Apparatus and process for the refinement of biodiesel fuel

Abstract

The present invention includes a method and apparatus for the production of biodiesel fuel from simple triglyceride sources, such as vegetable oil. In particular, the present invention incorporates a compact processor including a vapor recovery system for removing excess alcohols from the fuel, and thus promoting ASTM compliance. The vapor recovery system includes means for conserving and storing the excess alcohol for further use in the processing of biodiesel fuel. Additionally, a chemical cleaner in the form of an adsorbent material is introduced into the fuel prior to filtering in order to remove particulate matter and other impurities in the biodiesel fuel.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of fuel production and more specifically to the production of diesel fuel from triglyceride sources in a compact apparatus.

2. History of the Related Art

It is known in the art to use various oils as fuel for combustion engines. Rudolph Diesel recognized that vegetable oils could be used for this purpose, particularly in his eponymous engines. In light of the escalating costs of petroleum-based fuels, there has been a great deal of attention paid to alternative fuels that will meet the needs of the heating and transportation industries. Willie Nelson, the famed country singer, has been a leading proponent of using pure vegetable oil as a diesel fuel, so much so that his tour bus runs entirely on this fuel source.

Unfortunately, the use of pure vegetable oil does have some drawbacks. Most notably, the viscosity of vegetable oil is far too great to be of use in a combustion engine. To lessen the viscosity, the vegetable oil must be heated prior to combustion. This requires preheating the vegetable oil, which can be done through the introduction of a specific fuel heater, or alternatively by configuring a parallel engine that runs on petroleum-based fuel in order to generate the necessary heat to lower the vegetable oil viscosity.

Another type of biodiesel currently in use is based upon a processed vegetable oil that has a reduced viscosity at lower temperatures. The typical method of processing is known as transesterification, which is a known process for creating esters from a triglyceride, such as vegetable oil. The byproducts of the transesterification process are generally the biodiesel fuel, an excess amount of alcohol and some amount of glycerin that is removed from the triglyceride base. Prior to use, the glycerin and excess alcohol must be removed in order to be compliant with ASTM fuel standards, shown below in Table 1.

TABLE 1
Free Glycerin %                  0.020 maximum
Total Glycerin %                 0.240 maximum
Flash Point, degrees C.          130 degrees C., maximum
Water and Sediment, Vol. %       0.050 maximum
Carbon Residue, %                0.050 maximum
Sulfated Ash, mass %             0.020 maximum
Kinematic Viscosity, cSt at 40 degrees C. 1.9-6.0
Total Sulfur, mass %             0.05 maximum
Cetane Number                    47 minimum
Copper Corrosion No.             3 maximum
Acid Number, mg KOH/gram         0.80 maximum
Phosphorus, Mass %               0.001 maximum

Given the complexity of the testing and compliance initiatives that must be undertaken to meet the ASTM and other standards, the preliminary focus of research in the biodiesel fuel area has been directed at distributed consumption. In short, the research focus has been related primarily to vehicle propulsion, and the economies of scale required for mass transportation have further limited the research into this important area. To wit, the existing art is primarily directed towards large-scale processing and refining systems and methods in order to facilitate a centralized processing and distribution system, likely modeled after the petrochemical refinery system that this emerging technology wishes to displace.

A consequence of this industrial modeling is that the equipment and methods utilized during the processing are prohibitively expensive for the average consumer or entrepreneur. Traditional processing methods call for the excess alcohol to be removed in one of two ways: through flash evaporation or water washing. Each of these methods requires expensive hardware as well as additional fuel, heat and other resources for operation. Water washing in particular leaves a producer with a very large volume of wastewater that is irretrievably tainted with excess alcohol. Moreover, once the alcohol is removed in either of these manners, it is generally not reusable in the processing of more biodiesel fuel. As such, the current methods for removing excess alcohol from biodiesel fuel are simply impracticable for the small business and individual consumer.

While such capital-intensive processes may make sense for large operations that are attempting to produce vast quantities of fuel, the aforementioned technology essentially prohibits the distribution of small-scale, local refineries that can be used to generate smaller amounts of fuel for such tasks as home heating, electricity generation and emergency generators. Moreover, the current state of the art requires systems and hardware that belie the intentions of alternative fuel, i.e. mass production and refinement may in time lead to higher prices as the distribution channels become more complicated.

As such, the state of the art is ill suited for combining the distribution and processing systems and methods into a single saleable product that would allow the consumer control over the production and distribution of biodiesel fuel on a smaller, individualized scale. Given the foregoing, what is needed in the art is an improved method and apparatus for the processing of a biodiesel fuel that eliminates the inefficiencies and expense associated with current technology. Moreover, there is a need in the art for a method and apparatus for the processing of biodiesel fuel that maximizes the usable output through the efficient and conscientious use of the raw materials. Lastly, there is a need in the art for a method and apparatus for the processing of biodiesel fuel that can successfully integrate the production and distribution of the end product such that individual consumers, businesses and entrepreneurs can make use of this energy source.

SUMMARY OF THE INVENTION

Accordingly, the present invention includes a method and apparatus for the production of biodiesel fuel on a distributable scale. In particular, the apparatus of the present invention includes a system of vessels that are connected through pumping mechanisms, valve mechanisms and filtration means for heating, mixing and moving the biodiesel fuel during processing. A second of the vessels is sealed and insulated in order to preserve any excess alcohol in a vapor state such that it can be removed through a vapor recovery system. Unlike the prior art, the vapor recovery system of the present invention allows a user to efficiently recover excess alcohol and store it for later use in the processing of biodiesel fuel. As such, the apparatus of the present invention is particularly well suited for use by individual consumers and businesses for supplying fuel for their heating and energy needs.

The present invention also includes a chemical cleaning step that introduces an adsorbent material into the refinement process. Unlike the prior art however, the adsorbent material in the present invention is introduced following the vapor-recovery of the excess alcohol, which improves the performance of the adsorbent material, and thus results in a cleaner, more efficient biodiesel product.

As described in detail below, the present invention incorporates chemical compounds that are known in the prior art into a unique method an apparatus that are specifically adapted for rendering an ASTM compliant product. The combination of the vapor recovery mechanism with the chemical cleaning of the fuel significantly aids in this regard and thus permits biodiesel fuel consumers to become biodiesel fuel producers as well. In sum, the present invention, both in processor and methodology, will allow individual consumers to have access to the means of production of their own energy.

Combined with the increased efficiency resulting from the reuse of the alcohol component of the fuel, the present invention will result in the production of biodiesel at the point of use, as opposed to the current system of centralized refinement and distribution. It is therefore anticipated that users of the present invention will benefit from reduced fueling costs as individual consumers enter the energy production market. These and various other benefits of the present invention are detailed below in discussing the preferred embodiments with reference to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a compact apparatus for the refinement of biodiesel fuel in accordance with the present invention.

FIG. 2 is a flowchart depicting a process for the refinement of biodiesel fuel in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention solves the problems noted above by combining a compact processor design with a novel and efficient method for refining biodiesel fuel. In its preferred embodiments, the present invention is adapted for use in any number of locations; and unlike the systems and methods known in the art, the present invention is particularly well-suited for applications in which the processing and distribution of the biodiesel fuel are integrated.

FIG. 1 is a schematic illustration of a biodiesel fuel processor 10 in accordance with a preferred embodiment of the present invention. The processor 10 includes a first vessel 12 and a second vessel 14 that are coupled through a series of pipes and valves described in detail below. A circulating pump 16 is disposed between the first vessel 12 and the second vessel 14 for creating the flow of materials between the respective vessels. A first valve 18, a second valve 20, and a third valve 22 are disposed at selected intervals for controlling the flow of materials between the first vessel 12 and the second vessel 14. In preferred embodiments, the processor further includes a filter 46 that is serially disposed between the first vessel 12 and the second vessel 14 for filtering the materials at various stages during the processing, including the final stage when the filter 46 directs the biodiesel to a fuel container 48 configured for receiving, storing and dispersing the fuel during use.

The pump 16 is coupled to a first port 23 that transmits materials from the first vessel 12 into circulation. A second port 24 transmits materials from the second vessel 14 into the pump 16. The pump 16 includes an exit port 25 that is further coupled to the first valve 18, which is adapted to control where the circulating materials are directed thereafter.

A hot water heater 26 or other suitable heating means is coupled to a second pump 28 that transmits a heated fluid into the first vessel 12 for heating the materials therein. In preferred embodiments, a heating coil 30 is disposed within the first vessel 12 for radiantly heating the mixture to a specified temperature as discussed in detail below. The heater 26 preferably runs on a closed loop for maximum efficiency and temperature regulation.

The second vessel 14 is connected to a vacuum gauge 40 that is in fluid communication with a vacuum pump 42 and a vacuum tank 44. The second vessel 14 is preferably insulated and vacuum-sealed so as to maintain a constant temperature and pressure therein.

The initial mixture forming the biodiesel is comprised of three components that are known in the art. A triglyceride 32, an alkaline catalyst 34 and an alcohol 36 are all placed in the first vessel 12 and heated to a proscribed temperature as discussed further here. The alcohol 36 is preferably received at least in part from recycled alcohol present in the vacuum tank 44 noted above. In preferred embodiments, the excess alcohol 36 from the processing reactions is removed, stored, and made available for later use according to the methodology described further herein.

Suitable triglycerides 32 are derived from both plant and animal sources, including canola oil, soybean oil, rapeseed oil, palm oil, coconut oil, corn oil, cottonseed oil, mustard oil, used cooking oils, float grease from wastewater treatment plants, beef tallow and pork lard, soapstock, crude oils, and so-called “yellow grease”, which is animal or vegetable fats derived from the preparation of food. In preferred embodiments, the triglyceride is a vegetable oil, such as canola or soybean oil, or yellow grease oil that can be readily procured from local restaurant establishments. Given the level of particulates that are generally present in yellow grease, it is more preferred that the triglyceride 32 be selected from a known vegetable oil. The alkaline catalyst 34 is preferably potassium hydroxide, although sodium hydroxide is a suitable alternative. The alcohol 36 is preferably methanol, but ethanol or propanol may also be used in the present invention.

The processor 10 of the present invention further comprises a source of an adsorbent material 38, preferably housed in a third vessel (not shown) connected to the first vessel 12 for ease of use. A preferred adsorbent material 38 is magnesium silicate, which is commercially available under the brand name Magnesol®, a product of the Dallas Group of America, Inc., Whitehouse, N.J. The chemical properties of Magnesol® are described in detail in U.S. Pat. Nos. 4,681,768 and 5,006,356. The adsorbent material 38 is a chemical cleaner that is preferably introduced into the biodiesel fuel after removal of any excess alcohol content. The adsorbent material 38 removes various impurities that would otherwise render the fuel noncompliant with ASTM and similar foreign fuel standards. Such impurities include soap, colors, odors, excess catalyst, metals, free triglycerides, sulfur, phosphorous and other metals, acids or sediments.

In operation, the processor 10 operates multiple circuits for the heating, cleaning and recycling of the biodiesel fuel and its various byproducts. In a preferred embodiment, the first tank 12 receives predetermined portions of the triglyceride, 32, the alkaline catalyst 34 and the alcohol 36. This initial mixture is heated by the hot water heater 26 to a specified temperature for a specified time period during which the initial reaction is completed. The typical byproducts of this reaction include the biodiesel fuel, a glycerin, some excess alcohol 36, and some amount of impurities described above. The glycerin may be tapped from the first vessel 12 and removed via an exit port 31.

The processor 10 of the present invention is further configured for pre-filtering the triglyceride 32, particularly if it is of the yellow grease variety. In doing so, the triglyceride 32 is released into the first vessel 12 without any other reactants. The pump 16 removes the triglyceride 32 and routes it through the filter 46 by closing the first valve 18, opening the second valve 20 and closing the third valve 22. In this manner, the triglyceride 32 is filtered to remove any particulates larger than 20 microns in diameter. More preferably, the filter 46 is configured for filtering at 5 microns. Upon completion of any initial filtering step, the triglyceride 32 is returned to the first vessel 12 where it is mixed with the other reactants as described above.

Upon completion of the initial reaction, the pump 16 is activated for moving the biodiesel fuel and remaining byproducts to the second vessel 14. As shown in FIG. 1, this can be accomplished by closing the first valve 18 and closing the second valve 20, which will cause the product to enter the second vessel 14. As noted above, the second vessel 14 is preferably vacuum-sealed and insulated, so as to maintain a specified pressure and temperature profile. In particular, the second vessel 14 must be sufficiently well sealed and heated so as to maintain the excess alcohol 36 in a gaseous state. Upon satisfaction of this state, the vacuum pump 42 is engaged for removing the excess alcohol 36 in its vapor form and channeling it to the vacuum tank 44, at which point it can be cooled and condensed into a liquid state for reuse by the processor 10. Preferably, the conduit (not shown) linking the vacuum pump 42 and the vacuum tank 44 is cooled in order to speed the condensation and recovery process. Conventional cooling means, such as a water jacket (not shown) disposed about the conduit can be used for this purpose.

After vapor removal of the excess alcohol 36, the biodiesel fuel and its remaining byproducts are routed from the second vessel 14 back into the first vessel 12 via the pump 16 by opening the first valve 18. When the resultant mixture is in the first vessel 12, the adsorbent material 38 is added for a final cleaning and removal of impurities. During the cleaning reaction, the first vessel 12 is maintained at a specified temperature for a predetermined amount of time, as described further below. Following the chemical cleaning, the biodiesel fuel is removed from the first vessel 12 and directed to the filter 46 through the pump 16 by closing the first valve and opening the second valve 20 and the third valve 22. The filter 46 is preferably adapted for filtering particulates less than 20 microns, and more preferably the filter 46 is adapted for filtering at 5 microns, thus cleansing the biodiesel fuel of any remaining particulates. After filtering, the biodiesel fuel is directed into the fuel container 48 for storage and later use.

The processing methodology of the present invention is discussed with reference to FIG. 2, which is a flow chart depicting a process for the refinement of biodiesel fuel in accordance with the present invention. The method of the present invention is best practiced with the apparatus of the present invention, described with respect to its preferred embodiments above. Moreover, given the unique characteristics, the method of the present invention is preferably, although not necessarily, practiced sequentially according to the flowchart of FIG. 2.

Beginning with step S102, the method of the present invention includes depositing the triglyceride in the first vessel 12. As noted above, the triglyceride is preferably a vegetable oil, such as corn or soybean oil. The size of the first vessel 12 is preferably between 50 and 75 gallons, thereby promoting the wide distribution of the processor 10 itself as opposed to merely distributing the biodiesel refined in the processor, as is currently the norm.

In step S104, the triglyceride is heated to between 115 and 125 degrees Fahrenheit in order to reduce its viscosity. As discussed above, the means for heating can include any conventional means, but most preferably includes a closed-loop water heater that is highly efficient, compact and easy to regulate. Preferably, the triglyceride is heated to approximately 120 degrees Fahrenheit for optimum mixing of the biodiesel reactants.

In step S106, a solution of the alcohol and alkaline catalyst is created. Preferably, the alcohol is methanol and the alkaline catalyst is potassium hydroxide, although the alternative reactants discussed above are also suitable. In a preferred embodiment, between nine and ten gallons of alcohol receive between 1.25 and 1.5 kilograms of potassium hydroxide, which is let to stand until the latter is fully dissolved within the former. Upon dissolution, the alcohol-alkaline catalyst solution is introduced into the first vessel 12 wherein it reacts with the triglyceride, as shown in Step S108. The mixture is circulated through the first vessel 12 for a time period ranging between sixty and ninety minutes, preferably about 75 minutes.

In Step S110, the contents of the first vessel 12 are permitted to settle and separate by phase. This settling phase will take anywhere between eight and twelve hours, at which time a film of glycerin will have formed at the bottom of the first vessel 12. In step S112, the glycerin is removed from the first vessel 12 in a manner described above using the exit port 31. In step S114, the pump 16 is activated and the necessary valve mechanisms are initiated to transfer the remaining contents of the first vessel 12 to the second vessel 14.

The second vessel 14 is preferably insulated and vacuum-sealed in order to maintain the excess alcohol in a gaseous phase. Once within the second vessel 14, step S116 requires the removal of the excess alcohol. A vacuum pressure is applied to the contents therein in order to extract the excess alcohol in its gaseous phase, preferably using the apparatus discussed in detail above. The vacuum pump 42 preferably operates between 0.3 and 0.6 cubic feet per minute, and most preferably the vacuum pump 42 recovers the excess alcohol at approximately 0.45 cubic feet per minute.

In particular, in step S116 it is essential that the second vessel 14 be insulated in order to maintain the mixture at a temperature greater than 100 degrees Fahrenheit so as to insure that the excess alcohol remains a vapor. By vacuum sealing the second vessel 14, the present invention assures a complete and efficient removal of the excess alcohol in such a manner that it is ready for reuse, and thus deviates from the prior art that utilizes flash evaporation and water washing in order to bring the fuel into ASTM compliance. After the excess alcohol is recovered, it is preferably condensed and stored for further use in step S106 of the present invention. That is, once the excess alcohol has been recovered in its vapor form, it can be cooled and reused by the present invention in the refinement of more biodiesel product.

Following the vapor removal of the excess alcohol, step S118 recites that the mixture is transferred back to the first vessel 12 by the pump 16 and the necessary valve mechanisms described above. In step S120, between 3 and 3.5 kilograms of an adsorbent material is introduced to the mixture in order to chemically cleanse the biodiesel prior to use. The chemical cleanse preferably continues for approximately 30 minutes. As noted above, the adsorbent material is preferably magnesium silicate, which is commercially available under the brand Magnesol®. Following the chemical cleaning, the biodiesel product is filtered through the filter 46 as described above in step S122. The filter 46 will preferably be configured for filtering particulate matter greater than 20 microns in diameter, and more preferably the filter will remove all waste product that is greater than 5 micron is diameter. After the filtration step, the biodiesel fuel is ready for storage and use by the user of the present invention.

As described herein, the present invention includes a method of processing a biodiesel fuel and a processor that is configured specifically for the method. In particular, the processor and method of the present invention incorporates the novel use of a vapor recovery system in order to more efficiently and effectively recover any excess alcohol from the initial reaction. Moreover, the present invention readily allows for the excess alcohol to be reused in the processing of additional biodiesel. Moreover, the size and efficiency of the present invention allows for individual users to produce biodiesel in remote locations, as opposed to relying on large-scale refineries and distribution channels for their fuel needs.

In particular, the combination of the vapor recovery system and the chemical cleaning mechanisms allow individual users to process biodiesel that is ASTM compliant, and thus the present invention obviates the need for the current methods of production and distribution. While the present invention is best carried out in a compact format, it is noteworthy that the principles described herein are equally applicable to any size biodiesel processor. In particular, the processor and method of the present invention could alternatively be scaled up ten-fold, such that each of the first and second vessels have a capacity of approximately 500 gallons. It is a feature of the present invention that such an increase in capacity would not dramatically increase the costs of establishment, operation, or maintenance. That is, aside from larger vessels, the marginal costs of increasing the volume and efficiency of the respective pumps and filters is significantly less than it would otherwise be for a traditional biodiesel-processing unit.

Accordingly, although the present invention has been described herein with reference to specific preferred embodiments, including a best mode of practice, it should be understood that design changes, scale modifications and insignificant alterations could be devised by those skilled in the art without departing from the scope and spirit of the present invention as defined by the following claims.

Claims

1. A method for refining a biodiesel fuel comprising:

providing a triglyceride base;

reacting the triglyceride base with a solution including an alcohol and an alkaline catalyst, thereby producing a biodiesel fuel portion and an excess alcohol portion;

recovering the excess alcohol portion;

cleansing the biodiesel fuel portion through contact with an adsorbent material; and

filtering the biodiesel fuel prior to use.

2. The method of claim 1 wherein the triglyceride base is vegetable oil, the alcohol is methanol, and the alkaline catalyst is potassium hydroxide.

3. The method of claim 1 wherein the adsorbent material is magnesium silicate.

4. The method of claim 1 wherein the step of recovering the excess alcohol portion comprises retrieving the excess alcohol through vapor recovery.

5. The method of claim 4 wherein the step of retrieving the excess alcohol through vapor recovery includes providing a vacuum pump for recovering the excess alcohol in a gaseous state.

6. The method of claim 1 wherein the step of reacting the triglyceride base with the solution including the alcohol and the alkaline catalyst includes the step of heating the triglyceride base, the alcohol and the alkaline catalyst to a temperature between 115 and 125 degrees Fahrenheit.

7. The method of claim 1 wherein the step of recovering the excess alcohol portion includes the step of heating the excess alcohol portion to a temperature between 95 and 105 degrees Fahrenheit.

8. The method of claim 1 wherein the step of filtering the biodiesel fuel prior to use includes passing the biodiesel fuel through a filter having a pore size between 5 and 10 microns.

9. The method of claim 1 further comprising the step of filtering the triglyceride base prior to reacting the triglyceride base with the solution including the alcohol and the alkaline catalyst, wherein filtering the triglyceride base includes passing the triglyceride base through a filter having a pore size between 5 and 10 microns.

10. A biodiesel fuel processor comprising:

a first vessel containing heating means for heating a fuel comprising a mixture of a triglyceride, an alcohol and an alkaline catalyst;

a second vessel coupled to the first vessel, the second vessel receiving the fuel after an initial heating phase, the second vessel containing a heated fuel portion and an excess alcohol portion;

a vacuum pump coupled to the second vessel, the vacuum pump adapted for recovering the excess alcohol portion from the second vessel; and

a filter coupled to the second vessel, the filter adapted for receiving and filtering the heated fuel portion from the second vessel.

11. The biodiesel fuel processor of claim 10 further comprising a third vessel coupled to the first vessel, the third vessel containing an adsorbent material for introduction into the first vessel for cleansing the heated fuel portion.

12. The biodiesel fuel processor of claim 11 wherein the adsorbent material is magnesium silicate.

13. The biodiesel fuel processor of claim 10 wherein the triglyceride is vegetable oil.

14. The biodiesel fuel processor of claim 10 wherein the alcohol is methanol.

15. The biodiesel fuel processor of claim 10 wherein the alkaline catalyst is potassium hydroxide.

16. The biodiesel fuel processor of claim 10 wherein vacuum pump is adapted for retrieving the excess alcohol portion in a gaseous state.

17. The biodiesel fuel processor of claim 10 further comprising a vacuum tank for containing the excess alcohol portion, the vacuum tank coupled to the vacuum pump and receiving the excess alcohol portion there from.

18. The biodiesel fuel processor of claim 10 wherein the first vessel has a capacity between 50 and 75 gallons.

19. The biodiesel fuel processor of claim 10 wherein the second vessel has a capacity between 50 and 75 gallons.

20. The biodiesel fuel processor of claim 10 wherein the vacuum pump has a recovery rate between 0.3 and 0.6 cubic feet per minute.