Study On The Generator Of Gaseous Chlorine Dioxide

Chlorine dioxide (ClO₂) is considered to be a good disinfectant which could take the place of liquefied chlorine. The chemical method of producing ClO₂ is the most common method. the process is simple and the technique is mature. The currently various chlorine dioxide generator added ClO₂ by utilizing the negative pressure of venturi, which discharges the formed ClO₂ aqueous solution to the treated water. This method not only has a low efficient, but also potential hazard.Having more efficiency and better results, chlorine dioxide released by gas, which can separate chlorine dioxide from the reaction residue, can not only solve the problem of the liquid having excessive acidity in the outlet, but also prevent the potential pollution of water body from the residual ClO₃^- or ClO₂^- for incomplete reaction.Released by gas, the chlorine dioxide generator was studied and designed in this paper. The reaction condition of obtaining chlorine dioxide from sodium chlorite was studied by experiments; meanwhile, a stripping experiment of the influence of air on the produced chlorine dioxide was carried out in order to research the feasibility of adding chlorine dioxide by gas. Finally, based on above experimental results, a chlorine dioxide generator was made, and was tested by experiments. The research results indicated that,(1) The reaction velocity was affected by the reaction temperature, the concentration of hydrochloric acid and the concentration of sodium chlorite. When the reaction temperature was below 40℃, the reaction velocity was accelerated by the increasing of temperature; however, the reaction velocity was not accelerated when the reaction temperature was above 40℃;(2) The reaction velocity was accelerated by the increasing of the concentration of hydrochloric acid and sodium chlorite. Meanwhile, there was a ratio relationship between the concentration of hydrochloric acid and the concentration of sodium chlorite, namely, the more the concentration ratio of hydrochloric acid to sodium chlorite was, the higher the transformation ratio of sodium chlorite was. To the concentration of sodium chlorite was below 5%, the reaction was completely finished within 6 min and the produced quantity of sodium chlorite could reach 90% of the theoretical value when the concentration of hydrochloric acid was above 15%.(3) The change of pressure did not have obvious influences on the reaction velocity and utilizing the negative pressure in the generator could efficiently control the liquid level and avoid the generator emptied or full filled.(4) When the temperature was below the boiling point of chlorine dioxide, chlorine dioxide could be stripped by air completely at very quick speed, even finished immediately so long as the stripping air flow was big enough. Thus, adding chlorine dioxide to the water by gas was feasible.(5) In this design, there were obvious deficiencies. It's mainly about the low efficiency of the stripping process which could only attain 62.5%. The reason was the stripping air flow resulted in the turbulent flow of the liquid in generator. Therefore, this design should be further improved.