The adsorption dryer is a commonly used air compressor supporting equipment. Its main function is to reduce the moisture in the compressed air. If the adsorption dryer does not operate well, the moisture content in the output gas will increase. It will directly lead to the decline of product quality. Once it is found that the water content in the compressed gas is too high, it is necessary to check the dryer. Today, this article will introduce several reasons for the poor drying effect of adsorption dryers, hoping to help everyone.
1. The harm of "tunneling effect"
1. Once the tunnel is formed, the passage of compressed air is accelerated, and the moisture has not had time to be completely absorbed, and the compressed air has passed through, the adsorption effect is significantly reduced, and the dew point is increased;
2. The collision and friction between the adsorbents are intensified, the adsorbents are seriously pulverized, and the water absorption performance is reduced, which is fatal to the suction dryer;
3. The pulverization of the adsorbent is intensified, the life of the adsorbent is shortened, and the replacement cycle is shortened;
4. The adsorbent dust is easy to block the muffler and the rear pipeline filter of the suction dryer.
2. Uneven distribution of airflow
Because the air intake pipe of the suction dryer is much smaller than the diameter of the adsorption cylinder, under the combined action of the initial pressure and speed, the compressed air tends to pass through the packing in the container in a condensed state, and the gas distribution is not balanced, and there will be a considerable part of the packing If it cannot be fully utilized, a dead angle of adsorption is formed. Uneven distribution of air flow will greatly reduce the utilization of adsorbent.
3. Large energy consumption for regeneration
Reason: The height of the adsorption tower of the traditional double-tower structure suction dryer is high, which makes the water desorption process, the stroke is long; and due to the existence of the diffuser (or diffuser orifice) and the small diameter of the drain pipe, extremely The earth limits the smooth drainage. The above factors all determine that the traditional suction dryer does not have the ability to instantaneously desorb on its own.
The poor instantaneous desorption capacity makes the traditional double-tower suction dryer need to consume a lot of dry compressed air to complete the regeneration and purge of the adsorbent. Usually, the regeneration air consumption of the heatless suction dryer is as high as 12% to 15%, even if it is The regeneration air consumption of the micro-heat suction dryer is also as high as 7% to 8%.
Fourth, the formation of "tunneling effect"
Because the compressed air passes through the packing in the container in a collected state, the adsorbent in the center of the adsorption cylinder will be loosened and pulverized in about three months, thus forming a "fast-pass tunnel" in the adsorption cylinder. However, the filling of the adsorbent is not uniform and tight, and the frequent switching of the adsorption cylinder and the repeated impact of compressed air will also accelerate the formation of "tunnels".
5. Hazards of sorbent pulverization
1. It is easy to cause blockage to the rear filter installed behind the suction dryer
2. The post filter usually requires an accuracy of only 1um, which has a great impact on the back-end gas equipment.
3. The regenerated exhaust gas carries a large amount of dust into the muffler. If the muffler is blocked, it will bring greater damage to the dryer.
6. Difficulties in filling the suction dryer
1. In the case of unbalanced airflow distribution and serious "tunnel phenomenon", traditional double tower manufacturers have to use the mixed filling method of alumina and molecular sieve for the consideration of ensuring the dew point and preventing the pulverization and aging of the adsorbent.
2. The filling of adsorbent should follow the principle of uniformity, tightness and no dead angle. Uneven filling will make the "tunneling effect" more serious and affect the drying effect.
3. However, due to the large and deep capacity of the adsorption tower, coupled with the different structural sizes of molecular sieve and alumina, it is also an impossible task to achieve most of the uniformity, tightness, and no dead ends.
Therefore, the best way to make up for the filling defect of the adsorbent is to make it on-site after a period of use (the replacement cycle of the adsorbent is long and difficult).
7. The filling amount of the adsorbent is increased
Under the dual use of adsorption dead angle and tunnel effect, the utilization efficiency of the traditional double-tower suction dryer is not high, and the pulverization and aging are fast and serious. In order to compensate for this part of the loss, the traditional double-tower structure suction dryer manufacturers usually When prefilling the adsorbent, fill it with 50% more.
This is also the reason why traditional double tower manufacturers recommend users to replace the adsorbent in layers and batches, because if it is replaced at the same time, it will exist in the adsorption dead corner, and the unaged and pulverized adsorbent will be wasted. However, the replacement of layers and batches is technically difficult on-site, and it is almost impossible to complete on-site. At the same time, it is difficult to guarantee the filling process.