Refractory degradation in glass tank melters. A survey of testing methods

Abstract

INTRODUTIONThe major objective in glass tank melters is to optimize the entire process by reducing the maximum temperature of melting, improving refractory performance and/or improving melter fuel efficiency. The required characteristics of refractories used in melters are: thermal shock resistance, corrosion resistance, controlled expansion behavior, low thermal conductivity, and adequate creep resistance.The corrosion of the refractories in the melter may be due to batch carryover (lime, soda, fluorides, lead oxide, borax, silica, other glass constituents), volatile fluxes (i.e., volatile alkali oxides penetrating pores, where solid, liquid, and gas coexist), and melt attack, mainly at the metal line. Erosion often follows the initial corrosion, washing away refractory grains after the original bond has dissolved. Corrosion test designs are usually based on operation and reaction temperatures, reaction rates, and the formation of coatings on the refractory surface.Refractories for glass furnaces normally are limited to compositions based on A1 2 O 3 , ZrO 2 , and SiO 2 , with or without Cr 2 O 3 . Alumina-zirconia-silicate (AZS) refractories in contact with molten glass form a viscous silicate layer adjacent to the refractory thus restricting contact, and therefore, increasing corrosion resistance. When AZS blocks are used in superstructures, they are exposed to high temperature combustion products. At temperatures above 1475 0 C, the bond strength between the embedded ZrO 2 crystals and the alumina is reduced, attributed to the variation in the thermal expansion characteristics of A1 2 O 3 and ZrO 2 .Superstructure and crown refractories are subjected to corrosive reactions with the vapor species of the batch components and batch carryover. In the melting of soda-lime glasses, the vapor species are primarily soda and sodium sulfates; for borosilicate This work intends to summarize the tests to date, discussing their particular advantages, and emphasizing the corrosion of refractories in the melter tank. Most future melters are predicted to be under oxy-fuel combustion [1,2], with limited use of checkerwork refractories. BIBLIOGRAPHY SEARCH Corrosion resistance of refractories to molten slagsSeveral methods have been used to evaluate the dissolution rate of refractories, including (1) before and after profile measurements [i.e., 3-7]; (2) [19]. These laboratory corrosion tests compare corrosion characteristics, effectively measuring the chemical compatibility between glass and refractory.Bruckner [3] considered the different factors influencing the corrosion of refractories by commercial glasses. Given assumptions such as pure diffusion, entirely electrochemical processes and a AbstractThe degradation of refractories used in the construction of glass melting furnaces, whether caused by the action of molten glass, vaporized melt constituents, products of fuel combustion, or by batch dusts and vapors, can normally only be assessed after a campaign when the furnace is partially or completely disassembled. Corrosi...

Isothermal corrosion testing of frit furnace refractories

“…Temperature, time and type of refractory were varied in all experiments to observe their effects on corrosion of the refractory samples. The testing geometry used was similar to ASTM C-621, and can be found as dip/dip and rotation or finger test in the literature [6,9,10].…”

“…Time, temperature, and type of refractory were the only variables changed in all experiments in this study. It is important to remember that in commercial service, refractory bricks used in the lining of the frit furnace are exposed to other harsh effects; including thermal shock, and flow of the molten and alkali vapour, causing an increase in the corrosion of those materials during service [3,10].…”

“…A corrosion testing method and a test protocol for frit kiln refractories were produced by mimicking the conditions in the frit kiln application. Some previous experimental setups used in corrosion testing were investigated to guide this study [9][10][11][12][13][14]. Dip/dip and rotation test (finger, rotating pencil test) was thought to be suitable for determining corrosion behaviours under both static and dynamic conditions that involved stagnant and flowing molten frit attack on a refractory sample.…”

A comparison of the use of refractive index (RI) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for the provenance establishment of glass bottles

“…It is possible that small particles of furnace brick debris may break off from the furnace walls and roof and be incorporated into the glass melt, producing variations in the concentration of 90 Zr and 178 Hf throughout the melt. In addition, surface dissolution and corrosion of the furnace brick cladding by the glass melt will also occur, resulting in increases in zirconium and hafnium concentrations of the melt with respect to time [31]. Tin is a volatile element and is often utilized as part of a surface spray to coat newly produced bottles [32].…”

Corrosion behavior of ZrO2–SiO2–Al2O3 refractories in lead silicate glass melts

“…[1][2][3][4][5][6][7] The rate of corrosion reactions that may occur between the refractory and the liquid phase depends on the temperature of the glass melting tank, composition of the melt and porosity of the solid phase. Fused cast ZrO 2 -Al 2 O 3 -SiO 2 (ZAS) refractories are superior because of low porosity, interconnected corundum-baddeleyite particles and interstitial glassy phase.…”