RU2255080C1 - Gas-free thermite fuel composition - Google Patents

Abstract

FIELD: alternate fuels.

SUBSTANCE: invention provides gas-free thermite fuel composition including powdered iron oxide-alumina mixture and additionally containing at least one element oxide selected from oxides of following elements: B, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, rare-earth elements, Hf, Ta, W, Pn, Bi and reducing agent selected from one or more of following elements: Mg, Ca, Ba, C, all components being taken in specified proportions and sum of all oxides to sum of reducing agents, including aluminum, being equal to 2-3. Fuel is characterized by controlled heat release, temperature, and burning rate. Inflammation time of fuel is of order of tenth parts of second.

EFFECT: extended assortment of gas-free fuels and increased safety of heat-generating apparatuses.

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Description

The invention relates to a power system, in particular, to gasless thermite fuel compositions capable of undergoing chemical transformations with the release of a large amount of heat upon initiation, mainly to those compounds that do not detonate and in which redox processes occur in combustion mode without the participation of the gas phase. The main use of such compounds is found in heat generators.

The known composition of the termite mixture containing the starting components in the following ratio, wt.%: Iron oxide (a mixture of iron oxides) 63-70; magnesium powder 23-28; sodium liquid glass 3.25-6.75; polytetrafluoroethylene 0.25-5.75 (SU 1779514 A1, 12/07/1992).

The known composition has a flash point of 752-1200 ° C and a moldability index of 0.16-0.55.

The main disadvantages of this composition:

- the impossibility of obtaining from the known mixture sufficiently strong fuel cells that would retain their shape and size not only during storage but also during combustion;

- the formation of harmful volatile substances during the combustion of organic binders included in the composition.

The closest in technical essence to the claimed composition is the composition of gas-free thermite fuel containing the starting components in the following ratio, wt.%: Iron oxide (a mixture of iron oxides) 40-45; aluminum (as reducing agent) 15-17; alumina 30-35; metallophosphate binder 7-10 (RU 2062194 C1, 06/20/1996).

The known composition of the fuel allows you to maintain the shape and size of the termite element during combustion and storage, has sufficient heat in the absence of gaseous and solid emissions. Exit to the stationary combustion regime of a thermite fuel cell is 6–13 s.

The known composition of the fuel is used for space heating and for generating electrical energy in special facilities.

The main disadvantages of the prototype:

- the presence in the composition of a significant amount of an inert additive - alumina, which significantly reduces the specific heat and does not allow to reach combustion temperatures above 2200K;

- the impossibility of smooth adjustment of specific heat and combustion temperatures above and below the interval of 2100 - 2200K;

- the need for the use of incendiary compounds;

- the formation during combustion of a phosphate binder vapor phase of phosphorus oxide and free phosphorus, which are toxic substances and can pollute the environment during emissions;

- long 6-13 s ignition time.

The technical result of the claimed invention is to expand the range of gas-free thermite fuel compositions that do not require the use of special ignition components, with controlled heat generation, temperature and burning rate, reducing the ignition time to tenths of a second, expanding the range of application of thermite fuel and increasing the safety of heat-generating devices based on this fuel.

The technical result is achieved in that the composition of gas-free thermite fuel, including a mixture of powders of iron oxide and aluminum, additionally contains at least one oxide of an element selected from the series B, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu , Zn, Y, Zr, Nb, Mo, REE, Hf, Ta, W, Pb, Bi and a reducing agent, which is selected as at least one element from the series Mg, Ca, Ba, C, in the following ratio of components, wt .%:

Iron oxide 16.6-62.5

Aluminum 5.0-24.0

The oxide of these elements is 12.5-52.5

The reductant of these elements is 1.0-20.0,

the ratio of the sum of all oxides to the sum of reducing agents, including aluminum, is 2-3.

The claimed combination of features by experimental selection of the components of the composition of thermite fuel and their ratio in the mixture allows you to adjust the combustion temperature in the range of 800 - 4400K, to control the specific heat in the range of 0.1 - 4.0 MJ / kg, the burning rate in the range of 4-20 mm / s, to obtain products combustion, preserving the shape and size of the initial compressed mixture and easily removed from the shell.

The claimed compounds are burned in a calm frontal mode without dispersing the initial mixture and combustion products, without emitting any harmful substances, including gaseous, except for air components that can be sorbed by the initial powder mixture. Depending on the requirements of a particular application, the combustion products may “hold” and may not “hold” the shape of the initial billet, while maintaining or not retaining the original volume. And combustion products can be used as abrasive and refractory materials.

The invention is confirmed by examples.

Example 1

Use the composition (wt.%): Fe ₂ O ₃ - 62.5; TiO ₂ - 12.5; Al - 5.0; Mg - 10.0; Ca - 10.0. Grinding and mixing the components is carried out in a ball mill. From this mixture, the fuel blocks are pressed in a hydraulic press at a load of 90-100 MPa in the form of blocks with a diameter of 30 mm and a length of 50 mm. The fuel blocks are then used in a heat generator, which is a cartridge with a head containing inlets for supplying an electrical impulse, by which the combustion of the drafts is initiated, as well as the terminal for the thermocouple BP 5/20, the junction of which is placed between adjacent drafts. Stationary combustion after initiation is established after approximately 0.3 s (ignition time). The calculated adiabatic combustion temperature of the composition used is 1950K. Inside the combustion zone, a temperature of 1890K develops. The velocity of the combustion front is 16 mm / s. The body of the cartridge is heated to white, but not melted.

Example 2

Use the composition (wt.%): Fe ₂ O ₃ - 26.75; TiO ₂ - 39.95; Al - 20.0; Mg - 7.0; C is 6.3. Further, as in example 1, but the thermocouple XA is fixed on the outer wall of the cartridge. The heat generator is lowered into a container of water. Stationary combustion after initiation of the composition by applying an electrical impulse is established after about 0.5. The estimated adiabatic combustion temperature is 2700 K. Inside the combustion zone, a temperature of 2100K develops, and on the outer wall of the cartridge 410K. The velocity of the combustion front is 10 mm / s.

In a parallel experiment, combustion of a fuel block of a similar composition is carried out outside the cartridge of the heat generator. Combustion products retain well the shape and size of the original checker with a slight increase in the length of the sample.

Example 3

Use the composition (wt.%): Fe ₂ O ₃ - 33.0; MoO ₃ - 36.8; Al - 20.2; Ca 10.0. Grinding and mixing the components is carried out in a ball mill. Fuel blocks from the specified mixture with a diameter of 30 mm and a length of 35-40 mm, compressed on a hydraulic press at a load of 100-120 MPa, are placed in the heat generator cartridge in an amount of 12 pieces. A heat generator is used in the form of a cartridge with a head containing in its composition inputs for supplying an electrical impulse with which combustion is initiated. Install a thermocouple XA on the outer wall of the cartridge. The cartridge is sealed and placed in a container of water. An internal thermocouple is not provided. The estimated adiabatic combustion temperature is 3870K. Ignition time - hundredths of a second. The maximum temperature on the outer wall of the cartridge immersed in water is 420K. Complete charge burning occurs in 20 s. The combustion product (iron - molybdenum alloy) sharply decreases in volume compared to the original block and is welded to the steel body of the cartridge. On top of the ingot is covered with a crust of slag from Al ₂ O ₃ .

Example 4

Use the composition (wt.%): Fe ₂ O ₃ - 22.5; CaO ₂ 47.5; B ₂ O ₃ - 5.0; Al - 20.0; Mg - 5.0. Next, as in example 3, put the fuel blocks from the specified mixture in the cartridge of the heat generator in the amount of 11 pieces. A heat generator is used in the form of a cartridge with a head containing in its composition inputs for supplying an electrical impulse, by which combustion is initiated. Install a thermocouple XA on the outer wall of the cartridge. The cartridge is sealed and placed in a container of water. Ignition time less than 0.1 s. An internal thermocouple is not provided. The estimated adiabatic combustion temperature is 3870K. The maximum temperature on the outer wall of the cartridge immersed in water is 397K. Complete charge combustion occurs in 22 s. The combustion product is easily removed from the cartridge, retains the shape and volume of the original fuel block.

Example 5

Use the composition (wt.%): Fe ₂ O ₃ - 45.0; SiO ₂ - 30.0; Al - 24.0; Ba - 1. Grinding and mixing of the components is carried out in a ball mill. Fuel blocks with a diameter of 30 mm and a length of 40 - 50 mm, pressed on a hydraulic press at a load of 120 - 125 MPa, are placed in a heat generator cartridge in an amount of 12 pieces. A heat generator is used in the form of a cartridge with a head and electrical impulse feed inputs to initiate the burning of checkers. Thermocouple XA is installed on the outer wall of the cartridge. The cartridge is sealed and placed in a container of water. Ignition time 0.8 s. The calculated adiabatic combustion temperature is 2360K. The maximum temperature on the outer wall of the cartridge immersed in water is 360K. Complete combustion of the charge occurs in 36 s. The combustion product is easily removed from the cartridge while maintaining the shape and volume of the original termite pieces.

Example 6

Use the composition (wt.%): Fe ₂ O ₃ - 42,0; TiO ₂ - 33.0; Al - 23.0; C is 2.0. After grinding and mixing the components of the composition from the mixture, the pieces are pressed with a diameter of 30 mm and a length of 50 mm at a load of 90 - 100 MPa. A heat generator is used in the form of a cartridge with a head and electrical impulse feed inputs for initiating the combustion of the blocks, containing a terminal for the thermocouple BP 5/20, the junction of which is placed between adjacent blocks. Fix the thermocouple XA on the outer wall of the cartridge. Stationary combustion after initiation is established almost instantly. The calculated adiabatic combustion temperature is 970K. Inside the combustion zone, a temperature of 890K develops, and on the outer wall of the cartridge - 165K. The velocity of the combustion front is 15 mm / s.

The presented examples do not limit the use of the claimed compounds, their other options can be carried out by specialists in this field.

Thus, the claimed compositions of gas-free thermite fuel do not contain inert additives, which allows you to fully use the calorific value of the system and achieve maximum combustion temperatures, do not require the use of special ignition compositions, allow you to adjust the specific heat, temperature and burning rate, while the ignition time of the compositions is not more than 1 s.

Claims (1)

The composition of gas-free thermite fuel, including a mixture of powders of iron oxide and aluminum, characterized in that it additionally contains at least one oxide of an element selected from the series B, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, REE, Hf, Ta, W, Pb, Bi, and a reducing agent, which is selected as at least one element from the series Mg, Ca, Ba, C, in the following ratio of components, wt .%: Iron oxide 16.6-62.5 Aluminum 5.0-24.0 The oxide of these elements is 12.5-52.3 Reductant specified elements 1,0-20,0, the ratio of the sum of all oxides to the sum of reducing agents, including aluminum, is 2-3.