Abstract
Solvent-based post-combustion CO2 capture technologies are key to timely decrease industrial CO2 emissions. However, the flue gas composition differs among different industries so that different optimal operating conditions are expected. This work provides a methodology to determine the operating conditions that minimize energy consumption and maximize productivity of the capture process, for given flue gas composition and process specifications, while keeping the time required for process development at a minimal level. Firstly, it carries out a comprehensive selection and calibration of the model. Secondly, it applies a step-wise heuristic optimization procedure. In this work, this methodology has been demonstrated by means of the Chilled Ammonia Process (CAP) applied to cement plants. The optimal CAP operation has led to reboiler duties as low as 2.1 MJthkgCO2captured-1, while maintaining the productivity of the CO2 absorber, thus the column height, at values similar to those typical of the power plant application.
Highlights
Industrial processes are responsible for 20–25% of global greenhouse gas emissions (GCCSI, 2017; International Energy Agency, 2017), with the iron and steel production and the cement industry alone responsible for more than 50% of industry-related CO2 emissions (International Energy Agency, 2017)
For cement production, where 60% of CO2 emissions stem from the calcination of limestone (CaCO3) to produce CaO, decarbonization relies on the deployment of carbon capture and storage technologies (International Energy Agency, 2018)
The model features described above, e.g. including the composition effects in the rate constants, and the results shown in Fig. 2 make the rate-based model presented in this work suitable for process simulation and optimization applied to flue gases with higher CO2 concentration
Summary
Industrial processes are responsible for 20–25% of global greenhouse gas emissions (GCCSI, 2017; International Energy Agency, 2017), with the iron and steel production and the cement industry alone responsible for more than 50% of industry-related CO2 emissions (International Energy Agency, 2017). 25% of industrial CO2 emissions are intrinsic to the process and can be avoided either by changing the product, the process, completely, or by applying CO2 capture and storage. While the former could be preferred in the long term (yet changing steel and cement production has proved very difficult), the latter would allow to timely decarbonize such key emitters as they are. Absorption-based post-combustion technologies are a commercial, suitable option for CO2 capture from industrial point sources: they allow for retrofitting without affecting the industrial manufacturing process (Bui et al, 2018; Hills et al, 2016).
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