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THIT B V H THNG

T NG

Nguyn Hong An MSSV: 1433001

Cao Duy nh MSSV: 1433021

Tm tt

o lu lng ng mt vai tr quan trng, khng ch v n phc v cho mc ch kim k, o m m cn bi v ng dng ca n trong h thng t ng ha cc qu trnh sn xut. Chnh v vy vic hiu r v phng php o, cng nh nm vng cc c tnh ca thit b o lu lng l iu ht sc cn thit.

M u

Lu lng k l cm bin o khng th thiu o lu lng ca cht kh, cht lng, hay hn hp kh-lng trong cc ng dng cng nghip nh thc phm-nc gii kht, du m- kh t, ha cht-dc phm, sn xut giy, in, xi mng

Trn th trng, cc loi lu lng k rt a dng v lun sn c cho bt k ng dng cng nghip hay dn dng no. Vic chn la cm bin o lu lng loi no cho ng dng c th thng da vo c tnh cht lng (dng chy mt hay hai pha, nht, m c, ), dng dng chy (chy tng, chuyn tip, chy hn lon, ), di lu lng v yu cu v chnh xc php o.

Cc yu t khc nh cc hn ch v c kh v kt ni u ra m rng cng s nh hng n quyt nh chn la ny. Ni chung, chnh xc ca lu lng k cn ph thuc vo c mi trng o xung quanh. Cc nh hng ca p sut, nhit , cht lng/kh hay bt k tc ng bn ngoi no u c th nh hng n kt qu o.

Cm bin o lu lng trong cng nghip c lp t mi trng nhiu cao v thng b xung p. iu ny i hi cc cm bin o lu lng phi hot ng bnh thng c vi xung in p v b c nhiu m bo a ra tn hiu o vi chnh xc cao.

Thng thng, trong cng nghip hay s dng giao din truyn dn tn hiu 4-20mA gia b truyn tn hiu o vi thit b iu khin.

B truyn tn hiu o:

Gn vi cm bin o lu lng c th c cp ngun bi chnh mch vng 4-20mA ny hoc bng ngun ring

S dng mch vng 4-20mA c yu cu rt kht khe v cng sut: tt c cc thit b in thu thp/x l v truyn tin cn phi hot ng c lp vi ngun cp t mch vng 4-20mA, ch nhng vi x l/vi iu khin tiu th rt t in (v d dng vi iu khin DSP) mi c kt hp dng chung ngun ca mch vng 4-20mA

B truyn tn hiu vi kt ni truyn s liu dng s nh tch hp giao din bus trng (Profibus, I/O Link) hoc kt ni khng dy ngy cng ph bin, v chng lm gim thi gian khi ng v cho php gim st lin tc, cng nh chn on li. Tt c cc yu t ny gp phn ci thin ng k nng sut v hiu qu ca h thng t ng ha.

. Di y, bi TT s trnh by tng qut v nguyn tc hot ng, u im v nhc im, cng nh nhng c tnh ca cm bin lu lng cht lng, cht kh m nhm tm hiu.

Cc cm bin lu lng

Cm bin lu lng da vo chnh lch p sut

Cm bin lu lng siu m

Cm bin lu lng Coriolis

Cm bin lu lng in t

GE Panametrics TransPort PT878 Ultrasonic Flow Meter System

C bn nhm chnh da vo nguyn l hot ng ca chng o lu lng, vy PT878 thuc loi no ???

Cm bin lu lng da vo chnh lch p sut ?

Cm bin lu lng in t ?

Cm bin lu lng Coriolis ?

Cm bin lu lng siu m ?

Cm bin lu lng siu m da vo hiu ng Doppler c th hin trn .Cm bin ny bao gm b pht v b thu. B pht thc hin lan truyn sng siu m vi tn s f1=0.5-10MHz vo trong cht lng vi vn tc l v. Gi s rng ht vt cht hoc cc bt trong cht lng di chuyn vi cng vn tc. Nhng ht vt cht ny phn x sng lan truyn n b thu vi mt tn s f2. Sai lch gia tn s pht ra v tn s thu v ca sng cao tn c dng o vn tc dng chy. Bi v loi cm bin lu lng siu m ny yu cu hiu qu phn x ca ht vt cht trong cht lng, nn n khng lm vic c vi cc cht lng mt pha, tinh khit.

Lu lng th tch Q=K(f1,f2), f1 - tn s sng pht, f2 - tn s sng thu v, K - h s, ph thuc gc ti/phn x, v tr vt cht phn x, mt ct ngang

Lu lng th tch Q=K(t1-t2)/(t1t2), t1 - thi gian sng xuyn qua dng chy xui dng, t2 - thi gian sng xuyn qua dng chy ngc dng, K - hng s, ph thuc chiu di ng m thanh, t s gia trc v ng tm, hnh dng dng chy, mt ct ngang.

Cm bin siu m xuyn thng (transit-time). Cm bin loi ny c th cho php o lu lng i vi cht lng/kh rt sch (khng ln tp cht). Cu to ca n bao gm mt cp thit b bin i sng siu m lp dc hai bn thnh ng dn dng chy, ng thi lm vi trc ca dng chy mt gc xc nh trc. Mi thit b bin i bao gm b thu v b pht, chng pht v nhn tn hiu cho nhau (thit b ny pht th thit b kia thu). Dng chy trong ng gy ra s sai lch thi gian ca chm sng siu m khi di chuyn ngc dng v xui dng chy. o gi tr sai lch v thi gian ca chm sng xuyn qua dng chy ny cho php ta xc nh vn tc dng chy. S sai lch thi gian ny v cng nh (nano-giy), do cn phi dng thit b in t, in t c chnh xc cao thc hin php o, hoc tin hnh o trc tip thi gian ny.

C th hiu n gin nguyn l o lu lng khng tip xc ging nh bi ton cho thuyn qua sng (Vt l ph thng). Da trn s chnh lch gia thi gian i v v ta s suy ra c vn tc ca dng chy.

PT878

u im:

Cm bin lu lng xuyn thng a ra k thut o cht lng khng dn in v n mn

Cm bin lu lng siu m lp t g, kp vo ng ng hin ti, cho php khng cn ct b hoc ph hy mt phn ng ng, loi b n ti thiu s tc ng con ngi n cht lng c hi v gim s bi bn cho h thng

Khng c thnh phn lp t trong ng, khng lm gim p lc.

im ni bt ca cm bin siu m l kt qu php o c lp vi hnh dng dng chy.

Nh gn, d em i

o dy ty chn

Thch hp cho hu ht cc kch thc ng v vt liu, bao gm c ng lt

Nhc im:

Gi thnh t v dng chy cn c in y ng.

Thng s k thut

Potable water

Wastewater

Cooling and heating water

Ultrapure water and liquids Water/glycol solutions

Crude oil

Refined hydrocarbons

Diesel and fuel oils

Lubricating oils

Chemicals

Beverages

Other liquids

ng dng :

CM N MI NGI CH

THEO DI V LNG NGHE