RU2150057C1 - Installation with nitrogen screen for long-time storage of liquefied gases - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: installation has heat-insulated vessel filled with liquid gas and positioned in heat-insulated vessel with liquid nitrogen, and safety valve. Installation is provided with Stirling machine, with helium used as working medium and closed nitrogen circuit. It consists of gaseous nitrogen line with intake device, safety valve, throttle valve positioned upstream of Stirling machine, and liquefied nitrogen line with check valve which couple liquid nitrogen vessel with Stirling machine condenser. EFFECT: higher efficiency. 1 dwg

Description

 The invention relates to the field of cryogenic technology, cryogenic gas refrigeration machines with helium as a working fluid, operating on the reverse Stirling cycle, and storage of liquefied gases, for example, natural gas.

 It is known that various cycles are used for gas liquefaction, for example, with throttling or expander, however, in the range of cryogenic temperatures (60-160 K), the most highly efficient cycle is a cycle with a refrigerating machine operating according to the Stirling cycle. The efficiency of cryogenic Stirling machines is almost 2 times higher compared to other plants used for gas liquefaction (IP Usyukin Installations, machines and apparatuses of cryogenic technology. M: Light and food industry, 1982, pp. 185 - 186) .

 It is known that due to external heat inflows in tanks with cryogenic liquids, vapor is formed (vapor of liquefied gases), the amount of which depends on many factors: the shape of the tanks; types of insulation, etc. (RB Scott Low Temperature Technique. Translated by Prof. MP Malkov. M.: Publishing House of Foreign Literature, 1962, p. 250). However, the release of vapor outside the liquefied gas storage tank results in either the loss of a valuable product or environmental pollution.

It is known that liquefied natural gas is considered as a promising liquid fuel, and the boiling point of liquefied natural gases corresponds to a temperature of 162 ^o C (113 K) (Oil and Gas Vertical. Anal. Journal 9-10 (24 - 25), Moscow, 1998, p. . 123). However, there is a problem of highly efficient production and storage of liquefied natural gas as a cryogenic liquid.

 A device of the gas refrigerating machine Philips, operating on the reverse Stirling cycle, designed to liquefy air (Questions of deep cooling. / Collection of articles edited by prof. MP Malkov. M.: Foreign literature, 1961, p. 35 ) However, the use of liquid air in various technologies requires enhanced explosion and fire safety measures.

 Known designs of vessels for storing and transporting liquid gases with low evaporation losses based on a nitrogen screen include a vessel with liquid gas placed in a vessel with liquid nitrogen and a safety valve for the release of nitrogen vapor (RB Scott Low Temperature Technique Translation, edited by Prof. MP Malkov, Moscow: Publishing House of Foreign Literature, 1962, p. 257-258). However, these technical solutions do not address the issues of nitrogen conservation, and, therefore, the efficiency of the nitrogen screen will constantly decrease with the evaporation of liquid nitrogen and the release of its vapor into the environment.

 The technical result that can be obtained by carrying out the invention is to increase the efficiency of systems and reduce material costs during storage of liquefied gases.

 To achieve this technical result, the installation for long-term storage of liquefied gases with a nitrogen screen, consisting of a thermally insulated vessel with liquid gas, placed in a thermally insulated vessel with liquid nitrogen, and a safety valve for the release of nitrogen vapor, is equipped with a Stirling machine with helium as a working fluid, as well as a closed nitrogen circuit consisting of a nitrogen gas line with a suction device, a safety valve, a throttle valve in front of the chiller, and lines of liquefied nitrogen with a check valve connecting the vessel with liquid nitrogen to the condenser of the refrigeration machine.

 Introduction to the composition of the installation for long-term storage of liquefied gases with a nitrogen screen, a Stirling refrigeration machine and a closed nitrogen circuit from lines with gaseous and liquefied nitrogen connecting the vessel with liquid nitrogen to the condenser of the refrigeration machine allows us to obtain a new property, which consists in the condensation of vapor (vapor ) nitrogen (nitrogen screen) in the condenser of the refrigeration machine with its subsequent discharge into a vessel with liquid nitrogen, due to heat exchange with the working fluid of the refrigeration machine.

 The drawing shows an installation for long-term storage of liquefied gases with a nitrogen screen.

 The installation includes a Stirling refrigeration machine 1, with a working fluid helium, a closed nitrogen circuit connecting a thermally insulated vessel with liquid nitrogen 2 to a condenser (not shown) of a refrigeration machine 1. A thermally insulated vessel with stored liquid is located inside a vessel with liquid nitrogen 2 gas 3. The closed loop consists of a line of liquefied nitrogen 4, with a check valve 5, and a line of gaseous nitrogen 6 with a suction device 7, a safety valve 8 and a throttle valve 9.

 Installation for long-term storage of liquefied gases with a nitrogen screen works as follows.

 The liquid gas in the vessel 3 is protected from external heat influx by a layer of liquid nitrogen located in the heat-insulated vessel 2. In turn, nitrogen vapor is formed in the upper part of the vessel 2 due to external heat inflows. When a certain pressure is reached, the safety valve 8 is activated, which serves as a signal to turn on the chiller 1. As a result, through line 6 high-pressure nitrogen gas through the intake device 7, the safety valve 8 enters the throttle valve 9 located in front of the condenser of the chiller 1, passing through which it is pre-cooled and then fed into a condenser (not shown) of the Stirling refrigeration machine 1, where it is condensed. The transition of nitrogen vapor into the liquid phase in the condenser of the refrigeration machine 1 creates the necessary pressure difference in line 6. Then, the liquefied nitrogen through line 4 through the check valve 5 is discharged into the insulated container 2 in the form of liquefied gas.

Sources of information taken into account when preparing the application:
1. Usyukin I.P. Installations, machines and apparatuses of cryogenic equipment. - M.: Light and food industry, 1982, p. 185 - 186.

 2. R. B. Scott Low Temperature Technique. Translation Ed. prof. M.P. Malkova, M .: publishing house of foreign literature, 1962, p. 250.

 3. Oil and gas vertical. Analytical journal 9-10 (24-25), M., 1998, p. 123.

 4. Issues of deep cooling. / Sat. articles edited by prof. M.P. Malkova. M .: Foreign literature, 1961, p. 35.

 5. R. B. Scott Low Temperature Technique. Translation Ed. prof. M.P. Malkova. M .: Publishing house of foreign literature, 1962, p. 257 - 258 - prototype.

Claims (1)

 Installation for long-term storage of liquefied gases with a nitrogen screen, consisting of a thermally insulated vessel with liquid gas, placed in a thermally insulated vessel with liquid nitrogen, and a safety valve for the release of nitrogen vapor, characterized in that it is equipped with a Stirling refrigeration machine with helium as a working fluid and closed a nitrogen circuit consisting of a nitrogen gas line with a suction device, a safety valve, a throttle valve in front of the chiller, and a liquefied nitrogen line with a return valve connecting the vessel with liquid nitrogen to the condenser chiller.