RU2027946C1 - Method of charging aircraft tank with liquefied natural gas - Google Patents

Abstract

FIELD: aeronautical engineering. SUBSTANCE: in pumping the cryogenic fluid to aircraft tank, vented vapors are directed to service reservoir. In draining liquefied natural gas from transfer lines, vented vapors are directed for pressurization of these lines together with self-pressurizing vapor. In case of probable return of liquefied gas from aircraft tank to service reservoir, vented vapors are directed for pressurization of aircraft tank together with self-pressurizing vapors. Required pressure of vapors in service reservoir is maintained through condensation of these vapors and regulation of supply of liquid to self-pressurizing evaporator. EFFECT: enhanced reliability. 1 dwg

Description

 The invention relates to cryogenic technology and will find application in the technology of refueling an aircraft tank with liquefied natural gas (LNG) from a vehicle's flow rate.

 A known method of overflowing liquefied gas from a supply tank to a stationary tank, including the removal of the generated vapors from one tank to another and their condensation due to the temperature difference in these tanks, pumping liquefied gas by a pump and the possible return of liquefied gas back from a stationary tank to a supply tank [1 ].

 This method of overflowing liquefied gas avoids the release of generated vapors into the atmosphere and thereby increases the safety of work with explosive gases, as well as partially uses the exhaust vapors to pressurize the tank when creating the necessary pressure at the pump inlet.

 These advantages apply only to propane-butane hydrocarbon gases, which with a relatively small increase in pressure can be transferred from one state to another (from gaseous to liquid).

 However, this method is ineffective for low-temperature (cryogenic) liquids, which is LNG.

 Closest to the proposed and selected as a prototype is a method of filling the tank of an aircraft (UAV) with cryogenic liquid from a vehicle’s tank, which includes self-pressurizing of a supply tank with an evaporator, pumping cryogenic liquid by a pump, draining the generated vapors, draining from the docking elements and possible return LNG in a supply tank with a UAV supercharged [2].

 The disadvantages of this method are the discharge of drainage vapors into the atmosphere, which is unacceptable due to flammability when refueling aircraft tanks, as well as product loss. Disposal (collection) of large quantities of vapors into a gas tank complicates the device for implementing the method, in addition, with the possible return of cryogenic liquid from the UAV to the supply tank, it is necessary to have an external boost source on board the aircraft, which also complicates this device.

 The proposed method of refueling an LNG aircraft tank from a vehicle’s supply tank includes self-pressurizing the tank using an evaporator, pumping a cryo-liquid, draining from overflow lines, a possible return of LNG to the tank with pressurizing the tank, and drainage of vapors generated when pumping cryogenic liquid into the tank aircraft drained pairs are sent to the supply tank, when draining LNG from overflow communications drained pairs, together with self-charging pairs, are directed to pressurizing these indications, and with the possible return of LNG from the aircraft tank to the supply tank, the drainage vapors together with the self-pressurization vapors are sent to pressurize the aircraft tank, and the required vapor pressure in the supply tank is supported by the condensation of part of these vapors and the regulation of the liquid supply to the self-pressurization evaporator.

 The invention consists in the following.

 Self-pressurization using an evaporator increases the pressure in the cushion of the supply tank to create a backwater at the inlet to the pump. When LNG is overflowed into the aircraft tank and vice versa, when draining from the communications, LNG vaporization occurs in the aircraft tank and in overflow communications. The resulting vapors are discharged into the supply tank. The pressure increase in the tank is regulated by the supply of liquid to the evaporator and the condensation of part of the vapor in the tank itself. This eliminates the removal of vapor into the atmosphere and increases the safety precautions for working with LNG and at the same time reduces the flow of liquid from the tank. The pressurization of the aircraft tank and overflow communications is carried out by self-pressurizing vapors and drainage vapors from the supply tank. This eliminates the use of a third-party source of pressurization of the tank of the aircraft and overflow communications and simplify the device for implementing the method.

 The drawing shows a schematic diagram of an installation for implementing the proposed method.

 The device comprises a transport consumable tank 1 for cryogenic liquid, equipped with an evaporator 2, located on line 3 connecting the upper and lower parts of the tank and having a control valve 4. In the gas cushion of the tank 1 there is a nitrogen condenser 5 with a valve 6 and a valve 7. In the bottom of the tank the liquid filling line 8 with shut-off valve 9 is omitted. The tank 1 is equipped with a pressure sensor 10 for signaling pressure. A suction line 11 with a shut-off valve 12 connects the pump 13 to the bottom of the tank 1. The discharge line 15 contains parallel valves 15 and 16 of high and low flow rate and has a branch 17 with a valve 18 connecting the annular part of the discharge line 14 with the suction line 11. Branch 19 a portion of the discharge line between the pump and valves 15 and 16 is connected to a valve 20 with a liquid filling line 8, a branch 21 with a normally open valve 22 connects a portion of the discharge line between the pump and valves with a gas cavity similar tank 1. From the gas cavity of the tank, a steam exhaust line 23 is provided with a valve 24. A liquid line 26 is provided with a valve 27 from the lower point of the aircraft tank 25, and a steam discharge line 28 with a valve 29 is from the upper point. The end section of line 28 connected in front of the valve 27 with the line 26 bypass line 30 with the valve 31.

 The proposed method is as follows.

 Before pumping LNG from the supply tank 1 to the tank 25 of the aircraft, the end sections of lines 14 and 26, 23 and 28 are docked. The nitrogen supply unit is connected, the control system is connected, the pipelines are purged with nitrogen to remove air components. Cooling of the pump 13 and the suction line 11 is carried out through the valve 12. The fluid flows by gravity into the pump, evaporates and drains through line 21 through the valve 22 into the supply tank. Cooling of lines 14, 26 and tank 25 of the aircraft is carried out using pump 13, pumping liquid at a low flow rate through valve 16 and valve 27 into the tank of the aircraft, while the resulting vapors are drained through lines 28, 23 through valves 29 and 24 to the supply tank, and the excess the liquid after the pump through line 19 is diverted to the supply tank.

 Cryo-liquid is supplied to the aircraft tank through pump 13, valve 15 and valve 27. The resulting vapors are drained along line 28, 23 through valves 29, 24 to the supply tank. Before turning on the pump 13 and throughout its operation, self-pressurization of the tank 1 by the evaporator 2 is carried out. The pressure in the gas cavity of the tank 1, necessary for pump back-up (PID refueling 1.0-1.2 atm), is controlled by the sensor 10 by opening the valve 6 at open valve 7 and feed control to the evaporator 2 using valve 4.

 Tank 25, filled to a certain level, is refilled through valve 16 with valve 15 closed.

 The discharge of LNG residues from the filling communications is carried out by the pump 13 through valves 18 and 20. The necessary pressure at the pump inlet is created by raising the pressure in the supply tank using the evaporator 2 and supplying vapor from the supply tank through lines 23, 30 through valves 24 and 31. The pressure is recorded pressure sensor 10 (PID discharge 1.8-2.4 atm).

 The return of LNG from the aircraft tank to the supply tank is carried out by the pump 13 through the valve and valves 27, 18 and 20. The necessary pressure at the inlet of the pump is created by raising the pressure in the supply tank 1 using the evaporator 2 and supplying drainage vapors to the gas tank of the tank through line 23, 28 through valves 24 and 29.

 When LNG is pumped into the aircraft tank and drained back, the pressure in the supply tank is regulated by the flow rate of the liquid in front of the evaporator and the condensation of part of the liquid in the tank itself, the preference depends on the volume of the tank being refueled.

 The proposed method of refueling an aircraft tank is environmentally friendly, non-flammable, easy to operate and can find application in the conversion of an aircraft fleet to cryogenic fuels.

Claims (1)

 METHOD FOR FILLING A LIQUID NATURAL GAS AIRCRAFT TANK from a vehicle’s supply tank, including self-pressurizing a supply tank using an evaporator, pumping with a cryo-fluid pump, discharge from overflow communications, possible return of liquefied natural gas to a tank with pressurization of the aircraft tank and the resulting vapor that when pumping cryo-liquid into the aircraft tank, the drained pairs are sent to the supply tank, when draining the liquefied natural gas from overflow communications, my pairs, together with the self-pressurization pairs, are sent to pressurize these communications, and if the liquefied natural gas can be returned from the aircraft tank to the supply tank, the drained pairs along with the self-pressurization pairs are sent to pressurize the aircraft tank, and the line-by-line vapor pressure in the supply tank is maintained by condensing some of these vapors and regulating the flow of liquid to the self-pressurizing evaporator.

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