A method for coupling oxygen consumption and cooling inerting of oil tanks

Abstract

The present invention provides a coupled oxygen-consuming and cooling fuel tank inerting method, wherein the fuel vapor and air in the gas phase space above the fuel tank are sucked out by an exhaust fan and sent to a catalytic oxidation reactor, and the reaction products enter a diverter, a part of which enters the hot side channel of the regenerator, and the other part flows into the aircraft air conditioning system for cooling. In the cooling system, an oil separator is used to separate the liquid fuel, and the fuel is passed into the fuel in the fuel tank through a pipeline, and the mixed gas is passed into the gas phase space in the fuel tank through a pipeline, and is uniformly mixed with the original mixed gas in the upper part of the fuel tank. The present invention couples the oxygen-consuming inerting and cooling inerting technologies, which can not only control the oxygen concentration in the upper gas phase space in the fuel tank to be lower than 9%, but also control the fuel vapor concentration in the upper gas phase space in the fuel tank to be below the flammable limit, thereby realizing safe, green, efficient and economical fuel tank inerting.

Description

Technical Field

[0001] The invention relates to the technical field of aviation systems, in particular to a coupled oxygen consumption type and cooling type oil tank inerting method. Background Art

[0002] In 1996, the center wing fuel tank of TWA Flight 800 exploded under the action of an ignition source during the climb, and no one on the plane survived. After the accident, foreign countries began to pay attention to the safety of fuel tanks for civil aircraft. Combustion and explosion require three elements: an ignition source, fuel, and oxygen (or air). In the gas phase space above the onboard fuel tank, a large amount of flammable and explosive fuel vapor mixture gathers. When the concentration of the fuel vapor and air mixture reaches the flammable limit, the fuel vapor is very easy to ignite, causing a serious aircraft explosion accident. The active explosion-proof technology that controls and maintains the oxygen concentration in the gas phase space by passing inert gas into the gas phase space above the fuel tank is the most widely used.

[0003] The inerting system using hollow fiber membrane to produce nitrogen-rich gas has advantages in both volume and weight, so it is the mainstream airborne inerting technology. However, hollow fiber membrane still has some inherent disadvantages that are difficult to overcome. The separation membrane nitrogen production process requires a large amount of engine bleed air, resulting in large aircraft compensation losses, and the high pressure required for the gas source leads to poor application effects on many models (such as helicopters). The membrane fibers and permeation pores are very small and easily clogged. Ozone in the bleed air will cause membrane performance degradation. When the nitrogen-rich gas fills the fuel tank, fuel vapor will leak out and pollute the environment.

[0004] New airborne inerting technologies are currently being developed, such as green inerting, which uses controllable flameless catalytic combustion to reduce the oxygen content to achieve inerting of the fuel tank; cooling inerting extracts gas from the gas phase space of the fuel tank and passes it into the refrigeration system to cool it down, changing the ratio of air to fuel vapor to complete the inerting of the fuel tank. However, the existing single systems have some disadvantages: the oxygen-consuming inerting system needs to extract gas from the upper part of the fuel tank and heat it, and needs to replenish air through ram air, and needs to cool the gas flowing through the reactor; the effect of cooling inerting is directly related to the heat and mass transfer inside and outside the fuel tank. When the mass transfer inside the fuel tank is too fast, the cooling inerting system faces the risk of failure, and its use is limited to fuel tanks with small internal heat sources. Summary of the invention

[0005] In order to solve the problems of the prior art, the present invention provides a coupled oxygen-consuming and cooling type fuel tank inerting method, which couples the oxygen-consuming inerting technology with the cooling inerting technology, and can not only control the oxygen concentration in the upper gas phase space in the fuel tank to be lower than 9%, but also control the fuel vapor concentration in the upper gas phase space in the fuel tank to be below the flammable limit, thereby realizing safe, green, efficient and economical fuel tank inerting.

[0006] The present invention provides a coupled oxygen consumption type and cooling type oil tank inerting method, comprising the following steps:

[0007] 1) Suck out the fuel vapor and air in the gas phase space above the fuel tank;

[0008] 2) The extracted air and fuel steam mixed gas is preheated through the regenerator and preheater to reach the required reaction temperature and then sent to the catalytic oxidation reactor;

[0009] 3) Controlled flameless catalytic combustion is carried out in the catalytic oxidation reactor, hydrocarbons are oxidized into carbon dioxide and water, and the reaction products enter the splitter, one part enters the hot side channel of the regenerator, and the other part flows into the aircraft air conditioning system for cooling;

[0010] 4) In the cooling system, the product after the reaction in step 3) first passes through a water separator to separate the water vapor, then passes through a primary heat exchanger for heat exchange, enters a compressor for compression, obtains a high-temperature and high-pressure gas and inputs it into a secondary heat exchanger to cool the gas, then flows through a turbine for expansion to obtain a low-temperature and low-pressure mixture, uses an oil separator to separate the liquid fuel, and passes the fuel into the fuel in the fuel tank through a pipeline. The mixed gas passes through a pipeline into the gas phase space in the fuel tank and is evenly mixed with the original mixed gas at the top of the fuel tank.

[0011] During the inerting process, as the partial pressure of each gas in the gas phase space above the fuel tank changes, the gas will dissolve into the fuel or escape from the fuel. The gas after flowing through the cooling system enters the fuel tank, effectively reducing the fuel vapor concentration and temperature in the gas phase space above the fuel tank, controlling the evaporation of the fuel, and further achieving the inerting of the fuel tank.

[0012] The coupled oxygen-consuming and cooling fuel tank inerting system adopted by the present invention comprises a fuel tank, wherein the outlet of the fuel tank is sequentially connected to a first flame arrester, a first solenoid valve, a first flow meter, an exhaust fan, a regenerator, a first temperature sensor, a preheater, a second temperature sensor, a reactor, a flow divider, a water separator, a main controller, a second pressure sensor, a fifth temperature sensor, a primary heat exchanger, a compressor connected to a motor, a sixth temperature sensor, a secondary heat exchanger, a fuel separator, a turbine, a seventh temperature sensor, a fourth flow meter, a second solenoid valve, a first concentration sensor, a third pressure sensor, a second flame arrester, and an inlet of the fuel tank through a pipeline to form a closed loop; the flow divider is sequentially connected to a first pressure sensor, a fourth temperature sensor, a second flow meter, and a regenerator through a pipeline, and the regenerator is sequentially connected to a third temperature sensor and a water separator through a pipeline; the fuel separator is sequentially connected to a third flow meter, a bypass valve, and a seventh temperature sensor through a pipeline, and the fuel separator is sequentially connected to a fifth flow meter and an inlet of the fuel tank through a pipeline.

[0013] As a further improvement, a fourth pressure sensor, an eighth temperature sensor and a second concentration sensor are provided in the fuel tank.

[0014] As a further improvement, the solenoid valve and the sensor are both connected to the main controller.

[0015] The beneficial effects of the present invention are:

[0016] 1. The coupled oxygen-consuming and cooling fuel tank inerting system does not require air to be drawn from the engine and can be used in aircraft without a suitable air source, such as helicopters. It has fast preheating and startup speeds, and oxygen is consumed in the reactor, which does not put much load on the cooling system. Its cost is much lower than the currently widely used airborne hollow fiber membrane inerting technology. It is more efficient than hollow fiber membrane inerting and takes less time to inert.

[0017] 2. The system is small in size and light in weight, and is more convenient to modify and overhaul. The temperature of the mixture in the gas phase space of the fuel tank can be used as a standard to easily and continuously monitor the system performance and the flammability status of the fuel tank. No fuel vapor is discharged during the inerting process, which is green and environmentally friendly. By controlling the temperature of the fuel tank, the dissolution and escape of fuel vapor and oxygen in the fuel can be controlled, further reducing the flammability of the fuel tank.

[0018] 3. It solves the problem that the oxygen-consuming inerting system needs to be supplemented with compressed air and the gas flowing through the reactor needs to be cooled. The cooling inerting method is used to make up for the energy waste problem and improve the safety of the single cooling inerting system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The schematic diagram of a coupled oxygen-consuming and cooling type tank inerting system.

[0021] Among them, 1-fuel tank, 2-first flame arrester, 3-first solenoid valve, 4-first flow meter, 5-exhaust fan, 6-regenerator, 7-first temperature sensor, 8-preheater, 9-second temperature sensor, 10-reactor, 11-diverter, 12-third temperature sensor, 13-first pressure sensor, 14-fourth temperature sensor, 15-second flow meter, 16-water separator, 17 second pressure sensor, 18-fifth temperature sensor, 19-primary heat exchanger, 20-motor, 21- Compressor, 22-sixth temperature sensor, 23-secondary heat exchanger, 24-turbine, 25-third flow meter, 26-bypass valve, 27-seventh temperature sensor, 28-fourth flow meter, 29-fuel separator, 30-second solenoid valve, 31-first concentration sensor, 32-third pressure sensor, 33-second flame arrester, 34-fifth flow meter, 35-fourth pressure sensor, 36-eighth temperature sensor, 37-second concentration sensor, 38-third concentration sensor, 39-main controller. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0023] like Figure 1 As shown, the present invention designs a coupled oxygen-consuming and cooling tank inerting system, which couples the oxygen-consuming inerting system with the cooling inerting system. On the basis of being compatible with the advantages of oxygen-consuming inerting and cooling inerting, such as not requiring air to be bleed from the engine, high inerting efficiency, safety and environmental protection, it realizes the reasonable distribution of energy and improves the safety of a single cooling inerting system or a single oxygen-consuming inerting.

[0024] A coupled oxygen-consuming and cooling tank inerting system, such as Figure 1As shown, it mainly consists of a fuel tank 1, a first flame arrester 2, a first solenoid valve 3, a first flow meter 4, an exhaust fan 5, a regenerator 6, a first temperature sensor 7, a preheater 8, a second temperature sensor 9, a reactor 10, a diverter 11, a third temperature sensor 12, a first pressure sensor 13, a fourth temperature sensor 14, a second flow meter 15, a water separator 16, a second pressure sensor 17, a fifth temperature sensor 18, a primary heat exchanger 19, a motor 20, a compressor 21, a sixth temperature sensor 22, a secondary heat exchanger 23, a turbine 24, a third flow meter 25, a bypass valve 26, a seventh temperature sensor 27, a fourth flow meter 28, a fuel separator 29, a second solenoid valve 30, a first concentration sensor 31, a third pressure sensor 32, a second flame arrester 33, a fifth flow meter 34, a fourth pressure sensor 35, an eighth temperature sensor 36, a second concentration sensor 37, a third concentration sensor 38, a main controller 39 and a number of pipelines.

[0025] The coupled oxygen-consuming and cooling fuel tank inerting system firstly sucks out the fuel vapor and air in the gas phase space above the fuel tank 1 through the exhaust fan 5, and respectively arranges a first flame arrester 2 and a second flame arrester 33 at the inlet and outlet of the fuel tank. The flame arrester is a temperature-controlled valve of a memory molten alloy, and utilizes the action of gravity and a spring mechanism to prevent fuel leakage in the fuel tank.

[0026] The extracted air, fuel steam mixed gas is preheated by the regenerator 6 and the preheater 8 to reach the required temperature for the reaction and then sent to the catalytic oxidation reactor 10, where controllable flameless catalytic combustion is carried out, and hydrocarbons are oxidized into carbon dioxide and water. The first temperature sensor is located between the regenerator and the preheater pipeline, which is convenient for measuring the temperature of the gas flowing through the regenerator. The second temperature sensor is located in the pipeline between the preheater and the reactor, which is convenient for controlling the heating temperature of the preheater to reach the catalytic oxidation reaction temperature condition. According to the usual process parameters of self-sustaining catalytic combustion, the temperature of the mixed gas entering the reactor (out of the preheater) is selected as 150°C, and the temperature leaving the reactor is 200°C.

[0027] The reaction product enters the splitter 11, a part of which enters the hot side channel of the regenerator 6, and the other part flows into the aircraft air conditioning system for cooling. A first pressure sensor 13, a fourth temperature sensor 14, and a second flow meter 15 are arranged between the splitter 11 and the hot side channel of the regenerator 6 to facilitate real-time detection of the flow rate, temperature, and pressure in the pipeline.

[0028] In the cooling system, the inlet of the primary heat exchanger 19 is connected to the outlet of the water separator 16 through a gas pipeline. The function of the water separator 16 is to remove the initial water vapor and the reacted water vapor in the oil tank.

[0029] The outlet of the primary heat exchanger 19 is connected to the inlet of the compressor 21; the mixed gas exchanges heat through the primary heat exchanger 19 and enters the compressor 21 for compression, and the inlet of the secondary heat exchanger 23 is connected to the outlet of the compressor 21 through a pipeline, and a high-temperature and high-pressure gas is obtained and input into the secondary heat exchanger 23. After the secondary heat exchanger 23 cools the mixed gas to a lower temperature again, it flows through the turbine 24 to expand and do work, and obtains a low-temperature and low-pressure mixture.

[0030] The outlet of the secondary heat exchanger 23 is connected to the inlet of the fuel separator 29. A bypass valve 26 is provided at the gas outlet of the fuel separator 29, which is respectively connected to the outlet of the turbine 24 and the inlet of the third flow meter 34. The seventh temperature sensor 27 is located between the fourth flow meter 28 and the turbine 24. The main controller 39 compares the temperature signal of the seventh temperature sensor 27 with the designed evaporation temperature. When the exhaust temperature of the turbine 24 is lower than the designed evaporation temperature, the main controller 39 opens the bypass valve 26 and mixes part of the gas after passing through the secondary heat exchanger 23 with the gas to increase the exhaust temperature of the turbine 24.

[0031] The liquid fuel is separated by using the fuel separator 29, and the fuel is passed into the fuel in the fuel tank 1 through a pipeline. The mixed gas is passed into the gas phase space in the fuel tank 1 through a pipeline, and is evenly mixed with the original mixed gas in the upper part of the fuel tank. During the inerting process, as the partial pressure of each gas in the gas phase space in the upper part of the fuel tank changes, the gas will dissolve into the fuel or escape from the fuel. The gas after flowing through the cooling system enters the fuel tank, which effectively reduces the fuel vapor concentration and temperature in the gas phase space in the upper part of the fuel tank, controls the evaporation of the fuel, and further realizes the inerting of the fuel tank.

[0032] In addition, in order to keep the pressure of the gas phase space in the fuel tank 1 unchanged, a vent hole is provided above the fuel tank 1 to keep the air pressure inside and outside the fuel tank balanced.

[0033] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as herein.

[0034] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for coupling oxygen consumption and cooling inerting of oil tanks, characterized in that The following steps are involved: 1) Suck out the fuel vapor and air in the gas phase space above the fuel tank; 2) The extracted air and fuel steam mixed gas is preheated through the regenerator and preheater to reach the required reaction temperature and then sent to the catalytic oxidation reactor; 3) Controlled flameless catalytic combustion is carried out in the catalytic oxidation reactor, hydrocarbons are oxidized into carbon dioxide and water, and the reaction products enter the splitter, one part enters the hot side channel of the regenerator, and the other part flows into the aircraft air conditioning system for cooling; 4) In the cooling system, the product after the reaction in step 3) first passes through a water separator to separate the water vapor, then passes through a primary heat exchanger for heat exchange, enters a compressor for compression, obtains a high-temperature and high-pressure gas and inputs it into a secondary heat exchanger to cool the gas, then flows through a turbine for expansion to obtain a low-temperature and low-pressure mixture, uses an oil separator to separate the liquid fuel, and passes the fuel into the fuel in the fuel tank through a pipeline. The mixed gas passes through a pipeline into the gas phase space in the fuel tank and is evenly mixed with the original mixed gas at the top of the fuel tank.

2. The method for coupling oxygen consumption and cooling inerting of an oil tank according to claim 1, characterized in that: During the inerting process, as the partial pressure of each gas in the gas phase space above the fuel tank changes, the gas will dissolve into the fuel or escape from the fuel, and the gas after flowing through the cooling system enters the fuel tank.

3. The method for coupling oxygen consumption and cooling inerting of an oil tank according to claim 1, characterized in that: The system used for coupled oxygen-consuming and cooling-type fuel tank inerting comprises a fuel tank (1), wherein the outlet of the fuel tank (1) is connected in sequence through a pipeline to a first flame arrester (2), a first solenoid valve (3), a first flow meter (4), an exhaust fan (5), a regenerator (6), a first temperature sensor (7), a preheater (8), a second temperature sensor (9), a reactor (10), a flow divider (11), a water separator (16), a main controller (39), a second pressure sensor (17), a fifth temperature sensor (18), a primary heat exchanger (19), a compressor (21) connected to a motor (20), a sixth temperature sensor (22), a secondary heat exchanger (23), a fuel separator (29), a turbine (24), and a seventh temperature sensor (27 ), a fourth flowmeter (28), a second solenoid valve (30), a first concentration sensor (31), a third pressure sensor (32), a second flame arrester (33), and an inlet of a fuel tank (1) form a closed loop; the flow divider (11) is sequentially connected to the first pressure sensor (13), the fourth temperature sensor (14), the second flowmeter (15), and the regenerator (6) through a pipeline, and the regenerator (6) is sequentially connected to the third temperature sensor (12) and the water separator (16) through a pipeline; the fuel separator (29) is sequentially connected to the third flowmeter (25), the bypass valve (26), and the seventh temperature sensor (27) through a pipeline, and the fuel separator (29) is sequentially connected to the fifth flowmeter (34) and the inlet of the fuel tank (1) through a pipeline.

4. The method for coupling oxygen consumption and cooling inerting of an oil tank according to claim 3, characterized in that: A fourth pressure sensor (35), an eighth temperature sensor (36), and a second concentration sensor (37) are arranged in the fuel tank (1).

5. The method for coupling oxygen consumption and cooling inerting of an oil tank according to claim 3, characterized in that: The solenoid valve and the sensor are both connected to the main controller (39).

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