Effect Of Kaolin Addition Research Articles

Effect of Kaolin Addition on Combustion Behavior of Zhundong Coal Pellet Using Flame Emission Spectroscopy

ABSTRACT Kaolin, as an adsorbent, has been proven to be effective in inhibiting sodium release during high alkali coal combustion thereby alleviating severe slagging and fouling problems. Understanding the co-firing behavior of Zhundong coal with kaolin additives is essential for Zhundong coal utilization. In this study, the effect of kaolin additive on the combustion behavior of two Zhundong coals with different Na contents was investigated based on image analysis and flame emission spectroscopy (FES) method. Spectral and image results were able to distinguish the three stages of coal combustion. The addition of kaolin impacted all combustion stages for both types of coal. The results show the volatile combustion time of the blended coal sample was shortened, while the char burnout time was prolonged, which was attributed to the ash suppression effect. The two coals presented similar decrease trends with different blending ratios in terms of sodium concentration, pellet surface temperature, and thermal radiation. However, the changes were no longer evident after the blending ratio reached 8% and 12%. The replacement of combustible components in the coal by the kaolin altered the mineral fraction of the ash and thus affected the heat and mass transfer. Combining the online measurement results and the analysis of the ash fusion characteristics, the suggested addition of kaolin was 8% and 12% respectively.

Effect of kaolin addition on the sinter-crystallisation kinetics of compacts of a crystallising frit

Non-isothermal techniques were used to study the sintering and crystallisation kinetics of an anorthoclase- and diopside-devitrifying frit and mixtures of this frit with a commercial kaolin. Raising kaolin content was verified to delay sintering and crystallisation and to increase the degree to which both processes overlapped, which decreased the sinterability of the material. In addition, raising kaolin content lowered the resulting diopside content, which cancelled out for the mixture with 16 wt% kaolin, while the shape, size, and composition of the anorthoclase crystals also changed. The kinetic parameters of the sinter-crystallisation processes were determined, and a model was developed that appropriately describes sintering kinetics. The model assumes the process develops in two parallel, partly overlapping stages, each of which can be described by the Kohlrausch–Williams–Watts (KWW) relaxation function.

Effect of Kaolin Addition on the Sinter-Crystallisation Kinetics of Compacts of a Crystallising Frit

Effect of Kaolin Addition on the Sinter-Crystallisation Kinetics of Compacts of a Crystallising Frit

Effect of Kaolin Addition on Electrochemical Corrosion Resistance of Duplex 2205 Stainless Steel Embedded in Concrete Exposed in Marine Environment

Effect of Kaolin Addition on Electrochemical Corrosion Resistance of Duplex 2205 Stainless Steel Embedded in Concrete Exposed in Marine Environment

Effect of Kaolin Addition into Metakaolin Geopolymer Composite

AbstractIndustrially produced metakaolin may contain raw kaolin residues. Therefore, the aim of this work was to determine the influence of kaolin remains in the metakaolin on the final geopolymer ...

Effect of kaolin addition on alkali capture capability during combustion of olive residue

ABSTRACTThe effect of kaolin addition on the combustion characteristics of olive residue was investigated by thermogravimetric analysis (TGA) combined with Fourier-transform infrared (FTIR) spectrometer in parallel with ash characteristics were studied by X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyzer. The experiments were carried out by burning olive residue with 2%, 4% and 8% by wt. kaolin at 900°C. Results indicate that the addition of kaolin led to a decrease in the rate of weight loss during char combustion and hence an increase in CO emission. This was due to a decrease in burning quality caused by the dilution effect of kaolin in the mixture. The increase in HCl(g) and SO2(g) concentrations with kaolin addition observed in FTIR results evaluated together with XRF and XRD results demonstrates the pathway of reactions for the capture of potassium by kaolin and formation of high-melting-temperature kalsilite crystals. Potassium retention in ash was found to increase up to 4% kaolin content; however, no significant improvement in potassium retention was observed with further addition of kaolin owing to the abundant amounts of Al and Si introduced via kaolin. The results show that 4% kaolin is the optimum content at which the alkali index decreases below unity, indicating reduced tendency of fouling in combustion systems.

The effect of sintering time on recycled magnesia brick from kiln of the cement plant

This research aim was to investigate the effect of sintering time on reuse waste of magnesia brick from the rotary kiln of the cement plant. Reuse of the magnesia brick was carried out by mixed the kaolin as the binder. Spent refractory was used as aggregate with the composition of 85% spent refractory and 15% kaolin clay, respectively. The reuse brick then was molded with the size of 5x5x5 cm using hydraulic press under a load of 10 tons in order to forms green body. Green body then dried and sintered at 1200 °C with time variation of 2 hours, 4 hours, 6 hours, 8 hours and 10 hours, respectively. Thus, for comparison reuse brick was tested to its apparent porosity, the bulk density, and Cold Crushing Strength (CCS). The effect of kaolin addition as binder was also discussed.

Characterisation of volatile organic sulphur compounds release during coal pyrolysis in inert, hydrogen and CO2 atmosphere

The effects of CO2 atmosphere on the distribution of volatile organic sulphur compounds during coal pyrolysis and the effect of kaolin addition were studied. Sulphur compounds release was determined by atmospheric pressure-temperature programmed reduction “on-line” coupled with MS (AP-TPR/MS) and “off-line” coupled with GC/MS after thermal desorption (AP-TPR-TD-GC/MS). The results show that thiophene and methyl and ethyl substituted analogues were released between 400 and 500°C, while relatively more complex organic sulphur compounds such as benzothiophene and methyl benzothiophene evolved at higher temperature. In CO2, thiophenes evolved at lower temperature due to its more reactive and oxidative character. With kaolin addition, an increase in most registered volatile organic sulphur compound amounts was noticed both in inert and CO2 gas, due to the catalytic effect of kaolin.

The effect of kaolin addition on the characteristics of a sintered diatomite composite support layer for potential microfiltration applications

Abstract Porous ceramic membranes have lately become a subject of special interest due to their outstanding thermal and chemical stability. We prepared a sintered diatomite composite support layer with the addition of kaolin, which enhanced the mechanical strength of the diatomite composite matrix while retaining acceptable permeation properties. We also discussed whether the sintered diatomite composite support layer could serve as a separation layer to minimize processing difficulties as well as the feasibility of using a sintered diatomite composite layer without a separation layer as a porous ceramic membrane for microfiltration. The pore characteristics of the sintered diatomite specimens were studied by scanning electron micrography, mercury porosimetry, and capillary flow porosimetry.

Effect of kaolin addition on the performance of controlled low-strength material using industrial waste incineration bottom ash

Effect of kaolin addition on the performance of controlled low-strength material using industrial waste incineration bottom ash

Effect of kaolin addition on ash characteristics of palm empty fruit bunch (EFB) upon combustion

Palm empty fruit bunch (EFB), a by-product of the palm oil industry, is being recognized as one of the most potential kinds of biomass for energy production in Thailand. However, it has been reported that, in combusting EFB in boilers, some compounds evolving from abundant alkali metals in EFB into gas-phase condense and deposit on low-temperature surfaces of heat exchange equipment, causing fouling and corrosion problems. To come up with a solution to impede the deposition, kaolin, which is abundant in kaolinite (Al 2Si 2O 5(OH) 4), is employed to capture the alkali metal vapours eluding from the combustion region. The experiments were designed to simulate the combustion situations that may take place when kaolin is utilized in two different approaches: premixing of kaolin with EFB prior to combustion and gas-phase reaction of volatiles from EFB with kaolin. The amounts of kaolin used were 8% and 16% by weight based on dry weight of EFB, which were equivalent to one and two times of the theoretical kaolin requirement to capture all potassium originally present in the EFB. The furnace temperatures used for EFB combustion were 700–900 °C and ashes were analyzed by XRF and XRD. The results revealed that, under the kaolin premixing condition, 8% kaolin addition was sufficient to capture the potassium compounds at low temperature, i.e. 700 and 800 °C. However, when the temperature was increased to 900 °C, 16% kaolin addition was needed to completely capture the potassium compounds. The results from gas-phase experiments showed that kaolin can capture volatile potassium at maximum 25% at 900 °C. The XRD results showed, for both experimental cases, the evidence of formation of the high melting temperature potassium-alumino-silicates, which confirmed the reaction of potassium compounds with kaolin. The study also suggests that the premixing method is better than the other because of its higher overall capture efficiency.

On the application of surface ionization detector for the study of alkali capture by kaolin in a fixed bed reactor

Alkali metals, mainly potassium, together with other ash forming inorganic components in biomass are believed to be responsible for bed agglomeration in fluidized bed boilers burning biomass. A solution to the problem is to capture alkali vapor released from the fuel during combustion by inorganic solid additives such as kaolin. In this study, the capture of vaporous potassium chloride was investigated in a fixed bed reactor equipped with an on-line alkali detector. The detector, which is based on surface ionization, is capable of operating at alkali metal concentrations as low as those encountered after reaction with kaolin during biomass combustion (of the order of 1 ppb). Various experiments of KCl capture by kaolin powder were made at a reactor temperature of 850 °C. Kaolin removed up to 99% of alkali species in gas phase. The efficiency slightly decreased when KCl concentration decreased. The effect of kaolin addition on the release of alkali metals during wood combustion was studied at 650 °C in air. During pyrolysis, the alkali metal release increased slightly when kaolin was mixed with the wood due to the release of alkali metal impurities in the kaolin additive. The alkali metal release during char combustion was reduced to approximately 50% of the original value. The reduction increased as the amount of kaolin addition increased. Overall, the addition of kaolin suppressed the alkali metal release from the wood by approximately 20%.

Effect of Kaolin Addition on Properties of Forsterite Porcelain

The stability of the forsterite porcelian in hydrogen at high temperatures, which is required in the application of the forsterite porcelain to a high frequency insulator, is governed by additives used to promote sintering. Among several additives examined kaolin has the effect to make the porcelain stable in hydrogen at high temperatures, so giving it favorable properties for Mo-Mn metallizing processed under such conditions.In this paper 0-10% of kaolin was added to forsterite porcelains which were prepared from Fukushima siliceous stone and sea-water magnesia in the molar ratio of MgO: SiO2=2:1.By the addition of kaolin the temperature range for sintering was remarkably extended and the firing shrinkage was almost constant within this range. The coefficient of linear thermal expansion decreased with the increase of added kaolin, and no considerable change was found by repeated heat treatments. With the increase of kaolin content from 0 to 10%, the softening temperature under load lowered to 1160°C from 1280°C. The electric resistance at elevated temperatures lowered gradually, but was still sufficiently high for practical use. The flexural strength decreased and the modulus of elasticity lowered gradually in the temperature range from room temperature to 300°C with the increase of kaolin content. The modulus of elasticity, however, became larger with the rise of temperature in this temperature range.Within 5% of kaolin added, the dielectric constant and dielectric loss were unvaried and these values were excellent for the high frequency insulator.The result of X-ray diffraction gave only the pattern of the forsterite. By microscopic observation, forsterite crystal grain changed from allotriomorphic into idiomorphic and glass matrix increased with the kaolin content.It is concluded that the addition of 2.5-5.0% of kaolin was most suitable for preparing the forsterite porcelain for this purpose.