Researchers at Chalmers University of Technology in Sweden say they have demonstrated that using an ilmenite-based fluidized bed material improves the combustion efficiency of waste and biomass while decreasing operating and maintenance costs. In collaboration with Germany-based energy supplier E.on, the researchers say they “have proven the concept in today’s commercial boilers.”

The findings make combined heat and power (CHP) technology “highly interesting both from a profit and a climate perspective, and open [the way] for smarter next generation designs,” according to a press release issued by the university.

From November 2014 to May 2015, researchers at Chalmers University and E.on personnel conducted testing with the new bed material at the Händelöverket CHP plant in Norrköping, Sweden.

Fluid bed material in the form of sand is used to even out heat fluctuations and make the combustion of fuel more efficient. In one of the plant’s five boilers, the silica sand normally used was replaced with an ilmenite-based bed material. The iron-titanium mineral ilmenite and other metal oxides demonstrated that they “have a clear advantage compared to regular sand,” say the researchers.

Ilmenite materials “can transport oxygen inside the combustion chamber from places where there is an abundance of oxygen to places where there is a depletion in oxygen. When oxygen-carrying bed material is circulated inside the chamber, mixing with the fuel, the oxygen is distributed evenly in time and space,” according to the Chalmers researchers.

“This brings forth an array of positive effects, which testing completed in Norrköping confirms,” says Fredrik Lind of the Department of Energy and Environment at Chalmers University, who also served as the project’s coordinator. “The combustion becomes more uniform and efficient. The boiler’s total efficiency increases. The emission of carbon monoxide is lowered radically, as are problems related to ash fouling.”

He continues, “We are now sure that we are able to significantly lower the operational and maintenance costs in most of the thousands of fluidized bed combustor plants that are currently in use internationally.”

The utility firm E.on is making arrangements to use the new ilmenite-based bed material in two boilers in Norrköping later in 2015, and has several other plants in line for consideration. “This is the biggest improvement I have experienced,” says Bengt-Åke Andersson, adjunct professor in combustion technology and a senior specialist at E.on, who says he has worked with fluidizing bed technology for many years. “[It is] a little like placing a turbo charge to the process.”

“One of the advantage [of ilmenite beds] is that it enables the burning of difficult fuels like coarse waste. This could become crucial in the future, if we are to meet our climate goals,” says Lind.

A video with additional details on the new process has been posted to https://vimeo.com/141717645.