One of the easiest ways to remove water from oil & Biodiesel is to heat & circulate it.
This can be done in a number of ways, but a really easy method for doing it is to build a simple dewatering tank using a 55 gallon drum, a transfer pump, a heater, and a spraying nozzle.
The basic theory is that spraying heated oil in a thin film will help the water to more easily evaporate. This creates a large surface area for the water to escape from the oil (air on both sides of the thin film) and with the oil heated, the water can more easily escape.
To accomplish this, you’ll want a spray nozzle that creates as fine of a film of oil as possible but doesn’t turn the oil into a mist. While misting the oil will work, it’s a sure way to also cover the rest of your work area with oil.
Making The Spray
To create the oil film, you can cut a notch out of a pipe and cap the end and run the heated oil through the pipe, or you can purchase pre-built nozzles, such as our Dry Pro Nozzle. The goal is to simply make a fan like spray in as wide of a pattern as possible.
Heating The Drum
The next step is to be able to safely heat the oil in the drum. We’ve seen everything from drop in bucket heaters, to heater spears (see Rilla Biofuels for a sweet, pre-built inline heater), to inline heaters that the oil circulates past on it’s way to the nozzle. But one of the safest methods is to attach a band heater to the outside of the drum.
This keeps the heating element away from the oil and also has the added benefit of evenly distributing the heat through the oil. Basically, you just need a reliable way to heat the oil up in the drum before it starts being circulated.
Circulating The Oil
Once the oil is heated, it’ll need to be circulated through the nozzle. One of the easiest ways to do this is to weld a fitting to the bottom of a drum (or attach a bulk-head fitting) and attach a transfer pump to the drum to pump the heated oil up to the nozzle.
The pump can be pretty much anything available. We find the inexpensive 1″ transfer pumps work really well. For piping, we recommend using black steel as it’s heat resistant and won’t break on you as easily as PVC Pipe or clear tubing might.
Plumbing The Tank
Nothing special here. You just need to connect the barrel to the pump, the pump to pipe, and the pipe to the nozzle as close to the top of the drum as possible.
Here’s a basic layout we came up with that uses as little plumbing as possible, but you can use whatever works best for you:
Once you get it all plumbed up, give it a test with some water to make sure the plumbing is all sealed up (water is a lot easier to clean up than an oil leak). Once you’re leak-proof, you’re ready to go.
We do recommend adding a by-pass valve though as we show in the diagram. This allows you to control how aggressively your spray nozzle spray’s and also makes a handy way to transfer the oil out of the tank.
Here’s a link to our step-by-step guide on building one of these tanks:
Instructions For Using The Tank
1) Fill the tank up about 2/3rds of the way full
2) Turn on the heater and bring the oil temperature up to at least 100 deg. F
— The hotter you can get the oil, the faster it will dry
3) Turn on the pump and start circulating the oil
How Fast It Dry’s
If your oil is REALLY wet (flunks a hot pan test something terrible), then it can take several hours to dry. But if it’s just slightly wet, usually 2-6 hours can get the job done. If the ambient room temperature is low (ie. below 60 deg. F) or if it’s really humid, it can take longer to dry, but given enough time, it’ll dry the oil out.
Tips & Tricks
– Adjust the spray of the oil so that it’s not spraying too hard to cause oil to come out of the drum (use the by-pass valve)
– Place a fan next to the drum & blow air ACROSS the top of the drum (not into the drum & not sucking out of the drum, but across the top).
– This creates a low air pressure above the drum and the moisture will get sucked up & blown away faster
– Plumb a temperature gauge into the plumbing. Usually just above the pump or just before it goes into the tank are ideal spots.
We offer complete kits with everything in them but the drum if you don’t feel like hitting the local hardware store.
Here’s the link: