Rau cov dej txias txias, dilute hydrochloric acid, qhov kev xaiv ntawm cov khoom siv yuav yog PTFE heat exchanger, tus huab tais ntawm tshuaj tiv thaiv. Tab sis PTFE yog kim. Ib qho ntxiv, rau qhov tshwj xeeb, qhov kub thiab txias, tsis muaj oxidizing kev pab cuam, yog polypropylene (PP), cov khoom yas uas raug nqi ib feem ntawm tus nqi. Nws thermal conductivity yog nyob rau hauv tib yam, sluggish tsawg ntau, yog li nws tsis yog ib tug thermal upgrade. Kev txiav txim siab siv PP yog ib qho kev lag luam nkaus xwb, kev lag luam tawm ntawm PTFE qhov kub ntau thiab kev tiv thaiv kab mob thoob ntiaj teb rau tus nqi qis dua.

Thermal conductivity: Kev sib tw kaw

Lub thermal conductivity ntawm polypropylene (PP) yog kwv yees li 0.2 W / m·K ntawm chav tsev kub. PTFE (polytetrafluoroethylene) muaj cov thermal conductivity me ntsis ntawm 0.25 W / m·K. Hauv cov ntsiab lus, qhov sib txawv 20% no yog qhov tsis txaus ntseeg rau feem ntau ntawm cov ntsuas kub sib txawv. Ob qho khoom siv yog thermal insulators piv rau cov hlau (xws li stainless hlau ntawm ~ 15 W / m·K). Yog li ntawd, PP lub tshav kub exchanger yuav xav tau roughly tib lub tshav kub hloov qhov chaw raws li ib tug PTFE chav tsev rau tib lub luag hauj lwm, dej velocities, thiab kub. Qhov kev ua tau zoo thermal tsis yog vim li cas xaiv PP dhau PTFE, lossis rov ua dua.

Thaum ua haujlwm aPP vs PTFE exchanger thermal conductivity tsawg acidKev sib piv, qhov xaus yog qhov tseeb: thermal conductivity tsis tsav qhov kev xaiv. Ob qho khoom siv nyob rau hauv tib chav kawm uas tsis tshua muaj hluav taws xob, thiab txhua qhov kev tsim qauv sib txawv yog me.

Vim li cas thiaj xaiv PP? Kev sib cav Economic

Qhov zoo tshaj plaws ntawm polypropylene yog nws cov nqi qis. PP yog cov khoom siv thermoplastic uas tsim nyob rau hauv cov ntim loj, nrog rau cov khoom siv raw khoom feem ntau 5-10 npaug qis dua PTFE. Fabrication txoj kev-xws li kub-gas vuam, extrusion, thiab txhaj tshuaj molding- kuj tsis tshua kim tshaj qhov tshwj xeeb sintering thiab compression molding yuav tsum tau rau PTFE. Lub plhaub-thiab-tube lossis coil-hom PP cov khoom siv hluav taws xob tuaj yeem tsim tau rau ib feem ntawm tus nqi ntawm PTFE sib npaug. Rau qhov ntsuas kub qis, tsis muaj kev ua phem rau cov kua qaub, qhov kev txuag nyiaj no tuaj yeem ua tau ntau yam.

Kev txwv ntawm PP: Kub thiab tshuaj tiv thaiv

Thaum PP yog kev lag luam txaus nyiam, nws lub qhov rais ua haujlwm yog nqaim. Qhov siab tshaj plaws kev pabcuam kub kub rau polypropylene tsuas yog txog 80℃(176℃F). Tshaj qhov kub no, PP softens, poob txhua yam muaj zog, thiab pib nkag rau hauv siab. PTFE, los ntawm qhov sib txawv, tuaj yeem ua haujlwm tsis tu ncua ntawm 200℃(392℃F) thiab txuas mus rau 260 degree. Nyob rau hauv qhov kub thiab txias kev pab cuam (piv txwv li, qis dua 60 degree), qhov kev txwv no tau txais, tab sis ib qho txheej txheem chim siab lossis chav ntxuav tuaj yeem tshaj PP qhov kev txwv.

Chemically, PP yog resistant rau ntau dilute acids, bases, thiab aqueous ntsev daws. Txawm li cas los xij, nws raug tawm tsam los ntawm muaj zog oxidizing acids, xws li concentrated nitric acid, sulfuric acid saum 70%, thiab chromic acid. Nws kuj swells los yog yaj nyob rau hauv ntau cov organic solvents (xws li, aromatic hydrocarbons, chlorinated solvents, thiab ketones). PTFE, ntawm qhov tod tes, muaj kev tiv thaiv zoo rau txhua yam tshuaj tshwj tsis yog molten alkali hlau thiab elemental fluorine ntawm qhov kub thiab txias. Yog li, PP yog tus kws tshaj lij tshwj xeeb rau kev txias, huv si, tsis muaj oxidizing acids (xws li dilute HCl, dilute H₂SO₄, acetic acid). PTFE yog lub cev tiv thaiv kab mob thoob ntiaj teb, kub kub, thiab muaj kev nyab xeeb dav dav.

Kev txiav txim siab ntxiv

UV rhiab heev thiab brittleness

Polypropylene muaj kev tiv thaiv tsis zoo rau ultraviolet (UV) hluav taws xob. Yog hais tias lub exchanger raug ntsia sab nraum zoov los yog nyob rau hauv ib qho chaw ci ntsa iab, UV raug ua rau photo-oxidation, ua rau nto tawg thiab poob ntawm lub zog. PP exchangers rau kev pab sab nraum zoov yuav tsum tau shielded los yog pleev xim rau nrog UV-resistant coatings. PTFE yog inherently UV-stable thiab tsis degrade nyob rau hauv tshav ntuj.

Flammability

PP yog cov khoom siv hluav taws xob uas muaj qhov ntsuas qis qis (LOI) ntawm kwv yees li 18%. Nws kub hnyiab tau yooj yim ib zaug ignited, tsim cov pa luam yeeb tuab thiab dripping molten polymer. Kev txiav txim siab txog kev nyab xeeb ntawm hluav taws- xws li cov twj tso kua mis, cov khoom thaiv hluav taws, thiab kev faib hluav taws xob hauv cheeb tsam- yuav tsum tau hais. PTFE muaj LOI ntawm 95% thiab raug cais raws li tsis-flammable; nws tsis txhawb combustion thiab self-extinguishes thaum lub nplaim taws raug tshem tawm. Qhov no ua rau PTFE qhov kev xaiv muaj kev nyab xeeb dua nyob rau hauv ib puag ncig uas muaj hluav taws kub.

Mechanical Strength ntawm qhov kub thiab txias

Thaum qhov kub thiab txias (piv txwv li, qis dua 10 degree), PP yuav ua rau nkig thiab ua rau muaj kev puas tsuaj los ntawm dej rauj lossis dej khov. PTFE tseem tawv thiab hloov tau mus rau qhov kub thiab txias (-200 degree). Rau kev pab cuam txias acid (xws li dej txias los yog cov tub yees txias), PP exchangers yuav tsum tau ceev faj tiv thaiv cov neeg kho tshuab poob siab.

Kev taw qhia kev xaiv: Sib piv cov khoom siv rau kev pabcuam

Kev xaiv ntawm PP thiab PTFE exchanger rau cov kua qaub qis tsis yog thermal, tab sis kev txiav txim siab ntawm kev lag luam thiab tshuaj lom neeg. Siv PP thaum:

Cov kua qaub yog dilute, tsis-oxidizing, thiab huv si (piv txwv li, HCl < 20%, H₂SO₄ < 50%, acetic acid).

Kev ua haujlwm kub yog qis dua 60℃(nrog rau kev nyab xeeb qis dua 80 degree).

Tsis muaj cov kuab tshuaj organic lossis muaj zog oxidizers.

Lub exchanger yog ntsia sab hauv tsev los yog tiv thaiv los ntawm UV.

Kev pheej hmoo hluav taws kub tsawg los yog txo kom txaus.

Tus nqi pib qis tshaj plaws yog qhov tsav tsheb.

Siv PTFE thaum:

Cov kua qaub yog kub (siab tshaj 80 degree), concentrated, los yog oxidizing (xws li, nitric, chromic, los yog kub sulfuric).

Cov kua muaj aggressive organic solvents.

Cov txheej txheem ntxhov siab tuaj yeem dhau ib ntus PP qhov ntsuas kub.

Kev nyab xeeb hluav taws lossis UV raug yog ib qho kev txhawj xeeb.

Lub neej ua haujlwm ntev nrog kev saib xyuas tsawg yuav tsum tau, txawm tias tus nqi siab dua.

Polypropylene yog tus nqi qis, tsis muaj frills workhorse rau txias, maj acid; PTFE yog tus hwm, invincible warrior rau cov kub, wilder, thiab ntau unpredictable chemistry. Tsis yog universally superior - qhov kev xaiv raug yog nyob ntawm lub hnab ntawv txheej txheem.

Xaus: Thermal Conductivity tsis yog qhov txiav txim siab

Nyob rau hauv qhov kub-kub acid kev pab cuam, lub thermal conductivity ntawm PP thiab PTFE yog li ntawd zoo sib xws uas kub exchanger loj thiab kev ua tau zoo yuav luag zoo tib yam. Qhov kev txiav txim siab yog li ntawd nyob rau ntawm cov tshuaj sib raug zoo, qhov kub thiab txias txwv, kev nyab xeeb, thiab tus nqi. Rau kev ua tib zoo txhais, me me, txias kua qaub, PP muaj kev txuag nqi thiab kev pabcuam txhim khu kev qha. Rau tej yam nyuaj, kub, los yog txhoj puab heev chemistry, PTFE qhov tsis sib xws tsis kam lees paub nws tus nqi hwm. Cov khoom siv pheej yig tshaj plaws uas ua haujlwm ntseeg tau yog qhov tsim nyog rau txoj haujlwm-thiab rau qhov kub thiab txias, tsis muaj oxidizing acids, cov khoom ntawd yuav zoo yog polypropylene.