RU2794674C1 - Elastic-deformable gel-like fuel - Google Patents

Abstract

FIELD: fuel.

SUBSTANCE: elastically deformable gel fuel containing an aqueous solution of polyvinyl alcohol, polyoxyethylene emulsifier, lignite, industrial oil, characterized in that it additionally contains aluminum nanopowder with a particle size of 90-100 nm in the following ratio of initial components, wt.%: polyvinyl alcohol (10% th aqueous solution) 19.6-49; polyoxyethylene 0.4-1; brown coal 1-10; industrial oil 40-50 and aluminum nanopowder 5-20.

EFFECT: expansion of the range of gel-like fuel while improving its parameters.

2 cl, 3 dwg, 1 tbl, 3 ex

Description

The invention relates to the fuel industry, in particular to the production of gel fuel, and can be used as kindling, reserve and main fuel for combustion in heating and heating domestic and industrial installations.

From WO 2016055814 [publ. 2016-04-14, IPC C10L 7/04] a gel-like fuel intended for use in the fuel industry, for heating or lighting rooms and a method for producing it are known. Gel-like fuel contains 3 kinds of components: component a), which is an alcohol or a mixture of several alcohols, occupying from 50 to 98% of the volume, ethanol is preferred, in particular bioethanol, butanol or isopropanol, bio-butanol or bioisopropanol can also be used; component b) a polymer comprising from 2 to 30% by weight of the gel fuel; component c) chemical crosslinker: 2 to 30% by weight of the gel fuel, preferably polyethylene glycol dimethyl acrylate. The gel fuel may further contain one or more optional solvents such as water. Preferably the solvent is up to 40% by volume of the gel, optimally 5% by volume of the gel. The method for producing gel fuel consists of the steps of mixing the above components, i.e. at least one alcohol, at least one monomer, and at least one chemical crosslinker. The components can be mixed in any order. For example, some or all of components b) and c) may be initially mixed together and then component a) is added, or all components may be mixed together at the same time. The method may further include the step of cooling the resulting mixture to 0° C. or below.

From WO 2003074935 [publ. 12.09.2003, IPC C10L 7/04] known fuel gel and method for its production. A fuel in a gel state is described, which includes a mixture of vegetable material in combination with alcohol, primarily ethanol, which is gelled by the addition of methylhydroxypropyl cellulose (MHPC). The resulting gel burns without smoke, without soot, without harmful gas emissions, is non-carcinogenic and non-aggressive, not expensive. The fuel described in the application contains: a gel-like mixture of not more than 95% ethanol by mass, obtained from vegetable raw materials, and not less than 5% water by mass, additionally the mixture contains up to 5 wt. % MHPC. Upon receipt of the claimed fuel gel, alcohol from vegetable raw materials, which consists of no more than 95% ethanol, is mixed with 5% water, then fusel oil and MHPC are added to the mixture, which is stirred to completely dissolve MHPC and fusel oil in the mixture. The viscosity of the gel increases with time as it approaches the completion of the MHPC dissolution and becomes constant after 5 days.

From patent RU2467058 [publ. 11/20/2012, IPC C10L5/10] on fuel briquettes and the method of their formation is known cryogel, which is obtained at the first stage of the process of obtaining a solid fuel briquette. The cryogel contains polyvinyl alcohol, water, coke(coal) and oil in the following ratios, wt. %: polyvinyl alcohol (PVA) - 5-10; particles of coke or coal - 30-70; mineral oil - 3-7; water is the rest. It also describes a method for producing a cryogel, in which fine carbon-containing particles (coke, coal) with a size of 0.1-10.0 mm, pre-impregnated with waste oil products, are added to an aqueous solution of polyvinyl alcohol. The resulting composition is thoroughly mixed, transferred to metal cells and frozen at a negative temperature (-20°C) for 20 hours, then thawed for 4 hours at room temperature (+20°C) at a rate of 0.15°C/min, as a result resulting in an elastic cryogel filled with carbon-containing particles, retaining its structure up to a temperature of 70°C.

From [Heat and mass transfer induced by the ignition of single gel propellant droplets. DO Glushkov, GV Kuznetsova, AG Nigay , VA Yanovskyb, OSYashutina // Journal of the Energy Institute. - 2019. - Vol. 92.-P. 1944-1944] known gel fuel, based on a 95% solution of ethanol (calorific value of 26.78 MJ/kg, combustion rate of about 60 kg/(m ² ⋅h)). Pine resin was added to the liquid fuel as a gelling agent. This is an organic substance that effectively thickens ethanol when dissolved in it. Small particles of aluminum 50-250 mm in size were added to the fuel as a promising component to improve its combustion characteristics and increase the energy density. Fuel samples were prepared in several stages. First, pine resin was mixed with ethanol to dissolve in it. Then, a finely dispersed solid component (aluminum particles) was added to the resulting mixture. The fuel components were mixed at a temperature of about 300 K. Each stage of mixing the components was controlled visually. At the first stage, mixing ended with the complete dissolution of pine resin in ethanol (there were no lumps of pine resin). At the second stage, aluminum particles were gradually introduced into the fuel mixture, which ensured a uniform distribution of both liquid and solid components over the volume of the fuel sample. When preparing a sample of gel-like fuel weighing about 0.25 kg, the duration of the first stage was at least 10 min, and the second one was two times shorter. A homogenizer with a speed of 2000 rpm made it possible to achieve a high uniformity in the distribution of components throughout the fuel volume. An experimental study showed that the minimum _air temperatures Tg _at which the ignition of the gel-like fuel occurred in the range from 873 _to 943 K. the following proportions of components: 45% ethanol; 45% pine resin; 10% aluminium.

From [Ignition mechanism and characteristics of gel fuels based on oil-free and oil-filled cryogels with fine coal particles. Glushkov D.O., Kuznetsov G.V., Nigay A.G., Yanovsky V.A., Yashutina O.S. // Powder Technology. - 2020. - Vol. 360. - P. 65-79] known elastically deformable gel-like fuel, the prototype, which is a cryogel containing fine solid particles of coal dust and oil as the main fuel component. The cryogel contains the following components in the ratio of concentration, wt. %:

aqueous solution of PVA (10 wt.%) 37.8

dispersed coal grade 2B, 30.0

oil I-40 32.2.

Brown coal dust was used as a solid combustible component. The fuel preparation process included the preparation of the main component of all cryogels - an aqueous solution of polyvinyl alcohol, which forms a polymer structure that determines the gel-like state of the fuel. Polyoxyethylene was used as an emulsifier, which was added to an aqueous solution of PVA in an amount of 4 vol. %. The next step was to obtain an oil emulsion in an aqueous solution of PVA, into which coal dust was then introduced. Emulsification was carried out by mixing the components with a high-speed digital mixer. The resulting emulsions remained stable for 3-5 hours until the formation of the gel-like structure of the fuel. The formation of the gel-like structure of the fuel occurred during the implementation of successive processes of freezing suspensions and emulsions at a temperature of -15°C for 12 hours and subsequent thawing for 12 hours at room conditions. Finely dispersed oil drops and coal particles were located in the cells of the formed polymer matrix. The total number of freeze/thaw cycles for gel fuels was 15. The ignition delay times for particles of gel fuels based on oil-filled cryogels (10 wt % aqueous PVA solution) containing coal particles at 600°C were about 5–6 s.

The advantage of all types of gel-like fuels described above and used for household needs is its ability to retain its shape, burn without smoke and soot, ease of packaging, low production cost.

The disadvantages of the already known gel-like fuel include its low energy characteristics, such as ignition delay time, combustion temperature, combustion heat, and burnout rate.

The objective of this invention is to develop a fuel composition with improved energy parameters, which can be used as a starting, reserve and main fuel for combustion in heating and heating domestic and industrial installations and is completely combustible, does not generate soot or dangerous gases, and is harmless to the human body. , maintains the solid phase during storage, does not create a risk of fire or environmental pollution due to fuel leakage.

The technical result is the expansion of the range of gel-like fuel for domestic and industrial needs, while improving its parameters - reducing the ignition delay time.

The technical result is achieved by the fact that the elastically deformable gel-like fuel containing an aqueous solution of polyvinyl alcohol, polyoxyethylene emulsifier, brown coal, industrial oil additionally contains aluminum nanopowder with a particle size of 90-100 nm. at the following ratio of initial components, wt. %:

polyvinyl alcohol (10% aqueous solution) 19.6-49;

polyoxyethylene 0.4-1

brown coal 1-10;

industrial oil 40-50;

aluminum nanopowder 5-20;

The composition of the gel-like fuel is optimal with the following ratio of initial components, wt. %:

polyvinyl alcohol (10% aqueous solution) 49;

polyoxyethylene 1

brown coal 1;

industrial oil 44;

aluminum nanopowder 5.

The essential difference of the claimed fuel is that with the claimed ratio of components, the process of ignition intensification and burnout of the gel-like fuel is realized due to the dispersion of the melt drop (Fig. 1). The effect of dispersing a drop of melted gel-like fuel leads to an intense release of energy within 2–5 s after the start of heating in a region that is sufficiently large in volume, the dimensions of which exceed the initial size of the drop by 7–14 times. At the initial moment of heating in the process of fuel melting, the components are separated. A thickener shell is formed on the surface of the drop. With further heating of the fuel, bubbles appear in the near-surface layer. When critical conditions are reached, these bubbles collapse, which leads to dispersion and a large number of fine droplets containing particles of coal and metal are formed, which scatter in the radial direction. Because Since the phase transformation processes are endothermic, the temperature in the vicinity of this droplet is rather low; therefore, when these finely dispersed droplets move, they fall into the region of higher oxidizer temperatures. As a result of dispersion, more intensive heating of particles impregnated with a combustible liquid occurs, a combustible gas mixture is formed more intensively, carbon particles are ignited, vapors of a combustible liquid are ignited, then, when high temperatures are reached, metal nanoparticles are ignited and, accordingly, ignition occurs faster than the fuel in the initial state. Then the combustion process spreads throughout the area.

The invention is illustrated by the following graphics.

On FIG. 1. schematically shows the ignition intensification mechanism of the inventive gel-like fuel.

On FIG. 2. a diagram of the process for obtaining gel-like fuel is presented.

On FIG. 3. A graph of the ignition delay time of particles of gel-like fuels based on oil-filled cryogels of various compositions is shown:

1. 49% PVA; 1% polyoxyethylene; 1% coal; oil 44%; 5% aluminum

2. 37.044% PVA; 0.756% polyoxyethylene; 30% coal; oil 32.2%

3. 44.1% PVA; 0.9% polyoxyethylene; 45% oil; 10% aluminum

4. 47.04% PVA; 0.96% polyoxyethylene; 50% oil.

The inventive gel fuel is prepared as follows. At the first stage (Fig. 1) is the manufacture of the basis of the gel-like fuel - an aqueous solution of polyvinyl alcohol. It is due to this component that a polymer matrix is formed with solid polymer nanoparticles in the nodes of the framework structure of polymer bonds, which determines the gel-like state of the fuel. PVA powder using high speed laboratory mixer Model GJ-3S (Qingdao ChuangMeng Instrument Co., Ltd., China) at 1000 rpm. dissolve in water. To intensify the process, during stirring, an aqueous solution of PVA is heated to a temperature of 85°C. Stir until complete dissolution of the PVA powder and the disappearance of the precipitate. The emulsifier polyoxyethylene (Tween® 80) is used to stabilize the emulsion. It is dissolved in an aqueous solution of PVA in an amount of 2% vol. When using aqueous solutions of PVA polymer with a mass concentration of the latter of 10% as a dispersion medium, a fuel emulsion with relatively high sedimentation stability characteristics is obtained.

At the second stage (Fig. 2), an oil emulsion is prepared in an aqueous PVA solution, into which coal dust is introduced. Oil is introduced into the PVA solution in portions (10-15% of the total calculated volume) (the volume ratio of oil/PVA solution is 1:1). Emulsification is carried out by mixing the components at a temperature of 20°C using a homogenizer with a rotation speed of 11000 rpm. Each next portion of the oil is injected after complete emulsification of the previous portion for 5-10 minutes. In the prepared oil emulsion under constant stirring with a paddle mixer at 3000 rpm. portions (weight of each 50-75 g) introduce coal dust and metal nanoparticles. The duration of mixing after adding each portion is at least 15 minutes. The resulting suspension remains stable for 5 hours before the formation of the gel-like structure of the fuel.

At the third stage, the prepared suspension is subjected to a series of consecutive processes of freezing at a temperature of minus 15°C for 12 hours and subsequent thawing of the sample for 12 hours at a temperature of plus 20°C. As a result, finely dispersed oil drops, coal and metal particles are located in the cells of the formed polymer matrix. The total number of cycles of freezing and thawing of elastically deformable gel-like fuel is 15.

The following materials were used in the manufacture of gel fuel. To prepare an aqueous solution of polyvinyl alcohol - distilled water with an electrical conductivity of not more than 5 μS / cm and polyvinyl alcohol Kuraray Poval® 15-99 (viscosity 4% (DIN 53015) - 13.4 mPa s, degree of hydrolysis - 99.2%, residual content of acetyl - 0.8% (manufactured by Kuraray Co., Ltd, Japan). The emulsifier Tween® 80, polyoxyethylene (20) sorbitan monooleate (Vekton, Russia) was used. Industrial oil I-40A (GOST 20799-88, Russia) was used as an oil with the following parameters: kinematic viscosity - 61-75 cSt (at 40 °C); density - 868 kg / m ³ (at 20 ° C); ash content - no more than 0.005% wt.; freezing point - not higher than minus 15°C; flash point - not lower than 220°C. Aluminum nanopowder was taken with the marking V-ALEX (100), which is equivalent to 85-87% wt. active aluminum + 8-10% wt. vinylidene fluoride and hexafluoropropylene + 5-7% wt. aluminum oxide with a particle size of 90-110 nm (manufacturer Advanced Powder Technologies, Russia). Brown coal was used grade 2B (Borodinsky open pit, Krasnoyarsk Territory) with the results of technical analysis - moisture content 14.11%, ash content 4.12%, volatile content 47.63%, lower calorific value 22.91 MJ / kg; and elemental analysis results - C _daf =73.25%, H _daf =6.52%, N _daf =0.79%, S _td =0.44%, O _daf =18.99%.

In FIG. 3. The obtained experimental dependences of the ignition delay time of particles of gel-like fuels based on oil-filled cryogels of various compositions are given. As can be seen from the graph, the ignition delay time (at 600°C) for a gel fuel consisting of PVA and I-40 oil is 16 s (curve 4). The addition of aluminum nanoparticles to this composition in an amount of 10% leads to a significant decrease in the ignition delay time, at 600°C t _d =7 s. (curve 3). Introduction to the gel-like fuel particles of brown coal in the amount of 30 wt. % makes it possible to obtain a gel-like fuel with an ignition delay time at 600°C t _d =8 s (curve 3). The best parameter of the ignition delay time t _d =6.5 s has the inventive composition, which simultaneously contains brown coal and aluminum nanoparticles (curve 1).

The invention can be illustrated by the following examples.

Example 1 Was made gel fuel with the following ratio of initial components, wt. %:

polyvinyl alcohol (10% aqueous solution) 49;

polyoxyethylene 1;

brown coal particles 1;

industrial oil 44;

aluminum nanopowder 5.

The fuel was prepared in the following way. 10 grams of PVA powder using a high speed laboratory mixer at 1000 rpm. dissolved in 90 grams of water. To intensify the process, during stirring, an aqueous solution of PVA was heated to a temperature of 85°C. The mixing procedure was carried out until the complete dissolution of the PVA powder and the disappearance of the precipitate. Emulsification was carried out by mixing 2 grams of polyoxyethylene with the resulting PVA solution at a temperature of 20°C using a homogenizer with a speed of 11,000 rpm./min. Further into the PVA solution with an emulsifier in portions of 10-20 grams, industrial oil I-40 was introduced with a total volume of 88 grams. Each next portion of the oil was introduced after complete emulsification of the previous portion for 5-10 minutes. In the prepared oil emulsion under constant stirring with a paddle mixer at 3000 rpm. portions (weight of each 1-2 grams) were introduced brown coal dust (total weight 2 grams) and aluminum nanopowder (total weight 10 grams). The duration of stirring after the addition of each portion was at least 15 min. The resulting suspension remained stable for 5 hours before the formation of the gel-like structure of the fuel. The prepared suspension was subjected to successive processes of freezing at a temperature of minus 15°C for 12 hours and subsequent thawing of the sample for 12 hours at a temperature of plus 20°C. Finely dispersed oil drops, coal and metal particles were located in the cells of the formed polymer matrix. The total number of freeze/thaw cycles of the elastically deformable gel fuel was 15. The ignition delay time (at 600°C) was 6.5 s.

EXAMPLES 2, 3.

The process of obtaining gel-like fuel for a different quantitative ratio of components was carried out in the same order as in Example 1. The conditions and physical parameters for the obtained compositions of gel-like fuel are presented in Table 1. From the experimental data given in the table, it follows that in all the given examples, claimed technical result.

Table 1 No. Initial mass of reagents, g PVA stirring temperature, °C PVA solution concentration, % Emulsification temperature, °C Mixer speed, rpm Modulus of elasticity G, kPa Ignition delay time (at 600°C), s burning time,
(at 600°C), s 1 PVS 49
polyoxyethylene 1
coal 1
oil 44
aluminum 5 85 10 20 11000 54 6.5 4.35 2 PVA 34.3
polyoxyethylene 0.7
coal 10
oil 40
aluminum 15 85 10 20 11000 25 9.1 3.258 3 PVA 19.6
polyoxyethylene 0.4
coal 10
oil 50
aluminum 20 85 10 20 11000 15 9.7 3.00

Finished products from gel-like fuel of the claimed composition have a stable elastically deformable shape with evenly distributed components throughout the volume. There is no formation of a combustible gas mixture in the vicinity of the gel-like fuel during its storage and transportation. For elastically deformable gelled fuels, packaging of any kind and shape is suitable without special requirements for handling combustible liquid materials. Such fuel does not leak, even if the packaging is damaged. The finished fuel is suitable for both pellet boilers and liquid atomized burners.

Thus, the claimed elastically deformable gel fuel is a new fuel and energy product with a low ignition time, rheologically stable and resistant to deformation, in combination with less flammable characteristics during storage and transportation. The introduction of solid combustible particles of brown coal and aluminum nanoparticles into the composition of the gel-like fuel together makes it possible to intensify the process of fuel ignition.

Claims (4)

1. Elastically deformable gel-like fuel containing an aqueous solution of polyvinyl alcohol, polyoxyethylene emulsifier, lignite, industrial oil, characterized in that it contains aluminum nanopowder with a particle size of 90-110 nm in the following ratio of initial components, wt.%: polyvinyl alcohol (10% aqueous solution) 19.6-49 polyoxyethylene 0.4-1 brown coal 1-10 industrial oil 40-50 aluminum nanopowder 5-20 2. Elastically deformable gel fuel according to claim 1, containing the initial components in the following ratio, wt.%: polyvinyl alcohol (10% aqueous solution) 49 polyoxyethylene 1 brown coal 1 industrial oil 44 aluminum nanopowder 5

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