JP4577977B2 - Air liquefaction separation method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air liquefaction separation method and apparatus, and more specifically, an air liquefaction separation method for collecting nitrogen, argon, oxygen, etc. from air as a product by low-temperature liquefaction distillation of air using a heat exchange distiller. And an apparatus.
[0002]
[Prior art]
Currently, in order to produce nitrogen, argon, oxygen, etc. by low-temperature distillation of air, generally, a double distillation column composed of a high-pressure column and a low-pressure column and an argon column connected as a side column to the low-pressure column are combined. An air liquefaction separation apparatus consisting of three distillation columns is used. However, in recent years, due to the demands of the times, there has been a strong demand for reduction in power consumption and downsizing of equipment, and a method and equipment using a heat exchange-type distiller have been proposed for that purpose. .
[0003]
For example, Japanese Patent No. 2833594 discloses a method for producing medium purity oxygen (85 to 99%). Here, a plate fin heat exchanger having two sets of passages is used as a heat exchange type distiller, the raw air gas is distilled in the one set of passages, and a nitrogen-rich product is placed in the upper portion of the passages. In the other set of passages, stripping is performed using an oxygen-rich liquid as a raw material to separate the nitrogen-rich product in the upper part and the oxygen in the lower part. I try to get oxygen as a product.
[0004]
Japanese Patent Application Laid-Open No. 11-153383 discloses a method and apparatus for producing high-purity nitrogen gas while minimizing the power consumption while limiting the power consumption to the maximum using a heat exchange type distiller. . Here, a three-pass heat exchange distiller is used, the air reflux is reboiled in the lower part of the distillation passage, and the nitrogen-rich gas is shrunk in the upper part, thereby enabling miniaturization. It is shown.
[0005]
[Problems to be solved by the invention]
However, in the combination of such a distillation column and a heat exchange type distiller, the reduction of the power consumption and the downsizing of the apparatus are still insufficient, and it has been produced using a heat exchange type distiller. Products to be produced are limited to nitrogen and oxygen, and it is required to collect nitrogen, oxygen and argon.
[0006]
Therefore, the present invention uses not only nitrogen and oxygen but also argon as a product while reducing power consumption and downsizing the apparatus by using the nitrogen gas separated in the distillation tower as a heat medium of the heat exchange type distillation apparatus. An object of the present invention is to provide an air liquefaction separation method and apparatus that can be collected and that can further reduce power consumption by circulating and using the nitrogen gas.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the air liquefaction separation method according to the present invention introduces compressed, purified, and cooled raw material air into a distillation column, and performs low-temperature distillation in the distillation column, whereby nitrogen gas at the top of the column and nitrogen at the bottom of the column are separated. And the crude liquefied oxygen led out from the distillation column is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, The temperature of the nitrogen gas derived from the distillation column is raised, and a part of the nitrogen gas is pressurized, and then cooled again, and then introduced as a descending gas into the condensation passage of the heat exchange distillation apparatus, and the fluid in the distillation passage It is condensed by heat exchange to form liquefied nitrogen, and the liquefied nitrogen is decompressed before being used as the reflux liquid of the distillation column. The nitrogen gas and the crude liquefied oxygen are heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the falling liquid are brought into gas-liquid contact in the distillation passage. Nitrogen gas containing oxygen is separated in the upper part of the passage, and liquefied oxygen is separated in the lower part of the distillation passage, and the liquefied oxygen is collected as product oxygen.
[0008]
Furthermore, the air liquefaction separation method of the present invention comprises: The compressed, purified, and cooled raw material air is introduced into the distillation column, and is separated into crude liquefied oxygen containing nitrogen gas at the top of the column and nitrogen at the bottom of the column by low-temperature distillation in the distillation column, and then derived from the distillation column. The crude liquefied oxygen is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and the nitrogen gas derived from the distillation column is introduced into the condensing passage of the heat exchange type distiller as a descending gas. The crude liquefied oxygen is heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the descending liquid are brought into gas-liquid contact in the distillation passage so as to be in the upper part of the distillation passage. Nitrogen gas containing oxygen is separated into liquefied oxygen at the lower part of the distillation passage, and the liquefied oxygen is collected as product oxygen; Derived as liquid coarse liquefied argon from the distillation tower, introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and raised by vaporizing a part of the coarse liquefied argon by heat exchange with nitrogen gas in the condensation passage Gas, and ascending gas and falling liquid are brought into gas-liquid contact in the distillation passage to separate nitrogen gas containing argon in the upper portion of the distillation passage and liquefied argon in the lower portion of the distillation passage, respectively. Is collected as product argon, and nitrogen gas containing argon at the top is reintroduced into the distillation column.
[0009]
Further, in the method of the present invention, instead of the nitrogen gas, a part of the cooled raw air can be introduced as a descending gas into the condensation passage of the heat exchange type distiller. wear .
[0010]
Furthermore, high-pressure product oxygen gas can be obtained by increasing the pressure of the liquefied oxygen derived from the distillation passage and then evaporating it. The cold necessary for operation can be obtained by adiabatically expanding at least one part of the source air and the separation gas, and the source air is secondarily compressed using the expansion work generated by the adiabatic expansion. You can also.
[0011]
In addition, instead of deriving the crude liquefied argon from the distillation column, it is derived as a gaseous crude argon gas, and the derived crude argon gas is introduced into the argon distillation column and further subjected to low-temperature distillation to form nitrogen gas. The liquefied argon can be separated into the liquefied argon, and the separated liquefied argon can be introduced into the distillation passage of the heat exchange type distiller as a descending liquid.
[0012]
The air liquefaction separation apparatus of the present invention includes a raw material air compressor that compresses raw material air, a purifier that removes impurities that solidify at a low temperature, such as moisture and carbon dioxide, contained in the compressed raw material air, A main heat exchanger for cooling the raw material air, a distillation tower for separating the cooled raw air into nitrogen gas and crude liquefied oxygen by low-temperature distillation, and a heat-exchange distiller having a distillation passage and a condensation passage The heat exchange-type distiller is configured to perform gas exchange by heat exchange between a path for introducing the crude liquefied oxygen separated by the distillation column as a descending liquid into the distillation passage and a fluid flowing through the condensation passage in the distillation passage. A route for deriving nitrogen gas containing oxygen that has been converted to an upper portion of the distillation passage and a route for deriving liquefied oxygen lowered to the lower portion of the distillation passage as product oxygen, A path for introducing a part of the nitrogen gas derived from the upper part of the distillation column into the main heat exchanger, and a path for deriving the nitrogen gas heated in the main heat exchanger and introducing it into the circulating nitrogen compressor; A path for introducing compressed nitrogen gas compressed by the circulating nitrogen compressor into the main heat exchanger, and a condensed passage of the heat exchanger type distiller by extracting compressed nitrogen gas cooled by the main heat exchanger In Liquefied nitrogen that has been liquefied by heat exchange between the path to be introduced as the descending gas and oxygen flowing through the distillation path in the condensing passage and descended to the lower part of the condensing passage And then introduced as reflux into the top of the distillation column after decompression It is characterized by having a route to perform.
[0013]
Further, the air liquefaction separation apparatus of the present invention derives crude argon containing nitrogen generated in the middle of the tower when the raw air is subjected to low-temperature distillation in the distillation tower from the distillation tower as liquid crude liquefied argon, and the heat exchange A nitrogen gas containing argon that has been vaporized by heat exchange between a passage for introducing a descending liquid into a part of a distillation passage of the mold distiller and a fluid flowing through the condensation passage in the distillation passage and has risen to the upper portion of the distillation passage. It is characterized in that there are provided a route for leading out and a route for collecting the liquefied argon descending at the lower part of the distillation passage as product argon.
[0014]
Further, as means for introducing the crude liquefied argon into the distillation passage, an argon distillation tower for separating the crude argon gas into nitrogen gas and crude liquefied argon by low-temperature distillation is provided, and the argon distillation tower is provided with a tower of the distillation tower. The crude argon produced in the middle is led out as gaseous crude argon gas, the path for introducing it into the argon distillation column, the path for leading out the nitrogen gas separated in the argon distillation tower, and the separated crude liquefied argon in the distillation It is possible to employ a route for introducing the liquid into the passage as a descending liquid.
[0015]
Furthermore, a gas-liquid separator is provided in the lower part of the distillation passage, and a liquefied oxygen supply pump for supplying the crude liquefied oxygen derived from the distillation column to the distillation passage of the heat exchange type distillation device is provided. It is characterized by having a liquefied oxygen pressurizing pump that pressurizes liquefied oxygen derived from the distillation passage of the heat exchange type still.
[0016]
In addition, instead of nitrogen, the condenser passage is liquefied by heat exchange between a path for introducing a part of the cooled raw material air as a descending gas to the condensation passage and a fluid flowing through the distillation passage in the condensation passage. And a path for leading the liquefied air descending to the lower part of the condensing passage.
[0018]
A path through which a part of the pressurized nitrogen gas is branched from the middle of the main heat exchanger and introduced into the expansion turbine; and the low-temperature nitrogen gas that is adiabatically expanded by the expansion turbine to generate cold is supplied to the main heat exchanger. A path for introducing the raw air from the middle of the main heat exchanger, and a secondary air compressor for low-temperature compression of the raw air led to the path, The secondary air compressor is generated by expansion work generated by adiabatic expansion in the expansion turbine, or by adiabatic expansion in an air expansion turbine that adiabatically expands high-pressure raw material air compressed at low temperature by the secondary air compressor. It is characterized by being driven by using the expanding work.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system diagram showing a first embodiment of the air liquefaction separation apparatus of the present invention, and FIG. 2 is a partial sectional perspective view showing one embodiment of a heat exchange type distiller used in the present invention.
[0020]
This air liquefaction separation apparatus is solidified at a low temperature such as moisture and carbon dioxide contained in the compressed raw material air, a raw air compressor 1 that compresses the raw material air, an air precooler 2 that removes the compression heat of the compressed air, and A purifier 3 for removing impurities, a main heat exchanger 4 for cooling the purified raw material air by heat exchange with a fluid obtained by low-temperature distillation, and a distillation column 5 for low-temperature distillation of the cooled raw material air A heat exchange type distiller 6 having an oxygen distillation passage (oxygen distillation passage) 61, an argon distillation passage (argon distillation passage) 62, and a nitrogen condensation passage (nitrogen condensation passage) 63; and a nitrogen circulation passage. The circulating nitrogen compressor 7 to be formed and the expansion turbine 8 that generates cold are the main constituent devices, and the low-temperature specification devices are housed in the cold storage tank 9.
[0021]
The oxygen distillation passage 61 and the argon distillation passage 62 in the heat exchange-type distiller 6 are in a heat exchange relationship with the nitrogen condensation passage 63, respectively, and the oxygen distillation passage 61 and the argon distillation passage 62 are heated and nitrogen condensed. The passage 63 is the cooled side. In FIG. 1, each passage 61, 62, 63 is shown by a single line for simplification of the drawing, but an actual heat exchange type distiller 6 has a configuration as shown in FIG. 2. It has become.
[0022]
The heat exchange type distiller 6 shown in FIG. 2 uses a plate fin type heat exchanger 10 as the heat exchange type distiller 6, and is condensed with the distillation passage 12 by a large number of partition plates 11 installed in the vertical direction. The passages 13 are alternately stacked, and a distillation passage for leading the gas vaporized in the distillation passage 12 and a distillation passage liquid introduction header 14 for introducing crude liquefied oxygen or coarse liquefied argon into the distillation passage 12 at the upper part of the heat exchanger. The gas outlet header 15 is provided at the lower part of the heat exchanger so that the distillation passage liquid outlet header 16 for leading the liquid (liquefied oxygen, liquefied argon) descending in the distillation passage 12 communicates with the distillation passage 12. In addition, a condensation passage gas introduction header 17 for introducing nitrogen gas into the condensation passage 13 is provided at the upper side of the heat exchanger side, and a condensation passage for deriving liquefied nitrogen liquefied in the condensation passage 13 is provided at the lower portion. The liquid outlet header 18 is provided so as each to communicate with the condensate passage 13. In addition, a liquid distributor 19 is provided at the upper part of the distillation passage 12 to allow the liquid to flow uniformly into each distillation passage 12, and the oxygen side and the argon side are separated by a wall plate 11 a orthogonal to the partition plate 11. It has been. Furthermore, piping which constitutes each route described later is connected to each of these headers.
[0023]
Hereinafter, a procedure for obtaining nitrogen, oxygen and argon by cryogenic liquefaction separation of air will be described with reference to FIG. First, the raw material air is compressed to a predetermined pressure by the raw material air compressor 1 and cooled to room temperature by the air precooler 2, and then impurities such as moisture and carbon dioxide in the raw material air are adsorbed and removed by the purifier 3. The The purified raw material air flows into the cold insulation tank 9 from the path 21 and is cooled to a predetermined temperature by exchanging heat with a low-temperature fluid composed of a product gas and exhaust gas described later in the main heat exchanger 4. Further, the raw air passes through the supercooler 23 from the path 22 and is introduced into the middle lower part of the distillation column 5 via the path 24.
[0024]
The raw material air introduced into the distillation column 5 rises while enriching the nitrogen component, which is a low-boiling component, by gas-liquid contact with the reflux liquid descending in the column, and nitrogen gas is separated at the top of the column. This nitrogen gas is led out to the path 25 from the upper part of the distillation column 5, is introduced into the main heat exchanger 4 through the supercooler 23 and the path 26, and after being heated, is collected as nitrogen gas GN from the path 27.
[0025]
On the other hand, the reflux liquid flowing down the distillation column 5 flows down while enriching the oxygen component which is a high-boiling component by gas-liquid contact with the rising gas rising in the column, and the crude liquefied oxygen containing nitrogen content at the bottom of the column Is separated. The crude liquefied oxygen is led out to the path 31 from the lower part of the distillation column 5, and after the pressure is increased to a predetermined pressure by the liquefied oxygen supply pump 32, the liquefied oxygen descends into the oxygen distillation passage 61 of the heat exchange distiller 6 via the path 33. As introduced.
[0026]
The crude liquefied oxygen flowing down in the oxygen distillation passage 61 is heated by exchanging heat with the fluid flowing through the adjacent nitrogen condensation passage 63, that is, nitrogen gas, and a part of the crude liquefied oxygen is vaporized, and the oxygen distillation passage 61 is heated. Rise inside. At this time, since nitrogen, which is a low-boiling component, in the crude liquefied oxygen is vaporized more, the descending liquid is brought into gas-liquid contact in the process of rising in the oxygen distillation passage 61, and the oxygen distillation passage 61 is enriched while enriching the nitrogen content. It is led out from the path 34. The nitrogen gas containing a small amount of oxygen is returned to the lower part of the distillation column 5 and becomes a rising gas.
[0027]
In addition, the falling liquid that descends without being vaporized in the oxygen distillation passage 61 flows down while enriching oxygen, which is a high-boiling component, and becomes liquefied oxygen in the lower part of the oxygen distillation passage 61. The liquefied oxygen is extracted into the path 35 and introduced into the gas-liquid separator 36. The liquefied oxygen separated from the gas and liquid is vaporized through the main heat exchanger 4 from the path 37 and heated up, and then the path 38. Is collected as oxygen gas GO. At this time, as shown by a broken line in FIG. 1, a liquefied oxygen boost pump 39 is provided in the path 38, and the pressure is increased by the liquefied oxygen boost pump 39 and then vaporized by the main heat exchanger 4. Product oxygen gas can be obtained.
[0028]
Further, the nitrogen gas introduced into the nitrogen condensing passage 63 of the heat exchange type distiller 6 branches a part of the nitrogen gas extracted from the upper part of the distillation column 5 into the path 25 to the path 41 and circulates this nitrogen gas. I am trying to use it. That is, the nitrogen gas branched into the path 41 is heated by the main heat exchanger 4 to normal temperature, led out from the cold storage tank 9 through the path 42, and compressed to a predetermined pressure by the circulating nitrogen compressor 7. . After the compression heat is removed by the nitrogen precooler 43, the compressed nitrogen gas is again introduced into the cold insulation tank 9 through the path 44 and is cooled again to a predetermined temperature by the main heat exchanger 4. The cooled compressed nitrogen gas is introduced as a descending gas into the nitrogen condensing passage 63 of the heat exchange-type distiller 6 through the passage 45 and exchanges heat with the fluid flowing through the adjacent oxygen distillation passage 61 and the argon distillation passage 62. .
[0029]
At this time, the compressed nitrogen gas flowing down the nitrogen condensing passage 63 is set to a high temperature by increasing the pressure, and the crude liquefied oxygen and the rough flowing through the oxygen distillation passage 61 and the argon distillation passage 62 adjacent to the nitrogen condensing passage 63 are set. Since the temperature is higher than that of liquefied argon, it acts as a reboyl gas source for vaporizing the liquefied oxygen and the liquefied argon. Therefore, the compressed nitrogen gas is cooled by applying heat to the crude liquefied oxygen and the crude liquefied argon flowing through the oxygen distillation passage 61 and the argon distillation passage 62 respectively while flowing down the nitrogen condensing passage 63. It condenses and becomes liquefied nitrogen and flows out from the lower part of the nitrogen condensing passage 63 to the path 46. The liquefied nitrogen in the path 46 is led out to the path 47 through the supercooler 23, and after being depressurized to near the operating pressure of the distillation column 5 by the pressure reducing valve 48, is returned as a reflux liquid from the path 49 to the upper portion of the distillation column 5. .
[0030]
Further, a part of the compressed nitrogen gas introduced into the main heat exchanger 4 from the path 44 is branched into the path 51 from the middle of the main heat exchanger 4 and introduced into the expansion turbine 8, and is insulated by the expansion turbine 8. The expansion generates the cold necessary for the operation of the device. The low-temperature nitrogen gas having obtained the cold is led out from the expansion turbine 8 to the path 52, merges with the nitrogen gas in the path 26, flows into the main heat exchanger 4, and is led out from the path 27 after being heated.
[0031]
Furthermore, in the present embodiment, in order to collect argon, crude liquefied argon composed of substantially nitrogen and argon is led out from the middle upper part of the distillation column 5 to the path 71, and is fed to the argon distillation passage 62 of the heat exchange type distiller 6. It is introduced as a descending liquid. The crude liquefied argon, like the crude liquefied oxygen, exchanges heat with the nitrogen gas flowing through the adjacent nitrogen condensation passage 63, and partly vaporizes and rises while enriching the nitrogen content in the argon distillation passage 62. The nitrogen gas containing a small amount of argon is led out to the path 72 and returned to the upper part of the distillation column 5 to become the rising gas.
[0032]
Further, the falling liquid in the argon distillation passage 62 flows down while enriching argon, which is a high-boiling component, and becomes liquefied argon, which is extracted from the lower portion of the argon distillation passage 62 to the passage 73, and the gas-liquid separator 74 is connected to the argon distillation passage 62. Then, it is collected from the path 75 as product liquefied argon LAr.
[0033]
FIG. 3 is a system diagram showing a second embodiment of the air liquefaction separation apparatus of the present invention. In the following description, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof is omitted.
[0034]
In the present embodiment, a crude argon gas composed of substantially nitrogen and argon is led out from the middle upper part of the distillation column 5 to the path 81 and introduced into the argon distillation tower 82 to be separated into nitrogen gas and crude liquefied argon. The crude liquefied argon separated into (3) is introduced as a descending liquid into the argon distillation passage 62 of the heat-exchange distiller 6 from the path 83, and nitrogen gas containing a small amount of argon that has risen through the argon distillation path 62 is argon distilled from the path 84 The rising gas is returned to the lower part of the tower 82. Further, liquefied nitrogen branched from the path 49 to the path 85 is introduced as a reflux liquid in the upper part of the argon distillation column 82, and the nitrogen gas separated in the upper part of the tower is led out to the path 86 and joined to the path 25. .
[0035]
That is, in the argon distillation column 82, low-temperature distillation is performed with the crude argon gas introduced as the rising gas at the lower part of the tower and the liquefied nitrogen introduced as the reflux liquid at the upper part of the tower. As a result of the contact, the rising gas rises in the tower while enriching nitrogen, which is a low-boiling component, and the reflux liquid descends in the tower, while enriching argon, which is a high-boiling component. As a result, nitrogen gas is separated at the upper part of the tower and crude liquefied argon is separated at the lower part of the tower.
[0036]
The crude liquefied argon introduced as a descending liquid from the argon distillation column 82 to the argon distillation passage 62 is heated by nitrogen gas flowing through the nitrogen condensation passage 63 in the same manner as described above. A certain amount of nitrogen is vaporized, and the vaporized gas rises in the argon distillation passage 62 while being enriched with nitrogen, and is returned to the argon distillation column 82. On the other hand, the liquid that descends the argon distillation passage 62 without being vaporized reaches the lower portion of the argon distillation passage 62 while enriching argon, which is a high boiling point component, and passes through the path 73, the gas-liquid separator 74, and the path 75 to liquefy the product liquefied argon. Collected as LAr.
[0037]
FIG. 4 is a system diagram showing a third embodiment of the air liquefaction separation apparatus of the present invention. In the present embodiment, the raw material air purified by the purifier 3 and introduced into the main heat exchanger 4 from the path 21 is led to the path 91 from the middle of the main heat exchanger 4 and then the two secondary airs. The air is introduced into the air compressor 92 and compressed at a low temperature to a predetermined pressure. The low-pressure compressed high-pressure raw material air is again introduced into the main heat exchanger 4 through the path 93 and cooled, and then branched into a path 94 and a path 95. The high-pressure raw material air in the path 94 is freely expanded by the pressure reducing valve 96 to become low-temperature air, and then is introduced from the path 97 through the supercooler 23 and into the distillation column 5 through the path 24. Further, the high-pressure raw material air branched into the path 95 is introduced into the air expansion turbine 98 and adiabatically expanded to become low-temperature air. After being led out to the path 99, it joins with the low-temperature air in the path 97 and enters the distillation column 5. be introduced.
[0038]
Further, a part of the compressed nitrogen gas compressed by the circulating nitrogen compressor 7 branches from the path 44 to the path 53 and is introduced into the expansion turbine 8 and adiabatically expands to become low-temperature nitrogen gas, which is led to the path 54. The This low-temperature nitrogen gas merges with the nitrogen gas introduced into the main heat exchanger 4 from the path 26 in the middle of the main heat exchanger 4, and the cold is recovered and led out from the path 27.
[0039]
The secondary air compressor 92 is driven by using expansion work generated by adiabatic expansion in the expansion turbine 8 and the air expansion turbine 98, so that cold can be generated effectively and power consumption is increased. The amount can be reduced.
[0040]
Here, in the oxygen distillation passage 61 of the heat exchange-type distiller 6, a part of the crude liquefied oxygen supplied to the oxygen distillation passage 61 is gasified by receiving heat supply from the nitrogen gas flowing through the nitrogen condensation passage 63. To generate rising gas. The flow rate of the nitrogen gas flowing through the nitrogen condensing passage 63 is determined by making the amount of heat of vaporization of the crude liquefied oxygen and the amount of heat of liquefaction of the nitrogen gas flowing through the nitrogen condensing passage 63 commensurate with the amount of the rising gas generated here. .
[0041]
At this time, the flow rate of nitrogen gas in the nitrogen condensing passage 63 can be arbitrarily set by circulating the nitrogen gas as described above, so that the amount of coarsely liquefied oxygen can also be arbitrarily set. Since this crude liquefied oxygen is supplied as a descending liquid to the upper part of the heat exchange type distiller 6, it corresponds to a reflux liquid in the oxygen distillation passage 61. Therefore, the amount of reflux liquid can be set arbitrarily, the reflux ratio can be increased, and the internal reflux ratio of the oxygen distillation passage 61 can be increased. Further, in the conventional air liquefaction separation apparatus, the argon-oxygen mixed gas is side-cut from the low-pressure column in order to recover argon, whereas in the present invention, the nitrogen / argon-based mixed gas having a large relative volatility is used. Since the mixed fluid can be side-cut from the distillation column 5, distillation in the argon distillation passage 62 and the argon distillation column 82 can be dramatically accelerated. Thereby, nitrogen gas, liquefied argon, and oxygen gas can be efficiently recovered as a product with the apparatus configuration reduced in size by reducing the height of the apparatus.
[0042]
In each embodiment, the crude liquefied oxygen derived from the lower part of the distillation column 5 is supplied to the oxygen distillation passage 61 by the liquefied oxygen supply pump 32. However, the positional relationship between the distillation column 5 and the heat exchange type distiller 6 is used. Depending on the case, the liquefied oxygen supply pump 32 can be omitted. Moreover, the introduction position of the raw material air to the distillation column 5 is arbitrary, and may be introduced to the lower portion of the column. Furthermore, it is possible to introduce a part of the raw air instead of nitrogen gas into the condensing passage 63 of the heat exchange type distiller 6 as a reboil gas source, and the liquefied air is placed at an appropriate position in the distillation column 5. It can be introduced as a descending liquid.
[0043]
【Example】
An operation of collecting nitrogen, oxygen, and argon was performed using the first embodiment apparatus having the configuration shown in FIG. First, after the raw material air compressed to 170 kPa by the raw material air compressor 1 is cooled to room temperature by the air precooler 2, the impurities are adsorbed and removed by the purifier 3, and then the gas-liquid at about −190 ° C. by the main heat exchanger 4. After cooling to a two-phase state, it was introduced into the distillation column 5. As a result of the low temperature distillation in the distillation column 5, nitrogen gas having a nitrogen concentration of 99.99% or more and an oxygen content of 1 ppb or less was obtained from the top of the column.
[0044]
The crude liquefied oxygen in the lower part of the tower is introduced as a descending liquid (reflux) into the upper part of the oxygen distillation passage 61 of the heat exchange-type distiller 6, and is subjected to heat exchange with the circulating nitrogen gas flowing through the nitrogen condensing passage 63. Went. As a result, liquefied oxygen having an oxygen purity of 99.5% or more could be obtained from the lower part of the oxygen distillation passage 61. At this time, circulating nitrogen gas compressed to 490 kPa by the circulating nitrogen compressor 7 and cooled to −179.6 ° C. by the main heat exchanger 4 was introduced into the nitrogen condensing passage 63 as a descending gas.
[0045]
Further, from the upper part of the distillation column 5, the liquefied argon having an argon content of 20% or more and the balance being substantially nitrogen is side-cut and introduced as a descending liquid into the argon distillation passage 62 of the heat exchange type distillation apparatus 6, Heat exchange was performed with nitrogen gas in the nitrogen condensing passage 63. As a result, liquefied argon having a purity of 98% or more was recovered from the lower part of the argon distillation passage 62.
[0046]
Further, when the second embodiment apparatus shown in FIG. 3 is used, the crude argon gas of substantially nitrogen and argon (content of 10% or more) is side-cut from the upper part of the distillation column 5, and the argon distillation column 82 Distillation was performed at the bottom. From the upper part of the argon distillation column 82, nitrogen gas having a nitrogen concentration of 99.99% or more and an oxygen content of 1 ppb or less was obtained. Moreover, as a result of introducing the crude liquefied argon at the bottom of the tower as a descending liquid into the argon distillation passage 62 of the heat exchange type distillation apparatus 6, liquefied argon having a purity of 98% or more was obtained from the lower portion of the argon distillation passage 62.
[0047]
【The invention's effect】
As described above, according to the present invention, in the air deep liquefaction separation method and apparatus using a heat exchange type distiller, nitrogen, argon and oxygen can be collected simultaneously as products. In addition, in the present invention, the height of the cold storage tank is compared with the height of the cold storage tank in an air separation apparatus using a conventional regular packed distillation column for collecting products of the same quality (purity, quantity, pressure). It can be reduced to about 65%, and the apparatus cost can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a first embodiment of an air liquefaction separation apparatus according to the present invention.
FIG. 2 is a partial cross-sectional perspective view showing one embodiment of a heat exchange type distiller used in the present invention.
FIG. 3 is a system diagram showing a second embodiment of the air liquefaction separation apparatus of the present invention.
FIG. 4 is a system diagram showing a third embodiment of the air liquefaction separation apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Raw material air compressor, 2 ... Air precooler, 3 ... Purifier, 4 ... Main heat exchanger, 5 ... Distillation tower, 6 ... Heat exchange type distiller, 7 ... Circulating nitrogen compressor, 8 ... Expansion turbine, DESCRIPTION OF SYMBOLS 9 ... Cold storage tank, 14 ... Distillation passage liquid introduction header, 15 ... Distillation passage gas extraction header, 16 ... Distillation passage liquid introduction header, 17 ... Condensation passage gas introduction header, 18 ... Condensation passage liquid extraction header, 23 ... Supercooler 32 ... liquefied oxygen supply pump, 36 ... gas-liquid separator, 39 ... liquefied oxygen boost pump, 61 ... oxygen distillation passage, 62 ... argon distillation passage, 63 ... nitrogen condensation passage, 82 ... argon distillation tower, 92 ... secondary Air compressor 96 ... Pressure reducing valve 98 ... Air expansion turbine

Claims (16)

The compressed, purified, and cooled raw material air is introduced into the distillation column, and is separated into crude liquefied oxygen containing nitrogen gas at the top of the column and nitrogen at the bottom of the column by low-temperature distillation in the distillation column, and then derived from the distillation column. The crude liquefied oxygen is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and the nitrogen gas derived from the distillation tower is heated, and after a part of the pressure is increased, the heat is cooled again and the heat exchange is performed. The gas is introduced as a descending gas into the condensing passage of the type distiller, condensed by heat exchange with the fluid in the distillation passage to form liquefied nitrogen, the liquefied nitrogen is decompressed and then used as the reflux liquid of the distillation column, and the nitrogen gas The crude liquefied oxygen is heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the descending liquid are brought into gas-liquid contact in the distillation passage so as to be in the upper part of the distillation passage. Nitrogen gas containing oxygen, Cryogenic air separation method characterized by the bottom of the distillation path liquid oxygen are separated respectively, collecting the liquefied oxygen as product oxygen.  2. The air liquefaction separation method according to claim 1, wherein high-pressure product oxygen gas is obtained by increasing the pressure of the liquefied oxygen derived from the distillation passage and then evaporating it.  2. The air liquefaction separation method according to claim 1, wherein the cooling required for operation is obtained by adiabatic expansion of at least one of raw material air and separation gas. The air liquefaction separation method according to claim 3, wherein the raw material air is secondarily compressed using expansion work generated by the adiabatic expansion. It claims 1 to 4 the method of cryogenic air separation wherein introducing the condensing passage of the heat exchanging type distillation apparatus, a portion of the feed air after cooling the descending gas instead of the nitrogen gas. The compressed, purified, and cooled raw material air is introduced into the distillation column, and is separated into crude liquefied oxygen containing nitrogen gas at the top of the column and nitrogen at the bottom of the column by low-temperature distillation in the distillation column, and then derived from the distillation column. The crude liquefied oxygen is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and the nitrogen gas derived from the distillation column is introduced into the condensing passage of the heat exchange type distiller as a descending gas. The crude liquefied oxygen is heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the descending liquid are brought into gas-liquid contact in the distillation passage so as to be in the upper part of the distillation passage. Nitrogen gas containing oxygen is separated into liquefied oxygen at the lower part of the distillation passage, the liquefied oxygen is collected as product oxygen, and the raw air is separated into nitrogen gas and crude liquefied oxygen by low-temperature distillation in the distillation tower. Do The crude argon containing nitrogen generated in the middle of the column is led out from the distillation column as liquid crude liquefied argon, introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and heated with the nitrogen gas in the condensation passage A part of the crude liquefied argon is vaporized by exchange to form an ascending gas, and the ascending gas and the descending liquid are brought into gas-liquid contact in the distillation passage to thereby convert nitrogen gas containing argon into the upper portion of the distillation passage. A liquid liquefaction separation method characterized by separating liquefied argon in the lower part of each, collecting the liquefied argon as product argon, and reintroducing nitrogen gas containing argon in the upper part into the distillation column. Instead of deriving crude liquefied argon from the distillation column, it is derived as gaseous crude argon gas, and the derived crude argon gas is introduced into the argon distillation column and further subjected to low-temperature distillation to thereby generate nitrogen gas and crude liquefied argon. 7. The air liquefaction separation method according to claim 6 , wherein the crude liquefied argon is introduced into the distillation passage of the heat exchange distiller as a descending liquid. A raw material air compressor that compresses raw material air, a purifier that removes impurities such as moisture and carbon dioxide contained in the compressed raw material air, and a main heat exchanger that cools the purified raw material air And a distillation column for separating the cooled raw material air at a low temperature into nitrogen gas and crude liquefied oxygen, and a heat exchange distiller having a distillation passage and a condensation passage, Oxygen that is vaporized by heat exchange between a path for introducing the crude liquefied oxygen separated in the distillation column as a descending liquid into the distillation passage and a fluid flowing in the condensation passage in the distillation passage and rises above the distillation passage. A path for deriving nitrogen gas containing oxygen, a path for deriving liquefied oxygen descending to the lower part of the distillation passage as product oxygen , and introducing part of the nitrogen gas derived from the upper part of the distillation column into the main heat exchanger And the main heat exchange A path for deriving the nitrogen gas heated in step and introducing it into the circulating nitrogen compressor, a path for introducing the compressed nitrogen gas compressed by the circulating nitrogen compressor into the main heat exchanger, and the main heat exchanger A path through which cooled compressed nitrogen gas is led out and introduced as a descending gas into the condensation passage of the heat exchanger-type distiller , and the condensation passage is liquefied by heat exchange with oxygen flowing through the distillation passage in the condensation passage. A liquefied nitrogen that descends to the lower part of the liquefied nitrogen, and a passage for introducing the liquefied nitrogen as a reflux into the upper part of the distillation column after decompression . When the raw air is distilled at a low temperature in the distillation column, crude argon containing nitrogen generated in the middle of the column is led out from the distillation column as liquid crude liquefied argon, and descends to a part of the distillation passage of the heat exchange type distiller. A path for introducing as a liquid, a path for deriving nitrogen gas containing argon which has been vaporized by heat exchange with the fluid flowing through the condensation path in the distillation path and has risen to the upper part of the distillation path, and a lower part of the distillation path The air liquefaction separation apparatus according to claim 8, further comprising a path for collecting the lowered liquefied argon as product argon. Instead of the path for introducing the crude liquefied argon derived from the distillation column into the distillation passage as a descending liquid, an argon distillation tower for separating the crude argon gas into nitrogen gas and crude liquefied argon by low-temperature distillation is provided. A path for deriving crude argon generated in the middle of the distillation column as a gaseous crude argon gas into the distillation column and introducing it into the argon distillation tower; and a path for deriving nitrogen gas separated by the argon distillation tower; 9. An air liquefaction separation apparatus according to claim 8 , further comprising a path for introducing the separated crude liquefied argon into the distillation passage as a descending liquid. 9. The air liquefaction separation apparatus according to claim 8, wherein a gas-liquid separator is provided in a lower part of the distillation passage. The air liquefaction separation apparatus according to claim 8 , further comprising a liquefied oxygen supply pump for supplying crude liquefied oxygen derived from the distillation column to a distillation passage of the heat exchange type distiller. 9. The air liquefaction separation apparatus according to claim 8, further comprising a liquefied oxygen pressurizing pump that pressurizes liquefied oxygen derived from a distillation passage of the heat exchange type distiller. In place of each of the nitrogen paths in the condensing passage, heat exchange between a path for introducing a part of the cooled raw material air into the condensing path as a descending gas and a fluid flowing through the distillation passage in the condensing path. 9. An air liquefaction separation apparatus according to claim 8, further comprising a path for deriving the liquefied air that has been liquefied and descended below the condensing passage. A path through which a part of the pressurized nitrogen gas is branched from the middle of the main heat exchanger and introduced into the expansion turbine, and a low-temperature nitrogen gas that is adiabatically expanded by the expansion turbine to generate cold is introduced into the main heat exchanger. The air liquefaction separation apparatus according to claim 8, further comprising: A path for deriving raw material air from the middle of the main heat exchanger and a secondary air compressor for low-temperature compressing the raw material air led to the path are provided, and the secondary air compressor is insulated by the expansion turbine. It is driven by using expansion work generated by expansion or expansion work generated by adiabatic expansion in an air expansion turbine that adiabatically expands high-pressure raw material air compressed at low temperature by the secondary air compressor. cryogenic air separation unit according to claim 1 5, wherein.

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