RU156584U1 - CRYOGENIC LIQUID FILLING AND GASIFICATION CYLINDER - Google Patents

Abstract

Cryogenic liquid filling and gasification cylinder containing an external pressure vessel and an internal vessel of volume V placed in it, the cavity of which is connected to the filling and discharge lines, and the communication between the vessel cavities is made in the form of holes in the upper part of the internal vessel, characterized in that the internal the vessel is made with a volume determined from the ratio for real gas: where V is the volume of the cavity of the inner vessel; V is the total volume of the cavities of the external and internal vessels; ρ is the density of the cryogenic liquid ty; R is the gas constant of the ideal gas; P is the maximum allowable gas pressure in the vessel; T is the maximum allowable gas temperature in the vessels; Z is the compressibility coefficient of the real gas, which is a function of pressure and temperature and depends on its compressibility, where Z> 1.

Description

The utility model relates to technologies for storage and distribution of gases and liquids using cryogenic filling of pressure vessels and can be used for energy-generating systems.

The well-known "Evaporator of cryogenic liquid" (RF Patent No. 2239121 of 01/28/2002), comprising a housing with nodes for supplying and dispensing refrigerant, a chamber of liquid and gaseous refrigerant, a heat exchange element. The device heats the liquid and gives consumers gasified refrigerant without increasing its pressure. However, the device can only be used by consumers of low pressure gasified refrigerant. In addition, for the operation of the device, thermal energy is needed to heat the heat exchange element.

It is known "Device for receiving liquefied natural gas, its gasification and the issuance of a gaseous product to the consumer" (RF Patent No. 2365810 from 02.15.2008), containing a gasifier, including an external pressure vessel, in the cavity of which an internal vessel is placed

without pressure drop, the cavity of which is in communication with the cavity of the external pressure vessel and is connected to the filling line. The device also contains a pressure vessel, the cavity of which is connected to the refrigerant supply line to the consumer and the cavity of the outer vessel. The device provides the consumer with gasified high pressure refrigerant. However, the presence of an additional (to the gasifier) high-pressure tank complicates the device.

These disadvantages are eliminated in the closest in technical essence analogue (Patent of the Russian Federation No. 2163699 dated 02.07.1999). The fuel cylinder according to this patent includes an external pressure vessel and an internal vessel, the cavity of which is connected to the refueling and emptying line, and in the upper part is communicated with openings with the cavity of the pressure vessel. The volume of the inner vessel is selected to work with pressure and temperature according to the well-known dependence for ideal gases. However, the gases obtained by evaporation of cryogenic liquids for high pressures are not ideal, but real, because of which the pressure of the working fluid in the balloon may be higher than the maximum allowable value, which reduces the reliability of the balloon. The lack of dependence in the prototype, taking into account the real properties of the gas, leads to an overestimation of the volume of the inner vessel. This, with complete gasification of the cryogenic liquid, makes it possible to increase the pressure in the cylinder above the permissible value.

The utility model is based on the solution of the problem of ensuring the most complete filling of a cylinder with cryogenic liquid. The technical result consists in obtaining the maximum allowable gas pressure during gasification of a cryogenic liquid.

The problem is solved in that the cylinder for refueling and gasification of cryogenic liquid contains an external pressure vessel and an internal vessel of volume V _B placed therein. The cavity of the inner vessel is connected to the refueling and discharge lines, and the message

between the cavities of the vessels is made in the form of through holes in the upper part of the inner vessel.

New in the utility model is that the inner vessel is made with a volume determined from the ratio for real gas

where V _In - the volume of the cavity of the inner vessel;

V _B - the total volume of the cavities of the external and internal vessels;

ρ _W is the density of the cryogenic liquid;

R _ID is the gas constant of the ideal gas;

P _MAX - the maximum allowable gas pressure in the vessel;

T _MAX - the maximum allowable temperature of the gas in the vessel;

Z is the compressibility factor of a real gas, which is a function of pressure and temperature, where Z> 1.

The physical meaning of the fact that the inner vessel is made with a volume of V _B , determined from a given ratio for real gas, is that the inner and outer vessels are maximally filled with gas, i.e. at a given maximum temperature T _MAX , the gas pressure reached a predetermined maximum value P _MAX , which ensures maximum efficiency of the gas station and its reliability.

An important role in the presented formula is played by the compressibility coefficient Z, which at high gas pressures and normal temperature can significantly differ from unity. Without accounting for this difference when full volume V _B and the cryogenic fluid as a result of its gasification vessel pressure may exceed the maximum allowable value P _MAX.

During refueling, the density ρ _{Ж of the} cryogenic liquid does not change.

The presented analytical dependence for determining the value of the volume V _{B of the} inner vessel is obtained on the basis that: the mass charged into the inner vessel of the liquid M _W = ρ _W V _B is equal to the mass of the gas M _G = ρ _G V _B (at full gasification of the charged liquid, temperature T _MAX and pressure P _MAX );

- gas parameters are interconnected at temperature T _MAKS and pressure P _{MAX on the} equation of state of real gas (see page 361 of the book AM Arkharov et al. "Cryogenic systems. M. Engineering, 1987)

Then the volume of the inner vessel, based on the equality M _W = M _G and the expression for the presented ρ _G , is:

The parameters of this dependence in the SI system have dimensions: V _B and

- taking into account the difference in parameters between the real (compressibility coefficient Z> 1) and ideal (Z = 1) gases when choosing the volume of the internal vessel, at a given maximum gas pressure, it is possible to ensure complete filling of the device with cryogenic liquid.

Thus, the problem posed in the utility model of the most complete filling of the cylinder with cryogenic liquid was solved.

The present utility model is illustrated by the following cylinder description with reference to the drawing.

The cylinder contains an external pressure vessel 1 and an internal vessel 2 of volume V _B located in it, the cavity of which is connected to the refueling and discharge lines 3, 4. Message between cavities

vessels 1, 2 are made in the form of through holes 5 in the upper part of the inner vessel 2. The filling line 3 is connected through a tap to a container containing cryogenic liquid (not shown). At the exit of the highway 4 emptying also installed a crane.

The cylinder refueling and gasification of cryogenic liquid works as follows. Before starting work, the taps at the inlet and outlet of the cylinder are closed. When refueling the inner vessel 2, the valve of the refueling line 3 opens, and the cryogenic liquid from the tank (not shown) enters the inner vessel 2 through the refueling line 3. To accelerate the refueling and increase the mass of the liquid charged into the vessel, the pump can be turned on (not shown). In the process of filling the inner vessel 2 and after refueling due to a significantly higher temperature of its walls compared to the temperature of the liquid, evaporation of the liquid with increasing pressure occurs and gasified liquid through the holes 5 fills the entire volume of the inner 2 and outer 1 vessels. Refueling line 3 valve is closing. After the liquid has completely evaporated and turns into a high-pressure gas, the cylinder is ready for operation. At the same time, the crane of the emptying line 4 controls the gas supply to consumers (not shown).

In case of cryogenic filling of the cylinder for maximum filling of the inner vessel 2 (for example, with liquid hydrogen), which provides the maximum allowable mass of the gaseous product in the cylinder, it is necessary that the gasification process proceeds more slowly than filling the inner vessel 2 with liquid, i.e. gas pressure should be lower than that of incoming cryogenic liquid. In known, for example, hydrogen filling tanks, the maximum liquid pressure is 0.2-0.6 MPa. In addition, it is known that methane, which is a real gas, in many cases accounts for more than 95% of natural gas. Therefore, natural gas is also a real gas and its parameters are almost the same as those of methane. Options

real gas are interconnected by the equation of state P = Z (P, T) · ρ · R · T. An ideal gas differs from a real gas in that it has a compressibility coefficient Z = 1 for all values of the parameters P. and T. The value of the coefficient Z for different combinations of the parameters P. and T can be either smaller or larger. For example, according to V.A. Zagoruchenko, A.M. Zhuravleva (Thermophysical properties of gaseous and liquid methane. M. Publishing House of Standards, 1969, p. 22) for methane at ambient temperature T = 300 K, the table shows the values of the parameter Z (P).

It follows that at a temperature of gasified methane T = 300 K and a pressure P> 300-400 MPa, the compressibility factor Z> 1, which must be taken into account when choosing the volume of the device’s internal vessel, otherwise the gas pressure in the external vessel will be large given (according to the strength conditions ) of its maximum allowable value. The compressibility factor of a real gas is advisable to choose in the region in which Z> 1.

Other cryogenic fluids have similar trends in the dependence of the compressibility coefficient Z on pressure P and temperature T.

High pressure hydrogen is used in various fields. So, for example, it is used by unmanned aerial vehicles (UAVs) as fuel. For storage on board UAVs are placed cylinders with gaseous hydrogen of high pressure (up to 70 MPa) for its use in electrochemical generators. In this case, the filling of cylinders can be carried out with gasified hydrogen, obtained, in particular, using gasifiers of cryogenic liquid.

Claims (1)

A cylinder for refueling and gasification of cryogenic liquid, containing an external pressure vessel and an internal vessel of volume V _B located in it, the cavity of which is connected to the filling and discharge lines, and the communication between the vessel cavities is made in the form of holes in the upper part of the internal vessel, characterized in that the inner vessel is made with a volume determined from the ratio for real gas:

where V _In - the volume of the cavity of the inner vessel; V _B - the total volume of the cavities of the external and internal vessels; ρ _W is the density of the cryogenic liquid; R _ID is the gas constant of the ideal gas; P _MAX - the maximum allowable gas pressure in the vessel; T _MAX - the maximum allowable temperature of the gas in the vessels; Z is the compressibility factor of a real gas, which is a function of pressure and temperature and depends on its compressibility, where Z> 1.

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