Dab tsi yog Hom Kev Ua Tsis Zoo ntawm Impervious Graphite Heat Exchangers hauv Kev Pabcuam Tshuaj?

Muaj ntau cov txheej txheem sib txawv uas feem ntau yog lub hauv paus ua rau graphite kub exchanger tsis ua haujlwm. Cov no tau nkag siab los ntawm cov neeg ua haujlwm kom txuas ntxiv lub neej kev pabcuam thiab zam kev kaw tsis tau npaj tseg. Graphite, impervious graphite, yog cov khoom muaj zog rau kev siv corrosive tab sis tsis tiv thaiv kev puas tsuaj. Impervious graphite feem ntau yog graphite impregnated nrog PTFE, phenolic resin, lossis carbon. Feem ntau hom kev ua tsis tiav ntawm graphite heat exchangers yog resin degradation, thermal shock cracking thiab yaig. Txhua hom muaj cov tsos mob sib txawv, ua rau, thiab kev tiv thaiv.

Resin Degradation: Lub ntsiag to poob ntawm impermeability
Lub impregnating resin sau lub qhov ntawm cov ntxeem tau graphite substrate thiab muab cov xau-tightness ntawm impervious graphite. Cov resin (feem ntau phenolic, qee zaum PTFE lossis furan) yuav tsum tuav nws txoj kev ncaj ncees thiab nws txoj kev ua raws li cov graphite thaum nws lub neej ua haujlwm. Resin deterioration tshwm sim thaum cov xwm txheej ua haujlwm dhau qhov thermal lossis tshuaj txwv ntawm cov resin.

Thaum tshav kub kub degradation
Phenolic resin pib tawg ntawm qhov kub siab tshaj li 200C (nyob ntawm seb muaj pes tsawg tus qauv). Cov txheej txheem degradation generates volatile byproducts thiab ua rau shrinkage, charring los yog softening ntawm resin. Thaum cov kua nplaum tau rov qab los ntawm lub pore network, cov graphite yuav ntxeem tau dua, tso cai rau kev nqus ntawm cov kua dej corrosive. Qhov no txhais tau hais tias nyob rau hauv lub plhaub - thiab - raj lossis thaiv kev sib pauv:

Hla kev paug plhaub & lub raj sab.

Los ntawm gasketed pob qij txha vim poob ntawm resin rhuav tshem lub foob.

Kev txo qis ntawm kev hloov pauv hluav taws xob qeeb los ntawm fouling lossis deposition ntawm degraded resin khoom.

Chemical Warfare
Qee cov khoom ua rau lub impregnating resin, txawm tias cov graphite substrate nws tus kheej tsis cuam tshuam. Phenolic resin yog hydrolysed sai sai los ntawm cov tshuaj caustic muaj zog (sodium hydroxide, potassium hydroxide) ntawm qhov kub siab. Cov resin tseem tawg los yog yaj los ntawm cov concentrated nitric acid, sulfuric acid saum toj no qee qhov kub, thiab cov kuab tshuaj organic (acetone, methyl ethyl ketone). Chemical compatibility teev feem ntau graphite los ntawm kev sib xyaw ntawm graphite substrate thiab resin. Qhov tsis ua hauj lwm tuaj yeem tshwm sim los ntawm qhov siab tshaj qhov ntsuas ntawm ob qho tib si.

Cov cim qhia ntawm resin deterioration muaj xws li:

Pom tau quaj los yog nchuav los ntawm qhov tsis yog -gasketed feem ntawm graphite block.

Ua kom lub siab poob qis yam tsis muaj fouling (ua rau muaj kev hloov pauv hauv qhov porosity).

Discoloration los yog softening ntawm exposed resin ntawm lub raj kawg los yog flanges

Kev Tiv Thaiv: Ib txwm ua kom qis dua qhov kub thiab txias thiab tshuaj lom neeg txwv rau hom resin uas tsim los ntawm cov chaw tsim khoom. Qhia meej PTFE-impregnated graphite lossis carbon-impregnated (resin-dawb) qib uas muaj feem xyuam rau kev pabcuam caustic lossis oxidising acid.

Thermal Shock Cracking: Hloov kub ceev
Graphite muaj qhov sib piv tsis zoo rau thermal shock piv nrog cov hlau. Thaum muaj qhov kub thiab txias hloov pauv sai heev, xws li kev taw qhia cov kua dej txias rau hauv cov khoom kub sib txawv, cov txheej sab nrauv lossis sab hauv ntawm cov khoom siv graphite nthuav dav lossis sib cog lus sib txawv. Cov khoom siv muaj zog tensile tsawg, tsawg dua qhov kub ntxhov siab tsim, ua rau cov kab nrib pleb kom loj hlob.

Hom Thermal Shock Cases
Pib nrawm- nce: dej txias los yog kua qaub yog circulated los ntawm ib tug block exchanger uas nyuam qhuav tau drained tab sis tseem kub los ntawm kev ua hauj lwm.

Chav los yog kub condensate maj: Ib qho nrawm nrawm ntawm qhov kub thiab txias rau hauv qhov hloov pauv txias.

Cov txheej txheem ntxhov siab: poob ntawm qhov txias txias, nrog rau qhov nruab nrab cua sov tseem nyob, ua raws li kev kub ntxhov ntawm cov kua dej txias.

Ntxuav sai sai tom qab tso cov txheej txheem kub nrog dej txias.

Cov thermal shocks feem ntau yog hla lub raj qhov los yog raws cov kab sib cais ntawm cov blocks. Cov kab nrib pleb tuaj yeem tshwm sim ntawm lub raj - mus rau - cov kab sib txuas los yog raws cov phab ntsa hauv lub plhaub - thiab - tube exchangers. Cov fissures cia ncaj qha bypass txoj kev ntawm lub plhaub thiab lub raj sab, los yog ntawm cov qhov nyob ib sab ntawm lub raj.

Cov tsos mob:

Sudden nce nyob rau hauv cov dej xau ntawm kev pab cuam.

Kev ntsuas siab qhia tau tias poob siab sai.

Pom pom cov kab nrib pleb thaum kuaj (dye penetrant tests qhia).

Kev Tiv Thaiv:

Siv tus nqi tsim nyog ntawm kev hloov pauv kub (feem ntau Tsawg dua lossis sib npaug li 5-10℃/ feeb, nyob ntawm hom exchanger).

TSIS TXHOB ntxiv cov kua dej txias rau hauv lub tshuab nqus dej kub. Khaws lub exchanger wetted nrog dej sov thaum lub sij hawm txias.

• Siv qhov kub thiab txias interlocks los yog raws li kev tswj valve ua haujlwm rau kev pib- nce thiab kaw.

Hom Failure Cov tsos mob tshwm sim ua tau
Resin degradation Leaking through block walls; resin softened at tube ends; rise in pressure decrease without foulingTemperature >200 degree, muaj zog caustics, nitric acid los yog cov kuab tshuaj organic, txuas ntxiv ua haujlwm sab nraum cov tshuaj txwv
Damage from thermal shockSudden cross-leakage between services Cracks apparent with dye penetrant Failure coincident with rapid temperature shiftCold fluid entering hot exchanger; fast heating/cooling (>5-10℃/ min); drained exchanger nrog kub viav vias
Erosion Tube thinning, particularly at tube inlets, baffle edges, or elbows; particle solids in process fluid; localised perforationHigh velocity fluid (>2-3 m / s pom zoo txwv) Ncua crystalline solids, catalyst nplua los yog scale Turbulent zones ze baffles
Erosion: Mechanical Wear los ntawm cov kua ceev thiab cov khoom
Graphite yog ib qho khoom muag muag, nkig. Nws tiv taus rau feem ntau cov tshuaj tua kab mob, tab sis nws qhov chaw muaj kev cuam tshuam rau kev yaig los ntawm cov kua dej siab, tshwj xeeb tshaj yog thaum cov kwj deg nqa cov khoom uas raug tshem tawm. Erosion tsis tu ncua tshem tawm cov khoom siv graphite, thinning tube phab ntsa, baffles lossis thaiv cov channel mus rau qhov chaw ntawm perforation lossis cov qauv tsis ua haujlwm.

Siab -Veocity Erosion
Txawm tias cov kua dej huv ntawm cov kab hluav taws xob siab dhau tuaj yeem ua rau yaig ntawm graphite hauv lub sijhawm. Qhov siab tshaj plaws tau pom zoo tshaj tawm rau cov raj graphite feem ntau yog 2-3 m / sec (nyob ntawm qhov tshwj xeeb exchanger tsim thiab chaw tsim khoom). Saum toj no ntau yam shear rog ntawm cov kua maj mam coj mus rau hauv lub cheeb ntawm lub raj. Qhov kev sib tsoo hnyav tshaj plaws yog nyob rau ntawm lub raj nkag (qhov twg qhov nrawm nrawm tau txhim kho) thiab hauv cov cheeb tsam tam sim ntawd downstream ntawm baffles (qhov twg muaj kev kub ntxhov hnyav).

Erosion los ntawm Particles
Cov kev pabcuam slurry yog qhov teeb meem tshwj xeeb, xws li phosphoric acid nrog gypsum los yog silica, los yog pickling acid nrog hlau hais. Cov khib nyiab tshem tawm yog abrasive thiab nce tus nqi ntawm cov khoom tshem tawm. Tus nqi ntawm erosion nce roughly raws li lub square ntawm qhov tshaj tawm thiab linearly nrog cov khoom concentration thiab hardness ntawm cov hais. Hauv cov xwm txheej hnyav, cov phab ntsa hauv lub raj yuav raug punctured hauv lub hlis.

Cov cim: -

Ua kom cov pa tawm ntau dua yam tsis muaj thermal shock lossis resin tawg.

Nyob ze ntawm qhov nkag, qhov chaw ntawm lub raj zoo li polished nyias.

Ultrasonic kuaj rau qhov sib txawv ntawm phab ntsa thickness.

Perforations uas zoo li ntshiab eroding qhov (tsis jagged tawg).

Kev Tiv Thaiv:

Tsim kom muaj cov kua dej nrawm dua li 2 m / s (thiab tsawg dua yog cov khoom muaj nyob).

• Txhim kho inlet flow distributors los yog tiv thaiv - lub tes tsho yaig ntawm qhov nkag ntawm cov raj.

Ua kom cov raj loj dua los yog ntxiv cov raj ntau dua nyob rau hauv parallel. Qhov ntawd yuav txo qhov nrawm ntawm ib lub raj.

Lim los yog daws cov khoom ntxhib los ntawm cov dej ntws.

Synergistic Effects of Erosion-Corrosion
Hauv qee qhov kev pabcuam, kev yaig thiab corrosion ua haujlwm ua ke. Cov kua yog me ntsis corrosive rau graphite resin binder. Cov txheej txheej tiv thaiv yog tsis tu ncua tshem tawm los ntawm kev yaig nthuav tawm cov khoom tshiab. Xws li kev yaig-corrosion mechanism tuaj yeem ua rau tsis ua haujlwm ntawm tus nqi zoo tshaj qhov suav ntawm tus nqi ntawm tus kheej. Piv txwv li, hydrochloric acid nrog nqa hlau oxide hais los yog sulfuric acid nrog carbon nplua.

Cov lus pom zoo rau kev soj ntsuam thiab soj ntsuam
Cov hauv qab no yuav tsum tau muab tso rau hauv kev tshuaj xyuas tsis tu ncua txhawm rau txheeb xyuas cov hom kev ua haujlwm ua ntej kev puas tsuaj loj:

Kev soj ntsuam pom ntawm lub raj kawg, lub ntsej muag gasket thiab sab nraud ntawm cov blocks thaum lub sijhawm tu.

Graphite nto dye penetrant xeem los qhia cov kab nrib pleb (thermal shock puas).

Ultrasonic thickness ntsuas ntawm qhov tseem ceeb erosion prone cheeb tsam (tube inlets thiab baffle zones).

Lub siab lwj kev sim ntawm lub plhaub thiab lub raj sab rau permeation los yog los ntawm phab ntsa flaws.

Kev soj ntsuam ntawm cov txheej txheem rau kev hloov pauv tsis tau xav txog hauv qhov hluav taws xob kub lossis siab poob.

Xaus
Cov hom graphite heat exchanger tsis ua hauj lwm xws li resin deterioration, thermal shock cracking thiab yaig. Cov no tuaj yeem zam tau los ntawm kev ua raws li cov kev txwv kev ua haujlwm thiab maj mam pib -up/shut- cov txheej txheem nqis. Graphite yog cov khoom siv muaj zog rau kev siv cov kua qaub, tab sis yuav tsum muaj kev qhuab qhia kom tau txais nws lub neej kev pabcuam siab tshaj plaws (feem ntau 10-20 xyoo lossis ntau dua). Cov neeg ua haujlwm yuav tsum saib xyuas qhov ntsuas kub thiab qhov nrawm, tiv thaiv kev hloov pauv sai sai, thiab saib xyuas qhov ntsuas ntawm qhov yaig. Thaum tsis ua hauj lwm tshwm sim, ib qho kev kawm tiav hauv paus, nrog rau kev kuaj mob resin, kev ntsuam xyuas tus qauv tawg thiab phab ntsa tuab, tso cai rau kev kho kom raug. Thaum ua haujlwm tau zoo, impermeable graphite heat exchangers txuas ntxiv muab kev pabcuam txhim khu kev qha thiab kev lag luam hauv cov txheej txheem tshuaj lom neeg hnyav tshaj plaws.