Fluidized Bed Combustion Waste Research Articles

Enhancement of selectivity toward ettringite during hydrothermal processes on fluidized bed combustion wastes for the manufacture of preformed building components

This advance is concerned with reactivity improvements of hydrating systems, based on fluidized bed combustion wastes, toward ettringite.

Study of the hydrothermal treatments of residues from fluidized bed combustors for the manufacture of ettringite-based building elements

Fluidized bed combustion (FBC) waste is generally unsuitable for making ordinary cements and concretes, and its alternative uses are therefore worthy of consideration. In the present work, FBC waste is investigated as a potentially suitable single raw material for the manufacture of building components based on ettringite, a compound characterized by low density, high fire resistance, significant mechanical strength and usefulness as the main component of preformed lightweight building materials. The hydration behaviour of two FBC waste samples (a fly and a bottom ash) was explored within curing periods comprised between 2 and 24h at 55°C, 70°C and 85°C. X-ray diffraction and differential thermal analysis were employed as main experimental techniques in order to evaluate the distribution of the hydration products. The role of the raw ash chemical and mineralogical composition, operating temperature and time in the ettringite formation was highlighted. The fly ash was more prone to generate ettringite which, after 2h-curing time, tended to form and decompose earlier, as the curing temperature and time were further increased. The selectivity of the reactants toward ettringite can be enhanced by the addition of blending components.

Impact of fluidized bed combustion waste on metal content of crops and soil

The fluidized bed combustion process for removing SO2 from coal-fired power plant stack gases results in generation of large tonnages of waste requiring environmentally acceptable storage or disposal. A field study was initiated in fall 1985 to determine limits of fluidized bed combustion waste (FBCW) applications to agronomic crops without causing significant yield reduction or accumulation of heavy metals in plants or the soil. Rates of FBW ranging from 22 to 560 t ha−1 were incorporated in soil by plowing down single and split applications. Conventional agricultural lime treatments were included for comparison. Tall fescue (Festuca arundinacea), alfalfa (Medicago sativa L.), corn (Zea mays L.), and soybeans (Glycine max. L.) were grown from 1986–88. Annual applications of 22 t ha−1 did not affect yield or metal uptake of any test crop. A single 112 t ha−1 application had no adverse effect, but repeated applications of that rate lowered corn and soybean yields. The rate of 560 t ha−1 resulted in depressed or eliminated growth of all crops. A high pH and high concentrations of Ca and S were associated with this rate but heavy metals and B concentrations in soil and plant tissue were not significantly affected.

The Uses and Morphology of Atmospheric Fluidized Bed Combustion Wastes From Canada’s First Industrial AFBC Boilers

The literature of FBC solid wastes has been critically evaluated and solid wastes from Canada’s first atmospheric fluidized bed combustion (AFBC) boilers at the Canadian Forces Base (CFB) Summerside, Prince Edward Island have been investigated in order to determine possible uses for AFBC wastes. Scanning electron microscopy (SEM), electron microprobe, and chemical and physical tests were employed to determine the suitability of the material for pollution control, construction, and other uses. SEM and ancillary techniques have shown that the chemical and physical properties of the bed material and the elutriated streams are significantly different. Agricultural use, pollution control, soil stabilization (where freezing and thawing are not significant problems), asphaltic concrete, and specialized construction applications such as low strength backfill appear to be potential uses for FBC solid wastes.

Alfalfa and corn response to sulfur fertilization on three Pennsylvania soils

Abstract Sulfur deficiencies have become more widespread throughout the United States as a result of: (a) reduced SO2 emissions, (b) the use of high analysis fertilizers that contain less S, and (c) reduced applications of animal waste on cropland. The S status of Pennsylvania soils is not known. Studies were conducted at three locations in Pennsylvania under different soil and climatic conditions to determine crop response to S applications. The experimental sites were on a Hagerstown silt loam (Typic Hapludalf), a Gilpin channery silt loam (Typic Hapludult), and a Morrison sandy loam (Ultic Hapludalf) at Landisville, Rector, and Zion, Pa., respectively. Two S materials, elemental S and fluidized bed combustion waste material (FBM), were applied annually to alfalfa and corn at three rates of application: 34, 67, and 134 kg S/ha, with appropriate controls. Elemental S plus CaO treatment was applied to alfalfa at the same three rates. Two levels of N were used in the corn trials, 112 and 224 kg N/ha. The e...

Utilization of Fluidized Bed Combustion Wastes

Abstract Atmospheric fluidized bed (AFB) combustion appears to be a promising means for producing energy from high sulfur coal in an environmentally acceptable manner. The process involves burning crushed coal in a bed of limestone or dolomite that has been fluidized by jets of hot air. The resultant by-products are a dry, sand-size spent bed residue and a relatively high carbon fly ash. This discussion focuses on possible uses for this material, the spent bed residue. The paper is a progress report for a research program sponsored by the U.S. Department of Energy to evaluate potential commercial applications for fluidized bed combustion wastes. Included in the paper are laboratory data related to seven separate residue sources; a discussion of promising approaches to beneficiation; and supporting data on several potential applications involving the use of the relatively high calcium content of the material as a lime substitute or in the form of a cementitious structural product. Specific applications include stabilized road base compositions, masonry block, artificial reefs, partial replacement for portland cement, synthetic aggregate, flue gas desulfurization, neutralization of acid mine drainage, and treatment of industrial trade wastes. Also briefly discussed are efforts to evaluate the environmental impact of AFB waste disposal.

Effects of Fluidized Bed Combustion Waste on the Ca, Mg, S, and Zn Levels in Red Clover, Tall Fescue, Oat, and Buckwheat1

AbstractFluidized bed combustion, a desulfurization process for coal‐fired power plants, produces a waste that contains large amounts of calcium oxide and calcium sulfate. Since approximately 200 kg of fluidized bed combustion waste (FBCW) is generated per metric ton of coal burned, it represents a significant potential source of lime that must be evaluated before it can be properly utilized. In this study, FBCW was compared with calcium hydroxide as a lime source in a greenhouse study with red clover, tall fescue, oat, and buckwheat. The FBCW and calcium hydroxide were applied at rates calculated to adjust the pH of Westmoreland silt loam (Ultic Hapludalf, mixed, mesic) to 5.0, 5.5, 6.0, and 6.5. Though the loading rates from FBCW were higher than those from calcium hydroxide, FBCW treatments increased Ca levels more than did calcium hydroxide only in red clover. Only dry matter yields of buckwheat were higher for FBCW than for calcium hydroxide applications. All species showed higher FBCW‐induced Mg and S increases than hydrated lime. In spite of the Zn loading, Zn levels in herbage decreased as the pH levels increased as a result of FBCW application. Soil pH increases in FBCW and Calcium hydroxide treatments were comparable when the materials were applied in equivalent amounts. It was concluded that FBCW may be valuable as a lime, Mg, or S source when the effects of heavy metals in the material are evaluated.

Solute Movement from Fluidized Bed Combustion Waste in Acid Soil and Mine Spoil Columns

AbstractFluidized bed combustion waste (FBCW), a by‐product from a specialized coal‐fired power plant, was used as a liming source to determine its impact on solute transport in the soil. The upper 10 cm of 60‐cm‐long acid silt loam soil (pH 4.6) and strip mine spoil (pH 4.1) columns was treated with enough FBCW to raise the pH of the two media to 5.0 and 6.0, and 4.6 and 6.0, respectively. Loadings of Ca, S, and Mg in the upper 10 cm of the pH 6 mine spoil treated were 1,132, 309, and 46 µg/g soil, respectively. Approximately twice these loadings were applied to the upper 10 cm of the acid soil columns. Heavy metal loading rates were very low in all treatments. Columns were leached with 10 cm of water at 10‐day intervals 7 and 14 times. Percolate samples collected from mine spoil columns treated with FBCW showed no evidence of enhanced levels of Al, B, Ca, Cd, Cr, F−, Cu, Fe, Mg, Mn, Ni, P, Pb, SO42‐, Sr, and Zn after 14 leachings. Acid soil columns, containing higher levels of organic matter, had percolate concentrations of Ca, Mg, Mn, and SO42‐ that increased with increasing FBCW liming applications. None of the analyzed constituents showed any evidence of downward migration in mine spoil matrix and only Ca moved downward into the 10‐ to 15‐cm depth of the soil matrix.