In this work, a data basis for the Calcium Looping (CaL) Process is established by experimental investigations on a 200 kWth pilot plant with realistic process conditions. On this foundation, a CaL plant consisting of coupled fluidized bed reactors can be designed, scaled and operated.
Initially, the process and its characteristic parameters for carrying out the experimental investigations are defined and theoretical backgrounds are outlined. The implementation of the plant technology with different variants of reactor and interconnection design as well as possibilities with regard to operational flexibility are discussed as an essential technical part of the work. As a basis for the experimental work, main aspects of the plant and process behavior are explained. These are, the hydrodynamic, thermal and dynamic behavior in operation with process-technically advantageous and operationally desirable pressure and temperature profiles of the reactors and the overall system.
The experimental investigations cover the fields of carbonator and regenerator operation as well as findings on sorbent behavior. Many factors contribute to the achieved goal of a carbonator separation efficiency significantly above 90% CO2 . These are investigated in detail and characteristic operating windows are derived. The main factors influencing the carbonator process operation are the specific parameters for sorbent circulation, the reactor inventory and the supply of fresh limestone, coupled with the temperature operating window, the composition of the flue gas - in particular the effect of moisture, and the influence of sulfur. As a major affecting factor on the quality of CO2 capture, the sorbent regeneration process is comparatively analysed with regard to calcination behavior under air and real oxygen combustion conditions up to 50 vol.-% with CO2 recirculation. From this, temperature windows for achieving a high degree of calcination at real gas atmospheres will be worked out. In addition, the influence on the sorbent capacity in the reactor bed will be investigated. As a second primary objective of a CCS process, the accumulation of CO2 to volume fractions significantly above 90% is presented and trace substances such as sulfur and nitrogen oxides are investigated. For a detailed understanding of sorbent-specific effects, investigations using TGA and SEM will be carried out, as well as particle size analysis to determine attrition under real process conditions.
Using process simulation, an energetic evaluation and optimization of the process is carried out. For this purpose, an existing process model is extended by a reaction model and a realistic plant modeling with CO2 recirculation train. By means of the simulative calculation of operating windows, the process is optimized on the basis of its characteristic parameters and efficiency potentials are shown on the basis of the net efficiency loss by CO2 capture. Finally, a method for simulation-based process design and up-scaling is developed.