Industrial Utility Efficiency

# Aluminum Plant Meters Compressed Air Flow to Solve Capacity Issues

A major Midwestern aluminum plant was experiencing dwindling compressed air capacity, primarily due to air leaks. If those capacity issues went unresolved, the facility would have needed rental compressors to keep up with demand. Instead, they turned to flow metering to identify and fix the leaks. In this article, they share their solutions with others who may be having similar difficulties.

“We have a huge operation here smelting aluminum and making sheet aluminum for the food and beverage industry,” said Mark, the utilities engineer. “A short while back we began to lose compressed air capacity. First I checked our air compressors. We have two centrifugal compressors that put out about 20,000 standard cubic feet per minute (scfm) backed up by eight reciprocating piston compressors that come on as demand increases. Compressed air system pressure is between 80 and 90 psi and our compressors run 24/7/365.”

### Flow Metering More Than Compressed Air

“We use high-temperature water as a heating medium for some of our processes. Our high-temperature, closed-loop water system delivers hot water at 350°F,” said Mark. “We use the heat from heat exchangers to heat buildings, process fluids, wash aluminum sheets, etc. We pay the power plant for the high-temp water, and we had an issue. We had no meter to measure what we were receiving. The only meter involved was an orifice meter at the power plant. They told us how much water we were using and how much to pay.

“But we had a history with them of lower temperatures than we wanted, and sometimes we felt the flows to our process areas were slower than we needed,” Mark explained. “I proposed another FLEXIM meter for the hot water line. After our experience with the FLEXIM portable, I had no problem getting approval to purchase a permanent clamp-on FLEXIM liquid meter to measure the flow and temperatures to and from the plant. Now I’ve got sensors on the supply, on the return, and I’ve got temperature sensors on the pipe.”

“Because of my previous knowledge of the air meter, I knew how the new one worked and had it installed and working in very short order. Both meters have data collection ability. The power plant was saying one thing, and we were saying another. Our flow data were showing lower by 500 gallons per minute or more than the power plant. Then we got into some other problems in the winter when the temperature of the water dropped and finishing lines were unable to maintain run speeds. I pulled the data from the meter and showed power plant engineers our flow and temperature data.”

“We got together and started understanding each others’ processes. They ended up checking their orifice plate computer and found it was calibrated wrong. Their guy looked at our figures and said, ‘Well your numbers make sense because the maximum we can pump is 4,000 gallons per minute, and were showing 4,300 gallons right now.’ Who knows how long its been out of calibration. After they made their calibration adjustments, our number got a lot closer together.”

“As someone once said, you can’t manage what you can’t measure.”

For more information, contact Jack Sine, tel: (845) 831-6578, email: jack.sine@verizon.net.

To read more about Flow Meters, please visit www.airbestpractices.com/technology/instrumentation.

To read more about the Metal Industry, please visit www.airbestpractices.com/industries/metals.