GB803458A - Emulsion alkylation of olefins with isoparaffins - Google Patents

Abstract

<PICT:0803458/IV (b)/1> <PICT:0803458/IV (b)/2> <PICT:0803458/IV (b)/3> In the emulsion alkylation of isoparaffins with olefins using a liquid acid catalyst, the acid and isoparaffin are premixed in the absence of olefin and passed through a series of stirred alkylation zones in a horizontal vessel, the flow of emulsion between successive zones being effected on alternate sides of the vessel to minimize the by-passing of emulsion round a zone, small portions of the olefin stream are introduced into each zone adjacent to the point of agitation and the temperature is controlled by vaporizing a portion of the hydrocarbons in the vessel. In a preferred embodiment, in which isobutane is alkylated with butylenes, two or more reactors represented as 10 and 10a (Fig. 1) are employed in series. Fresh isobutane from the product recovery enters through line 11 and recycle isobutane through line 12 and these are mixed with recycle acid from line 15 to which fresh acid may be added by line 16. Additional recycle isobutane enters by line 55. Olefine is added to each reactor, which is divided into several compartments, by lines 23. Effluent emulsion passes to the settler from which recycle acid is removed by line 31, spent acid by line 30 and hydrocarbons containing the desired product by line 29. Cooling is provided in each reactor by auto-refrigeration, liquid being allowed to vaporize to cool the emulsion. These vapours are removed from reactor 10 by line 34, compressed, cooled and passed to receiver 39. The liquid collecting there is divided into two streams, one is passed through line 41, heated and enters the depropanizer. Depropanized liquid from line 50 is cooled and passed with the other liquid stream from the receiver to economizer 47 which is at a lower temperature than the receiver and in which the liquid is flashed and from which vapours are recycled to the compressor and liquid, mostly isobutane is recycled to the mixer 14. In a modification using a multistage compressor vapours from the economizer are recycled to a late stage of the compressor while liquid passes to a second flash drum from which the vapours are recycled to an early stage of the compressor and the liquid is recycled to the process. Vapours from the second and any further reactors removed by line 34a are similarly treated except that the depropanizing treatment is omitted, and recycle liquid re-enters the system by line 55a. A suitable reactor is illustrated in Fig. 4. Liquid entering by inlet 61 falls on to the surface 64 which acts as a flash pan. Stirrers are provided in each section which sections are separated by baffles 62a, 62b which are stepped on alternating sides to provide a circuitous path for the liquid. Olefines are introduced by the multi-point circular injectors 68 which direct the olefine upwardly and outwardly into the turbulent region created by the stirrers. The olefines should be cooled sufficiently prior to introduction to prevent vaporization on introduction. Liquid finally leaves by outlet 78. The mixer 14 is preferably of the form illustrated in Fig. 3. Acid esters by line 15 and into this stream is injected recycle isobutane from the refrigeration system by line 55 and recycle isobutane from the product recovery and fresh isobutane by line 13.