Yuav Ua Li Cas Xaiv Cov Tube kom raug-rau-Baffle Clearance rau PTFE Exchanger nyob rau hauv High-Tub Kub Kev Pabcuam?

Hauv cov pa roj kub kub-rau-gas heat exchanger qhov kub ntawm lub viav vias ntawm PTFE hlab tuaj yeem yog ib puas degrees lossis ntau dua los ntawm qhov txias pib mus rau tag nrho cov haujlwm. Qhov no ua rau cov hlua yas ntev ntev kom ntev thiab dav ntau. Yog hais tias lub qhov nyob rau hauv lub txhav txhawb nqa baffles yog drilled nrog ib tug ze clearance nyob rau hauv chav tsev kub, lub expanding hlab yuav raug nias tawm tsam cov npoo tawv, khi thiab tejzaum nws crushing los yog raug txiav. Ib qho kev txiav txim siab txias qhov kev tshem tawm kom zoo, kev suav tsim tseem ceeb, tuaj yeem tiv thaiv qhov kev qaug dab peg.

Kab lus no piav qhia txog yuav ua li cas ntsuas lub raj baffle clearance yuav tsum tau rau PTFE exchanger gas kev pab cuam, xav txog lub siab coefficient ntawm thermal expansion ntawm PTFE thiab lub zog kub gradients feem ntau pom nyob rau hauv roj- tuav daim ntaub ntawv.

Vim li cas PTFE Tubes nthuav ntau dua li hlau Baffles
Qhov sib txawv loj hauv Thermal Expansion
Lub coefficient ntawm thermal expansion (CTE) ntawm PTFE yog kwv yees li kaum npaug tshaj li ntawm stainless hlau. Txheem tus nqi:

PTFE: 120-200 × 10-6 /℃(nyob ntawm qhov ntsuas kub thiab kev taw qhia)

Stainless hlau (304/316) 16-18 x 10-6 / degree

Rau PTFE raj ua haujlwm ntawm 200℃(ambient pib ntawm 20℃, ΔT=180℃) radial expansion ntawm 20 mm sab nraud txoj kab uas hla yog:

⋅ L= 0 ⋅ L 0 ⋅ Δ T=20 × 150 × 10 − 6 × 180 ≈ 0.54 mm Δ D=D 0 ⋅ PTFE ⋅ Δ T=20 × 150 × 410 mm −

Qhov sib npaug nthuav dav ntawm lub qhov nyob rau hauv stainless hlau baffle ntawm tib txoj kab uas hla yog:

ΔDhole =20 × 17 × 10−6 × 180≈ 0.06 mm ΔDhole =20 × 17 × 10−6 × 180≈ 0.06 mm

Net radial expansion sib txawv (tube rho tawm qhov) yog kwv yees li 0.48 hli. Yog hais tias qhov clearance ntawm chav tsev kub tsuas yog 0.2 hli, lub raj yuav raug yuam tawm tsam lub qhov baffle ntawm kev khiav hauj lwm kub. Qhov no ua rau clamping thiab muaj kev sib txhuam siab thiab muaj peev xwm crushing ntawm lub raj phab ntsa.

Cov teebmeem ntawm Kev Tsis Txaus Siab
Qhov kev puas tsuaj uas tuaj yeem tshwm sim thaum lub raj PTFE raug nias tawm tsam ib qho nyuaj baffle qhov (tshwj xeeb tshaj yog hlau baffle) yog:

Kev khi thiab lub raj buckling - Tube tsis txav mus los ntawm baffle, ua rau axial compression thiab buckling ntawm kev txhawb nqa.

Txiav los yog abrasion - Ib tug ntse ntug ntawm ib tug hlau baffle yuav txiav mus rau hauv lub softened PTFE ntawm qhov kub thiab txias thiab ua rau ib tug to.

Lub siab radial ntau dhau los ntawm lub qhov uas nruj dhau ua rau lub raj nkag mus rau hauv cov duab oval uas txo qis qhov chaw ntws mus tas li thiab ua rau muaj kev tiv thaiv thermal.

Lub raj txias, xoob haum thaum sov yuav tsum tau tso cai kom nthuav dav rau hauv qhov zoo nkauj tab sis tsis haum, zoo li lub piston hauv nws lub tog raj kheej. Kev tshem tawm kom raug yog xws li tias ntawm kev ua haujlwm kub lub raj tsuas yog kov lub qhov baffle, tsis raug pinched.

Kev txiav txim siab ntawm qhov txias clearance yuav tsum tau
KAUJ RUAM 1: Nrhiav qhov siab tshaj plaws ua haujlwm kub ntawm lub raj nplaim
Hauv cov pa roj-rau-gas exchanger lub raj phab ntsa kub yog ib txwm nyob ze rau qhov nruab nrab ntawm cov pa roj kub thiab txias. Tab sis cov dej ntws tuaj yeem raug maldistributed kom muaj cov thaj chaw kub hauv zos. Expansion xam yuav tsum ua raws li qhov siab tshaj plaws ntawm qhov ntsuas kub ntawm lub raj. Conservatism Ntau tus neeg tsim qauv siv qhov kub ntawm cov pa roj kub uas yog qhov phem tshaj plaws ntawm qhov kub thiab txias rau kev khaws cia.

Kauj Ruam 2: Txiav txim siab Radial Expansion ntawm Tube
Siv cov qauv hauv qab no suav qhov nce hauv lub raj sab nraud ntawm qhov ntsuas kub (feem ntau 20 degree) mus rau qhov siab tshaj plaws ua haujlwm kub. Rau kev nyab xeeb siv sab sauv txwv rau CTE ntawm PTFE (xws li . 180-200 x 10^-6 /ºC)

Kauj Ruam 3: Xam Radial Expansion ntawm Baffle Qhov
Cov khoom siv baffle, feem ntau yog cov hlau tsis muaj steel, carbon hlau los yog cov hlua hlau, nthuav ntau dua. Lub net radial cuam tshuam rau xoom clearance ntawm ambient kub yog tau los ntawm nws expansion los txo lub raj expansion.

Kauj Ruam 4: Xaiv qhov tsawg kawg nkaus kub tshem tawm
Qhov tsawg kawg nkaus diametral clearance yog xav tau rau qhov tsis yog - khi zawv zawg haum ntawm qhov siab tshaj plaws ua haujlwm kub. Hom kub clearance rau PTFE tubing yog 0.2 txog 0.5 hli (nyob ntawm txoj kab uas hla raj). Qhov no tiv thaiv lub raj los ntawm radially squeezed.

5. Xam Cov Chav Yuav Tsum Tau-Tsuas Cuam Tshuam Rov Qab
Qhov txias clearance (diametral) tsim nyog yog:

Ccold=Ch+(ΔDtube-ΔDhole) Chot=Ch+(ΔDtube-ΔDhole)

Piv txwv li nrog lub raj OD 20 hli, ΔT=180 degree, kub clearance phiaj=0.3 hli:

=0.3+(0.54-0.06)=0.78 mmCcold=0.3+(0.54-0.06)=0.78mm

Yog li lub qhov baffle yuav tsum tau muab tawm 0.78 hli loj dua lub raj txias OD. Qhov no yog ib qho looser haum tshaj li 0.2-0.3 mm clearance feem ntau siv rau qis -kub kua cov kev pab cuam.

"Kev tsim qauv rau Gas Exchangers ntawm PTFE
Pom zoo nyob nrug deb
Tube OD (mm) Max. Kev khiav hauj lwm kub (degree) Pom zoo txias diametral clearance (mm)
10 150 0.4–0.6 10 200 0.6–0.8 20 150 0.6–0.8 20 200 0.8–1.1 30 200 1.0–1.4
Cov duab no yog ua los ntawm kev siv cov hlau tsis muaj steel baffles thiab kub clearance ntawm 0.3-0.5 hli. Qhov kev tshem tawm tuaj yeem txo qis los ntawm 10-15% rau PFA hlab (nrog CTE me ntsis).

Kev Lag Luam -Tawm: Tsawg Kev Pabcuam Hauv Lub Txias
Lub looser chav kub clearance txhais tau hais tias cov hlab tsis muaj kev txhawb nqa zoo thaum lub exchanger txias los yog thaum pib. Qhov no tuaj yeem ua rau:

Ua kom lub raj muaj kev vibration ntawm qhov xwm txheej tsis txaus los yog tsawg txaus

Muaj peev xwm mus rau tube tiv tauj (yog tias qhov kev tshem tawm loj dhau)

Tube pob me ntsis tawm ntawm kev sib dhos thaum lub sijhawm teeb tsa

Cov teeb meem no feem ntau zam tau vim tias tus exchanger siv feem ntau ntawm nws lub neej kev khiav hauj lwm ntawm qhov kub thiab txias, qhov twg cov hlab inflated ua nruj nreem. Txhawm rau txo qhov phom sij ntawm kev co txias, ntxiv cov baffles nruab nrab lossis los tiv thaiv - cov hlua khi tuaj yeem raug ntxiv, lossis cov raj tuaj yeem ua rau mos mos ntawm cov ntawv raj.

Xaiv cov khoom baffle zoo: Hlau lossis Fluoropolymer
Qhov yuav tsum tau tshem tawm yog nyob ntawm cov khoom ntawm baffle:

Hlau baffles ( Stainless hlau , hastelloy ) - Siab rigidity, ntse npoo . Xav tau qhov kev tshem tawm loj tshaj plaws vim tias lawv tsis muab txoj hauv kev los yog ua raws li lub raj txuas ntxiv. Ib qho muag PFA lossis PTFE baffle yog kev zam txim ntau dua li cov hlau baffle.

Lined hlau baffles - Lub PTFE hauv ob sab phlu muab ib tug softer bearing nto, txo txoj kev txiav. Lub liner yog elastically deformable thiab yog li qhov kev tshem tawm tuaj yeem txo qis me ntsis (10-20%).

Khoom PTFE lossis PFA baffles Cov no nthuav ze li ntau npaum li cov hlab lawv tus kheej. Qhov sib txawv ntawm kev nthuav dav ntawm lub raj thiab baffle yog qhov me me yog li qhov kev sib tw txias txias (0.2-0.4 hli) tuaj yeem ua haujlwm. Tab sis cov khoom fluoropolymer baffles tsis muaj zog thiab tuaj yeem cuam tshuam ntawm cov roj nrawm, ua rau lawv tsis haum rau txhua qhov kev pabcuam roj.

TEMA Standards & PTFE
Cov khoom siv hluav taws xob hlau muaj cov qauv raj- rau- baffle clearances teem los ntawm Tubular Exchanger Manufacturers Association (TEMA). 0.4 hli rau cov raj me me thiab 1.2 hli rau cov raj loj yog qhov kev tshem tawm ib txwm muaj rau cov raj hlau stainless thaum kub heev. TEMA txawm li cas los xij tsis hais txog PTFE tubing ncaj qha, vim PTFE tubing nthuav dav hauv txoj kev sib txawv kiag li.

Ib tug PTFE exchanger yuav tsum tau txiav txim siab pub rau kub kub kev pab cuam gas. Cov neeg tsim qauv ua raws li cov qauv kev lag luam lossis fluoropolymer exchanger tsim cov lus pom zoo (xws li, cov tuam txhab xws li DuPont lossis Chemours) thiab tsis yog TEMA ib leeg. Ib txoj hauv kev zoo yuav yog coj TEMA tshem tawm rau cov raj hlau ua lub hauv paus thiab ntxiv qhov sib txawv ntawm qhov sib txawv ntawm PTFE thiab hlau.

Piv txwv li: Qhia meej meej rau kev pabcuam roj 200 degree.
PTFE raj ntawm 25 hli OD, baffles ntawm 316 stainless hlau, max gas temp 200 degree, ambient siv 20 degree.

Kev suav:

ΔT=180 degree

CTE PTFE ≈ 160 x 10⁻⁶ /℃(nruab nrab ntawm qhov ntau ntawm 20 txog 200 degree)

CTE steel kwv yees li 17 × 10⁻⁶ / degree

ΔD_tube=25 × 160e-6 × 180=0.72 mm

ΔD qhov=25 x 17e-6 x 180=0.077 mm

Net sib txawv expansion=0.72 - 0.077=0.643 mm

Kub clearance phiaj=0.4 hli (25 hli OD)

Clearance Yuav tsum tau txias=0.4 + 0.643=1.043 hli (li 1.0 txog 1.1 hli)

Daim duab Specification: Baffle qhov taub=Tube OD (txias) + 1.0 hli. Nyob rau hauv chav tsev kub qhov haum yog zoo nkauj tsis zoo. Ntawm 200℃lub raj nthuav dav kom ua tiav qhov kev tshem tawm, muab kev txhawb nqa yam tsis muaj kev khi.

Xaus: Tsim rau Thermal Swelling
Ib qho yooj yim zoo li qhov sib txawv ntawm lub raj thiab baffle yog ib qho tseem ceeb tsim feature, kub rhiab heev, nyob rau hauv ib tug PTFE gas exchanger --ntau yam uas tsis txhob muaj kev puas tsuaj thermal lock-up. PTFE nthuav dav nyob ib ncig ntawm kaum npaug ntau dua li cov hlau tsis muaj steel, yog li chav ntsuas kub kom txaus rau cov kev pabcuam ua kua yuav ua rau muaj kev sib khi thiab lub raj puas rau hauv daim ntawv thov roj kub kub. Lub radial nthuav dav ntawm lub raj thiab lub qhov baffle tuaj yeem suav tau thiab qhov kev ua haujlwm kub tsim nyog ntxiv kom paub meej qhov kev tshem tawm qhov txias. Txhua yam khoom siv uas ua kom sov yuav tsum tau tsim kom ua rau nws tus kheej nthuav dav. PTFE gas exchanger nrog lub raj loj-rau-baffle tshem tawm tsis yog kev ua haujlwm tsis zoo. Nws yog kev txawj ntse thermal engineering.