JP2012153545A - Ammonia purification system and ammonia purification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ammonia purification system in which moisture and a hydrocarbon included as an impurity in crude ammonia can be efficiently adsorption-removal by using the adsorptivity of an adsorbent to its maximum, and that can purify ammonia by a simplified method.SOLUTION: In the ammonia purification system 100, a control means 5 makes a first valve 611 open while closing second, third, and fourth valves 631, 641, 651, to thereby control the discharge operation of low boiling point impurities from the crude ammonia in a storage tank 1, and makes the second, third, and fourth valves 631, 641, 651 open after closing the first valve 611 to thereby control the adsorption removal operation of high boiling point impurities in an adsorption means 2 after the discharge operation.

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.

  In crude ammonia, low-order hydrocarbons such as methane, ethane, and propane, higher-order hydrocarbons having a larger number of carbon atoms, moisture, and low-boiling gases such as hydrogen, nitrogen, oxygen, argon, and carbon monoxide are included. The purity of crude ammonia, which is contained as an impurity and is generally available, is about 99.5% by weight.

  Depending on the type of process in which ammonia is used in the semiconductor manufacturing process and the liquid crystal manufacturing process, the influence of impurities in ammonia varies, but the purity of ammonia is 99.9999% by weight or more, more preferably 99.99999% by weight. That is required.

  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 high-boiling impurities from liquid crude ammonia, and an impurity (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 by a gas and a second distillation tower that removes low-boiling 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.

  In such a case, when the quantity ratio of moisture and hydrocarbons contained as impurities in the crude ammonia fluctuates, even if one adsorbent has not reached adsorption saturation, the other adsorbent has reached adsorption saturation. Reach and break 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.

  Further, in the technology for purifying ammonia disclosed in Patent Documents 1 and 2, impurities contained in the crude ammonia are adsorbed and removed by an adsorption tower, and further, the ammonia is purified by distillation by distillation using a distillation tower. The purified gaseous ammonia thus derived is condensed and recovered as liquid ammonia. That is, in the technology for purifying ammonia disclosed in Patent Documents 1 and 2, impurities contained in the crude ammonia are adsorbed and distilled off, and further condensed to obtain purified liquid ammonia. It cannot be said to be simplified.

  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 and a method for purifying ammonia that can be purified.

The present invention is an ammonia purification system for purifying crude ammonia containing impurities,
By storing liquid crude ammonia so as to form a gas phase, low boiling point impurities having a lower boiling point than ammonia contained in the crude ammonia are distributed to the gas phase, and gaseous ammonia is derived from the gas phase. Storage means to
An adsorbing means for adsorbing and removing high-boiling impurities having a boiling point higher than that of ammonia contained in gaseous ammonia derived from the storage means, using an adsorbent having an adsorption ability for moisture and hydrocarbons;
A first pipe that communicates the gas phase and the outside of the storage means and serves as a flow path for discharging low boiling point impurities distributed to the gas phase to the outside;
A second pipe that connects the storage means and the adsorption means, and serves as a flow path for gaseous ammonia derived from the storage means to flow toward the adsorption means;
First channel opening / closing means for opening or closing a channel in the first pipe;
A second channel opening / closing means for opening or closing the channel in the second pipe;
A discharge operation for discharging low-boiling-point impurities distributed to the gas phase of the storage means to the outside by controlling the opening and closing operations of the first flow path opening and closing means and the second flow path opening and closing means, Control means for controlling the adsorption removal operation of high boiling point impurities in the adsorption means,
The control means includes
With the second flow path opening / closing means closed, the first flow path opening / closing means is opened to control the discharge operation,
The ammonia purification system is characterized in that the adsorption removal operation is controlled by opening the second flow path opening / closing means after closing the first flow path opening / closing means.

  In the ammonia purification system of the present invention, the adsorption unit is a plurality of adsorption units that adsorb and remove high-boiling impurities contained in gaseous ammonia derived from the storage unit, and are connected in series or in parallel. It has a plurality of adsorption parts.

  Further, in the ammonia purification system of the present invention, the control means opens and closes the first flow path opening / closing means a plurality of times in a state where the second flow path opening / closing means is closed. Control is performed.

  Moreover, the ammonia purification system of the present invention is characterized in that the adsorbent used by the adsorption means is a porous synthetic zeolite.

  In the ammonia purification system of the present invention, the synthetic zeolite is a synthetic zeolite having a pore diameter of 5 to 9 mm.

The present invention is also a method for purifying crude ammonia containing impurities,
A storage step of distributing low-boiling impurities having a lower boiling point than ammonia contained in the crude ammonia into the gas phase by storing liquid crude ammonia so as to form a gas phase;
A discharge step of discharging low-boiling impurities distributed to the gas phase in the storage step to the outside;
A derivation step of deriving gaseous ammonia from the gas phase after discharging low boiling point impurities to the outside in the discharge step;
An adsorption step of adsorbing and removing high-boiling impurities having a boiling point higher than that of ammonia contained in the gaseous ammonia derived in the deriving step by an adsorbent having an adsorption ability for moisture and hydrocarbons alone. Is a method for purifying ammonia.

  According to the present invention, the ammonia purification system is a system for purifying crude ammonia containing impurities, and includes a storage means, an adsorption means, a first pipe, a second pipe, and a first flow path opening / closing means. The second flow path opening / closing means and the control means are included. The storage means stores liquid crude ammonia so as to form a gas phase, thereby distributing low-boiling impurities having a boiling point lower than that of ammonia contained in the crude ammonia to the gas phase. Deriving ammonia. The adsorbing means adsorbs and removes the high-boiling impurities contained in the gaseous ammonia derived from the storage means, using an adsorbent that has adsorbability for moisture and hydrocarbons alone. The first pipe communicates the gas phase of the storage means with the outside and serves as a flow path for discharging low boiling point impurities from the gas phase to the outside. The second pipe is a flow path that connects the storage means and the adsorption means and allows gaseous ammonia derived from the storage means to flow toward the adsorption means. The first channel opening / closing means opens or closes the channel in the first pipe. The second flow path opening / closing means opens or closes the flow path in the second pipe. Then, the control means opens the first flow path opening / closing means with the second flow path opening / closing means closed, thereby discharging the low boiling point impurities distributed in the gas phase of the storage means to the outside. By performing control and closing the first flow path opening / closing means and then opening the second flow path opening / closing means, the adsorption removal operation of high boiling point impurities in the adsorption means after the discharge operation is controlled.

  In the ammonia purification system of the present invention, the adsorbing means adsorbs and removes high-boiling impurities contained in gaseous ammonia by an adsorbent having adsorption ability for water and hydrocarbons alone. It is not necessary to use a plurality of adsorbents, that is, an adsorbent having an adsorbing ability for adsorbent and an adsorbent having an adsorbing ability for hydrocarbon. Therefore, high-boiling impurities contained in gaseous ammonia can be efficiently adsorbed and removed by utilizing the adsorption capacity of the adsorbent to the maximum. In the ammonia purification system of the present invention, the control means discharges and removes low-boiling impurities from the crude ammonia in the storage means by opening the first flow path opening / closing means with the second flow path opening / closing means closed. Control the discharge operation. Thereby, the low boiling point impurities in the crude ammonia distributed to the gas phase formed in the storage means can be discharged through the first pipe. The control means controls the adsorption removal operation of the high boiling point impurities in the adsorption means after the discharge operation by opening the second flow path opening / closing means after closing the first flow path opening / closing means. As a result, ammonia after the low boiling point impurities are discharged and removed during the discharging operation can be introduced to the adsorbing means via the second pipe, so that the high boiling point impurities can be removed by the adsorbing means. Therefore, ammonia can be purified with a simplified system without providing distillation means as in the prior art.

  According to the invention, the adsorbing means is a plurality of adsorbing parts for adsorbing and removing high-boiling impurities contained in gaseous ammonia derived from the storage means, and is connected in series or in parallel. Have When the adsorbing means has a plurality of adsorbing portions connected in series, it is possible to improve the adsorbing and removing ability for high-boiling impurities contained in gaseous ammonia derived from the storage means. In addition, when the adsorption means has a plurality of adsorption parts connected in parallel, gaseous ammonia derived from the storage means is introduced separately from the plurality of adsorption parts connected in parallel. Therefore, it is possible to regenerate another used adsorption unit so that the adsorption removal operation can be performed again by another used adsorption unit while the one adsorption unit performs adsorption removal. it can.

  Further, according to the present invention, the control means opens and closes the first flow path opening / closing means a plurality of times with the second flow path opening / closing means closed, so that the low boiling point impurities from the crude ammonia in the storage means can be obtained. The discharge operation for discharging and removing the water is controlled. As a result, low boiling point impurities in the crude ammonia distributed in the gas phase formed in the storage means can be more reliably discharged through the first pipe, so that the purity of the ammonia after purification can be increased. it can.

  According to the present invention, the adsorbent used by the adsorbing means is porous synthetic zeolite. As a result, moisture and hydrocarbons contained as impurities in the gaseous ammonia derived from the storage means can be efficiently adsorbed and removed.

  According to the present invention, the synthetic zeolite used as the adsorbent by the adsorbing means has a pore diameter of 5 to 9 mm. As a result, moisture and hydrocarbons (particularly higher-order hydrocarbons) contained as impurities in gaseous ammonia derived from the storage means can be efficiently adsorbed and removed.

  According to the present invention, the ammonia purification method is a method for purifying crude ammonia containing impurities, and includes a storage step, a discharge step, a derivation step, and an adsorption step. In the storage step, liquid crude ammonia is stored so as to form a gas phase, whereby low-boiling impurities having a boiling point lower than that of ammonia contained in the crude ammonia are distributed to the gas phase. In the discharging process, the low boiling point impurities distributed in the gas phase in the storing process are discharged to the outside. In the derivation step, gaseous ammonia is derived from the gas phase after the low boiling point impurities are discharged to the outside in the discharge step. In the adsorption step, high-boiling impurities having a boiling point higher than that of ammonia contained in the gaseous ammonia derived in the derivation step are adsorbed and removed by an adsorbent having an adsorption ability for moisture and hydrocarbons alone.

  In the method for purifying ammonia according to the present invention, low-boiling impurities, which are stored and distributed from the liquid crude ammonia to the gas phase, are discharged to the outside, and then the gaseous ammonia is derived from the gas phase. And since the high boiling point impurity contained in gaseous ammonia derived | led-out from the gaseous phase is adsorbed and removed, ammonia can be refine | purified by the simplified method, without passing through a distillation process like a prior art. Further, in the ammonia purification method of the present invention, in the adsorption step, high-boiling impurities contained in gaseous ammonia are adsorbed and removed by an adsorbent having adsorption ability for moisture and hydrocarbons alone. In addition, it is not necessary to use a plurality of adsorbents, that is, an adsorbent capable of adsorbing moisture and an adsorbent capable of adsorbing hydrocarbons. Therefore, high-boiling impurities contained in gaseous ammonia can be efficiently adsorbed and removed by utilizing the adsorption capacity of the adsorbent to the maximum.

It is a figure which shows the structure of the ammonia purification system 100 which concerns on 1st Embodiment of this invention. 1 is a block diagram showing a configuration of an ammonia purification system 100. FIG. 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. FIG. 2 is a block diagram showing the configuration of the ammonia purification system 100. The ammonia purification system 100 of this embodiment is a system for purifying liquid crude ammonia containing impurities. In liquid crude ammonia, low-order hydrocarbons such as methane, ethane, and propane, higher-order hydrocarbons having a higher carbon number, moisture, and low levels such as hydrogen, nitrogen, oxygen, argon, and carbon monoxide Boiling point gas is contained as an impurity. That is, in liquid crude ammonia, low-boiling impurities such as low-order hydrocarbons and low-boiling gases having a boiling point lower than that of ammonia (boiling point −33.44 ° C.), and higher-order hydrocarbons having a boiling point higher than that of ammonia. , And high boiling impurities such as moisture.

  The ammonia purification system 100 includes a storage tank 1, which is a storage means, an adsorption means 2, a capacitor 3, a recovery tank 4, and a control means 5. Further, the ammonia purification system 100 realizes the ammonia purification method according to the present invention, executes the storage process in the storage tank 1, executes the discharge process and the derivation process in the control means 5, and performs the adsorption process in the adsorption means 2. Execute.

  The storage tank 1 stores crude ammonia. In this embodiment, the crude ammonia stored in the storage tank 1 has a purity of about 99.5% by weight.

  The storage tank 1 is not particularly limited as long as it is a heat retaining container having pressure resistance and corrosion resistance. The storage tank 1 stores crude ammonia as liquid ammonia and is controlled by the operating condition control unit 5b of the control means 5 so that the temperature and pressure are constant. Specifically, the storage tank 1 is controlled to have a temperature of 10 to 50 ° C. and a pressure of 0.5 to 2.0 MPa.

  In a state where the storage tank 1 stores liquid crude ammonia, a gas phase is formed in the upper part of the storage tank 1 and a liquid phase is formed in the lower part. The storage tank 1 stores liquid crude ammonia so as to form a gas phase, thereby distributing low boiling point impurities contained in the crude ammonia to the gas phase. In this embodiment, when deriving ammonia from the storage tank 1 to the adsorbing means 2, it is derived from the gas phase as gaseous ammonia.

  The storage tank 1 is connected to a first pipe 61 provided with a first valve 611 serving as a first flow path opening / closing means, and a second pipe 62.

  The first pipe 61 communicates the gas phase of the storage tank 1 with the outside, and serves as a flow path for discharging low boiling point impurities distributed in the gas phase from the gas phase to the outside. The first valve 611 provided in the first pipe 61 opens or closes the flow path in the first pipe 61. Further, the second pipe 62 serves as a flow path through which gaseous ammonia derived from the gas phase of the storage tank 1 flows toward the adsorption means 2.

  The adsorbing means 2 adsorbs and removes high-boiling impurities contained in gaseous ammonia derived from the gas phase of the storage tank 1 using an adsorbent. In the present embodiment, the adsorption unit 2 includes a first adsorption tower 21, a second adsorption tower 22, and a third adsorption tower 23 that are a plurality of adsorption units.

  The adsorbent filled in the first adsorption tower 21, the second adsorption tower 22, and the third adsorption tower 23 has 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 21, the second adsorption tower 22, and the third adsorption tower 23 are made of a gas phase in the storage tank 1 by using an adsorbent that has adsorption ability for moisture and hydrocarbons alone. The high-boiling impurities contained in gaseous ammonia derived from are adsorbed and removed, so that, as in the prior art, a plurality of adsorbents having adsorbing ability for moisture and adsorbing agents having adsorbing ability for hydrocarbons. There is no need to use an adsorbent. Therefore, moisture and hydrocarbons contained as impurities in gaseous ammonia can be efficiently adsorbed and removed by making maximum use of the adsorption capacity of the adsorbent. Furthermore, by adsorbing and removing impurities contained in gaseous ammonia with an adsorbent having adsorption ability for moisture and hydrocarbons alone, the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23 Even when the quantity ratio of water and hydrocarbons contained in the supplied ammonia varies, the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 3 are based on the analysis result by the analysis means 53 described later. The breakthrough of the adsorption tower 23 can be easily managed.

  Further, 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, so that gaseous ammonia derived from the gas phase of the storage tank 1 is used as an impurity. The contained moisture and hydrocarbons (particularly higher-order hydrocarbons) can be efficiently adsorbed and removed.

  In the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23, an adsorbent having an adsorption ability for moisture and hydrocarbons alone and other adsorbents can be used in combination. 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.

  In the ammonia purification system 100 of the present embodiment, the temperature of the first adsorption tower 21, the second adsorption tower 22, and the third adsorption tower 23 is controlled to 0 to 60 ° C. by the operating condition control unit 5b of the control means 5, The pressure is controlled to 0.1 to 1.0 MPa. When the temperature of the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23 is less than 0 ° C., cooling is required to remove adsorption heat generated during the adsorption removal of impurities, resulting in a decrease in energy efficiency. There is a risk. When the temperature of the 1st adsorption tower 21, the 2nd adsorption tower 22, and the 3rd adsorption tower 23 exceeds 60 degreeC, there exists a possibility that the adsorption capacity of the impurity by adsorption agent may fall. Moreover, when the pressure of the 1st adsorption tower 21, the 2nd adsorption tower 22, and the 3rd adsorption tower 23 is less than 0.1 Mpa, there exists a possibility that the adsorption capacity of the impurity by an adsorbent may fall. When the pressure in the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23 exceeds 1.0 MPa, a large amount of energy is required to maintain a constant pressure, which may reduce the energy efficiency. is there.

  The linear velocities (linear velocities) in the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23 are the amounts of gaseous ammonia supplied to the adsorption towers 21, 22 and 23 per unit time. Is converted to a gas volume in NTP, and the range of values obtained by dividing by the empty cross-sectional area of each adsorption tower 21, 22, 23 is preferably 0.1 to 5.0 m / sec. If the linear velocity is less than 0.1 m / sec, it takes a long time to adsorb and remove the impurities, which is not preferable. If the linear velocity exceeds 5.0 m / sec, the heat of adsorption generated during the adsorption removal of the impurities. In this case, the adsorption capacity of the impurities by the adsorbent may be lowered.

  In the present embodiment, the second piping 62 through which gaseous ammonia derived from the gas phase of the storage tank 1 flows passes through the third piping 63, the fourth piping 64, and the second piping branching from the second piping 62. Five pipes 65 are connected.

  The third pipe 63 branches from the second pipe 62 and is connected to the top of the first adsorption tower 21. The third pipe 63 is provided with a second valve 631 that opens or closes the flow path in the third pipe 63. The fourth pipe 64 branches from the second pipe 62 and is connected to the top of the second adsorption tower 22. The fourth pipe 64 is provided with a third valve 641 that opens or closes the flow path in the fourth pipe 64. The fifth pipe 65 branches from the second pipe 62 and is connected to the top of the third adsorption tower 23. The fifth pipe 65 is provided with a fourth valve 651 that opens or closes the flow path in the fifth pipe 65. In the present embodiment, the second flow path opening / closing means is realized by the second valve 631, the third valve 641, and the fourth valve 651.

  A sixth pipe 66 through which gaseous ammonia derived from the first adsorption tower 21 flows is connected to the bottom of the first adsorption tower 21. The sixth pipe 66 is provided with a fifth valve 661 that opens or closes the flow path in the sixth pipe 66. A seventh pipe 67 through which gaseous ammonia derived from the second adsorption tower 22 flows is connected to the bottom of the second adsorption tower 22. The seventh pipe 67 is provided with a sixth valve 671 that opens or closes the flow path in the seventh pipe 67. An eighth pipe 68 through which gaseous ammonia derived from the third adsorption tower 23 flows is connected to the bottom of the third adsorption tower 23. The eighth pipe 68 is provided with a seventh valve 681 that opens or closes the flow path in the eighth pipe 68.

  In addition, a ninth pipe 69 that branches from the sixth pipe 66 is connected to the sixth pipe 66. The ninth pipe 69 is branched from the sixth pipe 66 and connected to the fourth pipe 64, and a flow path for introducing gaseous ammonia led out from the first adsorption tower 21 into the second adsorption tower 22. It becomes. The ninth pipe 69 is provided with an eighth valve 691 that opens or closes the flow path in the ninth pipe 69. A tenth pipe 70 that branches from the ninth pipe 69 is connected to the ninth pipe 69. The tenth pipe 70 is branched from the ninth pipe 69 and connected to the fifth pipe 65, and a flow path for introducing gaseous ammonia led out from the first adsorption tower 21 into the third adsorption tower 23. It becomes. The tenth pipe 70 is provided with a ninth valve 701 that opens or closes the flow path in the tenth pipe 70.

  In addition, an eleventh pipe 71 and a twelfth pipe 72 branched from the seventh pipe 67 are connected to the seventh pipe 67. The eleventh pipe 71 is branched from the seventh pipe 67 and connected to the third pipe 63, and a flow path for introducing gaseous ammonia derived from the second adsorption tower 22 into the first adsorption tower 21. Become. The eleventh pipe 71 is provided with a tenth valve 711 that opens or closes the flow path in the eleventh pipe 71. The twelfth pipe 72 branches from the seventh pipe 67 and is connected to the fifth pipe 65, and a flow path for introducing gaseous ammonia derived from the second adsorption tower 22 into the third adsorption tower 23. Become. The twelfth pipe 72 is provided with an eleventh valve 721 that opens or closes the flow path in the twelfth pipe 72.

  The eighth pipe 68 is connected to a thirteenth pipe 73 branched from the eighth pipe 68. The thirteenth pipe 73 is branched from the eighth pipe 68 and connected to the third pipe 63, and a flow path for introducing gaseous ammonia derived from the third adsorption tower 23 into the first adsorption tower 21. It becomes. The thirteenth pipe 73 is provided with a twelfth valve 731 that opens or closes the flow path in the thirteenth pipe 73. A fourteenth pipe 74 branched from the thirteenth pipe 73 is connected to the thirteenth pipe 73. The fourteenth pipe 74 is branched from the thirteenth pipe 73 and connected to the fourth pipe 64, and a flow path for introducing gaseous ammonia derived from the third adsorption tower 23 into the second adsorption tower 22. It becomes. The fourteenth pipe 74 is provided with a thirteenth valve 741 that opens or closes the flow path in the fourteenth pipe 74.

  In the sixth pipe 66, the seventh pipe 67, and the eighth pipe 68, a fifteenth pipe 75 is connected to the downstream end portion in the flowing direction of gaseous ammonia. The 15th pipe 75 is supplied with gaseous ammonia derived from any one of the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23. The fifteenth pipe 75 is provided with a sixteenth pipe 76 that branches from the fifteenth pipe 75 and is connected to a seventeenth pipe 77 that is connected to the condenser 3 and the recovery capacitor 51 described later. .

  Here, control of the opening / closing operation of each valve by the control means 5 in the ammonia purification system 100 of the present embodiment will be described. In this embodiment, the control means 5 controls the opening / closing operation | movement of each valve by the flow-path opening / closing control part 5a.

  The flow path opening / closing controller 5a of the control means 5 includes a first valve 611, a second valve 631, a third valve 641, a fourth valve 651, a fifth valve 661, a sixth valve 671, a seventh valve 681, and an eighth valve. The low boiling point distributed to the gas phase of the storage tank 1 by controlling the opening / closing operation of the valve 691, the ninth valve 701, the tenth valve 711, the eleventh valve 721, the twelfth valve 731 and the thirteenth valve 741. The discharging operation for discharging impurities to the outside and the adsorption removing operation for high boiling point impurities in the adsorption means 2 are controlled.

  The flow path opening / closing control unit 5a of the control means 5 opens the first valve 611 with the second valve 631, the third valve 641 and the fourth valve 651 closed, so that crude ammonia in the storage tank 1 is removed. Controls the discharge operation to discharge and remove low boiling point impurities. Specifically, after the liquid crude ammonia is stored in the storage tank 1 for 0.5 to 3 days, the first valve 611 is closed with the second valve 631, the third valve 641, and the fourth valve 651 closed. For 10 to 300 minutes. Please fill in the blank. Thereby, low boiling point impurities in the crude ammonia distributed in the gas phase formed in the storage tank 1 can be discharged through the first pipe 61.

  In addition, the flow path opening / closing control unit 5a of the control means 5 opens and closes the first valve 611 multiple times in a state where the second valve 631, the third valve 641 and the fourth valve 651 are closed. It is preferable to control the discharge operation for discharging and removing low boiling point impurities from the crude ammonia in the storage tank 1. For example, when the first valve 611 is opened and closed five times, after the liquid crude ammonia is stored in the storage tank 1 for 0.5 to 3 days, the second valve 631, the third valve 641 and the fourth valve With the valve 651 closed, the first valve 611 is opened for 10 to 120 minutes, and then the first valve 611 is closed and left for 60 to 300 minutes. The operation of opening the first valve 611 for 10 to 120 minutes and then closing the first valve 611 and allowing it to stand for 60 to 300 minutes may be repeated five times in total. Please fill in the blank. As a result, low boiling point impurities in the crude ammonia distributed in the gas phase formed in the storage tank 1 can be more reliably discharged through the first pipe 61, so that the purity of ammonia after purification is increased. be able to.

  Further, the flow path opening / closing control unit 5a of the control means 5 closes the first valve 611, and then opens any of the second valve 631, the third valve 641, and the fourth valve 651, thereby performing the post-discharge operation. The adsorption removal operation of high boiling point impurities in the adsorption means 2 is controlled. Thereby, gaseous ammonia derived from the gas phase of the storage tank 1 after the low boiling point impurities are discharged during the discharging operation is supplied to the first adsorption tower 21 and the second adsorption tower 22 via the second pipe 62. Since it can be introduced into any of the third adsorption towers 23, high-boiling impurities can be removed. Therefore, ammonia can be purified with a simplified system without providing distillation means as in the prior art.

  In the present embodiment, the adsorption removal operation in the adsorption unit 2 by the flow path opening / closing control unit 5a of the control unit 5 has the following six control patterns.

  The first control pattern is a control pattern in which gaseous ammonia derived from the gas phase of the storage tank 1 after the low boiling point impurities are discharged is passed through the first adsorption tower 21 and the second adsorption tower 22 in this order. is there. In the first control pattern, the flow path opening / closing controller 5a opens the second valve 631, the sixth valve 671, and the eighth valve 691 in a state where the first valve 611 is closed, and the third valve 641, The fourth valve 651, the fifth valve 661, the seventh valve 681, the ninth valve 701, the tenth valve 711, the eleventh valve 721, the twelfth valve 731 and the thirteenth valve 741 are closed. Thereby, gaseous ammonia derived from the gas phase of the storage tank 1 and flowing through the second pipe 62 flows through the third pipe 63 and is introduced into the first adsorption tower 21, and the first adsorption tower 21. The gaseous ammonia derived from the refrigerant is introduced into the second adsorption tower 22 through the sixth pipe 66 and the ninth pipe 69, and the gaseous ammonia derived from the second adsorption tower 22 is the seventh The pipe 67 is passed through and supplied to the fifteenth pipe 75, and from the fifteenth pipe 75 to the sixteenth pipe 76 connected to the condenser 3 and the analysis recovery capacitor 51, the sixteenth pipe 76 is connected in a gaseous state. Of ammonia is supplied. In such a first control pattern, the high boiling point impurities contained in the gaseous ammonia can be adsorbed and removed by the first adsorption tower 21 and the second adsorption tower 22, so that the adsorption removal capability for the high boiling point impurities is increased. Can be improved. In the first control pattern, since the adsorption removal operation in the third adsorption tower 23 is not executed, the third adsorption tower 23 can be regenerated.

  The second control pattern is a control pattern in which gaseous ammonia derived from the gas phase of the storage tank 1 after the low boiling point impurities are discharged is passed through the first adsorption tower 21 and the third adsorption tower 23 in this order. is there. In the second control pattern, the flow path opening / closing control unit 5a opens the second valve 631, the seventh valve 781, and the ninth valve 701 in a state where the first valve 611 is closed, and the third valve 641, The fourth valve 651, the fifth valve 661, the sixth valve 671, the eighth valve 691, the tenth valve 711, the eleventh valve 721, the twelfth valve 731 and the thirteenth valve 741 are closed. Thereby, gaseous ammonia derived from the gas phase of the storage tank 1 and flowing through the second pipe 62 flows through the third pipe 63 and is introduced into the first adsorption tower 21, and the first adsorption tower 21. The gaseous ammonia derived from the gas flows through the sixth piping 66, the ninth piping 69, and the tenth piping 70, is introduced into the third adsorption tower 23, and is gaseous from the third adsorption tower 23. Ammonia flows through the eighth pipe 68 and is supplied to the fifteenth pipe 75, and the sixteenth pipe connected from the fifteenth pipe 75 to the seventeenth pipe 77 connected to the capacitor 3 and the analysis recovery capacitor 51. 76 is supplied with gaseous ammonia. In such a second control pattern, the high boiling impurities contained in gaseous ammonia can be adsorbed and removed by the first adsorption tower 21 and the third adsorption tower 23, so that the adsorption removal ability for the high boiling impurities is increased. Can be improved. In the second control pattern, the adsorption removal operation in the second adsorption tower 22 is not executed, so that the second adsorption tower 22 can be regenerated.

  The third control pattern is a control pattern in which gaseous ammonia derived from the gas phase of the storage tank 1 after the low boiling point impurities are discharged is passed through the second adsorption tower 22 and the first adsorption tower 21 in this order. is there. In the third control pattern, the flow path opening / closing control unit 5a opens the third valve 641, the fifth valve 661, and the tenth valve 711 with the first valve 611 closed, and the second valve 631, The fourth valve 651, the sixth valve 671, the seventh valve 681, the eighth valve 691, the ninth valve 701, the eleventh valve 721, the twelfth valve 731 and the thirteenth valve 741 are closed. As a result, gaseous ammonia derived from the gas phase of the storage tank 1 and flowing through the second pipe 62 flows through the fourth pipe 64 and is introduced into the second adsorption tower 22, and the second adsorption tower 22. The gaseous ammonia derived from the refrigerant is introduced into the first adsorption tower 21 through the seventh pipe 67 and the eleventh pipe 71, and the gaseous ammonia derived from the first adsorption tower 21 is the sixth The pipe 66 flows and is supplied to the fifteenth pipe 75, and from the fifteenth pipe 75 to the sixteenth pipe 76 connected to the capacitor 3 and the analyzing recovery capacitor 51, the sixteenth pipe 76 is connected in a gaseous state. Of ammonia is supplied. In such a third control pattern, the high boiling point impurities contained in the gaseous ammonia can be adsorbed and removed by the first adsorption tower 21 and the second adsorption tower 22, so that the adsorption removal capability for the high boiling point impurities is increased. Can be improved. In the third control pattern, the adsorption removal operation in the third adsorption tower 23 is not executed, so that the third adsorption tower 23 can be regenerated.

  The fourth control pattern is a connection pattern in which gaseous ammonia derived from the gas phase of the storage tank 1 after the low boiling point impurities are discharged passes through the second adsorption tower 22 and the third adsorption tower 23 in this order. is there. In the fourth control pattern, the flow path opening / closing controller 5a opens the third valve 641, the seventh valve 681, and the eleventh valve 721 with the first valve 611 closed, and the second valve 631, The fourth valve 651, the fifth valve 661, the sixth valve 671, the eighth valve 691, the ninth valve 701, the tenth valve 711, the twelfth valve 731 and the thirteenth valve 741 are closed. As a result, gaseous ammonia derived from the gas phase of the storage tank 1 and flowing through the second pipe 62 flows through the fourth pipe 64 and is introduced into the second adsorption tower 22, and the second adsorption tower 22. The gaseous ammonia derived from the refrigerant is introduced into the third adsorption tower 23 through the seventh pipe 67 and the twelfth pipe 72, and the gaseous ammonia derived from the third adsorption tower 23 is the eighth The pipe 68 is passed through and supplied to the fifteenth pipe 75, and from the fifteenth pipe 75 to the sixteenth pipe 76 connected to the capacitor 3 and the analysis recovery capacitor 51, the sixteenth pipe 76 is connected in a gaseous state. Of ammonia is supplied. In such a fourth control pattern, the high boiling point impurities contained in the gaseous ammonia can be adsorbed and removed by the second adsorption tower 22 and the third adsorption tower 23, so that the adsorption removal capability for the high boiling point impurities is increased. Can be improved. In the fourth control pattern, the adsorption removal operation in the first adsorption tower 21 is not executed, so that the first adsorption tower 21 can be regenerated.

  The fifth control pattern is a connection pattern in which gaseous ammonia derived from the gas phase of the storage tank 1 after the low boiling point impurities are discharged passes through the third adsorption tower 23 and the first adsorption tower 21 in this order. is there. In the fifth control pattern, the flow path opening / closing control unit 5a opens the fourth valve 651, the fifth valve 661, and the twelfth valve 731 with the first valve 611 closed, and opens the second valve 631, the second valve 631, and the second valve 631. The third valve 641, the sixth valve 671, the seventh valve 681, the eighth valve 691, the ninth valve 701, the tenth valve 711, the eleventh valve 721, and the thirteenth valve 741 are closed. Thus, gaseous ammonia derived from the gas phase of the storage tank 1 and flowing through the second pipe 62 flows through the fifth pipe 65 and is introduced into the third adsorption tower 23, and the third adsorption tower 23. The gaseous ammonia derived from the refrigerant is introduced into the first adsorption tower 21 through the eighth pipe 68 and the thirteenth pipe 73, and the gaseous ammonia derived from the first adsorption tower 21 is the sixth The pipe 66 flows and is supplied to the fifteenth pipe 75, and from the fifteenth pipe 75 to the sixteenth pipe 76 connected to the capacitor 3 and the analyzing recovery capacitor 51, the sixteenth pipe 76 is connected in a gaseous state. Of ammonia is supplied. In such a fifth control pattern, the high boiling point impurities contained in the gaseous ammonia can be adsorbed and removed by the first adsorption tower 21 and the third adsorption tower 23, so that the adsorption removal capability for the high boiling point impurities is increased. Can be improved. In the fifth control pattern, since the adsorption removal operation in the second adsorption tower 22 is not executed, the second adsorption tower 22 can be regenerated.

  The sixth control pattern is a control pattern in which gaseous ammonia derived from the gas phase of the storage tank 1 after the low boiling point impurities are discharged is passed through the third adsorption tower 23 and the second adsorption tower 22 in this order. is there. In the sixth control pattern, the flow path opening / closing control unit 5a opens the fourth valve 651, the sixth valve 671, and the thirteenth valve 741, with the first valve 611 closed, and the second valve 631, The third valve 641, the fifth valve 661, the seventh valve 681, the eighth valve 691, the ninth valve 701, the tenth valve 711, the eleventh valve 721, and the twelfth valve 731 are closed. Thus, gaseous ammonia derived from the gas phase of the storage tank 1 and flowing through the second pipe 62 flows through the fifth pipe 65 and is introduced into the third adsorption tower 23, and the third adsorption tower 23. The gaseous ammonia derived from the refrigerant is introduced into the second adsorption tower 22 through the eighth pipe 68, the thirteenth pipe 73, and the fourteenth pipe 74, and the gaseous ammonia derived from the second adsorption tower 22 is introduced. Ammonia flows through the seventh pipe 67 and is supplied to the fifteenth pipe 75, and the sixteenth pipe connected from the fifteenth pipe 75 to the seventeenth pipe 77 connected to the capacitor 3 and the analysis recovery capacitor 51. 76 is supplied with gaseous ammonia. In such a sixth control pattern, the high boiling point impurities contained in the gaseous ammonia can be adsorbed and removed by the second adsorption tower 22 and the third adsorption tower 23, so that the adsorption removal capability for the high boiling point impurities is increased. Can be improved. In the sixth control pattern, the adsorption removal operation in the first adsorption tower 21 is not executed, so that the first adsorption tower 21 can be regenerated.

  Gaseous ammonia derived from the first adsorption tower 21, the second adsorption tower 22 or the third adsorption tower 23 and supplied to the sixteenth pipe 76 is introduced into the seventeenth pipe 77.

  The seventeenth pipe 77 has one end connected to the storage tank 1 via the analysis-time recovery capacitor 51 and the other end connected to the capacitor 3 via the filter 52. The seventeenth pipe 77 is provided with a fourteenth valve 771 on the capacitor 3 side relative to the connection with the sixteenth pipe 76, and a fifteenth valve 772 on the analysis recovery capacitor 51 side. Further, a nineteenth pipe 79 branched from the seventeenth pipe 77 is connected to the seventeenth pipe 77 between the fourteenth valve 771 and the fifteenth valve 772. The nineteenth pipe 79 is provided with a sixteenth valve 791 to which the analysis means 53 is connected.

The analysis unit 53 analyzes the concentration of impurities contained in gaseous ammonia derived from the adsorption unit 2. In the present embodiment, the analysis unit 53 includes a cavity ring-down spectroscopic analyzer (CRDS) 531 and a gas chromatograph analyzer (GC-PDD: pulse discharge type detector) 532. Examples of the cavity ring-down spectroscopic analyzer 531 include MTO-LP-H ₂ O (manufactured by Tiger Optics). Examples of the gas chromatograph analyzer 532 include GC-4000 (manufactured by GL Sciences, Inc.). ). In the ammonia purification system 100 of the present embodiment, breakthrough management of the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23 of the adsorption means 2 is performed based on the analysis result of the analysis means 53.

  The flow path opening / closing control unit 5a of the control means 5 opens the 15th valve 772 and the 16th valve 791 with the 14th valve 771 closed during the analysis by the analysis means 53. As a result, gaseous ammonia led out from the adsorption means 2 flows through the nineteenth pipe 79 and is introduced into the analysis means 53. In addition, gaseous ammonia derived from the adsorption means 2 until the analysis by the analysis means 53 is completed flows through the seventeenth pipe 77 and is introduced into the analysis recovery capacitor 51 to be condensed and stored. Returned to tank 1. The operating conditions of the analyzing recovery capacitor 51 and the analyzing means 53 are controlled by the operating condition control unit 5 b of the control means 5.

  Further, the flow path opening / closing control unit 5a of the control means 5 finishes the analysis by the analysis means 53, and the analysis result indicates that the first adsorption tower 21, the second adsorption tower 22 and the third adsorption tower 23 of the adsorption means 2 are the same. If the result indicates that the breakthrough has not occurred, the fourteenth valve 771 is opened while the fifteenth valve 772 and the sixteenth valve 791 are closed. As a result, gaseous ammonia derived from the adsorbing means 2 flows through the seventeenth pipe 77 and is introduced into the capacitor 3 through the filter 52.

  The filter 52 removes heavy metals contained in gaseous ammonia led out from the adsorption means 2. In the present embodiment, the filter 52 has a two-layer structure in which a 5 μm filter made of polypropylene (PP) and a 0.01 μm filter made of polytetrafluoroethylene (PTFE) / PP are connected in series. In FIG. 1, the configuration in which one filter 52 is provided in the seventeenth pipe 77 is not limited to this configuration, and a plurality of filters 52 are connected to the seventeenth pipe 77 in parallel. Also good. For example, when the two filters 52 are configured to be connected in parallel to the seventeenth pipe 77, the heavy metal contained in the gaseous ammonia derived from the adsorption means 2 is filtered and removed by the one filter 52. In addition, it is possible to replace another used filter 52.

  Gaseous ammonia that has passed through the seventeenth pipe 77 and passed through the filter 52 is introduced into the capacitor 3.

  The condenser 3 discharges and removes low-boiling impurities in the storage tank 1, adsorbs and removes high-boiling impurities in the adsorbing means 2, and condenses the purified gaseous ammonia that has been filtered and removed by the filter 52 into a liquid. Recover as ammonia. The liquid ammonia condensed and recovered by the condenser 3 is introduced into the recovery tank 4 via the 18th pipe 78 and stored in the recovery tank 4. Operating conditions such as temperature in the capacitor 3 and the recovery tank 4 are controlled by an operating condition control unit 5 b of the control means 5.

  FIG. 3 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 2 described above.

  The adsorbing means 201 provided in the ammonia purification system 200 adsorbs and removes high-boiling impurities contained in gaseous ammonia derived from the gas phase of the storage tank 1 using an adsorbent. In the present embodiment, the adsorption means 201 includes a first adsorption tower 2011, a second adsorption tower 2012, a third adsorption tower 2013, and a fourth adsorption tower 2014 that are a plurality of adsorption sections.

  The first adsorption tower 2011, the second adsorption tower 2012, the third adsorption tower 2013, and the fourth adsorption tower 2014 are configured in the same manner as the first adsorption tower 21 described above. Specifically, the first adsorption tower 2011, the second adsorption tower 2012, the third adsorption tower 2013, and the fourth adsorption tower 2014 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 temperature of the first adsorption tower 2011, the second adsorption tower 2012, the third adsorption tower 2013, and the fourth adsorption tower 2014 is controlled by the operating condition control unit 5b of the control means 5. The pressure is controlled to 0 to 60 ° C., and the pressure is controlled to 0.1 to 1.0 MPa. When the temperatures of the first adsorption tower 2011, the second adsorption tower 2012, the third adsorption tower 2013, and the fourth adsorption tower 2014 are less than 0 ° C., cooling is necessary to remove the heat of adsorption generated during the adsorption removal of impurities. Thus, the energy efficiency may be reduced. When the temperatures of the first adsorption tower 2011, the second adsorption tower 2012, the third adsorption tower 2013, and the fourth adsorption tower 2014 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, the 3rd adsorption tower 2013, and the 4th adsorption tower 2014 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, the third adsorption tower 2013, and the fourth adsorption tower 2014 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 2011, the second adsorption tower 2012, the third adsorption tower 2013, and the fourth adsorption tower 2014 are as follows: gaseous ammonia per unit time, and each adsorption tower 2011, 2012. , 2013, 2014 are converted into gas volumes in NTP, and the range of values obtained by dividing by the empty cross-sectional area of each adsorption tower 2011, 2012, 2013, 2014 is 0.1-5. It is preferably 0 m / sec. If the linear velocity is less than 0.1 m / sec, it takes a long time to adsorb and remove the impurities, which is not preferable. If the linear velocity exceeds 5.0 m / sec, the heat of adsorption generated during the adsorption removal of the impurities. In this case, the adsorption capacity of the impurities by the adsorbent may be lowered.

  In this embodiment, the 20th pipe 202 and the 21st pipe 203 branched from the second pipe 62 are connected to the second pipe 62 through which gaseous ammonia derived from the gas phase of the storage tank 1 flows. Is done.

  The twentieth pipe 202 branches from the second pipe 62 and is connected to the top of the first adsorption tower 2011. The twentieth pipe 202 is provided with a seventeenth valve 2021 that opens or closes the flow path in the twentieth pipe 202. The 21st pipe 203 branches from the second pipe 62 and is connected to the tower top of the third adsorption tower 2013. The twenty-first pipe 203 is provided with an eighteenth valve 2031 that opens or closes the flow path in the twenty-first pipe 203. That is, in the present embodiment, the first adsorption tower 2011 and the third adsorption tower 2013 are connected in parallel to the second pipe 62.

  When supplying gaseous ammonia derived from the gas phase of the storage tank 1 to the first adsorption tower 2011, the flow path opening / closing control unit 5a of the control means 5 opens the 17th valve 2021, and opens the 18th valve 2031. Close. As a result, gaseous ammonia flows through the twentieth pipe 202 from the storage tank 1 toward the first adsorption tower 2011. Further, when supplying gaseous ammonia derived from the gas phase of the storage tank 1 to the third adsorption tower 2013, the flow path opening / closing controller 5a of the control means 5 opens the 18th valve 2031 and the 17th valve. 2021 is closed. As a result, gaseous ammonia flows through the 21st pipe 203 from the storage tank 1 toward the third adsorption tower 2013.

  Thus, the adsorption means 201 has the first adsorption tower 2011 and the third adsorption tower 2013 connected in parallel, so that gaseous ammonia derived from the gas phase of the storage tank 1 is connected in parallel. Since the first adsorption tower 2011 and the third adsorption tower 2013 can be introduced separately from each other, for example, while the first adsorption tower 2011 is performing adsorption adsorption, the used third adsorption tower 2013 is used. Thus, the used third adsorption tower 2013 can be regenerated so that the adsorption removal operation can be performed again.

  The second adsorption tower 2012 is connected in series with the first adsorption tower 2011 via the 22nd pipe 204. That is, in the 22nd piping 204, one end is connected to the tower bottom of the first adsorption tower 2011, and the other end is connected to the tower top of the second adsorption tower 2012. Thereby, gaseous ammonia derived from the gas phase of the storage tank 1 and introduced into the first adsorption tower 2011 flows through the 22nd pipe 204 and is introduced into the second adsorption tower 2012. As described above, the adsorption means 201 includes the first adsorption tower 2011 and the second adsorption tower 2012 connected in series, so that high-boiling impurities contained in gaseous ammonia derived from the gas phase of the storage tank 1 can be reduced. Since the adsorption removal can be performed by the first adsorption tower 2011 and the second adsorption tower 2012, the adsorption removal ability for high boiling impurities can be improved.

  Gaseous ammonia derived from the second adsorption tower 2012 flows through the 24th pipe 206 and is supplied to the 26th pipe 208 connected to the 16th pipe 76. The twenty-fourth pipe 206 is provided with a nineteenth valve 2061 that opens or closes the flow path in the twenty-fourth pipe 206. At the time of supplying gaseous ammonia derived from the second adsorption tower 2012 to the 26th pipe 208, the 19th valve 2061 is opened, and the inside of the 24th pipe 206 is directed from the second adsorption tower 2012 to the 26th pipe 208. Gaseous ammonia flows through.

  The fourth adsorption tower 2014 is connected in series with the third adsorption tower 2013 via the 23rd pipe 205. That is, in the 23rd pipe 205, one end is connected to the tower bottom of the third adsorption tower 2013 and the other end is connected to the tower top of the fourth adsorption tower 2014. Thereby, gaseous ammonia derived from the gas phase of the storage tank 1 and introduced into the third adsorption tower 2013 flows through the 23rd pipe 205 and is introduced into the fourth adsorption tower 2014. As described above, the adsorbing means 201 includes the third adsorption tower 2013 and the fourth adsorption tower 2014 connected in series, so that high-boiling impurities contained in gaseous ammonia derived from the gas phase of the storage tank 1 can be reduced. In addition, since adsorption and removal can be performed by the third adsorption tower 2013 and the fourth adsorption tower 2014, the ability to adsorb and remove high-boiling impurities can be improved.

  Gaseous ammonia led out from the fourth adsorption tower 2014 flows through the 25th pipe 207 and is supplied to the 26th pipe 208 connected to the 16th pipe 76. The twenty-fifth pipe 207 is provided with a twentieth valve 2071 for opening or closing the flow path in the twenty-fifth pipe 207. When supplying gaseous ammonia derived from the fourth adsorption tower 2014 to the twenty-sixth pipe 208, the twentieth valve 2071 is opened, and the inside of the twenty-fifth pipe 207 is directed from the fourth adsorption tower 2014 toward the twenty-sixth pipe 208. Gaseous ammonia flows through.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to such examples.

<Rough ammonia>
As the crude ammonia stored in the storage tank, liquid crude ammonia having the impurity concentration shown in Table 1 was used. As for the impurity concentration, the hydrocarbon concentration, hydrogen, oxygen, and carbon monoxide concentration are analyzed by a gas chromatograph analyzer (GC-4000, manufactured by GL Sciences Inc.), and the moisture concentration is determined by cavity ring-down spectroscopy. Analysis was performed with an analyzer (MTO-LP-H ₂ O, manufactured by Tiger Optics).

Example 1
Crude ammonia was purified using the ammonia purification system 100 shown in FIG. First, in a state where the second valve 631, the third valve 641 and the fourth valve 651 are closed, the first valve 611 is opened and closed five times, so that low boiling point impurities are removed from the gas phase of the storage tank 1. It was discharged. Next, a cylindrical tubular first adsorption tower (packed with synthetic zeolite MS-13X having an adsorption ability for moisture and hydrocarbons alone using gaseous ammonia derived from the gas phase of the storage tank 1 as an adsorbent ( 50 cm in length and 2 cm in inner diameter) were passed under conditions of a temperature of 25 ° C., a pressure of 0.4 MPa, and a linear velocity of 1.7 Nm / s. Thus, impurity concentration was analyzed about gaseous ammonia after passing the 1st adsorption tower. The analysis results are shown in Table 2.

(Example 2)
The same procedure as in Example 1 was conducted except that gaseous ammonia derived from the gas phase of the storage tank 1 was passed through the first adsorption tower and the second adsorption tower connected in series. The impurity concentration of the gaseous ammonia after passing through the adsorption tower was analyzed. The analysis results are shown in Table 2.

(Comparative Example 1)
Except that the first valve 611 is not opened and closed and the first valve 611 is maintained in a closed state, the gaseous ammonia after passing through the first adsorption tower is treated as an impurity in the same manner as in Example 1. The concentration was analyzed. The analysis results are shown in Table 2.

(Comparative Example 2)
The gaseous state after passing through the first adsorption tower and the second adsorption tower in the same manner as in Example 2 except that the first valve 611 is not opened and closed and the first valve 611 is kept closed. The impurity concentration was analyzed for ammonia. The analysis results are shown in Table 2.

  As apparent from the results in Table 2, in the ammonia purification methods of Examples 1 and 2 in which the adsorption removal operation by the adsorption tower was performed after the opening and closing operation of the first valve 611 in the storage tank 1, the methane, ethane The concentration of low-boiling impurities such as propane, hydrogen, oxygen and carbon monoxide and high-boiling impurities such as moisture, butane, pentane and hexane is reduced. In the ammonia purification methods of Examples 1 and 2, low-boiling impurities can be discharged from the gas phase of the storage tank 1 by opening and closing the first valve 611, and high-boiling impurities can be removed by an adsorption tower. This is because adsorption removal was possible.

  In contrast, in the ammonia purification methods of Comparative Examples 1 and 2, although the concentration of high-boiling impurities such as moisture, butane, pentane, and hexane was reduced, methane, ethane, propane, hydrogen, oxygen, monoxide The concentration of low-boiling impurities such as carbon is not sufficiently reduced. This is because, in the ammonia purification methods of Comparative Examples 1 and 2, the first valve 611 was not opened and closed, and thus low boiling point impurities could not be discharged and removed from the gas phase of the storage tank 1.

DESCRIPTION OF SYMBOLS 1 Storage tank 2,201 Adsorption means 3 Condenser 4 Recovery tank 21,2011 1st adsorption tower 22,2012 2nd adsorption tower 23,2013 3rd adsorption tower 51 Capacitor for collection | recovery at the time of analysis 52 Filter 53 Analyzing means 61 1st piping 62 2nd piping 100,200 Ammonia purification system 611 1st valve 631 2nd valve 641 3rd valve 651 4th valve 2014 4th adsorption tower

Claims (6)

An ammonia purification system for purifying crude ammonia containing impurities,
By storing liquid crude ammonia so as to form a gas phase, low boiling point impurities having a lower boiling point than ammonia contained in the crude ammonia are distributed to the gas phase, and gaseous ammonia is derived from the gas phase. Storage means to
An adsorbing means for adsorbing and removing high-boiling impurities having a boiling point higher than that of ammonia contained in gaseous ammonia derived from the storage means, using an adsorbent having an adsorption ability for moisture and hydrocarbons;
A first pipe that communicates the gas phase and the outside of the storage means and serves as a flow path for discharging low boiling point impurities distributed to the gas phase to the outside;
A second pipe that connects the storage means and the adsorption means, and serves as a flow path for gaseous ammonia derived from the storage means to flow toward the adsorption means;
First channel opening / closing means for opening or closing a channel in the first pipe;
A second channel opening / closing means for opening or closing the channel in the second pipe;
A discharge operation for discharging low-boiling-point impurities distributed to the gas phase of the storage means to the outside by controlling the opening and closing operations of the first flow path opening and closing means and the second flow path opening and closing means, Control means for controlling the adsorption removal operation of high boiling point impurities in the adsorption means,
The control means includes
With the second flow path opening / closing means closed, the first flow path opening / closing means is opened to control the discharge operation,
An ammonia purification system, wherein the adsorption removal operation is controlled by opening the second flow path opening / closing means after closing the first flow path opening / closing means.   The adsorbing means is a plurality of adsorbing parts for adsorbing and removing high boiling point impurities contained in gaseous ammonia derived from the storage means, and has a plurality of adsorbing parts connected in series or in parallel. The ammonia purification system according to claim 1.   The control means controls the discharge operation by opening and closing the first flow path opening / closing means a plurality of times with the second flow path opening / closing means closed. Item 3. The ammonia purification system according to Item 1 or 2.   The ammonia purification system according to any one of claims 1 to 3, wherein the adsorbent used by the adsorption means is a porous synthetic zeolite.   The ammonia purification system according to claim 4, wherein the synthetic zeolite is a synthetic zeolite having a pore diameter of 5 to 9 mm. A method for purifying crude ammonia containing impurities,
A storage step of distributing low-boiling impurities having a lower boiling point than ammonia contained in the crude ammonia into the gas phase by storing liquid crude ammonia so as to form a gas phase;
A discharge step of discharging low-boiling impurities distributed to the gas phase in the storage step to the outside;
A derivation step of deriving gaseous ammonia from the gas phase after discharging low boiling point impurities to the outside in the discharge step;
An adsorption step of adsorbing and removing a high-boiling impurity having a boiling point higher than that of ammonia contained in the gaseous ammonia derived in the deriving step by an adsorbent having adsorption ability for moisture and hydrocarbons alone. A process for purifying ammonia, characterized in that

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