Biofuels

Biogenic fuels are biological/organic in origin. They may therefore be derived from plants or may be a product of fermentation or digestion of organic materials. Chemical and physical properties vary considerably depending on the fuel. For example, some substances are solid at room temperature, while others are liquid or gaseous.

Typical biofuels include:

• Canola oil
• Soy oil
• Palm oil
• Biodiesel
• Biogas
• Bio natural gas
• Sewer gas
• Gas from biomass gasification
• Wood dust

They have in common a high heat value of more than 15 MJ/kg (15 MJ/m³) and a CO₂ balance for combustion. If sewer gas or bio gas was previously being released with no controls, thermal utilization can relieve an even greater climate burden: These gases contain methane, which is harmful to climate and which is converted into CO₂ during combustion.

Although the combustion of canola oil, soy oil or biodiesel works similarly to the use of light or heavy oil to a great extent, each individual fuel places great challenges on the firing system: All these substances differ in their heat value, pour point, viscosity and combustibility. Because palm oil is solid at room temperature, it must be preheated, more or less depending on which burner is used, so that it can be pumped and atomized.

These mostly biogenic liquids also contain a certain amount of free fatty acids, which have a very corrosive effect. In this case all parts in contact with the fuel must be made of stainless steel.

Biogenic gases also differ greatly between themselves. They contain either hydrogen or methane as the main combustible component. They also contain nitrogen and may fluctuate greatly in their composition. This fluctuating composition together with discontinuous occurrence of the gas requires exact monitoring of the heat value as well as precise and rapid control of the amount of air, biogas and other fuels.

In addition to the SSB swirl burner series or the DDZG steam pressure atomizer series, the SKVG and SKVG-A rotary cup atomizer series can also be used for combustion of biogenic fuels. The Eurotherm and TEMINOX GLS pressure atomizer series are also suitable for use if light fuel oil will be used in addition to biogas as a second fuel.

Incidentally, while wood pellets have now become an established biogenic fuel, use of wood dust for the same purpose is generally overlooked. However, ground wood can be easily, cleanly and very efficiently used to produce energy. The SSB-D swirl burner series is ideal for this purpose: It offers not only especially low emissions and a wide control range, but also the option of utilizing additional fuels.

Whatever burner is used, a decision to use biogenic fuels is always a decision for improved CO₂ balance and reliable heat supply in times of fluctuating fuel markets.