Effect of Operating Parameters and Reactor Structure on Moderate Temperature Dry Desulfurization

Abstract

A moderate temperature dry desulfurization process at 600-800 degrees C was studied in a pilot-scale circulating fluidized bed flue gas desulfurization (CFB-FGD) experimental facility. The desulfurization efficiency was investigated for various operating parameters, such as bed temperature, CO2 concentration, and solids concentration. In addition, structural improvements in key parts of the CFB-FGD system, i.e., the cyclone separator and the distributor, were made to improve the desulfurization efficiency and flow resistance. The experimental results show that the desulfurization efficiency increased rapidly with increasing temperature above 600 degrees C due to enhanced gas diffusion and the shift of the equilibrium for the carbonate reaction. The sorbent sulfated gradually after quick carbonation of the sorbent with a long particle residence time necessary to realize a high desulfurization ratio. A reduced solids concentration in the bed reduced the particle residence time and the desulfurization efficiency. A single-stage cyclone separator produced no improvement in the desulfurization efficiency compared with a two-stage cyclone separator. Compared with a wind cap distributor, a large hole distributor reduced the flow resistance which reduced the desulfurization efficiency due to the reduced bed pressure drop and worsened bed fluidization. The desulfurization efficiency can be improved by increasing the collection efficiency of fine particles to prolong their residence time and by improving the solids concentration distribution to increase the gas-solid contact surface area.

Simultaneous removal of SO2 and NO by low cost sorbent-catalysts prepared by lime, fly ash and industrial waste materials

“…In the optimum temperature window (700-800 o C) for dry-FGD process developed in our previous work [11], NO reduction performance is unknown. In this study, the potential of the sorbent-catalysts prepared from three low-cost materials including lime, fly ash, and the industrial waste material containing iron oxides, has been investigated for the simultaneous removal of SO 2 and NO at temperatures of 700-850 o C. NH 3 was chosen as the reducing agent for NO reduction.…”

“…The raw lime was ground and calcined in air at 450 o C for 3 h in order to convert Ca(OH) 2 to CaO. The sorbent-catalysts used in our experiments were prepared by specific procedures that were similar to the processes in our previous work [7,[9][10][11]. Two types of sorbent-catalysts were prepared, which are named as Sample-A and Sample-B hereinafter.…”

“…The negative effect of carbonate reaction (reaction (2)) is negligible in this temperature range. The pilot scale CFB-FGD experiment results [11] showed that SO 2 removal efficiency reached 85-95% at Ca/S molar ratio of 2 in the temperature range 700-770 o C. The best temperature window around 750 o C was suggested for dry-FGD in the medium temperature window. There were two advantages for the dry CFB-FGD operating in the higher medium temperature window (700-800 o C), compared to the lower medium temperature window (near 350 o C).…”

Effect of CaO on NH3 + NO + O2 reaction system in the absence and presence of high concentration CO2

“…• C. [7] It is obvious that, simultaneous removal of SO 2 and NO x in the same temperature window in a single reactor will be more attractive from both the economic and equipment simplicity points of view than alternative techniques which remove SO 2 and NO x separately.…”

Feasibility study on simultaneous removal of sulfur and trace selenium in the MTD-FGD reactor

“…Zhang et al [8] have reported the experimental results from a pilot-scale circulating fluidized bed flue gas desulfurization (CFB-FGD) facility at a temperature range of 600-800 °C. They found that the desulfurization efficiency increased rapidly with increasing temperature above 600 °C.…”