The global warming has reached tremendous dimensions in form of water scarcity and long drought periods. Not only in the southern hemisphere, but also in Germany the average temperatures raised since year 2000. There are several possibilities to mitigate the climate change and consequently the effects for humans on the world. Firstly, by reduction of energy consumption, food waste and mass-market consumables. Another possibility is the application of Carbon Capture and Storage (CCS) technologies which has been scientifically researched for several years at the institute of Energy Systems and Technology in Darmstadt. One of the most promising technologies is the carbonate looping (CaL) process. This process has small efficiency penalties in comparison to other CCS technologies. The here investigated CaL process consists of two interconnected circulating fluidized bed reactors in 1-MW scale, carbonator and calciner respectively. The operation of such fluidized bed reactors in combustion and gasification applications has been already industrialized to large scale however with little understanding of the reactor gas-solid hydrodynamics. The objective of this work is to develop and evaluate a numerical model using the coupled Euler Lagrange method with deterministic particle tracking scheme (CFD-DEM) for the simulation of the carbonator reactor in the CaL process. The particle-particle, particle-wall and particle-gas interactions are modelled by a reduced tracking scheme in order to lower the computational time that otherwise would result from the trajectory computation of several billions of particles. The modelling approach applied here is known as coarse graining method. In this approach so-called representative particles, called parcels, are tracked in the domain.