US2248993A - Apparatus for controlling chemical reactions - Google Patents

Description

July 15, 1941` E. J. HouDRY 2,248,993

ArPARATUs FOR coNTRoLLme caEMicAL REACTIONS original Filed May's, 19:56

l'NyENToR v EuncNEdHnuom Patented July .15, y1941 APPARATUS-FOR CON TROLLNG CHEMlCAL REACTIONS Eugene J. Houdry, Ardmore, Pa., assigner to Hondry Process Corporation, W

ilmington, Del.,

a'col'poratlon of Delaware Original application May 8, 1936, Serial No. 78,542. y Divided and this application February 9, y1939.

Serlal No. 255,459

z claims. (cl. 234288) This invention relates apparatus for controlling chemical reactions and is a division of i the invention set forth in my copending applicaaspects of the invention wasilled on April 4.

- 1939. More particularly, it concerns temperature control of exothermic or endothermic reactions eileoted in the presence or with the aid of contact masses.

One object of the invention is to adjust the temperature of a gaseous stream by its passage in heat exchange relation with the reaction zone before being admitted to the contact mass. Another object is to effect heat exchange chiefly by radiation to or from the exterior of the reaction zone. Still another object is to maintain substantially constant temperature throughout the reaction zone. Still other objects will be ap- 'parent from the detailed description which follows.

While the invention is capable of rather general application, it is of particular value in controlling exothermic reactions, as for example, combustion reactions resulting from treatment of' regeneration fumes from catalytic converters after the manner set forth in my aforesaid copending and parentapplication to prepare the fumes for industrial use, as indicated, for example, in the copending application of myself and RQS. Vose, Serial No; 58,858, led January 13, 1936 (Patent No. 2,167,655 issued August l', 1939).

Concrete embodiments of the invention are disclosed inthe acompanying drawing, in which:

Fig. `1 is a vertical sectional view through a converting unit, the section being made substantially on the line I-l of Fig. 2;

Fig. 2 is a transverse sectional view substantially on the line 2-2 of Fig. l; and

Fig. 3 is a fragmentary or left half section Fig. l, showing a modification.

The apparatus provides a reaction zone for the desired contact or catalytic mass M. deilned by a tubular member or casing l having screwthreaded connection with a lower header 6 and welded to an upper header member 1. An outlet pipe 6 leads from the upper end of the reproducts, for example, neutral heated regeneration fumes which may be conducted away to suitable apparatus (not shown) for further treatment of any known or desired type. When the duid issuing from line l is inert burned combustion fumes, the treatment may lbe utilization of kinetic or heat energy in those fumes.

The gaseous material to be treated may enter the lower end of the reaction zone by an inlet pipe I0 extending through header 6. To insure the stream entering the zone at the proper temperature and also to give a measure of control of the reaction, thestream, prior to its admission to pipe I0, may be brought into extended heat exchange with 4the exterior of the reaction zone, but such heat exchange is conned, primarilyto radiation. By preference, the gaseous stream picks up heat progressively as it iscaused to traverse the length or depth of the elongate reaction zone. As indicated, feed conduit I I may be formed in a coil I Ia which encircles the reaction zone throughout its length from' outlet end 8 to inlet end l0.' The turns of coil Ila may A wire, cotter pin, or other member is inserted through the rods as at I2c to retain them. in place. To control the quantity of heat absorbed or radiated by coil IIa per unit of length of'the reaction chamber. and to provide for expansion of the stream, coils I la m'ay be changed in shape or increased in size as they approach 'inlet I0,

' this change or increase being eiected in stages,

by the use of sections of -plpe of increased diameter or increased surface presented 'to casing 5, or gradually and progressively as indicated vin Fig. l. The lower end of coil .Ila maybe joined to inletl conduit -Ill by a suitable connection I3. To prevent loss of heatfrom the unit,l an outer casing Il, which is preferably in sections to allow for the pipe connections II and I3. is secured to upper and lower headers l. and 6 in any suitable manner, as by seating the lower end in an annular recess 6a in lower'header '6, while the upper end is attached or clamped to header 1 as by a split ring I5. A layer of heat'v insulating material I6 may be applied to the entire exterior of the unit.

Progressive exchange of heat by radiation may be eiected between :the feed Vand the. reaction I o zone in other ways. If it isnot desired to change the size or shape of the conduit making up coil Ila, a conduit of uniform size and shape-may be utilized, but the pitch of the coil may be increased as lower header i4 is approached by making the coils-closer together. thereby increasing the ration chamber andrwhich enclose the catalytic r or other contact; mass, Vthe rate of heat exchange being controlled to provide accurate .temperature regulation of localized portions of the reaction zone to offset tendencies of the latter to absorb or radiate smaller quantities of heat as the temperature of the fluid traversing the coils approaches the temperature'of the reaction zone and its contents. Thus, provision is made for controlling increase of the temperature of the reactants at regulated rate by increased surface areas, by baiiles, or by other means so as to remove or supply substantially equal amounts of heat from or to all parts of the reaction zone.

One exothermic reaction to which the apparatus is Well adapted is in the combustion of car,- bon monoxide and/or oil .vapors which may be presen-t in' regeneration 'fumes issuing from a catalytic converter for thepurpose of increasing the energy content of the fumes, which may be thereafter recovered either as kinetic energy or as heat` energy or both, as indicated, for example, in the aforesaid copending application of myself and R. S. Vose. The combustion is best effected when a contact mass is employed, which may vary in character, depending upon the temperature at which the gaseous stream enters the combustion chamber. When it entersat high temperatures, as of the order of1000" F. or more, and contains suiiicient oxygen, the contact mass may be mere inert spreading material, but preferably of a highly porous nature, so as to retain oil vapors and the like until combustion is effected, such aspumice, kaolin, iirebrick, and other blends of silica and alumina. This material is preferably in the form of lumps, fragments, or moldedV pieces. When the gaseous stream enters the combustion zone at a temperature below 1000 F., as of the order of 900 F., the contact mass may comprise or cont-ain suitable catalytic material, such, for

example, as metallicoxides and compounds, in-

cluding thoseof copper, iron. cobalt, nickel and lead. The metals may be utilized directly, as in the form of shavings or' tuniings, or the metal or metallic compound may be in finely divided form on or incorporated in suitable. supports such as iiiert or active blends of silica and alumina of natural or artificial origin, preferably in the form oi.' lum ns, fragments or molded pieces.

Other exnthermic reactions which may be conducted within casing 5 with the aid of'suitable contactmass of known or desired type include synthesis of |ammonia from nitrogen and hydrogen, hydrogenation .of hydrocarbons and their derivatives, polymerization of hydrocarbons. and regeneration by burning of contact masses which have been vcontaminated with' carbonaceous, sulphur bearing o r other combustible deposits as the result of an endothermic-or exothermic onstream reaction.

When the 'apparatus of this invention is used forlcontrolling temperature of an endothermic reaction zone suitable fluid isadmitted to the heat exchange coil at somewhat higher ltemperature than desired in the reaction zone. Then the rates at which heat of reaction is supplied to localized portions of the zone are regulated by the increased radiating surfaces of the coil. A few typical endothermic'reactions for which 4this operation is used are the transformation of higher boiling hydrocarbons into lower boiling products, the dehydrogenation of ordinarily gaseous hydrocarbons, and transformation of low anti-knock naphthas and the like into high antiknock motor fuels.-

. Suitable or desired cooling or heating medium may be added to the reactants beforeand/or after -they traverse the radiant heat exchange coil or the like to assist in control of the radiant heat exchange between the coil and the reaction vessel and in regulation of the temperature of a reactant iiuid a-s it enters the reaction Such -addition to reactants entering the carbon monoxide and hydrocarbons, a cooling or heat absorbing medium such as air, or an extraneous fluid such as inert gases, atomized water or steam may be added by line 30 to increase the heat absorbing capacity of the heat exchange coils through decrease of the temperature and/or increase of the bulk of materialentering and traversing the same. Further adjustment of the temperature and/or composition of the reactants entering casing 5 may be effected by admitting a portion of the reactants at controlled temperature or a suitable diluent fluid to the stream iiowing through line I0, as by valved conduit 3|. When it i-s desired to reduce heat radiation from casing 5 lor to increase the rate of absorption of endothermic reaction heat therein a stream of reactants or other fluid heated to the desired temperature may be added by valved line '30. With certain reactions, as for example, when oxidizing a stream of gases containing burnable components and oxygen or when treating a stream of hydrocarbon starting material elevated temperatures may be obtained in line Il by effecting controlled combustion therein, as by adding a'suitable fuel or a controlled amount of air .to the combustion gases or hydrocarbons as the case may be. A

The apparatus of `this invention provides. among other importantadvantages, a reaction vessel in which all portions of the desired cata- 55 lytic or other contact mass are disposed at small and even minimum distance from a heating or cooling surface maintained at predetermined and closely regulated temperature. Thusl each portion of the mass has the quantum oi' reaction heat produced or absorbed by the reaction effected therein removed from or' supplied to an adjacent heat exchange surl'ace with the result that substantially constant and predetermined temperature may be maintained in all portions of v the reaction zone.

When it is desirable to utilize a reaction zone vhaving substantial width as compared. to its length, the Iheat removal from or absorption by the outer wall of the reaction chamber may be supplemented by one or more heat exchange conduits of suitable type embedded in the con tact mass. Such conduits may be capable of introducing4 reactants into the mass in addition to controlling temperature of localized portions of the same. Advantageous types of conduits for controlling the temperature of interior portions of the mass by means of reactants or other heat exchange fluid are disclosed in U. S. Paten-t 1,987,933, issued January 15, 1935 t0 J. W. Hai- A rison, in U. S. Patent 1,987,636, issued January 15, 1935, to T. B. Prlckett' and myself: and in U. S. Patent 2,042,469, issuedJune 2, 1936 to A. Joseph.

Although this 'invention has beendescribed in I connection with regulating the temperature of reactants for the desired endothermic or exothermic reaction. it is tol be" understood that it is by no -meansv limited to this preferred use. Suitable extraneous heat exchange iuid,for example, mercury, inert gases, fused salts and the like' may'be passed through the 'radiant heat exchange conduit or conduits. l'n such instances, connection I3 between the heat 'exchange unit and the reaction chamber will be omitted and conduits il and Il will be connected to suitable sources for simplyinsfheat exchange fluid and reactants, respectively, while the heat exchange fluid may discharge from -the radiant side and end walls, a conduit spaced from'and outside of theside walls and extending lengthwise of the 'reaction chamber, means for supplying heat exchange fluid for passage through said conduit, said conduit being so constructed and arranged as to provide progressively increasing heat exchange surfaces per unit of conduit length and per unit .of reaction chamber length, said f heat exchange surfaces facing saidside wall to transfer heat by free radiation between said side wall and 'said conduit in order to regulate the temperature of contact material in said reaction chamber.

2. vApparatus foreifecting chemical reactions comprising a catalytic reaction chamber having side and endwa11s, acoil outside said reaction chamber, means for supplying heat exchange fluid for passage through said coil, said coilbeing so constructed and arranged as to provide progressively increasing heat exchange surfaces per unit of conduit length and per imit of reaction chamber length, said heat exchange surfaces facing said reaction chamber side wall to transfer heat by free radiation between said side vwall and said coil in order to regulate the temperature of contact material in said reaction chamber.

- EUGENE J. normar.

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