Apparatus for converting hydrocarbons

Claim 1

In an apparatus of the radial type for effecting hydrocarbon conversions in the presence of a catalyst, comprising at least one substantially vertical elongated chamber whose cross-section by a horizontal plane is circular, the elongated chamber including at least one annular enclosure provided for receiving a moving bed of catalyst and arranged substantially vertically in the elongated chamber, each annular enclosure being delimited by a permeable external cylindrical wall and a permeable internal cylindrical wall; an internal collector adjacent to each annular enclosure, formed by the internal space of each elongated chamber and delimited by the internal cylindrical wall of each annular enclosure; an external distributor adjacent to each annular enclosure and formed by the space which is delimited by the wall of each elongated chamber and by the external cylindrical wall of each annular enclosure; an inlet connected to the external distributor adjacent to each annular enclosure for feeding the reactants; an outlet connected to the internal collector adjacent to each annular enclosure for discharging the reactants; means for introducing the catalyst at the top of each annular enclosure; and at least one catalyst collector for continuously discharging catalyst from the bottom of each annular enclosure; wherein the internal wall of each annular enclosure is provided in its upper portion with a screen to impede discharge of reactants at the top of the internal collector, the screen having a height amounting to about 80-300% of the total width of each annular enclosure and being arranged as an inverted truncated cone of upwardly increasing cross-section and having the same axis as the internal cylindrical wall of each annular enclosure, the surface area of the smaller of the two bases of the truncated cone being substantially the same as that of the cross-section of the internal cylindrical wall of each annular enclosure, and the angle which the axis of the inverted truncated cone makes with one of its generators being from 10 to 40 degrees; and wherein the upper portion of the external wall of each annular enclosure amounting to about 10-40% of the height of the annular enclosure, has the shape of a truncated cone whose cross-section increases downwardly, the greater of the two bases of the truncated cone being substantially equal to the cross-section of the external cylindrical wall of the annular enclosure, and the angle which the axis of the truncated cone makes with one of its generators being from 10 to 40 degrees; the improvement wherein each catalyst collector for continuously discharging the catalyst from the bottom of each annular enclosure is substantially cylindrical, the top of the catalyst collector being substantially flush with the bottom of the annular enclosure, and so arranged that the center of the circle that it cuts at the bottom of the annular enclosure is located at a distance less than (R-r)/3 from the internal wall of the annular enclosure, where R is the radius of the external wall of the annular enclosure and r is the radius of the internal wall of the annular enclosure.