My current process plant produce biodiesel from crude palm oil (CPO). However, recently we face the problem of free glycerine in biodiesel although many times of washing. Water to biodiesel ratio used is 1:2.5. We have monitored the actual water used and temperature of feed water (50-70degC). Methyl ester GC completeness is >97% with total ME >95%. There is no problem with reaction and washing. Glycerine is settled down to be decanted before start washing. What are the other possibility that free glycerine can't be washed out?
Free glycerine desired specification is below 0.02% whereas the obtained result after washing is 0.06%.
Can you add some information about standard method that used for analysis free glycerol ? Are you use titration method or GC method (ASTM D 6584) ? We can also check the accuracy and precision the method, so after we sure the method is correct, we can finding an accurate technique for washing glycerol more effectively.
We use the GC Method (ASTM D6584) to quantify the free glycerol. How does the accuracy & precision of method will affect the washing glycerol process? Please enlighten regarding this.
Nur Allif Fathurrahman We're using GC method (ASTM D6584) in which we quantify the esters based on boiling point and molecular weight/chromatography.
Do you think there is problem with the reaction, where the free glycerol dispersed in methyl ester and gravitational settling unable to settle down the glycerol?
As for the washing sprinkle, we employ the full cone spray nozzle with greater coverage of surface area. Although the pH of methyl ester has passed after many washes, the free glycerol content still high at 0.06%.
That's a very appropriate method using GC. I mean, just to make sure that the quality control of the product is ok, right ?
So, we can focus on the technique for separate free gly on biodiesel.
Based on my experience, as useful and applicable technique, we use double washing with centrifugal force. We can increase step by step the water that used up to 6%. And we can use weak acid Ca-based to control the pH so, we get final pH at 4-5.
That's all for me, thank you and good luck for your team
Hv a good day !
Water wash is not done to remove glycerol but alkaline catalysts. So, water wash will not help you to remove glycerol. You must optimize the temperature, speed of rotation, reaction time and settling time to get rid off maximum quantity of glycerol. Are you using palm oil or palm distillate
Rachan Karmakar I agree. Water wash unable to reduce much the glycerol. We now use neutralized palm oil, which is crude palm oil with reduced FFA. Current running method is we do evaporate excess MeOH from biodiesel before go to settling and decant out the glycerol.
However, we managed the biodiesel ester completeness 97% and total ME 95% which show the reaction running well? Any other parameter we shall look into?
to separate glycerol is a solvent extraction process, hence those important features as solvent to feed ratio, temperature, mode of (mass transfer) contact and others must be considered. There must be an optimal mode of operation that gives the desired rate of separation
The water washing is conducted to remove homogeneous base catalysts from FAME.It does not remove free glycerol from FAME. However, the free glycerol content in the FAME layer could be further reduced through optimizing the separation time, reaction speed and reaction temperature. In my opinion, the purity of FAME layer maybe enhanced if it is subjected to centrifuge at high speed after separate from crude glycerol
1) Try to use sodium methoxide (NaOCH3) catalyst instead of KOH/NaOH catalysts. This catalyst gives faster and more complete phase separation between glycerol & FMEA phases. We tested this method when we developed bioester products for a company back in 2013.
2) You can optimize separator (glycerol and biodiesel phase separator) performance to achieve desired level of free glycerol contents in your finished biodiesel.
3) You can add 5% crude glycerol during phase separation and see if it could improve you separation efficiency. Note that is option 3 is a trial and error method and do not have any scientific explanation but a company is using to improve their separation efficiency.
Hope, this will help.
Udara, but yes, but plenty of water is needed, but not, if glycerol isbrought to fine emulsion, especially microemulsion
Js Liew Are you talking about the result from process simulation (say Aspen) ? If so, you might want to look at changing the Property methods. We encountered a similar problem with Water washing section when using NRTL method. Using UNIFAC solved the problem and we got complete separation of glycerol from fame mixture.
You should check acidity of CPO and then of that you should change the catalyst
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