Biodiesel Production: Technology

Barry Latham, M.A.Ed.Biodiesel Production & Curriculum

Chemistry & Physics InstructorChicago Heights, Illinois

ASTM 6751-08 (BQ-9000)Flash Point 93°C min.Water/Sediment 0.05% (vol.) max.Sulfur 0.0015% (mass) max.Cloud Point report onlyAcid Number 0.50mg KOH/gFree Glycerin 0.020% (mass) max.Total Glycerin 0.240% (mass) max.Oxidation Stability 3 hours min.Cold Soak Filtration360 seconds max.

Flash Point (ASTM D93-08)Flash Point by Pensky-

Martens Closed Cup Tester

Flash point- tendency of the test specimen to form a flammable mixture with air under controlled laboratory conditions

~$2,000

Water & Sediment (ASTM D2709)

Water and Sediment in Middle Distillate Fuels by Centrifuge

An indication of water and sediment in middle distillate fuels such as Grade Nos. 1-D and 2-D diesel fuel

~$12,000

Sulfur (ASTM D5453-09)Determination of Total

Sulfur in Diesel Engine Fuel by Ultraviolet Fluorescence

Determines sulfur in process feeds, sulfur in finished products and can also be used for purposes of regulatory control.

~$3,000

Cloud Point (ASTM D2500-09)Cloud Point of

Petroleum Products

Cloud Point- temperature at which paraffin wax or other solid substance begins to separate from biodiesel; a cloudy appearance is seen in the oil at this point

~$12,000

Acid Number (ASTM D664)Acid Number of

Petroleum Products by Potentiometric Titration

Biodiesel and blends of biodiesel may contain acidic constituents that are present as additives or as degradation products formed during service, such as oxidation products.

~$900

Free & Total Glycerin (D6584-08)

Determination of Free and Total Glycerin in B-100 Biodiesel Methyl Esters By Gas Chromatography

A high content of free glycerin may cause problems during storage or in the fuel system, due to separation of the glycerin. A high total glycerin content can lead to injector fouling and may also contribute to the formation of deposits at injection nozzles, pistons, and valves.

~$10k-$50k

Oxidation Stability (EN 14112)Oxidation Stability of

Fatty Acid Methyl Esters for Biodiesel

Oxidative degradation is harmful and can deteriorate many physical properties of the biodiesel including viscosity, and acid and peroxide values.

~$8,000

Cold Soak Filtration (D6751-08-A1)

Cold Soak Filtration Analysis

Detects filter plugging tendencies at low temperatures.

~$1,000

Oil Titration (Small Scale)Correlated to Acid ValueUsed to measure the amount of Free Fatty Acids

in used or virgin oil◦ Higher titration is less desired, but still usable◦ More FFA’s mean more catalyst needed means more

expense

Performed to check quality of oil◦ Can be performed at oil collection site◦ Use disposable syringes and small plastic, re-sealable

containers

Indicator Choices◦ Phenolphthalein, Phenol Red, pH Meter, Tumeric spice◦ Looking for color change (near pH 7.0)

Crackle Test (Small Scale)Correlated to Water/Sediment Test

When heated over a hotplate, water will “crackle” in the pan, indicating its presence

Heat a cup of oil to ~100°C

If the oil sputters, then water is present◦ More sputtering = more

water

Water will have to be removed by heating or settling over time and tested again

Centrifuge Test (Small Scale)Correlated to Water/Sediment Test

Oil and water will separate over time

Centrifuging will speed up this process

Fill two appropriate sized test tubes ¾ of the way with your used oil

Spin for 5 minutesThe oil will rise to the top and water

will settle to the bottomThe presence of water indicates

that your oil will need to be treated further◦ Heating◦ Settling

DewateringWater in your used

oil will complicate the formation of biodiesel and must be removed

HeatingSettling

Heating to Dewater (Small Scale)

A band heater on a 55-gallon drum will heat your oil sufficiently◦Shorter time period (hours-

days?)◦Consumes electricity

Use gentle agitation◦Emersion mixer set on low

setting◦Stir once or twice a day

Settling to Dewater (Small Scale)

Allowing a 55-gallon drum filled with used oil will settle your water to the bottom and can be drained off◦Much longer time

period (weeks?)◦Consumes no

electricity

Avoid any agitation

Appleseed Processor (Small Scale)Plumbing w/ Pump

~$550120V Water Heater

~$400Lumber ~$25

No plumbing experience needed

All new parts usedCosts can be reduced by

salvaging/recycling

Reactor Specifics (Small Scale)Water heater preferred over steel drum◦Pre-insulated◦Pre-plumbed◦Pre-wired for heating elements

Electrical water heater has less risk of explosion hazard◦ Internal immersion heaters◦Upper heater disabled; it is rarely submerged

Needs to be connected to 120VAC source◦Electrical box & switch needs to be installed

Do not compromise temperature regulators◦Explosion risk

Quality Testing3/27 Test Correlates to Free Glycerin Test

Tests for triglycerides (unreacted oil)

◦ Does not for monoglycerides and diglycerides

Tells you if you must reprocess

Add 1 part biodiesel to 9 parts methanol in a sealable vial (3mL & 27mL, etc.)

◦ Be very precise with measurements if using these small amounts

Look for particles in the vial and/or cloudiness

◦ If present, your sample failed- reprocess

Sample should be clear to pass

Biodiesel Size Exclusion ChromatographyOnly B100 remains after final glycerin drain

◦ Longer wait-time allows more glycerin to settle outResidual MeOH may remain

◦ Costly/complicated to distill MeOH out of glycerinB100 pumped through molecular sieve into

storage drum◦ 4A sieve traps small molecules (MeOH, H2O) and allows

larger molecules (biodiesel, glycerin) to pass◦ Sized-based trap◦ Based on gas trap designs and drying agents

Because MeOH exists at ppm or ppb levels, sieve may take a very long time to exhaust◦ No current research available◦ Can be recharged by heating in an exhaust hood or

outside To vaporize MeOH and “bake-off” biodiesel adhered to

surface

Biodiesel StorageCorrelates to Oxidation Stability Test

Biodegradable in months to years◦ Less time than table sugar◦ No research to support this

claimOnly make as much as is

neededHydroscopic (attracts

atmospheric water)More glycerin falls out over

time, regardless of draining or filtering

Fire code regulations

Turn-Key OperationsMore and more companies have plans

for plants ready to purchase to produce ASTM certified biodiesel in a range of scales.

Costs are related to plant size◦$1.95M per 5Mgallons/year (Xenerga quote)

Biodiesel SystemsSRS Engineering CorporationXenerga

Biodiesel Systems

SRS Engineering Systems

Xenerga

Custom SECDry-washing System