A techno-economic analysis was completed to compare the use of Hollow Fiber Membrane Modules (HFMM) with the more conventional structured packing columns as the absorber in amine-based CO2capture systems for power plants. In order to simulate the operation of industrial scale HFMMsystems, a two-dimensional model was developed and validated based on results of a laboratory scale HFMM. After successful experiments and validation of the model, a pilot scaleHFMMwas constructed and simulated with the same model. The results of the simulations, from both sizes of HFMM, were used to assess the feasibility of further up-scaling to a HFMM system to capture the CO2from an 800 MWe power plant. The system requirements – membrane fiber length, total contact surface area, and module volume – were determined from simulations and used for an economic comparison with structured packing columns. Results showed that a significant cost reduction of at least 50% is required to make HFMM competitive with structured packing columns. Several factors for the design of industrial scale HFMMrequire further investigation, such as the optimal aspect ratio (module length/diameter), membrane lifetime, and casing material and shape, in addition to the need to reduce the overall cost. However,HFMMwere also shown to have the advantages of having a higher contact surface area per unit volume and modular scale-up, key factors for applications requiring limited footprints or flexibility in configuration.@en

Membrane contactors have been proposed for decades as a way to achieve intensified mass transfer processes. Post-combustion CO2capture by absorption into a chemical solvent is one of the currently most intensively investigated topics in this area. Numerous studies have already been reported, unfortunately almost systematically on small, laboratory scale, modules. Given the level of flue gas flow rates which have to be treated for carbon capture applications, a consistent scale-up methodology is obviously needed for a rigorous engineering design. In this study, the possibilities and limitations of scale-up strategies for membrane contactors have been explored and will be discussed. Experiments (CO2absorption from a gas mixture in a 30%wt MEA aqueous solution) have been performed both on mini-modules and at pilot-scale (10 m2 membrane contactor module) based on PTFE hollow fibers. The results have been modeled utilizing a resistance in series approach. The only adjustable parameter is in fitting the simulations to experimental data is the membrane mass transfer coefficient (km), which logically plays a key role. The difficulties and uncertainties associated with scaleup computations from lab scale to pilot-scale modules, with a particular emphasis on the km value, are presented and critically discussed.@en

With chemical looping combustion (CLC), the condensation of water from the combustion product stream yields essentially pure CO2 that can be readily compressed for transport and storage. Using synthesis gas as fuel, fixed-bed CLC is studied with the optimization of systems ≤ 1 kw. The production of pure CO2 is optimized while the pressure drop over the reactor is minimized. The ability to have a sharp breakthrough of the fuel at the outlet of the reactor is an important parameter and the amount of pure CO2 that can be produced before contamination from the slip of fuel gives a measure of system performance. The total fuel required to complete a full reduction is another indicator of efficiency and has a logarithmic relationship with respect to the size of the reactor. Improvement in the bed design and choice of flow rates should decrease the dependence on scale. With results for three different sizes of reactors, optimal packing and operating conditions can be predicted for increasingly larger systems while being customized to specific applications. Future research implications are discussed. This is an abstract of a paper presented at the 2011 AIChE Spring Meeting & 7th Global Congress on Process Safety (Chicago, IL 3/13-17/2011).@en

Fixed-bed chemical looping combustion is currently being studied experimentally with the optimization of systems up to 1 kW. One of the key advantages for using the fixed-bed configuration over fluidized-beds is the flexibility in operating parameters that allows for application of CLC not only to power production, but also to niche applications, such as the decoupled production of heat and CO 2 for the greenhouse industry. Another advantage is the modularity of the systems that greatly simplifies scale-up once the optimal single reactor design is realized. This is currently being studied by optimizing the production of pure CO 2 while minimizing the pressure drop over the reactor. With results for three different sizes of reactors, optimal packing and operating conditions can be predicted for increasingly larger systems while being tailored to the specific application.@en