Method of injecting ammonia into a flue for waste gases

摘要

The method is characterized by bringing a mixture of ammonia and air to a temperature substantially equal to the temperature of the waste flue gas in the flue at the exit of an air heater, and then injecting the mixture into the flue from a number of nozzles arranged in uniformly spaced relation in the flue while regulating the respective flow rates thereof. The non-uniform distribution of sulfuric acid components and non-uniform temperature distribution in the exit flue are compensated by individually controlling the respective flow rates of the gaseous mixture discharged from the nozzles to conform the distribution of the injected ammonia to the measured sulfuric acid component distribution while adjusting the molar ratio of the injected ammonia to the sulfuric acid components, at each point having a nozzle, in accordance with the measured temperature at the respective point, to a value such that the resulting reaction product will not melt and adhere to any component, such as a precipitator, connected to the exit flue downstream of the air feeder.