The removal of noxious and air polluting substances from exhaust gases has become a routine procedure in the glass industry. Nevertheless, process control is still based on empirical data and on the experience of the plant operators. In the past, the occasional and unexpected occurrence of aggressive fluxes in the electrostatic precipitators (e-filters) has bothered operators. This is unsatisfactory since the occurrence could not be attributed ina clear way to any unfavourable boundary conditions. This paper presents investigations of the thermodynamic and kinetic conditions in Na2O-H2O-SO2-CO2-N2-containing flue gases below 500 deg C. The investigations are particularly focused on the formation of liquid and solid sodium pyrosulphates and sodium bisulphates, as well as on their occurrence and avoidance inside the flue gas filters. It is shown that the formation is strongly dependent on the oxygen and water vapour partial pressure of the system. The measurements show that many different liquid mixed phases are formed within this system at low water vapour pressures. These phases can be avoided by raising the saturated vapour pressures above 200 mbar.
