For the record, I didn't name it, somebody on the Hofart forum did years ago.
If you pay attention to nothing else in this posting, pay attention to this!
The Franzinator is a pressure vessel, and will operate in a very nasty environment of high pressure compressed air that is pulsating. If you aren't qualified to weld up a Franzinator with complete confidence DO NOT even attempt to weld one together. Improperly welded, the Franzinator has all the capability to blow apart and kill you! If it doesn't kill you, it will hurt you badly.
If you aren't competent to weld one together, you can still build a Franzinator using pipe fittings and threaded pipe. I'll post how to do that later.
There is one and only one Franzinator seperator, and I know because I developed it from a design given to me by an old timer. Over time, a lot of immitators have tried to duplicate and replicate the Franzinator. They have advanced their product and their concept of how it works. Some have even claimed to have improved upon the Mark I Franzinator. Unfortunately, they haven't been able to wrap their minds around everything that happens in the Mark I, let alone the Mark II water cooled Franzinator+.
My design has stayed the same for 30 years, because it works, and it works well. The specification and sizes are exact for a reason, they are what works. In all of the 30 years, I've only seen 1 person build his differently and get the same results as the Mark I model.
To begin, the Franzinator Mark I and Mark II are seperators. They are NOT dryers. Both devices accomplish the same function, but they do it entirely differently. Nearly all compressed air contains moisture as it leaves the compressor. A lot of energy is put into compressing enough cubic feet of free air into a cubic foot of air compressed to 100 psi, and some of that energy is converted to heat. Anybody who stayed awake during high school physics or meteorology remembers hot air can hold more humidity than cold air. Therein lies the first principal both Mark I and Mark II models work on. Chill the incoming airstream from the compressor as rapidly as possible, and force the compressed hot air to give up it's moisture.
The column of the Franzinator made from 2" pipe does this by forcing the airstream to impact the wall of the column immediately as it enters. The airstream enters the colum traveling in a downward direction, and begins cooling dropping water as it cools by expansion. Then, the airstream has to make a U turn since it can't leave the colum at a lower point than it entered, and must travel to the top of the colum to get to the receiver. In the process of this trip, the airstream expands. That minor expansion allows the airstream to act as a refridgerant gas, further cooling the column's housing.
The cooled airstream in the process of making the U turn drops a percentage of it's moisture by gravity into the sump of the column. Since the hot air stream is coming into the column at the coaxial center of the column, the air headed out has to flow along the walls of the column. This furtner cools the airstream, causing remaining moisture to condense into droplets on the wall.
Since the air is now even cooler, it cannot resorb the water from the inner wall of the column. The water that has condensed is also harder to pick back up because of the surface tension on the layer of water. There is also an unproven possibility that the column gains efficiency as the inner wall wets because of the affinity of water droplets to attach to the layer of water on the inside wall. As water accumulates on the surface, gravity carrys it to the sump.
The outside of the column cools by radiating its heat to the surrounding atmousphere. The trip thru the column takes between 10 and 20°f out of the compressed air stream before it leaves the column, and most of the water. Slower cooling of the airstream will not remove the same volume, even if the temperatures leaving the cooler match those of the Franzinator, because they do not employ the reversal of direction or the shock cooling of the column. Equal cooling by running the airstream thru a device such as an air conditioning coil leaves the compressed air in contact with the water longer, and allows a certain amount of resorption.
The dimensions of the Franzinator are somewhat critical. 2" pipe with a ½" elbow on the inlet provides optimum performance. A total column height of 36 to 38" also provides the greatest amount of seperation possible. Any water remaining in the airstream after leaving the Franzinator seems to condense on the inside of the receiver, and stay there.
A single column Franzinator is about perfect for a 2½ horsepower compressor running full out. Air volumes higher than that produced by 2½ hp need a second column piped paralell with the first.
The Franzinator MUST be plumbed into the system between the compressor and receiver, because that is where the maximum temperature differential can be acheived. For supercriticle situations, a secondary seperator of the same size and configuration can be employed to remove almost all condensate that finds its way out of the receiver.
Why the Franzinator is made from steel pipe- rather than copper tubing?
Very simply, steel and iron pipe radiate heat off to the surrounding atmousphere. Copper is not radiational. Copper can only transferr heat efficiently by conduction. If this design were set up as a water cooled seperator, copper would be more efficient. For an air cooled column, steel is best.
Why does the Mark II Franzinator use a wound copper coil around the steel column and not an all copper column?
Because it was what I had available when I built the Mark II, and because it worked far better than expected. I just wound a coil of 3/8 soft copper around the column with a greater coil density at the center and top than the sump end. My thinking was that maximum cooling was needed in the center where the hottest air enters the column, and minimal cooling was needed at the sump, with medium cooling at the top of the column. The coil is connected to an air conditioner coil via a tank and pump, much in the manner of a TIG torch cooler. Testing demonstrated a single Mark II removed as much volume of water from the airstream that a pair of Mark I columns could. When it works don't mess with it.
The pump picks up cool fluid from the tank and delivers the cool fluid to the top of the column. The cold fluid enters the coil at the top, and is pumped down along the column cooling the steel pipe. The fluid exits the column coil and heads back to the tank by way of an air conditioner coil. As the fluid passes thru the AC coil, heat is removed by air being drawn thru the AC coil by a muffin fan. The fan is installed to suck air thru the fins to provide even airflow across all the cooling tubes. The fluid exits the coil and returns to the tank where the pump delivers it back to the Mark II. The pump and fan run constantly so they can gain cooling on the fluid when the compressor isn't running and delivering heat load to the column. The fluid system is sealed to minimize evaporation loss, and prevent animal consumption of the antifreeze solution. In a climate where no freeze potential exists, water could be used in the Mark II system.
The cooling coil on the Mark II column is wrapped tightly around the column, and soldered to the steel column for maximum thermal transferr. Galvanized pipe was used for the Mark II column to make the soldering easier.
Either the Mark I or Mark II system can be improved by adding autodrain to the columns for a high volume air consumption system. This would be accomplished by adding reverse acting solonoid valves to the drain ports in place of the draincocs, and connecting them via a time delay relay to the compressor motor. The timer would be set for a few seconds to allow the initial low pressure airstream from the compressor to evacuate accumulated condensate from the column's sump. As with any autodrain system on a compressor, the performence of the valves needs to be checked regularly as they all seem to plug up over time.
For a real crappy drawing, click the thumbnail. It was drawn with version 63.77 of LeTurneauCAD.
I built a welded version of the Mark 1 and it doesn't seem to work.
I actually built 2 and hooked them up in series. I used 2" dia pipe 36" long. I fabricated the els and insured that they were faced downward before welding them in place. I am including pictures. Maybe you can tell me what I did wrong.
It does remove a ton of heat but no moisture. In fact I ran a water hose over the lower portions of the cylinders. This had no effect on the moisture removal. Just the temperature drop alone should remove some moisture. I have yet to get a drop of water from the petcocks. I do get plenty of water out of the tank petcock.