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NaOH to CO2 is larger than 4.43, the difference between CO2 removal efficiencies at different experimental conditions is small. So, the equivilence ratio of NaOH to CO2 is suggested to have the value of 4.43 in order to save the reaction material of NaOH.

100

CO2 removal efficiency, %

95

90

The CO2 removal efficiencies are measured at different concentrations of NaOH solution, liquid flow rates, total gas flow rates, initial temperatures and CO2 inlet concentrations. Experimental results show that the higher concentration of NaOH solution, the larger flow rate of NaOH solution and the lower flow rate of total gas mixture of nitrogen and CO2 are beneficial to promote CO2 removal efficiency. Besides, an increase in temperature results in higher absorption

performance and higher CO2 removal efficiency.

Experimental results show that the equivalence ratio of NaOH solution to CO2 flow rate is a key parameter and plays an important role in CO2 removal efficiency.

ACKNOWLEDGMENT

This research was supported by Beijing Municipal Commission for Science & Technology under Grant No.Z08040902950803.

85

80

CO2 inlet concentration, % (v/v)

Figure 6. Effect of inlet concentration of carbon dioxide on CO2 removal

efficiency

REFERENCES

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[2] IPCC(Intergovernment Panel on Climate Change), IPCC special

report on carbon dioxide capture and storage. Cambridge: Cambridge University Press, 2005.

[3] Y. F. Diao, X. Y. Zheng, B. S. He, C. H. Chen and X. C. Xu,

“Experimental study on capturing CO2 greenhouse gas by ammonia scrubbing,” Energy Conversion and Management, Vol. 45, pp.2283-2296, 2004.

[4] S. Ma'mun, J. P. Jakobsen, H. F. Svendsen and O. Juliussen,

“Experimental and modeling study of the solubility of carbon dioxide in aqueous 30 mass % 2-((2-aminoethyl)amino)ethanol solution,” Industrial & Engineering Chemistry Research, Vol. 45, pp.2505-2512, 2006.

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Furthermore, when the equivilence ratio of NaOH to CO2 and the ratio of NaOH flow rate to total gas flow rate have nearly the same values at different conditions, the CO2 removal efficiencies have the nearly same values. In Figure 3, the concentration of NaOH solution is 5%, the flow rate of NaOH solution is 200 ml/min, the total gas flow rate is 7.6 l/min, and the initial temperature of the reactor is 280C, the inlet concentration of CO2 is 15% (v/v). The measured CO2 removal efficiency is 91.7%. In Figure 6, the concentration of NaOH solution is 5%, the flow rate of NaOH solution is 180 ml/min, the total gas flow rate is 7.6 l/min, and the initial temperature of the reactor is 320C, the inlet concentration of CO2 is 13% (v/v). The measured CO2 removal efficiency is 91.8% which is as the nearly same value as above in Figure 3.

TABLE II.

Equivilence Ratio of NaOH to CO2 CO2 Removal Efficiency, %

EQUIVALENCE RATIOS IN EXPERIMENTS

In Figure 3, the calculed equivilence ratio of NaOH to CO2 is 4.92 at the above experimental conditions, and the ratio of NaOH flow rate to total gas flow rate is 0.0263 l/l. In Figure 6, the calculed equivilence ratio of NaOH to CO2 is 4.88, and the ratio of NaOH flow rate to total gas flow rate is 0.0237 l/l. The difference of the equivilence ratio and the ratio of NaOH flow rate to total gas flow rate between these two cases is small, it results in small difference of CO2 removal efficiency between these two cases.

IV. CONCLUSIONS

Experimental studies on carbon dioxide capture are carried out in a scrubber using fine spray of NaOH solution.