What is the formula for Wobbe index?
The Wobbe index may be defined as Iw = Vc/(Gs)^1/2 where Iw is the Wobbe index, Vc is the HHV value for the fuel and Gs is its specific gravity. Calculate the Wobbe index for a typical fuel. The HHV of natural gas is typically 1,050 Btu / cubic foot and its specific gravity is about 0.59.
What is meant by Wobbe index?
The Wobbe Index (WI) or Wobbe number is an indicator of the interchangeability of fuel gases such as natural gas, liquefied petroleum gas (LPG), and town gas and is frequently defined in the specifications of gas supply and transport utilities.
What is Wobbe index correction?
An alternate format for the fuel gas composition correction is to express the performance changes as a function of the fuel Wobbe Index. Wobbe Index represents the energy density of the gas and is commonly used to gauge the extent to which a given gas is compatible with a given combustion system design.
What is Wobbe index for gas turbine?
Most combustion turbine owners/operators and original equipment manufacturers (OEMs) measure gas composition and interchangeability using the “Wobbe Index.” The Wobbe Index defines the heating value of a quantity of gas that will flow though a hole (combustion turbine burner tip) of a given size in a given amount of …
What is the difference between calorific value and Wobbe index?
The key difference between Wobbe index and Calorific Value is that the Wobbe index indicates the interchangeability of fuel gases whereas the Calorific Value indicates the total amount of heat energy generated when we burn a unit mass of fuel.
What is the gross calorific value?
Gross calorific value is the amount of heat produced as a result of the complete combustion of a unit volume of a substance. It is the absolute value of the specific energy of combustion for a unit mass of a substance. We can generally call it calorific value or high heating value.
What is Wobbe number?
The Wobbe Number or Wobbe Index describes the way in which the gas burns and is calculated as a factored ratio of CV and specific gravity (SG otherwise known as relative density).
What value does a Wobbe index show?
The Wobbe Index is a measure of the interchangeability of fuel gases and their relative ability to deliver energy. It gives an indication of whether a turbine or burner will be able to run on an alternative fuel source without tuning or physical modifications.
How is methane number calculated?
You can calculate this with the chemical formula by dividing the number of hydrogen atoms by the number of carbon atoms, but heavier fuels will more likely be labeled by H/C ratio than by chemical formula. This example will use a fuel with an H/C of 3.72. This answer is the methane number.
What is the basic formula for calculating gross calorific value?
Calculate a) Gross calorific value, moist basis b) Net calorific value, dry basis c) Net calorific value, moist basis d) Gross calorific value, dry basis using Dulong formula. = 32060.2 KJ/Kg NCV = GCV – 24.44(9×%H + %M) = 30630.26 KJ/Kg Thus NCV = 0.955 times GCV in this case. 3. Note: Change in basis increases CV.
What is the Wobbe number of natural gas?
Pure methane has a Wobbe number of 1363; natural gas as piped to homes in the United States typically has a Wobbe number between 1310 and 1390.