An Experimental Investigation Of SO₂ Adsorption By Activated Char-Supported Iron Based Sorbent For Flue Gas Cleaning

With the increase in of coal consumption, the emissions of flue gas from coal-firing continue to increase. SO2 is one of the main components of flue gas. The emissions of SO2 are serious in China, ranking first in the world. SO2 is the main source of acid rain. SO2 causes environmental damage and has serious effects on public health. Lignite is an abundant and low-cost fuel. Efficient use of lignite and controlling of its pollution is critical for economic growth of China.In this study, the lignite char supported Fe-Zn-Cu sorbents were prepared for removal of sulfur gases from flue gas. Flue gas desulfurization experiments were carried out on a fixed-bed reactor at a temperature range of 100-300 ℃ using simulated flue gas containing SO2/O2/H2 O diluted in N2. The exit flue gas composition was analyzed using a flue gas analyzer. The composition and structure of sorbents before and after desulfurization were analyzed by using X-ray Diffraction(XRD), Fourier Transform Infrared spectroscopy(FTIR), STA-MS, and Brunauer-Emmett-Teller(BET) methods. The effects of operating parameters such as temperature, space velocity, and particle size of sorbent were investigated. The optimum experimental conditions were obtained as follows: space velocity of 1500 h-1, at 100℃ with O2 5%(vol) and H2 O 10%(vol). At optimum experimental conditions, the sorbents exhibited the longest breakthrough time of 290 minutes and breakthrough SO2 adsorption capacity of about 2200 mg(SO2) per gram sorbent. Experimental results showed that both char and char supported Fe-Cu-Zn sorbents can effectively adsorb SO2 under the tested conditions. The presence of O2 and H2 O promoted the adsorption of SO2. The SO2 adsorption capacities of char supported Fe-Cu-Zn sorbents increased with increasing the temperature up to 250 ℃. With further increasing the temperature, the SO2 adsorption capacities decreased rapidly. Based on the experimental results, the mechanism of SO2 adsorption with char supported Fe-Zn-Cu sorbent was established.