US2548759A - Fluid mixer-reactor - Google Patents

Description

pm w, E951 J. G. ALLEN FLUID MIXER-REACTOR Original Filed July 6,v 191155` QUENCH W F E L w D 8 4 N Y lnn/ F EW; L O IJ DR.

POROUS REFRACTORY HYDROCARBONS HYDROCARBONS AIR FIG-3 lNvENToR J.G. ALLEN BY u s ATTORNEY Patented pr. 10, 1951 UNITED STATES vAFENT OFFICE FLUID MIXER.-REAC'IORv John Gordon Allen, Bartlesville, Okla., assigner to Phillips Petroleum Company, a corporation of Delaware Original application July 6 1943, Seriall No. 493,671. Divided and this application `October 30, 1945, Serial No. 625,916

Claims- 1 This invention relates to the. conversion of hydrocarbons and to the production of dioleiin hydrocarbons. A preferred. modification relates to the decomposition of light, normally liquid. hydrocarbons under conditions chosen for ope timum production of dioleflns aided by the action of free oxygen on said hydrocarbons. Specific aspects include an apparatus and method of operating which favor a partial oxidation ot hydrocarbon reactantsin such manner that a very rapid temperature rise to the desired range` isV attained. This application is a division of copending application. Serial No. 493,671,v led July 6, 1943, issued October 30, 1945, as Patent No. 2,387,731.

The production of 10W-boiling diolefinic hydro.- carbons such as butadiene, isoprene, piperylene, etc., has recently become of vital importance for` the manufacture of synthetic rubber-like ma.- terials. In perhaps the most important type of synthetic rubber the dioleiinic constituent comprises about 75 per cent of the raw material..

While relatively highyields ofdiolens may bel obtained through carefully controlled selective.

catalytic processes, for example",4 the catalytic dehydrogenationof. normalbutenes to butadiene, such processes suffer somewhat. from the. disad vantage of requiringr a careful isolation of. feed. stocks which may be needed for other purposes.y

Furthermora a; high initial capital. expenditure is` required.

In order to obtain asubstantial production of' diolens in airelatively short period of time-and, to utilize lcssva-luablc .stocks in so. doing. atten:v

temperature range is attained very rapidly, and

unless the reaction products are in turny rapidly cooled, the hydrocarbons will undergo extensive reactions other than those. desired, with conse@ quent reduction in yield'. I have found that an effective way tol attain the desired temperature level almost instantaneously is to admix. an oxy.v

ecn-containing. sas.. with c r. without incr-t diluents, with a partially preheated charge stock in a particular manner chosento promote a par-1 tial oxidation ofthe hydrocarbons, as more fully hereinafter disclosed and. discussed.

An object of this; invention is to. provide apev paratus useful in effecting chemical reactions.

Another object of this invention is to provfjdcr such apparatus; particularly adapted for high temperatureoperation.

A further object is to' effect a rapid and inti-e,

mate: intermixture` of two gases.

Yet another object isy to provide apparatus 4 suited to the catalytic' oxidation of organic: ma-` terials.

Furtherl objects and advantages of the invention will become apparent to oneA skilled in the art from the accompanying disclosure andA dis. cussion;

In order to provide a better understanding of: the invention and to illustrate the preferred features thereof the accompanying drawing isproa. vided which shows in somewhat diagrammatic form one arrangement of apparatus.. and; whichl also showsl in some: detail preferred. structures which are particular features of: the present ina.

vention. Figure l` isv a simple flowdiagram inwhich one-form of reactor is shown in detail, as.` used for the production of diolensy whileV Eig.Y ures 2 and 3v illustrate'. other preferred forms of the reactor.

As particularly adapted for the oxidation of. hydrocarbons, the reactor of thepresent inverniv tion is provided with. a porous. refractory body:

coated with an oxidation catalyst. This? body is positionedV with respect,v to theV rest of' the ap paratus so that hydrocarbon: feed introduced 'ad-1 jacenty thereto passes; immediately away from theI porous body. Means. are. provided: for passingranoxidizing gas through the catalystfcoated porous" refractory into` admixture with the hydrocarbons.

The body itself is shaped and positioned in, a novel manner ensuring. intimate mixture of the: oxidizing gas with the hydrocarbons. In order to bring out the various; featuresof theapparatus there. will be described now, thelutilization there-v of in producingloW-boiling diolens byoxidation. It will bc appreciated that numerous other chemical reactions' may likewisebe. effected in;`

the apparatusl of this invention with orv Without; various modifications which will beobvious tof one skilled inthe art, in View of; the speciiic dis;

closure of Various preferred structures. givenherein.

In the preferred manner of carrying out thez production of 10W-bcling` diolens in` accordance:

with the principles of this invention, a nonaromatic hydrocarbon distillate such as cracked or straight-run naphtha is diluted with steam or other non-oxidizable diluent, is brought to a temperature of about 1100 F. or slightly higher, and then passed rapidly past the incandescent surface of a porous refractory material through which air in carefully controlled proportions is being introduced. The resulting gaseous admixture is maintained at the desired reaction temperature for the short time required and quenched immediately thereafter to stop the reaction. The porous refractory material referred to preferably is coated with a catalyst, such as a metal oxide, which catalyzes the oxidation of hydrocarbons. The introduction of oxygen through said refractory member in the manner described provides a very rapid and intimate interrnixture of hydrocarbon charge with oxygen and the desired oxidation is at least partially effected at the refractory surface. The result is the maintenance of a highly heated surface past which the hydrocarbon stream flows. It will be seen that the temperature of the hydrocarbon stream is raised almost instantaneously several hundred degrees from the preheat temperature tothe reaction temperature. Due to the intimate mixture of oxygen with hydrocarbons thus effected the oxidative reaction continues in the portion of the reaction zone immediately following the incandescent refractory and serves to maintain the temperature of the mixture in the desiredV range in spite of the highly endothermic cracking reaction which is being affected. In other words, the hydrocarbons are rst rapidly raised 'to reaction temperature and second maintainedv at reaction'temperature by the introduction of limited amounts of oxygen in the particular manner described. i

It `has been found that the best results are obtained when a diluent, such as steam, nitrogen, an oxide of carbon, etc., is mixed with the selected hydrocarbon charge stock prior to its passage through the preheat zone. This serves to minimize any reaction in said zone and permits a relativelyhigher temperature to be maintained therein without the occurrence of an appreciable amount of coking.v The'diluent serves during thereaction to help control temperatures and partial pressure of reactants and enables the attainment of a high conversion to diolei'lns. Preferably the mol ratio of "diluent to oil vapor is in the range of from about 3:1 to about 6:1. While the total pressure of the reaction mixture should generally be above atmospheric, the use of a great'super-atmospheric pressure will appreciably reduce the yield of low-boiling diolei'lns. In most cases a preferred operation will involve the use' of only a suflicient super-atmospheric pressure to overcome lthe pressure drop through the apparatusand provide a few pounds of superatmospheric pressure at the exit of the reaction zone.

H'Any suitable source of oxygen may be utilized, but air is ordinarily 'found to be most convenient. The inert constituents of the air have an advantageous diluting effect in the reaction zone. The amount of free oxygen utilized must be carefully controlled to obtain a suiciently rapid and great temperature rise on the one hand, While avoiding' undue destruction of hydrocarbons on the other hand. With the type of charging stocks described herein and under the given temperature and time conditions, it is necessary that free oxygen be used in an amount substantially between about 0.15 and 0.25 pound per pound of hydrocarbon material to attain the most satisfactory results. In the case of air, this requires an air-hydrocarbon weight ratio in the range of about 0.7 to 1.2.

An important feature of the present invention is the catalyst-covered porous refractory body, particularly with respect to its composition and to its position relative to the steam-hydrocarbon stream. The body proper should have a relatively large surface area, and may comprise any suitable refractory material which is stable at the high temperatures encountered. The porosity is such that the required flow of air or other oxygencontaining gas may be maintained without requiring too high a pressure drop across the body, while at the same time providing for a very intimate admixture of oxygen with hydrocarbon. The catalyst coating may comprise one or more high-melting oxides of metals of groups IIIB, IVA, VA, VIA, or VIIA of the periodic system as grouped by Mellor, Modern Inorganic Chemistry, Longmans, Green & Co. (1939), page 118. Such coating may be applied in any suitableY manner,

exemplary of which is`the impregnation of the body with, or spraying upon the surface of the` body, a solution of a metal salt, followed by calcining to convert the salt to the oxide. Preferred combustion catalysts are ThOz, ZrOz, and W03.

The body thus coated with the combustion catalyst is placed in the apparatus in such way with respect to the ow of hydrocarbon reactants that the latter contact the same for only a very short period of time, and then pass away to the re- As stated above,

mainder of the reaction Zone. this provides sufficient combustion to raise the temperature to the desired range, while maintenance of temperature during the ensuing endothermic cracking is provided by continued action of the admixed oxygen with the hydrocar-V bons in the balance of the reaction Zone. The shape of the porous body will be somewhat dependent on-the design of the reactor and its location therein. One preferred shape is that of a ysures a rapid temperature increase only to thel desired level whereas if the hydrocarbon were allowed to remain in close contact with the incandescent Ybody for a more substantial portion of the total reaction time a decomposition entirely too extensive for satisfactory diolen production would be encountered. The reaction time allowed between introduction of preheated charge to admixture with air and the subsequent shock cooling is preferably between about 0.1 and about 0.2 second.` Usually-an empty reaction chamber is provided, the size of which is correlated with flow rates togive the proper reaction time. However, the reaction zone may be partially lled with metal or refractory packing to provide a more extended Surface which seems to favor the continuance of the already initiated combustion. Immediately upon completion ofv the conversion the total reaction mixture is quenched, preferably to about 400 F. or lower.

In the choice of chargingstock for dioleiina` production in .the 'instant process, a certain amount of latitude is permissible, which adds to the value of the process, particularly for use in Aa petroleum ren'ery where changing operations affect the availability offany particular type of stock. -Asstated before, the ordinarily less 'valuable stocks are generally utilizable, thus enhancing the economic status `of the process. Thematerial used should, however, generally '-f'all within the following classification: it Should be non- Varomatic, that is, have a content lof aromatic hydrocarbons less than about .ten Iper cent, Yand preferably less than live per centi; .it should be .normally liquid, and preferably higher boiling than the diolefin to be produced; it should be relatively light, that is, substantially .boiling belowabout 600 F.-preferably the material com- .prises vhydrocarbons having at least four and not more than twelve carbon 'atoms 'per molecule. :As examples of such materials may be mentioned straight-run .naphthas of narrow `or wide boiling range, catalytically or .non-catalytically cracked naphthas of narrow or -wide boiling range, or mixtures of such naphthas.

In Figure l, the naphtha or other oil to be cracked is introduced via line IIJ, joined by recycled material from line l2 if desired, and mixed with vsteam from line I4 in the proper ratio disclosed hereinabove. The resulting mixture is passed through coil I6 in Apreheater furnace kI8 fr.

where the temperature is rapidly raised to about 1100-1200 F. The thus preheated `material then flows Via line into reactor 22, rst entering the vmixing T 24. Disposed within this T with its axis at a right angle to the 'entering stream is a porous refractory fcone 26 coated with Aa combustion catalyst. The cone inserted about halfway across the bull-head opening of the T so oil Yvapors flow across the cone in contact with the surface where air enters, yet leaving enough clearance so that there is no great restriction to oil flow. Air is admitted tothe baseof cone 26 via line 28 in a quantity based on the quantity of charge oil as described herein. The stream of preheated oil and steam flows past the cone 2E `and immediately is turned to llow 'parallel With the axis thereof away from the cone on into the next portion of reactor 22. The air owing through cone 26 `into reactor 22 mixes with the oil and a considerable proportion of the total combustion voccurs in T 24 onor adjacent 'the `catalyst-coated surface of cone 26, which is Vheated to incandescence. The oxygen and the hot products of combustion rapidly Amix with the hydrocarbon and immediately raise the temperature of the total lstream tothe desired cracking lrange. It will be 'seen that the construction of T 24 ensures ease of nstallation'and replacement, which is of particular advantage when'such high temperatures are encountered.

After-cracking is completed in reactor 22, the total eiiluents leaving via line 30 are immediately `quenched by cool liquid, such as 'water or oil, entering via line 32. The yquenched material passes into a separation system indicated diagrammatically by unit E4. Some incompletely converted material may be vrecycled via line l2, but it should irst -be Aseparated A,from aromatic hydrocarbons by suitable means. Low-boiling "material is removed via line Stand high-boiling material vvia -line 49, while a fraction containing desired di'olefins 'is passed via line 42 to diolen recovery equipment 44. This may include solvent extraction, extractive distillation, azeotropic distillation, formation and decomposition of Cil .rium salt to the oxide.

cent based on the charge.

,from the-process effluents.

'melena-metal salt :complexes .such as diciefirl* cupr'ous chloride complex, or 'any other suitable means known .to the art. Nonv-diolen'ic material is removed through line 46, while the desired diolens, such as butadiene, are recovered through line 48. It will be understood that the C5 and/0r C6 andl even Vheavier diolens vmay .be similarly recovered.

Figure 2 illustrates another imanner'of fashion'- ing the portion of 'reactor 22 containing the iporous refractory. An L 50takesthepla'c'e of T 24. A porous refractory YVcatalyst-coated .plate 52 iis placed .in the .L `'as shown so that air, 'entering through line .'2-8., is introduced into the 'flowing'oil stream without too much restriction to the 'oil lio'w. The oil-steam mixture passes `adjacent plate 52 and then immediately away fro'm .itinto thereactionzoneproper.

Figure 3 .illustrates another preferred structur of this invention, which employs a Venturishaped porous lrefractory :catalyst-'coated tube 54 in the oil-steam flow line, :allowing .for air Ainjection .from all sides of the .flowing oil stream. .An annular space 56 rabout Venturi-tube .54 is .provided by cylinder 58, into which air from :line y28 is introduced. The Venturi decreases any '.possibility of the center portion of the flowing oil stream not receiving contact with the air, and provides an added mixing effect due to the pressure drop across the Venturi. The hot gases pass rapidly `from .glowing tube 54 on "into lthe remaining portion of reactor 22.

The .following example is given asa means of illustrating the results `which are obtainable .in producing diolens when using the apparatus of this invention. It will be understood, of course, that the exact data are not `to be construed as unduly limiting .since the vdifferent factors may be varied within the .preferred ranges as 'heretofore set out.

'A .straight-run naphtha having a boiling .range of 20G-400 F. is admixed with 5 mois of `steam per mol of oil and preheated to 1100 F. This preheated material is then passed into a reactor similar to that shown in Figure 1 in contact `with a porous alundum body coated with thorium oxide by impregnation with a solution of thorium nitrate Afollowed by burning to convert the tho- Air, preheated to 500 F., :is introducedthrough the porous body at the rate of 1.1 pound per pound of oil charged. 'Based `on the volume of material charged, a reaction time of 0.2 second is realized, and the temperature at -the outlet of the reactor is 1600 F. The reactor eilluent is immediately quenched with water to about 350 F. and passed to separating equipment comprising conventional absorbers and fractionators. The C4 cutis recovered and the butadiene, which comprises ll5 to 50 per cent of the cut, is separated therefrom by extractive distillation with furfural. The weight ratio of butadiene to dry gas (C3 and lighter) is 0.11,`and

the over-all yield of butadiene is 4.5 weight 'per Substantial, though lesser, amounts of C5 diolens are also recovered While partial oxidation of hydrocarbons for the production of low-boiling diolens has been vemphasized in the `foregoing discussion, this is lmerely exemplary, for obviously various other .processes Yknown to the art for the oxidation'of vorganic materials may likewise be effected in the novel apparatus described herein. Merely by way of illustration may be mentioned the production of methanol, formaldehyde, and other exif-compounds by the controlled oxidation of methane or natural gas; the production of olefin oxides as by the oxidation of ethylene; the partial oxidation of highly unsaturated oils to produce drying oils or the like useful in the manufacture of protective coatings. The apparatus herein disclosed is likewise very advantageous in the production of phthalic anhydride by oxidation of naphthalene or ortho xylene.

Oxygen-containing fluids which may be used include those containing free oxygen, such as air, or ozone, or those containing oxygen combined with other elements, e. g. nitrous oxide or nitrogen dioxide. Other fluids, such as chlorine, may be employed to effect oxidation reactions.

The apparatus of the present invention is not necessarily limited in uses to those involving oxidation, for obviously other organic or inorganic chemical reactions such as chlorination, nitration, sulfonation, neutralization of acids with bases, and the like, may be affected. Such reactions may be carried out either with or without catalysts as desired, and though either gas or liquid or both may be utilized, the advantageous features of the invention are most completely realized when both reactants are in the gas phase.

The invention may also be applied to the problems involving physical admixture of two fluids even in the absence of chemical reaction. The porous Venturi illustrated in Figure 3 is particularly to be noted in this connection as it provides complete and very rapid mixing action. This and the other forms permit streamline flow before and/or after the porous section, with turbulent flow at the point of mixing.

While preferred aspects of this invention have been described, the scope is not to be limited other than as defined in the appended claims.

I claim:

1. Apparatus suitable for effecting reaction between fluids which comprises a cylindrical conduit an elongated portion of which comprises a reaction chamber, a porous refractory body of relatively large surface area within said conduit immediately upstream of said reaction chamber portion and having a catalytic coating on the surface thereof which is in communication with said conduit, means forming with the opposite surface of said porous refractory body a closed chamber, means for introducing a first fluid into said closed chamber and thence through the pores of said porous refractory body into said conduit, means for flowing a second fluid longitudinally through said conduit past said porous refractory body, said porous refractory body being so positioned within said conduit with respect to said reaction chamber portion thereof that said first fluid flowing through its pores has at least lateral vector components with respect to said reaction chamber portion of the conduit, whereby rapid and intimate admixture of said rst and second fluids occurs at and near said catalyst coated surface and the admixture immediately flows away from said surface into and longitudinally through said elongated reaction chamber, and means for withdrawing iiuids from the downstream end of said reaction chamber.

2. Apparatus suitable for effecting reaction between fluids which comprises a tubular T co-mposed of a cylindrical main or through portion and a cylindrical branch portion perpendicular thereto and in communication therewith, one

part of said through portion beyond the junction with said branch comprising a reaction chamber more elongated than the other part of said through portion on the opposite side of said junction, a porous refractory cone axially positioned in and closing said other part having its apex extending into the central junction portion of said T so as to produce only a partial restriction of flow therethrough, said porous refractory cone having a catalytic coating on the outer surface thereof which is in communication with said T, means for introducing a first fluid into said T through the pores of said cone, means for inf troducing a second uid into said T through said branch portion, and means for withdrawing fluids from the end of said reaction chamber.

3. Apparatus suitable for effecting reaction between iiuids which comprises an elongated tube, a porous refractory section of said tube having a restricted cross-section and having a catalytic coating on the inner surface thereof, a casing surrounding said porous section of restricted crosssection and forming therewith a closed chamber, means for introducing a rst fluid into said closed chamber and thence through the pores of said refractory material into the interior of said tube. means for flowing a second fluid longitudinally through said tube, and means for withdrawing fluids from said tube at a point downstream from said restricted section.

4. Apparatus suitable for effecting reaction between fluids which comprises an elongated tube, a porous section of said tube having a restricted cross-section and having a catalytic coating on the inner surface thereof, a casing surrounding said porous section of restricted cross-section and forming therewith a closed chamber, means for introducing a first uid into said closed chamber and thence through the pores of said restricted section into the interior of said tube, means for flowing a second fluid longitudinally through said tube, and means for withdrawing fluids from said tube at a point downstream from said r stricted section.

5. Apparatus suitable for effecting reaction between fluids which comprises an L-shaped conduit, a porous refractory plate disposed in the corner thereof so as to produce only a partial restriction of flow therethrough and so as to form a closed chamber between said plate and the outer corner of said L, said porous refractory plate having a catalytic coating on the surface thereof which is in communication with said conduit, means for introducing a first fluid into said closed chamber and thence through the pores of said porous plate into said conduit, means for owing a second iiuid through said L-shaped conduit, and means for withdrawing fluidsv from said conduit at a point downstream from saidiL.

JOHN GORDON ALLEN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,270,989 Taliani July 2, 1918 1,309,623 Henwood July 15, 1919 1,960,608 Weber May 29, 1934 2,071,119 Harger Feb. 16, 1937 2,387,731 Allen Oct. 30, 1945

Claims (1)

1. APPARATUS SUITABLE FOR EFFECTING REACTION BETWEEN FLUIDS WHICH COMPRISES A CYLINDRICAL CONDUIT AN ELONGATED PORTION OF WHICH COMPRISES A REACTION CHAMBER, A POROUS REFRACTORY BODY OF RELATIVELY LARGE SURFACE AREA WITHIN SAID CONDUIT IMMEDIATELY UPSTREAM OF SAID REACTION CHAMBER PORTION AND HAVING A CATALYTIC COATING ON THE SURFACE THEREOF WHICH IS IN COMMUNICATION WITH SAID CONDUIT, MEAND FORMING WITH THE OPPOSITE SURFACE OF SAID POROUS REFRACTORY BODY A CLOSED CHAMBER, MEANS FOR INTRODUCING A FIRST FLUID INTO SAID CLOSED CHAMBER AND THENCE THROUGH THE PORES OF SAID POROUS REFRACTORY BODY INTO SAID CONDUIT, MEAND FOR FLOWING A SECOND FLUID LONGITUDINALLY THROUGH SAID CONDIUT PAST SAID POROUS REFRACTORY

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