System for recovering ammonia
The ammonia recovery system with a dual packed bed configuration and controlled concentration/temperature management enhances recovery efficiency and reduces costs and space requirements by optimizing ammonia absorption processes.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MAYEKAWA MFG CO LTD
- Filing Date
- 2025-12-08
- Publication Date
- 2026-06-25
AI Technical Summary
Existing ammonia recovery systems face high introduction costs and require significant installation space due to the use of multiple ammonia absorption towers, which also lead to inefficiencies in ammonia recovery rates.
The system employs an ammonia absorption tower with a dual packed bed configuration, where the gas to be treated contacts dilution water of varying ammonia concentrations, and includes a circulation loop for ammonia water, along with controlled temperature and concentration management using heat exchangers and valves to enhance recovery efficiency.
This configuration increases ammonia recovery rates while reducing the cost and space requirements for ammonia absorption towers, maintaining efficient operation by adjusting ammonia and dilution water concentrations and temperatures.
Smart Images
Figure JP2025042657_25062026_PF_FP_ABST
Abstract
Description
Ammonia recovery system
[0001] The present disclosure relates to an ammonia recovery system.
[0002] Conventionally, an ammonia recovery system for recovering ammonia from a gas to be treated containing ammonia has been known.
[0003] For example, Patent Document 1 describes an absorption treatment system (ammonia recovery system) including a first absorption tower and a second absorption tower for absorbing ammonia in a gas to be treated (gas to be treated) into dilution water.
[0004] Japanese Patent Application Laid-Open No. 2008-255520
[0005] By the way, for example, as described in Patent Document 1, from the viewpoint of increasing the recovery rate of ammonia from the gas to be treated, it is conceivable to circulate the gas to be treated through a plurality of ammonia absorption towers (the first absorption tower and the second absorption tower) and absorb ammonia into dilution water.
[0006] However, when absorbing ammonia in the gas to be treated into dilution water using a plurality of ammonia absorption towers, the introduction cost of the ammonia absorption towers increases according to the number of ammonia absorption towers, and a large space is required for installing the ammonia absorption towers.
[0007] In view of the above circumstances, at least some embodiments of the present invention aim to provide an ammonia recovery system capable of reducing the introduction cost of ammonia absorption towers and reducing the installation space of ammonia absorption towers while increasing the recovery rate of ammonia from the gas to be treated.
[0008] An ammonia recovery system according to at least some embodiments of the present invention includes: an ammonia absorption tower for bringing a gas to be treated containing ammonia into gas-liquid contact with diluent water to absorb ammonia in the gas to be treated into the diluent water; an ammonia water recovery line for recovering ammonia water, in which ammonia has been dissolved in the diluent water, from the bottom of the ammonia absorption tower; a distillation tower for receiving ammonia water supplied via the ammonia water recovery line and separating the ammonia water into ammonia gas and diluent water; and a diluent water supply line for supplying diluent water from the distillation tower to the ammonia absorption tower. The ammonia absorption tower includes: a diluent water inlet into which diluent water from the diluent water supply line is introduced; a first packed bed located below the diluent water inlet; a second packed bed located below the first packed bed; a gas inlet located below the second packed bed into which the gas to be treated is introduced; a storage section located at the bottom of the tower below the gas inlet where ammonia water is stored; and an ammonia water circulation line between the first packed bed and the second packed bed for supplying the ammonia water stored in the storage section.
[0009] According to at least some embodiments of the present invention, the gas to be treated rises so as to pass through the second packed bed and the first packed bed. In contrast, the liquid that comes into gas-liquid contact with the gas to be treated has different ammonia concentrations in the first and second packed beds, respectively. Specifically, the liquid flowing down through the first packed bed is dilution water. The liquid flowing down through the second packed bed is a mixture containing dilution water whose ammonia concentration has increased after passing through the first packed bed and ammonia water with a higher ammonia concentration than the dilution water. In this way, the gas to be treated comes into gas-liquid contact with dilution water, which has a lower ammonia concentration than the mixture flowing down through the second packed bed, in the first packed bed. Therefore, even if the ammonia contained in the gas to be treated cannot be completely recovered in the second packed bed, the ammonia in the gas to be treated can be efficiently recovered. Accordingly, it is possible to increase the ammonia recovery rate from the gas to be treated while reducing the cost of introducing an ammonia absorption tower and reducing the installation space of the ammonia absorption tower.
[0010] This is a diagram showing the overall configuration of an ammonia recovery system according to one embodiment. This is a diagram showing the specific configuration of region A around the ammonia absorption tower in an ammonia recovery system according to one embodiment. This is a diagram showing the specific configuration of region A around the ammonia absorption tower in an ammonia recovery system according to another embodiment. This is a schematic diagram of an ammonia recovery system, a fabric processing machine, and an ammonia liquefaction system according to one embodiment.
[0011] Hereinafter, several embodiments of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.
[0012] Hereinafter, several embodiments of ammonia recovery systems will be described with reference to Figures 1 to 3. Figure 1 is a diagram showing the overall configuration of an ammonia recovery system according to one embodiment. Figure 2 is a diagram showing the specific configuration of region A around the ammonia absorption tower in an ammonia recovery system according to one embodiment. Figure 3 is a diagram showing the specific configuration of region A around the ammonia absorption tower in an ammonia recovery system according to another embodiment.
[0013] As shown in Figure 1, the ammonia recovery system 1 includes an ammonia absorption tower 100, an ammonia water recovery line 20, a distillation tower 40, and a dilution water supply line 60. The ammonia absorption tower 100 is connected to the distillation tower 40 via the ammonia water recovery line 20 and the dilution water supply line 60, respectively.
[0014] The ammonia absorption tower 100 brings the ammonia-containing gas G1 into a gas-liquid contact with dilution water L1, allowing the dilution water L1 to absorb the ammonia from the gas G1. The ammonia water L2, in which the ammonia has dissolved in the dilution water L1, accumulates at the bottom 110 of the ammonia absorption tower 100. The ammonia water L2 accumulated at the bottom 110 of the ammonia absorption tower 100 is recovered via the ammonia water recovery line 20 and supplied to the distillation tower 40. The distillation tower 40 separates the ammonia water L2 received from the ammonia water recovery line 20 into ammonia gas G2 and dilution water L1. The dilution water L1, from which ammonia has been separated from the ammonia water L2, is supplied from the dilution water supply line 60 from the distillation tower 40 to the ammonia absorption tower 100.
[0015] In some embodiments, as shown in Figures 2 and 3, the ammonia absorption tower 100 includes a dilution water inlet 122a into which dilution water L1 from a dilution water supply line 60 is introduced, and a gas inlet 124a into which the gas to be treated G1 is introduced. The dilution water inlet 122a is an opening formed in the dilution water inlet portion 122 of the main body 120 of the ammonia absorption tower 100. Similarly, the gas inlet 124a is an opening formed in the gas inlet portion 124 of the main body 120. The gas inlet 124a is located below the dilution water inlet 122a. The downstream end 60b of the dilution water supply line 60 is connected to the dilution water inlet portion 122 from the outside of the ammonia absorption tower 100. Similarly, the downstream end 2b of the gas to be treated supply line 2 is connected to the gas inlet portion 124 from the outside of the ammonia absorption tower 100.
[0016] Furthermore, as shown in Figures 2 and 3, the ammonia absorption tower 100 includes a first packed bed 140 located below the dilution water inlet 122a, and a second packed bed 150 located below the first packed bed 140. The second packed bed 150 is located above the gas inlet 124a. That is, the gas inlet 124a is located below the second packed bed 150. The first packed bed 140 may be an irregularly packed bed in which the packing material is stacked irregularly, or a regular packed bed in which the packing material is stacked regularly. Similarly, the second packed bed 150 may be an irregularly packed bed or a regular packed bed.
[0017] Furthermore, as shown in Figures 2 and 3, the ammonia absorption tower 100 includes a storage section 112 where ammonia water L2 is stored at the bottom 110 of the tower below the gas inlet 124a, and an ammonia water circulation line 160 for supplying the ammonia water L2 stored in the storage section 112 between the first packed bed 140 and the second packed bed 150. In the embodiment shown in Figures 2 and 3, the ammonia absorption tower 100 includes an ammonia water outlet 114a for taking ammonia water L2 out of the storage section 112, and an ammonia water inlet 126a for supplying ammonia water L2 between the first packed bed 140 and the second packed bed 150. The ammonia water outlet 114a is an opening formed in the ammonia water outlet section 114 of the storage section 112. Similarly, the ammonia water inlet 126a is an opening formed in the ammonia water inlet section 126 provided on the main body 120 at a height between the lower surface 140b of the first packed bed 140 and the upper surface 150a of the second packed bed 150. On the other hand, the ammonia water circulation line 160 includes an upstream end 160a connected to the ammonia water outlet section 114 and a downstream end 160b connected to the ammonia water inlet section 126. A pump 162 may be provided in the ammonia water circulation line 160.
[0018] As shown in Figures 2 and 3, the dilution water L1 introduced from the dilution water inlet 122a comes into gas-liquid contact with the gas to be treated G1 in the first packed bed 140, causing the ammonia concentration to increase. The dilution water L1 that flows down through the first packed bed 140 comes into gas-liquid contact with the gas to be treated G1 in the second packed bed 150 together with the ammonia water L2 supplied from the ammonia water circulation line 160. In other words, in the second packed bed 150, the mixed liquid containing the dilution water L1 and the ammonia water L2 comes into gas-liquid contact with the gas to be treated G1. The mixed liquid that flows down through the second packed bed 150 is stored in the storage section 112 as ammonia water L2, which has a higher ammonia concentration than the dilution water L1. On the other hand, the gas to be treated G1 introduced from the gas inlet 124a rises, passing through the second packed bed 150 and the first packed bed 140. The gas to be treated G1 comes into gas-liquid contact with the aforementioned mixed liquid and diluent L1 in the second packed bed 150 and the first packed bed 140, respectively, and as a result, the ammonia in the gas to be treated G1 is absorbed by the aforementioned mixed liquid and diluent L1. The gas to be treated G1 that has passed through the first packed bed 140 is discharged from the ammonia absorption tower 100 via a gas outlet 132a formed at the top of the tower 130 above the diluent water inlet 122a. The gas to be treated G1 discharged from the gas outlet 132a is sent to an ammonia filtration facility (not shown) via a gas to be treated discharge line 134 connected to the top of the tower 130.
[0019] In the embodiments shown in Figures 1 to 3, the ammonia recovery system 1 is provided in the ammonia water circulation line 160 and includes a first heat exchanger 164 for cooling the ammonia water L2. The first heat exchanger 164 may be a heat exchanger that cools the ammonia water L2 by heat exchange with a heat transfer medium. For example, the first heat exchanger 164 controls the heat exchange between the heat transfer medium and the ammonia water L2 so that the temperature of the ammonia water L2 becomes approximately 15 degrees Celsius. The heat transfer medium as the cooling source for the first heat exchanger 164 is not particularly limited, but may be chilled water CW produced in a chiller (not shown) and supplied to the first heat exchanger 164.
[0020] In the embodiments shown in Figures 1 to 3, the ammonia recovery system 1 includes a concentration measuring device 170 for measuring the ammonia concentration of the ammonia water L2. The ammonia concentration measured by the concentration measuring device 170 is referenced in the control of the first control valve 24, which will be described later. In the embodiments illustrated in Figures 1 and 2, the concentration measuring device 170 is provided in the ammonia water circulation line 160 of the ammonia absorption tower 100. In the embodiment illustrated in Figure 3, the concentration measuring device 170 is provided in the storage section 112 of the ammonia absorption tower 100. In embodiments not shown, the concentration measuring device 170 may be provided upstream of the first control valve 24, which will be described later, in the ammonia water recovery line 20.
[0021] In the embodiments shown in Figures 1 to 3, the ammonia recovery system 1 includes a liquid level measuring device 180 for measuring the liquid level of aqueous ammonia L2 in the storage section 112 of the ammonia absorption tower 100. The liquid level of aqueous ammonia L2 measured by the liquid level measuring device 180 is referenced in the control of the second control valve 66, which will be described later.
[0022] Furthermore, as shown in Figures 2 and 3, the ammonia absorption tower 100 may include a dilution water disperser 190A connected to the dilution water inlet 122 for spraying dilution water L1 onto the upper surface 140a of the first packed bed 140. Similarly, the ammonia absorption tower 100 may include an ammonia water disperser 190B connected to the ammonia water inlet 126 for spraying ammonia water L2 onto the upper surface 150a of the second packed bed 150. The dilution water disperser 190A and the ammonia water disperser 190B are not particularly limited and may be pipe-type liquid dispersers or trough-type liquid dispersers.
[0023] The ammonia water recovery line 20 is a line for recovering ammonia water L2 from the bottom 110 of the ammonia absorption tower 100 configured as described above. In some embodiments, as shown in Figure 1, the ammonia water recovery line 20 includes an upstream end 20a connected to the ammonia absorption tower 100 and a downstream end 20b connected to the distillation tower 40.
[0024] In the embodiments shown in Figures 1 and 2, the upstream end 20a of the ammonia water recovery line 20 is connected to the ammonia water circulation line 160. In this case, the ammonia water L2 drawn into the ammonia water circulation line 160 via the ammonia water outlet 114a is supplied to the ammonia absorption tower 100 via the ammonia water inlet 126a and also supplied to the distillation tower 40 via the ammonia water recovery line 20.
[0025] In the embodiment shown in Figure 3, the upstream end 20a of the ammonia water recovery line 20 is connected to the storage section 112 of the ammonia absorption tower 100. The storage section 112 has an ammonia water outlet 114b, which is different from the ammonia water outlet 114a described above. The ammonia water L2 is recovered into the ammonia water recovery line 20 via the ammonia water outlet 114b. A pump 22 may also be provided in the ammonia water recovery line 20.
[0026] In the embodiments shown in Figures 1 to 3, the ammonia recovery system 1 includes a first control valve 24 provided in the ammonia water recovery line 20. The first control valve 24 is a valve for controlling the amount of ammonia water L2 supplied from the ammonia absorption tower 100 to the distillation tower 40 so that the ammonia concentration measured by the concentration measuring device 170 described above becomes a specified concentration. The first control valve 24 is not particularly limited and may be a valve whose opening degree can be adjusted manually, or a valve whose opening degree is automatically adjusted based on the ammonia concentration measured by the concentration measuring device 170.
[0027] In the embodiments shown in Figures 1 and 2, the opening degree of the first control valve 24 is adjusted according to the ammonia concentration measured by the concentration measuring device 170. Specifically, if the ammonia concentration measured by the concentration measuring device 170 is higher than a specified concentration, the opening degree of the first control valve 24 is increased so that the amount of ammonia water L2 supplied to the distillation column 40 increases. As a result, the amount of ammonia water L2 supplied between the first packed bed 140 and the second packed bed 150 decreases. For example, if the amount of dilution water L1 supplied to the ammonia absorption tower 100 and the ammonia concentration of the gas to be treated G1 are constant, the amount of ammonia water L2 supplied to the dilution water L1 that has passed through the first packed bed 140 decreases, so the ammonia concentration of the mixture containing dilution water L1 and ammonia water L2 decreases, and the ammonia concentration of the mixture (ammonia water L2) that has absorbed ammonia from the gas to be treated G1 in the second packed bed 150 also decreases. Therefore, the ammonia concentration of ammonia water L2 measured by the concentration measuring device 170 decreases. Similarly, if the ammonia concentration measured by the concentration measuring device 170 is lower than the specified concentration, the opening of the first control valve 24 is reduced so that the amount of aqueous ammonia L2 supplied to the distillation column 40 decreases.
[0028] In the embodiment shown in Figure 3, if the opening of the first control valve 24 is increased to increase the amount of ammonia water L2 supplied to the distillation column 40, for example, if the supply amount of dilution water L1 is constant, the liquid level of ammonia water L2 in the storage section 112 will decrease. The amount of ammonia water L2 supplied between the first packed bed 140 and the second packed bed 150 is constant and does not depend on the opening of the first control valve 24. Therefore, by increasing the supply amount of dilution water L1 in accordance with the decrease in ammonia water L2 in the storage section 112, the ammonia concentration of the mixed solution containing dilution water L1 and ammonia water L2 decreases, and the ammonia concentration of ammonia water L2 measured by the concentration measuring device 170 decreases. Similarly, by reducing the opening of the first control valve 24 so that the amount of ammonia water L2 supplied to the distillation column 40 decreases, and by reducing the amount of dilution water L1 supplied in accordance with the increase in ammonia water L2 in the storage section 112, the ammonia concentration of the mixture containing dilution water L1 and ammonia water L2 increases, and the ammonia concentration of ammonia water L2 measured by the concentration measuring device 170 increases. In the embodiment shown in Figure 3, the ammonia concentration of ammonia water L2 may be adjusted using the liquid level measuring device 180 and the second control valve 66 described later.
[0029] In the embodiment shown in Figure 1, the ammonia recovery system 1 is provided in the ammonia water recovery line 20 and includes an ammonia water tank 26 for storing ammonia water L2. The ammonia water tank 26 is provided between the upstream section 20A, which includes the upstream end 20a of the ammonia water recovery line 20, and the downstream section 20B, which includes the downstream end 20b of the ammonia water recovery line 20. In this case, the first control valve 24 may be provided in the upstream section 20A. A pump 28 may be provided in the downstream section 20B.
[0030] The ammonia water tank 26 may include a liquid level sensor (not shown). The liquid level sensor of the ammonia water tank 26 is a sensor for measuring the liquid level of ammonia water L2 in the ammonia water tank 26. In one embodiment, the distillation column 40 may be controlled according to the liquid level of ammonia water L2 measured by the liquid level sensor. Specifically, control may be executed to operate the distillation column 40 when the liquid level of ammonia water L2 is above a specified liquid level, and control may be executed to stop the distillation column 40 when the liquid level of ammonia water L2 is below a specified liquid level.
[0031] In the embodiment shown in Figure 1, the ammonia recovery system 1 is provided in the ammonia water recovery line 20 and includes a preheater 30 for heating the ammonia water L2. The preheater 30 may be a heat exchanger that heats the ammonia water L2 by heat exchange with a heat transfer medium. The heat transfer medium used as the heat source for the preheater 30 is not particularly limited, but may be dilution water L1 supplied to the preheater 30 from the distillation column 40 via the dilution water supply line 60. In the embodiment illustrated in Figure 1, the preheater 30 is provided in the downstream section 20B of the ammonia water recovery line 20.
[0032] The distillation column 40 receives the ammonia water L2 supplied via the ammonia water recovery line 20 described above, and separates the ammonia water L2 into ammonia gas G2 and dilution water L1.
[0033] In some embodiments, as shown in Figure 1, the distillation column 40 includes a gas-liquid contact section 42 for bringing ammonia water L2 and ammonia gas G2 into gas-liquid contact, a storage section 44 for storing dilution water L1 obtained by vaporizing ammonia from ammonia water L2 as ammonia gas G2 in the gas-liquid contact section 42, and a reboiler 46 for heating the dilution water L1 accumulated in the storage section 44. The distillation column 40 is not particularly limited, and the gas-liquid contact section 42 may be a packed column composed of a regular packed bed or a random packed bed, or the gas-liquid contact section 42 may be a tray column composed of cap trays, sieve trays, valve trays, etc.
[0034] In the embodiment shown in Figure 1, the distillation column 40 includes a top section 48, an ammonia gas discharge line 50 for discharging ammonia gas G2 from the top section 48, a partial condenser 52 provided in the ammonia gas discharge line 50 for cooling the ammonia gas G2, and a drain water line 54 for returning drain water L3 separated from the ammonia gas G2 in the partial condenser 52 back to the distillation column 40. The partial condenser 52 may be a heat exchanger that cools the ammonia gas G2 by heat exchange with a heat transfer medium. The heat transfer medium as the cooling source for the partial condenser 52 is not particularly limited, but may be chilled water CW produced in a chiller (not shown) and supplied to the partial condenser 52.
[0035] As shown in Figure 1, the ammonia water L2 received in the gas-liquid contact section 42 of the distillation column 40 comes into gas-liquid contact with high-temperature ammonia gas G2 passing upward through the gas-liquid contact section 42. As the ammonia water L2 flows down the gas-liquid contact section 42 while being heated by the ammonia gas G2, it releases some of the ammonia as ammonia gas G2. The ammonia water L2 with reduced ammonia concentration is stored in the storage section 44 as dilution water L1. On the other hand, high-temperature ammonia gas G2 is generated when the dilution water L1 stored in the storage section 44 is heated by the reboiler 46, and the ammonia remaining in the dilution water L1 vaporizes.
[0036] The ammonia gas G2 that has passed through the gas-liquid contact section 42 reaches the top of the column 48 and is discharged from the distillation column 40 via the ammonia gas discharge line 50. The ammonia gas G2 is cooled in the partial condenser 52, and the water in the ammonia gas G2 is removed. The water removed from the ammonia gas G2 is returned to the distillation column 40 as drain water L3 via the drain water line 54.
[0037] The dilution water supply line 60 is a line for supplying dilution water L1 from the distillation column 40 to the ammonia absorption column 100. In some embodiments, as shown in Figure 1, the dilution water supply line 60 includes an upstream end 60a connected to the distillation column 40 and a downstream end 60b connected to the dilution water inlet 122 of the ammonia absorption column 100. A pump 62 may also be provided in the dilution water supply line 60.
[0038] In the embodiment shown in Figure 1, the ammonia recovery system 1 is provided in the dilution water supply line 60 and includes a second heat exchanger 64 for cooling the dilution water L1. The second heat exchanger 64 may be a heat exchanger that cools the dilution water L1 by heat exchange with a heat transfer medium. For example, the second heat exchanger 64 controls the heat exchange between the heat transfer medium and the dilution water L1 so that the temperature of the dilution water L1 is about 20 degrees, preferably about 15 degrees. The heat transfer medium as the cooling source for the second heat exchanger 64 is not particularly limited, but may be chilled water CW produced in a chiller (not shown) and supplied to the second heat exchanger 64.
[0039] In the embodiment shown in Figure 1, the ammonia recovery system 1 includes a second control valve 66 provided in the dilution water supply line 60. The second control valve 66 is a valve for controlling the amount of dilution water L1 supplied from the distillation column 40 to the ammonia absorption column 100 so that the liquid level measured by the liquid level measuring device 180 described above reaches a specified liquid level. The second control valve 66 is not particularly limited and may be a valve whose opening degree can be adjusted manually, or a valve whose opening degree is automatically adjusted based on the liquid level measured by the liquid level measuring device 180.
[0040] The opening degree of the second control valve 66 may be controlled according to the ammonia concentration of the gas G1 to be treated. Specifically, when the ammonia concentration of the gas G1 to be treated is high, the ammonia concentration of the ammonia water L2 in the ammonia absorption tower 100 increases, so the opening degree of the first control valve 24 is increased as described above. As a result, the liquid level in the storage section 112 of the ammonia absorption tower 100 decreases, so the opening degree of the second control valve 66 is increased to increase the supply amount of dilution water L1. Similarly, when the ammonia concentration of the gas G1 to be treated is low, the ammonia concentration of the ammonia water L2 in the ammonia absorption tower 100 decreases, so the opening degree of the first control valve 24 is decreased as described above. As a result, the liquid level in the storage section 112 of the ammonia absorption tower 100 increases, so the opening degree of the second control valve 66 is decreased to reduce the supply amount of dilution water L1.
[0041] In the embodiment shown in Figure 1, the ammonia recovery system 1 is provided in the dilution water supply line 60 and includes a dilution water tank 68 for storing dilution water L1. The dilution water tank 68 is provided between the upstream section 60A, which includes the upstream end 60a of the dilution water supply line 60, and the downstream section 60B, which includes the downstream end 60b of the dilution water supply line 60. In this case, the second control valve 66 is provided in the downstream section 60B. A pump 70 may also be provided in the downstream section 60B. In the embodiment illustrated in Figure 1, the ammonia recovery system 1 includes a cooler 72 provided in the upstream section 60A. When the dilution water L1 flowing through the dilution water supply line 60 is used as a heat source for the preheater 30, the cooler 72 is provided between the preheater 30 and the dilution water tank 68. The cooler 72 may be a heat exchanger that cools the dilution water L1 by heat exchange with a heat transfer medium. The heat transfer medium used as the cooling source for the cooler 72 is not particularly limited, but may be chilled water CW produced in a chiller (not shown) and supplied to the cooler 72.
[0042] The ammonia recovery system 1 with the above configuration is connected to a fabric processing machine 3 for fabric modification using ammonia, thereby recovering ammonia contained in the treated gas G1 discharged from the fabric processing machine 3. Several embodiments of the fabric processing machine 3 will be described below with reference to Figure 4. In the following, parts common to the configuration described above in Figures 1 to 3 will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate. Figure 4 is a schematic diagram of an ammonia recovery system, fabric processing machine, and ammonia liquefaction system according to one embodiment.
[0043] As shown in Figure 4, the ammonia recovery system 1 is connected to the fabric processing machine 3 via the treated gas supply line 2. In some embodiments, as shown in Figure 4, the fabric processing machine 3 includes a processing chamber 3A for modifying the fabric C to be processed using ammonia, and a volatilization chamber 3B for removing ammonia remaining attached to the fabric C to be processed. The upstream end 2a of the treated gas supply line 2 is connected to the volatilization chamber casing 320 that forms the volatilization chamber 3B. The ammonia gas in the volatilization chamber 3B is supplied to the ammonia recovery system 1 as the treated gas G1 via the treated gas supply line 2.
[0044] As shown in FIG. 4, the processing chamber 3A is formed by a processing chamber casing 310. The processing chamber casing 310 is formed with a processing chamber inlet 312 for receiving the workpiece cloth C and a processing chamber outlet 314 for taking out the workpiece cloth C. Further, the processing chamber casing 310 houses a liquid ammonia tank 316 for immersing the workpiece cloth C in the liquid ammonia L4 and a heating cylinder 318 for heating the workpiece cloth C taken out from the liquid ammonia tank 316. The volatilization chamber casing 320 is adjacent to the processing chamber casing 310. The volatilization chamber casing 320 is formed with a volatilization chamber inlet 322 for receiving the workpiece cloth C that has passed through the processing chamber outlet 314 and a volatilization chamber outlet 324 for taking out the workpiece cloth C. Further, the volatilization chamber casing 320 houses a volatilization cylinder 326 for removing the ammonia remaining and adhering to the workpiece cloth C.
[0045] In the embodiment shown in FIG. 4, the cloth processing machine 3 includes seal boxes 4 (4A, 4B, 4C) for preventing leakage of ammonia from the cloth processing machine 3. The upstream end 2a of the processing gas supply line 2 is connected to the seal boxes 4 (4A, 4B, 4C) in addition to the volatilization chamber 3B. The seal gas in the seal boxes 4 (4A, 4B, 4C) is supplied to the ammonia recovery system 1 as the processing gas G1 together with the ammonia gas in the volatilization chamber 3B. At this time, since the internal pressure of the seal boxes 4 (4A, 4B, 4C) becomes lower than the atmospheric pressure, it becomes difficult for ammonia to leak from the cloth processing machine 3. In the embodiment illustrated in FIG. 4, the seal box 4A is installed at the processing chamber inlet 312. The seal box 4B is installed at the processing chamber outlet 314 and the volatilization chamber inlet 322. The seal box 4C is installed at the volatilization chamber outlet 324.
[0046] The fabric to be processed C is introduced into the processing chamber 3A via the processing chamber inlet 312 and drawn into the liquid ammonia tank 316. In the liquid ammonia tank 316, the fabric to be processed C, immersed in liquid ammonia L4, is wrapped around the heating cylinder 318 and heated. As the fabric to be processed C is heated, most of the ammonia impregnated in the fabric to evaporate. After most of the ammonia has been removed by the heating cylinder 318, the fabric to be processed C is introduced into the volatilization chamber 3B via the processing chamber outlet 314 and the volatilization chamber inlet 322. The fabric to be processed C is wrapped around the volatilization cylinder 326 and high-temperature (e.g., 98 degrees Celsius) steam is blown onto it. Any remaining ammonia adhering to the fabric to be processed C is vaporized by the high-temperature steam. The fabric to be processed C, from which the remaining ammonia has been removed, is taken out from the volatilization chamber outlet 324.
[0047] The ammonia gas concentration of the treated gas G1 supplied from the volatilization chamber 3B to the ammonia recovery system 1 varies depending on the operating conditions of the fabric processing machine 3 and the type of fabric C being processed. For example, when the movement speed of the fabric C passing through the fabric processing machine 3 is relatively slow, such as immediately after starting or just before stopping the machine, the amount of ammonia vaporized from the fabric C is relatively small, resulting in a relatively low ammonia concentration in the treated gas G1. On the other hand, as the movement speed of the fabric C passing through the fabric processing machine 3 increases, the amount of ammonia vaporized from the fabric C increases, and the ammonia concentration in the treated gas G1 rises. Furthermore, the greater the amount of ammonia held by the fabric C, the greater the amount of ammonia vaporized from the fabric C, and the higher the ammonia concentration in the treated gas G1. The amount of ammonia held by the fabric C varies depending on, for example, the weight and type of fibers of the fabric C. The movement speed of the fabric C passing through the fabric processing machine 3 is determined, for example, based on the upper limit of the ammonia recovery amount of the ammonia absorption tower 100 and the type of fabric C being processed.
[0048] Incidentally, in order to liquefy ammonia gas and reuse it in the fabric processing machine 3, an ammonia liquefaction system 6 can be used together with the fabric processing machine 3 and the ammonia recovery system 1. The ammonia liquefaction system 6 liquefies the ammonia gas G2 led from the processing chamber 3A and the distillation column 40, and supplies the liquid ammonia L4 to the liquid ammonia tank 316. As shown in FIG. 4, the ammonia liquefaction system 6 includes an ammonia liquefier 610 for liquefying the ammonia gas G2 led from the fabric processing machine 3 and the ammonia recovery system 1 to obtain the liquid ammonia L4, and a liquid ammonia line 620 for leading the liquid ammonia L4 from the ammonia liquefier 610 to the liquid ammonia tank 316 of the fabric processing machine 3. The ammonia liquefier 610 receives the ammonia gas G2 in the processing chamber 3A via the ammonia gas line 5, and also receives the ammonia gas G2 discharged from the distillation column 40 via the ammonia gas discharge line 50. A receiver 630 for storing the liquid ammonia L4 is provided in the liquid ammonia line 620.
[0049] As shown in FIG. 4, the ammonia liquefaction system 6 includes a refrigerator 640 having a refrigeration cycle for cooling the refrigerant R supplied to the ammonia liquefier 610. The ammonia liquefier 610 liquefies the ammonia gas G2 using the refrigerant R supplied from the refrigerator 640 as a cold heat source. The refrigerant R cooled by the refrigerator 640 is not particularly limited, and may be an ammonia refrigerant.
[0050] Summarizing the characteristic configurations of the ammonia recovery system 1 according to some of the above embodiments, they are as follows.
[0051] [1] An ammonia recovery system (1) according to several embodiments comprises: an ammonia absorption tower (100) for bringing a gas to be treated (G1) containing ammonia into gas-liquid contact with dilution water (L1) to absorb ammonia in the gas to be treated (G1) into the dilution water (L1); an ammonia water recovery line (20) for recovering ammonia water (L2) in which ammonia has been dissolved in dilution water (L1) from the bottom (110) of the ammonia absorption tower (100); a dilution tower (40) for receiving ammonia water (L2) supplied via the ammonia water recovery line (20) and separating the ammonia water (L2) into ammonia gas (G1) and dilution water (L1); and a dilution water supply line (60) for supplying dilution water (L1) from the dilution tower (40) to the ammonia absorption tower (100), wherein the ammonia absorption tower (100) comprises: a dilution water inlet (122a) into which dilution water (L1) from the dilution water supply line (60) is introduced, The apparatus includes: a first packed bed (140) located below a dilution water inlet (122a); a second packed bed (150) located below the first packed bed (140); a gas inlet (124a) located below the second packed bed (150) into which the gas to be treated (G1) is introduced; a storage section (112) located at the bottom of the tower (110) below the gas inlet (124a) where ammonia water (L2) is stored; and an ammonia water circulation line (160) for supplying the ammonia water (L2) stored in the storage section (112) between the first packed bed (140) and the second packed bed (150).
[0052] An ammonia absorption tower absorbs ammonia from the gas to be treated by bringing the diluent water flowing down from the top of the tower into contact with the gas to be treated rising from the bottom of the tower. The ammonia water, in which ammonia has dissolved, is stored at the bottom of the ammonia absorption tower. Meanwhile, the gas to be treated, which has released ammonia, is discharged from the top of the ammonia absorption tower. From the viewpoint of increasing the ammonia recovery rate from the gas to be treated, it is conceivable to circulate the gas to be treated through multiple ammonia absorption towers. When multiple ammonia absorption towers are used, the process of guiding the gas to be treated discharged from the preceding ammonia absorption tower to the subsequent ammonia absorption tower and bringing it into contact with the diluent water is repeated. However, when multiple ammonia absorption towers are used, issues arise such as increased introduction costs for the ammonia absorption towers and the need for additional installation space for the ammonia absorption towers. According to the configuration in [1] above, in the ammonia absorption tower (100), the gas to be treated (G1) and the diluent water (L1) are in gas-liquid contact in the first packed bed (140) and the second packed bed (150). The gas to be treated (G1) rises, passing through the second packed bed (150) and the first packed bed (140). In contrast, the liquid that comes into gas-liquid contact with the gas to be treated (G1) has different ammonia concentrations in the first packed bed (140) and the second packed bed (150). Specifically, the liquid flowing down through the first packed bed (140) is diluent water (L1). The liquid flowing down through the second packed bed (150) is a mixture containing diluent water (L1) whose ammonia concentration has increased after passing through the first packed bed (140), and ammonia water (L2) with a higher ammonia concentration than diluent water (L1). In this way, the gas to be treated (G1) comes into gas-liquid contact with diluent water (L1), which has a lower ammonia concentration than the mixed liquid flowing down the second packed bed (150), in the first packed bed (140). As a result, ammonia in the gas to be treated (G1) that was not absorbed in the second packed bed (150) can be effectively recovered in the first packed bed (140). Therefore, the ammonia recovery rate from the gas to be treated (G1) can be increased while reducing the cost of introducing the ammonia absorption tower (100) and the space required for installing the ammonia absorption tower (100) can be reduced.
[0053] [2] In some embodiments, the ammonia recovery system (1) in the configuration of [1] further comprises a first heat exchanger (164) provided in the ammonia water circulation line (20) for cooling the ammonia water (L2).
[0054] When ammonia dissolves in dilution water (L1), the temperature of the ammonia solution (L2) rises. As the temperature of the ammonia solution (L2) rises, the solubility of ammonia in the ammonia solution (L2) decreases, which may reduce the ammonia recovery rate from the gas to be treated (G1). In this regard, according to the configuration of [2] above, the ammonia solution (L2) is cooled by the first heat exchanger (164) before it is introduced between the first packed bed (140) and the second packed bed (150). Therefore, the decrease in the ammonia recovery rate from the gas to be treated (G1) can be suppressed.
[0055] [3] In some embodiments, in the configuration of [1] or [2] above, the ammonia recovery system (1) further comprises: a concentration measuring device (170) for measuring the ammonia concentration of ammonia water (L2); and a first control valve (24) provided in the ammonia water recovery line (20) for controlling the amount of ammonia water (L2) supplied from the ammonia absorption tower (100) to the distillation tower (40) so that the ammonia concentration measured by the concentration measuring device (170) becomes a specified concentration.
[0056] The operating efficiency of the distillation column (40) depends on the ammonia concentration of the aqueous ammonia (L2) supplied from the ammonia absorption column (100) to the distillation column (40). If the concentration of the aqueous ammonia (L2) supplied to the distillation column (40) is not suitable for the operation of the distillation column (40), the distillation column (40) may not be able to operate effectively. Incidentally, the concentration of aqueous ammonia (L2) changes depending on the balance between the circulation rate of aqueous ammonia (L2) in the ammonia absorption column (100) and the supply rate of aqueous ammonia (L2) to the distillation column (40). Specifically, if the circulation rate of aqueous ammonia (L2) is high (the supply rate is low), the concentration of aqueous ammonia (L2) will be high. On the other hand, if the circulation rate of aqueous ammonia (L2) is low (the supply rate is high), the concentration of aqueous ammonia (L2) will be low. In this regard, according to the configuration described in [3] above, since a first control valve (24) is provided in the ammonia water recovery line (20), the amount of ammonia water (L2) supplied from the ammonia absorption tower (100) to the distillation tower (40) can be controlled so that the ammonia concentration reaches a specified concentration. Therefore, ammonia water (L2) adjusted to an ammonia concentration suitable for the operation of the distillation tower (40) can be supplied to the distillation tower (40), allowing the distillation tower (40) to be operated effectively.
[0057] [4] In some embodiments, in any of the configurations of [1] to [3] above, the ammonia recovery system (1) further comprises a second heat exchanger (64) provided in the dilution water supply line (60) for cooling the dilution water (L1).
[0058] As described in [2] above, the temperature rise of the ammonia water (L2) due to ammonia absorption may reduce the ammonia recovery rate from the gas to be treated (G1). In this regard, according to the configuration in [4] above, the dilution water (L1) is cooled by the second heat exchanger (64) before being introduced into the ammonia absorption tower (100) from the dilution water inlet (122a). Therefore, the decrease in the ammonia recovery rate from the gas to be treated (G1) can be suppressed.
[0059] [5] In some embodiments, in any of the configurations of [1] to [4] above, the ammonia recovery system (1) further comprises: a liquid level measuring device (180) for measuring the liquid level of ammonia water (L2) in the storage section (112) of the ammonia absorption tower (100); and a second control valve (66) provided in the dilution water supply line (60) for controlling the amount of dilution water (L1) supplied from the distillation tower (40) to the ammonia absorption tower (100) so that the liquid level measured by the liquid level measuring device (180) becomes a specified liquid level.
[0060] The operating efficiency of the distillation column (40) depends on the concentration of the ammonia water (L2) supplied from the ammonia absorption column (100) to the distillation column (40). If the concentration of the ammonia water (L2) supplied to the distillation column (40) is unstable, the distillation column (40) may not be able to operate effectively. Incidentally, depending on the amount of dilution water (L1) supplied to the ammonia absorption column (100), the liquid level of the ammonia water (L2) in the storage section (112) of the ammonia absorption column (100) may change over time. When the liquid level of the ammonia water (L2) fluctuates, it may be difficult to maintain a constant concentration of the ammonia water (L2). In this regard, according to the configuration of [5] above, since a second control valve (66) is provided in the dilution water supply line (60), the amount of dilution water (L1) supplied to the ammonia absorption column (100) can be controlled so that the liquid level of the ammonia water (L2) reaches a specified level. Therefore, a constant ammonia concentration of aqueous ammonia (L2) can be stably supplied to the distillation column (40), allowing the distillation column (40) to be operated effectively.
[0061] Although several embodiments of the present invention have been described above, it goes without saying that modifications to the above embodiments are permitted as long as they do not deviate from the spirit of the present invention.
[0062] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances sufficient to achieve the same function. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" shall not only describe states of being strictly equal, but also describe states where tolerances or differences exist to the extent that the same function is achieved. Furthermore, in this specification, expressions describing shapes such as quadrilaterals or cylindrical shapes shall not only describe geometrically precise quadrilaterals or cylindrical shapes, but also describe shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect is achieved. In addition, in this specification, expressions such as "equipment," "includes," or "possesses" a component are not exclusive expressions that exclude the existence of other components.
[0063] 1: Ammonia recovery system 20: Ammonia water recovery line 24: First control valve 40: Distillation column 60: Dilution water supply line 64: Second heat exchanger 66: Second control valve 100: Ammonia absorption column 110: Column bottom 112: Storage section 122a: Dilution water inlet 124a: Gas inlet 140: First packed bed 150: Second packed bed 160: Ammonia water circulation line 164: First heat exchanger 170: Concentration measuring device 180: Liquid level measuring device G1: Gas to be treated G2: Ammonia gas L1: Dilution water L2: Ammonia water
Claims
1. An ammonia absorption tower for bringing a gas containing ammonia into gas-liquid contact with dilution water to absorb the ammonia in the gas to be treated into the dilution water; an ammonia water recovery line for recovering the ammonia water in which the ammonia has dissolved in the dilution water from the bottom of the ammonia absorption tower; a distillation tower for receiving the ammonia water supplied via the ammonia water recovery line and separating the ammonia water into ammonia gas and the dilution water; and a dilution water supply line for supplying the dilution water from the distillation tower to the ammonia absorption tower, wherein the ammonia absorption tower comprises: a dilution water inlet into which the dilution water from the dilution water supply line is introduced; a first packed bed located below the dilution water inlet; a second packed bed located below the first packed bed; a gas inlet located below the second packed bed into which the gas to be treated is introduced; a storage section located at the bottom of the tower below the gas inlet into which the ammonia water is stored; and an ammonia water circulation line between the first packed bed and the second packed bed for supplying the ammonia water stored in the storage section. Ammonia recovery system including [specific component].
2. The ammonia recovery system according to claim 1, further comprising a first heat exchanger provided in the ammonia water circulation line for cooling the ammonia water.
3. The ammonia recovery system according to claim 1 or 2, further comprising: a concentration measuring device for measuring the ammonia concentration of the ammonia water; and a first control valve provided in the ammonia water recovery line for controlling the amount of ammonia water supplied from the ammonia absorption tower to the distillation tower so that the ammonia concentration measured by the concentration measuring device becomes a specified concentration.
4. The ammonia recovery system according to claim 1 or 2, further comprising a second heat exchanger provided in the dilution water supply line for cooling the dilution water.
5. The ammonia recovery system according to claim 1 or 2, further comprising: a liquid level measuring device for measuring the liquid level of the ammonia water in the storage section of the ammonia absorption tower; and a second control valve provided in the dilution water supply line for controlling the amount of dilution water supplied from the distillation tower to the ammonia absorption tower so that the liquid level measured by the liquid level measuring device becomes a specified liquid level.