Ammonia vaporization facility

Abstract

This ammonia vaporization facility comprises: an ammonia vaporizer that vaporizes liquid ammonia; a liquid ammonia extraction unit that decompresses and extracts liquid ammonia accumulated in the ammonia vaporizer; an extracted liquid ammonia storage unit in which the liquid ammonia extracted from the liquid ammonia extraction unit is temporarily stored; a pressure adjustment unit that adjusts the pressure of the extracted liquid ammonia storage unit to a pressure lower than the pressure inside the ammonia vaporizer; and a liquid extraction pump that delivers the liquid ammonia stored in the extracted liquid ammonia storage unit.

Description

Ammonia Vaporization Facility

[0001] The present invention relates to an ammonia vaporization facility. The present application claims priority based on Japanese Patent Application No. 2025-049590 filed in Japan on March 25, 2025, the content of which is incorporated herein by reference.

[0002] For example, Patent Document 1 discloses a vaporizer including a shell and a supply unit that supplies liquefied gas into the shell. Further, the vaporizer disclosed in Patent Document 1 includes a liquid outflow unit that discharges liquefied gas accumulated in the shell.

[0003] Japanese Unexamined Patent Publication No. 2022-6152

[0004] When vaporizing liquid ammonia using a vaporizer such as that disclosed in Patent Document 1, it is conceivable to use a heat medium such as seawater or warm waste water to heat and gasify liquid ammonia while suppressing energy consumption.

[0005] In heat exchange between liquid ammonia and heat media such as seawater or warm waste water, it is difficult to evaporate all the moisture contained in liquid ammonia, and the moisture will be concentrated and remain inside the vaporizer. For this reason, it is necessary to drain liquid ammonia mixed with moisture out of the vaporizer using a drain pump or the like.

[0006] The pressure inside the vaporizer is the saturated vapor pressure. For this reason, the liquid ammonia handled by the drain pump is a saturated liquid. Therefore, in order to secure an effective suction head and prevent the occurrence of cavitation or the like, the drain pump is arranged at a position lower than the vaporizer. However, the ammonia gas delivery flow rate fluctuates based on load fluctuations of the supply destination and the like. For this reason, for example, when the gas delivery flow rate increases rapidly, the pressure inside the vaporizer temporarily decreases, which may cause cavitation or the like. To cope with such load fluctuations, countermeasures such as further deepening the pump pit are required, which is disadvantageous.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to make it possible to suppress the occurrence of cavitation in a drain pump in an ammonia vaporization facility capable of draining liquid ammonia accumulated in an ammonia vaporizer.

[0008] An ammonia vaporization apparatus according to one aspect of the present invention comprises: an ammonia vaporizer for vaporizing liquid ammonia; a liquid ammonia extraction unit for reducing the pressure and extracting the liquid ammonia accumulated in the ammonia vaporizer; an extracted liquid ammonia storage unit for temporarily storing the liquid ammonia extracted from the liquid ammonia extraction unit; a pressure adjustment unit for adjusting the pressure in the extracted liquid ammonia storage unit to a pressure lower than that inside the ammonia vaporizer; and a liquid extraction pump for discharging the liquid ammonia stored in the extracted liquid ammonia storage unit.

[0009] According to one aspect of the present invention, the pressure in the extracted liquid ammonia storage section is adjusted to be lower than that inside the ammonia vaporizer. Furthermore, the liquid ammonia accumulated in the ammonia vaporizer is reduced in pressure and supplied to the extracted liquid ammonia storage section. Therefore, even if the pressure inside the ammonia vaporizer fluctuates, the range of pressure fluctuations in the extracted liquid ammonia storage section is suppressed to be smaller than the range of pressure fluctuations inside the ammonia vaporizer. Consequently, the range of pressure fluctuations of liquid ammonia in the liquid extraction pump can be kept small. Thus, in an ammonia vaporization system capable of extracting liquid ammonia accumulated in the ammonia vaporizer, the occurrence of cavitation in the liquid extraction pump can be suppressed.

[0010] This is a schematic flowchart showing the general configuration of an ammonia vaporization facility in one embodiment of the present invention.

[0011] Hereinafter, an embodiment of the ammonia vaporization equipment according to the present invention will be described with reference to the drawings.

[0012] Figure 1 is a schematic flow diagram showing the general configuration of the ammonia vaporization equipment 1 of this embodiment. The ammonia vaporization equipment 1 of this embodiment is equipment that vaporizes liquid ammonia X stored in a low-temperature storage tank 100 to produce ammonia gas, and sends the ammonia gas to the customer. In this embodiment, the low-temperature storage tank 100 is described, but the tank is not limited to low-temperature storage. For example, a spherical tank may be used instead of the low-temperature storage tank 100.

[0013] The low-temperature storage tank 100 is, for example, a large double-shelled above-ground low-temperature tank with a total height of about 50 m. The double-shelled above-ground low-temperature tank comprises a metal inner tank (not shown) and a metal outer tank, and stores liquid ammonia X transferred from a tanker or the like inside the inner tank.

[0014] The low-temperature storage tank 100 may be an underground low-temperature tank. The storage temperature of the liquid ammonia X stored in the low-temperature storage tank 100 is, for example, around -33°C to -34°C. The liquid ammonia X stored in the low-temperature storage tank 100 also contains, for example, about 0.5 wt% water.

[0015] As shown in Figure 1, the ammonia vaporization equipment 1 of this embodiment comprises an ammonia vaporizer 2, a liquid ammonia supply unit 3, a liquid ammonia extraction unit 4, a side drum 5 (extracted liquid ammonia storage unit), a pressure adjustment unit 6, a drain pipe 7, a liquid extraction pump 8, and an extraction volume control valve 9.

[0016] The ammonia vaporizer 2 vaporizes the liquid ammonia X supplied from the liquid ammonia supply unit 3. Inside the ammonia vaporizer 2, there is a heat exchange tube (not shown) through which a heat transfer medium flows. The ammonia vaporizer 2 evaporates the liquid ammonia X into ammonia gas through heat exchange between the liquid ammonia X supplied from the liquid ammonia supply unit 3 and the heat transfer medium flowing through the heat exchange tube.

[0017] A gas supply pipe (not shown) is connected to the ammonia vaporizer 2. The ammonia gas produced in the ammonia vaporizer 2 is sent to the supply destination via the gas supply pipe. The gas supply pipe is connected to the top of the ammonia vaporizer 2.

[0018] Furthermore, the ammonia vaporizer 2 is supplied with liquid ammonia X that has been pressurized in the liquid ammonia supply unit 3. For this reason, the internal pressure of the ammonia vaporizer 2 is higher than the internal pressure of the low-temperature storage tank 100.

[0019] The liquid ammonia supply unit 3 supplies liquid ammonia X stored in the low-temperature storage tank 100 to the ammonia vaporizer 2. As shown in Figure 1, the liquid ammonia supply unit 3 includes a discharge pump 3a located inside the low-temperature storage tank 100 and a supply pipe 3b connecting the discharge pump 3a to the ammonia vaporizer 2.

[0020] The discharge pump 3a is a pump that discharges liquid ammonia X from the low-temperature storage tank 100. The discharge pump 3a pressurizes the liquid ammonia X stored in the low-temperature storage tank 100 and sends it to the supply pipe 3b. Note that the discharge pump 3a does not necessarily have to be located inside the low-temperature storage tank 100. The discharge pump 3a may be installed outside the low-temperature storage tank 100.

[0021] The supply pipe 3b is connected to the discharge pump 3a at its upstream end and to the ammonia vaporizer 2 at its downstream end. The downstream end of the supply pipe 3b is branched into two, and connected to the upper and lower parts of the ammonia vaporizer 2, respectively. However, the downstream end of the supply pipe 3b does not necessarily have to be branched.

[0022] Furthermore, the liquid ammonia supply unit 3 includes a flow control valve 3c installed in the middle of the upstream portion of the supply pipe 3b. The liquid ammonia supply unit 3 also includes an on-off valve 3d installed in the middle of the downstream portion of the supply pipe 3b that connects to the upper part of the ammonia vaporizer 2, and another on-off valve 3d installed in the middle of the downstream portion of the supply pipe 3b that connects to the lower part of the ammonia vaporizer 2.

[0023] The liquid ammonia supply unit 3 adjusts the opening degree of the flow control valve 3c based on a command from, for example, a higher-level control unit. The liquid ammonia supply unit 3 can adjust the flow rate of liquid ammonia X supplied from the low-temperature storage tank 100 to the ammonia vaporizer 2.

[0024] The liquid ammonia extraction unit 4 extracts liquid ammonia X from the ammonia vaporizer 2. The liquid ammonia extraction unit 4 extracts the liquid ammonia X accumulated in the ammonia vaporizer 2 from the ammonia vaporizer 2. The liquid ammonia X extracted by the liquid ammonia extraction unit 4 from the ammonia vaporizer 2 (i.e., the liquid ammonia X accumulated in the ammonia vaporizer 2) has a higher water concentration than the liquid ammonia X stored in the low-temperature storage tank 100.

[0025] In this embodiment, the liquid ammonia extraction unit 4 extracts the liquid ammonia X accumulated in the ammonia vaporizer 2 by reducing the pressure. As shown in Figure 1, the liquid ammonia extraction unit 4 comprises an extraction pipe 4a, a pressure reducing valve 4b, and a liquid level gauge 4c.

[0026] The extraction pipe 4a is a pipe that connects the ammonia vaporizer 2 and the side drum 5. The extraction pipe 4a is connected to the ammonia vaporizer 2 at a position that allows the liquid ammonia X accumulated inside the ammonia vaporizer 2 to be guided to the outside of the ammonia vaporizer 2. For example, the extraction pipe 4a may be connected to the bottom of the ammonia vaporizer 2.

[0027] The pressure reducing valve 4b is installed in the middle of the extraction pipe 4a. The pressure reducing valve 4b reduces the pressure of the liquid ammonia X flowing through the extraction pipe 4a. Specifically, the pressure reducing valve 4b reduces the pressure of the liquid ammonia X, which has been pressurized and supplied to the ammonia vaporizer 2, to the pressure inside the side drum 5.

[0028] The liquid level gauge 4c detects the liquid level of the liquid ammonia X accumulated in the ammonia vaporizer 2 and outputs a signal indicating the detection result. The liquid level gauge 4c is connected to the pressure reducing valve 4b. Based on the detection result input from the liquid level gauge 4c, the pressure reducing valve 4b adjusts its opening so that the liquid level of the liquid ammonia X accumulated in the ammonia vaporizer 2 is within a predetermined range.

[0029] The side drum 5 is a container in which liquid ammonia X extracted from the liquid ammonia extraction unit 4 is temporarily stored. The side drum 5 is connected to the extraction pipe 4a of the liquid ammonia extraction unit 4, and liquid ammonia X flowing through the extraction pipe 4a flows into it.

[0030] The pressure adjustment unit 6 adjusts the pressure in the side drum 5 to a pressure lower than the pressure inside the ammonia vaporizer 2. In this embodiment, the pressure adjustment unit 6 is connected to the boil-off gas guide pipe 101. The boil-off gas guide pipe 101 is connected to the upper part of the low-temperature storage tank 100 and is a pipe that guides the boil-off gas Y generated in the low-temperature storage tank 100. As shown in Figure 1, the pressure adjustment unit 6 includes a pressure adjustment pipe 6a, a pressure adjustment valve 6b, a liquid level gauge 6c, and a pressure gauge 6d. The boil-off gas Y is a gas generated when liquid ammonia X evaporates, and may be supplied to the gas supply pipe or compressed and returned to the low-temperature storage tank 100.

[0031] The pressure regulating pipe 6a is a pipe that connects the side drum 5 and the boil-off gas guide pipe 101. For example, the pressure regulating pipe 6a is connected to the top of the side drum 5 and directs some or all of the ammonia gas generated inside the side drum 5 toward the boil-off gas guide pipe 101.

[0032] The pressure adjustment pipe 6a connects the side drum 5 to the boil-off gas guide pipe 101, making it possible to reduce the pressure inside the side drum 5 to the pressure in the boil-off gas guide pipe 101. Furthermore, it becomes possible to process the ammonia gas generated inside the side drum 5 together with the boil-off gas Y, for example, enabling the effective utilization of the ammonia gas generated inside the side drum 5.

[0033] The pressure regulating valve 6b is installed in the middle of the pressure regulating pipe 6a. The pressure regulating valve 6b regulates the pressure inside the side drum 5 by adjusting the flow rate of ammonia gas that flows from the side drum 5 to the boil-off gas guide pipe 101.

[0034] The liquid level gauge 6c detects the liquid level of the liquid ammonia X accumulated in the side drum 5 and outputs a signal indicating the detection result. The pressure gauge 6d is connected to the same outlet nozzle as the liquid level gauge 6c and detects the pressure of the gas layer in the side drum 5 and outputs a signal indicating the detection result. The pressure gauge 6d is connected to the pressure regulating valve 6b. The pressure regulating valve 6b adjusts its opening degree based on the detection result input from the pressure gauge 6d.

[0035] The drain pipe 7 is connected to the side drum 5 and is the pipe through which liquid ammonia X discharged from the side drum 5 flows. The drain pipe 7 is connected to, for example, a forced vaporization device (not shown). The liquid ammonia X flowing through the drain pipe 7 and supplied to the forced vaporization device is heated to a higher temperature than, for example, the ammonia vaporizer 2, and vaporized together with the water it contains. This generates ammonia gas containing water vapor. The drain pipe 7 is connected to, for example, a gas supply pipe, and the ammonia gas containing water vapor is mixed with the ammonia gas flowing through the gas supply pipe and supplied to the destination.

[0036] The drain pump 8 is installed in the middle of the drainage piping 7. The drain pump 8 sucks in the liquid ammonia X from the side drum 5 and discharges it toward the opposite side of the side drum 5 so that the liquid ammonia X is extracted from the side drum 5. In other words, the drain pump 8 delivers the liquid ammonia X stored in the side drum 5.

[0037] The extraction volume control valve 9 is installed downstream of the liquid drain pump 8, in the middle of the drain pipe 7. The extraction volume control valve 9 adjusts the flow rate of liquid ammonia X that the liquid drain pump 8 extracts from the side drum 5. The extraction volume control valve 9 is connected to the liquid level gauge 6c, and adjusts its opening degree based on the detection result input from the liquid level gauge 6c. By adjusting the opening degree of the extraction volume control valve 9, it is possible to adjust the liquid level in the ammonia vaporizer 2 in addition to adjusting the liquid level in the side drum 5.

[0038] In the ammonia vaporization equipment 1 of this embodiment, liquid ammonia X is supplied from the liquid ammonia supply unit 3 to the ammonia vaporizer 2. The liquid ammonia X supplied to the ammonia vaporizer 2 is vaporized in the ammonia vaporizer 2 to become ammonia gas. The ammonia gas is sent from the ammonia vaporizer 2 to the destination via a gas supply pipe (not shown).

[0039] Furthermore, liquid ammonia X containing water accumulates in the ammonia vaporizer 2. When the liquid drain pump 8 is activated, the liquid ammonia X accumulated in the ammonia vaporizer 2 flows through the side drum 5 into the drain pipe 7, and is then supplied to the forced vaporization device where it is vaporized.

[0040] In this embodiment of the ammonia vaporization equipment 1, the pressure in the side drum 5 is adjusted to be lower than that in the ammonia vaporizer 2 by the pressure adjustment unit 6. The liquid ammonia X accumulated in the ammonia vaporizer 2 is depressurized by the pressure reducing valve 4b and then supplied to the side drum 5.

[0041] In the ammonia vaporization equipment 1 of this embodiment, when the pressure of the ammonia vaporizer 2 fluctuates due to load fluctuations at the supply destination, the pressure of the side drum 5 also changes at a similar rate to that of the ammonia vaporizer 2. However, since the pressure of the side drum 5 is kept lower than that of the ammonia vaporizer 2, the range of pressure fluctuation in the side drum 5 is smaller compared to the range of pressure fluctuation in the ammonia vaporizer 2. Therefore, the range of pressure fluctuations in the supply pressure to the drain pump 8 due to load fluctuations at the supply destination is suppressed to a smaller extent compared to the case where the drain pump 8 is directly connected to the ammonia vaporizer 2. For this reason, the ammonia vaporization equipment 1 of this embodiment can suppress cavitation and the like in the drain pump 8 without increasing the liquid head pressure.

[0042] As described above, the ammonia vaporization facility 1 of the present embodiment includes an ammonia vaporizer 2, a liquid ammonia extraction unit 4, a side drum 5, a pressure adjustment unit 6, and a drainage pump 8. The ammonia vaporizer 2 vaporizes liquid ammonia X. The liquid ammonia extraction unit 4 depressurizes and extracts liquid ammonia X accumulated in the ammonia vaporizer 2. The side drum 5 temporarily stores liquid ammonia X extracted from the liquid ammonia extraction unit 4. The pressure adjustment unit 6 adjusts the pressure inside the side drum to a pressure lower than that inside the ammonia vaporizer 2. The drainage pump 8 delivers liquid ammonia X stored in the side drum 5.

[0043] According to the ammonia vaporization facility 1 of the present embodiment, the pressure of the side drum 5 is adjusted to be lower than the internal pressure of the ammonia vaporizer 2. Further, liquid ammonia X accumulated in the ammonia vaporizer 2 is depressurized and supplied to the side drum 5. Therefore, even when the internal pressure of the ammonia vaporizer 2 fluctuates, the range of pressure fluctuation in the side drum 5 is suppressed to be smaller than the range of pressure fluctuation inside the ammonia vaporizer 2. Therefore, according to the ammonia vaporization facility 1 of the present embodiment, the fluctuation range of the pressure of liquid ammonia X in the drainage pump 8 can be kept small. Accordingly, in the ammonia vaporization facility capable of extracting liquid ammonia X accumulated in the ammonia vaporizer 2, the ammonia vaporization facility 1 of the present embodiment can suppress the occurrence of cavitation in the drainage pump 8.

[0044] Further, in the ammonia vaporization facility 1 of the present embodiment, the liquid ammonia extraction unit 4 includes an extraction pipe 4a and a pressure reducing valve 4b. The extraction pipe 4a connects the ammonia vaporizer 2 and the side drum 5. The pressure reducing valve 4b is installed at an intermediate position of the extraction pipe 4a.

[0045] According to the ammonia vaporization facility 1 of the present embodiment, by adjusting the opening degree of the pressure reducing valve 4b, the pressure of liquid ammonia X extracted from the ammonia vaporizer 2 can be easily adjusted to match the pressure of the side drum 5.

[0046] Furthermore, in the ammonia vaporization facility 1 of the present embodiment, the pressure adjusting unit 6 is connected to a boil-off gas guide pipe 101. The boil-off gas guide pipe 101 is a pipe connected to a low-temperature storage tank 100 and guides boil-off gas Y. The low-temperature storage tank 100 is a tank that stores liquid ammonia X to be supplied to the ammonia vaporizer 2.

[0047] According to the ammonia vaporization facility 1 of the present embodiment, the pressure adjusting unit 6 can easily reduce the pressure of the side drum 5 to the pressure of the boil-off gas guide pipe 101. Furthermore, the ammonia vaporization facility 1 of the present embodiment can mix the ammonia gas generated in the side drum 5 into the boil-off gas Y, and can effectively utilize the ammonia gas generated in the side drum 5.

[0048] Furthermore, in the ammonia vaporization facility 1 of the present embodiment, the pressure adjusting unit 6 includes a pressure adjusting pipe 6a and a pressure adjusting valve 6b. The pressure adjusting pipe 6a connects the side drum 5 and the boil-off gas guide pipe 101. The pressure adjusting valve 6b is installed at an intermediate position of the pressure adjusting pipe 6a.

[0049] According to the ammonia vaporization facility 1 of the present embodiment, the pressure of the side drum 5 can be easily adjusted by adjusting the opening degree of the pressure adjusting valve 6b.

[0050] Hitherto, preferred embodiments of the present invention have been described with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to the above-described embodiments. The various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements and the like within a range that does not deviate from the spirit of the present invention.

[0051] For example, in the above embodiment, a configuration was described in which the pressure regulating unit 6 is connected to the boil-off gas guide pipe 101. However, the present invention is not limited thereto. For example, the pressure regulating unit 6 only needs to be connected to a space with a lower pressure than the ammonia vaporizer 2, and may be connected to the internal space at the top of the low-temperature storage tank 100. Also, the pressure regulating unit 6 may be connected to other equipment such as a flare or denitrification equipment. This allows, for example, ammonia gas to be supplied to the denitrification equipment via the pressure regulating unit 6.

[0052] Furthermore, the above embodiments can also be described, for example, as shown in the following appendix.

[0053] (Note 1) An ammonia vaporization apparatus comprising: an ammonia vaporizer for vaporizing liquid ammonia; a liquid ammonia extraction unit for reducing the pressure and extracting the liquid ammonia accumulated in the ammonia vaporizer; an extracted liquid ammonia storage unit for temporarily storing the liquid ammonia extracted from the liquid ammonia extraction unit; a pressure adjustment unit for adjusting the pressure in the extracted liquid ammonia storage unit to a pressure lower than the pressure inside the ammonia vaporizer; and a liquid extraction pump for discharging the liquid ammonia stored in the extracted liquid ammonia storage unit.

[0054] (Note 2) The ammonia vaporization apparatus according to Note 1, wherein the liquid ammonia extraction unit comprises an extraction pipe connecting the ammonia vaporizer and the extracted liquid ammonia storage unit, and a pressure reducing valve installed in the middle of the extraction pipe.

[0055] (Note 3) The ammonia vaporization equipment according to Note 1 or 2, wherein the pressure regulating unit is connected to a low-temperature storage tank for storing the liquid ammonia supplied to the ammonia vaporizer and to a boil-off gas guide pipe for guiding the boil-off gas.

[0056] (Note 4) The ammonia vaporization apparatus as described in Note 3, wherein the pressure regulating unit comprises a pressure regulating pipe connecting the extracted liquid ammonia storage unit and the boil-off gas guide pipe, and a pressure regulating valve installed in the middle of the pressure regulating pipe.

[0057] According to the present invention, in an ammonia vaporization system capable of extracting liquid ammonia accumulated in an ammonia vaporizer, the generation of cavitation in the liquid extraction pump can be suppressed.

[0058] 1...Ammonia vaporization equipment, 2...Ammonia vaporizer, 3...Liquid ammonia supply unit, 3a...Discharge pump, 3b...Supply piping, 3c...Flow control valve, 3d...On / off valve, 4...Liquid ammonia extraction unit, 4a...Extraction piping, 4b...Pressure reducing valve, 4c...Liquid level gauge, 5...Side drum (extracted liquid ammonia storage unit), 6...Pressure regulating unit, 6a...Pressure regulating piping, 6b...Pressure regulating valve, 6c...Liquid level gauge, 7...Drainage piping, 8...Liquid extraction pump, 9...Extraction volume control valve, 100...Low temperature storage tank, 101...Boil-off gas guide piping, X...Liquid ammonia, Y...Boil-off gas

Claims

1. An ammonia vaporization system comprising: an ammonia vaporizer for vaporizing liquid ammonia; a liquid ammonia extraction unit for reducing the pressure and extracting the liquid ammonia accumulated in the ammonia vaporizer; an extracted liquid ammonia storage unit for temporarily storing the liquid ammonia extracted from the liquid ammonia extraction unit; a pressure regulating unit for adjusting the pressure in the extracted liquid ammonia storage unit to a pressure lower than that inside the ammonia vaporizer; and a liquid extraction pump for discharging the liquid ammonia stored in the extracted liquid ammonia storage unit.

2. The ammonia vaporization apparatus according to claim 1, wherein the liquid ammonia extraction unit comprises an extraction pipe connecting the ammonia vaporizer and the extracted liquid ammonia storage unit, and a pressure reducing valve installed in the middle of the extraction pipe.

3. The ammonia vaporization apparatus according to claim 1 or 2, wherein the pressure regulating unit is connected to a low-temperature storage tank for storing the liquid ammonia supplied to the ammonia vaporizer and is connected to a boil-off gas guide pipe for guiding the boil-off gas.

4. The ammonia vaporization apparatus according to claim 3, wherein the pressure regulating unit comprises a pressure regulating pipe connecting the extracted liquid ammonia storage unit and the boil-off gas guide pipe, and a pressure regulating valve installed in the middle of the pressure regulating pipe.

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