Just ran across a client who needed me to quote some drills for an aluminum bracket / wood backer application (Thus the copy to two newsgroups)...
In the end, his quote was for somewhere close to $100k and I told him he needed to find a quality compressor that could supply 1000 SCFM, had an air dryer, etc.
I've never run across such an animal, but I'm guessing some of you have.
If you don't mind, tell me about the larger compressors you have run across so at least I can *act* like I know what I'm talking about when I quote these things...
I presume anything close to that size is going to be a screw compressor... But I could be indicating my lack of knowledge with that guess too.
Were using about 1500hp of compressors here at work, the largest units are 200hp ingersoll rand screws at 875 CFM at 125 psi, if you only needed 90psi, you could get close with a 200hp but otherwise you would have to go to a 250hp or even a 300hp for even higher pressure.
Before my retirement, I was Engineering Manager fora number of production companies,and we always had compressed air available. My best results generally was with Atlas Copco screw compressors and refrigerated air dryers. They varied in size from 500 to 2000 CFM. If capital is readily available, then get one with an inverter drive. Over a few years the electrical cost savings will pay for the additional cost. A refrigerated air dryer, is necessary. If you expect to use the compressed air for food or pharmecuetical use then an oil free compressor is required.
Well, I did see some gigantic Ingersoll one-lung compressors in a factory here on a tour. I was amazed they were from 1952. Gigantic horizontal cylinder about 8 - 10" diameter and probably a stroke of a foot.
But, today, everything big is rotary screw. 1000 CFM, if you are serious, is a HUGE compressor, and I doubt you can get a single unit in that size. They may come up to 500 CFM, but maybe they just make them bigger and I've just never seen one that size.
If you really need 1000 CFM, there may be serious power supply problems, this could require power for a several hundred HP motor.
I haven't worked on anything THAT Big, but Rule Number One in an industrial situation is you do NOT get one huge compressor and dryer to supply a factory - that one compressor fails, and you're screwed.
You get three screw compressors and refrigerated air dryers to match, at roughly 500 CFM each. Three units where two will handle all your needs gives you one down for maintenance and the place keeps running. And if one's already down for maintenance or repair and a second one dies, you have to cut consumption but you still aren't dead in the water.
You hook them up to a big manifold and have shutoff valves and vent/drain valves everywhere, so you can isolate the compressors and air driers under service and keep the main trunk line for the factory up and running.
And always plan the manifold oversized, because no matter how well you plan the needs will always grow. You'll want to add another big compressor or two as your needs grow.
And you have the Plumbers and Fitters rig the compressors and driers up so you can shut down, disconnect, and slide one of them out for service while leaving the others running.
Ring Mains in the factory with several shutoffs around the ring, so you can isolate sections for service (or to stop off a huge leak) while the rest of the place stays up.
Oh, and you still want to have a smaller (25 HP) piston unit or two around to hold pressure overnight for the Maintenance Crew, or for "Oh, S***!" situations. Like the big screw compressors 480V transformer or Motor Control Center just died, and the 25-HP one is fed from a separate 480V power system and still runs.
You don't want to leave a screw compressor running all night for nothing, and the Maintenance Crew doesn't want to mess with starting a unit up.
--------------------------------------- Back in the days when I was involved with such things, the rule of thumb to limit induction motor powered air compressors to 100 HP.
Today, the most economical are usually variable speed screw. There are still some recips, like the Ingersol Rand models that run at 100%,
50%, or 0% depending on load.
For 1000 cfm, you need about 150 HP. Good places to start are Kaeser, Ingersol Rand, Atlas Copco.
You need a well laid out installation also. Receiver tank(s), proper sized lines, proper piping, etc. You need a lot of 3 phase power also. A really good sales person can do all of that for you.
A friend's manufacturing business uses a very moderate amount of air MOST of the time, but when the autoclave requires pressurization it takes a LOT of air. He runs the main shop on a 10HP electric compressor - Webster I think, on a 50-ish gallon tank. When the autoclave is fired up, it is pressurized by a good sized diesel compressor - I think it's an Atlas Copco - a wheeled unit like used for air hammers etc in construction semi permanently installed in a corner of the shop, with external exhaust and air intakes and a furnace type oil tank that is filled from outside.
Price out that 8" pipe and you'll probably buy a receiver.
It also depends on the point of use of the air. If it is all used in one place, why pipe the entire perimeter with 8" pipe?
We have our machine area piped with 4" on the perimeter and have a receiver at each end. To the rest of the plant, a 3/4" copper line handles it all as it is only maintenance use.
Aside from everything else, check local laws. In our state, receivers and safety valves must be permitted and be inspected every two years. That 5 HP compressor many of you have in the garage is OK, but in a factory, the tank is subject to inspection.
It's practical as a backup - but primarily when the rest of the operation is air powered (or you also have a good backup generator) and you don't need Utility Power to keep the rest of the show going.
I wouldn't use it as a daily Prime Mover to run the whole place unless you also have a use for the heat produced, as in your own little Cogeneration Plant. You send the radiator and exhaust heat off to radiators to warm the plant, or to a adsorption chiller unit to make cold to cool it.
The other factor that would make it a great idea is the location - If you are way out in the boonies and have a tiny power line just enough to run a house, and it'll run you $100,000+ to beef up the utility feed to run your little factory. Or no power at all, and they want $250,000 to run 25 miles of poles and wires.
If it wasn't for the extra costs of the engine systems purchase, maintenance and repairs, and the fuel and supplies delivery costs, you might actually come out ahead buying Red Dye Off-road Diesel (no road taxes - the dye keeps people honest) versus buying utility power at full urban area rates.
Remember, the utility burns fuel to make power - then they lose half of it to conversion and resistive losses and inefficiencies getting it from the power plants to you. (Even when they make it with Hydro or other alternate sources, they still have transmission costs and losses) You burn fuel and make the power locally, and that cuts out all the transmission losses.
At best, it would be a very slight financial gain long term - then your big engine throws a rod and the crankcase and the crankshaft are both toast and you have to start over fresh...
(Diesel Option Not Available in dense urban areas with Smog laws - around here, the South Coast Air Quality Management District would have kittens if you even proposed it. They have strict limits on emissions - the Phone Company has to keep detailed logs on their testing and run hours on their backup generators, and huge fines can be levied for going over the permit limits.)
You can use Natural Gas for that, if you have a pipeline available. Caterpillar has several engine families that are Dual Fuel Diesel and NG. Suddenly your fuel costs just got a lot lower.
The factory/store we bought our furniture had no issues with electric tools but had to be self-sufficient. They weren't "allowed" to be connected to the grid, so had a bank of Cummins diesel generators. This store had electric lights but others in the area had gas lights.
I'm curious about NG cogeneration. Say I was to build a 10k sqft shop, radiant in the floors, well insulated. I could use NG for my radiant boiler, hot water and air makeup easy-peazy. But now I'm wondering about being off the grid, and maybe I can get a NG generator so I can "send the radiator and exhaust heat off to radiators to warm the plant, or to a adsorption chiller unit to make cold to cool it." That sounds slick...and expensive. I live upstate New York so def "need" both heat and AC. Somehow I'd want to be able to fine tune humidity levels too. And what would I do when power demand was low - do I need to run this generator 24/7/364? Would it be cost effective to stay hooked to the grid and sell the power back at these times? Or would I be better served by a smaller generator or some sort of battery back-up? PV, maybe? Doubtful...CNY is cloudy most of the time. Maybe I just stay hooked to the grid and run the generator during business hours. Probably no possible way that that's cost effective, even in the long run. Any good forums for this type of discussion? JP
I'd stay on the grid so you don't need to run it 24-7, but that's up to the local utility - they allow you to use Solar and Wind to back-feed excess power to the grid, I'm not sure if they'll let you do it with a Home or Small Business Cogen, because that's not "Green" energy. Silly rules, and you don't make them.
If they won't let you backfeed and sell them power, you just stop using the Utility power when you run the Cogen and cover all your own needs during high demand periods, and have Utility as a backup and for the low demand overnights & weekends.
You don't keep an expensive engine running 24-7 when your local energy demand is low, because it's not earning you all that much from the Power Company. If it wasn't for the advantage of reuse of waste heat for space heating or AC, it won't make sense.
Making cool from heat is fairly simple, look up adsorption chillers. The only reason they are expensive is they aren't being mass produced, start selling them by the thousands in a standardized style, and that price would drop like a rock.
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