induced draft , forced air cylinder

[farmerden]

Wes Now a flame out the stack caught my attention!! How do you lubricate the bearing between the fan and the turbo? My truck's turbo was oiled by engine oil and we don't have any here and no oil pressure either.No doubt your Dad solved that problem. Den

[87gn@tahoe]

LOL

The turbo was/is no longer fit for automotive use.. bearings are shot and it ate a couple of the compressor blades while it was still on my GN i.e. LOTS of play in the shaft and LOTS of blue smoke out of the car's exhaust...

He just added a zerk fittig to the oil inlet and a valve on the outlet to drain out any condensate.. turns a bit slowly when cold, but speeds up when the heat is turned up... On a turbo with "good" bearings, I would probably use some type of steam turbine luricant that will not froth up when contaminated with water and drain once in a blue moon (perhaps Bart has some input on oils to use in water environments?... His converted compressor-steam engine for example)... OR, one could make a simple solid centre section with sealed bearings on either end.

[barts]

Well, I finally ran a quart of water plus 2T of cylinder oil in the crankcase of that old compressor; it leaked so much that I didn't want more oil in the bilge or in the exhaust....

Anyway, I use something like one of these:


http://www.nexflowair.com/adjustable_air_amplifier.php

to force more air into the boiler when I want to go racing

Lots of draft, not much steam consumption, and easy to fit.

- Bart

[Maltelec]

Easy to make as well.

[Richard Orr]

John, you asked me about my boat. I would be all too glad to describe it but suppose I should try and do it under he heading of "Steamboat Stuff". I say "try" because I tend to loose what ever bloody thing I type up.

[fredrosse]

It appears that you really only need the air jets in the firebox to create the turbulence necessary to liven the fire. If this is the case, then you can use an ordinary natural draft chimney which will keep all of the boiler under a slight vacuum. A six foot stack at 580F produces only about 0.04 inches of water column differential pressure to cause flow within the boiler and combustion system. Air jets to liven the fire have been used in industry for over 100 years.

Designing the boiler to have sufficient combustion air for full load operation when using the moderate differential pressure of a short natural draft stack is then the technical challenge. With small water tube boilers this can be easily accomplished. With firetube boilers this is usually difficult, due to the lack of open flow area thru the system.

As for the air jets to create turbulence through the fire/fuel bed, a high speed centrifugal fan would be applicable, an automotive turbocharger (with steam thru the turbine section) could do the job quite well, as mentioned by others. However this machine will be turning at high speed, probably thousands of RPM, and of a capacity well in excess of what you need. While an automotive turbocharger is probably big enough to provide full combustion air, and to force this flow thru the boiler, it would frequently produce a positive pressure firebox, with the disadvantages mentioned in previous replies.

A reciprocating blower can easily produce the pressure you need, probably a few inches of water column thru small jet orifices. Be careful not to produce too much flow, so that the furnace always is under a slight vacuum when opening the fire door. The reciprocating blower will use up significant power if grossly oversized. Probably only a few percent of the total combustion air needs to be pumped thru the firebox jets, the rest of the combustion air can come thru odrinary inlets using the natural drafr of the stack.

If you need help determining the desired pressures and flow rates for the air jet system, send a PM and we will cook some numbers up.