18-06-2013, 01:16 PM
Biodiesel Production
Biodiesel Production.ppt (Size: 189.5 KB / Downloads: 41)
Types of Biodiesel Production Processes
Definition and standards
Transesterification
Fatty acid chains
Standard recipes
Competing reactions
Process issues
Definition of “Biodiesel”
Biodiesel – a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated
B 100.
Biodiesel must meet the specifications of ASTM D 6751
Triglyceride Sources
Rendered animal fats: beef tallow, lard
Vegetable oils: soybean, canola, palm, etc.
Chicken fat
Rendered greases: yellow grease (multiple sources)
Recovered materials: brown grease, soapstock, etc.
Process Issues
Feedstock requirements
Reaction time
Continuous vs. batch processing
Processing low quality feedstocks
Product quality
Developing process options
Reaction time
Transesterification reaction will proceed at ambient (70°F) temperatures but needs 4-8 hours to reach completion.
Reaction time can be shortened to 2-4 hours at 105°F and 1-2 hours at 140°F.
Higher temperatures will decrease reaction times but require pressure vessels because methanol boils at 148°F (65°C).
High shear mixing and use of cosolvents have been proposed to accelerate reaction.
Batch vs Continuous Flow
Batch is better suited to smaller plants (<1 million gallons/yr).
Batch does not require 24/7 operation.
Batch provides greater flexibility to tune process to feedstock variations.
Continuous allows use of high-volume separation systems (centrifuges) which greatly increase throughput.
Hybrid systems are possible.
Product Quality
Product quality is important – modern diesel engines are very sensitive to fuel.
It is not biodiesel until it meets ASTM D6751.
Critical properties are total glycerol (completeness of reaction) and acid value (fuel deterioration). Reaction must be >98% complete.
Summary
Biodiesel is an alternative fuel for diesel engines that can be made from virtually any oil or fat feedstock.
The technology choice is a function of desired capacity, feedstock type and quality, alcohol recovery, and catalyst recovery.
Maintaining product quality is essential for the growth of the biodiesel industry.