In the field of synthetic ammonia, the shift gas generated in the shift section contains a certain amount of CO2 (18% to 35%). The removal of this CO2 is usually divided into two categories: dry and wet. Wet method can be divided into chemical absorption method, physical absorption method and physical-chemical comprehensive absorption method. The dry method is the pressure swing adsorption method. Using the pressure swing adsorption method to remove CO2 from the shift gas has the following significant advantages:

 

1. Low energy consumption. PSA operates at room temperature. Compared with the NHD method and the low-temperature methanol washing method, the energy consumption of refrigeration can be saved; it does not consume steam, which reduces the cold and hot diseases of the NHD and the low-temperature methanol washing process and the unreasonable part of the process setting.

 

2. Low investment and low operating cost. PSA is dry purification, with simple decarburization process, no liquid solvent regeneration and dehydration system; the adsorbent has a long service life, generally it can be used for more than ten years. No liquid or solvent loss during operation; no equipment corrosion problem.

 

3. The operation of the device is controlled by a computer, the adsorption tower is automatically switched, the fault is automatically diagnosed, the operation is convenient, the startup and shutdown are simpler and faster than other methods; the maintenance is simple, the maintenance time is less, and the operating rate is high; conditions such as the impurity content and pressure in the raw gas are changed It has strong adaptability, strong device adjustment ability, large operation flexibility, and wide adjustment range; when the device fails or needs to adjust the device's processing gas volume, it can be switched to different operating procedures as needed to avoid the entire line of the device due to minor failures Parking has a greater impact on production.

 

4. The device has high reliability. The pressure swing adsorption device usually only has the program control valve as a moving part, and the current program control valves at home and abroad are all patented products with long life and low failure rate.

 

5. The pressure swing adsorption device occupies a small area and is easy to expand. The PSA device can be expanded only by adding an adsorption tower and a programmable valve.