Explain in detail with a suitable diagram how you will determine the GCV and NCVof a given coal sample.
Question
Explain in detail with a suitable diagram how you will determine the GCV and NCVof a given coal sample.
Solution
To determine the Gross Calorific Value (GCV) and Net Calorific Value (NCV) of a given coal sample, you can use a bomb calorimeter. Here are the steps:
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Preparation of the Sample: The coal sample should be ground to a fine powder (less than 60 mesh) and dried in an oven at about 108 degrees Celsius for one hour to remove moisture.
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Weighing the Sample: Weigh about 1 gram of the coal sample and place it in the crucible of the bomb calorimeter.
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Setting up the Bomb Calorimeter: The bomb calorimeter consists of a strong vessel (the bomb), which can withstand high pressures and is surrounded by a jacket of water. The bomb is filled with oxygen and the coal sample is ignited electrically.
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Ignition: The coal sample is ignited by passing an electric current through a wire coil or fuse wire which ignites the coal sample. The combustion of the coal sample under high pressure of oxygen results in the production of heat.
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Measurement of Temperature Rise: The heat produced by the combustion of the coal sample is absorbed by the water jacket and results in a rise in temperature of the water. This rise in temperature is measured using a thermometer.
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Calculation of GCV: The GCV is calculated using the formula:
GCV = W x (T2 - T1) x F
where: W = weight of water in the calorimeter T2 = final temperature of the water T1 = initial temperature of the water F = calorific value factor of the fuse wire
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Calculation of NCV: The NCV is calculated by subtracting the latent heat of vaporization of the water produced during combustion from the GCV. The formula is:
NCV = GCV - (9 x H x 587)
where: H = percentage of hydrogen in the coal sample
The diagram of a bomb calorimeter is as follows:

Image Source: ResearchGate
The bomb (B) is filled with oxygen and the coal sample. It is then placed in a water jacket (W) and the coal sample is ignited. The heat produced is absorbed by the water and the temperature rise is measured.
Similar Questions
One coal sample was analyzed and showed 90% C, 8% hydrogen, and 2% ash. 2.0 gof this coal sample was burned in a bomb calorimeter and the temperature of 2.5Kg water was increased from 25 to 35°C. Calculate the GCV and NCV of coal. Given:Water equivalents the instrument and the latent heat of vaporization are 1500 gand 580 cal/g, respectively.
0.6 g of a coal sample with 92% C, 5% hydrogen, and 3% ash, caused a rise in the temperature of 2000 g water by 3.2 °C in a bomb calorimeter experiment. Calculate the GCV and NCV of coal, given. Water equivalent = 200 g. Ans:GCV= 11733.3 cal/g NCV= 11469.2 cal/g
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