Abstract:
Apparatus and method for rapid production of biodiesel fuel. The apparatus includes a packed column followed by a high pressure kinetic reactor. A homogeneous stream of feed oil (vegetable oil or animal fat), methanol, and a catalyst is metered, mixed, fed into a packed column, and finally into the high pressure kinetic reactor where the conversion into biodiesel fuel is completed. The packed column is packed with rings (either Raschig rings or pall rings or equivalent). The homogeneous stream enters from the bottom with rings kept in a fluidized bed state to allow greatest surface area for reaction to take place. Approximately 40 to 70 percent reaction is typically achieved in the packed column. The high pressure kinetic reactor receives the partially reacted homogeneous stream and breaks fluid molecules into nano molecules with very high instantaneous temperatures and availability of large surface areas which allow complete reaction without external heat.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to the production of biodiesel fuel and in particular to rapid production of biodiesel fuel. 
         [0002]    Recent increases in the cost of petroleum have raised both economic and national security concerns. Petroleum costs translate directly into gasoline and diesel fuel costs which impact both personal and commercial expenses. Various alternatives for powering vehicles have been proposed and in various stages of maturity. These alternatives including: natural gas; electricity; hydrogen; and biodiesel. Biodiesel is an alternative fuel for conventional diesel engines and offers advantages including less pollution, but presently is not available in large quantities. 
         [0003]    Biodiesel is produced from ingredients comprising feed oils (vegetable oils or animal fats), a small percentage of alcohol, and a catalyst. The process for producing biodiesel fuel, commonly called transesterification, generally includes a tradeoff between reaction time and temperature, and involves the reaction of triglycerides in the feed oils with the alcohol to produce a mixture of methyl esters and glycerin. The production of biodiesel fuel in the US reached approximately 250 million gallons in 2006 compared to diesel fuel consumption of over 50 billion gallons a year in the US. 
         [0004]    Conventional biodiesel production technology involves introducing the feed oil, methanol, and a catalyst into a two stage reactor vessel and requires up to two hours or more for completion of a chemical reaction converting the ingredients into biodiesel fuel and a glycerine byproduct. Many plants have incorporated multiple reactor systems to do continuous batch processing. High residence time in reactors requires very large reactor vessels, for example, a 20 gpm (10 million gallons/yr) plant will require total reactor vessel capacity of about 3,600 gallons which requires a large foot print. Additionally, high residence time promotes a secondary formation of soaps which are undesired contaminants and must be removed using an expensive wash technology to meet biodiesel fuel specifications. Soaps also trap product biodiesel with resulting yield loss of two to three percent. Soaps in the glycerine byproduct also make the glycerine less desirable because it requires acidulation and results in production of acid oils which have very low market value and often require disposal as a hazardous liquid waste. 
         [0005]    IKA Corporation sells high shear reactors intended to address the time/heat issues of biodiesel fuel production. Reaction inside each high shear reactor is fast, only a few seconds; however, the IKA process requires two stage high shear pumps with intermediate holding tanks to complete the reaction. Holding tanks complete the reaction in about 15-20 minutes, and soap formation is not eliminated. 
         [0006]    Arisdyne Systems and Hydro Dynamics, Inc. make hydrodynamic cavitations based reactors intended to address the time/heat issues of biodiesel production. While these reactors speed up the reaction, each facility requires a complex two stage reactor system to complete the reaction which increases complexity of the system and costs involved. 
         [0007]    Thus, a need remains for rapid low cost fast production of biodiesel fuel. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention addresses the above and other needs by providing a biodiesel fuel production system including a packed bed column followed by a high pressure kinetic reactor to achieve nearly complete production of biodiesel fuel while minimizing undesired by products. High surface area made available through packed bed columns provide 40 to 70 percent reaction completion in a first phase. The remaining reaction is completed in the high pressure kinetic reactor which is preferably a high pressure cavitation chamber. The present invention allows reactions to proceed at 40 degrees centigrade as opposed to 80 to 100 degrees centigrade required by known fast reactors, thus saving energy costs. Near stoichiometric quantities of methanol are sufficient for reaction completion in the present invention compared to 50 to 100 percent excess methanol required in known systems. The present invention allows all of the chemicals to be added ahead of the packed bed column as opposed to spilt chemicals being added in a conventional reactor system into first stage and then second stage. Known systems require a limit of Free Fatty Acid (FFA) content in the incoming feed oil to less than 2.5 percent, and required refined, bleached, degummed oil for feed. The present invention processes degummed crude palm oil with five to eight percent FFA with minimal soaps formation as well as tallow with 2.8% FFA with complete success. In known processes, FFA will react into soaps. The present invention does not produce such soaps. 
         [0009]    In accordance with one aspect of the invention, there is provided a continuous flow through system for rapid production of biodiesel fuel. The continuous flow system includes flow meters and/or pumps, a venturi static mixer, packed bed columns for a first phase, and a high pressure kinetic reactor for completing the rapid production of the biodiesel fuel. Following metering, the ingredients are introduced into the venturi static mixer which allows thorough mixing of the ingredients into one homogeneous stream. The homogeneous stream then enters the packed bed column which is designed for three minutes residence time. The partially reacted ingredients then enter the high pressure kinetic reactor. Fluids exiting the high pressure kinetic reactor are completely reacted into biodiesel fuel and byproduct glycerine. 
         [0010]    In accordance with yet another aspect of the invention, there is provided a packed bed column. The packed bed column is packed with rings (either Raschig rings or pall rings or the equivalent). The homogeneous stream enters from the bottom with rings kept in a fluidized bed state to allow greatest surface area for reaction to take place. Approximately 40-70% reaction is typically achieved in the packed bed column. 
         [0011]    In accordance with yet another aspect of the invention, there is provided a kinetic reactor comprising a high pressure cavitation reactor based on principles of hydro cavitation and high shear whereby the cavitation forces break fluid molecules into nano molecules with very high instantaneous temperatures and availability of large surface areas which allow complete reaction without external heat. The high pressure kinetic reactor is operated at 700-1000 psi pressure and is composed of an adjustable need valve design in which fluid entering the kinetic reactor is forced through opposing orifices at opposite ends of the kinetic reactor creating impinging streams. The resulting collision of the streams causes high shear and cavitation to complete the reaction producing the biodiesel fuel. The opposing orifices are adjustable through the internal needle valve to provide the desired effect. 
         [0012]    In accordance with yet another aspect of the invention, there is provided apparatus which may be embodied in a skid mounted integrated system for convenient installation at a biodiesel fuel production facility. The integrated system may be designed with flexibility to either retrofit into an existing biodiesel fuel production facility which previous used a conventional technology or be installed at a new biodiesel production facility. When feed pumps are already in place at the production facility, metering pumps included in the integrated system are bypassed and each ingredient is metered through control valves included in the integrated system. In a new facility, the ingredients may be metered through pumps included in the integrated system. 
         [0013]    In accordance with yet another aspect of the invention, there is provided a method for producing biodiesel fuel from a mixture of feed oil, alcohol, and catalyst. The catalyst may be potassium methoxide, sodium methoxide, or sodium methylate and catalyst dosing is between 0.4% to 1.2% depending upon the type of catalyst used. The alcohol is preferably methanol and between fourteen and eighteen percent of the incoming feed oil. The method generally includes steps of providing feed oil to a mixer, providing alcohol to the mixer at step  202 , providing catalyst to the mixer, mixing the feed oil, the alcohol, and the catalyst in the mixer to produce a mixture, providing the mixture to a packed column, pumping the mixture through the packed column to react the mixture to produce a partially reacted mixture, providing the partially reacted mixture to a high pressure kinetic reactor, and pumping through the high pressure kinetic reactor to complete the reaction to produce biodiesel fuel. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0014]    The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
           [0015]      FIG. 1  is a high level diagram of a biodiesel fuel processing system according to the present invention. 
           [0016]      FIG. 2  is a flow control valve assembly for the biodiesel fuel processing system. 
           [0017]      FIG. 3  is a metering pump assembly for the biodiesel fuel processing system. 
           [0018]      FIG. 4  is a high pressure kinetic reactor assembly according to the present invention. 
           [0019]      FIG. 5  is a packed column of the biodiesel fuel processing system according to the present invention. 
           [0020]      FIG. 6  is a high pressure cavitation reactor according to the present invention. 
           [0021]      FIG. 7  is a nozzle of the high pressure cavitation reactor according to the present invention. 
           [0022]      FIG. 8  is a cross-sectional view of the nozzle of the high pressure cavitation reactor taken along 8-8 of  FIG. 7 . 
           [0023]      FIG. 9  is a side view of a static mixer of the biodiesel fuel processing system according to the present invention. 
           [0024]      FIG. 10  is a perspective view of a mixing element of the static mixer of the biodiesel fuel processing system according to the present invention. 
           [0025]      FIG. 11  is a method for biodiesel fuel production according to the present invention. 
       
    
    
       [0026]    Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
         [0028]    A high level diagram of a biodiesel fuel processing system  10  according to the present invention is shown in  FIG. 1 . The biodiesel fuel processing system  10  may be pre-assembled on a skid  11  for delivery to a biodiesel fuel production facility. The biodiesel fuel processing system  10  includes two sequential phases for biodiesel fuel production. The first phase is performed in a packed column  40  and the second phase is performed in a high pressure kinetic reactor assembly  44 . Feed oil, alcohol, and a catalyst are combined and reacted to produce the biodiesel fuel. The biodiesel fuel production facility includes a catalyst tank  12 , an alcohol tank  14 , and a feed oil tank  16 . The feed oil, alcohol, and catalyst are provided to the biodiesel fuel processing system  10  through a 1.5 inch diameter line  17   c , a one inch diameter line  17   b , and a ¾ inch diameter line  17   a  respectively, the lines sizes corresponding to flow rates and viscosity of the ingredients. The respective lines sizes are carried on through the biodiesel fuel processing system  10  to a point where the flows are mixed by a mixer  36 . Each ingredient passes through a pump  18   a ,  18   b , and  18   c  in the lines  17   a ,  17   b , and  17   c  respectively, and is controllable through first valves  20   a ,  20   b , and  20   c  respectively, the pumps  18   a - 18   c , and the valves,  20   a - 20   c  reside off the skid. 
         [0029]    The biodiesel fuel processing system  10  is configured for installation at an existing biodiesel fuel production facility or at a newly constructed biodiesel fuel production facility. When the biodiesel fuel processing system  10  is installed in an existing biodiesel fuel production facility include existing pumps, the flows of ingredients are routed through flow control assemblies  24   a - 24   c  (see  FIG. 2 ) to control the amounts of each ingredient. When the biodiesel fuel processing system  10  is installed in a new biodiesel fuel production facility, the flows of ingredients may be routed through metering pump assemblies  34   a - 34   c  (see  FIG. 3 ) to control the amounts of each ingredient. After either of the flow control assemblies  24   a - 24   c  and the metering pump assemblies  34   a - 34   c , metered flows  35   a ,  35   b , and  35   c  are directed to a mixer  36 . The flows of ingredients are controlled to provide between approximately 81 and 85 percent by volume feed oil, between approximately 14 and 18 percent by volume alcohol and between approximately 0.4 and 1.2 percent by volume catalyst. A suitable mixer  36  is a venturi static mixer. The preferred venturi static mixer not only mixes the three fluid streams into a homogenous phase, it also acts as a mini kinetic reactor, providing first phase of transesterification reaction 
         [0030]    The flows through the flow control assemblies  24   a  pass through check valves  31   a ,  31   b , and  31   c  and valves  33   a ,  33   b , and  33   c  respectively to control the flow into the mixer  36 . The flows from the metering pump assemblies  34   a - 34   c  pass through valves  29   a ,  29   b , and  29   c  to control the flow into the mixer  36 . 
         [0031]    After mixing in the mixer  36 , the mixed flow  37  passes through a third valve  38  and into the packed column  40  for a first phase of the reaction of the ingredients to form the biodiesel fuel. About 40 to 70 percent of the reaction generally occurs in the packed column  40 . The partially reacted ingredients  43  flow from the packed column  40  to a high pressure kinetic reactor assembly  44  to complete the reaction of the ingredients into biodiesel fuel  45 . The biodiesel fuel  45  flows into a biodiesel holding tank  46 . The packed column  40  additionally includes a drain line with a valve  35   a , a sight glass  42  and a valve  35   b  sequentially from the packed column  40 , and a vent from the top of the packed column  40  through a valve  41 . 
         [0032]    The flow control assembly  24  for the biodiesel fuel processing system  10  is shown in  FIG. 2 . The flow control assembly  24  is used when the biodiesel fuel processing system  10  is installed in an existing biodiesel fuel production facility. A fourth valve  22  controls the flow into the flow control assembly  24  and a fifth valve  30  controls the flow from the flow control assembly  24 . The flow through the flow control assembly  24  is regulated by a flow control valve  25  with an actuator  26  receiving a feedback signal from a flow controller  28 . Each of the flow control assemblies  24   a ,  24   b , and  24   c  is represented by the flow control assembly  24 . 
         [0033]    The metering pump assembly  34  for the biodiesel fuel processing system  10  is shown in  FIG. 3 . The metering pump assembly  34  includes a valve  56 , a pump  52 , a motor  50  driving the pump  52 , and a pressure gauge  54  for monitoring the pressure of the flow through the metering pump assembly  34 . A valve  58  controls the flow from the metering pump assembly  34 . Each of the metering pump assemblies  34   a ,  34   b , and  34   c  is represented by the metering pump assembly  24 . The metering pumps in the metering pump assembly  34  are initially adjusted in the factory for fixed volume of flow according to the formulation needed for transesterification reaction, however, they can be field adjusted later to a desired formulation. 
         [0034]    The high pressure kinetic reactor assembly  44  of the biodiesel fuel processing system  10  is shown in  FIG. 4 . A first surge tank  60  receives the partially reacted ingredients  43  from the packed column  40 . Alternatively, the surge tank  60   a  may receive flow directly from the mixer  36  through line  37 . The first surge tank  60   a  is designed for five minutes holding time to provide a uniform flow to high pressure pump  80   a . A first level gauge  74   a  monitors the level of liquid in the first surge tank  60   a . The first surge tank  60   a  is vented through valve  64   a  for methane recovery through line  62   a  and includes a drain line  66   a  through a valve  68   a . The partially reacted ingredients are carried from the surge tank  60   a  to high pressure pump  80   a  through valve  76   a  or alternatively the partially reacted ingredients can go to high pressure pump  80   b  through valve  76   b . The high pressure pumps  80   a  and  80   b  are driven by motors  78   a  and  78   b  respectively to provide the partially reacted ingredients to kinetic reactors  82   a  and  82   b  respectively where the reaction of the ingredients to form the biodiesel fuel is completed. Gauges  84   a  and  84   b  monitor the flows of the biodiesel fuel through valves  86   a  and  86   b  respectively to the biodiesel fuel tank  46 . All of the main flows of ingredients to, through, and from the kinetic reactor assembly  44  are preferably through 1½ inch diameter lines. 
         [0035]    A second surge tank  60   b , also designed for five minutes holding time to provide uniform flow to high pressure pump  82   b , is connected to the biodiesel fuel flow from the first reactor  82   a  through a valve  85 . The surge tank  60   b  is further connected to the inlet of the high pressure pump  82   b  through a valve  76   c . Alternatively, the flow from surge tank  69   b  can go directly to high pressure pump  80   a  through valve  76   b . Surge tanks  60   a  and  60   b  are further connected to level gauges  74   a  and  74   b  respectively at high positions on the surge tanks  60   a  and  60   b  through valves  70   a  and  70   b , and at low positions on the surge tanks  60   a  and  60   b  through valves  72   a  and  72   b . The second surge tank  60   b  is vented through valve  64   b  for methane recovery through line  62   b  and includes a drain line  66   b  through a valve  68   b.    
         [0036]    The packed column  40  is shown in detail in  FIG. 5 . The packed column  40  is packed with rings  90  (for example, either Raschig rings or pall rings or equivalent). The homogeneous stream enters from the bottom resulting in the rings  90  being in a fluidized bed state. The fluidized bed state provides the advantage of low pressure drop and no channeling effect (fluid bypasses the rings in channeling) which affords good contact surface for reaction to take place uniformly. The packed column  40  preferably comprises three packed columns in series, each packed column approximately eight inches in diameter and approximately sixty inches high. Approximately 40-70 percent of the reaction of the ingredients is generally achieved in the packed column  40 . 
         [0037]    A high pressure kinetic reactor  82  suitable for use as either the kinetic reactor  82   a  or  82   b  in the high pressure kinetic reactor assembly  44  is shown in  FIG. 6 . The kinetic reactor  82  is based on principles of hydro cavitation whereby the cavitation forces break fluid molecules into nano molecules with very high instantaneous temperatures and availability of large surface areas which allow complete reaction without external heat. The kinetic reactor  82  splits the partially reacted flow from the packed column  40  into two flows and impinges the two flows on each other from opposite directions to complete the reaction of the ingredients producing the biodiesel fuel. The kinetic reactor is based on principles of hydro cavitation and high shearing whereby the cavitation and shearing forces break fluid molecules into nano molecules with very high instantaneous temperatures and availability of large surface areas which allow complete reaction without external heat. A suitable kinetic reactor is a high pressure cavitation chamber. 
         [0038]    The kinetic reactor  82   b  also is thus equipped with impingement technology whereby two streams collide with each other causing additional contact for complete reaction of the ingredients into biodiesel fuel and the byproduct glycerine. The high pressure kinetic reactor is operated at 900-1,000 psi pressure and is composed of adjustable need valve design in  82   a  where fluid entering is reactor is forced out through an orifice which is adjustable through internal needle valve, causing high shear and cavitation and a split orifice design in  82   b  where fluid is first forced through two identical split orifices at each end of the reactor, causing high shear and cavitation and then the two streams impinge on each other from opposite direction to complete the reaction producing the biodiesel fuel. While a high pressure cavitation chamber is described above, biodiesel fuel production systems including other kinetic reactors operating on the principles of hydro cavitation are intended to come within the scope of the present invention. 
         [0039]    A nozzle  84  of the kinetic reactor  82  according to the present invention is shown in  FIG. 7  and a cross-sectional view of the nozzle  84  taken along 8-8 of  FIG. 7  is shown in  FIG. 8 . A flow shaping cone (or needle valve)  85  resides in the nozzle  84  and forms a nozzle cavity  84   a  and a conical flow accelerator (or high pressure orifice)  84   b  between the flow shaping cone  86  and the interior of the nozzle  84 . The nozzle  84  receives a flow of partially reacted ingredients into the nozzle cavity  84   a  and the flow accelerates through the conical flow accelerator  84   b  and is directed against an opposing similarly formed flow to provide the hydro cavitation. 
         [0040]    A side view of a static mixer  36  of the biodiesel fuel processing system is shown in  FIG. 9  and a perspective view of a mixing element  36   a  of the static mixer  36  is shown in  FIG. 10 . The static mixer  36  receives the feed oil flow  98  into a mixer mouth  37  and the alcohol flow  100  and catalyst flow  102  into side ports  39 . 
         [0041]    A method for rapidly producing biodiesel fuel according to the present invention is described in  FIG. 11 . The method includes providing feed oil to a mixer at step  200 , providing alcohol to the mixer at step  202 , providing catalyst to the mixer at step  204 , mixing the feed oil, the alcohol, and the catalyst in the mixer to produce a mixture at step  206 , providing the mixture to a packed column at step  208 , pumping the mixture through the packed column to react the mixture to produce a partially reacted mixture at step  210 , providing the partially reacted mixture to a high pressure kinetic reactor at step  212 , and pumping through the high pressure kinetic reactor to complete the reaction to produce biodiesel fuel at step  214 . The method may further more particularly includes steps described above. 
         [0042]    Various valves which are not described herein in detail are provided for functions related to installation, filling, purging, etc. which will be obvious to those skilled in the art. 
         [0043]    While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.