JP4854466B2 - Ammonia gas supply system, ammonia gas supply method, and ammonia gas supply program - Google Patents

Description

  The present invention relates to an ammonia gas supply system for supplying ammonia to a denitration apparatus, an ammonia gas supply method, and an ammonia gas supply program.

  The denitration device is installed and used in a thermal power plant. Thermal power plants generate electricity by burning oil or coal, but burning oil or coal generates nitrogen oxides. In order to prevent the environment from being affected, the exhaust gas containing nitrogen oxides is treated by a denitration device. In other words, an ammonia gas supply device that supplies ammonia gas is installed in the denitration device, and the denitration device adds nitrogen gas from the ammonia gas supply device to the exhaust gas containing nitrogen oxides and processes it, thereby oxidizing nitrogen. A thing is decomposed | disassembled into harmless nitrogen and water (for example, refer patent document 1).

When the supply of ammonia gas to the denitration device is stopped, exhaust gas containing nitrogen oxides from a thermal power plant or the like is released into the atmosphere, so the ammonia gas supply device includes a plurality of ammonia tanks that store liquid ammonia, When the remaining amount in the ammonia tank supplying liquid ammonia is reduced, this tank is switched to another ammonia tank.
JP 2001-286735 A

  By the way, in a thermal power plant or the like, each facility is regularly inspected, but the same applies to an ammonia gas supply device. At the time of regular inspection of, for example, an ammonia tank of the ammonia gas supply device, the ammonia tank to be inspected while supplying liquid ammonia is switched to another ammonia tank filled with liquid ammonia. At this time, if the liquid ammonia in the ammonia tank scheduled for inspection is used up and then switched to another ammonia tank, the supply of ammonia gas to the denitration device will be interrupted, so that liquid ammonia remains in the ammonia tank scheduled for inspection. The operation of switching the ammonia tank is performed.

  Since the worker enters the tank at the time of checking the ammonia tank, there arises a problem that an ammonia tank blowing operation of vaporizing and discharging the liquid ammonia remaining in the ammonia tank is required. Moreover, since liquid ammonia which can be used for exhaust gas treatment is discarded, there is a problem that the liquid ammonia remaining in the ammonia tank cannot be effectively used. Furthermore, since liquid ammonia is vaporized and discarded, there is a problem that it takes time to blow the ammonia tank and the work efficiency is poor.

  An object of the present invention is an ammonia gas supply system that solves the above-described problems and that allows the liquid ammonia in the ammonia tank to be used up without causing a supply stop of the ammonia gas when the ammonia tank is switched, To provide an ammonia gas supply method and an ammonia gas supply program.

  In order to solve the above problem, the invention of claim 1 includes a second valve that communicates with the outlet side of the first valve provided at the outlet of each of the plurality of ammonia tanks. In the ammonia gas supply system corresponding to each ammonia tank, the first valve of the one ammonia tank is provided with a supply system for supplying ammonia gas at a constant pressure by an accumulator after the liquid ammonia is vaporized When the level of liquid ammonia in the ammonia tank decreases, the pressure of the accumulator of one supply system corresponding to the ammonia tank is applied to the other ammonia tank. A second control that is set higher than the accumulator pressure of the corresponding other supply system, and the other supply system Opening the first valve ammonia tank being continued, ammonia gas supply system, characterized in that it comprises a control device that performs a third control to close the second valve.

  According to the first aspect of the present invention, a supply system is provided corresponding to the plurality of ammonia tanks. Further, after each supply system vaporizes liquid ammonia, the ammonia gas is supplied at a constant pressure by an accumulator. Further, the control device controls opening and closing of the first valve provided on the outlet side of the ammonia tank and opening and closing of the second valve connecting the outlet side of each first valve.

  That is, the control device opens the first valve and the second valve of one ammonia tank. Thereby, the liquid ammonia from an ammonia tank is supplied to two supply systems. Thereafter, when the level of liquid ammonia in the ammonia tank is lowered, the control device sets the pressure of the accumulator of one supply system corresponding to this ammonia tank to be higher than the pressure of the accumulator of the other supply system. Thereby, ammonia gas from a supply system provided with an accumulator having a high pressure set is supplied. In addition, since the first valve of the ammonia tank connected to the other supply system is opened, when the liquid ammonia corresponding to the supply system supplying ammonia gas disappears, the ammonia connected to the other supply system Supply of liquid ammonia from the tank begins.

  According to a second aspect of the present invention, in the ammonia gas supply system according to the first aspect, when the control device issues an alarm indicating that the one ammonia tank side indicates a low level of liquid ammonia, the level of the liquid ammonia in the ammonia tank It is characterized that it is judged that has fallen.

  According to a third aspect of the invention, in the ammonia gas supply system according to the first or second aspect, the control device performs control to temporarily increase the pressure of the accumulator of the other supply system after the second control. It is characterized by performing.

  According to a fourth aspect of the present invention, there is provided a second valve that communicates with the outlet side of the first valve provided at the outlet of each of the plurality of ammonia tanks, and after accumulating liquid ammonia from the first valve, the accumulator In the ammonia gas supply method using the ammonia gas supply system provided with a supply system for supplying ammonia gas at a constant pressure by the ammonia gas supply system, the first valve of the one ammonia tank is opened. When the second valve is opened and the level of liquid ammonia in the one ammonia tank decreases, the pressure in the accumulator of one supply system corresponding to the ammonia tank is changed to the other supply corresponding to the other ammonia tank. Set higher than the pressure of the accumulator of the system, and connected to the other supply system Opening the first valve Niatanku, ammonia gas supply method characterized by closing said second valve.

  The invention of claim 5 includes a second valve that communicates with the outlet side of the first valve provided at the outlet of each of the plurality of ammonia tanks, and after accumulating the liquid ammonia from the first valve, the accumulator This is an ammonia gas supply program for causing a computer to execute an ammonia gas supply method using an ammonia gas supply system provided with a supply system for supplying ammonia gas at a constant pressure in accordance with each ammonia tank. When the first valve of the one ammonia tank is opened and the second valve is opened, and when the level of liquid ammonia in the one ammonia tank decreases, one of the supply systems corresponding to the ammonia tank The pressure of the accumulator is changed to the accumulator of the other supply system corresponding to the other ammonia tank. The ammonia gas supply comprising: a process for setting the pressure higher than the pressure of the first tank; and a process for opening the first valve of the ammonia tank connected to the other supply system and closing the second valve. It is a program.

  According to the first, fourth, and fifth aspects of the invention, for example, when the ammonia tank is inspected, the liquid ammonia in the ammonia tank to be inspected can be used up. As a result, the liquid ammonia in the ammonia tank is effectively used to the end, and the work of vaporizing and discharging the liquid ammonia remaining in the ammonia tank is unnecessary, so the ammonia tank blow work is greatly shortened. It is possible to improve work efficiency. According to the first, fourth, and fifth aspects of the invention, when the liquid ammonia is used up, the liquid ammonia from another ammonia tank is supplied to the supply system and the supply of the ammonia gas is continued. It is possible to prevent the supply of ammonia gas from being interrupted.

  According to the invention of claim 2, when one of the ammonia tanks issues an alarm indicating a low level of liquid ammonia, it is determined that the level of liquid ammonia in this ammonia tank has dropped, so that the process proceeds automatically to the next control. enable.

  According to the invention of claim 3, since the pressure set of the accumulator of the other supply system is temporarily increased, it is possible to vent ammonia to the other supply system.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a case where ammonia gas is supplied to a denitration apparatus (not shown) installed in a thermal power plant will be described as an example.

(Embodiment 1)
An ammonia gas supply system according to this embodiment is shown in FIG. This ammonia gas supply system includes tank devices 1 and 2 that supply liquid ammonia, an absorption device 3 that absorbs ammonia gas, a tank output communication valve 4 that connects the outlet side of the tank device 1 and the outlet side of the tank device 2, A system 5 and B system 6 for supplying liquid ammonia from tank apparatuses 1 and 2 to ammonia gas as denitration apparatus (not shown), tank apparatuses 1 and 2, tank output communication valve 4, A system 5 and B A control device 7 for controlling the system 6 is provided.

Further, as shown in FIG. 2, the tank apparatuses 1 and 2 are composed of ammonia tanks 10A and 20A, tank gas release valves 10B ₁ and 20B ₁ , tank liquid outlet outlet valves 10B ₂ and 20B ₂ , and a tank output valve 10B _3. 20B ₃ respectively. Moreover, the absorption device 3 includes an absorption tank 31 and an absorption tank water injection cutoff / bypass valve 32. Further, the A system 5 and the B system 6 include vaporizers 50A and 60A, accumulators 50B and 60B, flow meters 50C and 60C, and various valves 50D _{1 to} 50D ₈ and 60D _{1 to} 60D ₈ , respectively.

The absorber 3 blows the ammonia gas in the ammonia tanks 10A and 20A of the tank devices 1 and 2. That is, the absorption device 3 passes through the tank gas discharge valves 10B ₁ and 20B _1, and the ammonia gas flowing into the absorption tank 31 from the ammonia tanks 10A and 20A passes through the absorption tank water injection cutoff / bypass valve 32 and the absorption tank 31. Dissolve in water sprayed inside and discharge.

The ammonia tanks 10A and 20A of the tank apparatuses 1 and 2 are for storing liquid ammonia. The tank devices 1 and 2 are provided with a water level meter (not shown) that measures the level of liquid ammonia in the ammonia tanks 10A and 20A, and sends an alarm indicating a low level to the control device 7 when the remaining amount of liquid ammonia decreases. The tank gas discharge valves 10B ₁ and 20B ₁ and the tank liquid safety outlet main valves 10B ₂ and 20B _{2 of the} tank apparatuses ₁ and ₂ are, for example, ammonia in the ammonia tanks 10A and 20A during regular inspection of the ammonia tanks 10A and 20A. When the gas is blown, the operator opens and closes it. The tank output valves 10B ₃ and 20B ₃ of the tank devices 1 and 2 are opened and closed under the control of the control device 7. Similarly, the tank output communication valve 4 is also opened and closed under the control of the control device 7.

A system 5 and B system 6 are supply systems for supplying ammonia gas, and are equipped with various valves.
Valves 50D ₁ and 60D ₁ are carburetor input valve valves 50D ₂ and 60D ₂ , temperature adjustment valve valves 50D ₃ and 60D ₃ are carburetor output valve valves 50D ₄ and 60D ₄ , and pressure adjustment valves. In the following, the valve _{50D 1 ~50D 4, 60D 1 ~60D} 4,
Vaporizer input valve 50D ₁ , 60D ₁
Temperature control valve 50D ₂ , 60D ₂
Vaporizer output valve 50D ₃ , 60D ₃
Pressure regulating valve 50D ₄ , 60D ₄
. Further, among these, the carburetor input valves 50D ₁ and 60D ₁ and the carburetor output valves 50D ₃ and 60D ₃ are opened and closed under the control of the control device 7.

The vaporizers 50A and 60A of the A system 5 and the B system 6 convert the liquid ammonia supplied from the ammonia tanks 10A and 20A into ammonia gas. The vaporizers 50A and 60A vaporize the liquid ammonia from the ammonia tanks 10A and 20A at the temperature set by the temperature control valves 50D ₂ and 60D ₂ . The temperature control valves 50D ₂ and 60D ₂ are set by an operator. The accumulators 50B and 60B store the ammonia gas vaporized by the vaporizers 50A and 60A and maintain the pressure set by the pressure regulating valves 50D ₄ and 60D ₄ . The pressure regulating valves 50D ₄ and 60D ₄ are set by an operator. The valves 50D _{5 to} 50D ₈ and 60D _{5 to} 60D ₈ supply ammonia gas having a high gas pressure to the denitration device (not shown) in the ammonia gas whose gas pressure is adjusted by the accumulators 50B and 60B. The flow meters 50C and 60C are installed on the outlet sides of the accumulators 50B and 60B, respectively, and measure the flow rate of ammonia gas supplied to a denitration device (not shown). Then, the flow meters 50 </ b> C and 60 </ b> C send the measured values to the control device 7.

The control device 7 performs a supply process of ammonia gas to the denitration device (not shown), a process for using up the ammonia tank, etc. during periodic inspections according to a program built in advance. The control device 7 performs the supply process of ammonia gas and the exhaustion process of the ammonia tank, the tank output communication valve 4, the tank output valves 10B ₃ and 20B ₃ , the vaporizer input valves 50D ₁ and 60D ₁ , and the vaporizer Open / close control of the output valves 50D ₃ and 60D ₃ is performed.

Specifically, in the case of supplying ammonia gas, for example, the control device 7 supplies liquid ammonia from the ammonia tank 10A.
Tank output valve 10B ₃ ... open tank output valve 20B ₃ ... closed tank output communication valve 4 ... open vaporizer input valves 50D ₁ , 60D ₁ ... open vaporizer output valves 50D ₃ , 60D ₃ ... open. That is, the control device 7 performs control for communicating the outlet side of the tank device 1 and the outlet side of the tank device 2. In the case of ammonia gas supply processing, the pressure set value Ap of the accumulator 50B and the pressure set value Bp of the accumulator 60B are determined as follows.
Ap = Bp
Ap> Bp
Ap <Bp
It is in one state. As a result, the ammonia gas from the accumulator having the higher pressure set value in the accumulator 50B of system A 1 and the accumulator 60B of system B 2 is supplied to the denitration device (not shown), and the pressure set value is the same. In some cases, ammonia gas from both systems is supplied to the denitration device.

That is, the pressure set value Ap of the accumulator 50B and the pressure set value Bp of the accumulator 60B are expressed as follows:
Ap> Bp
Then, the A system 5 becomes an operation system, and the B system 6 becomes a backup system. The pressure set value Ap of the accumulator 50B and the pressure set value Bp of the accumulator 60B are
Ap <Bp
In this case, the operation system and the backup system are reversed.

When the ammonia tank is used up, for example, when the ammonia tank 10A is regularly checked, the control device 7
Tank output valves 10B ₃ , 20B ₃ ... Open tank output communication valve 4... Closed vaporizer input valves 50D ₁ and 60D ₁ ... Open vaporizer output valves 50D ₃ and 60D ₃ . In the case of exhausting the ammonia tank, the pressure set of the accumulator of the supply system connected to the ammonia tank to be used up is set to a higher value than the pressure set of the accumulator of the other supply system. For example, when the ammonia tank 10A is an ammonia tank to be used up, a pressure set value Ap of the accumulator 50B and a pressure set value Bp of the accumulator 60B are set as follows:
Ap> Bp
To the state. As a result, when the ammonia gas from the accumulator 50B in the A system 5 is supplied to the denitration apparatus and the liquid ammonia in the ammonia tank 10A is exhausted, the liquid ammonia from the ammonia tank 20A is vaporized in the accumulator 60B in the B system 6 and accumulator 60B. The ammonia gas from is supplied to the denitration device.

Next, an ammonia gas supply method using the ammonia gas supply system according to this embodiment will be described with reference to the flowcharts of FIGS. In this description, the tank for supplying liquid ammonia by the supply process of ammonia gas is the ammonia tank 10A, and the case where the ammonia tank 10A is regularly inspected is taken as an example. In this case, the A system 5 is an operational system, and the B system 6 is a backup system when an abnormality occurs in the operational system. That is, the pressure set value of the accumulator on the operating system side (accumulator 50B) and the pressure set value of the accumulator on the backup system (accumulator 60B) are
Ap> Bp
It is in the state of. As a result, as shown in FIG. 6, ammonia gas is supplied to the denitration apparatus through a path indicated by a solid wide arrow. Further, ammonia gas can be supplied to the denitration apparatus through a path indicated by a broken wide arrow. In FIG. 6, the black coating of the valve indicates a closed state, and the flow of liquid ammonia or ammonia gas is prevented. Further, in FIG. 6, only some of the valves are described in order to prevent the drawing from becoming complicated. 9 is described in the same manner as FIG.

  When the ammonia tank depletion process (FIG. 3) is started from the state in which the ammonia gas supply process is performed, the control device 7 confirms whether or not the ammonia tank to be used up (the ammonia tank 10A) is in use. (Step S1), supply of liquid ammonia from the tank is continued (Step S2).

After step S2, it is checked whether or not the tank device (tank device 1) including the ammonia tank to be used up (ammonia tank 10A) has issued an alarm indicating a low level (step S3). If there is no alarm, the control device 7 returns the process to step S2. When an alarm indicating a low level is generated in step S3, the controller 7 notifies the operator of the alarm generation, and the pressure set of the accumulator (accumulator 50B) on the operating system side is set to the accumulator (accumulator 60B) on the backup system side. A predetermined value higher than the value of the pressure set is set (step S4). For example, the value Ap of the pressure set of the accumulator (accumulator 50B) on the operating system side and the value Bp of the pressure set of the accumulator (accumulator 60B) on the backup system side,
Ap = 0.15 [MPa]
Bp = 0.14 [MPa]
To.

After step S4, an ammonia aeration process is performed to change the pressure set of the accumulator (accumulator 60B) on the backup system side (step S5). In the ammonia aeration process (FIG. 4), the pressure set value of the accumulator (accumulator 60B) on the backup system side is increased (step S21). For example, the pressure set value Bp of the accumulator (accumulator 60B) is changed from 0.14 [MPa] to 0.15 [MPa]. After step S21, it is confirmed that the output flow rate of the flow meter (flow meter 60C) on the backup system side has become larger than 0 [Nm ³ / H] (step S22). This confirms that liquid ammonia and ammonia gas have flowed through the backup system. After step S22, the pressure set of the accumulator (accumulator 60B) on the backup system side is returned to the original value (step S23), the ammonia aeration process in step S5 is terminated, and the operator or the like notifies the control device 7 of the end of the process. To do.

After step S5, the control device 7 opens the tank output valve (tank output valve 20B ₃ ) on the backup system side (step S6) and closes the tank output communication valve 4 (step S7). Thereby, as shown in FIG. 7, ammonia tanks are respectively connected corresponding to the operation system and the backup system. That is, the A system 5 is connected to the ammonia tank 10A, and the B system 6 is connected to the ammonia tank 20A. As a result, in step S4, the pressure set of the accumulator on the operating system side (accumulator 50B) is set to a predetermined value higher than the pressure set value of the accumulator on the backup system side (accumulator 60B). From the backup system, ammonia gas can be supplied by liquid ammonia from the tank.

After step S7, the control device 7 confirms that the output flow rate of the flow meter (flow meter 50C) on the operating system side has become 0 [Nm ³ / H] (step S8). Thereby, it is confirmed that the liquid ammonia in the ammonia tank (ammonia tank 10A) to be used up has been used up. At this time, the pressure set value of the accumulator on the operating system side (accumulator 50B) and the pressure set value of the accumulator on the backup system (accumulator 60B) are:
Ap> Bp
As shown in FIG. 8, when the liquid ammonia in the ammonia tank to be used up (ammonia tank 10A) is used up, the liquid ammonia from the ammonia tank 20A connected to the backup system enters the backup system as shown in FIG. The supply of ammonia gas does not stop.

After step S8, the control device 7 opens the tank output communication valve 4 closed in step S7 (step S9), and immediately thereafter closes the tank output valve (tank output valve 10B ₃ ) on the operation system side (step S10). ). Thereby, as shown in FIG. 9, the pressure set value of the accumulator on the operating system side (accumulator 50B) and the pressure set value of the accumulator on the backup system (accumulator 60B) are
Ap> Bp
Therefore, liquid ammonia from the ammonia tank (ammonia tank 20A) connected to the backup system is supplied to the operation system and the backup system, and the denitration device (not shown) has ammonia gas from the operation system. Is supplied. Thus, the exhausting process of the ammonia tank is completed. In addition, when switching an operation system and a backup system from the original state, the value of the pressure set of each accumulator is changed.

When the exhausting process of the ammonia tank is completed, the ammonia tank is blown by the absorber 3 (FIG. 5). In this process, the level of the ammonia tank (ammonia tank 10A) to be used up is confirmed (step S41). In step S41, the ammonia apparatus drain pump trial run and the water level gauge of the absorption tank 31 are used. After step S41, the absorption tank water injection blocking / bypass valve 32 is slightly opened (step S42). Thereafter, the tank liquid safety outlet main valve (tank liquid safety outlet main valve 10B ₂ ) of the ammonia tank (ammonia tank 10A) to be used up is closed (step S43). Thereafter, the tank gas release valve (tank gas release valve 10B ₁ ) of the ammonia tank to be used up (ammonia tank 10A) is slightly opened and the tank gas release valve is fully opened while paying attention to piping hammering ( Step S44). After step S44, it is confirmed that the tank pressure of the ammonia tank to be used up (ammonia tank 10A) has reached 0 [MPa] (step S45), and the tank gas release valve (tank gas release valve 10B ₁ ) on this tank side is confirmed. ) Is closed (step S46). After the work is completed, the tank liquid safety outlet main valve (tank liquid safety outlet main valve 10B ₂ ) of the ammonia tank (ammonia tank 10A) to be used up is opened (step S47), and the absorption tank water injection shut-off / bypass valve 32 is closed. (Step S48), the ammonia tank blowing process is terminated.

  Thus, according to this embodiment, for example, it is possible to use up liquid ammonia when inspecting the ammonia tanks 10A and 20A. As a result, the ammonia tank blowing work of vaporizing and discharging the liquid ammonia remaining in the exhausted ammonia tank becomes unnecessary, and the ammonia tank blowing work is only ammonia gas, so the working time is greatly reduced. It is possible to improve work efficiency. Further, since the liquid ammonia in the ammonia tank to be used up is used up, the liquid ammonia can be effectively used to the end. Also, when the liquid ammonia in the ammonia tank to be used up is used up, the supply of ammonia gas is continued by supplying liquid ammonia from another ammonia tank filled with liquid ammonia, so the supply of ammonia gas is interrupted Can be prevented. Furthermore, according to this embodiment, it is possible to use up the liquid ammonia without using a device newly added to the system.

(Embodiment 2)
In this embodiment, the ammonia gas supply method of Embodiment 1, that is, the ammonia tank exhaustion process (FIG. 3), the ammonia aeration process (FIG. 4), and the ammonia tank blow process (FIG. 4) are executed by a computer. It is good also as a program for. In this case, the tank gas discharge valves 10B ₁ and 20B ₁ of the tank apparatuses 1 and 2 and the tank liquid safety outlet main valves 10B ₂ and 20B ₂ and the pressure regulating valves 50D ₄ and 60D _{4 of the} A system 5 and the B system 6 are used. Are opened and closed under the control of the control device 7.

  According to this embodiment, the ammonia tank exhausting process, the ammonia aeration process, and the ammonia tank blowing process of the ammonia gas supply method can all be performed automatically, and the burden on the worker can be greatly reduced. To.

  As mentioned above, although each embodiment of this invention has been described in detail, the specific configuration is not limited to each embodiment, and even if there is a design change or the like without departing from the gist of this invention, It is included in this invention. For example, in each embodiment, the ammonia gas supply system is configured to include two ammonia tanks and supply systems corresponding thereto, but the present invention corresponds to three or more ammonia tanks and these. The present invention can also be applied to a system having a configuration including a supply system.

It is a block diagram which shows the ammonia gas supply system by Embodiment 1 of this invention. It is a block diagram which shows the detail of the tank apparatus of Embodiment 1, an absorber, A system, and B system. 3 is a flowchart showing a process for using up an ammonia tank according to the first embodiment. 3 is a flowchart showing ammonia aeration processing according to Embodiment 1. 3 is a flowchart showing an ammonia tank blow process according to Embodiment 1; It is a figure explaining the mode of using up the ammonia tank by Embodiment 1. FIG. It is a figure explaining the mode of using up the ammonia tank by Embodiment 1. FIG. It is a figure explaining the mode of using up the ammonia tank by Embodiment 1. FIG. It is a figure explaining the mode of using up the ammonia tank by Embodiment 1. FIG.

Explanation of symbols

1, 2 Tank device 10A, 20A Ammonia tank 10B ₁ , 20B ₁ Tank gas release valve 10B ₂ , 20B ₂ Tank liquid outlet outlet valve 10B ₃ , 20B ₃ Tank output valve 3 Absorber 31 Absorption tank 32 Absorption tank water injection shut-off Bypass valve 4 Tank output communication valve 5 A system (supply system)
6 B system (supply system)
50A, 60A vaporizer 50B, 60B accumulator 50C, 60C flowmeter 50D _1, 60D ₁ tank gas release valve 50D _2, 60D ₂ thermostatic valve 50D _3, 60D ₃ vaporizer output valve 50D _4, 60D ₄ pressure regulating valve 50D ₅ -50D ₈ , 60D ₅ -60D ₈ valve 7 control device

Claims (5)

A second valve that communicates with the outlet side of the first valve provided at each of the outlets of the plurality of ammonia tanks; after the liquid ammonia from the first valve is vaporized, the ammonia gas is supplied at a constant pressure by an accumulator; In the ammonia gas supply system provided with a supply system to be maintained in correspondence with each ammonia tank,
First control for opening the first valve of the one ammonia tank and opening the second valve, and when the level of liquid ammonia in the ammonia tank decreases, the accumulator of one supply system corresponding to the ammonia tank A second control for setting the pressure of the ammonia tank higher than the pressure of the accumulator of the other supply system corresponding to the other ammonia tank, and a first valve of the ammonia tank connected to the other supply system. An ammonia gas supply system comprising: a control device that performs a third control that opens and closes the second valve.   2. The ammonia gas according to claim 1, wherein when the one ammonia tank side issues an alarm indicating a low level of liquid ammonia, the control device determines that the level of liquid ammonia in the ammonia tank has decreased. Supply system.   The ammonia gas supply system according to claim 1, wherein the control device performs control to temporarily increase the pressure of the accumulator of the other supply system after the second control. A second valve that communicates with the outlet side of the first valve provided at each of the outlets of the plurality of ammonia tanks; after the liquid ammonia from the first valve is vaporized, the ammonia gas is supplied at a constant pressure by an accumulator; In the ammonia gas supply method using the ammonia gas supply system provided with a supply system to be maintained in correspondence with each ammonia tank,
Opening the first valve of the one ammonia tank and opening the second valve;
When the level of liquid ammonia in the one ammonia tank decreases, the pressure of the accumulator in one supply system corresponding to the ammonia tank is made higher than the pressure of the accumulator in the other supply system corresponding to the other ammonia tank. Set and
Opening the first valve of the ammonia tank connected to the other supply system, and closing the second valve;
A method for supplying ammonia gas. A second valve that communicates with the outlet side of the first valve provided at each of the outlets of the plurality of ammonia tanks; after the liquid ammonia from the first valve is vaporized, the ammonia gas is supplied at a constant pressure by an accumulator; An ammonia gas supply program for causing a computer to execute an ammonia gas supply method using an ammonia gas supply system provided with a supply system corresponding to each ammonia tank,
Opening the first valve of the one ammonia tank and opening the second valve;
When the level of liquid ammonia in the one ammonia tank decreases, the pressure of the accumulator in one supply system corresponding to the ammonia tank is made higher than the pressure of the accumulator in the other supply system corresponding to the other ammonia tank. Processing to set,
Opening the first valve of the ammonia tank connected to the other supply system, and closing the second valve;
The ammonia gas supply program characterized by including.

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