Reduction of sulfur emission

Since 1970, in OECD countries the problem of air quality has become the subject of studies at many scientific centers. Oil from the Middle East became the main source of energy. The content of sulfur in oil constitutes 2.5%-3%. In 1985 some European countries signed the CLRTAP protocol on a 30% reduction of sulfur emissions. As a result, present day levels of S02 emissions have decreased by more than 50% compared with 1980. Of course, this was possibly largely due to Europe going over to the use of Russian gas. 

There is, however, some success to note in the reduction of sulfur emissions from industrial operations in some developed countries. The European Union, for example, expect a decrease in sulfur dioxide emissions from 1990 to 2010, ranging from 11 to 47% in its individual member states (Anonymous 1999, see also Part I, Chapter 3). However, significant problems persist with regard to air pollution by SO2 (see the following paragraph). 

Helsinki Protocol on Reduction of Sulfur Emissions or their Transboundary Fluxes by at least 30% (22 have ratified entered into force 1987). 

Oslo Protocol on Further Reduction of Sulfur Emissions (25 have ratified entered into force August 1998)... 

Influence of sulfur content in gasoline (from 500 to 50 ppm) in the reduction of pollutant emissions. j... 

Air Pollution. Particulates and sulfur dioxide emissions from commercial oil shale operations would require proper control technology. Compliance monitoring carried out at the Unocal Parachute Creek Project for respirable particulates, oxides of nitrogen, and sulfur dioxide from 1986 to 1990 indicate a +99% reduction in sulfur emissions at the retort and shale oil upgrading faciUties. No violations for unauthorized air emissions were issued by the U.S. Environmental Protection Agency during this time (62). 

The 1990 Amendments to the U.S. Clean Air Act require a 50% reduction of sulfur dioxide emissions by the year 2000. Electric power stations are beheved to be the source of 70% of all sulfur dioxide emissions (see Power generation). As of the mid-1990s, no utiUties were recovering commercial quantities of elemental sulfur ia the United States. Two projects had been aimounced Tampa Electric Company s plan to recover 75,000—90,000 metric tons of sulfuric acid (25,000—30,000 metric tons sulfur equivalent) aimuaHy at its power plant ia Polk County, Elorida, and a full-scale sulfur recovery system to be iastaHed at PSl Energy s Wabash River generating station ia Terre Haute, Indiana. Completed ia 1995, the Terre Haute plant should recover about 14,000 t/yr of elemental sulfur. 

Reduction of exhaust emissions is being tackled in two ways by engineers, including precombustion and postcombustion technology. One of the most effective methods now being researched and adopted includes use of synthetic fuel made from natural gas. This fuel is crystal clear, and just like water, it has no aromatics, contains no sulfur or heavy metals, and when used with a postcombustion device such as a catalytic converter any remaining NO, or other emissions can be drastically reduced. Estimates currently place the cost of this fuel at 1.50 per gallon, with availability in 2004 to meet the next round of stiff EPA exhaust emission standards. 

Silveston, P. L and Hudgins, R. R., Reduction of sulfur dioxide emissions from a sulfuric acid plant by means of feed modulation. Environ. Sci. Technol. 15, 419-422 (1981). 

Many studies on the performances and emissions of compression ignition engines, fueled with pme biodiesel and blends with diesel fuel, have been conducted and are reported in the literature (Laforgia and Ardito, 1994). Fuel characterization data show some similarities and differences between biodiesel and petrodiesel fuels. The sulfur content of petrodiesel is 20 to 50 times that of biodiesel. Biodiesel has demonstrated a number of promising characteristics, including reduction of exhaust emissions. 

Sensitivity of European ecosystems to acid deposition The calculation and mapping of CDs of acidity, sulfur and nitrogen form a basis for assessing the effects of changes in emission and deposition of S and N compounds. So far, these assessments have focused on the relationships between emission reductions of sulfur and nitrogen and the effects of the resulting deposition levels on terrestrial and aquatic ecosystems. 

The conversion of hydrogen sulfide to elemental sulfur in the Claus process is limited by a combination of equilibrium and kinetic factors. Over the past decade, the pressures of air pollution control requirements have resulted in major improvements in the design and operation of Claus plants, with consequent increases in conversion and reduction of sulfur oxides emissions (74-79). Nevertheless, emissions still commonly exceed the permissible limits coming into force both in the United States and abroad. Sulfur dioxide reduction plants present similar problems. Apart from the initial furnace or reactor, they are essentially Claus plants. 

Anonymous (1999) Reduction of sulfur dioxide emissions in the EU 2010 vs. 1990. International Institute of Applied Systems Analysis. 

The reactivity of limestones with respect to the reaction with sulfur dioxide varies markedly. For example, for a given fluidised bed combustor, the Ca S stoichiometric ratio required to achieve a 90 % reduction in sulfur emission at atmospheric pressure, varies from 2 to 5. The reasons for such a variation are not understood, but are likely to include decrepitation, catalytic effects of minor components such as iron, and the structure of the limestone and lime [12.12]. Laboratory test methods have been developed for predicting the performance of sorbents [12.13,12.14]. 

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