SPECIAL GASES.

In addition to natural gas, which is the standard fuel, there are a whole range of special gases with high calorific values that are often flared or burned with the aid of a support fuel. Typical gases in this group include landfill gas, sewage gas, refinery gas, coal mine gas, vent gases, and coke oven gas. All of these can be easily utilized thermally, but place increased demands on the combustion system.

In contrast to lean gas, these gases have a significant energy content of more than 15 MJ/m³, but they occur in fluctuating quantities or with fluctuating calorific values. Vent gases from fuel storage facilities are a good example: the tank contents consist of volatile, highly flammable hydrocarbons, so the tanks are inerted with nitrogen during refueling. During loading and unloading, therefore, not only the volume and quantity of gas fluctuate, but also the composition of the gas between pure fuel gas and pure nitrogen.

While the combustible components of refinery gas consist of hydrogen to butane, methane is the main component of landfill gas, sewage gas, or coal mine gas. These also contain significant proportions of carbon dioxide and nitrogen.