Sulfur dioxide, from coal

L. B. Heia, A. B. Phillips, and R. D. Young, "Recovery of Sulfur Dioxide from Coal Combustion Stack Gases," ia F. S. MaHette, ed. Problems and Control of A.ir Pollution, Reioliold Publishing Corporation, New York, 1955, pp. 155—169. 

Penn State University Researchers Discover Inexpensive Way to Clean Up Sulfur Dioxide from Coal Plants. U.S. Department of Energy, National Energy Technology Laboratory, http //www.netl.doe.gov/newsroom/media rel/mr pennst.html... 

Although the occupational human health impact of bioelectricity is smaller than that of coal-fired electricity, the overall human health impact of bioelectricity is higher than that of electricity because of the large contribution of environmental human health impact (Table 14.7). In both systems, the environmental human health impacts come from the emission of carbon monoxide, methane, and sulfur oxides. The hotspots are also similar for the two product systems, because most of these emissions come from the electricity and bioelectricity generation stages. However, the contributions of these emissions are a htde bit different, as sulfur dioxide from coal contributes mostly to human health impacts of electricity, while in the bioelectricity product system there is a small difference in contribution of carbon monoxide and sulfur oxides to human health impact. Fig. 14.5 represents the contributions of main emissions to environmental human health impact for the two product systems. 

In December 1952, thick fog rolled across many parts of the British Isles. In the Thames Valley, the fog mixed with smoke, soot and sulfur dioxide from coal-burning homes and factories, turning the air over London into a dense yellow mass. Due to a temperature inversion, the fog stayed put for several days, during which the city s hospitals filled to over-flowing. According to the Parliamentary Office of Science and Technology, more than... 

Carbon dioxide from heated concrete may be absorbed in barium hydroxide and measured conductimetrically. Sulfur dioxide from coal combustion can also be determined electrochemically. Ammonia evolved from ammonium aluminum compounds can be measured by pH change. 

In magnesium casting, sulfur dioxide is employed as an inert blanketing gas. Another foundry appHcation is as a rapid curing catalyst for furfuryl resins in cores. Surprisingly, in view of the many efforts to remove sulfur dioxide from flue gases, there are situations where sulfur dioxide is deHberately introduced. In power plants burning low sulfur coal and where particulate stack emissions are a problem, a controUed amount of sulfur dioxide injection improves particulate removal. 

Flue Ga.s Desulfuriza.tion. Citric acid can be used to buffer systems that can scmb sulfur dioxide from flue gas produced by large coal and gas-fired boilers generating steam for electrical power (134—143). The optimum pH for sulfur dioxide absorption is pH 4.5, which is where citrate has buffer capacity. Sulfur dioxide is the primary contributor to acid rain, which can cause environmental damage. 

North Thames Gas Board A process for removing organic sulfur compounds from coal gas by catalytic oxidation over nickel sulfide at 380°C. The sulfur dioxide produced is removed by scrubbing with dilute aqueous sodium hydroxide. Operated by the gasworks of the North Thames Gas Board, London, between 1937 and 1953. 

The detrimental effects of acid rain are a major reason why legislation such as the Clean Air Act places strict limitations on sulfur and nitrogen emissions. It is also a reason why low sulfur coal is preferred over high sulfur coal. To reduce sulfur dioxide emissions, industry also uses a technique call scrubbing. Industrial scrubbers employ a variety of physical and chemical processes to remove sulfur dioxide from emissions. Another technique used to combat acidification of lakes is to treat these systems with lime. The lime acts to neutralize the acid, but such techniques are usually costly and are only a temporary remedy for combating the problem. 

Lime (portlandite) spray dryers are often used to remove sulfur dioxide from flue gases at coal combustion facilities. Calcium in the spray and flyash may also simultaneously remove arsenic. The resulting arsenic-bearing flyash and calcium sulfites and sulfates are then collected in baghouses or with electrostatic... 

Sulfur dioxide from the combustion of sulfur-containing fossil fuels (e.g., diesel oil and coal) is oxidized in the atmosphere to form sulfur trioxide that reacts with water to form sulfuric acid. 

Sulfur dioxide is formed whenever sulfur-containing fuels are combusted in air. Sulfur dioxide can lead to the formation of acid rain and is a controlled pollutant in most countries. U.S. 5,196,176, assigned to Paques B.V, describes a biological process for removing sulfur dioxide from a vent gas and converting it to elemental sulfur. Estimate the cost (in /kWh) of using the Paques process to treat the flue gas from a 1000 MW power station that burns Illinois Number 6 coal in pressurized fluidized bed combustors. 

There were 1004 fossil-fueled units with a total capacity of about 18 thousand MW which were installed in 1940 or earlier but were still in operation in 1970. Some of these units were installed in the first two decades of this century. These units were estimated to be 56% coal-fired, 28% oil-fired, and 16% gas-fired. Assuming that one-half of each of the types of older units will be retired by 1975, then 281 coal-fired, 141 oil-fired, and 80 gas-fired units will be retired. In addition 90 coal-fired and 30 gas-fired units are expected to be converted to oil-fired units. Consequently, by 1975 there will be 960 coal-fired and 1050 oil-fired for a total of 2010 units which will require some form of sulfur emission control either through stack devices to remove sulfur dioxide from flue gases or through low sulfur fuels. 

Use Cement additive for oil-well casings, absorbent for oil spills (silicone-coated), to replace lime in scrubbing sulfur dioxide from flue gas, as a filler in plastics, source of germanium (England), proposed as catalyst for coal liquefaction, removal of heavy metals from industrial wastewaters, separation of oil-sand tailings. 

Use Building stone, metallurgy (flux), manufacture of lime, source of carbon dioxide, agriculture, road ballast, cement (Portland and natural), alkali manufacture, removal of sulfur dioxide from stack gases and sulfur from coal. 

When the calcium carbonate, CaC03, in limestone is heated to a high temperature, it decomposes into calcium oxide (called lime or quick lime) and carbon dioxide. Lime was used by tbe early Romans, Greeks, and Egyptians to make cement and is used today to make over 150 different chemicals. In another reaction, calcium oxide and water form calcium hydroxide, Ca(OH)2 (called slaked lime), used to remove the sulfur dioxide from smoke stacks above power plants burning bigb-sulflir coal. The equations for all these reactions are below. Determine the oxidation number for each atom in the equation and identify whether the reactions are redox reaction or not. For each redox reaction, identify what is oxidized and what is reduced. 

---