Coal and Ash

The reactor effluent is separated by conventional distillation into recycle solvent, light gases, to 537°C bp distillate, and a heavy vacuum bottoms stream containing unconverted coal and ash. The recycle solvent is hydrogenated in a separate reactor and sent back to the Hquefaction reactor. 

Several developments are being pursued to utilize coal directly, ie, automation of controls, coal and ash handling equipment for smaller stoker and pulverized coal-fired units, design of packaged boiler units, and pollution control equipment. In the cement industry coal firing has been used, because the sulfur oxides react with some of the lime to make calcium sulfate in an acceptable amount. 

Apart from the provision of various permutations of (chemical-based) boiler water programs, it is common to find water treatment companies supplying value adding chemicals and services in other boiler plant-related areas where their expertise in applied chemical technology can deliver additional economic benefit. Such areas typically include cleaning services for boiler waterside and fireside and the provision of fuel treatments and combustion additives, dust suppressants (for coal and ash handling), acids, and cleaner products. 

Hydrogen introduced after removal of unreacted coal and ash would come in contact with only 25 percent of the sulfur content of the as-fed coal. 

Atlantic Richfield Company, Arco has developed several conventional technologies for sulfur removal from coal and ashes and for manufacturing oil-coal mixed fuels, prior to becoming involved in BDS. Their patent entitled, Biodesulfurization of carbonaceous materials [16] was developed for the coal application, but nevertheless was extrapolated for application to petroleum desulfurization as well. 

Analysis of Coal and Ash Samples Ultimate Analysis - Utah II Bituminous Supplied by EER. Inc. 

The second program, funded by the U.S. Bureau of Mines, is concerned with the fate of the various toxic trace elements present when coal is burned in power plants. Coals and ashes from experimental combustors and power plants are collected and chemically analyzed. Comparing the amount of a trace element in a coal with the amount found in the ash resulting from the combustion of that coal allows us to determine the maximum amount of that element that could be emitted into the environment via the power plant stacks. 

The next experiments are conducted on a 500-pound-per-hour combustor. This combustor, which simulates commercial practice, is shown in Figure 2. It is a wall-fired, dry-bottom unit which uses cyclone ash collection. Where possible both coal and ash samples are obtained from commercial power plants to verify the results from the experimental combustors. The combination of the two programs will hopefully give... 

Coal and Ash Analysis. The coal and ash samples were separated into 20-40 g representative samples in the laboratory by a small riffle splitter. These samples were then pulverized with a mortar and pestle. The moisture content was determined by weighing the sample, drying it at 103 °C, and then reweighing it. These samples were kept in a desiccator and were subsequently used for the mercury analysis. 

The permanganate solutions obtained from both the coal and ash samples were analyzed by the direct aeration flameless atomic absorption procedure. The concentration in each sample was calculated from the measured mercury value, the blank concentration in the permanganate solutions, and the weight of the samples. 

Hg and electrostatic, 0.159 ppm Hg. The coal and ash concentrations are plotted in Figure 4 for those tests where at least one ash sample was collected. During this study the electrostatic ash always had a higher mercury concentration than the original coal, and the bottom ash always had a mercury concentration less than that of the original coal. 

The results of the mass balance are summarized in Table VI. The ratio of the mercury found in the gas stream to the amount of mercury released from the coal but not recovered in the ash is given in the third column. The average of this ratio is 1.19, with a standard deviation of 0.24. Within one standard deviation unit there is not a significant difference between the measured ratio and the expected ratio of 1.0. Therefore, based on 14 ratios at one plant, there is not a statistically significant difference between the total mercury found in the stack gas and the amount expected in the stack gas from the coal and ash determinations. Dual tests 13 and 14 showed close ratios of 0.88 and 0.95. 

The two highest ratios, from tests 3 and 7, showed the greatest deviation from the expected norm of 1.0. Results from these tests showed a larger amount of mercury in the stack gas stream than was expected from the coal and ash analysis. These two tests were the first two tests... 

Name of Coal and Ash Volatile CHONS cation International Class (dry basis) Matter % % % % % Temperature... 

The reactor is the key to the versatility of the H-Coal process. Figure 3 is a simplified diagram of the reactor. The concept involves a catalyst bed that is kept in an expanded or ebullated state by charging the feed and additional recycle oil to the bottom of the reactor. The products, including unreacted coal and ash, flow through the catalyst and are removed from the reactor at a point above the top of the catalyst bed. An external separator removes gaseous products and recycle hydrogen from the liquid. 

To pursue this issue, the coal and ash samples were examined under higher modulation and increased gain to enhance the signal-to-noise in the ESR spectra the results are shown in Figure 6. Of special interest are the broad resonance at low field (left side of figure), the four sharp... 

Microwave-assisted digestion has been applied to other types of samples such as ceramics [198,199], air particulate matter [200-202], polymers [203,204], lithographic materials [205], coal and ash [206], among others. As with the previous samples, the main purpose was the determination of their metal contents. The results provided by microwave-assisted digestion are similar to those obtained with conventional methods. 

In technical furnaces the radiation from soot, coal and ash particles has to be considered as well as the gas radiation. Then the scattering of radiation by the suspended particles becomes important, alongside absorption and emission. P. Biermann and D. Vortmeyer [5.67], as well as H.-G. Brummel and E. Kakaras [5.68] have developed models for this. A summary can be found in [5.69] and in [5.37], p. 652-673. The calculations of heat transport in furnaces has been dealt with by W. Richter and K. Corner [5.70] as well as H.C. Hottel and A.F. Sarohm [5.48],... 

Figure 1. Relationship between K concentration in the coal and ash content for 34 coals from Eastern Kentucky. R 0.86.

Higher coolant outlet temperatures allow for a smaller reaction volume and a higher coal throughput, respectively. The intermediate heat exchanger is required because of the difficulties expected when handling coal and ash within the reactor containment Furthermore coal gasifiers have a shorter lifetime than steam reformers which means that the former should be outside the nuclear plant for shutoff and repair purposes [69]. 

Coal-fired power plants are well-known sources of SO2, NO2, heavy metals and other elements (Fig. 1). Lichens applied as monitors near coal-fired power stations in Portugal were found to accumulate heavy metals such as Fe, Co, Cr, and Sb, originating in coal and ash particles drifting through the air and positioned on the thallus (Freitas, 1994). 

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