Stripping device

Abstract

To provide a stripping device capable of lowering the height of a stripping tower.SOLUTION: Ammonia-containing drain water is passed through a first stripping module 1A, a second stripping module 1B, and a third stripping module 1C in this order. Gas for gas diffusion is passed through the stripping modules 1C, 1B and 1A in this order. Treatment water is extracted from circulation piping 6 by piping 7. Only one filling layer 3 is arranged within the stripping modules 1A-1C.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a stripping device for stripping gas-containing water such as ammonia-containing water.

Background Art

[0002] As a method for treating ammonia-containing wastewater, there is a stripping treatment. As the stripping gas (or carrier gas), usually air or steam is used. Whether to use air or steam is appropriately selected according to individual conditions. Generally, simple air is used in a small stripping tower (stripper), and efficient steam is used in a large stripping tower.

[0003] The ammonia-containing gas discharged from the stripping tower is used for (1) oxidative decomposition treatment by a catalyst, (2) utilization as a raw material for producing ammonium sulfate, (3) recovery as concentrated ammonia water, etc. When there is no distribution market for ammonium sulfate or ammonia water, it is used for (1) oxidative decomposition treatment by a catalyst.

[0004] Fig. 3 shows the configuration of a conventional stripping device. The water to be treated (wastewater containing ammonia) is supplied to the water sprinkler 2a at the upper part of the stripping tower 1 through the water supply pipe 2 for the water to be treated, and is sprinkled from the water sprinkler 2a. The sprinkled water flows down while contacting the gas in the packing layer 3, and becomes the bottom liquid L from which ammonia has been stripped. In this conventional example, the packing layer 3 is provided in two stages vertically, but it may be three or more stages.

[0005] ​​​​A nozzle 11 is installed to inject gas into the lower part of the tower below the packed bed 3. The gas injected from this nozzle 11 rises through the packed bed 3 and comes into contact with the wastewater, causing the ammonia in the wastewater to be released as gas. The released gas and water vapor generated by the evaporation of water rise through the tower along with the air, pass through the demister (mist separator) 12, and the water droplets are removed.

[0007] This ammonia and water vapor-containing gas flows out from the top of the tower into piping 13, is heated in the heat exchanger 14 to above the dew point, preferably 280-380°C, particularly around 320-350°C, and then passes through piping 15 to be introduced into the catalytic reactor 16. A catalytic reactor inlet heater may be provided in the middle of piping 15.

[0008] Ammonia in the gas is oxidized upon contact with catalyst 16a in catalytic reactor 16. This oxidation reaction is exothermic, causing the gas temperature to rise. The gas flowing out of catalytic reactor 16 is introduced into heat exchanger 14 via piping 17, where it cools down through heat exchange with the gas flowing out of the radiating column. This gas is then supplied to nozzle 11 via piping 18, blower 19, and piping 20. A portion of the gas blown out by blower 19 is sent to chimney 22 via piping 21, which branches off from piping 20, and discharged outside the system. Downstream of the branching point of piping 21 (towards nozzle 11), air (atmosphere) is added via blower 23 and piping 24. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2014-144445 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] As described above, in an ammonia stripping facility, ammonia wastewater is brought into gas-liquid contact in a stripping tower, releasing the ammonia components in the water into the gaseous side. The ammonia components that have migrated to the gaseous side are then treated by methods such as catalytic oxidation to render them harmless.

[0011] Because this stripping tower involves gas-liquid contact in a packed bed, a very tall stripping tower is required to adequately release ammonia components, and a large, elevated support structure is necessary to support and operate the stripping tower.

[0012] For these reasons, the conventional equipment had the following problems: (1) A tall tower is required, necessitating the construction of a robust foundation and a large, elevated operating platform to support and operate the tower. This occupies a large installation space and incurs costs for the construction of the foundation and platform. (2) The height of the packed bed in the tower must be designed according to the ammonia concentration at the inlet, and the design must be tailored to the conditions of each site. (3) In order to prevent heat loss from the tower itself, it is necessary to insulate the entire structure, but because it is a cylindrical shell and has a high total height, insulation work is extremely difficult and the construction costs are high. (4) In particular, in wastewater from the electronics industry, impurities in the wastewater can cause crystalline deposits to form in the packed bed, potentially leading to blockage. To remove these deposits, it was necessary to shut down the entire facility and perform chemical cleaning or replace the packing material.

[0013] One aspect of the present invention aims to provide a stripping device that can reduce the height of the stripping tower. [Means for solving the problem]

[0014] A stripping apparatus according to one aspect of the present invention is a stripping apparatus having first to n (n is 2 or more) stripping modules in which gas-containing water comes into contact with a gas for gas release in a packed bed to perform gas release treatment, wherein raw water to be treated is supplied to the first stripping module, raw gas for gas release is supplied to the nth stripping module, the bottom liquid of the j (j is 1 or more but less than n) stripping module is supplied to the (j+1) stripping module as water to be treated, gas from the top of the k (k is greater than 1 and less than or equal to n) stripping module is supplied to the (k-1) stripping module as gas for gas release, and treated water is extracted from the bottom liquid of the nth stripping module.

[0015] In one aspect of the present invention, n is 2 to 5.

[0016] In one aspect of the present invention, a circulation line is provided for circulating the bottom liquid of the n stripping module to the first stripping module, and treated water is taken out from the circulation line.

[0017] In one aspect of the present invention, the tank of each stripping module is a rectangular tube with a square horizontal cross-section.

[0018] In one aspect of the present invention, each stripping module is provided with only one packing layer. [Effects of the Invention]

[0019] In one aspect of the present invention, the ammonia stripping tower section is divided and modularized, thereby reducing the overall height of the tower and eliminating the need for an elevated operating platform.

[0020] In one aspect of the present invention, the modular standard design allows for easy modification of the number of connected towers according to the raw water concentration, enabling simple equipment design. Furthermore, because the modular stripping tower has low internal pressure and is not a pressure vessel, a rectangular tower can be realized, resulting in excellent space efficiency and a tower design that is easy to modularize.

Brief Description of the Drawings

[0021] [Figure 1] It is a configuration diagram of a stripping device according to an embodiment. [Figure 2] It is a schematic perspective view of a stripping module. [Figure 3] It is a configuration diagram of a conventional stripping device.

Modes for Carrying Out the Invention

[0022] Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 shows a stripping device according to an embodiment of the present invention.

[0023] In this embodiment, instead of the stripping tower 1, stripping modules 1A, 1B, and 1C each having only one stage of the packing layer 3 are installed. Note that two or four or more, for example, five stripping modules may be installed. The configuration of the stripping modules 1A to 1C is the same as that of the stripping tower 1 except that only one stage of the packing layer 3 is provided.

[0024] In FIG. 1, the water to be treated (wastewater containing ammonia) is supplied to the sprinkler 2a at the upper part of the first stripping module 1A through the water supply pipe 2 for the water to be treated, and is sprinkled from the sprinkler 2a. The sprinkled water flows down while contacting the gas in the packing layer 3, and becomes the bottom liquid L from which ammonia has been diffused.

[0025] This bottom liquid L is supplied to the sprinkler 2a at the upper part of the second stripping module 1B through the pipe 4A, the pump 5A, and the pipe 2A, and is sprinkled from the sprinkler 2a. The sprinkled water flows down while contacting the gas in the packing layer 3, and becomes the bottom liquid L from which ammonia has been diffused. This bottom liquid L is supplied to the sprinkler 2a at the upper part of the third stripping module 1C through the pipe 4B, the pump 5B, and the pipe 2B, and is sprinkled from the sprinkler 2a. The sprinkled water flows down while contacting the gas in the packing layer 3, and becomes the bottom liquid L from which ammonia has been diffused.

[0026] The bottom liquid L from the third stripping module 1C is circulated to pipe 2 via pipe 4, circulation pump 5C, and pipe 6. A portion of the bottom liquid is taken out as treated water from pipe 7, which is connected to pipe 6.

[0027] In each stripping module 1A to 1C, a nozzle 11 is installed to inject gas into the lower part of the stacked bed 3. The gas injected from this nozzle 11 rises through the stacked bed 3 and comes into contact with the wastewater, causing the ammonia in the wastewater to be released as gas. The released gas and water vapor generated by the evaporation of water rise through the stack along with the air, pass through the demister (mist separator) 12, and the water droplets are removed. This ammonia and water vapor-containing gas flows out from the top of the stack into piping 13A, 13B, or 13C.

[0028] Furthermore, ammonia and water vapor-containing gas from the top of the third stripping module 1C is supplied to the nozzle 11 of the second stripping module 1B via piping 13C. Ammonia and water vapor-containing gas from the top of the second stripping module 1B is supplied to the nozzle 11 of the first stripping module 1A via piping 13B.

[0029] The gas flowing out of the first stripping module 1A into piping 13A is heated in the heat exchanger 14 to a temperature above the dew point, preferably 280-380°C, particularly around 320-350°C, before passing through piping 15 and being introduced into the catalytic reactor 16. A catalytic reactor inlet heater may be provided in the middle of piping 15.

[0030] Ammonia in the gas is oxidized upon contact with catalyst 16a in catalytic reactor 16. This oxidation reaction is exothermic, causing the gas temperature to rise. The gas flowing out of catalytic reactor 16 is introduced into heat exchanger 14 via piping 17, where it cools down through heat exchange with the gas flowing out of the first stripping module 1A. This gas is then supplied to the nozzle 11 of the third stripping module 1C via piping 18, blower 19, and piping 20. A portion of the gas blown out by blower 19 is sent to chimney 22 via piping 21, which branches off from piping 20, and discharged outside the system. Downstream of the branching point of piping 21 (towards nozzle 11), air (atmosphere) is added via blower 23 and piping 24.

[0031] Figure 2 shows an example of a case where stripping modules 1A, 1B, and 1C are arranged in parallel. In this embodiment, each stripping module 1A to 1C is rectangular (a cylindrical shape with a roughly square horizontal cross-section).

[0032] The stripping apparatus according to this embodiment employs a modular tower structure by dividing a conventional stripping tower, which has multiple layers of packed beds installed vertically, into multiple sections, and has the following advantages. (a) By adopting a modular structure in which the multi-stage stripping tower is divided, the total height of each stripping module 1A to 1C can be significantly reduced, eliminating the need for structures such as elevated operating platforms that were required in conventional examples. In addition, the reduced tower height eliminates the need for a robust foundation, significantly reducing the manufacturing costs of the foundation and platform. (i) By adopting a modular design, the number of stages can be easily increased or decreased according to the raw water quality, contributing to a reduction in equipment costs. Standardization is also easy. (c) By using a rectangular tank, a large cross-sectional area can be secured for the installation area, contributing to space saving. In addition, insulation work on the tank itself is easy. (e) (By installing gas piping and bottom liquid piping that bypass each stripping module, and by installing on / off valves on each bypass piping,) each stripping module can be stopped independently, and maintenance such as cleaning when the packed bed becomes clogged can be performed without stopping the entire apparatus. [Explanation of Symbols]

[0033] 1 Stripping Tower 1A, 1B, 1C Stripping Module 3 Filled bed 16 Catalytic reactor 22 Chimneys

Claims

1. A stripping apparatus having first to n (n is 2 or more) stripping modules in which gas-containing water comes into contact with a gas-releasing gas in a packed bed to perform a gas-releasing treatment, The raw water to be treated is supplied to the first stripping module. The raw gas for gas release is supplied to the nth stripping module. The bottom liquid from the j-th (where j is 1 or greater and less than n) stripping module is supplied to the (j+1) stripping module as water to be treated. The gas from the top of the k-th (where k is greater than 1 and less than or equal to n) stripping module is supplied to the (k-1) stripping module as a gas for gas release. A stripping apparatus in which treated water is extracted from the bottom liquid of the nth stripping module, A pump for supplying treated water from the stripping module is provided in each stripping module. Each stripping module is a rectangular tube with a roughly square horizontal cross-section. Each stripping module is arranged in parallel with one side of the rectangular tube facing the same direction. The pump of each stripping module is a stripping device arranged along one side of each stripping module.

2. The stripping device according to claim 1, wherein n is 2 to 5.

3. A stripping apparatus according to claim 1 or 2, wherein a circulation line is provided for circulating the bottom liquid of the n stripping module to the first stripping module, and treated water is taken out from the circulation line.

4. A stripping apparatus according to any one of claims 1 to 3, wherein each stripping module is provided with only one packing layer.

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