Coal nitrogen contents

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. 

In 1990, a test using scrap tires (2x2 in. I DE) to generate steam for electricity was conducted at the Elexsys plant. The I DE replaced 20% of the plant s coal. Results showed that IDE is an environmentally sound fuel. Particulate emissions were reduced by the lower ash content of IDE, volatile organic compounds (VOC) were reduced because of more efficient burning of I DE compared to coal, and carbon dioxide emissions were reduced because I DE contains half the fixed carbon found in coal. Nitrogen oxide, chlorine emissions, and metals were also reduced, and ferrous metals and dioxins were nondetectable (7). 

Nitrogen, unlike pyritic sulfur, is mosdy chemically bound in organic molecules in the coal and therefore not removable by physical cleaning methods. The nitrogen content in most U.S. coals ranges from 0.5—2.0 wt %. 

Solid fuels, unlike gases and liquids, are entirely characterized by their composition. For example, coal can be characterized by its carbon, hydrogen, oxygen, sulfur, and nitrogen content. The water and mineral content of coal are also important means of differentiating coals from various sources. 

Acid rain. Lakes in some areas of the world are now registering very low pH s because of excess acidity in rain. This was first noticed in Scandinavia and is now prevalent in eastern Canada and the northeastern U.S. Normal rainfall is 5.6 (because of CO2 in the air forming H2CO3). However, excessive use of fossil fuels (especially coal) with high sulfur and nitrogen content cause sulfuric and nitric acids in the atmosphere from the sulfur dioxide and nitrogen oxide products of combustion. Some rain in the Adirondack Mountains of upper New York State has been measured with a pH of 3.0. This problem is not specific to the chemical industry but should be of concern to all of us. 

Clearly the oil is a much cleaner fuel than the original coal, from the point of view either of the environmentalist or of the plant engineer concerned with fouling of steam and superheater tubes. The sulfur contents of the oils are 0.1-0.2%, which is acceptable, but the nitrogen contents are about 0.6%, which may cause undesired NOx emissions. Some of the more toxic elements, (mercury, selenium, fluorine, and cadmium) have not yet been determined in oil. It is not clear what will be done with the solid residue whether it will be disposed of as waste or whether its small carbon content, typically 20-50% depending on the... 

Ultimate analysis of coal and coke, determination of nitrogen content... 

The asphaltene content correlated with the nitrogen content of the liquids, thus supporting the use of nitrogen content to monitor the extent of coal-liquid upgrading. 

Table III lists the specific gravity, nitrogen content, and sulfur content of the various distillation fractions obtained from each of the eight coal liquids. Nitrogen content increased for the higher-boiling distillates as expected. All sulfur values were low as expected. Nitrogen contents of the asphaltenes from the bituminous-coal liquids were higher than those from the lower-rank-coal liquids.

Linear regression results for the correlation of the PAP contents of the 200° to 325° C, 325° to 425° C, and 425° to 540° C distillates with the distillate nitrogen content gave correlation coefficients of 0.85, 0.96, and 0.93, respectively, indicating very good correlations. Data for the middle distillate are plotted in Figure 4. Thus, the trend in PAP content may very well be more dependent on nitrogen content than on coal rank for these liquids. 

Coal liquids require less severe hydrotreatments than shale oil due to the lower nitrogen content. 

Particulate emissions may increase if combustion is not complete. As seen in Tables 1-2 and 1-3, sulfur emissions may decrease if the tires or TDF replace higher sulfur coal, but may increase if tires or TDF replace wood waste containing little sulfur. NOx emissions, likewise, may increase or decrease based on the relative nitrogen content of the fuel. Also, NOx emissions may increase if additional excess air enters the combustion system to facilitate the feed of the tires or TDF. 

The elemental analysis of the Rasa coal extract appears in Table III, along with the values for the coal. The elemental analyses of the coal and of the extract are similar. This is consistent with the extract being representative of the organic matter in the coal. The nitrogen content of the extract is... 

For the splitting hydrogenation of petroleum gas oil, a lower temperature than that required for the prehydrogenation of bituminous-coal middle oil with smaller conversion to gasoline was sufficient. This is caused mainly by the higher nitrogen content of the bituminous-coal middle oil, which decreases catalyst activity. As shown in Table IV, aromatic rings like naphthalene are saturated with WS2 catalyst at a temperature of 335°C. 

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