Model-based evaluation of a chemical looping combustion plant for energy generation at a pre-commercial scale of 100 MW th Petteri Peltola ⇑ , Jouni Ritvanen, Tero Tynjälä, Timo Hyppänen Lappeenranta University of Technology, LUT Energy, P.O. Box 20, FI-53851 Lappeenranta, Finland article info Article history: Received 24 May 2013 Accepted 27 July 2013 Keywords: Chemical looping combustion CO 2 capture Modelling Scale-up Simulation Steam turbine cycle abstract Chemical looping combustion (CLC) is an emerging combustion technology with an inherent separation of the greenhouse gas CO 2 . The feasibility of CLC has been proven in various small-scale units worldwide, but the large-scale realization of theoretical or small-scale units is still lacking due to many technical challenges. Most of the existing CLC installations use a configuration of two interacting fluidized bed reactors, and even though the fluidized bed technology is mature and well-established, a high level of uncertainty is included in the attempts to up-scale the reactor system involved in CLC. For progressive scale-up of the new technology, a preliminary design of a 100 MW th pre-commercial CLC unit for gaseous fuels is presented. A reactor-level model was used to predict the performance of such a system, and as a result, the operation of the system was characterized and valuable information of the parameters affect- ing the process was received. For cost-effective energy generation with efficient CO 2 capture, the power plant-level integration of CLC must be conducted carefully, and different plant configurations need to be investigated to find the most optimal solution. Hence, the integration of the reactor system and steam turbine cycle for power production was studied resulting in a suggested plant layout including a CLC boi- ler system, a simple heat recovery setup, and an integrated steam cycle with a three pressure level steam turbine. A plant-level model was used to evaluate the viability of the plant, and without the purification and compression of CO 2 , the net cycle efficiency of 42.8% was obtained. It was also found that a drop of 2% points in the degree of fuel conversion decreases the net cycle efficiency by about 1% point. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The attempts to restrain CO 2 emissions into the atmosphere have led to the development of new low-cost carbon capture tech- nologies to be used in fossil fuel based power production. First introduced in 1954 [1], chemical looping combustion (CLC) is con- sidered as a promising combustion technique, in which metal oxide particles are used to transfer oxygen from an air reactor (AR) to a fuel reactor (FR) as shown in Fig. 1. In CLC, the air is not mixed with the fuel, and the CO 2 in the flue gas does not be- come diluted by the inert nitrogen, like in the conventional com- bustion process. Ideally, the exhaust gas from the FR consists only of CO 2 and water vapor, and a pure stream of CO 2 can be ob- tained with minor losses of energy caused by the condensation of the water vapor [2]. Majority of the work in different areas of CLC research has been done within the last decade [3]. To date, more than 900 different materials have been investigated in order to find oxygen carrier materials suitable for the process, mostly including active oxides of iron, copper, nickel, and manganese [4,5]. In addition, thousands of hours of experience in continuous CLC operation have been gained from various pilot units with sizes varying from 0.3 to 120 kW th [6]. The research has mainly focused on gaseous fuels, but in the last years important work has been dedicated to adapt- ing the process to solid fuels [7]. 1.1. Scale-up of the technology Most of the existing CLC systems use the configuration of two interconnected fluidized bed reactors working at atmospheric pressure. One important advantage of the use of a fluidized bed configuration for the CLC process is that circulating fluidized bed (CFB) technology is mature and well-established, and has been used for decades for various processes. Compared to other reactor designs, a fluidized bed reactor has a lot of advantages: uniform particle mixing, excellent gas–solid contacting, lack of hot spots even with highly exothermal reactions, improved internal heat transfer, and the ease of solids handling which is particularly important if solid particles need to be replaced due to attrition or loss of reactivity [8]. On the other hand, the scale-up problems of fluidized bed reac- tors are also well known. According to Johnsen et al. [8], the critical aspects relate to the impact of surface/volume and height/diameter 0196-8904/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.enconman.2013.07.062 ⇑ Corresponding author. Tel.: +358 503657889. E-mail address: petteri.peltola@lut.fi (P. Peltola). Energy Conversion and Management 76 (2013) 323–331 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman