MXPA06003747A - Combustion method and apparatus for carrying out same - Google Patents

Abstract

The invention relates to recirculation flow combustors having a generally curved recirculation chamber and unobstructed flow along the periphery of the boundary layer of the vortex flow in this chamber, and methods of operating such combustors. Such combustors further have a border interface area of low turbulence between the vortex flow and the main flow in the combustor, in which chemical reactions take place which are highly advantageous to the combustion process, and which promote a thermal nozzle effect within the combustor. A combustor of this type may be used for burning lean and super-lean fuel and air mixtures for use in gas turbine engines, jet and rocket engines and thermal plants such as boilers, heat exchanges plants, chemical reactors, and the like. The apparatus and methods of the invention may also be operated under conditions that favor fuel reformation rather than combustion, where such a reaction is desired.

Description

APPARATUS AND COMBUSTION METHOD BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The invention relates to a combustion apparatus and method for burning fuel in a mixture with air for the purpose of producing hot gas for various applications. More specifically, the invention relates to a combustion apparatus and method using a combustor with recirculation flow. The invention further relates to an apparatus and method for igniting and burning a mixture of fuel and air. A combustor of this type can be used to burn lean and super lean fuel and air mixtures for use in gas engine machines, jet engines and oscillating engines and thermal plants such as heaters, heat exchange plants, chemical reactors and the similar ones. The apparatus and methods of the invention can also be operated under conditions that favor fuel reformation in addition to combustion, where said reaction is desired.

PRIOR ART In a typical combustor, the combustion air and fuel (which can or can not be pre-mixed) is introduced through an inlet opening to a combustion space, where the combustion process occurs. The recirculation flow may be present, in which the combustion gases are re-circulated within the combustor before being re-united in the main combustion flow. The introduction at high speed, high temperature, large mass of recirculating flow injects thermal and kinetic energy into the main combustion flow, furthermore allows stable combustion of lean / lean air / fuel mixtures and decreases harmful emissions among other advantages .

Although the flow of re-circulation is present in many methods and combustion apparatuses, the flow of re-circulation in the existing combustors occurs within the combustion space being confined to a special space for an organized movement. As a result, existing combustors do not maximize the speed of the re-circulation flow and also do not maximize the amount of thermal and kinetic energy injected into the main combustion flow, which could be desirable for efficient and reliable combustion air / fuel lean and very lean.

For example, US Patent No. 4,586,328 to Howaid discloses a combustor in the form of a toroid generally in which the combustion mixture is burned along a generally helical-toroidal gas flow path. However, the re-circulation flow (burning gas) that is fed back into the inlet opening zone within the combustion chamber does not have a speed that is sufficiently high, low energy is supplied to the mixture here. fresh air / fuel. The output of the periphery of the toroidal flow path is in the motor. In addition, in Howaid, additional cooling fluxes are introduced between the air flow and the recirculated burner gas flow. Consequently, the conditions for the injection of the combustion gases in the air flow or in the air / fuel mixture flow are deteriorated and the amount of energy supplied by the re-circulation flow to the air / fuel mixture is low. The solution is to make the air / fuel mixture richer, which is undesirable because it results in a higher combustion temperature, incomplete combustion and increased harmful emissions.

U.S. Patent No. 3,309,866 to Kydd discloses a process and apparatus for the combustion of flameless gas in which re-circulation occurs (i.e., hot, substantially, completely burned gas within the combustor is combined with the air mixture). /combustibl.e entering the combustor). Like Howaid, the combustor described by Kydd does not maximize the speed of the re-circulation flow, further resulting in a low level of energy being supplied to the main combustion flow. As in Howaid, the flow next to the periphery of the toroidal circulation area also feeds the motor. In addition, the Kydd combustor includes an amplifier in the form of an annular plate with holes so that the combustion gases do not flow directly into the fresh air / fuel mixture, thus damaging the conditions for the injection of the exhaust gases. burned in the fuel mixture. The main disadvantage is the complete mixing, with the fuel and the admitted air mixture and the complete mixing with almost completely burnt gases that are in a rotating motion.

In US Patent No. 5,857,339 to Roquemore et al., A vortex combustor trapped with hot gas re-circulation for the main flow inlet has inlets for air and fuel to admit the fuel and / or air for the hot gases re-circulated before the hot gases join the main flow. Similar to other known combustors, the temperature of the hot gases recirculated to the fresh fuel and the air mixture decreases rapidly due, among other things, to the intense fuel reforming processes that occur in the fresh fuel and the mixture of air. In this case, adding air and / or fuel to the re-circulated hot gases is counterproductive because the temperature of the re-circulated hot gases will almost decrease before it finds the main flow. The geometry of the combustion space is such that the re-circulated hot gases join the main flow as closely as possible to a co-existing flow. This means that the primary objective is to achieve the lowest possible hydraulic losses when the re-circulated flow meets the incoming main flow. This mixing geometry of two flows is very disadvantageous, because the "soft" conditions in collision of two flows results in a poor transfer of energy between the flows and non-uniformity or temperatures in the main flow input can reach more than 100% and the inner layers of the main stream that enters can not be fully heated. This results in poor heating of the main flow entering with the engine failure. A typical temperature profile for combustors of this type (see Figure 19) shows that the temperature of the main flow entering a vortex combustor trapped at the combustion space inlet remains virtually the same as the main flow temperature fed to the combustor. The consequence of this is the high non-uniformity of the combustion temperature axially to the long and radially of the combustor that moves in the stability of the flame when the fuel and the air mixture reaches more lean and also high for NOx emissions and CO. It should be added that the use of additional air and / or fuel inputs in the re-circulation flow path is very disadvantageous because they create non-uniformity of the velocity profile within the re-circulation flow, which results in non-uniformity Increased energy transfer between the hot gases re-circulated and the main flow that enters.

In US Patent No. 6,295,801 to Burus et al., A combustor uses the principle of vortex operation to sustain a pilot flame. This design has the disadvantages of those described above. The main advantage of this trapped vortex design is the stability of the pilot's flame. This is done because the stability of the main flame could not be achieved in the prior art without using additional devices. The vortex velocity can not be the same for the input flow velocity. The air is fed to the vortex area through the ports that have a speed coefficient of approximately 0.75. The main air flow is admitted to the combustor through the profiled passages that have a speed coefficient of approximately 0.9. With an ideal isentropic velocity of 100 m / s, the velocity of the main air flow will be 90 m / s and the vortex velocity will be 75 m / s. The velocity of the flow fed to the vortex could be increased with the differential available pressure before feeding the air to the vortex or the differential pressure can be increased. It should be noted, however, that the temperature of the fluid admitted to the vortex should not be below the gas temperature in the vortex, that is, the combustion products should be added to the vortex. The main flow suffers from sudden expansion, which results in a decrease in speed. In general, the turbulent character of the vortex flow results in a decrease in velocity. All these factors will not allow additional energy to be supplied to the main flow that enters.

It should be summarized that the use of vortex in the combustors in the prior art is characterized mainly by heating the surface layers of the main incoming stream, which by itself is not bad and can provide certain improvements in the lean mixture of the flame . On the other hand, surface heating can not result in any dramatic improvement in the stability of the flame and the reduction of emissions.

In these combustors of the re-circulation flow of the prior art, the flow of re-circulation of hot gases is diluted (cooled) with a secondary air flow and subsequently the cooled re-circulated gases are directed to the primary air of the inlet, that should be heated. (See Figure 20). Fuel is added to the hot gases re-circulated with the secondary airflow before it joins the primary (main) air flow. The admission of fuel for the re-circulated hot gas results in very non-uniform conditions for combustion because a very small amount of fuel can not be completely mixed with a large amount of re-circulated gases and secondary air. The reforming of the fuel will be very intense and not uniform in the case with the assurance of cooling. The fuel is subsequently burned and the temperature of the gases increases, but this increase will be partially used to compensate for the reduction of the temperature of the fuel reformation. The flow is then attached to the primary (main) air flow (which is really a secondary flow because the mixture is already burning) and again it cools. The main flow can not be heated at the inlet because the re-circulated hot gases have already been cooled twice (first, with the secondary air flow and second, by the admission of the fuel) and the heating of the re-circulation flow through the fuel, the burning has been partially spent to compensate for the losses of re-formation temperature. It is not possible to heat the main flow in the uniformity of the inlet over the entire cross section because the result depends entirely on the turbulent mixing of two flows, which can not ensure uniform mixing throughout the entire volume. This depends on how questionable the turbulence (mechanical mixing) is, because the two flows move practically concurrently.

The temperature in the re-circulation flow in all the above described combustors can not be higher than the TIT (turbine inlet temperature), (see Figure 21). The preferred temperature in the re-circulation flow based on the exchange of NOx and CO emissions is 1100-1200 ° C. Adding air and / or fuel to the re-circulated hot gases results in a reduction in the re-circulation gas temperature. There are two main consequences of this. First, CO emissions will increase. Second, most combustion products will have to be added to the inflow to increase the temperature of the inflow, which causes an increase in the re-formation of the fuel, in addition to lowering the temperature. Therefore, the use of trapped vortex and the re-circulated flow in the prior art combustors, while providing some improvement in the stability of the flame and the operation of the emission, is not possible in any breakage.

U.S. Patent No. 5,266,024 to Anderson discloses the use of a thermal nozzle to increase the kinetic energy of an oxidant stream for a blow torch by supplying heat to the flow.

US Patent No. 1, 952,281 to Ranque describes the phenomenon and apparatus for creating the phenomenon, whereby in a vortex tube having a tangential inflow of compressed flow, the heat is transferred between the layers of rotation of the fluid in the vortex tube, resulting in a separation of the rotating fluid in a hot exhaust flow and a warm internal flow, which can be taken from separate outlets.

SUMMARY OF THE INVENTION The present invention relates to recirculation flow combustors having a generally curved recirculation chamber and unobstructed flow along the periphery of the vortex flow boundary layer of this chamber. Said combustors have a boundary interface area of low turbulence between the vortex flow and the main flow in the combustor in which the chemical reactions are carried out, which are highly advantageous for the combustion process and which promote an effect of thermal nozzle inside the combustor. A combustor of this type can be used for the burning of very lean and lean fuel and air mixtures for use in gas turbine engines, jet and oscillating engines and thermal plants such as heaters, heat exchange plants, chemical reactors and the similar ones. The apparatus and methods of the invention are also operated under conditions that favor fuel re-formation than combustion, where a reaction is desired.

More particularly, the invention provides a combustor comprising a reactor, an inlet for admitting a main flow to said reactor, an outlet for discharging the hot fluid from said reactor, said reactor positioned between said inlet and said outlet and comprising a flow zone The main flow, through which a majority of said main flow passes along a main flow path and a recirculation zone, through which a lower portion of said main flow passes, wherein said main flow of re-circulation is defined in part by a wall having an inner surface curved in one direction in a substantially continuous manner and running from a withdrawal point near the exit for a return point proximate said entrance, said inner surface being shaped and positioned with respect to said main flow path in said manner as a distinct part of the fluid in said main flow path, in said withdrawal point to form a re-circulation vortex flow in said re-circulation zone during the operation of said reactor and wherein said inner surface is further characterized by a lack of discontinuities so as to cause substantially quiet movement of a boundary layer along the periphery of said re-circulation vortex flow. Therefore, a thermal nozzle effect results from the chemical reactions that take place within the boundary or "interface" layer between said re-circulation flow and the main, linear flow of the fluid in the reactor.

The invention further provides methods for reacting the fuel in a combustor as described above, comprising the steps of: passing the majority of said main flow in a route together with said main flow area, passing a lower portion of said flow in a route through said re-circulation zone, so as to form a re-circulation vortex flow that returns a portion of the fluid in said recirculation zone to an area close to said inlet, causing a boundary layer of recirculating fluid to flow around said inner wall surface of said recirculation zone without substantial turbulence, causing the peripheral portion of said recirculating vortex flow to intercept said main flow in an area near said inlet, wherein said peripheral flow has a higher velocity than said main flow; said peripheral flow and said main flow by thermal diffusion and not by substantial mechanical mixing, therefore forming an interface layer between said main flow and said peripheral flow and causing a substantial transfer of heat energy from the fluid in said peripheral flow through of said interface layer and in the fluid in said flow zone.

The implementation of the invention will be more apparent from a review of the accompanying drawings and from the description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows schematically the interface between a fuel flow and the air mixture and a re-circulation vortex flow in a combustor according to the invention.

Figure 1A schematically shows the part of the interface layer between the re-circulation vortex flow and the incoming fuel and the air mixing stream, in which the symbol X represents "hot" CO molecules in the layer peripheral of the recirculation vortex flow.

Figure 2 is a table showing the CH4, T and CO against the contact time between the re-circulation vortex flow and the fuel and ion of the air mixture flow of the combustor according to the invention.

Figure 3 is a table showing the NO emission levels against the combustion temperature.

Figure 4 shows the temperature in the fuel and the air mixture flow against the V2 / Vt ratio.

Figure 5 shows the concentrations of CO and CH (%) against the combustion time.

Figure 6 is a sectional view of a combustor according to the invention as applied to a burner.

Figure 7 is a view partly in section along the arrow VII in Figure 6.

Figure 8 is a schematic partial sectional view of an annular combustor according to the invention.

Figure 9 is a longitudinal sectional view of another embodiment of an annular combustor designed along the lines of Figure 8.

Figure 10 is a mode of the combustor shown in Figure 8.

Figure 11 is a schematic longitudinal sectional view of a combustor canister according to the invention.

Figure 12 is an end view of a combustor according to the invention observed on the inlet side, showing an embodiment of the inlet opening.

Figure 13 is another modality of the entrance opening in the view similar to that shown in Figure 12.

Figure 14 shows a longitudinal sectional view of a gas turbine engine incorporating an annular combustor according to the invention.

Figure 15 shows a longitudinal sectional view of another embodiment of a gas turbine engine incorporating an annular combustor according to the invention.

Figure 16 is a view taken along arrow XVI in Figure 16.

Figure 17 is an extended partial view of the combustor shown in Figure 15.

Figure 18 shows the level of carbon monoxide (CO) (A) against the contact time (B) for the different radii of the velocity V2 of the re-circulation vortex flow for velocity velocity) of the flow of the entrance.

Figure 19 shows a typical temperature profile for a trapped vortex combustor.

Figure 20 shows a temperature distribution in a recirculating flow combustor of the prior art, where: (C) = intermediate air (D) = primary air (E) = air dilution (F) = outlet; Figure 21 shows a predicted temperature distribution in a prior art re-circulation flow combustor.

Figure 22 shows temperature measurement points in a combustor line, where: (G) = Metallic lining.

DETAILED DESCRIPTION OF THE INVENTION The invention will now describe in greater detail and with reference to the accompanying drawings, the non-limiting exemplary embodiments of the combustor according to the invention.

As in a preliminary problem, some definitions will be provided for the purposes of understanding this application and the claims.

Flames a thin area where the chain oxidation reaction starts. Combustion a chain reaction of fuel oxidation. Inflammation (or fire, the stage of initiation of a chain oxidation reaction, as in the use of "to be burned") Flameless phenomenon of the occurrence of oxidation Combustion reactions evenly through the volume of the main flow Reactor device for the realization of the chemical reaction This specification generally uses the term "combustor" to refer to the apparatus described herein, although, as will be described, the apparatus according to the invention can be operated under conditions that favor fuel re-formation rather than combustion. The term "reactor" is sometimes used in this document as a general alternative for "combustion chamber" or "combustion space" because under some conditions, by the invention, the re-formation of the fuel may be the predominant process leading to out in it.

In addition, it should be kept in mind that combustion and / or reformation are complex chemical processes with complicated kinetics and that more than a thousand different chemical reactions will occur at various times in any given reactor. Generally, reactions within the reactor include, in addition to the direct oxidation of the fuel for carbon dioxide and water, numerous alternating and intermediate reactions including: a) Thermal decomposition of the fuel, for example CH4? C + 2H2 b) Partial oxidation of the fuel, for example. 2CH4 + 02? 2CO + 4H2 (Methane is given as the most elementary example, with different corresponding reactions taking place with other fuels). These reactions occur in particular where the temperatures are lower than the temperatures in the prior art combustors, and without using a catalyst. In addition, it is also observed (for example): c) Fuel reformation, C + C02? CO + CO (Oxidation - Reduction) d) Fuel combustion, C + 02 - »C02 (Oxidation) e) Fuel Reform H2 + C02? H20 + CO (Oxidation - Reduction) f) Fuel combustion, 2C0 + 02 - 2C02 (oxidation) g) Fuel combustion, H2 + 02? H20 (Oxidation) h) Fuel reforming, C + H20? H2 + CO (Oxidation -Reduction) Also note that the reforming of fuel and combustion are both sometimes characterized herein as a type of chemical reaction, which are oxidation-reduction and an oxidation reaction. This is because in each case "all" the reaction products (H20 and CO) are being formed by an oxidation process. Of course, it is understood that during the reforming of the fuel there are also the "cold" reaction products (CO) which are formed by a reduction reaction.

Now returning to the drawings of Figures 6 and 7, there are two views of one embodiment of the invention. This embodiment provides a combustor 10 having a combustion space or reactor 16 between an inlet 18 for admitting a main flow of fluid to the combustion space and an outlet 20 for discharging the heated fluid from the combustion space, said combustion space comprising a main flow zone, through which a majority of the main flow passes along a main flow path and a recirculation zone, through which a lower portion of the main flow passes along a route . The recirculation zone is defined in part by a wall having an interior surface 21 curved in one direction in a substantially continuous manner, positioned with respect to the main flow of the fluid and the main flow path and shaped in such a manner as to cause the flow a vortex of recirculation of a part of the fluid in the main flow path at a withdrawal point that is returned from the point of withdrawal near the exit for a point of return near the entrance before the fluid is discharged from the space of combustion and furthermore placed without any discontinuity, so as to cause a substantially quiet movement of the boundary layer along the periphery of said recirculation vortex flow.

Preferably, the volume of the recirculation zone is not less than the volume of the main flow zone when the reactor 16 functions as a combustion chamber. However, when the reactor 16 functions as a reformer, which will be described later, the volume of the recirculation zone is preferably not less than the double volume of the main flow zone.

As will be further described, a thermal nozzle effect results from the chemical reactions that are carried out within the edge of the "interface" layer between said recirculation vortex flow and the main linear flow of the fluid in the reactor 16.

The combustor according to the invention provides a recirculation vortex flow. At the interface between the flow in this vortex and the main flow in the main flow area is an "interface" or "boundary" layer. There is also a periphery or boundary layer between the wall of the recirculation zone and the vortex flow, whose boundary layer has a substantially laminar flow. More particularly, the boundary layer has a degree of turbulence of less than 0.2 (preferably between 0.008-0.01).

The quiet recirculation flow in the boundary and periphery layers provides the following advantages: The vortex layers are not substantially mixed radially within the vortex, which allows retaining the distribution profile of the hot gas molecules in the vortex, with the "hot" molecules of primary CO, C02 and H20 moving to the periphery of the recirculation flow vortex and the CO burned there and the "cold" molecules of the fuel reformation and dissociation products, the CO, H2 secondary and oxygen moving from the periphery to the center of the vortex where they participate in the oxidation reactions within the vortex. This separation occurs as a result of inert diffusion in the centrifugal field of forces. As a result, the interface or intersection between the recirculation vortex flow and the incoming main flow of the fluid will be at the highest possible temperature and the vortex will always have a supply of fuel material without any mixing of the layers.

The velocity of the anterior vortex for its peripheral layer is greater than the velocity of the incoming main flow of the fluid due to the thermal nozzle effect and also due to a very low degree of turbulence of the recirculation flow (which is achieved by providing the circular surface placed to ensure natural flow and ensure calm flow along this surface).

The presence of the periphery and boundary layers allows the combustion of the fuel to be completed within approximately 2 ms or less.

A reforming reaction is carried out together with the peripheral vortex layer, involving C02 and the reaction of C to form 2CO. Although initially formed as a "cold" and "hot" CO molecule, over time this layer rejoins the main flow in the inlet area if it has been heated substantially due, among other factors, to contact with the chamber wall. This flow of peripheral vortex or hot CO, which serves as a fuel is extremely advantageous when properly mixed with the incoming fuel and the air mixture at the inlet, as will be described later.

The ratio of the recirculation flow to the main (linear) flow in the combustor may vary. The proportion of fluid entering the vortex compared to the fluid leaving the combustor at the outlet is preferably not less than seven percent (7%) in the operating mode in which the reactor functions as a combustion chamber and does not less than ten percent (10%) in the mode of operation in which the reactor functions as a reformer.

As described above, a fluid flow or a boundary layer is formed along the periphery of the recirculation zone. To maintain this flow of a desirable depth, the surface of this chamber should be curved, keeping curved in one direction (ie, not returning and so forth) in a substantially continuous manner. This depth of the boundary layer will be approximately 1 mm when the fluid in the outlet has a temperature of approximately 1100 degrees C and approximately 2 mm when the fluid in the outlet has a temperature of approximately 800 degrees C and much deeper in the lower temperatures , that is 380-420 degrees C for the point where the boundary layer will have a depth greater than the diameter of the central core of the recirculating fluid in the recirculating vortex flow.

As a result, the following conditions are obtained at an intersection point or area near the entrance where the periphery of the vortex joins the incoming main flow of fluid that is admitted to the combustion space, the higher temperature is at the interface of the two flows and there is a relative high velocity between the two flows that move in the same direction following the intersection flow. The result of these two conditions is the highly intensive transfer of heat from the periphery of the vortex to the interconfrontation surface of the incoming main flow, characterized by a very high heat transfer rate due to the aforementioned conditions. Therefore, the vortex can transfer heat energy to the face-to-face layer of the incoming main flow in the most efficient manner. For this reason, the surface layer of the main inlet flow burns and is immediately ignited inconsiderately from the fuel / air ratio, acting as the pilot's flame without, however, an appreciable turbulent mixture between the two flows that would result in information from "hot" and "cold" sites averaging temperatures and other unwanted phenomena inherent in most modes of previous trapped vortex combustors. It should be noted that as the result of inert diffusion, the burned fuels reach the surface layer of the incoming stream first and the "cold" molecules leave the central part of the vortex, further providing conditions for a chain reaction, ie the oxidation in proportions commensurable with the combustion rates and the proportion of combustion can also be increased with an additional increase in the proportion of the vortex velocity for the incoming flow velocity, further leading to controlled explosive combustion with much more lean than that used in conventional combusers (ke of approximately 0.5). This phenomenon results in a sudden increase in the temperature of the incoming flow and as a consequence of this, for the rapid and uniform heating through the entire body of the inflow into the very intake of the combustion space with the result that the kinetic energy or speed the incoming flow begins to increase from the inlet area and this increase continues to the exit area, further providing the thermal nozzle effect that provides an impulse to the recirculation vortex flow to move at a higher velocity. It should also be noted that rapid heating through the inflow occurs without mechanical (turbulent) mixing of! vortex recirculation flow and incoming fluid flow using only the mechanism described above.

The use of the thermal nozzle phenomenon in the combustor according to the invention allows the increase of the speed of the fluid flow through the outlet from the combustion space while almost completely eliminating the turbulent mixing of the recirculation flow (vortex) with the main body of the fluid flow through the combustion space. The losses in the combustion space are therefore substantially reduced. The use of a circular surface to create the thermal nozzle effect, with the circular surface do not have any disturbing element of the flow such as openings, recesses, protuberances, fluid inlets and the like, ensures the redistribution of the gas molecules in the Recirculating vortex flow, inter alia, by virtue of the aforementioned inert diffusion and rapid heating of the incoming fluid flow body combined with a stable high temperature interface between the two floors. The absence of mixing, which could involve the formation of "hot" and cold spots "ensures the minimum levels of NOx formation, since the combustion products do not mix with the incoming fluid due to turbulence (mechanical mixing), the incoming fuel and the air mixture, which can be very lean, does not become leaner because the combustion gases and the air / fuel mixture move concurrently (in the same direction at different speeds) without their mechanical mixing . This advantage allows the combustion of very lean mixtures to be maintained at any temperature at which the oxidation of the hydrocarbon fuel is theoretically possible.

The combustion temperature of a hydrocarbon fuel can be below 500 ° C with the exhaust gas temperature of the combustor as low as 350-330 ° C. This is the oxidation temperature, so that the C02 and the ratio of H20 formation should be decreased by more than 100 times if a conventional combustor design is used. However, due to the inert diffusion described above, the proportion of the relocation of newly formed CO, C02 and H20 in the area with the highest fuel content (from the center to the periphery of the vortex) and subsequently to the interface layer is several times greater than the normal combustion ratio which is about 1 m / s and the proportion of combustion of the fuel component in the combustor according to the invention is of the same order as the combustion rate in the previous combustors.

As mentioned above, no fluid (including fuel) was added to the combustion products in the recirculation flow (at least not within the main portion of the circular recirculation flow surface between the combustion space inlet and outlet ) and the degree of turbulence of the recirculation flow is very slow (below the lowest value for any conventional combustor). As a result, no particulate carbon is formed in the vortex. The favorable consequence of this is the absence of the high thermal radiation losses from the recirculation flow to the combustor wall and a relatively low temperature of the combustor wall within the area from the flow recirculation flow separation point. the combustion products that leave the combustor in the entrance area. It should be noted that the temperature of the combustor wall which rises the separation point has no substantial effect on the CO levels.

The process of heat exchange between the vortex surface and the chemically reactive fuel and the air mixture is not determined by the temperature fields only, it also depends on the chemical accumulation of the vortex and the fuel and the air mixture. There is a difference between the temperatures of two streams (the vortex temperature is higher) and a difference between their chemical composition (the vortex contains more C02 and H20 and the fresh mixture contains more fuel and oxygen). Therefore, if the two flows move in the same direction without mechanical mixing, the conditions for the diffusion processes are created, more specifically for thermal diffusion and concentration diffusion. The barometric diffusion is insignificant and could be important only in the transition for a controlled explosive combustion.

The ratio between thermal diffusion and concentration diffusion varies during the operation of the combustor, however, the concentration diffusion will always predominate in the heat exchange between the vortex and the fuel and the air mixture. The diffusion of concentration really has a decisive effect on the intensity of the heat exchange process. It is problematic to check the actual concentration gradient during heat exchange if chemical reactions should be factored into it. It should be noted that a change in the concentration of CH4 (or other fuel) and 02 in the inter-confrontation layers of the vortex flow and the fuel and air flow influences not only the thermal energy transfer process, but also the reaction direction (direct and inverted). If, for example, the CH4 concentration in the fuel and the air mixture increases (as a result of a coefficient of increase of equivalence compared to the value of the point of establishment of the design), the fuel reforming processes will start prevailing in the interface layers. This, in combination with specific oxygen supply for the vortex, will result in the temperature decrease of the periphery of the vortex and as a consequence, the temperature of the molecules that reaches the central part of the vortex will also decrease. Both processes, which occur simultaneously, would result in a decrease in vortex temperature to a sub-critical value resulting in a flame extinction. This is because the problem of stable combustion of a lean mixture could not be solved by simple mechanical mixing of the vortex flow and the fuel and air mixture flow as has been done before because the supply of thermal energy to the fuel and the air mixture in which case it is accompanied by a concurrent increase in C02 and the supply of H20 (resulting in enhanced fuel reformation), with a decrease in the temperature of the vortex and the fuel and air mixture. According to the invention, the diffusion process prevails between the two flows (without their mechanical mixing) and the source of thermal energy at the entrance where the flows meet (the vortex) has an increased speed with respect to the speed of the consumer of thermal energy, fuel and air mixture.

The intense vortex for the heat transfer of the air / fuel mixture initiates the effect of the thermal nozzle in the following manner. The peripheral layer of the fuel flow and the air mixture will always receive the thermal energy from the periphery of the vortex at a high rate of heat transfer as well as the "hot" molecules of C02, CO and H20. In addition the conditions of burning the periphery of the fuel and the air flow and sustaining the combustion of this layer are provided. As soon as this peripheral layer ignites, the combustion propagates at a very high velocity although the whole body of the fuel and the air flow and the velocity of the flow starts rising under the effect of thermal nozzle. As a result, the kinetic energy of the fuel and the air flow increase. The stable burning (stable flame) of the fuel and the peripheral layer of the air flow is ensured not only by the high temperature of the vortex flow and the high proportion of heat transfer from the periphery of the vortex to the fuel and the periphery of the air flow that forms a kind of a "pilot flame". The sufficient and continuous supply of the C02, CO and H20 molecules for this layer of "pilot flame" sustains the flame under any transient, with the minimum proportions of fuel to air and under sudden fluctuations of the fuel supply.

The fuel and oxygen molecules move in opposition to the "hot" molecules that move from the vortex in the fuel and the air mixture by diffusion. This is the diffusion of concentration. The nitrogen molecules diffuse from the vortex in the fuel and the air mixture in a very small amount (thermal diffusion) and the nitrogen for the most part that does not move from the fuel and the air mixture in the vortex because the concentrations of nitrogen in the vortex and the fuel and the air mixture are substantially equal. A part of the fuel that arrives in the interphase layer between the vortex and the flow and the fuel and the air flow is burned, since the main part of the fuel in that layer is reforming. The primary ("hot") CO molecules as well as the hydrogen part remain in the interface layer.

Some molecules that remain are oxidized by C02 and H20 that returns to the fuel and air mixture. The main part of the CO molecules ("hot") and the return of hydrogen to the fuel and the mixture of air in the form of CO and H2. They form the "striking force" of the vortex. The "cold" molecules (obtained as a result of reformation), so called secondary CO, H2 as well as oxygen, will move to the center of the vortex (they have lower inertia due to a lower thermal movement speed). Not all of them will be made to the center. A part of them will be oxidized by C02 and H20 on their way to the center, which will return by centrifugal forces to the periphery of the vortex (by diffusion of inertia) and so on.

The process illustrated in Figures 1 and 1A in which the dots represent the molecules of CO, C02, H20 and H2"hot" and the plus signs represent the "cold" fuel molecules and oxygen. The arrows show the directions of the movement of the molecule as described above and the point at which the recirculation vortex flow and the incoming fuel are joined and the flow of the air mixture is shown at "O".

A partial, schematic, prolonged view of the interphase layer between the recirculation vortex flow and the incoming fuel and the flow of the air mixture is shown in Figure 1A. The symbols "X" represent CO formed by reformation, carried in the peripheral layer of the vortex. The figure shows the diffusion of CO in the incoming fuel and the air mixture in the entrance area, greatly helping combustion. As should be understood, although the velocity V2 of the recirculation vortex flow is greater than that of the incoming fuel and the flow of the air mixture V1, the velocity V3 of the peripheral layer of the recirculation vortex flow is much lower than that of the fuel incoming and air mixing flow (there is a velocity gradient from the surface and the average velocity in this layer is in the range of about 1/5 of V1).

The processes that occur in the interface layer are illustrated in the table in Figure 2. It can be seen that the fuel level (CH4) falls over time, but the temperature remains almost unchanged (if it does not increase as it normally should in conventional combusers) because the intensive fuel reformation is being carried out with the formation of both "hot" and "cold" CO molecules. The temperature T starts rising approximately after a lapse of approximately 2/3 of the contact time or in this mode approximately 0.7 to 0.8 ms after the two flows are joined.

The presently preferred way to carry out the combustion method according to the invention is to have a combustor designed to meet the following proportions of dimension: a > 1.4 b d = 2.2 b 2r + b = c = r + b where: r is the radius of the circular surface (see Figure 6); a is the distance between the entrance and the exit of the combustion space; b is the height of the entry section; c is the maximum dimension of the combustion space in the direction of the radius r; d is the height of the exit section.

If d is greater than 2.2 b, the cross-sectional area of the thermal nozzle will be very large and the desired fuel and the velocity of the air flow imparting the initial impulse in the vortex will be achieved. If c is greater than 2r + b, the cross-sectional area will be very large, the desired fuel and the velocity of the air flow will not be achieved, its effect on the vortex will be reduced, and the velocity of the vortex in the area of its Filter with the fuel and the air flow will be very low. Preferably, the cross sectional area of the outlet is not more than 2.2 times the cross sectional area of the entrance. When it is desired to change in the operation mode in which the reactor functions as a reformer, the cross-sectional area of the inlet is reduced relative to the cross-sectional area of the inlet used in the operation mode to which the reactor functions as a combustion chamber.

The dimension a determines the vortex and the fuel and the contact time of the air flow. Preferably, this time should be greater than about 1 ms. The dimension a can be obtained based on the speed of the entrance of the fluid at the entrance, preferably from 10 to 20 m / s.

When the fresh fuel and the air mixture are heated (with the temperature rise of approximately 150 ° C), which is normally carried out when the mixture is heated with hot gases re-circulated in a conventional combustor before burning, There is normally a non-uniformity of the temperature profile inside the fuel and the air flow. The non-uniformity of the temperature can be as great as 100%, which mediates the individual jets of the flow that can remain practically at the same temperature as the temperature of the air flow before entering the combustor. The non-uniformity of the temperature will be approximately the same at the end of the fuel combustion. If the exit temperature of the combustor should be about 1200 ° C, the temperatures within the flow can be as high as 1500 ° C due to the aforementioned non-uniformity. While levels of N02 at 1200 ° C may be acceptable, nitrous oxide emissions at high temperature are substantially higher. This is illustrated in Figure 3, where Curve I shows the nitrous oxide emissions for a hotter layer of the fuel air mixture and Curve II shows the nitrous oxide emissions for a cooler layer of the fuel mixture. fuel air. It can be seen that N02 can be at the level of 1 ppm and 10 ppm and be higher in the same combustor. Curve III shows a case for the uniform temperature profile in the fuel and the heated air mixture before burning.

The attempts to eliminate the non-uniformity of the temperature by providing more hot gases for the fresh fuel and the air flow result in the fact that the part of the fuel and the air mixture that receives more hot combustion products will be heated to a lower temperature than the rest of the mixture that receives lower combustion products contrary to those expected. This is explained by the fact that excessive amounts of hot combustion products cause more intensive fuel reforming, which is the cause of temperature reduction. This phenomenon becomes more pronounced with poor mixing of fuel and air, so the flow areas with higher fuel levels will fall even lower due to the higher reforming ratios. This can be seen in Figure 4 which shows the temperature in the fuel and the flow of the air mixture against the velocity of the periphery of the vortex. It can be seen that the temperature rises in the fuel and the air flow increases until the velocity of the periphery of the vortex reaches 1.2 to 1.25 times the flow velocity of the inlet fluid, after which the point of the temperature falls and this instead of large amounts of thermal energy injected into the fluid flow of the inlet.

Therefore it will be apparent that the non-uniformity of the temperature described above remains within the fuel and the air flow above the moment of burning. When the fuel and the air mixture are burned, the colder parts will burn faster and become hotter than the part that was hottest before burning. With the periphery speeds of the vortex, which are desirable to reduce emissions, the non-uniformity of the temperature within the burning fuel and the air mixture (after burning) will become even greater due to the reforming effect described above . This is explained by the fact that the hottest parts of the fuel and the air mixture will still burn after burning the coldest part of the mixture that has been completed. The non-uniformity of the temperature at this time may be greater than about 500 ° C.

The aforementioned difference between the combustion processes is explained by the different combustion chemistry in the flow jets having different temperatures. Since the colder jets contain more combustion products, the proportion of the CO oxidation in these jets is determined by the first first-order chemical reaction equation well known to those skilled in the art: x = a-, - b ! [exp (-kt)] (1) where x is the current CO level in the combustion products (mol); a-t is the initial CO level (mol); k is the reaction kinetic constant (2.15 mol / s); b1 is the temperature coefficient t is the combustion time (s).

The hotter jets of the flow, which contain fewer combustion products, burn in accordance with a second-order chemical reaction equation, which reflects the effect of diffusion mass transfer in the combustion process in whose jets: x = a2 - b2 [exp (-kt)] + Deff [exp (-mt2)], (2) where: x, a2, b2, k and t have the same meanings as x, a ^ bi, k and t; Deff is the effective diffusion coefficient (mol / cm2 * s); m is the coefficient of non-binary collisions (cm "1 * s ~ 1).

The works of these two equations are explained with reference to Figure 5 showing the concentrations of CO and CH (%) against the combustion time. Curve 1 represents the kinetics that are described by equation (1) and it can be seen that the fuel burns quickly with a short burning time, which is good for decreasing NOx emissions with minimum CO levels at the same time. Curve II illustrates the kinetics described by equation (2) and it can be seen that the combustion process is much greater than in the case of the former, which is coupled with a higher combustion temperature, since it provides high NOx emissions and burns of very slow CO. It should be noted that Curve 11 is given with the assumption of a homogeneous fuel and the air mixture, which is an ideal case. With the fuel and air mixture obtained in the prior art combustors, the result will be much worse.

To eliminate the disadvantages of the prior art, it is necessary to raise the temperature of the main air flow in the same to the combustion zone, uniformly over the cross section of the inlet where the flow of the fluid for the combustor is admitted. It is important that the total body substantially of the inflow has received substantially the same amount of thermal energy before entering the combustion zone. If this is the case, the conditions of reformation on the total body of the fuel and the air mixture will be substantially the same.

The advantage of this method is as follows. Since the burned flow has no non-uniformity of temperature before the burning of the fuel and the air mixture, the combustion occurs substantially at the same temperature over the total body of the flow and in this case, the temperature of the design configuration point maximum output of the combustor will be, for example 1200 ° C and the temperature can not be above this level any point inside the combustor. It is known that this is the minimum N02 formation temperature and the most intense CO burning. This allows a combustor to be designed for the combustion temperature that equals the TIT when used in a gas turbine engine. The uniform temperature profile in the combustion zone ensures the absence of heat points and locally superheated combustor areas, further making the combustor cheaper and simpler to manufacture and extending the life of the combustor.

The uniformity of the temperature profile in the incoming flow allows the combustor to work well using equation (1) or equation (2). As shown in Figure 4, with the velocity of the vortex periphery of more than 1.2 times the flow velocity of the input fluid, the combustion process occurs predominantly by equation (2) with the NOx emissions at the output of the combustor and relatively low CO emissions. With the velocity ratios between 1.4 and 2, both CO and NOx emissions at the combustor outlet will be low (see Figure 5).

It is preferred that the air temperature for combustion rise by 50 ° C to 550 ° C in the inlet zone. If the CO emission requirements are not very strict, the higher temperature rise can be used, which greatly simplifies the design of the combustor. In this case, equation (2) will determine the operation of the combustor and the process will not require large quantities of re-circulated hot gases, whose low thermal load on the combustor components. If the level of CO is required to be low, then the temperature rise can be decreased, but the proportion of the peripheral velocity of vortex in the area approximates the input but outside the boundary layer for the velocity of the incoming main flow entering the The main flow area should be increased, working within the range of 1.4 to 2.2. In this case, the combustor works by equation (1) again with the lower NOx emissions and the CO levels are markedly reduced as shown by Curve 1 in Figure 5.

The proportion of the vortex periphery velocity in the area approximates the inlet but outside the boundary layer for the flow velocity of the incoming main fluid entering the main flow zone ranges from 1.4 to 2.2. As shown above, there is a relationship between this radius and the temperature rise in the flow of the inlet fluid. As can be seen in Figure 4, there are two areas, one dominated by equation (2) and the other dominated by equation (1). An area of transition approximately between the values of radius 0.8 and 1.5 are described by both equations (1) and (2), in which the NOx levels will be greater than the levels in both areas on the right and left hand and the level of CO will be higher only compared to the area on the right. This transient area will occur, for example, under transients and can be eliminated, for example, by changing the speed ratio (i.e., by changing the cross-section of the entrance or the angle ß at the separation point).

The combustor according to the invention can be made with a turbulizer placed downstream from the combustion space outlet to improve conditions for residual CO oxidation. In such a case, the combustor can be worked in accordance with equation (2) with a lower combustion temperature and still has a good CO emission operation. The same installation can be used when working in accordance with equation (1) to further reduce the CO level.

Figure 6 shows a combustor according to the invention as a burner is applied, a transverse view. As shown in Figure 7, the combustor has a prolonged design and can be made of a length required to cover, for example, a furnace wall for a boiler plant. The combustor shown at 10 has a housing defined by a wall 12 (which can also function as a liner). Wall 12 and end walls 14 (only one, right-hand wall 14 is shown in Figure 7) define a combustion space 16, in which fuel combustion takes place. The combustion space 16 has an inlet 18 and an outlet 20 spaced apart from each other and it is understood that the fluid (eg air under pressure) is admitted with a velocity V ^ for the combustion space 16 through the inlet 18 and moves through the combustion space 16 in the direction toward the outlet 20 for use in a device (not shown) positioned downwardly of the combustor 10. In accordance with the invention, the combustion space has a circular wall 21 defining a route for a recirculation vortex flow, which is separated from the fluid flow that is discharged through the outlet 20 of the combustion space 16. A part of the fluid flow is it separates from the fluid before it has been discharged from the combustion space 16 through the outlet 20 at a separation point 22 and the circular surface 21 extends between the separation point 22 and the entry area 24 within which the entrance 18 is located. The term "circular" is used in this document to mean "to have an approximate or exact or pointed form of a circle" (Webster's Third International English Dictionary, Merriam-Webster, Inc.). It is understood that the exact circle is preferred for purposes of the invention, but a shape approaching a circle such as an ellipse or the like may also be used to achieve the objects of the present invention. The fluid flow from the inlet moves through the combustion space 16 along a route shown with the O-O line. The angle α between the direction of movement of the inlet fluid flow and a portion 26 of the wall 12 at the inlet 18 or the direction of the re-circulation vortex at the inlet 18 is preferably between about 85 ° and 175 ° and It is shown as a right angle. This function of this angle will be described later. The angle ß between the direction of movement of the fluid flow from the inlet OO and the tangent plane TT for the wall 12 at the separation / withdrawal point 22 or the direction of the re-circulation vortex at the withdrawal point 22 of preference between approximately 100 ° and 15 °. The function of this angle will be explained later. The dimensions a, b, c, d and r were explained above in the description of the combustion method according to the invention.

This combustor works in the following way. Fluid such as air for combustion is admitted through the inlet opening 18, ie, from a blower or compressor and it will be understood that the air can be admitted with the already premixed fuel or the fuel can be administered independently in the flow of the fluid in the inlet (not shown). This fluid admitted through the inlet 18 moves in a general direction O-O to the outlet 20 from the combustion space 16 and the initial velocity of this fluid flow is Vi. The fuel is burned by means of a burner (not shown and which can be installed, for example rising from the inlet 18 or within the combustion space 16) and initiating burning within the combustion space 16, resulting in the formation of hot combustion products, which are discharged through the outlet 20, ie to be used in a heater or any other heat exchange device.

Preferably, the burner could not be placed within the re-circulation vortex, to avoid interference with the flow in that area. In a can combustor mode, the crossfire tubes can be connected at a point where it can go beyond the recirculation area, or before the recirculation area (but not within the recirculation area as is sometimes the case). practice conventionally). Alternatively, the burner may even be placed inside the recirculation chamber if it is adapted so as not to interfere substantially with the flow. Before the combustion products (hot gases) leave the combustion space 16, a part of them separates in the separation or the withdrawal point 22 from the main flow which moves generally along the line 0-0 to forming a recirculation vortex flow shown by arrow 28 in Figure 6. This flow has a velocity V2 which depends on the proportions between the internal dimensions of the combustion space 16 and also on the character of the recirculation vortex flow as length of the circular surface 21. With the angle ß between the direction of movement of the input fluid flow 0-0 and the tangent plane TT for the wall 12 at the separation point 22 of 45 °, the degree of turbulence of the flow The vortex along the circular surface 21 will be approximately 0.008 and if the angle ß is approximately 100 °, the degree of turbulence will be approximately 0.2. The preferred value of the ß angle is approximately 65 ° for the turbulence degree of approximately 0.03 to 0.025. It will be understood that the previously given low values of the degree of turbulence can be obtained only if the circular surface 21 (at least over the larger portion of its surface starting from the separation point 22 and extending in the direction towards the inlet 18) is it makes soft, that is to say without any hole, recess, protrusion, fluid inlets and the like. Any such unevenness in the surface inevitably and positively disturbs the vortex flow together with the surface 21, makes it turbulent and raises the degree of turbulence in excess of the aforementioned limits to 0.2 and even higher, making it similar to the one carried out in conventional trapped vortex combustors. The degree of turbulence can be increased (within the limits specified above) to increase the vortex temperature when the application requires it. The angle a is selected within the range of from 85 ° to 175 ° based on the conditions under which the recirculation vortex flow is joined to the flow of the input fluid in zone 24 of the inlet 18. An increase in the The value of this angle results in a lower turbulence of the two flows when they are joined. When the recirculation vortex flow having a velocity V2 joins the fluid flow of the inlet having a velocity] in the inlet zone (V2 >; V |), the two flows define an interphase layer between them as described in detail above to illustrate the processes that occur in the combustion space 16. It will be understood that the velocity V2 is greater than the velocity \ / - as it was previously described due to the thermal nozzle effect described above and due to the low degree of turbulence along the circular surface 21 and the absence of turbulence elements along this route and the high speed V2 continues higher than the speed V1 until the moment when the two flows meet in the entrance area.

Figure 8 shows a schematic partial sectional view of an annular combustor according to the invention, with the identical parts shown in the same reference numerals as in Figures 6 and 7 with addition of 100. In this embodiment, the surface 130 along which the inflow fluid flows have a portion 132 at the inlet 118, which is inclined with respect to the general direction 0-0 of the inlet fluid flow at an angle? from about 0 ° to 15 °. This design can be used in applications where it is required to maintain the radius between the speeds V-i and V2 and the radial size of the combustor is limited. In that case, the speed V! it can not be decreased by increasing the cross-sectional area of entry by simply lengthening dimension b because this would result in the inflow that interferes with the low turbulence recirculation vortex flow. By using the angle? which is greater than 0 °, the dimension b is partially unchanged to the left, but the flow of the transverse area becomes greater, without interfering with the recirculation vortex flow. For the rest, this method works together with the lines of the modality described above with reference to Figures 6 and 7.

Figure 9 is a longitudinal sectional view of the annular combustor designated together with the lines of Figure 8, with the identical parts shown with the same reference numerals as in Figures 6 and 7, with addition of 200. The difference here is that the angle a becomes greater, providing very smooth turbulence conditions for the two flows (the recirculation vortex flow and the input fluid flow) to decrease the CO level.

Figure 10 shows a mode of the combustor shown in Figure 8, with the identical parts shown with the same reference numerals with the addition of 300 to illustrate how the combustor modes shown in Figures 8 and 9 are used together. It can be observed here that the angle? is greater than 0 ° and the angle a is greater than 90 °. With the combustor according to the invention thus designed, the level of CO can be reduced with a small radial dimension of the combustor.

Figure 11 shows a can combustor designed in accordance with the invention. The identical parts are shown with the same reference numerals with the addition of 400. The difference here is that the inflow is admitted in the radial direction and moves along a curved route OR 0- ?. The wall 434 defining the surface 430 can move in and out (left to right or vice versa in the drawing) in a guide sleeve 436. This allows the same combustor to be used in different applications because by changing the conditions of entry, the speed radius] and V2 can be changed, also by changing the maximum temperature of the combustor design point. The wall 434 can also be positioned to move during the operation of the combustor (by means of a mechanism that is not shown) and in such a manner, the maximum temperature of the combustor can be varied, that is, depending on the loading conditions.

Figures 12 and 13 show the modes of the combustor according to the invention, with modifications of the inlet 18. As shown in Figure 12, the inlet opening has internally extending radially spaced projections 13 along the circumference of the opening, in Figure 13, the inlet opening has the radial recess 15 spaced along the circumference of the opening. In both cases, the projections and recesses ensure the structuring of the surface of the periphery of the incoming fluid flow by increasing its surface area. This allows contact of the surface area between the periphery of the incoming fluid flow and the recirculation vortex flow to extend with the same ratio between the V-i and V2 velocities of the two flows. With this arrangement, the combustor can be made shorter or the interaction between the two flows can be intensified with the same length of the combustor.

Figure 14 shows a longitudinal sectional view of a gas turbine engine incorporating an annular combustor according to the invention, in which the identical parts are shown in the same reference numerals with the addition of 500. The annular combustor 510 , which is constructed generally similarly to the combustor shown and described with reference to Figure 11, is constructed in a gas turbine engine of which a turbine 540 with a set of nozzles 541 is shown, mounted on a shaft 542. Air is supplied to the turbine. combustor through conduit 519 from a compressor (not shown) for inlet 518 of combustion space 516. Inlet 518 has a diffuser 544, which maintains a residual circumferential swirl that has been imparted to the air flow to improve the interaction between the peripheral surface of the air flow of the inlet and the recirculation vortex flow 528 in the combustion space 516. The fuel is admitted to the space 516 through ports 546 to pre-mix with the air. It is understood that the fuel can be pre-mixed with rising air of the combustor. An additional inlet for the air and / or fuel is provided in the wall portion 516 in the inlet zone 524 as shown at 548 to change the accumulation of the recirculation vortex flow just before it is attached to the periphery of the flow. of air admitted through inlet 518. If the combustor is designated to work at a low combustion temperature, said 1000 ° C, adding air and fuel through ports 548 will result in the elevation of the temperature a, for example, 1500 ° C. If, on the other hand, the combustor is designed to work at a temperature of 1500 ° C, a lower temperature of 1000 ° C, can be obtained by additionally supplying air through ports 548. Both air and fuel can be supplied through the ports 548 in controlled quantities and in controlled proportions to maintain the combustor at any desired temperature around a certain set point under fluctuating load conditions. The combustor has another inlet for the combustion air shown at 550 to add fresh air (ie oxygen) to the combustion products that are separated from the flow of the hot gases discharged through the outlet 520 for use in the turbine 540. If the equivalence radius is very low, the exhausted flow needs more oxygen to oxidize the CO. If the combustor works with an equivalent radius, this is very high, the exhausted flow will contain the incomplete oxidation products of the fuel, CH and CO components and the addition of fresh air in this case will improve the oxidation reactions, even elevating the exhausted gas temperature. It should be added that the air added through the ports 550 makes turbulent the exhausted flow and improves the burning of CO. The nozzle set 541 also makes the exhausted air turbulent. It will be apparent that special turbulizers well known to those skilled in the art are also installed downstream from the combustion space. It is understood that the steps described above of adding air and / or fuel through ports 548 and adding air through ports 550 can be accomplished by using a control system that has temperature and / or load sensors and devices of control suitable for varying ON or OFF the additional air and fuel supplies for the combustor using methods and equipment well known to those skilled in the art.

Figure 15 shows a longitudinal sectional view of another embodiment of a gas turbine engine incorporating an annular combustor according to the invention. This mode uses a centrifugal compressor 600 and a centripetal turbine 610 in a common rotor disk 612 mounted on a shaft 614 covered in a housing 615. A combustor 616 according to the invention has a housing 618 and a liner 619 defining a combustion space 620 which has an inlet 622 on the side of the compressor and an outlet 624 on the side of the turbine. The combustor has a burner 626. A separation wall between the compressor 600 and the turbine 610 has a circular surface 630 for the flow of recirculating vortex, extending between a point of separation 632 at the outlet 624 and the inlet 622 of the combustion space 620. It will be apparent from Figure 16 (which is a view taken along the arrow XVI of Figure 15) that a flow of recirculation vortex formed by a part of combustion products moving along the line 02-02, the arrow 634 will be located in this case inside! Inbound flow moving along route 02-02 in the same direction as shown in the drawing. With vortex flow turbulence conditions being the same as those described above for the previous modes, the additional advantage is that the flow moves on a "lubricating gas" provided by the flow of the fuel and the air mixture that reduces both thermal and hydraulic losses. As can be seen in Figure 17, the circular surface 630 is divided into fin segments 636 (shown in Figure 16) which transforms the circumferential velocity of the fluid flow near the longitudinal axis 03-03 of the engine at the apex velocity V2 .

It should be noted that the vortex velocity for the input flow velocity ratio (V2?) Has an effect on the CO level in the exhausted gases. Figure 18 shows the concentration CO against the residence time (in ms) for three different values of the ratio V2 ?? |. It can be seen that the best solution is to have the ratio radius greater than said 2.2 but in this case, the maximum possible temperature decreases. This means that in applications that require high temperatures at the combustor outlet, the rate ratio should be reduced with a subsequent increase in CO concentration. The methods that can be used to control the CO concentrations are described above.

The prototype ring combustors have been manufactured in accordance with the invention and tested. A combustor # 1 has a capacity of 760 cm3 and combustion occurs with the maximum possible velocity V2. The maximum temperature in the combustor occurs with a preferred speed V2 ensuring the maximum temperature of approximately 1260 C. The combustor had the following specifications: Internal diameter 100 mm Flow 0.06 kg / s Pressure 1.2 kg / cm2 1 output 650-1260 ° C.

The tests carried out on burning natural gas gave the following results: • The combustor ensured a stable burn without an accumulation of initial spice fuel mixture. • The combustor ensured a stable cold start without any preliminary heating. • The interior metal of the combustor showed no sign of damage after approximately 500 start cycles. • Stable combustion during the full range of combustion conditions with an equivalence ratio of 0.7 to 0.17. • No visible particulate material was observed in the depletion during the entire test period with the equivalence ratios of 0.7 to 0.17.

Some test results are provided later.

Table 1 - Results of the Emission Tests for the Prototype Chamber # 1 (760 cm) Note: All data in Tables 1 to 4 refer to 15% of 02.

Table 2 - Results of the CO Emission Tests for the Prototype Chamber # 2 (690 cm3) Table 3 - NOx emission for the prototype combustor "2 (690 cm3) (Gas Analyzer 400 HCLD) Table 4 - Results of the NOx Emission Test using the most accurate API 200A Gas Analyzer; Fuel # 2 (690 cm3) The prototype combusers were tested with a fuel having the following composition: Methane 15-22% abs. Nitrogen 10-30% Carbon dioxide 20-25% Water (jet) more than 40% Other gases more than 7% The results of the tests were the same as those shown for natural gas fuel. Using a normal equivalent ratio for a concrete combustor (for example Figure 22), the inverse reactions of the fuel reformation are carried out in the vortex blanket and in this case the process is accompanied by the reduction of the temperature of the vortex and as a result causes the reduction of the temperature of the walls of the combustor (along the gas jet). See Table 6.

It should be noted that a change in the concentration of CH4 and 02 in the interaction layers of the vortex flow and the fuel and the air flow influence not only the thermal energy transfer process but also the reaction direction (direct and indirect). inverted). If the concentration of CH4 is more than normal for combustion in the fuel and the air mixture (as a result of a coefficient of increase of equivalence compared to the value of the point of establishment of the design), the processes of reforming the fuel start prevailing in the interface layers. This, in combination with the oxygen supply species for the vortex, will result in the temperature decrease of the periphery of the vortex and as a consequence, the temperature of the molecules that reaches the central part of the vortex will also decrease. Both processes, which occur simultaneously, would result in a decrease in the vortex temperature to a sub-critical value resulting in the extinction of the flame. This is one reason why the problem of stable combustion of a lean mixture could not be solved by simple mechanical mixing of the vortex flow and the fuel and air mixture flow as has been done before because the thermal energy supply for the Fuel and air mixture in such a case is accompanied by a concurrent increase in the supply of C02 and H20 (resulting in enhanced fuel reformation), with a decrease in the vortex temperature and the mixture of fuel and air. However, because the reactions are carried out in the "interface" layer of the limit of the present invention, a combustor according to the present invention can be operated stably under said conditions. See Table 7. Said "reforming mode" operation can be stable and conducted continuously even without the presence of a flame.

Tables 5 and 6: Results of the Combustion Stability Test # 2 (690 cm3) for a Combustor with the Metallic Liner (tests completed with gas fuel) Table 5 * Standard liters per minute. The proportion of equivalence was not determined. Only the fuel flow was changed and the air flow remained unchanged. ** Fuel consumption of 60 sl / m is preferred for the 690 cm3 combustor.

Table 6 Table 7 Preferred embodiments of the invention have been described above. However, it is understood that several modifications and changes to the modalities present in this document are possible without going beyond the scope and spirit of the invention defined in the attached modalities.

Claims (37)

1. A combustor comprising: a reactor, an inlet for admitting a main flow of fluid for said reactor; an outlet for the discharge of the hot fluid from said reactor; said reactor positioned between said inlet and said outlet and comprising a main flow area, through which a majority of said main flow passes along the main flow path and a recirculation zone, through which a minor portion of said main flow passes; wherein said recirculation zone is defined in part by a wall having an inner surface curved in one direction in a substantially continuous manner and running from the point of withdrawal close to said outlet for a point of return close to said entrance, said surface interior being shaped and positioned with respect to said main flow path in such a manner as to divert the part of the fluid in said main flow path at said withdrawal point to form a recirculation vortex flow in said recirculation zone during the operation of said reactor and wherein said inner surface is further characterized by a lack of discontinuities so as to cause substantially quiet movement of a boundary layer along the periphery of said recirculation vortex flow.

2. The combustor according to claim 1, wherein the volume of said recirculation zone is not less then the volume of said main flow zone in the operation mode in which said reactor functions as a combustion chamber.

3. The combustor according to claim 1, wherein the volume of said recirculation zone is not less than the double volume of said main flow zone in the operation mode in said reactor that functions as a reformer.

4. The combustor according to claim 1, wherein the volume of the fluid entering said recirculation zone compared to the fluid discharged at said outlet is not less than seven percent in the operation mode in which said reactor functions as a combustion chamber.

5. The combustor according to claim 1, wherein the volume of fluid entering said recirculation zone compared to the fluid discharged in said outlet is not less than ten percent in the operation mode in which said reactor functions as a reformer.

6. The combustor according to claim 1, wherein the fluid within said boundary layer has a degree of turbulence of less than 0.2.

7. The combustor according to claim 6, wherein said degree of turbulence is between 0.008 and 0.01.

8. The combustor according to claim 1, wherein the direction of said recirculation flow at said withdrawal point is at an angle of between 15 and 100 degrees for the direction of said main flow path at said withdrawal point.

9. The combustor according to claim 1, wherein the direction of said recirculation flow at said return point is at an angle of between 85 and 175 degrees for the direction of said main flow path at said return point.

10. The combustor according to claim 1, wherein the ratio of the velocity of said recirculation vortex flow in the area near said inlet but outside said limit layer for the velocity of said main flow entering said flow zone The main one is in the range of not less than 1.4: 1 in the mode of operation in which said reactor functions as a combustion chamber.

11. The combustor according to claim 1, wherein the ratio of the velocity of said recirculating vortex flow in the area near said inlet but outside said boundary layer for the velocity of said main stream entering said principal flow zone it is in the range of not less than 2: 1 in the operating mode in which said reactor functions as a reformer.

12. The combustor according to claim 1, wherein said boundary layer has a depth of about 1 mm when said fluid heated in said outlet has a temperature of about 1100 ° C.

13. The combustor according to claim 1, wherein said boundary layer has a depth of about 2 mm when said fluid heated in said outlet has a temperature of about 800 ° C.

14. The combustor according to claim 1, wherein said boundary layer has a depth greater than the diameter of the central core of the recirculating fluid in said recirculating vortex flow when said fluid heated in said outlet has a temperature in the range of 380 -420 ° C.

15. The combustor according to claim 1, wherein the fluid within said recirculation vortex flow moves in layers and said layers do not mix substantially radially within the vortex.

16. The combustor according to claim 15, wherein the heat energy is transferred from the interior of said layers to the outside of said layers.

17. The combustor according to claim 1, wherein a high temperature relative to other temperatures within said reactor exits at the intersection of said peripheral vortex flow and said main flow passes through said inlet and said peripheral vortex flow moves. in the same direction as said main flow after said main flow passes through said intersection, forming an interfacial layer between said peripheral vortex flow and said main flow and wherein the heat energy is transferred from the fluid in said fluid. peripheral vortex flow through said interface layer and in the fluid in said main flow area.

18. The combustor according to claim 17, wherein the fluid passing through said inlet in the surface area of said fluid near said interface layer is burned by contact with said interface layer and acts as a flame. pilot for the combustor.

19. The combustor according to claim 17, wherein there is an absence of appreciable turbulent mixing between the fluid in said main flow and the fluid in said peripheral vortex flow.

20. The combustor according to claim 17, wherein said interface layer causes a thermal nozzle to be stabilized and maintained in said main flow area.

21. The combustor according to claim 17, wherein both combustion and fuel reforming are carried out within said interface layer wherein said interface layer is bonded with said main flow and said combination of combustion and reforming is maintains during said operation of the combustor.

22. The combustor according to claim 20, wherein the cross-sectional area of said salt is not more than 22 times the cross-sectional area of said inlet.

23. The combustor according to claim 1, wherein to change in the mode of operation in which said reactor functions as a reformer, said inlet cross-sectional area is reduced relative to said cross-sectional area employed in the operation mode in which said The reactor operates as a combustion chamber.

24. A method for reacting the fuel in a combustor, said combustor comprising a reactor, an inlet for admitting a main flow of fluid in said reactor, an outlet for discharging the hot fluid from said reactor, said reactor positioned between said inlet and said outlet comprising a main flow zone and a recirculation zone, said method comprising the steps of: passing a majority of said main flow in a route along said main flow area; passing a smaller portion of said main flow in a route through said recirculation zone, so as to form a recirculation vortex flow returning to a portion of the fluid in said recirculation zone for an area near said recirculation; causing a boundary layer of recirculating fluid for flow along the inner wall surface of said recirculation zone without substantial turbulence; causing the peripheral portion of said recirculation vortex flow to intercept said main flow in an area close to said inlet, wherein said peripheral flow has a higher velocity than said main flow, said peripheral flow following the area of said intersection, moves in approximately the same direction as said main flow; mixing said peripheral flow and said main flow by diffusion and not by substantial mechanical mixing; thus forming an interface layer between said main flow and said peripheral flow and causing a substantial transfer of heat energy from the fluid in said peripheral flow through said interface layer and in the fluid in said main flow area.

25. The method according to claim 24, wherein the volume of fluid entering said recirculation zone compared to the fluid discharged in said outlet is not less than seven percent in the operation mode in which said reactor functions as a combustion chamber.

26. The method according to claim 24, wherein the volume of fluid entering said recirculation zone compared to the fluid discharged in said outlet is not less than ten percent in the operation mode in which said reactor functions as a reformer.

27. The method according to claim 24, wherein said boundary layer of the recirculating fluid flow along said inner wall surface of said recirculation zone has a degree of turbulence of less than 0.2.

28. The method according to claim 27, wherein said limit layer of recirculation fluid flow along said inner wall surface of said recirculation zone has a turbulence degree of between 0.008 and 0.01.

29. The method according to claim 24, wherein the proportion of said velocity of said peripheral vortex flow for the velocity of said main flow entering said main flow area is in the range of not less than 1.4: 1, in the mode of operation in which said reactor functions as a combustion chamber.

30. The method according to claim 24, wherein the proportion of said higher velocity of said periphery vortex flow for the velocity of said main flow entering said main flow area is in the range of not less than 2: 1, in the mode of operation in which said reactor functions as a reformer.

31. The method according to claim 24 further comprises causing the fluid within said recirculation vortex flow to move in layers, wherein said layers do not mix substantially radially within the vortex.

32. The method according to claim 24, wherein the heat energy is transferred from the internal part of said layers to the external parts of said layers.

33. The method according to claim 24, further comprising causing the fluid entering said inlet in the surface area of said fluid proximate said interface layer to be burned by contact with said interface layer and therefore act as a pilot flame for the combustor.

34. The method according to claim 24, further comprising mixing the fluid in said main flow with the fluid in said peripheral vortex flow causing appreciable turbulence.

35. The method according to claim 24 further comprises causing a thermal nozzle to be established and maintained in said main flow area.

36. The method according to claim 24 further comprises causing both combustion and reforming of the fuel that are carried out in said interface layer and maintaining said combination of combustion and reforming during the operation of the combustor.

37. The method according to claim 24, further comprising changing the mode of operation in which said reactor functions as a combustion chamber for an operation mode in which said reactor functions as a reformer reducing the cross-sectional area of said entrance.