Lub ntsiab lus ntawm sedimentation txoj kev tsom xam yog ntsuas tus nqi ntawm cov khoom nyob (tsuas yog los ntawm cov kua nruab nrab). Thiab siv qhov tseem ceeb ntawm qhov kev daws teeb meem, qhov ntau thiab tsawg ntawm cov khoom no thiab lawv qhov chaw tshwj xeeb yog xam. Txoj kev no txiav txim siab qhov tsis sib xws ntawm ntau hom kev faib tawm, xws li ncua kev kawm ntawv, aerosols, emulsions, uas yog, cov uas tau dav thiab tseem ceeb rau ntau yam kev lag luam.
Lub tswvyim ntawm kev tawg
Ib qho ntawm cov thev naus laus zis tseem ceeb uas qhia cov tshuaj thiab cov khoom siv hauv ntau cov txheej txheem tsim khoom yog lawv qhov zoo. Nws yuav tsum raug coj mus rau hauv tus account thaum xaiv cov cuab yeej siv tshuaj lom neeg, hauv kev tsim khoom ntawm ntau yam khoom noj, thiab lwm yam. Qhov no yog vim tsis tsuas yog lub fact tias nrog ib tug txo nyob rau hauv lub hais ntawm cov khoom, lub nto ntawm lub theem nce thiab tus nqi ntawm lawv kev sib raug zoo nce, tab sis kuj mus rau lub fact tias ib co zog ntawm lub system hloov nyob rau hauv cov ntaub ntawv no.. Hauv particular, lub solubility nce, lub reactivity ncetshuaj, qhov kub thiab txias ntawm theem kev hloov pauv txo. Yog li ntawd, nws tau dhau los ua qhov tsim nyog los nrhiav cov yam ntxwv ntawm qhov sib txawv ntawm ntau lub tshuab thiab hauv kev tshuaj xyuas sedimentation.
Nyob ntawm seb qhov loj npaum li cas ntawm qhov sib txawv ntawm cov theem sib txawv, cov tshuab tau muab faib ua monodisperse thiab polydisperse. Cov qub muaj tsuas yog cov khoom ntawm tib qhov loj. Xws li cov txheej txheem disperse yog qhov tsawg heev thiab hauv kev muaj tiag yog ze rau qhov tseeb monodisperse sawv daws yuav. Ntawm qhov tod tes, feem ntau ntawm cov kab ke uas twb muaj lawm yog polydisperse. Qhov no txhais tau hais tias lawv muaj qhov sib txawv ntawm qhov loj me, thiab lawv cov ntsiab lus tsis zoo ib yam. Nyob rau hauv cov chav kawm ntawm sedimentation tsom xam ntawm disperse systems, qhov ntau thiab tsawg ntawm cov hais uas tsim lawv yog txiav txim, ua raws li los ntawm kev tsim kho ntawm lawv loj tis curves.
Theoretical foundations
Sedimentation yog cov txheej txheem ntawm nag lossis daus ntawm cov khoom uas ua rau cov theem dispersed nyob rau hauv gaseous los yog kua media nyob rau hauv qhov kev txiav txim ntawm lub ntiajteb txawj nqus. Sedimentation tuaj yeem thim rov qab yog tias cov khoom me me (doplets) ntab hauv ntau yam emulsions.
Gravity Fg ua rau cov duab kheej kheej tuaj yeem suav nrog siv tus qauv kho hydrostatic:
Fg=4/3 π r3 (ρ-ρ0)g, qhov twg ρ yog qhov ntom ntawm cov teeb meem; r yog lub vojvoog particle; ρ0 – kua dej ntom ntom; g - ceevcaij nplooj zeeg dawb.
Lub zog ntawm kev sib txhuam Fη, piav qhia los ntawm Stokes txoj cai, tawm tsam qhov teeb meem ntawm cov khoom:
Fη=6 π η r ᴠsed, qhov twg ᴠsed yog qhov nrawm nrawm thiab η yog cov kua viscosity.
Thaum qee lub sijhawm, cov khoom pib hloov pauv ntawm qhov nrawm nrawm, uas tau piav qhia los ntawm kev sib npaug ntawm cov neeg tawm tsam Fg=Fη, uas txhais tau hais tias qhov sib npaug kuj muaj tseeb:
4/3 π r3 (ρ-ρ0) g=6 π η r·ᴠ sed. Los ntawm kev hloov nws, koj tuaj yeem tau txais cov qauv uas qhia txog kev sib raug zoo ntawm lub vojvoog particle thiab nws qhov chaw nyob:
r=√(9η/(2 (ρ-ρ0) g)) ᴠsed=K √ᴠ sed.
Yog tias peb xav txog tias qhov ceev ntawm cov khoom tuaj yeem txhais tau tias yog qhov piv ntawm nws txoj kev H rau lub sijhawm txav τ, ces peb tuaj yeem sau cov kab zauv Stokes:
ᴠsat=N/t.
Tom qab ntawd lub vojvoog ntawm cov khoom tuaj yeem cuam tshuam nrog lub sijhawm ntawm nws qhov kev daws teeb meem los ntawm kev sib npaug:
r=K √N/t.
Txawm li cas los xij, nws tsim nyog sau cia tias qhov theoretical justification ntawm sedimentation tsom xam yuav siv tau raws li ntau yam xwm txheej:
- Solid particle size yuav tsum nyob nruab nrab ntawm 10–5 rau 10–2 saib
- Particles yuav tsum yog spherical.
- Particles yuav tsum txav mus rau qhov nrawm thiab ywj pheej ntawm cov khoom nyob sib ze.
- Kev sib txhuam yuav tsum yog qhov tshwm sim sab hauv ntawm qhov nruab nrab dispersion.
Vim qhov tseeb tias cov kev ncua tiag tiag feem ntau muajcov khoom uas sib txawv hauv cov duab los ntawm cov duab kheej kheej qhia lub tswv yim ntawm qhov sib npaug ntawm lub vojvoog rau lub hom phiaj ntawm kev tsom xam sedimentation. Txhawm rau ua qhov no, lub vojvoog ntawm cov duab kheej kheej kheej kheej ua los ntawm cov khoom siv tib yam li cov khoom tiag tiag hauv qhov kev kawm raug ncua thiab nyob ntawm tib qhov ceev yog hloov mus rau hauv kev sib npaug ntawm kev suav.
Nyob rau hauv kev xyaum, hais nyob rau hauv dispersed systems yog heterogeneous nyob rau hauv loj, thiab lub luag hauj lwm ntawm sedimentation tsom xam yuav hu ua kev soj ntsuam ntawm particle loj faib nyob rau hauv lawv. Nyob rau hauv lwm yam lus, thaum lub sij hawm txoj kev tshawb no ntawm polydisperse systems, cov txheeb ze cov ntsiab lus ntawm ntau feem ntau yog pom (ib txheej ntawm hais tias nws qhov ntau thiab tsawg nyob rau hauv ib tug tej lub sij hawm).
Txoj kev tsom xam sedimentation
Muaj ntau txoj hauv kev los ua kev soj ntsuam ntawm cov kab ke sib cais los ntawm sedimentation:
- saib xyuas hauv thaj chaw gravitational qhov nrawm ntawm cov khoom nyob rau hauv cov kua dej;
- ncua kev ntxhov siab rau nws qhov kev sib cais tom qab rau hauv feem ntawm cov khoom ntawm qhov ntau thiab tsawg hauv lub dav hlau ua kua;
- cais cov hmoov tshuaj rau hauv feem nrog qee qhov me me, ua los ntawm huab cua sib cais;
- saib xyuas hauv thaj chaw centrifugal qhov tsis muaj kev cuam tshuam ntawm cov tshuab tawg heev.
Ib qhov siv dav tshaj plaws yog thawj qhov kev tshuaj xyuas. Rau nws txoj kev siv, tus nqi sedimentation yog txiav txim los ntawm ib qho ntawm cov hauv qab no:
- saib ntawm lub tshuab tsom iav;
- hnyav cov sediment;
- txiav txim siab qhov concentration ntawm cov theem tawg nyob rau hauv ib lub sijhawm ntawm kev daws teeb meem;
- ntsuas hydrostatic siab thaum lub sij hawm tawg;
- txiav txim siab qhov ntom ntawm qhov raug ncua thaum lub sijhawm kho.
Txoj kev xav
Kev ncua kev nkag siab yog cov txheej txheem ntxhib tsim los ntawm cov txheej txheem tawg, qhov loj me uas siab tshaj 10 -5cm, thiab cov kua nruab nrab dispersion. Suspensions feem ntau tshwm sim raws li kev ncua ntawm cov hmoov tshuaj hauv cov kua. Qhov tseeb, qhov no tsis yog tag nrho, vim slurries yog dilute suspensions. Cov khoom ntawm cov theem yog kinetically ywj siab thiab tuaj yeem txav mus los hauv cov kua.
Nyob rau hauv tiag tiag (ntseeg) suspensions, feem ntau hu ua pastes, khoom particles cuam tshuam nrog ib leeg. Qhov no ua rau muaj kev tsim ntawm cov qauv spatial.
Muaj lwm hom kev faib tawm uas tsim los ntawm cov txheej txheem dispersed thiab kua dispersion media. Lawv hu ua lyosols. Txawm li cas los xij, qhov loj me me me dua (ntawm 10 -7txog 10 -5cm). Hauv qhov no, sedimentation hauv lawv yog qhov tsis tseem ceeb, tab sis lyosols yog tus cwj pwm los ntawm cov xwm txheej xws li Brownian motion, osmosis thiab diffusion. Kev soj ntsuam sedimentation ntawm kev ncua yog nyob ntawm lawv cov kinetic instability. Qhov no txhais tau hais tias kev tshem tawm yog tus cwj pwm los ntawm lub sijhawm hloov pauv ntawm qhov tsis xws li kev ua kom zoo thiab sib npaug ntawm cov khoom hauv qhov nruab nrab dispersion.
Methodology
Kev tshuaj xyuas sedimentation yog ua los ntawm kev sib npaug torsion nrog lub khob ntawv nyiaj(inch 1-2 cm) thiab iav siab. Ua ntej pib qhov kev tshuaj ntsuam, lub khob yog hnyav rau hauv qhov nruab nrab dispersion, immersing nws nyob rau hauv ib lub khob ntim puv thiab ntsuas qhov sib npaug. Nrog rau qhov no, qhov tob ntawm nws immersion yog ntsuas. Tom qab ntawd, lub khob raug tshem tawm thiab muab tso rau hauv ib lub khob sai sai nrog qhov kev sim ncua, thaum nws yuav tsum tau dai rau ntawm qhov sib npaug ntawm qhov sib npaug. Nyob rau tib lub sijhawm, lub stopwatch yuav pib. Lub rooj muaj cov ntaub ntawv ntawm qhov loj ntawm nag lossis daus ntawm cov ntsiab lus arbitrary hauv lub sijhawm.
| Lub sijhawm pib kawm, s | Mass ntawm khob nrog sediment, g | Ntau cov sediment, g | 1/t, c-1 | Sedimentation limit, g |
Siv cov ntaub ntawv cov lus, kos ib qho kev nkhaus ntawm daim duab. Qhov loj ntawm cov khoom sib hais yog npaj raws li axis ordinate, thiab lub sij hawm yog plotted raws abscissa axis. Nyob rau hauv cov ntaub ntawv no, ib tug txaus scale raug xaiv kom nws yooj yim los ua ntxiv graphical xam.
Kov tsom xam
Hauv qhov nruab nrab monodisperse, qhov kev daws teeb meem ntawm cov khoom yuav zoo ib yam, uas txhais tau hais tias kev daws teeb meem yuav txawv ntawm qhov sib xws. Txoj kab nqes sedimentation hauv qhov no yuav yog linear.
Thaum lub sijhawm daws teeb meem ntawm polydisperse ncua kev kawm (uas tshwm sim hauv kev xyaum), cov khoom sib txawv kuj txawv ntawm qhov ceev ceev. Qhov no yog qhia rau ntawm daim duab nyob rau hauv qhov muag plooj ntawm ciam teb ntawm txheej txheej.
Qhov nkhaus nkhaus yog ua tiav los ntawm kev faib ua ob peb ntu thiab kos duab tangents. Txhua tangent yuav characterize lub subence ntawm ib tug caismonodisperse ib feem ntawm kev ncua.
Lub tswv yim dav dav ntawm particle loj faib
Cov ntsiab lus ntau ntawm cov khoom ntawm qee qhov loj hauv pob zeb feem ntau hu ua granulometric muaj pes tsawg leeg. Qee lub zog ntawm cov xov xwm ntxeem tau nyob ntawm nws, piv txwv li, permeability, thaj chaw tshwj xeeb, porosity, thiab lwm yam. Raws li cov khoom no, nyob rau hauv lem, cov lus xaus yuav tau kos txog lub geological tej yam kev mob rau tsim pob zeb deposits. Tias yog vim li cas ib qho ntawm thawj theem hauv kev kawm ntawm cov pob zeb sedimentary yog granulometric tsom xam.
Yog li, raws li cov txiaj ntsig ntawm kev tshuaj xyuas ntawm cov granulometric muaj pes tsawg leeg ntawm cov xuab zeb hauv kev sib cuag nrog cov roj, lawv xaiv cov cuab yeej siv thiab cov txheej txheem ua haujlwm hauv kev xyaum ua roj. Nws pab xaiv cov lim dej kom tsis txhob xuab zeb nkag mus rau hauv qhov dej. Tus nqi ntawm av nplaum thiab colloidal-dispersed minerals nyob rau hauv muaj pes tsawg leeg txiav txim cov txheej txheem ntawm nqus ions, raws li zoo raws li lub degree ntawm o ntawm pob zeb nyob rau hauv dej.
Sedimentary tsom xam ntawm granulometric muaj pes tsawg leeg ntawm pob zeb
Vim qhov tseeb tias kev tshuaj xyuas ntawm cov tshuab tawg raws li cov hauv paus ntsiab lus ntawm sedimentation muaj ntau qhov kev txwv, nws siv hauv nws daim ntawv ntshiab rau kev kawm granulometric ntawm pob zeb muaj pes tsawg leeg tsis muab kev ntseeg siab thiab raug. Niaj hnub no nws tau ua tiav siv cov cuab yeej siv niaj hnub siv cov khoos phis tawj.
Lawv tso cai rau kev kawm ntawm pob zeb hais los ntawm cov txheej txheem pib, tso cai rau koj mus txuas ntxiv sau cov tsub zuj zujsediment, tsis suav nrog approximation los ntawm kev sib npaug, ntsuas cov sedimentation ncaj qha. Thiab, tsis muaj tsawg tseem ceeb, lawv tso cai rau kev kawm ntawm sedimentation ntawm irregularly zoo li hais. Qhov feem pua ntawm ib feem ntawm ib qho loj lossis lwm qhov yog txiav txim los ntawm lub computer, raws li tag nrho cov qauv ntawm cov qauv, uas txhais tau hais tias nws tsis tas yuav hnyav ua ntej kev tshuaj ntsuam.
