45 research outputs found

    Title: Refractory for Black Liquor Gasifiers Type of Report: Topical Report Task 1.4 Reporting Period Start Date

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    ABSTRACT 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 lowpressure 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 industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's 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 Task1.4, Industrial Trial of candidate materials developed by refractory producers and in the laboratory based on the results of Task 1.1, 1.2 and 1.3. Refractories provided by in-kind sponsors to industrial installations tested by cup testing, density/porosity determinations, chemical analysis and microscopy. None of the materials produced in this program have been trialed in high temperature gasifiers, but the mortar developed Morcocoat SP-P is outperforming other mortars tested at ORNL. MORCO PhosGun M-90-O has shown in laboratory testing to be an acceptable candidate for hot and cold repairs of existing high temperature gasifiers. It may prove to be an acceptable lining material

    Host selection by an insect herbivore with spatially variable density dependence

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    Many species of phytophagous insects do not oviposit preferentially on plants that yield high offspring performance. One proposed explanation is that negatively density-dependent offspring performance would select for females that disperse eggs among plants to minimize competition. Recent work showing larval density dependence often varies substantially among plants suggests that ovipositing females should not only respond to the density of competitors but also to traits predictive of the strength of density dependence mediated by plants. In this study, we used field and greenhouse experiments to examine oviposition behavior in an insect herbivore that experiences density-dependent larval performance and variability in the strength of that density dependence among host-plant individuals. We found females moved readily among plants in the field and had strong preferences for plants that mediate weak offspring density dependence. Females, however, did not avoid plants with high densities of competitors, despite the fact that offspring performance declines steeply with density on most plants in natural populations. This means females minimize the effects of density dependence on their offspring by choosing plants that mediate only weak larval density dependence, not by choosing plants with low densities of competitors. Our results suggest that explaining the lack of positive preference-performance correlations in many systems may not be as simple as invoking density dependence. Resource selection behavior may depend not just on the presence or absence of density-dependent offspring performance but also on variation in the strength of offspring density dependence among sites within populations

    Entrepreneurs, Firms and Global Wealth Since 1850

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    Title: Refractory for Black Liquor Gasifiers Type of Report: Quarterly Report Reporting Period Start

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    ABSTRACT 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 materials problems encountered during the operation of low-pressure high-temperature (LFHT) and lowpressure 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 industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's 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 magnesia aluminate and baria aluminate spinels 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 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
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