Showing papers on "Coal published in 1977"

Minimizing environmental effects in production and use of coal

Abstract: Coal gas is produced in situ using the techniques of gasification, liquefaction and pyrolysis Normal effluents to the atmosphere are recycled in part to the underground reaction zone for conversion into commercial products Contaminants to underground aquifers are captured and injected into the underground reaction zone for destruction and transformation into useful products

Process for producing methanol

Abstract: A system for processing coal to produce methanol, alcohol-slurry coal for transport, electric power and urea. Raw coal is graded. The downgraded fraction is gasified, producing steam and synthesis gas. The synthesis gas is converted to methanol which is then used to slurry upgraded coal for transport or to produce electric power. The steam output of the gasifier drives an oxygen generator to produce oxygen for the gasifier, when the synthesis gas is used to produce methanol, and also drives an electric power turbine. Natural gas may be used to maximize methanol production. Urea is a by-product.

Process for the gasification of coal in situ

Abstract: Process for the gasification of coal in situ comprising driving shafts or tunnels into a coal seam, injecting air into the bore holes to ignite and burn the coal to raise its temperature ceasing the flow of air when the coal is hot enough to support the endothermic water gas reaction, and injecting steam into the hot coal formation, such steam preferably being preheated by the flue gases taken from the same end of the bore holes where the air was injected, and recovering product gases, including carbon monoxide and hydrogen, and also product oil, exiting the tunnel at the other end of the bore holes. When the temperature of the coal drops during injection of steam to a level which will just permit combustion, the steam flow is stopped, and the cycle is repeated by air injection and flue gas removal at the front end of the bore holes, and through the tunnel connected therewith. This cyclic process is repeated until the entire mass of coal within the area encompassed by the bore holes is exhausted.

Generating medium BTU gas from coal in situ

Abstract: Medium BTU gas is generated from coal in situ by establishing communication channels through the coal in part by projectiles and in part by burning. Oxygen is employed for reaction with the coal and reaction temperatures are controlled by injection of steam.

The Physical Transformation of the Mineral Matter in Pulverized Coal Under Simulated Combustion Conditions

Abstract: The physical transformation of the mineral matter in coal has been studied in a laboratory furnace using size-graded, pulverized samples of a lignite and a bituminous coal. The mineral matter is originally distributed in micron-size inclusions in the coal particles. The paper illustrates how the final particle size distribution of the ash produced at combustion temperatures of 1250 to 1830K is determined by a combination of agglomeration of fused mineral matter, cenosphere formation due to gas evolution and vaporization and recondensation of volatile constituents

Rapid devolatilization of pulverized coal in hot combustion gases

Abstract: An experimental and analytical study on the rapid devolatilization of pulverized bituminous coal injected and entrained in hot combustion gases flowing in a constant cross-section gasifier is presented. Data on the weight loss through rapid pyrolysis, on the temperature of the heterogeneous medium, and on the composition of the overall products are correlated with an analytical model incorporating two volatile-producing competitive first-order Arrhenius reactions followed by cracking of the volatiles. The experimental parameters are the mass fraction of coal fed into the combustion gases (0 to 0.12), the input gas temperature (1800°K to 2250°K), three particle size distributions for the same type of coal, and the residence time in the gasifier (7 to 70 ms). All data pertain to tests conducted at a pressure of one atm. Heating rates up to 10 5 °K/s and volatile product yields up to 68% of the original dry, ash-free coal are observed. Analysis of the data suggests that a significant fraction of these volatiles crack to soot and hydrogen, and that the cracking fraction increases with the coal fraction in the input gases. The fraction of the volatiles which crack in the gas phase vs. those which crack within the particles is deduced from the data.

Numerical model of coal gasification in a packed bed

Abstract: A one-dimensional time-dependent computational model has been developed as a pilot study for the multidimensional simulation of coal gasification in a packed bed, treated as a porous medium. Different gas and solid temperatures are used, and concentrations of eight chemical species (N 2 , O 2 , H 2 O, H 2 , CH 4 , CO, CO 2 , tar) two forms of water (surface and interior), coal and char are followed in space and time. Numerical results obtained for gasification of a Wyoming subbituminous coal by a mixture of steam and oxygen show reasonable agreement with laboratory measurements. The numerical method retains all time derivatives and treats the nonlinear partial differential equations as an initial-value problem, using implicit methods which are capable of being extended to two or more space dimensions.

Briquette comprising caking coal and municipal solid waste

Abstract: Briquettes of specified geometry and composition are produced to serve as feed material or "burden" in a moving-burden gasifier for the production of a synthesis or fuel gas from organic solid waste materials and coal, including especially, the so-called "caking" coals, as in the process of copending application number 675-918. The briquettes are formed from a well-blended mixture of shredded organic solid wastes, including especially, municipal solid waste (MSW) or biomass, and crushed caking coal, including coal fines. A binder material may or may not be required, depending on the coal/MSW ratio and the compaction pressure employed. The briquettes may be extruded, stamped, or pressed, employing compaction pressures in excess of 1000 psi, and preferably in the range of 2000 to 10,000 psi. The briquettes may be circular, polygonal, or irregular in cross-section; they may be solid, or concentrically perforated to form a hollow cylinder or polygon; they may be formed into saddles, pillows or doughnuts. The ratio of caking coal to shredded municipal solid waste is controlled so that each part of the predominately cellulosic organic solid waste will be blended with 0.5 to 3.0 parts of crushed coal. Suitable binder materials include dewatered sewage sludge (DSS), "black liquor" rich in lignin derivatives, black strap molasses, waste oil, and starch. The binder concentration is preferably in the range of 2 to 6 percent. If coals high in sulfur content are to be processed, at least a stoichiometric equivalent of dolomite may be included in the briquette formulation to eliminate a major fraction of the sulfur with the slag.

Historical development of underground coal gasification

Abstract: The development of underground coal gasification is traced through a discussion of the significant, early experiments with in situ gasification. Emphasized are the features of each experiment that were important in helping to alter and refine the process to its present state. Experimental details, coal characteristics, and gasification data are supplied for many of the experiments. 69 refs.

Pulverized coal combustion: The influence of flame temperature and coal composition on thermal and fuel NOx

Abstract: A laboratory combustor was used to investigate the factors that influence the conversion of fuel nitrogen in coal during coal combustion. Fuel NO was isolated by experimentation utilizing Argon/Oxygen/Carbon Dioxide mixtures as the oxidant, and care was taken to compare cases with air at matched conditions. For both well mixed and slowly mixed flame types, fuel NO contributed over 75% of the total NO emissions for all conditions examined. Fuel NO was insensitive to temperature changes except when the adiabatic flame temperatures were above 2480°K (4000°F). At the highest adiabatic flame temperature, 2580°K (4200°F), a 10% increase in fuel NO was observed. Four different coals and one coal char were investigated. Fuel NO could not be correlated with fuel nitrogen content alone, even though aerodynamic conditions were kept constant. Fuel nitrogen conversion to NO during pulverized char combustion was 12–16% at a stoichiometric ratio of 1.15 compared to 28% for a pulverized coal of the same nitrogen content. Furthermore, in contrast to the coal results, NO emissions from char combustion were not greatly influenced by changes in injector design. The implication is that although conversion of fuel nitrogen to NO may be relatively low during the char burnout regime of coal combustion, the residual “char NO” may be especially resistant to abatement by modifications of the burner aerodynamics.

Sedimentary record of heavy metals and polycyclic aromatic hydrocarbons in lake constance

Abstract: The enrichment of heavy metals and polycyclic aromatic hydrocarbons (PAH) in dated sediments from Lake Constance during the past 75 years corresponds to the general increase of European coal consumption within the same period of time. Coals are assumed to be the main source of heavy-metal enrichment; incomplete combustion (pyrolysis) of coal also seems to be responsible for the very sharp increase of PAH.

Effect of Sulfur on the Fischer-Tropsch Synthesis

Abstract: One of the principalcauses of present concern is the current unavailability of alternative sources of fuels for transporation. Other fuel imensive sectors, such as electric power generation, can depend on coal or nuclear fuel to provide the energy if petroleum-based fuels become scare. The transporation sector, on the other hand, is projected to need liquid fuels. Due to the relevant abundance of coal in the United States, it isimperative to find ways of converting coal to liquid fuels. Products from coal liquefaction processes contain a high aromatic content. Though this is a desirable comporent isgasoline, it is a very undersirable one in jet and diesel fuels (Table 1). In even higher boiling materials such as gas oils, the high aromatic content makes it quite difficult to produce gasoline by normal rednery processess. Fischer-Tropsch (FT)synthesis, in which carbon produces mainly straight chain aliphatic hydrogen obtained from coal gastfication are reacted over a caralyst, is the only develped...

Devolatilization and oxidation of coal nitrogen

Abstract: The pyrolysis of the nitrogen content of coal was studied by rapidly heating dispersed pulverized particles of a lignite and a bituminous coal to temperatures of 1000 and 2100 K. Nitrogen evolution paralleled that of the total volatiles with the notable exception that little nitrogen was released until 10 to 15 percent of the coal had been devolatilized. A pseudo-first order rough fit of the nitrogen pyrolysis data yielded a rate constant of 9.3 ×10 3 exp (−22,700/RT) sec −1 . Oxidation of the coal was studied in a laminar diffusion flame produced by injecting the coal particles into a flowing helium/oxygen mixture. At a furnace temperature of 1500 K, the conversion of the nitrogen in the coal to nitric oxide was found to decrease from about 60 percent at a fuel equivalence ratio of 0.2 to 10 percent at equivalence ratios above 1.5. At the higher equivalence ratios, however, 30 percent of the char remained unreacted and 45 percent of the original coal nitrogen was retained in the char. Similar oxidation experiments were conducted with char produced by devolatilizing coal at 1500 K under conditions at which the char retained about two-thirds of the original coal nitrogen. Conversion to nitric oxide of the nitrogen retained in the char was significantly lower, by factors of two to three, than conversion for coal nitrogen but showed a similar trend with fuel equivalence ratio. From the difference of the coal and char oxidation results it was inferred that, at a furnace temperature of 1500 K, sixty to eighty percent of the NO x was contributed by the oxidation of nitrogen released with the volatiles and that the conversion efficiency of volatiles to NO x and its dependence on fuel equivalence ratio were similar to data previously reported in the literature for the oxidation of model fuel nitrogen compounds burned in laboratory premixed and diffusion flames.

Method for the gasification of carbonaceous matter by plasma arc pyrolysis

Abstract: Apparatus and method for gasification of carbonaceous matter by plasma arc pyrolysis are disclosed. In one embodiment, a refractory-lined furnace is provided with a depression along its base for holding a pool of molten metal which acts as the external electrode for a bank of long arc column plasma torches which provide a heat mass for the process. The plasma arc pressure imparts momentum to the surface of the melt and causes it to flow in cusping eddy currents during the process. Crushed coal is deposited through the roof of the furnace by a rotary feeder in continuous plural streams. The coal is devolatilized in a matter of milli seconds and the volatiles are cracked as the coal falls by gravity through the interior of the furnace. The remaining carbon-rich char collects at plural sites on the surface of the melt and the mounds of char are rotated by the eddy currents. Steam is continuously injected into the furnace to produce hydrocarbon gases through reaction with the carbon-rich char. A residence time of five to thirty minutes produces carbon utilization of up to 92 percent. The hot raw gases are directed through a gas cooler where heat is extracted for producing the process steam and the cooled raw gases are upgraded to pipeline quality by conventional carbon dioxide and moisture removal techniques and by methanization with catalysts. The raw gas may also be burned directly as a medium-Btu gas or used as a reductant in the direct reduction of iron ore.

Pulverized coal burner for furnace and operating method

Abstract: A pulverized coal burner for a furnace adapted to be used in conjunction with a pulverizer which reduces coal to approximately 40 microns size in the presence of inert steam which conveys it under pressure to said burner tangentially to spiral the same within a fuel tube around a coaxial central tube axially adjustable within the fuel tube to adjust the relation between flared distribution and mixing members respectively on the discharge ends of said tubes. Combustion air is fed coaxially around the discharge end of the fuel tube for thorough mixture with the coal which is conveyed with a minimum amount of steam through said tube so as not to deter combustion in the combustion zone which is immediately adjacent the discharge end of the fuel and central tubes.

Apparatus for converting carbonaceous material into fuel gases and the recovery of energy therefrom

Abstract: The invention is concerned with novel apparatus and process for converting crude carbon such as coal, carbonaceous wastes and the like into valuable chemical products and/or energy. A mass of solid crude carbonaceous fuel is fed into a high temperature liquid which acts as a solvent for carbon at a temperature sufficient to carbonize the mass and by which the carbon is separated from impurities. Volatile fractions are removed from the mass which acts as a distillation column. Air, or another oxygen source, is introduced into the reactor wherein it reacts with the carbon dissolved in the liquid therein, which may preferably be iron to form a hot fuel gas. The hot fuel gas is then used to produce useful energy, generally via a stepwise procedure.

Gasification process using ion-exchanged coal

Abstract: A process wherein Group I-A or Group II-A metals, or both, can be ion-exchanged onto coal, especially a high rank coal, notably a subbituminous or bituminous coal, to produce a highly reactive carbonaceous feed for use in gasification reactions, especially to produce high-BTU fuel gases, but also intermediate-BTU or synthesis gas. The coal is treated by contact with an alkaline solution of an admixture of compounds, inclusive of a soluble alkali metal salt and an excess of an alkaline earth metal hydroxide, each of which interacts one with the other to form an alkali metal hydroxide, and an insoluble alkaline earth metal salt precipitate. The coal is treated in a single step by contact with the solution within which both the Group I-A and II-A metal compounds are dispersed, or dissolved. Where the coal does not contain adequate ion-exchange sites, these are formed by reaction between the alkali metal hydroxide, generated by the reaction, and the coal, and in turn all or a portion of the alkali metal cations are exchanged or replaced by alkaline earth metal cations which are present in the alkali metal hydroxide solution that is formed. Preferably, the treatment is continued until substantially all of the alkali metal cations have been replaced by the alkaline earth metal cations, and then the solution is evaporated while in contact with the coal to redeposit and physically disperse the alkali metal upon the coal.

Process for the catalytic gasification of coal

Abstract: A process for the production of synthetic natural gas from a carbon-alkali metal catalyst or alkali-metal impregnated carbonaceous feed, particularly coal, by reaction of said feed with water (steam) in the presence of a mixture of hydrogen and carbon monoxide, in a series of staged fluidized bed gasification reactors (or gasification zones). The first reactor, or main reactor, of the series is operated as an entrainment reactor and entrained solids are carried over to the second reactor, or reactors, of the series. A carbonaceous feed, or coal, is thus partially gasified in a fluidized bed in the main reactor to form a product gas and a char, and char is entrained within the effluent gases, separated therefrom and then fed into the secondary gasification reactor, or reactors, of the series, the entrained char constituting feed to a secondary reactor, or reactors. Some char is also passed via dense phase transfer from the main reactor to the secondary reactor to maintain catalyst balance. More effective ultilization of the feed carbon is possible by use of the reactor system operated in such a manner than is possible by the sole use of the main reactor, even when the latter is operated at the same or at more optimum conversion conditions.