Nyob rau hauv cov lag luam twg yog Graphite lub Default Heat Exchanger Khoom thiab Vim li cas?

Hauv qee qhov chaw, kev qhia txog graphite heat exchanger yog tsis muaj -brainer. Graphite tau ua haujlwm rau ntau xyoo lawm thiab yog cov khoom ntawm kev xaiv qhov twg lwm cov ntaub ntawv yuav ua tsis tau sai lossis yuav kim dhau los ua tau. Qhov twg hlau xeb thiab polymers soften los yog poob thermal efficiency, impermeable graphite (phenolic los yog furan resin impregnated) muaj ib tug tshwj xeeb ua ke ntawm thermal conductivity, tshwj xeeb corrosion kuj rau ntau yam hnyav hnyav, thiab serviceability mus txog 200℃thiab tshaj. Peb yuav tsum paub cov txheej txheem meej uas graphite ua haujlwm zoo dua li lwm yam khoom siv kom paub txog kev lag luam kev lag luam ntawm graphite heat exchangers.

Kev lag luam tseem ceeb
Peb qhov kev lag luam tseem ceeb tsis tu ncua xaiv cov graphite kub exchanger raws li qhov kev xaiv ua ntej. Hlau pickling (hydrochloric acid), concentration ntawm phosphoric acid, ziab ntawm chlorine. Hauv txhua qhov kev daws teeb meem zoo tshaj plaws thiab kev lag luam zoo tshaj plaws yog graphite vim tias muaj qhov sib txawv ntawm cov kua dej, qhov kub thiab txias thiab qhov yuav tsum tau ua rau kev sib cog lus, kev hloov hluav taws xob zoo.

IndustryCritical Fluid Conditions of Operation FailureResult of Substandard Materials
Hlau Pickling (HCl) Kub hydrochloric acid 80-95 degree, mus txog 18% HCl Feem ntau nrog FeCl 2Metal exchangers (titanium, tantalum) corrode sai PTFE softens; xav tau cov units loj dua
Concentration ntawm phosphoric acid ntub- txheej txheem phosphoric acid nrog fluorides, chlorides, silica 100-160 degree, 40-54% P2O5, muaj HF thiab H2SiF6 iav-lined steel raug tua los ntawm fluoride; high-alloy hlau (Hastelloy) corrode los yog kim heev
Cov roj chlorine ntub dej + concentrated sulfuric acid 10-40℃(lub luag haujlwm txias), ua kom muaj zog oxidising, acidic condensate Ceev oxidation ntawm hlau (nickel, tooj liab, hlau); tsis yog-kev xaiv hlau (PTFE) tsis muaj thermal conductivity rau compact drying coolers
Steel Pickling - Kub Hydrochloric Acid Service
Hlau strip thiab hlau pickling Kub hydrochloric acid (feem ntau 10-18% HCl ntawm 80-95 degree) yog siv los tshem tawm cov hlau oxide nplai. Cov kua qaub yog ntim nrog ferrous chloride (FeCl2) thiab yuav tsum tau ua kom sov tas li kom cov txheej txheem ua haujlwm zoo nrog rau txias hauv cov kua qaub rov ua dua tshiab. Cov khoom siv hluav taws xob zoo xws li cov titanium, tantalum thiab zirconium raug kev txom nyem los ntawm pitting ceev, crevice corrosion los yog hydrogen embrittlement los ntawm kub HCl. Nickel-raws li alloys tawg hauv lub lis piam. PTFE plhaub thiab tube exchangers yog resistant rau tshuaj tua kab mob, tab sis lawv muaj ob tug loj tsis zoo:

Qhov hluav taws xob qis qis (0.2 W/m·K vs. 100–120 W/m·K rau graphite) txhais tau hais tias chav tsev loj thiab qhov chaw-siv.

Kev txwv kub: PTFE softens thiab creeps nyob ib ncig ntawm 110℃thiab yog li tsis haum rau kub kub pickling los yog regeneration boiler dej.

Graphite thaiv los yog plhaub thiab lub raj cua kub exchangers tuaj yeem ua haujlwm ruaj ntseg ntawm 95℃thiab tuaj yeem ua haujlwm luv luv rau 120-130 degree. Qhov loj me me ua rau nws yooj yim rau kev sib xyaw ua ke rau hauv cov kab uas twb muaj lawm. Lub neej kev pabcuam hauv HCl kev pabcuam yog 10-20 xyoo rau ntau pua kev teeb tsa thoob ntiaj teb. Graphite yog li cov khoom siv rau pickling acid heaters, coolers thiab regeneration system heat exchangers. Qhov twg PTFE tuaj yeem ua haujlwm raws li kev xav, qhov loj dua thiab cov nqi siab dua ntawm PTFE chav tsev feem ntau nyiam graphite.

Phosphoric Acid Concentration: Ua hauj lwm nrog kub kub thiab fluorides
Kev ntub dej - txheej txheem phosphoric acid (WPA) yog tsim los ntawm reacting phosphate pob zeb nrog sulfuric acid. Cov kua qaub uas tau txais muaj ntau yam ntawm impurities: fluorides (raws li HF thiab H2SiF6), chlorides thiab hlau sulphates. Kev sib xyaw ntawm ib ncig ntawm 28% P₂O₅ rau cov tub lag luam-qib 54% P₂O₅ yog nqa tawm hauv lub tshuab nqus tsev lossis cua kub ntawm qhov kub txog li 160 degree. Cov ntsiab lus fluoride yuav ua phem rau cov silicon{10}}cov ntaub ntawv (iav, iav{11}}liab steel) thiab ntau yam tshwj xeeb alloys.

Graphite heat exchangers yog siv dav hauv cov cua sov, evaporator calandria thiab condenser coolers hauv phosphoric acid cov chaw. Graphite tau dhau los ua lub neej ntawd rau: Cov laj thawj suav nrog:

Fluoride tsis kam: Graphite tsis cuam tshuam los ntawm HF lossis fluorosilicic acid nyob rau hauv cov concentrations thiab kub hauv WPA concentration.

Kev kub siab ua haujlwm: Graphite khaws nws lub zog txhua yam thiab kev tiv thaiv corrosion mus txog 170-200 degree, npog txhua daim ntawv thov phosphoric acid concentration.

Thermal conductivity kom zoo dua: Graphite yog ib tug zoo tshav kub conductor thiab qhov no yog ib tug ntxiv rau evaporator tsim nyob rau hauv uas nws txhais tau hais tias tsawg ntog cheeb tsam thiab me me hlab ntsha.

PTFE kuj tiv thaiv cov fluorides, txawm li cas los xij PTFE cov khoom siv hluav taws xob tsis tshua tau thov hauv kev lag luam no. Qhov teeb meem tseem ceeb yog qhov ntau dua hneev taw rau tib txoj haujlwm. Rau cov chaw loj phosphoric acid (ntau pua txhiab tons hauv ib xyoos) qhov chaw muaj kev txwv thiab kev txhawb nqa rau cov PTFE pauv loj loj tsis yog kev lag luam txaus nyiam. PTFE kuj muaj qhov kub siab tshaj plaws ntawm ~ 180 degree, uas muaj cov npoo me me rau cov xwm txheej cuam tshuam. Graphite zaum ntawm cov hlau kab txawv (uas corrode sai heev) thiab qis kub polymers (uas xav tau ntau dhau lawm).

Chlorine drying: cua txias ua haujlwm tiv thaiv oxidation
Nyob rau hauv cov nroj tsuag chlorine alkali chlorine gas tsim los ntawm daim nyias nyias los yog diaphragm electrolysis yog saturated nrog dej vapor. Cov chlorine ntub dej yog corrosive heev, tsim hypochlorous thiab hydrochloric acid. Cov tshuaj chlorine ntub dej yog qhuav hauv ntim cov yees los ntawm kev sib cuag nrog sulfuric acid muaj zog (98-99%). Cov roj chlorine qhuav uas ua rau (nrog cov kua qaub pos huab) yuav tsum tau txias ua ntej compression lossis ua haujlwm ntxiv. Chlorine coolers downstream of the dry towers are graphite shell-and-tube heat exchangers.

Vim li cas graphite hauv thawj qhov chaw? Cov roj cua txias muaj cov tshuaj chlorine qhuav thiab cov seem sulfuric acid vapor thiab condensate. Qhov sib tov no yog ib qho muaj zog oxidizer thiab yuav tawm tsam feem ntau cov hlau. Tooj, hlau thiab npib tsib xee corrode ceev. Tantalum yog resistant tsis tau kim heev rau qhov tseem ceeb tshav kub hloov chaw. Chemically resistant, PTFE tsis tuaj yeem muab lub compact, high efficiency txias uas yuav tsum tau condense acid pos huab thiab tswj roj kub. Lub siab kub conductivity ntawm graphite tso cai rau cov khoom siv hluav taws xob pheej yig uas tuaj yeem nkag tau yooj yim ntxiv rau lub tsheb ciav hlau kom qhuav chlorine.

Cov kev pabcuam chlorine kuj tau ua ib thaj chaw uas cov graphite heat exchangers tau ua haujlwm rau ntau tshaj 50 xyoo, nrog rau qhov zoo -tsim kom muaj kev nyab xeeb thiab kev ntseeg siab. Hauv cov tshuaj chlor-alkali sector, cov txheej txheem engineers feem ntau qhia graphite coolers raws li qhov tseeb, tsis tshua xav txog lwm yam khoom siv.

Vim li cas PTFE tsis yog lub neej ntawd
PTFE muaj cov tshuaj tiv thaiv tshwj xeeb, yog li vim li cas graphite tseem yog qhov kev xaiv niaj hnub hauv cov kev lag luam no? Vim li cas ho tsis PTFE? Cov lus piav qhia los mus rau peb qhov kev txwv PTFE:

Kub qab nthab: PTFE yuav soften thiab pib swb nyob rau hauv siab saum toj no hais txog 110-120 C Nruam ua hauj lwm ntawm 150℃yog tsis conceivable. Graphite ruaj khov yam tsawg li 200 C.

Thermal conductivity: Cov thermal conductivity tsawg heev ntawm PTFE xav tau cov cheeb tsam loj loj rau kev hloov hluav taws xob. Rau cov ntawv thov uas xav tau ntau pua square metres, chav PTFE yuav loj heev, hnyav thiab kim rau nruab.

Mechanical robustness: Cov graphite blocks thiab lub plhaub -thiab-tube units muab kev ruaj ntseg, txhim khu kev qha rau cov ntawv raj thiab gaskets. Ua tib zoo tensioning ntawm PTFE hlab yog tsim nyog vim hais tias lawv muaj feem xyuam rau cov neeg kho tshuab puas thaum lub sij hawm ntxuav.

Yog tias qhov ntsuas kub ntawm PTFE tsis dhau ntawm daim ntawv thov thiab qhov chaw tsis muaj kev txhawj xeeb, ces PTFE tuaj yeem xaiv. Txawm li cas los xij, nyob rau hauv peb qhov chaw qhia, steel pickling, phosphoric acid concentration, thiab chlorine kom qhuav, kev sib xyaw ua ke ntawm qhov kub thiab txias, siab corrosivity, thiab kev lag luam tsim nyog rau kev tsim compact ua rau graphite qhov kev xaiv.

Lub luag hauj lwm ntawm Keeb Kwm Field Success
Graphite lub luag haujlwm tseem ceeb yog vim muaj ntau xyoo ntawm kev tsim kev ua haujlwm. Hauv cov txheej txheem nyuaj li no, graphite tau ua pov thawj muaj kev ntseeg siab ntau dua li lwm cov khoom siv. Cov ntaub ntawv hauv chav kuaj feem ntau tsav kev xaiv cov khoom siv, tab sis ua li yav dhau los kev paub dhau los. Cov kws tshaj lij qhia cov khoom siv rau cov kab tshiab tshiab, phosphoric acid evaporator, lossis chlorine txias tsheb ciav hlau feem ntau lo nrog cov qauv kev lag luam ntawm graphite, vim tias qhov kev sib txawv ntawm qib ntawd tsis tsim nyog.

Cov ntsiab lus xaus
Graphite heat exchangers yog cov khoom siv niaj hnub hauv steel pickling (kub HCl), phosphoric acid concentration (kub, fluoride uas muaj cov kua qaub) thiab chlorine kom qhuav (dawb chlorine nrog sulfuric acid). Graphite muaj kev sib xyaw ua ke ntawm cov tshuaj tiv thaiv, siab thermal conductivity thiab kub muaj peev xwm tsis tuaj yeem sib tw los ntawm lwm cov ntaub ntawv (hlau, PTFE, iav) dhau qhov ua tiav ntawm cov txheej txheem hauv txhua qhov xwm txheej. PTFE yog zoo dua nyob rau hauv cov tshuaj inertness nyob rau hauv qis kub, tab sis nws tsis zoo thermal conductivity thiab kub txwv ua rau nws unsuitable raws li ib tug hloov rau graphite nyob rau hauv cov ntaub ntawv thov. graphite heat exchanger default kev lag luam raws li txoj cai tsis yog kev huam yuaj- nws yog raws li kaum xyoo ntawm kev ntseeg siab, tus nqi -kev pab cuam zoo qhov twg lwm txoj kev tau rov ua tsis tiav.