JP4062710B2 - Method and apparatus for purifying ammonia - Google Patents

Description

  The present invention relates to a purification method for purifying crude ammonia gas containing various impurities, and more specifically, a purification method for ammonia that provides high-purity ammonia gas required in the semiconductor industry, chemical industry, research institutes, etc. And a purification apparatus thereof.

  Ammonia is generally widely used in the semiconductor manufacturing industry and the like, but purified ammonia is used at the manufacturing site. The raw material ammonia is ammonia produced at an ammonia manufacturing plant or recovered ammonia recovered from the use site. In addition to metals, this raw material ammonia contains nonmetallic impurities such as water, hydrogen, oxygen, carbon monoxide, carbon dioxide, and methane. It needs to be purified.

By the way, various devices for removing impurities contained in the raw material ammonia have been conventionally used. For example, regarding water removal, JP-A-9-142833 discloses a method for removing ammonia by contacting it with barium oxide. Further, JP-A-6-107412 discloses a method for removing ammonia from carbon monoxide and carbon dioxide by bringing them into contact with a nickel catalyst.
JP-A-9-142833 JP-A-6-107412

  However, since the raw material ammonia contains many types of impurities as described above, it is necessary to carry out individual substance removal methods shown in Patent Document 1, Patent Document 2, and the like. For this reason, there has been a problem that ammonia purification requires many purification steps. That is, in order to obtain a large amount of high-purity ammonia efficiently, it is necessary to perform continuous purification. However, when the number of individual purification steps increases, there is a problem that a large-scale purification facility is required for continuous purification.

  The present invention provides a method for purifying ammonia and a purification apparatus therefor, which can efficiently remove many kinds of non-metallic impurities contained in the raw material ammonia without using a multi-stage purification process. The purpose. In particular, a second object is to provide a purification method and a purification apparatus for ammonia that can efficiently remove impurities of water and oxygen and contribute to the efficiency of continuous purification. It is a third object of the present invention to provide an ammonia purification method and apparatus capable of efficiently removing many kinds of non-metallic impurities, purifying high-purity ammonia, and simplifying a continuous purification process.

  The present invention has been made to solve the above-mentioned problems, and a first embodiment of the present invention is a method for purifying crude ammonia gas containing a low-boiling impurity gas having a boiling point lower than that of ammonia, comprising a heat exchanger. The crude ammonia gas is introduced into a distillation section consisting of the above, the ammonia gas is liquefied by the cooling action of the heat exchanger, the low boiling point impurity gas is exhausted from the distillation section in a gaseous state, and the low boiling point impurity gas is discharged. It is a purification method of ammonia gas removed from the crude ammonia gas.

  According to a second aspect of the present invention, in the first aspect, a liquefied ammonia storage section for storing liquefied ammonia is provided in the distillation section, and the liquefied ammonia in the liquefied ammonia storage section is heated to be liquefied. This is a method for purifying ammonia gas by exhausting and removing low-boiling impurities remaining in ammonia.

  The 3rd form of this invention is the purification method of the ammonia gas which vaporizes by discharging | emitting liquefied ammonia from the said liquefied ammonia storage part and letting it pass through a heating part in the said 1st or 2nd form.

  A fourth aspect of the present invention is a method for purifying crude ammonia gas containing at least moisture and oxygen, wherein the crude ammonia gas is introduced into a moisture adsorption portion that adsorbs moisture and a catalyst portion that separates oxygen. A method for purifying ammonia gas by removing moisture and oxygen from the crude ammonia gas.

  According to a fifth aspect of the present invention, there is provided a method for purifying crude ammonia gas containing at least moisture and oxygen, wherein at least a pair of a moisture adsorbing part for adsorbing moisture and a catalyst part for separating oxygen are provided, Purification method of ammonia gas, in which the crude ammonia gas is introduced into the catalyst part and the catalyst part to remove moisture and oxygen from the crude ammonia gas, and the reducing gas is circulated and regenerated through the other moisture adsorption part and the catalyst part It is.

  According to a sixth aspect of the present invention, in the fifth aspect, the moisture and oxygen are removed from the crude ammonia gas and the reducing gas is circulated for each of the pair of the moisture adsorbing portion and the catalyst portion. This is a purification method of ammonia gas in which regeneration is continuously repeated and continuously purified.

  A seventh aspect of the present invention is a method for purifying crude ammonia gas containing moisture and a low-boiling impurity gas having a boiling point lower than that of ammonia, wherein the crude ammonia gas is introduced into a distillation section comprising a heat exchanger. A first removal step in which ammonia gas is liquefied by the cooling action of the heat exchanger, the low boiling point impurity gas is exhausted from the distillation section in a gaseous state, and the low boiling point impurity gas is removed from the crude ammonia gas. And the vaporization step for vaporizing ammonia liquefied in the distillation section by discharging from the distillation section and passing through the heating section, the moisture adsorption section for adsorbing moisture, and the catalyst section for separating oxygen. A method for purifying ammonia gas comprising the second removal step of introducing ammonia gas vaporized in the process and removing moisture and oxygen from the ammonia gas. That.

  According to an eighth aspect of the present invention, in the seventh aspect, a liquefied ammonia reservoir that stores the liquefied ammonia in the first removal step is provided, and the liquefied ammonia in the liquefied ammonia reservoir is heated. A method for purifying ammonia gas, which includes a third removal step of exhausting and removing low-boiling impurities remaining in the liquefied ammonia through the third removal step, wherein the liquefied ammonia is introduced into the vaporization step via the third removal step and vaporized. is there.

  According to a ninth aspect of the present invention, in the seventh or eighth aspect, the second removal step is performed on at least one of the moisture adsorption unit and the catalyst unit provided in the moisture adsorption unit and the catalyst unit. A removal process for introducing the ammonia gas vaporized in the vaporization step and removing moisture and oxygen from the ammonia gas, and a regeneration process for regenerating by circulating a reducing gas through the other moisture adsorption part and the catalyst part. This is a method for purifying ammonia gas.

  According to a tenth aspect of the present invention, in the ninth aspect, the regeneration by the removal treatment of moisture and oxygen and the flow of the reducing gas for each of the pair of the moisture adsorbing portion and the catalyst portion. This is a purification method of ammonia gas in which the treatment is repeated alternately and continuously purified.

  An eleventh aspect of the present invention is the ammonia gas according to any one of the first to tenth aspects, wherein the crude ammonia gas is a gas phase component gas obtained by separating raw material ammonia into a liquid phase and a gas phase. This is a purification method.

  A twelfth aspect of the present invention is a purifier for purifying crude ammonia gas containing a low-boiling impurity gas having a boiling point lower than that of ammonia, wherein the crude ammonia gas is introduced and the ammonia gas is liquefied by a cooling action. An apparatus for purifying ammonia gas, comprising a distillation section comprising an exchanger and provided with an exhaust passage in the distillation section for exhausting the low-boiling impurity gas in a gas state.

  According to a thirteenth aspect of the present invention, in the twelfth aspect, the distillation section stores the liquefied ammonia storage section that stores the liquefied crude ammonia, and the low boiling point impurity gas from the liquefied ammonia in the liquefied ammonia storage section. An apparatus for purifying ammonia gas comprising a heating device for separation.

  A fourteenth aspect of the present invention is an ammonia gas purification apparatus including the vaporizer for vaporizing the liquefied ammonia discharged from the distillation section in the twelfth or thirteenth aspect.

  A fifteenth aspect of the present invention is a purifying apparatus for purifying crude ammonia gas containing at least moisture and oxygen, comprising a moisture adsorption part for adsorbing moisture and a catalyst part for separating oxygen, It is an ammonia gas purification device that is introduced into the moisture adsorbing unit and the catalyst unit and removes moisture and oxygen from the crude ammonia gas.

  According to a sixteenth aspect of the present invention, there is provided a purification apparatus for purifying crude ammonia gas containing at least moisture and oxygen, comprising at least a pair of a moisture adsorbing portion for adsorbing moisture and a catalyst portion for separating oxygen, One of the moisture adsorption parts is provided with a crude ammonia gas introduction path for introducing the crude ammonia gas into the adsorption part and the catalyst part, and a reducing gas introduction path for introducing a reducing gas into each of the moisture adsorption part and the catalyst part. The crude ammonia gas is introduced into the catalyst part through the crude ammonia gas introduction path, and moisture and oxygen are removed from the crude ammonia gas, while the other moisture adsorbing part and the catalyst part are introduced through the reducing gas introduction path. It is an ammonia gas purifier for regenerating by circulating a reducing gas.

  According to a seventeenth aspect of the present invention, in the sixteenth aspect, the moisture and oxygen are removed from the crude ammonia gas and the reducing gas is circulated for each of the pair of the moisture adsorbing unit and the catalyst unit. It is an ammonia gas refining device provided with a continuous refining control unit that controls opening and closing of the crude ammonia gas introducing path and the reducing gas introducing path so as to alternately repeat regeneration.

  An eighteenth aspect of the present invention is a purifier for purifying crude ammonia gas containing moisture and a low-boiling impurity gas having a boiling point lower than that of ammonia, wherein the ammonia gas is removed by cooling by introducing the crude ammonia gas. A distillation section comprising a heat exchanger to be liquefied; an exhaust passage provided in the distillation section for exhausting the low-boiling impurity gas in a gas state; and a vaporizer for vaporizing the liquefied ammonia discharged from the distillation section. An ammonia gas provided with a moisture adsorption part for adsorbing moisture, a catalyst part for separating oxygen, and an ammonia gas introduction path for introducing the ammonia gas vaporized by the vaporizer into the moisture adsorption part and the catalyst part. It is a purification device.

  According to a nineteenth aspect of the present invention, in the eighteenth aspect, a liquefied ammonia storage section that stores the crude ammonia liquefied in the distillation section is provided in the distillation section, and the liquefied ammonia storage section is configured to store the liquefied ammonia storage section. It is the refinement | purification apparatus of the ammonia gas containing the heating apparatus for isolate | separating the low boiling-point impurity which remains in the liquefied ammonia in a part.

  According to a twentieth aspect of the present invention, in the eighteenth or nineteenth aspect, at least one pair of the moisture adsorption part and the catalyst part is provided, and each of the moisture adsorption part and the catalyst part is vaporized by the vaporizer. The ammonia gas introduction path for introducing ammonia gas is provided, and the reducing gas introduction path for introducing the reducing gas to each of the moisture adsorption part and the catalyst part is provided, and the ammonia is provided in one of the moisture adsorption part and the catalyst part. The vaporized ammonia gas is introduced through the gas introduction path, and moisture and oxygen are removed from the ammonia gas, while the reducing gas is circulated through the reducing gas introduction path to the other moisture adsorption part and the catalyst part for regeneration. This is an apparatus for purifying ammonia gas.

  According to a twenty-first aspect of the present invention, in the twentieth aspect, the moisture and oxygen are removed from the crude ammonia gas and the reducing gas is circulated for each of the pair of the moisture adsorbing portion and the catalyst portion. The ammonia gas purification apparatus includes a continuous purification control unit that controls opening and closing of the ammonia gas introduction path and the reducing gas introduction path so that regeneration is alternately repeated.

  A twenty-second aspect of the present invention is the ammonia gas according to any one of the twelfth to twenty-first aspects, wherein the crude ammonia gas is a gas phase component gas obtained by separating raw material ammonia into a liquid phase and a gas phase. This is a purification device.

  According to the method for purifying ammonia according to the first aspect of the present invention, crude ammonia gas is introduced into a distillation section composed of a heat exchanger, the ammonia gas is liquefied by the cooling action of the heat exchanger, and has a boiling point higher than that of ammonia. A low low-boiling impurity gas can be removed from the crude ammonia gas by exhausting the low-boiling point impurity gas from the distillation section in a gas state.

The crude ammonia gas in the present invention is a raw material ammonia in a gas state. Further, the low boiling point impurity gas having a boiling point lower than that of ammonia is hydrogen H ₂ , oxygen O ₂ , carbon monoxide CO, carbon dioxide CO ₂ , nitrogen N ₂ , methane CH _4, etc. contained in the crude ammonia gas. .

  According to the purification method of the second aspect of the present invention, in the first aspect, the distillation part is provided with a liquefied ammonia storage part for storing liquefied ammonia, and the liquefied ammonia in the liquefied ammonia storage part is added. By heating, low boiling point impurities remaining in the liquefied ammonia can be removed by exhaust, and higher purity ammonia can be purified.

  According to the purification method of the third aspect of the present invention, in the first or second aspect, since the liquefied ammonia is discharged from the liquefied ammonia reservoir and allowed to pass through the heating section, the first or second embodiment is used. In the second aspect, ammonia purified to a high purity can be discharged in a gas state, and can be supplied to a continuous process.

According to the purification method of the fourth aspect of the present invention, crude ammonia gas is introduced into a moisture adsorption part that adsorbs moisture and a catalyst part that separates oxygen, and at least non-metallic impurities are produced from the crude ammonia gas. Moisture and oxygen can be removed. If, for example, a nickel catalyst is used in the catalyst portion according to the present invention, not only oxygen but also carbon monoxide CO can be removed. The application of the nickel catalyst agent has the same removal effect even in the catalyst portion in the following embodiments of the present invention. Further, as the moisture adsorbent used in the moisture adsorbing part of the present invention, molecular sieve, activated alumina and the like are suitable.

  According to the purification method of the fifth aspect of the present invention, at least a pair of a moisture adsorbing portion that adsorbs moisture and a catalyst portion that separates oxygen are provided, and crude ammonia gas is introduced into one of the moisture adsorbing portion and the catalyst portion. While removing at least moisture and oxygen, which are non-metallic impurities, from the crude ammonia gas, the reducing gas is circulated and regenerated through the other moisture adsorbing unit and the catalyst unit, so that the water content is not interrupted by the regeneration operation. And oxygen can be continuously removed, and the purification efficiency of high-purity ammonia can be improved. As the reducing gas used for regeneration, a mixed gas of hydrogen and nitrogen or a mixed gas of hydrogen and self-purified ammonia gas is used.

  According to the purification method of the sixth aspect of the present invention, in the fifth aspect, for each of the pair of the moisture adsorption part and the catalyst part, the removal of moisture and oxygen of the crude ammonia gas, Since the regeneration by the flow of the reducing gas is alternately repeated and continuously purified, a large amount of high-purity ammonia can be purified.

  According to the purification method of the seventh aspect of the present invention, a crude ammonia gas containing water and a low-boiling impurity gas having a boiling point lower than that of ammonia is introduced into a distillation section composed of a heat exchanger, and the heat exchanger In the distillation section, a first removal step of liquefying ammonia gas by a cooling action, exhausting the low boiling point impurity gas from the distillation section in a gaseous state, and removing the low boiling point impurity gas from the crude ammonia gas; Ammonia vaporized in the vaporization step into a vaporization step for vaporizing the liquefied ammonia by discharging from the distillation unit and passing through the heating unit, a moisture adsorption unit for adsorbing moisture, and a catalyst unit for separating oxygen A second removal step of introducing gas and removing moisture and oxygen from the ammonia gas, so that the boiling point of ammonia is reduced by the first removal step. Removing low low boiling point impurity gas, and further, through the vaporization step, moisture and oxygen can be removed by the second removal step, a continuous impurity treatment step can be realized, and higher purity ammonia can be purified. Can do.

  According to the purification method of the 8th form of this invention, in the said 7th form, the liquefied ammonia storage part which stores the ammonia liquefied by the said 1st removal process is provided, The liquefied ammonia in the liquefied ammonia storage part And a third removal step for exhausting and removing low-boiling impurities remaining in the liquefied ammonia by heating, and the liquefied ammonia is introduced into the vaporization step through the third removal step and vaporized. In the third removal step, low-boiling impurities remaining after the first removal step can be removed, and the purification purity can be further increased.

  According to the purification method of the ninth aspect of the present invention, in the seventh or eighth aspect, the second removal step includes at least one pair of the moisture adsorption section and one of the moisture adsorption sections of the catalyst section. In addition, the ammonia gas vaporized in the vaporization step is introduced into the catalyst part, and a removal process is performed to remove moisture and oxygen from the ammonia gas, and the reducing gas is circulated through the other moisture adsorption part and the catalyst part for regeneration. In the second removal step, at least one of the moisture adsorbing unit and the catalyst unit is regenerated in the second removal step, thereby performing a continuous process of the first to second removal steps by a regeneration operation. Continuous purification is possible without interruption.

  According to the purification method of the tenth aspect of the present invention, in the ninth aspect, the moisture and oxygen removal treatment and the reducing gas are performed on each of the pair of the moisture adsorbing portion and the catalyst portion. Since the regeneration process by circulation is repeated alternately and continuously, high-purity ammonia can be purified in large quantities.

  According to the purification method of the eleventh aspect of the present invention, since the crude ammonia gas is a gas phase component gas obtained by separating raw material ammonia into a liquid phase and a gas phase, moisture and metal are used in the liquid phase. Using the property of containing a large amount of impurities, gas phase ammonia having a very low moisture and metal impurities content is used as a purification starting material, and the purification treatment in any one of the purification methods of the first to tenth embodiments is performed. By applying, higher purity ammonia can be purified.

  According to the ammonia gas purification apparatus of the twelfth aspect of the present invention, crude ammonia gas is introduced into a distillation section composed of a heat exchanger, and the ammonia gas is liquefied by the cooling action of the heat exchanger, and has a boiling point higher than that of ammonia. The low-boiling point impurity gas can be removed from the crude ammonia gas by exhausting the low-boiling-point impurity gas from the distillation section through the exhaust passage in a gas state.

  According to the purifying device of the thirteenth aspect of the present invention, in the twelfth aspect, the distillation section is provided with a liquefied ammonia storage section for storing liquefied ammonia, and the liquefied ammonia in the liquefied ammonia storage section is supplied to the distillation section. By heating with a heating device, low boiling point impurities remaining in the liquefied ammonia can be exhausted and removed, so that higher purity ammonia can be purified.

  According to the purifying device of the fourteenth aspect of the present invention, since the liquefied ammonia is discharged from the liquefied ammonia reservoir and vaporized by the vaporizer, the ammonia purified to a high purity in the twelfth or thirteenth embodiment is obtained. The gas can be discharged and supplied to a continuous process.

  According to the purifying apparatus of the fifteenth aspect of the present invention, crude ammonia gas is introduced into a moisture adsorption part that adsorbs moisture and a catalyst part that separates oxygen, and at least non-metallic impurities are produced from the crude ammonia gas. Moisture and oxygen can be removed.

  According to the purification apparatus of the sixteenth aspect of the present invention, at least a pair of a moisture adsorption part that adsorbs moisture and a catalyst part that separates oxygen are provided, and the crude ammonia gas introduction path is provided in one of the moisture adsorption part and the catalyst part. Through which the crude ammonia gas is introduced and at least moisture and oxygen, which are non-metallic impurities, are removed from the crude ammonia gas, while the reducing gas is circulated through the reducing gas introduction path to the other moisture adsorbing portion and the catalyst portion. Since it is regenerated, it is possible to continuously remove moisture and oxygen without being interrupted by the regenerating operation, and the purification efficiency of high purity ammonia can be improved.

  According to the purifying apparatus of the seventeenth aspect of the present invention, in the sixteenth aspect, for each of the pair of the moisture adsorbing part and the catalyst part, the removal of the moisture and oxygen of the crude ammonia gas, Regeneration by the flow of reducing gas can be continuously and continuously purified by controlling the opening and closing of the crude ammonia gas introduction path and the reducing gas introduction path by the continuous purification control unit, Mass purification can be realized.

  According to the purifying apparatus of the eighteenth aspect of the present invention, the boiling point of water and ammonia is reduced by the distillation unit and the exhaust path provided in the distillation unit and exhausting the low boiling point impurity gas in a gas state. The crude ammonia gas containing a low-boiling point impurity gas having a low temperature can be liquefied, and the low-boiling point impurity gas can be exhausted and removed from the distillation section in the gaseous state, and the liquefied ammonia is vaporized by the vaporizer Is introduced into the moisture adsorbing part and the catalyst part through the ammonia gas introduction path, so that moisture and oxygen can be removed from the ammonia gas, so that a continuous impurity treatment process can be realized and higher purity ammonia can be obtained. Can be purified.

  According to the purifying device of the nineteenth aspect of the present invention, there is provided a liquefied ammonia reservoir that stores the liquefied ammonia in the eighteenth aspect, and the liquefied ammonia in the liquefied ammonia reservoir is heated by the heating device. By doing so, low boiling point impurities remaining in the liquefied ammonia can be separated and removed, so that the purification purity can be increased.

  According to the purifying device of the twentieth aspect of the present invention, in the eighteenth or nineteenth aspect, at least one pair of the water adsorbing part and the catalyst part provided with one of the water adsorbing part and the catalyst part is the vaporizer. The ammonia gas vaporized by the gas is introduced through the ammonia gas introduction path, moisture and oxygen are removed from the ammonia gas, and the reducing gas is circulated through the reducing gas introduction path to the other moisture adsorption part and the catalyst part. Since the regeneration is performed, the regeneration process of the other moisture adsorption unit and the catalyst unit can be performed in parallel with the removal process by the one moisture adsorption unit and the catalyst unit, and the removal process by the regeneration operation is interrupted. And continuous purification becomes possible.

  According to the purifying device of the twenty-first aspect of the present invention, in the twentieth aspect, for each of the pair of the moisture adsorbing part and the catalyst part, the removal of the moisture and oxygen of the crude ammonia gas, Regeneration by the flow of reducing gas can be continuously and continuously purified by controlling the opening and closing of the crude ammonia gas introduction path and the reducing gas introduction path by the continuous purification control unit, Mass purification can be realized.

  In the twenty-second aspect of the present invention, a gas phase component gas obtained by separating raw material ammonia into a liquid phase and a gas phase is used as the crude ammonia gas, so that the liquid phase contains a large amount of moisture and metal impurities. By utilizing the contained properties, gas phase ammonia having a very low moisture and metal impurity content is used as a purification starting material, and by performing a purification treatment in any of the purification methods of the above 12th to 21st forms, High purity ammonia can be purified.

  Hereinafter, embodiments of a purification method and a purification apparatus for ammonia according to the present invention will be described in detail with reference to the accompanying drawings.

  A purification apparatus and a purification method for removing low boiling impurities from crude ammonia according to the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the purification apparatus of the present embodiment. The raw material ammonia is accommodated in the liquid ammonia cylinder 1, and the ammonia gas in the gas phase portion 12 becomes the crude ammonia gas for purification. This raw material ammonia is separated into the liquid phase part 11 and the gas phase part 12, and by this liquid phase / gas phase separation, most of the moisture and metal impurities contained in the raw material ammonia remain in the liquid phase part 11. Become. Therefore, the ammonia in the gas phase part 12 obtained by this liquid phase / gas phase separation is in a state in which moisture and metal impurities have been removed in advance, so that the starting material ammonia is transferred to the purification step in that state. As such, it is suitable for higher purity purification.

The distillation column 2 for removing many kinds of non-metallic impurities contained in the crude ammonia gas includes a distillation section 3 comprising a heat exchanger 31 provided at the upper part thereof, and a gas inflow part 7 provided at an intermediate part thereof. And a liquefied ammonia reservoir 8 provided at the bottom. The refrigerant circulation device 4 is connected to the heat exchanger 31 of the distillation unit 3 via refrigerant supply circulation paths 41 and 42, and the refrigerant is circulated and supplied to the heat exchanger 31. Ethylene glycol or the like is used as the refrigerant, and the inside of the heat exchanger 31 is maintained at −5 ° C. to + 10 ° C. by a temperature sensor monitoring system (not shown) provided in the refrigerant circulation device 4. A large number of gas passages 32 are formed in the heat exchanger 31 between the gas inflow portion 7 and the uppermost space 6 of the distillation column 2. The gas inflow part 7 communicates with the gas phase part 12 of the liquid ammonia cylinder 1 via the gas supply path 9, and the crude ammonia gas from the gas phase part 12 is supplied via the gas supply path 9. The crude ammonia gas supplied to the gas inflow portion 7 enters the gas passage 32 and is liquefied by the cooling action by the heat exchanger 31 and the refrigerant circulation device 4. It falls as droplets and liquefied ammonia is stored. On the other hand, when crude ammonia is liquefied in the distillation unit 3 in the uppermost space 6, an impurity gas having a low boiling point is deposited together with a part of the ammonia gas, and is exhausted through an exhaust passage 10 provided in the uppermost space 6 (not shown). ), The impurity gas can be discharged. At this time, the impurity gas deposited in the uppermost space 6 is mainly hydrogen H ₂ , oxygen O ₂ , carbon monoxide CO, carbon dioxide CO ₂ , nitrogen N ₂ , methane CH ₄ and the like.

According to the distillation unit 3 described above, since the crude ammonia gas is liquefied and the liquefied ammonia storage unit 8 stores the liquefied ammonia 81, the contained non-metallic impurities having a boiling point lower than that of ammonia are separated as gas. In addition, the impurity gas can be separated and recovered, and many kinds of impurities can be removed at once. Therefore, it is possible to easily and efficiently increase the purity of ammonia by the single distillation column 2 without requiring a separate removal step for impurities such as hydrogen, oxygen, carbon monoxide, carbon dioxide, nitrogen and methane. it can.

   The distillation column 2 has a residual impurity exhaust function for further purifying ammonia. In other words, the liquefied ammonia storage unit 8 is provided with a hot water circulation pipe 13 for circulating the hot water supplied from the hot water circulation device 5 in the storage unit. The hot water is maintained at 30 ° C. to 50 ° C. by a temperature sensor monitoring system (not shown) provided in the hot water circulation device 5, and this warm water circulation causes boiling (vaporization) on the surface of the hot water circulation pipe 13. As a result, impurities remaining during the liquefaction of crude ammonia in the distillation section 3 are separated from the liquid ammonia, discharged to the gas inflow section 7 side, and finally recovered in the uppermost space 6.

 Impurities remaining in the ammonia liquefied by the distillation unit 3 can be removed by providing the liquefied ammonia storage unit 8 with a heating function by the heating device including the hot water circulation device 5 and the hot water circulation pipe 13. The purification purity of ammonia can be further increased.

  The liquid ammonia stored in the liquefied ammonia storage unit 8 is discharged to the vaporization unit 15 side through the discharge path 14. The vaporizing unit 15 is disposed in the hot water tank 16. A heater 18 is provided in the hot water tank 16 and is controlled to a hot water state of 30 ° C. or more and 100 ° C. or less by a constant temperature control unit 17. Accordingly, the liquid ammonia discharged through the discharge path 14 is returned to the gas state in the vaporization unit 15 by being vaporized by the vaporizer comprising the hot water tank 16. By exhausting the re-vaporized purified ammonia gas through the vaporization section 15 by an exhaust device (not shown), high-purity ammonia gas can be obtained.

  Next, a purification apparatus capable of efficiently removing water and oxygen contained in the crude ammonia and a purification method thereof will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the purification apparatus of the present embodiment. The purification apparatus according to this embodiment includes a pair of water / oxygen / carbon monoxide removal units 20 and 21. The water / oxygen / carbon monoxide removal units 20 and 21 include a water removal unit 22 and a catalyst unit 23, and a water removal unit 24 and a catalyst unit 25, respectively. The moisture removing units 22 and 24 are filled with molecular sieves made of crystalline zeolite that adsorbs moisture. In the moisture removing units 22 and 24, moisture removal is performed by the adsorption action by the molecular sieve. In addition to the molecular sieve, a water adsorbent such as activated alumina may be used as the water adsorbent. The catalyst portions 23 and 25 are filled with a nickel catalyst agent. In the catalyst parts 23 and 25, oxygen and carbon monoxide are adsorbed and removed by the chemical adsorption action by the nickel catalyst. The removal of impurities of oxygen and carbon monoxide by the nickel catalyst is performed by the following chemical reaction.

2Ni + O ₂ → 2NiO
Ni + CO → Ni (CO)
Each of the water / oxygen / carbon monoxide removal units 20 and 21 has a two-layer separation structure of a water removal unit and a catalyst unit. If the amount of purified ammonia is, for example, 3N (standard state) m ³ / h, in a cylinder with an inner diameter of 43 mm, the molecular sieve is filled with 0.3 kg (filling height: 300 mm) in each water removal part. In addition, 0.8 kg (filling height: 500 mm) of nickel catalyst agent is filled in each catalyst part. Then, when ammonia gas is passed at a flow rate of 0.17 m / s in the charged state of these molecular sieves and nickel catalyst agent, the contact time with each adsorbent in the catalyst part and the water removal part is about 3 s, 1 .77s. Note that the same adsorption effect can be obtained even if the water / oxygen / carbon monoxide removal units 20 and 21 have a single hybrid structure in which a moisture adsorbent and a nickel catalyst are mixed.

  Gas phase ammonia gas from the liquid ammonia cylinder 50 is introduced into the water / oxygen / carbon monoxide removal sections 20 and 21 through the crude ammonia gas introduction path 51 through the introduction paths 29 and 30, respectively. The liquid ammonia cylinder 50 is the same as the liquid ammonia cylinder 1 used in the embodiment of FIG. 1, and is obtained by separating a raw material ammonia into a liquid phase and a gas phase, and a gas phase ammonia gas with a small amount of moisture and metal impurities is obtained. Used as a gas to be purified.

  In this apparatus, the gas flow direction is designed to be reversed in the purification process (lower part → upper part) and the regeneration process (upper part → lower part). However, the regeneration process can be performed from the lower part to the upper part in the same manner as the purification process. Reference numerals 56, 58, and 59 denote gas introduction side opening / closing valves for ammonia gas to the water / oxygen / carbon monoxide removal units 20 and 21. In addition, the regeneration gas composed of the hydrogen reducing gas supplied from the regeneration gas supply devices 54 and 55 passes through the regeneration gas introduction path, and from the regeneration gas introduction side opening / closing valves 61 and 64 to the respective water / oxygen / carbon monoxide removal units 20. , 21.

  An exhaust passage 28 is connected to the gas discharge passages 26, 27 from the water / oxygen / carbon monoxide removal sections 20, 21, and gas discharge-side opening / closing valves 62, 63 are provided in the gas discharge passage. Yes. Further, regeneration gas recovery devices 52 and 53 are provided for circulating the regeneration gas from the regeneration gas supply devices 54 and 55 to the water / oxygen / carbon monoxide removal section and then recovering the regeneration gas. On this recovery side path, on-off valves 57 and 60 for recovering the regeneration gas are arranged.

  As the regeneration gas, hydrogen is used for the reducing gas for the nickel catalyst, and dry nitrogen is used for removing moisture from the molecular sieve. Accordingly, hydrogen gas and nitrogen gas are vented as regeneration gas. Each water / oxygen / carbon monoxide removing section is provided with heaters 70 and 71 and used for heat treatment during regeneration. As an example of the regeneration process, first, dry nitrogen gas is supplied from the regeneration gas supply device 54 or 55 to the water / oxygen / carbon monoxide removal unit, and water is purged for 1 hour by the heaters 70 and 71. The oxygen / carbon monoxide removal section is heated to about 200 ° C. Next, in the heated state, hydrogen gas is also supplied from the regeneration gas supply device 54 or 55 in addition to the dry nitrogen gas, and the nickel catalyst is reduced for 3 hours. The reduction treatment of the nickel catalyst is performed by the following chemical reaction.

NiO + H ₂ → Ni + H ₂ O
Ni (CO) + 3H ₂ → Ni + CH ₄ + H ₂ O
Thereafter, the supply is switched to supplying only dry nitrogen gas, and the adsorbed moisture is removed for 2 hours. Finally, the heating by the heaters 70 and 71 is gradually reduced while flowing dry nitrogen gas, and the temperature is returned to room temperature over about 5 hours. As for the supply of the regeneration gas, if the amount of purified ammonia is 3N (standard state) m ³ / h, for example, the dry nitrogen gas amount is 200 N (standard state) L / h, and the reduced hydrogen gas amount is 4 N (standard state). ) L / h. Further, after the regeneration treatment is completed, the purification effect is not immediately performed, and if the purified ammonia gas is allowed to flow for a certain period of time before purification, the adsorption effect is improved.

  With the above configuration, since the pair of water / oxygen / carbon monoxide removal units 20 and 21 are used, one of them is used for the impurity removal treatment and the rest can be regenerated. By means of a purification management control device (not shown), for example, the gas introduction side valves 56 and 58 are opened from the state where all the valves are closed, and the exhaust side valve 62 is opened, and the water / oxygen / carbon monoxide removal unit 20 is opened. Introduce crude ammonia. By introducing crude ammonia, oxygen and carbon monoxide impurities by the nickel catalyst are removed by the catalyst unit 23, and further, moisture impurities are removed by moisture adsorption by the molecular sieve at the water removing unit 22, and water, oxygen The purified ammonia gas obtained by the continuous removal of carbon monoxide is discharged through the exhaust passage 28.

  When the purification process on the water / oxygen / carbon monoxide removal unit 20 side is completed, the valves 58 and 62 are closed. Further, by opening the valves 59 and 63, crude ammonia is introduced into the water / oxygen / carbon monoxide removing unit 21, and the purification process by the catalyst unit 25 and the water removing unit 24 can be continued. On the other hand, with respect to the water / oxygen / carbon monoxide removal unit 20 that has undergone the purification process, the regeneration process described above is performed by opening the valves 57 and 61. In this way, continuous purification of high-purity ammonia gas by removing impurities of water and oxygen can be realized by alternately switching each water / oxygen / carbon monoxide removal unit to purification and regeneration treatment, enabling mass purification To do.

  Next, a purification apparatus capable of efficiently removing many kinds of impurities contained in the crude ammonia and a purification method thereof will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the purification apparatus of the present embodiment. In the present embodiment, the same components as those in the embodiment of FIGS. 1 and 2 are denoted by the same reference numerals.

  The purification apparatus according to the present embodiment includes a distillation column 2 for removing various types of non-metallic impurities contained in the crude ammonia gas, and a pair of water / oxygen for removing impurities of moisture, oxygen, and carbon monoxide. -It consists of carbon monoxide removal parts 20 and 21. The distillation column 2 and the water / oxygen / carbon monoxide removing units 20 and 21 are the same as those described with reference to FIGS. Also in the present embodiment, the raw ammonia is separated into the liquid phase part 11 and the gas phase part 12 by the liquid ammonia cylinder 1, and the gas phase ammonia is exhausted from the gas phase part 12, whereby the distillation tower is obtained as crude ammonia gas. Led to 2. Reference numeral 19 denotes an on-off valve between the gas phase section 12, the gas supply path 9 and the gas inflow section 7.

As described above, the distillation column 2 includes the distillation part 3, the gas inflow part 7 provided in the intermediate part, and the liquefied ammonia storage part 8 provided in the lower part. The liquefying function of the distillation unit 3 liquefies crude ammonia gas, and the non-metallic impurities having a boiling point lower than that of ammonia are separated as gas while storing the liquefied ammonia in the liquefied ammonia storage unit 8. Impurity gas can be separated and recovered in the space 6, and various kinds of impurity gas G <b> 1 can be removed at a time by exhausting through the exhaust passage 10. The impurity gas deposited in the uppermost space 6 is mainly hydrogen H ₂ , oxygen O ₂ , carbon monoxide CO, carbon dioxide CO ₂ , nitrogen N ₂ , methane CH ₄ and the like. Further, by the warming action by the hot water circulation device 5 provided in the liquefied ammonia reservoir 8 at the lower part of the distillation column 2, impurities remaining during the liquefaction of the crude ammonia in the distillation unit 3 are also separated from the liquid ammonia and discharged to the gas inlet 7 side. Finally, it is recovered in the uppermost space 6 and the purification purity can be further increased.

  The liquid ammonia stored in the liquefied ammonia storage unit 8 is introduced into the water / oxygen / carbon monoxide removal units 20 and 21 through the discharge channel 14 and the hot water tank 16. The liquid ammonia is re-vaporized by passing through the hot water tank 16, and is introduced into the water / oxygen / carbon monoxide removal unit 20, 21 side as a secondary refined gas. Each of the water / oxygen / carbon monoxide removing units 20 and 21 includes a moisture removing unit 22 and a catalyst unit 23, and a moisture removing unit 24 and a catalyst unit 25. In the moisture removing units 22 and 24, moisture is removed by an adsorption action by the filled molecular sieve. Oxygen and carbon monoxide are adsorbed and removed from the catalyst portions 23 and 25 by the chemical adsorption action of the filled nickel catalyst. Therefore, the water, oxygen, and carbon monoxide impurities that could not be treated in the distillation tower 2 can be further removed by the water / oxygen / carbon monoxide removal units 20 and 21, and finally, various types Among the impurities, in particular, purified ammonia gas G2 having a high purity from which more impurities of water, oxygen and carbon monoxide are removed in two stages can be obtained through the exhaust passage 28.

  As described above, the purification apparatus according to the present embodiment realizes a more simplified high-purity purification process by connecting the distillation column 2 and the water / oxygen / carbon monoxide removal units 20 and 21 as a purification system. can do. As described above, since a pair of water / oxygen / carbon monoxide removal units 20 and 21 can be alternately switched between purification and regeneration, and one of them can always be operated for purification treatment, It is possible to avoid interruption of the purification process during regeneration when using the carbon monoxide removing units 20 and 21, and to enable continuous purification operation, thereby contributing to cost reduction of mass purification.

FIG. 4 shows an example of impurity concentration distribution measurement showing the purification effect by the above-described purification apparatus. First, the crude ammonia gas in the gas phase part 12 includes low-boiling impurities such as hydrogen H ₂ , oxygen O ₂ , carbon monoxide CO, carbon dioxide CO ₂ , nitrogen N ₂ , methane CH _4, and water H ₂ O in ppm. It is contained in many units of order density (see (1) in FIG. 4). When this is purified through the distillation column 2, as shown in (3) of FIG. 4, most of impurities except for water H ₂ O are reduced to a concentration unit of ppb order. Furthermore, by introducing the primary purified gas that has passed through the distillation column 2 to the water / oxygen / carbon monoxide removal units 20 and 21, as shown in FIG. 4 (4), water H ₂ O is also a concentration unit of ppb order. Is reduced to. Thus, according to the purification method using the purification apparatus of the present embodiment, extremely high purity purified ammonia can be obtained. According to this measurement example, oxygen and carbon monoxide impurities are almost removed on the distillation column 2 side, and a slight amount is removed at the stage of the water / oxygen / carbon monoxide removal sections 20 and 21.

  As shown in (2) of FIG. 4, since water is initially contained in the liquid phase in a large amount, the amount of gaseous ammonia is less than that in the liquid phase, but the process of continuous purification is performed. When ammonia gradually decreases at, the moisture content in the gas phase rapidly increases. A measurement example in the purification apparatus of the present embodiment is shown in FIG. From FIG. 5, it can be seen that when the ammonia usage rate of the liquid ammonia cylinder 1 is about 85%, the water content in the gas phase suddenly increases. Therefore, the use in this vicinity is the normal purification limit, and according to the purification apparatus of this embodiment, it can be said that continuous purification up to an ammonia usage rate of 85% is possible.

  As described above, according to the purification method and the purification apparatus of the present invention, industrial raw material ammonia and the like can be purified with high purity, the purification process can be simplified without using a complicated purification process, and continuous. A purification process can also be formed easily.

It is a schematic block diagram of the refiner | purifier which concerns on this invention. It is a schematic block diagram of another refinement | purification apparatus based on this invention. It is a schematic block diagram of another refinement | purification apparatus based on this invention. It is an impurity concentration analysis figure for demonstrating the purification effect by this invention. FIG. 4 is an ammonia usage amount-gas phase moisture concentration distribution diagram for explaining an appropriate ammonia usage state in the purification apparatus of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid ammonia cylinder 2 Distillation tower 3 Distillation part 8 Liquefied ammonia storage part 20 Water, oxygen, carbon monoxide removal part 21 Water, oxygen, carbon monoxide removal part 22 Moisture removal part 23 Catalyst part 24 Moisture removal part 25 Catalyst part

Claims (8)

A method for purifying crude ammonia gas containing moisture and a low-boiling impurity gas having a boiling point lower than that of ammonia, wherein the crude ammonia gas is introduced into a distillation section comprising a heat exchanger, and the heat exchanger is cooled A first removal step of liquefying ammonia gas, exhausting the low boiling point impurity gas from the distillation part in a gaseous state, and removing the low boiling point impurity gas from the crude ammonia gas, and then liquefying in the distillation part In the vaporization step, the vaporized ammonia was discharged from the distillation unit and vaporized by passing through the heating unit, and then the moisture adsorption unit adsorbing moisture and the catalyst unit separating oxygen were vaporized in the vaporization step. A second removal step of introducing ammonia gas and removing moisture and oxygen from the ammonia gas. Manufacturing method. A liquefied ammonia reservoir for storing the liquefied ammonia in the first removal step is provided, and a low boiling point impurity remaining in the liquefied ammonia is exhausted and removed by heating the liquefied ammonia in the liquefied ammonia reservoir. It includes a removal step, the third method for purifying ammonia gas according to claim 1 which is adapted to introduce vaporized into the vaporization step liquefied ammonia through a removal step. In the second removing step, the ammonia gas vaporized in the vaporization step is introduced into one of the moisture adsorption portion and the catalyst portion of at least one pair of the moisture adsorption portion and the catalyst portion, and moisture from the ammonia gas is introduced. method for purifying ammonia gas according to claim 1 or 2 comprising oxygen and removal process for removing, and a reproduction process to reproduce by circulating a reducing gas in the moisture adsorption portion and the catalytic portion of the other. 4. The ammonia according to claim 3 , wherein each of the pair of the moisture adsorbing part and the catalyst part is subjected to continuous purification by alternately repeating the removal process of moisture and oxygen and the regeneration process by circulation of the reducing gas. Gas purification method. A purification device for purifying crude ammonia gas containing moisture and a low-boiling impurity gas having a boiling point lower than that of ammonia, wherein the crude ammonia gas is introduced and the ammonia gas is liquefied by a cooling action of a heat exchanger to reduce the low A distillation section for removing the boiling-point impurity gas in the gas state by an exhaust passage, a vaporizer for vaporizing the liquefied ammonia discharged from the distillation section from which the low-boiling-point impurity gas has been removed by exhaust, and a vaporizer by the vaporizer An ammonia gas introduction path for introducing ammonia gas, a moisture adsorption part for adsorbing moisture from the ammonia gas introduced by the ammonia gas introduction path, and a catalyst part for separating oxygen are provided. Ammonia gas purification equipment. A liquefied ammonia storage section for storing crude ammonia liquefied in the distillation section is provided in the distillation section, and the liquefied ammonia storage section is used for separating low boiling point impurities remaining in the liquefied ammonia in the liquefied ammonia storage section. purification device of ammonia gas according to claim 5 comprising a raising device. At least a pair of the moisture adsorbing portion and the catalyst portion are provided, the ammonia adsorbing passage for introducing the ammonia gas vaporized by the vaporizer is provided in each of the moisture adsorbing portion and the catalyst portion, and each of the moisture A reducing gas introduction path for introducing a reducing gas into the adsorption section and the catalyst section is provided, and the vaporized ammonia gas is introduced into the moisture adsorption section and the catalyst section through the ammonia gas introduction path, and from the ammonia gas The apparatus for purifying ammonia gas according to claim 5 or 6 , wherein a reductive gas is circulated through the reductive gas introduction path to regenerate the water adsorbing part and the catalyst part on the other side while removing water and oxygen. For each of the pair of the moisture adsorbing unit and the catalyst unit, the removal of the moisture and oxygen of the crude ammonia gas and the regeneration by circulation of the reducing gas are alternately repeated, and the ammonia gas introduction path and the The apparatus for purifying ammonia gas according to claim 7, further comprising a continuous purification control unit that controls opening and closing of the reducing gas introduction path.

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