Carbon dioxide from coal

The Vision 21 program is focused on new concepts for coal-based energy production where modular plants could be configured to produce a variety of fuels and chemicals depending on market needs with virtually no environmental impact outside the plant s footprint. Membranes would be used to separate oxygen from air for the gasification process and to separate hydrogen and carbon dioxide from coal gas. 

Analysis necessary only for carbon dioxide from phosphate rock sources. b Analysis necessary only for carbon dioxide from coal gassification sources. 

Nandi, S. P., and P. L. Walker The Diffusion of Nitrogen and Carbon Dioxide from Coals of Various Ranks. Fuel 43, 385/393 (1964). 

As a consequence of this, there is now a major focus on the use of coal as a source for fuels and olefins. Coal has a far higher level of carbon than petroleum fuels and natural gas and this inevitably leads to higher emissions of carbon dioxide in the production of fuels and olefins. As a consequence there are research and development projects concerned with the capture of carbon dioxide from coal based operations and the geo-sequestration of the carbon dioxide. 

The combination of high value outputs, scale-effects and flexibility in general, may lead to a very efficient, cost-effective and clean overall system. Cost-effective means that the electricity produced has to compete with electricity from coal. For fair comparison the cost of clean electricity generation must be considered with a similarly low environmental burden. For instance, costs for removal or storage of the emitted carbon dioxide from coal plants have to be included. For electricity this inches an allowable cost price of 0.05 Euro/kWh. This value is the EU strategic goal and seems achievable for large advanced systems [5] where electrical efficiencies between 50 and 60% can be obtained [6]. In the case of the produced liquid fuels, cost-effective means that the cost price must correspond to the cost prices of fossil fuels, which will be used in the future in cars with low or very low emissions. For the liquid fuels FT diesel is taken as example and the cost price would have to be 0.34 Euro/litre (of diesel). 

The interesting aspect of one of these examples (Figure 3.20) is the inclusion of carbon dioxide within the cycle. Both postulates recognize the production of carbon dioxide from coal, thereby pointing out the relationship of carbon dioxide and coal but recognition of carbon dioxide as part of the natural cycle between plants, lignin, humus, and coal underscores the closeness of the relationship and the end product of the environmental aspects of coal use. 

However, it is not only the production of carbon dioxide from coal that needs to be decreased. The production of pollutants such as sulfur dioxide (SOj) and oxides of nitrogen (NOx, where x = 1 or 2) also needs attention. These gases react with the water in the atmosphere and the result is an acid ... 

Capture of carbon dioxide from coal gasification is already achieved at low marginal cost in some plants. One (albeit where the high capital cost has been largely written off) is the Great Plains Synfuels Plant in North Dakota, where six million tons of lignite is gasified each year to produce clean synthetic natural gas. 

Hattenbach, R.P., M. Wilson, and K.R. Browncep. 1999. Capture of carbon dioxide from coal combustion and its utilization for enhanced oil recovery. Pp. 217-221 in Greenhouse Gas Control Technologies Proceedings of the 4th International Conference, P. Reimer and B. Eliassen, Editors. Amsterdam Pergamon. 

ADA-ES (2) A process for removing carbon dioxide from coal-fired power plants and other industrial sources. It uses a regenerable solid adsorbent. A pilot plant was planned for 2013. 

Example 1.3-6 Facilitated transport across membranes Some membranes contain a mobile carrier, a reactive species that reacts with diffusing solutes, facilitating their transport across the membrane. Such membranes can be used to concentrate copper ions from industrial waste and to remove carbon dioxide from coal gas. Diffusion across these membranes does not vary linearly with the concentration difference across them. The diffusion can be highly selective, but it is often easily poisoned. Should this diffusion be described with mass transfer coefficients or with diffusion coefficients ... 

Benfield process Removal of carbon dioxide from fuel gases, such as those obtained by gasifying coal in the Lurgi process, by countercurrent scrubbing of the gases by hot potassium carbonate solution. 

The methanation reaction is currently used to remove the last traces (<1%) of carbon monoxide and carbon dioxide from hydrogen to prevent poisoning of catalysts employed for subsequent hydrogenation reactions. Processes for conversion of synthesis gas containing large quantities of carbon monoxide (up to 25%) into synthetic natural gas have been investigated to serve plants based on coal-suppHed synthesis gas. 

Anaerobic digestion to methane, on-site combustion, mixing with coal to form solid fuel Direct combustion, can utilize carbon dioxide from industrial flue gas, can grow in municipal waste facilities... 

Fig. 29. Effect of heat treatment on the reactivity of carbons derived from coal tar pitch and delayed petroleum coke. Reaction with carbon dioxide at 1150°. [After P. L. Walker, Jr., and D. O. Baumbach, unpublished results 1969.]...

Part of the North Branch of the Potomac River runs crystal clear through the scenic Appalachian Mountains, but it is lifeless—a victim of acid drainage from abandoned coal mines. As the river passes a paper mill and a wastewater treatment plant near Westemport, Maryland, the pH rises from an acidic, lethal value of 4.5 to a neutral value of 7.2, at which fish and plants thrive. This happy "accident comes about because calcium carbonate exiting the paper mill equilibrates with massive quantities of carbon dioxide from bacterial respiration at the sewage treatment plant. The resulting soluble bicarbonate neutralizes the acidic river and restores life downstream of the plant.1... 

The only published work on the diffusion of gas in coals of different rank appears to be that of Bolt and Innes (2) who studied the diffusion of carbon dioxide from eleven samples of coal at 38°C. They found the diffusion coefficient to range from 3.5 to 9.2 x 10 8 sq. cm./sec., with no apparent correlation with coal rank. Diffusion data on coals of different rank at temperatures higher than 38°C. have only been reported by the present authors (6). It has been shown (7) that the diffusion of inert or noble gases from coal above room temperatures can be rigorously analyzed by using simple diffusion theory, and that true diffusion parameters of the micropore systems can be obtained. In this paper our measurements on the unsteady state release of argon from coals of various rank, over a temperature range, are reported. 

One particular test method (ASTM D-1756) covers the determination of carbon dioxide in coal in any form, such as mineral carbonate, from which carbon dioxide is released by action of mineral acids (e.g., hydrochloric acid). The method can be applied to high- and low-carbonate coals. The determination of carbon dioxide is made by decomposing with acid a weighed quantity of the sample in a closed system and absorbing the carbon dioxide in an absorbent (e.g., such as sodium... 

Ash, as determined by the standard test method (ASTM D-3174), is the residue remaining after burning the coal and coke and differs in composition from the original inorganic constituents present in the coal. Incineration causes an expulsion of all water, the loss of carbon dioxide from carbonates, the conversion of iron pyrites into ferric oxide, and other chemical reactions. In addition, the ash, as determined by this test method, will differ in amount from ash produced in furnace operations and other firing systems because incineration conditions influence the chemistry and amount of the ash. 

Existing physical absorption AGR processes are relatively energy inefficient for application in coal gasification they use substantial amounts of steam or stripping gas to regenerate lean solvent and power to pump lean solvent into the AGR absorber. In the treatment of crude gas with substantial carbon dioxide content, work available by expansion of separated carbon dioxide from its partial pressure in the crude gas, typically 100-300 psia, to atmospheric pressure, is not recovered. In theory, an AGR process could recover and utilize this potential energy. 

Worldwide, approximately 5000 coal-based electric power plants release a total of 10 billion metric tons of carbon dioxide into the atmosphere each year. Separation of this carbon dioxide from power-plant flue gas and sequestration as liquid carbon dioxide... 

The use of selective membranes to separate carbon dioxide from flue gas is illustrated in Figure 8.16. Figure 8.16(a) shows a simplified flow diagram of a conventional power plant. For ease of calculation, the fuel input is assumed to be 150 tons/h of carbon as medium-volatility coal. Combustion of this amount of fuel with an excess of air would generate 2.26 x 10sm3/h of flue gas containing 13% carbon dioxide. This hypothetical plant would produce approximately 600 MWe of electric power (at 10 000 Btu heat/kW power). 

Among the samples of carbon dioxide from natural sources are limestone from various localities, and from ages up to 500 million years marble fresh water and ocean shells carbon dioxide from the air hard and soft coal natural gas wood and various biological products. 

From (4) and (5) above, we gather that if sufficient air is forthcoming to supply the necessary oxygen and to dilute down the carbon dioxide, a coal-gas flame should be more healthy than electric incan-... 

The Selexol process removes acid gases from hydrocarbon gas streams by selective absorption in polyethylene glycol dimethyl ether (DMPEG). It absorbs H2S, C02, COS, and mercaptans. The process has been used to remove carbon dioxide from syngas, natural gas, and coal gas. The process was developed by Allied Chemical in the 1960s and is now... 

With the energy provided by sunlight, plants build up their own tissues out of minerals and water from the earth and from carbon dioxide from the air. These decayed plant tissues in sunken forests become coal deposits, and the elements which they contained pass into the coal. Coal is basically carbon, and without the additional elements from the plant tissues it would be pure carbon. When you heated the coal, these other elements were forced out of the tube through the nozzle in the form of a gaseous mixture. This is one of several gaseous mixtures used in gas stoves. When an industrial company manufactures gas like this, it passes steam over the hot coal to make the process more efficient. The remaining coal is also sold as coke. 

MAGSORB A process for removing carbon dioxide from hot gas streams by reversible absorption on magnesium oxide modified with potassium carbonate. Developed by the Institute of Gas Technology, Chicago, for fuel gas derived from coal. 

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