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  • Washing in Reactor Vessel

    Folks,

    What are the problems with washing in a reactor vessel (one of the cone bottom variety)? Does this leave too many deposits on the sides to contaminate the next batch?

    If many folks now do a pre wash, doesn't it mean that it is OK to use water in the reactor and therefore do the full washes in the same tank?

    Thanks

  • #2
    Re: Washing in Reactor Vessel

    I've done it many times. I suppose people set up a seperate wash tank so that they can use a different technique for washing.

    The pre-wash will get rid of most of the soap so that you shouldn't get an emulsion when you do the violent first wash. Big thing to remember though, make sure you flush ALL the glycerin out with a purge before you start the wash (if your processor has all sorts of nooks and crannys that the glycerin can hide in, you will soon know it).

    The wash water drops to the bottom of the tank with the biodiesel over it. When you finish with your last wash, the decanting of the biodiesel will flush out any remaining wash water. Let the processor sit for a bit before the next batch. There will be some water laden biodiesel still on the sides of the processor that will slowly work its way down to the decanting valve. Just before you fill up the processor again, purge that bit of biodiesel out.

    You will still need a seperate container to dry the biodiesel, so that may be another reason that people use a seperate wash tank.
    Terry Syd
    Senior Member
    Last edited by Terry Syd; 15 August 2006, 11:31 AM.

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    • #3
      Re: Washing in Reactor Vessel

      Thanks for the advice,

      What do you regard as your "violent first wash"? Do you then follow up with another long bubble wash or just keep doing direct washes?

      Cheers

      Adam

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      • #4
        Re: Washing in Reactor Vessel

        No bubble wash, I just used a propeller system. With the variable speed of a drill press motor I could adjust the agitation.

        Comment


        • #5
          Re: Washing in Reactor Vessel

          This is a good topic. I'm a bit suspect about washing or prewashing in my processor but I might give it a go if your such an advocate for it.

          Just to clarify a few points though
          • currently you settle in the tank - Is that correct?
          • If not how long do you process for before adding water to stop the process and start the prewash?
          • You say the prewash is good enough to have a violent first wash. Is a bubble wash a violent wash or too violent or not violent enough.
          • How many water changes do you advocate?
          • do you bubble dry? if so for how long.
          • Also, I was talking to a producer in my area and he says that he bubble washes with out any water. I can imagine it would help evaporate the meth out, but cant see much other benefit. He swears that after a two day dry bubble that he gets maybe 20 litres of sludgy compound out of the bottom (from a 500 ltr batch). Might that still be glycerine and soap? i wanted to talk to him about this so I may show him the results of this thread.
          Thanks for taking the time top answer these questions.
          Joe Morgan
          Brisbane Biodiesel Site Admin
          http://www.brisbanebiodiesel.com

          Searching tips using Google - SVO Dual tank systems
          SVO, Common Rail and Direct Injection - Vehicles converted to Used Cooking Oil

          Comment


          • #6
            Re: Washing in Reactor Vessel

            Originally posted by Chev28
            Thanks for the advice,

            What do you regard as your "violent first wash"? Do you then follow up with another long bubble wash or just keep doing direct washes?

            Cheers

            Adam
            Adam,
            I have been doing 2 of 20min spray washes = 2 x 25litres approx
            then a series of up to 5 quite 12 hour Bubble washes depends on soaps.
            Last weekend I tried out my new bubbler on the last wash. I could describe it but you will hopefully see it one day. But bottom line it is attached to an air compressor and she really mixes things up. I recon with careful usage I may cut down at least one bubble wash. Basically it has to be used late in the wash process when I only want to get that very last bit of soap out. The bio and water turns into mayonnaise but within 30mins the 100litres of bio and 25 litres water are separate. That is a violent wash!
            HDJ80 (aka Kiwipete)
            Canberra

            Comment


            • #7
              Re: Washing in Reactor Vessel

              Hi Joe,

              Regarding the bubble drying process without the use of water, it is described here:

              http://biodiesel.infopop.cc/eve/foru...1/m/2811039341

              I have tried one batch like this and it seems to work just fine, even with a 5%pre-wash. You just have to skim off the soap scum off the top and clean out the brown jelly that collects in the bottom of the wash tank. Seems easier than trying to dispose of many litres of soapy wash water.

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              • #8
                Re: Washing in Reactor Vessel

                Excellent topics. Thanks for that.
                Joe Morgan
                Brisbane Biodiesel Site Admin
                http://www.brisbanebiodiesel.com

                Searching tips using Google - SVO Dual tank systems
                SVO, Common Rail and Direct Injection - Vehicles converted to Used Cooking Oil

                Comment


                • #9
                  Re: Washing in Reactor Vessel

                  Joe,

                  On the idea of "violent washing", have a look halfway down the page of

                  http://www.journeytoforever.org/biod...ubblewash.html

                  under the heading Stir Washing.

                  JTF talk about full on mixing with a drill and paint mixer for 5 minutes. No gentle washing here but they insist that it will not work on a partially converted batch. JTF suggest you do a violent wash test of a small batch first to see and if it seperates and if so then you gan go ahead and stir wash the main batch. In other words, if it fails, it was becasue you didn't have complete conversion in the first place and you need to go back to the begining to work out why.

                  Comment


                  • #10
                    Re: Washing in Reactor Vessel

                    Chev28, thanks for mentioning the problem with low conversion biodiesel. If the biodiesel is low conversion you can get the DWS with this method. If you are making low-conversion biodiesel, then just do the 5% pre-wash, then bubble dry/air dry the biodiesel after seperating the glycerin.

                    Comment


                    • #11
                      Re: Washing in Reactor Vessel

                      [QUOTE=geewizztoo]
                      Regarding the bubble drying process without the use of water, it is described here:

                      http://biodiesel.infopop.cc/eve/foru...1/m/2811039341
                      QUOTE]

                      Bloody Hell...geewizztoo
                      This is great... I just love it when people come up with great ideas like that and then freely share them... I think this is why I love these groups/list so much..
                      I am going to be setting my processor up to recover Methanol from my Bio before washing and according to this link washing will be a breeze... and I am lucky that my pump and wash tank is basically setup as discribed in these threads, I only need the filters.
                      http://biodiesel.infopop.cc/eve/foru...1/m/9721044051
                      HDJ80 (aka Kiwipete)
                      Canberra

                      Comment


                      • #12
                        Re: Washing in Reactor Vessel

                        Just to be clear, is this bubbling done after the Glycerine is settled and drawn out? Or is it done immediately after reaction finished?

                        - I read on and it is done after the settling. My problem is then that the mix is quite cool in Canberra and bubbling may not liberate the Methanol as hoped. Also, You would want to vent off the Methanol during the bubbling. Nothing worse than your garage going "FOOMP" in the middle of the night.

                        Terry Syd, when you mentioned washing low conversion BD as just a prewash, followed by air or bubble drying, are you saying not to risk further washing the mix but instead just let is dry and settle? Is this saying, in other words that for a low conversion batch, it is better to just do the prewash and then the bubble dry and then skim off the scum, etc?

                        Thanks

                        Chev28
                        Chev28
                        Senior Member
                        Last edited by Chev28; 16 August 2006, 10:23 AM.

                        Comment


                        • #13
                          Re: Washing in Reactor Vessel

                          You may not even have to skim the top. I like to use a 10% pre-wash as there is a bit more soap removed (pity about the increase in byproduct). After bubble drying the biodiesel until it is clear (as little as possible to minimise oxidation), I find a small amount of water/glycerin in the bottom of the tank that has settled out of the biodiesel, but nothing on top.

                          Yes, if you are making low-conversion fuel, you can get away with the pre-wash. However, if you take the wash process any further with a straight water wash you will get the DWS (dreaded white stuff). That is why so many people that are using low-conversion biodiesel run the fuel unwashed.

                          I also think that most of the methanol goes out with the pre-wash. Methanol has an affinity with water.
                          Terry Syd
                          Senior Member
                          Last edited by Terry Syd; 16 August 2006, 11:55 AM.

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                          • #14
                            Re: Washing in Reactor Vessel

                            Thanks for clearing that up.

                            Don't ever die will you - or at least give us 24 hours notice to get all the questions answered first!

                            Comment


                            • #15
                              Re: Washing in Reactor Vessel

                              Sorry, one more question

                              Originally posted by Terry Syd
                              After bubble drying the biodiesel until it is clear (as little as possible to minimise oxidation), I find a small amount of water/glycerin in the bottom of the tank that has settled out of the biodiesel, but nothing on top.
                              When you are talking about you not needing to skim the top after bubble drying, are you doing this bubble drying after regular washing or before regular washing?

                              Comment

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