Hi all, Need some advice on my biodiesel quality. After processing used VGO with meth catalyst for apro 4 hrs and leaving settle over night, the sample I take after removing glycerol is very transparent but after putting it through a dry wash it appears to be a little cloudy. Is this due to water being present and if so, how do I remove the water? Thankyou for any support given.
Hi What do you mean by demeth before dry washing? I thought all remaining impurities were removed through the dry wash process? Yes I am using woodchip (Biopure media), a blend of Organic, kiln dried, French hardwood shavings with high cellulose and silicone content, with additional Zeolitic compounds for Methanol and moisture adsorption. This process removes any soaps and trace methanol ensuring that your fuel compares with any professionally made bio diesel, (That's what it says on the tin).
There is excess methanol in the glycerol layer, and in the biodiesel. When the glycerine layer is removed (which isn't 100% glycerine) there is soap, methanol, water and possibly catalyst left in the biodiesel. Evaporating or distilling off the remaining methanol from the crude biodiesel, after the glycerine layer has been removed, should cause more glycerine to fall out (precipitate) and I read that sodium salt (soap) will also settle, precipitate, fall out. I have been using potassium hydroxide catalyst. When more soap and glycerine falls out, settles out, and can be removed before dry washing, then there are less impurities in the crude biodiesel for the drywash to remove. Which probably results in a superior, purer product, when excess methanol is removed prior to dry washing, allowing to settle, decanting or removing the crud, then dry washing. Thanks
I was interrupted while typing my last statement. Generally the biodiesel transesterfication reaction uses about 12-14 per cent of the vegetable oil volume in methanol for a 100% reaction, leaving say 6 to 8 percent by volume of excess methanol. About 1/3 of the excess methanol dissolves in the crude biodiesel product. The methanol also is miscible with water, this water and methanol dissolve soap. If most of the methanol is removed from the crude biodiesel product, I have read that more glycerine, soap and a little water will precipitate, fall out, settle out. This further purifies the biodiesel prior to subjecting it to the dry wash. There are less impurities in the biodiesel to remove, so it may extend the life of your wood chips to remove impurities, or use less wood chips. When soap is absorbed by the wood chips water probably follows the soap, there by removing some of the water as well, assuming the wood chips have been prepared properly. I don't know of a proper dessicant to dry biodiesel, but this type of dry wash may do it to a degree. I make small quantities of biodiesel and remove the excess methanol (demeth) from the transesterification reaction by vacuum distillation. My biggest batch so far has been about 600 millilitres. I think it was Graham Lemming that posted after he demeths his biodiesel and lets it sit in barrels, sodium soap precipitates out to the bottom of the barrel, but I think there's glycerine in it also. Thanks