GB1139428A - Dirt trap for downflow reactors - Google Patents

Abstract

1,139,428. Dirt trap in chemical contacting apparatus. UNIVERSAL OIL PRODUCTS CO. 31 May, 1966, No. 24167/66. Headings B1F and B1T. In a chemical contacting vessel in which gaseous reactant flows downwards through catalyst bed 17, the incoming gas is directed downwards from inlet 4 into a debris trap, consisting of a vertical casing 8 having a grating 11 extending across below its upper edge 9. The grating 11 may rest on a peripheral ledge 12 and is coarse enough to pass entrained debris which collects at 21 in the bottom of the casing. In Fig. 1, some of the gas passes out of casing 8 over its edge 9 and some passes radially into the bed 17 through annular screen 14, but in Fig. 3 (not shown) screen 14 is omitted and all the gas reverses its direction in the upper part of the casing (38). The inlet 4 may be extended by a downcomer 5 so spaced from casing 8 that #=10 to 45 degrees. Downcomer 5 and casing 8 may taper and may be circular or polygonal in section. Casing 8 may be supported in sockets on struts 16 and may be lifted out for emptying when cover 3 is removed to replace the catalyst or may contain a removable mesh basket to catch the debris. Alternatively casing 8 may be attached to cover 3. The catalyst bed 17 is supported on ceramic balls 18 and screen 19 round outlet 20, and in Fig. 3 further balls (51) and surface-extending wire baskets (52) are provided on top of the bed. In addition to gas or vapour reactions, liquidi/gas reactions may be performed with gas entering inlet 4 and liquid entering peripherally around the vessel and avoiding casing 8. Typical reactions are naphtha reforming, hydrodesulphurisation of naphthas and middle distillates, hydrogenation and hydrodealkylation of aromatic stocks, isomerisation of normal paraffins, polymerisation of olefins and hydrocracking of heavy oils. The apparatus may be used for drying gases by desiccants or selective adsorption on molecular sieves.