BTC PTEC Biodiesel Workshop

August 7 – 8, 2006

Session 3 – Feed stock and product quality

Agenda for third session

• Feed stock types

• Measurement of feed stock quality

• Biodiesel specifications

• Measurement of product quality

Feedstocks for biodiesel

• Vegetable oil– Soybean– Rapeseed– Palm

• Animal fats (lower cost)– Rendering plants

• Spent oils (lowest cost, so far)– Yellow and grey grease

Comparison of feedstocks

• Vegetable oil– Unrefined (high phospholipid content) un-degummed

oils have separation problems in the process– Refined (better product)

• Animal fats– Lower cost– Higher concentrations of saturated FA– Biodiesel products may have higher freezing points– Higher cetane numbers

Comparison of feedstocks

• Spent oils– Trap grease (odor, moisture and color

problems for this low cost feedstock)– Brown grease (FFA > 15%)– Yellow grease (FFA < 15%)– Cheaper

Vegetable oils

• US– Soybean oil (0.4 T oil/ha, 20% yield from seeds)– Canola and mustard oil (40% yield from seeds)

• Europe– Rapeseed oil (0.5 T/ha, 40% yield from seeds)– Sunflower oil (0.5 T/ha)

• Tropics– Palm oil (4 T/ha)

Feedstock preparation

• Removal of contaminants– Sediment < 2%– Moisture < 0.5 – 1%– Free fatty acids < 2 – 15%– Phosphatide and sulfur <20 ppm

Chemical quality

• Alcohols– Dry– Free of contaminants that may go into ester

phase

• Catalysts– Dry

Fuel quality issues

• Free fatty acids

• Moisture (hard to keep out)

• Contaminants– Unreacted triacyl glycerols, alcohol– Unseparated glycerine– Mono and diglycerides

• Storage properties– Measure acid and viscosity to follow quality

Fuel contaminant problems

• Fuel filter plugging– From mono and di glycerides

• Engine deposits

• Fuel deterioration– Affected by presence of air, heat, metals– Biodiesel will absorb some water upon

storage (1500 ppm)– May pick up material from storage tanks

Fuel standards

• US ASTM D6751– Mostly same as for diesel fuel, except for– Acid number, glycerine– Higher limit on water

• Europe EN14214 (engine), EN14213 (heating)

• Diesel standard is ASTM 975

• State standards for cloud point

ASTM D6751 Biodiesel Standard

Property Test Limits Unit

Flash Point D93 130 min Deg C

Water and sediment D2709 0.050 max % volume

Kinematic viscosity @ 40 deg C D445 1.9 – 6.0 mm2/sec

Sulfated ash D874 0.020 max % mass

Sulfur D5453 0.0015 or 0.05 max % mass

Copper strip corrosion D130 No. 3 max

Cetane number D613 47 min

Cloud point D2500 report Deg C

Carbon residue (100% sample) D4530 0.050 max % mass

Acid number D664 0.80 max mg KOH/g

Free/total glycerine D6584 0.02/0.24 max % mass

Phosphorus D4951 0.001 max % mass

Distil temperature (90% recovered)

D1160 360 max Deg C

Comparison of diesel to biodiesel ASTM limits

Property #2 Diesel Biodiesel Unit

Flash Point 52 130 min Deg C

Water and sediment 0.050 max 0.050 max % volume

Kinematic viscosity @ 40 deg C 1.9 - 4.1 1.9 – 6.0 mm2/sec

Sulfated ash 0.010 max 0.020 max % mass

Sulfur 0.050 max 0.0015 or 0.05 max % mass

Copper strip corrosion No. 3 max No. 3 max

Cetane number 40 min 47 min

Cloud point regional report Deg C

Carbon residue (100% sample) 0.35 max 0.050 max % mass

Acid number N/A 0.80 max mg KOH/g

Free/total glycerine N/A 0.02/0.24 max % mass

Phosphorus N/A 0.001 max % mass

Distil temperature (90% recovered)

338 max 360 max Deg C

Ash < 0.01 % mass

Fuel related properties of diesel and methyl esters

Diesel or Ester

Cetane number

Viscosity

mm2/s 40 deg C

Cloud point

Deg C

Pour point,

Deg C

Flash point, deg C

ASTM limit 47 min 1.9 – 6.0 report 130 min

Rapeseed 48 - 53 4.5 - 5 -3 to -6 -9 166 - 170

Soybean 48 - 56 4 – 4.3 -4 to 3 -7 to 0 130 - 240

Sunflower 54 - 58 4.4 – 4.8 0 – 1.5 -3 to 3 85 - 110

Tallow 62 4.1 - 5 12 - 16 9 - 13 96 - 190

Yellow grease

63 5.2

Grease 6.2 5 -1

Used fry oil 59 4.5 1 -3 >110

No. 1 diesel 48 2.6 -50 -51 56

B20 46 2.9 -14 -15

Analytical tests

• Gas chromatography (GC)– Ester identification and quantification

• Titration– FFA measurement– Iodine test

• Flashpoint (flammabilit) cup method• Water and sediment (centrifuge for volume)

– Low water solubility in biodiesel (15 ppm)• Distillation (upper/lower limits for 90%)

– Too low, may have to high a flashpoint– Too high, tendency of fuel to deposit on cylinder walls

Analytical tests

• Viscosity (falling ball or capillary method)• Ash (muffle furnace method)• Cloud point (temperature at which fuel first starts

to crystallize), regional and seasonal• Carbon residue (pyrolysis test)• Glycerol (Gas Chromatograph)• Acid number (potentiometric titration)• Phosphorus (Inductively Coupled Plasma Atomic

Emission Spectroscopy)• Sulfur by Ultraviolet Fluorescence

Fuel properties

• Cetane number– Measure of ignition quality of fuel (autoignition

property)– Hexadecane (cetane) has a cetane number of

100– Biodiesel minimum of 47 (ASTM D6751)– Uses an engine (expensive)

Analysis and costs

• Full specification analysis – about $1300/sample– $1100/sample for seven consecutive samples

(Magellan Midstream Partners Laboratory Service)

• Several analytical companies are equipped for analysis

• PerkinElmer offers on-line training courses

Fuel properties

• Cold weather properties– Cloud point

• Temperature at which fuel starts to crystallize

– Pour point• Temperature at which fuel cannot be freely poured

– Cold filter plugging point (ASTM D6371)• Lowest filtration temperature

Fuel properties

• Storage properties (oxidation)– Iodine value

• Indication of unsaturation of FA• Indication of tendency to polymerize• European limits of 120 (engine) and 130 (heating)

– Rancimat test– Can improve with additives (same as for

diesel fuel) or modification

National Biodiesel Accreditation Program

• Voluntary program for producers and markets to produce a standard biodiesel called BQ-9000

• Includes ASTM 6751 standard and quality systems standards for the practices of:– Storage– Sampling and testing– Shipping and distribution– Fuels management

• Eight accredited producers in the US• Market a BQ-9000 manual ($125)

Improvement of low temperature properties

• Additives (polymers)

• Winterization (cooling and filtration)– Results in loss of material and reduces CN

• Branched esters– Isopropyl ester has mp 6 - 7 deg below propyl– Higher cost