A method of pressure swing adsorption water removal

By using pressure swing adsorption (PSA) and silica-alumina molecular sieve adsorbents, the problem of incomplete moisture removal from ammonia in existing technologies has been solved, achieving efficient purification of ammonia and significantly improving its purity.

CN115920586BActive Publication Date: 2026-05-29CHINA CATALYST HLDG CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
CHINA CATALYST HLDG CO LTD
Filing Date
2022-12-22
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

Existing technologies have failed to effectively remove moisture from ammonia, resulting in low ammonia purity.

Method used

The pressure swing adsorption method is adopted, and an adsorption dehydration system is used, including a first mixed gas buffer tank, a heater, a second mixed gas buffer tank, a booster pump, a condensate drain buffer tank, an adsorption tower, and a purified ammonia buffer tank. Through heating, pressurization, and temperature and pressure swing steps, ammonia is efficiently purified by using silicon-aluminum molecular sieves or pure silicon or pure aluminum molecular sieves as adsorbents.

Benefits of technology

It significantly improves the purity of ammonia, has high moisture removal efficiency, and reduces the moisture content in ammonia to 0.009-0.046% by mass.

✦ Generated by Eureka AI based on patent content.

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Abstract

The present application relates to the technical field of chemical separation, and particularly relates to a method for removing water by pressure swing adsorption; comprising: S1, mixed gas of ammonia and water enters a buffer tank 1; S2, the mixed gas in the buffer tank is heated to T1 and then is delivered to a buffer tank 2; S3, the mixed gas in the buffer tank 2 is pressurized to a pressure P by using a booster pump and then is delivered to a temperature swing pressure swing adsorption tower; S4, the temperature of the adsorption tower is T2; S5, after a certain time of adsorption, the adsorption tower is depressurized, the pressure at the top of the tower is less than P, ammonia gas flows out from the top buffer tank, and ammonia water flows out from the bottom. For the mixed gas of ammonia and water, the present application further removes water and purifies ammonia, and has the advantage of high purity of purified ammonia. In the present application, the ammonia gas mixed with water is purified, wherein the principle of absorption tower and temperature swing and pressure swing is used, so that the purity of the ammonia gas is efficiently improved.
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Description

Technical Field

[0001] This invention relates to the field of chemical separation technology, and in particular to a method for dewatering by pressure swing adsorption. Background Technology

[0002] Patent 201310053495.X describes a method for separating and purifying low-concentration ammonia water to prepare high-concentration ammonia. Dilute ammonia water is heated to form ammonia / water vapor, which enters a pre-separator. After cooling, water droplets are precipitated. The ammonia vapor passes through a membrane distillation unit under negative pressure to obtain high-purity ammonia gas. No subsequent dehydration operation is performed on the obtained ammonia gas.

[0003] Patent 201020244775.0 describes a tar-ammonia water separator device for separating tar and ammonia water, but does not further enrich and purify the ammonia in the ammonia water.

[0004] Patent 201220439745.4 describes a dilute ammonia water recovery system for a hydrogen extraction device. The system heats the dilute ammonia water and utilizes the different evaporation rates of ammonia and water to enrich the ammonia. However, the system does not perform any subsequent dehydration operation on the obtained ammonia gas.

[0005] Patent 201721804970.2 describes an adaptive condensing ammonia water separator device that separates ammonia water and uncondensed gas into gas and liquid, but does not perform subsequent water removal operations on the obtained ammonia gas.

[0006] For a mixture of ammonia and water, this invention further removes water and purifies ammonia, resulting in a higher purity of the purified ammonia gas. Summary of the Invention

[0007] The purpose of this invention is to provide a pressure swing adsorption method for water removal, which further removes water and purifies ammonia in a mixture of ammonia and water.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] The present invention provides a method for dewatering by pressure swing adsorption, including an adsorption dewatering system, wherein the adsorption dewatering system comprises a first mixed gas buffer tank, a heater, a second mixed gas buffer tank, a booster pump, a condensate discharge buffer tank, an adsorption tower, and a purified ammonia buffer tank connected in sequence.

[0010] Application steps of the adsorption water removal system:

[0011] S1. Introduce the mixture of ammonia and water into the first mixed gas buffer tank;

[0012] S2, the mixed gas in the first mixed gas buffer tank is heated to T1 by a heater and then transported to the second mixed gas buffer tank;

[0013] S3. The mixed gas in the second mixing buffer tank is pressurized to pressure P by a booster pump and then transported to the temperature and pressure swing adsorption tower.

[0014] S4. Adjust the temperature of the adsorption tower to T2;

[0015] S5. After the adsorption tower has adsorbed for a certain period of time (less than the time it takes for water to penetrate the adsorption tower bed), the bottom of the adsorption tower is depressurized, so that the pressure at the top of the tower is less than P. Ammonia gas flows out from the purified ammonia gas buffer tank, while ammonia water flows out from the bottom of the adsorption tower.

[0016] Preferably, the water content in the ammonia and water mixture is ≤4.5% by mass.

[0017] Preferably, the temperature range is 15≤T2≤T1≤100℃.

[0018] Preferably, the pressure range is 0.2 ≤ P ≤ 1.9 MPa, wherein the pressure P is lower than the saturated vapor pressure of ammonia and higher than the saturated vapor pressure of water.

[0019] Preferably, after being pressurized by a booster pump, the second mixing buffer tank is provided with a condensate drain buffer tank and a condensate drain outlet on the delivery pipeline for discharging any ammonia water that may be generated from the condensate drain outlet.

[0020] Preferably, two adsorption towers are arranged in parallel.

[0021] Preferably, the adsorption tower is filled with adsorbent.

[0022] Preferably, the adsorbent is a spherical or strip-shaped silica-alumina molecular sieve or a pure silica or pure aluminum molecular sieve.

[0023] Preferably, in step S5, the pressure is released to atmospheric pressure or below the adsorption pressure.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are as follows: the ammonia gas mixed with water is purified by using an absorption tower and the principle of temperature and pressure variation, thereby efficiently improving the purity of the ammonia gas. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 This is a schematic diagram of the installation of the pressure swing adsorption water removal method of the present invention. Detailed Implementation

[0027] This embodiment discloses a pressure swing adsorption method for water removal, including an adsorption water removal system. The adsorption water removal system includes a first mixed gas buffer tank, a heater, a second mixed gas buffer tank, a booster pump, a condensate discharge buffer tank, an adsorption tower, and a purified ammonia buffer tank connected in sequence.

[0028] Application steps of the adsorption water removal system:

[0029] S1. Introduce the mixture of ammonia and water into the first mixed gas buffer tank;

[0030] S2, the mixed gas in the first mixed gas buffer tank is heated to T1 by a heater and then transported to the second mixed gas buffer tank;

[0031] S3. The mixed gas in the second mixing buffer tank is pressurized to pressure P by a booster pump and then transported to the temperature and pressure swing adsorption tower.

[0032] S4. Adjust the temperature of the adsorption tower to T2;

[0033] S5. After the adsorption tower has adsorbed for a certain period of time (less than the time it takes for water to penetrate the adsorption tower bed), the bottom of the adsorption tower is depressurized, so that the pressure at the top of the tower is less than P. Ammonia gas flows out from the purified ammonia gas buffer tank, while ammonia water flows out from the bottom of the adsorption tower.

[0034] In step S1, the water mass percentage in the ammonia and water mixture is ≤4.5%.

[0035] In steps S1 and S4, the temperature range is 15 ≤ T2 ≤ T1 ≤ 100℃.

[0036] The pressure range is 0.2 ≤ P ≤ 1.9 MPa, where the pressure P is lower than the saturated vapor pressure of ammonia and higher than the saturated vapor pressure of water.

[0037] The second mixing buffer tank is pressurized by a booster pump, and a condensate drain buffer tank and a condensate drain outlet are provided on the delivery pipeline to allow any ammonia water that may be generated to flow out from the condensate drain outlet.

[0038] In this embodiment, two adsorption towers are installed in parallel.

[0039] In this embodiment, the adsorption tower is filled with an adsorbent; specifically, the adsorbent is a spherical or strip-shaped silicon-aluminum molecular sieve or a pure silicon or pure aluminum molecular sieve.

[0040] In this embodiment, the pressure is released to atmospheric pressure or below the adsorption pressure in step S5.

[0041] Example 1

[0042] A mixture of ammonia and water, with a water content of 4.5% by mass, was heated to 100℃ and pressurized to 0.5 MPa. Two switching pressure swing adsorption (PSA) towers used 3mm diameter 4A molecular sieve spheres as adsorbents, with an adsorption separation temperature of 95℃. After adsorption in a single tower, the pressure at the top was 0.45 MPa, and the pressure at the bottom was reduced to 0.1 MPa. Ammonia water flowed out from the bottom, while ammonia gas flowed out from the top. The ammonia gas at the top contained 0.031% water by mass.

[0043] Example 2

[0044] A mixture of ammonia and water, with a water content of 4.5% by mass, was heated to 100℃ and pressurized to 0.9 MPa. Two switching pressure swing adsorption (PSA) towers used 3mm diameter 4A molecular sieve spheres as adsorbents, with an adsorption separation temperature of 95℃. After adsorption in a single tower, the pressure at the top was 0.85 MPa, and the pressure at the bottom was reduced to 0.1 MPa. Ammonia water flowed out from the bottom, while ammonia gas flowed out from the top. The ammonia gas at the top contained 0.022% water by mass.

[0045] Example 3

[0046] A mixture of ammonia and water, with a water content of 4.5% by mass, was heated to 50°C and pressurized to 0.9 MPa. Two switching pressure swing adsorption (PSA) towers used 3 mm diameter 4A molecular sieve spheres as adsorbents, with an adsorption separation temperature of 45°C. After adsorption in a single tower, the pressure at the top was 0.85 MPa, and the pressure at the bottom was reduced to 0.1 MPa. Ammonia water flowed out from the bottom, while ammonia gas flowed out from the top. The ammonia gas at the top contained 0.011% water by mass.

[0047] Example 4

[0048] A mixture of ammonia and water, with a water content of 4.5% by mass, is heated to 50°C and pressurized to 0.5 MPa. Two switching pressure swing adsorption (PSA) towers use 3mm diameter 4A molecular sieve spheres as adsorbent, and the adsorption separation temperature is 45°C. After adsorption in a single tower, the pressure at the top is 0.45 MPa, and the pressure at the bottom is reduced to 0.1 MPa. Ammonia water flows out from the bottom, while ammonia gas flows out from the top. The ammonia gas at the top contains 0.015% water by mass.

[0049] Example 5

[0050] A mixture of ammonia and water, with a water content of 3.5% by mass, is heated to 50°C and pressurized to 0.5 MPa. Two switching pressure swing adsorption (PSA) towers use 3mm diameter 4A molecular sieve spheres as adsorbent, and the adsorption separation temperature is 45°C. After adsorption in a single tower, the pressure at the top is 0.45 MPa, and the pressure at the bottom is reduced to 0.1 MPa. Ammonia water flows out from the bottom, while ammonia gas flows out from the top. The ammonia gas at the top contains 0.013% water by mass.

[0051] Example 6

[0052] A mixture of ammonia and water, with a water content of 2.5% by mass, is heated to 50°C and pressurized to 0.5 MPa. Two switching pressure swing adsorption (PSA) towers use 3mm diameter 4A molecular sieve spheres as adsorbent, and the adsorption separation temperature is 45°C. After adsorption in a single tower, the pressure at the top is 0.45 MPa, and the pressure at the bottom is reduced to 0.1 MPa. Ammonia water flows out from the bottom, while ammonia gas flows out from the top. The ammonia gas at the top contains 0.012% water by mass.

[0053] Example 7

[0054] A mixture of ammonia and water, with a water content of 1.5% by mass, is heated to 50°C and pressurized to 0.5 MPa. Two switching pressure swing adsorption (PSA) towers use 3mm diameter 4A molecular sieve spheres as adsorbent, and the adsorption separation temperature is 45°C. After adsorption in a single tower, the pressure at the top is 0.45 MPa, and the pressure at the bottom is reduced to 0.1 MPa. Ammonia water flows out from the bottom, while ammonia gas flows out from the top. The ammonia gas at the top contains 0.011% water by mass.

[0055] Example 8

[0056] A mixture of ammonia and water, with a water content of 1.5% by mass, is heated to 50°C and pressurized to 1.5 MPa. Two switching pressure swing adsorption (PSA) towers use 3mm diameter 4A molecular sieve spheres as adsorbent, and the adsorption separation temperature is 45°C. After adsorption in a single tower, the pressure at the top is 1.45 MPa, and the pressure at the bottom is reduced to 0.1 MPa. Ammonia water flows out from the bottom, while ammonia gas flows out from the top. The ammonia gas at the top contains 0.009% water by mass.

[0057] Example 9

[0058] A mixture of ammonia and water, with a water content of 4.5% by mass, was heated to 100℃ and pressurized to 1.9 MPa. Two switching pressure swing adsorption (PSA) towers used 3mm diameter 4A molecular sieve spheres as adsorbents, with an adsorption separation temperature of 95℃. After adsorption in a single tower, the pressure at the top was 1.85 MPa, and the pressure at the bottom was reduced to 0.1 MPa. Ammonia water flowed out from the bottom, while ammonia gas flowed out from the top. The ammonia gas at the top contained 0.012% water by mass.

[0059] Example 10

[0060] A mixture of ammonia and water, with a water content of 4.5% by mass, was heated to 15°C and pressurized to 0.2 MPa. Two switching pressure swing adsorption (PSA) towers used 3 mm diameter 4A molecular sieve spheres as adsorbents, with an adsorption separation temperature of 10°C. After adsorption in a single tower, the pressure at the top was 0.15 MPa, and the pressure at the bottom was reduced to 0.1 MPa. Ammonia water flowed out from the bottom, while ammonia gas flowed out from the top. The ammonia gas at the top contained 0.046% water by mass.

[0061] Example 11

[0062] A mixture of ammonia and water, with a water content of 4.5% by mass, was heated to 15°C and pressurized to 0.4 MPa. Two switching pressure swing adsorption (PSA) towers used 3mm diameter 4A molecular sieve spheres as adsorbents, with an adsorption separation temperature of 10°C. After adsorption in a single tower, the pressure at the top was 0.35 MPa, and the pressure at the bottom was reduced to 0.1 MPa. Ammonia water flowed out from the bottom, while ammonia gas flowed out from the top. The ammonia gas at the top contained 0.029% water by mass.

[0063] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0064] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for removing water using pressure swing adsorption, characterized in that: The system includes an adsorption dehydration system, which comprises a first mixed gas buffer tank, a heater, a second mixed gas buffer tank, a booster pump, a condensate discharge buffer tank, an adsorption tower, and a purified ammonia buffer tank connected in sequence. Application steps of the adsorption water removal system: S1. Introduce the mixture of ammonia and water into the first mixed gas buffer tank; S2, the mixed gas in the first mixed gas buffer tank is heated to T1 by a heater and then transported to the second mixed gas buffer tank; S3. The mixed gas in the second mixing buffer tank is pressurized to pressure P by a booster pump and then transported to the temperature and pressure swing adsorption tower; wherein the pressure range is 0.2≤P≤1.9MPa, and the pressure P is lower than the saturated vapor pressure of ammonia and higher than the saturated vapor pressure of water; S4. Adjust the temperature of the adsorption tower to T2; where the temperature range is 15 ≤ T2 ≤ T1 ≤ 100℃. S5. After the adsorption tower has adsorbed for a certain period of time, which is less than the time it takes for water to penetrate the adsorption tower bed, the bottom of the adsorption tower is depressurized, so that the pressure at the top of the tower is less than P. Ammonia gas flows out from the purified ammonia gas buffer tank, while ammonia water flows out from the bottom of the adsorption tower.

2. The pressure swing adsorption method for water removal according to claim 1, characterized in that: The water content in the mixture of ammonia and water is ≤4.5%.

3. The pressure swing adsorption method for water removal according to claim 1, characterized in that: The second mixing buffer tank is pressurized by a booster pump, and a condensate drain buffer tank and a condensate drain outlet are provided on the delivery pipeline to allow any ammonia water that may be generated to flow out from the condensate drain outlet.

4. The pressure swing adsorption method for water removal according to claim 1, characterized in that: Two adsorption towers are connected in parallel.

5. The pressure swing adsorption method for water removal according to claim 4, characterized in that: The adsorption tower is filled with adsorbent.

6. The pressure swing adsorption method for water removal according to claim 5, characterized in that: The adsorbent is a spherical or strip-shaped silica-alumina molecular sieve or a pure silica or pure aluminum molecular sieve.

7. The pressure swing adsorption method for water removal according to claim 1, characterized in that: In step S5, the pressure is released to atmospheric pressure or below the adsorption pressure.