Sulfur coal properties

Corrosion. The primary coal properties affecting corrosion are sulfur and chlorine levels. The range of sulfur levels in Table 2 shows a low of 0.3% for SUFCo and a high of 5.2% for petroleum coke. R F coal has 4.2% sulfur. The highest chlorine level in this group of coals is 0.41% for Pyro No. 9 coal. 

Cost of GasificatUm-Tiased Power Systems Comparing power options is complicated by the many different parameters that must be considered in making a cost determination coal cost coal properties, inclnding sulfur and moisture contents ambient temperature degree of process integration gas turbine model and gas cleanup method. These, and many other factors, have a significant impact on cost. 

White, D. M. Edwards, L. 0. et al. "Correlation of Coal Properties with Environmental Control Technology Needs for Sulfur and Trace Elements" Radian Corporation, EPA Contract 68-01-3171. 

Both of those chemical reaction equations are exothermic reaction, and when the products meet water, they will combine with strong oxidizing acid and release large amounts of heat. A huge amount of thermal accelerate the speed of coal oxidation, thus promote the spontaneous combustion. The study found that under the condition of the same coal property, the higher sulfur content, the easier oxidized(Wen et al. 2011). 

The direct objectives of coal cleaning practices are reduction (within predetermined limits) of size, moisture, ash, as well as sulfur (Williams, 1981 Couch, 1991). However, coal properties have a direct bearing not only on whether but also on how coal should be cleaned. Indeed, coal rank (rank being a complex property that is descriptive of the nature of the coal and its properties) (Chapters 2, 8, and 9) can, and usually does, play an important role in determining the feasibility and the extent of cleaning. 

In recent years, deliberate attempts have been made to bring about desulfurization on an industrial scale by modification of the coal preparation practices. In part, this has been due to development of more precise methods for the separation of coal and minerals. However, these practices are usually dependent upon the coal properties. Thus, where low-sulfur coal feedstock is a necessity, the deliberate selection of naturally occurring low-sulfur coal has been the most effective solution and has been the practice followed in producing metallurgical coals, political aspects notwithstanding as evidenced by the selection of higher sulfur (and inappropriate) coal for politically sensitive, rather than market, satisfaction. 

Each of the coal properties interacts in a significant way with generation technology to affect performance. For example, higher-sulfur content reduces efficiency of pulverized coal combustion (PCC) due to the added ena gy consumption and operating costs to remove sulfur oxides (SOx) from the flue gas. 

The sulfur content is an important, but undesirable property of coals. If the coal is to be used for the production of metallurgical coke, its sulfur content has to be limited because of the deleterious effect of sulfur on the properties of steel. The sulfur content of coal used as fuel is also undesirable because of the resultant SO2 in the flue gases. At present, low-sulfur coals are at a premium and much research is being done on the desulfurization of coal. 

Properties. The properties of naphtha, gas od, and H-od products from an H-coal operation are given in Table 7. These analyses are for Hquids produced from the syncmde operating mode. Whereas these Hquids are very low in sulfur compared with typical petroleum fractions, they are high in oxygen and nitrogen levels. No residual od products (bp > 540° C) are formed. 

Properties. Pilot-unit data indicate the EDS process may accommodate a wide variety of coal types. Overall process yields from bituminous, subbituminous, and lignite coals, which include Hquids from both Hquefaction and Flexicoking, are shown in Figure 14. The Hquids produced have higher nitrogen contents than are found in similar petroleum fractions. Sulfur contents reflect the sulfur levels of the starting coals ca 4.0 wt % sulfur in the dry bituminous coal 0.5 wt % in the subbituminous and 1.2 wt % sulfur in the dry lignite. 

Properties. The properties of char products from two possible coal feeds, a low sulfur Western coal, and a high sulfur Midwestern coal, are shown in Table 11. The char derived from the low sulfur Western coal may be direcdy suitable as plant fuel, with only minor addition of clean process gas to stabilize its combustion. Elue gas desulfurization may not be required. Elue gas from the combustion of the char derived from the high sulfur Illinois coal, however, requires desulfurization before it may be discharged into the atmosphere. 

Properties. A high volatile western Kentucky bituminous coal, the tar yield of which by Fischer assay was ca 16%, gave a tar yield of ca 26% at a pyrolysis temperature of 537°C (146—148). Tar yield peaked at ca 35% at 577°C and dropped off to 22% at 617°C. The char heating value is essentially equal to that of the starting coal, and the tar has a lower hydrogen content than other pyrolysis tars. The product char is not suitable for direct combustion because of its 2.6% sulfur content. 

Cationic polymerization of coal-tar fractions has been commercially achieved through the use of strong protic acids, as well as various Lewis acids. Sulfuric acid was the first polymerization catalyst (11). More recent technology has focused on the Friedel-Crafts polymerization of coal fractions to yield resins with higher softening points and better color. Typical Lewis acid catalysts used in these processes are aluminum chloride, boron trifluoride, and various boron trifluoride complexes (12). Cmde feedstocks typically contain 25—75% reactive components and may be refined prior to polymerization (eg, acid or alkali treatment) to remove sulfur and other undesired components. Table 1 illustrates the typical components found in coal-tar fractions and their corresponding properties. 

Properties Involving Utilization. Coal rank is the most important single property for appHcation of coal. Rank sets limits on many properties such as volatile matter, calorific value, and swelling and coking characteristics. Other properties of significance include grindabHity, ash content and composition, and sulfur content. 

Coking coal is cleaned so that the coke ash content is not over 10%. An upper limit of 1—2 wt % sulfur is recommended for blast furnace coke. A high sulfur content causes steel (qv) to be brittle and difficult to roU. Some coal seams have coking properties suitable for metallurgical coke, but the high sulfur prevents that appHcation. Small amounts of phosphoms also make steel brittle, thus low phosphoms coals are needed for coke production, especially if the iron (qv) ore contains phosphoms. 

J. A. CavaHaro and co-workers. Sulfur and A.sh Reduction Potential and Selected Chemical and Physical Properties of United States Coals, DOE/PETC-91 / 2, Jan. 1990. 

The sulfur content of U.S. coals varies widely, ranging from a low of 0.2 percent to as much as 7 percent by weight, on a diy Basis. The estimated remaining U.S. coal reserves of all ranks, by sulfur content, are shown in Fig. 27-1. Extensive data on sulfur and sulfur reduc tion potential, including washability, in U.S. coals are given in Sulfur and Ash Reduction Potential and Selected Chemical and Physical Properties of United States Coal (U.S. Dept, of Energy, DOE/PETC, TR-90/7, 1990 TR-91/1 andTR-91/2, 1991). 

Sulfur and phosphorus content Coals should assay low in these harmful impurities as they have adverse effects on the properties of the metal. Moreover, gases produced from sulfur- and phosphorusbearing coals are corrosive to equipment and pollute the atmosphere. 

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