Controlling Energy Hogs #2
Foundry Analysis (Vacuum Pump Air Handling System)
Length of study: 6 months
Sensors used: AC Power Monitoring Sensors
Implementation time: 2 hours
Key data points included: Electric of power used every 2 seconds, 24/7
Projected Annual Savings: Potentially almost $100,000/year
Capital investment required: One variable speed drive
Pricing: complete system is under $18,000 (AFS corporate members receive a discount of over 20%).
Projected ROI: Less than 4 months
A large gray iron foundry wanted to explore energy use by electric motors in their vacuum pump generation area. These pumps are required to create the vacuum needed for V-Process casting operations. At the start of this AFS R&D project, plant management indicated felt that there may be energy savings opportunities involved with the motors driving the vacuum pumps but they had no “hard numbers” to prove that.
In order to monitor electric power usage, we instrumented the motors driving the vacuum pumps to
measure electric power usage, as well as monitoring vacuum pressure at the production floor. This monitoring system allowed us to examine and correlate vacuum pressures and electric power usage continuously, at 2 second intervals.
The vacuum pumps are operated in an “open loop” configuration - with no feedback control signals generated by the actual vacuum pressure at the production floor. In addition, the motors are running in an “on-off” mode; that is either running at full power, or not at all. Since air handling systems are present in virtually every foundry environment, this was a good candidate to include as an R&D project.
Research team developed 4 key project goals hoping to reveal savings opportunities with vacuum system “energy hogs”:
- Determine the cost-benefit ratio for adding variable frequency drives to the vacuum pump drive motors.
- Observe the correlation of vacuum pressure changes with power consumption changes
- Measure short-term fluctuations of the vacuum pressure on the pouring floor.
- Identify opportunities for saving power by monitoring weekend pump turn-on/turn-off times
What We Looked At