Surface power density is a core design index of electric heating tubes, representing the heat load borne per unit outer wall area. Many equipment manufacturers pursue compact structure and low procurement cost, designing 316 stainless steel heating tubes with excessively high surface power density without matching medium corrosion resistance. High tshav kub load sharply lifts qhov tseeb tube phab ntsa kub nyob deb tshaj li tej kua kub, rhuav lub dynamic tshuav nyiaj li cas ntawm cov chromium - nplua nuj zaj duab xis passive thiab heev aggravating pitting, crevice thiab nyob rau hauv - deposit corrosion. Tsis quav ntsej txog qhov sib piv txwv ntawm lub zog ntom ntom ua rau cov phab ntsa sai sai thiab tawg ntxov ntawm kev tiv thaiv-cov kav dej kub hauv cov tshuaj thiab cov dej kho.
Excessive power density creates an overheated hot zone on the tube surface. Raws li tus qauv tsim tsis, qhov kub sib txawv ntawm cov phab ntsa thiab cov txheej txheem nruab nrab yog tswj tsis pub dhau 10-20 degree. Once power density exceeds the safe threshold, the wall temperature rises by 30℃or higher. Kev kub siab ua kom lub zog ntawm cov tshuaj chloride ions, cov kua qaub radicals thiab lwm yam corrosive, ua rau lawv nkag mus rau qhov tsis xws luag ntawm cov zaj duab xis passive hauv lub voj voog luv. Meanwhile, kub kub txo cov oxidation kev ua ntawm stainless hlau matrix, slowing tus kheej - kho ceev ntawm puas passive zaj duab xis. Cov txheej tiv thaiv ua rau poob kev ncaj ncees, tsim cov ntsiab lus txuas ntxiv corrosion pib ntawm thaj chaw overheated.
Cov phab ntsa kub kub ua rau cov fouling hauv zos thiab hauv qab - tso nyiaj rau corrosion. Solubility ntawm inorganic ntsev xws li calcium chloride thiab magnesium sulfate txo qis ntawm qhov kub thiab txias. Overloaded cua sov phab ntsa ua rau thermal nag lossis daus ntawm cov pob zeb hauv av impurities, tsim cov nplai me me uas npog cov hlau nto. Qhov sib txawv ntawm qhov ntsuas thiab lub raj phab ntsa ntxiab corrosive ions, tsim kom muaj microenvironment kaum ob lub sij hawm ntau corrosive tshaj qhov nruab nrab nruab nrab. Qhov kub cheeb tsam nyob rau hauv scale ntxiv accelerates hlau dissolution, generating sib sib zog nqus pits uas tsis tau raug tshem tawm los ntawm pa circulating tu. Weld thaj chaw nrog ib txwm tsis muaj zog ua yeeb yaj kiab dhau los ua qhov chaw kub hnyav tshaj plaws nyob rau hauv lub zog siab ceev.
Kev kub ntxhov siab tshwm sim los ntawm ultra- lub zog ceev ceev nthuav dav cov kab nrib pleb tsis zoo. Ntev- lub sij hawm hloov pauv kub siab load thiab qhov kub thiab txias hloov pauv ua rau lub sij hawm nthuav dav thiab kev sib zog ua rau lub raj nplaim. Lub nkig chromium oxide passive zaj duab xis tsis tuaj yeem tiv taus rov qab thermal deformation, ua kom pom tsis pom micro- tawg raws li ion nkag mus. Txawm hais tias kev hloov pauv tsis tu ncua yog teem caij, cov yeeb yaj kiab tsim tshiab yuav tawg dua nyob rau hauv kev kub ntxhov siab tas li, poob ntev - lub sij hawm tiv thaiv - tiv thaiv corrosion. Nyob rau hauv ntau- cov cua kub sib txuas ua ke, ib leeg cov raj muaj lub hnub nyoog muaj zog dua li lub hnub nyoog nrawm dua li lwm tus, ua kom pom tseeb qhov kub thiab txias stratification hauv cov tshuaj tiv thaiv tank.
Cov xov xwm corrosive sib txawv sib xws rau qhov sib txawv ntawm kev nyab xeeb ntawm lub zog ntom ntom txwv. Rau cov dej huv nruab nrab nrog cov ntsiab lus chloride qis dua 20ppm, qhov pom zoo siab tshaj plaws lub zog ceev ntawm 316 cua sov raj yog 1.8 W / cm². Rau brine thiab tsis muaj zog organic acid fermentation kua, qhov kev txwv poob rau 1.2 W / cm² los tswj cov phab ntsa kub. Muaj zog acid thiab alternating acid- puag ncig tu ib puag ncig yuav tsum muaj lub zog ceev hauv qab 0.8 W / cm² kom tsis txhob muaj zaj duab xis tawg. Ib qho kev tsim ntau tshaj li cov kev txwv no yuav ua rau lub voj voog kev pab cuam ntawm 316 stainless hlau cua sov raj.
Cov tuam txhab lag luam yuav tsum rov kuaj xyuas cov cua sov lub raj fais fab tsis zoo thaum lub sijhawm kho khoom siv thiab xaj khoom. Rau cov uas twb muaj lawm overloaded hlab, txo kev khiav hauj lwm hwj chim los ntawm zaus hloov dua siab tshiab tswj kom txo deg tshav kub load. Sib piv qis- zog- ntom tuab- phab ntsa 316 cua sov tub rau kev ua haujlwm corrosive tuaj yeem ua kom tsis muaj zog ntawm zaj duab xis kev ncaj ncees, txiav corrosion tsis ua hauj lwm zaus thiab qis dua kev saib xyuas cov nqi.
表格
| Lub Hwj Chim Loj Tshaj Plaws Tshaj Tawm | Tshwj xeeb Corrosion Damage Mechanism | Standard Control Solution |
|---|---|---|
| Ultra-siab tube phab ntsa kub | Accelerate ion diffusion, inhibit passive zaj duab xis tus kheej - kho | Txwv lub zog ntawm lub zog ntom ntom raws li nruab nrab corrosivity |
| Rapid ntxhia fouling nag lossis daus | High -concentration corrosive micro- kua hauv qab nplai induces tob pitting | Txo cov cua sov kom qeeb thermal nag lossis daus ntawm cov ntsev inorganic |
| Cyclic thermal expansion thiab contraction | Micro- tawg ntawm cov zaj duab xis passive muab kev nkag mus rau ions corrosive | Txais cov qauv tsim hluav taws xob tsawg kom nqaim qhov sib txawv |
| Kev laus tsis sib xws ntawm cov yeeb nkab sib txuas | Overloaded hlab corrode nyiam, ua rau tank kub stratification | Uniform power tis thiab unified power density specification |
Cov ntsiab lus luv luv
Excessive surface power density raises tube wall temperature, accelerates fouling accumulation and generates thermal stress cracks on the passive film, all of which jointly speed up local corrosion of 316 heating tubes. Xaiv qhov sib tw qis zog ceev tshwj xeeb raws li qhov nruab nrab muaj pes tsawg leeg tuaj yeem ua kom ruaj khov tiv thaiv - kev ua haujlwm corrosion thiab txuas ntxiv lub neej kev pabcuam ntawm cov khoom siv cua sov.
