Process and system for producing biodiesel fuel

Abstract

Disclosed and claimed herein is a system and method for producing biodiesel fuel from low quality feedstock sources of free fatty acids. The system includes a reaction chamber having a jacket for circulating heating fluid around the chamber; a feedstock pre-treatment assembly; a methoxide reaction tank; a settling tank; a crude biodiesel wash assembly; and, a methanol recovery assembly, also referred to as a methanol recoverer herein. The method includes the steps of pre-treating the feedstock by heating and, optionally, filtering it; reacting the feedstock in the reaction chamber with a source of esters thereby carrying out transesterfication of the free fatty acids, thereby producing an intermediate reaction product, cooling the intermediate reaction product to allow glycerine to settle out, separating the glycerine from the crude biodiesel, and washing the crude biodiesel to remove impurities, thereby producing biodiesel fuel.

1 . A method of producing biodiesel fuel from a feedstock source of free fatty acids, said method comprising the steps of:
 (a) pre-treating the feedstock, wherein said the pre-treating comprises heating the feedstock;   (b) in a reaction chamber, carrying out a transesterification reaction between a source of esters and the free fatty acids of the pre-treated feedstock of Step (a) to yield intermediate reaction product, wherein carrying out the transesterification reaction comprises circulating heated heating fluid through a jacket surrounding the outside surface of the reaction chamber, whereby the reaction temperature is maintained at a predetermined temperature;   (c) allowing the intermediate reaction product of Step (b) to cool sufficiently to cause glycerine to settle out, thereby separating the glycerine from crude biodiesel;   (d) removing the separated glycerine from the crude biodiesel; and,   (e) washing the crude biodiesel, whereby the biodiesel fuel is produced.   
   
   
       2 . The method of  claim 1  wherein methoxide is the source of esters. 
   
   
       3 . The method of  claim 2  further comprising:
 (f) recovering methanol from waste fluids produced by at least one of Step (d) and Step (e).   
   
   
       4 . The method of  claim 3  wherein Step (f) comprises the steps of:
 (f1) heating the inner surface of a drum to a temperature above the boiling point of methanol;   (f2) spraying the waste fluid onto the inner surface of a drum heated at Step (f1), thereby producing methanol vapors;   (f3) passing the methanol vapors produced at Step (f2) through a condenser, wherein the temperature of the condenser is maintained at a temperature below the boiling point of methanol, thereby producing a liquid methanol condensate; and,   (f4) collecting the methanol condensate of Step (f3).   
   
   
       5 . The method of  claim 4  wherein Step (f1) is performed with heat produced by an oil burner that burns biodiesel fuel produced at Step (e). 
   
   
       6 . The method of  claim 4  further comprising reducing the air pressure within the drum, thereby lowering the boiling point of methanol. 
   
   
       7 . The method of  claim 1  wherein the feedstock is heated to approximately 43° C. at Step (a). 
   
   
       8 . The method of  claim 1  wherein Step (b) further comprises mixing the source of esters and the free fatty acids in the reaction chamber by rotating at a rotation speed a paddle mounted in the reaction chamber, wherein the rotation speed is from about 60 RPM to about 80 RPM. 
   
   
       9 . The method of  claim 1  wherein at least one of i) heating the feedstock at Step (a) and ii) heating the heating fluid of Step (b) comprises burning biodiesel fuel from Step (e). 
   
   
       10 . The method of  claim 1  wherein Step (a) further comprises at least one of i) filtering the feedstock, and ii) de-watering the feedstock. 
   
   
       11 . The method of  claim 1  wherein the predetermined temperature of Step (b) is below the boiling point of methanol. 
   
   
       12 . The method of  claim 1  wherein Step (e) comprises the steps of:
 (e1) precipitating impurities from the crude biodiesel, and   (e2) separating the biodiesel fuel from the impurities.   
   
   
       13 . The method of  claim 12  wherein Step (e) further comprises forcing compressed gas through the crude biodiesel, whereby the crude biodiesel is mixed. 
   
   
       14 . A system for producing biodiesel fuel from at least one feedstock source of free fatty acids, said system comprising:
 (a) a reactor comprising:
 (a1) a reaction chamber; 
 (a2) reactor heating means for heating reactants in said reaction chamber; and, 
 (a3) mixing means for mixing reactants in said reaction chamber; 
   (b) a feedstock pre-treatment assembly comprising:
 (b1) a pre-treatment tank; and, 
 (b2) a feedstock heating means, wherein said pre-treatpre-treatment tank is in communication with said reaction chamber to allow said reaction chamber to receive pre-treated feedstock from said pre-treatment tank; 
   (c) a methoxide reaction tank in communication with said reaction chamber such that said reaction chamber receives methoxide produced in said methoxide reaction tank;   (d) a settling tank in communication with said reaction chamber, wherein said settling tank receives intermediate reaction product from said reaction chamber;   (e) a wash assembly comprising a wash tank in communication with said settling tank, wherein said wash tank receives crude biodiesel from said settling tank; and,   (f) a methanol recovery assembly.   
   
   
       15 . The system of  claim 14  wherein said reactor heating means comprises a jacket means for circulating heated heater fluid around said reactor chamber; and, a heater for heating the heating fluid. 
   
   
       16 . The system of  claim 15  wherein said heater comprises an oil burner adapted to burn biodiesel fuel produced by the system. 
   
   
       17 . The system of  claim 14  wherein said feedstock heating means comprises:
 (b3) a radiator through which heated heating fluid flows, said radiator being in thermal communication with the feedstock;   (b4) a heater for heating the heating fluid; and,   (b5) a pump for pumping the heated heating fluid through said radiator.   
   
   
       18 . The system of  claim 17  wherein said heater is an oil burner adapted to burn biodiesel fuel produced by the system. 
   
   
       19 . The system of  claim 14  wherein said mixing means of said reactor comprises at least one internal paddle mounted within said reaction chamber; and, rotation means for rotating said paddle. 
   
   
       20 . The system of  claim 14  wherein said mixing means of said reactor comprises at least one baffle. 
   
   
       21 . The system of  claim 14  wherein said methanol recovery assembly comprises:
 (g1) a drum having an interior volume bounded by an interior wall surface;   (g2) a drum heating means for heating said interior wall surface to a temperature equal to or greater than the bolting point of methanol;   (g3) a spray head;   (g4) a pump for forcing methanol containing fluids through said spray head;   (g5) a condenser; and,   (g6) a vapor pump in communication with i) said drum interior volume, and ii) said condenser;   wherein said spray head is adapted to deposit the methanol-containing fluid against said drum interior wall surface, thereby producing methanol vapors in the interior volume of said drum when said interior wall surface is heated to a temperature equal to or above the boiling point of methanol, and wherein said vapor pump is adapted to pump the methanol vapors from the interior volume of said drum to said condenser.   
   
   
       22 . The system of  claim 14  wherein at least one of said reactor heating means and said feedstock heating means comprises an oil burner adapted to burn biodiesel fuel produced by said system. 
   
   
       23 . The system of  claim 14  further comprising a vehicle for carrying said reactor, said pre-treatment assembly, said methoxide reaction tank, said settling tank, said wash assembly, and said methanol recovery assembly. 
   
   
       24 . The system of  claim 23  further comprising a diesel-powered electric generator mounted in or on said vehicle, wherein said generator is adapted to burn biodiesel fuel produced by the system. 
   
   
       25 . The system of  claim 14  wherein said wash assembly further comprises means for injecting compressed air into the crude biodiesel being washed, thereby mixing the crude biodiesel.