Raws li cov kev xav muaj feem xyuam, yuav luag tag nrhoformaldehydeNyob rau hauv formaldehyde aqueous tov muaj nyob rau hauv daim ntawv ntawm monohydrate thiab polymeric hydrate. Yav tag los yeej ib txwm ntseeg
ed tias feem ntau formaldehyde thiab dej tsim methylene glycol thiab muaj nyob rau hauv aqueous tov, uas muab ib co kev taw qhia rau formaldehyde concentration mechanism. Nyob rau hauv cov xwm txheej ntawm 60 ℃, tag nrho cov dawb formaldehyde ntawm formaldehyde aqueous tov nyiaj rau 0.1 wt% ntawm tag nrho; Nyob rau hauv cov xwm txheej ntawm 100 ℃, tag nrho cov dawb formaldehyde ntawm theformaldehyde aqueous tov nyiaj rau 1 wt% ntawm tag nrho, thiab cov kev hloov hauv cov ntsiab lus ntawm dawb formaldehyde yog raws li cov tshuaj tiv thaiv mechanism ntawm formaldehyde nrog dej. ntawm. Txhawm rau kom tau txais cov ntsiab lus siab dua ntawm formaldehyde, nws yog ib qho tsim nyog yuav tsum ua tiav kev sib cais zoo dua ntawm formaldehyde thiab dej. Tam sim no, kev tsim khoom lag luam feem ntau siv ob txoj hauv kev kom ua tiav lub hom phiaj no:
Siv cov tshuaj tiv thaiv ntawm formaldehyde thiab cawv
Paub tias yuav muab tso rau hauv cov ntawv thov kev lag luam yog cov txheej txheem ntawm DuPont ntawm Tebchaws Meskas thiab cov txheej txheem ntawm Asahi Kasei ntawm Nyiv. Cov txheej txheem DuPont siv 50% formaldehyde tov los teb nrog isooctyl cawv los tsim ethylhexyl semi-aqueous formaldehyde tov, uas yog lub cev qhuav dej thiab thermally tawg kom tau txais high-concentration formaldehyde.
Siv azeotrope ntawm formaldehyde thiab dej
Ntawm 100 ℃ thiab 1 cua, azeotropic muaj pes tsawg leeg ntawm formaldehyde thiab dej yog 21%: 79%, thiab azeotropic kub yog li 96 ℃. Lub azeotropic muaj pes tsawg leeg nce nrog nce kub thiab siab. Thaum qhov kub thiab txias txo qis, cov ntsiab lus formaldehyde hauv azeotrope txo. Thaum lub siab qis dua 26.6 KPa (A) thiab qhov kub thiab txias yog li 65 ℃, qhov tshwm sim azeotrope ploj mus.
Siab concentration
Raws li txoj cai, kev siv zog tuaj yeem siv los ua kom muaj cov formaldehyde nyob rau hauv lub distillate, thiaj li ua tiav cov concentration ntawm formaldehyde. Txawm li cas los xij, thaum cov concentration ntawm formaldehyde ntau dua 45%, cov chav uas yuav tsum tau noj thiab qhov hnyav corrosion ntawm high-temperature thiab high-concentration formic acid gas tshwm sim los ntawm qhov teeb meem no tau txwv tsis pub muaj kev nce ntxiv ntawm cov concentration ntawm cov kua qaub. formaldehyde. Yog li ntawd, kev lag luam tam sim no tsuas yog siv cov txheej txheem siab distillation kom rov qab tau cov tshuaj formaldehyde qis raws li cov khoom siv raw los npaj cov tshuaj formaldehyde nrog cov concentration ntawm li 45%.
Nqus flash
Nqus flash evaporation tam sim no yog txoj hauv kev tseem ceeb ntawm kev tsim cov tshuaj formaldehyde siab. Nws tau ua haujlwm hauv thaj chaw azeotropic, thiab lub tshuab nqus tsev siab dua thiab qis dua yuav tsum tau siv ntau li ntau tau. Ntxiv nrog rau azeotropic tej yam kev mob, kev cia thiab kev thauj mus los ntawm concentrated formaldehyde kuj raug txwv. Nws nyob ntawm qhov concentration ntawm cov concentrated formaldehyde kua tsim. Tam sim no, nws paub tias qhov siab tshaj plaws ntawm formaldehyde tau los ntawm lub tshuab nqus tsev yog 74%. Los ntawm kev xyaum ua lag luam, kev tsim khoom siv nrog 65% mus rau 70% concentrated formaldehyde tuaj yeem ua tiav cov haujlwm ruaj khov mus ntev.
Tsis tas li ntawd, cov txheej txheem ntawm kev siv lwm cov azeotropic cov neeg ua hauj lwm nyiam azeotropic tshem tawm lawv nrog dej, thiab ces tshem tawm cov azeotropic tus neeg saib xyuas los ntawm high-concentration formaldehyde tov kom tau ib tug high-concentration.formaldehydekev daws kuj tau ua tiav ib qho kev ntsuas ntawm kev tsim khoom.