{"id":718,"date":"2026-10-28T21:32:22","date_gmt":"2026-10-28T13:32:22","guid":{"rendered":"https:\/\/siliconcarbide.net\/?p=718"},"modified":"2026-10-28T21:32:22","modified_gmt":"2026-10-28T13:32:22","slug":"proc-dochazi-ke-predcasnemu-selhani-nebo-k-driftu-ochrannych-trubic-termoclanku-ve-sklarskych-pecich","status":"publish","type":"post","link":"https:\/\/siliconcarbide.net\/cs\/why-thermocouple-protection-tubes-fail-early-or-drift-in-glass-furnaces\/","title":{"rendered":"Pro\u010d doch\u00e1z\u00ed k p\u0159ed\u010dasn\u00e9mu selh\u00e1n\u00ed nebo k odchylk\u00e1m v hodnot\u00e1ch ochrann\u00fdch trubic termo\u010dl\u00e1nk\u016f ve skl\u00e1\u0159sk\u00fdch pec\u00edch"},"content":{"rendered":"<p dir=\"auto\"><strong>Pro\u010d doch\u00e1z\u00ed k p\u0159ed\u010dasn\u00e9mu selh\u00e1n\u00ed nebo k odchylk\u00e1m v hodnot\u00e1ch ochrann\u00fdch trubic termo\u010dl\u00e1nk\u016f ve skl\u00e1\u0159sk\u00fdch pec\u00edch<\/strong><\/p>\n<p dir=\"auto\">Po dvan\u00e1cti letech provozu p\u0159i taven\u00ed skla se opakovan\u011b vyskytuje probl\u00e9m, \u017ee hodnoty z termo\u010dl\u00e1nk\u016f postupn\u011b vybo\u010duj\u00ed nebo dojde k poru\u0161e ochrann\u00e9 trubice dlouho p\u0159ed pl\u00e1novan\u00fdm cyklem \u00fadr\u017eby. Teplota pece je stabiln\u00ed a termo\u010dl\u00e1nek je spr\u00e1vn\u00e9ho typu, p\u0159esto se nam\u011b\u0159en\u00e1 teplota posouv\u00e1 o des\u00edtky stup\u0148\u016f, p\u0159\u00edpadn\u011b trubice praskne nebo se zten\u010d\u00ed v m\u00edst\u011b styku se sklem nebo ve spalovac\u00ed komo\u0159e. P\u0159\u00ed\u010dinou jsou rychlost koroze zp\u016fsoben\u00e1 alkalick\u00fdmi parami nebo roztaven\u00fdm sklem a tepeln\u00e1 vodivost materi\u00e1lu trubice, kter\u00e9 spole\u010dn\u011b ur\u010duj\u00ed jak \u017eivotnost, tak zpo\u017ed\u011bn\u00ed teplotn\u00ed odezvy.<\/p>\n<p dir=\"auto\">Trubky z oxidu hlinit\u00e9ho (obvykle 99 % Al\u2082O\u2083) d\u00edky sv\u00e9 chemick\u00e9 stabilit\u011b pom\u011brn\u011b dob\u0159e odol\u00e1vaj\u00ed p\u016fsoben\u00ed roztaven\u00e9ho skla a alkalick\u00fdch par, maj\u00ed v\u0161ak st\u0159edn\u00ed tepelnou vodivost (kolem 25\u201330 W\/m\u00b7K) a omezenou odolnost proti tepeln\u00fdm \u0161ok\u016fm. Trubky z karbidu k\u0159em\u00edku, zejm\u00e9na slinut\u00e9 nebo rekrystalizovan\u00e9 typy, nab\u00edzej\u00ed vy\u0161\u0161\u00ed tepelnou vodivost (\u010dasto 30\u201350 W\/m\u00b7K nebo v\u00edce) a lep\u0161\u00ed odolnost proti teplotn\u00edm \u0161ok\u016fm, co\u017e sni\u017euje zpo\u017ed\u011bn\u00ed odezvy, av\u0161ak u n\u011bkter\u00fdch typ\u016f m\u016f\u017ee doch\u00e1zet k povrchov\u00e9 oxidaci nebo k reakc\u00edm ve siln\u011b alkalick\u00fdch atmosf\u00e9r\u00e1ch. Koroze prob\u00edh\u00e1 reakc\u00ed oxid\u016f alkalick\u00fdch kov\u016f s povrchem trubky, p\u0159i\u010dem\u017e se tvo\u0159\u00ed vrstva s n\u00edzkou teplotou t\u00e1n\u00ed, kter\u00e1 se pomalu rozpou\u0161t\u00ed nebo odlupuje. V pono\u0159en\u00fdch \u010d\u00e1stech je korozn\u00ed p\u016fsoben\u00ed rychlej\u0161\u00ed; v horn\u00ed \u010d\u00e1sti nebo nadstavb\u011b je korozn\u00ed p\u016fsoben\u00ed zp\u016fsobeno kondenzac\u00ed par. Zten\u010den\u00ed st\u011bny zvy\u0161uje riziko mechanick\u00e9ho selh\u00e1n\u00ed, zat\u00edmco siln\u00e1 st\u011bna nebo st\u011bna s n\u00edzkou tepelnou vodivost\u00ed zvy\u0161uje \u010dasovou konstantu m\u011b\u0159en\u00ed.<\/p>\n<p dir=\"auto\">V peci na sklo v kontejneru, pracuj\u00edc\u00ed p\u0159i teplot\u011b 1450\u20131500 \u00b0C, byly v horn\u00ed \u010d\u00e1sti pece po dobu 90 dn\u016f instalov\u00e1ny vedle sebe dv\u011b uzav\u0159en\u00e9 ochrann\u00e9 trubice. Trubice z oxidu hlinit\u00e9ho (p\u016fvodn\u00ed tlou\u0161\u0165ka st\u011bny 6 mm) vykazovala v nejteplej\u0161\u00ed z\u00f3n\u011b pr\u016fm\u011brn\u00e9 zten\u010den\u00ed 1,2 mm a nam\u011b\u0159enou \u010dasovou konstantu p\u0159ibli\u017en\u011b 45 sekund p\u0159i zm\u011bn\u011b zat\u00ed\u017een\u00ed ho\u0159\u00e1ku. Trubice ze slinut\u00e9ho karbidu k\u0159em\u00edku (p\u016fvodn\u00ed tlou\u0161\u0165ka st\u011bny 5 mm) vykazovala za stejn\u00fdch podm\u00ednek zten\u010den\u00ed o 0,7 mm a \u010dasovou konstantu p\u0159ibli\u017en\u011b 28 sekund. V \u017e\u00e1dn\u00e9 z trubic nedo\u0161lo k pr\u016fchoz\u00edm trhlin\u00e1m. Po demont\u00e1\u017ei vykazoval povrch trubky z oxidu hlinit\u00e9ho tenkou reak\u010dn\u00ed vrstvu obsahuj\u00edc\u00ed sod\u00edk a drasl\u00edk; povrch trubky z karbidu k\u0159em\u00edku m\u011bl tenkou vrstvu oxidu k\u0159emi\u010dit\u00e9ho s omezen\u00fdm pronik\u00e1n\u00edm alkalick\u00fdch prvk\u016f. Teplotn\u00ed \u00fadaje z trubky z karbidu k\u0159em\u00edku sledovaly zm\u011bny v procesu p\u0159esn\u011bji, zat\u00edmco trubka z oxidu hlinit\u00e9ho vykazovala dostate\u010dn\u00e9 zpo\u017ed\u011bn\u00ed, kter\u00e9 vy\u017eadovalo v\u011bt\u0161\u00ed mrtvou z\u00f3nu regulace.<\/p>\n<p dir=\"auto\">P\u0159i v\u00fdb\u011bru trubek se proto zohled\u0148uje rovnov\u00e1ha mezi odolnost\u00ed proti korozi, tepelnou vodivost\u00ed a tlou\u0161\u0165kou st\u011bny s ohledem na konkr\u00e9tn\u00ed um\u00edst\u011bn\u00ed. Pro kontrolu koroze sklen\u011bn\u00fdch trubek chr\u00e1n\u00edc\u00edch termo\u010dl\u00e1nky v pec\u00edch jsou praktick\u00fdmi prom\u011bnn\u00fdmi \u010distota materi\u00e1lu, hustota a vystaven\u00ed alkalick\u00fdm par\u00e1m oproti p\u0159\u00edm\u00e9mu kontaktu se sklem. V\u00fdkonnost skla pl\u00e1\u0161t\u011b termo\u010dl\u00e1nku z oxidu hlinit\u00e9ho ve srovn\u00e1n\u00ed se sklem z karbidu k\u0159em\u00edku (SiC) se potvrzuje m\u011b\u0159en\u00edm \u00fabytku tlou\u0161\u0165ky st\u011bny a doby odezvy za stejn\u00fdch podm\u00ednek v peci, nikoli pouze na z\u00e1klad\u011b laboratorn\u00edch \u00fadaj\u016f o korozi. \u017divotnost trubice termo\u010dl\u00e1nku v roztaven\u00e9m skle se prodlu\u017euje, pokud materi\u00e1l odol\u00e1v\u00e1 jak chemick\u00e9mu p\u016fsoben\u00ed, tak tepeln\u00e9mu \u0161oku p\u0159i provozn\u00ed teplot\u011b. Pokud doch\u00e1z\u00ed k odchylk\u00e1m nam\u011b\u0159en\u00fdch hodnot nebo k p\u0159ed\u010dasn\u00e9mu selh\u00e1n\u00ed trubek, potvrzuj\u00edc\u00edm d\u016fkazem jsou m\u011b\u0159en\u00ed tlou\u0161\u0165ky st\u011bny a pozorovan\u00e9 \u010dasov\u00e9 zpo\u017ed\u011bn\u00ed b\u011bhem zn\u00e1m\u00e9 zm\u011bny teploty. Volba trubice s vy\u0161\u0161\u00ed vodivost\u00ed a dostate\u010dnou odolnost\u00ed proti korozi, jak dokl\u00e1d\u00e1 sn\u00ed\u017een\u00ed \u00fabytku tlou\u0161\u0165ky st\u011bny z 1,2 mm na 0,7 mm a zkr\u00e1cen\u00ed \u010dasov\u00e9 konstanty z 45 s na 28 s v porovn\u00e1n\u00ed korunov\u00fdch \u010d\u00e1st\u00ed, zlep\u0161uje jak odezvu m\u011b\u0159en\u00ed, tak \u017eivotnost p\u0159i provozu ve skl\u00e1\u0159sk\u00e9 peci.<\/p>","protected":false},"excerpt":{"rendered":"<p>Why Thermocouple Protection Tubes Fail Early or Drift in Glass Furnaces After twelve years supporting glass melting operations, a repeated issue is that thermocouple readings gradually drift or the protection tube fails well before the scheduled campaign. The furnace temperature is stable and the thermocouple element is the correct type, yet the indicated temperature shifts&hellip;&nbsp;<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"off","neve_meta_content_width":70,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","ngg_post_thumbnail":0,"footnotes":""},"categories":[30],"tags":[],"class_list":["post-718","post","type-post","status-publish","format-standard","hentry","category-sic-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts\/718","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/comments?post=718"}],"version-history":[{"count":2,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts\/718\/revisions"}],"predecessor-version":[{"id":720,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts\/718\/revisions\/720"}],"wp:attachment":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/media?parent=718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/categories?post=718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/tags?post=718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}