Problems with compressed air microheat regenerative dryers
Thread Content
I’m seeking advice from experts. Our company has two compressed air microheat regenerative dryers, which operate simultaneously. The dew point of these dryers remains stable at around -40 degrees. During the maintenance work in the third year, the original desiccants were replaced in both units. After they started operating again, one unit functioned normally, while the other unit had an unstable dew point, fluctuating between 0 and -30 degrees, and sometimes even showing positive values. Actual observations showed that in the normal unit, the temperatures at the top and bottom of the drying tower were relatively high during regeneration, ranging from 60 to 80 degrees. In the unit where the dew point was a problem, the temperature in the drying tower during regeneration was only around 50 to 60 degrees in the section approximately 20 centimeters away from where the hot gas entered; the temperature on the walls of the tower further down was at ambient level, around 30 degrees, which is quite low. Therefore, we tried several solutions, but none of them had a significant effect. 1. The volume of regenerated compressed air was increased; the valve setting was raised from 1/3 to 2/3. The noise level associated with exhaust air at the site was very high, and this even caused the compressed air pressure to drop from 0.65 to 0.6 MPa. The dew point improved slightly, but it still did not reach -40 degrees, and the temperature inside the tower was also not satisfactory. 2. The temperature of the regenerated gas was increased from 150 to 200; the dew point improved only slightly as well, with the tower temperature being in the 30s degrees. 3. Replace the alumina desiccant; the old desiccant is in good condition, with no signs of contamination or damage. 4. Check the filters at the inlet and outlet of the drying tower; if there is corrosion, replace them with new filters. The dew point issue persists. 5. Check the outlet silencer of the tower; it should not be clogged. When the tower is switched, a large amount of water vapor is emitted, and the exhaust gas is humid during regeneration. 6. The inlet temperature of the dryer is between 30 and 40, with little variation in the dew point. 7. The instrument showed that the resistance values of the three heating rods were normal. Basically, we have carried out the checks mentioned above, but they haven’t had much effect on reducing the dew point. Previously, with the same flow rate of compressed air, the dew point could be maintained at -40 degrees; yet now it fluctuates between 0 and -30 degrees in a sinusoidal pattern, changing every hour. I was wondering if there is anyone with extensive experience who can help resolve this issue – I would be extremely grateful! ! !
This phenomenon is mostly caused by internal leakage in the switching valve; it would be advisable to check whether there is any internal leakage. Furthermore, since one of the purifiers has a high water content as a result of the above issue, it should be heated intensively to remove the water. From a pressure perspective, it may be possible to obtain a relatively accurate assessment; however, it’s difficult to detect internal leakage in the switching valve by visual inspection. These include pressure equalizing valves. It is possible to remove all the switching valves and conduct a thorough leak test.
Okay, thank you. We checked the check valve earlier and it was fine; we’ll test the shut-off valve again
Bro, before discussing so many issues, let’s first determine whether the dew point measurement is accurate or not. My vision is poor; everything I see is blurry. 1. The volume of regenerated compressed air was increased; the valve setting was raised from 1/3 to 2/3. The noise level associated with exhaust air at the site was very high, and this even caused the compressed air pressure to drop from 0.65 to 0.6 MPa. The dew point improved slightly, but it still did not reach -40 degrees, and the temperature inside the tower was also not satisfactory. This scenario provides no guidance; as the flow rate increases, the values will definitely decrease. It is necessary to determine whether the dew point is at atmospheric pressure or under pressure ；
Has the original poster solved their problem? We’re facing the same problem; do you have any experience to share?