THERMODYNAMIC AND ECONOMIC ASPECTS OF THE HARD COAL BASED OXYFUEL CYCLE

摘要

The present study shows a new approach in modelling the hard coal fired Oxyfuel Cycle on the whole. The static process model comprises an Oxyfuel combustion principle applied to an existing state-of-the-art hard coal power plant located in Rostock, Germany. It includes the air separation unit and the flue gas liquefaction unit, which are modelled in detail. As one of the main advances to previous work, the closed simulation of all components in one model delivers a coherent solution with a significantly reduced number of assumptions. The model needs no interfaces between different stand alone simulation tools or manual iteration and transfer of internal variables. Results from a thermodynamic and economic feasibility study on this process are shown and areas relevant for future research are identified. The present study shows the feasibility and prospective key figures of the technology under realistic, comparable and reproducible assumptions and boundary conditions. The basic engineering of the process with a detailed study of the necessary gas separation and flue gas handling technologies is undertaken in the effort to a first stage optimisation of the process. The flowsheet tool Aspen Plus (TM) was used to simulate the overall process. This particular tool was chosen because it offers an advanced data library on chemical substances and allows the calculation of phase equilibria and real gas behaviour during air separation and flue gas liquefaction. Emissions, coal consumption and investment costs of the Oxyfuel power plant are compared to those of the original state-of-the-art hard coal power plant which is used as the reference case.