According to researchers in Sweden, a new material used in biomass beds can increase efficiency of waste while decreasing costs for biomass boilers.
The bed material – metal oxide – could be a replacement for sand and other conventional materials used in beds for boilers, based on its oxygen-carrying properties.
The researchers at Chalmers University of Technology, in conjunction with the energy company Eon, found that metal oxide is better at carrying and distributing oxygen throughout the bed, which helps drive up combustion efficiency. The material – an iron-titanium mineral ilmenite – has an advantage over silica sand that is normally used with circulating fluidized bed (CFB) boilers in that it more even distributes oxygen.
According to researchers, this even distribution creates a more efficient and uniform combustion that not only increases efficiency, but also lowers carbon monoxide emissions. The end result is lower operational and maintenance costs and a higher profit margin for CFB boilers.
CFB Boilers Undergoing Test Runs
Eon plans to implement the new material in the beds of its CFB boilers in 2015, starting with two boilers and gradually incorporating the material layout in its new reactors. Researchers predict that metal oxide-based materials will become more prevalent in CFB boilers throughout the world as a result of this development.
The development was born out of years of attempting to solve a common problem: dealing with unburned fuel in commercial reactors. Trials were begun in test reactors in 2013 and continued through 2014, although the collaboration between Chalmers and Eon began in 2007.
The choice of bed material was determined to be one solution to the problem. Bed material is important due to the nature of burning biomass fuel: it tends to have lower overall heating value, lower fixed carbon, and a higher level of moisture, necessitating an inert bed on which to burn the fuel and a boiler-type apparatus to more efficiency convert the fuel to energy in the form of steam. Additionally, using a bed can lower the operating temperatures from 2,200 degrees Fahrenheit to 1,400-1,600 degrees Fahrenheit.
For these reasons, CFB boilers are the most common types of boilers for biomass, meaning this new development should make a substantial impact on the industry.
Developing Efficient Biomass Boilers
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