Coal from different processes, characteristics

Characteristics of Coal-Derived Liquids from Different Processes ... 

Differences between the mineral contents of coals from different mines produce different slagging and fouling characteristics when burnt in an identical combustor. The physical and chemical changes that these materials experience when they are rapidly heated in a flame, have a direct bearing on the deposition process. 

Adsorption is the process by which liquid or gaseous molecules are concentrated on a solid surface, in this case activated carbon. This is different from absorption, where molecules are taken up by a liquid or gas. Activated carbon can made from many substances containing a high carbon content such as coal, wood and coconut shells. The raw material has a very large influence on the characteristics and performance activated carbon. 

The distinguishing characteristic of non-plasma and plasma methods of gasification is that the products are different the non-plasma conventional carbonization process yields gas and tar plasma processes yield gas and soot. Based on the representative data collated for hvab coal in Table 17 it is inferred that the gas from carbonization is richer in methane, the chief component of natural gas and the preferred product the gas from plasma is richer in acetylene. In most of the plasma methods collated in Table 17 the gas temperatures were 1300 K or more and any methane formed would readily decompose to yield acetylene. Clearly, in-so-far as the plasma formation of methane is concerned the temperature region of 700—1000 K needs to be investigated. Her 60 Hz discharges, with or without electrodes, in reactors heated to the desired temperature may be advantageous. 

Tar is a product of fractional distillation of primary tar produced by carbonation of natural organic matters, such as coal or wood. When the primary tar is derived from coal, the product is called pitch tar. Similarly, when it is derived from wood, it is called wood tar. The pitch tar is further mixed with oil distillates, to produce the processed tar, commonly known as tar. The tar differs in chemical composition and odour to bitumen. Tars consist of variable mixtures of phenols, polycyclic aromatic hydrocarbons (PAHs) and heterocyclic compounds, and their odour is characteristically more aromatic than the odour of the asphalt. 

Natural graphite is classified into three general types flake (also known asp/umbago), crystalline (vein), and amorphous, varying in physical properties, appearance, chemical composition, and impurities. These differences stem from the type of precursor material (oil, coal, or other carbonaceous deposits) and the natural process by which graphite was formed. Table 10.2 summarizes the characteristics ofthesethreetypes.I lPl... 

It is of interest to mention briefly about the origin and composition of oil as found in the earth reservoirs (Rao, 2012). This is important since the EOR method will be dependent on the composition and chemical characteristics of the oil and the reservoir rock. The composition of oil as found in different parts of the world has been analyzed. Many different trace amounts of molecules have been identified as markers for the source of oil. It is believed that oil (fossil fuel) is formed by natural processes as decomposition of organic matter (such as wood, grass, leaves, etc.). These processes are also known to have taken place over hundreds of millions of years. The composition of fossil fuels is high in carbon. It is thus evident that some millions of years ago, CO2 from air (at present, CO2 concentration in air is about 400 ppm [0.04%]) was used to produce plants through photosynthesis (C02-water-sunlight plants, wood, etc.), which after decomposition aeated coal (solid), oil (liquid petroleum), and natural gas (mostly methane as gas). This also shows that the state (solid-liquid-gas) at which the decomposition ended depends on the physicochemical conditions (i.e., pressure and temperature) in the reservoir. 

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