Characterization of Catalyzed Devitrification in Quenched Fly Ash Melts

1984 ◽  
Vol 43 ◽  
Author(s):  
Subhash H. Risbud
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Ceramic Body ◽  
Combustion Process ◽  
Bottom Ash ◽  
Waste Utilization ◽  
Raw Material ◽  
Friable Material ◽  
Air Pollution Control ◽  
Silica Alumina

Coal combustion produces enormous quantities of residual ash often called bottom ash or fly ash. The fly ash component contains lightweight cenospheres giving the ash a fluffy character. Fly ash is captured in the coal combustion process by air pollution control devices as the gases exit the stack. Fly ash compositions are usually highly siliceous consisting mainly of the oxides of silica, alumina, calcia, and iron oxides; minor constituents such as MgO, alkali oxides, TiO2 etc. are also almost invariably present in quantities of ≈0.5 to 3 wt%. Two important aspects of crystallization of fly ash melts and glasses relate to the prevention of boiler slagging [1] and, from a waste utilization point of view, to the development of new products using fly ash as a raw material[2–4]. Ash devitrification on cooling of the melt results in friable material that does not stick to boiler walls as easily as glassy slag [5]. From another standpoint, crystallization of glassy ash slag to a fine grained equiaxed microstructure is considered a desirable glass-ceramic body for thermomechanical reasons [6].

Bottom-Ash Waste Management for Soil Improvement in Saraburi Province, Thailand

2019 ◽  
Vol 947 ◽  
pp. 114-118
Author(s):  
Kreangkrai Maneeintr ◽  
Tuyet Thi Anh Tran ◽  
Watcharin Kaewmaneewan
Keyword(s):  
Coal Combustion ◽  
Soil Amendment ◽  
Combustion Process ◽  
Bottom Ash ◽  
Soil Improvement ◽  
Waste Utilization ◽  
Coal Waste ◽  
Huge Amount ◽  
Normal Soil ◽  
Properties Of Soil

Recently, coal is still one of the main sources of energy. From a coal combustion process, a huge amount of coal waste such as bottom ash is generated. The most common method for coal-waste disposal is a landfill which creates the environmental problems. However, the coal-waste utilization like soil amendment is a better way to manage the waste as well as to reduce the environmental impacts and to increase the profit for the manufacturers. Therefore, the objectives of this study are to measure the properties of soil mixed with bottom ash from coal waste and to apply the bottom ash to improve the soil quality by growing one types of plants, chili, and to compare the results with the normal soil and soil with fertilizer. The operating parameters of this study are the compositions of coal-waste mixed with soil and fertilizer ranging from 0 to 30%wt. Furthermore, the pH, bulk density as well as soil texture are also measured and studied. From the results, it is found that bottom ash can help growing both plants especially chili with 10%wt bottom ash.

scholarly journals Preparation of Synthetic Zeolites from Coal Fly Ash by Hydrothermal Synthesis

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1267
Author(s):  
David Längauer ◽  
Vladimír Čablík ◽  
Slavomír Hredzák ◽  
Anton Zubrik ◽  
Marek Matik ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Product Analysis ◽  
Coal Combustion Products ◽  
X Ray ◽  
Wide Range ◽  
Silica Alumina

Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al2O3, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

The Strength of Fly Ash-Bottom Ash (FA-BA) Mixtures as Backfill Material in Ground Improvement Works

2013 ◽  
Vol 465-466 ◽  
pp. 937-943
Author(s):  
Abd Rahim bin Hj. Awang ◽  
Wan Hilmi bin Wan Mansor ◽  
Ahmad Yusri Bin Mohamad
Keyword(s):  
Shear Strength ◽  
Fly Ash ◽  
Specific Gravity ◽  
Ground Improvement ◽  
Bottom Ash ◽  
Friction Angle ◽  
Soil Improvement ◽  
Geotechnical Properties ◽  
Raw Material ◽  
Fa Composition

In Malaysia, coal has been used as a raw material to generate electricity since 1988. In the past, most of the wastage of coal burning especially the bottom ash was not managed properly as it was dumped in the waste pond and accumulated drastically. This research has been conducted to explore the physical characteristic and geotechnical properties of fly ash-bottom ash (FA-BA) mixtures that consist of 30% FA, 50% FA, 70% FA and 90% FA by weight. The physical characteristics, that include the specific gravity, particle size distribution and compaction, were tested for each mixture without any curing. However, the geotechnical properties of the mixtures that include the permeability and shear strength had been studied at various curing periods (0, 14 and 28 days) to review the effect of time on the geotechnical properties of the mixtures. The results show that mixtures with higher FA composition have lower value of specific gravity, well-graded, and need less moisture to be compacted efficiently compared to those mixtures with lower FA composition. The results also show that mixtures with higher FA composition have less drainage characteristics but can be improved by prolonging the curing period. The maximum shear strength was obtained at mixture with 50%FA and the value increased with curing periods. The friction angle obtained ranged from 270to 370. It is also found that the mixtures with lower FA composition are more compressible compared to the mixtures with higher FA composition. The results obtained could be used by others to determine the suitability of different FA-BA mixtures for various usage in Geotechnical Engineering work such as for soil improvement work in weak soils or as backfill materials in embankment construction.

A Review on Processing and Properties of Bottom Ash Based Geopolymer Materials

2015 ◽  
Vol 660 ◽  
pp. 3-8
Author(s):  
Laila Mardiah Deraman ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Liew Yun Ming ◽  
Kamarudin Hussin ◽  
Zarina Yahya
Keyword(s):  
Raw Materials ◽  
Thermal Power ◽  
Rapid Change ◽  
Bottom Ash ◽  
Chemical Properties ◽  
Silicate Solution ◽  
Raw Material ◽  
Silica Alumina ◽  
Curing Method ◽  
Geopolymer Material

Geopolymerization are chemical reaction between raw material and alkaline activator where a rapid change of some partial armorphous, specific structure into a compact cemented framework. It was treated with an alkali silicate solution at 45 – 80 °C whereas it’s formed from reaction of mineral clays or aluminosilicate-bearing industrial waste. The previous study about geopolymer has been done for many years due to the physical and chemical properties which is suitable to use in the construction industry. A Geopolymer material that was containing most Silica (Si) and Aluminium (Al) is such as fly ash, bottom ash, metakaolin and ground granulate blast slag (GGBS). Bottom ash is produced from coal fired thermal power plant and has a physical characteristic similar as sand or gravel sand that makes it ideal for industrial application like a green concrete. The different performance of geopolymer is according to the different content of silica, alumina and calcium. To obtain the best geopolymer material, parameter of raw materials content, the types and ratio of alkaline activators also the curing method will affect the high result of compressive strength. This paper will summarize a previous researchers work about the alkali-activated binder in geopolymer raw materials to become green product.

scholarly journals Characteristics of high carbon ash as a raw material for spontaneous combustion inhibitor and its field demonstration

2020 ◽  
Author(s):  
Seok Un Park ◽  
Jae Kwan Kim ◽  
Dong Ik Shin
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Bituminous Coal ◽  
Spontaneous Combustion ◽  
Bottom Ash ◽  
Frequency Factor ◽  
Raw Material ◽  
Unburned Carbon ◽  
Mixing Ratio ◽  
High Carbon

Abstract In this study, we examined the physical chemistry, fuel characteristics and combustion reactivity of high carbon ash as a raw material for spontaneous combustion inhibitor in order to solve the problem of spontaneous combustion which has been often occurring in coal yard of coal-fired power plants in Korea. The high carbon ash has higher activation energy and lower frequency factor than bituminous coal, so combustion began at a relatively higher temperature than bituminous coal. In case of fly ash, the heat transfer characteristics were better than those of bottom ash and pond ash, and in case of coarse particles of fly ash, they were found to be highly applicable as a raw material for spontaneous combustion inhibitor due to their relatively high unburned carbon content. As a result of manufacturing spontaneous combustion inhibitors along with asphalt and PFAD (palm fatty acid distillate), the contact angle to water was more than 90° regardless of the mixing ratio, showing hydrophobic surface characteristics, and it was found that the hardness and viscosity of spontaneous combustion inhibitors increased as the mixing ratio of high carbon ash increased. In addition, when spontaneous combustion inhibitors manufactured were applied to coal stockpiles in coal yard at coal-fired power plants, there was little change in the internal temperature of coal stockpiles and the highest value of instantaneous increasing rate per minute was found to be lowered from 1.60°C/min to 0.061°C/min, indicating that spontaneous combustion inhibitors using high carbon coal ash had a great effect of preventing spontaneous combustion.

Fluidized bed combustion bottom ash: A better and alternative geo-material resource for construction

2018 ◽  
Vol 36 (4) ◽  
pp. 351-360 ◽  
Author(s):  
AK Mandal ◽  
Bala Ramudu Paramkusam ◽  
OP Sinha
Keyword(s):  
Fluidized Bed ◽  
Coal Combustion ◽  
Construction Material ◽  
Combustion Process ◽  
Bottom Ash ◽  
Base Material ◽  
Filter Material ◽  
Fluidized Bed Combustion ◽  
River Sand ◽  
Pulverized Combustion

Though the majority of research on fly ash has proved its worth as a construction material, the utility of bottom ash is yet questionable due to its generation during the pulverized combustion process. The bottom ash produced during the fluidized bed combustion (FBC) process is attracting more attention due to the novelty of coal combustion technology. But, to establish its suitability as construction material, it is necessary to characterize it thoroughly with respect to the geotechnical as well as mineralogical points of view. For fulfilling these objectives, the present study mainly aims at characterizing the FBC bottom ash and its comparison with pulverized coal combustion (PCC) bottom ash, collected from the same origin of coal. Suitability of FBC bottom ash as a dike filter material in contrast to PCC bottom ash in replacing traditional filter material such as sand was also studied. The suitability criteria for utilization of both bottom ash and river sand as filter material on pond ash as a base material were evaluated, and both river sand and FBC bottom ash were found to be satisfactory. The study shows that FBC bottom ash is a better geo-material than PCC bottom ash, and it could be highly recommended as an alternative suitable filter material for constructing ash dikes in place of conventional sand.

Effect of CaO and Fe2O3 on Partitioning of As and S within Ash Fractions from Fluidised-Bed Co-Combustion of Coal and Wastes

2018 ◽  
Vol 11 (1) ◽  
pp. 81-90
Author(s):  
Lucie Bartoňová
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Coal Combustion ◽  
Bottom Ash ◽  
Correlation Coefficients ◽  
Fluidised Bed ◽  
Solid Product ◽  
Gas Cleaning

Possible interaction of volatilized As and S with CaO and Fe2O3 (creating solid product) could efficiently improve coal combustion flue gas cleaning. For this reason, S-CaO, As-CaO, S- Fe2O3 and As- Fe2O3 relationships were evaluated in bottom ash and fly ash fractions from fluidised-bed co-combustion of coal and wastes (and limestone as desulphurization additive) through calculation of correlation coefficients and composition of magnetic concentrates. It was concluded that S exhibited a dominant association with CaO while As exhibited affinity to both CaO and Fe2O3 - the significance differed a little in bottom ash and fly ash. In the bottom ash, the affinity of As to CaO was more significant, while in the fly ash the association to Fe2O3 slightly prevailed.

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

2006 ◽  
Vol 7 (2) ◽  
Author(s):  
Shin-Der Chen ◽  
Li-Hsiung Chen ◽  
Chih-Kun Cheng ◽  
Jiann-Fuh Chen
Keyword(s):  
Fly Ash ◽  
Power Systems ◽  
Power Plants ◽  
Bottom Ash ◽  
Waste Utilization ◽  
Mineral Admixture ◽  
Attractive Alternative ◽  
Grounding System ◽  
Grounding Resistance ◽  
Resistance Reduction

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.

An Overview of Fly Ash and Bottom Ash Replacement in Self-Compaction Concrete

2013 ◽  
Vol 594-595 ◽  
pp. 465-470 ◽  
Author(s):  
Aeslina binti Abdul Kadir ◽  
Mohd Ikhmal Haqeem Hassan
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Building Materials ◽  
Bottom Ash ◽  
Coal Ash ◽  
Limestone Powder ◽  
Conventional Concrete ◽  
Hydraulic Lime ◽  
Pollution Problem ◽  
Labor Requirements

Over the centuries, concrete is commonly been used in construction world due to its properties. From the conventional concrete until the concrete that has been diversify with innovations, the usefulness is still the same, which is as building materials. One of the innovations called Self-Compaction Concrete (SCC). SCC is a type of concrete that does not require any mechanical compaction at all. This type of concrete will leveled and compacted under its self-weight. Such concrete will accelerate the placement, reduce the labor requirements needed for consolidation, finishing and eliminate environmental pollution. In terms of sustainability, previous researchers have recycled so many waste in SCC for example coal ash, silica fume, hydraulic lime, rice husk ash and fine limestone powder. Recently, recycling fly ash and bottom ash in SCC has grasped the attention of researchers as it demonstrated promising results. Furthermore, previous investigations already confirmed the potential of fly ash and bottom ash in replacing aggregates in SCC represents a better option than landfill and at the same time will decrease pollution problem especially in coal combustion area. This paper reviews the fly ash and bottom ash replacement in SCC.

Experimental Study on the Effects of Declivitous Angle of Secondary Air on the Flow Characteristics and Coal Combustion of a Down-Fired

2011 ◽  
Author(s):  
Jian Shi ◽  
Yuzhong Chen ◽  
Yubo Hou ◽  
Bin Yao
Keyword(s):  
Fly Ash ◽  
Flow Field ◽  
Carbon Content ◽  
Coal Combustion ◽  
Field Experiments ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Cold Flow ◽  
Horizontal Momentum ◽  
Secondary Air

Aiming at Foster Wheeler (FW) technology down-fired boiler with horizontal F layer secondary air, in which the strong horizontal momentum of the secondary air seriously pounds the down flowing coal gas flame, making the problems of short trip of coal flame and low flame fullness of the furnace, and this leads to higher carbon content of fly ash and so on. A designed adjusting device making the declivitous angle of secondary air is erected in the F layer wind box of a FW down-fired furnace, so the declivitous angle of secondary air can be regulated freely. By this means, the declivitous angle of the F layer secondary air is able to be refined depending on the real combustion situation to achieve the best configuration of the momentum radio by downward momentum from the arch and horizontal momentum from the front/rear wall. As a result, it is able to adapt the change of the furnace combustion situation, extending the flame travel, and improving the combustion process and efficiency. This method was applied to a 300MW grade FW down-fired boiler, and the cold flow field results by fireworks showed the down flow depth of the primary air increasing with the declivitous angle. The best flow field was achieved as the declivitous angle was set to 45°. Based on the cold flow field experiments, combustion experiment was accomplished to compare with the coal combustion performance before the declivitous refinement of the F layer secondary air. It was shown that the carbon content of the fly ash was greatly decreased after the refinement, and the combustion efficiency was increased by 3.3%.

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