Research On Preparation Of Activated Coke And Its Flue Gas Desulfurization

Flue gas desulfurization by activated coke is a resourceable technology that can not only remove SO2, but also recover sulfur element. Therefore, many researches have been done about flue gas desulfurization by activated coke. The key factors for applicating this technology are desulfurization and regeneration of activated coke. Broken activated coke was prepared with caking coal by simplifying the production process, which including coal crushing, preoxidation, carbonization and activation. The production process of preparing the broken activated coke overcame the complex production process of traditional activated coke. Experiments of flue gas desulfurization were conducted with broken activated coke as adsorbent and catalyst carrier respectively on a fixed-bed reactor. The effect of surface properties of activated coke and process conditions on desulfurization efficiency and sulfur capacity research was studied. And the regeneration characteristics of adsorbent and catalyst of activated coke after desulfurizaion was also studied. Finally pilot study was conducted.The effect of preoxidation of caking coal on the property of coal, char and activated coke was studied. The caking index of coal decreased and the porosity of coal increased after preoxidation of coal. Specific surface area, micropore volume and total pore volume of char increased with preoxidation of coal, compared to the char carbonizated without preoxidation of coal. With increasing preoxidation time, specific surface area, micropore volume and total pore volume of activated coke enhanced significantly, but mechanical intensity of activated coke decreased. After preoxidation of coal at 270℃for 1h, the best conditions for preparing activated coke was as follows:carbonization temperature is 600℃, carbonization time is 1h, activation temperature is 900℃, the activation time is 1.5h and the flow of steam is 406 mL·min-1. On these conditions, specific surface area, micropore pore volume, total pore volume mechanical strength and sulfur capacity of is 245.20m2·g-1,0.0968m3·g-1,0.1183m3·g-1, and 95.2% respectively. The sulfur capacity of activated carbon is 65.8mg·g-1.Experiments of desulfurization were conducted with activated coke as adsorben. The results show that activated coke has higher sulfur capacity and longer breakthrough time under lower inlet concentration of SO2, higher concentration of O2 and steam. Reducing the flow also can increase breakthrough time of activated coke. Reaction temperature of 80℃～100℃is suitable. Specific surface area, micropore volume and total pore volume of activated coke were greater, sulfur capacity is bigger. Surface basictiy concentration of activated coke was higher, sulfur capacity is bigger. Based on experimental data, dynamics equation and mathematical model of flue gas desulfurization by activated coke were established. Mobile bed desulfurization tower of dealing with the flow of 1000Nm3·h-1 was designed and established according to the parameter, the experimental results agreed well with the designed results.CuO/AC catalyst was prepared with activated coke, Experiments of desulfurization were conducted with CuO/AC. The results show that activated coke has higher sulfur capacity and longer breakthrough time under lower inlet concentration of SO2 and lower flow velocity in oxygen gas environment. Steam didn't participate in the reaction of flue gas desulfurization. Reaction temperature of 200℃-240℃is suitable. The sulfur capacity of CuO/AC first increases then decreases with increasing copper loading on activated carbon. Considering the sulfur capacity of CuO/AC and the utilization of copper, copper content of 5%～10% is prefer. CuO/AC was prepared by activated coke treated by nitric acid, the sulfur capacity of CuO/AC is improved obviously. Based on the experiment data, dynamics model of flue gas desulfurization by CuO/AC was established, Cu/S mole ratio of the simulation results and experimental results are almost the same using this model.Saturated activated coke and deactivated CuO/AC were regenerated at 400℃under inert atmosphere, the regeneration efficiency is close to 100%. The sulfur capacity of activated coke and CuO/AC has no change almost after several desulfurization-regeneration cycles. SO2 concentration of regeneration gas are higher at higher temperature or under smaller flow of carrier gas.