Energy Management: Your questions answered
Webcast presenter Tom Wenning from Energy Efficiency Research & Analysis (EERA) answered additional questions about topics such as artificial demand, dilute/dense phase transport replacement, and why you shouldn't open manual drain valves.
The "Energy Management" webcast was presented live on May 3, 2018, by Tom Wenning, program manager, Energy Efficiency Research & Analysis (EERA). The webcast can be found here. He supplied written answers to some of those questions that weren’t addressed from the webcast attendees:
Question: What should be the standard kwh consumption for full capacity running of centrifugal compressors?
Answer: A centrifugal compressor’s operating efficiency is typically around 16 to 20 kW/100 cfm. I’d recommend visiting the Compressed Air and Gas Institute (www.cagi.org) and checking out their compressor performance data sheets.
Q: What is artificial demand?
A: Artificial demand is defined as the excess volume of air that is consumed when supplying higher pressure than necessary for applications – unregulated and/or regulated to higher than necessary.
Q: What is a replacement for dilute/dense phase transport?
A: An alternative is a low- or high-pressure blower or a low pressure air compressor. You may want to take a look at the DOE’s compressed air sourcebook: "Improving Compressed Air System Performance"
Q: Why should you not open manual drain valves?
A: There are four main methods for draining condensate from the system: manual valves, level-operated mechanical traps, electrically operated solenoid valves and zero air-loss traps. While manual valves can be effective, they may be very costly from an air-loss perspective. They should never be permanently "cracked open" to allow continuous condensate removal – this is extremely costly. The best solution from an energy/cost viewpoint is a zero air-loss trap.
Q: From your audits, do you have some examples of typical savings from energy recovery?
A: Heat recovery efficiencies can range a tremendous amount depending upon the equipment and end-use of the heat. The recovery can range anywhere from 50 to 90% of the available thermal energy, but again, it depends. I would recommend taking a look at the Heat Recovery factsheet in the DOE’s compressed air sourcebook: "Improving Compressed Air System Performance"
Q: What is the most common ECM that you have dealt with, with respect to compressed air systems?
A: The most common are reducing leaks, reducing system pressure, modifying/improving compressor control and eliminating inappropriate uses.