A brine ammonium removal system

Abstract

The utility model discloses a kind of brine ammonium removal systems, including brine heater and impurity removal reactor, sodium hydroxide and sodium carbonate are added in this impurity removal reactor and calcium ion and magnesium ion are removed by reaction, while adding sodium hypochlorite reaction to make ammonium substance in brine into monochloramine and dichloramine, the downstream of impurity removal reactor is set to front reaction pool, and front reaction pool is accessed to compressed air to blow out part of monochloramine and dichloramine gas, ceramic membrane filter and ammonium removal tower are sequentially arranged in the downstream of front reaction pool, after ammonium removal, brine enters the downstream baffle tank, add sulphurous acid in baffle tank to remove free chlorine, while adding hydrochloric acid to adjust pH value.Using the above design, the utility model can make that fouling does not appear in ammonium removal tower, and the ammonium removal effect of ammonium removal tower is improved simultaneously.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, specifically to a brine ammonium removal system. Background Technology

[0002] Brine, a liquid salt mineral resource with a sodium chloride content of approximately 300 g / L, plays an indispensable role as a raw material in the chlor-alkali industry. Its quality directly affects the safety and stability of the chlor-alkali production process. In the ion-exchange membrane electrolysis stage, ammonium impurities in the brine directly affect the nitrogen trichloride content in the chlorine gas. Nitrogen trichloride is an extremely unstable substance, highly susceptible to decomposition and explosion, potentially leading to serious safety accidents. Therefore, the chlor-alkali industry imposes stringent requirements on brine purity, explicitly stipulating that the total ammonium content in monohydrate must be below 2 mg / L. This indicator has become a key criterion for assessing whether brine meets production standards, highlighting the urgency and necessity of removing ammonium impurities from the brine.

[0003] However, the ammonium content in underground brine is generally high. Taking Chongqing as an example, the ammonium content in the brine in this area ranges from 5-30 mg / L, far exceeding the requirements for industrial production. Therefore, it is necessary to treat it through an effective ammonium removal process. Traditional ammonium removal processes typically involve heating the brine to around 45°C, then adding sodium hydroxide to adjust the pH to above 9, followed by the addition of sodium hypochlorite for reaction. Finally, the reacted brine is sent to an ammonia stripping tower to remove ammonium. However, this process has significant drawbacks. Due to the high calcium and magnesium content in the brine, the addition of sodium hydroxide reacts with calcium and magnesium ions to form insoluble magnesium hydroxide and calcium hydroxide precipitates. These precipitates easily cause scaling inside the ammonia stripping tower and in connecting pipes. Scaling not only significantly reduces the mass transfer efficiency within the ammonia stripping tower, affecting the efficiency and quality of ammonium removal, but also requires regular acid washing of the pipes and the ammonia stripping tower to remove the scale. This increases equipment maintenance costs and operational difficulty, and makes it difficult to guarantee stable ammonium removal results, severely restricting the continuous and stable production of the chlor-alkali industry. Utility Model Content

[0004] In view of the above-mentioned shortcomings of the existing technology, the purpose of this utility model is to provide a brine ammonium removal system, which solves the problems of internal scaling in the existing ammonium removal devices, resulting in high production costs and poor ammonium removal effect.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A brine ammonium removal system includes a brine heater and a purification reactor. Sodium hydroxide and sodium carbonate are added to the purification reactor to react and remove calcium and magnesium ions. Sodium hypochlorite is added to react and convert ammonium substances in the brine into monochloroamine and dichloroamine. A pre-reaction tank is set downstream of the purification reactor, and compressed air is introduced into the pre-reaction tank to blow out a portion of the monochloroamine and dichloroamine gases. A ceramic membrane filter and an ammonium removal tower are sequentially set downstream of the pre-reaction tank. The brine after ammonium removal enters a downstream baffle tank. Sulfurous acid is added to the baffle tank to remove free chlorine, and hydrochloric acid is added to adjust the pH value.

[0007] As a further improvement, an intermediate tank and a salt treatment tank are sequentially arranged between the impurity removal reactor and the pre-reaction tank.

[0008] As a further improvement, low-pressure steam is introduced into the lower end of the ammonium removal tower to prevent brine crystallization and maintain the temperature inside the tower. At the same time, a blower is installed at the lower end of the ammonium removal tower to blow out monochloramine and dichloramine gases from the top of the tower.

[0009] As a further improvement, the outlet of the ammonium removal tower is provided with a reflux pipe that is connected to the upper end of the ammonium removal tower to circulate and remove ammonium from the brine.

[0010] As a further improvement, the temperature at which the brine heater preheats the brine is 60-65℃, and the temperature of the ammonium removal tower is not lower than 65℃.

[0011] As a further improvement, the brine filtered by the ceramic membrane filter is connected to the upper end of the ammonium removal tower through a pipeline, and sprayed downwards into the tower through several nozzles installed inside the tower.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. This utility model removes calcium and magnesium ions by adding sodium hydroxide and sodium carbonate to the impurity removal reactor and filtering the precipitate after the reaction through a ceramic membrane filter, thereby ensuring that no scaling occurs in the ammonium removal tower, thus eliminating the need for regular acid washing and improving the ammonium removal efficiency of the ammonium removal tower.

[0014] 2. The brine of this invention is preheated before entering the impurity removal reaction tank and maintained at a blowing temperature of not less than 65°C in the ammonium removal tower, which can effectively improve the ammonium removal effect.

[0015] 3. This utility model improves the ammonium removal efficiency by introducing compressed air into the pre-reaction tank to blow out a portion of the monochloramine and dichloramine gases, and then performing secondary blowing to remove ammonium in the ammonium removal tower, thereby ensuring that the brine after ammonium removal meets the standards.

[0016] 4. In this utility model, low-pressure steam is introduced into the lower end of the ammonium removal tower, which not only prevents brine crystallization, but also ensures that the temperature of the brine in the ammonium removal tower is controlled at no less than 65°C, so as to achieve better ammonium removal effect. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model.

[0018] In the picture:

[0019] 1. Brine heater, 2. Impurity removal reactor, 3. Pre-reaction tank, 4. Ceramic membrane filter, 5. Ammonium removal tower, 6. Baffle trough, 7. Intermediate tank, 8. Salt dissolving tank, 9. Blowout fan, 10. Return pipe. Detailed Implementation

[0020] To explain in detail the technical content, structural features, objectives and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0021] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] Please see Figure 1A brine ammonium removal system includes a brine heater 1 and a purification reactor 2. The brine heater 1 preheats the brine to a temperature of 60-65°C. Sodium hydroxide and sodium carbonate are added to the purification reactor 2 to react and remove calcium and magnesium ions. Sodium hydroxide reacts with magnesium ions to produce magnesium hydroxide precipitate, and sodium carbonate solution reacts with calcium ions to produce calcium carbonate precipitate. These reactions are existing technologies and will not be described in detail here. Simultaneously, sodium hypochlorite is added to react and convert ammonium substances in the brine into monochloroamine and dichloroamine. A pre-reaction tank 3 is located downstream of the purification reactor 2. The pre-reaction tank 3 is open, and compressed air is introduced into it to blow out a portion of the monochloroamine and dichloroamine gases, thus removing some of the ammonium from the brine. A ceramic membrane filter 4 and an ammonium removal tower 5 are sequentially installed downstream of the pre-reaction tank 3. Insoluble substances such as magnesium hydroxide and calcium carbonate are filtered out in the ceramic membrane filter 4, and then ammonium is removed through the ammonium removal tower 5. The brine after ammonium removal enters the downstream baffle tank 6. Sulfurous acid is added to the baffle tank 6 to remove free chlorine, and hydrochloric acid is added at the same time to adjust the pH value.

[0023] The experiment involved heating and blowing out a brine solution (a refined brine solution with a pH of 9-11 and a temperature of approximately 60°C). The remaining ammonium content in the brine was determined using the following data:

[0024] Let stand for 30 minutes 3.1 mg / L 1.57 mg / L 1.29 mg / L 1.17 mg / L 0.7 mg / L Blow for 30 minutes 1.65 mg / L 0.63 mg / L 0.52 mg / L 0.48 mg / L 0.1 mg / L

[0025] As can be seen from the table above, the ammonium removal effect is better when the brine is heated to 65-80℃. Considering the overall cost, the higher the heating temperature, the higher the energy consumption. Therefore, in this invention, the temperature of the ammonium removal tower 5 is set to no less than 65℃ to ensure a better ammonium removal effect.

[0026] An intermediate tank 7 and a salt dissolving tank 8 are sequentially arranged between the impurity removal reactor 2 and the pre-reaction tank 3. The intermediate tank 7 is used for buffering. After being pressurized, the brine enters the salt dissolving tank 8. Since the addition of sodium hydroxide and sodium carbonate in the impurity removal reactor 2 causes the brine concentration to decrease, the salt dissolving tank 8 ensures that the brine concentration reaches saturation.

[0027] Low-pressure steam is introduced into the lower end of the ammonium removal tower 5 to prevent brine from crystallizing inside the tower and to ensure that the temperature inside the tower is not lower than 65°C. Simultaneously, a blower 9 is installed at the lower end of the ammonium removal tower 5 to blow out monochloramine and dichloramine gases from a vent pipe installed at the top of the tower. A reflux pipe 10 is provided at the outlet of the ammonium removal tower 5 and connects to the upper end of the tower for circulating ammonium removal of the brine. The outlet of the ammonium removal tower 5 is connected to the reflux pipe 10 and a pipe connected to the baffle trough 6 via a T-junction pipe.

[0028] The brine filtered by the ceramic membrane filter 4 is connected to the upper end of the ammonium removal tower 5 through a pipeline, and sprayed downwards into the tower through several nozzles installed inside the ammonium removal tower 5.

[0029] In this embodiment, the brine enters the ammonium removal tower 5 from above, while the blower 9 and low-pressure steam enter from below, thus ensuring sufficient contact with the brine and removing monochloramine and dichloramine as much as possible.

[0030] The working principle of this utility model is as follows:

[0031] After preheating to approximately 60°C by brine heater 1, sodium hydroxide and sodium carbonate are added. Sodium hydroxide reacts with magnesium ions to produce magnesium hydroxide precipitate, while sodium carbonate solution reacts with calcium ions to form calcium carbonate precipitate, thus removing calcium and magnesium ions. The amount of sodium carbonate and sodium hydroxide added must exceed the theoretical requirements of the reaction to ensure complete removal of calcium and magnesium ions. Next, sodium hypochlorite is added. The reaction principle is that when the pH of the brine is greater than 9, adding sodium hypochlorite converts ammonium salts in the brine into monochloramine and dichloramine. The brine then enters the pre-reaction tank 3, where compressed air is introduced at the bottom for thorough aeration, blowing out some of the monochloramine and dichloramine gases. Finally, the brine is filtered through a ceramic membrane filter 4 to remove insoluble substances such as magnesium hydroxide and calcium carbonate. The filtered brine is introduced into the ammonium removal tower 5, where the monochloramine and dichloramine gases are blown out by the blower 9 and low-pressure steam. Simultaneously, the brine is refluxed through the return pipe 10 to recirculate and remove monochloramine and dichloramine gases, ensuring effective ammonium removal. The deammonium-removed brine then enters the baffle tank 6, where hydrochloric acid and sulfurous acid are added. The sulfurous acid removes any remaining free chlorine, and the hydrochloric acid adjusts the pH.

[0032] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments disclosed and described above, and some modifications and changes to this utility model should also fall within the protection scope of the claims of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. A brine ammonium removal system, characterized in that, The system includes a brine heater (1) and a purification reactor (2). Sodium hydroxide and sodium carbonate are added to the purification reactor (2) to react and remove calcium and magnesium ions. Sodium hypochlorite is added to react and convert ammonium substances in the brine into monochloramine and dichloramine. A pre-reaction tank (3) is set downstream of the purification reactor (2). Compressed air is connected to the pre-reaction tank (3) to blow out a portion of the monochloramine and dichloramine gases. A ceramic membrane filter (4) and an ammonium removal tower (5) are set downstream of the pre-reaction tank (3). The brine after ammonium removal enters the downstream baffle tank (6). Sulfurous acid is added to the baffle tank (6) to remove free chlorine. Hydrochloric acid is added to adjust the pH value.

2. The brine ammonium removal system according to claim 1, characterized in that, An intermediate tank (7) and a salt-dissolving tank (8) are also arranged sequentially between the impurity removal reactor (2) and the pre-reaction tank (3).

3. The brine ammonium removal system according to claim 1, characterized in that, Low-pressure steam is introduced into the lower end of the ammonium removal tower (5) to prevent brine crystallization and ensure the temperature inside the tower. At the same time, a blower (9) is installed at the lower end of the ammonium removal tower (5) to blow out monochloramine and dichloramine gases from the top of the ammonium removal tower (5).

4. The brine ammonium removal system according to claim 1, characterized in that, The outlet of the ammonium removal tower (5) is provided with a reflux pipe (10) which is connected to the upper end of the ammonium removal tower (5) to circulate and remove ammonium from the brine.

5. The brine ammonium removal system according to claim 1, characterized in that, The brine filtered by the ceramic membrane filter (4) is connected to the upper end of the ammonium removal tower (5) through a pipeline, and sprayed downward into the tower through several nozzles installed in the ammonium removal tower (5).

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