RU2183300C1 - Method and device for keeping of liquid hydrogen in vessel in conditions of gravitation - Google Patents

Abstract

FIELD: keeping of liquid hydrogen in the conditions of gravitation. SUBSTANCE: method of keeping of liquid hydrogen under pressure consists in extraction of vapor from the vessel and discharge of it in the environment. After extraction of vapor its orthoconversion is accomplished. After that the surface of the part of the vessel with a gas cushion is cooled by vapor, and then - the surface of the part of the vessel with liquid. The device realizing the method has a vessel with a draining pipe connection, protective housing and a shield with a drainage of the component. The shield is positioned between the vessel and the housing and made of two parts isolated from each other. The upper part shields the part of the vessel with a vapor cushion and has a factor of emissivity of the inner surface of at least 0.9. The lower part shields the part of the vessel with liquid. A para-ortho hydrogen converter is fastened on the shield upper part with a thermal contact. The converter inlet is connected to the draining pipe connection, and the outlet - to the inlet of the shield upper part. The outlet of the shield upper part is connected to the inlet of the shield lower part. EFFECT: enhanced life of keeping of liquid hydrogen and reduced loss of it. 2 cl, 1 dwg

Description

 The invention relates to cryogenic technology and can be used when storing liquid hydrogen in stationary ground conditions, when there is no mixing of the liquid.

 An analog of the method is a method for storing liquid hydrogen in a vessel [1], which includes storing liquid hydrogen in a vessel under overpressure and discharging the evaporated component through a drain line.

 An analogue of the device is a device for storing liquid hydrogen in a container [2], containing a container with thermal insulation, placed in a protective casing, equipped with a drain line with a safety valve. Between the tank and the casing is placed anti-radiation screen.

 The disadvantage of such technical solutions is the strong influence that temperature stratification has on the storage mode of liquid hydrogen. The component pressure rises too quickly, and the component loss during drainage is very high.

 Methods of combating temperature separation are based on mixing the liquid during storage using a variety of devices [3]. Thus, it is possible to equalize the temperature field in the liquid, however, it is impossible not only to eliminate the cause of the appearance of the upper heated liquid layer, but even to reduce the rate of its formation. Moreover, when mixing the liquid, additional energy is introduced into it, part of which passes into heat.

 At the same time, it is known that the formation of the upper heated layer in a cryogenic liquid during its stationary storage under gravity conditions is mainly due to the influx of heat to the liquid from above from the side of the “warm” container dome and steam cushion. By cooling the upper part of the tank and the steam cushion, it is possible to significantly reduce the rate of formation of the warm surface layer, and hence the rate of increase in pressure in the tank.

 This solution is used in the method [4] (prototype), where the gas cooling in the steam cushion is achieved due to gas-dynamic destabilization (turbulization) of the flow in the steam cushion during vapor drainage.

 The disadvantage of this method is its low thermodynamic efficiency - mixing the gas over the liquid is not very effective for its cooling and is associated with sufficiently large component losses. The amount of heat entering the upper part of the tank and the gas inside it does not decrease.

 For the proposed device, the prototype is a tank for storing liquid hydrogen with vacuum insulation and an anti-radiation screen, cooled by drained pairs [5]. The disadvantage of this design is the fact that the heat gain to the liquid from above is not sufficiently compensated. When the component is drained, the pressure in the tank drops quite quickly, while the temperature of the gas above the liquid and the upper part of the tank practically does not change. In this regard, after the termination of drainage, the warm surface layer of the liquid (and with it the pressure in the tank) is quickly restored. This requires renewed drainage and leads to increased component loss.

 The objective of the new technical solution is to increase the shelf life of liquid hydrogen and reduce its losses by reducing the rate of recovery of the warm surface layer in liquid hydrogen after the end of drainage and reducing the duration of the drainage itself.

 The problem is solved in that, after the selection of the steam, it is orthoconverted by passing through the para-orthogonal transducer, and then the upper part of the container with the steam cushion is cooled by it, and then its lower part, in which the liquid is located, is cooled. An exception is the bottom of the tank, which is not cooled in pairs.

 This provides additional cooling of the steam compared with its temperature in the steam cushion [2].

Thus:
- shielded radiant heat flow to the tank from the side of the warm casing;
- heat is removed (by radiant outflow of energy) from the top of the tank with a steam cushion;
- limited heat gain to the liquid on the side and not limited to the influx of heat from the bottom from the bottom.

This intensifies the convective mixing of the liquid and evens out the temperature field in it;
- reduced heat transfer through the body of the tank from the upper, warmer part, down. This helps to reduce the warm boundary layer at the side surface of the tank and the removal of warm liquid to the surface.

 The technical result of the method and device that implements it is the ability to significantly reduce the rate of pressure growth in the tank and thereby increase the storage time of hydrogen and reduce its loss.

 The bottom line is that in the method of storing liquid hydrogen in a tank under gravity conditions, including storing liquid hydrogen under excess pressure, taking its steam from the tank and dumping the steam into the environment, after taking the steam from the tank, carry out its orthoconversion, then cool them the surface of the part of the tank with a gas cushion, and then the surface of the part of the tank with liquid.

 The device that implements the method includes a container with a drainage pipe, a protective casing and a screen with a component drainage, located between the container and the casing, the screen is made of two parts isolated from each other: the upper screening part of the container with a steam cushion and having a degree of black inner a surface of at least 0.9, and the lower screening part of the container with liquid, while on the upper part of the screen a hydrogen orthogon transducer is fixed with thermal contact, the input of which is connected to the tank drainage pipe, and stroke - to the input of the upper part of the screen, the top of the screen output connected to the input bottom.

 Due to thermal insulation of the upper part of the tank from the casing side, as well as additional heat removal from this part of the tank, the formation time of the upper heated layer of liquid hydrogen in the tank increases. The same purpose is the restriction of heat gain to the liquid from the side, without limiting the heat gain from below, from the bottom of the tank. The latter measure reduces the "carry" of the warm component along the walls to the surface of the liquid and at the same time promotes convective mixing of the liquid in the tank. Thus, the effect of the "warm dome" is translated into the effect of the "warm bottom".

 For deeper cooling of the upper part of the tank (and the steam cushion located there), it is cooled separately from the lower part of the tank. For this, vapor of liquid hydrogen is used, which absorb external thermal radiation.

 To take heat from the top of the tank, these vapors are additionally cooled by passing them through an orthoparotransducer of hydrogen, where the para-orthoconversion of hydrogen, which goes with the absorption of heat, takes place [21. After that, the vapor temperature becomes lower than in the steam cushion of the tank, and the direction of thermal radiation in the region of the upper part of the tank changes to the opposite - it becomes directed from the tank. Absorption capacity of the upper part of the screen should, of course, be maximum. As the calculations showed, the heat sink is effective if the degree of blackness of this part of the screen is at least 0.9.

 After cooling the upper part of the tank, the pairs are sent to cool its lower part. At the same time, the bottom of the tank is not shielded in order to facilitate the formation of ascending convective flows that destroy the warm surface layer.

The scheme of the proposed device is presented in the drawing, where it is indicated:
1 - a container with liquid hydrogen, 2 - the upper part of the screen with the component drainage, 3 - the lower part of this screen, 4 - the hydrogen para-orthogon transducer, 5 - insulating spacers (may be absent), 6 - drain valve. The casing in the drawing is conventionally not shown.

 The device implements the method as follows. When storing hydrogen, the temperature of the upper layer of liquid and gas in the steam cushion rises; accordingly, the pressure in the vessel increases.

 1. When the pressure in the tank reaches a predetermined level, gas is taken from the tank, for which open valve 6 on the drain line.

 2. Then carry out the para-orthoconversion of the selected steam, passing it through the para-ortho-hydrogen 4.

 3. After passing through the para-orthorectifier 4, the pairs are cooled and sent to the upper part of the screen 2. In this case, not only the external heat gain to the tank from the casing is shielded, but also heat is taken from the upper part of the tank. As a result, not only the gas pressure in the tank drops rapidly, but also its temperature.

 4. After cooling the upper part of the screen (tank), the pairs are sent to the lower part of the screen 3. At the same time, the bottom of the tank is not protected from external heat influx.

 Thus, the proposed method and the device realizing it solves the problem of increasing the shelf life of liquid hydrogen and reducing its loss during storage.

LITERATURE
1. Rozhkov IV and others. "Obtaining liquid hydrogen." Chemistry, 1967, pp. 158-168.

 2. "Hydrogen. Properties, production, storage ..." Reference, ed. Hamburg D.Yu., M. "Chemistry", 1989, pp. 57-65, 213-214.

 3. "Liquid cryogenic systems." Filin N.V., Bulanov A.B. Leningrad, Mechanical Engineering, 1985, pp. 35-37.

 4. A method for storing a cryogenic component. US Pat. 2002990, F 17 C 3/00.

 5. "Long-term storage of cryogenic liquids." Fradkov A.B. Automation and modern technology. N 11, 1997.

Claims (2)

 1. A method of storing liquid hydrogen in a vessel under gravity conditions, including storing liquid hydrogen under excess pressure, taking its steam from the vessel and discharging the steam into the environment, characterized in that after the extraction of steam from the vessel, it is ortho-converted, then the surface is cooled parts of the container with a gas cushion, and then the surface of the part of the container with liquid.  2. A device that implements the method according to claim 1, comprising a container with a drainage pipe, a protective casing and a screen with a component drainage located between the container and the casing, the screen is made of two parts isolated from each other, the upper screening part of the container with steam cushion and having a blackness of the inner surface of at least 0.9, and the lower screening part of the container with liquid, while on the upper part of the screen is mounted a thermal para-transformer of hydrogen, the input of which is connected to the drain pipe bones, and the output is with the input of the upper part of the screen, while the output of the upper part of the screen is connected to the input of the lower part of the screen.