Réacteur à contrôle de température par rétrodiffusion et récupération thermiques

955,417. Exothermic gas reactions. HOUILLERES DU BASSIN DU NORD ET DU PAS-DE-CALAIS. April 18, 1962 [April. 28, 1961], No. 15043/62. Headings B1F and B1X. Exothermic gas reactions are carried out adiabatically by supplying the reaction-mixture to the reaction zone at a temperature at which the reaction-rate is too slow for the reaction to be self-supporting, and maintaining the massvelocity sufficiently low (values from 0À0025- 0.02 gm./cm.2/second are specified) to ensure that, before entry into the reaction zone, the reaction-mixture is preheated by convection and radiation of heat from the reaction zone to a temperature at which the reaction is selfsupporting. In Fig. 1, the reaction zones R 1 and R 2 comprise two thin layers of granular material, which may be catalytic or not. The ratio of thickness to surface area of these layers is preferably from 1À5-15 cm./cm.2. The reactants, entering at E at the temperature T 0 , flow into the space between the two zones where, because of the relatively large crosssection, they remain sufficiently long to acquire, by thermal retrodiffusion, the temperature Ti at which the reaction becomes self-supporting. The reactants then pass through the zones R 1 and R 2 where the reaction takes place. Since some of the reaction-heat is transferred out of R 1 and R 2 in order to heat the reactants from T 0 to T 1 , the exit temperature T 2 of the products leaving at S is below the permissible maximum temperature, i.e. the temperature at which thermal decomposition of the products or the granular material occurs. Fig. 2 shows an apparatus wherein the reactants are distributed into four admission chambers C 1 , C 2 , Cs, C 4 , each bounded by a reaction zone R ; and there are four withdrawal chambers Si, S 2 , Ss, S 4 , leading to a common exit S. The oxidation of ammonia to nitric oxide on platinum gauze, and the dehydrogenation of methanol to formaldehyde on silver, are mentioned.