Coal ash fusion temperatures—New characterization techniques, and implications for slagging and fouling

Wall, Terry; Creelman, Robert A.; Gupta, R.P.; Gupta, Sushil K.; Coin, C.; Lowe, A.

doi:10.1016/s0360-1285(98)00010-0

Cited by 88 publications

(47 citation statements)

References 4 publications

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“…The minimum endothermic temperatures evaluated in this way are much lower than the corresponding initial deformation temperatures obtained from ash fusion tests. This is in agreement with the findings of Wall et al [8] who used alternative laboratory techniques to conclude that the initial deformation temperature cannot be regarded as the lowest temperature for ash to soften. On the other hand, the minimum endothermic temperature cannot automatically be assumed to represent the temperature where melting first starts.…”

Section: Cacosupporting

confidence: 92%

“…Commonly used analytical techniques include testing the fusion characteristics of ash, measurements of ash viscosity and estimation of indices based on ratios of elemental oxides [8][9][10]. Despite the limitations associated with these techniques, they are still widely used to assess the tendency of various coals to slag and foul boiler heat transfer surfaces and have also been extended to biomass fuels for evaluation of the same [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Prediction of biomass ash fusion behaviour by the use of detailed characterisation methods coupled with thermodynamic analysis

Rizvi

Xing

Pourkashanian

et al. 2015

Fuel

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. AbstractAsh deposition such as slagging and fouling on boiler tube surfaces is an inevitable, though undesirable consequence of burning solid fuels in boilers. The role of fuel characteristics, in affecting the form and severity of the problem, is significant. In recent years, biomass fuels have gained increasing popularity as an environmentally friendly source of energy in power plants all over the world. This study is based on characterising the fusion behaviour of four biomass fuels (pine wood, peanut shells, sunflower stalk and miscanthus) using ash fusion temperature (AFT) tests, simultaneous thermal analysis (STA) of fuel ashes, calculation of empirical indices and predicting ash melting behaviour with the help of thermodynamic equilibrium calculations. The AFT results failed to show any clear trend between fusion temperature and high alkali content of biomass. STA proved useful in predicting the different changes occurring in the ash. Empirical indices predicted high slagging and fouling hazards for nearly all the biomass samples and this was supported by the possible existence of a melt phase at low temperatures as predicted by thermodynamic calculations.

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Section: Cacosupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Prediction of biomass ash fusion behaviour by the use of detailed characterisation methods coupled with thermodynamic analysis

Rizvi

Xing

Pourkashanian

et al. 2015

Fuel

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“…Due to these reasons, the ash fusion tests give no direct indication of the propensity of the heated ash to become sticky and cause agglomeration. Wall et al (1998) have attributed the difference between ash fusion temperatures for laboratory and combustion ash to the loss of potassium and reactions between the mineral residues at the higher temperatures experienced during actual combustion conditions. In case of co-firing straw and coal in a laboratory fluidized bed combustor, Lin et al (1999) have shown that the presence of high K 2 O in the straw ash led to rapid agglomeration in the bed.…”

Section: Chicken Litter Biomass (Lb)mentioning

confidence: 99%

Co-Firing Coal: Feedlot and Litter Biomass (Cfb and Clb) Fuels in Pulverized Fuel and Fixed Bed Burners

Annamalai¹,

Sweeten²,

Mukhtar³

et al. 2003

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Intensive animal feeding operations create large amounts of animal waste that must be safely disposed of in order to avoid environmental degradation. Cattle feedlots and chicken houses are two examples. In feedlots, cattle are confined to small pens and fed a high calorie grain-diet diet in preparation for slaughter. In chicken houses, thousands of chickens are kept in close proximity. In both of these operations, millions of tons of manure are produced every year. The manure could be used as a fuel by mixing it with coal in a 90:10 blend and firing it in an existing coal suspension fired combustion systems. This technique is known as co-firing, and the high temperatures produced by the coal will allow the biomass to be completely combusted. Reburn is a process where a small percentage of fuel called reburn fuel is injected above the NO x producing, conventional coal fired burners in order to reduce NO x . The manure could also be used as reburn fuel for reducing NO x in coal fired plants. An alternate approach of using animal waste is to adopt the gasification process using a fixed bed gasifier and then use the gases for firing in gas turbine combustors. In this report, the cattle manure is referred to as feedlot biomass (FB) and chicken manure as litter biomass (LB). The report generates data on FB and LB fuel characteristics. Co-firing, reburn, and gasification tests of coal, FB, LB, coal: FB blends, and coal: LB blends and modeling on cofiring, reburn systems and economics of use of FB and LB have also been conducted. The biomass fuels are higher in ash, lower in heat content, higher in moisture, and higher in nitrogen and sulfur (which can cause air pollution) compared to coal. Small-scale cofiring experiments revealed that the biomass blends can be successfully fired, and NO x emissions will be similar to or lower than pollutant emissions when firing coal. Further experiments showed that biomass is twice or more effective than coal when used in a reburning process. Computer simulations for coal: LB blends were performed by modifying an existing computer code to include the drying and phosphorus (P) oxidation models. The gasification studies revealed that there is bed agglomeration in the case of chicken litter biomass due to its higher alkaline oxide content in the ash. Finally, the results of the economic analysis show that considerable fuel cost savings can be achieved with the use of biomass. In the case of higher ash and moisture biomass, the fuel cost savings is reduced.

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“…Various laboratory methods have been developed to determine the slagging properties of coal ash, such as the ash fusion temperature and cone melting test, but these have not resulted in a good tool for selecting good coals [12]. Another widely used method is to multiply the basic to acidic oxides ratio (B/A) by the dry sulphur content (S) in coal, but this is only applicable when there is a strong correlation between the sulphur and iron contents, i.e.…”

Section: Introductionmentioning

confidence: 99%

Prediction of ash slagging propensity in a pulverized coal combustion furnace

Degereji

Ingham

et al. 2012

Fuel

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Coal ash fusion temperatures—New characterization techniques, and implications for slagging and fouling

Cited by 88 publications

References 4 publications

Prediction of biomass ash fusion behaviour by the use of detailed characterisation methods coupled with thermodynamic analysis

Prediction of biomass ash fusion behaviour by the use of detailed characterisation methods coupled with thermodynamic analysis

Co-Firing Coal: Feedlot and Litter Biomass (Cfb and Clb) Fuels in Pulverized Fuel and Fixed Bed Burners

Prediction of ash slagging propensity in a pulverized coal combustion furnace

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