JP5550486B2 - Air liquefaction separation device and operation method thereof - Google Patents

Description

  The present invention relates to an air liquefaction separation apparatus and an operation method thereof.

  The rectification separation method is used in many fields such as an air liquefaction separation apparatus. In the rectification separation method, a raw material fluid is introduced into a rectification column, and is separated using a difference in boiling points of components constituting the raw material fluid. Here, the high boiling point component in the fluid component in each rectification column is stored in liquid form at the bottom of each rectification column (also referred to as the lower part or the column bottom).

  By the way, krypton and xenon are trace components in the atmosphere, and are contained in the atmosphere at 1.14 ppm and 0.087 ppm, respectively. Krypton is used as a gas sealed in a lamp. On the other hand, xenon is used in xenon lamp encapsulated gas, ion engine propellant, double heat insulating glass and the like.

  Krypton and xenon are industrially separated by cryogenic distillation of air. That is, after being concentrated in a double rectification column mainly for air separation, it is separated and purified through a predetermined separation process. Since the boiling point of krypton and xenon is higher than that of oxygen, it is concentrated in the liquid oxygen at the bottom of the low pressure column of the double rectification column.

  On the other hand, since the boiling point of the hydrocarbon contained in the raw material air is higher than that of oxygen, it is concentrated in the liquid oxygen at the bottom of the low-pressure column together with krypton and xenon. Therefore, basically, liquid oxygen in which krypton, xenon and hydrocarbons are concentrated is used as a raw material, and after removal of hydrocarbons, krypton and xenon are further concentrated and separated and purified.

  By the way, Patent Document 1 is known as a method for removing hydrocarbons from liquid oxygen. Specifically, Patent Document 1 describes a process for purifying and separating krypton and xenon using liquid oxygen obtained by concentrating hydrocarbons, krypton and xenon as a raw material. In this process, as shown in FIG. 4, the hydrocarbons contained in the liquid oxygen flowing through the paths L101 to L102 after the double rectification column 102 are oxidized in the catalyst column 105, and the resulting moisture and carbon dioxide are Adsorption is removed by a two-column adsorber 106.

  Here, the two-cylinder type adsorber 106 is a general switching type adsorber, and it is necessary to regenerate each adsorption cylinder every predetermined time. The regeneration of the adsorption cylinder is generally performed at a low pressure, and the adsorption cylinder that has been regenerated is charged to a pressure required for the adsorption operation (this process is referred to as a “charging process”).

  However, in the above-described charging step, a part of the processing fluid derived from the adsorption cylinder in the adsorption step is used as the charging fluid, so that the flow rate of the fluid introduced into the downstream deoxygenation tower 107 is reduced and the desorption is performed. There was a problem that the operating pressure of the oxygen tower fluctuated (decreased).

  In order to solve the above problem, Patent Document 2 and Patent Document 3 are known as methods for making the flow rate of fluid derived from the adsorber to a downstream device constant.

Specifically, Patent Document 2 describes a method of controlling the suction guide vanes of the raw air compressor so that the flow rate of the raw air introduced from the adsorber to the air separation device is constant.
Patent Document 3 discloses a method of measuring the flow rate actually charged in the charging step of the adsorber and increasing the amount of the raw material air compressor by that amount.
That is, the method disclosed in Patent Document 2 and Patent Document 3 is a method for securing a fluid necessary for charging the adsorber by increasing the amount of the raw material air compressor using inexhaustible air. .

  However, it is inappropriate to incorporate inexhaustible air as a charging fluid for the adsorber installed in the post-process of the double rectification column, and it is difficult to secure the charging fluid freely when necessary. That is, the pressurized fluid required in the charging process of the target adsorber is a fluid in which the main component is oxygen and a predetermined amount of krypton and xenon, which are rare gases, is concentrated. Therefore, even when an oxygen fluid in which xenon or the like is concentrated is used, when a fluid having a different composition is used, the fluid composition introduced into the deoxygenation tower in the subsequent step fluctuates, which causes a process variation. there were.

  Therefore, in order to secure a charging fluid for the adsorber, as shown in FIG. 4, a buffer tank 125 having a predetermined capacity is installed between the adsorber 106 and the deoxygenation tower 107, so that the charging pressure of the adsorber is increased. It is considered possible to reduce process variations during the process. However, if such a buffer tank 125 is installed between the adsorber 106 and the deoxygenation tower 107, it is necessary to replace the inside of the buffer tank 125 with the target fluid, so that it takes a longer time to start up the apparatus. There was a problem of becoming.

  On the other hand, Patent Document 4 is known as a method for safely carrying out the concentration step of krypton and xenon. This Patent Document 4 discloses a process for changing oxygen itself to other components by chemical reaction in order to avoid reaction between liquid oxygen and hydrocarbons contained in the krypton and xenon concentration step. That is, in the process disclosed in Patent Document 4, methane is introduced into liquid oxygen containing krypton, xenon, and hydrocarbon to form hydrogen and carbon monoxide (synthesis gas). Thereby, since the reaction between oxygen and hydrocarbons can be suppressed, there is no concern about explosion and the concentration step can be performed safely.

  However, there has been a problem that cryogenic separation of krypton and xenon from hydrogen, carbon monoxide, carbon dioxide, water vapor and the like generated by the above reaction is newly required. Moreover, the above reaction is basically a partial oxidation technique for natural gas, and requires steam at a high temperature (for example, about 340 ° C.), resulting in a problem that the equipment cost is greatly increased.

Japanese Patent Application Laid-Open No. 07-139876 Japanese Patent Laid-Open No. 04-121577 Japanese Patent No. 3195982 Japanese Patent Laid-Open No. 2003-212524

  The present invention has been made in view of the above problems, and there is no pressure fluctuation due to switching of the adsorption cylinder of the adsorber in the separation and purification process of krypton and xenon in the post-process of the double rectification column, and the operation is safe. An object of the present invention is to provide a method of operating an air liquefaction separation apparatus and an air liquefaction separation apparatus.

In order to solve this problem, the present invention has the following configuration.
According to the first aspect of the present invention, the operation of the air liquefaction separation apparatus for extracting liquid oxygen enriched with krypton and xenon from the bottom of the low-pressure column of the double rectification column and separating krypton and xenon by low temperature rectification using the raw material as a raw material. A method,
A pumping step of compressing liquid oxygen enriched with krypton and xenon to a critical pressure or higher by a pumping means provided on the secondary side of the double rectification column, and deriving at a predetermined flow rate;
A pressure reducing step for raising the liquid oxygen derived from the pressure feeding means to room temperature and then introducing it into the pressure reducing means, and reducing the pressure to a critical pressure or lower;
A catalytic reaction step of introducing oxygen gas having a pressure equal to or lower than the critical pressure derived from the depressurization means into a catalytic reaction cylinder, and reacting hydrocarbons contained in the liquid oxygen with oxygen to generate water and carbon dioxide;
The gas derived from the catalyst reaction cylinder is introduced into at least one adsorption cylinder of a switching type adsorber having two or more adsorption cylinders that alternately perform adsorption, regeneration, and charging, and water and carbon dioxide are extracted from the gas. An adsorption process for adsorbing and removing carbon;
After the gas derived from the adsorber is divided into two, after cooling one gas, krypton and xenon are introduced into a post-process for low-temperature rectification, and the other gas is introduced into the regenerated adsorption cylinder and the adsorption cylinder A charging step for charging
The flow rate or the pressure is measured continuously or at predetermined intervals so that the flow rate or pressure of the one gas introduced into the post-process for rectifying krypton and xenon at a low temperature is constant. And a step of increasing or decreasing the flow rate of the liquid oxygen derived from the pumping means in accordance with the amount of fluctuation of the measured value of the air liquefaction separation apparatus.

The invention according to claim 2 is characterized in that in the catalytic reaction step,
Introducing the liquid oxygen derived from the pumping means into the heating means;
2. The method of operating an air liquefaction separation apparatus according to claim 1, wherein the differential pressure between the primary side and the secondary side of the heating means is measured continuously or at a predetermined interval.

The invention described in claim 3 is an air liquefaction separation apparatus for extracting liquid oxygen enriched with krypton and xenon from the bottom of the low pressure column of the double rectification column, and separating krypton and xenon by low-temperature rectification using this as a raw material. And
A pumping means provided on the secondary side of the double rectification column, compressing liquid oxygen enriched with krypton and xenon to a critical pressure or more and deriving at a predetermined flow rate;
Heating means for raising the temperature of the liquid oxygen derived from the pressure feeding means to room temperature;
Pressure measuring means for measuring a differential pressure between the primary side and the secondary side of the heating means;
Pressure reducing means for reducing the pressure in the supercritical state derived from the heating means to a critical pressure or less;
A catalytic reaction cylinder for producing water and carbon dioxide by reacting hydrocarbons and oxygen contained in an oxygen gas having a critical pressure or less derived from the decompression means;
A switchable adsorber having two or more adsorption cylinders that alternately perform adsorption, regeneration, and charging, and that adsorbs and removes water and carbon dioxide from the gas derived from the catalyst reaction cylinder;
Separation means provided on the secondary side of the adsorber and separating krypton and xenon from the remainder of the fluid derived from the adsorber;
Measurement means for measuring at least one of the flow rate and pressure of the fluid introduced into the separation means;
An air liquefaction separation apparatus comprising: control means for controlling the flow rate of the liquid oxygen from the pressure feeding means to be increased or decreased based on at least one measurement value of the flow rate and pressure of the measurement means. It is.

According to the operation method and the air liquefaction separation apparatus of the present invention, after the gas led out from the catalytic reaction cylinder is introduced into the switching type adsorber to adsorb and remove water and carbon dioxide, from the adsorber The gas after the derivation is divided into two, one is introduced into a post-process for low-temperature rectification of krypton and xenon, and the other is introduced into the regenerated adsorption cylinder to charge the adsorption cylinder. That is, even if the adsorber is provided on the secondary side of the double rectification column and the components of the oxygen gas fluid for charging are limited, water and carbon dioxide are removed by one adsorption cylinder. Can be used for charging the other adsorption cylinder after regeneration.
Then, the flow rate or pressure of the liquid oxygen introduced from the pumping means is measured continuously or at predetermined intervals so that the flow rate or pressure of the gas introduced into the subsequent process is constant. It is the structure provided with the control means which controls by increasing or decreasing. In this way, the flow rate or pressure of the fluid led out from the adsorber and introduced into the separation means, which is a subsequent process, is measured, and the flow rate of liquid oxygen derived from the pumping means is increased or decreased according to the amount of variation in the measured value. By controlling by decreasing, the flow rate or pressure of the fluid introduced into the separation means can be kept constant.
Accordingly, the air liquefaction separation device can suppress flow rate fluctuation and pressure fluctuation at the time of switching the adsorption cylinder in the adsorber without providing a buffer tank or the like between the adsorber and the separation means constituting the post-process. Stable operation becomes possible.

Further, according to the operation method of the air liquefaction separation apparatus and the air liquefaction separation apparatus of the present invention, the liquid oxygen enriched with krypton and xenon is brought to a critical pressure or higher by the pumping means provided on the secondary side of the double rectification column. The liquid oxygen is heated to room temperature by a heating means, and reduced to below the critical pressure by a pressure reducing means, and then introduced into the catalyst reaction cylinder. In this way, by increasing the pressure of liquid oxygen above the critical pressure by the pumping means, oxygen becomes a supercritical fluid in the heating means, so that the generation of a gas-liquid interface caused by part of the liquid oxygen is suppressed. can do. Therefore, since the concentration of hydrocarbons on the liquid side at the gas-liquid interface can be reduced, the air liquefaction separation apparatus can be operated safely.
After the oxygen containing hydrocarbons is heated to room temperature, there is no need to worry about hydrocarbon concentration due to gas-liquid equilibrium, and the pressure is reduced to a pressure suitable for catalytic reaction, adsorption or rectifying operation in the subsequent process. can do.

  Furthermore, when the air liquefaction separation apparatus is provided with a pressure measuring means for measuring the differential pressure between the primary side and the secondary side of the heating means, a change in pressure loss during this period can be detected early. . As a result, it is possible to take measures such as purging internal equipment piping at an early stage, and the air liquefaction separation apparatus can be operated more safely.

It is a systematic diagram which shows the structure of the air liquefaction separation apparatus which is one Embodiment to which this invention is applied. It is a figure for demonstrating the effect of this invention, and is a figure which shows the fluctuation | variation of the measured value of each pressure gauge in the driving | operation of an air liquefaction separation apparatus. It is a figure for demonstrating the effect of this invention, and is a figure which shows the rotation speed of a liquid oxygen pump in the driving | operation of an air liquefaction separation apparatus, and the measured value of a flowmeter. It is a systematic diagram which shows the structure of the conventional air liquefaction separation apparatus.

  Hereinafter, the operation method of the air liquefaction separation apparatus which is one embodiment to which the present invention is applied will be described in detail with reference to the drawings together with the air liquefaction separation apparatus used therefor. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

First, the structure of the air liquefaction separation apparatus used for the operating method of the air liquefaction separation apparatus which is one Embodiment to which this invention is applied is demonstrated.
The air liquefaction separation apparatus of this embodiment is an apparatus for extracting liquid oxygen enriched with krypton and xenon from the bottom of a low-pressure column of a double rectification column, and separating krypton and xenon by using low temperature rectification as a raw material. More specifically, hydrocarbons concentrated together with krypton and xenon are removed from the liquid oxygen, and then krypton and xenon are further concentrated and separated and purified.

  As shown in FIG. 1, an air liquefaction separation apparatus 1 according to this embodiment includes a liquid oxygen pump (pressure feeding means) 3 and an oxygen heater (heating means) that are sequentially provided on the secondary side of a double rectification column 2. 4, a pressure reducing valve (pressure reducing means) 13, a catalytic reaction cylinder 5, a switching type adsorber 6, and a deoxygenation tower (separating means) 7 are schematically configured. Further, the air liquefaction separation apparatus 1 measures a differential pressure gauge (pressure measuring means) 8 that measures the differential pressure between the primary side and the secondary side of the oxygen heater 4 and the flow rate of the fluid introduced into the concentration tower 7. A flow meter (measuring means) 9 and an inverter (control means) 10 for controlling the flow rate of the liquid oxygen from the liquid oxygen pump 3.

  The double rectification column 2 is mainly intended for air separation, and hydrocarbons, which are high-boiling impurities, are concentrated together with krypton and xenon in the liquid oxygen at the bottom of the low-pressure column 2A. A buffer tank 11 is provided in the path L1 between the bottom of the low pressure column 2A and the liquid oxygen pump 3, and liquid oxygen derived from the bottom of the low pressure column 2A can be temporarily stored. It is like that.

  The hydrocarbons are not particularly limited as long as they are contained in a minute amount in the raw material air. Specific examples of such hydrocarbons include methane, ethane, and propane.

  The liquid oxygen pump 3 is provided on the secondary side of the double rectification column 2. This liquid oxygen pump 3 is a pumping means for deriving liquid oxygen at a predetermined flow rate (set flow rate) after compressing liquid oxygen introduced from the bottom of the low pressure column 2A to a critical pressure of 5.05 MPa or more. The liquid oxygen pump 3 is not particularly limited as long as it can compress liquid oxygen to a critical pressure or higher and can be derived at a predetermined flow rate, and a conventionally known one can be used. it can.

  The oxygen heater 4 is provided on the secondary side of the liquid oxygen pump 3. The oxygen warming device 4 is a heating means that heats liquid oxygen, which is introduced from the liquid oxygen pump 3 through the filter 12 and is compressed to a critical pressure or higher, and raises the temperature to room temperature. A gas (oxygen fluid) that has been heated to room temperature is derived from the oxygen heater 4. The oxygen heater 4 is not particularly limited as long as it can raise the temperature of liquid oxygen to room temperature, and a conventionally known one can be used.

  A pressure reducing valve (pressure reducing means) 13 is provided between the oxygen temperature increasing device 4 and the catalyst reaction cylinder 5 in order to reduce the pressure in the supercritical state heated to room temperature by the oxygen temperature increasing device 4 to a critical pressure or lower. It is provided in the path L3. By providing this pressure reducing valve 13, it is not necessary to worry about hydrocarbon concentration due to gas-liquid equilibrium after oxygen containing hydrocarbons has been heated to room temperature, and catalytic reaction, adsorption, or rectification operation in the post-process The pressure can be reduced to an appropriate pressure. The pressure reducing valve 13 is not particularly limited as long as it can depressurize a supercritical fluid to a critical pressure or lower, and a conventionally known one can be used.

  Further, a heat exchanger 14 and a heater 15 for further raising the temperature of the gas to the secondary side of the pressure reducing valve 13 are arranged in this order in the path L3 between the oxygen heater 4 and the catalyst reaction cylinder 5. Is provided.

  The catalytic reaction cylinder 5 is provided with an oxygen heater 4 for reacting hydrocarbons and oxygen contained in oxygen gas having a critical pressure or less derived from the pressure reducing valve 13 to generate water and carbon dioxide. It is provided on the secondary side. The catalyst reaction cylinder 5 is filled with a predetermined amount of catalyst. For example, the catalyst may be a noble metal catalyst such as platinum (Pt) or palladium (Pd). Of course, these metal catalysts may be used alone or in combination. The catalyst reaction cylinder 5 is not particularly limited as long as it can decompose hydrocarbons contained in the gas led out from the oxygen heater 4 into water and carbon dioxide by oxidation. Instead, conventionally known ones can be used. Further, the concentration of hydrocarbons contained in the gas derived from the catalytic reaction cylinder 5 is preferably not more than a detection limit (for example, not more than 0.05 ppm).

  A path L4 between the catalyst reaction cylinder 5 and the adsorber 6 includes a heat exchanger 14 and a cooler 16 for cooling oxygen gas from which hydrocarbons have been removed by the catalyst reaction cylinder 5 and a drain separator 17. They are provided in this order.

  The adsorber 6 is for adsorbing and removing water and carbon dioxide from the gas led out from the catalyst reaction cylinder 5, and is provided on the secondary side of the catalyst reaction cylinder 5. The adsorber 6 is a switchable adsorber having two adsorption cylinders 6A and 6B that alternately perform adsorption, regeneration, and charging. Here, the adsorber 6 of the present embodiment is an example having two adsorption cylinders as described above, but is not limited to this, and has two or more adsorption cylinders, which are alternately arranged. It is good also as a structure which performs adsorption | suction, reproduction | regeneration, and charging.

  The adsorption cylinders 6A and 6B have the same configuration, and are configured so that the flow of gas introduced into the adsorption cylinder 6A and the adsorption cylinder 6B can be switched by opening and closing the valves 18 to 21, respectively. The adsorption cylinder 6A and the adsorption cylinder 6B are provided with pressure gauges 22 and 23 for measuring the internal pressure, respectively.

  In the adsorption cylinder 6A (6B), water and carbon dioxide are introduced from the inflow side (bottom side in FIG. 1) to the outflow side (upper side in FIG. 1) of the gas led out from the catalytic reaction cylinder 5. The adsorbent for adsorbing and removing is filled in a single layer or stacked.

  Here, the moisture adsorbent for adsorbing water in the gas derived from the catalyst reaction cylinder 5 is not particularly limited, and for example, any one of activated alumina, silica gel, and synthetic zeolite is used. Two or more can be used. The adsorbent for adsorbing carbon dioxide is not particularly limited, and for example, synthetic zeolite can be used.

  The deoxygenation tower (separation means) 7 is equipment for separating krypton and xenon from the fluid led out from the adsorber 6, and is provided on the secondary side of the adsorber 6. The deoxygenation tower 7 is provided with a reboiler 7a at the bottom and a condenser (condenser) 7b at the top.

  The fluid introduced into the deoxygenation tower 7 is rectified, and a liquefied gas (fluid) consisting of 90 to 95% krypton, 5 to 10% xenon and 0.5 ppm or less oxygen is separated at the bottom of the deoxidation tower. Is done. Then, the fluid led out from the bottom of the deoxygenation tower 7 is introduced into the middle or middle and lower stages of a separation tower (not shown) provided on the secondary side of the deoxygenation tower 7. The rectification in the separation column separates krypton having a purity of 99.99% or more at the top of the column and xenon having a purity of 99.99% or more at the bottom.

  In addition, in this embodiment, as shown in FIG. 1, although the example which used only the deoxygenation tower 7 as the separation means is shown, it is not limited to this, The low-temperature rectification process such as the separation tower described above It is good also as what combined with the other apparatus which comprises.

  A differential pressure gauge (pressure measuring means) 8 is provided across the path 2 and the path 3 in order to measure the differential pressure between the primary side and the secondary side of the oxygen heater (heating means) 4. Specifically, as shown in FIG. 1, one end side is connected to the primary side of the filter 12, and the other end side is connected to the upstream side of the pressure reducing valve 13. The differential pressure gauge 8 is not particularly limited as long as it can measure the differential pressure between the primary side and the secondary side of the oxygen heater 4, and a conventionally known one can be used. it can.

  Here, the operating pressure between the liquid oxygen pump 3 and the pressure reducing valve 13 is set to be equal to or higher than the critical pressure (5.05 MPa) of oxygen as described above. In the unlikely event that hydrocarbons, which are high-boiling components, are clogged in equipment or piping, the pressure loss (for example, 0.001 MPa) caused by equipment or piping clogging compared to the operating pressure of the liquid oxygen pump 3. ) Is relatively small and difficult to find. Therefore, by installing the differential pressure gauge 8 between the liquid oxygen pump 3 and the pressure reducing valve 13, a change in pressure loss during this period can be detected early. Therefore, it becomes possible to purge the inside of equipment, piping and the like at an early stage, and the process can be safely operated.

  A flow meter (measuring means) 9 is provided in a flow path L5 between the adsorber 6 and the deoxygenation tower 7 in order to measure the flow rate of the fluid introduced from the adsorber 6 and introduced into the deoxygenation tower 7. Is provided. The flow meter 9 is not particularly limited as long as it can measure the flow rate of the fluid introduced into the deoxygenation tower 7, and a conventionally known one can be used.

  In the present embodiment, as shown in FIG. 1, an example in which only the flow meter 9 is used as the measuring means is shown, but the present invention is not limited to this. For example, as shown in FIG. 1, the pressure gauge 24 provided in the flow path L5 measures the pressure of the fluid introduced into the deoxygenation tower 7 after being led out from the adsorber 6, Instead of 9, measurement means may be used. Further, both the flow meter 9 and the pressure gauge 24 may be provided and used as measuring means.

  The inverter (control means) 10 controls the flow rate of liquid oxygen from the liquid oxygen pump 3 by increasing or decreasing based on the measured value of at least one of the flow meter 9 and the pressure gauge 24. Further, as shown in FIG. 1, the inverter 10 is connected so that the liquid oxygen pump 3 and the flow meter 9 or the pressure gauge 24 can be controlled. Thus, the inverter 10 is configured to control the flow rate of the liquid oxygen to be pumped by increasing or decreasing the rotational speed of the liquid oxygen pump 3 so that the value of the flow meter 9 or the pressure gauge 24 becomes constant. .

Next, an operation method (hereinafter simply referred to as “operation method”) of the air liquefaction separation apparatus 1 will be described.
The operation method of the present embodiment compresses liquid oxygen enriched with krypton and xenon to a critical pressure or higher by a liquid oxygen pump (pressure feeding means) 3 provided on the secondary side of the double rectification column 2, A pressure-feeding step derived from the flow rate, a pressure-reducing step in which the liquid oxygen derived from the liquid oxygen pump 3 is heated to room temperature and then introduced into the pressure-reducing means, and the pressure is reduced to a critical pressure or less, and a critical pressure derived from the pressure-reducing means The following oxygen gas is introduced into the catalytic reaction cylinder 5, a catalytic reaction step for producing water and carbon dioxide by reacting hydrocarbons contained in liquid oxygen with oxygen, and a gas derived from the catalytic reaction cylinder 5 An adsorption step for introducing and adsorbing and removing water and carbon dioxide from the gas into at least one adsorption cylinder 6A (or 6B) of an adsorber 6 having adsorption cylinders 6A and 6B that alternately perform adsorption, regeneration and charging. The gas derived from the adsorber 6 is divided into two, and after cooling one gas, the krypton and xenon are introduced into a post-process for low-temperature rectification, and the other gas is introduced into the regenerated adsorption cylinder 6B (or 6A). Then, at least one of the flow rate and the pressure is set so that at least one of the flow rate and the pressure of one of the gases introduced into the charging step for charging the adsorption cylinder and the subsequent step for low-temperature rectification of krypton and xenon is constant. A step of measuring continuously or at predetermined intervals and controlling the flow rate of liquid oxygen derived from the liquid oxygen pump 3 to be increased or decreased in accordance with a variation amount of at least one of the flow rate and pressure. It is roughly structured.

  Specifically, first, krypton, xenon and hydrocarbons contained in trace amounts in the raw air are concentrated in the liquid oxygen at the bottom of the low pressure column 2A of the double rectification column 2. Part of this liquid oxygen is introduced into the liquid oxygen pump 3 via the pipes constituting the path L1 and the buffer tank 11, and is compressed to a pressure equal to or higher than the critical pressure of oxygen (= 5.05 MPa) and derived in a predetermined amount. (Pumping process). Then, the liquid oxygen led out from the liquid oxygen pump 3 is introduced into the oxygen temperature riser 4 to be heated.

  Here, as described above, the reason why the liquid oxygen is increased to the critical pressure of 5.05 MPa or more by the liquid oxygen pump 3 is that the precipitation of hydrocarbons concentrated in the liquid oxygen by the double rectification column 2 is avoided. It is to do.

  In general, when liquid oxygen having a pressure lower than the critical pressure is vaporized by receiving heat (Q), a gas-liquid interface is always generated. Here, when the concentration of the hydrocarbon contained in the liquid oxygen side is (C), the concentration of the hydrocarbon in the vaporized oxygen gas is also (C). However, hydrocarbon vapor-liquid equilibrium occurs at the gas-liquid interface. That is, in the vicinity of the gas-liquid interface, the hydrocarbon concentration (Cs) in the liquid oxygen is in a gas-liquid equilibrium relationship with the hydrocarbon concentration (C) in the oxygen gas, and is larger than the liquid oxygen concentration (C). Moreover, if the hydrocarbon concentration (Cs) in the liquid oxygen near the gas-liquid interface exceeds the solubility of the hydrocarbon in the liquid oxygen, the hydrocarbon will precipitate.

  Therefore, according to the operation method of the present embodiment, the liquid oxygen is boosted to a critical pressure of 5.05 MPa or more by the liquid oxygen pump 3 and heated by the oxygen temperature riser 4 in a state of being boosted to the critical pressure or more. It has become. For this reason, a gas-liquid interface does not occur in the process in which the oxygen fluid becomes room temperature oxygen, and precipitation of hydrocarbons in equipment and piping can be suppressed.

  Further, when liquid oxygen derived from the liquid oxygen pump 3 is introduced into the oxygen heater 4, the differential pressure between the primary side and the secondary side of the oxygen heater 4 is continuously or predetermined using a differential pressure gauge 8. It is preferable to measure at intervals. Thereby, even when the liquid oxygen pump 3 and the pressure reducing valve 13 are caused by blockage of equipment or piping due to hydrocarbons which are high-boiling components, the change in pressure loss during this period should be detected early. Can do. Therefore, it becomes possible to purge the inside of equipment, piping and the like at an early stage, and the process can be safely operated.

  Next, after the supercritical fluid heated to room temperature by the oxygen heater 4 is depressurized to a critical pressure or less by the pressure reducing valve 13 and then heated again by the heat exchanger 14 and the heater 15. It is introduced into the catalytic reaction cylinder 5. In the catalytic reaction cylinder 5, hydrocarbons in the oxygen gas are oxidized to generate moisture and carbon dioxide. That is, hydrocarbons are removed from the oxygen gas (catalytic reaction step).

  Next, the gas derived from the catalytic reaction cylinder 5, that is, the oxygen gas from which hydrocarbons have been removed, is cooled by the heat exchanger 14 and the cooler 16 and then introduced into the adsorber 6. Hereinafter, in this embodiment, the case where the adsorption cylinder 6A is the adsorption process and the adsorption cylinder 6B is the regeneration process will be described as an example.

(Adsorption process)
In the adsorption cylinder 6A, moisture and carbon dioxide in the oxygen gas led out from the catalyst reaction cylinder 5 are adsorbed and removed. Specifically, oxygen gas led out from the catalytic reaction cylinder 5 is introduced into the adsorption cylinder 6A, and moisture and carbon dioxide are adsorbed and removed by the adsorbent layer filled in the adsorption cylinder 6A. The purified oxygen gas is led out to the path L5 from the adsorption cylinder 6A, and then introduced into a post-process facility (deoxygenation tower 7) for separating and purifying krypton and xenon.

(Regeneration process)
While the adsorption process is performed in one adsorption cylinder 6A, the regeneration process is performed in the other adsorption cylinder 6B. Here, when the regeneration of the adsorption cylinder 6B is completed, the inside of the adsorption cylinder 6B is charged in preparation for the adsorption process (charging process). Specifically, by opening the valve 21, a part of the oxygen gas purified by the adsorption cylinder 6A is introduced into the adsorption cylinder 6B from the path L5. Thereby, a part of oxygen gas refine | purified with 6 C of adsorption cylinders can be used as a charging gas of the said adsorption cylinder 6B.

  By the way, in the conventional operation method of the air liquefaction separation apparatus, a fluid having a composition different from that of the fluid flowing through the path L5 is used as the charging fluid for the adsorber installed in the post-process of the double rectification column. There has been a problem that the fluid composition introduced into the deoxygenation tower of the process fluctuates and contributes to the process fluctuation.

  On the other hand, according to the operation method of the present embodiment, the oxygen gas produced by the adsorption process of the adsorption cylinder 6A is used as the charging oxygen gas of the adsorption cylinder 6B after the regeneration in the regeneration process. . For this reason, a fluid limited to a predetermined composition (having oxygen, krypton, and xenon and not including hydrocarbons, moisture, and carbon dioxide) flowing through the path L5 is used as the air liquefaction separation apparatus 1 itself (adsorption in the adsorption process). Tube), and it is not necessary to supply from the outside. Accordingly, the composition of the fluid introduced into the post-stage deoxygenation tower 7 does not fluctuate, and process operation is suppressed and stable operation is possible.

  And the operation method of this embodiment is a case where a part of oxygen gas manufactured by the adsorption cylinder 6A in the adsorption process is used as the oxygen gas for charging the adsorption cylinder 6B after the regeneration in the regeneration process. The flow rate of the liquid oxygen led out from the liquid oxygen pump 3 is controlled so that the flow rate of the oxygen gas introduced from the adsorber 6 into the deoxygenation tower 7 in the subsequent process is constant.

  Specifically, the flow rate or pressure of oxygen gas introduced from the adsorber 6 to the deoxygenation tower 7 is measured continuously or at predetermined intervals by one or both of the flow meter 9 and the pressure gauge 24 provided in the path L5. Then, at least one fluctuation amount of the measured value of the flow rate or pressure is transmitted to the inverter 10 as a control signal. The inverter 10 that has received this control signal controls the rotational speed of the liquid oxygen pump 3 to increase or decrease according to the amount of change in the measured value of the flow rate or pressure of the fluid flowing through the path L5.

  As described above, by adopting the control of the liquid oxygen pump 3, the flow rate of the liquid oxygen led out from the liquid oxygen pump 3 is increased or decreased, and introduced into the deoxygenation tower 7 provided at the rear stage of the adsorber 6. The flow rate of oxygen gas is constant. Accordingly, the operation pressure of the deoxygenation tower 7 which is a subsequent process does not fluctuate, and a constant operation can be performed (control process).

  Finally, the fluid introduced into the deoxygenation tower 7 as a post-process is rectified, and at the bottom of the deoxygenation tower 7, krypton is 90 to 95%, xenon is 5 to 10%, and oxygen is 0.5 ppm or less. The resulting liquefied gas (fluid) is separated. The fluid led out from the bottom of the deoxygenation tower 7 is rectified in a separation tower (not shown) provided on the secondary side of the deoxygenation tower 7 to obtain a krypton having a purity of 99.99% or more, Separated into 99.99% or more of xenon.

  As described above, according to the air liquefaction separation apparatus 1 and its operating method of the present embodiment, the gas derived from the catalytic reaction cylinder 5 is introduced into the switchable adsorber 6 to adsorb and remove water and carbon dioxide. After that, the gas derived from the adsorber 6 is divided into two, one is introduced into the deoxygenation tower 7, and the other is introduced into the regenerated adsorption cylinder 6B to charge the adsorption cylinder. That is, even if the adsorber 6 is provided on the secondary side of the double rectification column 2 and the components of the oxygen gas fluid for charging are limited, water and carbon dioxide are absorbed by one adsorption cylinder 6A. Can be used to charge the other adsorption cylinder 6B after regeneration.

  Further, according to the air liquefaction separation apparatus 1 and the operation method thereof of the present embodiment, deoxidation is performed by at least one of the flow meter 9 and the pressure gauge 24 provided in the path L5 between the adsorber 6 and the deoxygenation tower 7. The flow rate or pressure of the gas introduced into the tower 7 is measured continuously or at predetermined intervals, and the rotation speed of the liquid oxygen pump 3 is controlled by the inverter 10 according to the fluctuation amount of the measured value. Thereby, the flow rate of the liquid oxygen led out from the liquid oxygen pump 3 can be increased or decreased, and the flow rate or pressure of the gas introduced into the deoxygenation tower 7 can be controlled to be constant. Therefore, it is possible to suppress flow rate fluctuations and pressure fluctuations when switching the adsorption cylinders 6A and 6B in the adsorber 6 without providing a new buffer tank or the like between the adsorber 6 and the deoxygenation tower 7. The air liquefaction separation apparatus 1 can be stably operated.

  Further, according to the air liquefaction separation apparatus 1 and its operating method of the present embodiment, the liquid oxygen pump 3 provided on the secondary side of the double rectifying column 2 is used to convert liquid oxygen enriched with krypton and xenon to a critical pressure. The liquid oxygen is heated up to room temperature with the oxygen heater 4 and then reduced to below the critical pressure with the pressure reducing valve 13, and oxygen gas below this critical pressure is introduced into the catalyst reaction cylinder 5. ing. In this way, by raising the liquid oxygen to a critical pressure or higher by the liquid oxygen pump 3, oxygen becomes a fluid in a supercritical state in the oxygen heater 4, and thus the gas-liquid produced by vaporization of a part of the liquid oxygen Generation of an interface can be suppressed. Therefore, since the concentration of hydrocarbons on the liquid side at the gas-liquid interface can be reduced, the air liquefaction separation apparatus can be operated safely. After the oxygen containing hydrocarbons is heated to room temperature, there is no need to worry about hydrocarbon concentration due to gas-liquid equilibrium, and the pressure is reduced to a pressure suitable for catalytic reaction, adsorption or rectifying operation in the subsequent process. can do.

  Furthermore, when the differential pressure gauge 8 for measuring the differential pressure between the primary side and the secondary side of the oxygen heater 4 is provided in the air liquefaction separation apparatus 1 of the present embodiment, the change in pressure loss during this time Can be discovered early. As a result, it is possible to take measures such as purging internal equipment and piping at an early stage, and the air liquefaction separation apparatus 1 can be operated more safely.

  In addition, this invention is not necessarily limited to the thing of the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention. For example, in the air liquefaction separation apparatus 1 of the above-described embodiment, a flow meter 9 or a pressure gauge 24 is provided between the adsorber 6 and the deoxygenation tower 7 and a signal is sent to the inverter 10 from these measured values. However, it is not necessarily limited to this configuration. For example, a flow meter is provided in the valve 21 that is opened when the adsorption cylinder 6B is charged, the flow rate of the pressurized fluid flowing through the valve 21 is measured, and the flow rate of the liquid oxygen pump 3 is increased so as to increase the corresponding flow rate. The object can be achieved even by controlling the rotation speed.

  Further, in the charging process of the adsorber 6, the flow rate of the liquid oxygen collected from the low pressure column 2A is made constant, and the increased operation amount of the liquid oxygen pump 3 when the adsorber is charged is stored in the buffer tank 11. The influence on the low pressure column 2A can be reduced.

Specific examples are shown below.
(Example)
An operation of separating krypton and xenon by low temperature rectification was performed using the air liquefaction separation apparatus 1 shown in FIG. FIG. 2 shows measured values during operation of the pressure gauges 22, 23, 24 of the air liquefaction separation apparatus 1. FIG. 3 shows the number of rotations during operation of the liquid oxygen pump 3 of the air liquefaction separation apparatus 1 and the measured value of the flow meter 9.
In the operation of the air liquefaction separation apparatus 1, the adsorption cylinder 6A was an adsorption process and the adsorption cylinder 6B was a regeneration process at an operation time of 0 minutes on the horizontal axis of FIGS.

As shown in FIG. 2 and FIG. 3, the adsorption cylinder 6 </ b> B that was in the regeneration process when the operation time was 0 minutes becomes a charging process between time A and time B. Then, at time B shown in FIGS. 2 and 3, the adsorption cylinder 6 </ b> B has completed the charging process, and then becomes the adsorption process.
In the charging step of the adsorption cylinder 6B, as shown in FIG. 3, the liquid oxygen pump 3 is in an increase operation by the rotation speed control (increase in the rotation speed), and supplies the fluid necessary for charging the adsorption cylinder 6B. . As a result, as shown in FIG. 2 and FIG. 3, the pressure of the oxygen fluid (pressure gauge 24 value) and the flow rate of the oxygen fluid (flow meter 9 value) introduced into the subsequent process can be made substantially constant. It was. Thus, it was confirmed that the stable operation of the air liquefaction separation apparatus 1 was possible.

DESCRIPTION OF SYMBOLS 1 ... Air liquefaction separation apparatus 2 ... Duplex rectification tower 2A ... Low pressure tower 3 ... Liquid oxygen pump (pressure feeding means)
4 ... Oxygen heater (heating means)
5 ... catalyst reaction cylinder 6 ... adsorber 6A, 6B ... adsorption cylinder 7 ... deoxygenation tower (separation means)
8 ... Differential pressure gauge (pressure measuring means)
9 ... Flow meter (measuring means)
10 ... Inverter (control means)
DESCRIPTION OF SYMBOLS 11 ... Buffer tank 12 ... Filter 13 ... Pressure reducing valve 14 ... Heat exchanger 15 ... Heater 16 ... Cooler 17 ... Drain separators 18-21 ... Valve 22 , 23, 24 ... pressure gauges L1-L5 ... flow path

Claims (3)

An operation method of an air liquefaction separation apparatus for extracting liquid oxygen enriched with krypton and xenon from the bottom of a low-pressure column of a double rectification column, and separating krypton and xenon by low-temperature rectification using it as a raw material,
A pumping step of compressing liquid oxygen enriched with krypton and xenon to a critical pressure or higher by a pumping means provided on the secondary side of the double rectification column, and deriving at a predetermined flow rate;
A pressure reducing step for raising the liquid oxygen derived from the pressure feeding means to room temperature and then introducing it into the pressure reducing means, and reducing the pressure to a critical pressure or lower;
A catalytic reaction step of introducing oxygen gas having a pressure equal to or lower than the critical pressure derived from the depressurization means into a catalytic reaction cylinder, and reacting hydrocarbons contained in the liquid oxygen with oxygen to generate water and carbon dioxide;
The gas derived from the catalyst reaction cylinder is introduced into at least one adsorption cylinder of a switching type adsorber having two or more adsorption cylinders that alternately perform adsorption, regeneration, and charging, and water and carbon dioxide are extracted from the gas. An adsorption process for adsorbing and removing carbon;
After the gas derived from the adsorber is divided into two, after cooling one gas, krypton and xenon are introduced into a post-process for low-temperature rectification, and the other gas is introduced into the regenerated adsorption cylinder and the adsorption cylinder A charging step for charging
The flow rate or the pressure is measured continuously or at predetermined intervals so that the flow rate or pressure of the one gas introduced into the post-process for rectifying krypton and xenon at a low temperature is constant. And a step of controlling by increasing or decreasing the flow rate of the liquid oxygen derived from the pumping means in accordance with the fluctuation amount of the measured value of the air liquefaction separation apparatus. In the catalytic reaction step,
Introducing the liquid oxygen derived from the pumping means into the heating means;
2. A method for operating an air liquefaction separation apparatus according to claim 1, wherein the differential pressure between the primary side and the secondary side of the heating means is measured continuously or at predetermined intervals. An air liquefaction separation apparatus for extracting liquid oxygen enriched with krypton and xenon from the bottom of a low-pressure column of a double rectification column, and separating krypton and xenon by low-temperature rectification using it as a raw material,
A pumping means provided on the secondary side of the double rectification column, compressing liquid oxygen enriched with krypton and xenon to a critical pressure or more and deriving at a predetermined flow rate;
Heating means for raising the temperature of the liquid oxygen derived from the pressure feeding means to room temperature;
Pressure measuring means for measuring a differential pressure between the primary side and the secondary side of the heating means;
Pressure reducing means for reducing the pressure in the supercritical state derived from the heating means to a critical pressure or less;
A catalytic reaction cylinder for producing water and carbon dioxide by reacting hydrocarbons and oxygen contained in an oxygen gas having a critical pressure or less derived from the decompression means;
A switchable adsorber having two or more adsorption cylinders that alternately perform adsorption, regeneration, and charging, and that adsorbs and removes water and carbon dioxide from the gas derived from the catalyst reaction cylinder;
Separation means provided on the secondary side of the adsorber and separating krypton and xenon from the remainder of the fluid derived from the adsorber;
Measurement means for measuring at least one of the flow rate and pressure of the fluid introduced into the separation means;
An air liquefaction separation apparatus comprising: control means for controlling the flow rate of the liquid oxygen from the pressure feeding means to be increased or decreased based on at least one measurement value of the flow rate and pressure of the measurement means. .

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