RU2151981C1 - Cryogenic system for air liquefaction - Google Patents

Abstract

FIELD: cryogenic equipment for air liquefaction. SUBSTANCE: air liquefaction cycle includes the following processes: compression of primary air in the compressor, air cleaning, precooling in the heat exchanger, separation of air into two flows, expansion of the first flow in an expansion machine with generation of useful power in the electric generator, throttle expansion of the second flow with subsequent partial condensation, joining of the non-condensed part of air of the second flow with the first flow, their preheating with pressure rise in the heat exchanger, expansion in the turbine with generation of useful power, liquefaction in the condenser of the cryogenic stirling machine and feeding of liquefied air through the Dewar flask to the vessel for liquid air by means of the high-pressure pump. Transition of gaseous air to the liquid phase in the evaporator of the refrigerating machine builds up the necessary pressure differential in the gaseous air line. EFFECT: enhanced system efficiency. 1 dwg

Description

 The invention relates to the field of cryogenic air liquefaction techniques and cryogenic refrigeration machines operating on the reverse Stirling cycle.

 Known technical solutions of gas turbines, in which the energy of compressed gas during expansion is converted into work simultaneously with a decrease in gas temperature. (Chechetkin A.V., Zanemonets N.A. Heat engineering. Textbook for chemical and technical special universities. - M.: Higher school, 1986. - p. 307).

 Known technical solutions for the gasification of liquefied gases before distributing them to consumers using high pressure pumps (Questions of deep cooling. / Collection of articles edited by prof. MP Malkov /. Ed .: "Foreign Literature", M., 1961 , p. 287-288).

 A device of the Dewar vessel for liquid nitrogen with vacuum-powder insulation is known (Sokolov E.Ya., Brodyansky V.M. Energy fundamentals of heat transformation and cooling processes. Textbook for universities. - 2nd ed., - M.: Energoizdat 1981, p. 202).

 It is known that in the region of cryogenic temperatures (60–160 K), the reverse Stirling cycle is the most highly efficient 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 equipment. M: Light and food industry, 1982, p. 185-186). However, the currently existing cryogenic Stirling machines have low productivity.

 A known scheme for air liquefaction in a Claude cycle with high productivity, including a primary air supply line, a compressor, a purifier, a counterflow heat exchanger, an expansion machine, a throttle valve, a container with liquid air, a non-condensed air supply line connecting the container with liquid air and a compressor. (RB Scott. The technique of low temperatures. Translation under the editorship of prof. MP Malkov. M: Publishing House of Foreign Literature, 1962, p. 21-22). However, the Claude cycle has a low efficiency and liquefaction coefficient, as a result of which only part of the air compressed by the compressor liquefies, and the remaining part of the gaseous air is again supplied to the compressor.

 The technical result that can be obtained by carrying out the invention is to increase the efficiency of the liquefaction system and increase the liquefaction coefficient to 100%.

 To achieve this technical result, a cryogenic system for liquefying air, which includes an air supply line, a compressor, a purifier, a counterflow heat exchanger, an expansion machine, a throttle valve, a container with liquid air, is equipped with a cryogenic Stirling machine with a working fluid - helium and a closed air condensation circuit, connecting the liquid air tank with the condenser of the refrigeration machine and consisting of a line of gaseous air with a suction device in the gas-containing part of the tank, expansion turbine with an electric generator on one shaft and the liquefied air line with a Dewar vessel, high pressure pump and the check valve, the gaseous air line passes through a counterflow heat exchanger and, if necessary, the system may include several parallel cryogenic Stirling machines.

The introduction of an expansion turbine with an electric generator on one shaft and a liquefied air line with a Dewar vessel, a high pressure pump, and a check valve into the cryogenic system for liquefying air, while the gaseous air line passes through a counterflow heat exchanger, and, if necessary, the system can be several cryogenic Stirling machines are included in parallel, as well as
the introduction of the cryogenic system for liquefying the air of a cryogenic Stirling machine with a working fluid - helium and a closed loop of air condensation with an expansion turbine connecting the liquid air capacity to the condenser of the refrigeration machine allows to obtain a new property, which consists in the possibility of post-expansion of the remaining part of gaseous air after its expansion in the throttle valve, in the capacitor of the highly efficient cryogenic Stirling machine, as well as reducing the energy consumption of the system as a whole due to the use of IAOD expansion machines to produce useful energy in it.

 The drawing shows a cryogenic system for liquefying air.

 The air liquefaction cycle includes the following processes: air compression in the compressor, air purification, pre-cooling in a counterflow heat exchanger, separation of air into two flows, expansion of the first air stream in an expansion machine to produce useful energy, throttle expansion of the second stream followed by partial condensation air (Joule-Thomson effect) and discharge into a container with liquid air, the connection of the non-condensed part of the air of the second stream with the first stream, their heating with increasing pressure expansion in an expansion turbine to produce useful energy, cryogenic liquefaction in the condenser of the Stirling machine and the supply of liquefied air to the liquid air tank.

 The cryogenic system for liquefying air includes an air supply line 1, a compressor 2, an air purifier 3, a counterflow heat exchanger 4, an expansion machine, for example, a turbine 5 with an electric generator 6, a throttle valve 7, a container with liquid air 8, a cryogenic Stirling refrigeration machine 9, a closed loop of air condensation connecting the tank with liquid air 9 with a condenser (not shown) of the Stirling machine 9. A closed loop of condensation of air consists of a line of gaseous air 10 with a intake device 11 in the gas-containing part of the tank 8, the expansion turbine 12, located on the same shaft with the electric generator 13 and the liquefied air line 14 with the Dewar vessel 15, high pressure pump 16 and check valve 17.

 A cryogenic system for liquefying air works as follows.

 The primary air through the supply line 1 enters the compressor 2, where it is compressed to high pressure and enters the purifier 3 for cleaning impurities. Then it is pre-cooled in a counterflow heat exchanger 4 due to heat exchange with cold air and is divided into two streams. The first air stream is supplied to the turbine 5, where it expands to produce useful energy in the electric generator 6, and the second stream, passing through the throttle valve 7, partially condenses and merges into the tank 8. The remaining part of the non-condensed cold air of the second stream through the gaseous air line 10 through the intake the device 11 is connected to the air of the first stream and first enters the counterflow heat exchanger 4, where it cools the primary air, while it heats up with increasing pressure, and then enters iritelnuyu turbine 12, passing through which it expanded, cooled and enters the condenser (not shown) of the Stirling chiller 9, where it is condensation. The expansion of air in the turbine 12 allows you to receive electricity in an electric generator 13 located on the same shaft with the turbine 12. The transition of gaseous air into the liquid phase in the condenser of the chiller 9 creates the necessary pressure difference in line 10 in front of the turbine 12. Then the liquefied remaining air is discharged through line 14 in the Dewar vessel 15 and the high pressure pump 16 through the check valve 17 is fed into the tank 8 in the form of a liquid.

Sources of information
1. Chechetkin A. V., Zanemonets N. A. Heat engineering. Textbook for chemical technol. specialist. universities. - M .: Higher. school, 1986. - p. 307.

 2. Issues of deep cooling. / Sat articles edited by prof. M.P. Malkova. Publisher: "Foreign Literature". M., 1961, p. 287-288.

 3. Sokolov E. Ya., Brodyansky V. M. Energy fundamentals of heat transformation and cooling processes. Textbook manual for universities. - 2nd ed. - M.: Energoizdat, 1981, p. 202.

 4. Usyukin I.P. Installations, machines and apparatuses of cryogenic equipment. M .: Light and food industry, 1982, pp. 185-186.

 5. Issues of deep cooling. / Sat articles edited by prof. M.P. Malkova. Publisher: "Foreign Literature". M., 1961, p. 35.

 6. R. B. Scott. Technique of low temperatures. Translation Ed. prof. M.P. Malkova. M .: Publishing. foreign letter., 1962, p. 21-22, - prototype.

Claims (1)

 A cryogenic system for liquefying air, which includes an air supply line, a compressor, a purifier, a counterflow heat exchanger, an expansion machine, a throttle valve, a container with liquid air, characterized in that it is equipped with a cryogenic Stirling machine with a working fluid-helium and a closed air condensation circuit, connecting the tank of liquid air with the condenser of the refrigeration machine and consisting of a line of gaseous air with a suction device in the gas-containing part of the tank, an expansion turbine with an electric generator one shaft, and a liquefied air line with a Dewar vessel, a high pressure pump and a check valve, while the gaseous air line passes through a counterflow heat exchanger, and the system is equipped with at least one cryogenic Stirling machine.