Karakterizacija metalurškog i petrokemijskog koksa kao punila za anode u sustavu katodne zaštite

master's thesis

• Title (english): Characterization of metallurgical and petroleum coke as anode backfill in cathodic protection system
• Author: Dino Bubaš
• Mentor: Helena Otmačić Ćurković (mentor)
• Committee member: Helena Otmačić Ćurković (predsjednik povjerenstva)
• Committee member: Marijana Kraljić Roković (član povjerenstva)
• Committee member: Juraj Šipušić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-09-26, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Analysis, Synthesis and Management of Chemical Processes

Abstract

Cilj ovog rada je karakterizacija električnih svojstava dvije vrste koksa (metalurški i petrokemijski) različitog porijekla, te njihovih mješavina, sa svrhom usporedbe zaštitne djelotvornosti koksnog punila za inertne MMO anode u sustavu katodne zaštite s vanjskim izvorom struje. Metalurški koks (MET) je konačni produkt dobiven suhom destilacijom kamenog ugljena u anaerobnim uvjetima, tj. bez pristupa zraka, a petrokemijski koks (PET) se dobiva kao sporedni produkt rafinerijskog procesa toplinskog koksiranja teških ostataka nafte. Pripremljeni ispitni uzorci 100 % MET i 100 % PET koksa, te njihovih mješavina s različitim udjelima, 70 % MET – 30 % PET i 50 % MET – 50 % PET koksa su obloženi oko četiri MMO anode istih dimenzija i ukopani u zasebna anodna ležišta. Iz pojedinačnih anodnih ležišta anode su spojene s vanjskim izvorom struje, tj. s četiri spojene napojne stanice koje su održavale konstantnu prolaznu istosmjernu struju do anodnih ležišta, izazvavši posljedično različitu degradaciju koksnih punila oko MMO anoda. Rezultati ispitivanja su pokazali da najbolju djelotvornost zaštite za inertne anode u anodnom ležištu pruža koksno punilo sa 100 % udjelom PET koksa, budući da dvostruko smanjuje otpor rasprostiranja MMO anode s vremenom i dugoročno produljuje vijek trajanja anode, ali za 3,7x višu cijenu od koksnog punila sa 100 % udjelom MET koksa koji je udvostručio otpor rasprostiranja MMO anode u anodnom ležištu s vremenom mjerenja, te pokazao najslabije apsorpcijsko svojstvo upijanja vode iz tla. Nasuprot tome, izvrsno zaštitno hidroskopno svojstvo apsorpcije vode iz tla, odnosno, bolju otpornost na degradaciju uslijed konstantne prolazne istosmjerne struje, pokazalo je 100 % PET koks punilo prateći vremenske oscilacije u izmjerenim vrijednostima električne otpornosti tla, nudeći tako primarnu površinu za odvijanje anodne reakcije oksidacije C do CO ili CO2. Mješavine punila dvije vrste koksa s različitim udjelima: 50 % MET – 50 % PET i 70 % MET - 30 % PET koksa su pokazale električna svojstva obje vrste koksa, ali bolju djelotvornost zaštite MMO anode u anodnom ležištu je ipak pokazala mješavina s većim udjelom PET koksa.

Abstract (english)

The main purpose of this work is the characterization of electrical properties of two types of coke (metallurgical and petrochemical) of different origin and their mixtures for comparison of the coke coating filler efficiency for inert MMO anodes in the cathode protection system with external current source. Metallurgical coke (MET) is the final product obtained by dry distillation of coal in anaerobic conditions, that is without the access of air, and petrochemical coke (PET) is obtained as a secondary product of the rafinery process of heat coking of heavy petrolium residues. Prepared test samples of 100 % MET and 100 % PET coke and their mixtures with different proportions, 70 % MET - 30 % PET and 50 % MET - 50 % PET coke encased four MMO anodes of same dimensions and are buried in separate anode reservoirs. Anodes with an external source of current are connected from the individual anode deposits, that is with four connected power stations which mantained constant direct current to the anode reservoirs, causing the consequent degradations of coke fillers around the MMO anodes. The test results showed that the best protection efficiency for an inert anode in an anodised bed provides a coke filler with 100 % PET coke since it doubles the grounding resistance of an anode MMO over time and prolongs the longevity of the anode, but at a 3.7x higher price than coke fillers with 100 % MET coke content, which doubled the grounding resistance of the MMO anode in the anode reservoir with the time of measurement and showed the lowest absorption of soil water. In contrast, the high water absorption from the ground, i.e., better resistance to degradation due to the constant transient direct current, showed 100 % PET coke filler following the time oscillation in the measured electrical resistance of the soil, thus providing a primary surface for conducting the anode oxidation reaction C to CO or CO2. Mixed fills of two types of coke: 50 % MET - 50 % PET and 70 % MET - 30 % PET coke showed the electrical properties of both types of coke, but improved efficacy of the MMO anode protection in the anode reservoir has nevertheless shown a mixture with a higher proportion of PET coke.

• Keywords: katodna zaštita; metalurški koks; petrokemijski koks; punilo za MMO anode
• Keywords (english): cathodic protection; metallurgical coke; petrochemical coke; MMO anodes filler
• Language: croatian
• URN:NBN: urn:nbn:hr:149:540015
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-04-23 13:47:42