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HP TH

1.Khi nim chung1.1. nh ngha. Ht kh bng cht lng.

Pha kh sang pha lng1.2. ng dng. Thu hi, phn ring, lmsch

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1.3. Dung mi. Ha tan chn lc, nht nh,

nhit dung ring b, nhit si khc xa so vicht tan, khng c khng hi, r tin dkim..

2.Phng trnh c bn ca qu trnh hp th.

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2.1.Phng trnh ng nng cn bng.

ha tan ca kh trong cht lng l lngkh ha tan trong mt n v cht lng, kg/kg,kg/m3, g/lty thuc tnh cht ca kh v dungmi, nhit v p sut ring phn ca khtrong hn hp.

Theo nh lut Henry

ycb = mx (1)

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Vi kh l tng pt c dng ng thng.

Ph hp vi kh thc c nng thp v hatan nh.Vi kh thc m ph thuc nng x, nn pt c

dng ng cong.Khi tnh ton hp thu, thng dng nng phnmol tng i

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v

thay gi tr ca x v y vo phng trnh (1) ta c

Trong ta Y X ng nng cn bng slun lun l ng cong

Y

Yy

1 X

Xx

1

XmmXY

)1(1 (2)

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2.2 Phng trnh ng nng lm vic

Gy Lng hn hp vo, kmol/hYdNng u ca hn hp kh, kmol/kmol khi trYcNng cui ca hn hp khL

xLng dung mi vo,

XdNng u ca dung mi kmol/kmol dmXcNng cui ca dung mi.Gtrlng kh tr vo thit b kmol/h

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Phng trnh cn bng vt liu

Gtr(YdYc) = Lx(XcXd) (3)

Phng trnh cn bng vt liu i vi khongth tch thit b k t mt tit din bt k cathp ta c

Gtr(YYc) = Lx(XXd)

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Rt ra

l phng trnh ng nng lm vic cdng phng trnh ng thng

Y = AX + B

d

tr

xc

tr

x XG

LYX

G

LY

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Hnh 1. ng nng cn bng v nng lm vic

XXd

Yc

Yd

XXcb

min

D

CB1 B2 B3

Xc

XXd

Yc

Yd

XXcb

min

D

CB1 B2 B

Xc

A

O

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Xd , Yd , Yc l hng s cho trc.Xcbin thin v t max bng Xcb khi B t n

C (hinh 1).T pt (3) ta c lng dung mi cn thit

dc

cd

trxXX

YY

GL

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Khi Xc = Xcb th Lx t gi tr min, ngha llng dung mi thc t lun ln hn lng dungmi ti thiu.

Lng dung mi tiu hao ring l

dc

cd

tr

x

XX

YY

G

L

l

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2.3. Cc yu t nh hng ln qa trnh hpth

2.3.1.Lng dung mi

Lng kh b hp th tnh theo cng thc

G = Ky.F.Ytb

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G, Kykhng i, vy F v Ytbphthuc ln nhau.

F tng (ngha l kch thc thit b tng )th ng lc chuyn khi trung bnh gimv ngc li.

Ti B Ytbln nht, ngha l thit b ckch thc nh nht, lng dung mi lnnht. Xc nh nht ngha l dung dch thuc v cng long.

Ti C Xc = Xcb va Ytb= 0 lng dungmi nh nht v thit b v cng ln, thphp th rt cao.

V vy phi chn iu kin ti u.

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2.3.2. Nhit Theo Henry Ycb= mx , m m tng theo nhit ,khi Ycbcng tng. ng cong cn bng s

tng theo nhit v chuyn dch gn v trctung. Ngha l Ytbng lc chuyn khi gim.Nhng,nhit tng th nht dung mi gim

li c li cho chuyn khi.

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2.3.3. p sut

p sut tng h s Henry m gim, ng congcn bng dch chuyn v pha trc honh, Ytbtng c li cho chuyn khi.Nhng p sut tng , nhit tng, bt li chochuyn khi. Thit b phi bn chu p lc.Hp th di p sut ch dng cho kh kh tannh CO2.

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3.Qa trnh nh hp th.-Mc ch.

-Cng tun theo nh lut chung ca hp th.-i hi nhit cao, p sut thp v nng vo y1ca cu t phn b trong pha hi phi nh. Nu dnghi nc th y1 = 0.-Trong thp nh (chng ct) hai dng vt liu chuynng ngc chiu

+hi nc t di ln,+dung mi bo ha t trn xung.

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4.H thng hp th.

-Mt hoc nhiu thp hp th mc ni tip thun hocngc chiu,- Thp chng ct- Thit b un nng, lm ngui, ngng t, bm, thngchaHnh 3. H thng hp th c tun hon

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5. Cu to thit b hp th

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THIT B HP TH LOI B MT

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THIT B HP TH LOI MNG.

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THIT B LOI PHUN

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THIT B LOI PHUN THNG NGV NM NGANG

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THIT B LOI CNH KHUY

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THIT B HP TH LOI A

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THP M

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THP A CHP

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THP A L

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THP A CH S

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thp a khng c ng chy chuyn

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6. Tnh ng knh thit b.

Gi V Lu lng pha kh, m3/sec,

W0 Vn tc pha kh, m/sec,

D ng knh thp, m

0785,0 wVD

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7. Tnh chiu cao lm vic thp m, H,m.v F = .H.f .

Tnh chiu cao thp a, H, m da vo s bcthay i nng ging nh tnh chiu cao thpchng luyn ta s nghin cu sau (xem trang 34-36 sch tham kho).

tby yk

GF

.