Rau cua sov Formic Acid/Dej Mixtures Nyob rau hauv Agitated Conditions, Tube txoj kab uas hla yuav ua li cas - mus rau -Wall Ratio Alter Erosion - Corrosion Resistance?

Aqueous sib xyaw ntawm formic acid (HCOOH) tsim kom muaj qhov chaw txo qis uas cuam tshuam cov yeeb yaj kiab tsis zoo ntawm titanium. Formic acid tsis induce oxidizing tej yam kev mob rau spontaneous repassivation zoo li nitric acid los yog seawater. Rau formic acid concentrations ntawm 10 thiab 90% ntawm qhov kub siab (70-100 degree) titanium siv ib daim ntawv nyias, kuj tsis ruaj tsis khov. Thaum muaj kev ntxhov siab yog muab los ntawm cov neeg kho tshuab nplawm, lub twj tso kua mis rov ua dua lossis cov pa pa tawm, cov teebmeem sib xyaw ua ke ntawm cov tshuaj tua kab mob thiab cov kua dej siv tshuab ua rau muaj kev yaig- lub xeev corrosion. Cov lus teb ntawm titanium nto rau qhov kev tawm tsam ob zaug no yog nyob ntawm txoj kab uas hla mus rau phab ntsa piv (D / t) ntawm lub raj. Ib qho me me D/t (phab ntsa tuab dua piv rau txoj kab uas hla) hloov qhov kev ntxhov siab ntawm qhov chaw thiab ntws hydrodynamics ntawm lub raj -kiv dej interface, uas cuam tshuam ncaj qha rau cov khoom tshem tawm.

Erosion-Cov txheej txheem Corrosion hauv Agitated Formic Acid

Erosion-corrosion txawv ntawm cov ntshiab corrosion los yog ntshiab yaig; Nyob rau hauv formic acid lub corrosion tivthaiv yog tsis tu ncua tawm tsam cov zaj duab xis passive, thaum lub agitation tivthaiv mechanically tshem tawm ib feem tiv thaiv nto txheej. Lub shear stress yog proportional rau lub square ntawm lub zos tshaj tawm gradient thiab yog tshwm sim los ntawm cov kua tshaj tawm ntawm lub raj nto. Rau ib qho kev khiav dej num, qhov kev tshaj tawm hauv zos thiab kev ntxhov siab yog siab dua nyob rau hauv cov hlab nrog me me diameters (thiab yog li qis dua D / t ratios rau tib phab ntsa thickness). Txawm li cas los xij, cov txiaj ntsig dominating yog vim qhov nyuaj ntawm qhov chaw. Hauv kev teb rau kev ntxhov siab, cov hlab ntsha vibrate ntawm cov zaus txuas nrog lawv cov tawv nqaij. Lub flexural rigidity ntawm lub raj yog proportional rau lub sij hawm ntawm inertia, uas txawv raws li (D4 - (D-2t)4). Ib qho me me D / t piv yields ib lub raj nruj dua uas tiv taus qhov sib txawv ntawm qhov kev co. Qhov kev txo qis ntawm qhov chaw txhais tau hais tias cov zaj duab xis passive feem ntau tawg tsis tshua muaj neeg kho tshuab thiab yog li qhov corrosion tuaj yeem ua rau qeeb qeeb thiab ntau yam tsis siv ceev thiab los ntawm kev tawg zaj duab xis.

Quantitative Correlation Ntawm Cov Khoom Siv Tshem Tawm thiab D / t Ratio

Kev ntsuas lub voj voog hauv 50% formic acid ntawm 85 degree, ntws nrawm ntawm 2 m / s thiab agitation los ntawm Rushton turbine (ntsiab ceev 3 m / s) tau ua rau cov kev sib raug zoo hauv qab no rau Qib 2 titanium:

8 D/t Ratio (xws li . 20mm txoj kab uas hla, 2.5mm phab ntsa): 0.08mm/yr cov khoom tshem tawm tus nqi. Cov phab ntsa loj heev rau txoj kab uas hla ntawm qhov sib piv ua rau lub raj txhav nrog lub ntuj zaus ntau dua 200 Hz, ntau dua li ib txwm agitator zaus (20-50 Hz). Tsawg kawg zaj duab xis vibration cuam tshuam. Erosion-corrosion muaj ib homogeneous tis thiab yog kwv yees.

D/t ratio ntawm 15 (xws li . 24 mm dia, 1.6 mm phab ntsa): Cov khoom tshem tawm tus nqi: 0.22 mm / xyoo. Tube txhav txo qis los ntawm kwv yees li 60% piv rau D/t=8. Ntawm agitator hniav hla zaus, resonant vibration tshwm sim. Kev cuam tshuam hauv cheeb tsam ntawm cov yeeb yaj kiab ntawm lub raj txhawb nqa thiab nruab nrab - ncua kev txhim kho tus nqi tshem tawm los ntawm qhov zoo ntawm 2.7.

D / t piv ntawm 25 (xws li . 25 hli txoj kab uas hla, 1.0 hli phab ntsa): 0.55 hli / xyoo cov khoom tshem tawm tus nqi. Tube txhav txo qis ~ 85% piv rau D/t=8. Kev co ntau dhau ua rau fretting ntawm qhov chaw sib cuag. Kev tshem tawm tus nqi dhau los ua ib cheeb tsam nrog kev quab yuam txhim kho ntawm cov ntsiab lus ntawm kev hloov pauv ntau dua amplitude.

D/t ratio 33 (piv txwv li . 33 hli inch, 1.0 mm phab ntsa): Cov khoom tshem tawm tus nqi> 1.0 mm / xyoo. Lub raj yuav raug ntws tawm -vim vibration tsis hais tus tsim ntawm tus agitator. Tsis pom zoo rau kev siv nrog agitated formica.

Txoj kab uas hla mus rau Phab ntsa Ratio Xaiv Qhia los ntawm Daim Ntawv Thov

Cov txheej txheem kev txiav txim siab rau kev xaiv qhov zoo tshaj plaws D / t piv raws li kev ua haujlwm ntawm agitation siv thiab formic acid concentration yog qhia nyob rau hauv cov lus hauv qab no.

Agitation Condition & Formic Acid Concentration Pom zoo D/t Ratio Core Rationale & Erosion-Corrion Modification
Slow turbine,<1 m/s tip speed, mild agitation, 10–30% formic acid, 70°C 20–25 (e.g., 25 mm × 1.0 mm)Lower acid content results in lower corrosion rate. Thin wall, vibration regulated with additional supports every 500 mm. Reduced material cost.
Kev ntxhov siab me ntsis (2 m / s ceev ceev, baffled tank), 30-60% formic acid, 85℃12 mus rau 18 (piv txwv li, 22 mm × 1.5 mm lossis 30 mm × 2.0 mm) Kev sib cog lus ntawm kev hloov hluav taws xob (phab ntsa nyias dua) thiab rigidity (cov phab ntsa tuab dua). Industrial heater arrangement typical.
Kev ntxhov siab hnyav (siab- shear tov khoom, roj sparging), 60-90% formic acid, 100℃8-12 (xws li . 25} hli x 2.5 hli lossis 20 hli x 2.0 hli) Kev xeb corrosion kuj siab tshaj plaws xav tau. Txais kev hloov hluav taws xob qis dua (phab ntsa tuab ua kom cov thermal kuj) Ntxiv rau cov khoom siv titanium.
Agitated formic acid, suspended crystals (abrasive tej yam kev mob) 6–10 (xws li, 20 mm × 2.5 mm los yog 18 mm × 2.0 mm) D / t ratio minimized rau siab tshaj plaws nruj. Phab ntsa thickness kuj muab rau kev puas tsuaj. Cov tes tsho hloov pauv tau qhia.
Sab nraud Diameter rau Phab ntsa Ratio Engineering

Qhov sib piv D / t tsis yog ywj pheej ntawm kev txhawb nqa lub raj. Cov kev txhawb nqa nruab nrab sib cais ntawm qhov tsis siab tshaj 20 lub raj diameters txo qhov kev vibration amplitude los ntawm qhov zoo ntawm 70 mus rau 80 feem pua ​​​​rau ib qho D / t piv ntau dua 15. Cov khoom siv txhawb nqa: PTFE lossis PEEK inserts zam galvanic corrosion thiab txo fretting nyob rau hauv kev sib piv rau metallic kev txhawb nqa. Lub formic acid concentration profile kuj hloov qhov yaig-corrosion mechanism. Hauv qab 20% formic acid, qhov kev daws teeb meem tsawg dua thiab cov yeeb yaj kiab tsis muaj zog nce ntxiv, tso cai ntau dua D / t ratios. Tshaj li 80% formic acid ntawm 100 degree, tus nqi tsis sib xws ntawm corrosion nce tsis hais txog kev ntxhov siab thiab D / t piv yuav tsum tau txo qis kom muab cov phab ntsa tuab pub rau kev ua kom nyias nyias ntau dua li kev tswj kev co. Cov ntaub ntawv cia rau lub neej ua haujlwm ntev yog tus nqi ntawm phab ntsa thickness (tsis yog qhov piv). Lub phab ntsa 2.0 hli (40 hli txoj kab uas hla) raj nrog D/t{16}} muaj ntau dua erosion kam rau siab tshaj 1.5 hli phab ntsa (22.5 hli inch) raj nrog D/t{19}}

Paub Specification

Thaum xaiv lub titanium rhaub rau formic acid / dej ua ke nyob rau hauv agitated tej yam kev mob, txhais cov agitation nyob rau hauv cov nqe lus ntawm agitator tip ceev (m / s) thiab tank baffling los txiav txim siab agitation siv. Ntawm qhov ceev ceev tsawg dua 1.5 m/sec, cov qauv cua sov tsim ntawm D/t 15-20 tuaj yeem tsim nyog nrog kev txhawb nqa kom zoo. Rau cov lus qhia ceev tshaj 2.5 m / s, lub xeev D / t piv tsis pub tshaj 12. Nug tus neeg muag khoom kom suav cov zaus ntawm ntuj rau lub raj raj geometry thiab txhawb kev sib nrug. Vibration kos npe, ib qho kev hloov pauv hauv amplitude ntawm qee zaus thaum lub sijhawm ua haujlwm yuav qhia tau tias xoob ntawm kev txhawb nqa lossis kev hloov pauv ntawm formic acid concentration, uas cuam tshuam rau cov kua dej ntom ntom. Kev xaiv ntawm txoj kab uas hla- mus rau- phab ntsa piv raws li tus qauv tsim ua rau tus kws tshaj lij tswj hwm kev yaig-corrosion tus nqi hauv ib qho ntawm cov neeg siv khoom xav tau cua sov tshaj plaws rau cov khoom siv titanium.