Results for fly ash

Acoustic agglomeration—Continued results for fly ash aerosol, 250f small particulates,... 

Few comprehensive classification schemes for CCP exist. The American Society for Testing and Materials (ASTM 1994) classifies two catgories of fly ash (Class F and Class C) based upon chemical and physical properties of the fly ash (the total amount of Si + A1 + Fe, sulphate, loss on ignition). This classification system was developed for the use of fly ash as an admixture in concrete. More recently, new classification schemes have been developed that place emphasis on textural descriptions, the form of carbon (or char ), and the surface properties of fly ash (Hower Mastalerz 2001). These new classification schemes for fly ash may be the result of growing concern over mercury emissions from coal-fired boilers. Studies have shown that mercury adsorption onto the surface of fly ash particles is a function of both the total carbon content and the gas temperature at the point of fly ash collection (Hower et al. 2000). 

The amount of the tar in the gas and fly ash varies depending on process parameters. Gasification at high temperature and high ER results in a lower content of tars in the product gas. For fly ash the fuel properties and the gas Altering temperature seems to be the two crucial parameters. Table 2 shows the ranges for the measured tar contents in the gas and fly ash. 

On the other hand, any uncertainty in the composition and complex refractive index of fly ash particles is likely to be less than the uncertainty in the volume fraction distribution of fly ash particles. It was shown that, using detailed spectral data for fly ash particles, one may obtain significantly different results for radiative flux from the flame to the walls of large scale pulverized-coal furnace compared to the results predicted using wavelength-independent properties however, the difference is lost if the accurate number densities of fly ash and soot present near the walls are not available [52,250]. 

Furthermore, from Table 7.15 and BET analysis results (refer Figs. 6.38 and 6.39), Step-3 fusion of the fly ash yields significant increase in the pore characteristics (viz., area, diameter and volume) of the resulting products corresponding to NaOH/RFA ratios viz. 0.4 and 1.0. It can be noticed that the pore volume increases drastically up to 0.0285 cm /g (i.e., 1361 % of that for fly ash) for 1.0-F3. 

On the other hand, when the reaction temperature was increased fijrther to 400°C, the reactivity of the absorbent significantly dropped. It was previously reported that for absorbent prepared from coal fly ash, when the absorbent was dried at temperature above 400°C, the reactivity of the absorbent dropped due to the decomposition of the active materials in the absorbent [8]. Since the effect of drying the absorbent above 400°C is similar to exposing the absorbent to reaction temperature above 400°C, therefore it can be concluded that the active materials in absorbent prepared from oil palm ash also decompose at reaction temperature above 400°C resulting in lower reactivity. Apart from that, another possible explanation for the drop in the reactivity of the absorbent at 400°C could be due to the sintering of the absorbent that decreases the surface area of the absorbent. 

Tab. 3.7 Results for NIST SRM 1633a Coal Fly Ash using the self-verification principle of NAA (Byrne and Kucera 1997 Kucera et al. 1997)...

It is assumed that the moisture content of the soil has been determined to be approximately 50% under worst-case conditions. Using this information and the results from vendor tests, it has been determined that a minimum dose of one part solidification reagent to two parts soil is required for the migration control of lead. Testing has shown that the optimum solidification reagent mixture would comprise ca. 50% fly ash and ca. 50% kiln dust. Thus, ca. 7000 t (6364 T) each of fly ash and cement kiln dust would be required. The reagents would be added in situ with a backhoe. As one area of the soil is fixed, the equipment could be moved onto the fixed soil to blend the next section. It may be anticipated that the soil volume would expand by ca. 20% as a result of the fixation process. This additional volume would be used to achieve the required slope for the cap. An RCRA soil/clay cap placed over the solidified material is necessary to prevent infiltration and additional hydraulic stress on the fixed soil. It is estimated that the fixation would reduce lead migration by 40% and that the fixed soil may pass the U.S. EPA levels for lead. 

Some typical examples of pneumatic conveying characteristics for three different fly ash samples conveyed on the same long-distance test rig are presented in Figs 11,12 and 13. Some important information regarding these materials and results is summarized below. 

The above test-design and scale-up procedures have been applied to numerous long-distance systems (e.g., fly ash, pulverized coal) and have been found to provide good accuracy and reliability. Some examples of these results have been presented by Pan and Wypych (1992a) and Pan and Wypych (1994). The interested reader is referred to these papers for further details. The above procedures also have been used successfully to... 

When evaluating a material for the purpose of establishing dense-phase and long-distance suitability, it is important to undertake all the necessary tests (e.g., particle sizing, particle and bulk densities, fluidization and deaeration). Also, if possible, it is useful to compare such results with those obtained on previously conveyed similar materials (e.g., fly ash). However, it should be noted that such an evaluation only is a qualitative one and it is not possible to predict say, minimum air flows or pipeline pressure drop based on such data (i.e., pilot-scale tests normally are required to confirm minimum velocities, friction factors, etc., especially over long distances and for large-diameter pipes). 

To check the influence of PCB oil admixture to the fly ash on the thermodynamic conversion of the whole mixture, the calculations were done for various amounts of organic compounds. The results for power plant ash thermodynamic conversion with temperature rise and with oil-PCB s addition are shown in Fig.l (A and B). These figures show that chlorine appears in the form of HC1 with a characteristic content minimum in the temperature range 1300-1700 K. In the range of 1000 -3000 K the offgas is rich in hydrogen. Maximum value of H2 is determined by the methane decomposition, which occurs above 1200 K. Due to different the... 

As it can be seen from Figme 17, adsorption process is not playing an important role in color and COD abatement from the solution. Similar results were foimd for catalyst C2, C3, C4 and C5. The exception was the original fly ash. Figure 18 shows a small amoimt of dye adsorbed on the original fly ash, see curve (b). 

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