1. Basic working steps of pressure swing adsorption?
Pressure swing adsorption technology, because the adsorbent needs to be regenerated, the adsorption is intermittent. Therefore, two or more adsorption towers are used in the industry to alternately (or sequentially cycle) the adsorption and regeneration of the adsorption tower, one column is pressurized and adsorbed, and the other column is decomposed and decomposed to regenerate to ensure the entire adsorption process. Continuity.
2. What is the effect of the choice of adsorbent on the pressure swing adsorption unit?
The adsorption performance of the adsorbent for each gas component was evaluated by experimentally measuring the isothermal adsorption line under static conditions and the outflow curve under dynamic conditions. The good adsorption performance of the adsorbent is the basic condition of the adsorption separation process. The choice of adsorbent in the pressure swing adsorption process also needs to consider the contradiction between adsorption and desorption. It is necessary to select an adsorbent with a large adsorption capacity and easy desorption to reduce the power consumption of the depressurization desorption. Another point of selecting the adsorbent is that the separation factor between the components is as large as possible, thereby reducing the loss of effective gas.
3. What is dead space?
The so-called dead space not only absorbs the remaining space in the tower layer after deducting the volume occupied by the adsorbent. That is to say, when a certain component is adsorbed and balanced, the total amount in the adsorption tower has two parts, one part is in the dead space, and the other part is adsorbed by the adsorbent, and the sum thereof is called the retention amount of a certain component in the adsorption tower; The ratio of the amount of each of the weakly adsorbed component and the strongly adsorbed component contained in the dead space to the memory retention of the bed is referred to as the separation factor. The larger the separation factor, the easier it is to separate.
4. Why do you want to control the appropriate airflow speed?
During the operation of the adsorption tower, the pressure in the bed changes periodically, and the gas enters and exits in a short time. The adsorbent should have sufficient strength to reduce crushing and wear. When the gas flow rate is too fast, causing the adsorbent to suspend, the wear is intensified, causing the adsorbent to break and affect the service life of the adsorbent. Different adsorbents have different gas flow rates. This depends primarily on the strength of the adsorbent and the size of the adsorbent particles.
5. Why does the raw material gas entering the PSA unit have to be dehydrated?
If the separated gas contains free water and saturated water, only a certain amount of saturated water can be removed in the adsorption tower layer. Then, in the adsorption process, if a large amount of water is brought into the adsorption tower, the performance of the adsorbent may be degraded or even failed. At this point, the failed adsorbent needs to be reactivated or replaced. The activation of the adsorbent requires the use of an inert gas circulating at a temperature of 150 ° C or more, which is time consuming and laborious, and is quite difficult. Therefore, the water content entering the PSA unit must be strictly controlled during operation, and mechanical water must not be contained.
6. Why does the raw material gas entering the PSA unit have to be degreased?
If the separated gas contains substances such as organic mechanical lubricating oil and coal tar, these oily substances will adhere to the outer surface of the adsorbing particles during the adsorption process, blocking the passage in the adsorbent and causing the adsorbent to lose its adsorption. ability. Any adsorbent to which an oily substance is adhered, regardless of whether it is heated or depressurized, cannot be regenerated. Therefore, the oil content in the gas must be strictly limited. In some cases, a degreasing facility should be added to prevent the adsorbent from failing during use.
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