Method of producing biofuels, and related apparatus

Abstract

Methods of producing biofuels are provided herein, for example and without limitation methods of producing biodiesel from trap grease are provided. Systems and apparatus also are provided for implementing, for example and without limitation, the methods described herein.

1 . A method of producing biofuel from a fatty acid triglyceride-containing material, comprising: 
 (a) heating the material to a temperature greater than about 25° C. to decrease its viscosity;    (b) filtering and dewatering the material at a temperature greater than about 25° C.; and    (c) converting the material to glycerol and biofuel by: 
 i) adjusting the pH of the starting material to about 2.5 and substantially completely mixing the acid into the material to produce a reaction mixture;  
 ii) adding methanol to the reaction mixture to esterify free fatty acids; and  
 iii) adding sodium or potassium methylate or hydroxide to the reaction mixture in an amount effective to bring the pH of the reaction mixture to from about 6.2 to about 8.0, thereby converting fatty acid acyl-glycerides to glycerol and biofuel.  
   
     
     
         2 . The method of  claim 1 , further comprising separating the glycerol and biofuel and washing the methoxylated fatty acids by mixing the methoxylated fatty acids with water and removing the water.  
     
     
         3 . The method of  claim 2 , wherein the water contains phosphoric acid.  
     
     
         4 . The method of  claim 2 , wherein the water is sprayed over the methoyxlated fatty acids.  
     
     
         5 . The method of  claim 2 , wherein the methoxylated fatty acids are aerated during washing.  
     
     
         6 . The method of  claim 5 , wherein the methoxylated fatty acids are aerated using a limewood airstone.  
     
     
         7 . The method of  claim 2 , wherein the methoxylated fatty acids are washed at least two times with water.  
     
     
         8 . The method of  claim 2 , wherein the methoxylated fatty acids are washed three times with water.  
     
     
         9 . The method of  claim 1 , comprising filtering the trap grease at a temperature of from about 25° C. to about 65° C.  
     
     
         10 . The method of  claim 9 , comprising filtering the trap grease at a temperature of from about 50° C. to about 55° C.  
     
     
         11 . The method of  claim 9 , comprising filtering the trap grease at a temperature of about 52° C.  
     
     
         12 . The method of  claim 1 , comprising filtering the trap grease in a screen filter comprising a filter screen, a filtrate collection container, a heater within or integral to the filtrate collection container, a pump fluidly connected to the filtrate collection container and a spray head fluidly attached to the pump and directed onto the filter screen for pumping warmed filtrate onto the screen.  
     
     
         13 . The method of  claim 12 , wherein the screen is a belt.  
     
     
         14 . The method of  claim 12 , wherein the screen is cylindrical, the screen filter further comprising a screw within the cylindrical screen for advancing material through the filter.  
     
     
         15 . The method of  claim 1 , comprising adding potassium methylate to the reaction mixture to convert fatty acid acyl-glycerides to glycerol and biofuel.  
     
     
         16 . The method of  claim 1 , comprising adding sodium methylate to the reaction mixture to convert fatty acid acyl-glycerides to glycerol and biofuel.  
     
     
         17 . The method of  claim 1 , wherein the starting material is trap grease.  
     
     
         18 . The method of  claim 1 , comprising converting the material to glycerol and biofuel at a temperature ranging from about 25° C. to about 65° C.  
     
     
         19 . The method of  claim 18 , comprising converting the material to glycerol and biofuel at a temperature ranging from about 45° C. to about 55° C.  
     
     
         20 . The method of  claim 18 , comprising converting the material to glycerol and biofuel at a temperature of about 52° C.  
     
     
         21 . The method of  claim 1 , wherein the filtering, dewatering and conversion of the material to glycerol and biofuel are performed using processing equipment configured within a commercial shipping container.  
     
     
         22 . The method of  claim 21 , wherein the container is about 40′ by about 8′ by about 8′9″.  
     
     
         23 . The method of  claim 1 , wherein the fatty acid triglyceride-containing material is trap grease.  
     
     
         24 . The method of  claim 1 , wherein during the heating of the material to a temperature greater than about 25° C. to decrease its viscosity, the material is fractionated to separate water and grease.  
     
     
         25 . The method of  claim 24 , wherein the material is fractionated in a conical-bottomed tank.  
     
     
         26 . The method of  claim 1 , wherein the material is passed through one or more self-cleaning screening devices.  
     
     
         27 . The method of  claim 26 , wherein the material is passed through two self-cleaning screening devices.  
     
     
         28 . The method of  claim 27 , wherein one of the self-cleaning screening devices is a disc filter.  
     
     
         29 . The method of  claim 28 , wherein the disc filter is a vibratory disc filter.  
     
     
         30 . The method of  claim 27 , wherein one of the self-cleaning screening devices is a liquid solid separator comprising a cylindrical screen.  
     
     
         31 . The method of  claim 26 , wherein the material is passed through a decanter centrifuge after it is passed through the one or more self-cleaning screening devices.  
     
     
         32 . The method of  claim 26 , wherein the material is passed through, in sequence, a vibratory disc filter, a liquid solid separator comprising a cylindrical screen and having a finer mesh than the disc filter, and a decanter centrifuge.  
     
     
         33 . The method of  claim 1 , further comprising separating the glycerol from the biofuel.  
     
     
         34 . The method of  claim 33 , further comprising fractionating the separated glycerol into a glycerol fraction and a residual fraction comprising one or both of biofuel and fatty acid acyl-glycerides.  
     
     
         35 . The method of  claim 34 , wherein the fractionating is performed by settling.  
     
     
         36 . The method of  claim 35 , wherein the settling is performed in a conical-bottom container.  
     
     
         37 . The method of  claim 34 , wherein the fractionating is performed in a centrifugal decanter.  
     
     
         38 . The method of  claim 1 , further comprising dewatering the washed biofuel.  
     
     
         39 . The method of  claim 1 , wherein the washed biofuel is dewatered in a water-oil separating coalescing filter.  
     
     
         40 . The method of  claim 1 , further comprising filtering the washed biofuel with a filter that excludes fatty acid acyl-glycerides, but passes biofuel.  
     
     
         41 . The method of  claim 40 , wherein the filter that excludes fatty acid acyl-glycerides, but passes biofuel is a PTFE-coated filter membrane.  
     
     
         42 . The method of  claim 41 , wherein the filter is about a 2 μ filter.  
     
     
         43 . The method of  claim 40 , wherein the filter is about a 2 μ filter.  
     
     
         44 . The method of  claim 1 , further comprising filtering the washed biofuel with, in sequence, about a 30 μ filter, about a 10 μ filter, a water-oil separating coalescing filter and a filter that excludes fatty acid acyl-glycerides, but passes biofuel.  
     
     
         45 . The method of  claim 1 , further comprising heating the glycerol under pressure to make propylene glycol.  
     
     
         46 . The method of  claim 45  wherein the glycerol is heated to about 200° C. at about 200 psi to produce propylene glycol.  
     
     
         47 . A biofuels processing system comprising, in sequence and fluidly connected: 
 a pre-filter assembly comprising one or more self-cleaning screening devices;    one or more reaction vessels comprising a heater and a mixing subsystem;    a wash tank; and    one or more of a methanol feed, an acid feed and a methylate feed fluidly connected to the one or more heated reaction vessels and a water feed fluidly connected to the wash tank.    
     
     
         48 . The system of  claim 47 , wherein pre-filter assembly comprises two self-cleaning screening devices.  
     
     
         49 . The system of  claim 48 , wherein one of the self-cleaning screening devices is a disc filter.  
     
     
         50 . The system of  claim 49 , wherein the disc filter is a vibratory disc filter.  
     
     
         51 . The system of  claim 48 , wherein one of the self-cleaning screening devices is a liquid solid separator comprising a cylindrical screen.  
     
     
         52 . The system of  claim 47 , further comprising a decanter centrifuge downstream to the one or more self-cleaning screening devices and upstream to the one or more reaction vessels.  
     
     
         53 . The system of  claim 47 , the pre-filter assembly comprising in sequence, a vibratory disc filter, a liquid solid separator comprising a cylindrical screen and having a finer mesh than the disc filter, and a decanter centrifuge.  
     
     
         54 . The system of  claim 47 , further comprising between the pre-filter assembly and the one or more reaction vessels two or more filter units of differing pore size connected in series, wherein the mesh size of the filter units decreases in a downstream direction.  
     
     
         55 . The system of  claim 54 , wherein the filter units are bag filters.  
     
     
         56 . The system of  claim 54 , comprising from three to five filter units.  
     
     
         57 . The system of  claim 47 , comprising one reaction vessel and a methanol feed, an acid feed and a methylate feed fluidly connected to the reaction vessel.  
     
     
         58 . The system of  claim 47 , comprising a first reaction vessel downstream to the pre-filter assembly and a second reaction vessel downstream to the first reaction vessel.  
     
     
         59 . The system of  claim 58 , in which a methanol feed and an acid feed are fluidly connected to the first reaction vessel and a methylate feed is fluidly connected to the second reaction vessel.  
     
     
         60 . The system of  claim 47 , comprising an acid feed fluidly connected to the one or more reaction vessels and further comprising a pH controller having a probe within the same reaction vessel and a pump or solenoid fluidly connected to the acid feed upstream of the reaction vessel under control of the pH controller.  
     
     
         61 . The system of  claim 47 , in which one or more of the methanol feed, the acid feed, the methylate feed and the water feed are fluidly connected to a spray head within the one or more reaction vessels and located in a portion within the one or more reaction vessels above where liquid collects during operation of the system.  
     
     
         62 . The system of  claim 47 , further comprising a temperature controller having a probe within the one or more reaction vessels.  
     
     
         63 . The system of  claim 47 , housed within a commercial shipping container.  
     
     
         64 . The system of  claim 47 , wherein dimensions of the container are about 40′ by about 8′ by about 8′ to about 9′.  
     
     
         65 . The system of  claim 47 , wherein dimensions of the container are about 20′ by about 8′ by about 8′ to about 9′.  
     
     
         66 . The system of  claim 47 , further comprising a fractionation container downstream to one or more of the reaction vessels to receive glycerol from the one or more reaction vessels.  
     
     
         67 . The system of  claim 66 , wherein the fractionation container is a conical-bottom container.  
     
     
         68 . The system of  claim 47 , further comprising a centrifugal decanter downstream to one or more of the one or more reaction vessels.  
     
     
         69 . The system of  claim 47 , further comprising a dewatering device downstream to the wash tank for dewatering the washed biofuel.  
     
     
         70 . The system of  claim 69 , wherein the dewatering device is a water-oil separating coalescing filter.  
     
     
         71 . The system of  claim 47 , further comprising a filter that excludes fatty acid acyl-glycerides, but passes biofuel downstream to the wash tank.  
     
     
         72 . The system of  claim 71 , wherein the filter that excludes fatty acid acyl-glycerides, but passes biofuel is a PTFE-coated filter membrane.  
     
     
         73 . The system of  claim 72 , wherein the filter is about a 2 μ filter.  
     
     
         74 . The system of  claim 71 , wherein the filter is about a 2 μ filter.  
     
     
         75 . The system of  claim 47 , further comprising downstream to the wash tank: about a 30 μ filter, about a 10 μ filter, a water-oil separating coalescing filter and a filter that excludes fatty acid acyl-glycerides, but passes biofuel.  
     
     
         76 . The system of  claim 47 , the pre-filter assembly containing a triglyceride.  
     
     
         77 . A pre-filter assembly for a biofuels processing station comprising a pre-filter assembly comprising two self-cleaning screening devices fluidly attached.  
     
     
         78 . The pre-filter assembly of  claim 77 , wherein one of the self-cleaning screening devices is a disc filter.  
     
     
         79 . The system of  claim 78 , wherein the disc filter is a vibratory disc filter.  
     
     
         80 . The system of  claim 77 , wherein one of the self-cleaning screening devices is a liquid solid separator comprising a cylindrical screen.  
     
     
         81 . The system of  claim 77 , further comprising a decanter centrifuge downstream to the one or more self-cleaning screening devices and upstream to the one or more reaction vessels.  
     
     
         82 . The system of  claim 77 , the pre-filter assembly comprising in sequence, a vibratory disc filter, a liquid solid separator comprising a cylindrical screen and having a finer mesh than the disc filter, and a decanter centrifuge.  
     
     
         83 . A screen filter apparatus, comprising: a filter screen, a filtrate collection container, a heater within or integral to the filtrate collection container, a pump fluidly connected to the filtrate collection container and a spray head fluidly attached to the pump and directed into the filter screen for pumping warmed filtrate onto the screen.  
     
     
         84 . The screen filter apparatus of  claim 83 , wherein the screen is a belt.  
     
     
         85 . The screen filter apparatus of  claim 83 , wherein the screen is cylindrical, the filter further comprising a screw within the cylindrical screen for advancing material through the filter.  
     
     
         86 . The modified screening filter of  claim 83 , wherein the heater is an electric resistance heater.