MXPA99010008A - Process and burner for the partial oxidation of hydrocarbons - Google Patents

Abstract

A process for the partial oxidation of hydrocarbons wherein a hydrocarbon-comprising gas flow (19) and a free oxygen-comprising gas flow (18) are fed into a reaction chamber (13), is distinguished by that it comprises the steps of:- mixing and reacting a first portionof the free oxygen-comprising gas flow with a first flow comprising reacted gases circulating within the reaction chamber;- mixing a second portion of the free oxygen-comprising gas flow with the hydrocarbon-comprising gas flow in the reaction chamber obtaining a gas flow comprising both hydrocarbons and free oxygen at least partly mixed together;- mixing and reacting the gas flow comprising both hydrocarbons and free oxygen at least partly mixed together with a second flow comprising reacted gases circulating inside the reaction chamber obtaining a gas flow comprising hydrogen and carbon monoxide.

Description

PROCESS AND BURNER FOR THE PARTIAL OXIDATION OF HYDROCARBONS FIELD OF THE INVENTION The present invention relates to a process for the partial oxidation of hydrocarbons to produce gaseous mixtures comprising hydrogen and carbon monoxide, for example as the synthesis gas and the reducing gas or fuel. In particular, the invention relates to a partial oxidation process comprising the steps of: feeding a gas flow comprising hydrocarbon to a reaction chamber; - feeding a gas flow comprising free oxygen into the reaction chamber. Throughout this specification and the appended claims the term "hydrocarbon (s)" is used to denote a heavy and / or light, saturated and / or unsaturated hydrocarbon, or mixtures thereof (eg, C? -C6); the expression "gas flow comprising hydrocarbons" is used to denote a fluid containing gaseous hydrocarbons, for example methane or natural gas, or a gaseous flow comprising solid suspended fuel (for example coal dust or coal soot) or a gaseous stream comprising liquid dispersed hydrocarbons (e.g.

P1649 / 99MX heavy or light hydrocarbons) as combustoleos or naftas). In technical language, a flow of gas containing suspended liquid hydrocarbons is usually referred to as "vapor or mist" while a flow of gas containing dispersed solid hydrocarbons is determined "smoke". The invention also relates to a burner to implement the above processes. As is known in the field of partial oxidation of hydrocarbons there is an increasing demand for high performance processes that can be easily implemented and that are efficient in both energy and costs.

PREVIOUS TECHNIQUE To meet the above demands, processes have been developed wherein the oxidation reaction is carried out at relatively low temperatures of the order of 1300 ° C in order to significantly reduce oxygen consumption and produce hydrogen and carbon monoxide in a more economic way. A process of this kind is described in EP-A-0 276 538, for example, where a gas flow comprising hydrocarbon is first mixed with a recovered solution comprising carbon soot and then, after evaporation of the water P1649 / 99MX contained in the solution, is mixed with oxygen in a reaction chamber at a temperature in the range of 927 ° C to 1316 ° C, combustion to form hydrogen and carbon monoxide is carried out in that chamber. While this prior prior process does not provide a reduction in the energy consumption in the reaction chamber or in the amount of oxygen to be fed to the reaction chamber, it has several advantages, as mentioned below. First, the carbon soot formed from pyrolyzed hydrocarbons in the reaction chamber that, in proximity to the burner, come into contact and mix with the hot gases that are circulating inside the chamber before they can be mixed properly. with oxygen. This production of carbon soot is mainly disadvantageous as it would require a full series of high-energy operations to separate the carbon soot from the reaction products and feed it back into the reaction chamber, and also because a plant is needed more complicated to implement the process and the cost of operation and capital is high. In addition, the carbon soot produced within the reaction chamber affects the overall performance of the partial oxidation process, P1649 / 99MX by decreasing the amount of hydrogen and carbon monoxide that can be obtained per unit of burned hydrocarbon, even when all the carbon soot produced and returned to the burner is gasified. On the other hand, the above processes effective to produce low concentrations of carbon soot involve the operation of the reaction chamber at very high temperatures (of the order of 1400 ° C) and, therefore, at a high rate of oxygen consumption and low conversion rate, for example as described in EP-A-0 276 538, page 2, lines 6-13. In addition, the plants to implement the aforementioned processes have the disadvantage that their operation is not flexible, being unable to adapt to large load variations to which reagents that are fed into the reaction chamber may be subjected, with the result that that the variations can activate or reinforce the formation of carbon soot. Due to these limitations of the prior art processes for the partial oxidation of hydrocarbons, large investment costs have been involved for their practical implementation, significantly limiting the production costs of those basic materials such as hydrogen and carbon monoxide, since has a broad demand for P1649 / 99MX them. In addition, the increasing demand in the field of waste hydrocarbons as residues from the distillation process in the oil industry can not be met by the aforementioned processes.

SUMMARY OF THE INVENTION The technical problem to be solved with this invention is to provide an improved process for partial oxidation of hydrocarbons, in high yields, which allows the high production of hydrogen and carbon monoxide per unit of burned hydrocarbon, while drastically decreasing the Coal soot formation even when operating at low temperatures, and is flexible and easy to implement with a reasonably low power consumption and low operating costs. According to the present invention, the above problem is solved with a process as indicated above, characterized in that it also comprises the steps of: mixing and reacting a first portion of the gas flow comprising free oxygen with a first flow comprising reacted gases circulating within the reaction chamber; mix a second portion of the flow of gas comprising free oxygen with the gas flow P1649 / 99MX comprising hydrocarbon in the reaction chamber, obtaining a gas flow comprising both hydrocarbons and free oxygen at least partially mixed together; - mixing and reacting the gas flow comprising the two hydrocarbons and the free oxygen at least partially with each other with a second flow comprising reacted gases circulating inside the reaction chamber, obtaining a gas flow comprising monoxide of carbon and hydrogen. Through this description and the claims the expression "gas flow comprising reacted gases" is used to denote a gas flow containing H20, C02, traces of hydrocarbons, H2S, COS, and possibly circulating N2 and Ar. within the reaction chamber, in addition to the products of partial combustion, ie CO and H2. Advantageously, this investment allows the production of hydrogen and carbon monoxide per unit of burned hydrocarbon to be substantially increased in relation to the processes of the prior art. In fact, thanks to the step of mixing a portion of the flow of gas comprising free oxygen with the flow of gas comprising hydrocarbon inside the reaction chamber, before the flow just mentioned is put in contact with the P1649 / 99MX hot gases circulating inside the chamber, the formation of carbon soot during the next combustion step can be avoided or at least reduced dramatically. In this way, the conversion performance of the hydrocarbons in the reaction chamber will only be marginally affected, if it is affected, by the presence of carbon soot, thus ensuring optimum production of hydrogen and carbon monoxide. It should be noted that thanks to the present invention the formation of carbon soot in the reaction chamber can be totally suppressed when the stream being processed comprises gaseous hydrocarbons, and can be kept to a minimum even when the gas flow comprises liquid hydrocarbons and / or solids These results are advantageously obtained even when operating at low temperatures, preferably in the range of 950 ° to 1300 ° C and, therefore, at lower oxygen consumption rates and higher yields (higher CO and H2 production) to the prior art. As an example, for all the partial oxidation of natural gas, in a condition of total absence of carbon soot, the oxygen requirement can be kept below 210 moles of 02 per kilolol of dry gas produced, which represents an achievement P1649 / 99MX quite surprising compared to the oxygen requirements of the prior art processes. In other words, the processes of the invention prevent a portion of the hydrocarbons flowing through the reaction chamber from mixing, in the absence of oxygen, directly with the gases at high temperature (for example in the range of 1000 ° to 1400 ° C) inside the chamber, causing the hydrocarbons to pyrolize and to form carbon soot. On the contrary, inside the reaction chamber, the hydrocarbons are first mixed properly with the free oxygen and only then they are put in contact with the hot gases, the hot gases later activate an advantageous combustion, and not the pyrolysis reaction of the reagents at least partially premixed, to produce hydrogen and carbon monoxide. Furthermore, the process of this invention is quite simple, economical and easy to implement and does not imply high energy consumption or high operation and maintenance costs. It should be noted that for the combustion of gaseous hydrocarbons, for example methane or natural gas, the plant that implements this process will not require separation of the carbon soot and a recirculation section, therefore P1649 / 99MX will provide greater savings in investment costs and greater savings in energy consumption compared to the plants of the prior art. Selling, the process of the present has proved to be very flexible since it can adapt to a wide variety of operating conditions while retaining its high rate of return. In particular, this process can be effectively applied even in the case of large variations in the speed of the flows fed into the reaction chamber, for example in the range of 0.2 to 1.0 (ratio of minimum to maximum flow velocity), without affecting the conversion performance, a feature of this type can not be found in prior art processes. The portion of the gas flow comprising free oxygen that is mixed within the reaction chamber with the flow of gas comprising hydrocarbons, before being contacted with the recirculated reacted gases, referred to as the second portion of the process according to the invention, they advantageously comprise between 10 and 90%, preferably between 50 and 70% of the gas flow comprising free oxygen. In a particularly advantageous embodiment of the invention, this process comprises the step of feeding the gas flow comprising hydrocarbon and the gas flow comprising oxygen to the nor c a i a a «, reaction chamber, as appropriate, in substantially annular and coaxial jets among themselves. Therefore, the mixing of the hydrocarbons and the free oxygen can be effected in a very efficient and immediate manner within the reaction chamber. Furthermore, it has been found that in order to promote the mixing action it is more advantageous that the gas flow comprising hydrocarbon is fed to the reaction chamber in the outward direction and preferably at a rate higher than that of the gas flow comprising oxygen free. Preferably, according to the above embodiment, the process of the invention further comprises the steps of: causing the flow of gas comprising free oxygen to flow through a first essentially cylindrical conduit of a predetermined length of a burner extending towards the reaction chamber; causing the flow of gas comprising hydrocarbon to flow through a substantially annular free space defined between the first conduit and a second external conduit coaxial with the first, the second conduit is longer than the first conduit and within it defines the reaction chamber, between one end of the second conduit and one end of the first conduit, a mixing zone P1649 / 99MX for the hydrocarbon, comprising gas flow and gas flow comprising oxygen; directing the gas flow comprising hydrocarbon from the essentially annular free space to a region of the mixing zone near an internal wall of the second conduit; expanding and directing the flow of gas comprising free oxygen leaving the first conduit to the inner wall of the second conduit in the mixing zone, thereby mixing and reacting a first portion of the gas flow comprising free oxygen with a first flow that comprises reacted gases circulating within the reaction chamber in a central zone thereof, and mixing a second portion of the gas flow comprising free oxygen with the gas flow comprising hydrocarbons obtaining a gas flow comprising both hydrocarbons and free oxygen in at least one partially mixed form. In this way, the desired premixing of the hydrocarbons and free oxygen can be achieved in the reaction chamber in a highly reliable and efficient way, while during this step all contact of the hydrocarbons with the reacted gases that are being made is avoided. circulate inside the camera. Advantageously, this premix is made to be present as part of the internal wall of the duct fed for the flow of gas comprising hydrocarbons, which extends between its end and the end of the conduit fed to the flow of gas comprising free oxygen. In practice, part of the flow comprising free oxygen is advantageously brt into the flow comprising hydrocarbon and a sufficient degree of mixing is achieved in a very small space to avoid, in the case of gaseous hydrocarbons, the formation of coal soot or drastically decrease, in the case of liquid and / or solid hydrocarbons, said formation, during the subsequent mixing with the hot gases circulating inside the reaction chamber. To promote the expansion and transport of the gas flow comprising free oxygen to the inner wall of the second conduit in the mixing zone, this gas flow is preferably made to flow thr the first conduit along a flow path in spiral. According to a further aspect of the invention, there is provided a burner for the partial oxidation of hydrocarbons comprising: a first essentially cylindrical conduit of a predetermined length defining, within it, a circular passage for feeding a gas flow comprising free oxygen to a reaction chamber outside the burner; P1649 / 99MX a second conduit, outside the first conduit and coaxial with it but not of greater length, which defines a substantially annular free space on its interior between the conduits, for feeding a gas flow comprising hydrocarbon to the reaction chamber; and characterized in that it further comprises: a mixing zone, wherein the gas flow comprising hydrocarbon is mixed with the flow of gas comprising free oxygen defined within the respective ends of the first and second conduits; means for directing the flow of gas comprising hydrocarbon from the substantially annular free space to a region of the mixing zone near an inner wall of the second conduit; means for expanding and directing the entire flow of gas comprising free oxygen leaving the first conduit to the inner wall of the second conduit in the mixing zone, in order to mix and react a first portion of the gas flow comprising free oxygen with a first flow comprising the reacted gases circulating within the reaction chamber in a central zone thereof, and for mixing a second portion of the gas flow comprising free oxygen with the flow of P1649 / 99MX gas comprising hydrocarbon obtaining a gas flow comprising both hydrocarbons and free oxygen, at least partially mixed. The features and advantages of the invention may be better understood by reading the following description of one embodiment of the process of the invention, which is provided as a non-limiting example with reference to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: Figure 1 is a longitudinal sectional view of a model schematically illustrating the flow paths of reactants and reacted gases within a hypothetical gas generator, when the process is used to the partial oxidation of hydrocarbons according to a preferred embodiment of the present invention; Figure 2 shows schematically a plant for the partial oxidation of gaseous hydrocarbons that implements the process of the present invention; - Figure 3 shows a longitudinal sectional view of a detail of a burner according to a preferred embodiment of the present invention; Figure 4 shows a sectional view P1649 / 99MX longitudinal of a detail of a burner according to another embodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED MODALITY To explain the principle and operation of this partial hydrocarbon oxidation process, reference will be made to Figure 1 which schematically shows the flow paths of the various gas flows through a hypothetical gas generator that it operates according to a preferred embodiment of the invention. In Figure 1 schematically shows the end portion of a burner that extends into a reaction chamber that is generally designated with the number 2, a hypothetical gas generator, and is specifically placed in the central area 2A of the chamber 2. A gas flow 3 comprising free oxygen and a gas flow 4 comprising hydrocarbon are fed to zone 2A of burner 1 through respective conduits 5 and 6. Specifically, the gas flows 3 and 4 are fed into the reaction chamber 2 in the form of annular jets, which are preferably obtained by causing the flow 3 to flow in a spiral path through the conduit 5, as indicated in the Figure 1 by means of a spiral arrow 3A, and that the flow 4 flows through an annular free space 7 P1649 / 99MX defined between conduits 5 and 6. Advantageously, by causing the gas reagents to be fed into the reaction chamber 2 in the form of annular jets, the flow containing the reacted gases (ie hydrogen and carbon monoxide) from the combustion of hydrocarbons is divided naturally into two flows 8A and 8B that circulate within the central zone 2A and a peripheral zone 2B, respectively, of the reaction chamber 2. As the flows 8A and 8B which comprise gas and which have reacted are quite hot, in general their temperature above 1000 ° C, their contact or mixing with the gaseous reactant flows causes the immediate combustion with flame formation in case of flow 3 comprising free oxygen, and pyrolysis of hydrocarbons coming from flow 4 comprising hydrocarbon. To avoid this hydrocarbon pyrolysis, which is responsible for the formation of carbon soot in the reaction chamber 2, the process of this invention comprises the step of mixing, at least in part, the hydrocarbons with the free oxygen before its mixture with the hot burned gases circulating inside the reaction chamber 2. For this purpose, the conduit 6 is longer than the conduit 5 and is formed with a frustoconical tip 6A extending towards the reaction chamber 2. Within this point 6A is defined, at a location close to the inner wall of the duct 6, a mixing zone for the gas flow 4 comprising hydrocarbon and the gas flow 3 comprising free oxygen, which is not disturbed by the flow of unreacted gas, especially flow 8B. To promote rapid efficient mixing of the hydrocarbons with free oxygen, conduit 5 is provided with an expansion cone 5A at its end. Only after the hydrocarbons and free oxygen have been mixed at least partially does a flow of gas containing hydrocarbons and free oxygen, generally indicated with the number 9, which is subsequently mixed with the flow 8B and reacted to produce hydrogen and carbon monoxide. The particular feed pattern of the annular jet type that is provided for the reactants, where the free oxygen jet flows into the hydrocarbon jet, in combination with the central circulation of part of the reacted gases, advantageously allows a little of the free oxygen mix and then react with the reacted gases circulating within the central zone 2A of the reaction chamber 2, giving P1649 / 99MX results in the flame generated within chamber 2 being established reliably and stable centrally near the free oxygen flow inlet zone into reaction chamber 2. In addition, by flowing oxygen in In the central region and the hydrocarbons in the outward direction, the tip 6A of the external conduit 6 of the burner 1 can be used to mix the reactants while protecting the hydrocarbons against the hot gases circulating in the peripheral zone 2B of the reaction chamber, as well as against the flame that is emitted from the central region of the burner 1. To fully explain the characteristics of this partial oxidation process, it should be noted that it is a totally different process to the diffusion or mixing processes of the prior art. The term "mixing process" refers to a process in which the flow of gas comprising hydrocarbon and the flow of gas comprising free oxygen are mixed together, normally within the burner, before they are fed into the reaction chamber. This mixing can be carried out either in a complete form, that is until a flow is obtained with uniform concentrations of oxygen and hydrocarbons, or in a partial form, that is to say with P1649 / 99MX a concentration field in the feed flow with respect to the reaction chamber that will depend on the extension and the mixing procedure. A process of this kind is disclosed, for example, in EP-A-0 098 043. Although in theory the mixing process is effective in keeping the production of carbon soot diminished, no practical application has been found due to its inherently dangerous nature. In fact, in operation, the gas generator presents the risk of igniting the burner, that is, the reaction and oxidation can be activated while it is still in the burner ducts, being always latent and resulting in premature wear of the burners. same. This is an almost uncontrollable phenomenon due to the high flammability of the hydrocarbon / oxygen mixture, the high operating temperatures and the possible variations in the flow rates of the reagents. The term diffusion process refers to a process in which the gas flow comprising hydrocarbon and the gas flow comprising free oxygen are fed in this case separately to the reaction chamber, where they are mixed simultaneously with each other and with the reacted gases present and circulating in the chamber.

P1649 / 99MX A process of this kind is, for example, that set forth in the aforementioned document EP-A-0 276 538. The problems of this conventional process have already been described in relation to the state of the art, in particular, its High production of carbon soot is notorious, which is due to the high temperature recirculation gases coming into contact with incoming hydrocarbons, inside the reaction chamber, which have not had the opportunity to mix properly with the free oxygen. In relation to the present invention, it should be noted that providing a preliminary mixing step within the reaction chamber for the flow of gas comprising hydrocarbon with the flow of gas comprising free oxygen, before the hydrocarbons can be brought into contact with the reacted gases, it contradicts the teachings of the prior art in the aspect that the reactants must either be mixed before they are introduced into the reaction chamber or only after their introduction simultaneously with the reacted gases. The research work developed by the applicant is the one that has led him to invent a partial hydrocarbon oxidation apparatus with high performance without having a production of P1649 / 99MX hydrocarbon soot is either produced in very small quantities. In essence, it can be said that the process of the invention reflects a kind of combination of the aforementioned processes, but without its problems and with a substantially higher conversion performance in hydrogen and carbon monoxide under similar operating conditions. In Figure 2, generally in the number 10 there is shown a plant for the partial oxidation of gaseous hydrocarbons according to the present invention. Advantageously, the plant 10 comprises two preheaters 11 and 12, respectively, for preheating a gas flow comprising hydrocarbon and a gas flow comprising free oxygen, a gas generator 13 for partially oxidizing the hydrocarbons and a boiler 24 for recovering the sensible heat from the resulting gas flow comprising hydrogen and carbon monoxide. The preheater 11 and 12 and the boiler 24 are of conventional type and will not be described in greater detail. The gas generator 13 comprises a nozzle 14 and a shell 15 which is lined with a refractory material resistant to high temperature, which is not shown to be conventional, to protectP1649 / 99MX internal walls. The inner shell 15 forms a reaction chamber 16 wherein the combustion of hydrocarbons with oxygen is carried out. A burner 17 extends through the nozzle 14 so that its end portion opens towards the interior of the reaction chamber 16. The gas flow comprising hydrocarbon is fed to the gas generator 13 by means of a conduit 18. which passes through the preheater 12. Similarly, the gas flow comprising oxygen is fed to the gas generator 13 by means of a conduit 19 passing through the preheater 11. In the example of Figure 1, the flow of gas comprising hydrocarbon comprises essentially gaseous hydrocarbons, for example natural gas or methane and mixtures thereof, and mixtures of these gases with the transport gases such as steam or inert gases. In addition, the gas flow comprising hydrocarbon can include predetermined amounts of gases from industrial plants, for example from a synthesis circuit of an ammonia plant. Alternatively, the gas flow comprising hydrocarbon may comprise a carrier gas, for example an inert gas or steam, which P1649 / 99 X has solid fuel or finely divided liquid, respectively dispersed or suspended therein. The term "finely divided" as used herein refers to droplets or solid particles of an average size in the range of 0.01 to 1.0 mm. Examples of suitable liquid fuels used in the process of the present invention include: fuel oil, diesel oil, naphtha, crude oil or residues from the distillation sections of oil plants, and mixtures thereof. Examples of solid fuels include: asphalts and coals, and mixtures thereof. When liquid or solid hydrocarbons are used, the plant in Figure 1 should include a processing and recovery section, not shown for any type of carbon soot produced. The gas flow comprising free oxygen generally comprises a gas selected from a group which includes: air, air enriched with oxygen, ie air having an oxygen content greater than 21 mole percent, essentially pure oxygen, i.e. gas with an oxygen content of not less than 95 mole percent, and mixtures thereof. The gas flows are heated independently through the preheater 2 P1649 / 99MX and 3, for example by convection at a temperature that is normally less than about 600 ° C, in preparatory form for feeding the gas flows to the gas generator 13. The plant 10 which implements the process of this invention can also be provided with a conventional desulphurization unit not shown in Figure 2, to remove any trace of sulfur from the gas flow comprising hydrocarbons. The working pressure inside the gas generator 13 is generally in the range of 1 to 150 bar. After preheating, the gas flows are fed to the gas generator 13 or, more precisely, to the reaction chamber 16 through the respective conduits of the burner 17. In particular, the gas flow comprising free oxygen is fed to the reaction chamber 16 through a circular passage defined within a first essentially cylindrical conduit 20, having a predetermined length. The gas flow comprising hydrocarbon is fed into the reaction chamber 16 through an annular free space formed between the first conduit 20 and a second external conduit 21, which is coaxial to the first conduit but not longer than this one. Advantageously, the burner 17 comprises P1649 / 99MX furthermore a mixing zone 22 defined within the reaction chamber 16 between respective ends of the conduits 20 and 21, wherein the reactants are premixed before being mixed with the flow of reacted gases circulating in the chamber. Immediately when leaving the mixing zone 22, in the reaction chamber 16, the mixing of the reactants is completed and the subsequent partial oxidation reaction of the hydrocarbons is carried out, obtaining a flow of gas containing hydrogen and carbon monoxide and leaving the gas generator. through the conduit 23. The oxygen to hydrocarbon molar ratio can vary between 0.5 and 1.2, according to the degree of purity of the gas flow containing free oxygen, the degree of preheating of the reactants and the type of hydrocarbon flow mixture. The reaction products are subsequently flowed, once again through the conduit 23, through the boiler 24 where they are cooled by indirect heat exchange with a water flow, to release steam at a high thermal level (for example in an interval of 20 to 100 bar). For this purpose, conduits 25 and 26 are provided in order to respectively supply water to boiler 24 and exhaust steam therefrom. Providing boiler 24 in the plant P1649 / 99MX of Figure 2 basically depends on the nature of the fuel being handled. When the latter provides a crude gas comprising hydrogen and carbon monoxide with a high content of impurities, it is cooled by a simple cooling device using water (not shown). The plant 10 just described can advantageously implement the process of this invention, the process is characterized in particular by comprising the mixing steps and reacting a first portion of the gas flow comprising free oxygen with a first flow comprising reacted gases circulating within the reaction chamber 16 and mixing a second portion of the gas flow comprising free oxygen with the flow of gas comprising hydrocarbon in the mixing zone 22 of the reaction chamber 16, to obtain a gas flow comprising both hydrocarbons and free oxygen, at least partially mixed with each other, and the step of mixing and reacting the gas flow obtained in this form in zone 22 with a second gas flow comprising reacted gases that they circulate inside the reaction chamber 16, to obtain a gas flow comprising hydrogen and carbon monoxide. In this way, the production of carbon soot can be suppressed or attenuated P1649 / 99MX significantly even when operating at low temperatures (below 1300 ° C), so that oxygen consumption can be narrowly reduced and the output of hydrogen and carbon monoxide can consequently be improved. As already stated, the process can be carried out efficiently even with significant variations in the flow rates of the reagent streams, without adversely affecting the conversion performance. It should be noted that the process of this invention can suppress the production of carbon soot entirely when handling flows comprising gaseous hydrocarbons. The presence of carbon soot depends essentially on the step of premixing of reactants within the reaction chamber 16 and, therefore, on the presence of free oxygen in the gas flow comprising hydrocarbon during the subsequent mixing with the circulation gases hot In order to promote complete mixing of the reactants and their subsequent combustion, it has been found useful to supply the gas flow comprising hydrocarbon to the reaction chamber 17 at a speed of 30 to 300 m / s, preferably from 60 to 180. m / s and the gas flow comprising free oxygen at a speed in the range of 10 to 100 m / s, preferably 20 to 60 P1649 / 99MX m / s. In an advantageous and especially preferred embodiment of the process according to the invention, the process further comprises the step of causing the flow of gas comprising free oxygen to flow through the first conduit 20, causing the flow of gas comprising hydrocarbon to flow to through the annular free space defined between the first conduit 20 and the second conduit 21, directing the flow of gas comprising hydrocarbon from the annular free space towards the mixing zone 22 at a location close to an internal wall 27 of the second conduit 21, and expanding and directing the flow of gas comprising free oxygen leaving the first conduit 20 towards the inner wall 27 of the second conduit 21 in the mixing zone 22. In this form, the free oxygen and the hydrocarbons can be premixed suitably in a form efficient and fast, while protecting the hydrocarbons from the hot gases circulating in the reaction chamber 16, as well as from the flame that is emitted from the central end of the burner 17 inside the chamber 16. As shown in Figure 3, the burner 17 advantageously comprises for this purpose, in addition to the ducts 20 and 21, a suitable means for directing the flow of gas comprising hydrocarbon from the annular free space 31 to the mixing zone 22 P1649 / 99MX in the reaction chamber 17, in a location close to the inner wall 27 of the second conduit 21 and comprising a means suitable to expand and direct the flow of gas comprising free oxygen leaving the first conduit 20 towards the wall internal 27 of the second duct 21, in the mixing zone 22. Figure 3 is a detailed view of the burner 17, in particular to illustrate the end portion of the burner, according to the preferred embodiment of the present invention. In this figure, articles equivalent in structure and function to those in Figure 2 have the same reference numbers and will no longer be described. It should be noted that the conduits 20 and 21 of the burner 17 are of hollow construction for more efficient cooling thereof, as will be explained below. At the end of the first conduit 20, the circular passage formed within the first conduit 20 and the annular free space defined between the second conduit 21 and the first conduit 20 of the burner 17, are denoted in Figure 3 with the reference numbers 28, 29 and 30, respectively. Advantageously, in order to accelerate the gas flow sweeping action comprising hydrocarbon through the inner wall 27 of the second conduit 21 in the mixing zone 22, the P1649 / 99MX means for directing the gas flow comprising hydrocarbon comprises an annular opening 31 thinner than the annular free space 30, which is formed at the end 28 of the first conduit 20, between the free space 30 and the mixing zone 22 The means for expanding and directing the gas flow comprising free oxygen advantageously comprises, near the end 28 of the first conduit 20, a portion of this conduit which essentially flares towards the inner wall 27 of the second conduit 21 in order to define, at the end 28, a gas flow outlet opening 33 between the passage 29 and the mixing zone 22, which has a larger diameter than the remainder of the first conduit 20. Therefore, the flow of gas comprising oxygen free will deviate and expand towards the wall 27 of the second conduit 21, thus ensuring optimal penetration into the hydrocarbon flow. The diameter of the opening 33 can vary between 1.25 and 10 the diameter of the first conduit 20 upwardly to the portion 32, and satisfactory results have been obtained in time intervals 2 to 4. As can be seen in Figure 3, the flared portion 32 of the first circuit 20 is advantageously curved to allow a controlled and as even as possible expansion of the gas flow • root comprising oxygen, while assisting it to direct it towards the inner wall 27 of the second conduit 21 in the mixing zone 22 In accordance with the process of this invention, the flow of gas comprising free oxygen is made to flow freely from the passage 29 to the mixing zone 22 through the outlet opening 33 of the first conduit 20. In parallel therewith, the gas flow comprising hydrocarbon is flowed freely from the free space 30 into the zone of mixed 22 through the annular opening 31 defined in the reaction chamber 16 between the end 28 of the first conduit 20 and the end 34 of the second conduit 21, close to its inner wall 27. Sale, according to an aspect Especially preferred of the present invention, the portion 32 extends continuously from an inner wall 20A to an outer wall 20B of the conduit 20, at a constant slope angle from the end of the p inner ared 20A towards the end of the outer wall 20B, or preferably, at a slope angle that varies continuously from 0 ° at the end of the inner wall 20A to at most 90 ° at the end of the outer wall 20B. Therefore, the end of the outer wall 20B forms the end 28 of the conduit 20 and the end of the outer wall 20A is coincident with the cylindrical end P1649 / 99MX of the conduit 20. This unique configuration of the portion 32 of the conduit 20 for feeding the gas flow comprising free oxygen into the reaction chamber 16 allows the rate of thermal wear of the end portion of that conduit near the end 28 is considerably slower. In fact, a study of the applicant has shown that the absence of sharp corners in the portion 32, ie in the portion connecting the inner wall 20A to the outer wall 20B of the conduit 20, is effective to prevent the formation of vortices or stagnation regions in the gas flow comprising free oxygen in the portion 32, protecting it against thermal wear. On the contrary, according to the invention, the oxygen is moved in a linear flow along the portion 32 before exiting the conduit 20, while its surface can be cooled. In particular, the initial gas flow contact comprising hydrocarbon flowing through conduit 21 with the flow of gas comprising free oxygen flowing through conduit 20 is advantageously made to be present at end 28 of conduit 20 It should be noted that the oxygen-fed conduits of the burners have an expansion due of no more than a few months in P1649 / 99HX the prior art arrangements, having to be replaced and therefore the whole plant has to be stopped. Thanks to the present invention, the life expectancy of the end portion of these ducts is much longer and can last several years before requiring their replacement, so that the plant can work continuously for extended periods of time. In this way, the costs and maintenance operation of the plant and production losses can be reduced. In particular, the curved shape of the portion 32 (shown in Figure 3) ensures optimal results in relation to duralibility of the conduit 20. In this aspect, satisfactory results have been obtained especially when adopting an angle dependent from 30 ° to 90 ° , preferably from 45 ° to 80 °, for the portion 32. According to a particularly advantageous aspect of the burner of the invention, the length of the inner wall 27 of the second conduit 21 in the mixing zone 22, measured between the ends respective 28 and 34 of the conduits 20 and 21, is established by the thickness dimension (cross-sectional area) of the annular opening 31 between the conduits 20 and 21. Preferably, this length will be from 5 to 15 P fi? Q / QQMY times the thickness dimension. By doing this, it is possible to optimally adjust (neither too little nor too much) a desired amount of pre-mixing of the reagents. According to a still further advantage of the burner of the present invention, the inner wall 27 of the second conduit 21 in the mixing zone 22 has a diameter that increases towards the end 34, so that the mixing zone 22 takes a frusto-conical shape . In particular, the angle dependent on the inner wall 27 of the second conduit 21 in the mixing zone 22 is advantageously in the range of 0 ° to 60 °, preferably 10 ° to 30 °, from the longitudinal axis 35. above-mentioned frusto-conical shape of the mixing zone 22, with its main circumference defined by the opening 36 of the burner 17 and its smaller circumference defined by the internal wall 27 of the second conduit 21 at the end 28 of the first conduit 20, essentially serves for a double function of maintaining the flow of gas comprising hydrocarbon away from the central flame and enlarging the width of the internal recovery zone (reference 2A, Figure 1) in order to achieve full stabilization (stable) of the f1ama. Advantageously, the burner 17 may also include suitable means for forcing the flow P1649 / 99MX of gas comprising free oxygen forms a spiral flow path through the first conduit 20, in order to promote the expansion and transport of the flow towards the inner wall 27 of the second conduit 21 in the mixing zone 22. In In the example of Figure 3, this means comprises one or more vanes 37 of suitable shape, optionally placed at an angle with respect to the longitudinal axis 35, located proximate to one end of a rod-shaped fastener, shown in Figure 3. by the duct 38 extending along a predetermined length coaxially through the passageway 29 defined by the duct 20. The vanes 37 have a shape imparting desired swirl movement in the gas flow. Preferably, the plurality of vanes 37 are helically positioned around conduit 38. In an alternative embodiment, not shown, this means may suitably conform to either conduit 20 or conduit 38. In Figure 3, conduit 38 is open sample as it advantageously serves the additional function of providing, in a simple and reliable manner, control of the gas flow comprising reacted gas circulated centrally in the reaction chamber 16, as well as in the stable position of the flame.

P1649 / 99MX For this purpose, a part of the gas flow comprising free oxygen is flowed through the interior of the conduit 38 in true axial flow which will oppose the sweep of the gas flow reacted through the central conduit 20. Alternatively, the duct 38 could be used during the refractory heating step, inside the gas generator, to supply fuel to the reaction chamber 16. In this form, the burner 17 can be advantageously used for the heating operation of the gas generator as well, eliminating the need for an additional burner that is provided for this purpose. As indicated in 39 and 40, there are also recesses in the walls of the first conduit 20 and the second conduit 21 for admitting a liquid refrigerant, preferably water. Therefore, the temperature of the conduits 20 and 21 can be effectively controlled, in particular at their ends 28 and 34, to avoid overheating and the probable rapid deterioration thereof. Under certain conditions of the operating temperature this cooling can be eliminated. Figure 4 is a detailed view of a burner according to another embodiment of the invention. In the figure, the pieces that are structural P1649 / 99MX and functionally equivalent to burner 17, in the manner shown in Figure 3, are denoted by the same reference numerals and will not be described further. According to this embodiment of the burner 17, the same protective effect that is provided by the inner wall 27 by the second conduit 21 in the mixing zone 22 (Figure 3) is now provided by a substantially annular jet, for example, of steam or of inert gases supplied to the reaction chamber 16 out of the hydrocarbon comprising flow. This additional or protective flow, as indicated by the arrows 41 of Figure 4, is effective (similar to the wall 27 of Figure 3) to isolate the mixing zone 22 from the flow comprising reacted gas (arrows 42) which circulate in the peripheral zone of the reaction chamber 16. The arrows 42 correspond to the arrows 8B of Figure 1. According to this embodiment, instead of increasing the length of the second conduit 21 relative to the first conduit 20, provide suitable means for letting in a protective gas flow (date 41), preferably comprised of steam and / or inert gases. For example, this input means can be a third conduit 43 placed externally to the conduits 20 and 21 and coaxially therewith. The number 44 denotes a defined free space nor cain «between the third conduit 43 and the second conduit 21 of the burner 17. According to the process of this particular embodiment of the invention, a gas flow comprising steam and / or inert gases is made to flow through the conduit 43 , so that it enters the reaction chamber 16 in the form of a substantially annular jet that defines a mixing zone 22 therein. At the same time, the flow of gas comprising free oxygen is flowed through passage 29 into the mixing zone 22 through the outlet opening 33 of the first conduit 20 and in parallel with it, the gas flow comprising The hydrocarbon is flowed through the free space 30 into the mixing zone 22 by the annular opening 31 defined between the end 28 of the first conduit 20 and the end 34 of the second conduit 21. The process of the partial oxidation of hydrocarbons and, in particular, of the premixed in the zone 22 of the gas flow comprising hydrocarbon with a second portion of the gas flow comprising free oxygen, in a condition of no contact with the hot gases circulating in the reaction chamber 16, is carried performed in a similar manner and provides the same advantages as mentioned above in relation to the previous figures.

P1649 / 99MX In the example of Figure 4, the gas flow 41 comprising steam and / or inert gases, by sweeping through the external wall of the duct 21, advantageously has a cooling effect on the duct, particularly in its extreme. Accordingly, the duct 21 can be made from a solid construction and not in a hollow form as shown in Figure 3.

The advantages of the distributor provided by the process of this invention can be appreciated more fully from the above description, in particular a partial oxidation reaction of the hydrocarbons can be carried out: in the total absence of carbon soot, for gaseous hydrocarbons, with a hydrocarbon plant. Simplified process implementation, with a simplified process implementation plant; with a drastic reduction of carbon soot in the case of liquid or solid hydrocarbons; at low rates of oxygen consumption and at high conversion rates in hydrogen and carbon monoxide per unit of burned hydrocarbon; and with longer life times for the burner.

P1649 / 99MX

Claims (22)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. Process for the partial oxidation of hydrocarbons comprising the steps of: feeding a flow of gas comprising hydrocarbon to a reaction chamber; - feeding a gas flow comprising free oxygen into the reaction chamber; characterized in that it further comprises the steps of: mixing and reacting a first portion of the gas flow comprising free oxygen with a first flow comprising reacted gases circulating within the reaction chamber; mixing a second portion of the flow of gas comprising free oxygen with the flow of gas comprising hydrocarbon in the reaction chamber, obtaining a gas flow comprising both hydrocarbons and free oxygen at least partially mixed together; mixing and reacting the gas flow comprising the two hydrocarbons and the free oxygen at least partially with each other with a second flow comprising reacted gases circulating within the reaction chamber, obtaining P1649 / 99MX a gas flow comprising carbon monoxide and hydrogen. The process according to claim 1, characterized in that the flow of gas comprising hydrocarbon and the flow of gas comprising free oxygen are fed into the reaction chamber as respective substantially annular jets, coaxial to each other. 3. The process according to claim 2, characterized in that the gas flow comprising hydrocarbons is flowed out of the gas flow comprising free oxygen and, preferably, at a higher velocity. The process according to claim 1, characterized in that the second portion of the gas flow comprising free oxygen comprises between 10 to 90% of the flow. The process according to claim 1, characterized in that the velocity of the gas flow comprising hydrocarbon fed to the reaction chamber is in the range of 30 to 300 m / s, preferably 60 to 180 m / s and that the speed of the gas flow comprising free oxygen fed into the reaction chamber is in the range of 10 to 100 m / s, preferably 20 to 60 m / s. The process according to claim 2, characterized in that it further comprises the steps of: making the gas flow comprising P1649 / 99MX free oxygen flows through a first essentially cylindrical conduit of a predetermined length of a burner that extends into the reaction chamber; - causing the flow of gas comprising hydrocarbon to flow through a substantially annular free space defined between the first conduit and a second external conduit coaxial with the first, the second conduit is longer than the first conduit and within it defines a the reaction chamber, between one end of the second conduit and one end of the first conduit, a mixing zone for the hydrocarbon, comprising gas flow and gas flow comprising oxygen; - directing the gas flow comprising hydrocarbon from the essentially annular free space towards a region of the mixing zone near an internal wall of the second conduit; expanding and directing the flow of gas comprising free oxygen leaving the first conduit to the inner wall of the second conduit in the mixing zone, thereby mixing and reacting a first portion of the gas flow comprising free oxygen with a first flow that comprises reacted gases circulating within the reaction chamber in a central zone thereof, and mixing a second portion of the gas flow comprising free oxygen with the gas flow comprising P1649 / 99 X hydrocarbons obtaining a gas flow comprising both hydrocarbons and free oxygen in at least one partially mixed form. The process according to claim 2, characterized in that it further comprises the steps of: causing the flow of gas comprising free oxygen to flow through a first essentially cylindrical conduit of a predetermined length of a burner extending towards the chamber of reaction; causing the flow of gas comprising hydrocarbon to flow through a substantially annular free space defined between the first conduit and a second external conduit coaxial with the first; - causing the gas flow to comprise steam and / or inert gases to flow through a substantially annular free space defined between the second conduit and a third conduit coaxial with the second conduit; feeding the gas flow comprising steam and / or inert gases into the reaction chamber as a substantially annular jet defining a mixing zone on its interior, for said gas flow comprising hydrogen and for said gas flow comprising oxygen free; direct the flow of gas comprising hydrocarbon from free space essentially P1649 / 99MX annular to a region of the mixing zone near the substantially annular gas flow stream comprising steam and / or inert gases; expanding and directing the flow of gas comprising free oxygen leaving the first conduit to the substantially annular jet of gas flow comprising vapor and / or inert gases in the mixing zone, thereby mixing and reacting a first portion of the flow gas comprising free oxygen with a first flow comprising reacted gases circulating within the reaction chamber in a central zone thereof, and mixing a second portion of the flow of gas comprising free oxygen with the flow of gas comprising hydrocarbons obtaining a gas flow comprising both hydrocarbons and free oxygen in at least one partially mixed form. The process according to claims 6 and 7, characterized in that the gas flow comprising free oxygen is flowed through the first conduit along a spiral flow path. The process according to claims 6 and 7, characterized in that the second portion of the gas flow comprising free oxygen is brought into contact with the flow of gas comprising hydrocarbon from the first end of the conduit in the interior. P1649 / 99MX 10. A burner for the partial oxidation of hydrocarbons comprising: a first essentially cylindrical conduit of a predetermined length defining, within it, a circular passage for feeding a gas flow comprising free oxygen to a reaction chamber outside the burner; a second conduit, outside the first conduit and coaxial with it but not of greater length, which defines a substantially annular free space on its interior between the conduits, for feeding a gas flow comprising hydrocarbon to the reaction chamber; characterized in that it further comprises: - a mixing zone, wherein the gas flow comprising hydrocarbon is mixed with the flow of gas comprising free oxygen defined within the respective ends of the first and second conduits; - means for directing the flow of gas comprising hydrocarbon from the substantially annular free space to a region of the mixing zone near an internal wall of the second conduit; - means for expanding and directing the entire flow of gas comprising free oxygen leaving the first conduit to the inner wall of the second conduit in the mixing zone, in order to mix and P1649 / 99MX reacting a first portion of the gas flow comprising free oxygen with a first flow comprising the reacted gases circulating within the reaction chamber in a central zone thereof, and for mixing a second portion of the flow of gas comprising free oxygen with the gas flow comprising hydrocarbon obtaining a gas flow comprising both hydrocarbons and free oxygen, at least partially mixed. 11. A burner for the partial oxidation of hydrocarbons comprising: a first essentially cylindrical conduit of a predetermined length defining, within it, a circular passage for feeding a gas flow comprising free oxygen to a reaction chamber outside the burner; a second outer and coaxial conduit with respect to the first conduit, defining a substantially annular free space on its interior between the conduits, for feeding a gas flow comprising hydrocarbon to the reaction chamber; characterized in that it further comprises: a third external and coaxial conduit with respect to the second conduit, which defines a substantially annular free space on its interior between the second and third conduits for feeding a gas flow comprising steam and / or inert gases towards the chamber of reaction; P1649 / 99MX means to expand and direct the entire flow of gas comprising free oxygen leaving the first conduit to the gas flow comprising hydrocarbon and leaving the second conduit, to thereby mix and react a first portion of the gas flow comprising free oxygen with a first flow comprising the reacted gases circulating within the reaction chamber in a central zone thereof, and to mix a second portion of the gas flow comprising free oxygen with the flow of gas comprising hydrocarbon obtaining a gas flow comprising both hydrocarbons and free oxygen, at least partially mixed. A burner according to claim 10, characterized in that the means for directing the flow of gas comprising hydrocarbon comprises an annular opening thinner than the annular free space defined near the end of the first conduit, between the free space and the mixing zone. . A burner according to claims 10 and 11, characterized in that the means for expanding and directing the flow of gas comprising free oxygen comprises, close to the end of the first conduit, a portion of the latter that is flared towards the inner wall. of the second conduit, in order to define, at that end, a P1649 / 99MX gas outlet opening having a larger diameter than the rest of the first conduit. A burner according to claim 13, characterized in that the diameter of the gas outlet opening is 1.25 and 10 times the diameter of the first conduit upstream of said portion, and preferably 2 to 4 times. A burner according to claim 13, characterized in that the flared portion of the first duct is curved. A burner according to claim 12, characterized in that the flared portion extends continuously from an internal wall of the duct towards an external wall thereof, at a constant dependent angle between a cylindrical end of the inner wall and an end of the outer wall , or alternatively to a dependent angle that varies continuously from 0 ° at the cylindrical end of the inner wall to at most 90 ° at the end of the outer wall. A burner according to claim 16, characterized in that the angle dependent on the flared portion is in the range of 30 ° to 90 °, preferably 45 ° to 80 °. A burner according to claim 10, characterized in that the length of the internal wall of the second conduit in the mixing zone is 5 to 15 times the thickness of the annular opening between the P1649 / 99MX first and second conduits. A burner according to claim 10, characterized in that the inner wall of the second conduit in the mixing zone has a frusto-conical shape that increases in diameter towards the end thereof. A burner according to claim 10, characterized in that the slope angle of the inner wall of the second duct in the mixing zone is in the range of 0 ° to 60 °, preferably 10 ° to 30 °, from longitudinal axis . A burner according to claims 10 and 11, characterized in that it comprises an additional conduit, internal to the first conduit and coaxial with it, being shorter than this one, defining within it a passage for introducing part of the gas flow comprising free oxygen along a purely axial flow path towards the reaction chamber. 22. A burner according to claim 21, for preheating the reaction chamber of a gas generator, the internal conduit is used to introduce a flow comprising fuel to the reaction chamber. P1649 / 99MX