BARBEAU, John (Forest BioProducts Inc, 875 Queen Street EastSault Ste Marie, Ontario P6A 2B3, CA)
DUCHESNE, Luc, C. (Forest BioProducts Inc, 875 Queen Street EastSault Ste Marie, Ontario P6A 2B3, CA)
JAEHRLING, Norman, R. (Forest BioProducts Inc, 875 Queen Street EastSault Ste Marie, Ontario P6A 2B3, CA)
BARBEAU, John (Forest BioProducts Inc, 875 Queen Street EastSault Ste Marie, Ontario P6A 2B3, CA)
DUCHESNE, Luc, C. (Forest BioProducts Inc, 875 Queen Street EastSault Ste Marie, Ontario P6A 2B3, CA)
CLAIMS
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
Claim 1 : A portable device for the transesterification of animal- and plant-derived glycerides, in small scale batches of 50-500 L, more or less, comprising a mounting frame, a main vessel used for transesterification and washing, a circulation system, an alcohol and catalyst mixing system, a facultative cleaning system under various combinations and a facilitative spill containment system.
Claim 2: A component of the device as according to claim 1 , which includes a reaction vessel which may be closed with a removable hatch and vented, includes heating elements or others source of heat and which is the main vessel used in the transesterification reaction.
Claim 3: A component of the device as according to claim 1 , which includes a circulation and piping system including transparent pipes and/or tubing mounted vertically on the side of the primary vessel for dual use in the circulation of the feedstock and/or biodiesel as well as a manometer and which permits visual assessment of phase separation which takes place during transesterification of glycerides.
Claim 4: A component of the device as according to claim 1 , which includes transparent pipes and/or tubing which are mounted below the reaction tank which permits to discriminate between the glycerin and fatty acid alky ester phases and the physical separation of the former and permits the elimination of the latter through gravimetry and or with the aide of a pump.
Claim 5: A component of the device as according to claim 1 , which may include a filtration unit which is mounted inside the main reservoir and permits the filtration of residues which may be contained in the feedstock. Claim 6: A component of the device as according to claim 1 , which may include a bottom reservoir for the containment of spilled reagents, feedstocks and/or biodiesel;
Claim 7: A component of the device as according to claim 1 , which may include an electrical console for the control of electrical equipment which is associated with subcomponents of claims 1 -6;
Claim 8: A component of the device as according to claim 1 , which may include a support stand and base which permits to hold subcomponents of the device as according to claims 1 to 7 in a single skid with a low footprint and which may be fitted with handles for easy handling and/or transport. |
A device for the transesterif ication of animal and plant glycerides into fatty acid alkyl esters for small scale production of biodiesel and value added products
BACKGROUND OF THE INVENTION
This invention relates to a portable device for the batch transesterification of glycerides into fatty acid alkyl esters, particularly fatty acid methyl esters, in a small scale system in the general range of 50-500 L, more or less, which permits the economic production of fatty acid alkyl esters for various uses, including biodiesel.
Biodiesel generated from the transesterification of animal and vegetable fats is a globally accepted and generally ecologically sound substitute to petrodiesel in the various applications for which the latter is known. Of all such applications, replacement of petrodiesel with biodiesel in mobile engines offers the potential for a significant impact in the economy of remote, rural and low density areas of the world.
The use of transesterified fatty acids as fuels for diesel engines is constrained by the necessity of the biodiesel to meet certain standards with respect to chemical contamination and composition. Fatty acid esters show a bulk density which is lower than that of glycerin, a byproduct of transesterification. For biofuel (biodiesel) applications, tolerance for impurities from various sources which include but are not limited to soap, colour, odours, unreacted catalyst, metals and metallic compounds, free and total glycerin, methanol, chlorophyll, water and sediment are listed in the specifications for ASTM 6751 for North America and European Standard EN14214 for Europe.
Fabrication of biodiesel is described in various patents, including EP 07708 813, AU 2006100428, WO 2004053036, WO 2005JP14015 20050801 and WO 200228811 , and generally consists of a process including steps of (1) degumming, (2) acid catalyzed esterification of free fatty acids with methanol in the presence of sulfuric acid, and (3) neutralization of the acid catalyst followed by conventional base catalyzed transesterification. The resulting diesel can then be washed with acids (WO 2004053036) or with adsorbants (WO 2005037968). Cooke et al. (WO 2005037969) described a
process based on the use of adsorbant materials, including magnesium silicate, for cleaning biodiesel to meet ASTM and EN requirements. The content of patent WO 2005037968 is hereby incorporated by reference. Cooke et al. (WO 2005037969), however, did not address the removal of the adsorbant materials after contacting with biodiesel. Such removal of the adsorbant material is critical to meet fuel standards and prevent damages to engines by end-users.
Previous inventions dealing with the transesterification of glycerides into biodiesel describe methods for manufacturing of fatty acid alkyl esters through complex continuous processes using large scale, multi-vessels equipment which creates economical fuel only at large production scales. For example, patent CA 2,499,821 designed a method based on the continuous transesterification at large scale processes using a complex multi-vessels system whereby the transesterification reaction is supported by dynamic emulsification using cavitation, ultrasound, and/or cavitation of a two phase system.
Another example, CA 2,280,289 by Boocock and Brooke created a method based on a continuous single-phase production system using cosolvents which increases phase co- mingling as described by Fisher et al. in CA 2,499,821.
Another example, patent CA 2,515,816 describes a complex, capital-intensive, automated, method for refining biodiesel which includes the transesterification catalyst to be prepared in a base catalyst tank by spraying alkyl alcohol under pressure through jets at metal hydroxide pellets until the pellets have fully reacted with the alcohol. The feedstock oil is heated and transesterified in the presence of alkyl alcohol and the transesterification catalyst in a closed, recirculating transesterification flow system under slight cavitation to yield product alkyl ester and product glycerol. Cavitation is achieved by permitting air to enter the transesterification flow system through an adjustable air inlet valve. Purification of the product alkyl ester preferably includes subjecting the product alkyl ester to an overhead water mist in a wash tank with simultaneous infusion of a stream of air bubbles.
In practice, the sophisticated levels of automation of previous arts (CA 2,499,821 ; CA 2,280,289; CA 2,525,816; US 2005204612; WO 2005017075) for the production of
biodiesel do not permit them to create cost-effective fuel at the scale of single biodiesel users in batch sizes of 100-500 L. Indeed, the apparatus described in patents CA 2,280,289; CA 2,499,821 ; CA 2,515,816; CA 2,525,816; MD 20040091 ; US 2005204612, US 2005006290; WO 2003016442; WO 2005017075 necessitate significant capital outlays to build, sophisticated controls to operate which together with their large sizes limit the market potential and/or usefulness of transesterified fatty acid technologies to large groups of biodiesel consumers which are found in large population centers while excluding their application in scarcely populated or geographically isolated areas such as rural, northern or remote environments. This is of special significance to restaurant owners who generate waste vegetable oil or oilseed farmers with excess seedstocks and emphasizes the need for small-scale systems.
Although attention to the small-scale concept for biodiesel manufacturing has been given in some patents, there is a need for improvement. Patent WO 2004035396 relates to a single 20-30 L vessel of clear or opaque plastic and uses hand shaking of the mixture in the vessel to produce biodiesel. The vessel is fitted with openings that allow the input of fluids and for the careful draining-off of stratified layers. The vessel incorporates lined levels on the sides of the vessel to assist the person in calibrating the amount of feedstock and the special blend of alcohol/catalyst (Biodiesel Converter) that will promote the reaction to produce biodiesel. Patent WO 2003022961 provides a description for a device based on a complex continuous flow and acid catalysis in the 1440 L range.
SUMMARY OF THE INVENTION
The invention addresses the need to create a simplified small scale device for the transesterification of animal and vegetable fats, either virgin or used, at a general range of 50-500 L batches and which can be operated by a minimally trained operator without the assistance of computer technologies and heavy infrastructure and can be easily transported from one location to the next. As such, the small size as well as the simplicity of use permit to deploy this biodiesel manufacturing technology to single users, restaurant owners, oilseed farmers as well as remote and low density parts of the world.
The invention comprises a primary vessel, preferably made of steel, supported on a frame. The primary vessel is connected to a mixing chamber as well as an optional filter assembly also mounted on the side of the reaction tank. The device may be mounted inside a spill containment basin. The main reaction vessel is heated with immersion heaters, preferably, or other means of heating to and maintaining reaction temperature. The invention includes an electrical console which permits the control of the electrical equipment which are subcomponents of the device. Elimination of the glycerin phase resulting from transesterification is conducted through transparent piping and facilitated by transparent piping serving as a manometer which is mounted on the side of main reaction vessel. Elimination of the lower phase is conducted through gravimetric flow and can be aided by a circulation pump. Purification of the remaining transesterified fatty acids is conducted through the addition of adsorbant material or acid washes. If adsorbant material is used, an optional filter housing unit can be used, preferably mounted on the side of the main vessel, for filtration of adsorbant particles. An embodiment of the invention includes a spill containment basin to prevent possible environmental contamination.
In the drawings, which form a part of this specification,
Fig. 1 is a side elevational view of the preferred embodiment of the device in its totality;
Fig. 2 is a side elevational view of the device support stand and mounting hoops;
Fig. 3 is a top plan view of the device support stand and mounting hoops;
Fig. 4 is a side elevational view of the primary vessel, system pump, associated plumbing and support stand with mounting hoops;
Fig. 5 is a side elevationai view of the filter housing, associated plumbing and support stand with mounting hoops;
Fig. 6 is a side elevational view of the alcohol/catalyst tank, associated plumbing and support stand with mounting hoops;
Fig. 7 is a longitudinal section view of the electrical console; and,
Fig. 8 is a top plan view of the device in its totality;
DETAILED DESCRIPTION OF THE INVENTION
In the preferred embodiment, the primary vessel of the device described is made of steel or material which is resistant to the conditions of the primary vessel and is fitted with two immersion heaters and includes a circulation system made of transparent tubing which permits the operator to visually ascertain the presence of phase separation as well as facilitates the removal of the glycerin phase from the primary vessel. The transesterified fatty acids containing adsorbant material is piped to a filter housing containing bag filters to specific mesh sizes such as those described in patent US 5514275 and which permit the elimination of absorbent material from the biofuel. The fabrication of such filters and filter assembly is described in patent US 5514275, the contents of which are hereby incorporated by reference.
In another embodiment of the current invention, the transesterified fatty acids are pumped through a column packed with absorbent material which is therefore prevented to reenter the primary vessel.
In the following two examples the invention is further described for the purpose of illustrating its application but not to limit scope of the invention.
Example 1: Transesterification of waste vegetable oil from restaurant deep fryers followed by cleaning using magnesium silicate and filtration column
1 ) Preparation of the waste vegetable oil feedstock for transesterification: a. Titrating the waste vegetable oil feedstock to determine its free fatty acid content; b. Measuring the water content of the waste vegetable oil feedstock; c. Filtering the waste vegetable oil feedstock through a 100 micron strainer and into the primary vessel; d. Circulating and heating the waste vegetable oil feedstock to 60 0 C; e. Settling and dewatering the waste vegetable oil feedstock, if necessary;
f. Dissolving the alkaline catalyst, particularly sodium or potassium hydroxide, in the alcohol, particularly methanol, in the alcohol/catalyst tank;
2) Performing the transesterification reaction: a. Adding the alcohol/catalyst mixture to the waste vegetable oil feedstock. The valves are configured such that the system pump simultaneously draws waste vegetable oil feedstock from the primary vessel outlet and alcohol/catalyst mixture from the alcohol/catalyst tank outlet and vigorously blends the two streams inside the pump chamber. The reaction mixture is then pumped to the vessel inlet. The rate at which the alcohol/catalyst mixture is added to the waste vegetable oil feedstock is controlled by way of an in-line flowmeter. b. Circulating the reaction mixture. The reaction mixture is continuously pumped from the bottom of the primary vessel to the top of the primary vessel and the temperature of the reaction mixture is maintained at 6O 0 C by way of the immersion heaters. c. Settling and draining the crude byproduct. Heat and mixing are removed and the reaction mixture is allowed to settle and separate under gravity into its two distinct phases or layers - the raw biodiesel phase and the crude glycerin phase. Following a settling period, the crude byproduct phase is repeatedly drawn-off the bottom of the primary vessel. d. Warming the raw biodiesel. Heat and mixing are re-applied to the raw biodiesel to raise the temperature to 60 0 C prior to the addition of magnesium silicate to the primary vessel.
3) Purifying the biodiesel fuel: a. Adding magnesium silicate. Magnesium silicate is added to the primary vessel and circulated with the raw biodiesel. The amount of magnesium silicate added to the raw biodiesel depends on the free fatty acid content of the original waste vegetable oil feedstock:
For example, raw biodiesel made using a waste vegetable oil feedstock with a free fatty acid content of 4.6% w/w of the waste vegetable oil feedstock would receive magnesium silicate at 1.9% w/w of the waste vegetable oil feedstock. b. Removing the magnesium silicate. Mixing is removed and the mixture of biodiesel and magnesium silicate is allowed to settle. The magnesium silicate that has accumulated on the bottom of the primary vessel is repeatedly drawn-off. Settling permits the removal of the larger magnesium silicate particles (i.e. >100 microns), however the smaller particles must be removed by filtration. In this example, the filter housing and 4 sizes of polypropylene felt filter bags (i.e. 100, 50, 25 and 5 micron) are used to eliminate the very fine magnesium silicate particles from the clean biodiesel. The valves are configured such that the pump delivers biodiesel containing magnesium silicate from the primary vessel outlet to the filter housing inlet and draws filtered biodiesel from the filter housing outlet and pumps it to the primary vessel inlet. The biodiesel is sent through the filter housing on each
filter bag. The purified biodiesel is then transferred from the primary vessel to a storage containers).
Example 2: Transesterification of virgin vegetable oil followed by acid washing
1) Preparation of the virgin vegetable oil feedstock for transesterification: a. Titrating the virgin vegetable oil feedstock to determine its free fatty acid content; b. Measuring the water content of the virgin vegetable oil feedstock; c. Filtering the virgin vegetable oil feedstock through a 100 micron strainer and into the primary vessel; d. Circulating and heating the virgin vegetable oil feedstock to 6O 0 C; e. Settling and dewatering the virgin vegetable oil feedstock, if necessary; f. Dissolving the alkaline catalyst, particularly sodium or potassium hydroxide, in the alcohol, particularly methanol, in the alcohol/catalyst tank;
2) Performing the transesterification reaction: a. Adding the alcohol/catalyst mixture to the virgin vegetable oil feedstock. The valves are configured such that the system pump simultaneously draws virgin vegetable oil feedstock from the primary vessel outlet and alcohol/catalyst mixture from the alcohol/catalyst tank outlet and vigorously blends the two streams inside the pump chamber. The reaction mixture is then pumped to the primary vessel inlet. The rate at which the alcohol/catalyst mixture is added to the virgin vegetable oil feedstock is controlled by way of an in-line flowmeter. b. Circulating the reaction mixture. The reaction mixture is continuously pumped from the bottom of the primary vessel to the top of the primary vessel and the temperature of the reaction mixture is maintained at 60C by way of the immersion heaters. c. Settling and draining the crude byproduct. Heat and mixing are removed and the reaction mixture is allowed to settle and separate under gravity into its two distinct phases or layers - the raw biodiesel phase and the crude glycerin
phase. Following a settling period, the crude byproduct phase is repeatedly drawn-off the bottom of the primary vessel.
ter-washing the biodiesel fuel: a. Adding the wash water/mild acid. An amount of water equal/mild acid to one third the volume of raw biodiesel is added to the main vessel. The wash water settles as a discrete phase at the bottom of the primary vessel. b. Bubbling the wash water/mild acid. Air is gently bubbled into the wash water/mild acid phase by way of a ceramic air stone connected to a hose containing compressed air. The air bubbles carry water/mild acid up through the raw biodiesel phase to its upper surface where the bubbles burst. The wash water/mild acid then descends through the raw biodiesel phase and returns to the wash water phase. On its ascent and subsequent descent, the wash water dissolves any polar compounds it encounters in the biodiesel phase. c. Removing the wash water. After bubbling the air stone is removed and the wash water is allowed to settle to the bottom of the primary vessel. After settling the spent wash water is drawn-off and disposed of. d. The water washing process is performed 3 times.