Sources of unburned carbon in the fly ash produced from low-NOx pulverized coal combustion

Journal ArticleThe unburned carbon in the fly ash produced from low-NOx pulverized coal combustion is shown to consist of a mixture of soot and coal char. The soot was identified by the presence of chains or aggregates of 10-50-nm-diameter primary particles in electron microscope images of both laboratory samples and a sample of fly ash from a power plant operating low-NOx burners. Laboratory samples showed increasing carbon content with decreasing nitrogen oxide (NOx) concentration. The experiments included a high-NOx base case and four low-NOx cases consisting of (1) staged combustion with short (0.5 s) residence time, (2) staged combustion with long (1.5 s) residence time, (3) a low-NOx burner with slow mixing, and (4) reburning using coal as the reburning fuel. Comparison of the base case that used premixed coal and air with the long-residence-time staged combustion case shows a decrease in the NOx from over 900 ppm to below 200 ppm and an increase in the carbon in the ash from 4% to over 30%. The fly ash from staged combustion was a mixture of large soot aggregates, porous char, and spherical particles of mineral ash, whereas the ash from reburning lacked the large aggregates. For all laboratory conditions, the carbon content in the particle fraction with an aerodynamic diameter over 10 lm was higher than in the 1-2.5- lm-diameter fraction. Both soot aggregates and char contributed to the high carbon in the large particle fraction. The difference in carbon burnout between the two staging conditions was consistent with published soot oxidation rates. Both char burnout and soot formation need to be considered in studies of the carbon content of pulverized coal fly ash

A Preliminary Study on Ensiling Aspen Bark

A preliminary study was conducted on the ensiling of aspen bark in laboratory silos for the production of animal food. Several types of silo, both with and without an enzyme preparation, were tested. Results of physical and chemical tests on the contents indicate that definite changes occur when bark is ensiled, and that these changes differ with ensiling conditions. Several of these changes suggest possibilities for future research

A novel method to detect unlabeled inorganic nanoparticles and submicron particles in tissue by sedimentation field-flow fractionation

A novel methodology to detect unlabeled inorganic nanoparticles was experimentally demonstrated using a mixture of nano-sized (70 nm) and submicron (250 nm) silicon dioxide particles added to mammalian tissue. The size and concentration of environmentally relevant inorganic particles in a tissue sample can be determined by a procedure consisting of matrix digestion, particle recovery by centrifugation, size separation by sedimentation field-flow fractionation (SdFFF), and detection by light scattering

Water-COLOR: Water-COnservation using a Learning-based Optimized Recommender

Efficient water use, particularly in the realm of irrigation, has emerged as a critical concern in regions suffering from persistent drought, such as California and Florida. With the advent of smart irrigation controllers encouraged by environmental policies, a new paradigm of water management is gaining traction. Among these, the Rachio smart controller has garnered significant attention. However, without direct feedback or actual water usage data, optimizing these irrigation systems for enhanced efficiency remains challenging. This paper introduces Water-COLOR, a novel recommendation system integrated within the Rachio smart controller's framework to address this challenge. The system leverages similar landscape profiles to suggest irrigation schedules that are both water-efficient and user-preferable. By analyzing manual user interactions with the controller, Water-COLOR infers user satisfaction, which, along with estimated water usage, informs the adaptation of irrigation plans. The system eschews the need for additional sensors, thereby reducing infrastructure requirements. Our evaluation demonstrates consistent performance across diverse climatic regions and indicates that the system's recommendations could significantly contribute to water conservation efforts. The results not only showcase the potential of Water-COLOR to enhance the efficiency of existing smart irrigation systems but also open avenues for deploying real-time, data-driven environmental solutions

Correlation of in Vitro Cytokine Responses with the Chemical Composition of Soil-Derived Particulate Matter

We treated human lung epithelial cells, type BEAS-2B, with 10–80 μg/cm(2) of dust from soils and road surfaces in the western United States that contained particulate matter (PM) < 2.5 μm aerodynamic diameter. Cell viability and cytokine secretion responses were measured at 24 hr. Each dust sample is a complex mixture containing particles from different minerals mixed with biogenic and anthropogenic materials. We determined the particle chemical composition using methods based on the U.S. Environmental Protection Agency Speciation Trends Network (STN) and the National Park Service Interagency Monitoring of Protected Visual Environments (IMPROVE) network. The functionally defined carbon fractions reported by the ambient monitoring networks have not been widely used for toxicology studies. The soil-derived PM(2.5) from different sites showed a wide range of potency for inducing the release of the proinflammatory cytokines interleukin-6 (IL-6) and IL-8 in vitro. Univariate regression and multivariate redundancy analysis were used to test for correlation of viability and cytokine release with the concentrations of 40 elements, 7 ions, and 8 carbon fractions. The particles showed positive correlation between IL-6 release and the elemental and pyrolyzable carbon fractions, and the strongest correlation involving crustal elements was between IL-6 release and the aluminum:silicon ratio. The observed correlations between low-volatility organic components of soil- and road-derived dusts and the cytokine release by BEAS-2B cells are relevant for investigation of mechanisms linking specific air pollution particle types with the initiating events leading to airway inflammation in sensitive populations

Impact of Anthropogenic Combustion Emissions on The Fractional Solubility of Aeroosol Iron: Evidence From The Sargasso Sea

We report empirical estimates of the fractional solubility of aerosol iron over the Sargasso Sea during periods characterized by high concentrations of Saharan dust (summer 2003) and by low concentrations of aerosols in North American/maritime North Atlantic air masses (spring 2004 and early summer 2004). We observed a strong inverse relationship between the operational solubility of aerosol iron (defined using a flow-through deionized-water leaching protocol) and the total concentration of aerosol iron, whereby the operational solubility of aerosol iron was elevated when total aerosol iron loadings were low. This relationship is consistent with source-dependent differences in the solubility characteristics of our aerosol samples and can be described by a simple mixing model, wherein bulk aerosols represent a conservative mixture of two air mass end-members that carry different aerosol types: Saharan air,\u27\u27 which contains a relatively high loading of aerosol iron (27.8 nmol Fe m-3) that has a low fractional solubility (0.44%), and North American air,\u27\u27 which contains a relatively low concentration of aerosol iron (0.5 nmol Fe m-3) that has a high fractional solubility (19%). Historical data for aerosols collected on Bermuda indicate that the low iron loadings associated with North American air masses are typically accompanied by elevated V/Al, Fe/Al, and V/Mn mass ratios in the bulk aerosol, relative to Saharan dust, which are indicative of anthropogenic fuel-combustion products. The identification of similar compositional trends in our Sargasso Sea aerosol samples leads us to suggest that the elevated solubility of iron in the aerosols associated with North American air masses reflects the presence of anthropogenic combustion products, which contain iron that is readily soluble relative to iron in Saharan soil dust. We thus propose that the source-dependent composition of aerosol particles (specifically, the relative proportion of anthropogenic combustion products) is a primary determinant for the fractional solubility of aerosol iron over the Sargasso Sea. This hypothesis implies that anthropogenic combustion emissions could play a significant role in determining the atmospheric input of soluble iron to the surface ocean

Signal Processing

Contains reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E