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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Correlation between the critical viscosity and ash fusion temperatures of coal gasifier ashes

Coal gasification yields synthesis gas, an important intermediate in chemical manufacturing. It is also vital to the production of liquid fuels through the Fischer-Tropsch process and electricity in Integrated Gasification Combined Cycle power generation. Minerals naturally present in coal become molten in entrained-flow slagging gasifiers. Molten coal ash slag penetrates and dissolves refractory bricks, leading to costly plant shutdowns. The extent of coal ash slag penetration and refractory brick dissolution depends on the slag viscosity, the gasification temperature, and the composition of slag and bricks. We measured the viscosity of several synthetic coal ash slags with a high-temperature rotary viscometer and their ash fusion temperatures through optical image analysis. All measurements were made in a carbon monoxide-carbon dioxide reducing atmosphere that approximates coal gasification conditions. Empirical correlation models based on ash fusion temperatures were used to calculate critical viscosity temperatures based on the coal ash compositions. These values were then compared with those obtained from thermodynamic phase-transition models. An understanding of slag viscosity as a function of ash composition is important to reducing refractory wear in slagging coal gasifiers, which would help to reduce the cost and environmental impact of coal for chemical and electricity production.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

Bio-based PA5.10 for Industrial Applications: Improvement of Barrier and Thermo-mechanical Properties with Rice Husk Ash and Nanoclay

Composites consisting of renewable PA5.10 were obtained from melt compounding with a modified clay (CL) and/or a by-product obtained from the combustion of rice husk (RHA). Two different industrialized lab-scale machines were used to obtain the final shape: a film extrusion machine and an injection moulding apparatus. The industrial application requirements for polyamides generally need good barrier properties and high thermo-mechanical strength. Considering the barrier properties, the CL was able to decrease the oxygen permeability to less than half with respect to neat PA5.10. DMTA demonstrated that the addition of RHA caused a consistent enhancement (+ 46 °C) in the heat deflection temperature (HDT) compared to the neat PA5.10 matrix, increasing the possible areas of interest. Furthermore, the simultaneous presence of RHA and CL provided the best result reaching an extraordinary HDT of 131 °C. A complete discussion taking into account the morphology, crystallinity and filler-matrix adhesion evaluation was reported as well as comparison of performances with other bio-PAs composites. These two fillers can therefore be used separated or together combined in PA5.10 for functional purposes in a sustainable scenario.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Simulated fireside corrosion of T91 in oxy-combustion systems with an emphasis on coal/biomass environments

Oxy-combustion is the burning of a fuel in oxygen rather than air for the ease of capture of CO2 for reuse or sequestration. Corrosion issues associated with the change in heat exchanger tube operating environment (replacement of most of the N 2 with CO 2 and potentially higher SO x levels) from air- to oxy-combustion were examined. The ferritic-martensitic alloy T91 was used in accelerated fireside corrosion tests using several different gas compositions and ash deposit overcoats to simulate air-fired, oxy-fired coal, and oxy-fired co-fired coal/biomass conditions. Initial corrosion was observed after 240 h of exposure by examining cross-sections with retained ash. Metal section losses were determined after exposures of up to 1440 h at 600-700 °C. Severe corrosion was observed, and a corrosion response with respect to ash deposit chemistry was observed. Corrosion response differences with respect to gas phase chemistry were minimal. Alloy-oxide scale-ash morphologies were consistent with oxide fluxing mechanisms.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2015

Integrated Waste Treatment Unit (IWTU) Input Coal Analyses and Off-Gass Filter (OGF) Content Analyses

A full engineering scale Fluidized Bed Steam Reformer (FBSR) system is being used at the Idaho Nuclear Technology and Engineering Center (INTEC) to stabilize acidic Low Activity Waste (LAW) known as Sodium Bearing Waste (SBW). The INTEC facility, known as the Integrated Waste Treatment Unit (IWTU), underwent an Operational Readiness Review (ORR) and a Technology Readiness Assessment (TRA) in March 2014. The IWTU began non-radioactive simulant processing in late 2014 and by January, 2015 ; the IWTU had processed 62,000 gallons of simulant. The facility is currently in a planned outage for inspection of the equipment and will resume processing simulated waste feed before commencing to process 900,000 gallons of radioactive SBW. The SBW acidic waste will be made into a granular FBSR product (carbonate based) for disposal in the Waste Isolation Pilot Plant (WIPP). In the FBSR process calcined coal is used to create a CO2 fugacity to force the waste species to convert to carbonate species. The quality of the coal, which is a feed input, is important because the reactivity, moisture, and volatiles (C,H,N,O, and S) in the coal impact the reactions and control of the mineralizing process in the primary steam reforming vessel, the Denitration and Mineralizing Reformer (DMR). Too much moisture in the coal can require that additional coal be used. However since moisture in the coal is only a small fraction of the moisture from the fluidizing steam this can be self-correcting. If the coal reactivity or heating value is too low then the coal feed-rate needs to be adjusted to achieve the desired heat generation. Too little coal and autothermal heat generation in the DMR cannot be sustained and/or the carbon dioxide fugacity will be too low to create the desired carbonate mineral species. Too much coal and excess S and hydroxide species can form. Excess sulfur from coal that (1) is too rich in sulfur or (2) from overfeeding coal can promote wall scale and contribute to corrosion in process piping and materials, in excessive off-gas absorbent loading, and in undesired process emissions. The ash content of the coal is important as the ash adds to the DMR and other vessel products which affect the final waste product mass and composition. The amount and composition of the ash also affects the reaction kinetics. Thus ash content and composition contributes to the mass balance. In addition, sodium, potassium, calcium, sulfur, and maybe silica and alumina in the ash may contribute to wall-scale formation. Sodium, potassium, and alumina in the ash will be overwhelmed by the sodium, potassium, and alumina from the feed but the impact from the other ash components needs to be quantified. A maximum coal particle size is specified so the feed system does not plug and a minimum particle size is specified to prevent excess elutriation from the DMR to the Process Gas Filter (PGF). A vendor specification was used to procure the calcined coal for IWTU processing. While the vendor supplied a composite analysis for the 22 tons of coal (Appendix A), this study compares independent analyses of the coal performed at the Savannah River National Laboratory (SRNL) and at the National Energy Technology Laboratory (NETL). Three supersacks a were sampled at three different heights within the sack in order to determine within bag variability and between bag variability of the coal. These analyses were also compared to the vendor’s composite analyses and to the coal specification. These analyses were also compared to historic data on Bestac coal analyses that had been performed at Hazen Research Inc. (HRI) between 2004-2011.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Mechanical Properties of Aluminum Matrix Composite Reinforced by Carbothermally Reduced of Fly Ash

The addition of fly ash into aluminum as reinforcement can potentially reduce the production cost and density of aluminum. However, mechanical properties of aluminum matrix composite reinforced by fly ash (MMC ALFA) have some limitations due to the characteristic of fly ash. In this study, a carbothermal reduction process of fly ash and activated carbon powder with particle size <32 {mu}m was performed prior to produce MMC ALFA.The process was carried out in a furnace at 1300 deg. C in vacuum condition under argon flow. Synthesis product was analyzed by XRD with Cu-K{sub {alpha}} radiation. From XRD analysis, it shows that the synthesis process can produce SiC powder. The synthesis product was subsequently used as reinforcement particle. Aluminum powder was mixed with 5, 10 and 15% of the synthesized powder, and then uni-axially compacted at pressure of 300 MPa. The compacted product was sintered for 2 hours in argon atmosphere at temperature variation of 550 and 600 deg. C. Flexural strength, hardness and density of MMC ALFA's product were respectively evaluated using a four point bending test method based on ASTM C1161 standard, Brinell hardness scale and Archimedes method. The result of this study shows that the increase of weight of reinforcement can significantly increase the hardness and flexural strength of MMCs. The highest hardness and flexural strength of the MMC product are 300 kg/mm{sup 2} and 107.5 MPa, respectively.

36 MATERIALS SCIENCE↗
NASA NTRS1974

An atlas of volcanic ash

Volcanic ash samples collected from a variety of recent eruptions were studied, using petrography, chemical analyses, and scanning electron microscopy to characterize each ash type and to relate ash morphology to magma composition and eruption type. The ashes are best placed into two broad genetic categories: magnetic and hydrovolcanic (phreatomagmatic). Ashes from magmatic eruptions are formed when expanding gases in the magma form a froth that loses its coherence as it approaches the ground surface. During hydrovolcanic eruptions, the magma is chilled on contact with ground or surface waters, resulting in violent steam eruptions. Within these two genetic categories, ashes from different magma types can be characterized. The pigeon hole classification used here is for convenience; there are eruptions which are driven by both phreatic and magmatic gases.

Heiken, G.↗
DOE OSTI2019

Spallation-altered Accreted Compositions for X-Ray Bursts: Impact on Ignition Conditions and Burst Ashes

Model predictions of X-ray burst ashes and light curves depend on the composition of the material accreted from the companion star, in particular the abundance of CNO elements. It has previously been pointed out that spallation in the atmosphere of the accreting neutron star can destroy heavy elements efficiently. In this work we study this spallation using a realistic reaction network that follows the complete spallation cascade and takes into account not only destruction, but also production of elements by the spallation of heavier species. We find an increased survival probability of heavier elements compared to previous studies, resulting in significantly higher CNO abundances.We provide resulting compositions as a function of accretion rate, and explore their impact on 1D multi-zone X-ray burst models. Finally, we find significant changes in the composition of the burst ashes, which will affect the thermal and compositional structure of accreted neutron star crusts.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

Controlled combustion tests and bottom ash analysis using household waste with varying composition

The influence of the co-combustion of household waste with either sewage sludge, shredder fluff, electronic and electrical waste (WEEE) or PVC on the bottom ash quality and content was investigated under controlled laboratory conditions using a pot furnace. This laboratory approach avoids the interpretation problems related to large variations in input waste composition and combustion conditions that are observed in large scale MSW incinerators. The data for metals content, transfer coefficients and leaching values are presented relative to data for a base household waste composition that did not contain any of the added special wastes. The small WEEE invited direct measurement of precious metals content in the ashes, where measurement accuracy is facilitated by using only mobile phone scrap for small WEEE. The analyses were carried out for different particle size ranges that are of relevance to the recyclability of metals and minerals in the ashes. Positive correlations were found between elements content of the input waste and the bottom ashes, and also between increased levels of Cl, Mo and Cu in the input waste and their leaching in the bottom ashes. These correlations indicate that addition of PVC, small WEEE and shredder fluff in input waste can have a negative influence on the quality of the bottom ashes. Enrichment of Au and Ag occurred in the fractions between 0.15 and 6 mm. The precious metals content represents an economically interesting intrinsic value, even when the observed peak values are properly averaged over a larger volume of ashes. Overall, it has been shown that changes in quality and content of bottom ashes may be traced back to the varied input waste composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Techno-economic analysis of biomass value-added processing informed by pilot scale de-ashing of paper sludge feedstock

Paper sludge biomass represents an underutilized feedstock rich in pulped and processed cellulose which is currently a waste stream with significant disposal cost to industry for landfilling services. Effective fractionation of the cellulose from paper sludge presents an opportunity to yield cellulose as feedstock for value-added processes. A novel approach to cellulose fractionation is the sidehill screening system, herein studied at the pilot-plant scale. Composition analysis determined ash removal and carbohydrate retention of both sidehill and high-performance benchtop screening systems. Sidehill screening resulted in greater carbohydrates retention relative to benchtop screening (90% vs 66%) and similar ash removal (95% vs 98%). Techno-economic analysis for production of sugar syrup yielded a minimum selling price of $331/metric ton of sugar syrup including disposal savings, significantly less than a commercial sugar syrup without fractionation. Furthermore, sensitivity analysis showed that screening conditions played a significant role in economic feasibility for cellulosic yield and downstream processes.

09 BIOMASS FUELS↗
DOE OSTI2010

Element associations in ash from waste combustion in fluidized bed

The incineration of MSW in fluidized beds is a commonly applied waste management practice. The composition of the ashes produced in a fluidized bed boiler has important environmental implications as potentially toxic trace elements may be associated with ash particles and it is therefore essential to determine the mechanisms controlling the association of trace elements to ash particles, including the role of major element composition. The research presented here uses micro-analytical techniques to study the distribution of major and trace elements and determine the importance of affinity-based binding mechanisms in separate cyclone ash particles from MSW combustion. Particle size and the occurrence of Ca and Fe were found to be important factors for the binding of trace elements to ash particles, but the binding largely depends on random associations based on the presence of a particle when trace elements condensate in the flue gas.

42 ENGINEERING↗
DOE OSTI2010

The importance of SO{sub 2} and SO{sub 3} for sulphation of gaseous KCl - An experimental investigation in a biomass fired CFB boiler

This paper is based on results obtained during co-combustion of wood pellets and straw in a 12 MW circulating fluidised bed (CFB) boiler. Elemental sulphur (S) and ammonium sulphate ((NH{sub 4}){sub 2}SO{sub 4}) were used as additives to convert the alkali chlorides (mainly KCl) to less corrosive alkali sulphates. Their performance was then evaluated using several measurement tools including, IACM (on-line measurements of gaseous alkali chlorides), a low-pressure impactor (particle size distribution and chemical composition of extracted fly ash particles), and deposit probes (chemical composition in deposits collected). The importance of the presence of either SO{sub 2} or SO{sub 3} for gas phase sulphation of KCl is also discussed. Ammonium sulphate performed significantly better than elemental sulphur. A more efficient sulphation of gaseous KCl was achieved with (NH{sub 4}){sub 2}SO{sub 4} even when the S/Cl molar ratio was less than half compared to sulphur. Thus the presence of gaseous SO{sub 3} is of greater importance than that of SO{sub 2} for the sulphation of gaseous KCl. (author)

09 BIOMASS FUELS↗
DOE OSTI2019

Radiative Properties of Coal Ash Deposits with Sintering Effects

The heat-transfer characteristics in the fireside of a pulverized-coal furnace are affected, among other factors, by the physical and chemical characteristics of the ash deposits. Indeed, the physical state of the ash deposits and their chemical composition determine the radiative and conductive properties of the furnace walls. Particularly, several complex mechanisms are involved in the radiative heat-transfer process at the walls that restricts the absorption of the incident radiation of the flame, particles, and hot gases. These mechanisms involve dependencies on the radiation spectrum due to the ash chemical composition and ash-sintering effects that enhance or hinder the overall heat transfer. In this work, the complex mechanisms that describe the heat exchange in the presence of ash deposits and their impact on the prediction of the wall emissivity and ultimately the wall heat transfer in a real system are discussed.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

Utilization of rice husk ash in green natural fiber-reinforced cement composites: Mitigating degradation of sisal fiber

This study aims to explore a novel approach to improve the durability of sisal fiber in cement composites by using by-products of biomass power plant: rice husk ash (RHA). The effects of two RHAs on the fiber's degradation were investigated indirectly by testing flexural behavior of sisal fiber-cement composite beams and directly by means of uniaxial tensile properties, thermal decomposition, crystallinity indices and microstructures of embedded fibers, after exploring up to 30 wetting and drying cycles. Allowing the distinction between pozzolanic activities, the efficiency of RHA was compared with two fly ashes and combinations of two clay minerals (metakaolin and nanoclay) with a cement substitution level of 30 wt.%. The durability of composites was improved considerably by incorporating RHA owing to the mitigation of fiber's degradation: the ultimate tensile strength and cellulose fraction of embedded fibers were improved by 384% and 45%, respectively. Fine RHA and the combination of metakaolin and nanoclay yield similar efficiency in mitigating degradation of sisal fiber, and are better than the coarse RHA and fly ashes. The correlations between cement hydration and sisal fiber degradation were analyzed. The results indicate that degree of hydration, calcium hydroxide content and alkalinity of the cement matrix play decisive roles in alkali attacks and mineralization of fiber's cell walls.

36 MATERIALS SCIENCE↗
NASA NTRS1996

Excess nutrients in hydroponic solutions alter nutrient content of rice, wheat, and potato

Environment has significant effects on the nutrient content of field-grown crop plants. Little is known, however, about compositional changes caused by controlled environments in which plants receive only artificial radiation and soilless, hydroponic culture. This knowledge is essential for developing a safe, nutritious diet in a Controlled Ecological Life-Support System (CELSS). Three crops that are candidates for inclusion in a CELSS (rice, wheat, and white potato) were grown both in the field and in controlled environments where the hydroponic nutrient solution, photosynthetic photon flux (PPF), and CO2 level were manipulated to achieve rapid growth rates. Plants were harvested at maturity, separated into discrete parts, and dried prior to analysis. Plant materials were analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate, minerals, and amino-acid composition. The effect of environment on nutrient content varied by crop and plant part. Total N and nonprotein N (NPN) contents of plant biomass generally increased under controlled-environment conditions compared to field conditions, especially for leafy plant parts and roots. Nitrate levels were increased in hydroponically-grown vegetative tissues, but nitrate was excluded from grains and tubers. Mineral content changes in plant tissue included increased phosphorus and decreased levels of certain micronutrient elements under controlled-environment conditions. These findings suggest that cultivar selection, genetic manipulation, and environmental control could be important to obtain highly nutritious biomass in a CELSS.

NASA Discipline Number 61-20↗