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WVO and centrifugal forces

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  • WVO and centrifugal forces

    I have been reading a lot till now about SVO and WVO and my current impression is that running a diesel on new SVO according to certain standards is quite easy while the use of WVO has a few more challenges.

    What I didn't find is any information on dealing with WVO using centrifugal forces. Does anybody have experience with this?
    I am a mechanical engineer so far away from chemistry but my general knowledge tells me that centrifugal forces are a very effective way to seperate different parts of liguid and especially solids.

    I came accross this idea reading that it is the best to have WVO standing around for some weeks to settle before using it. This should be reduced with centrifugal forces to a few seconds or maybe a minute.

    Thought I throw this into the forum in case this might be something for easy improving of WVO. Don't mind designing a simple unit if this method would make sense.

  • #2
    Re: WVO and centrifugal forces

    I have used veg oil which has sat for 12 months or so, and the clarity and ease of dealing with it would seem to make it worth while.
    Would this be a batch or continuous type?
    cheers<BR>Chris.<BR>1990 landcruiser 80, 1HD-T two tank, copper pipe HE+ 20 plate FPHE, toyota solenoids and filters. 1978 300D, elsbett one tank system.<BR>

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    • #3
      Re: WVO and centrifugal forces

      So my idea might have some validity. Good to know.
      I would first start with a batch unit, using stuff that you can get at any Bunnings or Warehouse.
      Continuous processing is a bit hard to start with.
      What I suggest is that I have a look around what parts are easily available (and cheap) and then post a possible design for everybody to comment.

      Does anybody have connection to a chemist lab where a small sample can be put through these small centrifuges to determine what you exactly end up with?

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      • #4
        Re: WVO and centrifugal forces

        Hi eddi,

        Centrifuges would be ideally suited to the cleaning and possibly dewatering of WVO. Units which could continuously process oil would be a boon for both SVO and biodiesel users alike. Fabrication of such equipment is probably a little beyond the average back yarder as I'm sure you're aware, the biggest challenge is the ballancing of high speed rotating masses. If you could come up with a safe, simple and effective design that was cheap to build then you would revolutionise the WVO world (pun intended).

        There have been lengthy discussions of this topic on another forum, here's a couple of links:

        http://biodiesel.infopop.cc/eve/foru...3861038251/p/1

        http://biodiesel.infopop.cc/eve/foru...1/m/9751014751

        Keep the ideas coming, I'm happy to discuss this further as this is something that interests me and I might have a go at making one someday.

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        • #5
          Re: WVO and centrifugal forces

          I have been running my 1976 W123 300D on WVO since June 2006.

          While we're talking about centrifugal forces, has anyone had experience with using the spin cycle of a washing machine to speed up cold filtering of WVO?

          What I am thinking of doing is pulling out the centre spindle of a 9kg capacity top-loader and having a heavy duty calico or canvas filter bag made to fit the tub. I would then process my cold oil, 20 litres at a time, via the spin cycle and collect the low melting point oil from the outlet for further filtering through a 1-5micron filter bag. The machine spins at 1200rpm, so this should push the oil through much faster than gravity alone.

          What concerns me a bit is that the HMP oils might also be forced through at these rpms, and I'd be back where I started.

          I've searched around but haven't found anyone who has recorded using a washing machine in this way, although I found a reference to a woman who used a twin tub machine to make and process biodiesel.

          My other thought is to seal the tub of a washing machine so that the oil cannot be expelled. After a few minutes on high spin, slowly reduce the speed of the spinning tub and when stopped, the oil will have been separated, allowing the the low melting point oil to be syphoned off the top. Again, would this have any potential to work?
          Cheers
          Bruce


          1976 W123 300D (3 litre 5-cyl NA diesel running on SVO since June 2006)
          1982 W126 280SE (Sadly is For Sale)
          1993 W124 300D (3 litre 6-cyl NA diesel - being converted to SVO)

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          • #6
            Re: WVO and centrifugal forces

            I have been wondering the same question for a while now but I'd make a slight modification. Replace the perforated basket with a sealed or solid rotor with an inward facing flanged rim on the top of the rotor. The heavier liquids (water/fats) and crud would be flung against the walls of the rotor and the clean oil allowed to spill out over the top of the flange to be collected in the outer drum.

            The commercial version is shown in the picture (attached).

            The main problem with washing machines is that the drum is sprung mounted and damped with a lump of concrete. In a clothes wash cycle most of the water is flung out before the drum reaches maximum revs. If the drum were to be loaded with say 15-20L of oil, then that would be a lot of weight to spin and keep balanced as this fellow found out:

            http://biodiesel.infopop.cc/eve/foru...9751014751/p/6

            JOAT had the bright idea of using a car hub, brake drum and wheel bearing as a centrifuge (scroll down this page):

            http://biodiesel.infopop.cc/eve/foru...3861038251/p/3

            All possible with a bit of igenuity and a good workshop.

            Comment


            • #7
              Re: WVO and centrifugal forces

              Hi All
              How about a hydrocyclone to do that guys? It is just like a cyclone that separates air and solids
              If you where to look behind some dish washers the have this little gadget they take out the solids usually found in dirty dishes
              They do that by pumping the dirty water as it is picked up from the bottom of the machine before it gets to the spray bars
              I would have thought that this device will at least take all the crud out of the WVO
              With a bit of mucking around they should also be able to give you a separation based on specific gravity
              The heavier oil will come out of the bottom lighter stuff through the top
              Just food for thought on the subject
              They are used in the mining industry extensively to do separations of slurries
              Cheers
              Chris
              Cheers
              Chris
              Never give up :)

              Comment


              • #8
                Re: WVO and centrifugal forces

                Hi Eddi,
                I ran a test on a lab centrifuge. The oil (hot filtered) is giving me problems because as the fat crystallises out it stops the settling process of ultrafine particles. Even though the oil had been through three filter bags with the last one at one micron, my two micron racor was blocking after just 60 litres of oil.
                I took about 30 mls of this oil, which looked really good when warm and spun it at 3500 RPM. the radius of spin was about 140mm in a fixed angle rotor- the g force would have been somewhere between 1500 and 2000. The depth of oil in the tube was about 75mm.
                With the oil at 50Co a 30 second spin resulted in a fine brown deposit down the outer side of the tube. A one minute spin resulted in a 3mm diameter spot in the base of the tube. This is the stuff going past my one micron filter and blocking the on board filter.
                From this experiment I guess that the residence time for the oil in a rotor would be somewhere between 30 - 60 seconds for a system that had say around 1500g's. If the rotor holds one litre to a depth of 75mm it should be able to handle a flow rate of around one litre per minute. The variables would be g force and viscosity of the oil that can be controlled by temperature.
                Anyhow, I am going to give it a go. I have purchased a set of plans from Bud over on the Biodiesel and SVO forum and over the next few months a system of some sort should be in operation. I am also scrounging for an old lab centrifuge to experiment with.
                If you are cold filtering liquid vege oil and letting it stand for a couple of weeks and then only pumping from the surface, that is enough to have no problems. I did this for 1000 litres through my 2 micron racor filter on board, with no problems. However if you hot filter and wish to use an oil fat slurry in a heated two tank system it looks like a centrifuge will do the job of polishing the hot SVO fat mix.
                We will see.
                GraemeW

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                • #9
                  Re: WVO and centrifugal forces

                  Sorry for not responding earlier but I was on a lenghty business trip.
                  I investigated a bit before my trip in German forums and there is extensive experience with cream centrifuges around.
                  The question is really what you want to achieve with it.
                  My conclusion is that if you just want to filter dirt particles and water out of the oil and are happy to have the WVO cleaner at ease the cream centrifuge or the washing machine is sufficient.
                  If you want to seperate WVO into SVO and the rest of the lot you definitely have to put more technology and money in.
                  I don't mind having WVO standing around for some weeks to settle so if you have the same mindset don't bother about a centrifuge.

                  How ever the engineer in my says that the WVO and Biodiesel home producer world needs a simple but effective way (and cheap) to seperate what ever oil, fat, ... into its ingredients (of course only what differs in density). I have several ideas of how to achieve this but it will definitely take weeks to move on with this.

                  For the meantime: Thanks to all your replies and please keep me updated with any further information you might come across. Especially a list of common WVO ingredients and their physical properties is most valuable to me as this is the information needed to set the basic design boundaries and parameters.

                  Cheers,
                  Eddi

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