Unconfigured Ad Widget

Collapse

Announcement

Collapse
No announcement yet.

washing with heat

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Re: washing with heat

    Well I am glad to hear that! Well done. For the record I think you won that exchange Tilly.

    From what I understand soap removal is something that everyone tries to acheive with water washing. Are the soaps created due to the presence of water? or are they there by default of the bio reaction?

    i.e. if I remove the methanol with heat, do I need to be concerned about the sneaky soap still hiding - or will this drop out with no methanol present - or is it not there at all because I havent introduced water?

    Comment


    • #17
      Re: washing with heat

      Hi Cade,

      Originally posted by Captaincademan View Post
      Are the soaps created due to the presence of water? or are they there by default of the bio reaction?
      There are two main causes for soap being produced. The first and sometimes most significant cause of soap production in a Base only procedure is when the FFA's are neutralized and turned into soap. This does create water.
      The second cause of soap production is the presence of water, both in the methoxide and the WVO. This will result in a saponifiction side reaction of both the WVO and biodiesel.



      i.e. if I remove the methanol with heat, do I need to be concerned about the sneaky soap still hiding - or will this drop out with no methanol present - or is it not there at all because I havent introduced water?
      I have heard from reliable sources that it is the methanol that holds the soap in suspension in the biodiesel and if you remove the methanol the soap will drop out. I have never performed tests to verify this is in fact what happens
      tillyfromparadise
      Senior Member
      Last edited by tillyfromparadise; 19 October 2017, 04:43 AM.

      Comment


      • #18
        Re: washing with heat

        Thanks Tilly. I think I will boil (65 degree or so) some fresh bio on the stove tonight and see what happens. It will be interesting to see how much the volume decreases. I have boiled the meth out of glycerine in the past attempting to make some useful body soap, so I know there is a crap load of methanol in the glycerine.

        Comment


        • #19
          Re: washing with heat

          I look forward to your test results. It may take some time for the byproduct to drop out after the methanol has gone. I would like to see how much has dropped out in 12 hours, 24 hours and 48 hours if this is feasible to record this. I was thinking that you may be able to draw it up in a syringe at those time intervals so you can measure it accurately. This may not be practical depending on the byproduct viscosity.
          Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

          Current Vehicles in stable:
          '06 Musso Sports 4X4 Manual Crew Cab tray back.
          '04 Rexton 4X4 Automatic SUV
          '2014 Toyota Prius (on ULP) - Wife's car

          Previous Vehicles:
          '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup.
          '80 Mercedes 300D. 2 tank conversion [Sold]
          '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Engine donor for W123 coupe. (body parted out and carcass sold for scrap.)
          '85 Mercedes Benz W123 300CD Turbodiesel
          '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
          '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
          '06 Musso Sports Crew Cab well body. [Head gasket blew!]
          '04 Rexton SUV 2.9L Turbodiesel same as Musso - Our Family car.
          '06 Musso sports Crew Cab Trayback - My hack (no air cond, no heater).

          Searching the Biofuels Forum using Google
          Adding images and/or documents to your posts

          Comment


          • #20
            Re: washing with heat

            Luckily for you I am a Chemist, unlike anyone else on this forum.

            Just heating the brew to remove the MeOH won't work - it will probably form an azeotrope (most alcohols do), but in any case the logistics of the heterogenous nature of the process render it impractical (if you had a thermostated heater, boiling chips, and a fractional distillation column it might work in principal). Bottom line is that you can be well above the BP of pure MeOH and still have residual MeOH in there.

            The biggest issue with the residual MeOH is the glycerol that it retains. Let me tell you, if you put some unclarified bio in your tank and get the gly settling out you're in a world of hurt.

            As far as how you remove it, there are several methods, but I use air. You don't need a compressor, I just use an aquarium bubbler, although it does take time. Important thing is to know when the process is done. Check my method and skip to the end for the QC test I use.

            Comment


            • #21
              Re: washing with heat

              Hi Cade,

              Originally posted by Mark View Post
              Luckily for you I am a Chemist, unlike anyone else on this forum.
              Indeed, we are lucky.
              If it had not been for Mark, it is doubtful that anyone else would have realized that you can not make biodiesel at room temperature using the "standard" production procedure.

              Comment


              • #22
                Re: washing with heat

                Sounds like you have a fair handle on this.

                this one will test you

                from what you are saying I wont be able to get all of the methanol out of solution by heating. That would imply that there will still be remaining methanol once it has stopped 'boiling'.

                So how much methanol by weight (this is much easier to measure) will there be in solution before I start to boil?

                FYI I use a 20% by volume proportion of methanol to oil (i.e. 40L meth in 200L of oil)

                Reason I ask this is to know how much methanol I have removed at the end of the 'boiling' process. I will do a test on 1kg of freshly made bio.

                I will do a test over the weekend, as i need to get this right soon. I dont want to be paying for fuel any longer than I have to!

                Comment


                • #23
                  Re: washing with heat

                  Re: washing with heat

                  'Luckily for you I am a Chemist, unlike anyone else on this forum.'

                  I think you need to pull your head out of your arse.

                  Comment


                  • #24
                    Re: washing with heat

                    Tilly, post No 21, I think you mean 'can' not 'can not' Also in a previous post you said the neutralisation reaction between ffa's and methoxide does not produce water, I don't think you are correct, it does produce water.

                    Cade and Tony, I have tested processed, raw bio many times whilst bubbling for soap. The starting soap level post reaction is very variable depending on quite a few factors but after settling for 12 hours it is nominally 2500ppm. You can bubble/de-meth at ambient temperature (takes longer than if using heat) and you will find the soap level decreases exponentially.

                    A settling time is required after bubbling as some of the glycerol/soap still in suspension will be mixed up by the bubbler. Nominal soap levels (using KOH) after bubbling 24 hours and settling 24 hours is 250ppm. If you don't intend to do any further purification then further bubbling will be reqd to reduce the soap to max spec (66ppm) but most here (UK) will pass the 250ppm level bio through woodchip or similar which should reduce the level to <66ppm.

                    Comment


                    • #25
                      Re: washing with heat

                      Cade, there is a rough way to estimate the methanol left in your bio.

                      Based on a 100 litre batch and adding 20 litres of methanol. The approximate amount of methanol reqd to reach full conversion would be 12.5 litres.
                      The residual methanol of 7.5 litres is split 'roughly' 3 to 1 glycerol to bio, So roughly 1.9 litres in the bio and 5.6 litres in the glycerol.

                      So the answer to your question of how much methanol by weight is left in your 200 litre batch is 3.8 litres x 0.82= 3.1kgs (roughly)
                      smithy
                      Senior Member
                      Last edited by smithy; 19 October 2017, 03:34 AM. Reason: Additional information for Cade.

                      Comment


                      • #26
                        Re: washing with heat

                        Hi smithy,

                        Originally posted by smithy View Post
                        Tilly, post No 21, I think you mean 'can' not 'can not'
                        Exactly the point.
                        You still do not know that biodiesel can not be produced at room temperature. I think Mark needs to come back and explain to you again that you can not make biodiesel ar room temperature.
                        Otherwise you will probably keep making biodiesel at room temperature which we now know is not possible.



                        Also in a previous post you said the neutralisation reaction between ffa's and methoxide does not produce water, I don't think you are correct, it does produce water.
                        You are correct, it does produce water! I wonder why I have thought it did not produce water.

                        "When an alkali catalyst is added to these feedstocks, the FFA react with the catalyst to form soap and water as shown in the reaction below:"

                        R-COOH + KOH R-COOK+ H20"
                        tillyfromparadise
                        Senior Member
                        Last edited by tillyfromparadise; 19 October 2017, 04:13 AM.

                        Comment


                        • #27
                          Re: washing with heat

                          Hi smithy,

                          Originally posted by smithy View Post
                          Cade, there is a rough way to estimate the methanol left in your bio...is split 'roughly' 3 to 1 glycerol to bio...
                          My testing as well as Neutral's showed the split was about 2/3 of the recoverable methanol is in the byproduct layer and 1/3 of the recoverable methanol is in the biodiesel layer.
                          But these are only "rules of thumb" and are variable

                          Comment


                          • #28
                            Re: washing with heat

                            Captain Cademan; Yes heating the crude bio will drive off the excess methanol. I have used vacuum distillation to remove the excess alcohol. Lowering the pressure enough and methanol might become vapor at maybe 20-30 degrees celcius. But imploding the boiling pot if it is large and the pressure is low is a possibility. I made an aparatus that allowed a gas to bubble through a boiling pot in a vacuum still (that's not from a book). By lowering the air pressure over the biodiesel the methanol can boil out at reduced temperature, increasing energy efficiency. You can find on the internet the boiling point of methanol at various atmospheric pressures. There's another formula for figuring boiling point of methanol diluted by a higher boiling miscible solvent (biodiesel) at atmospheric pressure. I probably don't need to give that one.

                            Comment


                            • #29
                              Re: washing with heat

                              Captain cademan; using a google search on the internet using key words Methanol (data page) Wikipedia , I found the boiling point of methanol at 100 milliters of air pressure is about 20-21 degrees centigrade. Pulling vacuum on a still pot of 100 millimeters of pressure while allowing slow release of air at the bottom of the still pot would create a moving gas phase to remove methanol vapor at any temperature above about 21 degrees centigrade. It's a balancing of energy input to optimize biodiesel production with a minimum of energy input. Obviously running the electric vaccuum pump requires energy expense. Just boiling it out would be energy expensive, but it would work. On biodiesel forum Ireland a while back , someone removed methanol from crude biodiesel , then let the crud settle out over weeks or months.

                              Comment


                              • #30
                                Re: washing with heat

                                The boiling-point elevation of a solution relative to that of a pure solvent (methanol) depends on the concentration of dissolved particles (biodiesel present), just as vapor pressure lowering does. The change in boiling point Delta T boiling for a solution is , delta T equals molal (not molar) concentration of solute particles (number of moles of solute per kilogram of solvent) times molal boiling-point elevation constant (which I do not have). In a high boiling liquid (biodiesel) a lower boiling liquid's (methanol) boiling point is elevated based on it's quantity present in the larger liquid volume. It's boiling point elevation, methanol diluted in biodiesel. High heat will force almost all of it out. At reduced pressure with a moving phase of air passing through it that changes the physical dynamics (it's cheating on the boiling point elevation formula using evaporation in addition to boiling out of a dilute methanol/biodiesel solution). That's the formula I skipped earlier in this thread. Slowly bubbling methanol out under vaccuum.
                                WesleyB
                                Donating Member
                                Last edited by WesleyB; 19 October 2017, 10:03 PM.

                                Comment

                                Working...
                                X