Top PDF Photoacoustic measurement of unburned carbon in fly-ash

Photoacoustic measurement of unburned carbon in fly ash

Photoacoustic measurement of unburned carbon in fly ash

The present invention provides a method and an apparatus for measuring the amount of unburned carbon in a sample of fly ash using infrared photoacoustic absorption. One preferred method according to the present invention involves directing modulated infrared radiation at a sample of fly ash and measuring the acoustic signal produced when the unburned carbon in the sample absorbs the radiation producing a thermal wave which propagates through the sample to generate a minute acoustic wave at interfaces between the carbon particles and gas surrounding the particles. One preferred apparatus includes a source of modulated infrared radiation, a chamber for containing the sample, a microphone to detect the acoustic signals, lock-in amplifier to separate the desired photoacoustic signal from noise at other frequencies, and a PC computer to provide output from the amplifier. This apparatus identifies the acoustic signal for determination of the amount of unburned carbon in the sample.
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CFD approach for unburned carbon reduction in pulverized coal boilers

CFD approach for unburned carbon reduction in pulverized coal boilers

LOI is a key parameter that is related to both boiler combustion efficiency and ash utilization. Thus, it was studied to determine boiler combustion performance. Figure 7 shows the LOI emissions at different boiler load cases. It can be seen that the OP-650 pulverized coal boiler was operating under more suitable conditions; the average LOI values at the three loads almost fulfilled the European standard of 5% in mass. Only the predicted LOI at 140 MW and measured LOI at 170 MW were slightly higher. Currently, the biggest market for fly ash is in concrete applications, as an additive for cement. One of the criteria for such an application is that the carbon content or the LOI limit must be lower than 6% according to ASTM standard 618, and lower than 3% in market practice [17]. The ash products with LOI approximately 2.5 wt% were performed well in concrete[18]. Therefore, the LOI emission has to be less than 3% for general market demand and 2.5% LOI emission is target, as shown in Figure 7. In this work, the LOI emission was controlled and further reduced to fulfill these tight requirements, both in combustion efficiency and ash utility. The entire low-NOx system was not altered, meaning that the reduction of the LOI had to be accomplished via adjustment of the operating conditions of the burners with higher unburned carbon emissions, while maintaining a low NOx emissions level.
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Direct synthesis of carbon nanofibers from South African coal fly ash

Direct synthesis of carbon nanofibers from South African coal fly ash

nanofiber (CNF) syntheses [30-35], hence the potential of fly ash to be used as a catalyst in this reaction. In this regard, Yasui et al. [28] have used Japanese fly ash, where Fe was added to the ash to enhance its activity. Although CNTs were produced, these were of a very low yield and poor quality. Dunens et al. [36] showed that CNTs and CNFs could be produced by Australian coal fly ash using the chemical vapour deposition (CVD) method. How- ever, in their case, multiple steps were followed, as iron (which was low in their fly ash, <2.5%) also had to be impregnated into their substrate and ethylene (an expen- sive carbon source) was used. This therefore resulted in the high cost of CNT and CNF production, although a recycled waste material was used as a catalyst. In an ef- fort to improve the aforementioned processes, Salah et al. [27] used carbon-rich Saudi Arabian fly ash to pro- duce CNTs. These tubes were also synthesized through a CVD process, but pre-treatment of the ash to remove unburned carbon was required in order to use the ash as a catalyst.
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Improvement on Quantitative Measurement of Fly Ash Contents Using Laser Induced Breakdown Spectroscopy

Improvement on Quantitative Measurement of Fly Ash Contents Using Laser Induced Breakdown Spectroscopy

Contents of fly ash are important factors for the operation of coal-fired plants. Real-time monitor- ing of coal and fly ash such as unburned carbon in fly ash can be an indicator of the combustion conditions. Because of the strong signal intensity and the relative simplicity of the LIBS (Laser- Induced Breakdown Spectroscopy) technique, LIBS can be applicable for real-time composition measurement of coal and fly ash. This research presented here focused on the clarification of the effects of plasma temperature and coexisting materials on quantitative measurement of fly ash contents. Quantitative capability of LIBS was improved using the proposed plasma temperature correction method. The CO 2 effect was also discussed to accurately evaluate unburned carbon in
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Study of the unburned carbon content of ash and propose one new technology separated the ash and unburned carbon discharged by the coal-fire thermal power plants in Vietnam

Study of the unburned carbon content of ash and propose one new technology separated the ash and unburned carbon discharged by the coal-fire thermal power plants in Vietnam

According to the Prospectus of the Factory premixed dry mortar production Da Cao Cuong, on average, Pha Lai 2 Thermal Power Plant (Hai Duong) daily discharges 3,000 tons ash, of which 30% is unburnt coal, the rest is bottom ash and fly ash [6], [13], [15]. The amount of coal left in ash is very large. However, this amount of coal is not reused as fuel for boiler etc. and moreover this high carbon content affects the quality of products produced from ash. That is reason why we need to separate the amount of unburnt carbon in ash.
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Strengthening of Soil by Using Fly Ash

Strengthening of Soil by Using Fly Ash

The production of fly ash in power plants has resulted in a major environmental problem because it gels easily air borne. The stringent environmental regulations in recent years have forced practicing engineers to search for new applications for fly ash. Fly ash is been used for several applications. Bulk uses of fly ash art: found in civil engineering in general and in geotechnical engineering in particular, due to its pozzolanic property. Geotechnical application is mainly due to favorable physical chemical properties which include stabilization of soil, reclamation of low lying areas by construction of structural fills, construction of road embankment, dykes, and dams. These aspects are discussed in detail.
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Effect of Fly ASH on Properties of Concrete

Effect of Fly ASH on Properties of Concrete

Manas Kumar Sahoo 2010-11 His experiments helped in determining the potential of the fly ash for use, in manufacture of bricks, in highway embankments, as an aggregate material in Portland cement, filling of low lying and mine void areas etc. Composite material made of fly ash is subject to a variety of different loading conditions, and so different types of stresses develop. Based on the different strength of composites it can be used in various geotechnical applications like construction of roads, Embankment, dams and reservoirs and mine filling.
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Impact of Fly Ash in Bituminous Mix

Impact of Fly Ash in Bituminous Mix

Abstract - Bituminous mix Design is estimated to result in a mix which is sufficiently durable, strong, and to fatigue resistive and permanent deformation, at the same time eco friendly and economical. A mix maker tries to achieve those requirements by a number of tests on the mix with different proportions of material and finalizes the perfect one. This involves a perfect balance between mutually conflicting properties. Design of bitumen mix is a slightly balancing act among the proportions of different aggregate sizes and bitumen content. For a specified aggregate gradation the optimum bitumen content (OBC) is determine by a number of mix design parameters. In bituminous mix fillers play an key role in engineering parameters of bituminous paving mixes. Generally stone dust, lime and cement are used as fillers. An effort has been made in this experiment to assess the impact of non-conventional and easily available fillers such as cement and fly ash in bitumen paving mixes.
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SOIL STABILIZATION BY USING FLY ASH

SOIL STABILIZATION BY USING FLY ASH

Soil is a peculiar material. Some waste materials such Fly Ash, rice husk ash, pond ash may use to make the soil to be stable. Addition of such materials will increase the physical as well as chemical properties of the soil. Some expecting properties to be improved are liquidity index, plasticity index, unconfined compressive strength and bearing capacity etc. The objective of this study was to evaluate the effect of Fly Ash derived from combustion of sub-bituminous coal at electric power plants in stabilization of soft fine-grained. Many areas in Telangana region are located on high expensive soil. This paper describes about a study carried out to check the improvement in properties of soil by adding different percentages of fly ash.
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Soil Stabilization using Fly Ash

Soil Stabilization using Fly Ash

Fly ash is waste material obtained from thermal power plant. There are large number of power plant across the world which produces huge amount of fly ash. Use of fly ash is economic and it also prevent environmental pollution. Unsafe disposal of fly ash will cause irritation in breathing and causes many diseases like asthma. Fly ash are micro-sized particles consisting of alumina, silica and iron. Fly ash can be used in combination with other materials for soil stabilization.
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A Study of Ferrospheres in the Coal Fly Ash

A Study of Ferrospheres in the Coal Fly Ash

The main objective of this research is focused on the obtaining new types of materials with the use of modern technological methods (for example, bricks, lightweight concrete, geopolymer and etc.) based on the detailed structural analysis of the ferrospheres from coal fly ash-industrial byproduct materials and further develop technological backgrounds of it.

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Fly Ash in Forest Road Rehabilitation

Fly Ash in Forest Road Rehabilitation

Finnish forestry and bioenergy production is seeking novel uses for the fly ash deriving from biomass conversion. There are various possibilities for using fly ash in civil engineering in- cluding road construction. The increase in bioenergy production has created more interest for using ash in forest roads. However, no established methods for the rehabilitation of forest roads exist yet. Hence, this research aims to find a suitable construction method that involves using ash that provides adequate bearing capacity. It involved building ten test road sections: two of them were reference sections without fly ash. The study examined the effect of four different rehabilitation methods on the bearing capacity of roads. Measurements were made once before and four times after the rehabilitation. The measuring devices included a light falling weight deflectometer (LFWD), a dynamic cone penetrometer (DCP) and a conven- tional falling weight deflectometer (FWD). Two of the rehabilitation structures were 50 and 25 cm thick fly ash layers. The other two were 15 and 20 cm thick layers made of fly ash and aggregate in different mixing ratios. In all cases, the constructed layers were paved with ag- gregate. Statistical comparison showed that the bearing capacity of the rehabilitated road sections had improved compared to the reference sections. The recorded bearing capacities after rehabilitation (during spring thaw in 2012, 2013 and 2014) were about the same as before rehabilitation in summer 2011. Based on this study, fly ash can be recommended as an option for forest road rehabilitation.
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REPLACEMENT OF CEMENT WITH GGBS & FLY ASH

REPLACEMENT OF CEMENT WITH GGBS & FLY ASH

Portland cement of Ultratech made is poured into drum mixer. Similarly the measured possibilities of fly ash and GGBS had been poured in to drum mixer and the device turned around for 2 to 3 minutes to acquire uniform blend. Then the desired quantity of water is added to the dry combo and it changed into thoroughly blended to advantage homogeneous concrete. The time of rotation of tilting drum mixer became maintained three to four minutes to get the uniform blend of concrete. The mixed concrete grows to be placed in trays on a certain floor to casting of specimen cubes and specimen prisms.
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Fly Ash as a Partial Replacement of Cement in Concrete and Durability Study of Fly Ash in Acidic (H 2so4 ) Environment

Fly Ash as a Partial Replacement of Cement in Concrete and Durability Study of Fly Ash in Acidic (H 2so4 ) Environment

sea water of those concrete mixes are determined by immersing these cubes for 7 days, 28 days, 60 days in above solutions and the respective changes in both compressive strength and weight reduction had observed and upto a major extent we can conclude concretes made by that fly-ash and GGBS had good strength and durable properties comparison to conventional aggregate in severe environment.

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The influence of physico-chemical properties of fly ash and CKD on strength
generation of high volume fly ash concrete

The influence of physico-chemical properties of fly ash and CKD on strength generation of high volume fly ash concrete

Figure 10 shows compressive strength results for pairs of concrete mixes from the experimental programme where the only difference between a mix pair is the fly ash used. Comparison of strength results within a mix pair can highlight the interaction of both fly ashes with cement only, with cement and CKD 2 and with a combination of cement, CKD 1 and GGBS. Generally, fly ash 2 mixes were stronger than the corresponding fly ash 1 mixes at all ages (with the 28 day strength of mix 45A1-6.5KD1-18.5S being the exception). The higher proportion of amorphous phases relative to crystalline phases in fly ash 2 is thought to be the main contributory factor to observed higher compressive strengths for fly ash 2 mixes. However, the finer particle size and lower water demand (which would enable better concrete compaction for a fixed water content) would have also contributed to the superior performance of fly ash 2 mixes.
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Utilization of Bottom Ash in Hydraulic Stowing for Replacement of Sand and Fly Ash

Utilization of Bottom Ash in Hydraulic Stowing for Replacement of Sand and Fly Ash

recognized as a suitable stowing material due to its properties favorable for stowing. Hydraulic sand stowing in underground coal mines has been popular due to its simplicity in its operation. In India. The scarcity of river sand made the sand stowing operation practically in feasible now a days. On the other hand, bottom ash, the coal combustion, the coal combustion by products(CCBs), which are generated from the thermal power plants in abundance, creates environmental problems and requires safe disposals and utilization in bulk, realizing the problem of both the mining and power sectors and studying the properties of fly ash the researchers have identified a suitable alternative to river sand for stowing in an effective manner in India, initiatives have been taken and fly ash stowing in small scale has been done on trial base on two mines PK-1 of Singareni collieries company limited(SCCL) and Durgapur Raitawari number 4 mine in the Chandrapura area of western coal fields ltd.(WCL).in these two mines fly ash stowing has been done. The scarcity of fly ash also increased due to utilization of fly ash in Cement Company so the demand has been increased to the fly ash another alternative has been introduced that is bottom ash as stowing material because it has similar properties of sand. like it has coarser and heavier than fly ash with a gritty and sand-like texture, collected at the bottom of boiler furnace, bottom ash stowing in small scale has been done on trail bases in one mine named RK-7 of Singareni collieries’ company limited (SCCL) the stowing results of these cases is highly encouraging, how ever, some of the basic problems are to be in the coming stowing and brief case studies of bottom ash stowing status of the above mines.
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Fly Ash Concrete - A comparative Study

Fly Ash Concrete - A comparative Study

in shape, allowing them to flow and blend freely in mixtures. The “ball – bearing” effect of fly ash particles creates a lubricating action when concrete is in its plastic state. Concrete is easier to place with less effort, responding better to vibration to fill forms more completely. Ease of Pumping, pumping requires less energy and longer pumping Distances are possible. 2. Water Demand Reduction - Water demand depends on

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A Brief Review on Fly Ash Utilization

A Brief Review on Fly Ash Utilization

Nowadays the particulate reinforced aluminium matrix composite are gaining importance because of their low cost with advantages like isotropic properties and the possibility of secondary processing facilitating fabrication of secondary components. Metal Matrix Composites (MMCs) possess significantly improved properties including high specific strength; specific modulus, damping capacity and good wear resistance compared to unreinforced alloys. There has been an increasing interest in composites containing low density and low cost reinforcements. Among various discontinuous dispersoids used, fly ash is one of the most inexpensive and low density reinforcement available in large quantities as solid waste. Hence, composites with fly ash as reinforcement are likely to overcome the cost barrier for wide spread applications in automotive and small engine applications. It is therefore expected that the incorporation of fly ash particles in aluminium alloy will promote yet another use of this low-cost waste by product and at the same time, has the potential for conserving energy intensive aluminium and thereby, reducing the cost of aluminium products.
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Hydro-Sieved Carbon-Rich Fly Ash: Procedure and Comparison to Coconut Shell Activated Biocarbon

Hydro-Sieved Carbon-Rich Fly Ash: Procedure and Comparison to Coconut Shell Activated Biocarbon

Comparisons between fractions of CRFA in relation to ash content (AC) revealed that the highest value was found in the fraction with particle size coarser than 177 µm (8.78%) which comparable to that for the crude materials studied (CRFA and CSAC). In contrast, the other fractions of CRFA had less AC values ranged from 3.42% to 5.37%. The low AC in the CRFA fractions with particle size less than 177 µm may be attributed to the sorption trapping of more ash minerals within pores of the coarse particles (˃177 µm). In addition, AC values of the later-mentioned fractions were lower than those for the crude materials (CRFA and CSAC) as presented in Table 2. This may be due to leaching out some salts by water meanwhile the hydro-sieving method used for graduation of the CRFA. Accordingly, washing CRFA by stream of water and consequent vacuum-filtration must be done to reduce its AC.
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Geological Engineering in Fly Ash
Raghupathi

Geological Engineering in Fly Ash Raghupathi

To estimate the settlement of the structure placed on fly ash embankments or fills, one-dimensional consolidation tests on undisturbed sample from the reclamation fills gave values of co efficient of consolidation, cV of the order of 0.57-1.14cm2/min ( d in the range of 0.75 to 1.3 g/cm3). But the actual in-situ values are much higher (around 3-10 times the laboratory values). Since primary consolidation for fly ash will be completed by about one minute, it is difficult to take the time compression readings manually for cV calculations using classical deformations Vs time plots. These high rates of consolidation suggest that in most cases primary consolidation will be practically complete when the fill construction is over. This high rate of consolidation of fly ash is favorable particularly for its use as embankment and reclamation fills. Equally important is the secondary consolidation, which accounts for 20- 30% of the total compression, which depends on the nature of the fly ash and the duration of curing. The coefficient of secondary consolidation values decrease with curing time due to age hardening of fly ash. They are also highly dependent on the pozzolanic activity of fly ash that depends on the free lime content, carbon content and chemical composition of the glass phases. Another important factor, which influences the compressibility of ash, is its initial density or void ratio. Typical range of values for cc is presented in Table 4 (Sridharan et al 1996).
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