In pressure swing adsorption gas separation devices, some need vacuum desorption, such as refinery gas pressure swing adsorption hydrogen purification device, ammonia plant pressure swing adsorption decarbonization device, pressure swing adsorption carbon monoxide purification device, etc. In other chemical plants, it is often necessary to vacuum the container, so that the container can reach a certain degree of vacuum to meet the production requirements. Therefore, in order to meet the production requirements, the application of pressure swing adsorption pump in pressure swing adsorption device can play a very important role in this place.
Pressure Swing Adsorption (PSA) is a new gas adsorption and separation technology. It has the following advantages:
(1) The product has high purity.
(2) Generally, it can work at room temperature and under low pressure. When the bed is regenerated, it does not need heating. It is energy-saving and economical.
(3) The equipment is simple, easy to operate and maintain.
(4) Continuous cyclic operation can completely achieve automation.
Pressure swing adsorption (PSA) process is mainly used in fertilizer plants for the following two purposes.
1. Removal of carbon dioxide from shift gas
One is to remove carbon dioxide from the shift gas and produce liquid ammonia and methanol. This method does not recover carbon dioxide and is widely used.
2. Used in urea production
Another process is used in urea production. In addition to removing carbon dioxide from the shift gas to less than 0.2%, carbon dioxide must be purified to more than 98.5% for urea production. This process requires higher requirements than the first one, because it is relatively difficult to purify carbon dioxide under the guarantee of effective gas yield. However, no matter what kind of decarbonization, in order to improve the yield of effective gases, it is necessary to increase the concentration of carbon dioxide in the air and reduce the content of effective gases. Therefore, the design ideas of the above two processes are exactly the same.
In the pressure swing adsorption device, when the vacuum requirement and the vacuum pump pumping quantity are determined, the longer the pipeline is, the longer the pumping time is; the smaller the diameter of the pipeline is, the longer the pumping time is; the larger the molecular weight of the gas is, the longer the pumping time is. When the vacuum time is determined, when the characteristics of the pipeline system directly affect the pumping capacity of the vacuum pump, that is, the longer the pipeline is and the smaller the diameter is, the larger the pumping capacity and the higher the energy consumption of the rotary vane vacuum pump.
In fact, according to the existing refinery gas pressure swing adsorption hydrogen purification, ammonia synthesis plant pressure swing adsorption decarbonization, carbon dioxide purification and other devices, in the design of pressure swing adsorption gas separation device and some other chemical devices, the influence of pipeline holdup on vacuum pumping is a long-term problem for designers. A thorny problem. can not only quantify the key parameters of the vacuum system (such as the time of pumping, the volume of pumping gas, the diameter of pipeline, etc.), but also optimize the design of the vacuum system and make it more economical and reasonable.
In the pressure swing adsorption unit, because the adsorbed gas in the adsorbent in the adsorption tower continuously desorbs and desorbs in the process of vacuum pumping, it can be seen from practice that the smaller the diameter of the pipeline is, the longer the pumping time is. That is to say, the diameter of the pumping pipeline should not be too small, otherwise the vacuum pump pumping rate needed is too high, and the energy consumption will increase correspondingly, but too large the diameter of the pumping pipeline will also cause an increase in investment. Therefore, even though the application of pressure swing adsorption pump in pressure swing adsorption device is very important, it is also very important to select a suitable pressure swing adsorption pump.