A fuel additive package and method of making and using the same

Abstract

This invention discloses a fuel additive package, its preparation method, and its application, belonging to the field of aerospace engine and fuel technology. The fuel additive comprises an aqueous hydroxylamine solution, palmitic acid-terminated hyperbranched polyester, and polyoxyethylene sorbitan laurate. This invention uses a hyperbranched polymer with a "core-shell" structure as a surfactant. The polymer core is rich in hydrophilic functional groups, while the outer shell consists of lipophilic segments. Its internal multi-branched flexible structure can form a cohesive energy density gradient buffer zone at the interface. This structure allows the polymer to adaptively adjust its interaction with different solvents, achieving efficient solvation of hydrophilic substances even in systems with mismatched cohesive energy densities. During emulsification, this hyperbranched polymer can significantly reduce interfacial energy, forming nanoscale droplets much smaller than conventional emulsions, thereby constructing a uniform and long-term stable pseudo-homogeneous fuel system.

Description

Technical Field

[0001] This invention belongs to the field of aerospace engine and fuel technology, and particularly relates to a fuel additive package, its preparation method and application. Background Technology

[0002] In high-speed air-breathing engines, liquid fuel must simultaneously perform the dual tasks of heat exchange and cooling, as well as combustion and propulsion. To meet requirements such as calorific value (energy density) and heat sink capacity (heat absorption capacity), coal-based hydrocarbon fuels are typically used. During operation, the hydrocarbon fuel flows as a coolant through the heat exchange channels on the engine surface, participating in the active cooling process of the aircraft and reducing the risk of engine overheating. However, during this heat absorption process, hydrocarbon fuel is susceptible to thermal cracking, resulting in coking. Coking has low thermal conductivity and can cause blockages, jeopardizing the stable operation of the engine. The coking problem is one of the important factors limiting the further development of engine technology.

[0003] Currently, there are three main technical approaches to suppress coking in hydrocarbon fuels: adding anti-coking agents, fuel purification treatment, and heat exchanger surface passivation. However, each method has significant technical limitations: First, although deep fuel purification processes can effectively reduce coking precursors in feedstocks, their high preparation costs severely restrict large-scale industrial applications; second, heat exchanger surface passivation technology inhibits carbon deposit adhesion through material modification, but the complex surface treatment process places stringent requirements on equipment processing precision and operating environment, significantly increasing the difficulty of engineering implementation and maintenance costs.

[0004] More importantly, existing anti-coking additive technologies are still insufficient to meet the special requirements of air-breathing engines. Currently, commonly used anti-coking agents are mainly divided into two categories: one is sulfur / phosphorus compounds, represented by dimethyl disulfide and dimethyl phosphate. Although they can inhibit coking by destroying the coke structure, they have poor storage stability and are prone to generating harmful small molecules such as SO2 during high-temperature pyrolysis, polluting gaseous products. They are mainly limited to industrial olefin production and are not suitable for aerospace propulsion fields with extremely high emission and stability requirements. The other category is hydrogen donors, represented by tetrahydroquinoline and methanol. They block the coking chain reaction by releasing hydrogen free radicals (H·) with reducing activity. However, this process is often accompanied by excessive inhibition of fuel pyrolysis reaction, resulting in a significant decrease in the fuel's chemical endothermic capacity (heat sink), which in turn weakens the active cooling efficiency of the aircraft. This contradicts the dual requirements of high-performance air-breathing engines for fuel with "high heat sink and low coking".

[0005] In summary, existing coking inhibition technologies have shortcomings in terms of safety, economy, and thermal performance matching, making it difficult to meet the practical requirements of air-breathing engines for hydrocarbon fuels. Therefore, developing a new additive technology that can efficiently inhibit coking without harmful byproducts has become a key breakthrough for promoting the engineering application of endothermic hydrocarbon fuel systems. Summary of the Invention

[0006] To address the issue that existing fuels do not meet application requirements in terms of heat sink and coking, this invention proposes a fuel additive package, its preparation method, and its application. The fuel additive package of this invention can prepare fuel compositions for air-breathing engines.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a fuel additive package composed of the following raw materials: an aqueous solution of hydroxylamine and a surfactant; The mass ratio of the hydroxylamine aqueous solution to the surfactant is 1:1; The hydroxylamine aqueous solution contains 50% hydroxylamine by mass. The surfactant is composed of palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan laurate (Tween-20); The mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene sorbitan laurate is 1:1.

[0008] This invention involves uniformly mixing hydroxylamine aqueous solution, polyoxyethylene sorbitan laurate, and palmitic acid-terminated hyperbranched polyester to form a fuel additive package. In this system, the hydroxylamine aqueous solution functions as a coking inhibitor, while the polyoxyethylene sorbitan laurate and palmitic acid-terminated hyperbranched polyester function as surfactants.

[0009] This fuel additive package can form a stable pseudo-homogeneous system with aviation kerosene (referring to a system that is uniform in appearance, stable over a long period of time, and has a nanoscale droplet dispersion phase at the microscopic level), with aviation kerosene serving as the base fuel.

[0010] An exemplary method for preparing the palmitic acid-terminated hyperbranched polyester includes the following steps: 1 g of trimethylolpropane, 9 g of 2,2-dimethylolpropionic acid, and 0.05 wt% of p-toluenesulfonic acid are added to a dry three-necked flask. Stirring is started under nitrogen protection, and a transesterification reaction is carried out at 140 °C for 2 h, using nitrogen to remove the generated water vapor. When the melt stops bubbling violently, the nitrogen device is removed, a vacuum pump and condenser are connected, and the three-necked flask is sealed. The temperature of the oil bath is increased to 160 °C, and a polycondensation reaction is carried out for 2 h. During the reaction, the melt viscosity gradually increases. When the melt stops bubbling, the pressure is reduced, and after cooling, a transparent amber-colored hyperbranched polyester product is obtained. The crude product is dissolved in acetone and precipitated with n-hexane. The precipitate is dried in a vacuum oven to obtain a powdered purified hyperbranched polyester with a yield of 87%. 2.2 g of palmitic acid and 0.1 g of p-toluenesulfonic acid catalyst were added to a three-necked flask containing 1 g of hyperbranched polyester. After purging with N2 at 140 °C for 1 h, the temperature was increased to 160 °C and vacuum was applied until no bubbles emerged, yielding a brownish-yellow, waxy modified hyperbranched polyester crude product. This crude product was then dissolved in chloroform, and palmitic acid was removed by precipitation with excess methanol. After drying, palmitic acid-terminated hyperbranched polyester was obtained.

[0011] The present invention also provides a method for preparing the above-mentioned fuel additive package, comprising the following steps: adding palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan laurate into an aqueous solution of hydroxylamine, and stirring until the mixture forms a uniform, viscous paste to obtain the fuel additive package.

[0012] An exemplary method for preparing a fuel additive package includes the following steps: (1) Weigh 50 parts by weight of hydroxylamine aqueous solution (hydroxylamine mass fraction is 50%), 25 parts by weight of palmitic acid-terminated hyperbranched polyester and 25 parts by weight of polyoxyethylene dehydrated sorbitan laurate. (2) Add the weighed palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan laurate to an aqueous solution of hydroxylamine; (3) Use a high-speed homogenizer to stir (10000 r / min) for 10 minutes until the mixture forms a uniform, viscous paste.

[0013] The present invention also provides the use of the above-mentioned fuel additive package in the preparation of alternative compositions for hydrocarbon fuels for air-breathing engines and / or in air-breathing engines.

[0014] The present invention also provides a fuel composition for an air-breathing engine, wherein the raw materials contain the above-mentioned fuel additive package as a hydrocarbon fuel substitute composition to replace part of the hydrocarbon fuel; the mass ratio of the substitution is 5-40%.

[0015] The fuel composition for an air-breathing engine of the present invention also contains aviation kerosene.

[0016] The technical concept of this invention is as follows: (1) In terms of inhibiting coking and improving heat sink: Conventional coking inhibitors mainly achieve coking inhibition by destroying the coke structure or inhibiting fuel pyrolysis. Since they cannot block the intermediate pyrolysis process, their effect at high temperatures is limited, and they also have problems such as generating harmful by-products and reducing the usable heat sink of fuel. In this invention, hydroxylamine can release free radicals such as ·OH and ·NH2. These free radicals can efficiently capture coking precursor free radicals with aromatic structures, and block their further polymerization and aromatization pathways by forming conjugated stable addition products, thereby significantly inhibiting the formation and growth of coke. At the same time, water molecules in the hydroxylamine aqueous solution play a dual role: on the one hand, at high temperatures, they consume coke through the water-gas reaction C+H2O→CO+H2, directly converting the generated coke; on the other hand, water, as a polar diluent, can effectively reduce the concentration of local pyrolysis products and physically scour the coke layer already attached to the channel wall, further delaying coke deposition. Based on the above mechanism, this invention selects hydroxylamine aqueous solution as the coking inhibitory functional component, taking into account both the inhibitory effectiveness and storage safety. In this mechanism, the inhibitor neither affects the pyrolysis of the fuel itself nor produces harmful byproducts containing S and P. Instead, it "de-harms" the free radicals that are prone to aggravating coking, thereby effectively inhibiting coking.

[0017] (2) Regarding the formation of stable fuels: Hydrocarbon fuels are incompatible with hydroxylamine aqueous solutions, and the stability of this system is highly dependent on the hydrophilic-lipophilic balance of the surfactant used. According to the Flory-Huggins theory, surfactants can effectively reduce interfacial tension and achieve full solubilization of the dispersed phase only when the cohesive energy densities of the oil phase and the water phase match the lipophilic and hydrophilic segments of the surfactant molecules, respectively. Therefore, for continuous phases with different cohesive energy densities and composition ratios, it is usually necessary to specifically match surfactants with specific molecular structures and hydrophilic-lipophilic balance values. Conventional surfactants, such as CTAB (hexadecyltrimethylammonium bromide) and Span 80 (sorbitan oleate), have relatively simple structures and cannot achieve dynamic adaptation to the oil-water interface, and cannot play a good stabilizing role in complex fuel systems (especially multi-component systems with large differences in cohesive energy densities such as hydroxylamine + hydrocarbon fuel + water). To address the aforementioned problems, this invention employs a hyperbranched polymer with a "core-shell" structure (i.e., palmitic acid-terminated hyperbranched polyester) as a surfactant. This polymer has a core rich in hydrophilic functional groups, while its outer shell consists of lipophilic segments. Its internal multi-branched flexible structure can form a cohesive energy density gradient buffer zone at the interface. This structure allows the polymer to adaptively regulate its interaction with different solvents, achieving efficient solvation of hydrophilic substances even in systems with mismatched cohesive energy densities. During emulsification, this hyperbranched polymer significantly reduces interfacial energy, forming nanoscale droplets much smaller than conventional emulsions, thereby constructing a uniform, long-term stable pseudo-homogeneous fuel system.

[0018] The present invention also provides a method for preparing the above-mentioned fuel composition for an air-breathing engine, comprising the following steps: Aviation kerosene is mixed with the fuel additive package and stirred evenly to obtain the fuel composition for air-breathing engines. The fuel additive package accounts for 5-40% of the mass of the fuel composition for air-breathing engines. or: (1) Preparation of aqueous base liquid: 1.25~10 parts (by mass, the same below) of polyoxyethylene dehydrated sorbitan laurate was added to an aqueous solution of hydroxylamine and stirred at 500 r / min for 10 minutes at room temperature to obtain a uniform and transparent base liquid A; (2) Preparation of oil phase base liquid: 1.25~10 parts of palmitic acid-terminated hyperbranched polyester and 5~40 parts of aviation kerosene are mixed and stirred at 500 r / min for 10 minutes at room temperature to obtain clear base liquid B; (3) Mixing and homogenization: Add base liquid A to base liquid B and stir for 15 minutes at a speed of 8000 r / min using a high-speed homogenizer to obtain a milky white homogeneous emulsion C; (4) Preparation of finished fuel: Add aviation kerosene to emulsion C to make the total mass 100 parts, and continue to homogenize at 8000 r / min for 10 minutes until the system is transformed into a uniform and stable milky white semi-transparent liquid, which is the fuel composition for air-breathing engines. It is a substitute for endothermic hydrocarbon fuel composition. The mass ratio of the total mass of the hydroxylamine aqueous solution, palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate is 1:1; the mass fraction of hydroxylamine in the hydroxylamine aqueous solution is 50%; the mass ratio of the palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate is 1:1, and the mass percentage of the hydroxylamine aqueous solution, palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate in the fuel composition for air-breathing engines is 5~40%.

[0019] The present invention also provides the application of the above-described fuel composition for air-breathing engines in air-breathing engines.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The present invention utilizes the cohesive energy density gradient buffer formed by hyperbranched polymer surfactants to achieve stable dispersion of water-soluble coking inhibitors in hydrocarbon fuels, forming a uniform system, and the engine does not need to add an additional feed channel. (2) The present invention utilizes the free radicals such as ·OH and ·NH2 released by hydroxylamine to effectively inhibit the growth of aromatic coking precursors, and the coking of the composition is significantly reduced compared with the basic fuel; (3) The combustion products of this coking inhibitor are mainly H2O, CO2 and N2, and it will not produce harmful byproducts containing elements such as S and P. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 Appearance images of the composition fuels prepared in Examples 1, 3, 4, and 7; Figure 2 The results of cryo-transmission electron microscopy of the alternative endothermic hydrocarbon fuel composition prepared in Example 4; Figure 3 The results of centrifugal stability tests are for the alternative endothermic hydrocarbon fuel compositions prepared in Examples 3 to 6. Figure 4 The centrifugal stability test results of four control samples prepared by directly adding hydroxylamine aqueous solution (hydroxylamine content of 50%) to RP-10 kerosene at mass ratios of 2.5%, 5%, 7.5% and 10% were obtained. Figure 5 The results are the centrifugal stability test results of the fuels in Comparative Examples 1 to 8. Figure 6 This is a temperature and pressure monitoring graph of the RP-10 kerosene system during operation. Figure 7 Temperature and pressure monitoring graphs during the operation of the alternative endothermic hydrocarbon fuel composition prepared in Example 1; Figure 8 Temperature and pressure monitoring graphs during the operation of the fuel composition prepared in Comparative Example 9; Figure 9 Temperature and pressure monitoring graphs during the operation of the fuel composition prepared for Comparative Example 10; Figure 10 This is a schematic diagram of the structure of the hyperbranched polyester used in this invention. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] Embodiments of the present invention provide a fuel additive package comprising the following raw materials: an aqueous solution of hydroxylamine and a surfactant; The mass ratio of hydroxylamine aqueous solution to surfactant is 1:1; The hydroxylamine in the aqueous solution has a hydroxylamine mass fraction of 50%. The surfactant is composed of palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan laurate; The mass ratio of palmitic acid-capped hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate is 1:1.

[0028] In the following embodiments of the present invention, the preparation method of palmitic acid-terminated hyperbranched polyester is as follows: 1 g of trimethylolpropane, 9 g of 2,2-dimethylolpropionic acid, and 0.05 wt% of p-toluenesulfonic acid are added to a dry three-necked flask. Stirring is started under nitrogen protection, and a transesterification reaction is carried out at 140 °C for 2 h, using nitrogen to remove the generated water vapor. When the melt stops bubbling violently, the nitrogen device is removed, a vacuum pump and condenser are connected, and the three-necked flask is sealed. The temperature of the oil bath is increased to 160 °C, and a polycondensation reaction is carried out for 2 h. During the reaction, the melt viscosity gradually increases. When the melt stops bubbling, the pressure reduction is stopped, and after cooling, a transparent amber-colored hyperbranched polyester product is obtained. The crude product is dissolved in acetone and precipitated with n-hexane. The precipitate is dried in a vacuum oven to obtain a powdered purified hyperbranched polyester with a yield of 87%. 2.2 g of palmitic acid and 0.1 g of p-toluenesulfonic acid catalyst were added to a three-necked flask containing 1 g of hyperbranched polyester. After purging with N2 at 140 °C for 1 h, the temperature was increased to 160 °C and vacuum was applied until no bubbles emerged, yielding a brownish-yellow, waxy modified hyperbranched polyester crude product. This crude product was then dissolved in chloroform, and palmitic acid was removed by precipitation with excess methanol. After drying, palmitic acid-terminated hyperbranched polyester was obtained.

[0029] The present invention also provides a method for preparing the above-mentioned fuel additive package, comprising the following steps: adding palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate to an aqueous solution of hydroxylamine, and stirring until the mixture forms a uniform, viscous paste to obtain the fuel additive package.

[0030] An exemplary method for preparing a fuel additive package includes the following steps: (1) Weigh 50 parts by weight of hydroxylamine aqueous solution (hydroxylamine mass fraction is 50%), 25 parts by weight of palmitic acid-terminated hyperbranched polyester and 25 parts by weight of polyoxyethylene dehydrated sorbitan laurate. (2) Add the weighed palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan laurate to an aqueous solution of hydroxylamine; (3) Use a high-speed homogenizer to stir (10000 r / min) for 10 minutes until the mixture forms a uniform, viscous paste.

[0031] Embodiments of the present invention also provide the use of the above-described fuel additive package in the preparation of fuel compositions for air-breathing engines and / or air-breathing engines.

[0032] Embodiments of the present invention also provide a fuel composition for an air-breathing engine, wherein the raw materials contain the above-mentioned fuel additive package as a hydrocarbon fuel substitute composition to replace a portion of the hydrocarbon fuel; the substitution mass ratio is 5-40%.

[0033] An embodiment of the present invention also provides a method for preparing the above-mentioned fuel composition for an air-breathing engine, comprising the following steps: Aviation kerosene is mixed with a fuel additive package and stirred evenly to obtain a fuel composition for air-breathing engines. The fuel additive package accounts for 5-40% of the mass of the fuel composition for air-breathing engines. or: (1) Preparation of aqueous base liquid: Add 1.25~10 parts (mass parts, the same below) of polyoxyethylene dehydrated sorbitan laurate to 2.5~20 parts of hydroxylamine aqueous solution (hydroxylamine mass fraction is 50%), stir at 500 r / min for 10 minutes at room temperature to obtain a uniform and transparent base liquid A; (2) Preparation of oil phase base liquid: 1.25~10 parts of palmitic acid-terminated hyperbranched polyester and 30 parts of aviation kerosene are mixed and stirred at 500 r / min for 10 minutes at room temperature to obtain clear base liquid B; (3) Mixing and homogenization: Add base liquid A to base liquid B and stir for 15 minutes at a speed of 8000 r / min using a high-speed homogenizer to obtain a milky white homogeneous emulsion C; (4) Preparation of finished fuel: Add aviation kerosene to emulsion C to make the total mass 100 parts, and continue to homogenize at 8000 r / min for 10 minutes until the system is transformed into a uniform and stable milky white semi-transparent liquid, which is the fuel composition for air-breathing engines, which is a substitute for heat-absorbing hydrocarbon fuel composition.

[0034] In a preferred embodiment of the present invention, the aviation kerosene is selected from RP-10 kerosene or RP-3 kerosene. RP-10 kerosene refers to high-density synthetic hydrocarbons conforming to GJB 10753-2022 standard, and RP-3 kerosene refers to aviation kerosene conforming to GB 6537-2025 standard.

[0035] The present invention also provides the application of the above-described fuel composition for air-breathing engines in air-breathing engines.

[0036] Patent CN120248950A discloses an endothermic hydrocarbon fuel additive using hydrazine hydrate as a coking inhibitor. However, this patent only describes the basic usage of hydrazine hydrate as a coking inhibitor and does not address the stability and safety issues that exist in practical applications. As a strong reducing agent, hydrazine hydrate is easily oxidized during storage and has poor stability. It usually needs to be prepared and added on-site, making it difficult to use as a long-term stored, storable fuel composition. This is fundamentally different from the stabilized, transportable fuel system involved in this patent. In addition, hydrazine hydrate is a strictly controlled hazardous chemical, and its storage, transportation, management, and production processes pose high safety risks and cost pressures, further limiting its feasibility in large-scale engineering applications.

[0037] Patent CN112961715A discloses a method for preparing a novel hydrocarbon fuel coking inhibitor and its application. Using glycerol, water, and terminally hydroxyl hyperbranched polyester, the release of hydroxyl radicals can effectively inhibit fuel cracking. Patents CN113025379A and CN110041965A respectively disclose a series of composite coking inhibitors containing elements such as S and P, and a series of sulfur-containing SO2 and H2S coking inhibitors. Using compounds containing elements such as S and P, or sulfur-containing gaseous compounds, can effectively inhibit coking by releasing mercapto and phosphine radicals.

[0038] However, the small molecule compounds formed by the aforementioned elements such as O, S, and P are highly polar, and none of the coking inhibitors mentioned above are miscible with hydrocarbon fuels. When applying these inventions, a separate sample introduction system must be installed at the inlet of the engine's high-temperature fuel pyrolysis device to ensure mixing of the fuel and additives. Furthermore, during aircraft maneuvers, the heterogeneous system may separate under overload conditions (acceleration ~50×G), affecting stable operation. Compounds such as water may also raise the freezing point of the fuel, affecting its anti-icing performance. Therefore, simultaneously addressing the solubility, overload stability, and high freezing point issues of these coking inhibitors in hydrocarbon fuels remains a significant research challenge in this field.

[0039] This invention involves uniformly mixing hydroxylamine aqueous solution, polyoxyethylene sorbitan laurate, palmitic acid-terminated hyperbranched polyester, and aviation kerosene to form a stable pseudo-homogeneous system. In this system, the hydroxylamine aqueous solution inhibits coking, while the polyoxyethylene sorbitan laurate and palmitic acid-terminated hyperbranched polyester act as surfactants, and aviation kerosene serves as the base fuel. This invention employs a hyperbranched polymer with a "core-shell" structure as the surfactant. The polymer's core is rich in hydrophilic functional groups, while the outer shell consists of lipophilic segments. Its internal multi-branched flexible structure can form a cohesive energy density gradient buffer zone at the interface. This structure allows the polymer to adaptively adjust its interaction with different solvents, achieving efficient solvation of hydrophilic substances even in systems with mismatched cohesive energy densities. During emulsification, this hyperbranched polymer significantly reduces interfacial energy, forming nanoscale droplets much smaller than conventional emulsions, thus constructing a uniform and long-term stable pseudo-homogeneous fuel system.

[0040] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0041] All raw materials used in the embodiments of the present invention were obtained through commercial purchase.

[0042] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0043] The technical solution of the present invention will be further illustrated by the following embodiments.

[0044] Example 1 This embodiment provides a method for preparing a fuel composition for air-breathing engines (as an alternative to endothermic hydrocarbon fuel compositions) by directly mixing the components. The composition is obtained through the steps of preparing an aqueous base liquid, preparing an oil-based base liquid, mixing and homogenizing, and formulating the finished fuel. The specific steps are as follows: (1) Preparation of aqueous base liquid: 2.5 parts (by mass, the same below) of polyoxyethylene sorbitan laurate were added to 5 parts of hydroxylamine aqueous solution (hydroxylamine mass fraction of 50%) and stirred at 500 r / min for 10 minutes at room temperature to obtain a uniform and transparent base liquid A; (2) Preparation of oil phase base liquid: 2.5 parts of palmitic acid-terminated hyperbranched polyester and 10 parts of RP-10 kerosene were mixed and stirred at 500 r / min for 10 minutes at room temperature to obtain clear base liquid B; (3) Mixing and homogenization: Add base liquid A to base liquid B and stir for 15 minutes at a speed of 8000 r / min using a high-speed homogenizer to obtain a milky white homogeneous emulsion C; (4) Preparation of finished fuel: Add 80 parts of RP-10 kerosene to emulsion C and continue to homogenize at 8000 r / min for 10 minutes until the system is transformed into a uniform and stable milky white semi-transparent liquid, thus obtaining the alternative endothermic hydrocarbon fuel composition.

[0045] In this embodiment, the total mass ratio of the hydroxylamine aqueous solution to the two surfactants (palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate) is 1:1, and the mass ratio between the two surfactants is also 1:1. The total mass of the three (i.e., the hydroxylamine aqueous solution and the two surfactants) accounts for 10% of the total mass of the final fuel composition, with the remainder being RP-10 kerosene.

[0046] Example 2 This embodiment provides a method for preparing a fuel additive package that can be stored for a long time, the steps of which are as follows: (1) Weigh 50 parts by weight of hydroxylamine aqueous solution (hydroxylamine mass fraction is 50%), 25 parts by weight of palmitic acid-terminated hyperbranched polyester and 25 parts by weight of polyoxyethylene dehydrated sorbitan laurate. (2) Add the weighed palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan laurate to an aqueous solution of hydroxylamine; (3) Use a high-speed homogenizer to stir (10000 r / min) for 10 minutes until the mixture forms a uniform, viscous paste; (4) Seal the obtained paste in a container to obtain a fuel additive package, which can be stored at room temperature away from light.

[0047] In this embodiment, the ratio of hydroxylamine aqueous solution to (palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate) is 1:1 (mass ratio), and the mass ratio of the two surfactants (i.e., palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate) is 1:1.

[0048] Example 3 This embodiment provides a method for preparing a fuel composition for an air-breathing engine, the steps of which are as follows: (1) Take 100 parts by weight of the fuel additive package prepared by the method of Example 2; (2) Add the above fuel additive package together with 900 parts by weight of RP-10 kerosene into a mixing container; (3) Use a high-speed homogenizer to stir at 10,000 r / min for 15 minutes until the whole system is transformed into a uniform, milky white, semi-transparent liquid. The resulting liquid is the fuel composition for air-breathing engines, which can also be called a replacement heat-absorbing hydrocarbon fuel composition.

[0049] In this embodiment, the total mass of the fuel additive package (i.e., hydroxylamine aqueous solution, palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate) accounts for 10% of the substitute endothermic hydrocarbon fuel composition.

[0050] This embodiment demonstrates how to rapidly prepare a fuel composition with performance consistent with the direct mixing method using the fuel additive package prepared in Example 2.

[0051] Examples 4 to 6 Following the method of Example 1, three sets of alternative endothermic hydrocarbon fuel composition samples were prepared. In each sample, the total mass ratio of hydroxylamine aqueous solution (hydroxylamine content of 50%), palmitic acid-terminated hyperbranched polyester, and polyoxyethylene sorbitan laurate to the total mass of the composition was 5% (Example 4), 15% (Example 5), and 20% (Example 6), respectively. The total mass ratio of hydroxylamine aqueous solution to the two surfactants was 1:1, and the mass ratio between the two surfactants was also 1:1.

[0052] The appearance of the alternative endothermic hydrocarbon fuel compositions prepared in Examples 1 and 4 is shown in the figure. Figure 1 It can be seen that the sample has a uniform appearance and is semi-transparent.

[0053] The cryo-transmission electron microscopy results of the alternative endothermic hydrocarbon fuel composition prepared in Example 4 are as follows: Figure 2 As shown, in the alternative endothermic hydrocarbon fuel composition, the dispersed phase is uniformly dispersed as spherical droplets with a size of less than 100 nm.

[0054] Example 7 This embodiment provides a method for preparing a fuel composition for an air-breathing engine, which is the same as in Embodiment 3, except that the fuel additive package accounts for 5% of the total mass of the hydrocarbon fuel substitute composition for an air-breathing engine.

[0055] The appearance of the alternative endothermic hydrocarbon fuel compositions prepared in Examples 3 and 7 is shown in the figure. Figure 1 It can be seen that its appearance is also uniform and semi-transparent.

[0056] Figure 1 The results showed that the fuels obtained by the two preparation processes were identical in composition, appearance and microstructure, indicating that the process of pre-preparing additive packages is equivalent to the direct mixing method and is convenient for industrial storage and use.

[0057] Test Example 1: Stability of Alternative Endothermic Hydrocarbon Fuel Compositions The stability of the alternative endothermic hydrocarbon fuel compositions prepared in Examples 3-6 was tested. The specific test method was as follows: the samples were placed in a centrifuge and centrifuged continuously at 8000 RCF for 5 minutes, and the stratification of the samples was observed. It can be seen that the samples remained homogeneous and stable, and no stratification occurred (see...). Figure 3 ).

[0058] As a comparison, hydroxylamine aqueous solution (hydroxylamine content 50%) was directly added to RP-10 kerosene at mass ratios of 2.5%, 5%, 7.5%, and 10% to prepare four control samples, which were then centrifuged under the same conditions. All control samples showed obvious stratification, failing to maintain system stability. Figure 4 ).

[0059] The results showed that palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate, as a composite surfactant, can effectively disperse and stabilize hydroxylamine aqueous solution in aviation kerosene, forming a stable composition that can resist high gravitational acceleration.

[0060] To further compare the effect of surfactant ratio on the stability of the fuel system, alternative endothermic hydrocarbon fuel compositions with different mass ratios of palmitic acid-terminated hyperbranched polyester and polyoxyethylene sorbitan laurate were prepared according to the method of Example 1. In Comparative Examples 1 to 8, the mass ratio of hydroxylamine aqueous solution (hydroxylamine content of 50%) to the total mass of the two surfactants was ensured to be 1:1.

[0061] Comparative Example 1 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate is 2:1, and the total mass of the three components, including hydroxylamine aqueous solution and two surfactants, accounts for 5% of the final fuel.

[0062] Comparative Example 2 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate is 2:1, and the total mass of the three components, namely hydroxylamine aqueous solution and two surfactants, accounts for 10% of the final fuel.

[0063] Comparative Example 3 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate is 2:1, and the total mass of the three components, namely hydroxylamine aqueous solution and two surfactants, accounts for 15% of the final fuel.

[0064] Comparative Example 4 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate is 2:1, and the total mass of the three components, namely hydroxylamine aqueous solution and two surfactants, accounts for 20% of the final fuel.

[0065] Comparative Example 5 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate is 1:2, and the total mass of the three components, namely hydroxylamine aqueous solution and two surfactants, accounts for 5% of the final fuel.

[0066] Comparative Example 6 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene sorbitan laurate is 1:2, and the total mass of the three components, namely hydroxylamine aqueous solution and two surfactants, accounts for 10% of the final fuel.

[0067] Comparative Example 7 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate is 1:2, and the total mass of the three components, namely hydroxylamine aqueous solution and two surfactants, accounts for 15% of the final fuel.

[0068] Comparative Example 8 Same as Example 1, except that the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene sorbitan laurate is 1:2, and the total mass of the three components, namely hydroxylamine aqueous solution and two surfactants, accounts for 20% of the final fuel.

[0069] The stability of the fuels in Comparative Examples 1 to 8 was tested according to the method in Test Example 1. The results showed that all samples in Comparative Examples 1 to 8 exhibited stratification and could not maintain stability (see Test Example 1). Figure 5 ).

[0070] The results showed that the binary surfactant system had the best hydrophilic-lipophilic balance when the mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene dehydrated sorbitan laurate was 1:1, thus achieving long-term stable dispersion of hydroxylamine aqueous solution.

[0071] Comparative Example 9 A method for preparing a fuel composition is the same as in Example 1, except that the mass concentration of the hydroxylamine aqueous solution is 25%.

[0072] Comparative Example 10 A method for preparing a fuel composition is the same as in Example 1, except that an aqueous solution of hydroxylamine is not added.

[0073] Test Example 2: Coking Performance of Alternative Endothermic Hydrocarbon Fuel Compositions Using blank RP-10 kerosene (i.e., pure RP-10 kerosene) as the sample, a continuous heat exchange experiment was conducted at 1.5 m / s and 8 MPa using a heat exchange device simulating a micro-heat exchange channel on the surface of an engine (GH3128 circular tube, total length 1000 mm, heating section length 900 mm, outer diameter 3 mm, inner diameter 2 mm). The results are as follows: Figure 6 As shown. In the experiment without the fuel additive pack (i.e., blank aviation kerosene), the pressure rapidly increased to 5 MPa within 100 s after the fuel reached the outlet temperature of 650 ℃, and the total operating time was 970 s.

[0074] The alternative endothermic hydrocarbon fuel composition prepared in Example 1 was tested under the same apparatus and experimental conditions. The results are as follows: Figure 6 As shown. The alternative endothermic hydrocarbon fuel composition of Example 1 maintained stable pressure for 1600 s after the fuel reached an outlet temperature of 650 °C. The pressure only rose to 1.55 MPa after 1800 s of operation.

[0075] The results show that the alternative endothermic hydrocarbon fuel composition of Example 1 of the present invention has better heat exchange safety and can significantly improve fuel coking.

[0076] The coking properties of fuel compositions with different concentrations of hydroxylamine aqueous solutions in Examples 1 and 9-10 are as follows: When the hydroxylamine concentration is 50 wt% (i.e., Example 1) (corresponding to) Figure 7 The pressure of the composition remained stable for 1600 s after the outlet temperature reached 650 ℃, and rose to 1.55 MPa after 1800 s, but was still within a controllable range.

[0077] When the hydroxylamine concentration was reduced to 25 wt% (i.e., Comparative Example 9) (corresponding to Figure 8 The pressure stabilization time was shortened to 1000 s, after which the pressure gradually increased and became uncontrollable, and the heat exchange safety was significantly reduced compared to the 50% group.

[0078] When using hydroxylamine-free pure water (i.e., Comparative Example 10) (corresponding to...) Figure 9 The pressure stabilization time was further shortened to 600 s, and then pressure runaway occurred, further reducing the safety of heat exchange.

[0079] The results showed that the concentration of hydroxylamine aqueous solution had a significant impact on the heat transfer safety of fuel. Hydroxylamine is an effective component for coking inhibition, which can release free radicals such as ·OH and ·NH2 to inactivate coking precursors and achieve coking inhibition.

[0080] A schematic diagram of the structure of the hyperbranched polyester used in this invention is shown below. Figure 10 As shown.

[0081] It should be noted that the fuel composition prepared according to the method of Example 3 has no significant difference in appearance, stability, and coking inhibition performance compared to the fuel composition prepared by directly mixing the components (method of Example 1). In use, the amount of fuel additive package added can be adjusted as needed to achieve a mass ratio of 5% to 40% in the final fuel, all of which can effectively inhibit coking and improve heat exchange safety.

[0082] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any simple modifications or alterations (including the amount of fuel additive, the water content of the fuel additive, the pressure, flow rate, temperature, etc. of the heat exchange test, etc.) or other equivalent substitutions that can be made by those skilled in the art without creative effort within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A fuel additive package, characterized in that, It consists of the following raw materials: aqueous hydroxylamine solution and surfactant; The mass ratio of the hydroxylamine aqueous solution to the surfactant is 1:1; The hydroxylamine aqueous solution contains 50% hydroxylamine by mass. The surfactant is composed of palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan lauryl ester. The mass ratio of palmitic acid-terminated hyperbranched polyester to polyoxyethylene sorbitan laurate is 1:

1.

2. A method for preparing the fuel additive package according to claim 1, characterized in that, The steps are as follows: palmitic acid-terminated hyperbranched polyester and polyoxyethylene dehydrated sorbitan laurate are added to an aqueous solution of hydroxylamine and stirred until the mixture forms a uniform, viscous paste to obtain the fuel additive package.

3. The use of the fuel additive package as described in claim 1 in the preparation of alternative compositions for hydrocarbon fuels for air-breathing engines and / or in air-breathing engines.

4. A fuel composition for an air-breathing engine, characterized in that, The fuel additive package of claim 1 is used as a substitute composition for hydrocarbon fuel to replace a portion of the hydrocarbon fuel; the mass ratio of the substitution is 5-40%.

5. A method for preparing the fuel composition for an air-breathing engine according to claim 4, characterized in that, The steps are as follows: Aviation kerosene is mixed with the fuel additive package and stirred evenly to obtain the fuel composition for air-breathing engines. The fuel additive package accounts for 5-40% of the mass of the fuel composition for air-breathing engines. or: (1) Mix polyoxyethylene dehydrated sorbitan lauryl ester with hydroxylamine aqueous solution and stir evenly to obtain base liquid A; (2) Mix palmitic acid-capped hyperbranched polyester with a portion of aviation kerosene and stir until a clear base liquid B is obtained; (3) Add the base liquid A to the base liquid B and stir to obtain a milky white homogeneous emulsion C; (4) Add the remaining aviation kerosene to the emulsion C and stir until the system is transformed into a uniform and stable milky white semi-transparent liquid, thus obtaining the fuel composition for the air-breathing engine.

6. The method for preparing the fuel composition for an air-breathing engine according to claim 5, characterized in that, In step (1), the stirring rate is 500 r / min and the stirring time is 10 minutes.

7. The method for preparing the fuel composition for an air-breathing engine according to claim 5, characterized in that, In step (2), the stirring rate is 500 r / min and the stirring time is 10 minutes.

8. The method for preparing the fuel composition for an air-breathing engine according to claim 5, characterized in that, In step (3), the stirring rate is 8000 r / min and the stirring time is 15 minutes.

9. The method for preparing the fuel composition for an air-breathing engine according to claim 5, characterized in that, In step (4), the stirring rate is 8000 r / min and the stirring time is 10 minutes.

10. The use of the fuel composition for an air-breathing engine according to claim 4 in an air-breathing engine.

Images