WO2022049769A1

WO2022049769A1 - Wet-type ammonia cleaning apparatus and fertilizer production plant provided with said wet-type ammonia cleaning apparatus

Info

Publication number: WO2022049769A1
Application number: PCT/JP2020/033783
Authority: WO
Inventors: 光一朗吉徳; 範明仙波; 幸男田中; 敦弘行本; 隆仁米川; 真也福澤; 知広大谷; 康平磯谷
Original assignee: 三菱重工エンジニアリング株式会社
Priority date: 2020-09-07
Filing date: 2020-09-07
Publication date: 2022-03-10

Abstract

A wet-type ammonia cleaning apparatus for treating a basic gas containing ammonia, the apparatus comprising: an ammonia scrubber that causes gas-liquid contact between the basic gas and an absorption liquid containing carbon dioxide; and fine bubble generating devices for producing the absorption liquid from carbon dioxide and water, wherein the fine bubble generating devices include at least a first fine bubble generating device for producing a first absorption liquid from carbon dioxide and water, and a second fine bubble generating device for producing an absorption liquid from carbon dioxide and the first absorption liquid.

Description

Wet ammonia cleaning device and fertilizer production plant equipped with this wet ammonia cleaning device

The present disclosure relates to a wet ammonia cleaning device and a fertilizer manufacturing plant equipped with this wet ammonia cleaning device.

A fertilizer production plant that produces fertilizer using methane-containing gas such as natural gas has an ammonia production unit that produces ammonia from methane-containing gas and a urea production unit that produces a urea solution by reacting ammonia with carbon dioxide. , Equipped with a urea granulation unit that produces granular solid urea from a urea solution. In the urea granulation unit, a basic gas containing urea dust such as solid urea powder and ammonia is generated. Patent Document 1 describes a wet ammonia cleaning device in which urea dust is removed by gas-liquid contact between water and a basic gas, and ammonia is removed by gas-liquid contact between an absorption liquid containing carbon dioxide and a basic gas. Are listed.

International Publication No. 2019/234816

However, when the temperature of the system rises, the solubility of the gas decreases and the concentration of carbon dioxide in the absorption liquid decreases, so there is a problem that the processing efficiency of the basic gas decreases, and the carbon dioxide in the absorption liquid decreases. There is a need for a technique for increasing the concentration of carbon. In the wet ammonia cleaning device described in Patent Document 1, the amount of carbon dioxide that can be supplied to the absorption liquid circulating in the ammonia scrubber where the absorption liquid and the basic gas are in gas-liquid contact is limited, and the amount of carbon dioxide in the absorption liquid is limited. In order to further increase the concentration of carbon dioxide, it is necessary to make the fine bubble generator a multi-stage type and further supply carbon dioxide to the absorbing liquid in the second and subsequent stages.

In view of the above circumstances, at least one embodiment of the present disclosure is an object of providing a wet ammonia cleaning device capable of improving the treatment efficiency of a basic gas and a fertilizer production plant equipped with the wet ammonia cleaning device.

In order to achieve the above object, the wet ammonia cleaning device according to the present disclosure is a wet ammonia cleaning device that treats a basic gas containing carbon dioxide, and is a gas-liquid contact between an absorbing liquid containing carbon dioxide and the basic gas. Ammonia scrubber to be generated and a fine bubble generator for producing the absorption liquid from carbon dioxide and water are provided, and the fine bubble generator is at least a first fine bubble generator for producing the first absorption liquid from carbon dioxide and water. And a second fine bubble generator that produces the absorption liquid from carbon dioxide and the first absorption liquid.

According to the wet ammonia cleaning device of the present disclosure, when carbon dioxide is absorbed by one fine bubble generator by absorbing carbon dioxide in at least each of the first fine bubble generator and the second fine bubble generator. As compared with this, the carbon dioxide concentration of the absorbing liquid can be increased, so that the processing efficiency of the basic gas can be improved.

It is a structural schematic diagram of the wet ammonia cleaning apparatus which concerns on Embodiment 1 of this disclosure. It is a figure for demonstrating the dissolution behavior of carbon dioxide by a fine bubble generator in the wet ammonia cleaning which concerns on Embodiment 1 of this disclosure. It is a structural schematic diagram of the wet ammonia cleaning apparatus which concerns on Embodiment 2 of this disclosure. It is a structural schematic diagram of the wet ammonia cleaning apparatus which concerns on Embodiment 3 of this disclosure. It is a structural schematic diagram of the fertilizer production plant provided with the wet ammonia cleaning apparatus which concerns on Embodiment 4 of this disclosure.

Hereinafter, the wet ammonia cleaning device according to the embodiment of the present disclosure will be described with reference to the drawings. The embodiment thereof shows one aspect of the present disclosure, does not limit the disclosure, and can be arbitrarily changed within the scope of the technical idea of the present disclosure.

The wet ammonia cleaning device of the present disclosure treats, for example, a basic gas containing ammonia generated from a fertilizer production plant. Specifically, the wet ammonia cleaning device removes ammonia from the basic gas by bringing the basic gas containing ammonia into gas-liquid contact with the absorbing liquid. However, the basic gas targeted in the present disclosure is not limited to that generated from a fertilizer production plant, and the basic gas containing ammonia is targeted regardless of where it is generated.

(Embodiment 1)
<Structure of the wet ammonia cleaning device according to the first embodiment of the present disclosure>
As shown in FIG. 1, the wet ammonia cleaning device 10 according to the first embodiment of the present disclosure includes an ammonia scrubber 11 and a fine bubble generator 12 for producing an absorption liquid supplied to the ammonia scrubber 11. .. The ammonia scrubber 11 has a housing 13 having an internal space 13a through which a basic gas flows, and an absorbing liquid circulation line 14 for extracting the absorbing liquid stored in the housing 13 and returning it to the gas phase in the housing 13. And a pump 15 provided in the absorption liquid circulation line 14. The absorption liquid extraction line 22 is branched from the absorption liquid circulation line 14 on the downstream side of the pump 15 in the direction in which the absorption liquid flows through the absorption liquid circulation line 14.

A pipe 17 for supplying the basic gas to the internal space 13a is connected between the top and bottom of the housing 13 to allow the basic gas in gas-liquid contact with the absorption liquid to flow out from the internal space 13a. The exhaust line 18 is connected to the top of the housing 13. The internal space 13a is provided with a nozzle 16 for sprinkling make-up water in the internal space 13a and a nozzle 20 for sprinkling the absorbing liquid in the internal space 13a. A make-up water supply pipe 19 for supplying make-up water to the nozzle 16 is connected to the nozzle 16, and the nozzle 20 is provided at the downstream end of the absorption liquid circulation line 14. The nozzle 20 may be configured to inject the absorbing liquid toward the tray 21 (for example, composed of a perforated plate) installed in the internal space 13a. The number of trays 21 may be one or any number of two or more.

In FIG. 1, the nozzle 16 is drawn so as to be located above the nozzle 20 and the tray 21, but the present invention is not limited to this form. The nozzle 16 may be configured to be located between the nozzle 20 and the tray 21, or may be configured to be located below the tray 21. Further, in FIG. 1, the nozzle 20 is provided at a position above the tray 21 and at a position between trays adjacent to each other in the vertical direction when two or more trays 21 are provided, but the present invention is limited to this form. The nozzle 20 may be provided only at a position above the tray 21.

The fine bubble generator 12 includes a first fine bubble generator 12a and a second fine bubble generator 12b arranged in series with each other. The first fine bubble generator 12a and the second fine bubble generator 12b are provided on the absorption liquid circulation line 14 on the downstream side of the pump 15, and the second fine bubble generator 12b is more than the first fine bubble generator 12a. It is provided on the downstream side. The configuration of the first fine bubble generator 12a and the second fine bubble generator 12b is not particularly limited, and carbon dioxide and water (or water in the absorbing liquid) supplied via the carbon dioxide supply line 118 are not particularly limited. Any device can be used as long as it can produce an absorbent liquid from (including), but a fine bubble generator that generates carbon dioxide bubbles of 100 micrometers or less is preferable. As such a fine bubble generator, an ejector method, a cavitation method, a swirling flow method, a pressure melting method, or the like can be used.

A more preferable configuration for the fine bubble generator 12 is to use a fine bubble generator that generates carbon dioxide bubbles of 1 to 100 micrometers as the first fine bubble generator 12a and 50 to several as the second fine bubble generator 12b. It is configured to use a fine bubble generator that generates 100 (for example, 500) nanometers of carbon dioxide bubbles. In each of the first fine bubble generator 12a and the second fine bubble generator 12b, an ejector type device is adopted as the first fine bubble generator 12a in order to generate carbon dioxide bubbles within the above range. 2 As the fine bubble generator 12b, a pressure melting type device can be adopted. Regarding the range of carbon dioxide bubble size, even if a large number of generated bubbles partially contain bubbles outside the range, if the average value of the bubble size is within that range. The device that generated the bubbles is considered to be generating bubbles of a size within that range.

<Operation of the wet ammonia cleaning device according to the first embodiment of the present disclosure>
Next, the operation of the wet ammonia cleaning device 10 according to the first embodiment of the present disclosure will be described. The basic gas flowing through the pipe 17 flows into the housing 13 (internal space 13a) of the ammonia scrubber 11. In the internal space 13a, when the basic gas flows upward, it is contained in the basic gas by flowing through the absorption liquid circulation line 14 by the pump 15 and making gas-liquid contact with the absorption liquid injected from the nozzle 20. Ammonia is absorbed by the absorption liquid and the ammonia is removed from the basic gas. The basic gas from which ammonia has been removed flows out of the internal space 13a via the exhaust line 18 and is exhausted. In the absorption liquid retained in the internal space 13a, the absorbed ammonia is present in the liquid in the form of at least one of ammonia molecules and ammonium ions.

The absorbent liquid is manufactured by the fine bubble generator 12. Specifically, a part of the absorbing liquid staying in the internal space 13a is extracted from the internal space 13a by the pump 15 and circulated through the absorbing liquid circulation line 14, and the water in the absorbing liquid in the first fine bubble generator 12a. The first absorption liquid is produced by blowing carbon dioxide into the first absorption liquid, and then carbon dioxide is blown into the first absorption liquid in the second fine bubble generator 12b to produce the absorption liquid. The fine bubble generator 12 includes two devices, that is, a first fine bubble generator 12a and a second fine bubble generator 12b. Therefore, by absorbing carbon dioxide in each of these, the carbon dioxide concentration of the absorbing liquid can be increased as compared with the case where carbon dioxide is absorbed by one fine bubble generator.

In the form in which the first fine bubble generator 12a is an ejector type device and the second fine bubble generator 12b is a pressure dissolution type device, carbon dioxide is dissolved in water by the first fine bubble generator 12a, and the first fine bubble generator 12a is used. 2 The fine bubble generator 12b supplies carbon dioxide to the first absorbing liquid as fine bubbles (fine bubbles). As shown in FIG. 2, in the internal space 13a, the absorbed liquid and the basic gas having a carbon dioxide partial pressure lower than the equilibrium carbon dioxide partial pressure are brought into gas-liquid contact, so that carbon dioxide in the absorbed liquid is contained. Dissipates to the basic gas side, and the fine bubble 200 compensates for the amount corresponding to the dissipated carbon dioxide and the carbon dioxide dissociated in the absorption liquid. As a result, it is possible to suppress a decrease in the concentration of carbon dioxide in the absorption liquid. Since the smaller the diameter of the fine bubble 200, the lower the speed at which the fine bubble 200 floats in the absorbing liquid, the residence time of the fine bubble 200 in the liquid becomes longer, and the fine bubble 200 is less likely to be released to the basic gas side. Further, as the diameter of the fine bubble 200 is smaller, the internal pressure of the fine bubble 200 is increased, so that the dissolution rate in the absorbing liquid is also improved.

From any of the above-mentioned configurations regarding the fine bubble generator 12, it is possible to increase the concentration of carbon dioxide in the absorption liquid ejected from the nozzle 20 as compared with the case where the above-mentioned configuration is not provided. As a result, the absorption of ammonia by the absorbing liquid is promoted, so that the processing efficiency of the basic gas can be improved.

As the removal of ammonia from the basic gas in the ammonia scrubber 11 continues, the concentration of ammonia in the absorption liquid staying in the internal space 13a increases, so the ammonia removal rate decreases, and eventually ammonia. Cannot be removed. Therefore, while a part of the absorption liquid flowing through the absorption liquid circulation line 14 is extracted through the absorption liquid extraction line 22, make-up water is injected from the nozzle 16 into the internal space 13a. As a result, the concentration of ammonia in the absorbing liquid staying in the internal space 13a decreases, so that the decrease in the ammonia removal rate can be suppressed.

<Modified example of the wet ammonia cleaning device according to the first embodiment of the present disclosure>
In the first embodiment, both the first fine bubble generator 12a and the second fine bubble generator 12b are provided on the absorbing liquid circulation line 14, but the embodiment is not limited to this. Absorbent liquid produced by the first fine bubble generator 12a and the second fine bubble generator 12b without the first fine bubble generator 12a and the second fine bubble generator 12b being provided in the absorption liquid circulation line 14. May be supplied to the absorption liquid circulation line 14, or the manufactured absorption liquid may be supplied to the internal space 13a. Further, only the second fine bubble generator 12b is provided in the absorption liquid circulation line 14, and the first absorption liquid produced by the first fine bubble generator 12a is configured to be supplied to the second fine bubble generator 12b. You can also.

However, in the configuration in which the first fine bubble generator 12a and the second fine bubble generator 12b are both provided in the absorption liquid circulation line 14, the absorption liquid produced by the fine bubble generator 12 is absorbed in the absorption liquid circulation line 14. The concentration of carbon dioxide in the absorption liquid supplied to the internal space 13a is higher than that in the case of supplying to the internal space 13a or the configuration for supplying the internal space 13a. This is because there is a limit to the amount of carbon dioxide that can be supplied to the circulating flow rate of the absorbent liquid in the fine bubble generator 12, so it is better to provide the fine bubble generator 12 on the line where the flow rate of the absorbent liquid is as large as possible. This is because the supply amount of carbon dioxide increases and the amount of carbon dioxide in the absorption liquid also increases. As a result, the processing efficiency of the basic gas can be improved.

In the first embodiment, the fine bubble generator 12 includes two fine bubble generators, that is, a first fine bubble generator 12a and a second fine bubble generator 12b, but the present invention is not limited to the two. It may be equipped with one or more fine bubble generators. Even in this case, it is preferable that at least two fine bubble generators are arranged in series with each other, and it is further preferable that all the fine bubble generators are arranged in series with each other.

(Embodiment 2)
Next, the wet ammonia cleaning device according to the second embodiment will be described. The wet ammonia cleaning device according to the second embodiment is obtained by adding a membrane separation device for removing ammonia from the absorbent liquid flowing through the absorbent liquid circulation line 14 to the first embodiment. In the second embodiment, the same reference numerals as those of the configuration requirements of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

<Structure of the wet ammonia cleaning device according to the second embodiment of the present disclosure>
As shown in FIG. 3, in the wet ammonia cleaning device 10 according to the second embodiment of the present disclosure, the absorption liquid circulation line 14 is provided with the first fine bubble generator 12a and the second fine bubble generator 12b. .. The absorption liquid circulation line 14 is provided with a membrane separation device 30 for removing ammonia from the absorption liquid between the pump 15 and the first fine bubble generator 12a. The configuration of the membrane separation device 30 is not particularly limited, and for example, a membrane separation device provided with a reverse osmosis membrane (RO membrane) can be used. The absorbent liquid circulation line 14 may be provided with a tank 31 in which make-up water is stored between the membrane separation device 30 and the first fine bubble generator 12a. Other configurations are the same as those of the first embodiment except that the absorption liquid extraction line 22 (see FIG. 1) is not provided.

<Operation of the wet ammonia cleaning device according to the second embodiment of the present disclosure>
Next, the operation of the wet ammonia cleaning device 10 according to the second embodiment of the present disclosure will be described. In the second embodiment, the operation during the flow of the absorbing liquid through the absorbing liquid circulation line 14 is different from that of the first embodiment, and the operation of removing ammonia from the basic gas in the ammonia scrubber 11 is the same as that of the first embodiment. Therefore, in the following, only the part different from the operation of the first embodiment, that is, the operation while the absorbing liquid flows through the absorbing liquid circulation line 14 will be described.

A part of the absorbing liquid staying in the internal space 13a is extracted from the internal space 13a by the pump 15 and circulates in the absorbing liquid circulation line 14. When the absorption liquid flows into the membrane separation device 30, only water passes through the separation membrane (for example, RO membrane) provided in the membrane separation device 30, and at least one of ammonia molecules, ammonium ions, carbonate ions, etc. that dissolves in the absorption liquid. Since the part cannot pass through the separation membrane, the absorption liquid flows out from the membrane separation device 30 in a state where the concentrations of ammonia and carbon dioxide dissolved in the absorption liquid are lowered. Ammonia molecules or concentrates of ammonium ions, carbonate ions, etc. that could not pass through the separation membrane are supplied to, for example, a stripper (not shown), and carbon dioxide and ammonia can be recovered and reused in the stripper. If the concentration of these molecules or ions is high, the concentrate can be reused as it is in the urea production process of the fertilizer production plant.

The absorption liquid flowing out of the membrane separation device 30 flows into the tank 31, then flows into the fine bubble generator 12 from the tank 31, and carbon dioxide is blown into the water in the absorption liquid in the first fine bubble generator 12a. 1 Absorption liquid is produced, and then carbon dioxide is blown into the first absorption liquid in the second fine bubble generator 12b to produce the absorption liquid. The operation after this is the same as that of the first embodiment.

In the second embodiment, the concentrations of ammonia and carbon dioxide in the absorbing liquid flowing into the fine bubble generator 12 are lower than those in the first embodiment. Therefore, the dissolution of carbon dioxide in the fine bubble generator 12 is promoted, and the carbon dioxide / ammonia ratio in the absorbing liquid becomes large. In general, the larger this ratio in the absorption liquid is, the more the removal of ammonia from the basic gas by the gas-liquid contact between the absorption liquid and the basic gas is promoted, so that the treatment efficiency of the basic gas is higher than that in the first embodiment. Can be improved.

(Embodiment 3)
Next, the wet ammonia cleaning device according to the third embodiment will be described. The wet ammonia cleaning device according to the third embodiment is obtained by adding a cooling device for cooling the basic gas to the first or second embodiment before the basic gas flows into the ammonia scrubber 11. Hereinafter, the third embodiment will be described with a configuration in which a cooling device is added to the configuration of the first embodiment, but the third embodiment may be configured by adding a cooling device to the configuration of the second embodiment. .. In the third embodiment, the same reference numerals as those of the constituent requirements of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

<Structure of the wet ammonia cleaning device according to the third embodiment of the present disclosure>
As shown in FIG. 4, in the wet ammonia cleaning device 10 according to the third embodiment of the present disclosure, the pipe 17 has a cooling device 40, for example, heat exchange between a cooling medium and a basic gas flowing through the pipe 17. A vessel is provided. Although it is not an essential configuration, in the absorption liquid circulation line 14, the cooling device 41, for example, the cooling medium and the absorption liquid flowing through the absorption liquid circulation line 14 exchange heat between the pump 15 and the first fine bubble generator 12a. A heat exchanger may be provided. Any fluid can be used as the cooling medium flowing through each of the

cooling devices

40 and 41, for example, ammonia produced by an ammonia production unit which is a component of a fertilizer production plant equipped with a wet ammonia cleaning device 10. Can be used. Other configurations are the same as those in the first embodiment.

<Operation of the wet ammonia cleaning device according to the third embodiment of the present disclosure>
Next, the operation of the wet ammonia cleaning device 10 according to the third embodiment of the present disclosure will be described. In the third embodiment, the basic gas is cooled by the cooling device 40 before the basic gas is supplied to the ammonia scrubber 11. The operation of removing ammonia from the basic gas in the ammonia scrubber 11 is the same as that of the first embodiment. By pre-cooling the basic gas in this way, it is possible to suppress an increase in the temperature of the absorbed liquid when the absorbed liquid and the basic gas come into gas-liquid contact in the ammonia scrubber 11, so that the absorbed liquid can be suppressed. The emission of carbon dioxide from the gas can be suppressed, and the processing efficiency of the basic gas can be improved.

When the cooling device 41 is provided in the absorbing liquid circulation line 14, the absorbing liquid is cooled in the cooling device 41 before flowing into the fine bubble generator 12. In general, the solubility of carbon dioxide increases as the temperature of water decreases, so that the concentration of carbon dioxide in the absorbing liquid can be increased as compared with the case where the absorbing liquid is not cooled before flowing into the fine bubble generator 12. In the third embodiment, since the basic gas flowing into the ammonia scrubber 11 is also cooled, the temperature of the absorbed liquid in the ammonia scrubber 11 rises due to the gas-liquid contact between the basic gas and the absorbed liquid in the ammonia scrubber 11 as compared with the first embodiment. Is suppressed. Therefore, since the absorbing liquid having a high concentration of carbon dioxide comes into gas-liquid contact with the basic gas, the processing efficiency of the basic gas can be improved as compared with the first embodiment.

(Embodiment 4)
Next, the fourth embodiment of the present disclosure will be described. In the fourth embodiment, the wet ammonia cleaning device according to any one of the first to third embodiments is provided in the fertilizer production plant. Hereinafter, the fourth embodiment will be described with the configuration in which the wet ammonia cleaning device 10 of the first embodiment is provided in the fertilizer production plant, but the wet ammonia cleaning device 10 of the second or third embodiment is provided in the fertilizer production plant. Form 4 may be configured. In the fourth embodiment, the same reference numerals as those of the constituent requirements of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

<Structure of a fertilizer production plant provided with the wet ammonia cleaning device according to the fourth embodiment of the present disclosure>
As shown in FIG. 5, the fertilizer production plant 100 produces a urea solution by reacting ammonia and carbon dioxide with an ammonia production unit 5 that produces ammonia using a raw material gas such as a natural gas containing methane. It is provided with a urea production unit 70 for producing urea, a urea granulation unit 60 for producing granular solid urea from a urea solution, and a wet ammonia cleaning device 10 for treating basic gas generated from the urea granulation unit 60. .. The fertilizer production plant 100 includes a reformer 1 that reforms the raw material gas, a modifier 2 that modifies carbon monoxide and steam in the gas supplied from the reformer 1, and a gas flowing out from the reformer 2. A carbon dioxide recovery device 3 for recovering carbon dioxide and a steaming device 4 for converting carbon dioxide and carbon monoxide in the gas flowing out from the carbon dioxide recovery device 3 into methane, respectively, may be further provided. In this case, the methanizer 4 and the ammonia production unit 5 are connected.

The urea production unit 70 includes a compressor 71 and a urea production apparatus 72. The compressor 71 and the urea production apparatus 72 are connected to each other via a pipe 121. The carbon dioxide recovery device 3 and the compressor 71 are connected to each other via a pipe 122. The ammonia supply line 123 is provided so that the ammonia produced by the ammonia production unit 5 is supplied to the pipe 121, and the ammonia supply line 123 is provided with a compressor 76 for boosting the ammonia. The carbon dioxide supply line 118 branches from the upstream side of the position where the ammonia supply line 123 joins in the pipe 121, and the carbon dioxide supply line 118 is the first fine bubble generator 12a and the second fine bubble generator 12b (FIG. 1). See) connected to each.

The wet ammonia cleaning device 10 removes ammonia from the dust scrubber 51 that removes solid components such as urea dust from the basic gas generated from the urea granulation unit 60 and the basic gas from which the solid components have been removed from the dust scrubber 51. It is equipped with an ammonia scrubber 11. The urea granulation unit 60 and the dust scrubber 51 are connected via a basic gas flow line 111. The dust scrubber 51 and the ammonia scrubber 11 are connected to each other via a pipe 17.

The other end of the make-up water supply pipe 19 to which one end is connected to the nozzle 16 (see FIG. 1) provided in the ammonia scrubber 11 is the compressor 71 or the pipe 6 connecting the reformer 1 and the modifier 2. It is connected to at least one of them. In the configuration in which the make-up water water supply pipe 19 is connected to the compressor 71, the drain generated in the compressor 71 is drained from the compressor 71 via the make-up water water supply pipe 19 so that the make-up water can be drained. In the configuration in which the water supply pipe 19 is connected to the pipe 6, the condensate contained in the gas flowing out from the reforming device 1 is drained from the pipe 6.

<Operation of a fertilizer production plant equipped with a wet ammonia cleaning device according to the fourth embodiment of the present disclosure>
Next, the operation of the fertilizer production plant 100 will be described. The raw material gas is reformed by air and steam in the reformer 1 to become a gas containing at least hydrogen and carbon dioxide. Since the reformer 1 also takes in air, the gas discharged from the reformer 1 and supplied to the modifier 2 in the subsequent stage also includes components derived from air. Specifically, the gas discharged from the reformer 1 also includes nitrogen and the like. This gas also contains carbon monoxide, which is converted into carbon dioxide and hydrogen by a chemical reaction with water in the modifier 2 in the subsequent stage.

By recovering carbon dioxide in the gas, the carbon dioxide recovery device 3 downstream of the denaturant 2 can suppress the introduction of carbon dioxide into the ammonia production unit 5 and suppress the influence on the ammonia production catalyst. .. The recovery of carbon dioxide in the carbon dioxide recovery device 3 can be performed, for example, by bringing an alkaline aqueous solution into contact with the gas. The recovered carbon dioxide is separated from the alkaline aqueous solution by heating the alkaline aqueous solution or the like, and then supplied to the fine bubble generator 12 (see FIG. 1) of the urea production unit 70 and the wet ammonia cleaning device 10.

In the methanizer 4 downstream of the carbon dioxide recovery device 3, the carbon dioxide that could not be recovered by the carbon dioxide recovery device 3 and the carbon dioxide that was not converted into carbon dioxide by the denaturator 2 and were not recovered by the carbon dioxide recovery device 3. Carbon monoxide and carbon monoxide are each converted to methane. By removing carbon monoxide, carbon dioxide, and other carbon oxides in the methanization apparatus 4, the introduction of carbon oxide into the ammonia production unit 5 is suppressed. This makes it possible to suppress the influence of carbon oxide on the ammonia production catalyst.

The gas flowing out of the methanizer 4 and flowing into the ammonia production unit 5 contains hydrogen and nitrogen, and contains methane as an impurity. In the ammonia production unit 5, by using an arbitrary ammonia production catalyst, a chemical reaction represented by the following chemical formula (1) occurs, and ammonia is produced.
N ₂ + 3H ₂ → 2NH ₃ ... (1)

The generated ammonia sequentially flows through the ammonia supply line 123 and the pipe 121 by the compressor 76 and flows into the urea production apparatus 72 of the urea production unit 70. Further, the carbon dioxide recovered by the carbon dioxide recovery device 3 flows out from the carbon dioxide recovery device 3, flows through the pipe 122, is boosted by the compressor 71, and flows into the urea production apparatus 72 through the pipe 121. .. In the urea production apparatus 72, urea (urea solution) is produced from carbon dioxide and ammonia by a chemical reaction represented by the following chemical formula (2).
2NH ₃ + CO ₂ → (NH ₂ ) ₂ CO + H ₂ O ・・・ (2)

The urea solution produced by the urea production unit 70 flows into the urea granulation unit 60. In the urea granulation unit 60, the urea supplied from the urea production unit 70 is granulated. Granular urea obtained by granulation of urea is shipped and used as fertilizer.

In the urea granulation unit 60, a basic gas containing urea dust, which is a powder of solid urea, and ammonia is generated during the granulation of urea. The basic gas flows through the basic gas flow line 111 and flows into the wet ammonia cleaning device 10. In the wet ammonia cleaning device 10, urea dust is removed from the basic gas by the gas-liquid contact between the cleaning water and the basic gas in the dust scrubber 51. The basic gas from which the urea dust has been removed flows into the ammonia scrubber 11 via the pipe 17. In the ammonia scrubber 11, ammonia is removed from the basic gas by the same operation as that described in the first embodiment. The basic gas from which ammonia has been removed is exhausted through the exhaust line 18.

In the fourth embodiment, at least one of the condensates contained in the drain generated in the compressor 71 or the gas flowing out from the reformer 1 is supplied to the ammonia scrubber 11 as make-up water via the make-up water supply pipe 19. .. Since the drain and condensate are carbonated water in which carbon dioxide is dissolved, carbonated water is supplied to the ammonia scrubber 11 as make-up water. As a result, not only carbonated water as an absorption liquid but also carbonated water as make-up water can absorb ammonia, so that treatment of basic gas is performed as compared with the case of supplying water containing no carbon dioxide as make-up water. Efficiency can be improved.

<Modification example of a fertilizer production plant equipped with a wet ammonia cleaning device according to the fourth embodiment of the present disclosure>
In the fourth embodiment, carbonated water is used as the make-up water supplied to the ammonia scrubber 11 as the condensate contained in the drain generated in the compressor 71 or the gas flowing out from the reforming device 1, but the present invention is limited to this embodiment. is not it. An apparatus for producing carbonated water as make-up water may be provided in the fertilizer production plant 100. Such a device can be a device for extracting a part of carbon dioxide flowing through the carbon dioxide supply line 118 and dissolving it in water, and the configuration of this device is a filling type filled with a filler such as Raschig ring. It is possible to adopt an absorption tower, a plate-type absorption tower, an absorption tower in which the plate can be cooled in the plate-type absorption tower, and the like.

In the fourth embodiment, carbonated water generated or produced at an arbitrary location in the fertilizer production plant 100 is used as make-up water, but instead of or in combination with this form, carbonated water is generated as a first fine bubble. It may be supplied to at least one of the device 12a and the second fine bubble generator 12b. In this case, the pipe branched from the make-up water supply pipe 19 has a configuration in which carbonated water is connected to at least one of the first fine bubble generator 12a and the second fine bubble generator 12b.

In the fourth embodiment, the wet ammonia cleaning device 10 is provided with two fine bubble generators and may be further provided with three or more fine bubble generators, but the present invention is not limited to this embodiment. As long as it is a fine bubble generator capable of producing carbonated water having a sufficient carbon dioxide concentration, the wet ammonia cleaning device 10 may be configured to include one fine bubble generator provided in the absorption liquid circulation line 14.

The contents described in each of the above embodiments are grasped as follows, for example.

[1] The wet ammonia cleaning device according to one aspect is
A wet ammonia cleaning device (10) that treats a basic gas containing ammonia.
Ammonia scrubber (11) that brings carbon dioxide-containing absorption liquid into gas-liquid contact with basic gas,
A fine bubble generator (12) for producing the absorbent liquid from carbon dioxide and water is provided.
The fine bubble generator (12) is at least
A first fine bubble generator (12a) that produces a first absorbent liquid from carbon dioxide and water, and
It includes carbon dioxide and a second fine bubble generator (12b) for producing the absorption liquid from the first absorption liquid.

[2] The wet ammonia cleaning device according to another aspect is the wet ammonia cleaning device according to [1].
The fine bubble generator (12) generates carbon dioxide bubbles of 100 micrometers or less.

According to such a configuration, carbon dioxide bubbles of 100 micrometers or less are supplied to the water and the first absorbing liquid, so that the dissolution of carbon dioxide can be promoted.

[3] The wet ammonia cleaning device according to still another aspect is the wet ammonia cleaning device of [2].
The first fine bubble generator (12a) is an ejector type fine bubble generator, and the second fine bubble generator (12b) is a pressure melting type fine bubble generator.

According to such a configuration, carbon dioxide is dissolved in water by the first fine bubble generator, and carbon dioxide is supplied to the first absorbing liquid as fine bubbles (fine bubbles) by the second fine bubble generator. .. In the ammonia scrubber, the absorbed liquid and the basic gas having a lower carbon dioxide partial pressure than the equilibrium carbon dioxide partial pressure come into gas-liquid contact, so that the carbon dioxide in the absorbed liquid is released to the basic gas side. The fine bubble supplements the amount corresponding to the emitted carbon dioxide and the carbon dioxide dissociated in the absorption liquid. As a result, it is possible to suppress a decrease in the concentration of carbon dioxide in the absorption liquid, so that the treatment efficiency of the basic gas can be improved.

[4] The wet ammonia cleaning device according to still another aspect is the wet ammonia cleaning device according to any one of [1] to [3].
The ammonia scrubber (11) is provided with an absorbent liquid circulation line (14) for extracting the absorbent liquid stored therein and returning it to the gas phase in the ammonia scrubber (11).
The fine bubble generator (12) is provided in the absorbent liquid circulation line (14).

According to such a configuration, the gas of the ammonia scrubber is compared with the case of supplying the absorbent liquid produced by the fine bubble generator to the absorbent liquid circulation line or the case of supplying the absorbent liquid stored inside the ammonia scrubber. Since the concentration of carbon dioxide in the absorption liquid supplied in the phase is increased, the treatment efficiency of the basic gas can be improved.

[5] The wet ammonia cleaning device according to still another aspect is the wet ammonia cleaning device according to [4].
A membrane separation device (30) for removing ammonia from the absorbent liquid flowing through the absorbent liquid circulation line (14) is further provided.
The membrane separation device is provided in the absorption liquid circulation line so as to be located upstream of the fine bubble generator in the flow direction of the absorption liquid.

According to such a configuration, by removing ammonia from the absorption liquid, the carbon dioxide / ammonia ratio in the absorption liquid becomes large, so that the treatment efficiency of the basic gas can be improved.

[6] The wet ammonia cleaning device according to still another aspect is the wet ammonia cleaning device according to any one of [1] to [5].
A cooling device (40) for cooling the basic gas before the basic gas flows into the ammonia scrubber (11) is further provided.

According to such a configuration, by pre-cooling the basic gas, it is possible to suppress an increase in the temperature of the absorbing liquid when the absorbing liquid and the basic gas come into gas-liquid contact in the ammonia scrubber. Therefore, the emission of carbon dioxide from the absorbing liquid is suppressed, and the processing efficiency of the basic gas can be improved.

[7] The fertilizer production plant according to one aspect is
A fertilizer production plant (100) for producing fertilizer from a raw material gas containing methane.
An ammonia production unit (5) that produces ammonia from the raw material gas, and
A urea production unit (70) that produces a urea solution by reacting ammonia with carbon dioxide, and the like.
A urea granulation unit (60) for producing granular solid urea from the urea solution, and a urea granulation unit (60).
The wet ammonia cleaning device (10) according to any one of [1] to [6] for treating the basic gas generated from the urea granulation unit (60) is provided.
The carbonated water generated in the fertilizer production plant (100) is configured to be supplied in the gas phase in the ammonia scrubber (11) or to the fine bubble generator (12).

According to the fertilizer production plant of the present disclosure, by supplying carbonated water to the ammonia scrubber as make-up water supplied to the ammonia scrubber, not only the carbonated water as the absorption liquid but also the carbonated water as the make-up water is ammonia. Can be absorbed, so that the treatment efficiency of basic gas can be improved as compared with the case of supplying water containing no carbon dioxide as make-up water.

[8] The fertilizer production plant according to another aspect is the fertilizer production plant of [7].
The urea production unit (70) is
The urea production apparatus (72) for producing the urea solution, and
The urea production apparatus (72) is provided with a compressor (71) for supplying carbon dioxide.
The carbonated water is a drain generated by the compressor (71).

According to such a configuration, the processing efficiency of the basic gas can be improved for the same reason as in the above [7].

[9] The fertilizer production plant according to still another aspect is the fertilizer production plant of [7] or [8].
A reformer (1) for reforming the raw material gas with air and steam before the raw material gas flows into the ammonia production unit (5) is further provided.
The carbonated water is a condensate contained in the gas flowing out from the reformer (1).

1 Reformer 5 Ammonia production unit 10 Wet ammonia cleaning device 11 Ammonia scrubber 12 Fine bubble generator 12a 1st fine bubble generator 12b 2nd fine bubble generator 14 Absorbent liquid circulation line 30 Membrane separation device 40 Cooling device 60 Urea production Grain unit 70 Urea production unit 71 Compressor 72 Urea production equipment 100 Fertilizer production plant

Claims

A wet ammonia cleaning device that processes basic gas containing ammonia.
Ammonia scrubber that brings the absorption liquid containing carbon dioxide into gas-liquid contact with the basic gas,
It is equipped with a fine bubble generator that produces the absorbent liquid from carbon dioxide and water.
The fine bubble generator is at least
A first fine bubble generator that produces a first absorbent from carbon dioxide and water,
A wet ammonia cleaning device including carbon dioxide and a second fine bubble generator for producing the absorption liquid from the first absorption liquid.
The wet ammonia cleaning device according to claim 1, wherein the fine bubble generator generates carbon dioxide bubbles of 100 micrometers or less.
The wet ammonia cleaning device according to claim 2, wherein the first fine bubble generator is an ejector type fine bubble generator, and the second fine bubble generator is a pressure dissolution type fine bubble generator.
The ammonia scrubber is provided with an absorption liquid circulation line for extracting the absorption liquid stored therein and returning it to the gas phase in the ammonia scrubber.
The wet ammonia cleaning device according to any one of claims 1 to 3, wherein the fine bubble generator is provided in the absorption liquid circulation line.
Further provided with a membrane separation device for removing ammonia from the absorbent liquid flowing through the absorbent liquid circulation line.
The wet ammonia cleaning device according to claim 4, wherein the membrane separation device is provided in the absorption liquid circulation line so as to be located upstream of the fine bubble generation in the flow direction of the absorption liquid.
The wet ammonia cleaning device according to any one of claims 1 to 5, further comprising a cooling device for cooling the basic gas before the basic gas flows into the ammonia scrubber.
A fertilizer production plant for producing fertilizer from raw material gas containing methane.
An ammonia production unit that produces ammonia from the raw material gas,
A urea production unit that produces a urea solution by reacting ammonia with carbon dioxide,
A urea granulation unit that produces granular solid urea from the urea solution,
The wet ammonia cleaning device according to any one of claims 1 to 6 for treating the basic gas generated from the urea granulation unit.
A fertilizer production plant configured such that carbonated water produced in the fertilizer production plant is supplied to the gas phase in the ammonia scrubber or the fine bubble generator.
The urea production unit is
A urea production device that produces the urea solution, and
It is equipped with a compressor that supplies carbon dioxide to the urea production device.
The fertilizer production plant according to claim 7, wherein the carbonated water is a drain generated by the compressor.
Further equipped with a reformer for reforming the raw material gas with air and steam before the raw material gas flows into the ammonia production unit.
The fertilizer production plant according to claim 7 or 8, wherein the carbonated water is a condensate contained in the gas flowing out from the reformer.