Calorific value of coal

The calorific value varies depending on the type of coal; it is necessary to determine the calorific value based on the quality of the coal

The calorific value of standard coal is approximately 6000 Kal/Kg

Hehe, thanks to everyone. However, what I want is information on the methods for determining the calorific value of coal.

This post was last edited by xwtsq on 2009-5-16 at 11:25. If a method standard is required, GB/T 213-2008 is available; see http://bbs.hcbbs.com/viewthread.php?tid=426344&highlight=%C3%BA%B5%C4%B7%A2%C8%C8%C1%BF%B2%E2%B6%A8%B7%BD%B7%A8. For actual determination of calorific value, fully automatic calorimeters are generally used nowadays, and the manufacturer will provide specific training after the instrument is purchased.

Are there manufacturers of fully automatic calorimeters? I’d recommend it

The standards for measuring calorific value have been provided above; the lower calorific value of coal can also be calculated using the results of its industrial analysis. The principles and methods for developing new formulas to calculate the lower calorific value of coal based on these industrial analysis results will not be discussed in detail here. The calculation formulas for practical use are introduced as follows: 1. New formula for calculating the lower heating value of bituminous coal. The calculation in joules is as follows: Qnet.ad = 35859.9 – 73.7Vad – 395.7Aad – 702.0Mad + 173.6CRC, in joules per gram. Alternatively, the formula in calories is: Qnet.ad = 8575.63 – 17.63Vad – 94.64Aad – 167.89Mad + 41.52CRC, in calories per gram. Qnet.ad represents the lower heating value on an analytical basis ； 　　 Vad——Analytical basis volatile matter (%) ； 　　 Aad——Analytical basic ash content (%) ； 　　 Mad——Analytical base moisture (%) ； 　　 CRC — Cokslag characteristics. 　　2. New formula for calculating the lower heating value of anthracite: The calculation in joules is as follows:
Qnet.ad = 34813.7 – 24.7Vad – 382.2Aad – 563.0Mad, in joules per gram.
The calculation in calories is as follows:
Qnet.ad = 8325.46 – 5.92Vad – 91.41Aad – 134.63Mad, in calories per gram.
If it is possible to determine the H value, or if an average value of past H values from the coal mining area in question can be obtained, using the following formula will yield more accurate results for the lower heating value of anthracite. 　　Formula in joules:
Qnet.ad = 32346.8 – 161.5Vad – 345.8Aad – 360.3Mad + 1042.3Had, in joules per gram.

Formula in calories:
Qnet.ad = 7735.52 – 38.63Vad – 82.70Aad – 86.16Mad + 249.27Had, in calories per gram.

3. New formula for calculating the lower heating value of lignite
Formula in joules:
Qnet.ad = 31732.9 – 70.5Vad – 321.6Aad – 388.4Mad, in joules per gram.

Formula in calories:
Qnet.ad = 7588.69 – 16.85Vad – 76.91Aad – 92.88Mad, in calories per gram.

4. To calculate the standard coal consumption, the lower heating value on an analysis basis (Qnet.ad), obtained using the formulas above, is converted to the lower heating value of the actual coal used (Qnet.ar) through the following formula, after which the standard coal consumption can be calculated. 　　Using the formula for calculating the lower heating value of coal: 100 – Mad, 100 – Mar. Qnet.ar = Qnet.ad × (100 – Mad) / (23 + (Mar – Mad) × 100 – Mad), in joules per gram. The new formula based on the industrial analysis of coal yields a significantly higher level of accuracy compared to the old formula in use. For bituminous coal, the standard error for calculating the lower heating value is 89 calories per gram (372 joules per gram), representing a 15% improvement in accuracy over the old formula. For anthracite, the standard error is 73 calories per gram (305 joules per gram), which represents a 34% improvement in accuracy. For lignite, the standard error is 94 calories per gram (393 joules per gram), indicating a 36% improvement in accuracy. The error of the new formula is related to the ash content; if the ash content (on a dry basis) is greater than 40%, the error increases. Moreover, the higher the ash content, the greater the error. Therefore, it should be noted that when the ash content is above 40%, a different formula should be used. 　　The newly developed formula for calculating the calorific value of coal provides a relatively accurate method for enterprises that do not have calorimetry equipment. However, the level of coal industrial analysis in current enterprise laboratories needs further improvement; the main issues include poor standardization in the operations carried out by analysts, a lack of specialized equipment for coal industrial analysis, and various problems with the existing equipment. Therefore, no matter how accurate the calculation formula is, inaccurate analysis results can still lead to significant errors.

When buying a calorimeter, different models have different operating procedures; of course, if the requirements aren’t high, calculations can be done using classic formulas. I saw a friend share some classic formulas.

Calculation of calorific value: The heat of combustion of coal is primarily generated by the oxidation of the fixed carbon and combustible volatile substances contained in it. Therefore, based on the contents of fixed carbon and combustible volatile matter in coal, as well as their ratio, the calorific value of bituminous coal is calculated using a classical formula: Qf = ×4.18. Where: Qf is the calorific value, in kJ/kg ； C f --Fixed carbon content, % ； V f -- Volatile matter content, % ； A f – Ash content, % ； K -- is a variable that varies depending on the volatile content of the combustible base and the characteristics of the cinder. Volatile matter of the combustible base, Vr = 100×Vf / (Cf + Vf), % Appendix A: Table of classification criteria for coal cinders. Classification code, Characteristics of cinders, Method of determination: 1. Powderous – entirely in a powder form, with no particles that stick to each other; 2. Sticky – turns into a powder or remains mostly in a powder form when lightly touched by hand. Among them, there are larger lumps or granules that turn into powder upon gentle touch. 3: Weak cohesion – it breaks into small pieces when lightly pressed by hand. 4: Non-fusible cohesion – it requires forceful pressing with fingers to break into small pieces; the upper surface of the slag has no luster, while the lower surface has a slight silver-white luster. 5: Non-expanding fusible cohesion – the slag forms a flat cake shape; the boundaries between the slag particles are not easily discernible, and the surface has a distinct silver-white metallic luster, with this luster being even more pronounced on the lower surface. 6: Slightly expanding fusible cohesion – it cannot be broken by finger pressure; both the upper and lower surfaces have a silver-white metallic luster, but there are small expansion bubbles or vesicles on the surface of the slag. 7: Expanding fusible cohesion – both the upper and lower surfaces have a silver-white metallic luster; there is obvious expansion, but the height does not exceed 15 mm. 8: Strongly expanding fusible cohesion – both the upper and lower surfaces have a silver-white metallic luster, and the height of the slag exceeds 15 mm. Appendix B: Table of bituminous coal constants K1/. Vr, % Classification codes for slag characteristics: 1 2 3 4 5 6 7 8 10.00–13.50 84.0 84.0 84.5 84.5 84.5 84.5 84.5 84.5 13.51–17.00 80.5 83.5 84.5 85.0 85.0 85.0 85.0 85.0 17.01–20.00 80.0 82.0 83.5 84.0 85.0 85.0 85.0 85.0 20.01–23.00 78.5 81.0 82.5 83.0 84.0 84.0 85.0 85.0 23.01–29.00 76.5 78.5 81.0 82.0 83.5 83.5 84.5 85.0 29.01–32.00 76.5 78.0 80.0 81.0 82.5 82.5 84.0 84.5 32.01–35.00 73.0 77.5 79.0 80.0 81.5 81.5 83.0 83.5 35.01–38.00 73.0 76.5 78.5 79.5 81.0 81.0 82.5 83.0 38.01–42.00 73.0 75.5 78.0 79.0 80.0 80.0 82.0 82.5 >42.00 72.5 74.5 76.5 77.5 79.5 79.5 81.0 82.0