US20160060565A1

US20160060565A1 - Process for purifying oils and products produced from the purified oils

Info

Publication number: US20160060565A1
Application number: US14/834,286
Authority: US
Inventors: Joseph M. Perez; Cameron C. Calhoun
Original assignee: Eco-Collection Systems LLC
Current assignee: Eco-Collection Systems LLC
Priority date: 2014-08-29
Filing date: 2015-08-24
Publication date: 2016-03-03

Abstract

Processes for purifying used cooking oil, and for isolating fractions from the used cooking oil that can be used in biodiesel and lubricant compositions, are described. Winterization of used cooking oil allows separation of particulate impurities, and the resulting oil can be further winterized to allow the oil to separate into fractions which include relatively higher and relatively lower FFA concentrations than the starting oil. Fractions can then be isolated, and those fractions with sufficiently low FFA concentrations can be used in biodiesel applications, and fractions with relatively higher FFA concentrations can be used in certain lubricant formulations, including chain saw lubricants and mould release oil compositions.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The benefit of priority under 35 USC §119 of U.S. Provisional Patent Application No. 62/044,036 filed Aug. 29, 2014 in the names of Joseph M. Perez and Cameron C. Calhoun for “PROCESS FOR PURIFYING OILS AND PRODUCTS PRODUCED FROM THE PURIFIED OILS” is hereby claimed. The disclosure of such U.S. Provisional Patent Application No. 62/044,036 is hereby incorporated herein by reference, in its entirety, for all purposes.

FIELD

The present disclosure relates to process for separating used cooking oil into different fractions, including a fraction with a relatively lower free fatty acid concentration than the starting oil, and a fraction with a relatively higher free fatty acid concentration than the starting oil. The present disclosure also relates to processes for producing biodiesel fuels from the fraction with a relatively lower free fatty acid concentration than the starting oil, and producing lubricants from the fraction with a relatively higher free fatty acid concentration than the starting oil.

BACKGROUND

Although fatty acids are typically present in low concentrations in virgin cooking oils, as they are used, the concentration of fatty acids increases, and once used cooking oils reach certain high fatty acid concentrations, they are no longer suitable for use in cooking applications.
There is a large market for used cooking oils in the biodiesel fuel and lubricant fields, because they are available at a much lower price than virgin cooking oils. However, there are also impurities in used cooking oils that may make them difficult to use as feedstocks to prepare biodiesel fuel or lubricants. These impurities include fatty acids, solids, and, occasionally, waxes. For some products, the presence of fatty acids and waxes may be advantageous. However, for biodiesel production, the presence of fatty acids is problematic, because biodiesel is produced via transesterification, a base-catalyzed reaction. Fatty acids react with the basic transesterification catalysts to form fatty acid carboxylate salts. These salts function as emulsifiers, making it difficult to separate the biodiesel from the crude glycerol by-product that is produced.
Phase separation also constitutes a major problem with used cooking oils when they are used in lubricant products. In most lubricant applications, including hydraulic fluids, chainsaw lubricants, mould release fluids and cutting oils, phase separation is considered as a major issue. Typically, these products include functional additives in addition to an oil base. If the functional additives were to precipitate out of the oil, the remaining fluid would not perform properly. However, with used cooking oils, precipitates can form, and while these precipitates may not include the functional additives, a customer might believe that such is the case. Therefore, in order to effectively use re-processed waste oil in lubricants, it would be desirable for manufacturing procedures to minimize sediment formation.
It would therefore be advantageous to have an efficient method to remove impurities from used cooking oil, and to recover products which include the oil from which the impurities are removed. The present disclosure provides such methods and products.

SUMMARY

Processes for treating used cooking oil to remove various impurities, and to provide various isolated fractions with different impurity profiles, are disclosed. Processes for using isolated fractions from the treated used cooking oil to produce biodiesel fuel, and to produce lubricants, are also disclosed.
Used cooking oil includes a variety of impurities. These predominantly include solids, including materials from the foods cooked in the oils, and fatty acids. Depending on the source of the oil, waxes can be present, though they may have already been removed from the cooking oil before it was used, for example, in a winterizing step. The processes described herein remove the solids, and can provide fractions in which the fatty acid content is relatively lower than in the starting material (used cooking oil), and fractions in which the fatty acid content is relatively higher than the starting material.
In one embodiment, the process starts in a restaurant, with the oil being heated in a fryer to 300 to 400° F. Typically, the oil is collected, and water is removed through a heating and settling process where the oil is heated to above 120° C., and remains in the tank for 36 hours or longer. In another embodiment, the process starts with used cooking oil that has already been subjected to these steps, or which is not treated to remove water.
The oil is then subjected to a chilling (i.e., winterization) process. When virgin oil is subjected to winterizing, the majority of fats/waxes that are present tend to crystallize out, and a filtering step removes the crystallized fats/waxes. Accordingly, if the cooking oil that is recovered had previously been winterized, the winterizing that occurs in this step will not remove fats/waxes, as such would already have been removed before the oil was used for cooking. However, fats or waxes can be present in the oil as a result of the food that was cooked in the oil, and can be removed in this winterizing step.
The winterizing step involves refrigerating the recovered cooking oil for a given period of time, then allowing it to warm to a temperature above the freezing point of the oil, typically around room temperature, then allowing the oil to separate into a series of fractions. The fractions typically include an upper layer of “sheen,” a bulk liquid layer, a cloudy phase, a slurry phase, and a bottom layer including pasty residues.
The pasty residues tend to have much higher water contents than the other layers. While not wishing to be bound to a particular theory, it is believed that water micelles occur in the oil, especially when high free fatty acids are present. These colloidal structures form and, being heavier than oil, settle to the bottom. Along with crystal formation, this is an important mechanism for the formation of oil precipitates.
In order to remove these molecules, the process initially involves cooling or refrigerating the oil, forcing their crystallization. Then, the cold oil is allowed to thaw, which leads to migration of more fluid molecules to the top of the oil and sedimentation of solid molecules on the bottom. The solid molecules can then be removed, for example, by filtering them out of the oil, or by decanting the oil from the solid bottom fraction.
While not wishing to be bound to a particular theory, it is believed that it is better to filter the oil only after it has been cooled, because if it is filtered before it is cooled, crystal seeds can be removed, which can lengthen the time for filtered samples to form precipitates.
Once the pasty residues have been collected, they can be used, for example, as a diluent (or a plasticizer) for roofing tars and asphalts.
The remaining oil can be sent to a winterization tank or a processing tank, where it is allowed to separate on cooling into (at least) two fractions. Generally, one of the fractions includes a relatively higher fatty acid content than another of the fractions. The relatively high fatty acid content fraction(s) can be used, for example, to produce lubricant formulations. When used for at least certain lubricant formulations, the presence of fatty acids is not detrimental.
The fraction(s) with relatively low fatty acid content can, ideally, be used for biodiesel production. However, where the fatty acid content is over 3 percent by weight, the fatty acid content is still too high for use in conventional biodiesel production. The fraction(s) can be subjected to another winterization step, which re-fractionates the oil and provides a further fraction with lower fatty acid content, or the fatty acid concentration can be reduced in one or more fractions, for example, by extracting the fraction(s) with a basic solution to lower the fatty acid concentration, or by filtration through a clay, where the clay intercalates fatty acid salts.
The apparatus used to process the used cooking oil may in various embodiments include a processing tank, a holding tank, and one or more winterization tanks. The oil is stored at a temperature between about 115° C. and 140° C. for a period of time between 48 and 72 hours in a processing tank. The processing tank can include a drain at the bottom, enabling the pasty residues to drain out once the residues separate from the remainder of the oil. Further winterization steps can be performed in one, two, or more winterization tanks. The tanks are ideally set up away from heat sources or sunlight. In one embodiment, at least one of the tanks includes a cold water jacket. In one embodiment, intake piping is used to pump the oil from the top reservoir levels, and in this embodiment, at least the winterization tanks are equipped with such an intake system, although its installation in other tanks can benefit the product quality as well.
It can be beneficial to equip tanks that include such intake systems with a means for skimming the oil surface. Those of skill in the art can readily ascertain how frequently the surface should be skimmed.
In practice, a water cooling jacket is typically capable of reducing the oil temperature to 10° C. Oil cooled to this temperature can be winterized in between about 2 and 4 weeks, depending on the ambient temperatures. However, considerable amounts (˜20% by volume of the starting oil) of clear oil can typically be sampled from the top of the winterization tanks as early as in a week after winterization has been initiated.
Without any cooling, the winterization can take anywhere from one month to several (e.g., 3-5) months, particularly if the winterization occurs during the summer, though it occurs faster during the winter. The cooling cycle in the beginning, followed by the gradual thawing (warming up) and sedimentation, appears to be much more effective in winterizing the oil than merely holding it at ambient temperature.
In one embodiment, the heavy residue from the re-processed oil is used as a diluent (or a plasticizer) for roofing tars and asphalts. This embodiment provides a use for this product fraction, rather than merely sending it off for disposal.
Using the winterization process described herein, one can provide re-processed oils with a relatively higher quality than the starting oils, and also provide for the use of such oils, or fractions thereof, to produce “value added” products such as biodiesel, lubricants, and hydraulic fluids.
In one aspect, the disclosure relates to a method of processing used cooking oil to recover material therefrom, wherein the used cooking oil has a first fatty acid concentration, said method comprising:
a) cooling the used cooking oil to temperature between about −6° C. and about 10° C., and maintaining it at such temperature for a period of time between about 3 hours and about four weeks,

- b) warming the used cooking oil to temperature between about 115° C. and 140° C.,
- c) sedimenting solid impurities from the used cooking oil,
- d) separating the oil from the sedimented solid impurities,
- e) subjecting the separated oil to a winterization, and
- f) isolating from the winterized oil a fraction with a second fatty acid concentration, which is higher than the first fatty acid concentration, and a fraction with a third fatty acid concentration, which is lower than the first fatty acid concentration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing depicting the fractions present in a winterized sample of used cooking oil.

FIG. 2 is a graphic illustration of a chemical plant that receives a waste oil supply, and passes it through a processing tank, a holding tank, and a winterization tank, to produce a fraction including solid materials that can be used as a diluent for roofing, an oil fraction that can be used as a feedstock for biodiesel production, and an oil fraction that can be used as a feedstock for lubricant production.

FIG. 3 is a graphic illustration of a chemical plant that receives a waste oil supply, and passes it through a processing tank, a holding tank, and two winterization tanks, to produce the same fractions as shown in FIG. 2.

FIG. 4 is a chart showing the relative percentages (vol. % vs. days) by volume of a liquid phase and a paste phase for two different oil samples stored under various storage conditions over various periods of time. Diamonds represent cold storage of a sample labeled 7EC. Squares represent room temperature storage of a sample labeled 7EC. Triangles represent cold storage of a sample labeled 8EC. Circular dots represent room temperature storage of a sample labeled 8EC.

FIG. 5 shows a schematic illustration of a chemical plant for converting the oil fraction including relatively high fatty acid contents into a lubricant composition, by mixing in various additives.

FIG. 6 is a chart showing the viscosity of a lubricant formulation (cSt at 40° C.) as a function of the weight percent of a particular additive, V-570.

FIG. 7 is a chart showing how used cooking oil proceeds from being winterized and separated into a base oil for lubricant manufacture and an oil for biodiesel production, how the base oil is combined with additives to produce a lubricant formulation, and how that formulation can optionally be subjected to quality assurance and possible re-working.

FIG. 8 is a chart showing the pour point (degrees C.) of various formulations (10%, 15%, and 20% POL V570) including various percentages of pour point depressant (PPD) 551.

DETAILED DESCRIPTION

The methods described herein can be used to isolate various products, or feedstocks useful to produce various products, from waste cooking oil (also referred to herein as “re-processed oil” or “used cooking oil”). In one embodiment, the methods can be used on-site where waste cooking oils are produced, to manufacture value-added lubricant and other products.
The methods described herein involve sedimentation, one or more winterization steps, and separation. These process steps are discussed in more detail below.
As used herein, the term “relatively low free fatty acid (“FFA”) content” refers to FFA content between 0.1 and 3% by weight. The term “relatively high free fatty acid (“FFA”) content” refers to FFA content greater than about 3% by weight. However, the term “relatively” is also used herein to relate the FFA content of one or more fractions to the FFA content of the starting oil, and/or to relate the FFA content of one or more fractions to each other.
The methods described herein allow one to separate waste cooking oil, which often has a relatively high initial FFA content, into fractions that include relatively higher FFA content and relatively lower FFA content than the initial oil.
In some embodiments, where a sample of waste cooking oil has an FFA content greater than 3%, and is subjected to the methods described herein, the sample is separated into different fractions, some of which have a low enough FFA content (i.e., less than 3% by weight, preferably less than about 1% by weight) to be used as a feedstock to produce biodiesel fuel.
In some embodiments, where a sample of waste cooking oil has an FFA content greater than 3%, and is subjected to the methods described herein, the sample is separated into different fractions, some of which have a relatively lower FFA content, and some of which have a relatively higher FFA content. The specification for free fatty acids in certain products is higher than in other products, so by providing different fractions with different FFA contents, waste cooking oil with an FFA content too high for use as feedstock for certain products can be separated into different fractions, one or more of which may have a low enough FFA content for use in different applications than the starting waste cooking oil.
Examples of products that tolerate relatively high FFA contents include chainsaw lubricants and mold release oils. Examples of products that may require relatively lower FFA contents include cutting oils and hydraulic fluids. A fraction otherwise suitable for biodiesel production can also be used to prepare lubricants, particularly those which require relatively low FFA content.
In some embodiments, it is desirable to further reduce the concentration of free fatty acids (i.e., Total Acid Number) in addition to what can be accomplished through winterization. This can be accomplished, for example, by neutralization and extraction, or by filtration through clay.
In one illustrative aspect, the disclosure relates to a method of processing used cooking oil to recover material therefrom, wherein the used cooking oil has a first fatty acid concentration, said method comprising:
a) cooling the used cooking oil to temperature between about −6° C. and about 10° C., and maintaining it at such temperature for a period of time between about 3 hours and about four weeks,
b) warming the used cooking oil to temperature between about 115° C. and 140° C.,
c) sedimenting solid impurities from the used cooking oil,
d) separating the oil from the sedimented solid impurities,
e) subjecting the separated oil to a winterization, and
f) isolating from the winterized oil a fraction with a second fatty acid concentration, which is higher than the first fatty acid concentration, and a fraction with a third fatty acid concentration, which is lower than the first fatty acid concentration.
In various embodiments of such method, the separated oil may be subjected to more than one winterization.
In other embodiments, the solid impurities are used as a diluent or a plasticizer for roofing tars or asphalts.
In still other embodiments, the used cooking oil comprises water, and the method further comprises removing water from the used cooking oil prior to the cooling a). For example, the water may be removed using a heating and settling process, comprising heating the oil to temperature above 120° C., and maintaining the oil at such temperature for a period of time of 36 hours or longer.
In various embodiments of the above-described method, the winterization comprises cooling the oil to temperature of about 10° C., and maintaining it at such temperature for a period of time between about two and four weeks.
In other embodiments, one or more of the oil fractions may include a higher free fatty acid concentration than a predetermined amount for a given application, further comprising removing fatty acids therefrom. The fatty acids may be removed in any suitable manner, e.g., via neutralization and extraction, or via filtration through clay.
The disclosure relates in another aspect to a lube base stock prepared by the method broadly described above.
In a further aspect, the disclosure relates to a chain saw lubricant comprising a lube base stock prepared by the method broadly described above. Such chainsaw lubricant may further comprise one or more additives selected from the group consisting of tackifiers, pour point depressants, anti-wear additives, rust inhibitors, and antioxidants. Such chainsaw lubricant may further comprise a pour point depressant at concentration of about 1.5% by weight, an anti-wear additive at concentration of between 0.1 and 1% by weight, an antiwear additive at a concentration of between 0.1 and 1% by weight, a rust protector between 0.1 and 1% by weight, and an antioxidant at concentration between 0.1 and 1% by weight, wherein all weight percentages are based on total weight of the chain saw lubricant.
The disclosure relates in a further aspect to a mold release fluid comprising a lube base oil prepared according to the method broadly described hereinabove. In various embodiments, the mold release fluid may comprise a lube base oil, an organic solvent, a tackifier, between 0.1 and 1% by weight of a rust inhibitor, between 0.1 and 1% by weight of an antioxidant, and optionally between 0.1 and 3% by weight of a demulsifier and/or between 0.1 and 1% by weight of an odorant, wherein all weight percentages are based on total weight of the mold release fluid.
The processes for treating used cooking oil to remove various impurities, to provide various isolated fractions with different impurity profiles, and to use these isolated fractions to form downstream products, are disclosed in more detail below.

I. Sources of Vegetable Oil/Animal Fat

Many restaurants use one or more vegetable oils to fry foods. These oils include palm oil, soybean oil, corn oil, cottonseed oil, and canola oil. These oils are typically subjected to winterizing steps, and, optionally deodorizing and other steps, before being used to cook food. Accordingly, recovered cooking oils may contain relatively low amounts of impurities, such as fats and waxes, which are found in virgin oils of these types. Since chicken is often cooked in the oil, chicken fat is frequently found in the used cooking oil.
Particulates from pieces of food, including bone, breading, and the like, are also found in used cooking oil. Filtration can typically remove the bulk of the particles, but may not be effective at removing all of the particles.
Water is also typically present in cooking oil, as a result of cooking food that includes relatively high water content in the oil. For example, potatoes and chicken both include large amounts of water, and although much of this water leaves the oil in the form of steam, residual amounts of water can remain. While most biodiesel production processes can tolerate up to 1% water in the feedstock, even this small quantity of water will increase soap formation and measurably affect the transesterification process.
This water can be largely removed by heating the oil, as described herein. However, a certain amount of water can remain in the form of micelles, which include water, fatty acids, and vegetable oil.
The free fatty acid content of used cooking oil is typically in the range of between about 5% and 30% by weight. The fatty acid content of trap grease is typically in the range of between about 40% and 100% by weight, which is typically too high for it to be subjected to the processes described herein. The preferred range of fatty acid content for used cooking oils used in the processes described herein is between 4 and 10% by weight.

II. Initial Winterization Step

After the oil has been obtained, and excess water has been removed, the oil can be cooled and the solid impurities allowed to crystallize. Then, the oil is allowed to warm, and the various phases are separated. The phases include at least a paste residue bottom layer and slurry phase, a cloudy layer, and a bulk oil layer, as shown in FIG. 1.
In one embodiment, the initial winterization step is conducted at a temperature of between about −6° C. and about 12° C., preferably between about 6° C. and about 10° C., for a period of time between 3 hours and 4 weeks. If desired, the initial winterization step can be carried out for longer periods of time, such as up to two months, up to a year, or up to a year and a half.

III. Filtration Step and Commercial Uses for the Corresponding Filtrate

After the used cooking oil has been subjected to a first winterization step, the oil allowed to warm to at or near room temperature. Impurities that have crystallized and formed a pasty residue at the bottom of the sample can be collected, for example, by filtration, centrifugation, or decanting the top layer of oil from the pasty residue.
The filtrate (i.e., the pasty residue) can be used, for example, as a diluent (or a plasticizer) for roofing tars and asphalts.

IV. Further Winterization Step(s)

After the pasty residue has been removed, the resulting intermediate oil can still include relatively high fatty acid content. However, when subjected to additional winterization steps, the oil can separate into fractions that include relatively higher and relatively lower fatty acid content. When used as a feedstock for certain lubricant formulations, the oil can include relatively higher fatty acid contents than can be present in oil to be used as a feedstock to produce biodiesel. Accordingly, once the fractions are separated using one or more additional winterization steps, they can be separately isolated, for example, by draining a bottom phase, or by decantation or centrifugation.

V. Optional Neutralization of Free Fatty Acids

Depending on the initial fatty acid concentration in the used cooking oil, even after the oil has been subjected to winterization, and one or more fractions with relatively lower fatty acid concentrations than the initial used cooking oil are obtained, the concentration may be too high for use in transesterification reactions. In such a case, it is desirable to reduce the fatty acid concentration in such fractions. This can frequently be accomplished using a neutralization step or an esterification step.
Neutralization of fatty acids can be accomplished by washing the oil fractions with a basic solution. However, doing so tends to waste otherwise usable free fatty acids. For example, if the free fatty acid content of the used cooking oil was 10% by weight (which is within the range of concentrations that might be obtained), and the concentration is reduced up to half using the winterization step, the resulting 5% by weight concentration of the fraction would not be suitable for biodiesel production, at least if the biodiesel was produced using a transesterification process. If 5% of the weight of the oil were removed, for example, by extraction into a basic aqueous solution or by intercalation into clay, the quantity of biodiesel that can be produced is reduced by that amount.
Esterification, on the other hand, does not remove the fatty acids. Rather, the fatty acids are reacted with methanol or ethanol, in the presence of an acid catalyst rather than a basic catalyst, to convert the fatty acids to biodiesel. A limitation of this type of process is that it adds an extra step, and one must first remove the acid catalyst before performing a basic transesterification step.
The fatty acids in the oil fraction(s) can be neutralized by treating the oil fraction(s) with a lye solution, such as potassium or sodium hydroxide (NaOH). This tends to form soap. The soap can be removed from the oil by washing several times with clean water. This involves removing soapy water by draining it from the bottom of the oil, which is time consuming because the mixture must be allowed to settle before the water can be removed.
In one embodiment, a neutralization step involves chilling the oil fraction(s) to less than about 15° C., for example, between about −1° C. and 10° C., and, more typically, around 4° C. The fraction(s) are held at the chilled temperature for an hour or more. Then, an alkali solution is added, typically in the range of from about 10 to about 30% by weight of the total mixture of oil and alkali solution.
Any of a variety of alkaline materials can be used for this purpose, for example, sodium and potassium hydroxide, sodium bicarbonate, sodium carbonate, calcium hydroxide, potassium hydroxide, magnesium hydroxide, ammonia, and some organic alkalies. Examples of suitable organic alkaline compounds include the water-soluble soaps of fatty acids such as the alkali metal (e.g., sodium, potassium), ammonium or substituted-ammonium (e.g., alkanol-amine) salts of saturated or unsaturated fatty acids.
When sodium hydroxide is used, it is typically present at a concentration of from about 1.0 to about 2.5% by weight in water. It will be appreciated that solutions of other alkali agents can be suitably employed although they will be used in different amounts or concentrations depending upon solubility, stoichiometry and nature of the particular alkali employed.
The chilled oil and alkali solutions are then typically mixed with gentle agitation. The alkali solution is added until it forms from about 10 to about 30% by weight, for example, from about 15 to about 25%, of the total mixture. Agitation may be provided by any suitable means, although rotary mixers operating to provide low shear and high circulation are preferred. The agitation should be strong enough to uniformly disperse the alkali solution, but not so strong that an inseparable emulsion is formed. If high shear mixing is employed the alkali solution and the oil form a virtually inseparable emulsion making further separation difficult. The alkali solution is kept in contact with the oil for a minimum of a half hour.
The mixture can then be centrifuged to form a heavy phase and light phase. The heavy phase contains the fatty acids and certain other impurities, while the light phase includes the neutralized oil fraction. Once dried, the oil fraction can be used in biodiesel production as described herein.
Alternatively, the oil fractions comprising the fatty acids can be esterified with an alcohol, such as methanol or ethanol, in the presence of an acid catalyst. Any strong acid can be used as catalyst, including hydrochloric acid, sulfuric acid, acidic zeolites, and polymers with sulfonic acid groups, commonly referred to Dowex® and Amberlyst® catalysts, including Dowex®50, for example.
Another way to deal with oil fractions that include high FFA concentrations is to filter them through clay, where fatty acid salts can be intercalated into the clay.

VI. Biodiesel Production

The methods used for biodiesel production from the used cooking oil purified using the processes described herein are similar to conventional transesterification processes used for virgin cooking oils. However, the processes may vary depending on the amount of free fatty acids, as well as the water content of the used cooking oil.
Biodiesel can be produced in batches or continuous processes by transesterifying triglycerides such as animal fat or vegetable oil with lower molecular weight alcohols in the presence of a base or an acid catalyst. This reaction occurs stepwise, with monoglycerides and diglycerides as intermediate products. The relatively large vegetable oil molecule is reduced to about one third of its original size, lowering the viscosity making it similar to diesel fuel. The resulting fuel operates similar to diesel fuel in an engine. The reaction produces three molecules of an ester fuel from one molecule of vegetable oil. Transesterification is the process of separating the fatty acids from their glycerol backbone to form fatty acid esters (FAE) and free glycerol. The reaction is base-catalyzed, and involves reacting a triglyceride with an alcohol, which is typically methanol or ethanol. Transesterification is the most common method and leads to mono alkyl esters of vegetable oils and fats (i.e., biodiesel). The methyl/ethyl ester produced by transesterification of vegetable oil typically has a high cetane number, low viscosity and improved heating value compared to those of pure vegetable oil which results in shorter ignition delay and longer combustion duration and hence low particulate emissions.
During transesterification, a triglyceride reacts with a threefold excess of an alcohol such as ethanol or methanol, and this alcohol takes the place of the ester linkage to glycerol, yielding three fatty acid esters of the new alcohol and glycerol.
The biodiesel produced by this process is totally miscible, in any proportion, with diesel derived from crude oil.

VII. Lubricant Production

In order to manufacture a finished lubricant product from recovered oil samples, referred to herein as lube base oils, the lube base oils are compounded. Those of skill in the art can readily determine how to add additives to a lube base oil, using conventional blending techniques. These techniques relate to the order and the rate of additive addition, temperature regime, extent of mixing, and the like.
Additives Used in Lubricant Formulations
Lubricant formulations include lube base oil and one or more additives. Representative additives include antirust agents, antioxidant agents, demulsifiers, antifoam agents (also known as defoamers), viscosity modifiers, pour point depressants, antiwear agents, seal swell agents, dispersants, detergents, diluent oils (solvents), and combinations thereof.
Representative solvents include kerosene, Exxsol D-95, and biodiesel. Additional solvents include paraffin base, naphthenic base, asphaltic base, and mixed base oils. Synthetic oils include polyolefin oils (especially hydrogenated alpha-olefin oligomers), alkylated aromatics, polyalkylene oxides, aromatic ethers, and carboxylate esters (especially diesters), among others.
Representative antioxidants (oxidation inhibitors) reduce the tendency of base stocks to deteriorate in service, which deterioration can be evidenced by the products of oxidation such as sludge and varnish-like deposits that deposit on metal surfaces and by viscosity growth of the finished lubricant. Such oxidation inhibitors include, but are not limited to, hindered phenols, sulfurized hindered phenols, alkaline earth metal salts of alkylphenolthioesters having about C₅to about C₁₂alkyl side chains, sulfurized alkylphenols, metal salts of either sulfurized or nonsulfurized alkylphenols, for example calcium nonylphenol sulfide, ashless oil soluble phenates and sulfurized phenates, phosphosulfurized or sulfurized hydrocarbons, phosphorus esters, metal thiocarbamates, and oil soluble copper compounds as described in U.S. Pat. No. 4,867,890.
Representative antioxidants include the Irganox family of antioxidants, for example, Ciba® IRGANOX® 1010, Ciba® IRGANOX® 245 DW, Ciba® IRGANOX® 1035, Ciba® IRGANOX® 565, Ciba® IRGANOX® 1076, Ciba® IRGANOX® 1425, Ciba® IRGANOX® 1098, Ciba® IRGANOX® 1520, Ciba® IRGANOX® 1135, Ciba® IRGANOX® 1726, Ciba® IRGANOX® 1330, Ciba® IRGANOX® 5057, Ciba® IRGANOX® 245, Ciba® IRGANOX® HP 2225, Ciba® IRGANOX® B 215, Ciba® IRGANOX® B 612, Ciba® IRGANOX® B 225, and Ciba® IRGANOX® 1171.
Other antioxidants that may be used include sterically hindered phenols and diarylamines, alkylated phenothiazines, sulfurized compounds, and ashless dialkyldithiocarbamates. Non-limiting examples of sterically hindered phenols include, but are not limited to, 2,6-di-tertiary butylphenol, 2,6 di-tertiary butyl methylphenol, 4-ethyl-2,6-di-tertiary butylphenol, 4-propyl-2,6-di-tertiary butylphenol, 4-butyl-2,6-di-tertiary butylphenol, 4-pentyl-2,6-di-tertiary butylphenol, 4-hexyl-2,6-di-tertiary butylphenol, 4-heptyl-2,6-di-tertiary butylphenol, 4-(2-ethylhexyl)-2,6-di-tertiary butylphenol, 4-octyl-2,6-di-tertiary butylphenol, 4-nonyl-2,6-di-tertiary butylphenol, 4-decyl-2,6-di-tertiary butylphenol, 4-undecyl-2,6-di-tertiary butylphenol, 4-dodecyl-2,6-di-tertiary butylphenol, methylene bridged sterically hindered phenols including, but not limited to, 4,4-methylenebis(6-tert-butyl-o-cresol), 4,4-methylenebis(2-tert-amyl-o-cresol), 2,2-methylenebis(4-methyl-6 tert-butylphenol, 4,4-methylene-bis(2,6-di-tert-butylphenol) and mixtures thereof as described in U.S Publication No. 2004/0266630.
Rust inhibitors also include nonionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, and anionic alkyl sulfonic acids.
Representative demulsifiers include alkyl benzene sulfonates, polyethylene oxides, polypropylene oxides, esters of oil soluble acids and the like.
Defoamers suitable for use in the embodiments may include silicone oils of suitable viscosity, glycerol monostearate, polyglycol palmitate, trialkyl monothiophosphates, esters of sulfonated ricinoleic acid, benzoylacetone, methyl salicylate, glycerol monooleate, glycerol dioleate, polyacrylates, poly dimethyl siloxane, poly ethyl siloxane, polydiethyl siloxane, polymethacrylates, trimethyl-triflouro-propylmethyl siloxane and the like. The antifoams may be used alone or in combination. The antifoams may be used in the range of about 0.001 wt % to about 0.07 wt % based on the total weight of the concentrate.
Viscosity modifiers (i.e., tackifiers) provide viscosity improving properties. Examples of viscosity modifiers include vinyl pyridine, N-vinyl pyrrolidone and N,N′-dimethylaminoethyl methacrylate. Polyacrylates obtained from the polymerization or copolymerization of one or more alkyl acrylates also are useful as viscosity modifiers.
Representative dispersants include ashless type dispersants such as Mannich dispersants; polymeric dispersants; carboxylic dispersants; amine dispersants, high molecular weight (i.e., at least 12 carbon atoms) esters and the like; esterified maleic anhydride styrene copolymers; maleated ethylene diene monomer copolymers; surfactants; emulsifiers; functionalized derivatives of each component listed herein and the like; and combinations and mixtures thereof. The dispersant may be used alone or in combination.
Representative anti-wear agents include sulfur or chlorosulfur compounds, a chlorinated hydrocarbon compound, a phosphorus compound, or mixtures thereof Examples of such agents are amine salts of phosphorus acid, reaction products of alkenes or alkenoic acids with thiophosphoric acids, chlorinated wax, organic sulfides and polysulfides, such as benzyldisulfide, bis-(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized sperm oil, sulfurized methyl ester of oleic acid sulfurized alkylphenol, sulfurized dipentene, sulfurized terpene, and sulfurized Diels-Alder adducts; phosphosulfurized hydrocarbons, such as the reaction product of phosphorus sulfide with turpentine or methyl oleate, phosphorus esters such as the dihydrocarbon and trihydrocarbon phosphate, i.e., dibutyl phosphate, diheptyl phosphate, dicyclohexyl phosphate, pentylphenyl phosphate; dipentylphenyl phosphate, tridecyl phosphate, distearyl phosphate and polypropylene substituted phenol phosphate, metal thiocarbamates, such as zinc dioctyldithiocarbamate and barium heptylphenol diacid, such as zinc dicyclohexyl phosphorodithioate and the zinc salts of a phosphorodithioic acid, as well as combinations and mixtures thereof.
In one embodiment the antiwear agent comprises an amine salt of a phosphorus ester acid. The amine salt of a phosphorus ester acid includes phosphoric acid esters and salts thereof; dialkyldithiophosphoric acid esters and salts thereof; phosphites; and phosphorus-containing carboxylic esters, ethers, and amides; and mixtures thereof. In one embodiment the phosphorus compound further comprises a sulfur atom in the molecule.
In one embodiment the amine salt of the phosphorus compound is ashless, i.e., metal-free (prior to being mixed with other components). The antiwear agent can be used alone or in combination and may be present in an amount of 0.001 wt % to 0.5 wt %, based on the total weight of the concentrate.
Pour point depressants, otherwise known as lube oil flow improvers, lower the minimum temperature at which the fluid will flow or can be poured. Such additives are well known. Non-limiting examples of pour point depressant additives which improve the low temperature fluidity of the fluid are about C₈to about C₁₈dialkyl fumarate/vinyl acetate copolymers, polyalkylmethacrylates, alkylphenols and derivatives thereof, ethylene vinyl acetate copolymers and the like. The pour point depressant may be used alone or in combination. The pour point depressant is typically present in an amount of 0.01 wt % to 0.5 wt %, based on the total weight of the formulation.
Representative seal swell agents include organo sulfur compounds such as thiophene, 3-(decyloxy)tetrahydro-1,1-dioxide, phthalates and the like. The seal swell agents may be used alone or in combination. The seal swell agents may be present in an amount of 0.01 wt % to 0.5 wt %, based on the total weight of the formulation.
Processes for Producing Lubricants
The following general procedure can be used to prepare lubricant formulations using the base oils and additives described herein:
Obtain a cleaned container capable of mixing the various components. Add in a first volume of the lube base oil, with mixing.
Making sure the oil is mixed, begin heating the lube base oil until the temperature reaches a temperature between about 60 and 70° C.
Add the antioxidant (in this case, AO-L135 (BASF, sold under the tradename Irganox® L135), the tackifying additive (in this case, POL-V570, Controlled Release Technologies) and the pour point depressant (in this case, PPD-310), and mix the components for a suitable period of time, for example, between about 1 and 2 hours. Once the mixture is clear and uniform upon visual inspection, additional components, such as an anti-wear hydraulic additive package (in this case, HF-543, HiTEC®), the anti-wear additive (in this case, HF-902, HiTEC®), an odorant (in this case, ODOR1 and a cleaner/degreaser (in this case, GREEN1 Cleaner, sold by Green1 in Irvine, Calif.) and mix the components for an additional period of time, for example, between 30 and 60 minutes.
Add the remaining lube base oil, and mix the components for another one to two hours.
Optionally, submit a sample of the resulting lubricant oil formulation to quality control/quality assurance for analysis.
A representative set of equipment for producing the lubricant formulations described herein is shown in FIG. 5. As shown in FIG. 5, lube base stocks are added to a vessel equipped with a mixer, and drums/bags with additives are lined up for addition to the vessel. After the lubricant formulation is thoroughly mixed, the finished product can be drained out of the bottom of the vessel (the “lubricant outlet”), optionally filtered to remove solid impurities and insoluble components, then dispensed/packaged.
In one embodiment, the mixing tank has a capacity of around 1000 liters, so that the base oil can be prepared in relatively small batches. Ideally, the kettle mixer has two sets of blades, with the bottom set at <10% kettle capacity, and with four to six blades per set. The capacity of such kettle should be flexible enough to manufacture both larger and smaller batches (e.g. 2 drums of 55 gal), and the mixer should be sufficiently powerful to blend in polymeric and viscous additives, needed for specialty lubricant manufacture.
In case quality assurance is performed off-site, it is advisable to collect specimens of every additive lot that is used, as well as compounded product batches, and store them for an appropriate period of time, for example, 2 years or longer.
Manufactured product should provide consistent technical performance and meet established specification limits. Accordingly, it is advisable to compile a set of technical specifications for the product, and submit the additives and base oil to a quality assurance team for analysis before compounding, and submit the product for analysis as well.
The properties of base oil are crucial to the product quality, because the additives have only very limited influence on the oil appearance and phase separation. It can be desirable to monitor the quality of the base oil in order to obtain the most appropriate properties of the winterized used cooking oil.
One representative overall scheme for a Quality Assurance (“QA”) system is shown in FIG. 7. As shown in FIG. 7, used cooking oil is collected, and winterized using the processes described herein to provide a fraction of oil for use in biodiesel production, and a fraction of oil for use in lube oil formulations (i.e., a base oil or a lube base oil), which can be subjected to QA protocols to confirm their acceptability for the desired uses. Additives are obtained, and can also be subjected to QA protocols. The additives (referred to as raw materials) and base oil are combined, batchwise, to produce a “lube batch.” This lube batch can also be subjected to QA protocols, and if necessary, adjusted or re-worked. Optionally, once the material is determined to have satisfied the desired QA protocol, the final lubricant formulation can be sold.
As shown in FIG. 7, the QA protocol ideally cover three sectors: additives, base oils and finished lubricants. Each QA sector is briefly discussed below.
QA of Additives
Usually the additives are supplied along with the Certificates of Analysis, which indicate the compliance to the most important requirements for purity, homogeneity and sometimes performance specifications. Tests can be used to confirm the identity, as well as the purity, of the material. Visual/odor inspection, density and viscosity measurements usually are sufficient. Thin layer chromatography can also be used.
QA of Winterized Oil
The consistency of waste oil re-processing and extent of its winterization determine the quality of the formulated lubricant. In one embodiment, the QA involves keeping track of how the oil properties change when key processing parameters are varied. For example, it can be useful to track one or more of the following:
the maximum achieved temperature of the oil in the processing tank,
the duration of the oil residence in the processing tank,
the amount of sediment retained in the processing tank,
the amount of bulk oil retained in the processing tank,
the % vol of clear liquid layer in a sediment sample from the processing tank after a given time period, such as approximately 1 week,
the % vol of sediment in a bulk oil sample from the processing tank after a given time period, such as 1 week.
the maximum achieved temperature of the oil in holding tank
the duration of the oil residence in the holding tank
the sediment retained in the holding tank
the bulk oil retained in the holding tank
the % vol of clear liquid layer in sediment sample from holding tank after 1 week
the % vol sediment in bulk oil sample from holding tank after 1 week
the lowest achieved temperature of the oil in the winterization tank
the duration of the oil residence in the winterization tank
the bulk oil retained in the winterization tank
the % vol sediment in a bulk oil sample from the winterization tank after 1 month
By collecting and reviewing one or more of these parameters, preferably three or more of these parameters, and, more preferably, five or more of these parameters, it is possible to optimize regimes for the oil processing and winterization. In one embodiment, the data is collected throughout the hottest and coldest seasons of the operations, e.g. during July and January.
Formal QA of winterized oil can include an analysis of the fatty acid content, which is likely to relate to the precipitate formation. Relatively high amounts of stearic, palmitic and trans-fatty acids are usually responsible for increased sedimentation. Free Fatty Acid (FFA) and Total Acid Number (TAN) analysis are relevant, because the oil acidity defines lubricant anticorrosion properties and water incompatibility, as well as additive solubility and lubricity.
Although this is not necessarily a measure of lube base oil performance, it can be relevant to measure oil color, as darker colored lube base oils tend to be perceived by customers as being less desirable.
The viscosity, water content, solidification temperatures (pour and cloud points), and the like can also be measured.
QA of Finished Lubricants
Although faulty products are unusual in lubricant manufacturing, the kettle blending process is prone to compounder mistakes, raw material contamination and deviations from the established procedures. Accordingly, a QA system is ideally sufficiently reliable to identify problematic batches. For monitoring the quality of the finished lubricant, it can be desirable to perform a series of QA tests on every manufactured batch.
In case of chainsaw lubricants, the QA of finished product ideally includes one or more of the following tests:
Appearance at room temperature (clear, hazy, cloudy, sediment, etc.)
Color assessment
Viscosity at 40° C.
Cloud point
Total Acid Number
Tackiness
Water rejection
Density
To confirm that the lubricity additives and pour point depressants were properly added, one can use specialized equipment to identify the presence of these additives either directly (for example, using chromatographs or spectroscopes) or indirectly (using lubricity testers or low temperature baths). Because the presence of lubricity additives can be important, in one embodiment, these additives are colored before blending with the oil to assure they are present in the finished product.
Chain Saw Lubricant Formulations
In some embodiments, the lube base oils described herein can be combined with at least one additive to provide finished chainsaw lubricant compositions. Representative additives include antirust agents, demulsifiers, antifoam agents, dispersants, detergents, diluent oils (solvents), and combinations thereof.
Preferably, chain saw lubricant formulations include at least six components, namely, a lube base oil as described herein, a tackifier, a pour point depressant (PPD), an anti-wear (AW) additive, such as an extreme pressure (EP) antiwear additive, a rust inhibitor/protector (RP), and an antioxidant.
A representative formulation includes a lube base oil at around 80% by weight, a tackifier additive (Functional V-570, Functional Products, Inc) at around 15% by weight, a pour point depressant (Functional PD-551, Functional Products, Inc) at around 1.5% by weight, an anti-wear additive (Functional HF-560, Functional Products Inc) at around 0.9% by weight, an extreme pressure antiwear additive (Irgalube TPPT, BASF (formerly Ciba)) at around 0.9% by weight, a rust protector (DCHA (Di Cyclo Hexyl Amine), BASF) at around 0.9% by weight, and an antioxidant (Irganox L-135, BASF (formerly Ciba) at around 0.9% by weight, wherein all weight percentages are based on total weight of the formulation.
The V-570 additive in this embodiment is used at a 15% treat rate in the chainsaw lubricant. V-570 is a composition including a proprietary polymer in a vegetable oil base. The content of its active material (polymer) is higher than 1% wt.
The amounts of active materials out of the other additives in the formulation are typically below 1% wt. In one embodiment, the additives are ashless, so do not significantly affect the safety parameters of the chainsaw lubricants. Their toxicity is relatively low, except DCHA that is essentially completely converted into the soap, when blended with the re-processed oil.
The additives serve defined functions, and improve the performance of the lubricants, including the chainsaw lubricants. The function of the various additives is shown in the following table:

TABLE 1

Additives and Their Function.

	Representative
Component	Components	Function in chainsaw lubricant

BASE OIL		Basestock - acts as a lubricant itself, although low
(first portion)		quality. Without additives might produce heavy
		deposits, fast chain wear
AO ADD	Irganox L-135	Antioxidant - inhibits degradation of oil and
	Irganox 1010	additives at high temperatures due to friction.
	Irganox L-109	Prevents deposit formation.
TACK ADD	Functional V-570	Tackifier - adds stringiness (tackiness) to the oil,
	Functional V-584	not letting it drip or fly off the chain during
	LZ 7612	operation. Concurrently increases oil viscosity
Polymer	Functional V-508	Thickener - increases oil viscosity for better film
(only in	Functional V-508S	strength, separating the chain and the bar. Better
alternative		control of the flow when pouring out of container
formulation)		onto the chain. Reduced need for tackifier
		additives.
PPD	Functional PD-551	Pour point depressant - inhibits oil solidification at
	Functional PD-555	low temperatures short term. Does not prevent the
	LZ-7671A	solidification long term. Slightly increases
	Viscoplex 10-310	viscosity.
	Viscoplex 10-171
AW ADD	Functional HF-560	AntiWear additives - prevent the chain, bar,
	Functional HF-500	sprocket and other moving metal surfaces from
	LZ-7653	rapid wear under mediumload and elevated
	HiTEC 543	temperature conditions.
	HiTEC 2590A
EP ADD	Irgalube TPPT	Extreme Pressure additives - reduce friction under
	VanLube 0902	heavy loads, assuring there is no major damage to
	Additin RC 2317	the metal surface. Might protect the chain from
		losing sharpness when hitting metal wire, nails, etc.
RP ADD	DCHA	Rust Protection additives - partially neutralize the
	Additin RC 3760	free acids and provide corrosion inhibition. DCHA
		is also effective in vapor phase and it makes the oil
		more resistant to microbial attacks.
COLOR	only in alternative	Colorant - improves appearance and differentiates
ADD	formulation	the product from competitors
ODOR ADD	only in alternative	Odorant (odor mask) - suppresses potentially
	formulation	objectionable smell, improves customer acceptance
BASE OIL		Basestock - same functions. In compounding, the
(second portion)		second portion reduces the kettle heating and stirrer
		energy consumption.

In the table shown above, base oil is shown twice. In one embodiment of a method for preparing the lube base oils, the additives are added to a first portion of base oil, and after the components are thoroughly mixed, a second portion of base oil is added, and the composition is re-mixed.
In selecting the most effective additives several types of tests were carried out. The performance of the additives varied significantly, despite belonging to the same category. Most likely the base oil effect on the additives was more significant than anticipated. The best performing additives were identified by running the bench tests and included into the formulation. Their treat rates were also balanced accordingly. If necessary, most of these additives can be replaced with others, however, not always at 1:1 ratio.
In one embodiment, the lube base oil is used to prepare a chainsaw formulation. The table below shows the addition of conventional chainsaw lubricant additives to a lube base oil obtained using the process described herein. The formulation is sufficient to prepare three 55 gallon drums.
Green1 is a 100% bio-based, non-toxic, non-hazardous, green degreaser/cleaner, which includes a proprietary colloidal blend of 100% bio-based nanoparticles.
AO-L135, also known as Irganox® L135 antioxidant, has the following formula:
PPD-310 is a pour point depressant (also known as EX® 10-310).
HF-543 (also known as HiTEC® 543), is an ashless anti-wear hydraulic additive package.
V570 (Tackifier V-570, sold by Functional Products, Inc. in Macedonia, Ohio, is a proprietary polymer dissolved in a biodegradable vegetable oil, where the weight percentage of polymer to oil is around 10%)
The contents of a representative batch of a chainsaw lubricant is shown in the following table.

TABLE 2

Additive	% wt	Gallons

Base Oil	18.98	31.11
(first portion)
AO-L135	1	1.77
V570	6	10.52
PPD-310	1	1.73
HF-543	1	1.71
Van Lube 0902	2	3.39
Odorant*	0.01	0.02
GREEN1*	0.01	0.02
Base Oil	70	114.73
(second portion)
total	100	165

*GREEN1 (a cleaner) and odorants are optional components.

The formulation shown above is tabulated in the order of addition during the compounding process, which is why there are two separate amounts of lube base oil listed.
Mould Release Fluid Formulations
The re-processed oil, in particular, the lube base oils, described herein can be used to produce mould-release fluids. Mould release oil compositions include the lube base oil described herein, an organic solvent, such as kerosene, a tackifier, a rust inhibitor, an antioxidant, and optionally a demulsifier, and/or an odorant. A representative formulation is listed in the table below.

TABLE 3

Representative Mould Release Oil Formulations

		Representative
		Components or
	Component	Suppliers

Mineral solvent	Exxsol D-95 or	0	50
	kerosene
Biodiesel		30	0
Re-processed oil		50	30
Tackifier	Functional V-570	7	7
	(Functional
	Products, Inc.)
Rust inhibitor	Rhein Chemie		7	7
Antioxidant	Irganox		1	1
Odorant		0.1	0.1
Demulsifier		2	2

It is believed that the relatively high free fatty acid content in the re-processed oil will not be a problem for mould release fluids, particularly if a rust protective additive, such as DCHA, is incorporated into the formulation.
Cutting Oils
Where a sample of used cooking oil the lube base oil has excessive sediment, it may not be suitable for use in manufacturing cutting oils. The reason is largely that if customers find significant amounts of the residue in their cutting oil, they might assume that the residue is precipitated performance additives, rather than pasty residues from the used cooking oil itself. Accordingly, it is desirable to use uniform and clean base oils to produce cutting oils.
The processes described herein allow one to produce high quality winterized lube base oils that include relatively low sediment concentration. Examples of cutting oil additives include Oil Conditioner L, an antioxidant blend sold by Commonwealth Oil, Oil Conditioner M, a phosphorous and antioxidant spike, sold by Commonwealth Oil, and Oil Conditioner N, a tank side sulfurized fat performance additive, also sold by Commonwealth Oil, TRIM® OSFA, a lubricity additive for straight cutting oils, DARL concentrate (Fiske Brothers Refining Company, AZ 1371, a sulfur-containing cutting oil additive recommended for machining ferrous as well as non-ferrous metals (Addizol), emulsifiers such as Emulsifier P-15, Emulsifier P-25, Emulsifier P-35, and Emulsifier P-45 (Nipro Technologies Ltd.).
It is believed that lube base oils for use in cutting oils can include relatively high fatty acid concentrations, and also tolerate relatively high water contents, since it is possible to reduce the acidity by adding materials with high alkalinity, such as DCHA.
Hydraulic Fluids
Uniform and clean base oils are very important for producing hydraulic fluid. In case high quality winterized oil is produced, this application might become more likely to be successful.
Most lubricant additive suppliers provide additive packages for vegetable oil based hydraulic fluids. Typically, hydraulic fluids include an antioxidant, an anti-wear additive in a range of from about 0.5 to 5% by weight, a rust-proofing additive, a pour point depressant additive, in a range of between about 0.5 and 1.5% by weight, more typically around 1% by weight, and a defoamer, typically at a very low concentration, for example, around 0.005-0.05%. In such hydraulic fluid composition, all weight percentages are based on total weight of the composition.
Relatively high fatty acid content can adversely impact hydraulic fluid formulations. Additives, which might be required to improve the rust protection of the lubricant, might be affected negatively by this acidity. That is, one such additive is DCHA (dicyclohexylamine), which is a base, and bases react with acids.
Therefore, if the lube base stock includes a higher fatty acid concentration than the range described above, the fatty acid concentration may be lowered, for example, by subjecting the lube base stock to a neutralization step as described above, or by filtering the base stock through clays. The intercalation of salts of fatty acids into clays such as kaolinite is known in the art, for example, as described in Sidheswaran et al., “Intercalation of salts of fatty acids into kaolinite,” Clays and Clay Minerals, 38(1):29-32 (1990).
Effectiveness of Lubricant Additives in Re-Processed Base Oils
The specific formulations of the chainsaw lubricants described above include components from two suppliers only, Functional Products and BASF, though additives from other companies, such as Lubrizol, Evonik, Afton Chemical, RT Vanderbilt and Rhein Chemie can also be used.
Viscosity Studies
Vegetable oils are known for relatively uniform viscosities and re-processed oil confirmed that rule. Therefore, relatively high treat rates of polymers are necessary in order to increase their viscosity. Several thickeners and tackifiers were tested for their effectiveness. Functional V-570 (Functional Products) was selected for the specific formulation described herein because it provides both tackiness and higher viscosity. Typically, the viscosity increases exponentially with addition of more viscous additives. For confirmation, the viscosity dependence on the contents of V-570 was established from the experimental data, as shown in FIG. 6. The data showed that the viscosity dependence on the tackifier contents met the theoretical expectations, so the viscosity can be tailored to individual specifications by using the chart shown in FIG. 6 and providing the appropriate amount of the thickener/tackifier.
Low Temperature Studies
Similarly to viscosity, the trends of pour point depression (PPD) were studied.
The amount of PPD additives is expected to reach optimal performance at about 1% wt. treatment level, though experimental data (FIG. 8) showed somewhat different performance. Lube base oil formulations with different levels of tackifier (10, 15, and 20% by weight Functional V-570) with varying amounts of PPD (Functional 551 at 1, 1.5, and 2% by weight) were evaluated. Pour points continued to be depressed as the concentration of the PPD additives was increased to 2 percent by weight.
Low temperature solidification depends on both the pour point depressant and the tackifier concentrations. The amount of tackifier in these formulations is relatively high, and, accordingly, the crystallization kinetics, in particular the nucleation, can be affected significantly by the polymer chains in the tackifiers. The correlation also suggests that the lubricity additive might have an influence on crystallization as well.

VIII. Representative Process and Plant Design

Representative models for plants capable of winterizing used cooking oil are shown in FIGS. 2 and 3, which represent separate embodiments of a plant capable of carrying out the winterization processes described herein.
In both embodiments, a crude oil supply (also referred to herein as a waste oil supply) is sent to a processing tank. After the oil is cooled, and then allowed to warm to room temperature, crystalline impurities settle to the bottom of the processing tank. These can be drained through a valve, as shown, or, alternatively, the oil could be passed through a centrifuge and the solids collected in a centrifuge back, or the oil could be decanted from the solids.
Oil in the processing tank is then passed through intake piping to transfer the material to a holding tank, and allowed to further separate. The upper fraction is removed through intake piping, and a portion of the oil is collected for use as a feedstock for biodiesel production. Another portion of the oil is moved to a winterization tank. A lower fraction of oil including solid material is removed, and sent to the processing tank, where solids settles to the bottom and can be collected apart from the oil.
In the winterization tank, the oil is chilled, and allowed to form a precipitate. An oil fraction including the precipitate is also sent to the processing tank, and the oil that remains is passed through an intake valve and collected for use as a lube base stock.
In the embodiment shown in FIG. 3, the set up includes two winterization tanks. An oil fraction including a precipitate is removed from the bottom of the processing tank, and an intake valve is used to transfer the oil to a first holding tank. From there, precipitate is sent back to the processing tank, and the oil is removed from the top of the processing tank through an intake valve. A first portion of the oil is collected for use in producing biodiesel, and the remaining oil is passed on to two winterization tanks, where it is allowed to further settle. Solid precipitates resulting from the winterization step are passed to the processing tank, where they are collected, and the oil at the top is removed from both tanks through intake valves and collected for use as a base oil for lubricants.
When oil, such as used cooking oil, is allowed to separate, it tends to form at least the following layers—an upper layer of “sheen,” a bulk phase, a cloudy phase, a slurry phase, and a paste phase.
In order to remove these molecules, it is necessary to cool or refrigerate the oil initially, forcing their crystallization. Then the cold oil can be allowed to thaw, which leads to migration of more fluid molecules to the top of the oil and sedimentation of solid molecules on the bottom. Filtration can be exercised at that stage as well. Such process is typically referred to as oil winterization. Its suitability for the waste oil re-processing is discussed in detail below.
The longer the used cooking oil is stored, the better the sediment (“paste phase”) separates from the top layers. Typically, this is called ‘oil winterization’ in the food industry.
In a typical winterization process, oil is stored stagnant in storage tanks and pumped out from the top. Various thermal regimes are used, but generally it is considered that better winterization is achieved with lower the temperature of the storage tank and prolonged storage durations.
The oils are chilled, typically with gentle agitation, which causes higher melting fractions to precipitate. The higher melting fractions typically include waxes and fatty acids.
Filtration of the Re-Processed Oils, Lubricants and/or Biodiesel Formulations
In one embodiment, the reprocessed oils, biodiesel fuel, and/or lubricant formulations are filtered, preferably through a filter with a pore size of between approximately 5 and 50 microns, more preferably, between approximately 10 and 20 microns, to remove solid impurities.
The features and advantages of the present disclosure will be more fully apparent with reference to the following non-limiting examples.

Example 1

Initial Winterization Step

A series of samples of used cooking oil was obtained, and the oils were stored for various periods of times. The appearance and volumetric extent of phase separation is shown below in Table 4.

TABLE 4

sample	Age,	Bulk phase,	Cloudy	Slurry	Pasty
code	days	color	phase	phase	residues

1EC	480	Clear light	<10% vol.	None	None
		amber	hazy amber
2EC	480	Clear light	<10% vol.	~2% vol	~0.02%
		amber	hazy amber	light	vol.
				sediment	particles
3EC
	16	Clear medium	<5% vol.	8% vol.	3% vol.
		amber	hazy amber	heavy	thick paste
				sediment
4EC
	16	Clear medium	<5% vol.	5% vol.	4% vol.
		amber	hazy amber	heavy	thick paste
				sediment
5EC	4	Hazy medium	Same as bulk	0.5% vol.	0.5% thick
		amber	phase	heavy	paste
				sediment
6EC	4	Hazy medium	Same as bulk	Same as	1% thick
		amber	phase	paste	paste
7EC
	2	Hazy medium	Same as bulk	None	<0.1%
		amber	phase		light paste
8EC
	2	Hazy medium	Same as bulk	None	<0.1%
		amber	phase		light paste
9EC	4	Hazy medium	Not	n.d.	n.d.
		amber	determined
10EC	4	Hazy medium	n.d.	n.d.	n.d.
		amber

This data shows that upon longer term storage, it is possible to separate the oil into various layers. While not wishing to be bound to a particular theory, it is believed that the thermal history, i.e. cooling and heating regimes (temperature intervals, durations, rates) can have an impact on the appearance of the oil.
Immediately after arriving, the samples of 7EC (which was filtered) and 8EC (which was unfiltered) were each poured into two test tubes. All of them appeared equally hazy without any bottom sediment. One set was cooled to +5° C. overnight, while the other was left at room temperature (20° C.). After 16 hrs, the oils in the refrigerated test tubes were frozen. The test tubes were taken out, melted at room temperature and stored together with the other two samples, which always stayed at room temperature. The samples started forming a clear layer on the top and heavy residues on the bottom, with the hazy phase in the middle. The observations were recorded for two weeks, as shown in FIG. 4. FIG. 4 shows that there was an absence of pasty residues in refrigerated samples, whereas the room temperature samples 7EC RT and 8EC RT produced significant pasty residue. The refrigerated samples 7EC cold and 8EC cold formed a relatively uniformly cloudy bulk phase, which was slowly receding to the bottom. On the top, a phase of clear oil formed and kept expanding much more rapidly, compared to RT samples.
Those samples not cooled (i.e., stored at room temperature) samples could not consistently produce sizeable clear phase on the top for more than a week. Apparently, after initial clarification, some other molecules would begin crystallizing and make the fluid cloudy. The samples were stored on the bench of an air conditioned laboratory, therefore, some temperature fluctuations may have had an influence on the sample appearance. Nevertheless, refrigerated samples clarified much faster than RT samples.
The results suggest that the samples, even after about a week of storage, filtration has little beneficial effect on cloudiness of oil or its pasty residue formation tendencies. To the contrary, during the first 4 days the non-filtered sample 7EC RT was forming the clear layer and pasty residue faster than filtered sample 8EC RT. This can also be said about the clear phase formation of 7EC cold sample with respect to 8EC cold. While not wishing to be bound to a particular theory, it is believed that during filtration, the crystal seeds were removed, and it therefore took longer for the filtered samples to separate the precipitates. The dynamics of forming a cloudy phase changed when oil samples 9EC and 10EC were stored at room temperature. The room temperature samples were not frozen before storage, whereas the “cold” samples were refrigerated to about +5° C. for about 16 hrs before storing at room temperature. Oil samples 9EC and 10EC followed a somewhat different scenario in terms of sediment formation. Pre-Filtered oil (10EC) appeared to separate somewhat faster than 9EC. However, these oils were received 4 days after the manufacturing, compared to 2 days for 7EC and 8EC. In the meanwhile unknown temperature fluctuations could have taken place.
These observations lead to the conclusion that the re-processed oils contain a lot of molecules that are bound to form crystals and precipitate. In order to remove these molecules, it is necessary to cool or refrigerate the oil initially, forcing their crystallization. Then, the cold oil can be allowed to thaw, which leads to migration of more fluid molecules to the top of the oil and sedimentation of solid molecules on the bottom. Filtration can be exercised at that stage as well. This type of process is typically referred to as oil winterization, but winterization is typically performed on virgin oil rather than on used cooking oil. The suitability of winterization for waste oil re-processing is discussed in detail below.
In any event, significant phase separation was evident in samples 3EC, 4EC, 5EC, 6EC, 7EC, 8EC, 9EC and 10EC. Because sediment formation would be problematic in most lubricant applications, including hydraulic fluids, chainsaw lubricants, mould release fluids or cutting oils, the oils were subjected to further steps to minimize sediment formation.

Example 2

Comparison to Competitive Products

The properties of the chainsaw formulation described above were compared with those of several commercially-available chainsaw lubricants. Key lubricating properties were selected, including the tackiness, which is very important for chainsaw lubricants. Two purchases of the same brand (Power Care) were made in Home Depot, one in Pittsburgh (CAREP) and another in State College, Pa. (CARES). Other samples represented different brands. Arborol chainsaw lubricant (ARBOR), produced by Oregon Blount Inc., is designed to serve as water-dilutable chainsaw fluid, recommended ratio 5:1. It was tested as is, however, without any dilution. The test results are shown in the table below.

TABLE 5

Comparison of key parameters of competitive chainsaw lubricants

		Vis-		Lu-
		cosity	Pour	bricity*	Acidity
	Trade-	cSt at	point	WSD,	mgKOH/	Tack-
Lubricant	name		40*C	*C	mm	g	iness

Instant		120	−20	0.42	14	Good
Compo-
sition
CARES	Power	35.6	−33	0.54	~0	Poor
	Care,
	Home
	Depot
ECHO	Echo	141.1	−19	0.57	~0	Good
	Premium
	Home
	Depot
HQVAR	Husqvarna	141.5	−22	0.50	~0	Good
	Premium
PSEL	Pro Select	90.7	−27	0.49	~0	Satisfact.
	Lowes
POUL	Poulan,	139.4	−23	0.53	~0	Satisfact.
	Wal-Mart
CAREP	Power	153.2	−19	0.50	~0	Very
	Care,					good
	Pittsburgh
ARBOROL	Oregon,	139.8	−22	0.68	—	None
	Water
	Dilutable

*Four-ball wear scar diameter.

Since Arborol is designed for water-dilutable application, its viscosity and tackiness were not included into the comparative study. CARES lubricant was clearly very different from others, therefore, its performance was not considered for comparison either.
Nevertheless, the results for the formulation disclosed above either appear similar to other lubricants or exceed their performance. The viscosity is higher than that of Power Select and sufficiently similar to other brands. Pour point performance is similar as well. Tackiness is more pronounced than that of Echo Premium or Husqvarna Premium.
Particularly clear benefits are demonstrated in the lubricity aspects. Other lubricants demonstrated much more pronounced wear. It must be noted, that zero-wear is considered when Wear Scar Diameter (WSD) is equal to 0.34 mm. Therefore, the margin of advantage for the formulation described herein is much more pronounced. Also, the lubricity testing conditions are somewhat more severe than typical and include higher temperatures and more damaging speeds between moving surfaces. The relatively high fatty acid content did not appear to cause any corrosive wear. The free fatty acids appear to have contributed to the lubricity, but the levels are ideally kept low.
Vegetable oil based chainsaw lubricants tend to have lower stability than those based on mineral oil. For this reason, it may be desirable to add high molecular weight antioxidants.
Modifications and variations of the present disclosure relating to a fuel additive composition and an alternative fuel derived from the composition will be obvious to those skilled in the art from the foregoing detailed description.

Claims

What is claimed is:

1. A method of processing used cooking oil to recover material therefrom, wherein the used cooking oil has a first fatty acid concentration, said method comprising:

a) cooling the used cooking oil to temperature between about −6° C. and about 10° C., and maintaining it at such temperature for a period of time between about 3 hours and about four weeks,

b) warming the used cooking oil to temperature between about 115° C. and 140° C.,

c) sedimenting solid impurities from the used cooking oil,

d) separating the oil from the sedimented solid impurities,

e) subjecting the separated oil to a winterization, and

f) isolating from the winterized oil a fraction with a second fatty acid concentration, which is higher than the first fatty acid concentration, and a fraction with a third fatty acid concentration, which is lower than the first fatty acid concentration.

2. The method of claim 1, wherein the separated oil is subjected to more than one winterization.

3. The method of claim 1, wherein the solid impurities are used as a diluent or a plasticizer for roofing tars or asphalts.

4. The method of claim 1, wherein the used cooking oil comprises water, and the method further comprises removing water from the used cooking oil prior to said cooling a).

5. The method of claim 4, wherein the water is removed using a heating and settling process, comprising heating the oil to temperature above 120° C., and maintaining the oil at such temperature for a period of time of 36 hours or longer.

6. The method of claim 1, wherein the winterization comprises cooling the oil to temperature of about 10° C., and maintaining it at such temperature for a period of time between about two and four weeks.

7. The method of claim 1, wherein one or more of the oil fractions includes a higher free fatty acid concentration than a predetermined amount for a given application, further comprising removing fatty acids therefrom.

8. The method of claim 7, wherein the fatty acids are removed via neutralization and extraction, or via filtration through clay.

9. A lube base stock prepared by the method of claim 1.

10. A chain saw lubricant comprising a lube base stock prepared by the method of claim 1.

11. The chain saw lubricant of claim 10, further comprising one or more additives selected from the group consisting of tackifiers, pour point depressants, anti-wear additives, rust inhibitors, and antioxidants.

12. The chain saw lubricant of claim 11, comprising a pour point depressant at concentration of about 1.5% by weight, an anti-wear additive at concentration of between 0.1 and 1% by weight, an antiwear additive at a concentration of between 0.1 and 1% by weight, a rust protector between 0.1 and 1% by weight, and an antioxidant at concentration between 0.1 and 1% by weight, wherein all weight percentages are based on total weight of the chain saw lubricant.

13. A mould release fluid comprising a lube base oil prepared according to the method of claim 1.

14. The mould release fluid of claim 13, wherein the mold release fluid comprises a lube base oil, an organic solvent, a tackifier, between 0.1 and 1% by weight of a rust inhibitor, between 0.1 and 1% by weight of an antioxidant, and optionally between 0.1 and 3% by weight of a demulsifier and/or between 0.1 and 1% by weight of an odorant, wherein all weight percentages are based on total weight of the mold release fluid.