MXPA06004801A - Heavy oil emulsion stabilizers containing saccharide based emulsion stabilizer - Google Patents

Abstract

Heavy oil emulsions, comprising decant oils and No. 6, No. 5 and No. 4 oils, and water are stabilized by adding certain saccharide-based esters. Preferably, the saccharide-based esters are naturally-occurring saccharide esters such as gallotannins, saponin, red gum, and the like.

Description

HEAVY OIL EMULSI N STABILIZERS CONTAINING A SACCHARID BASED EMULSION STABILIZER Related Request This application is based on and claims priority for the US Patent Application. provisional, co-pending, SN 60 / 514,885, filed October 28, 2003. BACKGROUND OF THE INVENTION The invention is directed to heavy fuel oils and particularly to environmentally benign compositions and methods for clean burning in the form of emulsions and giving the emulsions a long-term stability. Heavy fuel oils (Numbers 4, 5 and 6) are difficult to burn cleanly. Even with properly maintained equipment of the most recent design, substantial amounts of unburned carbon and other products of incomplete combustion are emitted as compared to inherently cleaner fuels such as gas or distilled oil. The fuels are typically sprayed to improve combustion but the droplets often burn incompletely. The result can be the production of soot, excessive smoke, carbon monoxide and other problems of poor combustion. One way to improve combustion is to decrease the size of the fuel droplets that enter the front of the flame, allowing a smaller droplet to burn out completely for the limited time allowed for combustion. The size of the drops can be reduced by improving the spray and introducing small droplets of water in the oil in the form of an emulsion. These droplets of water vaporize in the form of vapor while the droplet of oil begins to burn. The steam produced within the oil droplet fragments it into many smaller droplets. A typical oil droplet is in the order of 50-100 microns in diameter and it has been found that water droplets in the range of 2-10 microns are very effective and the total water contents of 5-15% by weight or approximately in the fuel, they provide enough energy to fragment most or almost all droplets and drastically reduce particulate emissions. The NOx emissions are usually reduced a little too due to the fact that the peak flame temperature is slightly reduced leading to a reduction in the thermal NOx formation. Emulsions have been frequently treated in the literature but there are many drawbacks in the systems useful for their production. The general process is well established and has been used commercially on a limited scale for many years, but needs improvement particularly in terms of providing additional stability and environmentally compatible chemical emulsification and / or stabilization chemicals. One problem is that chemical stabilizers are necessary to keep the water in suspension and prevent the formation of free water at the bottom of the storage tank if it is intended to store the emulsion before use or transport it to a secondary location for combustion. The equipment required to make a No. 6 oil emulsion is quite expensive and these emulsions are often made in a single location for distribution to the end-user sites located at a certain distance. Emulsion stabilizers currently in commercial use are generally surfactants designed to match the hydrophilic-lipophilic balance (HLB) requirements of NO oil. 6 to reduce the surface tension at the oil-water interface and form a stable emulsion. Both are (relatively) expensive and are subject to failure when the HLB requirement of the oil changes and because these droplets have almost no surface tension, they bind quickly and form a layer of water. Therefore, when a distillate fuel is mixed with a decanted fuel, usually of a very different composition and HLB, the result may be similar to that of deliberately adding a surfactant of a known wrong HLB to improve the separation of the emulsion as in the case of the use of a de-emulsifier to remove the small amounts of water that were emulsified in oil No. 6 during transport and handling, to remove it under controlled conditions before distribution. The additive, according to the invention, is more stable to variations in the formulation than can be expected when residual fuels are used. The HLB requirement changes drastically when the characteristics of the oil change. The most common comparison is between a "normal" No. 6 oil and a visco-reduced decanted oil. The user of heavy oils is often forced to buy what is available at a low cost and to make adjustments to enable efficient combustion without the improper creation of particles and other contamination. It would be desirable if such a user had emulsification additives and effective systems to allow variations in source and type of heavy oil. Normal No. 6 oil is largely aliphatic and has a density of 1.0 and less and is very viscous. Decanted oils have high aromatic contents and have densities above 1.0 and have a lower viscosity. They behave differently during emulsification and have different stabilization requirements. Sometimes the mixtures of the two types of oils are commercially bound and / or diluted with distillates to make a No. 5 or No. 4 oil, greatly complicating the outlook. Fuel oils No. 4 and 5 are substantially of lower viscosity, making it more difficult to keep the emulsions stable. Another practical problem is encountered when a fuel or similar distributor finds that the water is filtered into a heavy oil storage tank and needs to remove water from the bottom of the tank. Typically a distributor could burn such fuel to maintain the temperature in several heavy fuel storage tanks to facilitate handling but can not easily burn the contaminated water with fuel and can not conveniently dispose of the water because it is contaminated. It would be desirable if there were a way to dispose of water without contamination, ideally to be used to improve combustion by reducing the particles. The "tank water" below, is difficult to emulsify due to the presence of unknown and widely varied contaminants.The ability to effectively emulsify the water in the tank, in the fuel would solve the problem of elimination and would help reduce emissions of particles; however this can only be achieved where the emulsion is stable over a wide range of HLB values due to the variation of such for heavy oils. In addition to ensure proper emulsion formation, the tank water must be removed from the tank and sometimes there is a need to supplement the tank water. Therefore the system is highly complex, even so the emulsification must be reproducible and support wide variations in the HLB and mineral contents in the water. There is a need for a system and additives for the emulsification of aggregate water and / or the tank to serve two purposes: (1) the removal of a source of contaminated water that must otherwise be disposed of and (2) the reduction of emissions of particles normally visible when normal No. 6 oil is burned. SUMMARY OF THE INVENTION It is an object of the invention to provide compositions and emulsification systems to enable the emulsification of HLB heavy oils widely variable. It is another object of the invention to provide compositions and emulsification systems to allow emulsification of heavy oils with water from storage tanks. These and other objects are achieved by means of the invention which is based on the discovery that by adding certain esters of saccharides, in particular mono, di and / or oligosaccharide esters such as glucose, corn syrup or glucose polymers with acids aromatics containing hydroxyl functionalities help to stabilize the decanted oils and oils No. 6, No. 5 and No. 4, collectively referred to herein as heavy oils. Unlike the more typical surfactants for use as emulsifiers, the stabilizers of the invention are not based on fatty acid esters. They will preferably include functional esters with aromatic groups. For non-decanted oils, the addition of a surfactant could be beneficial but not essential, while in the case of decanted oils, such addition is usually detrimental to the stability of the emulsion produced. It has further been found that the addition of conventional non-saccharide surfactants does not increase the effectiveness of saccharide-based stabilizers and decanted oils, it can reduce the ability of the stabilizer to stabilize the emulsion. ? Next, other preferred aspects of the invention will be described. DETAILED DESCRIPTION OF THE INVENTION The invention is applicable to heavy fuel oils and particularly to environmentally benign compositions and methods for burning them cleanly in the form of emulsions and giving the emulsions a long-term stability. Among the heavy oils that can be used more effectively due to the invention, are the heavy fuel oils (Numbers 4, 5 and 6), which are difficult to burn cleanly, as well as the oils and mixtures decanted. Oil Number 6 is largely aliphatic and typically has a density of less than 1.0 and is very viscous. Decanted oils have high aromatic contents and have densities above 1.0 and have a lower but still high viscosity. They behave differently during emulsification and have different stabilization requirements. Sometimes the mixtures of the two types of oils are commercially bound and / or diluted with distillates to be included in a No. 5 or No. 4 oil, which have substantially lower viscosities. Preferred compositions of the invention will employ a stabilizer as defined herein, but do not need to contain a surfactant to enjoy the maximum applicability of the composition. Preferred stabilizers are naturally occurring saccharide esters such as gallotannins, tannic acid, liquidambar, saponin and similar saccharide esters. It is surprising that these are not normally considered active surface agents and the stabilization of the interfacial emulsion is unexpected. Unlike surfactants of more typical composition for use as emulsifiers, the stabilizers of the invention are not based on fatty acid esters. They will preferably include functional esters with aromatic groups. Also preferably, the stabilizers of the invention will be predominantly from natural sources, as compared to the synthesized surfactants and may be found in impure recovered form. The HLB values will preferably be consistent with the solubility in water, ex. , greater than about 10. Tannic acid is a preferred stabilizer of the invention and is also referred to as gallotanic acid and may be derived from the extraction of agalia with water, desirably with alcohol. Tannic acid, (galotanic acid) is a vegetable astringent product found in a wide variety of plants. Sources include oak bark, American spruce, chestnut and mangrove; the leaves of certain sumac; and Cecidia plants. Tannin is also present in tea, coffee and nuts. A tannic acid solution can be obtained from one of these natural sources by means of extraction with hot water. In particular, gallotanic acid can be obtained from the cecidia plant. It is commercially available as a solid. Tannin varies somewhat in composition, since it has the approximate empirical formula C76H52046. Tannic acid is a solid from colorless to pale yellow. It is believed to be a glucoside in which each of the five hydroxyl groups of the glucose molecule is esterified with a molecule of digalic acid. It is suitable in the form of a polysaccharide esterified with trihydroxybenzoic acid (Cg (OH) 3COOH). In its preferred form, tannic acid is available as a commercial material and may contain various impurities depending on the source and degree of purification. Possible stabilizers are also tannic acid derivatives, such as tanoform, prepared by the condensation of 2 moles of tannin with 1 mole of HCHO. Compositions like this and the equivalents are suitable as they are or with suitable solvents or vehicles which are insoluble in water but soluble in alcohols. Gallotannins and their equivalents are trade materials of slightly variable composition that are available from many suppliers in commercial forms used for other purposes. The cost of these materials varies considerably depending on the purity and other factors. We have been able to successfully utilize the less expensive grades of these materials as emulsion stabilizers indicating that normal commercial problems requiring high purity materials are not important to ensure the emulsion's stabilization capacity. The formulations of the invention are superior to many commercial emulsifiers and stabilizers because they are environmentally favorable because the organisms are naturally available in the soil to degrade them. Saponin and its derivatives will be collectively referred to herein, as saponins which in their preferred form is a polysaccharide esterified with a triterpene. The liquidambar is useful in any of its commercial forms. It is also known as eucalyptus gum and contains 45% kino-tannic acid, kino-red, glucoside, pyrocatechin, pyrocatechol. It is therefore very similar to tannic acid. In a preferred form, the liquidambar is available as an ester of a polysaccharide and hydroxybenzoic acid and other components in amounts that do not inhibit the functionality of the liquidambar as a stabilizer of the invention. Synthetic products are not completely regulated, since products such as Glucopon brand additives are effective: polysaccharide / C8-C? Ethers. These materials are artificial reaction products with short chain addition groups. Polyacrylic acid and acrylamide can also be present in these materials, but it is unknown how essential the acrylic components are, as an example of this is Glucopon 220UP, which is part of a small family of similar Henkel compounds that are not mixtures with Other anionic and non-ionic surfactants include glucopon 225, 225DK, 425, 425N, 425UP, 600, 600UP, 625, 625FE, and 625UP, all of which are ethers with a maximum chain length of C8-C? 2. Glucopon AV100, AV120 and LD45 The preferred stabilizers of the invention are soluble or dispersible in water and / or polar solvents such as alcohols and the like, of which the most preferred solvent is water based both on cost and on a hazardous product handling These materials may contain sugars, some of which may be prone to fermentation when contaminated with environmental bacteria. This can be avoided with the use of a biological stabilizer such as formaldehyde, glutaraldehyde and other similar agents, in effective concentrations, and j. , less than about 0.1%, eg. , approximately 0.05%. The additive according to the invention will preferably contain a composition such as an alcohol or glycol in an amount effective to prevent freezing or precipitation of the additive composition. In a preferred form, about 5 to 25% glycol is used, eg. , approximately 15% ethylene glycol. The emulsions prepared according to the invention have the following advantages, among others: • Improves combustion • Cleans the thermal transfer surfaces of the boiler • Reduces emissions and blows of soot • Provides long-term emulsion stability • Is completely fuel miscible • Reduces vapor spraying • Reduces deposits and corrosion of cold start The formulations of the invention, which have been formulated without the traditional surfactants, tend to provide the minimum surface tension reduction with good stability of the drop in emulsion. The larger interfacial tensions help avoid excessive shear reduction of the droplets before combustion during pumping and other manipulations. Excessively small water droplets (<2um) tend to have a minimal beneficial impact on the combustion process. Excessively large droplets (> 10-15 um) are rapidly reduced during the emulsification process. The additive according to the invention can be added to the fuel either by means of a direct injection in the front of the boiler through specially designed equipment or run through volume emulsification systems towards existing storage tanks. The treatment ratio is 1 gallon of additive according to the invention for each 1000 gallons of heavy fuel oil emulsified with from up to about 15% water. Preferably, the stabilizer includes tannic acid or a derivative in a concentration of from about 0.05 to about 0.5% of the weight of the final fuel emulsion. According to the process of the invention, a heavy oil is emulsified with water containing a stabilizer of the invention. Water can be from any source, including fresh water from lakes and rivers, tap water that has been processed and, very advantageously, tank water found in an oil storage tank. Preferably, the tank water is separated from the oil, mixed with the stabilizer of the invention and then emulsified with the oil. The oil may be one or more of those identified above and may be mixed with still other materials, including various materials and biologically derived oil residues. The following examples are presented to further explain and illustrate the invention by preparing various compositions according to the invention and comparing them with compositions that are not effective in achieving the objectives of the invention. All parts and percentages given below are based on the weight of the materials indicated in the state indicated in the process. Example 1 This example addresses the practical problem of a fuel or similar dispenser encountering water by filtering into a heavy oil storage tank and what can be done to make an emulsion using the bottom water of the tank. Typically a distributor could burn the fuel to maintain the temperature in several heavy fuel storage tanks to facilitate handling but can not easily burn it due to the presence of water in the tank and can not conveniently dispose of the water because it is contaminated . To solve this problem, it would be desirable to remove the water and dispose of it. It would also be desirable to improve the combustion to reduce the particles. The ability to effectively emulsify the water in the tank inside the fuel would solve the problem of elimination and help reduce particulate emissions. However, this can only be achieved when the emulsion is stable over a wide range of HLB values due to the variation of such heavy oils. In addition, to ensure the formation of a correct emulsion, the water in the tank must be removed from the tank and sometimes needs to be supplemented with the addition of tap water. Therefore the system is highly complex although the emulsification must be reproducible and support wide variations in the HLB and mineral contents in the water. The water referred to below as "tank water" is more difficult to emulsify than tap water due to the presence of unspecified contaminants. The emulsification of this water serves two purposes: (1) the removal of a contaminated water source that must otherwise be disposed of and (2) the reduction of normally visible particulate emissions when normal No. 6 oil is burned. The emulsions formed according to the invention serve both purposes. Others, the most typical situation, are ineffective and are not typically employed under the conditions described. The test data below were generated for emulsions prepared in the laboratory using the following test protocol: 1. The Additive Compositions are added to the solvent (water or butylcellosolve) in the amount established to make a test additive. 2. The test additive is added to the water to form an additive mixture to form the emulsion. 3. Preheat the oil to 150 ° F. 4. The water and additive mixture is added to the hot oil and mixed by hand with a stirring rod.

. The crude emulsion is homogenized in a manual homogenizer. Emulsions prepared for their stability were tested (ASTM D3707, Modified), as follows: 1. The prepared emulsion is placed in a tube of 25x150 mm (50 ml) with screw cap and cover. 2. The tube is placed in an oven at 85 ° C for 48 hours. The ASTM has estimated that 48 hours at 85 ° C is approximately equivalent to 3 months of storage under normal storage conditions. 3. Success or Failure is determined. Failure is indicated by the formation of large droplets of water, a layer of water or pockets of water on the bottom or sides of the tube. The following emulsions are prepared using 10% water from the indicated source to emulsify the fuel oil number 6 with the identified additives. As an example, 10% of water emulsions treated at 1: 1000 with the additive chemical required mixing 135 ml of hot oil with 15 ml (mixture of water + additive). The water additive mixture in this case consists of 1.0 ml of additive in 100 ml of water. The corresponding adjustments in these quantities were used for the compositions made in the other listed concentrations.

Additive Source Composition Rate Stability Additive Feed 48 Hours Water Additive Surfactant A Key 1/500 Commercial Fuel Commercial DJR 1000S Successful Surfactant Tank A 1/500 Commercial Fuel Commercial DJR 1000S Surfactant Failure B Tank 1/500 Commercial Fuel Commercial PEP99 Failure 20% Liquidambar in Butyl 1 Tank 1/500 Celosolve Success 2 Tank 1/500 20% tannin solution Success and Tank 1/750 Mix 50/50 Failure 2 Tank 1/1000 20% tannin solution Success 20% Glucopon 220UP of 3 Tank 1/500 Henkel in butyl cellosolve of Success (alkyl polysaccharide / acrylamide ether) Saponin 20% in water 1/500 tank (Quillaja saponaria molina) Success Example 2 This example addresses the practical problem of the emulsification of the decanted oil. A sample of oil No. 6 decanted (viscoreduced) was obtained and, from experience, it proved very difficult to form stable emulsions due to the low viscosity and the very high aromatic content. An emulsion was prepared using Additive A, see above, at 1: 1000 in 10% water. This emulsion failed in terms of hours at 60 ° C. When the same decanted oil was emulsified with Additive 2, the emulsion was successful for 96 hours under the same conditions. The above description is proposed to enable a person skilled in the art to practice the invention. It is not intended to detail all possible modifications and variations that will become apparent to the skilled worker after reading the description. It is intended, however, that such modifications and variations be included in the scope of the invention contemplated in the foregoing description and otherwise defined by the following claims. The claims are intended to cover the elements and steps indicated in any order or sequence that are effective to achieve the intended objectives for the invention, unless the context specifically indicates otherwise.

Claims (17)

1. CLAIMS 1. An improvement in a method for the preparation of heavy oil emulsions, which comprises: adding an ester based on saccharides to water to stabilize the emulsions of decanted oils and heavy oils.
2. 2. A method according to claim 1 wherein the saccharide-based ester comprises naturally occurring saccharide esters.
3. 3. A method according to claim 1 wherein the ester comprises galotanine.
4. 4. A method according to claim 1 wherein the ester comprises tannic acid.
5. 5. A method according to claim 1 wherein the ester comprises liquidambar.
6. 6. A method according to claim 1 wherein the ester comprises saponin.
7. 7. A method according to claim 1 wherein the polymers are not normally considered as surface active agents and the stabilization of the interfacial emulsion is unexpected.
8. 8. A method according to claim 1 wherein the oil is a decanted oil and is free of added surfactant.
9. 9. A method according to claim 1 wherein the oil is a non-oil and the emulsion may contain an added surfactant.
10. 10. A method according to claim 1 wherein the oil is an undecanted oil and the emulsion is free of added surfactant.
11. 11. A method according to claim 1 wherein the emulsion comprises up to about 15% water.
12. 12. A method according to claim 1 wherein the emulsion comprises from 5 to 10% water.
13. 13. A method according to claim 1 wherein the stabilizer comprises tannic acid or a derivative at a concentration of from about 0.05% to about 0.5% of the weight of the composition.
14. 14. A composition according to claim 1.
15. 15. A concentrate for preparing a composition according to claim 1 by means of the addition to the heavy oil with or without added water.
16. 16. A method according to claim 1 which includes the additional step of removing water from a heavy oil storage tank and using that water for emulsification with heavy oil and stabilizer.
17. 17. A method according to claim 1 including the additional step of mixing the water and heavy oil under sufficient cutting conditions to emulsify the water in the oil.