CA2418743C

CA2418743C - Emulsifiers and methods for creating improved emulsions

Info

Publication number: CA2418743C
Application number: CA002418743A
Authority: CA
Inventors: Tapantosh Chakrabarty
Original assignee: Imperial Oil Resources Ltd
Current assignee: Imperial Oil Resources Ltd
Priority date: 2003-02-12
Filing date: 2003-02-12
Publication date: 2006-02-07
Anticipated expiration: 2023-02-12
Also published as: CA2418743A1

Abstract

The invention provides a non-terminal alcohol ethoxylate (NTAE) for use; as an emulsifier. In one embodiment, the NTAE comprises the formula: where R' is a C1 to C48 alkyl group, R" is a C1 to C48 alkyl group and n is 1 to 100. The NTAE is particularly effective in forming an emulsion of water and a hydrocarbon such as bitumen. Emulsions created using the NTAE have a decreased droplet size to facilitate transportation and storage of the hydrocarbon as well as improving combustion efficiency when the emulsions are used as a fuel.

Description

EMULSIFIERS AND METHODS FOR CREATING IMPROVED EMULSIONS
FIELD OF THE INVENTION
The invention generally relates to the field of errmlsions. More specifically, this invention provides a non-terminal alcohol ethoxylate (NTAE) for use as an emulsifier. In one embodiment, the NTAE comprises the formula:
H
R'-C-R"

~OC2H4)n OH
where R' is a Cl to C48 alkyl group, R" is a Cl to C48 alkyl group and n is 1 to 100. The NTAE is particularly effective in forming an emulsion of water and a hydrocarbon such as bitumen. Emulsions created using the NTAE have a decreased droplet size to facilitate transportation and storage of the hydrocarbon as well as improving combustion efficiency when the emulsions are used as a fuel.
BACKGROUND OF THE INVENTION
The emulsification of whole bitumen with water and one or more emulsifiers is well known. Water/bitumen emulsions effectively reduce the viscosity of bitumen, thereby enabling its efficient transportation through pipelines and enabling its use as a burnable fuel.
In particular, water/bitumen emulsions having a small particle size are desirable because of the increased stability of the emulsion as well as improved combustion efficiency and decreased stack emissions.
Many emulsifiers have been proposed and utilized in creating stable emulsions.
Of these, phenol- or alcohol-based ethoxylates are the most common. In phenol- or alcohol-based ethoxylate emulsifiers, the base phenol or alcohol molecule is modified to increase its hydrophilicity by the addition of ethoxy groups to create phenol or alcohol ethoxylates.
Environmental concerns have arisen with the use of phenols resulting in a shift in recent years towards the use of alcohol ethoxylates. As a result, the recent prior art in particular teaches the use of terminal alcohol ethoxylate (TAE) emulsifiers with the formula R(OC2H4)"OH that are derived from terminal alcohols (R-OH) in which the OH group is at the last or terminal carbon in the hydrocarbon chain.
While such compounds are effective as emulsifiers, there continues to be a need for emulsifiers having superior interfacial properties to enhance the creation, handling and use of bitumen emulsions. For example, there is a need for emulsifiers that improve the quality of the emulsion by enabling the creation of finer emulsions that will enhance combustion efficiency. Furthermore, there is a need for emulsifiers that do not require other additives to simplify the emulsification process and avoid problems associated with certain additives.
Whereas additives such as amine or sodium have been used for the activation or creation of surfactants which may be naturally present in the bitumen, these additives may otherwise increase NOx emissions or increase the propensity for equipment corrosion.
There is also a need for emulsifiers having an appropriate hydrophile-lipophile balance for creating a water-external emulsion wherein the emulsifiers maximize surface coverage at the hydrocarbon/water interface in order to minimise the amount of surfactant required and/or reduce the size of the emulsion droplets. More specifically, there is a need for an amphipathic ethoxylate emulsifier with the above interfacial properties and one in which the attachment of the ethoxy groups to a non-terminal alcohol group creates a T-shaped molecule, where the head of the T is oleophilic and the stem of the T is hydrophilic. In addition, there is a need for emulsions that can utilize a variety of water sources for preparing the emulsion including municipal drinking water, water produced with bitumen, lake water, river water, canal water, ground water, brackish water or sea water. Finally, there is also a need for an effective method of preparing emulsions utilizing improved emulsifiers.
A review of the prior art has revealed that an emulsifier having this T-structure and these properties has not been previously disclosed.
For example, Canadian Patent 1117568 discloses an amphipathic terminal alcohol exthoxylate (TAE} of the general formula R(CH2CH20)"OH, where R is an alkyl group containing 10 to 20 carbon atoms (the oleophilic moiety) and n is the number of moles of ethylene oxide (E0) that is between 5 and 40 (the hydrophilic moiety). Because of the essentially linear structure of this molecule at the interface, both the oleophilic alkyl chain and the hydrophilic ethoxy alcohol penetrate their respective phases leading to a stick-like packing of the molecule at the oil-water interface. This results in both a larger oil droplet size in the emulsion and an increased amount of surfactant to prepare a stable, fine emulsion.
Canadian Patent 2232490 (Intevep) discloses the use of additives in addition to a TAE.
Specifically, this patent teaches the use of an amine and an electrolyte (NaOH) in addition to the TAE to form an emulsion having an average droplet size of 13 to 24 Vim.
However, the use of nitrogen-containing amine in an emulsion fuel leads to higher NOx emissions. Further, the use of NaOH will also result in the undesirable side-reaction of sodium reacting with vanadium in the bitumen which will form a stubborn sodium-vanadate scale known to cause corrosion of boiler tubes.
Other prior art includes US Patent 4,666,457, US Patent 4,725,287, US Patent 5,000,872, US Patent 5,024,676, US Patent 4,618,348, US Patent 4,976,745, US
Patent 5,263,848, US Patent 5,283,001, US Patent 5,437,693, US Patent 5,851,245, US
Patent 5,879,419, US Patent 5,902,227, US Patent 5,964,906, US Patent 5,976,240, US
Patent 5,993,495, US Patent 6,069,178, US Patent 6,194,472, US Reissue Patent 36,983, US Patent 6,113,659 and US Patent 6,384,091, none of which discloses the structure and use of a non-terminal alcohol ethoxylate as an emulsifier. Accordingly, there is a need for a method to create and utilise a non-terminal alcohol ethoxylate emulsifier for use as an emulsifier.

SUMMARY OF INVENTION
In accordance with the invention, there is provided a non-terminal alcohol ethoxylate (NTAE) for use as an emulsifier, the NTAE preferably having the formula:
H
R'-C-R"
I
(OC2H4)n OH
where R' is a C1 to C48 alkyl group, R" is a C1 to C48 alkyl group and n is 1 to 100.
More specific embodiments of the emulsifier include those wherein R' and R"
are C1 to C30, R' and R" are C1 to C20, R' is C5 to C10, R" is C4 to C7, and n is 6 to 40. In a specific embodiment, R' is C~His, R" is CSHlI, and n is 15.
The NTAE is particularly effective in preparing an emulsion comprising water, bitumen and the NTAE wherein the bitumen/water ratio is 5:95 to 95:5 (w/w). In more specific embodiments, the bitumen/water ratio is 20:80 to 80:20 (w/w), the bitumen is selected from any one of or a combination of Cold Lake bitumen, Athabasca bitumen, Cerro Negro bitumen or a resid fraction thereof and the emulsifier concentration is 0.03 to 2 % by weight and more preferably 0.08 to 1.25% by weight.
In accordance with the invention, the emulsion may he further characterised in terms of the mean droplet size and bulk droplet size. In various embodiments, the mean droplet size of the emulsion is less than 2.6 p,m, less than 7.9 p,m or less than 31 pm. In other embodiments, the emulsion is characterised by having bulk droplet size wherein 90% by volume of the droplets have a diameter less than 6 ~.m, less than 13 ~,m or less than 65 pm.
In accordance with another embodiment of the invention, a method of preparing a bitumen/water emulsion comprising the step of mixing water, bitumen and an NTAE
emulsifier in a mixing device to form the emulsion is provided. In a preferred embodiment, bitumen is introduced into the mixing device at an elevated temperature with respect to the water.

BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described, by way of example, with reference to the attached figures, wherein:
Figure 1 is a schematic diagram representation of a non-terminal alcohol ethoxylate (NTAE) in accordance with the invention and a ternzinal alcohol ethoxylate (TAE) as determined by computational chemistry;
Figure 2 is a comparison of actual and regression model droplet sizes; and, Figure 3 is a comparison of actual and power-law model droplet sizes.

DETAILED DESCRIPTIOhl The present invention provides a non-terminal alcohol ethoxylate (NT'AE) for use as an emulsifier and a method of creating a fine emulsion of water and hydrocarbon utilizing the NTAE.
NTAE ChenzistYy The starting alcohol for the NTAE emulsifier is a non-terminal alcohol:
H
R'-C-R"

OH
where the alcohol group, OH, is at a non-terminal carbon in the hydrocarbon chain. This starting non-terminal alcohol is ethoxylated to create an NTAE molecule in which a number of ethylene oxide or ethoxy groups (E0) are placed in between the non-terminal carbon and the OH group. This is contrasted with a terminal alcohol wherein the alcohol group is attached to a carbon atom that is at the end of the hydrocarbon chain according to the general formula R-OH, where R is an alkyl group that is unbranched or branched at a carbon position not adjacent to the alcohol group.
The NTAE emulsifier has the general formula:
H
-~-R99 (OC2H4)n OH
where R' is an alkyl group with 1 to 48 carbon atoms (C 1 to C48) and R" is an alkyl group with 1 to 48 carbon atoms (C 1 to C48). The number, n, of ethoxy groups (OC2H4) varies from 1 to 100. The preferred range for R' and R" is from 1 to 30 carbon atoms and for n from 3 to 50 and more preferably from 6 to 40. Both R' and R" can be linear or branched with an alkyl side chain.

For the emulsification of specific bitumen and/or fractions thereof, R' is C 1 to C20 and more preferably CS to C10, R" is Cl to C20 and more preferably C4 to C7.
In one embodiment of the NTAE, R' is C~HIS, R" is CSHlI, and the OH group is at the end of a chain of 15 EO groups.
With reference to Figure 1, an NTAE 2 and a terminal alcohol ethoxylate (TAE) 1 are shown schematically in a configuration as drawn by computational chemistry software (Titan by Wavefunction, Inc.). The amphipathic NTAE 2 has a T-shaped structure having hydrophobic 4 and hydrophilic moieties 5. As shown, the hydrophilic moiety 5, including the ethoxy chain 6, represents one arm of the 'T extending into the water phase 7 of a water/hydrocarbon interface 8. The hydrophobic moiety 4 includes two alkyl chains 9, 10 representing the top of the T extending across the water/hydrocarbon interface 8 on the hydrocarbon side 11 of the interface. In this example, R' is C7 alkyl (C~H15), R" is CS alkyl (CSH~ 1), and the OH group 15 is at the end of a chain of 15 EO groups 6. R' and R" may also be branched alkyl groups.
In comparison, the TAE 1 has a generally linear structure having the general formula R-(EO)"-OH (R is Cl2Hza in this example) wherein the hydrophobic moiety 12 extends deeply into the hydrocarbon phase 11. In other TAEs, R may be branched at carbon positions not adjacent the interface carbon position 14.
As a result, and as shown by computational chemistry and the following examples, the NTAE 2 covers more interfacial area than the TAE 1 and is, therefore, a better surface-active agent than the TAE 1.
NTAE Synthesis The NTAE is synthesized in accordance with known techniques having consideration to the properties of bitumen or bitumen fractions being emulsified and the desired properties of the emulsion wherein the above ranges of R', R" and EO represent practical ranges for the synthesis of useable emulsifiers.
The NTAE is made conventionally by the reaction of ethylene oxide with a non-terminal alcohol, in proportions set by the target moles of ethylene oxide.
The ability to obtain a favourable reaction of ethylene oxide with a non-terminal alcohol by setting the proportions based on the target moles of ethylene oxide is known to persons skilled in the art. In one such conventional method, the reaction is carried out in the presence of an alkaline catalyst (sodium or potassium hydroxide) at about 120° to 150° C. Reactor cooling is needed as the reaction is exothermic. At the end of reaction, the alkaline catalyst is neutralized with an acid.
The feed stock for ethylene oxide is natural gas or petroleum naphtha that is thermally cracked to produce ethylene. Reaction of ethylene with oxygen in the presence of a silver catalyst produces ethylene oxide, is well known to persons skilled in the art.
The non-terminal alcohol is made from naturally occurring oleochemical sources (vegetable or animal oils) or synthesized from petrochemical sources. Starting alcohols are available in which the total number of carbon atoms can range from i to 50, as is known to persons skilled in the art.
As indicated above, in the NTAE structure, the head part (the two alkyl groups attached to a carbon atom) is oleophilic and the stem part (OCZH4 groups) is hydrophilic. The ratio of these two parts determines the hydrophile-lipophile balance (HLB) of the emulsifier molecule. To emulsify a given oil, the surfactant requires the proper HLB. The HLB of a surfactant also correlates with its water solubility - the higher the HLB, the more water-soluble the surfactant is.
The HLB of a surfactant made from a given starting alcohol can be modified by changing the number of moles of OCZH4. As the number of moles of OCZH4 increases, the surfactant's hydrophile-lipophile balance increases along with its solubility in water. The physical state of the surfactant changes from liquid to solid as the OCZH4 number increases.
The melting point of the surfactant also increases with the OCZH4 number.
Thus, the number of moles of OC2H4 relative to the carbon chain numbers in the two alkyl groups in R' and R" is important in determining a favourable surfactant chemistry to emulsify a given hydrocarbon.
_g_ Water and Bitumen Sources The water and bitumen sources for an emulsion prepared with the NTAE may vary.
Unlike emulsions made with an ionic surfactant that is known to be sensitive to the water salinity and the presence of divalent ions, such as calcium and magnesium in the water, an emulsion using the non-ionic NTAE can be prepared with water from different sources with variable salinity and divalent ion concentrations.
Suitable sources of water include municipal drinking water, water produced with bitumen, lake water, river water, canal water, ground water, brackish (saline) water or sea water all of which may be used either in whole or in part to make the emulsion.
The bitumen for making the emulsion may be held-produced bitumen that may contain emulsified produced water.
In one embodiment, the field-produced, oil-externall emulsion is not dewatered if it contains less than the target water content of the emulsion fuel. Additional water from any of the above sources is added to meet the water concentration target of the water-external emulsion.
In a further embodiment, the produced bitumen contai~vng emulsified water is dewatered conventionally to less than a predetermined amount of water and then additional water from any of the above sources is added to make the target water content of the final water-external emulsion.
Further still, the bitumen may be completely dewatered and the water from any of the above sources added to make a water-external emulsion with a target water content.
In still yet another embodiment, the dewatered bitumen may contain an amount of diluent used in typical dewatering processes. The bitumen and the water may also contain oil-field demulsifier(s).
Typical hydrocarbons that can be emulsified include but are not limited to Cold Lake Bitumen, Athabasca Bitumen, and Cerro Negro Bitumen whose typical properties are shown in Table 1. Other hydrocarbons include Fischer-Tropsch liquids and waxes.

Table 1. Typical Bitumen Properties Properties Bitumen Cold Lake Cerro Negro Athabasca API Gravity 11 7.9 8.8 Viscosity @ 15C 84184 7584702 251706 Viscosity @ 40C 4112 133371 12311 Basic Nitrogen, 4014 6188 4100 ppm Sulfur, wt% 4.3 3.7 4.7 CCR, wt% 13.8 17.2 13.3 Neutralization 1.3 3.0 2 - 4 No.

(mg KOH/g) Vandium, ppm 178 367 210 Nickel, ppm 85 96 83 Method for Preparing Emulsions An emulsion can be prepared in accordance with the following general methodology.
A hydrocarbon, such as bitumen, water and emulsifier are introduced at elevated temperature into a mixing device and vigorously mixed to form an emulsion.
Upon exiting the mixing device, the resulting emulsion may be cooled for subsequent downstream handling.
The process may be batch or continuous and may be practised using a variety of mixing devices, including a rotor-stator assembly having an adjustable clearance, where both rotor and stator have circular grooves intersected by radial grooves.
Other embodiments of mixing devices include on-line, non-moving mixing devices.
Stable emulsions may be prepared by forcing bitumen, water and emulsifier through mixing devices such as sintered porous metal or perforated disks.
The bitumen to water ratio is 5:95 to 95:5 and preferably 20:80 to 90:10 (w/w). The range of emulsifier concentrations is preferably 0.03 to 2% by weight and more preferably 0.08 to 1.25% by weight, all based on emulsion. The pre-mixing temperature of the bitumen may be 40° C to 300° C and preferably 60° C to 100° C. The pre-mixing temperature of the water may be 4° C to 150° C and preferably 30° C to 90° C. The temperature of the bitumen is generally higher than the water in order to promote pumping of the bitumen into the mixing device. The temperature of the water is preferably less than 100° C to eliminate the need for vessel pressurization.
ZTse of Emulsions The emulsions prepared in accordance with the invention can be used in a variety of applications principally either to facilitate transportation of hydrocarbon through pipelines, or by tankers (land and sea) and/or as a fuel.
In one use, the emulsion is burned as a fuel in a dual-fuel burner almost immediately after synthesis, thereby eliminating or reducing the need for storage and/or transportation of the emulsion. A dual-fuel burner can burn either gaseous fuel when the gaseous fuel price is low and burn the emulsion fuel when the gaseous fuel price is high. In another embodiments where an emulsion is synthesized almost immediately before; use as a fuel, and where longer-term emulsion stability may not be required, the emulsion may be synthesized using less water while maintaining a small droplet size, thereby improving the combustion efficiency.
In another embodiment, the water-soluble NTAE emulsifier is used alone or in combination with other conventional water-soluble surfactants (non-ionic, cationic and anionic) or chemicals that generate surfactants in situ by forming soaps of carboxylic and napthenic acids present in the bitumen. Such chemicals are alkali (sodium hydroxide, NH3, ammonium hydroxide, potassium hydroxide and sodium carbonate). In addition, other low-molecular weight alcohols, such as methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, pentyl, iso-pentyl to decyl and iso-decyl alcohol can be used as a co-surfactant.
Examples Example 1 Produced Cold Lake Bitumen was de-watered to 0.7% water and subsequently emulsified using the NTAE of Figure 1 by adding additional water. Bitumen at 85° C was pumped at 6900 L/h and a water solution containing the emulsifier at 53° C was pumped at 3300 L/h through a commercial-size rotor-stator assembly rotating at 4200 rpm.
Upon exiting the rotor-stator assembly, the emulsion was rapidly cooled from 70° C
to 48° C to maintain emulsion quality and reduce possible coalescence that may occur at higher temperatures. The resulting emulsion had a water volume of 33.6% and an emulsifier concentration of 0.75°/~ by weight. The average droplet size was 2.5 ~,m, the median droplet size was 2.3 ~.m and 90% by volume of the droplets were smaller than 4.7 p,m. The resulting emulsion was stable for longer than one month and had a viscosity of 125 cp at 50° C.
Example 2 The conditions for this example were the same as those for Example 1 except that the rotor speed was reduced from 4200 rpm to 3600 rpm. The lower rotor speed resulted in slightly larger particles with a mean droplet size of 2.6 pxn, a median of 2.2 l.un and 90% by volume of the droplets being smaller than 5.0 pm.
Example 3 The conditions for this example were the same as those for Examples 1 and 2 except that the rotor speed was further reduced to 3000 rpm. Further lowering of the rotor speed resulted in a further increase in the droplet size with a mean of 2.9 p,m, a median of 2.3 p,m and 90% by volume of the droplets being smaller than 5.7 pm.
Example 4 The conditions for this example were the same as those in Example 3 except that the emulsifier concentration was increased to 1.1 wt%. The increased emulsifier concentration resulted in a finer emulsion with a mean droplet size of 2.3 yn, a median of 1.8 pm and 90%
by volume of the droplets being smaller than 4.4 pm.
Example 5 The conditions for this example were the same as those for Example 4 except that the rotor speed was increased from 3000 rpm to 3600 rpm. This resulted in a slightly finer emulsion with a mean droplet size of 2.1 p,m, a medium draplet size of 1.8 ~.m and 90% by volume of the droplets being smaller than 3.8 pm.
Example 6 The conditions for this example were the same as those for Example 5 except that the rotor speed was increased from 3600 rpm to 4200 rpm. This resulted in a slightly finer emulsion with a mean droplet size of 2.0 prn, a medium droplet size of 1.8 pm and 90% by volume of the droplets being smaller than 3.6 pm.
Example 7 This example repeated E~cample 2 to confirm reproducibility and resulted in a mean droplet size of 2.4 pm, a medium droplet size of 2.0 and 90% by volume of the droplets being smaller than 4.4 pxn. The statistical significance of the variations between Examples 2 and 7 is explained in the description of example 9 below.
The emulsion from Example 7 was pumped through a gear pump to a 26.4 GJ
commercial-size demonstration boiler capable of burning both a gaseous fuel and a liquid emulsion fuel. This capability allows switching between a gaseous fuel and a liquid emulsion fuel depending on the gaseous feel price. Droplet analysis before and after the pump showed no sign of emulsion degradation by the pump. The combustion of the emulsion exhibited excellent flame characteristics with long, slender and stable flames with a few sparklers. Very fine oil droplets in the emulsion led to high carbon conversion efficiency, low particulates, low carbon monoxide and low NGx emissions. The emulsion fuel was comparable to burning No. 6 fuel oil. The switching between gaseous and liquid emulsion fuel and vice versa also went very smoothly.
Example 8 The conditions for this example were the same as those in Example 7 except that the emulsifier concentration was reduced from 0.75% to 0.25% by weight. The rotor speed was set at 3600 rpm. The resulting emulsion had a mean droplet size of 7.9 hum, a median droplet size of 7.5 ~m with 90% by volume of the droplets being smaller than 12.7 Vim.
Example 9 This example repeated Examples 2 and 7 to confirm reproducibility in emulsion quality. The mean droplet size was 2.2 ~m and the median was 1.8 ~m with 90%
by volume of the droplets being smaller than 4.0 ~.Lm. This emulsion was also burnt successfully in the 26.4 GJ dual-fuel burner. This example again demonstrates the excellent reproducibility of the emulsion quality using the emulsifier and method of this invention. The mean particle size from three repeat runs was 2.3 ~.m with a very tight 95% confidence interval of 2.1 tc~ 2.5 Vim.
As in Example 7, the switching between the gaseous and liquid emulsion fuel went very smoothly, demonstrating that the same burner can be used for both fuels.
Example 10 (Comparison of NT'AE with a Commercial Asphalt Emulsifier) Examples 1 to 9 relate to whole bitumen emulsification. In Example 10, a heavier fraction of bitumen was used to compare the effectiveness of the NTAE
emulsifier with a commercial asphalt emulsifier consisting of an amine and hydrochloric acid.
A 520° C+ fraction (resid) of Cold Lake bitumen was blended with water containing the commercial asphalt emulsifier in a laboratory blender. The hydrocarbon to water ratio was 68:32 (w/w). The resid was preheated to 160° C and the water containing the amine (0.2% by weight based on emulsion) and enough hydrochloric acid to lower its pH to 3 was heated to 80° C. In the first test, all of the resid was poured into the water in the blender. The blending of this mixture was very difficult and noisy as the unemulsified resid got stuck in the blender's blades. No emulsion was formed. A repeat attempt to make the emulsion by slowly pouring the resid to the emulsifier solution while blending was also unsuccessful.
A similar emulsification test was conducted with the NTAE emulsifier of this invention and the same resid. Blending in this case was smooth and after blending for 30 seconds an oil-in-water emulsion containing 31 % by volume water was formed.
The emulsifier concentration in the emulsion was 0.24% by weight. An oil-in-water emulsion was also formed in another repeat test where the resid was added i.n two stages.
This example shows that under conditions where a commercial asphalt emulsifier cannot emulsify a heavy fraction of bitumen, the emulsifier of the present invention creates an emulsion without requiring additional compounds including amine or hydrochloric acid.
Discussion of Examples 1 to 9 The oil droplet sizes for emulsions prepared with the NTAE are much lower than that disclosed in CA 2232490. In Tables 2, 3, 4, 5 and 6, and in Figures 1, 9, 10, 13 and l.4 of CA
2232490, the mean droplet size is described as ranging from 13 to 24 pm. This was achieved by a combination of three additives. Eight out of nine examples using this invention show mean particle size in the range of 2 to 2.9 Vim. These are lower than those in CA 2232490 by a factor of 4.5 to 12Ø In particular., one example of the subject invention with 0.25% by weight surfactant shows mean particle size of 7.5 pm with 90% by volume of the particles being lower than 12.7 ~,m, which is still smaller than the lowest mean particle size obtained by CA
2232490.
Further Examples Relating to mater Content, Surfactant Concentration and Preparation Further tests using NTAE reveal that the water content in a whole bitumen emulsion can be reduced by at least half from the industry standard of 30% by volume water based on the total volume of the emulsion. In addition, further testing has demonstrated that the concentration of NTAE surfactant can be reduced from those used in Examples 1 to 9.
Lower surfactant and water concentrations are expected to reduce the cost of commercializing emulsions as an alternate fuel technology, particularly in a scenario where emulsions are burnt as they are made. In this scenario, the need for storage and/or pumping emulsions at low temperatures (that is, less than about 50° C) is eliminated. Therefore, emulsions can be made with a lower surfactant concentration and a lower water content. In addition to cost savings associal;ed with a lower surfactant concentration, a lower water content will improve the economics of the process by increasing the heat value of the fuel per unit volume of emulsion, and dec~~easing the water handling and recycling costs.
Further evaluation of NT.AE was conducted in an in-line static mixing unit wherein emulsions were made by varying the water content from 6.6% to 36.6% by vohune and varying the surfactant concentrai:ion from 0.03% to 0.18% by weight, both based on total emulsion. In addition to these two variables, the effects of maximum liquid superficial velocity (MXLSV), bitumen and surfactant temperatures on mean oil droplet size were also studied. MXLSV is a measure of shear rate (or agitation) and is determined by the measuring the flow rate of both separate and combined components (bitumen and water) through a static mixing emulsification process (SMEP) apparatus. The MXLSV was varied from 3..6 to 4.3 m/s, the bitumen temperature from 74° to 98° C and the NTAE
solution temperature from 53°
to 68° C.
NTAE was dissolved in Calgary tap water and preheated from 53° to 68° (J. Field-produced Cold Lake bitumen devratered to 0.7% water was preheated from 74° to 98° C in a separate vessel. Each liquid wa.s pumped separately through the following static mixer combination: 30.5 cm x 1.27 cm; 30.5 cm x 0.95 cm; 30.5 cm x 0.64 cm. The inside diameter of 0.64 cm of the smallest static mixer set was used to calculate the maximum superficial velocity of the co-mingled bitumen and NTAE water. The pressure upstream of tlhe static mixer was monitored and the emulsion type checked using the water dispersion test. In the dispersion test, a small drop of emulsion is placed on top of water taken in a small container.
If the drop easily disperses into tile water, the emulsion has a continuous water phase that is miscible with the water in the cantainer. On the other hand, if the emulsion drop does not disperse in the water but stays a.s a drop, the emulsion has a continuous oil phasfs that is immiscible with water. The water content of the emulsion was determined using a Dean-Stark analysis. A Beckman Coulter LS - 230 particle size analyzer (available from E~eckman Coulter, Miami, Florida) was used to determine particle size distribution. The shelf stability of the emulsion was assessed by observing the amount of water separation at the bottom of the bottle stored at room tempera~.ure. Stability was recorded. after 1 hour, 2 hours, 2 0 hours and one month.

Results Table 1 shows the results of the SMEP tests.
Table 1 NTAE Bitumen Mean Mean Mean % Water*Flow Emulsifier PressureSize, Size, Rate Emulsion MXLSV

Concn.* T T T um um Size, um wt% vol% cm3/minmis C C C KPag Exptl. Regressionpwer-Law Model Model 0.090 36.6 4680 4.26 74 59.0 69 958.3721.4 21.7 20.9 0.088 35.4 4680 4.2 75 59.0 70 923.9021.8 22.0 21.1 0.068 27.0 2410 2.2 75 59.0 73 379.2138.2 38.0 37.9 0.068 27.1 2410 2.20 76 59.0 73 406.7938.1 38.2 38.2 0.097 38.3 4500 4.10 95 53.0 70 786.0021.5 20.9 20.9 0.097 38.2 4500 4.10 96 53.0 72 730.8423.7 21.0 21.0 0.088 35.1 4320 3.94 97 53.0 79 613.6322.6 23.2 22.6 0.088 35.4 4320 3.94 98 53.0 79 634.3220.9 23.4 22.8 0.157 31.4 4320 3.94 75 58.0 67 923.9012.0 11.7 15.3 0.135 27.0 4140 3.77 76 58.0 70 854.9514.9 15.7 16.8 0.030 6.6 3815 3.48 77 58.0 78 875.6331.0 30.7 31.4 0.175 17.5 3960 3.61 75 67.0 76 854.9516.3 15.5 15.7 0.182 18.2 3960 3.61 76 67.0 77 827.3714.3 14.8 15.6 0.162 16.2 3960 3.C~1 76 67.0 78 820.4717.3 17.6 16.2 0.163 16.3 3960 3.61 76 68.0 79 799.7918.5 18.2 16.5 SOS 15.98 32.43 'based MSOS 2.00 4.05 on STD 1 2 emulsion DEVN. , .

R2 0.98 0.96 As shown in Table l, emulsions were made at or around the industry standard.
of 30%
water, with 16% to 18% water, and with as little as 6.6% water, all by volume.
The results in Table 1 also show the ability to make an emulsion with less than 0.25% by weight N7.'AE, the lowest concentration tried previously in a commercial-scale rotor-stator assembly. In the SMEP unit, emulsions were made with O.IB% by weight NTAE or lower and with as little as 0.03% by weight (300 ppm) NTAE in the emulsion.
The most significant observation from the tests in Table 1 is that an oil-in-water emulsion can be made with as little as 0.03% (or 300 ppm) by weight NTAE
concentration and with as little as 6.6 % by volume of water, both based on emulsion. The mean oil. particle size at this combination is, however, 31 ~m with 90% by volume of the particles being smaller than 65 Vim. Using this combination of NTAE and water concentration, finer emulsions can be made using higher MXLSV and/or additional static mixers.
In all the tests, the emulsic>ns made were stable at least for a month showing no sign of water separation. One-month stability is sufficient for applications where the emulsion is burned as a fuel shortly after its s~mthesis.
An emulsion made at 3.6 m/s MXLSV, 0.18% by weight NTAE, 18% by volume water, a bitumen temperature of 76° C and an NTAE solution temperature of 67° C had a mean particle size of 14.3 ~m and was stable for at least one month. In addition, the pressure upstream of the static mixer was :not much different from that of the 31.4%
water by volume emulsion as shown in Table I. A.s mentioned earlier, finer emulsions can be prepared using higher MXLSV and/or additional static mixers.
Emulsion Droplet Size Prediction Two types of models, a power-law and a linear regression model were used to relate the mean oil droplet size to the independent variables in the study described as follow;a:
Regressiofz Model:
ODS = 0.0234 - (158.7547 * SC) - (6.9422 * MXLSV) + ( 0.1913 * WC) + (0.1669 ~' BT) + (0.7834 * sT) where, ODS = mean oil droplet size, ~,m SC = surfactant concentration, % by weight based on emulsion MXLSV = maximum liquid superficial velocity, m/s WC = water content, % by volume based on emulsion BT = bitumen temperature, °C
ST = NTAE soluticm temperature, °C
For this model, the mean sum of squares (Mean SOS), defined as the sum of squares of the differences between the experimental and model-predicted particle sizes divided by the degrees of freedom is 2.0 (p.m)2. The degrees of freedom, defined as the number of experimental runs (15 in this case) minus the number of parameters in the model (~6 in this case) minus l, is 8. The standard deviation (Std. Devn.), defined as the square root of the Mean SOS, is 1.4 pin, while the: correlation coefficient, R2, between the experimental and predicted mean oil droplet size is 0.98.
Table 1 and Figure 2 show that the experimental mean particle sizes compare well with the ones predicted by the regression model.
Power-Law Model:
ODS = (1.205 E - 02) * (S~')-°~s7°' * (MXLSV)'° 7430 * (WC)o.zaz4 * (BT)°.4802 * (ST)1.0478 Mean SOS = 4.05 (pm)Z
Std. Devn. = 2.01 pin R2 = 0.96 Table 1 and Figure 3 show good agreement between the experimental and the;
power-law model predicted mean particle sizes.
Both models allow the quantification of the effect of each pertinent variable on the mean droplet size. As expected, both models predict that the particle size should decrease with increased NTAE concentration and/or increased flow velocity.
An unexpected prediction from the models is that a reduction in water content decreases oil droplet size. What this means is that an emulsion created with less than the industry standard of 30% by volume water has smaller oil droplets. While this emulsion may be less stable than conventional emulsions because of lower water, it may be particularly effective as a fuel that is burnt alrr~ost immediately after preparation.
The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto.

Claims

1. A bitumen/water emulsion comprising water, bitumen and a non-terminal alcohol ethoxylate (NTAE).

2. The bitumen/water emulsion of claim 1, wherein said NTAE comprises:
where R1 is a C1 to C48 alkyl group, R" is a C1 to C48 alkyl group and n is 1 to 100.

3. The bitumen/water emulsion of claim 2 wherein R' and R" are C1 to C30.

4. The bitumen/water emulsion of claim 3 wherein R' and R" are C1 to C20.

5. The bitumen/water emulsion of claim 4 wherein R' is C5 to C10.

6. The bitumen/water emulsion of any one of claims 2 to 5 wherein R" is C4 to C7.

7. The bitumen/water emulsion of claim 2 wherein R' is C7H15, R" is C5H11, and n is 15.

8. The bitumen/water emulsion of any one of claims 2 to 7 wherein any one of or a combination of R' and R" are branched having an alkyl side chain.

9. The bitumen/water emulsion of claim 2 wherein R' is C7 and R" is C5 alkyl.

10. The bitumen/water emulsion of any one of claims 2 to 6 and 9 wherein n is 6 to 40.

11. A bitumen/water emulsion as in any one of claims 1 to 10 wherein the bitumen/water ratio is 5:95 to 95:5 (w/w).

12. A bitumen/water emulsion as in claim 11 wherein the bitumen/water ratio is 20:80 to 80:20 (w/w).

13. A bitumen/water emulsion as in any one of claims 1 to 12 wherein the bitumen is selected from the group comprising Cold Lake bitumen, Athabasca bitumen, Cerro Negro bitumen, a resid fraction thereof and any combination thereof.

14. A bitumen/water emulsion as in any one of claims 1 to 13 wherein the bitumen is field-produced bitumen that contains emulsified water.

15. A bitumen/water emulsion as in any one of claims 1 to 13 wherein the bitumen is field-produced bitumen that has been dewatered with a diluent.

16. A bitumen/water emulsion as in any one of claims 1 to 13 wherein the bitumen is field-produced bitumen that has been dewatered without a diluent.

17. A bitumen/water emulsion as in any one of claims 1 to 16 wherein the emulsifier is 0.03 to 2% by weight.

18. A bitumen/water emulsion as in claim 17 wherein the emulsifier is 0.08 to 1.25%
by weight.

19. A bitumen/water emulsion as in any one of claims 1 to 18 wherein the water for the emulsion is selected from the group comprising municipal drinking water, water produced with bitumen, lake water, river water, canal water, ground water, brackish water, sea water and any combination thereof.

20. A bitumen/water emulsion as in any one of claims 1 to 19 wherein the mean droplet size of the emulsion is less than 2.6 µm.

21. A bitumen/water emulsion as in any one of claims 1 to 19 wherein the mean droplet size of the emulsion is less than 7.9 µm.

22. A bitumen/water emulsion as in any one of claims 1 to 19 wherein the mean droplet size of the emulsion is less than 31 µm.

23. A bitumen/water emulsion as in any one of claims 1 to 19 wherein the median droplet size of the emulsion is less than 2.5 µm.

24. A bitumen/water emulsion as in any one of claims 1 to 19 wherein the median droplet of the emulsion is less than 7.5 µm.

25. A bitumen/water emulsion as in any one of claims 1 to 19 wherein the median droplet of the emulsion is less than 39 µm.

26. A bitumen/water emulsion as in any one of claims 1 to 19 wherein 90% by volume of the droplets have a diameter less than 6 µm.

27. A bitumen/water emulsion as in any one of claims 1 to 19 wherein 90% by volume of the droplets have a diameter less than 13 µm.

28. A bitumen/water emulsion as in any one of claims 1 to 19 wherein 90% by volume of the droplets have a diameter less than 65 µm.

29. A method of preparing a bitumen/water emulsion comprising the step of mixing water, bitumen and an NTAE emulsifier in a mixing device to form the emulsion.

30. A method of preparing a bitumen/water emulsion comprising the step of mixing water, bitumen and an NTAE emulsifier to form the emulsion wherein the bitumen/water emulsion is in accordance with any one of claims 1 to 28.

31. A method of preparing a bitumen/water emulsion as in claim 29 wherein the bitumen, water and emulsifier are introduced into a mixing device selected from the group comprising a rotor-stator assembly, on-line non-moving mixing devices, sintered porous metal or a perforated disk, and any combination thereof.

32. A method as in claim 31 wherein the bitumen is introduced into the mixing device at a higher temperature than the water.

33. A method as in claim 31 or 32 wherein the bitumen is introduced into the mixing device at 20° to 300° C and the water is introduced at a temperature of 4° to 150° C.

34. A method as in any one of claims 31 to 33 wherein the emulsion is cooled after exiting the mixing device.

35. A method as in any one of claims 31 to 34 wherein the mixing device is a rotor-stator assembly and the rotor speed is 3000 to 4200 rpm.

36. A method as in any one of claims 29 to 35 wherein the bitumen for making the emulsion is field-produced bitumen containing emulsified produced water.

37. A method as in claim 36 wherein the field produced bitumen contains less than the final target water and wherein additional water is added to create the emulsion.

38. A method as in claim 36 wherein the field-produced bitumen is dewatered prior to making the emulsion.

39. The use of the bitumen/water emulsion as in any one of claims 1 to 28 as a fuel.

40. The use of the bitumen/water emulsion as in any one of clams 1 to 28 to facilitate transportation of bitumen through pipelines or tankers or to facilitate storage of bitumen.

41. The use of the bitumen/water emulsion as in any one of claims 1 to 28 as a fuel in a dual-fuel burner system.

42. A bitumen/water emulsion, comprising: water, bitumen and a non-terminal alcohol ethoxylate (NTAE), said NTAE comprising:

wherein R' is C7H15, R" is C5H11, and n is 15; wherein the bitumen/water ratio is 5:95 to 95:5 (w/w), wherein the mean droplet size of the emulsion is less than 2.6µm, wherein the median droplet size is less than 2.5 µm, wherein 90%
by volume of the droplets of the emulsion have a diameter of less than 6 µm.