GB868043A - Distributing gas to fluidized beds - Google Patents

Abstract

An apparatus for distributing fluidising gas to a vessel (32) comprises two concentric downwardly pointing cone members (22, 24), spaced apart and sealed at their peripheries, the upper member (24) being provided with <PICT:0868043/III/1> <PICT:0868043/III/2> nozzles (36) and the lower member (22) being imperforate and provided at the apex with an inlet (16) for fluidising gas. The numerals relate to the embodiment illustrated in Figs. 2 and 3 to be used for catalytically hydroforming naphthas which shows the apparatus in position in a generally cylindrical reactor 32 having an aperture in the bottom through which the inlet 16 for naphtha enters and to which the distributer is attached by means of annulus 92 which takes up any displacement due to expansion. The space between the lower cone and the bottom may be filled with insulation. The nozzles 36 are arranged to lie on concentric circles and a central nozzle 74 is provided. The nozzles are provided with orifice plates which supply an amount of gas corresponding the position of the nozzle: in an example the nozzle 74 had an orifice diameter of 0.934 inch and succeeding rows B, C, D had diameters of 0.915, 0.905 and 0.900 inches respectively. A second, valved, inlet 35 is provided for the introduction of hydrogen, mixing takes place in the central zone 73 and the mixed gases are conducted by baffles 68 to the nozzles. A well 54 is provided for withdrawal of the catalyst: a stripping gas may be introduced through one or more lines 62 and a fluidising gas through one or more line 64. In an alternative construction, pipe rings are embedded in the upper cone and have slots or holes in place of the nozzles, and in the lower surfaces of the pipes, between the cones, holes of suitable size are provided in order to maintain an equal gas flow through the upper holes. Radial ribs between the upper and lower cones may be provided. For hydroforming, catalysts such as oxides of molybdenum (5-15%), chromium, tungsten or vanadium, or platinum (0.1-5%) supported on alumina, silica-alumina, or zinc aluminate spinel may be used at 850-1000 DEG F. and 50-500 p.s.i.g. and regenerated at 1050-1200 DEG F. and the same pressure. The catalyst may have a particle size up to 150 microns. The catalyst to oil ratio may be 0.5-5.0 and the superficial gas velocity 0.6-1.2 ft./sec. A suitable feed comprises virgin or cracked naphtha of B.P. 125-450 DEG F. preheated to above 800 DEG F. together with 3000-10,000 cu. ft. of hydrogen preheated to 1050-1200 DEG F. per barrel of naphtha. The apparatus may also be used for catalytic cracking, hydrogenation and isomerisation, and for desulphurisation, adsorption and partial oxidation of hydrocarbons.