USRE22415E - Method for cooling fluid catalysts - Google Patents

Description

Y Jan. 4, 1944. Fr. T. BARR Y R4!- 22,415 f METHOD FOR COOLING FLUID cA'rALYs'rs l original Filed March 1. 1941 Zone particularly aggravated .and

Patented Jan. 4, 1944 METHOD FR COOLING-FLUID CATALYSTS Frank T. Barr, Summit, N. J., assignor, by mesne assignments, to Standard Catalytic Company, a corporation of Delaware original No, 2,309,034, am .nanny 19, 1943, Serial No. 381,229, March l, 1941. Application for reissue october 1, 194s, semi No. 505,413

s claims. (c1. lzoo- 44915) The present invention is concerned with the removal of heat from an exothermic reaction,

particularly when employing a suspended :iluld catalyst. In accordance with the present process. exothermic heat o! reaction is'absorbed as sensible heat of the fluid catalyst which is removed from the reaction zone 'and cooled by the regeneration of steam and, if desired, the superv heating of the same ln acooling zone. The invention is particularly adapted to the manufacture of products by a reaction involving hydrogen and oxides of carbon. In accordance with the present process, the temperature vwithin the reaction zone is positively controlled by regulating l the' temperature of the catalyst in a manner as hereinafter described.

It is known in the art toconduct .various exothermic chemical reactions and to remove the heat or reaction by suitable means. These means usually comprise liquid-cooling mediums which are circulatedv within or without the reaction' zone. Circulation of the cooling means within the reaction zone, however, is frequently impossible or inadvisable owing to the eiect of the cooling medium on the course and extentofl the reaction, difliculty in separating the cooling me'- dium from reaction products or catalytic material. reduction in lreaction space caused by the :presence oi the medium. etc. On the other hand, circulation of cooling means without the reaction zone ls-not entirely satisfactory for ce1'- tain `operations owing -to the fact that the temperature within the reaction zone is relatively dimcult to control within a narrow range. particularly when a catalytic material isl employed,

-and that local overheating occurs, along the surface of the catalytic material across the path ol the owlng gases. These disadvantages are emphasized in chemical 'reactions involving thehydrogenation of carbon oxides for the production of hydrocarbons having more than one carbon atom in the molecule,l since it is essential that the temperature in these reactions be controlled so that no substantial temperature variation during the course of the reaction results.

It has, therefore, been proposed that a :duid suspended catalyst be employed in various types or exothermic reactions and that exothermic heat of reaction be removed by absorbing the same as sensible heat of the catalyst, withdrawing theA catalyst from the reaction zoneI removing the exothermic heat of reaction, and recycling the cooled catalyst to the reaction zone.

operation may be more efficiently and economically conducted. My process overcomes inherent difiiculties 'present in the removal of the heat of reactionv from the catalyst and produces additional benefits. In accordance with my process, the catalyst is withdrawn from the reaction zone and passed into a cooling zone wherein the same is cooled by vaporization of water, producing Y relatively largequantities of steam.

The process of my'invention may be readily understood by reference to the drawing illustrating an embodiment of the same. The figure illustrates an operation employing a powdered suspended catalyst utilized in a reaction for the production of hydrocarbon constituents containlng more than one carbonatom in the molecule by the hydrogenation of oxidesof carbon. The feed gases comprising oxides of carbon and hydrogen are introduced into reaction zone I by means of feed line 2. These gases flow upwardly through reaction zone I and countercurrently i contact a downflowing powdered suspended catalyst which is introduced into zone I by means of line 3. It is to be understood that zone I comprises suitable means to control the temperature of reaction within the desired range, at least part of which involves absorption of reaction heat as sensible heat of the catalyst. Reaction products comprising vaporized hydrocarbonconstitsirable.

The powdered catalyst flows downwardly in zone I and absorbs exothermic heat as sensible heat of the catalyst,.and is withdrawn from zone I by means' of line `5. 'I'hese gases are passed along cooling zon-e 6 wherein the sensible heat of the catalyst is removed by contacting the same with water which is introduced into zone 6 by means of line 'I. The amount of Water introduced is adjusted so that complete vaporization of the same is secured. In general,v it is preferable to introduce the water-,at a plurality of stages by means of lines I5 and I6.

The cooled catalyst together with steam passes upwardly through zone 6 and passes into separation zone 9 wherein a separation is made between the steam, which is withdrawn by means of line III and the cooled catalyst which is Withdrawn by means of line 3 and recycled to the reaction zone.

I have now discovered a process by which this Il Fresh catalyst may be introduced by means of perature.

une l2 while spera @mwst is withdrawn by means of line I3. The temperature of the catalyst may be further controlled if necessary by passing the same through suitable heating or cooling means.

The process of the, present invention may be widely varied and is not limited to the construction of the ligure. It is to be understood that the respective zones may comprise any suitable number, arrangement. and position of units.-

The invention isl particularly beneficial in that the catalyst is suspended in the steam and passed to the top of the reaction `,chamber from where it may readily be recycled. lThe invention may be readily adapted for the removal of heat from any chemical reaction in which heat is evolved. y It is, however, particularly suitable for use when employing a suspended powdered catalyst, especially in the reactions involving the hydrogenation of oxides of carbon conducted under conditions to produce hydrocarbon products containing more than one carbon atom in the molecule. i

'Ihese reactions are generally conducted at a temperature in the range from about 370 to 410 i F. It is essential in order to secure a satisfactory yield of the desired quality product that the temperature of the reaction does not vary substantially from the predetermined operating tem- In general, to secure satisfactory results it is essential that the temperature of the reaction in Vprocesses of this character must not vary over a temperature range in excess of about 10 F. and preferably should not vary over a temperature range in excess of 5 F. The catalyst employed in this process may be any suitable catalyst selected from the class of substances which 'are known as suitable for aiding the hydrogenation of oxides of carbon. Satisfactory catalysts are, for example, cerium, chromium, cobalt, manganese, osmium, palladium, titanium, zinc, iron, and oxides or othercompounds of these metals. Mixturesof these catalysts may be employed or the same impregnated with suitable agents adapted to increase their efllciency or strength. In general, in carrying out the present process I have found `it preferable `to employ a iinely divided or powdered catalyst of about 200 to 400 mesh. Although the operation has been described employing a countercurrent flow be` tween the catalyst and thel gases in the reaction zone, it is to be understood that concurrent flow, either upflow or downow, may be employed. When employing a powdered catalyst in an operation of this character, the same may be uniformly distributed as it freely falls throughJ the reaction zone and intimate contact is obtained between the concurrently owing gases and powdered catalyst. A modication of my invention is to regulate the ow of synthesis gases and catalysts in a manner whereby the velocity of the catalyst passing through the reaction zone exl ceeds the velocity of the flowing synthesis gases.

When concurrent flow is used an additional zone to separate the catalyst from reaction products may be provided. Provision of this auxiliary separating zone may also be desirable with countercurrent flow in the reaction, as, for instance, on

line l of the accompanying drawing, from which the separated catalyst would join line for charging to the cooling zone.

The extent to which the catalystis cooled may be readily controlled by the quantity'of water introduced into the cooling zone. In general,

' my process is best adapted to operations in which the catalyst is cooled to a temperature not substantially below about 300 F. If the catalyst is v much below this temperature, the water does 'not weight hydrocarbon products.

lllash readily t0 steam at a vuseful pressure level.

It is essential, particularly when employing a powdered catalyst that the quantity of water added to the cooling zone b of an amount that will readilyvaporize and that the reaction zone be substantially completely free of liquid water. The temperature of the Water added may vary widely, but in general it is preferred that the added water be at its boiling point with respect to the pressure employed. A particularly desirable operation as outlined above, is to introduce an aqueous mixture comprising about 5% to 10% of steam into the reaction zone under conditions so that the liquid will be iiashed immediately. Much the same effect is obtained in part by introducing the water at a plurality of stages along the path of the flowing catalyst in the cooling zone.

What I claim as new and wish to protect by Letters Patent is:

1. A method of removingl heat from reaction chambers in which exothermic reactions are carried out and wherein the desired reaction temperature is materially above the boiling poi-nt of Water under obtaining pressure conditions which comprises continuously introducing into said reaction chamber a stream of finely divided, heatabsorptive, solid material, said solid material being in` direct contact with the reactants within said reaction chamber, the inlet temperature of said lnely divided solids so introduced being below the desired reaction temperature whereby heat liberated during said reaction may be absorbedffby said solid material, continuously withdrawing a stream of said finely divided contact material from said reaction chamber while at said reaction temperature, injecting Water into said stream of solid material so withdrawn, limiting the amount of waterso introduced to completely vaporize the water so injected and to cool said solid material, separating the steam formed by the vaporization of the water from the solid material, continuously returning the cooled solid material separated from said steam to the reaction chamber, and regulating the return of i'low of said solid material through the reaction chamber to maintain the desired temperature therein.

2. The method deiined by claim 1 wherein the solid, heat-absorptive material forms a catalyst for said exothermic reaction.

3. The method dened by claim 1 wherein car-y bon monoxide and hydrogen are reacted within said reaction chamber to form higher molecular T. BARR.

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