Frequently Asked Questions
1. What is GCV DAF?
GCV DAF (Gross Calorific Value on Dry Ash-Free basis) is the calorific value of fuel after excluding moisture and ash. It represents the maximum heating value of the combustible part of the fuel.
Simple explanation:
- Assumes 0% moisture.
- Assumes 0% ash.
- Used as a standard laboratory value to compare fuels.
2. What is GCV ARB?
GCV ARB (Gross Calorific Value on As Received Basis) is the actual calorific value of the fuel as received, including its moisture and ash content. It represents the usable energy available in real operating conditions.
Simple explanation:
- Includes the fuel’s actual moisture and ash.
- Reflects the energy available under real operating conditions.
- Used for boiler efficiency, steam generation, and fuel cost calculations.
3. Why is GCV ARB lower than GCV DAF?
Moisture and ash reduce the effective heating value of fuel. Therefore, GCV ARB is always lower than GCV DAF unless the fuel contains no moisture or ash.
4. What is Fuel Mix Percentage?
Fuel Mix Percentage is the proportion of each fuel used in the boiler. The total of all fuel mix percentages must equal 100% for accurate steam cost calculations.
5. Why must the Fuel Mix total be 100%?
The calculator distributes fuel cost and steam production based on the selected fuel mix. If the total is not 100%, the calculated steam cost will be incorrect.
6. How is Steam kg/kg Fuel calculated?
Steam production is estimated from the fuel’s GCV ARB, the energy required to produce steam (steam enthalpy), and the selected boiler efficiency.
7. What is Boiler Efficiency?
Boiler efficiency is the percentage of fuel energy converted into useful steam. For example, a boiler operating at 85% efficiency converts 85% of the fuel’s heat into steam, while the remaining 15% is lost through flue gases, radiation, and other heat losses.
8. What is Steam Enthalpy?
Steam enthalpy is the total heat energy contained in 1 kg of steam, measured in kJ/kg. It depends on the steam pressure and temperature and is used to calculate steam production and boiler fuel consumption.
9. How does Moisture affect steam cost?
Higher moisture reduces the usable energy in the fuel, resulting in lower steam production and a higher steam cost.
10. How does Ash content affect boiler performance?
Higher ash content reduces the combustible portion of the fuel, lowers the effective calorific value, increases ash handling, and may reduce boiler efficiency.
11. Why is Boiler Efficiency set to 100% by default?
The default value of 100% allows theoretical comparisons. Users should enter their actual boiler efficiency (typically 75–90%) to obtain realistic steam cost estimates.
12. What unit is used for Steam Cost?
The calculator displays steam cost in Rs/kg and Rs/ton, making it easy to compare operating costs for different fuels and fuel blends.