Process and apparatus for the absorptive removal of pollutants from waste gases

Claim 1

A process for purging hot waste gas from pollutants including HCL, SO 2 , HF and flue dust comprising the steps: (a) passing the waste gas into an absorber and injecting a neutralizing agent consisting of sodium hydroxide or calcium hydroxide in the form of a dispersion or aqueous suspension or solution into said absorber; (b) injecting together with said neutralizing agent water in such an amount into said absorber that the water will completely evaporate while cooling said waste gas and said neutralizing agent will react with said pollutants to form dry salts therewith; (c) passing the gas from said absorber through a filter to separate said dry salts from the gas; (d) continuously measuring the concentration of said pollutants in said waste gas at a location upstream of the injection of water and neutralizing agent into said absorber and at a location upstream and downstream of the separation of said dry salts from said waste gas; (e) automatically and continuously adjusting the amount of neutralizing agent injected into said absorber depending on the measuring of the concentration at said three locations so as to always react at least a stoichiometric amount of neutralizing agent with said gas; (f) continuously measuring the temperature of the gas between said absorber and said filter; and (g) continuously and automatically adjusting the amount of injected water in dependence on the measured temperature of the gas.