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Recent chemical-looping achievements at Chalmers University of Technology

Henrik Leion
Environmental Inorganic Chemistry, Chalmers university of Technology
Gothenburg, Sweden

June 3, 2011 at 10:00am
Ben Bandy Conference Center
UK Center for Applied Energy Research

The first demonstration rig for continuously operating CLC ever was designed and constructed at Chalmers in 2004. A few years later the first demonstration rig for continuous CLC of solid fuels was erected next to it. Chalmers were the first to demonstrate synthesis gas generation via chemical-looping, so called chemical-looping reforming, CLR, and the first to demonstrate chemical-looping with oxygen uncoupling, CLOU. Today the chemical-looping research at Chalmers has three main focuses: development of combined oxide oxygen carriers, the use of chemical-looping in indirect gasification and, most importantly, scale-up and development of chemical-looping units.

Development of combined oxide oxygen carriers: The oxygen carriers for CLC has primarily focused on particles with NiO, Fe2O3, Mn2O3, CuO or Co3O4 as single active phase, often supported on Al2O3, ZrO2 or other inert materials. For CLOU the system CuO/Cu2O is the only technical feasible single metal system. But the fairly high cost and the low melting point for Cu may restrict the usefulness. However, combined manganese oxide systems with one or more added metal cations potentially have CLOU properties. Mn is a non-toxic, fairly inexpensive, and can easily form a number of different oxides with other metals. The initial work with the Ca/Mn oxide system, developed by SINTEF in Norway, is very promising. Other interesting options are Fe/Mn and Mg/Mn oxides.

The use of chemical-looping in indirect gasification: Chalmers has recently started a large research project aiming to produce biogas with indirect gasification and a 2 MW indirect gasifier has been built as an integrated part of the 12 MW research CFB at Chalmers. One of the problems with gasifying biomass is the high fraction of tars in the product gas. Therefore a part of this project is to use Chemical-Looping Reforming (CLR) to crack tars, partly as a way of better utilizing the heating values of the tars and partly to simplify the tar cleaning, since the flue gas by this arrangement does not need to be cooled. The challenge is to find oxygen carriers that react selectively with tars and not with lighter components such as methane.

Scale-up and development of chemical-looping units: The major focus for the CLC-researchers at Chalmers is to finish the construction of a 100 MW CLC-unit for solid fuel. Other important work is the restoration of the 10 kW unit for gaseous fuel in order to beat the current record of 1000 h of continuous operation. In order to improve the operation in our 10 kW unit for solid fuel we are using additives to ilmenite, as well as completely new oxygen carriers. Finally, after some modifications, we just recently succeeded in running our 300W unit with liquid fuel.