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Building a Biodiesel Processor
March 24, 2006
Hosted by:
Paul Feather
and
The Collaborative Biodiesel Project
Outline Biodiesel and Vegetable Oil Basics How Biodiesel is Made Safety Small Scale Processor Design Economics
Basics
What Is Biodiesel? Biodiesel is a diesel fuel made from
vegetable oil, methanol and a catalyst. Biodiesel is the only alternative fuel that
has passed all of the EPA clean air fuel requirements.
Biodiesel is fully compatible with any diesel engine. It has been tested more thoroughly than any other alternative fuel.
Biodiesel is safe to handle and is biodegradable, it is less toxic than table salt.
Best of all, Biodiesel can be made quite easily using recycled waste vegetable oil.
Biodiesel Blends Biodiesel is fully compatible with petroleum
diesel, it can therefore be blended with diesel to: decrease cost increase performance improve cold weather characteristics
The state of Minnesota currently sells all diesel as a blend of B2
Most common biodiesel blend is B20
Cold Weather and Biodiesel Everything is harder
Oil quality is more important Collection is more difficult Settling is more difficult Pumping and filtration is more difficult Fuel gelling is a problem below 32°F Your design must be tolerant of winter conditions
Emissions Reductions of Biodiesel Compared to Diesel
Other Uses for Biodiesel Biodiesel makes a great degreaser Biodiesel as Home Heating Oil
Emmisions are further reduced with open-flame combustion
NOx emmisions eliminated compared to fuel oil
What is SVO?
A Straight Vegetable Oil system requires a secondary, heated fuel tank.
A valve is installed so that Diesel or SVO can be burned.
Any oil can be used, but it must be filtered and water free.
Basics of an SVO SystemTwo-Tank System
Heated vegetable oil tank Usually heated using engine’s heat - via coolant Can be heated with electric elements Inline electric, or coolant fuel heaters, and heated filters are available.
Fuel Switching Valve Allows you to start on Diesel(or Biodiesel) switch to vegetable oil
while driving, then switch back to Diesel(or Biodiesel) for purge/shut-down.
Second Fuel Filter Filters down to at least 10 microns
Systems generally cost $500-1500 (see www.frybrid.com or www.biofuels.ca)
Biodiesel Vs. SVO SVO is (generally) free, but initial system
cost is high Biodiesel is Pour and Go, SVO requires
more user maintenance SVO emmisions are higher in idle and
traffic conditions Biodiesel’s solvency will degrade rubber
fuel lines, SVO will not
How Biodiesel Is Made Chemistry Recipe Titrations
Basic Recipe
1. Collect, process, and heat oil.
2. Measure 1 part methanol to 5 parts oil.
3. Measure lye and mix methoxide.
4. Mix oil and methoxide together for one hour.
5. Settle, and drain glycerin.
Chemistry The chemical structure of oil. Transesterification –
the biodiesel reaction.
CH2OORa catalyst CH2OH| |CHOORb + 3CH3OH 3CH3OORx + CHOH| |CH2OORc CH2OH Oil Methanol Biodiesel Glycerin
Titration When oil is fried too hot too long, the fatty
acids break off, acidifying the oil. Titration is necessary to determine the
acidity of oil. Use a stock solution of known strength, and
phenolphthalein indicator. Creates a 1/1000 scale reaction.
How much lye? Use 4 g NaOH per liter plus titration. Or use 6 g KOH per liter plus titration. KOH is more expensive NaOH doesn’t dissolve as well, and the
glycerin tends to solidify at higher temperatures?
Safety
Safety Potential hazards include, and are not limited to:
Fire Chemical exposure Spills Explosion
Recommended personal protection measures Gloves Goggles Ventilation Acid for neutralization
Additional safety equipment to consider
Fire extinguishers Secondary Containment Sealed vessels Respirators Explosion proof motors Pumps rated for volatile materials Grounding
Processor Design
Processor Design Oil Collection WVO Settling Tanks Heating System Filters Methoxide Mixing
Processor Settling Wash/Dry Settling/Final Storage
Oil Collection Relationship with restaurants DC pump, or portable inverter Hand Dipping Hand pumps Legality issues
Oil quality De-watering
Heat, gravity and time
Filtration Hydrogenated oils Rancid oil Oil quality = fuel quality
Heating You must have a way to heat oil
Ideal reaction temperature is 120°F Ideal settling temperatures are above 80°F Heated space is sufficient for settling, but not
reaction.
The heating system is a vital component of the processor design.
Solar Thermal Heating
Heating Options Electric elements
Relatively cheap (ballpark 2¢/gallon). Easy to control Exports emissions elsewhere
Passive solar (greenhouses, black tanks, etc.) Free. No emissions. Great for pre-heating.
Active solar Can be an expensive installation. Great investment.
Gas, wood, biodiesel, oil, and other fuels. Processor should be indirectly heated. Price varies with
fuel.
Filtration Filter oil
Only practical if oil is hot, or if the filter can slowly drain.
Large surface area. (sock filters, etc.) Provides higher quality glycerine.
Filter biodiesel 10 microns at least. Water separator removes glycerine.
Methoxide Mixing Most dangerous activity in the process. Hand pumps are safe for small scale. KOH dissolves easily.
Spraying methanol over KOH is sufficient. NaOH should be mixed or re-circulated.
Sealed tank.
Processor Designed to mix methoxide and oil.
Optionally designed to separate glycerin. Sealed. Probably heated. Propellers are great, but tricky to install in a
sealed tank. Pump mixing is effective in small scale,
especially when combined with a mixing tube.
Settling Settling is valuable at every stage in the
process. Allows you to drain glycerin, water,
particles, oil, etc. Every tank should drain from the bottom,
and conical tanks are very helpful. Settling will not occur below ~45°F
Washing New fuel contains unreacted or partially
reacted material, glycerin, soaps, water, and methanol.
Settling removes most of this material. For completely clean fuel, you have to
wash it. Mist and/or bubble water through the fuel. Use magnesium silicate. (Magnesol).
Water washing Most impurities would rather dissolve in water than
biodiesel. Water is heavy, and settles out, carrying impurities with it.
Pros Cons
Well tested Time Consuming
Water is cheap Fuel must be dried
Wastewater
Magnesol washing Magnesium Silicate absorbs impurities, and is
then filtered out.
Pros Cons
Fast Some particles are extremely small. (1 micron)
No wastewater Somewhat expensive. Ballpark 6¢/gallon.
Can’t make it yourself.
Drying after a water wash. Heat, time and gravity. Air flow helps with drying. Warm air can
absorb more water than cold air. Well washed fuel dries easily.
Quality Control and Testing Visual inspection for clarity. Specific gravity = 0.86 Emulsion tests Cloud and gel point measurements.
Cloud point should be 25-32°F Gel point should be about 15°F
Water content should be very low. (weigh, boil and weigh again).
Total and free glycerin measurements with spectrophotometry
Gas chromatography
Byproducts Methanol recovery is safe, responsible, and
economical Can be distilled. Methanol boils at 148°F (lower in a
vaccuum) Distillation in the processor is convenient.
Glycerin Contains methanol if you don’t recover it. Good for soap, compost, and many other things.
Wash water Low quality fuel and oil
Glycerin Soap
Terra is boiling the methanol off of some glycerin so that it can be made into soap
Materials Compatibility
Aluminum Stainless Steel Flourinated plastics Teflon, viton, nylon Fiberglass
Zinc Copper, brass, bronze Nitrile rubber Polypropylene Polyvinyl Tygon
Good Bad
Biodiesel Handling and Use Guidelines, NREL, 2004.
Processors
Economics – consumables. Oil is still free. Methanol is the most expensive ingredient
(about $150 for a 55 gallon drum). That represents 55¢ per gallon of biodiesel.
KOH costs around $1/lb, representing 6¢ per gallon of biodiesel. Alternatively, NaOH adds about 3¢ per gallon.
Fuel for heating depends on your situation.
Economics Labor.
Labor times are short, but spread out. Oil collection can be labor intensive, and requires
fuel.
Space. Need an indoor space in winter. Building codes
and restrictions can be a problem.
Economics Capital
Tanks Can be recycled water heaters, fuel oil tanks, etc. Can be off-the-shelf plastic or stainless.
Pumps Can spend $35 to $700 on a pump.
Plumbing Fittings add up quick.
Great Biodiesel Websites
www.biodieselcommunity.org – Great Grassroots, Beginners Website
biodiesel.infopop.cc- THE discussion board for all things Biodiesel
www.biodiesel.org – The Industry Webpage, news, pump locations, etc.
www.biodiesel.appstate.edu – ASU Biodiesel Project, soon to be a bastion of quality info on small scale biodiesel design
www.utahbiodieselsupply.com – Great source for homebrew supplies
www.pumpbiz.com – Great source for high quality pumps
www.me.iastate.edu/biodiesel - Technical info on Biodiesel
www.biofuels.coop – Piedmont Biofuels website, Home to the world-famous ‘Energy Blog’
The Collaborative Biodiesel Project
Contact
Dr. Jeff Ramsdell
Paul Feather
Jeremy Ferrell
