A mathematical model to characterize effect of silica content in the boiler fly ash on erosion behaviour of boiler grade steel

In order to obtain the adsorption mechanism and failure characteristics of CO2 adsorption by potassium-based adsorbents with different supports, five types of supports (circulating fluidized bed boiler fly ash, pulverized coal boiler fly ash, activated carbon, molecular sieve, and alumina) and three kinds of adsorbents under the modified conditions of K2CO3 theoretical loading (10%, 30%, and 50%) were studied. The effect of the reaction temperature (50 °C, 60 °C, 70 °C, 80 °C, and 90 °C) and CO2 concentration (5%, 7.5%, 10%, 12.5%, and 15%) on the adsorption of CO2 by the adsorbent after loading and the effect of flue gas composition on the failure characteristics of adsorbents were obtained. At the same time, the microscopic characteristics of the adsorbents before and after loading and the reaction were studied by using a specific surface area and porosity analyzer as well as a scanning electron microscope and X-ray diffractometer. Combining its reaction and adsorption kinetics process, the mechanism of influence was explored. The results show that the optimal theoretical loading of the five adsorbents is 30% and the reaction temperature of 70 °C and the concentration of 12.5% CO2 are the best reaction conditions. The actual loading and CO2 adsorption performance of the K2CO3/AC adsorbent are the best while the K2CO3/Al2O3 adsorbent is the worst. During the carbonation reaction of the adsorbent, the cumulative pore volume plays a more important role in the adsorption process than the specific surface area. As the reaction temperature increases, the internal diffusion resistance increases remarkably. K2CO3/AC has the lowest activation energy and the carbonation reaction is the easiest to carry out. SO2 and HCl react with K2CO3 to produce new substances, which leads to the gradual failure of the adsorbents and K2CO3/AC has the best cycle failure performance.

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Fly Ash, from Recycling to Potential Raw Material for Mesoporous Silica Synthesis

Nanomaterials ◽

10.3390/nano10030474 ◽

2020 ◽

Vol 10 (3) ◽

pp. 474 ◽

Cited By ~ 4

Author(s):

Marius Gheorghe Miricioiu ◽

Violeta-Carolina Niculescu

Keyword(s):

Fly Ash ◽

Mesoporous Silica ◽

Energy Demand ◽

Power Plants ◽

Circulating Fluidized Bed ◽

Structural Characteristics ◽

Silica Content ◽

Raw Material ◽

Hard Coal ◽

High Level

In order to meet the increasing energy demand and to decrease the dependency on coal, environmentally friendly methods for fly ash utilization are required. In this respect, the priority is to identify the fly ash properties and to consider its potential as raw material in the obtaining of high-value materials. The physico-chemical and structural characteristics of the fly ash coming from various worldwide power plants are briefly presented. The fly ash was sampled from power plants where the combustion of lignite and hard coal in pulverized-fuel boilers (PC) and circulating fluidized bed (CFB) boilers was applied. The fly ash has high silica content. Due to this, the fly ash can be considered a potential raw material for the synthesis of nanoporous materials, such as zeolites or mesoporous silica. The samples with the highest content of SiO2 can be used to obtain mesoporous silica materials, such as MCM-41 or SBA-15. The resulting mesoporous silica can be used for removing/capture of CO2 from emissions or for wastewater treatment. The synthesis of various porous materials using wastes would allow a high level of recycling for a sustainable society with low environmental impact.

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EFFECT OF MIXING PROPORTION ON COMPRESSIVE STRENGTH OF FLY-ASH BASED GEOPOLYMER PASTE AND MORTAR USING TAGUCHI’S METHOD

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2015.72 ◽

2015 ◽

Vol 2 (1) ◽

Author(s):

Sajid Khan Afridi ◽

Vanissorn Vimonsatit

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Elevated Temperatures ◽

Three Dimensional ◽

Silica Content ◽

Polymeric Chain ◽

Low Carbon ◽

Solid Ratio ◽

Mix Proportion ◽

Alkali Activated

Alkali activated pozzolan are known low carbon cementitious binders which can be used to replace cement. The material is also known as geopolymer because of its three dimensional polymeric chain and ring like structure consisting silica and alumina. A common type of pozzolan used is fly ash because of its rich silica content; therefore the term alkali activated fly-ash based binders is adopted. Despite much research and development of this material, there is no specific standard for design mix proportion. This research used the Taguchi’s design of experiment method to determine the optimum mix proportion of alkali activated fly ash based cement paste and mortar. Four factors were considered in the tests, silica fume, sand to cementitious ratio, liquid to solid ratio, and percentage of superplasticiser. Tests were conducted on the 9 batches of alkali activated fly-ash based paste and mortar samples to determine the compressive strength under ambient condition. Tests were also conducted to determine the residual strength of the samples after exposed to elevated temperatures. ANOVA analysis of the test results revealed the main factors contribution on the tested properties and led to the determination of the optimum design proportion of the factors considered in these tests.

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A model to predict erosion on mild steel surfaces impacted by boiler fly ash particles

Wear ◽

10.1016/j.wear.2004.03.007 ◽

2004 ◽

Vol 257 (5-6) ◽

pp. 612-624 ◽

Cited By ~ 46

Author(s):

J.G Mbabazi ◽

T.J Sheer ◽

R Shandu

Keyword(s):

Fly Ash ◽

Mild Steel ◽

Steel Surfaces ◽

Boiler Fly Ash

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Unburned carbon in the circulating fluidised bed boiler fly ash

Chemical and Process Engineering ◽

10.2478/v10176-011-0020-8 ◽

2011 ◽

Vol 32 (4) ◽

pp. 255-266 ◽

Cited By ~ 4

Author(s):

Rafał Kobyłecki

Keyword(s):

Fly Ash ◽

Separation Efficiency ◽

Unburned Carbon ◽

Fuel Particle ◽

Fluidised Bed ◽

Bed Temperature ◽

Grid Design ◽

Cfbc Fly Ash ◽

Boiler Fly Ash ◽

Circulating Fluidised Bed

Unburned carbon in the circulating fluidised bed boiler fly ash The paper describes the results of various actions and industrial tests conducted in order to decrease the content of unburned carbon in the fly ash of a circulating fluidised bed combustor (CFBC). Several attempts to improve the situation were made and the effects of several parameters on the unburned carbon content in the fly ash were investigated (e.g. bed temperature, cyclone separation efficiency, fuel particle size distribution, boiler hydrodynamics, grid design, and fuel data). Unfortunately, no satisfactory solution to these problems was found. Probably, apart from attrition and char fragmentation, additional factors also contributed to the formation of unburned carbon in the CFBC fly ash.

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Erosion-corrosion of coatings by biomass-fired boiler fly ash

Wear ◽

10.1016/0043-1648(95)06598-9 ◽

1995 ◽

Vol 188 (1-2) ◽

pp. 40-48 ◽

Cited By ~ 33

Author(s):

Bu-Qian Wang

Keyword(s):

Fly Ash ◽

Erosion Corrosion ◽

Boiler Fly Ash

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Comparison of strength and durability characteristics of a geopolymer produced from fly ash, ground glass fiber and glass powder

Materiales de Construcción ◽

10.3989/mc.2017.05416 ◽

2017 ◽

Vol 67 (328) ◽

pp. 136 ◽

Cited By ~ 9

Author(s):

H. Rashidian-Dezfouli ◽

P. R. Rangaraju

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Portland Cement ◽

Glass Fiber ◽

Glass Powder ◽

Silica Content ◽

Ground Glass ◽

Alkali Silica Reaction ◽

Strength And Durability ◽

Cement Mixtures

Strength and durability characteristics of geopolymers produced using three precursors, consisting of fly ash, Ground Glass Fiber (GGF), and glass-powder were studied. Combinations of sodium hydroxide and sodium silicate were used as the activator solutions, and the effect of different sodium and silica content of the activators on the workability and compressive strength of geopolymers was investigated. The parameters used in this study were the mass ratio of Na2O-to-binder (for sodium content), and SiO2-to-Na2O of the activator (for silica content). Geopolymer mixtures that achieved the highest compressive strength from each precursor were assessed for their resistance to alkali-silica reaction and compared against the performance of portland cement mixtures. Test results revealed that GGF and fly ash-based geopolymers performed better than glass-powder-based geopolymer mixtures. The resistance of GGF-based and fly ash-based geopolymers to alkali-silica reaction was superior to that of portland cement mixtures, while glass-powder-based geopolymer showed inferior performance.

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Erosion Analysis on Copper Fly-Ash Composite

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.b1082.1292s219 ◽

2019 ◽

Vol 9 (2S2) ◽

pp. 568-570

Keyword(s):

Fly Ash ◽

Powder Metallurgy ◽

Solid Particle ◽

Solid Particle Erosion ◽

Particle Erosion ◽

Erosion Behaviour ◽

Input Parameters

In the present study, solid particle erosion behaviour on copper – fly ash composite is studied. Composite with addition of 2.5 (wt.%) fly ash as reinforcement is prepared through powder metallurgy(P/M) technique. Solid particle erosion studies were carried out by varying the input parameters such as erodent velocity and erosion time. The results revealed that addition of fly ash reduced the resistance to erosion.

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Mechanical Properties of Geopolymer Concrete with Flyash and Metakaolin

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.a1180.109119 ◽

2019 ◽

Vol 9 (1) ◽

pp. 3863-3868 ◽

Cited By ~ 1

Keyword(s):

Mechanical Properties ◽

Fly Ash ◽

Sodium Hydroxide ◽

Silica Content ◽

Geopolymer Concrete ◽

Long Term Effects ◽

Concrete Production ◽

High Silica ◽

By Products

Trials has been made to produce efficient GPC which gives maximum strength. By-Products from industries such as Fly-Ash, Metakaolin and GGBS can be used in concrete replacement which in-turn reduces carbon-di-oxide (CO2 ) emission affecting to green house. Using the above said products also leads to reduction of water demand in concrete and also shows comparatively no effects on long term effects in concrete, these by-products can effectively be used in concrete production. The high silica content in Fly-Ash and Metakaolin increases the bonding in concrete which in-turn increases the mechanical properties of concrete. Geopolymer concrete of M50 grade was proposed to be produced using fly-ash and Metakaolin instead of cement.Alklai solutions Sodium Hydroxide (NaOH), Sodium Silicate (Na2SiO3) were replaced with water for better bonding and mixing. Molarity of Sodium Hydroxide with 10M and 12M was considered for this study. Ratio of Alkaline solution were considered as 1:2,1:2.5&1:3 to determine the optimum ratio which gives effective strength. In this experimental study, tests were carried on concrete specimens with percentage replacement of Fly-Ash with Buff Metakaolin in variable percentages of 20,40,60,80&100. Mechanical properties of concrete specimens were studied and were compared with control mix results.

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