Determination of Moisture in Coal
Coal is one of the most abundant energy resources on the planet, supplying almost 30% of the global energy needs. It is important to have an accurate measurement of moisture in coal before it can be used efficiently. This is because water has high heat capacity, which means that it absorbs more heat when heated, making it difficult to reach higher temperatures. Additionally, water can cause problems in coal-fired power plants due to steam explosions, corrosion and wear and tear on the machinery. Knowing the amount of moisture in coal is therefore essential for efficient operation of power plants.
The determination of moisture in coal is done using a variety of methods and instruments. Some of the most commonly used methods include the Karl Fischer titration, combustion bunkers, and the drop-in-pan methods.
The Karl Fischer titration method involves measuring the amount of moisture in coal by titrating a sample of coal with a reagent. After titration, the excess reagent is volumetrically determined and the concentration of water in the sample may then be calculated. This method is quite accurate but is often expensive and time consuming.
The combustion bunker method uses a sealed chamber for the combustion of coal. The amount of water present in the sample is measured by recording the difference in weight before and after combustion. This method is suitable for determining the very low levels of moisture, but it can be difficult to get an accurate measurement at moisture levels above 10%.
The drop-in-pan method is the simplest and most economical way of determining the moisture in coal. A sample of coal is placed in an open pan and weighed. The pan is then placed in a thermal oven, where the coal is heated. The weight of the coal is then determined after the coal is cooled. This method is accurate and easy to perform, but can only measure higher moisture levels.
All the above mentioned methods have their own merits and demerits, and choosing the right method depends on the accuracy required and the amount of sample available. In addition to the techniques mentioned above, there are also more sophisticated techniques such as waveguides and near infrared programs for the determination of moisture in coal.
When measuring moisture in coal, it is important to remember that moisture levels can vary from sample to sample. Thus, it is important to take several measurements from different samples of coal, before making a determination. Additionally, the presence of other substances such as sulfur and ash in coal can affect the accuracy of the moisture determination.
In summary, although water is an important energy source, it can be detrimental to coal-fired power plants if the amount of moisture in coal is not accurately determined. Several methods exist for the accurate measurement of moisture in coal, and it is important to select the right method depending on the accuracy required and the sample size available.
