truyền chất.tháp Đĩa
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Sinh vin thc hin: Bi Quang Hiu Lp: Lc Ha Du K52 -
Phn II: Qu trnh v thit b truyn khi.Tnh cc thng s c bn ca thit b (thp a) chuyn khi lm vic p sut kh quyn (760 mmHg) chng luyn hn hp hai cu t nc v axit axetic ; m bo cc yu cu v nng sut tnh theo hn hp u v thnh phn nguyn liu, nh y. Cc yu cu c th nh sau:GF=4170kg/h , aF = 27% , aP=97% , aw= 2%1- Xc nh nng phn mol v lu lng [kmol/h] ca nguyn liu, sn phm nh v sn phm y.2- V ng cn bng trn th x y.3- Xc nh ch s hi lu thch hp, ng lm vic v s a l thuyt ca thp.4- Xc nh ng knh, s a thc t v chiu cao c bn ca thp.5- Xc nh nhit nh, y v v tr a tip liu ng vi trng hp nguyn liu vo thp trng thi si.K hiu:Nc : AMA = 18 [g]; ts = 100;
axit axetic :BMB = 60 [g]; ts =118,1 ;
y cu t d bay hi hn A l NCThnh phn cn bng lng hi ca hn hp Nc- Axit axetic:
X05102030405060708090100
Y09,216,730,342,55362,671,679,586,493100
t118,1115,4113,8110,1107,5105,8104,4103,3102,1101,3100,6100
1. Xc nh nng phn mol v lu lng [kmol/h] ca nguyn liu, sn phm nh v sn phm y.- Phng trnh cn bng vt liu cho c thp: (cng thc IX.16 [4])F = P + WHayGF = GP + GW(1)Phng trnh cn bng vt liu cho cu t d bay hi: (cng thc IX.17 [4])FxF = PxP + WxWGFaF = GPaP + GWaW(2)T (1) v (2) suy ra:
T (1) suy ra:GW = GF GP = 4170 1097,37 = 3072,63 [kg/h]- Nng phn mol trong hn hp u: (cng thc VIII.1 [4])
[phn mol]Nng phn mol trong sn phm nh:
[phn mol]Nng phn mol trong sn phm y:
[phn mol]- Khi lng mol trung bnh:p dng cng thc : M = xMA + (1 x)MBtrong :M : khi lng mol trung bnh [kg/kmol]x : Nng phn molMA,MB : Khi lng mol ca 2 cu t A, Bta tnh c:
Trong hn hp u:MF = xFMM + (1 xF)MT = 0,552.18 + (1 0,552).60 = 36,816 [kg/kmol]Trong sn phm nh:MP = xPMM + (1 xP)MT= 0,99.18 + (1 0,99).60 = 18,42 [kg/kmol]Trong sn phm y:MW = xWMM + (1 xW)MT= 0,064.18 + (1 0,064).60 = 57,312 [kg/kmol]
- Lu lng tnh theo kmol/h:
2. V ng cn bng trn th x y.(S liu bng IX.2a 147 [4])X05102030405060708090100
Y09,216,730,342,55362,671,679,586,493100
t118,1115,4113,8110,1107,5105,8104,4103,3102,1101,3100,6100
3. Xc nh ch s hi lu thch hp, ng lm vic v s a l thuyt ca thp.a. Ch s hi lu ti thiu Rmin:xF = 0,552 [phn mol] yF* = 0,672Ch s hi lu ti thiu Rmin c xc nh da vo cng thc: (IX.24 [4])
b. Ch s hi lu thch hp Rth v Nlt:- Ch s hi lu lm vic thng c xc nh qua ch s hi lu ti thiu theo cng thc (IX.25 [4]):Rth = b.Rmintrong b l h s d, thng ly t 1,2 2,5- Ta lp bng s liu sau xc nh Rth:
b1,41,61,82,02,22,4
Rth3,714,244,775,35,836,36
Nlt322626252423
Nlt(Rth + 1)150,72136,24150,02157,5163,92169,28
- Da vo bng s liu trn ta lp c quan h Rth vi Nlt(Rth + 1) theo th sau:
- T th Rth - Nlt(Rth + 1) ta xc nh c Rth = 4,24 vi s a l thuyt Nlt = 26, trong s a on luyn l 18 v on chng l 8.
c. Phng trnh ng lm vic:- on luyn: (IX.20 [4])
- on chng: (IX.22 [4])
yU = 1,172x 0,011
4. ng knh thp D, s a thc t Ntt v chiu cao c bn ca thp H:a. ng knh thp D :ng knh thp c xc nh theo cng thc
, m [II - 181]Trong :gtb: lng hi trung bnh i trong thp, kg/h.(y.y)tb: tc hi trung bnh i trong thp, kg/m2.sV lng hi v lng lng thay i theo chiu cao ca thp v khc nhau trong mi on nn ta phi tnh lng hi trung bnh cho tng on.1. ng knh on luyn:a. Xc nh lng hi trung bnh i trong on luyn:Lng hi trung bnh i trong on luyn tnh gn ng bng trung bnh cng ca lng hi i ra khi a trn cng ca thp v lng hi i vo a di cng ca on luyn.
, kg/h [II - 181]Trong :gtb: lng hi trung bnh i trong on luyn, kg/h.g: lng hi i ra khi a trn cng ca thp, kg/h.gl: lng hi i vo a di cng ca thp, kg/h.* Lng hi ra khi nh thp: g = GR + Gp = Gp(Rx+1)[II 181]g = 1097,37(4,24 + 1)g = 5750,22 kg/h* Lng hi i vo on luyn: Lng hi g1, hm lng hi y1 v lng lng G1 i vi a th nht ca on luyn c xc nh theo h phng trnh.g1 = G1 + Gp (1)g1.y1 = G1.x1 + Gp.xp (2)[II - 182]g1.r1 = g.r(3)Trong :y1: hm lng hi i vo a 1 ca on luyn, phn khi lng.G1: lng lng i vi a th nht ca on luyn.r1: n nhit ho hi ca hn hp hi i vo a.r: n nhit ho hi ca hn hp hi i ra khi nh thp.x1 = xF = 0,552 phn mol tng ng vi 0,27 phn khi lngr1 = ra.y1 + (1-y1).rb [II - 182]Vi ra, rb: n nhit ho hi ca cc cu t nguyn cht l Nc va Axit axetic t01 = tF .
T x1= xF = 0,552 tra th trn ta c t01 = tf = 103,8 0CVi t01 = 103,8 0 C ni suy theo bng I.212 trong [I 254] ta c;
kJ/kg.
kJ/kg. (tra thi hinh I.65-stay 1) r1 = 2246,34.y1 + (1 - y1).410,31 r1 = 1836,03y1 + 410,31 kJ/kg.r = ra.y + (1 y).rb [II - 182]Vi ra, rb: n nhit ho hi ca cc cu t nguyn cht l Nc va Axit axetic t02 = tp. T xp = 0,99 tra th lng hi trn ta c tp = 100,1.y: hm lng hi i ra khi nh thp, phn khi lng.y = yp = 0,993 phn mol ( suy ra t xp= 0,99 phn mol)i ra phn khi lng:
Vi t02 = tP = 100,10C ni suy theo bng I.212 trong [I 254] ta c:
kJ/kg.
kJ/kg. r = 2256,41.0,977 + (1 - 0,977).418,68 r = 2214,14 kJ/kg.Thay cc gi tr tnh c vo h phng trnh trn ta cg1 = G1 + 1097,37g1.y1 = 0,27G1 + 1097,37.0,977g1(1836,03y1 + 410,31) = 5750,22.2214,14=12731792,11Gii h phng trnh ta c: g1 =12479,97kg/hG1 = 11382,6 kg/hy1 = 03322 phn khi lng Thay y1 = 0,3322 vo r1 ta c: r1 = 1836,03.0,3322 + 410,31= 1020,24 kJ/kgVy lng hi trung bnh i trong on luyn l:
kg/h.b. Tnh khi lng ring trung bnh* Khi lng ring trung bnh i vi pha hi c tnh theo
, kg/m3. [II - 183]Trong :MA MB: khi lng phn mol ca cu t Nc va Axit axetic T: nhit lm vic trung bnh ca thp, 0K.ytb1: nng phn mol ca cu t 1 ly theo gi tr trung bnh
[II - 183]
Vi : nng lm vic ti 2 u mi on thp, phn mol.
= yp = 0,993 phn mol
= y1 = 0,3322 phn khi lng i sang phn mol ta c:
phn mol
phn molNhit trung bnh on luyn: .ttbl= = =102=3750KVy khi lng ring trung bnh ca pha hi i vi on luyn l:
kg/m3.* Khi lng ring trung bnh i vi pha lng
, kg/m3 [II - 183]Trong :
: khi lng ring trung bnh ca lng, kg/m3.
: khi lng ring trung bnh ca cu t 1 v 2 ca pha lng ly theo nhit trung bnh, kg/m3.
: phn khi lng trung bnh ca cu t 1 trong pha lng.
phn khi lngVi ttb=1020C, ta c
kg/m3.
kg/m3.Vy khi lng ring trung bnh ca lng trong on luyn l:
kg/m3 Tnh ytb Chn thp a li, lm vic u n (ng knh l 2,5mm, chiu cao ng chy chuyn trn a 10 12 mm, thit din t do ca a 12,8%). Thng ly tc lm vic ytbkhong 80 90% tc gii hn gh: (IX.111 [4])
[m/s]trong ytb, xtb l khi lng ring trung bnh ca pha hi v pha lng ca on luyn.Vy,
Tc lm vic ytb c ly bng 0,9.gh, nn:ytb = 0,9.1,6795 = 1,512 [m/s]T cc thng s gtb, ytb, ytbtnh c, ta c ng knh on luyn bng:
Quy chun ng knh Do= 1,6 [m]
ng knh on chng:a. Lng hi trung bnh i trong thp
[II - 182]Trong :gn: lng hi i ra khi on chng, kg/h.g1: lng hi i vo on chng, kg/h.V lng hi i ra khi on chng bng lng hi i vo on luyn (gn= g1) nn ta c th vit:
[II - 182]Lng hi i vo on chng gl, lng lng G1 v hm lng lng xl c xc nh theo h phng trnh cn bng vt liu v cn bng nhit lng sau:G1 = g1 + Gw G1. x1 = g1.yw + Gw.xw [II - 182] g1.r1 = g1.r1Trong :r1: n nhit ho hi ca hn hp hi i vo a th nht ca on chng.xw: thnh phn cu t d bay hi trong sn phm y.r1: n nhit ho hi ca hn hp hi i vo a trn cng ca on chng.Ta c:Gw = W = 3072,63kg/h.xw = 0,064 phn mol tng ng vi 0,02 phn khi lng y1 = yw xc nh theo ng cn bng ng vi xw = 0,064 phn mol. yw = 0,113 phn mol.i y1 = yw = 0,113 phn mol ra phn khi lng ta c:
phn khi lng r1 = ra. y1 + (1- y1).rb [II 182]Vi ra, rb: n nhit ho hi ca cc cu t nguyn cht t0 = tw. Vi xw = 0,064 tra th ta c tw = 1150C. T t0 = tw =1150C ni suy theo bng I.212 trong [I 254] ta c.
kJ/kg.
kJ/kg.=> r1 = 2215,86.0,0368 + (1 - 0,0368).355,88 r1 = 424,33 kJ/kgThay vo h phng trnh trn ta c:G1 = g1 + 3072,63G1. x1 = g1.0,0368 + 3072,63.0,02g1.424,33 = 12479,97.1020,24Gii h phng trnh trn ta c:g1 = 30006,28 kg/hG1 = 33078,91 kg/hx1 = 0,0352 phn khi lngVy lng hi trung bnh i trong on chng l:
kg/h.b. Tnh khi lng ring trung bnh:* Khi lng ring trung bnh i vi pha hi c tnh theo:
, kg/m3. [II - 183]Trong :MA MB: khi lng phn mol ca cu t Nc va Axit axeticT: nhit lm vic trung bnh ca thp, 0K.ytbc: nng phn mol ca cu t 1 ly theo gi tr trung bnh
[II - 183]
Vi : nng lm vic ti 2 u mi on thp, phn mol.
= y1 = yw = 0,113 phn mol
= y1 = 0,8084 phn mol
phn molNhit trung bnh on chng: .ttbc= = =109,4=382,40K
Vy khi lng ring trung bnh ca pha hi i vi on chng l:
kg/m3.* Khi lng ring trung bnh i vi pha lng
, kg/m3 [II - 183]Trong :
: khi lng ring trung bnh ca lng, kg/m3.
: khi lng ring trung bnh ca cu t 1 v 2 ca pha lng ly theo nhit trung bnh, kg/m3.
: phn khi lng trung bnh ca cu t 1 trong pha lng.
Vi a1: nng phn khi lng ca pha lng a di cng ca on chng.Ta c: a1 = x1 = 0,0352 phn khi lng
phn khi lng
ng vi t0 = 109,40C. Ni suy theo bng I.2 trong [I-9] ta c:
kg/m3.
kg/m3.Vy khi lng ring trung bnh ca lng trong on chng l:
kg/m3Vy,
Tc lm vic ytb c ly bng 0,9.gh, nn:ytb= 0,9.1,348 = 1,2132 [m/s]T cc thng s gtb, ytb, ytbtnh c, ta c ng knh on chng bng:
Quy chun ng knh : DU= 2,2 m
Nh vy ta xc nh c ng knh on chng DU = 2,2 [m] v luyn DO = 1,5 [m]
b. S a thc t Ntt :S a thc t c tnh theo cng thc: (IX.59 [4])
trong :Nlt s bc thay i nng hay s a l thuyttb hiu sut trung bnh ca thit b:
(IX.60 [4]) l bay hi tng i ca hn hp:
(IX.61 [4]) hh nht ca hn hp lng [N.s/m2]:
A nht ca cu t A ph thuc nhit xtB nht ca cu t B ph thuc nhit xt Ti nh thp:xP = 0,99 [phn mol]; yP* = 0,993 [phn mol]; tP = 100,1 [oC];suy ra: = 1,43 A = 0,28374 [10-3 Ns/m2] (ngoi suy bng I.110 [3])B = 0,43 [10-3 Ns/m2] (ngoi suy bng I.101 [3])
Vy, ta c:. = 0,41P= 61%(ngoi suy th hnh IX.11 [4])
Ti v tr tip liu:xF = 0,552 [phn mol]; yF* = 0,672[phn mol]; tF = 103,8 [oC];suy ra: = 1,663A = 0,27412 [10-3 Ns/m2] (ngoi suy bng I.110 [3])B = 0,42 [10-3 Ns/m2] (ngoi suy bng I.101 [3])
Vy, ta c:. = 0,552F = 57%(ngoi suy th hnh IX.11 [4])
Ti y thp:xW = 0,064 [phn mol]; yW* = 0,113 [phn mol]; tW = 115 [oC];suy ra: = 1,863A = 0,245 [10-3 Ns/m2] (ngoi suy bng I.110 [3])B = 0,35 [10-3 Ns/m2] (ngoi suy bng I.101 [3])
Vy, ta c:. = 0,64W = 54%(ngoi suy th hnh IX.11 [4])
T cc gi tr P, F, Wtm c, tbbng:
Vy s a thc t l:
S a on luyn : 18/0,5733 = 32 [mm]S a on chng : 8/0,5733 = 14 [mm]
c. Chiu cao c bn ca thp:
(IX.54 [4])trong Hd khong cch gia cc mm chiu dy ca mm, Chiu cao on luyn: vi s a on luyn: Nttl=32ng knh DO=1,6 m, chn Hd=450mm, = 4mm - chn theo bng IX.4a HO= Ntt.(Hd + )= 32.(0,45+0,004)= 14,528 14,6 m Chiu cao on chng:vi s a on luyn: Nttl=14ng knh DU=2,2 m, chn Hd=550mm, = 4mm - chn theo bng IX.4a HU= Ntt.(Hd + )= 14.(0,55+0,004)= 7,756 7,8 m Chiu cao ton b thp:H= HO + HU + 0,9 = 14,6 + 7,8 +0,9=23,3 24[m]
5.Nhit nh, y v v tr a tip liu ng vi trng hp nguyn liu vo trng thi si:T th t x,y, ta c th xc nh d dng nhit nh, y v v tr a tip liu ca thp:tP = 100,1 [oC], tW = 115 [oC], tF = 103,8 [oC].