Air compressor optimization
Air compressor optimization
(OP)
I'm currently working on the air compressor optimization project.
We have max.750cfm air consumption 7 hrs/day, and 350 cfm consumption 17 hrs of cyclical load/no-load regime (15 sec. load and 45 sec. unload). Type of compressor in use is piston. We are planning to develop new utility area and install new compressors. We have another 1200cfm Denver-Gardner Electro-Saver compressor, which is currently not in use. The problem is that I believe that 1200cfm compressor is too big and cost ineffective to run in terms of motor HP utilization and energy consumption. However, Denver-Gardner Electro-Saver has an option of automatic adjustment to air load, which they believe can save a lot on energy consumption by constant pumping air 24 hrs/day at different motor utilization depending on air load (no load/no-load regime). According to my calculations it is more expensive to run electro-saver rather than regular load/no-load regime.
I would appreciate any ideas for sizing compressor and the most efficient way to run it: load/no-load regime or 24 hrs constant run with automatic adjustment for a current load.
We have max.750cfm air consumption 7 hrs/day, and 350 cfm consumption 17 hrs of cyclical load/no-load regime (15 sec. load and 45 sec. unload). Type of compressor in use is piston. We are planning to develop new utility area and install new compressors. We have another 1200cfm Denver-Gardner Electro-Saver compressor, which is currently not in use. The problem is that I believe that 1200cfm compressor is too big and cost ineffective to run in terms of motor HP utilization and energy consumption. However, Denver-Gardner Electro-Saver has an option of automatic adjustment to air load, which they believe can save a lot on energy consumption by constant pumping air 24 hrs/day at different motor utilization depending on air load (no load/no-load regime). According to my calculations it is more expensive to run electro-saver rather than regular load/no-load regime.
I would appreciate any ideas for sizing compressor and the most efficient way to run it: load/no-load regime or 24 hrs constant run with automatic adjustment for a current load.





RE: Air compressor optimization
we are a small foundry getting by with 150cfm screw, by means
of two ways, we installed large lines, 3" loop all over the shop, and back in the molding are we have a 1200 gal. tank
the tank takes awhile to pump up but even with or automatic running full bore we never have a problem
# we run a B&P 2016 at 120 mph + 3 jolt squeesers with 14 to 18 inch squeeze cyl. plus the air opp. grinders in cleanup.
we learned to get rid of the small leaks and the smaller screw
has been very efficiant
RE: Air compressor optimization
I like to run a water cooled wet screw at about 80% duty. An air cooled unit would be at 70-75% duty. As Sbi posted, an inplant reciever will smooth out your duty.
RE: Air compressor optimization
Ingersoll Rand has variable speed arrangement to take care of fluctuating loads.
If your compressor is loading and unloading frequently, check for the leakages in the system. Close all the terminal valves and drain valves in the system.At the point of no consumption check the loading and unloading times.
%leak = loading time *100/(unloading time - loading time)
Generally accepted leakage rates are 5 to 10%.
Check this link http://www.conservair.com/ (if you are not aware of already)They have very good systems (add ons) for compressed air management.
Finally, compressed air pressure requirement for any equipment reduces when you supply constant pressure air. By reducing pressure you can save compressor power as well as leakage in the system.
RE: Air compressor optimization
RE: Air compressor optimization
The 1200cfm Gardner-Denver is a screw machine that CAN operate without a receiver but it's not a good idea. A lot of money tied up in the machine so why not opt for a decent sized receiver, at least 1000 gal. capacity is a guess. It will smooth out the peaks in pressure and ease compressor loading during short term, temporary spikes in demand. Keep in mind that during normal maintenance service the machine will be down for 4 or more hours and you may need a backup. Why not cycle more than one machine to moderate the load during off demand?
As to leaks---leaks will kill ANY compressor and contrary to the above, IMHO, 10% is TOTALLY unacceptable. I am not happy with 1 o 2%, but sometimes I just can't seem to find them all. You cannot put in words the calls that are made saying my compressor will not keep up anymore---when a service rep goes out, invariably the problem can be traced to leaks. Leaks and lack of maintenance is the biggest killers of industrial air units (most often they go hand in hand).
Rod
RE: Air compressor optimization
RE: Air compressor optimization
What could be an ideal leakage? Isn't it 0%? And who is that Alchemist who could try for it?
Length of piping, type of end use and the interest of engineer or the variables which decide the leakage. Controlling between 5 to 10% will also give you good savings for I saw worst plants (with leakages upto 30% and the engineers were pretty sure about the tightness of their system before doing the audit, because they said they never observed any noise.lol)
And as far as our type of plant was concerned (Pharmaceutical) I could never acheive below 5% on a real basis. If you guys did then Bravo! (Once you do the tightening job how long will it hold?)
If you are patient enough to search the internet with 'compressed air leakage' the rough values given are below 10%. But as far as my practical experience is concerned it is upto 5%.
RE: Air compressor optimization
Keep after it, quark. I know it can drive you nuts but the end result can be worth it.
Rod
RE: Air compressor optimization
As for leakages, I can give you my opinion only based on my own experience. It is pretty much impossible to define exact percentage of leakages in my plant- we have a continuous process with constant usage of compressed air. But anyway, leakages more than 5% are unavoidable for large scale production. At least in cost effective manner. I tried to estimate the costs for line enspections and fixing all the leaks (moreover, you can not identify them all) and cost savings for 2-3%. I can say that it does not worth it. You'll get a little payback with relatively distant break-even. If you have leakages within 5% you are good. Again, it is only on the large scale production with hundreds feet pipe lines.
Thank you again, you all great!
RE: Air compressor optimization
RE: Air compressor optimization
I still couldn't imagine Why you didn't eat me out for my arrogance
In my plant the main culprits were 3/5 way valves, quick exhaust valves and pneumatic pistons. I really vexed up finding the leakage shoot up every week. Till this time I thought restricting leakage below 5% was practically impossible (may be because I never used ultrasonic detectors or any other hitech gizmo)
I will be much delighted to know what procedures you follow in determining leakage or reducing the wastage?
Note: I assure I will take more care in my future posts.
Cheers
RE: Air compressor optimization
Quark, I have no magic to give you. I did it 'the old fashioned way', a stethascope and a bottle of soapy water(actually it was "Leak Detector"). As to arrogance, compared to me, you are just a beginner. My hat size has incresased TWO sizes since we started this thread!!!
Rod
RE: Air compressor optimization
Cheers!
RE: Air compressor optimization
Went out to my shop this morning. My air system was down! First time in a long while, perhaps one day I'll stop bragging as it allways seems to come back and bite me in the arse!
Rod