US3071633A - Process and apparatus for producing unsaturated hydrocarbons - Google Patents

Description

Jan. 1, 1963 H. HESKY 3,071,633

PROCESS AND APPARATUS FOR FRODUCING UNSATURATED HYDROCARBONS Filed July 13, 1959 /Nl/FNTOP.' Hm MM,

Uite tates Patent Olilice senesi Patented dan.. l, 1963 3,071,633 PRQCESS ANB) APPARATUS FUR PRDUCiN-G UNSAIURATED HYDRUCARBNS Hans Heslry, Frankfurt am Main, Rodeiheim, German', assigner to H. Si. Zimmer Verfahrenstechnik Frankfurt am Main, Germany Filed .iuiy 33, 1959, Ser. No. @25,5716 Claims priority, application Germany .luly ld, i958 1S Claims. (Cl. Z60m-6d@ The invention relates to a process and apparatus for producing unsaturated hydrocarbons by combustion of saturated hydrocarbons with oxygen and quenching the reacted gases in a reaction chamber.

lt is known to produce acetylene, for example, by blowing pre-heated methane and pre-heated oxygen separately into an oven where the streams of gas mix and the miX- ture deagrates after a certain time and suitable slowing down of its velocity. Shortly after the reaction the combustion gases are quenched, so that acetylene and hydrogen are obtained, these being subjected to any desired subsequent treatment.

The ovens employed for carrying this process into etlect have below the feed conduits for the reactants a chamber widening after the fashion of a dilfuser and which is Closed in relation to the reaction chamber by a gas distributor having the form of a wall provided with a plurality of holes arranged substantially at equal intervals. Below this gas distributor there takes place the reaction by combustion of the reactants and also the subsequent quenching of the combustion gases.

In ovens designed in this manner experience shows that, in addition to the acetylene the production of which is desired, comparatively large quantities of soot are also produced. This is attributable to the fact that below the gas distributor a zone of unequal combustion develops because in the region of the holes of the gas distributor the gases passing therethrough force the flame downwardly in zig-zag form. Different dwell periods of the reactants under comparatively high temperatures thereby occur between the salient teeth and the re-entrant teeth of the llame front, as a result of which decomposition of the formed acetylene into soot or black and hydrogen takes place in the re-entrant teeth and this results in the undesirable intensified soot formation already mentioned.

A further disadvantage of the manner in which this process proceeds is that deposits are formed on the underside of the gas distributor which consist partly of soot and also partly of other solid or viscous liquid substances. In order to remove these deposits, which slowly grow into the reaction chamber in the direction of the cooling jet, it is necessary in the known constructions of such ovens to provide continuously or intermittently operating scraping devices which complicate the structure of the oven and are liable to cause trouble.

Moreover, in the known method of conducting this process, owing to the unavoidable retardation of the Velocity of the gas at the walls of the openings, the flame readily flashes back upwardly and this then makes it essential to put the oven out of operation.

The invention aims to eliminate the drawbacks of the known method of conducting the process and proposes to this end that the boundary or outer layers of the already mixed gases be sucked off ahead of the reaction chamber, ie., the boundary layers of gas mixture are removed at a point at which the mixture has not yet reached the reaction chamber. ln this way the stream of gas moving towards the gas distributor is equalized in its forward movement through the chamber ofthe oven widening after the fashion of a diffuser, whereby the disadvantageous phenomena previously mentioned are at once substantially mitigated. It is particularly advantageous, however, to

omit the gas distributor altogether, which is readily possible since, owing to the sucking off of the boundary layers, there is obtained an even distribution of velocity of the gases flowing through the chamber or space widening after the fashion of a diffuser and these gases, after reaching the reaction zone, which has heretofore been bounded by the gas distributor, detlagrate automatically with a substantially conical ame front and are then quenched.

Preferably the comparatively hot gases sucked oil from that zone of the oven which widens after the fashion of a diuser are quenched after issuing from this zone in order thereby to cool them and permit their utilisation without any ditliculty to their further application, since the gases drawn off will generally not be allowed to go to waste. The further application may, for example, take the form of the use of these gases for heating the gases taking part in the reaction by burning such gases. It is also possible, however, to reintroduce the drawn-off portions of the reaction gases into the process, it being particularly advantageous to blow them into the reaction chamber a short distance ahead of the reaction zone at the side wall of the reaction chamber. The injection is advantageously carried out in the direction of the wall, so as to accelerate in this way the retarded boundary layer developing as a rule at the wall, whereby the form of the dames can be further and advantageously inuenced.

The suction boxes are preferably fed with a quenching liquid, preferably water, through spraying devices arranged inside them. If required, sprinkled or irrigated filling bodies may be placed in the suction boxes.

A special advantage of the process according to the invention is that it is possible as a result thereof to employ a hollow conical spray nozzle arranged centrally in the reaction chamber, said nozzle being preferably designed so as to be vertically adjustable for the purpose of adaptation to the progress of the reaction.

Since, during the transformation of such saturated hydrocarbons in the presence of oxygen to give unsaturated iydrocarbons, formaldehyde is formed in the region where the hydrocarbons are mixed with the oxygen and is of course also sucked off during the sucking oli of the boundary layers and assists the readiness of the drawn-olf gases for ignition, it is advantageous to separate this formaldehyde, which can also be used to advantage for other purposes, from the drawn-olf gases and apply it to some other separate use. Although, owing to the sucking off of the boundary layers, a comparatively large proportion, of the order of magnitude of 10% of the reaction gases proper, is undoubtedly removed `from the process, this apparent loss is nevertheless very largely compensated by suitable further use of the sucked-olf gases and by the reduction of the soot formation and simplification of the method of conducting the process. Moreover, in the process according to the invention, it is possible to increase the degree of pre-heating, since the danger of flashback is completely eliminated, whereby again higher yields of the product to be obtained are produced. The apparent loss due to the sucking olf of the gases is more than compensated by the advantages of the method according to the invention, i.e. the controllability of the process, the reliability of operation and the saving of devices for cleaning the gas distributor. The: latter is of not inconsiderable importance and moreover the stoppage periods caused by flashback are basically eliminated.

An embodiment of the object of the invention is illustrated in the accompanying drawings, in which:

FIGURE l is a section through an oven constructed according to the invention for producing acetylene, and

FIGURE 2 shows a detail of the oven according to FIGURE 1.

In the drawings the reference numeral 1 designates the wall of the mixing space or chamber, said wall being provided at its upper end with holes 2 and being surrounded at this point by an annular jacket 3 into which the feed pipe 4 for the methane opens. Furthermore, the feed pipe 5 for the oxygen is arranged centrally in the upper part of the mixing space or chamber l.

According to the invention that part of the mixing space 1 which widens after the fashion of a diffuser is surrounded by a suction chamber 6 provided with a connection 7 for a source of subpressure shown schematically at 7a. In the region of the suction chamber 6 the wall of the mixing chamber 1 is provided with holes or slots S so that the interior of the mixing chamber l is in communication with the suction chamber 6. Below this part of the mixing chamber 1 with its perforated wall there is disposed in communication therewith the reaction chamber 9, which has an outlet orifice lil for the acetylene produced and for the other fission gases. The reference numeral 11 denotes a sump for the quenching liquid, preferably water, while reference numeral 12 indicates the discharge pipe through which the sump 11 is emptied. In the embodiment illustrated there extends through the discharge pipe 12 a conduit 13 provided at its upper end with a spray nozzle 14 which directs an umbrella-like spray jet 15 against the llame front 16 of the mixture of methane and oxygen leaving the mixing chamber Il and which has been ignited, and in this way quenches the reaction. Conduits for a medium, preferably water, impinging against the outer wall of the mixing chamber 1 and quenching the sucked-oit gases are provided in the suction chamber 6 at 17. As set forth above, the suction chamber 6'may contain sprinkled or irrigated iilling bodies; FIGURE 1 shows, for the sake of clarity, only a portion of the volume of chamber 6 as being tilted by such bodies, at 6a.

It will be seen from the above that, according to the present invention, the gaseous mixture formed in the upper cylindrical part of the mixing chamber 1 moves from that part downwardly through the haring part and from there into the reaction chamber. However, before the mixture reaches this reaction chamber, the boundary layers of the mixture will be sucked oif, this taking place, in the illustrated embodiment, in the `aring part formed with the holes or slots which communicate with the interior of the suction chamber t5, the latter forming together with the suction pump or the like connected at 7, a suction means which serves to remove the boundary layersl of the gas mixture. In this way, an even distribution of the gas iiow velocity is obtained.

In FIGURE 2 the reference 1 denotes the wall of the mixing chamber, while the reference 6 again designates the suction chamber. At 13 t-here is a connection 19 opening into the reaction chamber 9. In this way the gases drawn o through the suction chamber o can be injected wholly or partially into the reaction chamber 9 along the wall of the latter, whereby the boundary layers at the wall are accelerated and a further improvement in the form of the flame 16 is obtained.

The devices referred to above for separating the formaldehyde formed and for returning the drawn-off gases, if required, to the upper part of the mixing chamber by way of the methane or oxygen feed pipes are not shown in the drawing.

I claim:

1. A process for theproduction of unsaturated hydrocarbons comprising in combination the steps of eifecting combustion of saturated hydrocarbons with oxygen, quenching the reacted gases in a reaction chamber and sucking olf the boundary layers of the already mixed gases ahead of the reaction chamber, whereby an even distribution of the gas flow velocity is obtained.

' 2. A process for the production of unsaturated hydrocarbons comprising in combination the steps of eifecting combustion of saturated hydrocarbons with oxygen and burning the gases freely in a reaction chamber, quenching the reacted gases in the reaction chamber and sucking off the boundary layers of the already mixed gases ahead of the reaction chamber, whereby an even distribution of the gas flow velocity is obtained.

3. A process for the production of unsaturated hydrocarbons comprising in combination the steps 0f effecting combustion of saturated hydrocarbons with oxygen, quenching the reacted gases in a reaction chamber and sticking oif the boundary layers of the already mixed gases ahead of the reaction chamber and quenching them, whereby an even distribution of the gas iiow velocity is obtained.

4. The process of claim 1 which further comprises burning the sucked-orf portions of the reaction gases to heat the gases taking part in the reaction.

5. The process of claim 1 which further comprises reintroducing the sucked-0E portions of the reaction gases into the process.

6. The process of claim 1 which further comprises reintroducing the sucked-oft portions of the reaction gases into the process along the outer wall of the reaction chamber.

7. 'The process of claim 1 which further comprises separating from the sucked-oit` gases the formaldehyde formed during the reaction.

8. A method for making unsaturated hydrocarbons, comprising the steps of mixing saturated hydrocarbon with oxygen, moving the mixture toward a reaction chamber wherein the mixture is quenched, and sucking off boundary layers of the already mixed hydrocarbon and oxygen before the mixture reaches the reaction chamber, whereby an even distribution of the gas flow velocity is obtained.

9. A method for making unsaturated hydrocarbons, comprising the steps of mixing saturated hydrocarbon with oxygen, moving the mixture toward a reaction chamber wherein the mixture is quenched, and Sucking ol boundary layerstotalling about 10% or' the mixture of the already mixed hydrocarbon and oxygen before the mixture reaches the reaction chamber, whereby an even distribution of the gas flow velocity is obtained.

l0. An apparatus for making unsaturated hydrocarbons by combustion of saturated hydrocarbons with oxygen, comprising, in combination: mixing means form- .ing a mixing chamber, said means having an inlet part and a haring part formed with openings therethrough and communicating at its narrow mouth with said inlet part; means communicating with said inlet part of said mixing chamber for introducing thereinto Saturated lhydrocarbon and oxygen; means communicating with the widemouth of said riaring part of said mixing chamber and forming a reaction chamber; a quenching device arranged in said reaction chamber; and suction pump means communicating by way of communicating means with said openings of said Haring part of said mixing means for establishing in said communicating means a pressure which is less than that prevailing within said flaring part immediately in the vicinity of said openings thereof, thereby removing boundary layers of already mixed hydrocarbon and oxygen before the mixture is exposed to the action of said quenching device in said reaction chamber, whereby an even distribution of the gas How Velocity is obtained.

11. An apparatus as defined in claim 10 wherein said communicating means include an annular chamber arranged exteriorly of and surrounding said flaring part of said mixing means.

12. An apparatus as dened in claim 11 wherein said suction pump means further comprise a suction pump, communicating with said annular chamber.

13. An apparatus as dened in claim 1l, further comprising spraying means arranged in said annular chamber for quenching the wall of said aring part.

14. An apparatus as defined in claim 11, further com:-

prising irrigated filling bodies arranged in said annular chamber.

15. An apparatus as defined in claim 11, further comprising means placing said annular chamber in communication with said reaction chamber at a point subsequent to said openings in said Haring part.

16. An apparatus as defined in claim 10 wherein said quenching device comprises a hollow conical spray nozzle arranged centrally in said reaction chamber.

17. An apparatus as defined in claim 16, further comprising means for adjusting said spray nozzle in a direction toward and away from said mixing chamber.

`18. A method for making unsaturated hydrocarbons, comprising the steps of mixing a saturated hydrocarbon with oxygen, moving the mixture through a flaring part toward a reaction chamber wherein the mixture is quenched, and sucking ot boundary layers of the already mixed hydrocarbon and oxygen as the mixture moves through said aring part and therefore before the mixture reaches the reaction chamber, whereby an even distribution of the gas ow velocity is obtained.

References Cited in the iile of this patent UNITED STATES PATENTS 2,572,338 Hartwig et al Oct. 23, 1951 2,672,488 Jones Mar. 16, 1954 2,822,411 Braconier et a1 Feb. 4, 1958

Claims (2)

1. A PROCESS FOR THE PRODUCTION OF UNSATURATED HYDROCARBONS COMPRISING IN COMBINATION THE STEPS OF EFFECTING COMBUSTION OF SATURATED HYDROCARBONS WITH OXYGEN, QUENCHING THE REACTED GASES IN A REACTION CHAMBER AND SUCKING OFF THE BOUNDARY LAYERS OF THE ALREADY MIXED GASES AHEAD OF THE REACTION CHAMBER, WHEREBY AN EVEN DISTRIBUTION OF THE GAS FLOW VELOCITY IS OBTAINED.

10. AN APPARATUS FOR MAKING UNSATURATED HYDROCARBONS BY COMBUSTION OF SATURATED HYDROCABONS WITH OXYGEN, COMPRISING, IN COMBINATION: MIXING MEANS FORMING A MIXING CHAMBER, SAID MEANS HAVING AN INLET PART AND A FLARING PART FORMED WITH OPENINGS THERETHROUGH AND COMMUNICATING AT ITS NARROW MOUTH WITH SAID INLET PART; MEANS COMMUNICATING WITH SAID INLET PART OF SAID MIXING CHAMBER FOR INTRODUCING THEREINTO SATURATED HYDROCARBON AND OXYGEN; MEANS COMMUNICATING WITH THE WIDE MOUTH OF SAID FLARING PART OF SAID MIXING CHAMBER AND FORMING A REACTION CHAMBER; A QUENCHING DEVICE ARRANGED IN SAID REACTION CHAMBER; AND SUCTION PUMP MEANS COMMUNICATING BY WAY OF COMMUNICATING MEANS WITH SAID OPENINGS OF SAID FLARING PART OF SAID MIXING MEANS FOR ESTABLISHING IN SAID COMMUNICATING MEANS A PRESSURE WHICH IS LESS THAN THAT PREVAILING WITHIN SAID FLARING PART IMMEDIATELY IN THE VICINITY OF SAID OPENINGS THEREOF, THEREBY REMOVING BOUNDARY LAYERS OF ALREADY MIXED HYDROCARBON AND OXYGEN BEFORE THE MIXTURE IS EXPOSED TO THE ACTION OF SAID QUENCHING DEVICE IN SAID REACTION CHAMBER, WHEREBY AN EVEN DISTRIBUTION OF THE GAS FLOW VELOCITY IS OBTAINED.

Images