A description of testing services for solid fuel sources

Coal, Coke, and Solid Fuels


Coal and Coke

Coal is the second largest source of fuel in the world, and it is also the most common fossil fuel for utility and power generation.  However, since coal is a heterogeneous substance with a wide variety of ranks dependent on where it falls in the coalification process, a proximate analysis is needed to classify the coal. 

For example, while the main coal source in the US is lignite, the main coal reserves in Germany are classified as subbituminous, while the highest concentration of bituminous is found in China.  The grade of a sample of coal or coke requires a proximate and an ultimate (elemental) analysis to be fully informed of its composition and of its usefulness.

Proximate analysis, ASTM D 3172, includes the determination of volatile matter, fixed carbon and ash.  Volatile matter and fixed carbon are two indicators of coal rank.  The amount of volatile matter in a coal indicates the load under which the collection system must operate.  High contents of ash typically create operational and disposal problems.

Coking is the severe thermal cracking process meant for producing distillate liquids from heavy ends.  The by-product is a low-temperature carbonization that typically holds commercial value for a variety of industries, including the aluminum industry, the utility industry, the iron and steel industry, and for niche applications such as for industrial heat and steam raising, in cement kilns, and for packing material.



The elemental or ultimate analysis of coal or coke found in ASTM Standard Practice D 3176 provides a uniform system for comparing coals and coke and requires the determination of Carbon, Hydrogen, Nitrogen, Sulfur, Oxygen, and Ash. 

Other tests for Heating Value or Trace Metals may also be required.  For example, combustion calculations can be performed to determine coal feed rates, combustion air requirements, heat release rates, boiler performance and sulfur emissions from the power plant. 

In addition, high contents of sulfur lead to concerns related to SO2 emission and equipment corrosion.  Contamination from heavy metals and trace elements perform as oxidation catalysts, and are thus not preferred.




Solid Fuels

At Texas OilTech Laboratories, we also provide testing for various types of solid fuels including fuel pellets, wood chips, tire chips, and additional sources for alternative fuel. As with all forms of energy production, the quality of the fuels are highly important for the health of the machinery used in its processing. By performing our thorough testing methods, we are able to ensure that the fuel quality of solid fuels remains clear, efficient, and uncontaminated as it powers expensive engines and turbines. Moreover, Texas OilTech Laboratories can test the health and quality of the solid fuels as they are being processed, so that we can guarantee a quality product. For more description of our solid fuels services, please visit our alternative fuels page.


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