Sulphuric acid or oleum prodn. by contact process - with recirculation of gas from first absorber to end of first contact stage, increasing efficiency

摘要

The process is carried out with gases contg. 10 vol.% SO2 in 2 contact stages, the first being followed by cooling absorption of the SO3 formed and reheating. The novelty is that 10-40 vol.% of the gas from the first absorption stage is mixed with the gas from the penultimate layer of the first contact stage and the combined gases are passed to the last layer of this stage. Pref. the gas from the penultimate layer is cooled to 480-500 degrees C in a heat exchanger and then mixed with 10-15 vol.% of the gas from the first absorption stage. The efficiency of the last layer of the first stage is increased, making operation more economical. The heat exchanger after the second contact layer of the first stage and the circulation blower can be smaller than usual.