By-product Of Coal-fired Power Plants Research Articles

CO2 adsorption by coal fly ash zeolite and modified zeolite-templated carbon

Coal fly ash (CFA), as the main by-product of coal-fired power plants, has a high content of silica-aluminium elements that can be used to prepare zeolite by the alkali fusion method with sound CO2 adsorption capacity. Among the four effect factors of Si/Al, NaOH/CFA, H2O/AFP(alkali fusion product), and crystallisation time, NaOH/CFA had the greatest effect on the CO2 adsorption performance of coal fly ash zeolite (CFAZ), followed by Si/Al and H2O/AFP, and crystallisation time had the least effect. The CO2 adsorption performance of the samples was tested and analysed using the thermal analysis method, the CO2 adsorption amount of CFAZ reached 4.23 mmol g–1 (30 °C, 101 kPa). In addition, the CFAZ and the zeolite-templated carbon (ZTC) adsorption performance is poor at high temperatures. The co-precipitation method modification of CFAZ and ZTC can produce layered double hydroxide derived material, which can adsorb CO2 at high temperatures reached at 3.35 mmol/g (650 °C, 101 kPa). Moreover, ZTC modified with polydivinylbenzene as the hydrophobic material has a sound CO2 adsorption effect in high-humidity environments. Thus, different adsorbents also could be produced using CFA to capture CO2 with a wide temperature range between 25 and 650 °C.

The Effect of Acid Treatment Time, Particle Size, and Synthesis Method on the Physical and Mechanical Properties of Dental Materials Produced from Flue Gas Desulfurization (FGD) Gypsum

FGD gypsum, a byproduct of coal-fired power plants, is readily available and relatively inexpensive, which makes it an ideal material for a variety of applications. This study considered the use of FGD gypsum as a substitute for natural gypsum in dental materials. The goal of this research was to investigate how acid treatment time, particle size, and the synthesis method impact the physical and mechanical properties of dental materials to be used in a dental study model for training in dental sciences, and for casting a gypsum model after the removal of the impression material from the patient's mouth. The study used various sulfuric acid treatment times (15, 30, and 60 min), particle sizes (less than 0.1 mm, 0.1-0.35 mm, and 0.4-0.45 mm), and synthesis methods (Method A for dental plaster and Method B for dental stone). From the results, an acid treatment time of 15 min was sufficient for removing impurities from the FGD gypsum while enhancing the compressive strength. The smaller particles provided higher compressive strength than the larger particles. FGD gypsum became lighter in color when treated with sulfuric acid, and the crystal structure had a rough and porous surface. The synthesis methods had a significant influence on the physical properties of dental gypsum. The increased alpha calcium sulfate hemihydrate (α-HH) phase content resulted in improved compressive strength. The gypsum synthesized using Method B exhibited the highest compressive strength due to the presence of the α-HH phase of 65.9%. While gypsum synthesized using Method A contained a α-HH phase of 58.9%. For further study, once the suitable conditions for synthesizing gypsum that meet the compressive strength requirements of the ISO standard for dental materials are achieved, there will be ongoing research and development to improve various properties. Additionally, practical applications will be considered, such as using it in conjunction with modern techniques such as 3D printing instead of traditional die-casting methods.

Effects of carrier particles on flotation removal of unburned carbon particles from fly ash

Fly ash, a major by-product of coal-fired power plants, contains unburned carbon which poses challenges to its effective utilization. The flotation separation efficiency of unburned carbon from fly ash is limited due to the ultrafine size and poor hydrophobicity of the unburned carbon. This study introduces carrier flotation as an efficient method for removing unburned carbon from fly ash. Experimental results indicated that the use of carrier particles (low ash content coal particles) significantly enhanced the flotation removal efficiency of unburned carbon from fly ash compared to conventional methods. The enhancement mechanism was evaluated by examining the differences in flotation froth properties, particle aggregation behaviors, and extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) interaction energy in the presence and absence of hydrophobic carrier particles. Hydrophobic carrier particles were found to increase the stability of the flotation froth layer, facilitate the water recovery, and aid in the removal of fine unburned carbon particles. Focused beam reflectance measurement (FBRM) confirmed that the presence of hydrophobic carriers promoted the aggregation of fine unburned carbon particles, thereby increasing bubble-particle collision probability. Furthermore, EDVLO theory calculations revealed that the attractive interaction energy between carrier particles and unburned carbon particles was stronger than that between carrier particles and ash particles. Therefore, carrier flotation shows promise as a highly efficient method for removing unburned carbon from fly ash.

Study of the Mechanical Properties of the Fly Ash Composite Bricks

Fly ash brick is an eco-friendly construction material comprised of fly ash, bottom ash, cement and rice husk. Fly ash, a by-product of coal-fired power plants is utilized in place of typical clay or lime in the manufacturing process. One of the key benefits of fly ash brick is its long-term viability. Utilizing fly ash in the manufacturing process lowers waste generated by power stations and the requirement for virgin resources. Fly ash brick also has a reduced carbon impact than typical clay bricks. In terms of performance, fly ash brick offers various benefits. The bricks are more robust and resistant to weathering because they have a higher compressive strength and lower water absorption rate than ordinary clay bricks. They are also well insulated and have a low thermal conductivity. Fly ash brick is also cost-effective since it takes less energy to produce and is less expensive than typical clay bricks. Fly ash bricks are better for the environment since they have a reduced carbon footprint than ordinary clay bricks. They also offer numerous advantages, such as sturdy, long-lasting, and weather-resistant. They also have strong insulation characteristics, which means they can keep a structure cool in the summer and warm in the winter. Fly ash bricks are also a suitable alternative for construction since they are less expensive than regular clay bricks. They also take less energy to manufacture, making them more cost-effective. In this paper, we study the comparison of conventional break and fly ash brick on various dimensions like compressive strength and water absorption test. In this study, the Taguchi technique of parameter design is used to describe the findings of an experimental investigation into the mix proportions of fly ash bricks. With four factors and three levels per factor, the experiments were created using a L9 orthogonal array

Activity Concentration Index Values for Concrete Multistory Residences in Greece Due to Fly Ash Addition in Cement

According to 2013/59/Euratom Directive, the activity concentration index (ACI) is required to be estimated for each building material that is of concern from a radiation protection point of view. This index applies to building materials and not to constituents that cannot be used as building materials themselves. Fly ash is a byproduct of coal-fired power plants and is one of the main constituents of cement. The radioactivity in fly ash that is produced by Greek lignite power plants cannot be considered insignificant. For example, in the case of the Megalopolis power plant, the concentration for radioisotopes of the 226Ra chain is found to be about 1 kBq/kg. Since natural radionuclide concentrations, which are harmful to human health in terms of radiation exposure, exist in fly ash, ACI should be assessed for building materials containing fly ash. The present study evaluates the ACI of concrete containing fly ash cement when used in multistory residential buildings. Results showed that cement produced in Greece by the three main Greek cement production plants, containing lignite fly ash, and used as a material for concrete multistory constructions, should not be considered as “of concern from a radiation protection point of view”. Each country that wishes to evaluate the use of fly ash into constructions should repeat the method for the ACI uncertainty budget proposed in this study, to assess whether it significantly exceeds the reference value (whether it is of concern from a radiation protection point of view).

Mechanical analysis of sisal fiber/bio-epoxy/fly-ash reinforced hybrid composites

This research investigates the mechanical characteristics of a novel hybrid composite material, which combines bio-epoxy reinforced with sisal fiber and integrated with fly ash nano-fillers. The study focuses on exploiting the environmentally friendly attributes of natural fiber composites and reducing reliance on synthetic materials. In this study, sisal fiber serves as the reinforcement, and a bio-epoxy matrix is utilized to create the composite. To further enhance its properties, fly ash, a byproduct of coal-fired power plants, is incorporated as a nano-filler. The experimental findings reveal significant improvements in the mechanical properties of the composite due to the inclusion of fly ash nano-fillers. The tensile strength shows a notable enhancement of up to 6.3%, flexural strength experiences an impressive increase of 68%, impact strength demonstrates a remarkable boost of 28%, and scratch hardness elevates by 17% which were all achieved at 20% fiber weight fraction and 5% fly ash weight fraction. The considerable potential of this hybrid sisal fiber reinforced bio-epoxy composite, integrated with fly ash nano-fillers, as an eco-friendly alternative to traditional synthetic composites is evident from these results. Such enhancements make the composite suitable for a wide range of engineering applications, including the manufacturing of automotive components, construction materials, and consumer goods. By adopting this bio-composite, industries can actively contribute to sustainable practices while maintaining optimal performance in their products. This research offers valuable insights into a promising solution for eco-conscious engineering applications, with both quantitative and qualitative evidence demonstrating the achievement of superior mechanical properties in this innovative hybrid material.

Evaluation of flue gas desulfurization gypsum as a low-cost precipitant for phosphorus removal from anaerobic digestion effluent filtrate

Land application of anaerobic digestion (AD) effluent as a fertilizer is desirable for nutrient recycle, but often supplies excess phosphorus (P), which contributes to surface water eutrophication. Reducing the P content in AD effluent using calcium treatment prior to land application is a potential strategy for improving effluent disposability. In order to solve the problems of low phosphorus removal efficiency and high operating cost in wastewaters, this study took flue gas desulphurization (FGD) gypsum, a by-product of coal-fired power plants, as a low-cost calcium source, and combined with traditional phosphorus removal agents to achieve high phosphorus removal efficiency with less chemical inputs. As the results showed, FGD gypsum dosages of 20 mM Ca (3.44 g/L) and 40 mM Ca (6.89 g/L) removed up to 97.1% of soluble P (initially 102.8 mg/L) within 60-90 minutes. Combining FGD gypsum treatment with traditional chemical treatments using Ca(OH)2 or FeCl3 could achieve >99% P removal with reduced chemical costs. This study demonstrated that FGD gypsum is an effective calcium precipitant for phosphorus removal.

Effect on bearing capacity and settlement behaviour of fly-ash reinforced with fine micropiles

ABSTRACT Micropiling is an extensively used method for improving the stability of building foundations and load-carrying capacity of the soil. Unlike regular piling, it can be employed without pile driving equipment and, hence, it is a versatile option of soil reinforcement under space-restricted situations. Since, it is an economical and easy to implement option for soil improvement, this paper intends to study the improvement in bearing capacity and settlement behaviour of a fly-ash bed using fine micropiles under isolated footings, for low-cast and lightweight structures. Fly-ash, a by-product of coal-fired power plants, is used in the experiment because it is extensively used as a filling material for housing projects in low-lying areas and pavements. Micropiles were installed underneath the footing as well as beyond the periphery of footing with varied spacing and extent ratio. The results are depicted through two dimensionless constants, namely bearing capacity ratio (BCR) and settlement reduction factor (SRF). Significant improvements have been observed in load-carrying capacity and settlement potential due to decrease in spacing and increase in lateral extent of micropiles. The optimum configuration of spacing and lateral extend achieved 135% bearing capacity improvement with 71% decrease in settlement.

Detecting Organic Materials in Fly Ash using Chromatographic Method

Abstract: Fly ash, a byproduct of coal-fired power plants, is entirely inorganic and inert, making it unfit for life. In Korba, fly ash is deposited in dykes, which are open embankments. The quest for organic compounds was critical because the humus formation is a revolution in fly ash, and just it will be capable of supporting life forms. This was conducted in the dykes to verify the organic materials source in fly ash, namely, whether they are originated from coal, furnace start-up oil, or animals and plants that grew in the area. Thin layer chromatography and ascending paper chromatography in a liquid medium were used as the method.

Leachability of Heavy Metals from Autoclaved Fly Ash-Lime Building Bricks

The fly ash as a byproduct of coal-fired power plants constitutes vital ecological problems. In Turkey, approximately 15 million tons ofashes are generated via the combustion of 40 million tons of lignite yearly. Worldwide, a number of investigation and applications wereundertaken to utilize fly ash in order to overcome the environmental problems. One of the application area of fly ashes is the production of building bricks. Characterization of fly ash samples from Seyitomer and Yatagan coal-firing power plants were conducted inthis study. TCLP 1311, ASTM3987-85 and EN 12457-2 leaching tests on the cylindrical fly ash/lime brick (FA/LB) samples which wereproduced from Seyitömer and Yatagan thermal power plant fly ash-lime mixtures were performed to determine the leachability ofsome chosen trace elements. The results show that the release of all trace elements was lower than the hazardous material limit valuesof waste acceptance. Thus, non- fired fly ash bricks are an advantageous way to solving environmental effect of disposal of fly ashes.

Stabilization of lead in waste water and farmland soil using modified coal fly ash

As a by-product of coal-fired power plants, fly ash has attracted widespread attention because of its heavy metal adsorption potential. In this study, two fly ashes from different power plants were re-used through modification to adsorb Pb(Ⅱ) from aqueous solution and field soil. The physicochemical properties of adsorbents were characterized by X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as the X-ray photoelectron spectroscopy (XPS). In addition, batch sorption experiments and field study were conducted to investigate their adsorption capacity on Pb(Ⅱ). The results demonstrated that, the surface area of modified fly ash-2 (MFA-2) has increased 25 times. The kinetic study illustrated that the adsorption process on both modified fly ash-1 (MFA-1) and MFA-2 were more suitable for pseudo-second-order model. Nevertheless, MFA-2 took less time to reach adsorption equilibrium. Compared with the raw fly ashes, the prepared MFAs had stronger affinities to Pb(II). When used as adsorbents, more than 146 and 165 mg of Pb(II) could be adsorptively stabilized by per gram of MFA-1 and MFA-2 at 318 K from waste water, respectively; when employed as amendments, the addition of MFA-1 and MFA-2 into soil could reduce Pb accumulation in rice, with the total Pb content in rice grains is lower than the level of natural standard. The investigation declared that the MFAs were promising materials which had great potentials on adsorptive stabilization of Pb(II) from waste water and contaminated soil, which also realizes the recycling of resources and cleaner production.

Comparative evaluation of iron leach from different sources of fly ash under atmospherically relevant conditions

Environmental contextIron, a limiting nutrient of plankton in the ocean, is deposited to the sea from atmospheric aerosols. In particular, atmospheric acidic conditions promote dissolution of iron from fly ash, a by-product of coal-fired power plants. Here, we report that the iron leached from fly ash depends on its source region, and that the type of combustion process may influence the iron species mobilized. AbstractFly ash, an iron-containing by-product of coal-fired power plants, has been observed in atmospheric aerosol plumes. Under the acidic atmospheric conditions resulting from the uptake of atmospheric gases, iron leached from fly ash can impact global biogeochemical cycles. However, the fly ash source region, as well as its generating power plant, plays an important role in the amount, speciation and lability of iron. Yet no comparative studies have been made on iron leached from fly ash from different sources. This study reports the iron mobilisation by proton-promoted dissolution from well-characterised fly ash samples from three distinctive locations: the USA Midwest, north-east India and Europe. In addition, pH dependency was also investigated. Proton-promoted dissolution showed a variability between source regions with a relative iron leach in the order USA Midwestern>north-east Indian>European ash. In addition, the initial rate of iron leach suggests that source region is indeed a determining factor in the iron leaching capacity of fly ash, because dissolution from Midwestern fly ash is also faster than both European and Indian ash. Finally, the combustion process of fly ash proved to be significant for the iron speciation, given that well-combusted fly ash samples leached mostly Fe3+ rather than bioavailable Fe2+. The role of fly ash should therefore be taken into account in order to better understand the effects of combustion particles in atmospheric iron deposition.

Hydrologic transport of fecal bacteria attenuated by flue gas desulfurization gypsum.

Flue gas desulfurization (FGD) gypsum is a byproduct of coal-fired power plants. Its application to agricultural fields may increase water infiltration, reduce soil erosion, and decrease nutrient losses from applications of animal manures. It may also reduce fecal bacterial contamination of surface waters. We tested the hypothesis that FGD gypsum applications would decrease the load of and the fecal indicator bacterium from poultry litter applications. Two rainfall simulation experiments were undertaken: one in spring 2009 and one in spring 2011. Six treatments consisted of four rates of FGD gypsum (0, 2.2, 4.5, and 9.0 Mg ha) with poultry litter (13.5 Mg ha and two controls) in a randomized, complete-block design with three replications. Each replicate 4- × 6-m plot contained a single 1- × 2-m subplot that was delineated by metal plates and a flume that captured total overland flow or runoff. Rainfall was applied at ∼64 mm h. Volume of overland runoff was measured and subsampled for analysis every 10 min for 1 h. Flow-weighted concentrations, total loads, and soil concentrations of were determined. was not detected in runoff. No significant differences between treatments were observed for the 2009 rainfall simulation. However, after 3 yr of FGD gypsum applications, the highest rate of FGD gypsum resulted in decreased flow-weighted concentrations and total loads of . Flue gas desulfurization gypsum applications may be a management practice that reduces microbial contamination of surface waters from manure applied to agricultural fields in the southeastern United States.

The experimental study of fly ash decarbonization on a circulating fluidized bed combustor

Fly ash is a by-product of coal-fired power plants, whose production is huge. As the coal resources are in short supply in recent years, most circulating fluidized bed (CFB) boilers in China burn hard coals, thus, the carbon content in the fly ash is much higher than expected. The high carbon content in the fly ash limits the potential utilization as building materials. At present, the decarbonization method of high carbon content CFB fly ash is mainly fly ash recirculation combustion (FARC). Because of the huge difference between original boiler operating conditions and fly ash ideal combustion state, the decarbonization effect is disappointed. Therefore, a series of fly ash decarbonization experiments were carried out on a bench-scale CFB combustor designed on fluidization properties of fly ash, and the decarbonization characteristics were discussed. Results show that fly ash requires a minimum sectional thermal load of 0.42 MW/m2 for continuous and stable combustion in test combustor, corresponding to the critical carbon content in the fly ash is 18%. The maximum decarbonization efficiency of the test CFB combustor is approximately 75%, which is much higher than that of FARC.

Influence of Particle Size Distribution of Fly Ash on Compressive Strength and Durability of Portland Cement Concrete

The Present Research Investigates the Compressive and Durable Properties of Concretes with Fly Ash (FA), a by-Product of Coal-Fired Power Plants. for this Purpose, a Reference Sample and Twenty-one Concretes Containing FA Were Tested. the FA Was Sieved to 200, 300, and 400 Mesh. then FA Was Mixed into Concrete with Different Content. Compressive Strength at 7 and 28 Days, and Chloride Penetration Properties Were Measured. it Is Concluded that FA Can Be Used in the Production of Concrete. in Addition, the FA Concretes Present Satisfactory Physical Properties. when Proper Amount of FA Were Added the Concrete Properties Can Be Better than the Blank one.

An Experimental Study on the Electrical Properties of Fly Ash in the Grounding System

A good grounding system is the fundamental insurance to keep the safe operation of power systems. The grounding resistance reduction additive-fly ash is proposed in this study. Fly ash is the byproduct of coal-fired power plants. A pulverized coal boiler generates approximately 80% fly ash and only 20% bottom ash. Furthermore, the study of these materials will assume greater importance. Waste utilization is an attractive alternative to disposal in that disposal cost and potential pollution problems are reduced. Extensively used as an additive in Portland cement or as a mineral admixture in concrete in recent years, we have found that fly ash has a low resistivity, and so can be used as an agent for reducing resistance to grounding. Also, an effort is made to investigate the effect of water-to-cement(W/C) and temperature on the resistivity of the test specimens. The grounding resistance reduction agent was determined by considering various proportions of water, cement and salt. Experimental results demonstrate that the proposed approach can effectively reduce the grounding resistance.

ERODIBILITY OF FLY ASH-TREATED MINESOILS

Fly ash, a by-product of coal-fired power plants, has been used successfully in reclaiming adverse mine sites such as abandoned mine lands by improving minesoil chemical and physical properties. But, the fine sand-silt particle size of fly ash may make it more susceptible to detachment and transport by erosive processes. Furthermore, the high content of silt-size particles in fly ash may make it more susceptable to surface crust formation resulting in reduced infiltration and increased surface runoff and erosion. In the summer of 1989, fly ash/wood waste mixtures were surface applied on two separate mine sites, one with 10% slope and the other 20% slope, in central Preston County, West Virginia. Erosion rates were measured directly using the Linear Erosion/Elevation Measuring Instrument (LEMI). Erosion measurements were taken during the first two growing seasons on both sites. Erosion values were up to five times greater on the fly ash-treated minesoil than on the minesoil without fly ash cover. Mulching with wood chips reduced fly ash erosion to about one-half the loss of the unmulched plots. Erosion was related to both the amount and type of ground cover. Increased vegetative ground cover resulted in reduced erosion. Mosses and fungi appeared to providemore » better erosion protection than grass-legume cover.« less

Extraction of leachable metals and recovery of alumina from utility coal ash

The classification of coal ash as a “special waste” by the Environmental Protection Agency (EPA) stimulated questions concerning the environmental impact of the disposal of this voluminous byproduct of coal-fired power plants. Both industry and Government face possible expensive disposal problems because of the large volume of coal ash produced annually. The extraction of metals from coal ash was investigated as part of a Bureau of Mines program to convert waste materials from a disposal problem to potential secondary resources. The objectives of this study were to produce a more environmentally acceptable waste and offset waste disposal costs with recovered metal values. The research was conducted in two steps: determination of parameters affecting extraction of aluminum from coal ash, and development of extraction-recovery procedures. The major parameter affecting the extraction of metals from coal ash was the calcium content of the fly or bottom ash. Other parameters, such as furnace type and operating temperature, had lesser effects on metal extraction. Two procedures were studied for metal extraction: an acid leach for high-calcium ashes and a lime sinter-acid leach for low-calcium ashes. The first procedure removed about 757 of the metals in high-calcium ash, and the second removed about 907 of the metals in low-calcium ash. An alumina product was recovered that, with sufficient washing, meets “Hall Cell” specifications. The leach residues pass the EPA EP toxicity test and are classified as nonhazardous wastes.