Coal continued technology

Alternative feedstocks for petrochemicals have been the subject of much research and study over the past several decades, but have not yet become economically attractive. Chemical producers are expected to continue to use fossil fuels for energy and feedstock needs for the next 75 years. The most promising sources which have received the most attention include coal, tar sands, oil shale, and biomass. Near-term advances ia coal-gasification technology offer the greatest potential to replace oil- and gas-based feedstocks ia selected appHcations (10) (see Feedstocks, coal chemicals). 

All this, of course, requires that economically competitive technologies will be developed. As the costs of oil, gas, and coal continue to increase, the potential economic competitiveness of hydrogen production is becoming more real daily. Accordingly, it is essential that we move forward as rapidly as we can with research and development programs involving hydrogen production and use. 

Moreover, viable clean coal technologies also promote the continued use of coal, thereby offering some degree of energy security to those countries that are net oil importers but having plentiful supplies of coal. Clean coal combustion technologies can reduce emissions of sulfur oxides (SO), nitrogen oxides (NO), and other pollutants at various points of coal use from a mine to a power plant or factory. 

However, apart from their inherent practical limitations at that time, supplies of biomass, wind, and water were limited. Coal was abundant and available and new technology allowed it to be used for Steam raising and iron making. The environmental consequences of rapidly growing and uncontrolled coal use were, of course, unacceptable. Continual technology development over time allowed coal to be used with much greater efficiency and with greatly reduced environmental impact. 

Present-day proposals for ammonia plants are predominantly based on natural gas feedstock, although a few plants are naphtha-based. A small minority of current projects are based on partial oxidation of heavy fuel oil, for example, in China. This pattern is likely to continue for the foreseeable future. A changeover to coal-based technology is unlikely in the near future because of the very high capital cost involved. 

Sasol produces synthetic fuels and chemicals from coal-derived synthesis gas. Two significant variations of this technology have been commercialized, and new process variations are continually under development. Sasol One used both the fixed-bed (Arge) process, operated at about 240°C, as weU as a circulating fluidized-bed (Synthol) system operating at 340°C. Each ET reactor type has a characteristic product distribution that includes coproducts isolated for use in the chemical industry. Paraffin wax is one of the principal coproducts of the low temperature Arge process. Alcohols, ketones, and lower paraffins are among the valuable coproducts obtained from the Synthol process. 

Three major compliance options for SOj emissions available to utilities using coal-fired boilers are to switch fuels, purchase/sell SO, allowances, or install flue gas desulfurization (FGD) technologies. Costs, availability, and impact on boiler operation must be considered when evaluating switching to low-sulfnr coal or natural gas. As more utilities enter the free market to purchase SO, allowances, prices will rise. Therefore, to minimize costs and, at the same time, meet environmental standards, power producers should continuously monitor the tradeoffs among these three options. 

Ab der-Halden A continuous process for distilling coal tar. It is operated under reduced pressure with the heat provided by five, superheated steam. This provides a clean separation of the products, without cracking. Developed in France in the 1920s by C. Ab der-Halden who formed the company PROABD to exploit it. PROABD is now a division of BEFS Technologies, Mulhouse, France, which offers this process and others under the same trade name. Not to be confused with the Abderhalden reaction in biochemistry. 

The reliability and cost of solar electric technologies should continue to improve, although solar power only accounts for less than 1% of all power consumed. The U.S. produces about 300 megawatts of electricity with solar which is about the same amount produced by a mid-size traditional power plant. If solar energy is to provide a significant part of the world s energy needs, the cost of solar must be competitive with other energy sources such as natural gas, nuclear or coal. 

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