Yangyang Guo

Regeneration performance and carbon consumption of semi-coke and activated coke for SO2 and NO removal

To decrease the operating cost of flue gas purification technologies based on carbon-based materials, the adsorption and regeneration performance of low-price semi-coke and activated coke were compared for SO2 and NO removal in a simulated flue gas. The functional groups of the two adsorbents before and after regeneration were characterized by a Fourier transform infrared (FTIR) spectrometer, and were quantitatively assessed using temperature programmed desorption (TPD) coupled with FTIR and acid-base titration. The results show that semi-coke had higher adsorption capacity (16.2% for SO2 and 38.6% for NO) than activated coke because of its higher content of basic functional groups and lactones. After regeneration, the adsorption performance of semi-coke decreased because the number of active functional groups decreased and the micropores increased. Semi-coke had better regeneration performance than activated coke. Semi-coke had a larger SO2 recovery of 7.2% and smaller carbon consumption of 12% compared to activated coke. The semi-coke carbon-based adsorbent could be regenerated at lower temperatures to depress the carbon consumption, because the SO2 recovery was only reduced a small amount.

Adsorption and desorption of SO2, NO and chlorobenzene on activated carbon

Activated carbon (AC) is very effective for multi-pollutant removal; however, the complicated components in flue gas can influence each others adsorption. A series of adsorption experiments for multicomponents, including SO2, NO, chlorobenzene and H2O, on AC were performed in a fixed-bed reactor. For single-component adsorption, the adsorption amount for chlorobenzene was larger than for SO2 and NO on the AC. In the multi-component atmosphere, the adsorption amount decreased by 27.6% for chlorobenzene and decreased by 95.6% for NO, whereas it increased by a factor of two for SO2, demonstrating that a complex atmosphere is unfavorable for chlorobenzene adsorption and inhibits NO adsorption. In contrast, it is very beneficial for SO2 adsorption. The temperature-programmed desorption (TPD) results indicated that the binding strength between the gas adsorbates and the AC follows the order of SO2>chlorobenzene > NO. The adsorption amount is independent of the binding strength. The presence of H2O enhanced the component effects, while it weakened the binding force between the gas adsorbates and the AC. AC oxygen functional groups were analyzed using TPD and X-ray photoelectron spectroscopy (XPS) measurements. The results reveal the reason why the chlorobenzene adsorption is less affected by the presence of other components. Lactone groups partly transform into carbonyl and quinone groups after chlorobenzene desorption. The chlorobenzene adsorption increases the number of C=O groups, which explains the positive effect of chlorobenzene on SO2 adsorption and the strong NO adsorption.

Influence of pollutants’ control facilities on PM2.5 profiles emitted from an iron and steel plant

ABSTRACT A typical long process in an iron and steel plant has been investigated with four main manufacturing processes, and nine sample sites were selected, in order to provide a comprehensive understanding of the PM2.5 profile changes caused by the pollutants’ control facilities. The result shows pollutants’ control facilities have not only affected PM2.5 concentrations, but also the PM2.5 profiles. PM2.5 concentration was increased 1.89 times after Flue gas desulfurization (FGD) in the sintering process, the Ca content in PM2.5 increased to 21.1% caused by the desulfurizing agent; compared with electrostatic precipitator (ESP), bag filter (BF) is more effective for removal of fine particles, especially the condensable particles. The chemical compositions of Cl, K, Pb and Sb decreased after ESP in the sintering process, Fe decreased to 38.0% after ESP in the pelletizing process, and and Organic carbon (OC) increased in both processes. Different from ESP, Fe content increased obviously after BF in both blast furnace and converter processes, while S, K, , and OC are all decreased after BF. The coefficient of divergence (CD) values has been calculated at 0.42∼0.60, showing giant influences of pollutants’ control facilities on PM2.5 chemical profiles. Sixteen Polycyclic aromatic hydrocarbons (PAHs) in PM2.5 have been analysed, the result shows that de-dusting facilities (ESP and BF) are quite effective for PAHs removal, and the PAHs’ concentration significantly increased after FGD. More efforts are still needed to complete the accurate profile data with the rapid development of pollutants’ control technologies. GRAPHICAL ABSTRACT

Pollutants Emission and Control for Sintering Flue Gas

The sintering process is an important part of iron and steel production. In the process of sintering, large amounts of SOx, NOx, HF, dioxins, particulate matters and other gaseous pollutants are produced. In order to control the sintering flue gas pollutants, the emission standard for iron and steeling sintering flue gas in China was published in 2012 and the control application of source, process and end treatment were applied. Based on a systematic description of relevant purification technologies, this chapter reviews the current situation for control of sintering flue gas in China and the trend of technology development. Aplication cases are described, with the purpose of providing an important reference for the choice of sintering flue gas emission control technology for domestic and international steel corporations.