Sulfur oxides emissions, control

In the United States and increasingly in other parts of the world, environmental regulations prohibit the combustion of all but very low sulfur-content coals without sulfur oxide emission controls. The cost of installing sulfur oxide control equipment together with concern about equipment rehabihty have led to the shipment of the lower rank low sulfur coals from up to 1600 km away from the mining site. 

Tn the last several years, much of the work in sulfur oxide emission - control has been aimed at emissions from power plant stacks. However, there are many other stationary sources of sulfur emissions including non-ferrous smelters, sulfuric acid plants, and petroleum refineries. The papers in this collection are concerned with these other sources of sulfur-bearing off-gases. This volume is intended to be a consolidated reference source for those interested in the latest sulfur recovery methods. 

High degrees of sulfur oxides emission control are reported at the newer Japanese copper smelters, whether they use conventional or advanced smelting processes (31). All the plants using reverberatory or... 

J. Lanier and co-workers, "Sulfur Dioxide and Nitrogen Oxide Emissions Control in a Coal-Eked MHD System," ASME Winter Annual Meeting Adanta, Ga., Dec. 1979. 

Today s major emissions control methods are sorbent injection and flue gas desulfurization. Sorbent injection involves adding an alkali compound to the coal combustion gases for reaction with the sulfur dioxide. Typical calcium sorbents include lime and variants of lime. Sodium-based compounds are also used. Sorbent injection processes remove 30 to 60% of sulfur oxide emissions. 

EPA, 1981. U.S. EPA, Office of Air Quality Planning and Standards, "Control Technologies for Sulfur Oxide Emission from Stationary Sources," Second Edition, Research Triangle Park, NC, April, 1981. 

Sulfuric acid is a stronger acid than sulfurous [pAa(l) < 0, p7fa(2) = 1.99 at 25 °C and infinite dilution] rain as acidic as pH 2.1 has been recorded at Hubbard Brook, New Hampshire, and the pH of water droplets in clouds can be as low as 1.5 (for comparison, the pH of rainwater saturated with atmospheric CO2 is about 5.6 at 15 °C). Acid rain destroys building materials (especially marble), kills fish and vegetation, accelerates metallic corrosion (Sections 16.5 and 16.7), and can be directly harmful to humans (e.g., it causes the alligator skin condition reported in Cubatao, Brazil). Sulfate rain is not completely without redeeming features, as many soils (e.g., in southern Alberta, Canada) are sulfur-deficient. On balance, however, its acidity is unacceptable, and sulfur oxide emissions must be controlled at the source. Several control measures are possible ... 

The control of sulfur oxide emissions is becoming more important. Several catalyst additives containing cerium and/or lanthanides can act as the SOX control agent (16]. 

Control of Sulfur Oxide Emissions in Copper, Lead, and Zinc Smelting, Inf. Circ. 8527. 

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. 

In the pulping industry, sulfur oxides emissions represent loss of pulping chemical, but the economic loss is apparently not regarded as very serious, at least in this period of relatively abundant and cheap sulfur. In current practice, much sulfur is evidently lost to become either a water or air pollutant (16, 53, 102), but pollution control regulations are forcing increased recovery and recycling of sulfur and other pulping chemicals. The need to increase heat recovery and use should also influence emission controls. 

In the twentieth century, dense smoke emission was gradually brought under control, and emphasis shifted to control of photochemical smog (i.e., control of hydrocarbon and oxide of nitrogen emissions from motor vehicles and stationary sources), of particulate matter and sulfur oxide emissions, of toxic and hazardous emissions (e.g., lead, mercury, beryllium, vinyl chloride, and asbestos), and acidic deposition. ... 

The plant is designed to satisfy NSPS requirements. NO emission control is obtained by fuel-rich combustion in the MHD burner and final oxidation of the gas by secondary combustion in the bottoming heat recovery plant. Sulfur removal from MHD combustion gases is combined with seed recovery and necessary processing of recovered seed before recycling. 

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). 

Title rV Acid Deposition Control - As we all know, acid rain occurs when sulfur dioxide and nitrogen oxide emissions are transformed in the atmosphere and return to the earth in rain, fog, or snow. Approximately 20 million tons of SOj are emitted annually in the United States, mostly from the burning of fossil fuels by electric... 

Sulfuric acid is added to the assembled batteries and the plates are formed within the batteries by applying electric voltage. The formation process oxidizes the lead oxide in the positive plates to lead peroxide and reduces the lead oxide in the negative plates to metallic lead. The charging process produces an acid mist that contains small amounts of lead particulate, which is released without emission controls. 

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