thi nghiem qt&tb cnhh_bai giang_hong duc_thanh hoa

7/29/2019 Thi Nghiem QT&TB CNHH_Bai Giang_Hong Duc_Thanh Hoa

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1

TH NGHIM QU TRNH V

THIT B CNG NGH HA HC

Ging vin: Phm Trung Kin


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2

NI DUNG CC BI TH NGHIM Xc nh chun s Reynolds (Reynolds Number)

Chng ct (Distillation)

Xc nh mc cht lng (Tank Draining)

Khuch tn (Stefan Diffusion)

Th nghim thit b truyn nhit (Heat Exchanger)

Tng quan v cc phn xng, qu trnh v thit b

trong nh my lc du (Overview of Refinery)

Tham quan h thit b chng ct ti phng th

nghim Lc-Ha Du v Vin Ha Hc Cng

Nghip Vit Nam


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3

XC NH CHUN S REYNOLDS

Ch dng chy ca cht lng Chy dng (tng) (Re2320): cc phn t cht lng

chuyn ng song song nhau theo ng thng vivn tc chm c gi l chy dng.

Chy xoy (ri) (Re10000): cc phn t chuynng vi vn tc nhanh theo ng thng khng tht vi cc hng khc nhau to thnh mt dng ric gi l chy xoy.

Chy chuyn tip (qu ) (2320


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4

CHUN S REYNOLDS

Cng thc xc nh chun s Reynolds

Re=wl/=wl/Trong :w: vn tc c trng ca dng chy (m/s)l: kch thc hnh hc c trng (m)

- chiu cao h nu l tng phng- ng knh tng ng dtca mt ct m lu th i qua

dt=4rtl rtl=f/U

f: din tch mt ct ca dng (ng) U: chu vi thm t: khi lng ring (kg/m3)

: nht ng lc hc (dynamic viscosity)(kg/m.s hay Pa.s, N.s/m2)v: nht ng hc (kinetic viscosity) (m2/s)

v= /


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5

S TH NGHIM REYNOLDS


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6

C S L THUYT TH NGHIM REYNOLDS

Th nghim Reynolds l mt th nghim c in

c Reynolds tm ra.

xem c cu trc ca dng chy, Reynolds dng mt ng rt nh dn nc mu vo thng

vi ng tm ca ng ln dn nc khng mu.

Cc nhn xt v kt lun m Reynolds rt ra trongqu trnh th nghim.


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7


1. Khi tng dn lu lng t Q=0

gi tr lu lng nh, tia mu chy theo mt ng thng vtheo ng tm ng, khng dao ng, dung dch mu khngc s ha trn vi dung dch nc chy quanh n.

Khi lu lng tng n mt mc no th tia mu bt u b

dao ng (gn sng). Lc ny dng chy tng kt thc.

Nu lu lng tip tc tng th tia mu s dao ng mnh hndn n b t on v sau s b ha trn hon ton vodng chy. Lc ny dng chy tr ln ri hon ton.

Theo Reynolds dng chy chuyn t trng thi chy tng sangtrng thi chy ri phi qua bc trung gian l trng thichy qu .


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2. Khi lu lng gim dn

Khi dng chy trng thi ri hon ton, nu tagim dn lu lng th ti mc no tia mu trli mc gn sng.

Nu tip tc gim lu lng th dng chy li tr vtrng thi chy tng, tia mu li chy theo mtng thng dc theo tm ng.

Nh vy, dng chy chuyn trng thi chy ttrng thi chy ri v trng thi chy tng qua trngthi trung gian l trng thi chy qu .


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XC NH H S REYNOLDS T TH NGHIM

Tnh lu lng: Q = W/t

Tnh vn tc dng chy: w = Q/A

Tnh ch s Reynolds: Re = w.D/v

Trong :

W l th tch cht lng o c trong 1 n v thigian

t l thi gian cht lng chy c th tch W

A l din tch ng ng

D l ng knh ng w l vn tc trung bnh trong ng

v l nht ng hc ca cht lu

Q l lu lng


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10

XY DNG H TH NGHIM REYNOLDS

YU CU:

B sung c s l thuyt ca qu trnh

Cc trang thit b cn dng cho th nghim

Lp t cc thit b cho th nghim

Cht mu (c th dng KMnO4) Nguyn tc o cc thng s

Tin hnh th nghim (lp li khong 2-3 ln)

Ghi kt qu th nghim

X l cc s liu th nghim Dng cc ng c D khc nhau hoc ng gp khc

nghin cu cho cc trng hp c bit


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11

CHNG CT (DISTILLATION)

Mc ch ca th nghim:

L thuyt v chng ct

Nguyn l, cu to ca thp chng ct

Nguyn tc hot ng ca thp chng ct

Xc nh hiu sut ca thp chng ct

Xc nh s a l thuyt ca thp v ch shi lu ti thiu

nh gi phng php McCabe-Thiele


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12

C S L THUYT QU TRNH CHNG CT

Thit b chng ct

n gin nhtThit b chng ct c ct

chng ct


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Thit b chng ct ASTM D86


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14


Kt qu th nghim (Bng 1 ni suy ra Bng 2)


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NG CONG CHNG CT


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THP CHNG CT


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17

THP CHNG CT

a trong thp chng ct


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18

S H THNG THP CHNG CT


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19

MT S M HNH THP CHNG CT

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20

PHNG PHP McCabe-Thiele

Dng cho qu trnh chng ct h hai cht lng tan v hn

(Ru+Nc) ng bay hi cn bng (a,b,c)

S nguyn l mt thp chng ct

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Gi s cn chng ct h 2 cht (1) v (2) c

p sut hi bo ha ln lt l P1 v P2Nng phn mol ca cht th nht trong

lng v hi ln lt l x v y

Theo Raoult v Dalton ta c:y=P1x v 1-y=P2(1-x)

Hay: y=x/[1+( -1x)]vi =P1/P2

cng ln th y cng khc x.ng (a) vi =1

ng (b), (c) vi tng dn

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Theo s thp chng ct:

D l sn phm nh

R l sn phm y

V l s mol hi bay ln

L l s mol lng chy xung

Ti mi a ca vng ct:

V(n) =L(n+1) + D

i vi cht th nht:V(n) y(n) =L(n+1) x(n+1) + DxD

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Theo gi thuyt Lewis, nhit bay hi mol

khng ph thuc phn t lng (s mol lngchy xung t cc a c th coi l nhnhau, s mol hi bay ln t cc a cngnh nhau). Khi ta c:

V(n) y(n) =L(n) x(n+1) + DxD

Hay:

y(n) =(h/(h+1))x(n+1)+(1/(h+1))xD (*)

Trong : h=L/D

Phng trnh (*) l tuyn tnh, h cng ln th th cng dc, h= th y(n)=x(n+1) (ng cho)

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24

PHNG PHP McCabe-Thiele th biu din s

ph thuc y(n) v x(n+1)l cc ng lm vic

- Tt c cc ng lm

vic ca vng ct u i

qua im D ng vi

xD(DR, DP, DE, DH,)

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Ti vng chng:

V(m)=L(m+1)-R

Vi R l s mol cn ly ra khi y thp

V(m) l s mol hi bay ln t a m

L(m+1) l s mol lng chy xung t a (m+1)

i vi cht th nht:

V(my(m) =L(m+1)x(m+1) RxR

Dng gi thuyt Lewis ta c:y(m)=(L

/V)x(m+1)-(R/V)xR (**)

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th biu din gia y(m) v x(m+1)l cc ng

lm vic vng chngChng u i qua im R c ta xR (RP)

Ti vng ct: L=hD

V= L+D=(h+1)D

Ti vng chng, dng lng L:

L=L+La=hD+La

Cn dng hi V: V=V-Va=(h+1)D-VaV R=A-D nn hi lu s:

s= V/R=[(h+1)D-Va]/[A-D]

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Khi phng trnh (**) c dng:

ym=[(s+1)/s)]x(m+1)-(1/s)xR

Hay: x(m+1)=[s/(s+1)]ym +[1/(s+1)]xR

i vi a np liu:

- vng ct:

V(n,)y=L(n+1)x+DxD

- vng chng:

V(m,)y=L

(m+1)x-RxR

Trong a (n) ca vng ct cng l a (m) ca vngchng v a (n +1) ca vng ct cng l a (m +1)ca vng chng

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Tr hai v ca phng trnh:

A l s mol nguyn liu c np

xAl phn mol ca cht th nht trong nguyn liu c np

Val s mol nguyn liu bay hi

Lal s mol nguyn liu trng thi lng

(A=Va+La)

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Phng trnh ng np liu (qua M)

Khi x=xA th y=x=xA, ta c im M

Gc nghing ca ng np liu ph thuc t sVa/A, tc ph thuc nhit np liu Ta, c th phthuc Ta v nhit si Ts, nhit ngng t Thcanguyn liu. Ta c cc ng a, b,c d, e.

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V tr ng np liu:

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ng (a): Ta=Ts, nguyn liu bt u si,B=0, (B-1)/B=-

ng (b): Ts


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S liu =4, D=1/3A, R=2/3A

B=Va/A=1/2, nn ng np liu: y=-x+2xA=-x+0,7 v xA=0,35

hi lu ng vi ng PD l h=2,17

Phng trnh ng lm vic vng ct PD: y=0,685x+0,3

V h=2,17 nn hi lu hi s=0,835

ng lm vic vng chng RP c phng trnh:x=0,455y+0,027

Hoc: y=2,198x-0,06

X 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9

y 0,31 0,50 0,63 0,73 0,80 0,86 0,90 0,94 0,97

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34


Theo hnh v:

tm s a l thuyt ta v ln lt ccng thng ng v nm ngang nm giang bay hi cn bng v ng lm vic.

S a vng ct ln hn 4 S a vng chng gn 3 S a ca c thp l 4+3=7

Trng hp hi lu hon ton, ng lm

vic l RD, s a l thuyt l ln hn 4ng bay hi cn bng cng cong ( cng

ln) th s a l thuyt tng hay gim v hcc cht cng d hay kh tch? V sao?

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S a l thuyt ca thp ph thuc:

Bn cht h hi lu

Nhit vng np liu

Nng distillat

Nng cn (sn phm y)

Khi nim a l thuyt l mt ci g rt l thuyt,mt a l thuyt c th khng phi l mt a thcm gm n a thc

Gi tr n ph thuc: cu trc hnh hc ca thp, tc, cch thc di chuyn ca pha hi, pha lng, nhit, p sut,

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Quan h gia hi lu v s a l thuyt

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Cc bc xc nh s a l thuyt

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41


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42


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M HNH TH NGHIM CHNG CT (UOP)

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MT S NI DUNG KHC

H chng ct trong thc t (UOP-UC DAVIS)

M hnh qu trnh chng ct (Michigan)

M hnh thp chng ct trong HYSYS

Thp chng ct du th trong nh my lc

du Dung QutTng quan v cc qu trnh v thit b trong

nh my lc du Dung Qut

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H CHNG CT UOP

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CC M HNH THP TRONG THC T

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CC M HNH THP CHNG CT

Thp chng ct kh quyn (Atmospheric)

Thp chng ct chn khng (Vacuum)

Thp chng ct phn ng (Reactive)

Thp chng ct ba pha (3 phases)

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THP CHNG CT KH QUYN

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THP CHNG CT CHN KHNG

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TH NGHIM V CHNG CT

YU CU:

Xy dng c s l thuyt v qu trnh chng ct (cnbng lng hi,)

Tm hiu cu to ca thit b chng ct, thp chngct du th,

Nguyn l hot ng ca thp chng ct Phng php xc nh s a ca thp chng ct

V s mt h thit b v chng ct (tham kho mhnh thp chng ct) c cc thit b ph tr v cch

vn hnh Xc nh s a ca thp chng ct theo phng

php MacCabe-Thiele

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XC NH MC CHT LNG TRONG BNH

Mc ch ca th nghim (Tank Draining) Xc nh h s thot ca cht lng trong bnh qua

mt l thng.

Kho st s nh hng ca kch thc l khc nhaun ng lc ca qu trnh chy.

D liu thc nghim cho php sinh vin phn tch sais (phng sai), ni v ngoi suy s liu.

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C S L THUYT CA QU TRNH

Khi nc chy qua bnh cha (Minh ha

hnh 1), lu lng th tch c th biu dinnh sau:

Trong : CD: c xc nh bng thc nghim

(H s thot ca dng chy)

Ao: Din tch l h: Chiu cao mc cht lng

g: gia tc trng trng

0 2 (1)Dq C A gh

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C S L THUYT CA QU TRNH

Phng trnh (1) i khi cng c xem nh nguyn l chyTorricelli.

Dn xut ca phng trnh trn c th vit nh sau:

Cc: H s tht ca dng chy=S2/S0 S2: Din tch mt ct dng nh nht S0: Din tch l (A0)

Trong thc nghim, s o su ca nc (h) nh l hm ca thigian (t) v xc nh h s thot cht lng (CD) Xc nh h s CC hay CD ph hp nht vi cc s liu cho trong

cc ti liu

0 2Cq C A gh

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XC NH MI QUAN H GIA q V h

Cc vn cn quan tm:

Thi gian chy ht cht lng (nc) trongbnh?

Chiu cao cht lng thay i theo thi gian

nh th no? Mi quan h gia q v h?

Chng ta s lm r cc vn

ny bng phng phpphn tch sau y:

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Gii thch cc k hiu:

q l lu lng th tch chy ra t bnh [m3/s]

A l din tch mt ct ca bnh [m2]

Aol din tch mt ct ca l [m2]

h l chiu cao mc cht lng thi im t [m] l khi lng ring ca cht lng [kg/m3]

t l thi gian [s]

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Theo nh lut bo ton khi lng: lng

cht lng ra khi bnh phi bng lng chtlng st gim trong bnh.Lng cht lng trong bnh: AhTc thay i khi lng trong bnh:

d[Ah]/dt=- qHay: Ad[h]/dt=- qHay: dh/dt=-q/A

Nu q=C (hng s) th dh/dt=-C/A Tch phn 2 v ca phng trnh vi phn, ta

c nh sau:

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Ta c:

Hay

2 2

1 1

[t2-t1]

t t

t t

dh C C dt dt

dt A A

( 2) ( 1) [t2-t1]

C

h t h t A

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Cho t1=0 (h=h0)v t2=t; Ta c phng trnh

2.5:

Ta c th xc nh h0 v C/A (h s gc)

bng cc s liu thc nghimM hnh q=hng s s khng ph hp khi h

dn ti o v khi q s dn ti o

( ) 0 0[1- ]0

Ct Ct h t h h

A Ah

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Gi s q=bh; Khi :

Tch phn ta c:

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Bin i phng trnh ta c:

Tch phn ta c:

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t t1=0 v t2=t; ta c phng trnh 2.9:

Hay: phng trnh 2.10

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65

C Q G


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Trng hp tng qut: q=khn

n=0 v 1 ( xt)

n>=1 (s khng xc nh c thi gian cnbnh)

Do : 0


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Phng trnh rt gn:

Tch phn ta c:

Hay ta c phng trnh 2.11:

67

XC NH MI QUAN H GIA V h


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Gii h theo t; ta c:

R rng l n


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Theo cch xc nh ny ta c:

-k/2A=-0.0287 in1/2/s

V: q=5.195h1/2

Nu ta xc nh theo 4 im u tin th:

-k/2A=-0.0264 in1/2/s [sai s kh ln]Trn c s xc nh c q=f(h) ta s xc nh

c cc h s CChoc CD

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BI TP: Xc nh phng trnh: q=f(h) theo

cc m t sau y:

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Quy trnh thc hin th nghim:

nc vo bnh ti v tr vch sn Chy ng h bm giy v m nt o mc cht lng trong bnh nh l hm ca thi

gian vi cc kch thc l khc nhau

Lp li s th nghim cn thit Xem xt cc yu t nh hng n qu trnh V th quan h gia h(in) v t (s) Xc nh cc sai s

Xc nh CDt cc s liu thu c vi cc kchthc l khc nhau So snh cc s liu CDtnh ton c v cc s liu

CD trong cc s tay

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Kt qu th nghim (dtank = 10,75 in; dorifice=0,609 in; htank= 12 in ):

Xc nh mi quan h gia x v y (bc 1 v bc 2) theo ccphng php ca Quy hoch thc nghim v xc nh sai s?

Xc nh mi quan h gia q v h (theo cc dng cho)

Thigian (s)

(x)

0 5.93 11.3 17.2 23.2 29.67 36.17

Chiucao

(inches)

(y)

12 11 10 9 8 7 6

Thi gian (s)

(x)

43.37 51.03 60 70.73 84.73

Chiu cao(inches)

(y)

5 4 3 2 1

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Kt qu th nghim (dtank = 1 in; dorifice= 0,043 in; htank= 15 in ):

Xc nh mi quan h gia x v y (bc 1 v bc 2) theo ccphng php ca Quy hoch thc nghim v xc nh sais?

Xc nh mi quan h gia q v h (theo cc dng cho)

Thigian (s)

(x)

0 6 12.2 18.7 25.5 32.7 40.3 48.3 56.7

Chiucao

(inches)

(y)

15 14 13 12 11 10 9 8 7

Thi gian (s)

(x)

66.1 76.2 87.6 101 117.5 140.7

Chiu cao(inches)

(y)

6 5 4 3 2 1

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PHNG PHP QUY HOCH THC NGHIM


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PHNG PHP QUY HOCH THC NGHIM

Phng php bnh phng cc tiu

Ni dung: cn biu din mi quan h gia x1,x2,,xk v y

Bi ton t ra l tm mt hm s biu din

gn ng nht mi quan h ny bng mthm s no

Ngha l, tm mt hm s biu din mi quanh gia x1, x2,,xkv y sao cho tng bnh

phng cc sai s l nh nht.y=f(x1,x2,,xk) v S(b0,b1) t min

Thng thng ta hay chn hm a thc

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PHNG PHP BNH PHNG CC TIU


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i vi cc hm a thc (bc nht) ni

chung th theo phng php ny cc h s bjc xc nh theo cng thc sau:

Gi s

Trong : X l ma trn th nghim

Y l ma trn cc kt qu th nghimB l ma trn cc h s bj

1 1

( ) 0 ( ) ( )T T T

X X B X X X Y


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Cc ma trn X, B, Y

p dng vi hm mt biny = b0 + b1x (Bc 1) v y = b0 + b1x + b2x2(Bc 2)

11 12 1

21 22 2

1 2

1 ...( )

(1) ...( )

..............................

..............................

..............................

(1) ...( )

k

k

N N Nk

x x x

x x x

X

x x x

1

2

.

.

.

y

y

Y

yN

0

1

.

.

.

b

b

B

bk


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Cc h s bjc xc nh theo cng thc

sau (Bc 1):

2

1 1 1 1 10

2 2

1 1

1 1 11

2 2

1 1

( ) ( )

( )

( )

N N N N

iT T i i i i

N N

i i

i i

N N N

i i i

N N

i i

i i

yi x xi xiyi

B X X X Y b

N x x

N xiyi xi yi

bN x x

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Hm bc nht: y = b0 + b1x (Theo cch khc)

Cho N kt qu u ra y1, y2,,yn tng ng vin gi tr u vo x1, x2,,xN, cn phi xc nhcc h s b0, b1 sao cho:

t Min

Ta c h phng trnh sau:

20 1 0 1

1

( , ) ( )

N

i i

i

S b b y b b x

0 10 1

10

0 10 1

11

( , ) 2 ( ) 0;

( , )2 ( ) 0

N

i i

i

N

i i i

i

S b b y b b xb

S b by b b x x

b

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Hay ta c:

0 1

1 1

2

0 11 1 1

0 1

2

0 1

0

0

:

;

( ) .

N N

i i

i i

N N N

i i i ii i i

Nb b x y

b x b x x y

Hay

nb nb x n y

nb x nb x nx y

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Gii h phng trnh ta c (Bc 1):

Trong :

2

0 2 2

. . .

( )

y x x x yb

x x

1 2 2

. .

( )

x y x yb

x x

1 1

2 2

1 1

1 1;

1 1. ;

N N

i i

i i

N N

i i i

i i

x x y y

N N

x y x y x xN N

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Cc h s tng quan (Bc 1):

2 2

2 1

1

( )1

;1

N

i Ni

x i

i

x N x

S x xN N

2 2

2 1

1

( )1

;

1

N

i Ni

y i

i

y N y

S y y

N N

1

xxy

y

Sr b

S

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Tng d bnh phng c tnh nh sau:

Nu S(b0,b1) cng gn 0, rxycng gn 1, nghi quy cng gn N im thc nghim.

V d: Cho bng s liu thc nghim sau:

2 2

0 1( , ) ( 1) (1 )y xyS b b N S r

x 1 2 3 4 5 6 7 8

y 2.35 2.41 2.60 2.73 2.90 3.11 3.25 3.45

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Kt qu:

b1= 0,1381; b0 =2,2285; Sx = 2,4494; Sy = 0,3524;rxy= 0,9598; S(b0, b1) = 0,06848

V d: Cho bng s liu sau:

Kt qu:

b0 = 4,5759; b1 = 3,4913; Sx = 1,8708;

Sx = 6,5322; rxy= 0,9998; S(b0, b1) = 0,04412

X 2 3 4 5 6 7

y 11.52 15.12 18.47 22.05 25.61 28.05

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Trong trng hp cc s liu th nghim c

lp li niln, ta c:

1

1

1 1

2 2 2

1

2 2 2

1

;

;

( / ( ) )

( / ( ) )

( )( )

N

i i Ni

i

i

N N

i i i i i

i i

N

x i i

i

N

y i i

i

xy

x y

x n

x n nn

x y n y n

xy yn n

S x n n x

S y n n y

xy x yr

S S

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Cho bng s liu thc nghim sau:

p dng cc cng thc trn ta thu c cc ktqu sau:

y = 0,1656x + 0,79

Sx = 138,755; Sy = 1,5772

rxy= 0,9715

x 10 14 18 18 20 20 24 24 30 30 32 36 40 44

y 2.5 2.6 3.2 3.5 4 4.4 5 5.4 6 6.2 6.3 6.8 7 7.5

ni 4 3 4 3 4 3 5 4 2 4 3 4 4 2

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i vi hm bc 2: y=b0+b1x+b2x2

Nu phng trnh hi quy c dng a thc bccao, th khi dng phng php bnh phng bnht s tm c cc h s a thc bng hphng trnh tuyn tnh.

Theo phng php BPCT:

2

0 1 2

( ) ( ) ( )

1; ;

f x f x f x

x xb b b

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Cc cng thc xc nh b0, b1, b2c xc nh

theo h phng trnh sau:

Thc hnh ti lp tnh ton cc h s bj

2

0 1 2

1 1 1

2 3

0 1 2

1 1 1 1

2 3 4 2

0 1 2

1 1 1 1

N N N

i i i

i i i

N N N N

i i i i i

i i i i

N N N N

i i i i i

i i i i

b N b x b x y

b x b x b x x y

b x b x b x x y

88

TUYN TNH HA HM S PHI TUYN


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89



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90



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YU CU:

C s l thuyt ca qu trnh Xy dng h th nghim qu trnh Nguyn tc vn hnh v o cc thng s X l cc s liu thc nghim (cho trc)

theo phng php quy hoch thc nghim(Bc 1 v Bc 2) Xc nh cc sai s

Phng php xc nh cc h s CD Tnh ton cc h s thot CDv so snh vi

cc s liu trong s tay.

91

KHUCH TN STEFAN (DIFFUSION)


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Mc ch ca thc nghim:

o h s khuch tn hi ca cc hp phnring bit (Methanol, Axeton, Hexan,) trongkhng kh ca h th nghim khuch tn theob mt phn cch lng kh.

Nghin cu h thng o h s khuch tnca Trng H UC at Davis

Phn tch v so snh cc kt qu thu c t

qu trnh th nghim Nghin cu cc m hnh tnh ton cc h s

khuch tn

92

KHUCH TN


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KHUCH TN

C s v khuch tn: Khi hai pha chuyn ng tip xc nhau, do s cn tr

ca pha ny i vi pha kia, ngha l do s ma stgia chng m trn b mt phn chia pha to thnhhai lp mng.

Qu trnh di chuyn vt cht trong mng c bn lnh s tip xc gia cc phn t v s tc dngtng h gia chng.

Qu trnh di chuyn vt cht qua mng l qu trnhkhuch tn phn t.

Qu trnh di chuyn vt cht nhn, nh s xo trncc phn t vt cht trong dng, gi l khuch tn ilu.

Vn tc khuch tn trong mng rt chm so vikhuch tn trong nhn.

93

KHUCH TN PHN T


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KHUCH TN PHN T

Xy ra trong lp mng hay trong mi trng ng

yn.ng lc khuch tn l gradien nng theo hng

di chuyn, tc l s bin i nng trn mt nv ng i.

nh lut Fick: Vn tc khuch tn t l vi gradiennng .

dG/Fd =-Ddc/dx

F l b mt vung gc vi hng khuch tn [m2]

D l h s khuch tn [m2/h] l thi gian [h]

Du (-) th hin nng gim theo chiu khuch tn

94

KHUCH TN PHN T


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KHUCH TN PHN T

H s khuch tn: l lng vt cht i qua

mt n v b mt, trong mt n v thigian khi nng vt cht gim mt n vtrn mt n v chiu di theo hngkhuch tn.

Khuch tn ca kh trong kh: V d kh Akhuch tn vo trong kh B (hay ngc li).H s khuch tn (D) c xc nh theo

cng thc sau:

95

KHUCH TN PHN T


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U C

Trong : M

Av M

Bl khi lng phn t ca kh A v kh B

[kg/kmol] T l nhit tuyt i ca kh [K] P l p sut chung ca kh [at] VA v VBl th tch mol ca kh A v kh B

[cm3/mol ] Th tch mol ca cc cht cho trong cc s tay

chuyn mn

Trng hp thiu s liu v th tch mol, c th tnhton theo cng thc sau:

V= nvi n l s nguyn t cng loi Vil th tch nguyn t (Tra bng)

96

KHUCH TN PHN T


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nh hng ca nhit v p sut ln h s

khuch tn:

Ch s 0 l nhit v p sut bit

Khuch tn kh trong lng (c thm)

97

KHUCH TN I LU (C THM)


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( )

Trng hp vt cht khuch tn trong mi trngchuyn ng, v d khuch tn t dng kh vo dngcht lng git.

Dng kh c vn tc w v nng ca cu t phn

b l C. Dng lng i vo vi vn tc u Vn tc khuch tn t kh vo lng khng nhng

nh vo chuyn ng ca phn t m cn nh vochuyn ng ca cc pha.

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( )

C s l thuyt ca qu trnh

Gi thit qu trnh khuch tn trng thitnh, vi ReDT


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( )

Trong :

CGnng mol trong pha kh, mol/cm3 CLnng mol trong pha lng, mol/cm3 d ng knh trong ca ng khuch tn, cm D h s khuch tn (cm2/s )

l chiu di phn khuch tn ti thi im t; l0chiudi phn khuch tn ng vi t = 0 ReDT chun s Reynolds= t l thi gian; t0l thi gian u l vn tc kh trung bnh, cm/s

xenng phn mol ca cu t khuch tn ti b mt = CL/CG khi lng ring, g/cm3 nht ng lc hc, g/cm.s

du

u

100

KHUCH TN STEPHAN


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101

S DI CHUYN CA CC HT KHUCH TN


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102



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( )

Tin trnh lm thc nghim

Cho cht lng d bay hi vo ng n nh nhit trong bnh (thermostat)

o lu lng dng khng kh m bo

ReDT


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( )

Phn tch d liu

Tnh ton h s khuch tn ca 3 cht lngkhc nhau theo phng trnh cho

V biu h s khuch tn theo nhit

So snh gi tr khuch tn thc nghim vicc s liu trong cc s tay

So snh cc gi tr h s khuch tn thu cvi mt s m hnh d on

nh gi phng php Stefan xc nh cch s khuch tn ca cc cht khc nhau

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H thng o h s khuch tn

Air inlet

Air outlet

Dessicant

Thermostat

Water bathDiffusion tubes

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( )

ng khuch tn

z

r

NA

Species A

0 Stagnant Air

Flowing Air (Re


106/134

( )

H thng khuch tn

316 Stainless Steel

Diffusion Manifold & Tube

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YU CU:

C s l thuyt ca qu trnh Xy dng h th nghim qu trnh (cc trang

thit b cn c, thit b ph tr,)

Nguyn tc vn hnh v o cc thng s Xc nh h s khuch tn

M hnh d on h s khuch tn ca cccht khc nhau

108

TH NGHIM THIT B TRUYN NHIT


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C s l thuyt qu trnh truyn nhit

Cc phng thc truyn nhit Dn nhit (Conduction)

Nhit i lu (Convection)

Natural Convection (i lu t nhin) Forced Convection (i lu cng bc)

Bc x nhit (Radiation)

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Cu to thit b trao i nhit:

Loi gin tip: nhit truyn t cht ti nhit ny sangcht ti nhit khc qua b mt phn cch (b mttruyn nhit)

Loi m: qu trnh trao i nhit thc hin trn cng

mt b mt ca vt rn v tin hnh theo cc giaion ni tip nhau u tin, cho cht ti nhit nng tip xc vi b mt rn

(m), vt rn s c un nng n mt nhit cn thit

Khi ngng cung cp cht ti nhit nng, cho cht ti nhit

lnh vo, vt rn s truyn nhit cho cht ti nhit lnh Loi trc tip: Hai cht ti nhit tip xc trc tip vi

nhau

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Cc tc nhn truyn nhit ch yu:

Khi l (1000C), dng in (1500-2000C), hi nc,hi qu nhit (180-350C), du khong (250C)

Cc cht hu c c nhit cao v hi ca n(diphenyl, etediphenyl,) [>180C-250], c un

nng bng khi l, hoc dng in

Cc mui v c nng chy (NaNO3hoc KNO3)hochn hp ca n v mt s kim loi hp kim trng

thi lng [Hg, Pb, Antimon] (140-510C)

Nhit ca cc kh thi hoc cht lng thi c nhit cao

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Thit b trao i nhit gin tip

Loi c v bc Loi ng

Loi tm

Loi xon c Loi ng gn

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Loi c v bc:

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Loi c v bc

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Loi ng

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Loi ng

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Loi ng

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Thit b trao i nhit ng chm

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Cch b tr ng trn li

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Cch chia ngn

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B gin n

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B gin n

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Loi tm

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Loi xon c

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Loi c gn

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Mt s m hnh thit b trao i nhit


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127

CC M HNH THIT B TRUYN NHIT


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Lm lnh bng khng kh (Air cooler)

un nng v lm lnh (Heater/Cooler)Trao i nhit (Heat Exchanger)

L t (Furnace-Fired Heater)

Trao i nhit nhiu dng LNG (LiquefiedNatural Gas)

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Thit lp h th nghim qu trnh truyn nhit

M hnh cc thit tr trao i nhit trong phnmm m phng HYSYS

Tnh ton cc h s truyn nhit (xem li ccbi tp)

Thc hnh M phng

Mt s bi tp v thit b trao i nhit ngchm (xem li)

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Thit lp h th nghim truyn nhit

130



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YU CU:

C s l thuyt qu trnh truyn (trao i)nhit

Nguyn l v cu to cc thit b trao i nhittrong thc t (bao gm c cc thit b lmlnh bng khng kh, l t,)

Thit lp mt m hnh qu trnh trao i nhittrong thc t

131

TI LIU THAM KHO (REFERENCES)


131/134

Chng trnh th nghim qu trnh v thit b trong

cng ngh ha hc, UC Davis, USA, 2012Gio trnh Cng ngh lc du, Phan T Bng, H

M-a cht, NXBXD, 2002Qu trnh v thit b trong cng ngh ha hc, Tp

1&4, Nguyn Bin, H bch khoa H ni, NXB KH&KT,2004

S tay qu trnh v thit b trong cng ngh ha hc,Tp 1&2 , NXB KH&KT, 2006

Qu trnh v thit b trong cng ngh ha hc, Tp 3,

Phm Xun Ton, H bch khoa H ni, NXBKH&KT, 2011 Cc ti liu th nghim cc qu trnh cng ngh ha

hc, UC Davis, USA, 2012

132

YU CU I VI BO CO TH NGHIM


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Vit tay khong 25-30 trang

V hnh hoc ct dn hnh (nu phc tp)Np Bo co ngy 18.02.2013 (Gi ra H Ni)

/C:B mn Lc-Ha Du, Khoa Du Kh,Trng i hc M-a cht, ng Ngc-T

Lim-H NiChm im Bo co ly im thiV s chi tit v m t k lng trnh t

v nguyn tc thc hin cc th nghimKhuyn khch xy dng mt s h th

nghim n gin theo c s l thuyt c hc.

133

NI DUNG BO CO TH NGHIM


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i vi tng bi th nghim:

C s l thuyt Xy dng h th nghim

Nguyn tc o v tnh ton cc thng s

X l cc s liu thc nghim Kt lun

THC HIN THEO YU CU C TH CHOCA TNG BI TH NGHIM

134

TH NGHIM QT&TB TRONG CNHH


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THE END

thi nghiem qt&tb cnhh_bai giang_hong duc_thanh hoa

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