Modeling Aspects of Chemical-Looping Combustion for Solid Fuels
Licentiatavhandling, 2011

Chemical-looping combustion is a novel technology for combustion of fossil fuel. By using a circulating bed material to transfer oxygen to the fuel, a pure stream of carbon dioxide can be obtained from the flue gas, undiluted by nitrogen. The main advantage of this capture technology is that there is no direct efficiency loss in obtaining the CO2 in a separate stream. The work presented in this thesis is divided into two parts. The first part deals with the behaviour of a 10 kW chemical-looping combustor for solid fuels. This combustor is normally operated in continuous mode but has here been studied with addition of fuel batches. From analysis of gas leaving the air reactor, it was possible to determine the residence-time and residence-time distribution of particles in the fuel reactor. Knowing the solids inventory in the fuel reactor, the circulation mass flow could be directly correlated to measured operational data, i.e. pressure drop, temperature and gas flow in air reactor riser. Using results for carbon-capture efficiency and residence-time distribution, a model was developed which could determine a mass-based reaction-rate constant for char conversion. This reaction-rate constant could also be determined independently from the conversion rates of char during the batch tests. The results showed a good agreement between the two approaches, indicating that the model well describes the behaviour of the unit. The second part of this work presents the design and experimental evaluation of a cold-flow model system, built to simulate a 100 kW chemical-looping combustor for solid fuels. A theoretical background with details on design and calculations on the dynamic similarity is provided. The system has been operated for about 10 hours and shows no indication of imbalances in the bed inventories. Both the internal circulation in the fuel reactor and the circulation between air and fuel reactor could be varied in a large range with only minor impact on the solids inventories. Studies were made on the mass flows, mass fluxes and residence-times in the air and fuel reactors using air as fluidization medium.

Cold-flow model

Residence time

Chemical-looping combustion

Solid fuel

Scaling

VF, Sven Hultins gata 6, Chalmers University of Technology
Opponent: Dr. Jens Wolf, Vattenfall Research and Development

Författare

Pontus Markström

Chalmers, Energi och miljö, Energiteknik

The Application of a Multistage-Bed Model for Residence-Time Analysis in Chemical-Looping Combustion of Solid Fuel

Chemical Engineering Sciences,; Vol. 65(2010)p. 5055-5066

Artikel i vetenskaplig tidskrift

Designing and operating a cold-flow model of a 100 kW chemical-looping combustor

Journal of Logic and Computation,; Vol. 222(2012)p. 182-192

Artikel i vetenskaplig tidskrift

Drivkrafter

Hållbar utveckling

Ämneskategorier

Energiteknik

Styrkeområden

Energi

Fundament

Grundläggande vetenskaper

VF, Sven Hultins gata 6, Chalmers University of Technology

Opponent: Dr. Jens Wolf, Vattenfall Research and Development

Mer information

Skapat

2017-10-08