Sulfur emission trend

FIGURE S.30 Comparison of ambient levels of t h maximum ozone, annual average of total suspended particulate matter (TSP), and sulfur dioxide in selected cities from around the world to illustrate the v tacion in these levels from countr)i to country with respect to the United States. [Reproduced from the National Air Quality and Emission Trends Report (1992), with permission.] ... 

The amount of sulfur in automotive fuels varies presently in the range from 0.01 to 0.10 wt% a typical value is 0.03 wt%. Even in a vehicle with a fuel economy of 27.5 miles/gal, mentioned earlier, the amount of sulfur passing through the catalyst in 50,000 miles will be of the order of 1500 g. Since sulfur emissions from vehicles equipped with oxidation catalysts are a matter of environmental concern (6, 7), one might anticipate some reduction of the fuel sulfur in the future through more extensive desulfurization in refining. On the other hand, such trends may be offset by energy-utilization considerations. However, even a tenfold reduction in fuel sulfur will not completely nullify the effect of this potential poison with respect to some catalysts. 

Emission Rate Algorithms. In order to compile a natural emissions inventory, emission rate functions must be determined for the sources included in the inventory. The emission rate for a specific source will vary depending upon certain environmental conditions. Analyses of sulfur emission measurements collected by Adams et al. (2) and later studies (21.22) suggest that temperature plays an important role in determining sulfur flux. While the mechanisms controlling the release of natural sulfur emissions are not well understood, field observations have demonstrated characteristic trends in temperature-flux patterns. Sulfur emissions tend to increase logarithmically with increasing temperature for normal ambient temperatures (10°C to 35°C). 

Carmichael, G. R., D. G. Streets, G. Calori, M. Amman, M. Z. Jacobson, J. Hansen and H. Ueda (2002) Changing trends in sulfur emissions in Asia Implications for acid deposition, air pollution, and climate. Environmental Sciences and Technology 356, 4707-4713 Carroll, J. J. and A. E. Mather (1992) The system carbon dioxide-water and the Krichevsky-Kasarnovsky equation. Journal of Solution Chemistry 21, 607-621 Carlton, A. G., C. Wiedinnyer and J. H. Kroll (2009) A review of secondary organic aerosol (SOA) formation from isoprene. Atmospheric Chemistry and Physics 9, 4987-5005 Carslaw, K. S., O. Boucher, D. V Spracklen, G. W. Mann, J. G. L. Rae, S. Woodward and M. Kulmala (2010) A review of natural aerosol interactions and feedbacks within the Earth system. Atmospheric Chemistry and Physics 10, 1701-1737... 

This has led to a strong decrease in sulfur emissions caused by transportation fuels for road traffic. For example, in 1975 and 1990, respectively, 100000 and 86000 tonnes of SO2 were emitted in Germany (only road traffic), whereas in 1999 the amount had fallen to 26 0001 SO2. [For comparison overall SO2 emissions (Germany) 7.5 mio. t in 1975, 5.3 mio. t in 1990, and 0.8 mio. t in 1999]. Thus the share of road traffic on the overall SO2 emissions is in many industrialized countries today much less than 10%. Today, less than 50ppmw (mostly even < 10 ppmw) sulfur in gasoline and diesel oil is mandatory in industrialized countries, and fuels with even less sulfur are or will be on the market due to tax benefits. A similar trend can be forecast for countries in Asia such as China and India (Table 6.8.2), where until recently the sulfur limit has been much higher. 

The hydrotreating process for desulfurization of petroleum products was developed in the 1960s mainly to reduce the sulfur concentration in gasoline and diesel oil to reduce sulfur dioxide emissions. In Europe, North America, and Japan this has led to a strong decrease in sulfur emissions caused by transportation fuels for road traffic. A similar trend can be forecast for countries in Asia like China and India, where until recently the sulfur limit has been much higher. 

The potential advantages of LPG concern essentially the environmental aspects. LPG s are simple mixtures of 3- and 4-carbon-atom hydrocarbons with few contaminants (very low sulfur content). LPG s contain no noxious additives such as lead and their exhaust emissions have little or no toxicity because aromatics are absent. This type of fuel also benefits often enough from a lower taxation. In spite of that, the use of LPG motor fuel remains static in France, if not on a slightly downward trend. There are several reasons for this situation little interest from automobile manufacturers, reluctance on the part of automobile customers, competition in the refining industry for other uses of and fractions, (alkylation, etherification, direct addition into the gasoline pool). However, in 1993 this subject seems to have received more interest (Hublin et al., 1993). 

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). 

Plant nutrient sulfur has been growing in importance worldwide as food production trends increase while overall incidental sulfur inputs diminish. Increasing crop production, reduced sulfur dioxide emissions, and shifts in fertilizer sources have led to a global increase of crop nutritional sulfur deficiencies. Despite the vital role of sulfur in crop nutrition, most of the growth in world fertilizer consumption has been in sulfiir-free nitrogen and phosphoms fertilizers (see Fertilizers). 

Similarly, Husain et al. (1998) have reported trends in sulfate at two sites in New York state, from 1979 to 1996 at Whiteface Mountain in a remote area in the eastern part of the state and from 1983 to 1996 at Mayville, in the western part. The trends at both sites were highly correlated. Figure 16.41 shows the relationship between sulfate or total sulfur (defined as sulfate plus gas-phase S02) at Whiteface Mountain as a function of the estimated anthropogenic emissions of S02 upwind in the Midwest. The relationship is well described as linear, with a correlation coefficient of r2 = 0.81. (However, a negative intercept suggests that this cannot be directly extrapolated down to very small S02 emissions.)... 

Since this estimated share pattern was derived mainly from projection of trends (particularly long term trends), it seems appropriate to focus on oil and speculate as to how possible future events might alter its forecast future role. Events related to pollution control tend to indicate increases in petroleum demand. The use of lead free gasoline, for instance, requires additional refinery processing, which in turn consumes more petroleum fuel. Increasingly tighter controls on sulfur dioxide emissions from thermal-electric plants will cause a shift from coal to low sulfur fuel oil if there is no economic flue-gas desulfurization to cope with coals sulfur content. 

Work in the first phase involved preliminary checking of equipment and instruments for measuring emissions, as well as establishment of N0X reduction trends using staged combustion techniques, while burning the current power plant fuel, a low-sulfur No. 6 fuel oil. The purpose of this phase was to reduce the time necessary to carry out the subsequent SRC-II tests and to achieve minimum NO levels with the limited supply (4,500 bbls) of SRC-II fuel oil. X... 

A third emission reduction choice is to remain with the existing front end process, which continues to produce a sulfur dioxide-containing waste gas stream, and move to some system which can effectively remove the sulfur dioxide from this waste gas before it is discharged. Many methods are available, each with features which may make one more attractive than the others for the specific sulfur dioxide removal requirements (Table 3.8). Some of the selection factors to be considered are the waste gas volumes and sulfur dioxide concentrations which have to be treated and the degree of sulfur dioxide removal required. It should be remembered that the trend is toward a continued decrease in allowable discharges. The type of sulfur dioxide capture product which is produced by the process and the overall cost are also factors. Any by-product credit which may be available to offset process costs could also influence the decision. Finally, the type of treated gas discharge required for the operation (i.e., warm or ambient temperature, moist or dry, etc.), also has to be taken into account. Chemical details of the processes of Table 3.8 are outlined below. 

Major environmental trends that we see for land, air, water, and transportation of environmentally hazardous materials are shown in Box 9. These trends require that we get ahead of these issues and lead the chemical industry in the reduction of toxic metal (e.g., Sb, Sn, As) compounds, greenhouse gases, mercury emissions, and sulfur from gasoline and diesel, and find ways to control and sequester C02. Reduction of arsenic, as well as nitrates and ammonia, in drinking water is necessary. It is also imperative in these days of terrorism that we reduce transportation and storage of hazardous materials and continue our drive to develop inherently safer processes. 

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