CA2049404A1 - Method for controlling the quality of an emulsion - Google Patents
Method for controlling the quality of an emulsionInfo
- Publication number
- CA2049404A1 CA2049404A1 CA002049404A CA2049404A CA2049404A1 CA 2049404 A1 CA2049404 A1 CA 2049404A1 CA 002049404 A CA002049404 A CA 002049404A CA 2049404 A CA2049404 A CA 2049404A CA 2049404 A1 CA2049404 A1 CA 2049404A1
- Authority
- CA
- Canada
- Prior art keywords
- emulsion
- surfactant
- oil
- storage
- added
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000839 emulsion Substances 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 23
- 239000004094 surface-active agent Substances 0.000 claims abstract description 65
- 239000003921 oil Substances 0.000 claims abstract description 21
- 238000003860 storage Methods 0.000 claims abstract description 13
- 239000010779 crude oil Substances 0.000 claims abstract description 8
- 239000002736 nonionic surfactant Substances 0.000 claims abstract description 7
- -1 alkyl phenol Chemical compound 0.000 claims abstract description 6
- 239000007864 aqueous solution Substances 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims description 14
- 230000006866 deterioration Effects 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 239000000243 solution Substances 0.000 claims description 6
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical group C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 claims description 4
- SNQQPOLDUKLAAF-UHFFFAOYSA-N nonylphenol Chemical class CCCCCCCCCC1=CC=CC=C1O SNQQPOLDUKLAAF-UHFFFAOYSA-N 0.000 claims description 4
- 239000008186 active pharmaceutical agent Substances 0.000 claims description 2
- 230000005484 gravity Effects 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims description 2
- 229920000847 nonoxynol Polymers 0.000 claims description 2
- 239000000446 fuel Substances 0.000 abstract description 9
- 238000003756 stirring Methods 0.000 abstract description 3
- 239000007764 o/w emulsion Substances 0.000 abstract description 2
- 238000005504 petroleum refining Methods 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 9
- 238000010008 shearing Methods 0.000 description 7
- 239000000203 mixture Substances 0.000 description 5
- 239000000523 sample Substances 0.000 description 5
- 238000005191 phase separation Methods 0.000 description 4
- 239000003945 anionic surfactant Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000013068 control sample Substances 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000003359 percent control normalization Methods 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- JNYAEWCLZODPBN-JGWLITMVSA-N (2r,3r,4s)-2-[(1r)-1,2-dihydroxyethyl]oxolane-3,4-diol Chemical class OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O JNYAEWCLZODPBN-JGWLITMVSA-N 0.000 description 1
- 241000132023 Bellis perennis Species 0.000 description 1
- 241000282461 Canis lupus Species 0.000 description 1
- 235000008495 Chrysanthemum leucanthemum Nutrition 0.000 description 1
- IGFHQQFPSIBGKE-UHFFFAOYSA-N Nonylphenol Natural products CCCCCCCCCC1=CC=C(O)C=C1 IGFHQQFPSIBGKE-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000003905 agrochemical Substances 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000003093 cationic surfactant Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 150000003856 quaternary ammonium compounds Chemical class 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 230000000246 remedial effect Effects 0.000 description 1
- 150000003333 secondary alcohols Chemical class 0.000 description 1
- 238000013112 stability test Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 125000001273 sulfonato group Chemical group [O-]S(*)(=O)=O 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 230000003442 weekly effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L1/00—Liquid carbonaceous fuels
- C10L1/32—Liquid carbonaceous fuels consisting of coal-oil suspensions or aqueous emulsions or oil emulsions
- C10L1/328—Oil emulsions containing water or any other hydrophilic phase
Landscapes
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Liquid Carbonaceous Fuels (AREA)
- Colloid Chemistry (AREA)
Abstract
7569(2) ABSTRACT OF THE DISCLOSURE
METHOD FOR CONTROLLING THE QUALITY OF AN EMULSION
The rate at which an emulsion of a viscous oil in water emulsion may deteriorate in storage is reduced by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added aqueous surfactant to remain in contact with each other. The surfactant is preferably mixed with the emulsion by gentle stirring. The emulsions are preferably combustible fuel emulsions and the oil may be a heavy crude oil or a residue from a petroleum refining process. The surfactant is preferably a non-ionic surfactant, most preferably an alkyl phenol ethoxylate.
METHOD FOR CONTROLLING THE QUALITY OF AN EMULSION
The rate at which an emulsion of a viscous oil in water emulsion may deteriorate in storage is reduced by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added aqueous surfactant to remain in contact with each other. The surfactant is preferably mixed with the emulsion by gentle stirring. The emulsions are preferably combustible fuel emulsions and the oil may be a heavy crude oil or a residue from a petroleum refining process. The surfactant is preferably a non-ionic surfactant, most preferably an alkyl phenol ethoxylate.
Description
7569(2) METHOD FOR CONTROLLING TH~ QUALITY OF AN EMULSION
This invention relates to a method for controlling the quality of an emulsion of a viscous oil in water, particularly an emulsion intended for combustion as a fuel, by arresting or reducing the rate at which the emulsion may deteriorate when subjected to prolonged standing, for example in storage tanks.
Emulsion fuels prepared from viscous oils have been previously described in the patent literature and elsewhere. For example, GB
974042 discloses a fuel composition comprising an oil-in-water emulsion of a petroleum oil having a viscosity above 40 SSF at 122F, the amount of water in said emulsion being such that said emulsion has a viscosity of less than 150 SSF at 77F and the said oil comprising at least 60 volume per cent of the emulsion.
The oils which are emulsified are generally viscous oils which in their non-emulsified state are too viscous to be pumped and require high preheat temperatures to be atomised successfully in combustion equipment.
Large deposits of viscous oils occur in several parts of the world, eg in Canada, USA, USSR and Venezuela. It is likely that emulsified fuels will become more commercially important in the future as the need to exploit the aforementioned deposits increases.
Such emulsified fuels are generally stable, some more so than others, depending on the method of production.
However, on prolonged storage, eg over a period of months or years, there may be a tendency for some emulsions to deteriorate somewhat, eg for the mean particle size of the droplets to increase, for the particle size distribution to widen and for the emulsions to become more susceptible to shear degradation, for example, in pumps, valves or at burner tips. This can give rise to problems in handling and combusting the emulsions.
GB 2220673-A discusses the problems of deteriorated, ultraheavy emulsion fuels and proposes methods for the regeneration of such deteriorated emulsions. If the deterioration is slight, a non-ionic surfactant is added to the deteriorated emulsion and the resulting mixture is subjected to high shear agitation. If the deterioration is more severe, an anionic surfactant is added, the mixture is sheared and a non-ionic surfactant is added. Alternatively, an anionic surfactant and a non-ionic surfactant are both added and the mixture is then sheared.
GB 2220673-A is concerned with a remedial treatment to restore the quality of an emulsion after significant deterioration has occurred.
We have now devised a preventative method for maintaining the quality of an emulsion of a viscous oil in water, which may have a tendency to deteriorate in storage, by reducing the rate at which it may deteriorate.
Thus according to the present invention there is provided a method for reducing the rate at which an emulsion of a viscous oil in water may deteriorate in storage by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added aqueous surfactant to remain in contact with each other.
In order to avoid the unnecessary use of surfactant, since the emulsion may be used before it has deteriorated or deteriorated to any significant extent, it may be advisable not to add the surfactant until signs of deterioration are noted.
Thus according to a further feature of the invention there is provided a method for reducing the rate at which an emulsion of a viscous oil in water may deteriorate in storage by monitoring the emulsion and, if signs of deterioration are noted, by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added aqueous surfactant to remain in contact with each other for the remainder of the period of storage.
The surfactant solution may simply be added to the emulsion but preferably, if facilities permit, it is mixed with the emulsion by low shear rate mixing, for example at a shear rate below 100 reciprocal seconds. Paddle mixers, which are sometim~s present in storage tanks, are suitable for this purpose.
It has been found that simply adding the surfactant to a deteriorating emulsion, or one with the potential for deterioration, reduces the rate of deterioration but phase separation may occur.
When the surfactant is mixed in, phase separation does not occur and the reduction effect is enhanced.
The emulsions may be monitored by carrying out regular determinations of oil droplet size.
Emulsion droplet size distribution data may be obtained by using a Coulter Counter, a Malvern Multisizer, a Galai CIS or other suitable instrument.
The method is particularly suitable for treating combustible emulsions intended for use as fuels derived from combustible oils, such as naturally occurring heavy crude oils. Such crude oils will generally have API gravities in the range 5 to 20 and include Wolf Lake and Lake Marguerite crude oil from Alberta, bitumen from the Canadian tar sands, Hewitt crude oil from Oklahoma and heavy oils from the Orinoco oil belt in Venezuela.
Combustible emulsions prepared from viscous products, by-products and waste products of the petroleum, petrochemical and chemical industries are also very suitable. Such materials include atmospheric and vacuum residues from the distillation of lighter crude oils and visbreaker residues.
Emulsions not intended for combustion which may be treated include paint emulsions, agrochemical emulsions, etc.
Suitable surfactants may be non-ionic, anionic or cationic, but are preferably non-ionic. Clearly they must be compatible with the surfactant originally used in preparing the emulsion. This is best achieved by using a member of the same family, if not the same surfactant.
z~
Preferred non-ionic surfactants are ethoxylated alkyl phenols, but ethoxylated secondary alcohols, ethoxyla-ted amines and ethoxylated sorbitan esters are also suitab]e.
The most preferred ethoxylated alkyl phenols are nonyl phenols containing 15 to 30 ethylene oxide units per molecule.
An ethoxylated nonyl phenol containing about 20 ethylene oxide units is very suitable.
Suitable anionic surfactants include alkyl, aryl and alkaryl sulphates, sulphonates and phosphates.
Suitable cationic surfactants include quaternary ammonium compounds and n-alkyl diamines and triamines in acidic form.
The surfactant is suitably added in the form of a fluid aqueous solution containing 10 - 30% by weight or 80 - 90% by weight surfactant, preferably about 25% by weight. Between 30% and 80% by weight surfactant, the solution is more viscous.
The guantity of surfactant added is suitably in amount 0.005 to 1~, preferably 0.1 to 0.7 %, by weight of the weight of the original emulsion.
The invention is illustrated with reference to the following Example.
Example An emulsion fuel containing approximately 30% by volume water and 70% by volume of a viscous crude oil from the Orinoco oil belt was kept in a storage tank over a period of several months.
After about six months it became apparent from droplet size analysis that the quality of the emulsion in the tank was deteriorating.
Experiments were carried out to investigate the effect of surfactant addition to samples of the emulsion.
The mean droplet size of the oil in the emulsion was 24.6,um at the beginning of the experiments.
The surfactant chosen was a nonylphenol ethyoxylate containing 20 ethylene oxide groups per molecule (NP20). It was used in the form of a 25% by weight solution in de-ionised water.
Three surfactant concentrations were investigated:
z~
6.25 x 10-3 % w/w NP20/Emulsion 6.25 x 10-2 % w/w NP20/Ernulsion 6.25 ~ 10~1 % w/w NP20/Emulsion The surfactant solution was added to the emulsion in the Eirs-t instance with no stirring and in the second instance with gentle manual stirring, at a shear rate below 100 reciproca]. seconds, thus simulating large tank mixers or recirculation systems.
200g samples of each of these blends were stored in an oven at 30C to simulate tank storage conditions. Control samples, containing no additional surfactant, were also placed in the oven.
Emulsion quality was monitored by measuring the mean droplet size at weekly intervals for five weeks and after nine weeks, and by measuring the results of shearing the samples at 20C and 70C aftar nine weeks using a Citenco mixer, operating under medium shear conditions of 5,500 rpm. The 200g samples were subdivided in order to perform the tests at the two temperatures.
Addition of Surfactant without Mixing The surfactant solution diffused downwardly through the samples which separated into a surfactant phase and an emulsion phase by the end of week one, the quantity of surfactant separated being similar to that added initially. The experiment was continued, however, to assess if the added surfactant still had any effect.
Table 1 shows the trends in mean droplet sizes throughout the test period. The control sample showed a steady increase in droplet size from 24.5~m initially, to 36.1,um at the end of week 9. Adding surfactant to the emulsion, with no mixing, slows the increase in droplet size, but does not arrest it completely. Some dependence on surfactant concentration was observed.
Results from the shearing tests are given in Table 2 for the three surfactant concentrations. It should be noted that the phase-separated surfactant was mixed into the emulsion before commencing the shearing test. The results obtained at 20C show increases in droplet size over the test period for the two lowest surfactant concentrations. At the highest surfactant concentration, the emulsion droplet size remained either the same or decreased 2~
slightly. The droplet size for the control sample (containing no additional surfactant) increased from 31.3 to 47.~3 ~m during testing.
Shearing results obtained at 70C show that the emulsions containing the two lowest concentrations of additional surfactant broke after mixing for 150 seconds. The sample containing 0.6%
additional surfactant showed a decrease in droplet size (32.6 to 10.4~m) over the test period. The control sarnple broke after 20 sec mixing at 70C.
Addition of Surfactant with Mixing Results are given in Table 3. Whilst it is evident from these results that mixing the surfactant into the emulsion is better than no mixing, there is still a gradual increase in droplet size over the test period. The highest surfactant addition again had the most positive effect.
Shearing results are sumrDarised in Table 4. At 20C, mean droplet size was not significantly affected at any of the surfactant concentrations investigated. At 70C, the sample containing 0.006 %
added surfactant showed a slight decrease in mean droplet size (30.5 to 25.2~m) over the test period.
The results lead to the following conclusions:
Addition of surfactant to an emulsion in the presence or absence of gentle mixing reduces the rate of emulsion deterioration.
Addition of surfactant to an emulsion with no mixing, results in sample phase separation into an emulsion and a surfactant layer within one week.
When the surfactant was gently mixed into the emulsion no phase separation occurred and the rate was reduced still further.
The results of shearing at both 20 and 70C is improved by the addition of more surfactant whether or not the surfactant is mixed in.
7 ~ L9~
TABLE 1: TRENDS IN MEAN DROPLET SIZE (~m), WEEKS 1 - 9 ADDITIONAL S~RFACTANT NOT MIXED IN
Surfactant Mean Droplet Size 5Concentration, % wt 0.0060.06 0.6 Control Week: 1 26.7 25.0 23.7 25.8 2 28.4 27.1 25.6 27.8 3 29.2 27.7 29.2 31.5 4 27.7 28.0 27.4 32.6 28.2 28.2 27.7 33.2 9 33.9 32.~ 32.3 36.1 Note: Emulsion Initial mean droplet size = 24.6~m ~ . .
8 ;~
TABLE 2: SI~EARING RES~LTS (~Im) ADDITIONAL SURFACTANT NOT MIXED IN
Mean Droplet Size Surfactant 0.0062 0.06% 0.6% Control Conc.
Mixing time 20 C 70 C 20 C 70 C 20 C 70 C 20 C 70 C
10 Seconds . _ .. _ 0 35.0 30.0 24.6 29.4 32.ô32.6 31.3 33.5 32.3 48.6 31.0 44.1 33.8 24.3 36.8 73.9 36.7 54.2 23.0 56.6 32.1 20.2 37.5 103.1 15 30 36.2 72.3 33.0 55.5 33.8 19.3 36.2 _____ 37.1 84.3 34.7 58.8 31.3 13.8 36.9 37.1 93.9 36.7 67.8 29.9 11.5 35.8 120 41.2 104.7 33.1 69.6 27.8 12.0 42.0 150 43.4 ____ 37.6 ____ 32.1 10.5 38.0 20 180 41 4 ~ 40.7 27.3 10.4 47.3 Note: Partitioned surfactant mixed into emulsion layer before commencing dynamic stability test.
("----" - sample inverted at this point.
9~
TABLE 3: TRENDS IN MEAN DROPLET SIZE (~m) WEEKS 1-9 ADDITIONAL SURFACTANT MIXED IN
Surfactant Mean Droplet Size 5Concentration, %wt 0.006 0.06 0.t Control Week: 1 23.9 20.1 20.2 25.8 2 28.4 27.1 25.6 27.8 3 30.5 24.3 24.2 31.5 4 31.3 27.1 25.2 32.6 30.0 28.1 27.9 33.2 9 34.5 30.1 28.0 36.1 __ Note: Emulsion Ini-tial mean droplet size = 24.6~m TABLE 4: SHEARING RESULTS (~m) ADDITIONAL SURFACTANT MIXED IN
Mean Droplet Size Surfactant 0.006% 0.06% 0.6% Control Conc.
Mixing time 20 C 70 C ZO C 70 C 20 C 70 C 2D C 70 C
Seconds O 33.0 36.5 33.0 31.2 28.6 30.5 31.3 33.5 32.8 65.5 32.1 42.3 29.5 31.8 36.8 73.9 34.3 74.2 33.4 51.5 32.3 27.4 37.5 103.1 1530 31.4 81.9 31.1 61.9 31.3 26.2 36.2 _____ 36.8 _____ 35.5 62.9 30.9 24.5 36.9 43.6 33.9 62.7 32.8 23.8 35.8 120 29.3 34.8 61.5 28.9 21.7 42.0 150 26.5 31.2 65.8 31.1 26.0 38.0 20180 33.7 3~.3 72.8 32.4 23.2 47.8 ("----" - sample inverted at this point.
This invention relates to a method for controlling the quality of an emulsion of a viscous oil in water, particularly an emulsion intended for combustion as a fuel, by arresting or reducing the rate at which the emulsion may deteriorate when subjected to prolonged standing, for example in storage tanks.
Emulsion fuels prepared from viscous oils have been previously described in the patent literature and elsewhere. For example, GB
974042 discloses a fuel composition comprising an oil-in-water emulsion of a petroleum oil having a viscosity above 40 SSF at 122F, the amount of water in said emulsion being such that said emulsion has a viscosity of less than 150 SSF at 77F and the said oil comprising at least 60 volume per cent of the emulsion.
The oils which are emulsified are generally viscous oils which in their non-emulsified state are too viscous to be pumped and require high preheat temperatures to be atomised successfully in combustion equipment.
Large deposits of viscous oils occur in several parts of the world, eg in Canada, USA, USSR and Venezuela. It is likely that emulsified fuels will become more commercially important in the future as the need to exploit the aforementioned deposits increases.
Such emulsified fuels are generally stable, some more so than others, depending on the method of production.
However, on prolonged storage, eg over a period of months or years, there may be a tendency for some emulsions to deteriorate somewhat, eg for the mean particle size of the droplets to increase, for the particle size distribution to widen and for the emulsions to become more susceptible to shear degradation, for example, in pumps, valves or at burner tips. This can give rise to problems in handling and combusting the emulsions.
GB 2220673-A discusses the problems of deteriorated, ultraheavy emulsion fuels and proposes methods for the regeneration of such deteriorated emulsions. If the deterioration is slight, a non-ionic surfactant is added to the deteriorated emulsion and the resulting mixture is subjected to high shear agitation. If the deterioration is more severe, an anionic surfactant is added, the mixture is sheared and a non-ionic surfactant is added. Alternatively, an anionic surfactant and a non-ionic surfactant are both added and the mixture is then sheared.
GB 2220673-A is concerned with a remedial treatment to restore the quality of an emulsion after significant deterioration has occurred.
We have now devised a preventative method for maintaining the quality of an emulsion of a viscous oil in water, which may have a tendency to deteriorate in storage, by reducing the rate at which it may deteriorate.
Thus according to the present invention there is provided a method for reducing the rate at which an emulsion of a viscous oil in water may deteriorate in storage by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added aqueous surfactant to remain in contact with each other.
In order to avoid the unnecessary use of surfactant, since the emulsion may be used before it has deteriorated or deteriorated to any significant extent, it may be advisable not to add the surfactant until signs of deterioration are noted.
Thus according to a further feature of the invention there is provided a method for reducing the rate at which an emulsion of a viscous oil in water may deteriorate in storage by monitoring the emulsion and, if signs of deterioration are noted, by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added aqueous surfactant to remain in contact with each other for the remainder of the period of storage.
The surfactant solution may simply be added to the emulsion but preferably, if facilities permit, it is mixed with the emulsion by low shear rate mixing, for example at a shear rate below 100 reciprocal seconds. Paddle mixers, which are sometim~s present in storage tanks, are suitable for this purpose.
It has been found that simply adding the surfactant to a deteriorating emulsion, or one with the potential for deterioration, reduces the rate of deterioration but phase separation may occur.
When the surfactant is mixed in, phase separation does not occur and the reduction effect is enhanced.
The emulsions may be monitored by carrying out regular determinations of oil droplet size.
Emulsion droplet size distribution data may be obtained by using a Coulter Counter, a Malvern Multisizer, a Galai CIS or other suitable instrument.
The method is particularly suitable for treating combustible emulsions intended for use as fuels derived from combustible oils, such as naturally occurring heavy crude oils. Such crude oils will generally have API gravities in the range 5 to 20 and include Wolf Lake and Lake Marguerite crude oil from Alberta, bitumen from the Canadian tar sands, Hewitt crude oil from Oklahoma and heavy oils from the Orinoco oil belt in Venezuela.
Combustible emulsions prepared from viscous products, by-products and waste products of the petroleum, petrochemical and chemical industries are also very suitable. Such materials include atmospheric and vacuum residues from the distillation of lighter crude oils and visbreaker residues.
Emulsions not intended for combustion which may be treated include paint emulsions, agrochemical emulsions, etc.
Suitable surfactants may be non-ionic, anionic or cationic, but are preferably non-ionic. Clearly they must be compatible with the surfactant originally used in preparing the emulsion. This is best achieved by using a member of the same family, if not the same surfactant.
z~
Preferred non-ionic surfactants are ethoxylated alkyl phenols, but ethoxylated secondary alcohols, ethoxyla-ted amines and ethoxylated sorbitan esters are also suitab]e.
The most preferred ethoxylated alkyl phenols are nonyl phenols containing 15 to 30 ethylene oxide units per molecule.
An ethoxylated nonyl phenol containing about 20 ethylene oxide units is very suitable.
Suitable anionic surfactants include alkyl, aryl and alkaryl sulphates, sulphonates and phosphates.
Suitable cationic surfactants include quaternary ammonium compounds and n-alkyl diamines and triamines in acidic form.
The surfactant is suitably added in the form of a fluid aqueous solution containing 10 - 30% by weight or 80 - 90% by weight surfactant, preferably about 25% by weight. Between 30% and 80% by weight surfactant, the solution is more viscous.
The guantity of surfactant added is suitably in amount 0.005 to 1~, preferably 0.1 to 0.7 %, by weight of the weight of the original emulsion.
The invention is illustrated with reference to the following Example.
Example An emulsion fuel containing approximately 30% by volume water and 70% by volume of a viscous crude oil from the Orinoco oil belt was kept in a storage tank over a period of several months.
After about six months it became apparent from droplet size analysis that the quality of the emulsion in the tank was deteriorating.
Experiments were carried out to investigate the effect of surfactant addition to samples of the emulsion.
The mean droplet size of the oil in the emulsion was 24.6,um at the beginning of the experiments.
The surfactant chosen was a nonylphenol ethyoxylate containing 20 ethylene oxide groups per molecule (NP20). It was used in the form of a 25% by weight solution in de-ionised water.
Three surfactant concentrations were investigated:
z~
6.25 x 10-3 % w/w NP20/Emulsion 6.25 x 10-2 % w/w NP20/Ernulsion 6.25 ~ 10~1 % w/w NP20/Emulsion The surfactant solution was added to the emulsion in the Eirs-t instance with no stirring and in the second instance with gentle manual stirring, at a shear rate below 100 reciproca]. seconds, thus simulating large tank mixers or recirculation systems.
200g samples of each of these blends were stored in an oven at 30C to simulate tank storage conditions. Control samples, containing no additional surfactant, were also placed in the oven.
Emulsion quality was monitored by measuring the mean droplet size at weekly intervals for five weeks and after nine weeks, and by measuring the results of shearing the samples at 20C and 70C aftar nine weeks using a Citenco mixer, operating under medium shear conditions of 5,500 rpm. The 200g samples were subdivided in order to perform the tests at the two temperatures.
Addition of Surfactant without Mixing The surfactant solution diffused downwardly through the samples which separated into a surfactant phase and an emulsion phase by the end of week one, the quantity of surfactant separated being similar to that added initially. The experiment was continued, however, to assess if the added surfactant still had any effect.
Table 1 shows the trends in mean droplet sizes throughout the test period. The control sample showed a steady increase in droplet size from 24.5~m initially, to 36.1,um at the end of week 9. Adding surfactant to the emulsion, with no mixing, slows the increase in droplet size, but does not arrest it completely. Some dependence on surfactant concentration was observed.
Results from the shearing tests are given in Table 2 for the three surfactant concentrations. It should be noted that the phase-separated surfactant was mixed into the emulsion before commencing the shearing test. The results obtained at 20C show increases in droplet size over the test period for the two lowest surfactant concentrations. At the highest surfactant concentration, the emulsion droplet size remained either the same or decreased 2~
slightly. The droplet size for the control sample (containing no additional surfactant) increased from 31.3 to 47.~3 ~m during testing.
Shearing results obtained at 70C show that the emulsions containing the two lowest concentrations of additional surfactant broke after mixing for 150 seconds. The sample containing 0.6%
additional surfactant showed a decrease in droplet size (32.6 to 10.4~m) over the test period. The control sarnple broke after 20 sec mixing at 70C.
Addition of Surfactant with Mixing Results are given in Table 3. Whilst it is evident from these results that mixing the surfactant into the emulsion is better than no mixing, there is still a gradual increase in droplet size over the test period. The highest surfactant addition again had the most positive effect.
Shearing results are sumrDarised in Table 4. At 20C, mean droplet size was not significantly affected at any of the surfactant concentrations investigated. At 70C, the sample containing 0.006 %
added surfactant showed a slight decrease in mean droplet size (30.5 to 25.2~m) over the test period.
The results lead to the following conclusions:
Addition of surfactant to an emulsion in the presence or absence of gentle mixing reduces the rate of emulsion deterioration.
Addition of surfactant to an emulsion with no mixing, results in sample phase separation into an emulsion and a surfactant layer within one week.
When the surfactant was gently mixed into the emulsion no phase separation occurred and the rate was reduced still further.
The results of shearing at both 20 and 70C is improved by the addition of more surfactant whether or not the surfactant is mixed in.
7 ~ L9~
TABLE 1: TRENDS IN MEAN DROPLET SIZE (~m), WEEKS 1 - 9 ADDITIONAL S~RFACTANT NOT MIXED IN
Surfactant Mean Droplet Size 5Concentration, % wt 0.0060.06 0.6 Control Week: 1 26.7 25.0 23.7 25.8 2 28.4 27.1 25.6 27.8 3 29.2 27.7 29.2 31.5 4 27.7 28.0 27.4 32.6 28.2 28.2 27.7 33.2 9 33.9 32.~ 32.3 36.1 Note: Emulsion Initial mean droplet size = 24.6~m ~ . .
8 ;~
TABLE 2: SI~EARING RES~LTS (~Im) ADDITIONAL SURFACTANT NOT MIXED IN
Mean Droplet Size Surfactant 0.0062 0.06% 0.6% Control Conc.
Mixing time 20 C 70 C 20 C 70 C 20 C 70 C 20 C 70 C
10 Seconds . _ .. _ 0 35.0 30.0 24.6 29.4 32.ô32.6 31.3 33.5 32.3 48.6 31.0 44.1 33.8 24.3 36.8 73.9 36.7 54.2 23.0 56.6 32.1 20.2 37.5 103.1 15 30 36.2 72.3 33.0 55.5 33.8 19.3 36.2 _____ 37.1 84.3 34.7 58.8 31.3 13.8 36.9 37.1 93.9 36.7 67.8 29.9 11.5 35.8 120 41.2 104.7 33.1 69.6 27.8 12.0 42.0 150 43.4 ____ 37.6 ____ 32.1 10.5 38.0 20 180 41 4 ~ 40.7 27.3 10.4 47.3 Note: Partitioned surfactant mixed into emulsion layer before commencing dynamic stability test.
("----" - sample inverted at this point.
9~
TABLE 3: TRENDS IN MEAN DROPLET SIZE (~m) WEEKS 1-9 ADDITIONAL SURFACTANT MIXED IN
Surfactant Mean Droplet Size 5Concentration, %wt 0.006 0.06 0.t Control Week: 1 23.9 20.1 20.2 25.8 2 28.4 27.1 25.6 27.8 3 30.5 24.3 24.2 31.5 4 31.3 27.1 25.2 32.6 30.0 28.1 27.9 33.2 9 34.5 30.1 28.0 36.1 __ Note: Emulsion Ini-tial mean droplet size = 24.6~m TABLE 4: SHEARING RESULTS (~m) ADDITIONAL SURFACTANT MIXED IN
Mean Droplet Size Surfactant 0.006% 0.06% 0.6% Control Conc.
Mixing time 20 C 70 C ZO C 70 C 20 C 70 C 2D C 70 C
Seconds O 33.0 36.5 33.0 31.2 28.6 30.5 31.3 33.5 32.8 65.5 32.1 42.3 29.5 31.8 36.8 73.9 34.3 74.2 33.4 51.5 32.3 27.4 37.5 103.1 1530 31.4 81.9 31.1 61.9 31.3 26.2 36.2 _____ 36.8 _____ 35.5 62.9 30.9 24.5 36.9 43.6 33.9 62.7 32.8 23.8 35.8 120 29.3 34.8 61.5 28.9 21.7 42.0 150 26.5 31.2 65.8 31.1 26.0 38.0 20180 33.7 3~.3 72.8 32.4 23.2 47.8 ("----" - sample inverted at this point.
Claims (12)
- 7569(2) The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-l. A method for reducing the rate at which an emulsion of a viscous oil in water may deteriorate in storage by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added aqueous surfactant to remain in contact with each other.
- 2. A method according to claim 1 for reducing the rate at which an emulsion of a viscous oil in water may deteriorate in storage by monitoring the emulsion and, if signs of deterioration are noted, by adding to the emulsion an aqueous solution of a surfactant and allowing the emulsion and added surfactant to remain in contact with each other for the remainder of the period of storage.
- 3. A method according claim 1 wherein the surfactant solution is simply added to the emulsion.
- 4. A method according to claim 1 wherein the surfactant is mixed with the emulsion by low shear rate mixing.
- 5. A method according to claim 4 wherein the shear rate of mixing is below 100 reciprocal seconds.
- 6. A method according to claim 2 wherein the emulsion is monitored by carrying out regular determinations of the oil droplet size.
- 7. A method according to claim 1 wherein the emulsion is a combustible emulsion derived from a combustible oil.
- 8. A method according to claim 7 wherein the oil is a heavy crude oil having an API gravity in the range 5° to 20°.
- 9. A method according to claim 7 wherein the oil is an atmospheric residue, a vacuum residue or a visbreaker residue.
- 10. A method according to claim 1 wherein the surfactant is a non-ionic surfactant.
- 11. A method according to claim 10 wherein the non-ionic surfactant is an ethoxylated alkyl phenol.
- 12. A method according to claim 11 wherein the ethoxylated alkyl phenol is an ethoxylated nonyl phenol containing 15-30 ethylene oxide units per molecule.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB909018358A GB9018358D0 (en) | 1990-08-21 | 1990-08-21 | Method for controlling the quality of an emulsion |
| GB9018358.3 | 1990-08-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2049404A1 true CA2049404A1 (en) | 1992-02-22 |
Family
ID=10681009
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002049404A Abandoned CA2049404A1 (en) | 1990-08-21 | 1991-08-20 | Method for controlling the quality of an emulsion |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0472329A3 (en) |
| JP (1) | JPH04250841A (en) |
| AU (1) | AU8243691A (en) |
| BR (1) | BR9103589A (en) |
| CA (1) | CA2049404A1 (en) |
| GB (1) | GB9018358D0 (en) |
| NO (1) | NO913268L (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1994003560A1 (en) * | 1992-08-05 | 1994-02-17 | Kao Corporation | Superheavy oil emulsion fuel and method for generating deteriorated oil-in-water superheavy oil emulsion fuel |
| EA016356B1 (en) * | 2011-06-29 | 2012-04-30 | Открытое Акционерное Общество "Казанский Жировой Комбинат" | Method of emulsion foodstuff quality control |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2589160B1 (en) * | 1985-10-29 | 1988-01-08 | Elf France | HEAVY HYDROCARBON COMPOSITION WITH LOWER VISCOSITY IN MULTIPLE EMULSION FORM, AND PROCESS FOR PREPARING THE SAME |
| JPH068424B2 (en) * | 1988-06-10 | 1994-02-02 | 花王株式会社 | Regeneration method of deteriorated O / W type super heavy oil emulsion fuel |
-
1990
- 1990-08-21 GB GB909018358A patent/GB9018358D0/en active Pending
-
1991
- 1991-08-08 EP EP19910307289 patent/EP0472329A3/en not_active Withdrawn
- 1991-08-14 AU AU82436/91A patent/AU8243691A/en not_active Abandoned
- 1991-08-20 NO NO91913268A patent/NO913268L/en unknown
- 1991-08-20 CA CA002049404A patent/CA2049404A1/en not_active Abandoned
- 1991-08-21 BR BR919103589A patent/BR9103589A/en unknown
- 1991-08-21 JP JP3208395A patent/JPH04250841A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0472329A3 (en) | 1992-07-29 |
| NO913268L (en) | 1992-02-24 |
| BR9103589A (en) | 1992-05-12 |
| GB9018358D0 (en) | 1990-10-03 |
| JPH04250841A (en) | 1992-09-07 |
| EP0472329A2 (en) | 1992-02-26 |
| AU8243691A (en) | 1992-02-27 |
| NO913268D0 (en) | 1991-08-20 |
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