Musa Karakus

Cathodoluminescence microscopy characterization of chrome-free refractories for copper smelting and converting furnaces

The results of an experimental program assessing the potential of several chrome‐free refractory materials as potential replacements for the mag‐chrome brick currently used in copper production furnaces are presented. Several commercial chrome‐free bricks were subjected to the standard dip test in a high‐copper calcium ferrite slag. The mineralogical changes in the bricks resulting from their interaction with the molten slag are described. The use of optical cathodoluminescence microscopy as an analytical tool is highlighted, along with reflected light microscopy and scanning electron microscopy–energy dispersive spectroscopy. Using the three tools together provides a description of the experimental results not achievable using one or two alone. The penetration resistance of the potential replacement refractories is comparable to that of mag‐chrome, but the substitution of Fe2+ for Mg2+ in the periclase and spinel crystalline structures of the replacements reduces their corrosion resistance compared with mag‐chrome, diminishing the likelihood that they will serve as reliable alternatives.

Refractory for Black Liquor Gasifiers

The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industrys environmental impact while increasing its potential for energy production, allowing the production of all the mills heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective surfaces in-situ; are functionally-graded to give the best combination of thermal, mechanical, and physical properties and chemical stability; or are relatively inexpensive, reliable repair materials. Material development will be divided into 2 tasks: Task 1, Development and property determinations of improved and existing refractory systems for black liquor containment. Refractory systems of interest include magnesium aluminate and barium aluminate for binder materials, both dry and hydratable, and materials with high alumina contents, 85-95 wt%, aluminum oxide, 5.0-15.0 wt%, and BaO, SrO, CaO, ZrO{sub 2} and SiC. Task 2, Finite element analysis of heat flow and thermal stress/strain in the refractory lining and steel shell of existing and proposed vessel designs. Stress and strain due to thermal and chemical expansion has been observed to be detrimental to the lifespan of existing black liquor gasifiers. The thermal and chemical strain as well as corrosion rates must be accounted for in order to predict the lifetime of the gasifier containment materials.

REFRACTORY FOR BLACK LIQUOR GASIFIERS

The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industrys environmental impact while increasing its potential for energy production, allowing the production of all the mills heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective surfaces in-situ; are functionally-graded to give the best combination of thermal, mechanical, and physical properties and chemical stability; or are relatively inexpensive, reliable repair materials. This report covers Task 1.3, Simulative corrosion of candidate materials developed by refractory producers and in the laboratory based on the results of Task 1.1 and Task 1.2. Refractories provided by in-kind sponsors were tested by cup testing, density/porosity determinations, chemical analysis and microscopy. The best performing materials in the cup testing were fused cast materials. However, 2 castables appear to outperforming any of the previously tested materials and may perform better than the fused cast materials in operation. The basis of the high performance of these materials is the low open porosity and permeability to black liquor smelt.

Characterization and testing of refractories for glass tank melters

Metas para pesquisas em andamento e futuras em nosso laboratorio incluem o estudo de ataque quimico em refratarios em contacto com vidro, bem como os refratarios da abobada de tanques de fusao de vidro sob condicoes de queima gas/ar ou oleo/oxigenio. Enfase em avaliacao e caracterizacao de parâmetros criticos serao considerados em refratarios comerciais, tais como microestrutura, porosidade e propriedades mecânicas. Um segundo foco e a avaliacao do desempenho de refratarios alternativos as abobodas tradicionais e refratarios de superestruturas, incluindo seus aspectos fisicos, desenho de aboboda e qualidade de juntas.