)

Trong :

(: h s cp nhit t tc nhn sy vo vt liu sy, W/m2

F: b mt vt liu, m2t, (, th: nhit tc nhn sy, vt liu v hi bo ha,

Go, Co: khi lng v nhit dung ca vt liu sy, kg; j/kg

Ga, Ca: khi lng v nhit dung ca m, kg; j/kg

r: An nhit ha hi ca m, j/kh

Ch: Nhit dung ring ca hi m, j/kg

Lng m bc hi trong thi gian d(:

dGa = d(GoU) = GodU

(4)

U: hm m (hay m) ca vt liu, tnh theo vt liu kh, kg m/kg vt liu kh

T (1), (2), (3) v(4), thit lp cn bng nhit:

(F(t-()d( = (GoCo + GaCa)d( + Go[r + Ch(t - th)]dU

(5)

T (5) rt ra:

y l biu thc tnh tc sy theo cn bng nhit

2.4 Phng trnh c bn ca ng hc qu trnh sy

Theo phng trnh truyn m t vt liu vo tc nhn sy:

dGa = kpF(pm-p)d(

(7)

Vi:kp: h s truyn m trong pha kh kg/m2.h.(p

Pm, p: p sut ca hi m trn b mt vt liu v trong pha kh, mmHg (at)

Thay Ga=G0U vo (7) v bin i ta c:

(8)

Khi hi m khng b qu nhit (tc t=th) th biu thc (5) c bin i thnh:

(9)

q: cng dng nhit hay mt dng nhit

t:

Vi (o: khi lng ring ca vt liu kh, kg/m3

Vo: th tch vt kh, m3

C: nhit dung ring ca vt liu m, j/kg

Ro: bn knh qui i ca vt liu, m

Khi , nu b qua nhit lm qu nhit hi m, ta c:

(10)

vi : chun s Rebinde c trng cho ng hc qu trnh sy

Biu thc (10) l phng trnh c bn ca ng hc v sy, n cho bit s bin i m ca vt liu theo thi gian. Ta c th nhn c biu thc (10) khi gii h phng trnh vi phn m t truyn nhit truyn m trong vt liu. Nhng ni chung h phng trnh ny khng gii c bng phng php gii tch.

2.5 Lng nhit cp cho vt liu trong giai on sy gim tc (q2)

Trong giai on sy gim tc, ng cong tc sy c dng ng thng, nn tc sy trong giai on ny c biu din:

(11)

K: h s t l, gi l h s sy. N ph thuc vo tc sy v tnh cht ca vt liu m, 1/s

K chnh l h s gc ca ng cong tc sy giai on sy gim tc, nn:

(12)

: h s sy tng i, ph thuc vo tnh cht vt liu m

Uth: m ti hn

U*: m cn bng

N: tc sy ng tc, kg m/(kg vt liu kh.s)

Tch phn phng trnh (11) ta nhn c:

(13)

Hay logarit ha (8), ta c

(14)

Nh vy, nu bit c h s sy K, c th xc nh c thi gian cn thit thc hin giai on sy gim tc

H s sy tng i c xc nh bng thc nghim v c th tnh gn ng nh sau:

(15)

Vi Uo: m ban u ca vt liu

T ta c:

(16)

Thay (12) v (15) vo phng trnh (11), ta c:

(17)

Thay (17) vo (10) ta c

(18)2.6 Lng nhit cung cp cho vt liu trong giai on sy ng tc (q1)

Trong giai on sy ng tc, ton b lng nhit cung cp t dng tc nhn bng lng nhit bc hi m v nhit vt liu khng i nn:

2.7 Cng trao i nhit (q(x))

Nh vy, theo biu thc (20), khi bit chun s Rb s tnh c cng trao i nhit theo m ca vt liu.

2.8 ng cong sy v ng cong tc sy.

th ng cong tc sy

th ng cong sy

2.8.1 ng cong sy

L ng cong biu din s thay i ca m vt liu (U) theo thi gian sy

U = f

(21)Dng ca ng cong sy:

Ph thuc vo nhiu yu t nh lin kt gi m v vt liu, hnh dng kch thc; Cu trc vt liu, phng php v ch sy.

ng cong sy l hm ca qu trnh sy. V vy, tuy ch v phng php sy khc nhau nhng dng ng cng sy l tng t nhau.

2.8.2 ng cong tc sy:

L ng cong biu din mi quan h gia tc sy v m ( hm m) ca vt liu sy:

(22)

T biu thc (21) v (22), r rng ng cong tc sy l o hm ca ng cong sy.

2.9 Cc giai on ca qu trnh sy

2.9.1 Giai on un nng vt liu (AB)

Giai on ny xy ra nhanh vi khong thi gian ngn khng ng k. Ton b nhit do dng tc nhn cp dng un nng vt liu t nhit u ln nhit bu t (t).

Trong giai on ny lng m tch ra khng ng k, m vt liu gim khng nhiu v tc sy nhanh ln vi tc cc i (N). thng giai on ny b qua trong tnh ton.

2.9.2 Giai on sy ng tc (BC)

Trong giai on ny, tc khuch tn m t trong lng vt liu ra b mt ln hn tc bc hi m t b mt vt liu, nn b mt vt liu lun bo ha m.

Tan b lng nhit cung cp bc hi m b mt (m t do) v b mt bc hi l b mt ngoi ca vt liu khng i nn cc thng s sy sau y s khng i: Nhit b mt vt liu v tc sy; v m vt liu gim nhanh.

Thi gian sy trong giai on ny l (thi gian sy ng tc c xc nh t:

- (23)

Nn tch phn (23) ta c

(24)

Vi l m cui giai on sy ng tc.

2.9.3 Giai on sy gim tc (CD)

Do bc hi ht m b mt ch cn m lin kt, nn b mt bc hi b co hp li dn i su vo trong lng vt liu.

Tc khuch tn m trong vt liu chm lm gim tc chung.

Nhit ca vt liu tng dn t nhit bu t (t) n nhit dng tc nhn (t) nhit bu kh.

Lc ny; Trong vt liu xut hin 3 vng : m, bc hi v kh.

Trong giai on ny, nu ng cong tc sy c dng ng thng (hoc qui i sang ng thng N2 =ax +b) th ta c th phn tch tnh thi gian sy giai on sy gim tc ny () :

Vi U: m cn bng, m kt thc giai on sy gim tc.

2.10 Thi gian sy vt liu

Thi gian sy vt liu c tnh bng tng thi gian ca 3 giai on sy: t nng vt liu . Sy ng tc v sy gim tc . C th b qua giai on t nng vt liu, v giai on ny xy ra rt nhanh. Biu thc tnh thi gian sy nh sau:

(26)

Vi m vt liu cui qu trnh sy. Tng ng vi .U2> U v thng c ly : U2 = U + 2(%)

3. THIT B, DNG C, HA CHT V NGUYN VT LIU

A. HA CHT

STTTn ha chtQuy cch/v tnhS lngGhi ch

1

2

B. DNG C

STTTn dng cQuy cch/v tnhS lngGhi ch

1

2

C. THIT B

Tn thit bQuy cch/v tnhS lngGhi ch

1Thit b sy i lu1

2

4. S NGUYN L THIT B

1. Ca kh vo

5. Bung sy

2.Qut ly tm

6. Khy sy

3.Caloriphe

7. Ca ra kh thi

4. Cn

5. PHNG PHP TH NGHIM

5.1. Ni dung th nghim

Tin hnh sy bnh trng 2 ch ca Caloriphe:500C v 600C. t vt liu vo bung sy, ghi nhn khi lng vt liu sau khi lm m (G1). Sau c 2 pht ghi nhn gi tr cn v gi tr nhit bu kh, bu t. Tip tc n khi gi tr khi lng vt liu khng i trong vng 15 pht th dng ch th nghim ny v chuyn sang ch th nghim khc.

5.2. Tin hnh

5.2.1. Chun b th nghim:Xc nh khi lng vt liu kh ban u (G0) ca vt liu: G0=750 gram

M ca bung sy ra, t cn thn c gi tr cn (G0)

Lm m vt liu:

Sau khi cn xong, ly vt liu ra v nhng nh nhng (trnh rch vt liu) vo chu nc. Ch khong 30 giy cho nc thm u, ly vt liu ln v ro nc sau xp vo gi.

Chun b ng h eo tay o thi gian.

Kim tra h thng:

Lp li ca bung sy.

M ht cc van ca hai ca kh vo raChm y nc vo bu t (pha sau h thng)5.2.2. Khi ng h thng:

Khi ng qut: bt cng tc ca qut ht dng tc nhn vo v thi qua caloriphe gia nhit dng tc nhn.

Khi ng caloriphe, bt cng tc Caloriphe.

Ci t nhit cho Caloriphe nhit th nghim.

5.2.3. Tin hnh th nghim

Ch h thng hot ng n nh khi: nhit ca Caloriphe t gi tr mong mun (). Tin hnh sy vt liu nhit kho st.

5.3. o s liu trong ch th nghim.5.3.1. Cc s liu cn o: Khi lng, nhit bu kh, bu t v thi gian.

5.3.2. Cch c:

Khi lng (gam) khi t gi vt liu sy, c s hin th trn cn.

Nhit (0C) : Nhn nt tng ng cc v tr cn o v c s trn ng h hin s.Bng s liu th nghimSTTCh sy 500C

((ph)G(g)T()(0C)T(k)(0C)

T() voT() raT(k) voT(k) ra

10962/

2596050485553

31095050485553

41594050485553

52092750485553

62592050485553

73090750485553

83589750485553

94088550485553

104587050485553

115086550485553

125585350485553

136084450485553

146583550485553

157082750485553

167581750485553

178080550485553

188580050485553

199079250485553

2010078450485553

2110577450485553

5.4. Chuyn ch th nghim:M ca bung sy, ly vt liu ra lm m tip (lp li nh ban u).

Ci nhit Caloriphe gi tr tip theo cho ch sy mi.

Ch h thng hot ng n nh.

Lp li trnh t nh ch u.

5.5. Kt thc th nghim

Tt cng tt ca in tr Caloriphe.

Sau khi tt Caloriphe c 5 pht, tt qut cho Caloriphe ngui.6. PHC TRNH6.1. Tnh theo thc nghim:

m vt liu:

Tc sy : (%/h).

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)

(%/h)S liu x l c trnh by thnh bng sau :

STTT(pht)Gi(g)Wi(%)N(%h)TkTPb(mmHg)Ph(mmHg)Th sy

1036228,27555097,595,835

25360283,24555097,595,835

31035026,6715,96555097,595,835

41534025,3316,08555097,595,835

52032723,620,76555097,595,835

62532022,6711.16555097,595,835

73030720,9320,88555097,595,835

83529719,615,96555097,595,835

9402851819,2555097,595,835

10452701624555097,595,835

115026515,338,04555097,595,835

125525313.7319,2555097,595,835

136024412.5314,4555097,595,835

146523511,3314,4555097,595,835

157022710,2712,72555097,595,835

16752178,9316,08555097,595,835

17802057,3319,2555097,595,835

18858006,677,92555097,595,835

19901925,612,84555097,595,835

201001844.5312,84555097,595,835

211051743,215.96555097,595,835

Pb(mmHg) : p sut ring phn hi m trn b mt vt liu iu kin on nhit.

Ph(mmHg) : p sut hi m trong tc nhn sy.

(c tra trn gin khng kh m)

6.2 Tnh theo l thuyt:

- Cng m: Jm = am.(Pb(TB) Ph(TB)).760/B (kg/m2.h)

= (0,0229 + 0,0174. 1,6). (97,5 95,83). 760/760 = 0,0847 (kg/m2.h)

Trong :

Jm : Cng m.

B: p sut phng sy; B = 760mmHg.

am : H s trao i m tnh theo chnh lch p sut ( kg/m2.h.mmHg).

am = 0,0229 + 0,0174.Vk Vk : Tc kh trong phng sy ( chn Vk = 1,6 (m/s)).

Din tch b mt F :

F=d.r.4 =0,34.0,19.4= 0,02546(m) = 0,26(m2)

Vi : Di = d = 34cm = 0,34m

Rng = r = 19cm = 0.19m- Tc sy ng tc :Nt =100.Jm.F/Go (%/h).

- m ti hn :

W1 : m ban u trc khi sy(%).Wc : m cn bng = 3%.

- Thi gian sy :

Thi gian sy ng tc:

Thi gian sy gim tc:

Wcuoi : m cui qu trnh sy. 6.3. V th :V th thc nghim ng cong sy (W-t)

KT LUN V GII THCH

Cc nguyn nhn gy sai s trong qu trnh sy

Cn s dng xc nh khi lng vt liu sy kh c chnh xc v v tr rt cao, phi nhn thng mt cn khi c khi lng

Canh thi gian sy khng n nh

Cc sai s trong qu trnh tnh ton t vic lm trn s liu

Nhng thng s nhn c t qu trnh th nghim, ta tnh ra c nhng gi tr cn xc nh ca qu trnh sy, v nhng sai s trong vic thc hin cng nh do nhng sai st sn c trong thit b nn kt qu khng c nh mong i, qu trnh sy ko di thu c nhiu gi tr gip gim bt vic gy nn sai s khi ch thi gian sy qua lu.

Bai 5: CT CHM

1. MC CH TH NGHIM

1.1. Mc ch ca qu trnh hp thu:

Trong cng nghip sn xut ha cht c bn: sn xut ra cc loi axit bng cch hp thu kh vo trong nc nh: HCl, H2SO4 phn ring hn hp kh Av B.Trong cng nghip ch bin thc phm: bo ha CO2 cho bia,nc ngt, ru c gas nhm tng gi tr cm quan cho sn phm.Trong cng ngh ln men: Qu trnh hp thu nhm lm giu hm lng O2 ha tan trong pha lng ca b ln men hiu kh.

Trong k thut x l mi trng: Trong kh thi cng nghip c nhiu cu t c hi. x l kh thi t tiu chun thi ra mi trng ngi ta tin hnh hp thu cc cu t c hi bng dung mi l nc sch hay ha cht d x l hn.

1.2. Mc ch ca th nghim:

Kho st c tnh ng lc hc lu cht v kh nng hot ng ca ct chm bng cch xc nh:

nh hng ca vn tc dng kh v lng ln tn tht p sut ( gim p) khi i qua ct.

S bin i ca h s ma st ct kh fcktheo chun s Reynolds (Re) ca dng kh v suy ra cc h thc thc nghim. S bin i ca tha s ( lin h gia gim p ca dng kh qua ct kh v qua ct t theo vn tc dng lng.

2. C S L THUYT

2.1. gim p ca dng kh

gim p (Pck ca dng kh qua ct ph thuc vo vn tc khi lng G ca dng kh qua ct kh (khng c dng chy ngc chiu). Khi dng kh chuyn ng trong cc khong trng gia cc vt chm tng dn vn tc th gim p cng tng theo. S gia tng ny theo ly tha t 1,8 n 2,0 ca vn tc dng kh.

(1)

Vin = 1,8 2,0

Khi c dng lng chy ngc chiu, cc khong trng gia nhng vt chm b thu hp li. Dng kh do di chuyn kh khn hn v mt phn th tch t do gia cc vt chm b lng cht lng chim c. Khi tng vn tc dng kh ln, nh hng cn tr ca dng lng tng u n cho n mt tr s ti hn ca vn tc kh, lc gim p ca dng kh tng vt ln. im ng vi tr s ti hn ca vn tc kh ny c gi l im gia trng. Nu tip tc tng vn tc kh qu tr s ti hn ny, nh hng cn tr h tng gia dng lng v dng kh rt ln, (Pc tng mau chng khng theo phng trnh (1) na. Dng lng lc ny chy xung cng kh khn, ct im lt.

ng biu din log((Pc/Z) ( gim p sut ca dng kh qua mt dn v chiu cao ca phn chm trong ct) d kin nh trnh by trn hnh 1.

Hnh 1: nh hng ca G v L i vi gim p ca ct (Pc2.2. H s ma st fck theo Rec khi ct kh

Tr lc thp kh:

Trong :

h - chiu cao lp m, m

wo- vn tc pha kh

a - b mt ring, m2/m3( - xp, m3/m3(k khi lng ring ca khng kh, kg/m3fck - h s ma sat ca dng chy qua lp ht, ph thuc vo RekKhi Rek40:

2.3. gim p (Pc khi ct t

S lin h gia gim p ct kh (Pck v ct t (Pc c th biu din nh sau:

(Pc = ((Pck(6)

Do c th d kin: fc = (.fck (7)Vi (: h s ph thuc vo mc xi ti ca dng lng L, kg/m2s.

Leva ngh nh hng ca L ln ( nh sau:

( = 10(L(8)

haylog ( = (L(9)

Gi tr ( ty thuc vo loi, kch thc, cch thc sp xp vt chm (xp ngu nhin hay theo th t) v ln ca lu lng lng L. Th d vi vt chm l vng s Raschig 12,7 mm, chm ngu nhin, xp ( = 0,586; gi tr ca L t 0,39 n 11,7 kg/m2s v ct hot ng trong vng di im gia trng.

( = 0,084

Mt s ti liu cn biu din s ph thuc gia t s vi h s xi ti nh sau:

Khi A < 0,3 cho vt chm bng s c d < 30 mm, ta c:

(10)

(11)

2.4. im lt ca ct chm

Khi ct chm b ngp lt, cht lng chim ton b khong trng trong phn chm, cc dng chy b xo trn mnh lit, hin tng ny rt bt li cho s hot ng ca ct chm. Gi gi tr ca GL tng ng vi trng thi ny l GL*.

SHAPE \* MERGEFORMAT

Hnh 2: Gin lt ca ct chmZhavoronkov kt lun rng trng thi ngp lt xy ra khi hai nhm s sau c s lin h nht nh vi nhau cho mi ct.

(12)

v

(13)

Vifck: h s ma st ct kh.

v: vn tc di ca dng kh ngay trc khi vo ct, m/s.

: nht tng i ca cht lng so vi nc. , nu cht lng l nc th .

Do s lin h gia (1, (2 trn gin log(1 log(2 s xc nh mt gin lt ca ct chm, phn gii hn hot ng ca ct chm di ng ny.

3. S NGUYN L THIT BI- My thi kh

1,2-Van iu chnh lu lng dng kh

II- Lu lng k dng kh3-Van x nc ng trong ng kh

III- Ct chm

4,6-Van iu chnh lu lng dng lng

IV- Bn cha

5-Van to ct lng ngn kh

V- Bm

7-Van iu chnh mc nc trong ct chm

VI- Lu lng k dng lng8-Van x nhanh khi lt ct chm

D-lp m vng s Raschig 9-Van x y bn cha

4. PHNG PHP TH NGHIM

4.1. Chun b

- Lm quen vi h thng thit b, tm hiu cc van v tc dng ca n.

- Lm quen vi thit b o nhit , cc v tr o v cch iu chnh cng tc o.

- Lm quen vi cch iu chnh lu lng.

- Xc nh cc i lng cn o.

- Lp bng ghi kt qu o.

Kh

Lng(l/p)12345

0

4

5

6

7

8

9

10

4.2. Trnh t th nghim

1) Kha li tt c cc van lng (t 4 n 8).

2) M van 2 v kha van 1, 3.

3) Cho qut chy trong 5 pht thi ht m trong ct. Tt qut.

4) M van 4 v 7. Sau cho bm chy.

5) M van 5 v t t kha van 4 chnh mc lng y ct ngang bng vi ng nh mc g. Tt bm v kha van 5.

6) o gim p ca ct kh:

Kha tt c cc van lng li. M van 1 cn 2 vn ng. Cho qut chy ri t t m van 2 chnh lu lng kh vo ct.

ng vi mi gi tr lu lng kh chn ta c (Pck trn p k U theo mmH2O. o xong tt qut, ngh 5 pht.

7) o gim p khi ct t:

M qut v iu chnh lu lng kh qua ct khong 15 20%.

M van 4 v cho bm chy. Dng van 6 ti lu lng k chnh lu lng lng. Nu 6 m ti a m phao vn khng ln th dng van 4 tng lng lng.

ng vi lu lng lng chn c nh, ta chnh lu lng kh v c gim p (Pc ging nh (Pck trc . Ch l tng lng kh n im lt th thi.

Ch :

1. Trong qu trnh o gim p ca ct t, sinh vin cn canh gi mc lng y ct lun n nh chiu cao y bng cch chnh van 7. Nu cn, tng cng van 8 nc trong ct thot v bnh cha.

2. Khi tt my phi tt bm lng trc, m ti a van 8 sau tt qut BK.

5. X L S LIU

5.1. Cc s liu lin quan n ct chm

Ct thy tinh:

ng knh d = 0,09 m.

Chiu cao H = 0,805 m.

Chiu cao phn chm h = 0,6 m.

Vt chm xp ngu nhin, vng Raschig ng knh 16 mm, b mt ring a = 350 m2/m3, xp ( = 0,67.

BNG S LIU THC NGHIM

Lng

kh12345

00,51,12,93,36,4

41,123,25,18,5

51,33,23,66,69,9

61,82,95,18,414,3

72,54,37,613,819,5 (lt)

84,1711,717,120,1(lt)

95,710,414,819.5(lt)

108,111,820,8(lt)

5.2. Tnh ton th nghim:d=0,09 (m) (SGK)= 0,67 (SGK)Din tch ca ct chm:

S= .d2./4=3,14.(0,09)2.0,67/4=4,2602.10-3 (m2) 5.2.1. Tnh ct kh:

- Tnh G: (khi lng khng kh):

Ni suy kk 500C = 1,093(kg/m3)

1fit3/pht = 2,83.10-2 (m3/pht) = 2,83.10-2/60 (m3/s)

Tng t tnh c G4= 0,484, G5= 0.605- Tnh chun s Reck

Vi a=350 (m2/m3), kk 500C=1,956.10-5 (kg/m.s)

Tnh tng t ta c: w3= 0,222 (m/s), w4= 0,297 (m/s), w5= 0,371 (m/s)T ta tnh c Re: (SGK)

Tng t tnh c :

Rek2= 744,313

Rek3= 1116,469

Rek4= 1493,655

Rek5= 1865,811

Tnh fckV Reck > 40 nn ta tnh (SGK)

Tng t ta tnh c:

fck2= 4,263

fck3= 3,931

fck4= 3,709

fck5= 3,548

Tnh :

Vi (s ln s nh).98,1(N/m2) (1cmH2O=98,1N/m2)

Tnh (N/m2)/m vi Z= 0.6 (SGK)

Bng cc tr s kt qu khi ct kh L = 0 :

iG

kg/s.m2PCK

N/m2PCK/Z

(N/m2)/mRefckLogGlogReLog PCK/Z

Logfck

10,12149,0581,75373,0564,895-0,9172,5721,9120,69

20,242107,91179,85744,3134,263-0,6162,8722,2550,63

30,363284,49474,151116,4693,931-0,4403,0482,6760,59

40.484323,73539,551493,6553,709-0.3153,1742,7320,57

50,605627,841046,41865,8113,548-0,2183,2703,0200,55

6.3.2. Tnh ct t:

Ni suy k 300C = 1,166 (kg/m3) (sch k thut nhit)

EMBED Equation.DSMT4



EMBED Equation.DSMT4 Tnh chun s Re

(SGK-TRANG 46)Vi a=350 (m2/m3), k 300C=1,86.10-5 (kg/m.s)

L=4 (lt/pht)

Tnh Pic = (s ln s nh).98,1 (N/m2)

P1c = 1,1.98,1=107,91(N/m2)P2c = 2.98,1=196,20 (N/m2)P3c = 3,2.98,1= 313,92 (N/m2)P4c = 5,1.98,1= 500,31 (N/m2)P5c = 8,5.98,1= 833,85(N/m2) Tnh Pc/Z: Z=0,6

Tnh : (SGK-TR.45)M (SGK)

Tng t ta tnh c:

T tnh c fc:

Bng cc tr s kt qu khi ct t L = 4:

STTG, Kg/s.m2PcPc/Z, (N/m2)/mfcRec

10,1292107,91179,8510,76979,39

20,2581196,2327,07,759158,59

30,3873313,92523,924,324237,97

40,5165500,31833,855,712317,36

50,6454833,851389,754,719396,56

Tng t tnh cho cc gi tr L=5, L=6, L=7, L=8, L=9, L=10

Bng cc tr s kt qu khi ct t L = 5:

STTG, Kg/s.m2PcPc/Z, (N/m2)/m

fcRec

10,1292127,53212,552,6012,72779,39

20,2581313,92523,22.9112,405158,59

30,3873353,16588,61,244,874237,97

40,5165647,46107,912,007,418317,36

50,6454971,191618,651,555,499396,56

Bng cc tr s kt qu khi ct t L = 6:STTG, Kg/s.m2PcPc/Z, (N/m2)/m

fcRec

10,1292176,58294,33,617,62279,39

20,2581284,49474,152,6411,25158,59

30,3873500,31833,851,766,92237,97

40,5165824,041373,42,549,42317,36

50,64541402,832338,052,237,91396,56

6.3.3 Tnh ct lt: Tnh ct lt ti (L=7, G*=5);(L=8, G*=5);(L=9, G*=4)

Tnh

Vi

Tnh

T cng thc ta tnh c:

Khi G=4

Khi G=5

Tnh : (SGK)Khi L=7

Khi L=8

Khi L=9

Bng cc tr s kt qu khi ct lt

STTG*, kg/s.m2L/G*

log

log

10,6051,929.10-40,0326,377.10-6-1,495-5,195

20,6052,203.10-40.0327,283.10-6-1,495-5,138

30,4843,099.10-40,2971,024.10-5-0,527-4,99

2.6.4 th:2.6.4.1. th logPck/Z theo log G:

2.6.4.2. th log fck theo Reck:

2.6.4.3. th Pc/Z theo G khi L=4:



2.6.4.6. th fc theo Rec khi L=4:



2.6.4.9. Gin lt ca log theo log

NHN XT

Nhng sai st trong qu trnh lm th nghim:

Thao tc cc van cn lung tng, ch chun xc

c kt qu o chm

Cch khc phc:

Thao tc thc hnh phi nhp nhng, nhanh v chnh xc.

BN LUNCh chy ca ct kh v ct t l ch chy ri.

Ch chy ca ct ngp lt l ch chy ngp lt.

H s ma st ca ct kh nh hn h s ma st ca ct t.

Ct kh: lu lng dng kh vo ct tng th p sut dng kh qua ct cng tng.

Ct t: lu lng dng kh t l thun vi p sut dng kh qua ct.BI 6: LC KHUNG BN(((((I. C S L THUYT

1. Lc cht lng

Lc l qu trnh phn ring cc hn hp nh 1 vt ngn xp, vt ngn xp c kh nng cho 1 pha i qua cn pha kia c gi li nn cn gi l vch ngn lc.

2. Nguyn tc lc

To ra trn huyn ph mt p sut P1, pha lng xuyn qua cc mao dn, pha rn b gi li. Chnh lch gia hai vch ngn gi l ng lc qu trnh lc.

(P = P1 P2

C th to ng lc ca qu trnh lc bng cc cch sau:

Ct p thy tnh

Bng my bm hay my nn

Bng bm chn khng

Cn bng vt tcht trong qu trnh lc:

Vh = V0 + V1 = Va + V

Gh = G0 + G1 = Ga + G

Vh, Gh : Th tch v khi lng hn hp huyn ph em i lc.

V0, G0 : Th tch v khi lng cht rn kh.

V1, G1 : Th tch v khi lng nc lc nguyn cht.

Va, Ga : Th tch v khi lng b m

V, G : Th tch v khi lung nc lc cha nguyn cht.

m ca b :

( % kg m / kg vt liu t).3. Phng trnh tc lca. Tc lc v cc yu t nh hng

Lng nc lc thu c trn mt n v din tch b mt vch ngn lc trn mt n v thi gian gi l tc lc.

Trong :

V Th tch nc lc thu c, m3

F Din tch b mt vch lc, m2

( - thi gian lc, s

Qu trnh lc huyn ph ph thuc vo cc yu t sau: Tnh cht huyn ph: nht, kch thc v hnh dng pha phn tn; ng lc qu trnh lc; tr lc b v vch ngn; din tch b mt vch lc.

b. Theo DAKSI, tc lc c th biu din di dng phng trnh sau:

(5.2)

Trong :

( - nht ca pha lin tc, Ns/m2Rb = 1/(Pb tr lc ca b lc (tn tht p sut qua lp b), 1/m

Rv =1/(Pv tr lc ca vch lc (tn tht p sut qua vch lc), 1/m

c. Lc vi p sut khng i, (P = const

phng trnh lc c dngq2 + 2.C.q = K(

q = V/F lng nc lc ring

;

- t s gia th tch b m thu c v lng nc lc

r0 tr lc ring theo th tch ca b lc (1/m2)

d. Lc vi tc lc khng i, W=const

phng trnh lc c dngq2 + Cq =

II. S NGUYN L THIT B

1. Khung khuy huyn ph

2. Bm huyn ph

3. Thit b lc khung bn

4.p kIII. BNG S LIU TH NGHIMP = 0.2 at

(s)39.3842.8641.87

V (l)101010

P = 0.4 at

(s)32.8136.0132.11

V (l)101010

P = 0.6 at

(s)31.1629.0928.99

V (l)101010

IV. PHC TRNH

1. Tnh nng sut ca qu trnh lc v lng nc lc ring

p sut p1= 0.2 at

- tnh nng sut ca qu trnh lc :

Q1 = = = 2.5 10-4 (m3/s) Q2 = = = 2.3 10-4 (m3/s) Q3 = = = 2.4 10-4 (m3/s) Din tch ca b mt lc :

S = 2 n: s bng lc

a : chiu di cnh

=> S = 2

= 0.625 m2- tnh lng nc lc ring:

q1 = = = 0.016 (m3/m2)q2 = = = 0.032 (m3/m2)q3 = = = 0.048 (m3/m2)

= 0.032 0.016 = 0.016 (m3/m2)

= 0.048 0.032 = 0.016 (m3/m2)

1 = 39.38 (s)

2 = 82.24 (s)

1 = 42.86 (s)

2 = 82.24 (s)

3 = 124.11 (s)

2 = 41.87 (s)

Phng trnh lc vi p sut khng i c dng:

q2 + 2Cq = K

2qdq + 2Cdq = Kd

2q + 2C = K.

= +

= +

= +

2678.75 = + (1)

= +

= +

2616.88 = + (2)

T (1) v (2) ta c h phng trnh:

2678.75 = + (1)

2616.88 = + (2)

Ly (1) (2) 61.87 =

K = -5.17 10-4Thay K = -5.17 10-4 vo (1) ta c C = - 0.708

p sut p2= 0.4 at



S = 2 n: s bng lc

a : chiu di cnh

=> S = 2


q1 = = = 0.016 (m3/m2)q2 = = = 0.032 (m3/m2)q3 = = = 0.048 (m3/m2)

= 0.032 0.016 = 0.016 (m3/m2)

= 0.048 0.032 = 0.016 (m3/m2)

1 = 32.81(s)

2 = 68.82 (s)

1 = 36.01 (s)

2 = 82.24 (s)

3 = 100.93 (s)

2 = 32.11 (s)


q2 + 2Cq = K

2qdq + 2Cdq = Kd

2q + 2C = K.

= +

= +

= +

2250.625 = + (1)

= +

= +

2006.875 = + (2)


2250.625 = + (1)

2006.875 = + (2)

Ly (1) (2) 243.75 =

K = - 1.3 10-4Thay K = - 1.3 10-4 vo (1) ta c C = - 0.16

p sut p3= 0.6 at



S = 2 n: s bng lc

a : chiu di cnh

=> S = 2


q1 = = = 0.016 (m3/m2)q2 = = = 0.032 (m3/m2)q3 = = = 0.048 (m3/m2)

= 0.032 0.016 = 0.016 (m3/m2)

= 0.048 0.032 = 0.016 (m3/m2)

1 = 31.16(s)

2 = 60.25 (s)

1 = 29.09 (s)

2 = 60.25 (s)

3 = 89.24 (s)

2 = 28.99 (s)


q2 + 2Cq = K

2qdq + 2Cdq = Kd

2q + 2C = K.

= +

= +

= +

1818.125= + (1)

= +

= +

1811.875 = + (2)


1818.125 = + (1)

1811.875 = + (2)

Ly (1) (2) 6.25 =

K = - 5.12 10-3Thay K = - 5.12 10-3 vo (1) ta c C = - 4.67

BNG . Gi tr C v K theo

STT

CK

10.2 - 0.708

-5.17 10-4

2

0.4

- 0.16

- 1.3 10-4

30.6 - 4.67- 5.12 10-3

3. V th

th theo q khi p1= 0.2 at

Bng s liu

q0.0160.032

2678.752616.88


Bng s liuq0.0160.032

2250.6252006.875


Bng s liuq0.0160.032

1818.1251811.875

4. Nhn xtu im ca my lc khung bn : Din tch lc ln. Thit k linh hot, theo tng module (din tch lc v vt liu lc c th d dng thay i). D dng chuyn i t phng th nghim sang quy m sn xut. Vn hnh n gin, d dng cho ngi s dng. Kt qu lc ng tin cy nu s dng vi lc hoc giy lc tiu chun. Chi ch bo hnh thp. Sau khi lc vn gi nguyn tnh cht ca sn phm.Trong th ta thy ng ni cc 1 ng thng c xu hng gim do trong qu trnh thc hnh c s sai s khi bm thi gian v th tch ca mc nc cn xc nh sau khi lc l khng hon ton chnh xc nn s liu ch mang tnh tng i. Qua phng trnh lc ta thy rng khi tc lc khng thay i p sut lc bin thin tuyn tnh theo thi gian lcKhi p sut cng tng th lng nc lc trn mt n v din tch v lu lng nc lc cng tng theo.

6

5

4

2

3

1

(t1

t1

tv1111

tv2

(tv

(t2

(tlog

t2











EMBED Excel.Chart.8 \s





6

2

3

4

Thit b un nng dng nhp liu

Thp chng ct

Ni un

Thit b ngng t

Thit b lm ngui sn phm nh

Dng nhp liu

Dng bo ha

Sn phm y

Hi bo ha

Hi bo ha

Lng si

Sn phm nh

Dng sp nh

5

1

3

4

6

7

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(2

EMBED Equation.3

1

2

3

1

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_1434565555.xlsChart1

79.113

90.396

90.552

162.978

157.125

192.223

203.823

19271.7

296.814

KL

Re

KL

Sheet1

REKL

6470.80079.113

6518.40090.396

6518.40090.552

12847.800162.978

13036.800157.125

12847.800192.223

19271.700203.823

19271.700

19133.100296.814

REKL*

1628.40033.520

1643.70033.560

1643.70033.560

3256.80046.240

3287.30046.880

3287.30046.850

4840.30056.080

4885.20056.140

4931.00056.000

REKL*

1628.40033.520

1643.70033.560

1643.70033.560

3256.80046.240

3287.30046.880

3287.30046.850

4840.30056.080

4885.20056.140

4931.00056.000

Sheet1

KL

Re

KL

Sheet2

KL*

Re

KL*

Sheet3

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