THERMAL¦ tinued growth and development of boilers and gasification with these companies has spanned more than 30 years,” Partanen says. As a result of lessons learned over the past 30 years, Metso currently has the two largest CFB gasification plants in successful operation in the world. The Vaasa, Finland, facility, cofires up to 40 percent forest residue in an existing 230 MW electric and 170 MW thermal pulverized coal utility boiler and is the first utility-scale application for Metso. Generating 230 MW electricity and 170 MW thermal, the facility has been in successful operation since December 2012. There are benefits to gasification cofiring, Partanen says, one of which is reusing the existing infrastructure inclusive of the boiler/turbine, an investment cost of approximately 30 percent of a new biomass plant. Additionally, cofiring with biomass provides the option to keep an old, coal-fired plant in operation by reducing mercury, CO2, and SO2 emission limits that might otherwise require new emissions controls equipment. The facility Metso completed in the city of Lahti, Finland, uses sorted municipal solid waste (MSW) to produce 90 MW of thermal energy and 50 MW of electricity for district heating. “This is Metso’s first demonstration facility using sorted MSW, and has been in successful commercial operation since December 2011,” Partanen says. “These are the first forest residue and sorted MSW gasification systems to demonstrate that gasification of these feedstocks can be successfully applied in both the industrial and utility sectors.” Large-scale biomass gasification projects, such as the aforementioned, offer some advantages over small or medium-sized projects, the
biggest of which is economies of scale. “Large-scale gasification can be utilized at large utility and industrial applications where smaller systems would not be cost effective,” Partanen says. “It’s more costly to build and operate multiple small systems than a single large system. The fact that Metso has demonstrated that up to 40 percent of the coal can be displaced with syngas in a utility boiler with no boiler de-rating is an important milestone. Smaller systems don’t make economic sense in utility applications.” On attributes that have allowed Metso to overcome challenges associated with large-scale biomass gasification, Partanen says it has been Metso’s long history of R&D in gasification technology and persistence that has pushed the technology into commercialization. “[Gasification technologies] must go through a learning cycle, and that takes time,” he adds. “Success is also based on understanding what is required, and then building the equipment and systems that fit the need. An example is fuel properties, and the effects these properties will have during the gasification process. Tars have always been a problem with gasifiers, and understanding how to deal with these tars is critical…an understanding of fuels and how different fuel characteristics affect fluidized bed boiler operation is the key to how [Metso] has overcome the challenges associated with gasification.” Author: Anna Simet Managing Editor, Biomass Magazine asimet@bbiinternational.com 701-751-2756
SARY A N NIVER 1984 –
2014
JUNE 9 – 12, 2014 Indianapolis, IN
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