GB1052215A - - Google Patents

Abstract

1,052,215. Sulphur trioxide. METALLGESELLSCHAFT A.G. Aug. 9, 1963 [Aug. 16, 1962], No. 31615/63. Heading C1A [Also in Division B1] In the catalytic conversion of an SO 2 -containing gas to SO 3 in a multi-stage converter, the converter contains a plurality of catalyst layers and the partly converted gases from the first converter stage are cooled by withdrawing them, mixing them with cold SO 2 -containing gas or air before they enter heat exchangers in which fresh SO 2 -containing gas is heated to reaction temperature, and then the gases are passed to the succeeding catalyst layers. As shown in Fig. 1, 90% by volume of an SO 2 - containing gas introduced through pipe 1 enters heat exchanger, 6, where it is pre-heated to 280‹ to 290‹ C. by means of converted gas at about 420‹ C. which enters 6 from pipe 7. This pre-heated gas passes through heat exchangers 10 and 12 by means of pipes 9 and 11, respectively, and then passes into converter 15 at a temperature of 430‹ to 450‹ C. by pipe 13. The gas, after passing through the first catalyst layer 14, is withdrawn at 16. It is then mixed with cold SO 2 -containing gas at 17 and passes through exchanger 12 in countercurrent to fresh SO 2 -containing gas and returned by tube 21. The gas then passes through catalyst layer 22, and is again withdrawn at 23, passed through exchanger 10 and returned at 24. The gas then passes through another catalyst layer 25 then through cooler 27, and finally through the catalyst layer 30 the conversion being thus completed. The converted gas then passes through pipe 7, exchanger 6 and is withdrawn through pipe 8. In Fig. 2 (not shown) air is mixed with the partly converted gas, and the air thus preheated may be used for burning sulphur to give SO 2 - containing gases which are cooled before introduction into the first catalyst layer.