{"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":"preco-dochadza-k-predcasnemu-zlyhaniu-alebo-k-posunu-ochrannych-rurok-termoclankov-v-sklarskych-peciach","status":"publish","type":"post","link":"https:\/\/siliconcarbide.net\/sk\/why-thermocouple-protection-tubes-fail-early-or-drift-in-glass-furnaces\/","title":{"rendered":"Pre\u010do doch\u00e1dza k pred\u010dasn\u00e9mu zlyhaniu alebo posunu ochrann\u00fdch r\u00farok termo\u010dl\u00e1nkov v skl\u00e1rskych peciach"},"content":{"rendered":"<p dir=\"auto\"><strong>Pre\u010do doch\u00e1dza k pred\u010dasn\u00e9mu zlyhaniu alebo posunu ochrann\u00fdch r\u00farok termo\u010dl\u00e1nkov v skl\u00e1rskych peciach<\/strong><\/p>\n<p dir=\"auto\">Po dvan\u00e1stich rokoch prev\u00e1dzky v oblasti tavenia skla sa opakuje probl\u00e9m, \u017ee hodnoty z termo\u010dl\u00e1nkov sa postupne pos\u00favaj\u00fa alebo doch\u00e1dza k poruche ochrann\u00e9ho pl\u00e1\u0161\u0165a e\u0161te dlho pred pl\u00e1novan\u00fdm servisn\u00fdm z\u00e1sahom. Teplota v peci je stabiln\u00e1 a termo\u010dl\u00e1nok je spr\u00e1vneho typu, napriek tomu sa nameran\u00e1 teplota pos\u00fava o desiatky stup\u0148ov alebo sa pl\u00e1\u0161\u0165 praskne \u010di sten\u010d\u00ed v mieste styku so sklom alebo v spa\u013eovacej komore. Pr\u00ed\u010dinou s\u00fa r\u00fdchlos\u0165 kor\u00f3zie sp\u00f4soben\u00e1 v\u00fdparmi alk\u00e1li\u00ed alebo roztaven\u00fdm sklom a tepeln\u00e1 vodivos\u0165 materi\u00e1lu r\u00farky, ktor\u00e9 spolo\u010dne ur\u010duj\u00fa \u017eivotnos\u0165 aj oneskorenie teplotnej odozvy.<\/p>\n<p dir=\"auto\">Trubice z oxidu hlinit\u00e9ho (zvy\u010dajne 99 % Al\u2082O\u2083) v\u010faka svojej chemickej stabilite pomerne dobre odol\u00e1vaj\u00fa p\u00f4sobeniu roztaven\u00e9ho skla a v\u00fdparov alk\u00e1li\u00ed, maj\u00fa v\u0161ak stredn\u00fa tepeln\u00fa vodivos\u0165 (pribli\u017ene 25\u201330 W\/m\u00b7K) a obmedzen\u00fa odolnos\u0165 vo\u010di tepeln\u00fdm \u0161okom. Trubice z karbidu krem\u00edka, najm\u00e4 spekan\u00e9 alebo rekry\u0161talizovan\u00e9 typy, pon\u00fakaj\u00fa vy\u0161\u0161iu tepeln\u00fa vodivos\u0165 (\u010dasto 30\u201350 W\/m\u00b7K alebo viac) a lep\u0161iu odolnos\u0165 vo\u010di teplotn\u00fdm \u0161okom, \u010do zni\u017euje oneskorenie reakcie, av\u0161ak u niektor\u00fdch typov m\u00f4\u017ee doch\u00e1dza\u0165 k povrchovej oxid\u00e1cii alebo reakcii v silne alkalick\u00fdch atmosf\u00e9rach. Kor\u00f3zia prebieha reakciou oxidov alkalick\u00fdch kovov s povrchom r\u00farky, pri\u010dom sa vytv\u00e1ra vrstva s n\u00edzkou teplotou topenia, ktor\u00e1 sa pomaly rozp\u00fa\u0161\u0165a alebo odlupuje. V ponoren\u00fdch \u010dastiach je koroz\u00edvny \u00fa\u010dinok r\u00fdchlej\u0161\u00ed; v hornej \u010dasti alebo nadstavbe je koroz\u00edvny \u00fa\u010dinok sp\u00f4soben\u00fd kondenz\u00e1ciou pary. Zten\u010denie steny zvy\u0161uje riziko mechanick\u00e9ho zlyhania, zatia\u013e \u010do hrub\u00e1 stena alebo stena s n\u00edzkou tepelnou vodivos\u0165ou zvy\u0161uje \u010dasov\u00fa kon\u0161tantu merania.<\/p>\n<p dir=\"auto\">V peci na spracovanie sklenen\u00fdch n\u00e1dob, pracuj\u00facej pri teplote 1450\u20131500 \u00b0C, boli v hornej \u010dasti po dobu 90 dn\u00ed ved\u013ea seba in\u0161talovan\u00e9 dve ochrann\u00e9 r\u00farky s uzavret\u00fdmi koncami. Trubica z oxidu hlinit\u00e9ho (p\u00f4vodn\u00e1 hr\u00fabka steny 6 mm) vykazovala v najteplej\u0161ej z\u00f3ne priemern\u00e9 zten\u010denie 1,2 mm a nameran\u00fa \u010dasov\u00fa kon\u0161tantu pribli\u017ene 45 sek\u00fand pri zmene za\u0165a\u017eenia hor\u00e1ka. Trubica zo spekan\u00e9ho karbidu krem\u00edka (p\u00f4vodn\u00e1 hr\u00fabka steny 5 mm) vykazovala za rovnak\u00fdch podmienok zten\u010denie o 0,7 mm a \u010dasov\u00fa kon\u0161tantu pribli\u017ene 28 sek\u00fand. Na \u017eiadnej z trub\u00edc sa nevyskytli priechodn\u00e9 trhliny. Po demont\u00e1\u017ei mal povrch r\u00farky z oxidu hlinit\u00e9ho tenk\u00fa reak\u010dn\u00fa vrstvu obsahuj\u00facu sod\u00edk a drasl\u00edk; povrch r\u00farky z karbidu krem\u00edka mal tenk\u00fa vrstvu oxidu kremi\u010dit\u00e9ho s obmedzen\u00fdm prenikan\u00edm alkalick\u00fdch prvkov. Teplotn\u00e9 hodnoty z r\u00farky z karbidu krem\u00edka sledovali zmeny v procese presnej\u0161ie, zatia\u013e \u010do r\u00farka z oxidu hlinit\u00e9ho zaost\u00e1vala nato\u013eko, \u017ee si vy\u017eadovala v\u00e4\u010d\u0161iu m\u0155tvu z\u00f3nu regul\u00e1cie.<\/p>\n<p dir=\"auto\">Pri v\u00fdbere r\u00farky sa preto zoh\u013ead\u0148uje rovnov\u00e1ha medzi odolnos\u0165ou proti kor\u00f3zii, tepelnou vodivos\u0165ou a hr\u00fabkou steny pre konkr\u00e9tne miesto pou\u017eitia. Pokia\u013e ide o ochranu termo\u010dl\u00e1nkov v sklen\u00fdch r\u00farkach v peciach na spracovanie skla, praktick\u00fdmi premenn\u00fdmi s\u00fa \u010distota materi\u00e1lu, hustota a vystavenie par\u00e1m alk\u00e1li\u00ed v porovnan\u00ed s priamym kontaktom so sklom. V\u00fdkonnos\u0165 skla pl\u00e1\u0161\u0165a termo\u010dl\u00e1nku z oxidu hlinit\u00e9ho v porovnan\u00ed so sklom z karbidu krem\u00edka (SiC) sa potvrdzuje meran\u00edm \u00fabytku steny a doby odozvy za rovnak\u00fdch podmienok v peci, a nie len na z\u00e1klade laborat\u00f3rnych \u00fadajov o kor\u00f3zii. \u017divotnos\u0165 r\u00farky termo\u010dl\u00e1nku v roztavenom skle sa predl\u017euje, ak materi\u00e1l odol\u00e1va chemick\u00e9mu p\u00f4sobeniu aj teplotn\u00e9mu \u0161oku pri prev\u00e1dzkovej teplote. Ak doch\u00e1dza k odch\u00fdlkam v nameran\u00fdch hodnot\u00e1ch alebo k pred\u010dasn\u00e9mu zlyhaniu r\u00farok, potvrdzuj\u00facim d\u00f4kazom s\u00fa merania hr\u00fabky steny a pozorovan\u00e9 \u010dasov\u00e9 oneskorenie po\u010das zn\u00e1mej zmeny teploty. V\u00fdber trubice s vy\u0161\u0161ou vodivos\u0165ou a primeranou odolnos\u0165ou proti kor\u00f3zii, ako ukazuje zn\u00ed\u017eenie zten\u010denia z 1,2 mm na 0,7 mm a skr\u00e1tenie \u010dasovej kon\u0161tanty z 45 s na 28 s v porovnan\u00ed v hornej \u010dasti pece, zlep\u0161uje nielen r\u00fdchlos\u0165 odozvy merania, ale aj \u017eivotnos\u0165 pri prev\u00e1dzke v skl\u00e1rskej 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\/sk\/wp-json\/wp\/v2\/posts\/718","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/comments?post=718"}],"version-history":[{"count":2,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts\/718\/revisions"}],"predecessor-version":[{"id":720,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts\/718\/revisions\/720"}],"wp:attachment":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/media?parent=718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/categories?post=718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/tags?post=718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}