A Handle on Heating Value
Along with the German Chamber of Commerce, Heinrich Unland, managing director of German technology developer APOS, recently visited the U.S. to survey the country’s biomass power market. Aware that the German bioenergy industry is much more mature than that of the U.S., Unland’s visit was mainly to determine the potential level of interest in a new biomass boiler tool APOS has developed. Unland says there is a global need for the FuelOPT system, which has been on the market for almost two months.
When fuel is pushed into a biomass boiler—whether it’s wood chips or hog fuel—the operator faces the challenge of an ever-changing heating value. “That’s simply because the material has greatly varying water, sand and ash content,” Unland explains, adding that it can have a significant impact on the heating value of the fuel.
Typically, a boiler management system pushes in a consistent amount of fuel, assuming the heating value is even. “The amount of energy going into the boiler varies considerably, however, because of that rapidly changing biomass heating value,” Unland says. This creates an unwanted effect on boiler steam production.
“What you want is a turbine running at maximum production all the time to generate the most power to make the most money,” Unland says. He was faced with the problem years ago, as managing director of a company that ran biomass power plants in Germany, and never found a technical solution. Unland formed his own team and developed a solution: an optical system that analyzes biomass fuel online without affecting the fuel flow in the power plant. “It uses spectrocity as its basis,” Unland explains. “Light is put on the fuel somewhere in the conveyors during the transportation process, and a reflection comes back that we’re able to analyze.”
That reflection or light is displayed on a spectrometer where a statistical analysis is performed. Water and sand content can be identified in real time, as well as other parameters, according to Unland. Using APOS software that is integrated into the existing plant control systems, the heating value is calculated. “This enables the plant to decrease the ups and downs that it usually has, allowing for a smoother boiler operation, and at the end of the day, it increases power production using the same amount of fuel.”
While the system could work for any kind of biomass boiler, Unland says it may not make economic sense in small boilers. “The payback period isn’t as attractive then, and our goal is a period of two years or less. A 5 MW boiler would take five years to reach pay off, so for two years, it would take a 10 MW boiler with an annual consumption of 30,000 metric tons (33,000 tons) of wood fuel.”
Since the FuelOPT has only been on the market a short time, the only installation is a pilot application at a 30 MW power plant in Brunsbüttel, Germany, but performance data is available, according to Unland. Interest and feedback from the market has been very positive, he adds. “[Varying heating value is] really a core problem of all biomass plants, especially ones running fresh wood, or a combination of fresh wood and demolition wood.”