How to calculate the received base volatile matter based on known parameters?
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It is known that the ash content on a coal basis is 12.6%, the volatile matter on an analysis basis is 18%, the total moisture content is 9.6%, and the volatile matter on a dry, ash-free basis is 24%. Determine the volatile matter on a received basis. This post was last edited by ryn on 2009-3-20 22:27]
Well, I’ll just tell you then. . . I’m not sure if it’s correct; take a look and see. Based on the parameters you provided, it seems that the following values are known: Aad=12.6%, Vad=18%, Mar=9.6%, Vdaf=24%. We need to find Var. 【Solution】According to the book \"Coal Chemistry\" or the standards for coal coking tests, it can be determined that Var=100Vdaf / and Var=(100-Mad)*Vad / (100-Mar). By combining these two equations, we obtain: (100-Mar)*Var2 + Aad*Vad*Var - 100*Vdaf*Vad=0 ； By substituting Aad=12.6, Vad=18, Mar=9.6, and Vdaf=24 into the above equation, we obtain: 90.4*Var2 + 226.8Var – 43200=0, which is equivalent to: Var2 + 2.5Var – 477.88 =0 ； It can be calculated from this that Var=20.65, that is, Var=20.65%. Where: Var2 represents the square of Var, and ar, daf, ad are all indices. Therefore, the base volatiles content is 20.65%. This post was last edited by ryn on 2009-3-20 21:41]
I don’t know what the concept of internal ash content is If it is the ash on an analysis basis, then the moisture on an analysis basis calculated in this way is 12.4, which is higher than the moisture on a received basis; this is not logical. The calculation is simple; the key is to understand the meaning of internal ash content.
Var=20.65%>Vad=18%, right? ? I think Vad should be greater than Var. . The denominator for the basis on which it is calculated is the largest; just as Vdaf for the combustible basis is greater than Vad for the dry basis. In terms of the denominator, ar > ad > daf, so it should be that Vdaf > Vad > Var
Could it be that the formula is reversed? I’ll calculate it the other way around. 【Solution】According to the book \"Coal Chemistry\" or the standards for coal and coke testing, it can be determined that Vdaf = 100Var / and Vad = (100 – Mad) * Var / (100 – Mar). By combining these two equations, we obtain: (100/Vdaf) * Var² + Aad * Var – (100 – Mar) * Vad = 0 ； By substituting Aad=12.6, Vad=18, Mar=9.6, and Vdaf=24 into the above equation, we obtain: Var2 + 3.024Var - 390.528=0 ； It can be calculated from this that Var=18.31, that is, Var=18.31%. Where: Var2 represents the square of Var, and ar, daf, ad are all indices. Therefore, the basic volatile fraction received is 18.31%. This post was last edited by ryn on 2009-3-23 15:10]
According to the calculations above, Vdaf > Var > Vad; the value of 18.31% is not greater than the volatility of the combustible base. However, a volatiles content Vad greater than that on an air-dry basis is still unreasonable.
According to dengjian820324 on the second floor, the analyzed basis moisture level is 12.4, which is higher than the received basis moisture level; this does not make sense. I assumed a base moisture content of Mad=8%, and then calculated as follows (not sure if it’s correct): Var=*Vad=*18=17.69%, meaning the volatile matter content on a received basis is 17.69%. Thus, Vdaf > Vad > Var; please offer your criticism.
Understanding the ash content of coal: The ash content of coal refers to the residue that remains after coal has been completely burned. Since this residue is the product of the complete combustion of the combustible components in coal, with the minerals in coal (all inorganic substances except water) undergoing a series of decomposition and combination reactions during this complete combustion process, ash should technically be referred to as the ash yield. (1) Minerals in coal: Minerals in coal are divided into inherent minerals and extrinsic minerals. a. Intrinsic minerals, which are further divided into primary minerals and secondary minerals. Primary minerals are the minerals contained within the coal-forming plants themselves, and their content generally does not exceed 1–2% ； Secondary minerals are those that remain in coal as a result of the mixing of minerals from peat swamp waters with the remains of coal-forming plants during the coal formation process. The content of secondary minerals is generally not high either, but it varies considerably. The ash formed by the inherent minerals is called inherent ash, and inherent ash can only be separated from coal using chemical methods. b. Foreign minerals refer to the gangue from the roof, floor, and interlayer strata that gets mixed into the coal during its formation and transportation. The ash formed by external minerals is called external ash, and external ash can be separated from coal through washing methods. (2) Ash in coal: The ash in coal originates from minerals. Minerals in coal form ash upon combustion. Minerals such as clay, gypsum, carbonates, and pyrite undergo decomposition and chemical reactions during the combustion of coal; some of them turn into gases and escape, while the residue that remains is ash. Ash content is usually lower than that of the original substance; therefore, based on the ash content and after correction using appropriate formulas, the mineral content can be approximated.
No one is questioning whether the calculations above are correct! ! !