Reactor for preparing hydrogen cyanide by the andrussow process, equipment comprising said reactor and process using such an equipment

Reactor for preparing hydrogen cyanide by the Andrussow process, with at least one gas inlet for reactant gases mixture, a catalyst, at least one support for the catalyst and at least one outlet for the reaction products, wherein said reactor (201) comprises a cone frustum shaped casing (210) and comprises inside said casing, a gas distributor (202) located between a gas inlet (I) and a catalyst (203), said distributor comprising at least one cone frustum element (Dn) having an upper base directed towards the gas inlet and wherein the gas distributor comprises a plurality of coaxial cone frustum elements (D1, . . . , Dn) being arranged around each other with a central cone frustum element having a height h1, an outer cone frustum element having an height hn, and intermediate elements having respectively height h2, . . . , h(n−1), where h1 is smaller than h2, and respectively h(n−1) is smaller than hn.