Producers of coal

The producers of coal, the most polluting fuel, will say there is no energy shortage - there is coal to last for several hundred years — and liquid fuels, from methanol through gasoline to fuel oil can be made from coal. They, like the oil companies, will argue carbon dioxide is not a problem and sulfur emissions can be reduced. 

The USA remains a major world producer of coal, occupying second position to China. More than 90 percent of the coal production is consumed within the USA, especially for the generation of electricity, while the main customer nations for coal exports are Canada, Brazil, Japan and Italy. 

Although oil and gas are important, coal is the major somce of energy for both nations. In China, for example, coal supplies c. 70 percent of the nation s energy needs. Coal production is expected to increase in the next decade as industrialization continues in both nations. Globally, coal production is also set to increase as other nations industrialize, notably in southeast Asia and South America. Other major producers of coal are Russia, Australia, South Africa and in a number of European nations, e.g. Poland and Germany, coal mining remains an important industry with a long history. 

Lurgi coal gasifleadon process A process involving the gasification of coal under pressure with mixtures of steam and oxygen. The reactions produce CO and H,. 

The Fischer-Tropsch reaction is essentially that of Eq. XVIII-54 and is of great importance partly by itself and also as part of a coupled set of processes whereby steam or oxygen plus coal or coke is transformed into methane, olefins, alcohols, and gasolines. The first step is to produce a mixture of CO and H2 (called water-gas or synthesis gas ) by the high-temperature treatment of coal or coke with steam. The water-gas shift reaction CO + H2O = CO2 + H2 is then used to adjust the CO/H2 ratio for the feed to the Fischer-Tropsch or synthesis reactor. This last process was disclosed in 1913 and was extensively developed around 1925 by Fischer and Tropsch [268]. 

On the industrial scale it is produced in large quantities for the manufacture of sulphuric acid and the production methods are dealt with later. It was once estimated that more than 4 000 000 tons of sulphur dioxide a year entered the atmosphere of Britain from the burning of coal and oil. 

Synthetic oil is feasible and can be produced from coal or natural gas via synthesis gas (a mixture of carbon monoxide and hydrogen obtained from incomplete combustion of coal or natural gas). However, these are themselves nonrenewable resources. Coal conversion was used in Germany during World War II by hydrogenation or. 

Methanol. If methanol is to compete with conventional gasoline and diesel fuel it must be readily available and inexpensively produced. Thus methanol production from a low-cost feed stock such as natural gas [8006-14-2] or coal is essential (see Feedstocks). There is an abundance of natural gas (see Gas, natural) woddwide and reserves of coal are even greater than those of natural gas. 

Produced from Co l. Estimates of the cost of producing methanol from coal have been made by the U.S. Department of Energy (DOE) (12,17) and they are more uncertain than those using natural gas. Experience in coal-to-methanol faciUties of the type and size that would offer the most competitive product is limited. The projected costs of coal-derived methanol are considerably higher than those of methanol produced from natural gas. The cost of the production faciUty accounts for most of the increase (11). Coal-derived methanol is not expected to compete with gasoline unless oil prices exceed 0.31/L ( 50/bbl). Successful development of lower cost entrained gasification technologies could reduce the cost so as to make coal-derived methanol competitive at oil prices as low as 0.25/L ( 40/bbl) (17) (see Coal conversion processes). 

Produced from Biomass. Estimates for methanol produced from biomass indicate (11) that these costs are higher than those of methanol produced from coal. Barring substantial technological improvements, methanol produced from biomass does not appear to be competitive. 

Most coal-tar chemicals are recovered from coproduct coke ovens. Since the primary product of the ovens is metallurgical coke, production of coal chemicals from this source is highly dependent on the level of activity in the steel industry. In past years most large coke producers operated thein own coproduct recovery processes. Because of the decline in the domestic steel industry, the recent trend is for independent refiners to coUect cmde coal tars and light oils from several producers and then separate the marketable products. 

In 1990, U.S. coke plants consumed 3.61 x 10 t of coal, or 4.4% of the total U.S. consumption of 8.12 x ICf t (6). Worldwide, roughly 400 coke oven batteries were in operation in 1988, consuming about 4.5 x 10 t of coal and producing 3.5 x 10 t metallurgical coke. Coke production is in a period of decline because of reduced demand for steel and increa sing use of technology for direct injection of coal into blast furnaces (7). The decline in coke production and trend away from recovery of coproducts is reflected in a 70—80% decline in volume of coal-tar chemicals since the 1970s. 

Although small amounts of hquids are produced during coal pyrolysis, significant amounts of coal-derived hquids did not become available until after the... 

The Eastman acetic anhydride [108-24-7] process provides an extension of carbonylation chemistry to carboxyUc acid esters. The process is based on technology developed independendy in the 1970s by Eastman and Halcon SD. The Eastman acetic anhydride process involves carbonylation of methyl acetate [79-20-9] produced from coal-derived methanol and acetic acid [64-19-7]. 

When completed in 1996, the Weihe plant will gasify 1500 t/day of coal to produce 300,000 t/yr of ammonia, which will be used to manufacture 520,000 t/yr of urea fertilizer. This project is the eighth Texaco oil or coal gasification plant Hcensed by Chinese industry. 

Other includes net imports of coal coke and electricity produced from wood, waste, wind, photovoltaic, and solar thermal sources connected to electric utihty distribution systems. It does not include consumption of wood energy other than that consumed by electric utiUty industry. 

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). 

Coal can be converted to gas by several routes (2,6—11), but often a particular process is a combination of options chosen on the basis of the product desired, ie, low, medium, or high heat-value gas. In a very general sense, coal gas is the term appHed to the mixture of gaseous constituents that are produced during the thermal decomposition of coal at temperatures in excess of 500°C (>930°F), often in the absence of oxygen (air) (see Coal CONVERSION PROCESSES, gasification) (3). A soHd residue (coke, char), tars, and other Hquids are also produced in the process ... 

The recorded chronology of the coal-to-gas conversion technology began in 1670 when a clergyman, John Clayton, in Wakefield, Yorkshire, produced in the laboratory a luminous gas by destmctive distillation of coal (12). At the same time, experiments were also underway elsewhere to carbonize coal to produce coke, but the process was not practical on any significant scale until 1730 (12). In 1792, coal was distilled in an iron retort by a Scottish engineer, who used the by-product gas to illuminate his home (13). 

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