quote:

Originally posted by Stevonator:
So, maybe I'm missing the boat, but wouldn't it be easier to just heat a 55 gallon drum full of oil much the same way a fryer does and wait for it to stop popping? Just leave the small bung open to vent pressure. Once your above about 275 if there's any water it'll be entertaining to listen to....and safe as long as you are protected from the splatter. In other words you're doing a really huge frying pan test. A small stream could be pumped if you have a concern of suspended water.

quote:

Originally posted by Tim c cook:
I recently tried several dewatering techniques, Heat-and-let-settle, Spray hot oil through the air, electric frypan. None did what I wanted. All these require that the oil go round-and-round til it may finaly be dry ( high humidity in illinois never did let it get really dry). you have to keep testing the oil and run the process for however long it takes, I wanted to run the oil through a process once and be assured it was dry. -- FOUND IT .. FLASH EVAPORATION ...With this method you pump cold, wet oil into the heater and get absolutly dry, hot oil out.

This dry oil can then be collected into a separate container and immediately used, no waiting for the entire batch to get dry and no testing needed. It does take a bit of electricity, I figure around 2 cents per gallon on my prototype but I was not recovering any of the heat with it, the new unit will pre-heat the incoming wet oil by running it through tubing emersed in the outgoing hot condensed steam (around 200 deg F) and hot (300 degree f) oil. Everything will get wrapped in insulation. I think this will recover at least 1/2 the heat so the additional heat should only cost about 1 cent/gallon.

In the "sugar in WVO" thread (here,2nd and 5th posts down) Magnito describes his large flash evaporator, it does around 5 gallon a minute, my small unit does about 2 gallon/hour. His evaporater is a modified pressure type oil fired steam genny. This is way bigger than I need ( only need a couple gallons per hour if it can run unattended 24 hours/day) and his big unit has to be monitored continuously. I came up with a small version using an 1100 watt electric water heater element for the heat and a 12 volt shurflo RV pump to pressurise the oil to 90-150 pounds to keep the water from boiling inside the heater pipe, flow rate is about 2 1/2 gallon/hour.

The pressurized wet oil is heated by the water heater element inside a 12 inch long piece of 1 inch pipe, the heater is screwed into a "T" on one end of the pipe, the oil is input into the side of this same "T", the 300 degree hot,wet oil comes out the other end of the pipe through some sort of small oriface, the water immediately flashes off into steam due to the reduction in pressure. I initially used a ball valve as an orifice and sprayed the oil/steam into a cooking pot. This works (I dewatered 25 gallon this way, absolutely NO bubbles seen, not one, using the "frypan bubble test") but there is a fair amount of oil vapor that drifts off with the steam, it condenses on everything in sight , it also is a big fire hazard. I am now working on the next generation that uses a fixed size orifice from a oil fired furnace burner unit and sprays the hot oil/steam into a couple of small tanks (2 quart),the first tank seperates the steam from the oil, then the steam-with-oil-vapor goes into a second tank where the steam is condensed into water and the oil vapor is condensed back to liquid oil, the oil floats on the water so they can easily be seperated using a gooseneck grease-trap type method.

The flow through this unit is a balance between heat, pressure and flow rate. You want to keep the oil temp at around 300 deg f so if you add more heat you need to increase the flow rare linearly, twice the heat = twice the gallons/hour etc, as long as the pump can hold the pressure you can build the unit to dry what ever gallon/hour you want.

I am using a shurflo rv pump for the pressure. I was amazed that these pumps will create way over 150 pounds pressure (and survive, at least so far). I adjusted the pressure cutoff switch to 150 pounds and the pump cycles off at 150 pounds and back on at 90 pounds. I am working on a pulse width modulated electronic motor control for the shurflo pump that will hold a more constant pressure. You could also use a fueloil pump from an oil fired furnace burner, it does this exact same job on the oil burner.

On the prototype I ran the heater continuously and controlled the oil temp by slightly opening/closing the ball valve. This works but you have to tweek it every few seconds. On the new unit I am using a constant flow burner orifice and will use a thermostat to control the heater, this way the unit will run without needing to be watched or tweeked.

I think this unit can be reduced to fit in the space of less than one cubic foot. It also could be built to run entirely on 12 volt DC power for mobile dewatering

Here is a picture of the prototype dewatering oil. The steam can sorta be seen as lighter patches floating away from the pot, hard to see in a still pic.