## 4 Conclusions  
This work mainly studies the characteristic of briquette cyanobacteria as fuel in CLC with hematite as OC. In this paper, the application system of CLC of cyanobacteria is divided into five stages: cyanobacteria powder densification, drying, devolatilization, char burnout and redox cycle. According to the comparative study on different measuring tests, some conclusions are made:  
Cyanobacteria powder is selected as raw material to extrude and pelletize by a single briquetting unit device. Moisture content and compressive load are selected as two experimental factors. Based on the apparent measurement, it is found that the moisture content of 10% is the best moisture content for the cyanobacteria densification process  
Figure 25: SEM analysis (X20000) of hematite oxygen carrier after different cycles (900 °C). through a single briquetting unit. Additionally, the densification process exhibits an evident change when the compressive load increases from 1 to 3 tons, while the molding effect is not that obvious when the compressive load is over 3 tons. At the same time, according to the pressure-crushing tests regarding briquette cyanobacteria samples, the results show that compressive load is conducive to the original mechanical strength of briquette cyanobacteria, and the moisture content of 10% seems better for the cyanobacteria powder densification process. Besides, the drying and devolatilization processes of briquette cyanobacteria under N\({}_{2}\) atmosphere are studied separately. The drying and devolatilization processes are considered the first and second break stage for briquette cyanobacteria in CLC. In the drying process (first break), the forming rate and relax density of residual samples after drying are increased with compressive load no matter what the moisture content and heating rate are. Additionally, the optimal moisture content for the mechanical strength of briquette cyanobacteria after drying is also 10%, which is same with the result through a single briquetting unit. Additionally, a higher heating rate in the drying process would result in the drying process being more violent, and the damage for the internal structure is more severe, which is adverse to the mechanical strength of briquette dewatered cyanobacteria. In the devolatilization process (second break), the mechanical strength evolution is also similar to the drying process. During the devolatilization process, water and volatiles would escape from the briquette cyanobacteria, and there is no difference in the total amount for the same briquette cyanobacteria samples. The releasing rate has no evident effect on the mechanical strength evolution during the devolatilization process. Thermochemical transformation characteristics in CLC process with hematite as OC are analyzed in a single fluidized bed. Compared with the results under the traditional combustion process (quartz sand as bed materials), the carbon conversion efficiency and rate due to the presence of hematite in CLC are evidently increased. Regarding the experimental results of gas yield, the difference in CO yield between CLC and the traditional combustion process is not so much, while CO\({}_{2}\) yield with the presence of hematite is evidently higher. Additionally, less CH\({}_{4}\) is generated during the CLC process due to the consumption by Fe\({}_{2}\)O\({}_{3}\) in hematite. It is inferred that the presence of hematite would enhance the carbon conversion of cyanobacteria and the catalyzed crack for liquid products (tar) from cyanobacteria. The stronger impact force of hematite during the fluidization process would accelerate the fragmentation of the briquette cyanobacteria, which is also advantageous to the carbon conversion of cyanobacteria. At last, the redox cycle experiments are conducted to investigate the reactivity stability and morphological features of hematite in CLC. The reactivity of hematite increases after eight cycles based on the variations in gas yield. Additionally, hematite particles after 10 cycles show an improved porous property.