Purification plant and purification plant control method

Abstract

This purification plant comprises: a temperature swing adsorption (TSA) tower in which unreacted ammonia is adsorbed to an adsorbent and removed from a decomposition gas and from which a resulting treated gas is discharged; a gas-purifying device that separately discharges product gas refined from the treated gas and off-gas; an off-gas heating device that heats the off-gas and supplies same to the TSA tower as regeneration gas for regenerating the adsorbent in the TSA tower; a combustion device that supplies, as a heat source for the off-gas heating device, a portion of a combustion gas resulting from combusting the regeneration gas discharged from the TSA tower; an off-gas flow path that circulates the off-gas through the combustion device; and a combustion-gas flow path that circulates the combustion gas through the off-gas heating device.

Description

Refining plant and method for controlling the refining plant

[0001] This application claims priority to Japanese Patent Application No. 2024-118819, filed on July 24, 2024, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 describes a hydrogen production system that includes an ammonia decomposition device that generates decomposition gas by decomposing ammonia, a hydrogen recovery device that separates hydrogen from the decomposition gas and discharges the hydrogen, and discharges the remaining off-gas containing hydrogen and nitrogen, and a heating device that uses the off-gas as a regeneration gas for the hydrogen recovery device and then as a heat source for the ammonia decomposition device.

[0003] International Publication No. 2018 / 116982

[0004] In the invention described in Patent Document 1, the off-gas generated in the hydrogen purification section is returned to the ammonia cracking section for reuse. In other words, the off-gas is circulated across the two sections. Therefore, when adding a hydrogen purification section to an existing plant (ammonia cracking section), the configuration of the existing plant must be modified.

[0005] An object of the present disclosure is to provide a refinery plant that can be easily added without changing the configuration of an existing plant, and a method for controlling the refinery plant.

[0006] According to one aspect of the present disclosure, a purification plant includes a TSA tower that discharges treated gas obtained by removing unreacted ammonia from cracked gas produced by thermally decomposing ammonia in a cracking plant by adsorbing the unreacted ammonia onto an adsorbent, a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas, an off-gas heating device that heats the off-gas and supplies it to the TSA tower as a regeneration gas for regenerating the adsorbent of the TSA tower after adsorbing ammonia, a combustion device that supplies a portion of combustion gas obtained by burning the regeneration gas discharged from the TSA tower as a heat source for the off-gas heating device, an off-gas flow path that circulates the off-gas to the combustion device, and a combustion gas flow path that circulates the combustion gas to the off-gas heating device.

[0007] According to one aspect of the present disclosure, a purification plant includes: a TSA tower that discharges treated gas obtained by removing unreacted ammonia from cracked gas produced by thermally decomposing ammonia in a cracking plant by adsorbing the unreacted ammonia onto an adsorbent; a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas; a combustion device that supplies a portion of combustion gas obtained by burning the off-gas to the TSA tower as a heat source for heating a regeneration gas that regenerates the adsorbent in the TSA tower after adsorbing the ammonia; an off-gas flow path that circulates the off-gas to the TSA tower; and a combustion gas flow path that circulates the combustion gas to the TSA tower.

[0008] According to one aspect of the present disclosure, a purification plant includes a TSA tower that discharges treated gas obtained by removing unreacted ammonia from cracked gas produced by thermally decomposing ammonia in a cracking plant by adsorbing the unreacted ammonia onto an adsorbent, a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas, a regeneration gas combustion device that combusts at least a portion of the off-gas and supplies it to the TSA tower as regeneration gas for regenerating the adsorbent of the TSA tower after adsorbing ammonia, and an off-gas flow path that circulates the off-gas to the regeneration gas combustion device.

[0009] According to one aspect of the present disclosure, a method for controlling a purification plant includes a TSA tower that discharges treated gas obtained by removing unreacted ammonia from cracked gas produced by thermally decomposing ammonia by adsorbing the ammonia onto an adsorbent, a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas, an off-gas heating device that heats the off-gas and supplies it to the TSA tower as a regeneration gas for regenerating the adsorbent of the TSA tower after adsorbing the ammonia, a combustion device that supplies a portion of combustion gas obtained by combusting the regeneration gas discharged from the TSA tower as a heat source for the off-gas heating device, and a combustion device that supplies the off-gas to the combustion equipment. a combustion gas flow path for flowing the combustion gas to the off-gas heating device; an off-gas heating device bypass flow path that branches off from the combustion gas flow path upstream of the off-gas heating device and bypasses the off-gas heating device; and a bypass valve provided in the off-gas heating device bypass flow path, the control method comprising the steps of: increasing the aperture of the bypass valve of the off-gas heating device bypass flow path when the regeneration temperature in the TSA tower exceeds a regeneration temperature upper limit value; and decreasing the aperture of the bypass valve of the off-gas heating device bypass flow path when the regeneration temperature is below a regeneration temperature lower limit value.

[0010] According to one aspect of the present disclosure, a method for controlling a purification plant includes a TSA tower that discharges treated gas obtained by removing unreacted ammonia from cracked gas produced by thermally decomposing ammonia in a cracking plant by adsorbing the unreacted ammonia onto an adsorbent, a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas, a combustion device that supplies a portion of combustion gas obtained by burning the off-gas to the TSA tower as a heat source for heating a regeneration gas that regenerates the adsorbent in the TSA tower after adsorption of ammonia, and an on-line combustion device that circulates the off-gas through the TSA tower. a combustion gas flow path for circulating the combustion gas to the TSA tower; a TSA tower bypass flow path branching from the combustion gas flow path upstream of the TSA tower and bypassing the TSA tower; and a bypass valve provided in the TSA tower bypass flow path, the control method for a refinery plant including the steps of: increasing an aperture of the bypass valve of the TSA tower bypass flow path when a regeneration temperature in the TSA tower exceeds a regeneration temperature upper limit; and decreasing an aperture of the bypass valve of the TSA tower bypass flow path when the regeneration temperature is below a regeneration temperature lower limit.

[0011] According to one aspect of the present disclosure, a method for controlling a purification plant includes a TSA tower that discharges treated gas obtained by removing unreacted ammonia from cracked gas produced by thermally decomposing ammonia in a cracking plant by adsorbing the unreacted ammonia onto an adsorbent, a gas purification unit that separates and discharges a product gas purified from the treated gas and an off-gas, a regeneration gas combustion unit that combusts at least a portion of the off-gas and supplies it to the TSA tower as regeneration gas for regenerating the adsorbent of the TSA tower after adsorbing the ammonia, and a control unit that circulates the off-gas through the regeneration gas combustion unit. a regeneration gas combustion device bypass flow path that branches off from the off gas flow path upstream of the regeneration gas combustion device and bypasses the regeneration gas combustion device; and a bypass valve provided in the regeneration gas combustion device bypass flow path, the control method comprising the steps of increasing the aperture of the bypass valve of the regeneration gas combustion device bypass flow path when the regeneration temperature in the TSA tower exceeds a regeneration temperature upper limit value, and decreasing the aperture of the bypass valve of the regeneration gas combustion device bypass flow path when the regeneration temperature is below a regeneration temperature lower limit value.

[0012] According to the above aspect, the system can be easily added to an existing plant without changing the configuration of the plant.

[0013] FIG. 1 is a schematic diagram showing the overall configuration of a plant according to a first embodiment. FIG. 2 is a block diagram showing the functional configuration of a control device according to the first embodiment. FIG. 3 is a first flowchart showing an example of processing by a control device according to the first embodiment. FIG. 4 is a second flowchart showing an example of processing by a control device according to the first embodiment. FIG. 5 is a schematic diagram showing the overall configuration of a plant according to a second embodiment. FIG. 6 is a flowchart showing an example of processing by a control device according to the second embodiment. FIG. 7 is a schematic diagram showing the overall configuration of a plant according to a third embodiment. FIG. 8 is a first flowchart showing an example of processing by a control device according to the third embodiment. FIG. 9 is a second flowchart showing an example of processing by a control device according to the third embodiment. FIG. 10 is a schematic diagram showing the overall configuration of a plant according to a fourth embodiment. FIG. 11 is a flowchart showing an example of processing by a control device according to the fourth embodiment. FIG. 12 is a schematic diagram showing the overall configuration of a plant according to a fifth embodiment. FIG. 13 is a schematic diagram showing the overall configuration of a plant according to a sixth embodiment. FIG. 14 is a schematic diagram showing the overall configuration of a plant according to a seventh embodiment. FIG. 15 is a schematic diagram showing the overall configuration of a plant according to an eighth embodiment. FIG. 16 is a schematic diagram showing the overall configuration of a plant according to a ninth embodiment. FIG. 17 is a flowchart showing an example of processing by an online analyzer according to the ninth embodiment. FIG. 18 is a schematic diagram showing the overall configuration of a plant according to a tenth embodiment.

[0014] First Embodiment Hereinafter, a first embodiment will be described in detail with reference to FIGS.

[0015] (Overall Configuration of Plant) Fig. 1 is a schematic diagram showing the overall configuration of a plant according to Embodiment 1. As shown in Fig. 1, the plant 1 includes a cracking plant 2 and a refining plant 3.

[0016] The cracking plant 2 includes an ammonia supply unit 21, an ammonia decomposition unit 22, and an ammonia recovery unit 23 (ARU). The ammonia supply unit 21 has a tank for storing ammonia (liquid). The ammonia decomposition unit 22 thermally decomposes the ammonia supplied from the ammonia supply unit 21 into a cracked gas containing nitrogen and hydrogen. The ARU 23 recovers ammonia from the cracked gas and returns it to the ammonia decomposition unit 22. An existing plant may be used as the cracking plant 2.

[0017] The refining plant 3 purifies a product gas (hydrogen gas) from the cracked gas produced in the cracking plant 2. The refining plant 3 includes a TSA column 30, a gas purifying device 31, an off-gas heating device 32, an air supply device 33, an air heating device 34, a combustion device 35, and a control device 10.

[0018] Cracked gas is introduced into the TSA tower 30 from the cracking plant 2 through the cracked gas flow path L1. The TSA tower 30 removes substances from the cracked gas that may adversely affect downstream gas purification equipment. The TSA tower 30 uses temperature swing adsorption (TSA) to adsorb unreacted ammonia, moisture, and other substances contained in the cracked gas onto an adsorbent, thereby removing the unreacted ammonia and moisture, and then discharges the treated gas. Note that multiple TSA towers 30 are provided in parallel. While FIG. 1 shows an example in which two TSA towers 30A and 30B are provided in parallel, three or more TSA towers may be provided. When the adsorbent approaches its adsorption limit, the TSA tower 30 switches the on / off state of an on-off valve to allow off-gas to flow instead of the cracked gas, thereby performing a regeneration process in which ammonia is desorbed from the adsorbent and regenerated. While one TSA tower 30 performs a regeneration process, the other performs an adsorption process in which ammonia is adsorbed onto the adsorbent and removed, allowing the adsorption process to continue without stopping the operation of the purification plant 3. FIG. 1 shows an example in which the TSA column 30A performs the adsorption treatment and the TSA column 30B performs the regeneration treatment.

[0019] The gas purification device 31 receives the treated gas from the TSA column 30 through the treated gas flow path L2. The gas purification device 31 uses various known techniques, such as temperature swing adsorption (TSA), pressure swing adsorption (PSA), and membrane separation, to remove substances other than the product gas (such as nitrogen) from the treated gas and purify it into a high-purity product gas (hydrogen). The purified product gas may be used in a production process at the facility (company's factory) where the purification plant 3 is installed, or may be sold to nearby consumers. The remaining off-gas is separated from the product gas and discharged. In this embodiment, the off-gas is used to regenerate the TSA column 30. A portion of the off-gas may be further separated and used as a by-product gas in another process. In this case, the off-gas flow path L3 has a by-product gas flow path L31, which is a branch flow path that outputs a portion of the off-gas as a by-product gas. A by-product gas flow control valve V31 is provided in the by-product gas flow path L31, which can adjust the flow rate of the by-product gas.

[0020] The off-gas heater 32 receives off-gas from the gas purifier 31 through an off-gas passage L3, and receives combustion gas from the combustor 35 through a combustion gas passage L5. The off-gas heater 32 is a heat exchanger that heats the off-gas by exchanging heat between the off-gas and the combustion gas. The off-gas heater 32 supplies the heated off-gas to the TSA tower 30 as a regeneration gas for regenerating the adsorbent in the TSA tower 30 after adsorbing ammonia.

[0021] The air supply device 33 supplies air taken in from the outside to the air heating device 34 through the air flow path L4.

[0022] The air heating device 34 receives air from the air supply device 33 through the air flow path L4, and also receives combustion gas from the combustion device 35 through the combustion gas flow path L5. The air heating device 34 is a heat exchanger that heats the air by exchanging heat between the air and the combustion gas. The air heating device 34 supplies the heated air to the combustion device 35 through the air flow path L4.

[0023] The regeneration gas (heated off-gas) used to regenerate the adsorbent in the TSA column 30 is introduced into the combustion device 35 through an off-gas passage L3, and air heated by the air heater 34 is introduced through an air passage L4. The combustion device 35 generates combustion gas by combusting the regeneration gas and air using a burner combustion, an oxidative decomposition catalyst, a thermal decomposition (cracking) catalyst, or the like. The combustion gas is supplied as a heat source to the off-gas heater 32 and the air heater 34 through a combustion gas passage L5.

[0024] The combustion gas flow path L5 has an off-gas heater bypass flow path L51 that branches off from the upstream side of the off-gas heater 32 and bypasses the off-gas heater 32, and an air heater bypass flow path L52 that branches off from the upstream side of the air heater 34 and bypasses the air heater 34. The off-gas heater bypass flow path L51 is provided with a bypass valve V51 that can adjust the flow rate of combustion gas in the off-gas heater bypass flow path L51. The air heater bypass flow path L52 is provided with a bypass valve V52 that can adjust the flow rate of combustion gas in the air heater bypass flow path L52. The off-gas heater bypass flow path L51 merges with the combustion gas flow path L5 downstream of the off-gas heater 32. The air heater bypass flow path L52 merges with the combustion gas flow path L5 downstream of the air heater 34. If the temperature of the combustion gas flowing downstream of the off-gas heater 32 and the air heater 34 is sufficiently high, it may be reused as a heat source for another heating device.

[0025] In addition, sensors for measuring temperature, concentration, etc. are provided in each part of the refining plant 3. In this embodiment, the refining plant 3 has a thermometer T1 that measures the temperature (regeneration temperature) in the TSA tower 30, a thermometer T2 that measures the temperature (combustor temperature) in the combustion device 35, and a concentration meter S1 that measures the concentration of nitrogen oxides (NOx, NO, etc.) contained in the combustion gas. For example, as shown in FIG. 1, the thermometer T1 is provided downstream (near the outlet) of the TSA tower 30 in the off-gas flow path L3 and measures the temperature of the regeneration gas (off-gas) flowing through the TSA tower 30 as the regeneration temperature. Alternatively, the thermometer T1 may be provided inside the TSA tower 30 to directly measure the temperature inside the TSA tower 30. As shown in FIG. 1, the thermometer T2 is provided on the most upstream side (near the outlet of the combustion device 35) of the combustion gas flow path L5 and measures the temperature of the combustion gas as the combustion device temperature. Alternatively, the thermometer T2 may be provided inside the combustion device 35 to directly measure the temperature inside the combustion device 35. The concentration meter S1 is provided on the most upstream side of the combustion gas flow path L5 (near the outlet of the combustion device 35) as shown in FIG. 1, and measures the concentration of nitrogen oxides contained in the combustion gas.

[0026] The control device 10 controls the operation of each part of the refining plant 3 .

[0027] (Functional Configuration of Control Device) Fig. 2 is a block diagram showing the functional configuration of the control device according to embodiment 1. As shown in Fig. 2, the control device 10 includes a processor 11, a memory 12, a storage 13, and a communication interface 14.

[0028] The processor 11 operates in accordance with a predetermined program to function as an acquisition unit 111 and a control unit 112 .

[0029] The acquisition unit 111 acquires measurement values ​​from the sensors (thermometers T1, T2, and concentration meter S1).

[0030] The control unit 112 adjusts the apertures of the bypass valves V51 and V52 in the combustion gas flow path based on measurements from sensors in various parts. Specifically, the control unit 112 adjusts the aperture of the bypass valve V51 in the off-gas heating device bypass flow path L51 based on the regeneration temperature of the TSA tower 30, thereby maintaining the regeneration temperature of the TSA tower 30 within an appropriate temperature range. The control unit 112 also adjusts the aperture of the bypass valve V52 in the air heating device bypass flow path L52 based on the concentration of nitrogen oxides contained in the combustion gas and the combustor temperature, thereby maintaining the combustor temperature within an appropriate temperature range.

[0031] The memory 12 has a memory area necessary for the operation of the processor 11 .

[0032] The storage 13 is a so-called auxiliary storage device, such as a hard disk drive (HDD), a solid state drive (SSD), etc. The storage 13 stores data that each part of the processor 11 acquires, generates, and references during processing.

[0033] The communication interface 14 is an interface for transmitting and receiving signals including measurement values, commands, etc. between each unit.

[0034] (Processing Example 1 of Control Device) Fig. 3 is a first flowchart showing a processing example of the control device according to the first embodiment. First, with reference to Fig. 3, a processing flow in which the control device 10 controls the regeneration temperature of the TSA column 30 will be described. First, the acquisition unit 111 of the control device 10 acquires the regeneration temperature of the TSA column 30 (measurement value of the thermometer T1) (step ST101).

[0035] If the regeneration temperature of the TSA column 30 exceeds a predetermined regeneration temperature upper limit (step ST102; YES), the control unit 112 of the control device 10 determines whether the aperture of the bypass valve V51 of the off-gas heater bypass flow path L51 can be increased (step ST103). If the aperture of the bypass valve V51 can be increased (i.e., the aperture is less than the maximum aperture) (step ST103; YES), the control unit 112 outputs a command to the bypass valve V51 to increase the aperture (step ST104). When the bypass valve V51 increases the aperture in response to the command, the flow rate of the combustion gas in the off-gas heater bypass flow path L51 increases, and the flow rate of the combustion gas introduced into the off-gas heater 32 decreases accordingly. This reduces the amount of heat imparted from the combustion gas to the off-gas heater 32, and the temperature of the off-gas (regeneration gas) heated by the off-gas heater 32 decreases. In other words, the regeneration temperature of the TSA column 30 decreases.

[0036] Furthermore, if the aperture of the bypass valve V51 cannot be increased (the aperture is already at the maximum value) (step ST103; NO), the control unit 112 may output a command to increase the aperture of the by-product gas flow control valve V31 (step ST105). This increases the flow rate of the by-product gas, and accordingly reduces the flow rate of the off-gas (regeneration gas) flowing to the off-gas heating device 32 and the TSA tower 30. At the same time, the flow rate of the combustion gas also decreases. As a result, the amount of heat provided to the TSA tower 30 can be reduced, thereby lowering the regeneration temperature. When the temperature of the combustion gas is high, the flow rate of the off-gas supplied to the off-gas heating device 32 and the flow rate of the combustion gas may be reduced in this manner to adjust the regeneration temperature of the TSA tower 30.

[0037] On the other hand, if the regeneration temperature of the TSA column 30 is equal to or lower than a predetermined regeneration temperature upper limit (step ST102; NO), it is determined whether the regeneration temperature is lower than a predetermined regeneration temperature lower limit (step ST106). If the regeneration temperature is lower than the predetermined regeneration temperature lower limit (step ST106; YES), it is determined whether the aperture of the bypass valve V51 of the off-gas heater bypass flow path L51 can be reduced (step ST107). If the aperture of the bypass valve V51 can be reduced (the aperture is greater than the minimum value) (step ST107; YES), the control unit 112 outputs a command to the bypass valve V51 to reduce the aperture (step ST108). When the bypass valve V51 reduces the aperture in response to the command, the flow rate of the combustion gas in the off-gas heater bypass flow path L51 decreases, and the flow rate of the combustion gas supplied to the off-gas heater 32 increases accordingly. This increases the amount of heat that the combustion gas provides to the off-gas heater 32, and increases the temperature of the off-gas (regeneration gas) supplied from the off-gas heater 32 to the TSA column 30. In other words, the regeneration temperature of the TSA column 30 increases.

[0038] Furthermore, if the aperture of the bypass valve V51 cannot be reduced (the aperture is already at the minimum value) (step ST107; NO), the control unit 112 may output a command to the by-product gas flow control valve V31 to reduce the aperture (step ST109). This reduces the flow rate of the by-product gas, and accordingly increases the flow rate of the off-gas (regeneration gas) flowing to the off-gas heating device 32 and the TSA tower 30. At the same time, the flow rate of the combustion gas also increases. As a result, the amount of heat provided to the TSA tower 30 can be increased, thereby raising the regeneration temperature. When the temperature of the combustion gas is low, the flow rate of the off-gas supplied to the off-gas heating device 32 and the flow rate of the combustion gas may be increased in this way to adjust the regeneration temperature of the TSA tower 30.

[0039] The control device 10 repeatedly executes the series of processes shown in FIG. 3 at each predetermined control cycle to maintain the regeneration temperature of the TSA column 30 within an appropriate temperature range.

[0040] (Processing Example 2 of Control Device) Figure 4 is a second flowchart showing a processing example of the control device according to the first embodiment. Next, with reference to Figure 4, a processing flow in which the control device 10 controls the concentration of nitrogen oxides contained in the combustion gas and the combustion device temperature will be described. The acquisition unit 111 of the control device 10 acquires the concentration of nitrogen oxides in the combustion gas (measurement value of concentration meter S1) and the combustion device temperature (measurement value of thermometer T2) (step ST201).

[0041] If the nitrogen oxide concentration of the combustion gas exceeds a predetermined nitrogen oxide concentration upper limit or if the combustion device temperature exceeds a predetermined combustion device temperature upper limit (step ST202; YES), the control unit 112 of the control device 10 determines whether the opening of the bypass valve V52 of the air heater bypass flow path L52 can be increased (step ST203). If the opening of the bypass valve V52 can be increased (step ST203; YES), the control unit 112 outputs a command to the bypass valve V52 to increase its opening (step ST204). When the bypass valve V52 increases its opening in response to the command, the flow rate of the combustion gas in the air heater bypass flow path L52 increases, and the flow rate of the combustion gas in the air heater 34 decreases accordingly. This reduces the temperature of the air supplied from the air heater 34 to the combustion device 35. If burner combustion or an oxidative decomposition catalyst is used in the combustion device 35, the nitrogen oxide generation rate increases as the temperature of the combustion device 35 increases. Therefore, by lowering the temperature of the air supplied to the combustion device 35, the temperature of the combustion device 35 can be lowered, and the concentration of nitrogen oxides contained in the combustion gas can be reduced. Furthermore, even if the concentration of nitrogen oxides contained in the combustion gas is equal to or lower than the upper limit, if the temperature of the combustion device 35 exceeds the upper limit, the amount of heat given to the combustion device 35 can be reduced in this way, thereby limiting the temperature of the combustion device 35 so that it does not exceed the design temperature.

[0042] Furthermore, if the opening degree of the bypass valve V52 cannot be increased (step ST203; NO), the control unit 112 outputs a command to the air supply device 33 to reduce the amount of air supplied (step ST205). At this time, the control unit 112 reduces the amount of air supplied by the air supply device 33 within a range in which the concentration of flammable gas in the combustion gas is below the lower explosion limit. This reduces the amount of heated air supplied from the air heating device 34 to the combustion device 35, and as a result, the amount of heat imparted to the combustion device 35 also decreases. Therefore, if the temperature of the combustion device 35 is high and the flow rate of combustion gas to the air heating device 34 cannot be reduced any further, the temperature of the combustion device 35 can be lowered by reducing the air flow rate and thereby reducing the amount of heat imparted to the combustion device 35.

[0043] On the other hand, if the nitrogen oxide concentration of the combustion gas is equal to or lower than the nitrogen oxide concentration upper limit, or if the combustion device temperature is equal to or lower than the predetermined combustion device temperature upper limit (step ST202; NO), the control unit 112 determines whether the combustion device temperature is lower than the predetermined combustion device temperature lower limit (step ST206). If the combustion device temperature is lower than the combustion device temperature lower limit (step ST206; YES), the control unit 112 determines whether the opening of the bypass valve V52 of the air heater bypass flow path L52 can be decreased (step ST207). If the opening of the bypass valve V52 can be decreased (step ST207; YES), the control unit 112 outputs a command to the bypass valve V52 to decrease its opening (step ST208). When the bypass valve V52 decreases its opening in response to the command, the flow rate of the combustion gas in the air heater bypass flow path L52 decreases, and the flow rate of the combustion gas supplied to the air heater 34 increases accordingly. This increases the temperature of the heated air supplied from the air heater 34 to the combustion device 35. In other words, the temperature of the combustion device 35 increases.

[0044] Furthermore, if the opening degree of the bypass valve V52 cannot be reduced (step ST207; NO), the control unit 112 outputs a command to the air supply device 33 to increase the amount of air supplied (step ST209). If the temperature of the combustion device 35 is low and the flow rate of the combustion gas to the air heating device 34 cannot be increased any further, the amount of heat given to the combustion device 35 can be increased by increasing the air flow rate, thereby raising the temperature of the combustion device 35.

[0045] The control device 10 repeatedly performs the series of processes shown in FIG. 4 at each predetermined control cycle to suppress the concentration of nitrogen oxides in the combustion gas so as not to exceed the upper limit value, and to maintain the temperature of the combustion device 35 within an appropriate temperature range.

[0046] (Operation and Effect) As described above, the refining plant 3 according to this embodiment includes the TSA tower 30 that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from the cracked gas generated by thermally decomposing ammonia in the cracking plant 2, the gas refining device 31 that separates and discharges a product gas purified from the treated gas and an off-gas, the off-gas heating device 32 that heats the off-gas and supplies it to the TSA tower as a regeneration gas for regenerating the adsorbent of the TSA tower after adsorption of ammonia, the combustion device 35 that supplies a portion of the combustion gas obtained by burning the regeneration gas discharged from the TSA tower 30 as a heat source for the off-gas heating device 32, and the combustion device 35. The system includes an air heating device 34 that supplies air heated by a portion of the gas to the combustion device, a combustion gas flow path L5 that circulates the combustion gas to the off-gas heating device 32 and the air heating device 34, an off-gas heating device bypass flow path L51 that branches off from the combustion gas flow path L5 upstream of the off-gas heating device 32 and bypasses the off-gas heating device 32, a bypass valve V51 provided in the off-gas heating device bypass flow path L51, and a control device 10 that increases the aperture of the bypass valve V51 when the regeneration temperature of the TSA tower 30 exceeds a regeneration temperature upper limit value and decreases the aperture of the bypass valve V51 when the regeneration temperature falls below a regeneration temperature lower limit value.

[0047] In this way, the refining plant 3 can establish a highly thermally efficient process in which the off-gas discharged from the gas refining device 31 is used to regenerate the TSA column of the refining plant 3. Furthermore, since the off-gas is utilized in the refining plant 3 without being utilized in the cracking plant 2, the refining plant 3 that refines the product gas (hydrogen) from the cracked gas can be easily added to the existing cracking plant 2 without changing the configuration of the cracking plant 2.

[0048] The refining plant 3 further includes an air heater bypass flow path L52 that branches off from the combustion gas flow path L5 upstream of the air heater 34 and bypasses the air heater 34, and a bypass valve V52 provided in the air heater bypass flow path L52, and the control device 10 increases the opening degree of the bypass valve V52 in the air heater bypass flow path L52 when the concentration of nitrogen oxides contained in the combustion gas exceeds the nitrogen oxide concentration upper limit value.

[0049] In this way, the refining plant 3 can limit the temperature of the combustion device 35 so that the concentration of nitrogen oxides contained in the combustion gas does not exceed the upper limit value.

[0050] In addition, the control device 10 increases the opening degree of the bypass valve V52 of the air heating device bypass flow path L52 when the combustion device temperature exceeds the combustion device temperature upper limit value, and decreases the opening degree of the bypass valve V52 of the air heating device bypass flow path L52 when the combustion device temperature falls below the combustion device temperature lower limit value.

[0051] In this way, the refining plant 3 can maintain the temperature of the combustion device 35 within an appropriate temperature range so as not to exceed the design temperature of the combustion device 35 and so as to generate sufficiently heated combustion gas.

[0052] In addition, a plurality of TSA towers 30 are provided in parallel, and in one TSA tower 30, a regeneration process is performed in which a regeneration gas is circulated to regenerate the adsorbent, and in the other TSA tower 30, an adsorption process is performed in which ammonia contained in the cracked gas is adsorbed onto the adsorbent and removed, and the treated gas is discharged.

[0053] In this way, the refining plant 3 can continue the adsorption treatment in one of the TSA towers 30 without stopping operation while the regeneration treatment is being performed in the other TSA towers 30. In other words, it is possible to prevent the operating rate of the refining plant 3 from decreasing due to the regeneration treatment of the TSA towers 30.

[0054] Second Embodiment Next, a second embodiment will be described in detail with reference to Figures 5 and 6. Components common to the above-described embodiment will be assigned the same reference numerals and detailed description will be omitted.

[0055] (Overall Configuration of Plant) Fig. 5 is a schematic diagram showing the overall configuration of a plant according to the second embodiment. As shown in Fig. 5, in a refining plant 3 according to this embodiment, combustion gas from a combustion device 35 is supplied to a TSA column 30 and used as a heat source for indirectly heating off-gas (regeneration gas) supplied from a gas refining device 31. Therefore, in this embodiment, the TSA column 30 also functions as the off-gas heating device 32 of the first embodiment, and therefore the off-gas heating device 32 may be omitted.

[0056] The TSA column 30 has a shell-and-tube or jacketed configuration, and is heated by combustion gas flowing through a combustion gas flow path L5. The combustion gas flow path L5 also has a TSA column bypass flow path L53 that branches off from the upstream side of the TSA column 30 and bypasses the TSA column 30. A bypass valve V53 is provided in the TSA column bypass flow path L53 that can adjust the flow rate of the combustion gas in the TSA column bypass flow path L53. The TSA column bypass flow path L53 merges with the combustion gas flow path L5 downstream of the TSA column 30. If the temperature of the combustion gas flowing downstream of the TSA column 30 and the air heater 34 is sufficiently high, it may be reused as a heat source for another heating device.

[0057] Furthermore, the control device 10 according to this embodiment adjusts the flow rate of the combustion gas supplied to the TSA column 30 to maintain the regeneration temperature of the TSA column 30 within an appropriate temperature range.

[0058] (Processing example of the control device) Fig. 6 is a flowchart showing a processing example of the control device according to the second embodiment. With reference to Fig. 6, a processing flow in which the control device 10 controls the regeneration temperature of the TSA column 30 will be described. First, the acquisition unit 111 of the control device 10 acquires the regeneration temperature of the TSA column 30 (step ST301).

[0059] If the regeneration temperature of the TSA tower 30 exceeds a predetermined regeneration temperature upper limit (step ST302; YES), the control unit 112 of the control device 10 outputs a command to the bypass valve V53 to increase its aperture (step ST303). When the bypass valve V53 increases its aperture in response to the command, the flow rate of the combustion gas through the TSA tower bypass flow path L53 increases, and the flow rate of the combustion gas introduced into the TSA tower 30 decreases accordingly. This reduces the amount of heat imparted from the combustion gas to the TSA tower 30, and the regeneration temperature of the TSA tower 30 decreases.

[0060] On the other hand, if the regeneration temperature of the TSA tower 30 is equal to or lower than a predetermined regeneration temperature upper limit (step ST302; NO), it is determined whether the regeneration temperature is lower than a predetermined regeneration temperature lower limit (step ST304). If the regeneration temperature is lower than the regeneration temperature lower limit (step ST304; YES), the control unit 112 outputs a command to the bypass valve V53 to decrease its opening (step ST305). When the bypass valve V51 decreases its opening in response to the command, the flow rate of the combustion gas through the TSA tower bypass flow path L53 decreases, and the flow rate of the combustion gas flowing into the TSA tower 30 increases accordingly. This increases the amount of heat provided by the combustion gas to the TSA tower 30, and the regeneration temperature rises.

[0061] 6 at predetermined control intervals to maintain the regeneration temperature of the TSA column 30 within an appropriate temperature range. Note that the flow of the process for controlling the concentration of nitrogen oxides contained in the combustion gas of the combustion device 35 and the temperature of the combustion device is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0062] (Operation and Effect) As described above, the refining plant 3 according to this embodiment includes the TSA tower 30 that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from the cracked gas generated by thermally decomposing ammonia in the cracking plant 2, the gas refining device 31 that separates and discharges a product gas purified from the treated gas and an off-gas, the combustion device 35 that supplies a portion of the combustion gas obtained by burning the off-gas to the TSA tower 30 as a regeneration gas for regenerating the adsorbent of the TSA tower 30 after adsorbing the ammonia, and an air heating device that supplies air heated by a portion of the combustion gas to the combustion device 35. 34, a combustion gas flow path L5 that passes the combustion gas through the TSA tower 30 and the air heating device 34, a TSA tower bypass flow path L53 that branches off from the combustion gas flow path L5 upstream of the TSA tower 30 and bypasses the TSA tower 30, a bypass valve V53 provided in the TSA tower bypass flow path L53, and a control device 10 that increases the aperture of the bypass valve V53 of the TSA tower bypass flow path L53 when the regeneration temperature of the TSA tower 30 exceeds an upper regeneration temperature limit, and decreases the aperture of the bypass valve V53 of the TSA tower bypass flow path L53 when the regeneration temperature falls below a lower regeneration temperature limit.

[0063] In this way, similarly to the first embodiment, the refining plant 3 utilizes the heat generated in the refining plant 3 only within the refining plant 3, so that the refining plant 3 that refines the cracked gas into the product gas (hydrogen) can be easily added to the cracking plant 2 without changing the configuration of the existing cracking plant 2. Furthermore, since the off-gas heating device 32 is omitted, the refining plant 3 can be made more compact in configuration than the first embodiment.

[0064] Third Embodiment Next, a third embodiment will be described in detail with reference to Figures 7 to 9. Components common to the above-described embodiments are given the same reference numerals, and detailed description thereof will be omitted.

[0065] (Overall Configuration of Plant) Fig. 7 is a schematic diagram showing the overall configuration of a plant according to the third embodiment. As shown in Fig. 7, the refining plant 3 according to this embodiment includes a regeneration gas combustion device 36 instead of the off-gas heating device 32 of the first embodiment.

[0066] The regeneration gas combustion device 36 receives offgas from the gas purification device 31 through an offgas flow path L3. The regeneration gas combustion device 36 combusts at least a portion of the offgas and supplies the combusted offgas to the TSA column 30 as regeneration gas for the TSA column 30. The regeneration gas combustion device 36 may be the same as the combustion device 35.

[0067] The refining plant 3 of this embodiment also has a thermometer T3 that measures the temperature inside the regeneration gas combustion device 36 (regeneration gas combustion device temperature), and a concentration meter S2 that measures the concentration of nitrogen oxides (NOx, NO, etc.) contained in the regeneration gas. For example, as shown in FIG. 7, the thermometer T3 is provided downstream of the regeneration gas combustion device in the off-gas flow path L3 (near the outlet) and measures the temperature of the regeneration gas generated by the regeneration gas combustion device 36 as the regeneration gas combustion device temperature. The thermometer T3 may also be provided inside the regeneration gas combustion device 36 to directly measure the temperature inside the regeneration gas combustion device 36. As shown in FIG. 7, the concentration meter S2 is provided downstream of the regeneration gas combustion device in the off-gas flow path L3 (near the outlet) and measures the concentration of nitrogen oxides contained in the regeneration gas.

[0068] The air heater 34 supplies air heated with the combustion gas purified by the combustion device 35 to the combustion device 35 and the regenerated gas combustion device 36 through an air flow path L4.

[0069] The combustion device 35 receives regeneration gas (off-gas) used in regenerating the adsorbent in the TSA column 30 through an off-gas passage L3, and receives air heated by the air heater 34 through an air passage L4. Combustion gas is supplied to the air heater 34 as a heat source through a combustion gas passage L5.

[0070] The control device 10 according to this embodiment also adjusts the flow rate of the offgas supplied to the regeneration gas combustion device 36 to maintain the regeneration temperature of the TSA column 30 within an appropriate temperature range. Furthermore, the control device 10 controls the concentration of nitrogen oxides contained in the regeneration gas generated by the regeneration gas combustion device 36 and the temperature of the regeneration gas combustion device.

[0071] (Processing Example 1 of the Control Device) Fig. 8 is a first flowchart showing a processing example of the control device according to the third embodiment. First, with reference to Fig. 8, a processing flow in which the control device 10 controls the regeneration temperature of the TSA column 30 will be described. First, the acquisition unit 111 of the control device 10 acquires the regeneration temperature of the TSA column 30 (step ST401).

[0072] If the regeneration temperature of the TSA column 30 exceeds a predetermined upper regeneration temperature limit (step ST402; YES), the control unit 112 of the control device 10 determines whether the aperture of the bypass valve V32 of the regeneration gas combustion unit bypass flow path L32 can be increased (step ST403). If the aperture of the bypass valve V32 can be increased (step ST403; YES), the control unit 112 outputs a command to the bypass valve V32 to increase its aperture (step ST404). When the bypass valve V32 increases its aperture in response to the command, the flow rate of the offgas in the regeneration gas combustion unit bypass flow path L32 increases, and the flow rate of the offgas flowing to the regeneration gas combustion unit 36 ​​decreases accordingly. This reduces the flow rate of the regeneration gas supplied from the regeneration gas combustion unit 36 ​​to the TSA column 30, thereby reducing the amount of heat provided from the regeneration gas to the TSA column 30 and lowering the regeneration temperature of the TSA column 30.

[0073] Furthermore, if the aperture of the bypass valve V32 cannot be increased (step ST403; NO), the control unit 112 may output a command to increase the aperture of the by-product gas flow control valve V31 (step ST405). This increases the flow rate of the by-product gas, and accordingly further reduces the flow rate of the off-gas flowing to the regeneration gas combustion device 36 (the amount of regeneration gas supplied to the TSA tower 30). As a result, similar to step ST404, the amount of heat provided to the TSA tower 30 can be reduced, thereby lowering the regeneration temperature. If the flow rate of the off-gas cannot be further reduced by the bypass valve V32 alone, the regeneration temperature of the TSA tower 30 may be adjusted by increasing the flow rate of the by-product gas in this manner.

[0074] On the other hand, if the regeneration temperature of the TSA column 30 is equal to or lower than a predetermined upper regeneration temperature limit (step ST402; NO), it is determined whether the regeneration temperature is lower than a predetermined lower regeneration temperature limit (step ST406). If the regeneration temperature is lower than the lower regeneration temperature limit (step ST406; YES), it is determined whether the aperture of the bypass valve V32 of the regeneration gas combustion unit bypass flow path L32 can be decreased (step ST407). If the aperture of the bypass valve V32 can be decreased (step ST407; YES), the control unit 112 outputs a command to the bypass valve V32 to decrease its aperture (step ST408). When the bypass valve V32 decreases its aperture in response to the command, the flow rate of the offgas in the regeneration gas combustion unit bypass flow path L32 decreases, and the flow rate of the offgas supplied to the regeneration gas combustion unit 36 ​​increases accordingly. As a result, the flow rate of the regeneration gas supplied from the regeneration gas combustion device 36 to the TSA column 30 increases, so that the amount of heat given from the regeneration gas to the TSA column 30 increases, and the regeneration temperature of the TSA column 30 rises.

[0075] Furthermore, if the aperture of the bypass valve V32 cannot be reduced (step ST407; NO), the control unit 112 may output a command to the by-product gas flow control valve V31 to reduce its aperture (step ST409). This reduces the flow rate of the by-product gas, and accordingly, the flow rate of the off-gas flowing to the regeneration gas combustion device 36 (the amount of regeneration gas supplied to the TSA tower 30) further increases. As a result, similar to step ST408, the amount of heat provided to the TSA tower 30 can be increased, thereby raising the regeneration temperature. If the flow rate of the off-gas cannot be further increased by the bypass valve V32 alone, the regeneration temperature of the TSA tower 30 may be adjusted by reducing the flow rate of the by-product gas in this manner.

[0076] The control device 10 repeatedly executes the series of processes shown in FIG. 8 at each predetermined control cycle to maintain the regeneration temperature of the TSA column 30 within an appropriate temperature range.

[0077] (Processing example 2 of the control device) Figure 9 is a second flowchart showing a processing example of the control device according to the third embodiment. Next, with reference to Figure 9, the flow of processing in which the control device 10 controls the concentration of nitrogen oxides contained in the regeneration gas and the temperature of the regeneration gas combustion device will be described. The acquisition unit 111 of the control device 10 acquires the concentration of nitrogen oxides in the regeneration gas (measurement value of concentration meter S2) and the temperature of the regeneration gas combustion device (measurement value of thermometer T3) (step ST501).

[0078] If the nitrogen oxide concentration in the regeneration gas exceeds a predetermined nitrogen oxide concentration upper limit, or if the regeneration gas combustion device temperature exceeds a predetermined combustion device temperature upper limit (step ST502; YES), the control unit 112 of the control device 10 determines whether the aperture of the bypass valve V52 of the air heater bypass flow path L52 can be increased (step ST503). If the aperture of the bypass valve V52 can be increased (step ST503; YES), the control unit 112 outputs a command to the bypass valve V52 to increase its aperture (step ST504). When the bypass valve V52 increases its aperture in response to the command, the flow rate of the combustion gas in the air heater bypass flow path L52 increases, and the flow rate of the combustion gas in the air heater 34 decreases accordingly. This reduces the temperature of the air supplied from the air heater 34 to the regeneration gas combustion device 36. As described in the first embodiment, when burner combustion or an oxidative decomposition catalyst is used in the regeneration gas combustion device 36, the nitrogen oxide purification rate increases as the temperature of the regeneration gas combustion device 36 increases. Therefore, by lowering the temperature of the air supplied to the regeneration gas combustion device 36, the temperature of the regeneration gas combustion device 36 can be lowered, and the concentration of nitrogen oxides contained in the regeneration gas can be reduced. Furthermore, even if the concentration of nitrogen oxides contained in the regeneration gas is below the upper limit, if the temperature of the regeneration gas combustion device 36 exceeds the upper limit of the combustion device temperature, the amount of heat provided to the regeneration gas combustion device 36 can be reduced in this way to limit the temperature of the regeneration gas combustion device 36 so that it does not exceed the design temperature.

[0079] Furthermore, if the opening degree of the bypass valve V52 cannot be increased (step ST503; NO), the control unit 112 outputs a command to the air supply device 33 to decrease the amount of air supplied (step ST505). This decreases the amount of heated air supplied from the air heating device 34 to the regeneration gas combustion device 36, and as a result, the amount of heat imparted to the regeneration gas combustion device 36 also decreases. Therefore, if the temperature of the regeneration gas combustion device 36 is high and the flow rate of combustion gas to the air heating device 34 cannot be reduced any further, the temperature of the regeneration gas combustion device 36 can be lowered by decreasing the flow rate of air and thereby decreasing the amount of heat imparted to the regeneration gas combustion device 36.

[0080] On the other hand, if the nitrogen oxide concentration of the combustion gas is equal to or lower than the nitrogen oxide concentration upper limit, or if the regeneration gas combustion device temperature is equal to or lower than the predetermined combustion device temperature upper limit (step ST502; NO), the control unit 112 determines whether the regeneration gas combustion device temperature is lower than the predetermined combustion device temperature lower limit (step ST506). If the regeneration gas combustion device temperature is lower than the combustion device temperature lower limit (step ST506; YES), the control unit 112 determines whether the aperture of the bypass valve V52 of the air heater bypass flow path L52 can be reduced (step ST507). If the aperture of the bypass valve V52 can be reduced (step ST507; YES), the control unit 112 outputs a command to the bypass valve V52 to reduce its aperture (step ST508). When the bypass valve V52 reduces its aperture in response to the command, the flow rate of the combustion gas in the air heater bypass flow path L52 decreases, and the flow rate of the combustion gas supplied to the air heater 34 increases accordingly. This also increases the temperature of the heated air supplied from the air heater 34 to the regeneration gas combustion device 36. That is, the temperature of the regenerated gas combustion device 36 increases.

[0081] Furthermore, if the opening degree of the bypass valve V52 cannot be reduced (step ST507; NO), the control unit 112 outputs a command to the air supply device 33 to increase the amount of air supplied (step ST509). If the temperature of the regeneration gas combustion device 36 is low and the flow rate of the combustion gas to the air heating device 34 cannot be increased any further, the amount of heat provided to the regeneration gas combustion device 36 can be increased by increasing the air flow rate, thereby raising the temperature of the regeneration gas combustion device 36.

[0082] 9 at each predetermined control cycle to prevent the nitrogen oxide concentration in the combustion gas from exceeding an upper limit value and to maintain the temperature of the combustion device 35 within an appropriate temperature range. Note that the flow of the process for controlling the nitrogen oxide concentration in the combustion gas of the combustion device 35 and the combustion device temperature is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0083] (Operation and Effect) As described above, the refining plant 3 according to this embodiment includes the TSA tower 30 that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from the cracked gas generated by thermally decomposing ammonia in the cracking plant 2, the gas refining device 31 that separates and discharges a product gas purified from the treated gas and an off-gas, the regeneration gas combustion device 36 that combusts at least a portion of the off-gas and supplies it to the TSA tower as regeneration gas for regenerating the adsorbent of the TSA tower 30 after adsorption of ammonia, the combustion device 35 that generates combustion gas by burning the regeneration gas discharged from the TSA tower 30, and the combustion device 36 that burns air heated by the combustion gas. the regeneration gas combustion device 36; an off-gas flow path L3 that branches off from the off-gas flow path L3 upstream of the regeneration gas combustion device 36 and bypasses the regeneration gas combustion device 36; a bypass valve V32 provided in the regeneration gas combustion device bypass flow path L32; and a control device 10 that increases the aperture of the bypass valve V32 of the regeneration gas combustion device bypass flow path L32 when the regeneration temperature of the TSA tower 30 exceeds the regeneration temperature upper limit value, and decreases the aperture of the bypass valve V32 of the regeneration gas combustion device bypass flow path L32 when the regeneration temperature is below the regeneration temperature lower limit value.

[0084] In this way, the refining plant 3 can establish a highly thermally efficient process in which the off-gas discharged from the gas refining device 31 is used for regenerating the TSA column of the refining plant 3. In addition, since the off-gas is used only inside the refining plant 3, it is possible to easily add a refining plant 3 that refines the product gas (hydrogen) from the cracked gas to the existing cracking plant 2 without changing the configuration of the cracking plant 2.

[0085] <Fourth embodiment> Next, a fourth embodiment will be described in detail with reference to Figures 10 and 11. Components common to the above-described embodiments will be assigned the same reference numerals and detailed description will be omitted.

[0086] (Overall Configuration of Plant) Fig. 10 is a schematic diagram showing the overall configuration of a plant according to the fourth embodiment. As shown in Fig. 10, the refining plant 3 according to this embodiment further includes a second off-gas heating device 37.

[0087] The second off-gas heating device 37 is provided upstream of the off-gas flow path L3 that passes the off-gas from the gas purification device 31 to the TSA column 30. Specifically, the second off-gas heating device 37 is provided upstream of the first off-gas heating device 32 (the off-gas heating device 32 of the first embodiment) and downstream of the branch point with the by-product gas flow path L31. The second off-gas heating device 37 uses electricity or steam as a heat source to heat the off-gas supplied to the first off-gas heating device 32.

[0088] While Fig. 10 shows an example in which the second off-gas heating device 37 is added to the configuration of the first embodiment, the present invention is not limited to this. The second off-gas heating device 37 may be added to the configuration of the second embodiment (Fig. 5) or the configuration of the third embodiment (Fig. 7). When added to the configuration of the second embodiment (Fig. 5), the second off-gas heating device 37 is provided upstream of the TSA column 30 in the off-gas flow path L3 and downstream of the branch point with the by-product gas flow path L31. When added to the configuration of the third embodiment (Fig. 7), the second off-gas heating device 37 is provided upstream of the regeneration gas combustion device 36 in the off-gas flow path L3 and downstream of the branch point with the by-product gas flow path L31.

[0089] (Example of Processing by the Control Device) FIG. 11 is a flowchart showing an example of processing by the control device according to the fourth embodiment. The control device 10 according to this embodiment executes the processing shown in FIG. 11 in addition to the processing for adjusting the regeneration temperature of the TSA column 30 described in the first to third embodiments ( FIG. 3 , FIG. 6 , or FIG. 8 ). For example, the control device 10 first executes the processing shown in FIG. 11 , and if the regeneration temperature of the TSA column 30 does not fall within the appropriate temperature range in the processing shown in FIG. 11 , then further executes the processing shown in FIG. 3 , FIG. 6 , or FIG. 8 . Alternatively, the control device 10 may first execute the processing shown in FIG. 3 , FIG. 6 , or FIG. 8 , and then further execute the processing shown in FIG. 11 if the regeneration temperature of the TSA column 30 does not fall within the appropriate temperature range.

[0090] First, the acquisition unit 111 of the control device 10 acquires the regeneration temperature of the TSA column 30 (step ST601).

[0091] When the regeneration temperature of the TSA column 30 exceeds a predetermined upper limit of the regeneration temperature (step ST602; YES), the control unit 112 of the control device 10 outputs a command to the second off-gas heater 37 to reduce the heat source (step ST603). As a result, the temperature of the off-gas decreases, and the regeneration temperature of the TSA column 30 decreases.

[0092] On the other hand, if the regeneration temperature of the TSA column 30 is equal to or lower than a predetermined upper regeneration temperature limit (step ST602; NO), the control unit 112 determines whether the regeneration temperature is lower than a predetermined lower regeneration temperature limit (step ST604). If the regeneration temperature is lower than the lower regeneration temperature limit (step ST604; YES), the control unit 112 outputs a command to the second off-gas heater 37 to increase the heat source (step ST605). This increases the off-gas temperature, and the regeneration temperature of the TSA column 30 increases.

[0093] (Operation and Effect) As described above, the refining plant 3 according to this embodiment further includes the second off-gas heater 37 provided upstream of the off-gas passage L3.

[0094] In this way, the refining plant 3 can adjust the regeneration temperature of the TSA column 30 more accurately by using the second off-gas heater 37 .

[0095] Fifth Embodiment Next, a fifth embodiment will be described in detail with reference to Fig. 12. Components common to the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof will be omitted.

[0096] (Overall Configuration of Plant) Fig. 12 is a schematic diagram showing the overall configuration of a plant according to the fifth embodiment. As shown in Fig. 12, the refinery plant 3 according to this embodiment further includes a pressure booster 38 that is provided in the treated gas flow path L2 and that boosts the pressure of the treated gas. The pressure booster 38 includes either a pressure booster 38A provided upstream of the gas refinery device 31 or a pressure booster 38B provided downstream of the gas refinery device 31.

[0097] 12 shows an example in which the booster device 38A or 38B is added to the configuration of the first embodiment, but the present invention is not limited to this. The booster device 38A or 38B may be added to the configuration of the second embodiment (FIG. 5), the configuration of the third embodiment (FIG. 7), or the configuration of the fourth embodiment (FIG. 10).

[0098] (Effects) The higher the pressure of the treated gas, the better the performance of removing substances other than the product gas in the gas purification device 31. Therefore, when the purification plant 3 includes the pressure booster 38A provided upstream of the gas purification device 31, the performance of the gas purification device 31 can be improved, and a product gas with a higher purity can be produced.

[0099] Furthermore, if the refining plant 3 has a pressure booster 38B provided downstream of the gas refining device 31, the product gas can be boosted to an appropriate pressure in accordance with the demands of the consumer. Therefore, for example, if the product gas is used in a production process at the facility (company's own factory) where the refining plant 3 is provided, the pressure booster for the production process can be omitted.

[0100] Sixth Embodiment Next, a sixth embodiment will be described in detail with reference to Fig. 13. Components common to the above-described embodiments will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0101] (Overall Configuration of Plant) Fig. 13 is a schematic diagram showing the overall configuration of a plant according to a sixth embodiment. As shown in Fig. 13, an off-gas passage L3 is connected to the pressure booster 38A or 38B, and the treated gas is pressurized using the off-gas discharged from the gas purifier 31 as power. In this embodiment, the pressure booster 38A or 38B is connected to the off-gas passage L3 upstream of the off-gas heating device 32 and downstream of the branch point with the by-product gas passage L31. Similarly, the off-gas passage L3 is connected to the air supply device 33, and the off-gas can be used as power for the air supply device 33.

[0102] While FIG. 13 illustrates an example in which the pressure booster 38A or 38B is added to the configuration of the first embodiment, the present invention is not limited thereto. The pressure booster 38A or 38B may be added to the configuration of the second embodiment ( FIG. 5 ), the configuration of the third embodiment ( FIG. 7 ), or the configuration of the fourth embodiment ( FIG. 10 ). When added to the configuration of the second embodiment ( FIG. 5 ), the pressure booster 38A or 38B is connected to the off-gas flow path L3 upstream of the TSA column 30 and downstream of the branch point with the by-product gas flow path L31. When added to the configuration of the third embodiment ( FIG. 7 ), the pressure booster 38A or 38B is provided in the off-gas flow path L3 upstream of the regeneration gas combustion device 36 and downstream of the branch point with the by-product gas flow path L31. When added to the configuration of the fourth embodiment ( FIG. 10 ), the pressure booster 38A or 38B is provided in the off-gas flow path L3 upstream of the second off-gas heating device 37 and downstream of the branch point with the by-product gas flow path L31.

[0103] (Operation and Effect) In this way, the refining plant 3 can improve the system efficiency by using the off-gas as the power source for the booster 38A or 38B and the air supply device 33.

[0104] Seventh Embodiment Next, a seventh embodiment will be described in detail with reference to Fig. 14. Components common to the above-described embodiments will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0105] (Overall Configuration of Plant) Fig. 14 is a schematic diagram showing the overall configuration of a plant according to the seventh embodiment. As shown in Fig. 14, a nitrogen supply line L33 capable of introducing nitrogen (N2) gas into the off-gas is connected to the off-gas line L3. A nitrogen flow rate adjustment valve V33 capable of adjusting the amount of nitrogen gas supplied is provided in the nitrogen supply line L33.

[0106] The control unit 112 of the control device 10 increases the flow rate of the by-product gas and reduces the flow rate of the off-gas supplied to the off-gas heater 32, as long as there is no problem with the regeneration temperature of the TSA tower 30. The control unit 112 increases the supply rate of nitrogen gas by the amount of the decrease in the off-gas flow rate, thereby ensuring the flow rate of the regeneration gas necessary for regeneration of the TSA tower 30. For example, when the regeneration temperature of the TSA tower 30 is high, the control unit 112 outputs a command to decrease the aperture of the nitrogen flow rate control valve V33 in step ST105 of FIG. 3 , instead of a command to increase the aperture of the by-product gas flow rate control valve V31. This reduces the flow rate of the nitrogen gas, the flow rate of the off-gas supplied to the off-gas heater 32, and the flow rate of the regeneration gas supplied to the TSA tower 30, thereby lowering the regeneration temperature of the TSA tower 30. Furthermore, when the regeneration temperature of the TSA tower 30 is low, the control unit 112 outputs a command to increase the aperture of the nitrogen flow rate control valve V33 instead of a command to decrease the aperture of the by-product gas flow rate control valve V31 in step ST109 of Fig. 3. This increases the flow rate of the nitrogen gas, the flow rate of the off-gas supplied to the off-gas heater 32, and the flow rate of the regeneration gas supplied to the TSA tower 30, thereby making it possible to raise the regeneration temperature of the TSA tower 30. Similar changes can also be applied to steps ST405 and ST409 of Fig. 8.

[0107] In the seventh embodiment, an example has been shown in which the flow rate of the by-product gas is increased and nitrogen gas is introduced to compensate for the decrease in the flow rate of the off-gas supplied to the off-gas heating device 32, but the timing of introducing nitrogen gas is not limited to this. For example, if there is a possibility that increasing the flow rate of the by-product gas will result in a shortage of heat required for regenerating the TSA column 30, it is also possible to introduce nitrogen gas without changing the flow rate of the by-product gas.

[0108] 14 shows an example in which the nitrogen supply flow path L33 and the nitrogen flow rate adjustment valve V33 are added to the configuration of the first embodiment, but the present invention is not limited to this. The nitrogen supply flow path L33 and the nitrogen flow rate adjustment valve V33 may be added to the configurations of the second to sixth embodiments.

[0109] (Effects) As described above, the purification plant 3 further includes a nitrogen supply line L33 connected to the off-gas line L3 and introducing nitrogen gas as a buffer into the off-gas, thereby minimizing fluctuations in the supply rate of the by-product gas and suppressing load fluctuations on by-product gas users. Furthermore, if a sufficient off-gas flow rate for regenerating the TSA column 30 cannot be ensured, additional nitrogen gas can be supplied, thereby appropriately maintaining the flow rate of the regeneration gas supplied to the TSA column 30 and the regeneration temperature of the TSA column 30.

[0110] Eighth Embodiment Next, an eighth embodiment will be described in detail with reference to Fig. 15. Components common to the above-described embodiments will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0111] (Overall Configuration of Plant) Fig. 15 is a schematic diagram showing the overall configuration of a plant according to the eighth embodiment. As shown in Fig. 7, the refinery plant 3 according to this embodiment further includes a circulation gas flow path L34 and a circulation gas compression device 39.

[0112] The circulation gas flow path L34 branches off from the off-gas flow path L3 downstream of the TSA tower 30 and joins the off-gas flow path L3 upstream of the TSA tower 30. In other words, the circulation gas flow path L34 is a flow path for circulating a portion of the regeneration gas used in the TSA tower 30 back to the TSA tower 30 to recycle the regeneration gas.

[0113] The circulation gas flow path L34 is also provided with a circulation gas compressor 39. The circulation gas compressor 39 compresses a portion of the regeneration gas (off-gas) that is discharged from the TSA column 30 and flows into the circulation gas flow path L34.

[0114] 15 shows an example in which the circulation gas compressor 39 is added to the configuration of the first embodiment, but the present invention is not limited to this. The circulation gas compressor 39 may be added to the configurations of the second to sixth embodiments.

[0115] (Effects) With this configuration, the refining plant 3 can appropriately maintain the flow rate of the regeneration gas supplied to the TSA column 30 and the regeneration temperature of the TSA column 30 while increasing the supply amount of the by-product gas, as in the seventh embodiment.

[0116] Ninth Embodiment Next, a ninth embodiment will be described in detail with reference to Figures 16 and 17. Components common to the above-described embodiments are given the same reference numerals, and detailed description thereof will be omitted.

[0117] (Overall Configuration of Plant) Fig. 16 is a schematic diagram showing the overall configuration of a plant according to the ninth embodiment. As shown in Fig. 16, the refinery plant 3 according to this embodiment further includes an online analyzer 40, a shutoff valve V21, and a blow-off valve V22.

[0118] The online analyzer 40 is provided in the treated gas flow path L2 upstream of the gas purification device 31. The online analyzer 40 monitors the concentration of ammonia contained in the treated gas sent out from the TSA tower 30, and switches the shutoff valve V21 and the vent valve V22 between open and closed states.

[0119] The shutoff valve V21 is provided in the treated gas flow path L2 upstream of the gas purification device 31 and downstream of the online analyzer 40. The shutoff valve V21 opens and closes under the control of the online analyzer 40 to allow or block the flow of treated gas to the gas purification device 31.

[0120] The vent valve V22 is provided in a branch flow path L22 that branches off from the treated gas flow path L2 on the upstream side of the shutoff valve V21. The branch flow path L22 is connected to an off-gas flow path L3 that introduces regeneration gas used in the TSA tower 30 into the combustion device 35. The vent valve V22 opens and closes under the control of the online analyzer 40. The vent valve V22 allows or blocks the flow of treated gas to the combustion device 35.

[0121] 16 shows an example in which the online analyzer 40 and the like are added to the configuration of the first embodiment, but the present invention is not limited to this. The online analyzer 40 and the like may be added to the configurations of the second to eighth embodiments.

[0122] 17 is a flowchart showing an example of processing by the online analyzer according to the ninth embodiment. During operation of the refinery plant 3, the shutoff valve V21 is open and the vent valve V22 is closed. First, the online analyzer 40 acquires the ammonia concentration contained in the treated gas (step ST701) and monitors whether the ammonia concentration exceeds a predetermined upper limit of the ammonia concentration (step ST702).

[0123] If the ammonia concentration does not exceed the ammonia concentration upper limit (step ST702; NO), the online analyzer 40 terminates the process. On the other hand, if the ammonia concentration exceeds the ammonia concentration upper limit (step ST702; YES), the online analyzer 40 outputs a close command to the shutoff valve V21 and an open command to the vent valve V22 (step ST703). When the shutoff valve V21 closes in accordance with the command, the supply of treated gas to the gas purification device 31 is stopped. This prevents the adsorbent in the gas purification device 31 from being poisoned by ammonia, for example, if the ammonia concentration in the treated gas becomes high due to an abnormality in the ARU 23 or the TSA column 30. Furthermore, when the vent valve V22 opens in accordance with the command, the treated gas containing ammonia is sent to the combustion device 35, where it is treated by oxidation or thermal decomposition. This prevents the treated gas from being discharged to the outside with a high ammonia concentration.

[0124] Furthermore, when any abnormalities in the ARU 23 or the TSA column 30 are resolved and the ammonia concentration of the treated gas falls below the upper ammonia concentration limit, the online analyzer 40 automatically, or upon receiving an instruction from the manager of the refining plant 3, outputs a close command to the vent valve V22 and an open command to the shutoff valve V21. This allows the refining plant 3 to resume refining the product gas.

[0125] (Effects) In the refining plant 3 according to this embodiment, when the online analyzer 40 detects that the concentration of ammonia contained in the treated gas exceeds the upper limit of the ammonia concentration, the shutoff valve V21 is closed. By doing so, when the ammonia concentration in the treated gas becomes high due to, for example, an abnormality in the ARU 23 or the TSA column 30, it is possible to suppress poisoning of the adsorbent in the gas refining device 31 by ammonia.

[0126] Furthermore, the online analyzer 40 closes the shutoff valve V21 and opens the vent valve V22. In this manner, the treatment gas containing ammonia can be treated by oxidation or thermal decomposition in the combustion device 35. This makes it possible to prevent the treated gas from being discharged to the outside with a high ammonia concentration.

[0127] Tenth Embodiment Next, a tenth embodiment will be described in detail with reference to Fig. 18. Components common to the above-described embodiments will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0128] (Overall configuration of plant) Fig. 18 is a schematic diagram showing the overall configuration of a plant according to the tenth embodiment. As shown in Fig. 18, the refining plant 3 according to this embodiment includes impregnated carbon 41 instead of the online analyzer 40, the shutoff valve V21, and the blast valve V22 of the ninth embodiment.

[0129] The impregnated carbon 41 is provided in the treated gas flow path L2 upstream of the gas purification device 31. The impregnated carbon 41 is a disposable ammonia adsorbent that adsorbs ammonia contained in the treated gas. The impregnated carbon 41 is replaced every time a predetermined period of time has elapsed since the impregnated carbon 41 was attached to the treated gas flow path L2, or every time a predetermined amount or more of treated gas is circulated.

[0130] (Effects) The refining plant 3 according to this embodiment further includes impregnated carbon 41 provided in the treated gas flow path L2 upstream of the gas refining device 31. In this way, the impregnated carbon 41 can absorb ammonia remaining in the treated gas, and poisoning of the adsorbent of the gas refining device 31 by ammonia can be suppressed.

[0131] <Other Embodiments> Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like are possible. That is, in other embodiments, the order of the above-described processes may be changed as appropriate. Furthermore, some processes may be executed in parallel. Note that, in each of the above-described embodiments, an example has been described in which the decomposition plant 2 includes the ARU 23, but this is not limiting. In still other embodiments, the ARU 23 may be omitted from the decomposition plant 2.

[0132] <Additional Notes> The above-described embodiment can be understood, for example, as follows.

[0133] (1) According to the first aspect, the refining plant 3 includes a TSA tower 30 that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from the decomposition gas produced by thermally decomposing ammonia in the decomposition plant 2, a gas purifying device 31 that separates and discharges a product gas purified from the treated gas and an off-gas, an off-gas heating device 32 that heats the off-gas and supplies it to the TSA tower 30 as a regeneration gas for regenerating the adsorbent of the TSA tower 30 after adsorbing the ammonia, a combustion device 35 that supplies a portion of the combustion gas obtained by burning the regeneration gas discharged from the TSA tower 30 as a heat source for the off-gas heating device 32, an off-gas flow path L3 that circulates the off-gas to the combustion device 35, and a combustion gas flow path L5 that circulates the combustion gas to the off-gas heating device 32.

[0134] In this way, the refining plant 3 can establish a highly thermally efficient process in which the off-gas discharged from the gas refining device 31 is used to regenerate the TSA column of the refining plant 3. Furthermore, since the off-gas is utilized in the refining plant 3 without being utilized in the cracking plant 2, the refining plant 3 that refines the product gas (hydrogen) from the cracked gas can be easily added to the existing cracking plant 2 without changing the configuration of the cracking plant 2.

[0135] (2) According to the second aspect, the refining plant 3 according to the first aspect further includes an off-gas heater bypass flow path L51 that branches off from the combustion gas flow path L5 upstream of the off-gas heater 32 and bypasses the off-gas heater 32, a bypass valve V51 provided in the off-gas heater bypass flow path L51, and a control device 10 that increases the aperture of the bypass valve V51 of the off-gas heater bypass flow path L51 when the regeneration temperature in the TSA tower 30 exceeds the regeneration temperature upper limit value, and decreases the aperture of the bypass valve V51 of the off-gas heater bypass flow path L51 when the regeneration temperature is below the regeneration temperature lower limit value.

[0136] In this way, the refining plant 3 can adjust the temperature of the off-gas heated by the off-gas heater 32 to maintain the regeneration temperature of the TSA column 30 within an appropriate temperature range.

[0137] (3) According to the third aspect, the refining plant 3 according to the second aspect further includes an air heating device 34 that supplies air heated with a portion of the combustion gas to the combustion device 35, and the combustion gas flow path L5 adds the combustion gas to the off-gas heating device 32 and circulates it to the air heating device 34.

[0138] In this way, the refining plant 3 can further utilize the combustion gas from the combustion device 35 as a heat source for the air heating device 34 .

[0139] (4) According to a fourth aspect, the refining plant 3 includes a TSA tower 30 that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from the cracked gas generated by thermally decomposing ammonia in the cracking plant 2, a gas purifying device 31 that separates and discharges a product gas purified from the treated gas and an off-gas, a combustion device 35 that supplies a portion of the combustion gas obtained by burning the off-gas to the TSA tower 30 as a heat source for heating a regeneration gas that regenerates the adsorbent in the TSA tower 30 after adsorbing the ammonia, an off-gas flow path L3 that circulates the off-gas to the TSA tower 30, and a combustion gas flow path L5 that circulates the combustion gas to the TSA tower 30 and the air heating device 34.

[0140] In this manner, similarly to the first embodiment, the refining plant 3 utilizes the heat generated in the refining plant 3 without using it in the cracking plant 2, and therefore, the refining plant 3 that refines the product gas (hydrogen) from the cracked gas can be easily added to the existing cracking plant 2 without changing the configuration of the cracking plant 2. Furthermore, since the off-gas heating device 32 is omitted, the refining plant 3 can be made more compact in configuration than in the first embodiment.

[0141] (5) According to the fifth aspect, the refining plant 3 according to the fourth aspect further includes a TSA tower bypass flow path L53 that branches off from the combustion gas flow path L5 upstream of the TSA tower 30 and bypasses the TSA tower 30, a bypass valve V53 provided in the TSA tower bypass flow path L53, and a control device 10 that increases the aperture of the bypass valve V53 of the TSA tower bypass flow path L53 when the regeneration temperature in the TSA tower 30 exceeds the regeneration temperature upper limit, and decreases the aperture of the bypass valve V53 of the TSA tower bypass flow path L53 when the regeneration temperature falls below the regeneration temperature lower limit.

[0142] In this way, the refinery plant 3 can adjust the flow rate of the combustion gas supplied to the TSA column 30 to maintain the regeneration temperature of the TSA column 30 within an appropriate temperature range.

[0143] (6) According to a sixth aspect, the refining plant 3 according to the fifth aspect further includes an air heating device 34 that supplies air heated with a portion of the combustion gas to the combustion device 35, and the combustion gas flow path L5 adds the combustion gas to the TSA column 30 and circulates it through the air heating device 34.

[0144] In this way, the refining plant 3 can further utilize the combustion gas from the combustion device 35 as a heat source for the air heating device 34 .

[0145] (7) According to the seventh aspect, the refining plant 3 includes a TSA tower 30 that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from the decomposition gas generated by thermally decomposing ammonia in the decomposition plant 2, a gas refining device 31 that separates and discharges a product gas purified from the treated gas and an off-gas, a regeneration gas combustion device 36 that combusts at least a portion of the off-gas and supplies it to the TSA tower 30 as regeneration gas for regenerating the adsorbent of the TSA tower 30 after adsorbing the ammonia, and an off-gas flow path L3 that circulates the off-gas to the regeneration gas combustion device.

[0146] In this way, the refining plant 3 can establish a highly thermally efficient process in which the off-gas discharged from the gas refining device 31 is used to regenerate the TSA column of the refining plant 3. Furthermore, since the off-gas is utilized in the refining plant 3 without being utilized in the cracking plant 2, the refining plant 3 that refines the product gas (hydrogen) from the cracked gas can be easily added to the existing cracking plant 2 without changing the configuration of the cracking plant 2.

[0147] (8) According to the eighth aspect, the refining plant 3 according to the seventh aspect further includes a regeneration gas combustion unit bypass flow path L32 that branches off from the off-gas flow path L3 upstream of the regeneration gas combustion unit 36 ​​and bypasses the regeneration gas combustion unit 36, a bypass valve V32 provided in the regeneration gas combustion unit bypass flow path L32, and a control device 10 that increases the aperture of the bypass valve V32 of the regeneration gas combustion unit bypass flow path L32 when the regeneration temperature in the TSA tower 30 exceeds the regeneration temperature upper limit value, and decreases the aperture of the bypass valve V32 of the regeneration gas combustion unit bypass flow path L32 when the regeneration temperature is below the regeneration temperature lower limit value.

[0148] In this way, the refining plant 3 can adjust the flow rate of the off-gas supplied to the regeneration gas combustion device 36 to increase or decrease the flow rate of the regeneration gas supplied to the TSA tower 30, thereby changing the amount of heat provided from the regeneration gas to the TSA tower 30 and maintaining the regeneration temperature of the TSA tower 30 within an appropriate temperature range.

[0149] (9) According to the ninth aspect, the refining plant 3 according to the eighth aspect further includes a combustion device 35 that generates combustion gas by burning the regeneration gas discharged from the TSA tower 30, an air heating device 34 that supplies air heated by the combustion gas to the combustion device 35, and a combustion gas flow path that circulates the combustion gas to the air heating device 34.

[0150] In this way, the refining plant 3 can further utilize the combustion gas from the combustion device 35 as a heat source for the air heating device 34 .

[0151] (10) According to the tenth aspect, the refining plant 3 according to the first, third, or ninth aspect further includes an air heater bypass flow path L52 that branches off from the combustion gas flow path L5 upstream of the air heater 34 and bypasses the air heater 34, and a bypass valve V52 provided in the air heater bypass flow path L52, and the control device 10 increases the opening degree of the bypass valve V52 in the air heater bypass flow path L52 when the concentration of nitrogen oxides contained in the combustion gas exceeds the nitrogen oxide concentration upper limit value.

[0152] In this way, the refining plant 3 can limit the temperature of the combustion device 35 so that the concentration of nitrogen oxides contained in the combustion gas does not exceed the upper limit value.

[0153] (11) According to the eleventh aspect, in the refining plant 3 according to the tenth aspect, the control device 10 increases the aperture of the bypass valve V52 of the air heating device bypass flow path L52 when the combustion device temperature in the combustion device 35 exceeds the combustion device temperature upper limit value, and decreases the aperture of the bypass valve V52 of the air heating device bypass flow path L52 when the combustion device temperature is below the combustion device temperature lower limit value.

[0154] In this way, the refining plant 3 can maintain the temperature of the combustion device 35 within an appropriate temperature range so as not to exceed the design temperature of the combustion device 35 and so as to generate sufficiently heated combustion gas.

[0155] (12) According to the twelfth aspect, in the refining plant 3 according to any one of the first to eleventh aspects, a plurality of TSA towers 30 are provided in parallel, and in one TSA tower 30, a regeneration process is performed in which a regeneration gas is circulated to regenerate the adsorbent, and in the other TSA tower 30, an adsorption process is performed in which ammonia contained in the cracked gas is adsorbed onto the adsorbent and removed, and the treated gas is discharged.

[0156] In this way, the refining plant 3 can continue the adsorption treatment in one of the TSA towers 30 without stopping operation while the regeneration treatment is being performed in the other TSA towers 30. In other words, it is possible to prevent the operating rate of the refining plant 3 from decreasing due to the regeneration treatment of the TSA towers 30.

[0157] (13) According to a thirteenth aspect, the refining plant 3 according to any one of the first to twelfth aspects further includes a second off-gas heating device 37 provided upstream of the off-gas passage L3.

[0158] In this way, the refining plant 3 can adjust the regeneration temperature of the TSA column 30 more accurately by using the second off-gas heater 37 .

[0159] (14) According to the fourteenth aspect, the refining plant 3 relating to any one of the first to thirteenth aspects further includes a treated gas flow path L2 that circulates treated gas from the TSA tower 30 to the gas refining device 31, and a booster device 38 that is provided upstream of the gas refining device 31 or downstream of the gas refining device 31 on the treated gas flow path L2.

[0160] In this way, when the refining plant 3 has a booster device 38A provided upstream of the gas refining device 31, the performance of the gas refining device 31 is improved, and a product gas with higher purity can be produced. Furthermore, when the refining plant 3 has a booster device 38B provided downstream of the gas refining device 31, the product gas can be boosted to an appropriate pressure in accordance with the demands of consumers.

[0161] (15) According to the fifteenth aspect, in the refining plant 3 according to the fourteenth aspect, the booster 38 boosts the pressure of the treated gas using the off-gas discharged from the gas refining device 31 as power.

[0162] In this way, the refining plant 3 can improve system efficiency by using the off-gas as power for the booster 38A or 38B.

[0163] (16) According to a sixteenth aspect, the refining plant 3 according to the third, sixth or ninth aspect further includes an air supply device 33 that supplies air to the air heating device 34 using off-gas discharged from the gas refining device 31 as power.

[0164] (17) According to a seventeenth aspect, the refining plant 3 according to any one of the first to sixteenth aspects further includes a nitrogen supply line L33 connected to the off-gas line L3 and introducing nitrogen gas into the off-gas.

[0165] In this way, the refinery plant 3 can minimize fluctuations in the supply amount of by-product gas and suppress load fluctuations of by-product gas users. Furthermore, if a sufficient off-gas flow rate for regenerating the TSA column 30 cannot be ensured, the flow rate of the regeneration gas supplied to the TSA column 30 and the regeneration temperature of the TSA column 30 can be appropriately maintained by supplying additional nitrogen gas.

[0166] (18) According to the eighteenth aspect, the refining plant 3 according to any one of the first to seventeenth aspects further includes a circulation gas flow path L34 that returns a portion of the regeneration gas discharged from the TSA tower 30 to the TSA tower 30 for circulation, and a circulation gas compression device 39 that is provided in the circulation gas flow path L34 and compresses the regeneration gas flowing through the circulation gas flow path L34.

[0167] In this way, the refinery plant 3 can appropriately maintain the flow rate of the regeneration gas supplied to the TSA column 30 and the regeneration temperature of the TSA column 30 while increasing the supply amount of by-product gas.

[0168] (19) According to the 19th aspect, the refining plant 3 relating to any one of the first to eighteenth aspects further includes a treated gas flow path L2 for circulating treated gas from the TSA tower 30 to the gas refining device 31, an online analyzer 40 provided in the treated gas flow path L2 for monitoring the concentration of ammonia contained in the treated gas, and a shut-off valve V21 provided upstream of the gas refining device 31 in the treated gas flow path L2 for allowing or blocking the flow of treated gas to the gas refining device 31, and the online analyzer 40 closes the shut-off valve V21 when the concentration of ammonia contained in the treated gas exceeds an upper ammonia concentration limit value.

[0169] By doing this, the refining plant 3 can suppress the poisoning of the adsorbent in the gas refining device 31 by ammonia, for example, in the event that the ammonia concentration in the treated gas becomes high due to an abnormality in the ARU 23 or the TSA tower 30.

[0170] (20) According to the twentieth aspect, the refining plant 3 relating to the nineteenth aspect further includes a branch flow path L22 that branches off from the upstream side of the gas refining device 31 of the treated gas flow path L2 and flows the treated gas to the combustion device 35, and a blow-off valve V22 that is provided in the branch flow path L22 and allows or blocks the flow of the treated gas to the combustion device 35.

[0171] In this way, the refining plant 3 can treat the treated gas containing ammonia by oxidation or thermal decomposition in the combustion device 35. This makes it possible to prevent the treated gas from being discharged to the outside with a high ammonia concentration.

[0172] (21) According to a fourteenth aspect, the refining plant 3 according to any one of the first to eighteenth aspects further includes a treated gas flow path L2 that circulates treated gas from the TSA tower 30 to the gas refining device 31, and an ammonia adsorbent 41 that is provided upstream of the gas refining device 31 in the treated gas flow path L2 and adsorbs ammonia contained in the treated gas.

[0173] In this way, the refining plant 3 can absorb the ammonia remaining in the treated gas with the ammonia adsorbent 41, thereby suppressing poisoning of the adsorbent in the gas refining device 31 by ammonia.

[0174] (22) According to a twenty-second aspect, a control method for a refining plant (3) includes a TSA tower (30) that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from cracked gas generated by thermally decomposing ammonia in a cracking plant (2) and discharging the treated gas; a gas purifying device (31) that separates and discharges a product gas purified from the treated gas and an off-gas; an off-gas heating device (32) that heats the off-gas and supplies it to the TSA tower (30) as a regeneration gas for regenerating the adsorbent of the TSA tower (30) after adsorbing the ammonia; a combustion device (35) that supplies a part of the combustion gas obtained by burning the regeneration gas discharged from the TSA tower (30) as a heat source for the off-gas heating device (32); and a combustion device (35) that circulates the off-gas through the combustion device (35). a combustion gas flow path L5 for circulating the combustion gas to the off-gas heating device 32; an off-gas heating device bypass flow path L51 that branches off from the combustion gas flow path L5 upstream of the off-gas heating device 32 and bypasses the off-gas heating device 32; and a bypass valve V51 provided in the off-gas heating device bypass flow path L51, the control method including the steps of increasing the aperture of the bypass valve V51 of the off-gas heating device bypass flow path L51 when the regeneration temperature in the TSA tower 30 exceeds a regeneration temperature upper limit value, and decreasing the aperture of the bypass valve V51 of the off-gas heating device bypass flow path L51 when the regeneration temperature is below a regeneration temperature lower limit value.

[0175] (23) According to a 23rd aspect, a control method for a purification plant 3 includes a TSA tower 30 that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from a cracked gas generated by thermally decomposing ammonia in a cracking plant 2, a gas purification device 31 that separates and discharges a product gas purified from the treated gas and an off-gas, a combustion device 35 that supplies a portion of the combustion gas obtained by burning the off-gas to the TSA tower 30 as a heat source for heating a regeneration gas that regenerates the adsorbent of the TSA tower 30 after adsorption of ammonia, and an off-gas flow path L3 that circulates the off-gas through the TSA tower 30. a combustion gas flow path L5 for circulating combustion gas through a TSA tower 30; a TSA tower bypass flow path L53 branching from the combustion gas flow path L5 upstream of the TSA tower 30 and bypassing the TSA tower 30; and a bypass valve V53 provided in the TSA tower bypass flow path L53, the control method including the steps of increasing the aperture of the bypass valve V53 of the TSA tower bypass flow path L53 when the regeneration temperature in the TSA tower 30 exceeds an upper regeneration temperature limit, and decreasing the aperture of the bypass valve V53 of the TSA tower bypass flow path L53 when the regeneration temperature is below a lower regeneration temperature limit.

[0176] (24) According to a 24th aspect, a control method for a refining plant (3) includes a TSA tower (30) that discharges treated gas obtained by removing unreacted ammonia by adsorbing it onto an adsorbent from a cracked gas generated by thermally decomposing ammonia in a cracking plant (2), a gas purifying device (31) that separates and discharges a product gas purified from the treated gas and an off-gas, a regeneration gas combustion device (36) that combusts at least a portion of the off-gas and supplies it to the TSA tower (30) as a regeneration gas for regenerating the adsorbent of the TSA tower (30) after adsorbing the ammonia, and an off-gas flow control device (36) that circulates the off-gas to the regeneration gas combustion device. a regeneration gas combustion device bypass flow path L32 that branches off from the off-gas flow path L3 upstream of the regeneration gas combustion device and bypasses the regeneration gas combustion device; and a bypass valve V32 provided in the regeneration gas combustion device bypass flow path L32, the control method comprising the steps of increasing the aperture of the bypass valve V32 in the regeneration gas combustion device bypass flow path L32 when the regeneration temperature in the TSA tower 30 exceeds a regeneration temperature upper limit value, and decreasing the aperture of the bypass valve V32 in the regeneration gas combustion device bypass flow path L32 when the regeneration temperature is below a regeneration temperature lower limit value.

[0177] According to the above aspect, the system can be easily added to an existing plant without changing the configuration of the plant.

[0178] REFERENCE SIGNS LIST 1 Plant 2 Cracking plant 3 Purification plant 10 Control device 11 Processor 111 Acquisition unit 112 Control unit 12 Memory 13 Storage 14 Communication interface 21 Ammonia supply unit 22 Ammonia decomposition unit 23 Ammonia recovery unit (ARU) 30, 30A, 30B TSA tower 31 Gas purification unit 32 Off-gas heating unit (first off-gas heating unit) 33 Air supply unit 34 Air heating unit 35 Combustion unit 36 ​​Regeneration gas combustion unit 37 Second off-gas heating unit 38, 38A, 38B Pressure booster 39 Circulation gas compression unit 40 Online analyzer 41 Impregnated coal (ammonia adsorbent) L1 Cracked gas flow path L2 Gas flow path L22 Branch flow path L3 Off-gas flow path L31 By-product gas flow path L32 Regeneration gas combustion unit bypass flow path L33 Nitrogen supply flow path L34 Circulation gas flow path L4 Air flow path L5 Combustion gas flow path L51 Off gas heater bypass flow path L52 Air heater bypass flow path L53 TSA tower bypass flow path V21 Shutoff valve V22 Bleed valve V31 By-product gas flow control valve V32 Bypass valve V33 Nitrogen flow control valve V51 Bypass valve V52 Bypass valve V53 Bypass valve

Claims

1. A refining plant comprising: a TSA tower that discharges treated gas from cracked gas produced by thermally decomposing ammonia in a cracking plant, with unreacted ammonia removed by adsorbing the ammonia onto an adsorbent; a gas purification unit that separates and discharges a product gas purified from the treated gas and an off-gas; an off-gas heating unit that heats the off-gas and supplies it to the TSA tower as regeneration gas for regenerating the adsorbent of the TSA tower after adsorbing ammonia; a combustion unit that supplies a portion of the combustion gas obtained by burning the regeneration gas discharged from the TSA tower as a heat source for the off-gas heating unit; an off-gas flow path that circulates the off-gas to the combustion unit; and a combustion gas flow path that circulates the combustion gas to the off-gas heating unit.

2. The refining plant according to claim 1, further comprising: an off-gas heater bypass flow path branching from the combustion gas flow path upstream of the off-gas heater and bypassing the off-gas heater; a bypass valve provided in the off-gas heater bypass flow path; and a control device that increases the aperture of the bypass valve of the off-gas heater bypass flow path when the regeneration temperature in the TSA tower exceeds a regeneration temperature upper limit value, and decreases the aperture of the bypass valve of the off-gas heater bypass flow path when the regeneration temperature is below a regeneration temperature lower limit value.

3. The refining plant according to claim 2, further comprising an air heating device that supplies air heated by a portion of the combustion gas to the combustion device, and the combustion gas flow path causes the combustion gas to flow through the air heating device in addition to the off-gas heating device.

4. A refining plant comprising: a TSA tower that discharges treated gas from cracked gas produced by thermally decomposing ammonia in a cracking plant, with unreacted ammonia adsorbed onto an adsorbent to remove the ammonia; a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas; a combustion device that supplies a portion of the combustion gas obtained by burning the off-gas to the TSA tower as a heat source for heating regeneration gas that regenerates the adsorbent in the TSA tower after adsorption of ammonia; an off-gas flow path that circulates the off-gas to the TSA tower; and a combustion gas flow path that circulates the combustion gas to the TSA tower.

5. The refining plant according to claim 4, further comprising: a TSA tower bypass flow path branching off from the combustion gas flow path upstream of the TSA tower and bypassing the TSA tower; a bypass valve provided in the TSA tower bypass flow path; and a control device that increases the aperture of the bypass valve of the TSA tower bypass flow path when the regeneration temperature in the TSA tower exceeds an upper regeneration temperature limit, and decreases the aperture of the bypass valve of the TSA tower bypass flow path when the regeneration temperature falls below a lower regeneration temperature limit.

6. The refining plant according to claim 5, further comprising an air heating device that supplies air heated by a portion of the combustion gas to the combustion device, and the combustion gas flow path adds the combustion gas to the TSA column and flows it through the air heating device.

7. A refining plant comprising: a TSA tower that discharges treated gas from cracked gas produced by thermally decomposing ammonia in a cracking plant, with unreacted ammonia removed by adsorbing the ammonia onto an adsorbent; a gas purification unit that separates and discharges a product gas purified from the treated gas and an off-gas; a regeneration gas combustion unit that combusts at least a portion of the off-gas and supplies it to the TSA tower as regeneration gas for regenerating the adsorbent in the TSA tower after adsorbing ammonia; and an off-gas flow path that circulates the off-gas to the regeneration gas combustion unit.

8. The refining plant according to claim 7, further comprising: a regeneration gas combustion device bypass flow path that branches off from the off-gas flow path upstream of the regeneration gas combustion device and bypasses the regeneration gas combustion device; a bypass valve provided in the regeneration gas combustion device bypass flow path; and a control device that increases the aperture of the bypass valve of the regeneration gas combustion device bypass flow path when the regeneration temperature in the TSA tower exceeds a regeneration temperature upper limit value, and decreases the aperture of the bypass valve of the regeneration gas combustion device bypass flow path when the regeneration temperature is below a regeneration temperature lower limit value.

9. The refining plant according to claim 8, further comprising: a combustion device that generates combustion gas by combusting the regeneration gas discharged from the TSA column; an air heating device that supplies air heated by the combustion gas to the combustion device; and a combustion gas flow path that circulates the combustion gas to the air heating device.

10. A refining plant as claimed in claim 3, 6 or 9, further comprising: an air heater bypass flow path that branches off from the combustion gas flow path upstream of the air heater and bypasses the air heater; and a bypass valve provided in the air heater bypass flow path, wherein the control device increases the opening of the bypass valve in the air heater bypass flow path when the concentration of nitrogen oxides contained in the combustion gas exceeds an upper limit value for nitrogen oxide concentration.

11. The refining plant according to claim 10, wherein the control device increases the opening of the bypass valve of the air heater bypass flow path when the combustion device temperature in the combustion device exceeds an upper combustion device temperature limit value, and decreases the opening of the bypass valve of the air heater bypass flow path when the combustion device temperature is below a lower combustion device temperature limit value.

12. The refining plant according to any one of claims 1 to 9, wherein a plurality of the TSA towers are provided in parallel, and in one TSA tower, a regeneration process is carried out in which the regeneration gas is circulated to regenerate the adsorbent, and in the other TSA tower, an adsorption process is carried out in which the ammonia contained in the cracked gas is adsorbed onto the adsorbent and removed, and the treated gas is discharged.

13. The refining plant according to any one of claims 1 to 9, further comprising: a second off-gas heating device provided upstream of the off-gas flow path.

14. The refining plant according to any one of claims 1 to 9, further comprising: a treated gas flow path for circulating the treated gas from the TSA tower to the gas refining device; and a pressure booster provided on the treated gas flow path upstream of the gas refining device or downstream of the gas refining device.

15. The refining plant according to claim 14, wherein the booster device boosts the pressure of the treated gas using the off-gas discharged from the gas refining device as power.

16. The refining plant according to claim 3, 6, or 9, further comprising an air supply device that supplies air to the air heating device using the off-gas discharged from the gas refining device as power.

17. The refining plant according to any one of claims 1 to 9, further comprising a nitrogen supply passage connected to the off-gas passage and for introducing nitrogen gas into the off-gas.

18. The refining plant according to any one of claims 1 to 9, further comprising: a circulation gas flow path for returning a portion of the regeneration gas discharged from the TSA tower to the TSA tower for circulation; and a circulation gas compression device provided in the circulation gas flow path for compressing the regeneration gas flowing through the circulation gas flow path.

19. The refining plant according to any one of claims 1 to 6 and 9, further comprising: a treated gas flow path for flowing the treated gas from the TSA tower to the gas purification device; an online analyzer provided in the treated gas flow path for monitoring the concentration of the ammonia contained in the treated gas; and a shut-off valve provided in the treated gas flow path upstream of the gas purification device for allowing or blocking the flow of the treated gas to the gas purification device, wherein the online analyzer closes the shut-off valve when the concentration of the ammonia contained in the treated gas exceeds an upper ammonia concentration limit.

20. The refining plant according to claim 19, further comprising: a branch flow path that branches off from the treated gas flow path upstream of said gas purification device and distributes said treated gas to said combustion device; and a bleed valve that is provided in said branch flow path and that allows or blocks the flow of said treated gas to said combustion device.

21. The refining plant according to any one of claims 1 to 9, further comprising: a treated gas flow path that distributes the treated gas from the TSA tower to the gas refining device; and an ammonia adsorbent that is provided in the treated gas flow path upstream of the gas refining device and that adsorbs ammonia contained in the treated gas.

22. A control method for a refinery plant comprising: a TSA tower that discharges treated gas from cracked gas produced by thermally decomposing ammonia in a cracking plant, with unreacted ammonia adsorbed onto an adsorbent to remove the ammonia; a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas; an off-gas heating device that heats the off-gas and supplies it to the TSA tower as a regeneration gas for regenerating the adsorbent of the TSA tower after adsorption of ammonia; a combustion device that supplies a portion of the combustion gas obtained by burning the regeneration gas discharged from the TSA tower as a heat source for the off-gas heating device; an off-gas flow path that circulates the off-gas to the combustion device; a combustion gas flow path that circulates the combustion gas to the off-gas heating device; an off-gas heating device bypass flow path that branches off from the combustion gas flow path upstream of the off-gas heating device and bypasses the off-gas heating device; and a bypass valve provided in the off-gas heating device bypass flow path, a step of increasing an aperture of a bypass valve of the off-gas heater bypass passage when a regeneration temperature in the TSA column exceeds a regeneration temperature upper limit value, and decreasing an aperture of the bypass valve of the off-gas heater bypass passage when the regeneration temperature is lower than a regeneration temperature lower limit value.

23. A control method for a refinery plant comprising: a TSA tower that discharges treated gas obtained by removing unreacted ammonia from cracked gas produced by thermally decomposing ammonia in a cracking plant by adsorbing the ammonia onto an adsorbent; a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas; a combustion device that supplies a portion of the combustion gas obtained by burning the off-gas to the TSA tower as a heat source for heating regeneration gas that regenerates the adsorbent in the TSA tower after adsorption of ammonia; an off-gas flow path that circulates the off-gas to the TSA tower; a combustion gas flow path that circulates the combustion gas to the TSA tower; a TSA tower bypass flow path that branches off from the combustion gas flow path upstream of the TSA tower and bypasses the TSA tower; and a bypass valve provided in the TSA tower bypass flow path, A method for controlling a refinery plant, comprising the steps of: increasing an aperture of a bypass valve of the TSA tower bypass flow path when a regeneration temperature in the TSA tower exceeds an upper regeneration temperature limit; and decreasing an aperture of the bypass valve of the TSA tower bypass flow path when the regeneration temperature is below a lower regeneration temperature limit.

24. A control method for a refinery plant comprising: a TSA tower that discharges treated gas from cracked gas produced by thermally decomposing ammonia in a cracking plant, with unreacted ammonia removed by adsorbing the ammonia onto an adsorbent; a gas purification device that separates and discharges a product gas purified from the treated gas and an off-gas; a regeneration gas combustion device that combusts at least a portion of the off-gas and supplies it to the TSA tower as regeneration gas for regenerating the adsorbent in the TSA tower after adsorbing the ammonia; an off-gas flow path that circulates the off-gas to the regeneration gas combustion device; a regeneration gas combustion device bypass flow path that branches off from the off-gas flow path upstream of the regeneration gas combustion device and bypasses the regeneration gas combustion device; and a bypass valve provided in the regeneration gas combustion device bypass flow path, the method comprising the steps of increasing the aperture of the bypass valve of the regeneration gas combustion device bypass flow path when the regeneration temperature in the TSA tower exceeds a regeneration temperature upper limit, and decreasing the aperture of the bypass valve of the regeneration gas combustion device bypass flow path when the regeneration temperature is below a regeneration temperature lower limit. Methods for controlling refinery plants.

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