Process system and process method for conversion of sulfur-containing flue gas to sulfuric acid

A process system for converting sulfur-containing flue gas into sulfuric acid, wherein, the process system comprises:

• a flue gas preheater for preheating the sulfur-containing flue gas to 15˜30° C. above its dew point, wherein the flue gas preheater has a glass tube as a heat exchange tube;
• a flue gas fan for boosting the pressure of the preheated acid process gas from the flue gas preheater, and transporting one part of which to a combustion furnace, and the other part of which to a process gas steam heater, wherein the combustion furnace and the process gas steam heater are used for heating the preheated acid process gas to catalytic oxidation temperature of SO2;
• the combustion furnace and the process gas steam heater are connected in parallel with a combined reactor, which is used for generating SO3 by catalytic oxidation of SO2 in the acid process gas;
• a sulfuric acid steam condenser for condensing SO3 generated by the combined reactor into sulfuric acid;
• the cold end of the sulfuric acid steam condenser is further connected with the flue gas preheater for providing hot air to the flue gas preheater.