JP2012214325A - Ammonia purifying system and method for purifying ammonia - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ammonia purifying system capable of efficiently adsorbing and removing water and hydrocarbons present as impurities in crude ammonia by taking full advantage of adsorptive capacity of an adsorbent and purifying ammonia by a simplified method.SOLUTION: The ammonia purifying system 100 is a system for purifying crude ammonia and includes a condenser 2, a distillation column 5 and an adsorbing means 3. The condenser 2 or the distillation column 5 condenses a part of gaseous ammonia delivered from a stock material storage tank 1 and discharges liquid ammonia. The adsorbing means 3 adsorbs and removes impurities in the liquid ammonia discharged from the condenser 2 or the distillation column 5 with MS-13X solely having adsorbing power to water and hydrocarbons.

Description

  The present invention relates to an ammonia purification system for purifying crude ammonia and a method for purifying ammonia.

  In a semiconductor manufacturing process and a liquid crystal manufacturing process, high-purity ammonia is used as a processing agent used for producing a nitride film. Such high-purity ammonia can be obtained by purifying crude ammonia to remove impurities.

  The crude ammonia contains hydrogen, nitrogen, oxygen, argon, nitrogen monoxide, carbon dioxide and other low-boiling gases, hydrocarbons, moisture, etc. as impurities, and the purity of generally available crude ammonia is It is about 98 to 99% by weight.

  Generally, hydrocarbons contained in crude ammonia are mainly those having 1 to 4 carbon atoms. However, when producing hydrogen gas used as a raw material for ammonia synthesis, the oil content in the cracking gas is insufficiently separated. Or, when the oil is contaminated with pump oil from pumps during production, hydrocarbons having a high boiling point and a large molecular weight may be mixed. Moreover, if ammonia contains a large amount of moisture, the function of a semiconductor or the like manufactured using this ammonia may be greatly reduced, and the moisture in ammonia needs to be reduced as much as possible.

  Depending on the type of process in which ammonia is used in the semiconductor manufacturing process and the liquid crystal manufacturing process, the effect of impurities in ammonia varies, but the purity of ammonia is 99.9999% by weight or more (each impurity concentration is 100 ppb or less). Preferably, it is required to be about 99.99999% by weight. In recent years, a moisture concentration of less than 30 ppb has been demanded for the production of a light emitter such as gallium nitride.

  As a method for removing impurities contained in crude ammonia, a method for adsorbing and removing impurities using an adsorbent such as silica gel, synthetic zeolite and activated carbon, and a method for removing impurities by distillation are known.

  For example, Patent Document 1 discloses a first distillation column that removes low-volatile impurities from liquid crude ammonia, and impurities (mainly moisture) contained in gaseous ammonia derived from the first distillation column. An ammonia purification system is disclosed that includes an adsorption tower that adsorbs and removes with an adsorbent, and a second distillation tower that removes highly volatile impurities from gaseous ammonia derived from the adsorption tower. Patent Document 2 discloses a method of purifying ammonia by distilling and removing moisture contained in gaseous crude ammonia with an adsorbent composed of barium oxide.

JP 2006-206410 A JP 2003-183021 A

  As an adsorbent that adsorbs and removes impurities contained in crude ammonia, it is common to distinguish between adsorbents that have a high adsorption capacity for moisture and adsorbents that have a high adsorption capacity for hydrocarbons. In the technology for purifying ammonia disclosed in Patent Document 1, moisture is adsorbed and removed by an adsorbent composed of synthetic zeolite 3A, and in the technology for purifying ammonia disclosed in Patent Document 2, adsorption composed of barium oxide is performed. Moisture is absorbed and removed by the agent.

  In order to adsorb and remove moisture and hydrocarbon impurities contained in crude ammonia, an adsorption tower packed with an adsorbent having a high adsorption capacity for moisture and an adsorbent having a high adsorption capacity for hydrocarbons It is necessary to make it the structure provided with a plurality of adsorption towers with the adsorption tower filled with or a structure where a plurality of adsorbents are stacked and packed in one adsorption tower.

  When a plurality of adsorbents are stacked in one adsorption tower, when the amount ratio of moisture and hydrocarbons contained as impurities in the crude ammonia varies, even if one adsorbent has not reached adsorption saturation The other adsorbent reaches adsorption saturation and breaks through. For this reason, it is not possible to efficiently absorb and remove moisture and hydrocarbons contained in the crude ammonia by making maximum use of the adsorption capacity of the adsorbent, and the management of adsorbent breakthrough becomes complicated. End up.

  Accordingly, an object of the present invention is to efficiently remove moisture and hydrocarbons contained as impurities in crude ammonia by making maximum use of the adsorption capacity of the adsorbent and to remove ammonia by a simplified method. To provide an ammonia purification system that can be purified, and a method for purifying ammonia.

The present invention is an ammonia purification system for purifying crude ammonia,
Storage means for storing liquid crude ammonia so as to form a gas phase, leaving most of low-volatile impurities in the liquid phase, and deriving a part of the gas phase as gaseous ammonia;
Condensing means for condensing a part of the gaseous ammonia derived from the storage means and deriving liquid ammonia;
An adsorbing means for adsorbing and removing impurities contained in liquid ammonia derived from the condensing means by an adsorbent having adsorption ability for moisture and hydrocarbons alone to obtain purified liquid ammonia; It is an ammonia purification system characterized by including.

  Further, in the ammonia purification system of the present invention, the adsorption means is a plurality of adsorption towers that adsorb and remove impurities contained in liquid ammonia derived from the condensation means, and a plurality of adsorption towers connected in series. It is characterized by having.

  In the ammonia purification system of the present invention, the adsorbent is a porous synthetic zeolite.

  In the ammonia purification system of the present invention, the synthetic zeolite is MS-13X.

The present invention also provides a method for purifying crude ammonia,
A storage step of storing liquid crude ammonia so as to form a gas phase, leaving most of low-volatile impurities in the liquid phase, and deriving a part of the gas phase as gaseous ammonia;
A condensation step of condensing part of the gaseous ammonia derived in the storage step and deriving liquid ammonia;
An adsorption step for obtaining and purifying purified liquid ammonia by adsorbing and removing impurities contained in the liquid ammonia derived in the condensation step by an adsorbent having adsorption ability for moisture and hydrocarbons alone. It is the purification method of ammonia characterized by including.

  According to the present invention, the ammonia purification system is a system for purifying crude ammonia containing impurities, and includes a storage means, a condensation means, and an adsorption means. The storage means stores liquid crude ammonia so as to form a gas phase, leaves most of the low-volatile impurities in the liquid phase, and derives part of the gas phase as gaseous ammonia. The condensing unit condenses part of the gaseous ammonia derived from the storage unit, and derives liquid ammonia. Then, the adsorbing means adsorbs and removes impurities contained in the liquid ammonia derived from the condensing means by an adsorbent having an adsorption ability for moisture and hydrocarbons alone to obtain purified liquid ammonia. .

  In the ammonia purification system of the present invention, the condensing means condenses a part of gaseous ammonia, so that highly volatile impurities contained in the ammonia derived from the storage means are separated and removed as gas phase components. Liquid ammonia can be derived. The adsorbing means adsorbs and removes the impurities contained in the liquid ammonia derived from the condensing means by the adsorbent having the ability to adsorb moisture and hydrocarbons alone. It is not necessary to use a plurality of adsorbents of an adsorbent having an adsorbing ability and an adsorbent having an adsorbing ability for hydrocarbons. Therefore, moisture and hydrocarbons contained in liquid ammonia as impurities can be efficiently adsorbed and removed by making full use of the adsorption capacity of the adsorbent, and the management of adsorbent breakthrough is simplified. be able to.

  According to the invention, the suction means has a plurality of suction portions connected in series. By having a plurality of adsorbing sections connected in series with the adsorbing means, it is possible to improve the adsorbing and removing ability for impurities contained in the liquid ammonia derived from the condensing means.

  According to the present invention, the adsorbent used in the adsorbing means is a porous synthetic zeolite. Thus, moisture and hydrocarbons contained as impurities in the liquid ammonia derived from the condensing means can be efficiently adsorbed and removed.

  According to the present invention, the synthetic zeolite used as the adsorbent is MS-13X. This makes it possible to efficiently adsorb and remove moisture and hydrocarbons (particularly higher-order hydrocarbons such as butane, pentane and hexane) contained as impurities in the liquid ammonia derived from the condensing means.

  According to the present invention, the ammonia purification method is a method for purifying crude ammonia containing impurities, and includes a storage step, a condensation step, and an adsorption step. In the storage step, liquid crude ammonia is stored so as to form a gas phase, and most of low-volatile impurities are left in the liquid phase, and a part of the gas phase is derived as gaseous ammonia. In the condensation step, a part of the gaseous ammonia derived in the storage step is condensed to derive liquid ammonia. In the adsorption step, the impurities contained in the liquid ammonia derived in the condensation step are adsorbed and removed by an adsorbent having an adsorption ability for moisture and hydrocarbons alone to obtain purified liquid ammonia. .

  In the ammonia purification method of the present invention, in the condensation step, a part of gaseous ammonia is condensed, so that highly volatile impurities contained in the ammonia derived in the storage step are separated and removed as gas phase components. Liquid ammonia can be derived. In the adsorption process, the impurities contained in the liquid ammonia derived in the condensation process are adsorbed and removed by the adsorbent having adsorption ability for water and hydrocarbons alone. It is not necessary to use a plurality of adsorbents of an adsorbent having an adsorbing ability and an adsorbent having an adsorbing ability for hydrocarbons. Therefore, moisture and hydrocarbons contained in liquid ammonia as impurities can be efficiently adsorbed and removed by making full use of the adsorption capacity of the adsorbent, and the management of adsorbent breakthrough is simplified. be able to.

It is a figure which shows the structure of the ammonia purification system 100 which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the ammonia purification system 200 which concerns on 2nd Embodiment of this invention.

  FIG. 1 is a diagram showing a configuration of an ammonia purification system 100 according to the first embodiment of the present invention. The ammonia purification system 100 of this embodiment is a system for purifying liquid crude ammonia containing impurities.

  The ammonia purification system 100 includes a raw material storage tank 1 that is a storage means, a condenser 2 or a distillation column 5 that is a condensation means, an adsorption means 3, an analysis means 4, and a product tank 6. Further, the ammonia purification system 100 realizes the ammonia purification method according to the present invention, executes a storage process in the raw material storage tank 1, executes a condensation process in the condenser 2 or the distillation tower 5, and performs an adsorption process in the adsorption means 3. Execute.

  The raw material storage tank 1 stores crude ammonia. In the present embodiment, the crude ammonia stored in the raw material storage tank 1 has a purity of 99% by weight or more, preferably a purity of 99.0 to 99.9% by weight.

  The raw material storage tank 1 is not particularly limited as long as it is a heat insulating container having pressure resistance and corrosion resistance. The raw material storage tank 1 stores crude ammonia as liquid ammonia and is controlled so that temperature and pressure are constant. In a state where the raw material storage tank 1 stores liquid crude ammonia, a gas phase is formed in the upper part of the raw material storage tank 1, and a liquid phase is formed in the lower part. In the present embodiment, when the ammonia is led out from the raw material storage tank 1 to the condenser 2 or the distillation column 5, the ammonia is liquefied with a large amount of low-volatile impurities (for example, moisture and hydrocarbons having 9 or more carbon atoms). It leaves in the phase and is derived as gaseous ammonia from the gas phase.

  A first pipe 81 is connected between the raw material storage tank 1 and the capacitor 2, and gaseous ammonia derived from the raw material storage tank 1 flows through the first pipe 81 and is supplied to the capacitor 2. The

  The first pipe 81 is provided with a first valve 811 and an opening / closing valve 812 that open or close a flow path in the first pipe 81. When supplying gaseous ammonia to the condenser 2, the first valve 811 and the opening / closing valve 812 are opened, and an opening / closing valve 811 a, which will be described later, is closed, so that the first pipe is directed from the raw material storage tank 1 toward the condenser 2. Gaseous ammonia flows through 81. In the first pipe 81, the first valve 811 is provided closer to the raw material storage tank 1 than the opening / closing valve 812.

  The first pipe 81 is connected to a branch pipe 81a branched from the first pipe 81 between the first valve 811 and the open / close valve 812. The branch pipe 81a is connected to a flow path in the branch pipe 81a. An open / close valve 811a is provided to open or close the valve.

  The branch pipe 81 a is connected to the central space 53 of the distillation column 5. When supplying gaseous ammonia derived from the raw material storage tank 1 to the distillation column 5, the first valve 811 and the opening / closing valve 811a are opened, and the open / close valve 812 is closed, whereby the distillation from the raw material storage tank 1 is performed. Gaseous ammonia flows through the first pipe 81 and the branch pipe 81a toward the tower 5.

  The raw material storage tank 1 communicates with the raw material storage tank 1 and the outside, and has high volatility impurities distributed in the gas phase (for example, hydrogen, nitrogen, oxygen, argon, carbon monoxide, carbon dioxide, and An exhaust pipe 81b serving as a flow path for discharging (C1-C8 hydrocarbon) to the outside is connected. The exhaust pipe 81b is provided with an exhaust valve 811b that opens or closes a flow path in the exhaust pipe 81b. The ammonia purification system 100 of this embodiment discharges and removes highly volatile impurities from the crude ammonia stored in the raw material storage tank 1 by opening the exhaust valve 811b with the first valve 811 closed. It is comprised so that discharge operation to perform can be implemented.

  Specifically, after liquid crude ammonia is stored in the raw material storage tank 1 for 0.5 to 3 days, the exhaust valve 811b is opened for 10 to 300 minutes with the first valve 811 closed. Thus, highly volatile impurities in the crude ammonia distributed in the gas phase formed in the raw material storage tank 1 can be discharged through the exhaust pipe 81b.

  When the first valve 811 and the opening / closing valve 812 are opened and the opening / closing valve 811 a is closed, gaseous ammonia flowing through the first pipe 81 is introduced into the condenser 2.

  Here, the condensation of gaseous ammonia by the condenser 2 as the condensing means in the ammonia purification system 100 of the present embodiment will be described.

  Capacitor 2 degenerates gaseous ammonia derived from raw material storage tank 1 and separates it into a gas phase component and a liquid phase component, thereby removing highly volatile impurities contained in ammonia in the gas phase component. To separate and remove.

  Impurities contained in industrially produced ammonia (crude ammonia) can be broadly classified into dissolved low boiling point gases such as hydrogen, nitrogen, oxygen, argon, carbon monoxide and carbon dioxide. , Hydrocarbons, moisture and the like. As the hydrocarbons contained in the crude ammonia, methane is the most abundant, but ethane, propane, ethylene, propylene, etc. are the second most abundant. In terms of carbon number, hydrocarbons having 1 to 3 carbon atoms constitute the main component of hydrocarbons.

  However, the crude ammonia contains hydrocarbons having 4 or more carbon atoms, and in many cases hydrocarbons having 4 to 6 carbon atoms, although the content thereof is small. In addition, when liquefying industrially produced ammonia gas, an oil pump or the like is used for compression. In such a case, hydrocarbons having a large molecular weight such as oil components derived from pump oil mixed from an oil pump or the like are contained in the crude ammonia.

  An ammonia refining system capable of removing hydrocarbons having a wide range of carbon atoms constituting these impurities is essential for producing ammonia for the electronic industry.

  Table 1 shows the boiling points of ammonia and saturated n-hydrocarbons having 1 to 8 carbon atoms, but hydrocarbons having 4 to 8 carbon atoms have boiling points higher than that of ammonia when the hydrocarbons exist as pure substances. However, in the rectification operation, it is discharged from the top of the distillation column as a highly volatile compound.

  Although this reason is not certain, the present inventors presume as this reason as follows. That is, when the boiling point of a hydrocarbon having 1 to 8 carbon atoms is, for example, the boiling point of propane having 3 carbon atoms, when the temperature is changed by putting propane into the container, the pressure in the container is This is the temperature at 1 atm (0.1013 MPa). The state of propane at this time is a state in which adjacent propane molecules are pulled with each other by van der Waals force or the like, and when the pulling force is strong, the boiling point appears high. However, in the situation where the concentration of propane present in ammonia is very low, which is now a problem, there is no propane molecule or other hydrocarbon molecule that can be attracted next to the propane molecule. In fact, there is just one propane molecule floating in the liquid ammonia sea.

  In general, a large intermolecular force is created between those with similar properties, such as between hydrocarbon molecules and between ammonia molecules, but between molecules with very different properties, such as propane molecules and ammonia molecules. The intermolecular force born between them is small. Thus, in the situation where a very small amount of hydrocarbon impurities are present in ammonia, the conventional distillation concept is no longer meaningful. In liquid ammonia, the ammonia molecules exert a pulling force on each other. On the other hand, even if the pure substance is a hydrocarbon having 4 to 8 carbon atoms having a boiling point higher than that of ammonia, they are ammonia molecules. It is no wonder that even in liquid ammonia it behaves as a compound with a boiling point lower than that of ammonia because of its small interaction. In fact, the results of rectification show that hydrocarbons having 1 to 8 carbon atoms behave as highly volatile compounds having a boiling point lower than that of ammonia.

  Various concentrations of hydrocarbons having 1 to 8 carbon atoms contained in a small amount of ammonia in the gas phase and liquid phase of liquid ammonia are shown by varying the temperature. Table 2 shows the measurement results when the concentration in ammonia reached a gas-liquid equilibrium state. The distribution ratio was measured after adjusting the initial concentration in liquid ammonia of each saturated n-hydrocarbon concentration to 500 to 5000 ppm, and then standing at a predetermined temperature for 2 days and nights.

The gas-liquid distribution coefficient shown in Table 2 is an index of how much impurities can be separated by partial contraction, and is defined as follows.
Distribution coefficient (Kd) = A ₁ / A ₂ (1)
Wherein, A ₁ represents an impurity concentration of gaseous ammonia after the gas-liquid equilibrium, A ₂ represents an impurity concentration of liquid ammonia after gas-liquid equilibrium. ]

However, the impurity concentrations A ₁ and A ₂ in the above formula (1) have mol-ppm as the unit, and the definition is the following formula (2).
Impurity concentration (A ₁ , A ₂ ) =
Impurity (mol) / (ammonia (mol) + impurity (mol)) × 10 ⁶
... (2)

  According to this definition, the larger the gas-liquid partition coefficient, the greater the amount of impurities contained in the uncondensed gaseous ammonia that has not been condensed by partial condensation. A hydrocarbon having a smaller carbon number has a higher ratio in the gas phase than in the liquid phase, and a hydrocarbon having a carbon number of up to 8 exists in a higher concentration in the gas phase. Furthermore, the lower the temperature, the higher the concentration of hydrocarbons in the ammonia gas phase.

  Furthermore, it has been found that the time to reach equilibrium becomes longer as the concentration of hydrocarbons contained in ammonia becomes lower, and it takes several days to reach equilibrium at concentrations on the order of ppm. This means that in the operation of removing impurities in ammonia by rectification, the mass transfer of hydrocarbons as impurities is not sufficiently performed in the short gas-liquid contact time that occurs in each distillation stage of the rectification column. From the results, it is considered that the method using rectification for purifying ammonia is industrially ineffective. Table 2 shows data for saturated straight-chain hydrocarbons. In the case of 4 or more carbon atoms, the corresponding various isomers, and in the case of hydrocarbons of 2 or more carbon atoms, unsaturated bonds are included in the molecule. There is also a tendency shown in Table 2.

  As described above, the present inventors confirmed that the behavior of the hydrocarbon having 1 to 8 carbon atoms, which is a dilute impurity in the crude ammonia, is significantly different from the state considered in the past, and proceeded one step further. Thus, it was considered that the difference in properties of this hydrocarbon having 1 to 8 carbon atoms in ammonia could be used for purification of ammonia.

  Therefore, 95% of gaseous crude ammonia containing methane, ethane and propane at about 5000 ppm, about 500 ppm and about 500 ppm, respectively, maintaining the ammonia gas temperature at −20 ° C., and setting the wall temperature in the capacitor 2 to −30 ° C. When liquefied by condensation, these hydrocarbons were not detected in the liquid ammonia obtained, and it was found that most of the impurities remained in the gaseous ammonia that was not condensed.

  According to the distribution ratio in Table 2, it is calculated that methane, ethane and propane are present at 54 ppm, 24 ppm and 56 ppm, respectively, in the liquid ammonia condensed at −20 ° C. by the partial reduction operation. However, the partial reduction in the capacitor 2 has a much smaller value, and it has been found that the crude ammonia can be purified to a very high purity within a short time.

  Furthermore, when the impurities contained in ammonia are hydrocarbons having 1 to 8 carbon atoms, the present inventors use the capacitor 2 to perform partial contraction with liquefaction of gaseous ammonia to about 90 to 99.5%. The fact that the concentration of impurities contained in liquid ammonia obtained as a liquid phase component is greatly reduced compared to the concentration of impurities contained in the first gaseous ammonia even after operation. I found.

  In the purification method in which impurities contained in ammonia are separated and removed by partial condensation in the condenser 2, the liquid ammonia obtained as a liquid phase component by partial condensation is the value expected from the gas-liquid distribution ratio as described above. Beyond that, the concentration of impurity hydrocarbons is much lower. The reason for this is not clear, but it is presumed that in the partial reduction, the equilibrium relationship is lost and dynamic impurity separation occurs, and most of the impurity hydrocarbons remain in the vapor phase components that are not condensed. The correctness of this inference is that the liquid ammonia obtained as a liquid phase component by the partial contraction in the capacitor 2 is not taken out of the capacitor 2 quickly, but in the liquid ammonia state for a while. However, it is supported by the fact that the concentration of impurity hydrocarbons in the liquid ammonia gradually increases.

  This inference and observation result shows that liquid ammonia obtained as a liquid phase component by partial contraction in the capacitor 2 is quickly derived from the capacitor 2, and only an uncondensed gas phase component exists in the capacitor 2. Thus, it is shown that the operation of the capacitor 2 is necessary to obtain high-purity ammonia.

  In order to increase the purification efficiency of ammonia, it is only a guide, but a larger gas-liquid distribution coefficient is considered preferable. As described above, this gas-liquid distribution coefficient is affected by temperature, and a larger gas-liquid distribution coefficient can be obtained as the partial contraction temperature is lower. This means that when the set temperature of the partial contraction operation in the capacitor 2 is high, for example, when the temperature at which the partial contraction of ammonia is 50 ° C., the ammonia pressure supplied to the capacitor 2 is 1.81 MPa or more. This means that the separation efficiency of the hydrocarbon impurities may be reduced as compared with the case where the set temperature of the partial reduction operation is low.

  Capacitor 2 degenerates gaseous ammonia derived from raw material storage tank 1 and separates it into a gas phase component and a liquid phase component, so that hydrogen, nitrogen, oxygen, argon, carbon monoxide, carbon dioxide, Then, hydrocarbons having 1 to 8 carbon atoms (highly volatile impurities) are separated and removed as gas phase components to obtain liquid ammonia purified as liquid phase components. Specifically, the condenser 2 condenses ammonia to gaseous ammonia derived from the raw material storage tank 1 by a cooling process so that a part of the ammonia becomes a gas phase component. And liquid phase components. Examples of the condenser 2 include a multi-tube condenser and a plate heat exchanger.

  In the present embodiment, the capacitor 2 condenses 70 to 99% by volume of gaseous ammonia derived from the raw material storage tank 1 and separates it into a gas phase component and a liquid phase component. In this case, 1 to 30% by volume, which is a part of gaseous ammonia derived from the raw material storage tank 1, is condensed so as to become a gas phase component and separated into a gas phase component and a liquid phase component. It will be. As a result, highly volatile impurities contained in gaseous ammonia derived from the raw material storage tank 1 can be separated and removed as a gas phase component, and liquid ammonia purified as a liquid phase component can be obtained with high yield. it can.

  Further, the condensation conditions in the condenser 2 are not limited as long as a part of the gaseous ammonia derived from the raw material storage tank 1 becomes a liquid, and the temperature, pressure and time are appropriately set. do it. In the present embodiment, the capacitor 2 is configured to condense gaseous ammonia derived from the raw material storage tank 1 at a temperature of −77 to 50 ° C. and separate it into a gas phase component and a liquid phase component. It is preferable. As a result, it is possible to obtain liquid ammonia purified by efficiently condensing gaseous ammonia derived from the raw material storage tank 1, and to increase the purity of the liquid ammonia.

  When the temperature at the time of condensation with respect to gaseous ammonia in the condenser 2 is less than −77 ° C., it is not preferable because a lot of energy is required for cooling. Since the concentration of impurities contained in the liquid ammonia obtained by condensation increases, it is not preferable.

  Capacitor 2 is configured to condense gaseous ammonia derived from raw material storage tank 1 under a pressure of 0.007 to 2.0 MPa and separate it into a gas phase component and a liquid phase component. Is preferred. When the pressure at the time of condensation with respect to gaseous ammonia in the condenser 2 is less than 0.007 MPa, the temperature at which ammonia is condensed is lowered, and therefore, a lot of energy is required for cooling, which is not preferable. If it exceeds 0.0 MPa, the temperature at which ammonia is condensed becomes high, which is not preferable because the concentration of impurities contained in liquid ammonia obtained by condensing a part of ammonia is high.

  In the ammonia purification system 100 of the present embodiment, the condenser 2 condenses a part of gaseous ammonia derived from the raw material storage tank 1 and separates it into a gas phase component and a liquid phase component, so that it has high volatility. Impurities are separated and removed as gas phase components, and liquid ammonia purified as a liquid phase component can be obtained.

  An exhaust pipe 81c provided with an exhaust valve 811c is connected to the capacitor 2. In the capacitor 2, highly volatile impurities separated and removed from ammonia as a gas phase component are discharged to the outside of the system through the exhaust pipe 81 c with the exhaust valve 811 c opened.

  Further, in the ammonia purification system 100, the gaseous ammonia flowing through the first pipe 81 and the branch pipe 81a when the first valve 811 and the open / close valve 811a are opened and the open / close valve 812 is closed is not removed from the distillation tower. 5 is introduced.

  The distillation column 5 distills and removes highly volatile impurities contained in gaseous ammonia derived from the raw material storage tank 1. In addition, the distillation column 5 can distill off impurities such as dimethyl ether and methanol that are difficult to remove only by the fractional operation by the condenser 2.

  The distillation column 5 forms a bottom space portion 55, a lower distillation portion 54, a central space portion 53, an upper distillation portion 52, and an upper space portion 51 in order from the bottom, and a heating device 55a is installed in the bottom space portion 55. The capacitor 2 described above is installed in the space 51. A heating medium such as heated water is supplied from the outside to the heating device 55a to support ammonia reboil, and a refrigerant such as cooling water is supplied to the condenser 2 from the outside to support condensation of ammonia.

  Gaseous ammonia introduced from the raw material storage tank 1 into the central space 53 of the distillation column 5 via the branch pipe 81a rises in the upper distillation part 52 and comes into gas-liquid contact with the refluxing liquid flowing down and rectifying. Is done. That is, the ammonia contained in the rising gas phase is dissolved in the reflux liquid, and highly volatile impurities dissolved in the reflux liquid are vaporized. At this time, the ammonia which has been condensed and purified by removing impurities with high volatility is led out from the bottom space portion 55 except for a part that flows back to the top space portion 55 and then refluxed to the top of the upper distillation portion 52. The On the other hand, highly volatile impurities rise to the upper space 51 to become a concentrated gas, which is cooled by the condenser 2 and continuously discharged as exhaust gas through the exhaust pipe 81c.

  A second pipe 82 provided with a second valve 821 is connected to the bottom space 55, and liquid ammonia condensed by the condenser 2 and led out from the condenser 2 or a distillation operation of the distillation column 5. The liquid ammonia condensed and discharged from the bottom space 55 flows through the second pipe 82 and is supplied to the adsorption means 3 with the second valve 821 opened.

  The adsorbing means 3 adsorbs and removes impurities contained in the liquid ammonia led out from the condenser 2 or the distillation column 5 with an adsorbent to obtain purified liquid ammonia. In the present embodiment, the adsorption means 3 includes a first adsorption tower 31, a second adsorption tower 32, a third adsorption tower 33, and a fourth adsorption tower 34, which are a plurality of adsorption units.

  The adsorbent filled in each of the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 has an adsorption ability for moisture and hydrocarbons alone. Examples of such an adsorbent include porous synthetic zeolite. Among the synthetic zeolites, a synthetic zeolite having a pore diameter of 5 to 9 mm is preferable, MS-5A is exemplified as a synthetic zeolite having a pore diameter of 5 mm, and MS-13X is exemplified as a synthetic zeolite having a pore diameter of 9 mm. Among these, it is particularly preferable to use MS-13X, which is a synthetic zeolite having a pore size of 9 mm, as an adsorbent. The adsorbent used in the present embodiment can be regenerated by desorbing the adsorbed impurities (water and hydrocarbons) by any one of heating, decompression, heating and decompression. For example, when desorbing impurities adsorbed on the adsorbent by heat treatment, heating may be performed at a temperature of 200 to 350 ° C.

  In the ammonia purification system 100 of the present embodiment, the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 are made of an adsorbent having an adsorption ability for moisture and hydrocarbons alone. Since impurities contained in liquid ammonia are adsorbed and removed, it is necessary to use a plurality of adsorbents, that is, an adsorbent capable of adsorbing moisture and an adsorbent capable of adsorbing hydrocarbons, as in the prior art. Absent. Therefore, moisture and hydrocarbons contained as impurities in liquid ammonia can be efficiently adsorbed and removed by making maximum use of the adsorption capacity of the adsorbent.

  Furthermore, the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the like are obtained by adsorbing and removing impurities contained in liquid ammonia by an adsorbent having adsorption ability for water and hydrocarbons alone. Even when the quantity ratio of the moisture and hydrocarbons contained in the ammonia supplied to the fourth adsorption tower 34 varies, the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 Based on the analysis result of the amount of impurities of ammonia derived from the adsorption tower 34, the breakthrough of the adsorbent in the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 is managed. Easy to implement.

  Further, since the synthetic zeolite used as the adsorbent has a pore diameter of 5 to 9 mm, particularly MS-13X having a pore diameter of 9 mm, moisture and hydrocarbons contained as impurities in ammonia (particularly higher-order hydrocarbons) Can be efficiently adsorbed and removed.

  In addition, in the 1st adsorption tower 31, the 2nd adsorption tower 32, the 3rd adsorption tower 33, and the 4th adsorption tower 34, the adsorption agent which has adsorption ability with respect to moisture and hydrocarbon independently, and other adsorption agents are combined. However, it is preferable to use only an adsorbent having an adsorption ability for moisture and hydrocarbons alone. Examples of other adsorbents include MS-3A (pore diameter 3 mm) and MS-4A (pore diameter 4 mm), which are synthetic zeolites excellent in moisture adsorbability.

  The first adsorption tower 31 and the third adsorption tower 33 are connected to the third pipe 83 in parallel. The third pipe 83 is provided with a third valve 831 and a fourth valve 832 that open or close the flow path in the third pipe 83. In the third pipe 83, the third valve 831 is disposed upstream of the first adsorption tower 31 (that is, the tower top side of the first adsorption tower 31), and the fourth valve 832 is upstream of the third adsorption tower 33. It arrange | positions at the side (namely, tower | column top part side of the 3rd adsorption tower 33).

  When supplying liquid ammonia derived from the condenser 2 or the distillation column 5 to the first adsorption tower 31, the third valve 831 is opened, the fourth valve 832 is closed, and the second valve 832 is closed from the condenser 2 or the distillation tower 5. Liquid ammonia flows through the third pipe 83 toward the first adsorption tower 31. When supplying liquid ammonia derived from the condenser 2 or the distillation tower 5 to the third adsorption tower 33, the fourth valve 832 is opened and the third valve 831 is closed, so that the condenser 2 or the distillation tower 5 is closed. The liquid ammonia flows through the third pipe 83 toward the third adsorption tower 33.

  Thus, the adsorption means 3 has the first adsorption tower 31 and the third adsorption tower 33 connected in parallel, so that the liquid ammonia derived from the condenser 2 or the distillation tower 5 can be connected in parallel. Since it can introduce | transduce into the 1 adsorption tower 31 and the 3rd adsorption tower 33 in the state which each distinguished, for example, while carrying out adsorption removal by the 1st adsorption tower 31, used 3rd adsorption tower 33 is used. Thus, the used third adsorption tower 33 can be regenerated so that the adsorption removal operation can be performed again.

  The second adsorption tower 32 is connected in series with the first adsorption tower 31 via a fourth pipe 84. That is, in the fourth pipe 84, one end is connected to the tower bottom of the first adsorption tower 31 and the other end is connected to the tower top of the second adsorption tower 32. Thereby, the liquid ammonia led out from the condenser 2 or the distillation column 5 and introduced into the first adsorption tower 31 flows through the fourth pipe 84 and is introduced into the second adsorption tower 32. Thus, the adsorption means 3 has the first adsorption tower 31 and the second adsorption tower 32 connected in series, so that impurities contained in the liquid ammonia led out from the condenser 2 or the distillation tower 5 can be reduced. Since it can be adsorbed and removed by the first adsorption tower 31 and the second adsorption tower 32, the ability to adsorb and remove impurities can be improved.

  The liquid ammonia led out from the second adsorption tower 32 flows through the fifth pipe 85 and is supplied to the tenth pipe 90 connected to the product tank 6.

  The fifth pipe 85 is provided with a fifth valve 851 and a sixth valve 852 that open or close the flow path in the fifth pipe 85. In the fifth pipe 85, the fifth valve 851 is arranged upstream in the ammonia flow direction (that is, the second adsorption tower 32 side), and the sixth valve 852 is downstream in the ammonia flow direction (that is, the first flow direction). 10 piping 90 side). At the time of supplying liquid ammonia derived from the second adsorption tower 32 to the tenth pipe 90, the fifth valve 851 and the sixth valve 852 are opened, and the second adsorption tower 32 toward the tenth pipe 90 is opened. Liquid ammonia flows through the fifth pipe 85.

  In the ammonia purification system 100 of the present embodiment, an eighth pipe 88 branched from the fifth pipe 85 and connected to the analysis means 4 is provided between the fifth valve 851 and the sixth valve 852. . The eighth pipe 88 is provided with a ninth valve 881 that opens or closes the flow path in the eighth pipe 88. The ninth valve 881 is always opened when liquid ammonia derived from the condenser 2 or the distillation column 5 is introduced into the first adsorption column 31 and the second adsorption column 32, and is necessary for analysis. A very small amount of ammonia flows through the eighth pipe 88 toward the analysis means 4.

  The fourth adsorption tower 34 is connected in series with the third adsorption tower 33 via a sixth pipe 86. That is, in the sixth pipe 86, one end is connected to the tower bottom of the third adsorption tower 33 and the other end is connected to the tower top of the fourth adsorption tower 34. Thereby, the liquid ammonia led out from the condenser 2 or the distillation tower 5 and introduced into the third adsorption tower 33 flows through the sixth pipe 86 and is introduced into the fourth adsorption tower 34. Thus, the adsorption means 3 has the third adsorption tower 33 and the fourth adsorption tower 34 connected in series, so that impurities contained in the liquid ammonia derived from the condenser 2 or the distillation tower 5 can be reduced. Since it can be adsorbed and removed by the third adsorption tower 33 and the fourth adsorption tower 34, the ability to adsorb and remove impurities can be improved.

  The liquid ammonia led out from the fourth adsorption tower 34 flows through the seventh pipe 87 and is supplied to the tenth pipe 90 connected to the product tank 6.

  The seventh pipe 87 is provided with a seventh valve 871 and an eighth valve 872 that open or close the flow path in the seventh pipe 87. In the seventh pipe 87, the seventh valve 871 is disposed upstream in the ammonia flow direction (that is, the fourth adsorption tower 34 side), and the eighth valve 872 is disposed downstream in the ammonia flow direction (that is, the first flow direction). 10 piping 90 side). At the time of supplying liquid ammonia derived from the fourth adsorption tower 34 to the tenth pipe 90, the seventh valve 871 and the eighth valve 872 are opened, and the fourth adsorption tower 34 toward the tenth pipe 90 is opened. Liquid ammonia flows through the seventh pipe 87.

  Further, in the ammonia purification system 100 of the present embodiment, a ninth pipe 89 branched from the seventh pipe 87 and connected to the analysis means 4 is provided between the seventh valve 871 and the eighth valve 872. . The ninth pipe 89 is provided with a tenth valve 891 that opens or closes the flow path in the ninth pipe 89. The tenth valve 891 is always opened when liquid ammonia derived from the condenser 2 or the distillation column 5 is introduced into the third adsorption column 33 and the fourth adsorption column 34, and is necessary for analysis. A very small amount of ammonia flows through the ninth pipe 89 toward the analysis means 4.

  In the ammonia purification system 100 of the present embodiment, the temperature of the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 is controlled to 0 to 60 ° C., and the pressure is 0.1. It is controlled to ˜1.0 MPa. When the temperature of the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 is less than 0 ° C., cooling is required to remove the heat of adsorption generated during the adsorption removal of impurities. Thus, the energy efficiency may be reduced. When the temperature of the 1st adsorption tower 31, the 2nd adsorption tower 32, the 3rd adsorption tower 33, and the 4th adsorption tower 34 exceeds 60 ° C, there is a possibility that the adsorption capacity of impurities by an adsorbent may fall. Moreover, when the pressure of the 1st adsorption tower 31, the 2nd adsorption tower 32, the 3rd adsorption tower 33, and the 4th adsorption tower 34 is less than 0.1 Mpa, there exists a possibility that the adsorption capacity of the impurity by adsorbent may fall. . When the pressure in the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 exceeds 1.0 MPa, a large amount of energy is required to maintain a constant pressure. Efficiency may be reduced.

  The linear velocities (linear velocities) in the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 are such that liquid ammonia per unit time is converted into the first adsorption tower 31 and the first adsorption tower 31. The amount supplied to the second adsorption tower 32, the third adsorption tower 33, and the fourth adsorption tower 34 is converted into the gas volume of NTP, and the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33, and the fourth It is preferable that the range of the value obtained by dividing by the empty cross-sectional area of the adsorption tower 34 is 0.01 to 0.5 m / sec. When the linear velocity is less than 0.01 m / sec, it is not preferable because it takes a long time to remove impurities, and when the linear velocity exceeds 0.5 m / sec, the heat of adsorption generated during the adsorption removal of impurities. In this case, the adsorption capacity of the impurities by the adsorbent may be lowered.

  The liquid ammonia led out from the second adsorption tower 32 and flowing through the eighth pipe 88 or the liquid ammonia led out from the fourth adsorption tower 34 and passed through the ninth pipe 89 is analyzed by the analyzing means 4. To be introduced.

  The analysis means 4 analyzes the concentration of impurities contained in the liquid ammonia derived from the second adsorption tower 32 or the fourth adsorption tower 34. In this embodiment, the analysis means 4 is a gas chromatograph analyzer (GC-PDD: pulse discharge type detector). An example of the gas chromatograph analyzer is GC-4000 (manufactured by GL Sciences Inc.). Based on the analysis result by the analysis means 4, the breakthrough of the adsorbent in the first adsorption tower 31, the second adsorption tower 32, the third adsorption tower 33 and the fourth adsorption tower 34 is managed.

  The liquid ammonia supplied from the second adsorption tower 32 and supplied to the tenth pipe 90 or the liquid ammonia supplied from the fourth adsorption tower 34 and supplied to the tenth pipe 90 is the tenth valve. In a state where 901 is opened, the tenth pipe 90 is passed through and introduced into the product tank 6.

  The product tank 6 stores liquid ammonia derived from the second adsorption tower 32 or the fourth adsorption tower 34. It is preferable that the temperature and pressure of the product tank 6 are controlled under constant conditions so that the product tank 6 can be stored as liquid ammonia.

  The product tank 6 is connected to an eleventh pipe 91 that communicates the product tank 6 with the outside and serves as a flow path for discharging the gas phase component to the outside. The eleventh pipe 91 is provided with an eleventh valve 911 that opens or closes the flow path in the eleventh pipe 91. In the ammonia purification system 100 of the present embodiment, by opening the eleventh valve 911 with the tenth valve 901 closed, impurities having high volatility can be obtained from the liquid ammonia stored in the product tank 6. A discharge operation for discharging and removing can be performed. By performing the discharge operation in the product tank 6, the purity of the liquid ammonia stored in the product tank 6 can be further increased.

  FIG. 2 is a diagram showing a configuration of an ammonia purification system 200 according to the second embodiment of the present invention. The ammonia purification system 200 of the present embodiment is similar to the ammonia purification system 100 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. The ammonia purification system 200 is the same as the ammonia purification system 100 except that the configuration of the adsorption unit 201 is different from the configuration of the adsorption unit 3 described above.

  The adsorbing means 201 provided in the ammonia purification system 200 adsorbs and removes impurities contained in liquid ammonia led out from the condenser 2 or the distillation column 5 using an adsorbent. In the present embodiment, the adsorption unit 201 includes a first adsorption tower 2011, a second adsorption tower 2012, and a third adsorption tower 2013 that are a plurality of adsorption units.

  The first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013 are configured in the same manner as the first adsorption tower 31 described above. Specifically, the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013 are filled with an adsorbent having an adsorption ability for moisture and hydrocarbons alone.

  In the ammonia purification system 200 of the present embodiment, the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013 are controlled at a temperature of 0 to 60 ° C. and a pressure of 0.1 to 1.0 MPa. To be controlled. When the temperatures of the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013 are less than 0 ° C., cooling is required to remove the heat of adsorption generated during the adsorption removal of impurities, resulting in a decrease in energy efficiency. There is a risk. When the temperatures of the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013 exceed 60 ° C., the adsorbing ability of impurities by the adsorbent may be reduced. Moreover, when the pressure of the 1st adsorption tower 2011, the 2nd adsorption tower 2012, and the 3rd adsorption tower 2013 is less than 0.1 Mpa, there exists a possibility that the adsorption capacity of the impurity by adsorbent may fall. When the pressure in the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013 exceeds 1.0 MPa, a large amount of energy is required to maintain a constant pressure, and energy efficiency may be reduced. is there.

  The linear velocities (linear velocities) in the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013 are such that liquid ammonia is converted per unit time into the first adsorption tower 2011, the second adsorption tower 2012, and the second adsorption tower 2011. The range of values obtained by converting the amount supplied to the three adsorption towers 2013 into the gas volume in NTP and dividing by the empty cross-sectional areas of the first adsorption tower 2011, the second adsorption tower 2012 and the third adsorption tower 2013 is 0.01 to 0.5 m / sec is preferable. When the linear velocity is less than 0.01 m / sec, it is not preferable because it takes a long time to remove impurities, and when the linear velocity exceeds 0.5 m / sec, the heat of adsorption generated during the adsorption removal of impurities. In this case, the adsorption capacity of the impurities by the adsorbent may be lowered.

  In the present embodiment, the third piping 83 through which the liquid ammonia led out from the condenser 2 or the distillation column 5 flows is connected to the thirteenth piping 202, the fourteenth piping 203, and the first piping branched from the third piping 83. 15 pipes 204 are connected.

  The thirteenth pipe 202 branches from the third pipe 83 and is connected to the tower top of the first adsorption tower 2011. The thirteenth pipe 202 is provided with a thirteenth valve 2021 that opens or closes the flow path in the thirteenth pipe 202. The fourteenth pipe 203 branches from the third pipe 83 and is connected to the top of the second adsorption tower 2012. The fourteenth pipe 203 is provided with a fourteenth valve 2031 that opens or closes the flow path in the fourteenth pipe 203. The fifteenth pipe 204 branches from the third pipe 83 and is connected to the tower top of the third adsorption tower 2013. The fifteenth pipe 204 is provided with a fifteenth valve 2041 that opens or closes the flow path in the fifteenth pipe 204.

  A sixteenth pipe 205 through which liquid ammonia led out from the first adsorption tower 2011 flows is connected to the bottom of the first adsorption tower 2011. The sixteenth pipe 205 is provided with a sixteenth valve 2051 that opens or closes the flow path in the sixteenth pipe 205. A seventeenth pipe 206 through which liquid ammonia derived from the second adsorption tower 2012 flows is connected to the bottom of the second adsorption tower 2012. The seventeenth pipe 206 is provided with a seventeenth valve 2061 that opens or closes the flow path in the seventeenth pipe 206. An 18th pipe 207 through which liquid ammonia derived from the third adsorption tower 2013 flows is connected to the bottom of the third adsorption tower 2013. The eighteenth pipe 207 is provided with an eighteenth valve 2071 that opens or closes the flow path in the eighteenth pipe 207.

  In addition, a nineteenth pipe 208 branched from the sixteenth pipe 205 is connected to the sixteenth pipe 205. The nineteenth pipe 208 is branched from the sixteenth pipe 205 and connected to the fourteenth pipe 203, and a flow path for introducing liquid ammonia led out from the first adsorption tower 2011 into the second adsorption tower 2012. It becomes. The nineteenth pipe 208 is provided with a nineteenth valve 2081 that opens or closes the flow path in the nineteenth pipe 208. A twentieth pipe 209 branched from the nineteenth pipe 208 is connected to the nineteenth pipe 208. The twentieth pipe 209 is branched from the nineteenth pipe 208 and connected to the fifteenth pipe 204, and a flow path for introducing liquid ammonia led out from the first adsorption tower 2011 into the third adsorption tower 2013. It becomes. The twentieth pipe 209 is provided with a twentieth valve 2091 that opens or closes the flow path in the twentieth pipe 209.

  In addition, a twenty-first pipe 210 and a twenty-second pipe 211 branched from the seventeenth pipe 206 are connected to the seventeenth pipe 206. The twenty-first pipe 210 branches from the seventeenth pipe 206 and is connected to the thirteenth pipe 202, and a flow path for introducing liquid ammonia led out from the second adsorption tower 2012 into the first adsorption tower 2011. Become. The 21st pipe 210 is provided with a 21st valve 2101 that opens or closes the flow path in the 21st pipe 210. The twenty-second pipe 211 is branched from the seventeenth pipe 206 and connected to the fifteenth pipe 204, and a flow path for introducing liquid ammonia derived from the second adsorption tower 2012 into the third adsorption tower 2013. Become. The 22nd pipe 211 is provided with a 22nd valve 2111 for opening or closing the flow path in the 22nd pipe 211.

  In addition, a 23rd pipe 212 branched from the 18th pipe 207 is connected to the 18th pipe 207. The 23rd pipe 212 is branched from the 18th pipe 207 and connected to the 13th pipe 202, and a flow path for introducing liquid ammonia led out from the third adsorption tower 2013 into the first adsorption tower 2011. It becomes. The 23rd pipe 212 is provided with a 23rd valve 2121 for opening or closing the flow path in the 23rd pipe 212. A 24th pipe 213 branched from the 23rd pipe 212 is connected to the 23rd pipe 212. The twenty-fourth pipe 213 is branched from the twenty-third pipe 212 and connected to the fourteenth pipe 203, and a flow path for introducing liquid ammonia derived from the third adsorption tower 2013 into the second adsorption tower 2012. It becomes. The twenty-fourth pipe 213 is provided with a twenty-fourth valve 2131 that opens or closes the flow path in the twenty-fourth pipe 213.

  In the sixteenth pipe 205, the seventeenth pipe 206, and the eighteenth pipe 207, a 25th pipe 214 is connected to the downstream end of the liquid ammonia flow direction. The 25th pipe 214 is supplied with liquid ammonia derived from any one of the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013. The 25th pipe 214 is branched from the 25th pipe 214 and connected to the analysis means 4, and the 10th pipe 90 is branched from the 25th pipe 214 and connected to the product tank 6. Is provided.

  In the ammonia purification system 200 configured as described above, there are the following six connection patterns for connecting the first adsorption tower 2011, the second adsorption tower 2012, and the third adsorption tower 2013.

  The first connection pattern is a connection pattern that allows liquid ammonia derived from the condenser 2 or the distillation tower 5 to pass through the first adsorption tower 2011 and the second adsorption tower 2012 in this order. In the first connection pattern, the thirteenth valve 2021, the seventeenth valve 2061, and the nineteenth valve 2081 are opened, and the fourteenth valve 2031, the fifteenth valve 2041, the sixteenth valve 2051, the eighteenth valve 2071, the twentyth valve 2091, The 21st valve 2101, the 22nd valve 2111, the 23rd valve 2121 and the 24th valve 2131 are closed.

  As a result, the liquid ammonia derived from the condenser 2 or the distillation tower 5 flows through the thirteenth pipe 202 and is introduced into the first adsorption tower 2011, and the liquid ammonia derived from the first adsorption tower 2011. Is introduced into the second adsorption tower 2012 through the sixteenth pipe 205 and the nineteenth pipe 208, and the liquid ammonia led out from the second adsorption tower 2012 passes through the seventeenth pipe 206 and flows into the second adsorption tower 2012. The liquid ammonia is supplied to the analysis pipe 4 and the product tank 6 from the 25th pipe 214.

  In such a first connection pattern, since impurities contained in liquid ammonia can be adsorbed and removed by the first adsorption tower 2011 and the second adsorption tower 2012, the ability to adsorb and remove impurities can be improved. it can. In the first connection pattern, since the adsorption removal operation in the third adsorption tower 2013 is not executed, the third adsorption tower 2013 can be regenerated.

  The second connection pattern is a connection pattern that allows liquid ammonia derived from the condenser 2 or the distillation tower 5 to pass through the first adsorption tower 2011 and the third adsorption tower 2013 in this order. In the second connection pattern, the thirteenth valve 2021, the eighteenth valve 2071, and the twentieth valve 2091 are opened, the fourteenth valve 2031, the fifteenth valve 2041, the sixteenth valve 2051, the seventeenth valve 2061, the nineteenth valve 2081, The 21st valve 2101, the 22nd valve 2111, the 23rd valve 2121 and the 24th valve 2131 are closed.

  As a result, the liquid ammonia derived from the condenser 2 or the distillation tower 5 flows through the thirteenth pipe 202 and is introduced into the first adsorption tower 2011, and the liquid ammonia derived from the first adsorption tower 2011. Is passed through the 16th pipe 205, the 19th pipe 208 and the 20th pipe 209 and introduced into the third adsorption tower 2013, and the liquid ammonia led out from the third adsorption tower 2013 passes through the 18th pipe 207. It flows through and is supplied to the 25th pipe 214, and liquid ammonia is introduced into the analysis means 4 and the product tank 6 from the 25th pipe 214.

  In such a second connection pattern, since impurities contained in liquid ammonia can be adsorbed and removed by the first adsorption tower 2011 and the third adsorption tower 2013, the ability to adsorb and remove impurities can be improved. it can. In the second connection pattern, since the adsorption removal operation in the second adsorption tower 2012 is not executed, the second adsorption tower 2012 can be regenerated.

  The third connection pattern is a connection pattern that allows liquid ammonia derived from the condenser 2 or the distillation column 5 to pass through the second adsorption column 2012 and the first adsorption column 2011 in this order. In the third connection pattern, the fourteenth valve 2031, the sixteenth valve 2051, and the twenty-first valve 2101 are opened, and the thirteenth valve 2021, the fifteenth valve 2041, the seventeenth valve 2061, the eighteenth valve 2071, the nineteenth valve 2081, The 20th valve 2091, the 22nd valve 2111, the 23rd valve 2121 and the 24th valve 2131 are closed.

  As a result, the liquid ammonia derived from the condenser 2 or the distillation tower 5 flows through the fourteenth pipe 203 and is introduced into the second adsorption tower 2012, and the liquid ammonia derived from the second adsorption tower 2012 is obtained. Flows through the 17th pipe 206 and the 21st pipe 210 and is introduced into the first adsorption tower 2011, and the liquid ammonia led out from the first adsorption tower 2011 passes through the 16th pipe 205 and enters the first adsorption tower 2011. The liquid ammonia is supplied to the analysis pipe 4 and the product tank 6 from the 25th pipe 214.

  In such a third connection pattern, since impurities contained in liquid ammonia can be adsorbed and removed by the first adsorption tower 2011 and the second adsorption tower 2012, the ability to adsorb and remove impurities can be improved. it can. In the third connection pattern, the adsorption removal operation in the third adsorption tower 2013 is not executed, so that the third adsorption tower 2013 can be regenerated.

  The fourth connection pattern is a connection pattern that allows liquid ammonia derived from the condenser 2 or the distillation tower 5 to pass through the second adsorption tower 2012 and the third adsorption tower 2013 in this order. In the fourth connection pattern, the fourteenth valve 2031, the eighteenth valve 2071 and the twenty-second valve 2111 are opened, and the thirteenth valve 2021, the fifteenth valve 2041, the sixteenth valve 2051, the seventeenth valve 2061, the nineteenth valve 2081, The 20th valve 2091, the 21st valve 2101, the 23rd valve 2121 and the 24th valve 2131 are closed.

  As a result, the liquid ammonia derived from the condenser 2 or the distillation tower 5 flows through the fourteenth pipe 203 and is introduced into the second adsorption tower 2012, and the liquid ammonia derived from the second adsorption tower 2012 is obtained. Is introduced into the third adsorption tower 2013 through the 17th pipe 206 and the 22nd pipe 211, and the liquid ammonia led out from the third adsorption tower 2013 passes through the 18th pipe 207 and is introduced into the third adsorption tower 2013. The liquid ammonia is supplied to the analysis pipe 4 and the product tank 6 from the 25th pipe 214.

  In such a fourth connection pattern, the impurities contained in the liquid ammonia can be adsorbed and removed by the second adsorption tower 2012 and the third adsorption tower 2013, so that the ability to adsorb and remove impurities can be improved. it can. In the fourth connection pattern, the adsorption removal operation in the first adsorption tower 2011 is not executed, so that the first adsorption tower 2011 can be regenerated.

  The fifth connection pattern is a connection pattern that allows liquid ammonia derived from the condenser 2 or the distillation tower 5 to pass through the third adsorption tower 2013 and the first adsorption tower 2011 in this order. In the fifth connection pattern, the 15th valve 2041, the 16th valve 2051, and the 23rd valve 2121 are opened, and the 13th valve 2021, the 14th valve 2031, the 17th valve 2061, the 18th valve 2071, the 19th valve 2081, The 20th valve 2091, the 21st valve 2101, the 22nd valve 2111 and the 24th valve 2131 are closed.

  As a result, the liquid ammonia derived from the condenser 2 or the distillation tower 5 flows through the fifteenth pipe 204 and is introduced into the third adsorption tower 2013, and the liquid ammonia derived from the third adsorption tower 2013. Flows through the 18th pipe 207 and the 23rd pipe 212 and is introduced into the first adsorption tower 2011, and the liquid ammonia led out from the first adsorption tower 2011 passes through the 16th pipe 205 and enters the first adsorption tower 2011. The liquid ammonia is supplied to the analysis pipe 4 and the product tank 6 from the 25th pipe 214.

  In such a fifth connection pattern, since impurities contained in liquid ammonia can be adsorbed and removed by the first adsorption tower 2011 and the third adsorption tower 2013, the ability to adsorb and remove impurities can be improved. it can. In the fifth connection pattern, since the adsorption removal operation in the second adsorption tower 2012 is not executed, the second adsorption tower 2012 can be regenerated.

  The sixth connection pattern is a connection pattern that allows liquid ammonia derived from the condenser 2 or the distillation tower 5 to pass through the third adsorption tower 2013 and the second adsorption tower 2012 in this order. In the sixth connection pattern, the fifteenth valve 2041, the seventeenth valve 2061, and the twenty-fourth valve 2131 are opened, and the thirteenth valve 2021, the fourteenth valve 2031, the sixteenth valve 2051, the eighteenth valve 2071, the nineteenth valve 2081, The 20th valve 2091, the 21st valve 2101, the 22nd valve 2111 and the 23rd valve 2121 are closed.

  As a result, the liquid ammonia derived from the condenser 2 or the distillation tower 5 flows through the fifteenth pipe 204 and is introduced into the third adsorption tower 2013, and the liquid ammonia derived from the third adsorption tower 2013. Is passed through the 18th pipe 207, the 23rd pipe 212 and the 24th pipe 213 and introduced into the second adsorption tower 2012, and the liquid ammonia led out from the second adsorption tower 2012 passes through the 17th pipe 206. It flows through and is supplied to the 25th pipe 214, and liquid ammonia is introduced into the analysis means 4 and the product tank 6 from the 25th pipe 214.

  In such a sixth connection pattern, impurities contained in liquid ammonia can be adsorbed and removed by the second adsorption tower 2012 and the third adsorption tower 2013, so that the ability to adsorb and remove impurities can be improved. it can. In the sixth connection pattern, since the adsorption removal operation in the first adsorption tower 2011 is not executed, the first adsorption tower 2011 can be regenerated.

DESCRIPTION OF SYMBOLS 1 Raw material storage tank 2 Capacitor 3 Adsorption means 4 Analysis means 5 Distillation tower 6 Product tank 31,2011 1st adsorption tower 32,2012 2nd adsorption tower 33,2013 3rd adsorption tower 34 4th adsorption tower 100,200 Ammonia purification system

Claims (5)

An ammonia purification system for purifying crude ammonia,
Storage means for storing liquid crude ammonia so as to form a gas phase, leaving most of low-volatile impurities in the liquid phase, and deriving a part of the gas phase as gaseous ammonia;
Condensing means for condensing a part of the gaseous ammonia derived from the storage means and deriving liquid ammonia;
An adsorbing means for adsorbing and removing impurities contained in liquid ammonia derived from the condensing means by an adsorbent having adsorption ability for moisture and hydrocarbons alone to obtain purified liquid ammonia; An ammonia purification system comprising:   The adsorbing means is a plurality of adsorption towers for adsorbing and removing impurities contained in liquid ammonia derived from the condensing means, and has a plurality of adsorption towers connected in series. 2. The ammonia purification system according to 1.   The ammonia purification system according to claim 1 or 2, wherein the adsorbent is a porous synthetic zeolite.   The ammonia purification system according to claim 3, wherein the synthetic zeolite is MS-13X. A method for purifying crude ammonia comprising:
A storage step of storing liquid crude ammonia so as to form a gas phase, leaving most of low-volatile impurities in the liquid phase, and deriving a part of the gas phase as gaseous ammonia;
A condensation step of condensing part of the gaseous ammonia derived in the storage step and deriving liquid ammonia;
An adsorption step for obtaining and purifying purified liquid ammonia by adsorbing and removing impurities contained in the liquid ammonia derived in the condensation step by an adsorbent having adsorption ability for moisture and hydrocarbons alone. A method for purifying ammonia, comprising:

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