Microwave-enhanced process to maximize biodiesel production capacity

Abstract

An improved process for the production of biodiesel fuels and fuel additives from triglyceride-containing feed stocks is described wherein the improvement involves the use of microwave energy to reduce free fatty acid content of feed stocks, enhance the reaction rate and conversion yield of triglycerides to fatty acid esters (biodiesel product), and/or assist in the separation of at least one of the mixtures formed in the biodiesel production process.

1 . In a method for making biodiesel fuel and fuel additive products wherein a triglyceride-containing feed stock is reacted with an alcohol in the presence of a transesterification catalyst to form a first mixture of biodiesel product, alcohol and glycerin, the first mixture subsequently undergoing a first separation for separating the biodiesel product from unreacted alcohol and glycerin, the biodiesel product subsequently undergoing a washing with a washing agent to produce a second mixture of biodiesel product and washing agent, the second mixture subsequently undergoing a second separation for separating the biodiesel product from the washing agent, the improvements comprising: 
 directing radio frequency microwave energy into at least one of: 
 the first mixture prior to the first separation for a time sufficient to reduce an amount of unreacted alcohol and glycerin retained in the biodiesel product and to reduce a time required for separating the biodiesel product from the unreacted alcohol and glycerin; and  
 the second mixture prior to the second separation for a time sufficient to reduce an amount of washing agent retained in the biodiesel product and to reduce a time required for separating the biodiesel product from the washing agent.  
   
   
   
       2 . The method of  claim 1  wherein the triglyceride-containing feed stock includes vegetable oils, animal oils, and used cooking oils.  
   
   
       3 . The method of  claim 1  wherein the radio frequency microwave energy is directed into the first mixture for a time sufficient to increase the temperature of the first mixture from about 5° to about 60° Fahrenheit.  
   
   
       4 . The method of  claim 1  wherein the radio frequency microwave energy is directed into the second mixture for a time sufficient to increase the temperature of the second mixture from about 5° to about 60° Fahrenheit.  
   
   
       5 . The method of  claim 1  wherein the flow rate of at least one of the first mixture and the second mixture is from about 3 to about 120 gallons per minute.  
   
   
       6 . The method of  claim 1  wherein the washing agent is one of a water-based washing agent and an acid-based washing agent.  
   
   
       7 . The method of  claim 1  wherein at least one of the first mixture and the separation thereof and the second mixture and the separation thereof occur in an integrated microwave separation technology unit comprising both microwave application equipment and phase separation equipment.  
   
   
       8 . A method of enhancing a transesterification reaction rate and biodiesel product yield for production of biodiesel fuel and fuel additive products, comprising: 
 reacting a triglyceride-containing feed stock with an alcohol in the presence of a transesterification catalyst to form a mixture of biodiesel product, alcohol, and glycerin;    applying radio frequency microwave energy to the mixture; and    separating the biodiesel product from unreacted alcohol and glycerin;    wherein the application of radio frequency microwave energy is performed prior to the separating of biodiesel product to increase the transesterification reaction rate and to drive a reaction equilibrium toward biodiesel production to thereby increase a yield of the biodiesel product available for recovery from the unreacted alcohol and glycerin.    
   
   
       9 . The method of  claim 8  wherein the triglyceride-containing feed stock includes vegetable oils, animal oils, and used cooking oils.  
   
   
       10 . The method of  claim 8  wherein the radio frequency microwave energy is applied to the mixture for a time sufficient to increase the temperature of the mixture from about 5° to about 60° Fahrenheit.  
   
   
       11 . The method of  claim 8  wherein the applying of radio frequency microwave energy to the mixture and the separating of the biodiesel product are performed in an integrated microwave separation technology unit comprising both microwave application equipment and phase separation equipment.  
   
   
       12 . The method of  claim 8  wherein the flow rate of the mixture is from about 3 to about 120 gallons per minute.  
   
   
       13 . A method of reducing a free fatty acid content of triglyceride-containing feed stocks used for production of biodiesel fuel and fuel additive products, comprising: 
 reacting a triglyceride-containing feed stock having a first free fatty acid content with a reactant to produce a treated mixture;    applying radio frequency microwave energy to the treated mixture to produce a triglyceride-containing feed stock having a second free fatty acid content, the second free fatty acid content being lower than the first free fatty acid content; and    separating the triglyceride-containing feed stock having the second free fatty acid content from a byproduct waste emulsion;    wherein the application of radio frequency microwave energy is performed prior to the separating of triglyceride-containing feed stock for a time sufficient to reduce an amount of free fatty acid retained in the triglyceride-containing feed stock and to increase an amount of triglyceride-containing feed stock having the second free fatty acid content recovered from the byproduct waste emulsion.    
   
   
       14 . The method of  claim 13  wherein the first free fatty acid content is greater than one percent by volume of the triglyceride-containing feed stock.  
   
   
       15 . The method of  claim 13  wherein the triglyceride-containing feed stock having the first free fatty acid content includes vegetable oils, animal oils, and used cooking oils.  
   
   
       16 . The method of  claim 13  wherein the radio frequency microwave energy is applied to the treated mixture for a time sufficient to increase a temperature of the treated mixture from about 5° to about 60° Fahrenheit.  
   
   
       17 . The method of  claim 13  wherein the applying of radio frequency microwave energy to the treated mixture and the separating of the triglyceride-containing feed stock are performed in an integrated microwave separation technology unit comprising both microwave application equipment and phase separation equipment.  
   
   
       18 . The method of  claim 13  wherein the flow rate of the mixture is from about 3 to about 120 gallons per minute.  
   
   
       19 . In a system for making biodiesel fuel and fuel additive products wherein a triglyceride-containing feed stock is reacted with an alcohol in the presence of a transesterification catalyst to form a first mixture of biodiesel product, alcohol and glycerin, the first mixture subsequently undergoing a first separation for separating the biodiesel product from unreacted alcohol and glycerin, the biodiesel product subsequently undergoing a washing with a washing agent to produce a second mixture of biodiesel product and washing agent, the second mixture subsequently undergoing a second separation for separating the biodiesel product from the washing agent, the improvements comprising: 
 a microwave separation technology unit configured to direct radio frequency microwave energy into at least one of: 
 the first mixture prior to the first separation for a time sufficient to reduce an amount of unreacted alcohol and glycerin retained in the biodiesel product, and to reduce a time required for separating the biodiesel product from the unreacted alcohol and glycerin; and  
 the second mixture prior to the second separation for a time sufficient to reduce an amount of washing agent retained in the biodiesel product and to reduce a time required for separating the biodiesel product from the washing agent.  
   
   
   
       20 . The system of  claim 19  wherein the improvements further comprise a microwave separation technology unit configured to increase a transesterification reaction rate of the first mixture and for driving a reaction equilibrium of the first mixture toward biodiesel production to thereby increase a yield of the biodiesel product available for recovery from the unreacted alcohol and glycerin.  
   
   
       21 . The system of  claim 19  wherein the improvements further comprise a microwave separation technology unit configured to reduce an amount of free fatty acid in the triglyceride-containing feed stock and for increasing an amount of triglyceride-containing feed stock having the reduced amount of free fatty acid content recovered.  
   
   
       22 . The system of  claim 19  wherein the microwave separation technology unit configured to direct radio frequency microwave energy into at least one of the first mixture and the second mixture is combined with a phase separation device in a single integrated unit.  
   
   
       23 . The system of  claim 20  wherein the microwave separation technology unit configured to increase a transesterification reaction rate is combined with a phase separation device in a single integrated unit.  
   
   
       24 . The system of  claim 21  wherein the microwave separation technology unit configured to reduce an amount of free fatty acid is combined with a phase separation device in a single integrated unit.