The Effect of Structure Modification of Sodium Compounds on the SO 2 and HCl Removal Efficiency from Fumes in the Conditions of Circulating Fluidised Bed

Abstract

The article presents the effects of mechanical and thermal modification on the surface area of sodium bicarbonate and its ability to remove SO2 and HCl from exhaust fumes. The mechanical modification consisted of grinding in an impact mill. The thermal modification consisted of heating in the temperature range from 373 K to 673 K. The applied modifications caused a change in the grain structure of sodium bicarbonate and parameters such as specific surface area and the pore size. The parameters were determined by low-pressure nitrogen adsorption (LPNA) and mercury porosimetry (MIP) methods. The largest development of the active surface, which was up to 6 m2 g–1 (LPNA), was achieved after crushing and heating in the temperature range of 423–523 K. The efficiency of a simultaneous purification of fumes from SO2 and HCl on a continuous-combustion installation with a circular fluidised bed CFB was determined. The samples were fed into the installation in three different molar ratios 2Na/S (0.5; 1.0; 2.1) in a gas jet of 573 K. It was shown that the removal of SO2 and HCl took place simultaneously and mainly on the grain surface. The average efficiency of SO2 purification was between 17 % and 89 %, and it depended on the comminution degree and the amount of the sorbent. The efficiency of HCl removal was between 54 and 78 %.

Keywords

• sodium bicarbonate
• purification of fumes
• removal of SO 2 and HCl