FR2922258A1 - Turbomachine e.g. turbopropeller, lubricating and fueling method for airplane, involves injecting recovered oil/fuel by injectors in supply circuit that is used for supplying fuel to elements of turbomachine to be lubricated - Google Patents

Abstract

The method involves lubricating elements of a turbomachine (3) to be lubricated using oil/ fuel. The oil/ fuel used for lubrication of the turbomachine are recovered. The recovered oil/fuel is injected by injectors in a fuel supply circuit (6) that is used for supplying the fuel to the elements of the turbomachine, where the turbomachine is provided with a low pressure supply pump (61) for supplying the oil/ fuel to the elements of the turbomachine, and connected to oil/fuel tanks (2, 60). An independent claim is also included for a device for lubricating and fueling a turbomachine.

Description

METHOD AND DEVICE FOR LUBRICATING AND FEEDING FUEL FROM A TURBOMACHINE

TECHNICAL FIELD AND PRIOR ART The invention relates to the field of lubrication and fuel supply of a turbomachine. It relates more particularly to a new lubrication process for injecting the liquid used for lubrication into the fuel supply circuit already provided for this purpose. It also relates to a device 15 particularly adapted to the implementation of such a method. In all the currently known turbomachines, the engine oil, that is to say that which serves to lubricate the functional elements implanted in the turbomachine, is cooled by the fuel. This is visible in FIG. 1 where, as described later, the engine oil circulates in a closed circuit 1 from a tank 2 and, after each passage in the turbomachine 3, it passes through a heater 4 of the servomechanisms of the turbomachine and is then cooled by an oil / fuel exchanger. The equilibrium temperature reached by the oil in this closed circuit 1 is high. However, for future turbomachines, the 30 powers envisaged are no longer compatible with the cooling capacity of the fuel supply circuit. In other words, it now seems necessary to use other cold sources. One solution that comes to mind would be to use air. However, the use of air / oil exchangers is very disadvantageous in terms of mass, cost and performance for the turbomachine (high impact on specific consumption), and poses major installation problems.

On the other hand, if we do not cool the oil properly, the oil circuit will quickly become dirty and lead to the shutdown of the turbomachine. The object of the invention is then to provide a solution that overcomes the aforementioned drawbacks and, therefore, that allows to effectively cool the elements of a high-power turbomachine, without harming its mass, cost or performance. SUMMARY OF THE INVENTION To this end, the subject of the invention is a method of lubricating and supplying fuel to a turbomachine in which the following steps are carried out. - lubrication of the elements of the turbomachine to be lubricated by means of an oil and / or fuel, - recovery of the oil and / or fuel used for the lubrication, - injection of the oil and / or fuel recovered (s) in the fuel supply circuit for supplying elements of the combustion engine such as injectors. According to the invention, the engine oil is no longer cooled for reinjecting it into the turbomachine, but it is burned as soon as it leaves the interior of the turbomachine. It is also used for combustion, this oil is no longer used for lubrication. Indeed, the current oils being limited in temperature resistance, they degrade during their passage in the turbomachine enclosures. According to the invention, the oil is therefore used only once in the turbomachine, it is mixed with the fuel at its outlet and this mixture is used for combustion. As described later, the process according to the invention can very well be carried out only with kerosene which thus plays both the role of lubricant and fuel.

The advantages of the process according to the invention are numerous. the elimination of oil / fuel exchangers as currently used, the use of a mixture of oil used for lubrication / fuel makes it possible to reduce the fuel consumption of the turbomachine, the possible use of biofuel as lubricating oil and fuel instead of kerosene, - the possible use of vegetable oils, ethyl esters or methylated vegetable oil (rapeseed for example) cheaper: indeed, because the oil circulates only once in the turbomachine and therefore remains for a short time, it is possible to dispense with conventional oils with high thermal resistance and relatively expensive, - the reduction of the flow in the lubrication circuit passing through the turbomachine: indeed, the open-circuit configuration of the single-use liquid for lubrication makes it possible to ensure a supply temperature upstream of the colder turbomachine (at least 60 ° C. lower than the temperature erosion of the lubricating oil currently used in a closed circuit). As a result, the cooling of the elements to be lubricated, such as the bearings, can be done at a reduced flow rate with respect to the conventional flow rates currently used, the cooling capacity of the fuel, which is not used in the invention, can be used for the cooling of equipment such as electricity generators for an airplane, or starter generators of the future generation (used for start-up and electrical generation) In classical architectures, these equipments require cooling supplemented by air / oil exchangers placed in the vein, which is therefore penalizing in terms of mass and performance.The invention also relates to a device for lubricating and supplying fuel to a turbomachine comprising: a reservoir of oil and / or fuel, - a pump for supplying oil and / or fuel to the elements of the turbomachine to be lubricated and racco to the reservoir, - an oil and / or fuel recovery pump used for lubricating elements of the turbomachine to be lubricated, - a lubrication circuit of the turbomachine passing through said turbomachine and connected, upstream of the turbomachine, to the feed pump and, downstream of the turbomachine, to the recovery pump, - injection means, connected downstream to the recovery pump, for injecting the oil and / or the fuel recovered (s) in the fuel supply circuit for supplying elements of the combustion engine such as injectors. Advantageously, the injection means are provided for injecting the oil and / or the fuel into the fuel supply circuit upstream of the combustion chamber of the turbomachine. According to an advantageous embodiment, the device comprises an oil reservoir separated from the fuel tank, the pump for supplying elements of the turbomachine to be lubricated being distinct from the fuel supply circuit and connected to the oil tank. . According to this advantageous embodiment, and in the case where the turbine engine is of type mounted on an aircraft, the oil reservoir is preferably located inside the wings of the aircraft.

According to another embodiment, the device comprises a single fuel tank, the element feed pump of the turbomachine to be lubricated being a low pressure pump of the fuel supply circuit and connected to the single tank. According to this other embodiment, the fuel is advantageously kerosene or a mixture of kerosene and oil.

To reinject the oil and / or fuel previously used for lubrication, three variants can be envisaged. According to the first variant, the injection means of the recovered oil and / or fuel (s) are connected to the recovery pump, and comprise a pipe connected upstream of a low pressure pump of the supply circuit. . According to a second variant, the injection means of the recovered oil and / or fuel (s) are connected to the recovery pump, and comprise a pipe connected between a low pressure pump and a high pressure pump of the fuel circuit. 'food. According to a third variant, the injection means of the recovered oil and / or fuel (s) are connected to the recovery pump, and comprise a pipe connected downstream of a high pressure pump of the supply circuit. and upstream of the turbomachine elements used for combustion such as injectors.

Finally, the invention relates to a turbojet engine or turboprop comprising a device as described above. BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and characteristics of the invention will emerge more clearly on reading the detailed description given with reference to the following figures in which: FIG. 1 is a schematic representation of an architecture of a lubrication device and FIG. 2A, 2B and 2C are respectively a schematic representation of an architecture of a device for lubricating and supplying fuel to a turbomachine according to a first embodiment. embodiment of the invention but according to three variants A, B, C different, - Figure 3 is a schematic representation of an architecture of a device for lubricating and supplying fuel to a turbomachine according to a second embodiment of embodiment of the invention. DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS In the figures, the terms upstream and downstream are to be understood in relation to the direction of flow of the liquid from its reservoir, that is to say oil and / or fuel lubrication function or fuel with fuel only function in the combustion chamber. In FIG. 1, the known device comprises a closed circuit 1 in which the so-called engine oil flows from a tank 2 and, after each passage in the turbomachine 3, it passes through a heater 4 of the servomechanisms of the turbomachine and then is cooled down. by an exchanger 5 oil / fuel. The reservoir 2 typically has a value of the order of 20 liters. This exchanger 5 is mounted on the fuel supply circuit 6 of the turbomachine 3. The equilibrium temperature of the oil is high, typically of the order of 130 ° C.

This fuel supply circuit 6 is open and comprises a tank 60 filled with kerosene whose downstream is connected to a low pressure pump 61 itself connected downstream to the exchanger 5 itself connected downstream to a pump 62. According to the invention, in FIGS. 2 and 3, the lubrication liquid 1 (oil and / or lubricating function fuel) and fuel supply 6 only fuel-function circuits are both open and not linked by heat exchangers. In other words, the architectures of the devices according to the invention do not include exchangers compared to the prior art. The lubrication circuit 1 is, according to the invention, common to the fuel supply circuit 6.

In the embodiment of FIG. 2, the device according to the invention firstly provides a reservoir 2 whose capacity is greater than that of the reservoir according to the state of the art and represented in FIG. 1. Indeed, according to the invention, the oil being consumed as part of the fuel, it does not circulate in a closed loop and therefore a higher capacity must be provided. Thus, typically the tank 2 according to the invention has a capacity of about ten m3. In the case where it is an aircraft turbomachine, it goes without saying that its dimensioning will be done according to the oil consumption required for a cycle of the aircraft, ranging from simple to long haul for a plane. The dimensions do not have a mass handicap because the oil used for combustion can advantageously be stored in a suitable box in one or all the wings of the airplane. The device according to the invention also comprises a pump 10 for supplying oil and / or fuel to elements of the turbomachine 3 to be lubricated and connected to the tank 2. It also comprises a pump 11 for recovering oil and / or of fuel used for lubricating elements of the turbomachine 3 to be lubricated. In the embodiment of Figure 2 (mixed oil / fuel lubrication), the oil is recovered by the pump 11 and deaerated. In the embodiment of Figure 2, the oil dedicated to lubrication does not undergo recirculation. It is therefore not necessary to use oils with high temperature resistance as in the embodiment of the state of the art shown in FIG. 1. According to the invention, it is therefore possible to use vegetable oils or ethyl or methyl esters of vegetable oil. The choice of oil can be made according to the value of its calorific value, its density, its price ... The residence time of the oil inside the turbomachine 3 being very short, it is possible to admit an oil temperature at the outlet of the higher turbomachine 3. In addition, if the oil is present inside an aircraft wing, its temperature at the inlet of the turbomachine 3 is relatively low. Also, the increase in temperature of the oil at the crossing of the turbomachine 3 may be greater than in the currently existing turbomachines, such as that shown in Figure 1, and, as a result, the oil flow rates may be reduced. It is thus possible, according to the embodiment of FIG. 2, to find the best compromise between oil flow for lubrication and oil flow for combustion in order to have an optimum oil / fuel ratio in terms of consumption. and therefore cost. As illustrated in FIGS. 2 (2A, 2B and 2C) and 3, the lubrication circuit of the turbomachine 3 passes through it and is connected upstream to the feed pump 10 and downstream of the turbomachine to the fuel pump. recovery 11. Connected downstream to the recovery pump 11, are provided, in three different variants A, B or C, injection means 61, 62, 63, 64, 65, for injecting the oil and / or the fuel recovered (s) in the fuel supply circuit 1 by the pump 11 to feed the injectors and servomechanisms of the turbomachine 3.

In the embodiment of FIG. 3, the lubricating liquid is constituted solely by the oil / fuel fuel function mixture, and the device of the invention thus comprises a single tank 2, 60. The oil / fuel ratio such as that oil / kerosene will advantageously be chosen to optimize the performance of the turbomachine and / or fuel savings. In this embodiment of FIG. 3, the lubricant supply pump 10 is constituted by the low-pressure pump 61 of the fuel supply circuit 6 and the reinjection of the lubricant into the latter is done in a manner similar to the embodiment of Figure 2, that is to say according to the three variants A, B, C detailed below.

According to variant A illustrated in FIG. 2A, the injection means of the lubricant (oil and / or fuel) recovered are connected to the recovery pump 11, and comprise a pipe 63 connected upstream of the low pressure pump 61 of the circuit. 6. According to variant B illustrated in FIG. 2B, the lubricant injection means (oil and / or fuel) recovered are connected to the recovery pump 11, and comprise a pipe 64 connected between the pump. low pressure 61 and the high pressure pump 62 of the supply circuit 6.

According to variant C illustrated in FIG. 2C, the injection means for the lubricant (oil and / or fuel) recovered are connected to the recovery pump 11, and comprise a pipe 65 connected downstream of the high-pressure pump 62 of the circuit. supply and upstream of the turbojet elements for combustion such as injectors, or servomechanisms. Variants A and B are the simplest to achieve from a hydraulic point of view because the pressure differences between oil and fuel are the lowest. According to the variants A and B, that is to say when the oil is injected upstream of the high pressure pump 62, it allows to heat up by mixing the fuel dedicated to the servomechanisms and thus to avoid the phenomenon of icing of the fuel used for regulation.

Claims (11)

A method of lubricating and supplying fuel to a turbomachine (3) in which the following steps are performed: lubricating elements of the turbomachine (3) to be lubricated by means of an oil and / or fuel , - recovery of the oil and / or fuel used for lubrication, - injection of the oil and / or fuel recovered in the fuel system (6) with fuel for the purpose of supplying elements of the combustion engine (3) such as injectors. 2. Device for lubricating and supplying fuel to a turbomachine comprising: - an oil reservoir (2, 60) and / or fuel tank, - a pump (10, 61) for supplying oil and / or in fuel of elements of the turbomachine (3) to be lubricated and connected to the reservoir, -a pump (11) for recovering oil and / or fuel used for lubricating elements of the turbomachine to be lubricated a lubricating circuit (1) of the turbomachine passing through said turbomachine and connected, upstream of the turbomachine (3), to the supply pump (10, 61) and, downstream of the turbomachine, to the recovery pump (11), - injection means (61, 62, 63, 64, 65), connected downstream to the recovery pump (11), for injecting the recovered oil and / or fuel (s), into the fuel supply circuit (6) for supplying elements of the combustion engine (3) such as the injectors. 3. Device according to claim 2, wherein the injection means are adapted to inject the oil and / or fuel into the fuel supply circuit upstream of the combustion chamber of the turbomachine (3). 4. Device according to claim 2 or 3, comprising an oil reservoir (2) separate from the fuel tank (60), the pump for supplying elements of the turbomachine to be lubricated being distinct from the fuel supply circuit. (6) and connected to the oil tank (2). 5. Device according to claim 4, wherein the turbomachine is an aircraft turbomachine, which aircraft comprises wings within which is implanted the oil reservoir (2, 60). 6. Device according to claim 2 or 3, comprising a single fuel tank (2, 60), the element supply pump of the engine to be lubricated being a low pressure pump (61) of the fuel supply circuit (6). ) and connected to the single tank (2, 60). 7. Device according to claim 6, wherein the fuel is kerosene or a mixture of kerosene and oil. 8. Device according to one of claims 2 to 7, wherein the injection means of the oil and / or recovered fuel (s), are connected to the recovery pump (11), and comprise a pipe ( 63) connected upstream of a low pressure pump (61) of the supply circuit (6). 9. Device according to one of claims 2 to 7, wherein the injection means of the oil and / or recovered fuel (s), are connected to the recovery pump (11), and comprise a pipe ( 64) connected between a low pressure pump (61) and a high pressure pump (62) of the supply circuit (6). 10. Device according to one of claims 2 to 7, wherein the injection means of the oil and / or recovered fuel (s), are connected to the recovery pump (11), and comprise a pipe ( 65) connected downstream of a high-pressure pump (62) of the supply circuit (6) and upstream of the laturbomachine elements (3) used for combustion such as the injectors. 11. Turbeactor (3) or turboprop 5 comprising a device according to any one of claims 2 to 10.