A liquid methane deep subcooling and filling system and method based on antifreeze control

Abstract

A liquid methane deep subcooling and filling system and method based on anti-freezing control, including a ground liquid methane storage tank, a vertical liquid nitrogen bath heat exchanger and an arrow-top liquid methane storage tank, using liquid nitrogen before filling The liquid methane storage tank, filling pipeline and engine and other components are pre-cooled with cold nitrogen gas. When filling, the method of filling while supercooling is adopted, and the vertical liquid nitrogen bath heat exchanger is used to supercool the liquid methane to 95K After the temperature zone enters the rocket storage tank, the flow rate and supercooling degree in the filling system are flexibly controlled based on pressure control and liquid level control; once the liquid methane is detected to freeze, the pipeline is immediately switched and high-pressure nitrogen gas is used Perform rapid rewarming and melting treatment; at the same time, use the vaporized cold nitrogen to control the pressure in the pillow area of ​​the liquid methane storage tank on the arrow and maintain the subcooling degree of the liquid methane; the invention realizes the acquisition of a large subcooling degree of the liquid methane, the Methane subcooling anti-freezing control, self-adaptive adjustment of subcooling heat exchanger to different flow rates and set temperature zones, etc.

Description

technical field [0001] The invention relates to the technical field of acquisition and filling of liquid methane supercooling at a low-temperature rocket launch site, and in particular to a liquid methane deep supercooling and filling system and method based on anti-freezing control. Background technique [0002] With the development of aerospace technology, cryogenic launch vehicles are gradually moving towards commercialization, and cryogenic propellants are transitioning from the most popular combination of liquid hydrogen / liquid oxygen and liquid oxygen / kerosene to the more promising combination of liquid methane / liquid oxygen, so Liquid methane has been paid more and more attention as a new propellant fuel. There are many advantages in using liquid methane / liquid oxygen as low-temperature rocket fuel: 1. The liquefaction temperature (111.7K) is higher than that of hydrogen, which is easy to liquefy, and the production and storage costs are low, and the temperature diffe...

AI Technical Summary

Problems solved by technology

After calculation and analysis, it is concluded that the use of 77K liquid nitrogen heat exchange cooling technology to obtain deep subcooled liquid methane is the most economical, simple and reliable method. However, there are still the following technical difficulties in the application of this method to the filling system of cryogenic rocket launch sites: 1. Anti-freezing problem of deep subcooled liquid methane

When 77K liquid nitrogen is used for cooling, it is easy to solidify liquid methane, because the freezing point of liquid methane is relatively high (90.694K), so when filling at the launch site, if the operation is not performed according to the designed flow rate or the filling is stopped, The liquid methane will freeze in the subcooler, block the filling pipeline, there will be a delay in filling, and the possibility of affecting the launch, and once the subcooler is designed, it will be difficult to adjust the filling flow and liquid methane subcooling degree. Make the flexibility and operability of the entire cryogenic rocket filling system very poor

2. The problem of deep subcooled liquid methane precooling for filling pipelines, engines and storage tanks on rockets

Because the saturation pressure corresponding to liquid methane at 91K is 12.16kPa, which is 88% lower than the saturated state pressure, and it is in a negative pressure state. At this time, the outside air will easily enter the storage tank and cause the pollution of liquid methane, and the arrow is on the storage tank. The structure cannot bear the excessive negative pressure difference. If the negative pressure state is forced to be used, the wall thickness of the storage tank on the arrow will increase, which virtually offsets the advantages brought by the supercooling of liquid methane. Therefore, for deep supercooled liquid When adding methane to the storage tank on the arrow, find a way to maintain a slightly positive pressure environment in the storage tank as much as possible

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