A food processing plant was running out of compressed air capacity and decided to bring in an auditor to assess the size of the new compressor. The auditor hooked up his instruments to measure compressor pressure, power consumption and flow. Very soon, the auditor began to notice that things didn’t quite add up.
When in the compressor room, the auditor observed that two compressors were running fully loaded—yet when he looked at the compressed air flow meter he installed, he noted that the actual plant flow was much lower than the running capacity. This started an investigation of the plant air dryer, which was located between the compressor discharge and the flow meter.
Originally, the plant had installed a heated blower dryer to ensure very dry air for their unheated production area to prevent freezing. From the beginning, this dryer was trouble and had difficulty maintaining dew point. Control replacement and desiccant changes did not solve the problem; eventually the plant personnel decided to live with the problem.
But the auditor didn’t give up so easily. Some special testing was done and it was determined that the dryer was consuming more than 100 cfm of compressed air during its heating cycle (should be zero), and 200 cfm during a cooling purge operation that cools down the desiccant (should be 65 cfm). Nobody noticed this dryer had a leaky valve inside that was passing wet undried air into the side being regenerated. Further to this, it was discovered after carful inspection that the dryer had been misassembled with a re-pressurization valve swapped out for a cooling valve. This was the cause of the missing air!
The service personnel confirmed the problem and the mistake was corrected. This greatly reduced the compressed air consumption and improved the dryer operation. It is looking like there may be no need to purchase another compressor. This is another example of why compressed air system efficiency should be monitored and analyzed.
Learn more about air dryers in our next Compressed Air Challenge seminar in your area. Visit www.compressedairchallenge.org for more information.
By Ron Marshall for the Compressed Air Challenge
Filed Under: Pneumatic Tips