Acidic water pressurization steam stripping ammonia extraction system

Abstract

The utility model discloses an acidic water pressurized steam stripping ammonia extraction system, and belongs to the technical field of acidic water pressurized steam stripping treatment. The system comprises a stripping tower, a feeding pump, first to fifth condensers, first to fourth heat exchangers, an ammonia water mixer, an ammonia water tank, an air cooler, a hydrogen sulfide output pipe, an acidic water output pipe, a purified water output pipe, a first branch pipe, a second branch pipe, a header pipe and a flushing pipeline. According to the utility model, the middle part of the stripping tower is provided with three side extraction ports which are distributed in the vertical direction, so that the extraction amount of hydrogen sulfide along with ammonia gas is reduced, and the possibility of ammonium salt crystallization is reduced. Steam heat tracing is additionally arranged on the second branch pipe to reduce the possibility of ammonium salt crystallization. A high-temperature purified water flushing pipeline is additionally arranged at the low-temperature easily-blocked part of the second branch pipe, flushing is carried out regularly, the situation that the pipeline is blocked by crystals, liquid separation is not timely, and consequently the quality of ammonia water is unqualified is prevented, and long-period stable operation of the device is guaranteed.

Description

Technical Field

[0001] The utility model belongs to the technical field of pressurized stripping treatment of acidic water, and more specifically relates to a pressurized stripping ammonia extraction system for acidic water. Background Technique

[0002] In the existing integrated utilization device of low-pressure gas and acidic water, the acid water stripping tower in the acidic water pressurized stripping unit is of the side-line ammonia extraction type. The side-line stripping tower extraction layer is provided with an extraction port on the tray where ammonia is enriched. After extraction, it is cooled and flash-evaporated, and then ammonia water with a concentration of about 15-20% is obtained after water absorption. The main component of the top gas is hydrogen sulfide, and the bottom is purified water with H2S ≤ 50 ppm, NH3 ≤ 100 ppm, and oil content ≤ 50 mg / L.

[0003] During the actual operation process, it is found that the liquid level of the side-line amine extraction secondary condenser is full, and the liquid level cannot be discharged even when the bottom drain control valve and the control valve bypass line are fully opened, which seriously affects the quality of ammonia water. The improper proportion of side-line amine extraction leads to the extraction of hydrogen sulfide together with ammonia gas, forming ammonium salt crystals at the low temperature of the secondary condenser, resulting in pipeline blockage, inability to drain condensate in time, unqualified ammonia water quality, and excessive hydrogen sulfide.

[0004] Therefore, how to develop a pressurized stripping ammonia extraction system for acidic water is a technical problem that needs to be urgently solved by those skilled in the art. Content of the Utility Model

[0005] In view of this, the utility model provides a pressurized stripping ammonia extraction system for acidic water.

[0006] In order to achieve the above object, the utility model adopts the following technical scheme:

[0007] A pressurized stripping ammonia extraction system for acidic water includes a stripping tower, a feed pump, a first condenser to a fifth condenser, a first heat exchanger to a fourth heat exchanger, an ammonia water mixer, an ammonia water tank, an air cooler, a hydrogen sulfide output pipe, an acidic water output pipe, a purified water output pipe, a first branch pipe, a second branch pipe, a main pipe, and a flushing pipeline;

[0008] The outlet of the above-mentioned feed pump, the first condenser, and the top feed port of the stripping tower are sequentially connected by pipelines;

[0009] The outlet of the above-mentioned feed pump is connected to the first medium inlet of the first heat exchanger by a pipeline, the first medium outlet of the first heat exchanger is connected to the first medium inlet of the second heat exchanger by a pipeline, the first medium outlet of the second heat exchanger is connected to the first medium inlet of the third heat exchanger by a pipeline, and the first medium outlet of the third heat exchanger is connected to the middle feed port of the stripping tower by a pipeline;

[0010] The top of the above-mentioned stripping column is connected with a hydrogen sulfide output pipe. A reboiler is provided at the bottom of the stripping column. The liquid outlet at the bottom of the stripping column is connected to the second medium inlet of the third heat exchanger through a pipeline. The second medium outlet of the third heat exchanger is connected to the second medium inlet of the first heat exchanger through a pipeline. The second medium outlet of the first heat exchanger, the air cooler, and the inlet of the fourth heat exchanger are sequentially connected through pipelines. The outlet of the fourth heat exchanger is connected to the purified water output pipe;

[0011] Three side draw outlets are provided in the middle of the above-mentioned stripping column and are vertically distributed. The three side draw outlets are respectively connected to the second medium inlet of the second heat exchanger through pipelines. The second medium outlet of the second heat exchanger is connected to the air inlet of the first liquid separation tank through a pipeline. The top air outlet of the first liquid separation tank, the second condenser, and the air inlet of the second liquid separation tank are sequentially connected through pipelines. The top air outlet of the second liquid separation tank, the third condenser, and the air inlet of the third liquid separation tank are sequentially connected through pipelines. The top air outlet of the third liquid separation tank, the ammonia mixer, the fourth condenser, and the ammonia tank are sequentially connected through pipelines;

[0012] The bottom liquid outlet of the above-mentioned first liquid separation tank is connected to the first branch pipe. The bottom liquid outlet of the second liquid separation tank is connected to the second branch pipe. The first branch pipe and the second branch pipe are respectively connected to the main pipe. The main pipe is connected to the inlet of the fifth condenser. The pipelines of the outlet of the fifth condenser and the bottom liquid outlet of the third liquid separation tank are respectively connected to the acidic water output pipe. The purified water output pipe is connected to the second branch pipe through a flushing pipeline. A heat tracing sleeve is provided outside the second branch pipe. The above-mentioned heat tracing sleeve is provided with a steam inlet and a steam condensate outlet.

[0013] Further, the above-mentioned stripping column includes 49 trays, and the three side draw outlets are specifically distributed on trays 17 - 21.

[0014] Further, the above-mentioned reboiler is heated by steam, the first condenser to the fifth condenser are cooled by circulating water, and the fourth heat exchanger exchanges heat with circulating water.

[0015] Advantages of the present utility model:

[0016] In the present utility model, three side draw outlets are provided in the middle of the stripping column and are vertically distributed, reducing the amount of hydrogen sulfide drawn out together with ammonia and reducing the possibility of ammonium salt crystallization.

[0017] Adding steam heat tracing to the second branch pipe reduces the possibility of ammonium salt crystallization.

[0018] Adding a high-temperature purified water flushing pipeline at the low-temperature and easily blocked part of the second branch pipe, and flushing regularly to prevent the pipeline from being blocked by crystallization products, so as to avoid untimely liquid separation and resulting in unqualified ammonia water quality, ensuring the long-term stable operation of the device. Description of the drawings

[0019] Figure 1This is a schematic structural diagram of the acidic water pressurized stripping ammonia extraction system of the present utility model.

[0020] Figure 2 This is a schematic structural diagram of the heat tracing casing of the present utility model.

[0021] Figure 1-2 In it, 1 - stripping column, 2 - feed pump, 3 - first condenser, 4 - second condenser, 5 - third condenser, 6 - fourth condenser, 7 - fifth condenser, 8 - first heat exchanger, 9 - second heat exchanger, 10 - third heat exchanger, 11 - fourth heat exchanger, 12 - ammonia water mixer, 13 - ammonia water tank, 14 - first liquid separation tank, 15 - second liquid separation tank, 16 - third liquid separation tank, 17 - reboiler, 18 - hydrogen sulfide output pipe, 19 - acidic water output pipe, 20 - purified water output pipe, 21 - first branch pipe, 22 - second branch pipe, 23 - main pipe, 24 - flushing pipeline, 25 - air cooler, 26 - heat tracing casing, 27 - steam inlet, 28 - steam condensate outlet. Specific embodiments

[0022] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0023] The acidic water pressurized stripping ammonia extraction system includes a stripping column 1, a feed pump 2, a first condenser 3 to a fifth condenser 7, a first heat exchanger 8 to a fourth heat exchanger 11, an ammonia water mixer 12, an ammonia water tank 13, an air cooler 25, a hydrogen sulfide output pipe 18, an acidic water output pipe 19, a purified water output pipe 20, a first branch pipe 21, a second branch pipe 22, a main pipe 23, and a flushing pipeline 24;

[0024] The outlet of the feed pump 2, the first condenser 3, and the top feed port of the stripping column 1 are sequentially connected through pipelines;

[0025] The outlet of the feed pump 2 is connected to the first medium inlet of the first heat exchanger 8 through a pipeline, the first medium outlet of the first heat exchanger 8 is connected to the first medium inlet of the second heat exchanger 9 through a pipeline, the first medium outlet of the second heat exchanger 9 is connected to the first medium inlet of the third heat exchanger 10 through a pipeline, and the first medium outlet of the third heat exchanger 10 is connected to the middle feed port of the stripping column 1 through a pipeline;

[0026] The top of the stripping column 1 is connected with a hydrogen sulfide output pipe 18. A reboiler 17 is provided at the bottom of the stripping column 1. The bottom liquid outlet of the stripping column 1 is connected to the second medium inlet of the third heat exchanger 10 through a pipeline. The second medium outlet of the third heat exchanger 10 is connected to the second medium inlet of the first heat exchanger 8 through a pipeline. The second medium outlet of the first heat exchanger 8, the air cooler 25 and the inlet of the fourth heat exchanger 11 are sequentially connected through a pipeline. The outlet of the fourth heat exchanger 11 is connected to the purified water output pipe 20.

[0027] Three side line extraction outlets are provided in the middle of the stripping column 1 and are vertically distributed. The three side line extraction outlets are respectively connected to the second medium inlet of the second heat exchanger 9 through a pipeline. The second medium outlet of the second heat exchanger 9 is connected to the gas inlet of the first separation tank 14 through a pipeline. The top gas outlet of the first separation tank 14, the second condenser 4 and the gas inlet of the second separation tank 15 are sequentially connected through a pipeline. The top gas outlet of the second separation tank 15, the third condenser 5 and the gas inlet of the third separation tank 16 are sequentially connected through a pipeline. The top gas outlet of the third separation tank 16, the ammonia mixer 12, the fourth condenser 6 and the ammonia tank 13 are sequentially connected through a pipeline.

[0028] The bottom liquid outlet of the first separation tank 14 is connected to the first branch pipe 21. The bottom liquid outlet of the second separation tank 15 is connected to the second branch pipe 22. The first branch pipe 21 and the second branch pipe 22 are respectively connected to the main pipe 23. The main pipe 23 is connected to the inlet of the fifth condenser 7. The pipelines of the outlet of the fifth condenser 7 and the bottom liquid outlet of the third separation tank 16 are respectively connected to the acidic water output pipe 19. The purified water output pipe 20 is connected to the second branch pipe 22 through a flushing pipeline 24. A heat tracing sleeve 26 is provided outside the second branch pipe 22. The heat tracing sleeve 26 is provided with a steam inlet 27 and a steam condensate outlet 28.

[0029] In one embodiment, the stripping column 1 includes 49 trays, and the three side line extraction outlets are specifically distributed on the trays from the 17th to the 21st.

[0030] In one embodiment, the reboiler 17 is heated by steam, the first condenser 3 to the fifth condenser 7 are cooled by circulating water, and the fourth heat exchanger 11 exchanges heat with circulating water.

[0031] Process flow:

[0032] The sulfur- and ammonia-containing sewage is pressurized by the feed pump. The pump outlet is divided into two paths. One is the cold feed, which passes through the first condenser 3 and enters the column from the top feed port of the stripping column 1. The other is the hot feed, which is sequentially heated to 150 °C through the first heat exchanger 8 and the second heat exchanger 9 and enters the column from the middle feed port of the stripping column 1. A reboiler 17 is provided at the bottom of the stripping column 1. The hydrogen sulfide gas produced at the top of the stripping column 1 enters the subsequent deammoniation column through the hydrogen sulfide output pipe 18. The purified water is produced at the bottom liquid outlet of the stripping column 1 and is sequentially cooled by the third heat exchanger 10, the first heat exchanger 8, the air cooler 25 and the fourth heat exchanger 11 and then sent out of the system. The side line is rich in ammonia gas, which is cooled to 120 °C by heat exchange with the feed through the second heat exchanger 9 and then enters the first liquid separation tank 14. The gas phase at the top of the first liquid separation tank 14 is cooled to 90 °C by the second condenser 4 and enters the second liquid separation tank 15. The gas phase at the top of the second liquid separation tank 15 is further cooled to 40 °C by the third condenser 5 and enters the third liquid separation tank 16. The gas phase ammonia content at the top of the third liquid separation tank 16 can reach more than 99%. In the ammonia water mixer 12, the gas phase ammonia is mixed with desalted water to produce product ammonia water with a concentration of about 15%, and then enters the ammonia water tank 13 after being cooled by the fourth condenser 6. The liquid phase at the bottom of the first liquid separation tank 14 enters the main pipe 23 through the first branch pipe 21 in sequence. The liquid phase at the bottom of the second liquid separation tank 15 enters the main pipe 23 through the second branch pipe 22 in sequence. The liquid phase enters the fifth condenser 7 through the main pipe 23 and is cooled to 40 °C and then enters the acidic water output pipe 19 together with the liquid phase at the bottom of the third liquid separation tank 16.

[0033] The condensate produced by the second liquid separation tank 15 contains hydrogen sulfide, ammonia and carbon dioxide, and ammonium salt crystals are formed at the low-temperature part of the second branch pipe 22, blocking the pipeline, so that the device is frequently shut down for maintenance. To solve this problem, the ammonia extraction outlet is adjusted. Originally, the lower extraction outlet was generally put into use. However, it was found in the operation that due to the rapid changes in raw materials, etc., it was difficult to accurately adjust the high-concentration area of ammonia to near the lower extraction outlet. Therefore, the side line extraction outlet is changed from a simple lower extraction to a combined "upper and lower" extraction, which enhances the adaptability, can effectively reduce the hydrogen sulfide extraction amount, and reduce the possibility of ammonium salt crystallization. There are 3 side line extraction outlets vertically distributed in the middle of the stripping column 1, which reduces the amount of hydrogen sulfide extracted together with ammonia and reduces the possibility of ammonium salt crystallization.

[0034] Steam tracing is added to the second branch pipe 22 to reduce the possibility of ammonium salt crystallization and ensure that the temperature of the tracing return water is above 120 °C.

[0035] A high-temperature purified water flushing pipeline 24 is added at the low-temperature and easily blocked part of the second branch pipe 22, and flushing is carried out regularly to prevent the pipeline from being blocked by crystalline substances, so as to avoid unqualified ammonia water quality caused by untimely liquid separation. During flushing, the frequency conversion of the air cooler 25 is used to raise the temperature of the cooled purified water to above 100 °C, and the high-temperature purified water is introduced into the flushing pipeline 24 for flushing. After the crystalline substance NH4HS on the inner wall of the pipeline is dissolved in water by the high-temperature purified water, the flushing liquid is sent out of the device together with the condensate of the first liquid separation tank 14 and the second liquid separation tank 15. After the flushing is completed, the frequency conversion of the air cooler 25 is used to lower the temperature of the cooled purified water to 60 °C.

[0036] The description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An acidic water pressurized stripping ammonia extraction system, characterized in that, It includes a stripping column, a feed pump, a first condenser to a fifth condenser, a first heat exchanger to a fourth heat exchanger, an ammonia water mixer, an ammonia water tank, an air cooler, a hydrogen sulfide output pipe, an acidic water output pipe, a purified water output pipe, a first branch pipe, a second branch pipe, a main pipe and a flushing pipeline; The outlet of the feed pump, the first condenser and the top feed inlet of the stripping column are sequentially connected by pipelines; The outlet of the feed pump is connected to the first medium inlet of the first heat exchanger by a pipeline, the first medium outlet of the first heat exchanger is connected to the first medium inlet of the second heat exchanger by a pipeline, the first medium outlet of the second heat exchanger is connected to the first medium inlet of the third heat exchanger by a pipeline, and the first medium outlet of the third heat exchanger is connected to the middle feed inlet of the stripping column by a pipeline; The top of the stripping column is connected with a hydrogen sulfide output pipe, a reboiler is arranged at the bottom of the stripping column, the bottom liquid outlet of the stripping column is connected to the second medium inlet of the third heat exchanger by a pipeline, the second medium outlet of the third heat exchanger is connected to the second medium inlet of the first heat exchanger by a pipeline, the second medium outlet of the first heat exchanger, the air cooler and the inlet of the fourth heat exchanger are sequentially connected by pipelines, and the outlet of the fourth heat exchanger is connected to the purified water output pipe; Three side line extraction outlets are vertically distributed in the middle of the stripping column, and the three side line extraction outlets are respectively connected to the second medium inlet of the second heat exchanger by pipelines. The second medium outlet of the second heat exchanger is connected to the air inlet of the first liquid separation tank by a pipeline. The top air outlet of the first liquid separation tank, the second condenser and the air inlet of the second liquid separation tank are sequentially connected by pipelines. The top air outlet of the second liquid separation tank, the third condenser and the air inlet of the third liquid separation tank are sequentially connected by pipelines. The top air outlet of the third liquid separation tank, the ammonia water mixer, the fourth condenser and the ammonia water tank are sequentially connected by pipelines; The bottom liquid outlet of the first liquid separation tank is connected to the first branch pipe, the bottom liquid outlet of the second liquid separation tank is connected to the second branch pipe, the first branch pipe and the second branch pipe are respectively connected to the main pipe, the main pipe is connected to the inlet of the fifth condenser, the pipelines of the outlet of the fifth condenser and the bottom liquid outlet of the third liquid separation tank are respectively connected to the acidic water output pipe, the purified water output pipe is connected to the second branch pipe through the flushing pipeline, a heat tracing sleeve is arranged outside the second branch pipe, and the heat tracing sleeve is provided with a steam inlet and a steam condensate outlet.

2. The acid water pressurized stripping ammonia extraction system according to claim 1, characterized in that, The stripping column includes 49 trays, and the three side line extraction outlets are specifically distributed on trays 17 - 21.

3. The acid water pressurized stripping ammonia extraction system according to claim 1, characterized in that The reboiler is heated by steam, the first condenser to the fifth condenser are cooled by circulating water, and the fourth heat exchanger exchanges heat with circulating water.

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