Ammonia decomposition system
Patent Information
- Application Number
- PCT/JP2025/044150
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-04-17
- Filing Date
- 2025-12-17
- Publication Date
- 2026-10-22
Smart Images
Figure JP2025044150_22102026_PF_FP_ABST
Abstract
Description
Ammonia decomposition system
[0001] The present disclosure relates to an ammonia decomposition system. The present application claims priority based on Japanese Patent Application No. 2025-067895 filed in Japan on April 17, 2025, the content of which is incorporated herein by reference in its entirety.
[0002] In an ammonia decomposition system, ammonia is converted into hydrogen and nitrogen gas. Ammonia is a low-cost chemical raw material. It has the advantages of high energy density, easy compression and liquefaction, convenient storage and transportation, and no CO generation when burned ２ For this reason, the concept of using ammonia as a hydrogen transport carrier has attracted widespread attention. Furthermore, the high mass density and volumetric hydrogen storage density of ammonia make it promising as a hydrogen transport carrier. In addition, the nitrogen gas generated by catalytic ammonia decomposition is an excellent protective gas that can be widely applied in the semiconductor industry and the metallurgical industry.
[0003] In such ammonia decomposition, it is desired to reduce the water content of ammonia in order to improve efficiency. For example, Patent Document 1 discloses an ammonia decomposition method in which ammonia gas supplied to a reactor is heated by a heat exchanger to reduce the water content of ammonia.
[0004] Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2024-524086
[0005] As described above, when decomposing ammonia, it is desired to reduce the water content of ammonia before it is supplied to the reactor in order to improve efficiency. On the other hand, if a heating device is added to reduce the water content of ammonia, the overall system will have complicated equipment and increased costs. Therefore, it is desired to reduce the water content of ammonia without adding additional equipment.
[0006] The present disclosure provides an ammonia decomposition system capable of reducing the water content of ammonia without adding additional equipment.
[0007] The ammonia decomposition system according to this disclosure is capable of decomposing ammonia contained in a gas to be treated into nitrogen and hydrogen, and discharges a decomposition gas containing the nitrogen, the hydrogen and undecomposed ammonia; an absorption tower into which the decomposition gas is introduced from the ammonia decomposition reactor, and the decomposition gas is brought into contact with an absorbent, and discharges an absorbent that has absorbed the ammonia contained in the decomposition gas, and an absorption tower exhaust gas from which the ammonia has been removed and the nitrogen and hydrogen remain; a regeneration tower that heats the absorbent discharged from the absorption tower to release the ammonia, and discharges the absorbent from which the ammonia has been released and a regeneration tower exhaust gas containing the ammonia; and the regeneration The regeneration tower comprises a condenser that cools and condenses the tower exhaust gas, a reflux drum that discharges a separated exhaust gas from the regeneration tower exhaust gas condensed in the condenser and supplies it to the ammonia decomposition reactor, and also supplies the separated liquid ammonia to the regeneration tower, a supply line that supplies the gas to be treated, which contains ammonia, to the regeneration tower, and a regeneration tower exhaust gas supply line that supplies a portion of the regeneration tower exhaust gas to the ammonia decomposition reactor before supplying it to the condenser, wherein the regeneration tower is capable of heating the absorbent liquid and the gas to be treated, and the regeneration tower exhaust gas supply line supplies the regeneration tower exhaust gas and a portion of the heated gas to be treated to the ammonia decomposition reactor.
[0008] Furthermore, other ammonia decomposition systems relating to this disclosure include: an ammonia decomposition reactor capable of decomposing ammonia contained in a gas to be treated into nitrogen and hydrogen, and discharging a decomposition gas containing the nitrogen, the hydrogen and undecomposed ammonia; an absorption tower into which the decomposition gas is introduced from the ammonia decomposition reactor, and the decomposition gas is brought into contact with an absorbent liquid, discharging an absorbent liquid that has absorbed the ammonia contained in the decomposition gas, and an absorption tower exhaust gas from which the ammonia has been removed and the nitrogen and hydrogen remain; a regeneration tower that heats the absorbent liquid discharged from the absorption tower to release the ammonia, and discharging the absorbent liquid from which the ammonia has been released and a regeneration tower exhaust gas containing the ammonia; and the pre- The regeneration tower comprises a condenser that cools the exhaust gas from the regeneration tower to condense it into a regeneration tower discharge liquid, a reflux drum that discharges a separated exhaust gas from which condensed liquid ammonia has been separated from the regeneration tower discharge liquid condensed in the condenser and supplies it to the ammonia decomposition reactor, and also supplies the separated liquid ammonia to the regeneration tower, a supply line that supplies the gas to be treated, which contains ammonia, to the regeneration tower, a partial liquid ammonia circulation line that supplies a portion of the liquid ammonia to the ammonia decomposition reactor, and a vaporizer that is arranged in the partial liquid ammonia circulation line and vaporizes the liquid ammonia flowing through the partial liquid ammonia circulation line, and the regeneration tower is capable of heating the absorbent liquid and the gas to be treated.
[0009] According to the ammonia decomposition system of this disclosure, the water content of ammonia can be reduced without adding any additional equipment.
[0010] This is a schematic diagram showing an ammonia decomposition system according to the first embodiment. This is a schematic diagram showing an ammonia decomposition system according to the second embodiment. This is a schematic diagram showing an ammonia decomposition system according to the third embodiment. This is a schematic diagram showing an ammonia decomposition system according to the fourth embodiment. This is a schematic diagram showing an ammonia decomposition system according to the fifth embodiment. This is a schematic diagram showing an ammonia decomposition system according to a modified example of the fifth embodiment.
[0011] The following describes embodiments for implementing the ammonia decomposition system according to this disclosure, with reference to the attached drawings. However, this disclosure is not limited to these embodiments.
[0012] <First Embodiment> (Ammonia Decomposition System) The ammonia decomposition system 1 generates hydrogen and nitrogen by thermally decomposing a target gas G1 containing ammonia, which is the raw material. The target gas G1 is the gas to be decomposed in the ammonia decomposition system 1 and is a gas with a high ammonia content. In addition to ammonia, the target gas G1 may also contain hydrogen, nitrogen, and impurities (water, oil, etc.). The hydrogen and nitrogen generated in the ammonia decomposition system 1 are used externally for various purposes.
[0013] As shown in Figure 1, the ammonia decomposition system 1 of this embodiment includes an ammonia decomposition reactor 2, an absorption tower 3, a regeneration tower 4, a supply unit 5, a supply line L1, a regeneration tower exhaust gas line L2, a condenser 6, a reflux drum 7, a reflux line L3, a reflux pump 8, a reactor supply line L4, a regeneration tower exhaust gas supply line L5, a reactor discharge line L6, a supply heat exchanger 9, a decomposition gas cooler 10, a rich line L7, a rich pump 11, a lean line L8, an absorption liquid heat exchanger 12, a lean cooler 13, a regeneration tower heating line L9, and a reboiler 14.
[0014] (Ammonia Decomposition Reactor) The ammonia decomposition reactor 2 is capable of decomposing ammonia contained in the gas to be treated G1 into nitrogen and hydrogen. The ammonia decomposition reactor 2 discharges decomposition gas G2 containing nitrogen, hydrogen, and undecomposed ammonia. The ammonia decomposition reactor 2 incorporates a predetermined catalyst (not shown).
[0015] (Absorption Tower) Decomposition gas G2 from ammonia decomposition reactor 2 is introduced into absorption tower 3. Absorption tower 3 removes ammonia from decomposition gas G2 by bringing it into contact with an absorbent liquid. For example, water (wash water) is used as the absorbent liquid. Absorption tower 3 separately discharges the absorbent liquid (rich liquid E1) that has absorbed the ammonia contained in decomposition gas G2, and the absorption tower exhaust gas G3 in which nitrogen and hydrogen remain after ammonia has been removed. The absorbent liquid discharged from absorption tower 3 and flowing through rich line L7 is called rich liquid E1. Rich liquid E1 is an absorbent liquid with a high concentration of ammonia after ammonia has been absorbed in absorption tower 3. In addition, absorbent liquid (lean liquid E2) from which ammonia has been released in regeneration tower 4 is introduced into absorption tower 3. The absorbent liquid discharged from regeneration tower 4 and flowing through lean line L8 is called lean liquid E2. Lean liquid E2 is an absorbent liquid with a low concentration of ammonia after ammonia has been released in regeneration tower 4. In other words, the lean liquid E2 has a lower ammonia concentration than the rich liquid E1. The absorption tower 3 is equipped with a nozzle (not shown) that discharges the absorbent liquid downward in the vertical direction. As a result, in the absorption tower 3, the decomposition gas G2 moving upward in the vertical direction and the absorbent liquid moving downward in the vertical direction come into countercurrent contact, and the ammonia in the decomposition gas G2 is absorbed by the absorbent liquid. The absorption tower exhaust gas G3 is discharged to the outside from the absorption tower 3. The absorption tower exhaust gas G3 is discharged outside the ammonia decomposition system 1. The absorption tower exhaust gas G3 can be used as fuel as is, or it can be purified and used as hydrogen for chemical purposes, or it can be supplied as raw material hydrogen for fuel cells.
[0016] (Regeneration Tower) The absorbent liquid (rich liquid E1) discharged from the absorption tower 3 is introduced into the regeneration tower 4. The regeneration tower 4 heats the rich liquid E1, which is the absorbent liquid discharged from the absorption tower 3, to release ammonia from the rich liquid E1. The regeneration tower 4 is capable of heating the gas supplied to its interior. As a result, the regeneration tower 4 separates ammonia from the rich liquid E1 by releasing most of it along with a small amount of vapor. Furthermore, the gas to be treated G1 is introduced into the regeneration tower 4. When the gas to be treated G1 is heated in the regeneration tower 4, the water evaporates and the water content is reduced. As a result, the regeneration tower 4 separately discharges the absorbent liquid from which ammonia has been released by heating the absorbent liquid and the gas to be treated G1, and the regeneration tower exhaust gas G4 containing the ammonia released from the absorbent liquid and the heated gas to be treated G1. Furthermore, the exhaust gas G4 from the regeneration tower, which is a mixture of ammonia released from the absorbent liquid and the treated gas G1 from which water has been removed by heating in the regeneration tower 4, has a high concentration of ammonia.
[0017] (Supply Unit) Supply Unit 5 temporarily stores the gas G1 to be treated, which contains ammonia that is to be decomposed. Supply Unit 5 stores the gas G1 to be treated in liquid form. For example, liquid ammonia is supplied to Supply Unit 5 from an external ammonia supply source, and nitrogen gas is supplied from a nitrogen supply source to pressurize the tank.
[0018] (Supply Line) Supply line L1 sends the liquid gas to be treated G1 from the supply unit 5 to the regeneration tower 4. Supply line L1 is piping that connects the supply unit 5 and the regeneration tower 4. Supply line L1 does not connect the supply unit 5 to any equipment other than the regeneration tower 4. Therefore, the gas to be treated G1 is supplied only to the regeneration tower 4 via supply line L1.
[0019] (Regeneration tower exhaust gas line) The regeneration tower exhaust gas line L2 supplies the regeneration tower exhaust gas G4 discharged from the regeneration tower 4 to the reflux drum 7 via the condenser 6. The regeneration tower exhaust gas line L2 is connected to the top of the regeneration tower 4. The regeneration tower exhaust gas line L2 is piping that connects the regeneration tower 4 and the reflux drum 7.
[0020] (Condenser) The condenser 6 cools the regeneration tower exhaust gas G4 discharged from the regeneration tower 4, thereby condensing it into regeneration tower effluent E3. In other words, the condenser 6 cools the regeneration tower exhaust gas G4, condensing the liquid ammonia contained in the regeneration tower exhaust gas G4 into a liquid. The condenser 6 condenses the regeneration tower exhaust gas G4 by exchanging heat between the cooling water and the regeneration tower exhaust gas G4. The condenser 6 is located in the middle of the regeneration tower exhaust gas line L2. In other words, the condenser 6 cools the regeneration tower exhaust gas G4 before it is supplied to the reflux drum 7.
[0021] (Reflux Drum) The reflux drum 7 separates the liquid ammonia contained in the regeneration tower exhaust gas G4 discharged from the regeneration tower 4. The reflux drum 7 discharges the separated exhaust gas G5, which is the liquid ammonia separated from the regeneration tower exhaust liquid E3 condensed in the condenser 6, and supplies it to the ammonia decomposition reactor 2, while also supplying the separated liquid ammonia E4 to the regeneration tower 4. The separated exhaust gas G5 is a gas in a water-depleted state and is ammonia gas containing hydrogen and nitrogen that are not condensed in the condenser. The liquid ammonia E4 contains a large amount of liquefied ammonia. In this embodiment, the reflux drum 7 recovers the liquid ammonia E4 produced by condensation in the condenser 6 and returns it to the regeneration tower 4. The liquid ammonia E4 recovered by the reflux drum 7 is discharged toward the regeneration tower 4. The reflux drum 7 discharges the separated exhaust gas G5, which has been removed by the regeneration tower 4, to the equipment supply line L4.
[0022] (Recirculation Line) The recirculation line L3 supplies liquid ammonia E4 discharged from the recirculation drum 7 to the regeneration tower 4. The recirculation line L3 is piping that connects the recirculation drum 7 and the regeneration tower 4. A recirculation pump 8 is located in the recirculation line L3.
[0023] (Reflux Pump) The reflux pump 8 pressurizes the liquid ammonia E4 and sends it to the regeneration tower 4. The reflux pump 8 is located in the middle of the reflux line L3. In other words, the reflux pump 8 pressurizes the liquid ammonia E4 flowing through the reflux line L3 and sends it to the regeneration tower 4.
[0024] (Reactor supply line) The reactor supply line L4 supplies the separated exhaust gas G5 discharged from the reflux drum 7 to the ammonia decomposition reactor 2. The reactor supply line L4 is a pipe connecting the reflux drum 7 and the ammonia decomposition reactor 2. The reactor supply line L4 also supplies the regeneration tower exhaust gas G4, which contains the heated gas to be treated G1 supplied from the regeneration tower exhaust gas supply line L5 that joins it midway, to the ammonia decomposition reactor 2. The reactor supply line L4 supplies the separated exhaust gas G5 and the regeneration tower exhaust gas G4 to the regeneration tower 4 via the supply heat exchanger 9.
[0025] (Regeneration Tower Exhaust Gas Supply Line) The regeneration tower exhaust gas supply line L5 supplies a portion of the regeneration tower exhaust gas G4 to the ammonia decomposition reactor 2 before supplying it to the condenser 6. Therefore, the regeneration tower exhaust gas supply line L5 supplies the regeneration tower exhaust gas G4, which includes the heated gas to be treated G1, to the ammonia decomposition reactor 2. This enables the regeneration tower exhaust gas supply line L5 to supply the ammonia gas heated in the regeneration tower 4 to the ammonia decomposition reactor 2. The regeneration tower exhaust gas supply line L5 is a pipe that connects the regeneration tower exhaust gas line L2 and the reactor supply line L4. The regeneration tower exhaust gas supply line L5 is connected to the regeneration tower exhaust gas line L2 between the regeneration tower 4 and the condenser 6. The regeneration tower exhaust gas supply line L5 is connected to the reactor supply line L4 between the reflux drum 7 and the ammonia decomposition reactor 2.
[0026] (Reactor discharge line) The reactor discharge line L6 supplies the decomposition gas G2 discharged from the ammonia decomposition reactor 2 to the absorption tower 3. The reactor discharge line L6 is a pipe connecting the ammonia decomposition reactor 2 and the absorption tower 3. The reactor discharge line L6 supplies the decomposition gas G2 to the absorption tower 3 via the supply heat exchanger 9.
[0027] (Supply Heat Exchanger) The supply heat exchanger 9 is positioned to span the reactor supply line L4 and the reactor discharge line L6. The supply heat exchanger 9 performs heat exchange between the separated exhaust gas G5, the regeneration tower exhaust gas G4, and a portion of the heated gas to be treated G1 flowing through the reactor supply line L4, and the decomposition gas G2 flowing through the reactor discharge line L6. As a result, the supply heat exchanger 9 heats the separated exhaust gas G5, the regeneration tower exhaust gas G4, and a portion of the heated gas to be treated G1 that are heading towards the ammonia decomposition reactor 2. At the same time, the supply heat exchanger 9 cools the decomposition gas G2 that flows through the reactor discharge line L6 from the ammonia decomposition reactor 2 towards the absorption tower 3.
[0028] (Decomposition Gas Cooler) The decomposition gas cooler 10 further cools the decomposition gas G2 cooled in the supply heat exchanger 9 and sends it to the absorption tower 3. The decomposition gas cooler 10 is located in the middle of the reactor discharge line L6. The decomposition gas cooler 10 is located between the supply heat exchanger 9 and the absorption tower 3.
[0029] (Rich line) Rich line L7 supplies the absorbent liquid containing ammonia from the absorption tower 3 to the regeneration tower 4. Rich line L7 is a pipe connecting the bottom of the absorption tower 3 and the top of the regeneration tower 4. Rich line L7 supplies the rich liquid E1 to the regeneration tower 4 via the absorbent liquid heat exchanger 12.
[0030] (Rich Pump) The rich pump 11 pressurizes the rich liquid E1 and sends it to the regeneration tower 4. The rich pump 11 is located in the middle of the rich line L7. In other words, the rich pump 11 pressurizes the rich liquid E1 flowing through the rich line L7 and sends it to the regeneration tower 4. Note that the rich pump 11 does not need to be located if the pressure inside the absorption tower 3 is higher than the pressure inside the regeneration tower 4.
[0031] (Lean line) The lean line L8 supplies the absorbent liquid from which ammonia has been released from the regeneration tower 4 to the absorption tower 3. The lean line L8 is a pipe that connects the bottom of the regeneration tower 4 to the top of the absorption tower 3. The lean line L8 supplies the lean liquid E2 to the absorption tower 3 via the absorbent liquid heat exchanger 12.
[0032] (Absorbent Liquid Heat Exchanger) The absorbent liquid heat exchanger 12 performs heat exchange between the rich liquid E1 flowing through the rich line L7 and the lean liquid E2 flowing through the lean line L8. As a result, in the absorbent liquid heat exchanger 12, the rich liquid E1 flowing through the rich line L7, which has been pressurized by the rich pump 11, is heated as it flows from the absorption tower 3 to the regeneration tower 4. At the same time, in the absorbent liquid heat exchanger 12, the lean liquid E2 flowing through the lean line L8, which flows from the regeneration tower 4 to the absorption tower 3, is cooled.
[0033] (Lean Cooler) The lean cooler 13 further cools the absorbent liquid cooled in the absorbent liquid heat exchanger 12 and sends it to the absorption tower 3. The lean cooler 13 is located in the middle of the lean line L8. The lean cooler 13 is located between the absorbent liquid heat exchanger 12 and the absorption tower 3.
[0034] (Regeneration Tower Heating Line) The regeneration tower heating line L9 heats a portion of the lean liquid E2 and supplies it to the regeneration tower 4 in order to raise the temperature inside the regeneration tower 4. The regeneration tower heating line L9 heats a portion of the lean liquid E2 before supplying it to the absorption liquid heat exchanger 12 and then supplies it to the regeneration tower 4. As a result, the inside of the regeneration tower 4 is heated by the heated lean liquid E2 supplied from the regeneration tower heating line L9. The regeneration tower heating line L9 is a pipe that connects the lean line L8 and the lower part of the regeneration tower 4. The regeneration tower heating line L9 is connected to the lean line L8 between the regeneration tower 4 and the absorption liquid heat exchanger 12.
[0035] (Reboiler) The reboiler 14 heats the lean liquid E2 flowing through the regeneration tower heating line L9. High-temperature steam is supplied to the reboiler 14 as a heating medium. The reboiler 14 heats the lean liquid E2 by exchanging heat between the steam and the lean liquid E2. The reboiler 14 is located in the middle of the regeneration tower heating line L9.
[0036] Furthermore, if the pressure inside the ammonia decomposition reactor 2 is higher than the pressure inside the regeneration tower 4, it is preferable to have a pump in the supply line L1 between the supply vaporizer 21 and the supply unit 5. In this case, it is preferable that the gas to be treated G1 is supplied to the pump in a liquefied state.
[0037] (Flow of gas and liquid in the ammonia decomposition system) In the ammonia decomposition system 1 of this first embodiment, the gas to be treated G1 supplied from the supply unit 5 via the supply line L1 is sent to the regeneration tower 4. In the regeneration tower 4, the gas to be treated G1 is heated and the water contained in the gas to be treated G1 is removed. The gas to be treated G1 from which the water has been removed is discharged as regeneration tower exhaust gas G4 to the regeneration tower exhaust gas line L2. The gas to be treated G1 discharged to the regeneration tower exhaust gas line L2 is supplied to the regeneration tower exhaust gas supply line L5. As a result, the heated gas to be treated G1 is supplied to the reactor supply line L4 before being supplied to the condenser 6. The gas to be treated G1 supplied to the reactor supply line L4 is further heated by heat exchange with the decomposition gas G2 in the supply heat exchanger 9 and supplied to the ammonia decomposition reactor 2.
[0038] In the ammonia decomposition reactor 2, ammonia is decomposed into nitrogen and hydrogen. As a result, decomposition gas G2 is discharged from the ammonia decomposition reactor 2 to the reactor discharge line L6. The decomposition gas G2 discharged to the reactor discharge line L6 is cooled by heat exchange with the gas to be treated G1 in the supply heat exchanger 9, so that it can be used to heat the gas to be treated G1. The cooled decomposition gas G2 flows further through the reactor discharge line L6 and is cooled even more in the supply heat exchanger 9. The decomposition gas G2 cooled in the supply heat exchanger 9 flows through the reactor discharge line L6 and is supplied to the absorption tower 3.
[0039] In the absorption tower 3, the decomposition gas G2 is brought into contact with the absorbent liquid, and ammonia is removed from the decomposition gas G2. As a result, the rich liquid E1 and the absorption tower exhaust gas G3 are discharged separately from the absorption tower 3. The absorption tower exhaust gas G3 is discharged outside the ammonia decomposition system 1 and can be used as fuel as is, or purified and used as hydrogen for chemical purposes, or supplied as raw material hydrogen for fuel cells. The rich liquid E1 is discharged into the rich line L7, pressurized by the rich pump 11, and sent to the absorbent liquid heat exchanger 12. The rich liquid E1 is heated by heat exchange with the lean liquid E2 in the absorbent liquid heat exchanger 12 and supplied to the regeneration tower 4.
[0040] In the regeneration tower 4, the rich liquid E1 supplied from the rich line L7 is heated, and ammonia is released from the rich liquid E1. At the same time, a portion of the lean liquid E2 heated in the reboiler 14 is supplied to the regeneration tower 4. As a result, the internal temperature of the regeneration tower 4 rises, and the rich liquid E1 is heated. The heated rich liquid E1 from which ammonia has been released becomes lean liquid E2 and is discharged to the lean line L8. The lean liquid E2 discharged to the lean line L8 is sent to the absorption liquid heat exchanger 12. The lean liquid E2 is cooled by heat exchange with the rich liquid E1 in the absorption liquid heat exchanger 12. The lean liquid E2 cooled in the absorption liquid heat exchanger 12 is further cooled in the lean cooler 13 and supplied to the absorption tower 3 via the lean line L8. The lean liquid E2 supplied to the absorption tower 3 is brought into contact with the decomposition gas G2 in the absorption tower 3. Furthermore, a portion of the lean liquid E2 discharged into the lean line L8 is sent to the regeneration tower heating line L9, heated in the reboiler 14, and returned to the regeneration tower 4.
[0041] Furthermore, the ammonia released from the rich liquid E1, along with the heated gas to be treated G1, becomes the regeneration tower exhaust gas G4 and is discharged into the regeneration tower exhaust gas line L2. During rated operation, the heated gas to be treated G1 supplied from the supply line L1 and the ammonia generated from the rich line L7 are discharged together as the regeneration tower exhaust gas G4. However, in stages such as during startup, before the rich liquid E1 is supplied to the regeneration tower 4 from the rich line L7, the regeneration tower exhaust gas G4 may contain only the heated gas to be treated G1. A portion of the regeneration tower exhaust gas G4 discharged into the regeneration tower exhaust gas line L2 is supplied to the regeneration tower exhaust gas supply line L5 and sent to the ammonia decomposition reactor 2. On the other hand, the remaining portion of the regeneration tower exhaust gas G4 that is not supplied to the regeneration tower exhaust gas supply line L5 is supplied to the condenser 6. In the condenser 6, the regeneration tower exhaust gas G4 discharged from the regeneration tower 4 is cooled and condensed into the regeneration tower discharge liquid E3 containing liquid ammonia. The regeneration tower discharge liquid E3 is supplied to the recirculation drum 7 via the regeneration tower exhaust gas line L2.
[0042] The reflux drum 7 discharges the separated exhaust gas G5, from which liquid ammonia E1 is separated from the regenerator column effluent E3 condensed by the condenser 6, to the reactor supply line L4. The separated exhaust gas G5 in the reactor supply line L4 merges with the regenerator column exhaust gas G4 flowing through the regenerator column exhaust gas supply line L5, and flows toward the ammonia decomposition reactor 2. As described above, the gas supplied to the reactor supply line L4 is heat-exchanged with the decomposition gas G2 in the supply heat exchanger 9 to be further heated, and then supplied to the ammonia decomposition reactor 2.
[0043] (Effects) According to the ammonia decomposition system 1 of the first embodiment as described above, the target processing gas G1 can be heated using the regenerator column 4. Therefore, moisture contained in the target processing gas G1 can be removed, and a gas with a high ammonia concentration can be supplied to the ammonia decomposition reactor 2. That is, a gas with reduced moisture that does not contribute to the decomposition reaction in the ammonia decomposition reactor 2 can be supplied to the ammonia decomposition reactor 2. Furthermore, by utilizing the regenerator column 4 that heats the rich liquid E1 for heating the target processing gas G1, there is no need to add an additional device for heating to vaporize the target processing gas G1. Accordingly, the number of additional devices and the number of pipes connecting the devices can be reduced. Thereby, the water content in ammonia can be reduced without adding an extra apparatus.
[0044] In addition, before the target processing gas G1 heated in the regenerator column 4 is supplied to the condenser 6, it is supplied from the regenerator column exhaust gas supply line L5 to the reactor supply line L4 and sent to the ammonia decomposition reactor 2. Therefore, the flow rate of the regenerator column exhaust gas G4 supplied to the condenser 6 is reduced. Accordingly, the flow rate of the cooling water used for cooling the regenerator column exhaust gas G4 in the condenser 6 can be suppressed.
[0045] Furthermore, the regenerator column exhaust gas G4 sent to the ammonia decomposition reactor 2 is heated using the heat of the decomposition gas G2 discharged from the ammonia decomposition reactor 2 by the supply heat exchanger 9 while flowing through the reactor supply line L4. Therefore, the heating and cooling of the gas including the condenser 6 and the supply heat exchanger 9 can be effectively performed by configuring a process with excellent thermal efficiency in the ammonia decomposition system 1.
[0046] Further, a regeneration tower exhaust gas supply line L5 is connected to a reactor supply line L4 that supplies the separated exhaust gas G5 discharged from the reflux drum 7 to the ammonia decomposition reactor 2. Therefore, the separated exhaust gas G5 recovered in the reflux drum 7 can be supplied to the ammonia decomposition reactor 2 together with the regeneration tower exhaust gas G4 containing the heated target processing gas G1. Accordingly, most of the ammonia contained in the gas discharged from the regeneration tower 4 can be supplied to the ammonia decomposition reactor 2.
[0047] Furthermore, the ammonia decomposition system 1 of the present embodiment can be easily manufactured by merely additionally installing the supply line L1 and the regeneration tower exhaust gas supply line L5 to an existing system for decomposing ammonia that is already provided with the ammonia decomposition reactor 2, the absorption tower 3, and the regeneration tower 4. That is, it is possible to easily manufacture a system capable of reducing the water content of ammonia without adding any additional equipment to the existing system for decomposing ammonia.
[0048] <Second Embodiment> Next, an ammonia decomposition system 1A according to a second embodiment of the present disclosure will be described. In the second embodiment described below, components common to those of the above-described first embodiment are denoted by the same reference numerals in the drawings, and descriptions thereof are omitted. The ammonia decomposition system 1A of the second embodiment differs from the first embodiment in that it has a structure capable of vaporizing the target processing gas G1 before being supplied to the regeneration tower 4.
[0049] As shown in Figure 2, the ammonia decomposition system 1A of the second embodiment further includes a supply vaporizer 21.
[0050] (Supply Vaporizer) The supply vaporizer 21 vaporizes the target processing gas G1 flowing through the supply line L1 and supplies the vaporized gas to the regeneration tower 4. High-temperature steam is supplied to the supply vaporizer 21. The supply vaporizer 21 is supplied with steam at a temperature lower than that of the reboiler 14. In the supply vaporizer 21, the target processing gas G1 is heated by performing heat exchange between the steam and the target processing gas G1. The supply vaporizer 21 is arranged in the middle of the supply line L1. The supply vaporizer 21 is arranged between the supply unit 5 and the regeneration tower 4.
[0051] (Effects) In the ammonia decomposition system 1A of this second embodiment, the gas to be treated G1 is heated in the supply vaporizer 21 before being supplied to the regeneration tower 4. Therefore, even if the gas to be treated G1 supplied from the supply unit 5 is in a liquefied state, the heating load in the regeneration tower 4 can be reduced. Specifically, the regeneration tower 4 is normally capable of heating the rich liquid E1 to the temperature necessary to release ammonia from the rich liquid E1 in order to heat the rich liquid E1 as well. However, the temperature required to vaporize the gas to be treated G1 (ammonia) is lower than the temperature required to release ammonia from the rich liquid E1. Therefore, by applying the supply vaporizer 21, the heating load in the regeneration tower 4 can be reduced. In other words, the consumption of heating medium such as steam in the reboiler 14 can be reduced.
[0052] In particular, when the pressure inside the ammonia decomposition reactor 2 is higher than the pressure inside the regeneration tower 4, it is necessary to pressurize the gas to be treated G1 and send it to the regeneration tower 4. In this case, pressurizing the liquefied gas to be treated G1 with a pump is more power-efficient than pressurizing the gaseous gas to be treated G1 with a compressor. In such cases, with the ammonia decomposition system 1A of the second embodiment, the ammonia can be vaporized in the supply vaporizer 21 after being pressurized with a pump, thus efficiently reducing the water content of the ammonia.
[0053] <Third Embodiment> Next, the ammonia decomposition system 1B of the third embodiment according to the present disclosure will be described. In the third embodiment described below, components common to the first and second embodiments are denoted by the same reference numerals in the figures and their descriptions are omitted. The ammonia decomposition system 1B of the third embodiment differs from the second embodiment in that it has a structure that allows adjustment of the gas flow through the regeneration tower exhaust gas supply line L5.
[0054] As shown in Figure 3, the ammonia decomposition system 1B of the third embodiment further comprises a flow rate acquisition unit 31 and an adjustment control valve 32.
[0055] (Flow Rate Acquisition Unit) The flow rate acquisition unit 31 acquires information on the flow rate of liquid ammonia E4 stored inside the reflux drum 7. The flow rate acquisition unit 31 is, for example, a liquid level gauge fixed to the reflux drum 7. Examples of liquid level gauges include ultrasonic liquid level gauges, capacitive liquid level gauges, optical fiber liquid level gauges, and contact type liquid level gauges. In this embodiment, the flow rate acquisition unit 31 measures the liquid level of liquid ammonia E4 inside the reflux drum 7 and outputs the measured position information to the control valve.
[0056] (Adjustment Control Valve) The adjustment control valve 32 is located in the regeneration tower exhaust gas supply line L5. The adjustment control valve 32 is a solenoid valve whose opening degree can be adjusted based on the flow rate information acquired by the flow rate acquisition unit 31. Therefore, the adjustment control valve 32 can adjust the flow rate of the gas flowing through the regeneration tower exhaust gas supply line L5 based on the flow rate information acquired by the flow rate acquisition unit 31. For example, if the flow rate information falls below a predetermined standard, the adjustment control valve 32 is opened to a smaller degree so that the flow rate of gas that can pass through the regeneration tower exhaust gas supply line L5 is reduced. On the other hand, when the flow rate information is above a predetermined standard, the adjustment control valve 32 is opened to a larger degree so that the regeneration tower exhaust gas supply line L5 is fully opened during normal operation of the ammonia decomposition system 1B. The predetermined standard is, for example, the amount of liquid ammonia E4 stored in the reflux drum 7 that allows the reflux pump 8 to supply only liquid ammonia E4 that is not mixed with gas. The adjustment control valve 32 is adjusted based on whether the flow rate information obtained from the flow rate acquisition unit 31 via a control device (not shown) is below a standard.
[0057] Furthermore, in the condenser 6B of the third embodiment, the entire amount of regenerative tower exhaust gas G4 supplied is condensed into regenerative tower effluent E3. Specifically, the flow rate of the cooling water supplied to the condenser 6B is kept constant, and the regenerative tower exhaust gas G4 sent to the condenser 6B is completely condensed.
[0058] (Effects) If the amount of liquid ammonia E4 stored in the reflux drum 7 becomes too low, there is a possibility that the separated exhaust gas G5 will mix with the liquid ammonia E4 that is returned to the regeneration tower 4 via the reflux line L3. If the separated exhaust gas G5 is mixed in, it will also be sent to the regeneration tower 4 when the reflux pump 8 pressurizes it. As a result, liquids and gases will be supplied to the regeneration tower 4 from the reflux line L3 in a mixed state, which may cause the operation of the regeneration tower 4 to become unstable.
[0059] However, in this third embodiment of the ammonia decomposition system 1B, the adjustment unit 41 acquires the liquid level of the liquid ammonia E4 stored inside the reflux drum 7. Therefore, the adjustment unit 41 acquires information on the flow rate of the liquid ammonia E4 stored in the reflux drum 7. When the acquired information on the flow rate of liquid ammonia E4 falls below a predetermined standard, the opening of the adjustment control is reduced. As a result, when the amount of liquid ammonia E4 stored in the reflux drum 7 falls below the standard, the flow rate of the regenerator exhaust gas G4 circulating in the regenerator exhaust gas supply line L5 is reduced, and the flow rate of the regenerator exhaust gas G4 sent to the condenser 6B is increased. Therefore, a large amount of regenerator exhaust liquid E3 is supplied to the reflux drum 7, and the flow rate of liquid ammonia E4 stored in the reflux drum 7 can be increased to above the standard. As a result, it is possible to suppress the supply of a mixture of liquid and gas from the reflux line L3 to the regenerator 4. This enables stable operation of the regenerator 4.
[0060] Furthermore, in the condenser 6B of the third embodiment, the entire amount of regenerative tower exhaust gas G4 supplied is condensed into regenerative tower discharge liquid E3 in the condenser 6B, so the flow rate (liquid level) of the reflux drum 7 can be adjusted by the amount of regenerative tower exhaust gas G4 supplied to the condenser 6B. Therefore, the flow rate of the reflux drum 7 can be directly adjusted by adjusting the flow rate of the gas flowing through the regenerative tower exhaust gas supply line L5 using the adjustment control valve 32, thereby adjusting the amount of regenerative tower exhaust gas G4 supplied to the condenser 6B. Consequently, the controllability of the adjustment control valve 32 can be stabilized.
[0061] <Fourth Embodiment> Next, the ammonia decomposition system 1C of the fourth embodiment according to the present disclosure will be described. In the fourth embodiment described below, components common to the first to third embodiments are denoted by the same reference numerals in the figures and their descriptions are omitted. The ammonia decomposition system 1C of the fourth embodiment differs from the first to third embodiments in that it has a structure that allows adjustment of the heating state inside the regeneration tower 4.
[0062] As shown in Figure 4, the ammonia decomposition system 1C of the fourth embodiment further comprises a flow rate acquisition unit 31 and an adjustment unit 41.
[0063] (Adjustment Unit) The adjustment unit 41 is capable of adjusting the heating temperature inside the regeneration tower 4 based on the flow rate information acquired by the flow rate acquisition unit 31. The adjustment unit 41 in this embodiment is a solenoid valve capable of adjusting the flow rate of steam supplied to the reboiler 14. The adjustment unit 41 is capable of adjusting the opening degree based on the flow rate information acquired by the flow rate acquisition unit 31. Therefore, the adjustment unit 41 is capable of adjusting the amount of steam supplied to the reboiler 14 based on the flow rate information acquired by the flow rate acquisition unit 31. For example, when the flow rate information falls below a predetermined standard, the adjustment unit 41 is opened to increase the amount of steam supplied to the reboiler 14. As a result, the temperature of the lean liquid E2 heated by the reboiler 14 to heat the regeneration tower 4 rises, and the heating temperature of the regeneration tower 4 rises. On the other hand, when the flow rate information is above a predetermined standard, the adjustment unit 41 is opened to decrease the amount of steam supplied to the reboiler 14 during normal operation of the ammonia decomposition system 1C. As a result, the temperature of the lean liquid E2 heated in the reboiler 14 to heat the regeneration tower 4 decreases, and the heating temperature of the regeneration tower 4 is reduced.
[0064] (Effects) According to the ammonia decomposition system 1C of this fourth embodiment, the heating temperature inside the regeneration tower 4 is adjusted based on the flow rate information of liquid ammonia E4 obtained by the adjustment unit 41. Specifically, when the obtained information on the flow rate of liquid ammonia E4 falls below a predetermined standard, the flow rate of steam supplied to the reboiler 14 is increased. As a result, when the amount of liquid ammonia E4 stored in the reflux drum 7 falls below the standard, the heating temperature in the regeneration tower 4 is raised, and the amount of regeneration tower exhaust gas G4 discharged from the regeneration tower 4 increases. As a result, the flow rate of regeneration tower exhaust gas G4 sent to the condensers 6 and 6B can be increased. Therefore, a large amount of regeneration tower discharge liquid E3 is supplied to the reflux drum 7, and the flow rate of liquid ammonia E4 stored in the reflux drum 7 can be increased to above the standard. As a result, it is possible to suppress the supply of liquid and gas mixtures from the reflux line L3 to the regeneration tower 4. This enables stable operation of the regeneration tower 4.
[0065] <Fifth Embodiment> Next, the ammonia decomposition system 1D of the fifth embodiment according to the present disclosure will be described. In the fifth embodiment described below, components common to the first to fourth embodiments are denoted by the same reference numerals in the figures and their descriptions are omitted. As shown in Figure 5, the ammonia decomposition system 1D of the fifth embodiment differs from the first to fourth embodiments in that it has a structure that supplies a portion of the liquid ammonia E4 to the ammonia decomposition reactor 2.
[0066] The ammonia decomposition system 1D further comprises a partial liquid ammonia circulation line L51 and a vaporizer 52. Furthermore, the ammonia decomposition system 1D does not have a regeneration tower exhaust gas supply line L5.
[0067] (Partial Liquid Ammonia Circulation Line) The partial liquid ammonia circulation line L51 supplies a portion of the liquid ammonia E4 to the ammonia decomposition reactor 2. The partial liquid ammonia circulation line L51 vaporizes a portion of the liquid ammonia E4 before it is pressurized by the reflux pump 8 and merges it with the gas flowing through the reactor supply line L4 before it is supplied to the supply heat exchanger 9. The partial liquid ammonia circulation line L51 is a pipe that connects reflux line L3 to reflux line L3. The partial liquid ammonia circulation line L51 is connected to reflux line L3 between reflux drum 7 and reflux pump 8. The partial liquid ammonia circulation line L51 is connected to reactor supply line L4 between reflux drum 7 and supply heat exchanger 9.
[0068] (Vaporizer) The vaporizer 52 vaporizes liquid ammonia E4 and supplies it to the regeneration tower 4. High-temperature steam is supplied to the vaporizer 52. In the vaporizer 52, heat exchange occurs between the steam and the liquid ammonia E4, heating and vaporizing the liquid ammonia E4. The vaporizer 52 is located in the middle of the partial liquid ammonia circulation line L51. As a result, a portion of the liquid ammonia E4 is heated in the vaporizer 52 and supplied to the reactor supply line L4. In other words, a portion of the liquid ammonia E4 is vaporized and supplied to the ammonia decomposition reactor 2.
[0069] (Effects) In this fifth embodiment of the ammonia decomposition system 1D, the gas to be treated G1 can be heated using the regeneration tower 4, similar to the first embodiment. Therefore, water contained in the gas to be treated G1 can be removed, and a gas with a high ammonia concentration can be supplied to the ammonia decomposition reactor 2. In other words, a gas with reduced water content that does not contribute to the decomposition reaction in the ammonia decomposition reactor 2 can be supplied to the ammonia decomposition reactor 2. Furthermore, by using the regeneration tower 4, which heats the rich liquid E1, to heat the gas to be treated G1, there is no need to add equipment for heating the gas to be treated G1. Therefore, the number of additional equipment and piping connecting the equipment can be reduced. As a result, the water content of ammonia can be reduced without adding any additional equipment.
[0070] (Other Embodiments) Although embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of the present disclosure.
[0071] For example, the ammonia decomposition systems 1, 1A, 1B, 1C, and 1D are not limited to structures having only the configurations described in the embodiments above. Specifically, each pipe (line) may be equipped with a heat exchanger or other equipment such as a pump or compressor, as needed.
[0072] Furthermore, the structure for heating the regeneration tower 4 is not limited to a steam-powered reboiler 14. For example, the structure for heating the regeneration tower 4 may be a heat exchanger or heater that uses a high-temperature heating medium instead of steam.
[0073] Furthermore, each embodiment may be implemented in any combination. For example, as a modified ammonia decomposition system 1E of the fifth embodiment, the supply vaporizer 21 of the second embodiment may be combined with the fifth embodiment, as shown in Figure 6. With such a modified ammonia decomposition system 1E, the fifth embodiment can be given the functions of the second embodiment.
[0074] <Note> The ammonia decomposition systems 1, 1A, 1B, 1C, 1D, and 1E described in each embodiment can be understood, for example, as follows.
[0075] (1) The ammonia decomposition systems 1, 1A, 1B, and 1C according to the first embodiment include: an ammonia decomposition reactor 2 capable of decomposing ammonia contained in a gas to be treated G1 into nitrogen and hydrogen, and discharging a decomposition gas G2 containing the nitrogen, the hydrogen and undecomposed ammonia; an absorption tower 3 into which the decomposition gas G2 is introduced from the ammonia decomposition reactor 2, and the decomposition gas G2 is brought into contact with an absorbent liquid, and an absorption tower exhaust gas G3 is discharged which contains the absorbent liquid that has absorbed the ammonia contained in the decomposition gas G2 and the nitrogen and hydrogen remaining after the ammonia has been removed; a regeneration tower 4 which heats the absorbent liquid discharged from the absorption tower 3 to release the ammonia, and discharges the absorbent liquid from which the ammonia has been released and a regeneration tower exhaust gas G4 containing the ammonia; and the regeneration tower exhaust gas discharged from the regeneration tower 4 The regeneration tower 4 includes condensers 6 and 6B that condense the absorbent liquid G4 by cooling it, a reflux drum 7 that discharges separated exhaust gas G5, from which condensed liquid ammonia has been separated from the regeneration tower exhaust gas G4 condensed in the condensers 6 and 6B, and supplies it to the ammonia decomposition reactor 2, and also supplies the separated liquid ammonia E4 to the regeneration tower 4, a supply line L1 that supplies the gas to be treated G1 containing ammonia to the regeneration tower 4, and a regeneration tower exhaust gas supply line L5 that supplies a portion of the regeneration tower exhaust gas G4 to the ammonia decomposition reactor 2 before supplying it to the condensers 6 and 6B, wherein the regeneration tower 4 is capable of heating the absorbent liquid and the gas to be treated G1, and the regeneration tower exhaust gas supply line L5 supplies the regeneration tower exhaust gas G4 and a portion of the heated gas to be treated G1 to the ammonia decomposition reactor 2.
[0076] With this configuration, the regeneration tower 4 can be used to heat the gas G1 to be treated. Therefore, water contained in the gas G1 to be treated can be removed, and a gas with a high concentration of ammonia can be supplied to the ammonia decomposition reactor 2. In other words, a gas with reduced water content that does not contribute to the decomposition reaction in the ammonia decomposition reactor 2 can be supplied to the ammonia decomposition reactor 2. Furthermore, by using the regeneration tower 4, which heats the absorption liquid, to heat the gas G1 to be treated, there is no need to add equipment to heat the gas G1 to be treated. Therefore, the number of additional pieces of equipment and the number of pipes connecting them can be reduced. As a result, the water content of ammonia can be reduced without adding any additional equipment.
[0077] Furthermore, before supplying the treated gas G1 heated in the regeneration tower 4 to the condensers 6 and 6B, it is supplied from the regeneration tower exhaust gas supply line L5 to the reactor supply line L4 and then sent to the ammonia decomposition reactor 2. As a result, the flow rate of the regeneration tower exhaust gas G4 supplied to the condensers 6 and 6B is reduced. Consequently, the flow rate of the cooling water used to cool the regeneration tower exhaust gas G4 in the condensers 6 and 6B can be reduced.
[0078] (2) The ammonia decomposition systems 1, 1A, 1B, 1C according to the second embodiment are the ammonia decomposition systems 1, 1A, 1B, 1C of (1), further comprising a reactor supply line L4 that supplies the separated exhaust gas G5 discharged from the reflux drum 7 to the ammonia decomposition reactor 2, and the regeneration tower exhaust gas supply line L5 is connected to the reactor supply line L4.
[0079] With this configuration, the separated exhaust gas G5 recovered in the reflux drum 7 can be supplied to the ammonia decomposition reactor 2 together with the regeneration tower exhaust gas G4 containing the heated gas to be treated G1. Therefore, most of the ammonia contained in the gas discharged from the regeneration tower 4 can be supplied to the ammonia decomposition reactor 2.
[0080] (3) The ammonia decomposition system 1A according to the third embodiment is the ammonia decomposition system 1, 1A, 1B, 1C of (1) or (2), further comprising a supply vaporizer 21 arranged in the supply line L1 and vaporizing the gas to be treated G1 flowing through the supply line L1.
[0081] With this configuration, even if the gas G1 to be processed supplied from the supply unit 5 is in a liquefied state, the heating load on the regeneration tower 4 can be reduced.
[0082] (4) The ammonia decomposition system 1B according to the fourth embodiment is any one of the ammonia decomposition systems 1, 1A, 1B, 1C of (1) to (3), comprising: a flow rate acquisition unit 31 that acquires information on the flow rate of the liquid ammonia E4 stored inside the reflux drum 7; and an adjustment control valve 32 arranged in the regeneration tower exhaust gas supply line L5, which can adjust its opening degree based on the flow rate information acquired by the flow rate acquisition unit 31, wherein the opening degree of the adjustment control valve 32 is reduced when the flow rate information falls below a predetermined standard.
[0083] With this configuration, if the amount of liquid ammonia E4 stored in the reflux drum 7 falls below the standard, the flow rate of regenerator exhaust gas G4 circulating in the regenerator exhaust gas supply line L5 can be reduced, and the flow rate of regenerator exhaust gas G4 sent to the condensers 6 and 6B can be increased. As a result, a large amount of condensed regenerator exhaust gas G4 is supplied to the reflux drum 7, increasing the flow rate of liquid ammonia E4 stored in the reflux drum 7 to above the standard. Consequently, it is possible to prevent liquid and gas mixtures from being supplied to the regenerator 4 from the reflux line L3. This enables stable operation of the regenerator 4.
[0084] (5) The ammonia decomposition system 1C according to the fifth embodiment is any one of the ammonia decomposition systems 1, 1A, 1B, 1C, 1D, 1E from (1) to (4), comprising a flow rate acquisition unit 31 that acquires information on the flow rate of the liquid ammonia E4 stored inside the reflux drum 7, and an adjustment unit 41 that can adjust the heating temperature inside the regeneration tower 4 based on the flow rate information acquired by the flow rate acquisition unit 31, wherein the adjustment unit 41 raises the heating temperature when the flow rate information falls below a predetermined standard.
[0085] With this configuration, if the amount of liquid ammonia E4 stored in the reflux drum 7 falls below the standard, the heating temperature in the regeneration tower 4 is increased, and the amount of regeneration tower exhaust gas G4 discharged from the regeneration tower 4 increases. As a result, the flow rate of regeneration tower exhaust gas G4 sent to the condensers 6 and 6B can be increased. Therefore, a large amount of regeneration tower effluent E3 is supplied to the reflux drum 7, increasing the flow rate of liquid ammonia E4 stored in the reflux drum 7 to above the standard. As a result, it is possible to suppress the supply of a mixture of liquid and gas from the reflux line L3 to the regeneration tower 4. This enables stable operation of the regeneration tower 4.
[0086] (6) The ammonia decomposition systems 1D and 1E according to the sixth embodiment include: an ammonia decomposition reactor 2 capable of decomposing ammonia contained in a gas to be treated G1 into nitrogen and hydrogen, and discharging a decomposition gas G2 containing the nitrogen, the hydrogen and undecomposed ammonia; an absorption tower 3 into which the decomposition gas G2 is introduced from the ammonia decomposition reactor 2, and the decomposition gas G2 is brought into contact with an absorbent liquid, and an absorption tower exhaust gas G3 is discharged which contains the absorbent liquid that has absorbed the ammonia contained in the decomposition gas G2 and the nitrogen and hydrogen remaining after the ammonia has been removed; a regeneration tower 4 which heats the absorbent liquid discharged from the absorption tower 3 to release the ammonia, and discharges the absorbent liquid from which the ammonia has been released and a regeneration tower exhaust gas G4 containing the ammonia; and the regeneration tower exhaust gas G The regeneration tower 4 comprises condensers 6 and 6B that cool 4 to condense it into regeneration tower discharge liquid E3, a reflux drum 7 that discharges separated exhaust gas G5, from which liquid ammonia E4 has been separated from the regeneration tower discharge liquid E3 condensed in the condensers 6 and 6B, and supplies it to the ammonia decomposition reactor 2, and also supplies the separated liquid ammonia E4 to the regeneration tower 4, a supply line L1 that supplies the gas to be treated G1 containing ammonia to the regeneration tower 4, a partial liquid ammonia circulation line L51 that supplies a portion of the liquid ammonia E4 to the ammonia decomposition reactor 2, and a vaporizer 52 that is located in the partial liquid ammonia circulation line L51 and vaporizes the liquid ammonia E4 flowing through the partial liquid ammonia circulation line L51, and the regeneration tower 4 is capable of heating the absorbent liquid and the gas to be treated G1.
[0087] With this configuration, water contained in the gas G1 to be treated can be removed, and a gas with a high concentration of ammonia can be supplied to the ammonia decomposition reactor 2. In other words, a gas with reduced water content that does not contribute to the decomposition reaction in the ammonia decomposition reactor 2 can be supplied to the ammonia decomposition reactor 2. Furthermore, by using the regeneration tower 4, which heats the absorption liquid, to heat the gas G1 to be treated, there is no need to add equipment to heat the gas G1 to be treated. Therefore, the number of additional pieces of equipment and the number of pipes connecting them can be reduced. As a result, the water content of ammonia can be reduced without adding any additional equipment.
[0088] (7) The ammonia decomposition system 1E according to the seventh embodiment is the ammonia decomposition system 1D, 1E of (6), further comprising a supply vaporizer 21 arranged in the supply line L1 and vaporizing the gas to be treated G1 flowing through the supply line L1.
[0089] According to the ammonia decomposition system of this disclosure, the water content of ammonia can be reduced without adding any additional equipment.
[0090] 1, 1A, 1B, 1C, 1D, 1E Ammonia Decomposition System 2 Ammonia Decomposition Reactor 3 Absorption Tower 4 Regeneration Tower 5 Supply Section L1 Supply Line L2 Regeneration Tower Exhaust Gas Line 6, 6B Condenser 7 Reflux Drum L3 Reflux Line 8 Reflux Pump L4 Reactor Supply Line L5 Regeneration Tower Exhaust Gas Supply Line L6 Reactor Discharge Line 9 Supply Heat Exchanger 10 Decomposition Gas Cooler L7 Rich Line 11 Rich Pump L8 Lean Line 12 Absorption Liquid Heat Exchanger 13 Lean Cooler L9 Regeneration Tower Heating Line 14 Reboiler G1 Gas to be Treated G2 Decomposition Gas G3 Absorption Tower Exhaust Gas G4 Regeneration Tower Exhaust Gas G5 Separation Exhaust Gas E1 Rich Liquid E2 Lean Liquid E3 Regeneration Tower Discharge Liquid E4 Liquid Ammonia 21 Supply vaporizer 31 Flow rate acquisition unit 32 Adjustment control valve 41 Adjustment unit L51 Partial liquid ammonia circulation line 52 Vaporizer
Claims
1. An ammonia decomposition reactor capable of decomposing ammonia contained in the gas to be treated into nitrogen and hydrogen, and discharging a decomposition gas containing the nitrogen, the hydrogen and undecomposed ammonia; an absorption tower into which the decomposition gas is introduced from the ammonia decomposition reactor, bringing the decomposition gas into contact with an absorbent, and discharging an absorbent that has absorbed the ammonia contained in the decomposition gas, and an absorption tower exhaust gas from which the ammonia has been removed and nitrogen and hydrogen remain; a regeneration tower that heats the absorbent discharged from the absorption tower to release the ammonia, and discharges the absorbent from which the ammonia has been released and a regeneration tower exhaust gas containing the ammonia; a condenser that cools the regeneration tower exhaust gas discharged from the regeneration tower to condense it; a reflux drum that discharges a separated exhaust gas from which condensed liquid ammonia has been separated from the regeneration tower exhaust gas condensed in the condenser and supplies it to the ammonia decomposition reactor, and supplies the separated liquid ammonia to the regeneration tower; and a supply line that supplies the gas to be treated containing ammonia to the regeneration tower. The ammonia decomposition system comprises a regeneration tower exhaust gas supply line that supplies a portion of the regeneration tower exhaust gas to the ammonia decomposition reactor before supplying it to the condenser, the regeneration tower being capable of heating the absorbent liquid and the gas to be treated, and the regeneration tower exhaust gas supply line supplying the regeneration tower exhaust gas and a portion of the heated gas to be treated to the ammonia decomposition reactor.
2. The ammonia decomposition system according to claim 1, further comprising a reactor supply line for supplying the separated exhaust gas discharged from the reflux drum to the ammonia decomposition reactor, wherein the regenerator exhaust gas supply line is connected to the reactor supply line.
3. The ammonia decomposition system according to claim 1 or 2, further comprising a supply vaporizer arranged in the supply line for vaporizing the gas to be treated that flows through the supply line.
4. The ammonia decomposition system according to claim 1 or 2, comprising: a flow rate acquisition unit that acquires information on the flow rate of the liquid ammonia stored inside the reflux drum; and an adjustment control valve arranged in the regeneration tower exhaust gas supply line and capable of adjusting its opening degree based on the flow rate information acquired by the flow rate acquisition unit, wherein the adjustment control valve reduces its opening degree when the flow rate information falls below a predetermined standard.
5. The ammonia decomposition system according to claim 1 or 2, comprising: a flow rate acquisition unit that acquires information on the flow rate of the liquid ammonia stored inside the reflux drum; and an adjustment unit that can adjust the heating temperature inside the regeneration tower based on the flow rate information acquired by the flow rate acquisition unit, wherein the adjustment unit raises the heating temperature when the flow rate information falls below a predetermined standard.
6. An ammonia decomposition reactor capable of decomposing ammonia contained in the gas to be treated into nitrogen and hydrogen, and discharging a decomposition gas containing the nitrogen, the hydrogen and undecomposed ammonia; an absorption tower into which the decomposition gas is introduced from the ammonia decomposition reactor, bringing the decomposition gas into contact with an absorbent, and discharging an absorbent that has absorbed the ammonia contained in the decomposition gas, and an absorption tower exhaust gas from which the ammonia has been removed and nitrogen and hydrogen remain; a regeneration tower that heats the absorbent discharged from the absorption tower to release the ammonia, and discharges the absorbent from which the ammonia has been released and a regeneration tower exhaust gas containing the ammonia; a condenser that cools the regeneration tower exhaust gas discharged from the regeneration tower to condense it into a regeneration tower effluent; a reflux drum that discharges a separated exhaust gas from which condensed liquid ammonia has been separated from the regeneration tower effluent condensed in the condenser and supplies it to the ammonia decomposition reactor, and also supplies the separated liquid ammonia to the regeneration tower; and a supply line that supplies the gas to be treated containing ammonia to the regeneration tower. An ammonia decomposition system comprising: a partial liquid ammonia circulation line that supplies a portion of the liquid ammonia to the ammonia decomposition reactor; and a vaporizer located in the partial liquid ammonia circulation line that vaporizes the liquid ammonia flowing through the partial liquid ammonia circulation line, wherein the regeneration tower is capable of heating the absorbent liquid and the gas to be treated.
7. The ammonia decomposition system according to claim 5, further comprising a supply vaporizer arranged in the supply line for vaporizing the gas to be treated that flows through the supply line.