Ash contents

Ash is the organic matter-free (or carbonaceous matter free) residue that remains after combustion of a fuel oil at a specified high temperature (ASTM D-482, IP 4). 

Depending on the use of the fuel, ash composition has a considerable bearing on whether or not detrimental effects will occur. However, distillate fuels tend to contain only negligible amounts of ash but pick up ash-forming constituents during transportation from the refinery. Water transportation, in particular, presents many opportunities for fuel oils to be contaminated with ash-forming contaminants (seawater, dirt, and scale rust). 

The ash-forming constituents in distillate fuel (ASTM D 2880) are typically so low that they do not adversely affect gas turbine performance, unless such corrosive species as sodium, potassium, lead, or vanadium are present. However, there are recommendations for the storage and handling of these fuels (ASTM D-4418) to minimize potential contamination. 

The sample of filler or pigment is dried at 105°C to remove water and then ashed at 900-1000°C for a total 30 minutes. This method is mostly used for mineral fillers. 

The ash in carbon black is determined after drying at 125°C in a 550°C muffle furnace. The duration in the furnace is up to 16 hours depending on crucible type. 

The furnace treatment is continued until a constant weight is obtained unlike in the previous standard where constant (short) ashing time is used. The method permits the use of a microwave furnace which typically shortens the time to 2 to 6 hours. 

When the instruments are available, the above methods can be replaced by thermogravimetric analysis which is more informative and simpler to conduct. 

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Reducing ash content and Increasing anti-oxidant and dispersant efficiencies are among the goals needed to improve the quality of future lubricants. 

Ash content EN 7 (M07-045) ISO 6245 ASTM D 482 Weight of residue from total combustion... 

In Example 7.6 we found that an analysis for the inorganic ash content of a breakfast cereal required a sample of 1.5 g to establish a relative standard deviation for sampling of 2.0%. How many samples are needed to obtain a relative sampling error of no more than 0.80% at the 95% conhdence level ... 

Environmental considerations also were reflected in coal production and consumption statistics, including regional production patterns and economic sector utilization characteristics. Average coal sulfur content, as produced, declined from 2.3% in 1973 to 1.6% in 1980 and 1.3% in 1990. Coal ash content declined similarly, from 13.1% in 1973 to 11.1% in 1980 and 9.9% in 1990. These numbers clearly reflect a trend toward utilization of coal that produces less SO2 and less flyash to capture. Emissions from coal in the 1990s were 14 x 10 t /yr of SO2 and 450 x 10 t /yr of particulates generated by coal combustion at electric utiUties. The total coal combustion emissions from all sources were only slightly higher than the emissions from electric utiUty coal utilization (6). 

Most of the renewable carbon sources Hsted in Table 8 have carbon contents near this value. When adjusted for moisture and ash contents, it is seen that with the exception of the sludge sample, the carbon contents are slightly higher than that of cellulose, but span a relatively narrow range. 

Specific gravity is the most critical of the characteristics in Table 3. It is governed by ash content of the material, is the primary deterrninant of bulk density, along with particle size and shape, and is related to specific heat and other thermal properties. Specific gravity governs the porosity or fractional void volume of the waste material, ie. 

The tiansition from a choice of multiple fossil fuels to various ranks of coal, with the subbituminous varieties a common choice, does in effect entail a fuel-dependent size aspect in furnace design. A controlling factor of furnace design is the ash content and composition of the coal. If wall deposition thereof (slagging) is not properly allowed for or controlled, the furnace may not perform as predicted. Furnace size varies with the ash content and composition of the coals used. The ash composition for various coals of industrial importance is shown in Table 3. 

The water—carbon slurry formed in the quench vessel is separated from the gas stream and flows to the carbon recovery system needed for environmental reasons and for better thermal efficiency. The recovered carbon is recycled to the reactor dispersed in the feedstock. If the fresh feed does not have too high an ash content, 100% of the carbon formed can be recycled to extinction. 

The moisture content of freshly mined lignitic coals can be as high as 73%, but it is usually 30—65%. The more mature, consoHdated coals have lower moisture contents and thus a higher heating value. Figure 2 shows moisture and ash contents, as well as net heating values for lignitic coals from the world s principal deposits (19). 

Preparing for mining in the United States involves studying cores drilled initially on 1.6 km centers and later at 1.5-3 cores/km (4-8 cores/mi ), depending on the occurrence of discontinuities. The actual mining takes into account the variation of deposit properties in terms of percent moisture, ash composition, ash content, and grindabiHty as a function of moisture (9). 

Briquettes bum similarly to bituminous coal, although some tend to disintegrate on combustion. Alow (<6-7%) ash content increases the possibility of disintegration. Normal combustion depletes the combined oxygen and volatile matter in the coal quiddy, effectively changing its composition and combustion behavior, making control of combustion difficult. 

Operating parameters of this German plant, on the basis of one cubic meter of raw gas, iaclude 0.139 m O2, 0.9 kg briquettes, 1.15 kg steam, 1.10 kg feed water, 0.016 kWh, and 1.30 kg gas Hquor produced. Gasifier output is 1850 m /h and gas yield is 1465 m /t dry, ash-free coal. The coal briquettes have a 19% moisture content, 7.8% ash content (dry basis), and ash melting poiat of 1270°C. Thermal efficiency of the gas production process is about 60%, limited by the quaHty and ash melting characteristics of the coal. Overall efficiency from raw coal to finished products is less than 50%. 

Fumaric acid is sold as resia-grade and food-grade. The general sales specification under which resia-grade fumaric acid is sold ia the United States specifies white, crystalline granules with a minimum assay of 99.6% and maximum ash content of 0.05%. The moisture specification is 0.3% maximum with < 10 ppm heavy metals. The color of a 5% solution ia methanol is to be less than 10 APHA. Food-grade fumaric acid calls for somewhat lower impurity levels. Particle size and particle size distribution are important ia many appHcations. 

Significant use properties of poly(ethylene oxide) are complete water solubiHty, low toxicity, unique solution rheology, complexation with organic acids, low ash content, and thermoplasticity. 

Piebaked anodes aie produced by molding petroleum coke and coal tar pitch binder into blocks typically 70 cm x 125 cm x 50 cm, and baking to 1000—1200°C. Petroleum coke is used because of its low impurity (ash) content. The more noble impurities, such as iron and siUcon, deposit in the aluminum whereas less noble ones such as calcium and magnesium, accumulate as fluorides in the bath. Coal-based coke could be used, but extensive and expensive prepurification would be required. Steel stubs seated in the anode using cast iron support the anodes (via anode rods) in the electrolyte and conduct electric current into the anodes (Fig. 3). Electrical resistivity of prebaked anodes ranges from 5-6 Hm anode current density ranges from 0.65 to 1.3 A/crn. ... 

In 1990, a test using scrap tires (2x2 in. I DE) to generate steam for electricity was conducted at the Elexsys plant. The I DE replaced 20% of the plant s coal. Results showed that IDE is an environmentally sound fuel. Particulate emissions were reduced by the lower ash content of IDE, volatile organic compounds (VOC) were reduced because of more efficient burning of I DE compared to coal, and carbon dioxide emissions were reduced because I DE contains half the fixed carbon found in coal. Nitrogen oxide, chlorine emissions, and metals were also reduced, and ferrous metals and dioxins were nondetectable (7). 

In converting ESBR latex to the dry mbber form, coagulating chemicals, such as sodium chloride and sulfuric acid, are used to break the latex emulsion. This solution eventually ends up as plant effluent. The polymer cmmb must also be washed with water to remove excess acid and salts, which can affect the cure properties and ash content of the polymer. The requirements for large amounts of good-quaUty fresh water and the handling of the resultant effluent are of utmost importance in the manufacture of ESBR and directly impact on the plant operating costs. 

Ash and Inorganic Constituents. Ash may be measured gravimetdcaHy by incineration in the presence of sulfudc acid or, more conveniendy, by conductivity measurement. The gravimetric result is called the sulfated ash. The older carbonate ash method is no longer in use. Ash content of sugar and sugar products is approximated by solution conductivity measurements using standardized procedures and conversion factors. 

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