An Alternative System For Alternative Fuels

Long before energy prices skyrocketed, engineers at FLSmidth’s research and development facility in Denmark had been working on a new type of combustion system that enables alternative fuels to burn more efficiently while also eliminating NOx. In 2018, FLSmidth contacted Mannok in Ireland with an offer to test this new technology at full scale to increase the rate of alternative fuels (AF) through the calciner in its cement facilities.

Having worked with Mannok previously, FLSmidth knew the plant was looking for ways to increase alternative fuel (AF) use without investing in a costly calciner expansion project.

“The FUELFLEX^TM pyrolyser grew out of some work we were doing at our pilot plant in Dania, where we were exploring gasification,” explains Lars Skaarup Jensen, Project Manager, FLSmidth. “We were testing it at pilot scale throughout 2017 and in early 2018, until we were convinced it could work in a real application. Mannok was at 50% fuel substitution in the calciner, and we knew they wanted to increase that rate, but were put off by the high capital and operational costs of expanding the calciner. We felt it was the perfect site for the first project.”

“It was a departure for us,” acknowledges Kevin Lunney, Chief Operations Officer for Mannok, reflecting on those early conversations about the project. “We hadn’t been involved with something like this before – effectively being part of the development of new equipment. But we have ambitious sustainability targets in place, and we could see how this new combustion system could help us achieve them. We decided it was worth trying.”

Ambitious alternative fuels targets

Mannok has been using alternative fuels since 2014. The plant is fortunate to operate in a landscape where solid recovered fuel (SRF) is abundantly available, with the infrastructure already well established to meet the plant’s needs. All of the fuel is sourced from the island of Ireland, and it is all commercial waste that would otherwise go to landfill, so the plant is making a significant contribution to waste management as well as to carbon reduction targets. However, Mannok was limited in how much SRF they could burn with their existing process.

“If we tried to go beyond 50% fuel replacement with the old set-up, we would get buildup in the process,” explains Damian Reilly, Cement Process Manager at Mannok. “We couldn’t take the risk, so we had to keep SRF at 50% of the calciner fuel feed.”

But they desperately wanted to do more. Increased use of alternative fuels is central to Mannok’s 2030 Vision target to reduce carbon emissions by 33% compared to 2020 levels.

“The FUELFLEX proposal came at just the right time to support us in achieving that goal, with the hope of eventually achieving near 100% fuel substitution in the calciner,” says Kevin.

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