RU2486463C1 - Method of limitation of explosive impact and flameproof enclosure - Google Patents

Abstract

FIELD: blasting operations.

SUBSTANCE: method of limitation of explosive impact is based on localisation of equipment in the flameproof enclosure, in which a protective layer is formed, and the protective layer is formed on the inner surface of the flameproof enclosure of the ballistic material made with damping layers, and on the damping layers the outer layers are applied, made of metal foil. The flameproof enclosure comprises a housing with a lid connected by screws, inside which the normally sparking equipment parts are installed, and the inner surface of the housing and the lid is covered with ballistic material made with the ability to reduce the pressure generated by the explosion shock wave at explosion of the explosive mixture inside the enclosure. The inner surface of the housing and the lid is covered by more than one layer of the ballistic material.

EFFECT: use of the claimed group of inventions enables to create a flameproof enclosure which has a high reliability, improved mass-dimensional properties, and the ability to use the equipment installed inside it at a low temperature.

12 cl, 1 dwg

Description

The invention relates to the field of protection against explosive effects, in particular, can be used to limit the effects of an explosion in flameproof enclosures designed to accommodate equipment, for example, electric, pneumatic, mechanical drives, etc.

A number of technical solutions are known to increase the explosion protection of equipment, among which are the use of circuitry solutions aimed at reducing the likelihood of sparking. One of the options for this solution is an explosion-proof uninterruptible power supply (US Pat. RF No. 97879, IPC H02J 7/10, published September 20, 2010), containing an explosion-proof enclosure, inside of which there is a battery and an electronic unit including functional units: interface, two pulse converters of alternating voltage to direct, diode circuit OR, spark-proof group of elements. Reducing the likelihood of sparking is achieved by introducing an OR diode circuit, a charger, a pulsed DC-to-DC converter, a blocking diode, and the use of a digital serial interface into the electronic unit.

The disadvantage of such solutions is their limited use, due to the fact that only electrical equipment located inside the enclosure is protected, due to the possibility of making circuitry additions. However, when a shock wave occurs, the degree of impact on the explosive-permeable shell and equipment placed in it does not decrease.

Known explosion-proof transformer substation, providing increased explosion protection of the equipment due to improved heat transfer (US Pat. RF No. 2305352, IPC Н02В 7/01, H01F 27/20, published on 08.27.2007.), Which contains a power transformer enclosed in an explosion-proof enclosure, including a magnetic circuit with horizontal yokes - upper and lower, and windings with axial channels, longitudinal channels, fans, guide plates, while the lateral surfaces of the explosion-proof shell are made in the form of panels of thin-walled pipes, and Aneli interconnected with a radiator cooling the coolant and a cooling manifold of the upper yoke, and the fans are installed in the lower part of the explosion-proof membrane, opposite the magnetic core.

A common disadvantage of the above devices is the low reliability and limited application, due to the fact that when the probability of spark formation is reduced, the impact of the shock wave when an explosion occurs does not decrease.

Another option to increase explosion protection is the use of transition chambers and labyrinth explosion channels. So, for example, in an explosion-proof push-button element (US Pat. RF No. 2290710, IPC H01H 13/06, Н01Н 9/04, publ. 12/27/2006) protection against explosion pressure and the prevention of transmission of the explosion into the environment is ensured by the fact that the camera switching in the housing is formed at the intersection of oncoming, blind, cylindrical openings, while the open parts of the cylindrical openings play a technological role and, upon completion of assembly, are closed with plugs or covers, as a result of which normally sparkling parts are enclosed in an explosion-proof enclosure Flamed using cylindrical flameproof joints.

Known explosion-proof light device (US Pat. RF №2259512, IPC F21V 25/12, publ. 08/27/2005), containing a discharge lamp with a cartridge, which is installed inside a protective optically transparent cap on a holder made of heat-conducting material in thermal contact with massive mandrel in the form of a flange from a similar material in which the specified cap is installed and sealed. The mandrel is equipped with a labyrinth explosion channel connecting the inner cavity of the cap with the environment and, together with the holder, is mounted on the cover of the input box for the device with the formation of a transition chamber to accommodate the free part of the current-carrying wires. The lamp holder with a cartridge is made in the form of a bead with a flange installed by sliding fit on the lateral surface and mounted in the axial hole of the mandrel of the intermediate ring element, threaded at the periphery and set on the reciprocal thread in the axial hole of the mandrel with the formation of a threaded labyrinth explosion channel.

A common disadvantage of transition chambers and labyrinth explosion channels is an increase in the overall dimensions and mass of explosion-proof shells, as well as low reliability due to the low efficiency of reducing the impact of a shock wave.

Widespread methods of increasing explosion protection by hardening the structural elements of the shell and the use of universal shell designs with lodgements.

So, there is a known method of increasing explosion protection, in which a flameproof enclosure (Pat. RF No. 21946, IPC F16M 5/00, Н02К 5/136, publ. 02/27/2002) contains a cylindrical body with a hole and an input box mounted on the end of the body, which is equipped with lodgements made with the possibility of installing interchangeable platforms on them with electric drives of various types, and the cylindrical body is made in the form of a pipe with end caps installed with an explosion-proof gap and pulled with the pipe by at least three fasteners, sprinimayuschimi explosion pressure.

A known method of localization of explosion products in a confined space (US Pat. RF No. 2009387, IPC F17C 1/00, publ. March 15, 1994), in which they form an outer metal shell on a spherical metal shell made with two coaxially arranged necks with holes of the same diameter, while the outer shell is multilayer of at least five groups of layers. The specified method involves the maximum use of the strength properties of materials and the bearing capacity of the structure, which complicates the manufacturing technology of explosion localization devices and increases its cost.

A known method of limiting the effects of explosive and shock waves in a closed volume (US patent No. 2397622, MKI F42D 5/00), comprising filling the volume in which the explosion is carried out with a heterogeneous medium in the form of a powdery or porous material having a low density (perlite, vermiculite ) The specified method allows to reduce the intensity of the shock wave, however, the efficiency of localization of aerosols and explosion products formed during the explosion is low, since their mixing capabilities are limited.

Closest to the claimed method is a method of limiting the effects of an explosion in a closed volume (RF patent No. 2009387, F17C 1/00, publ. March 16, 1994), in which the closed volume is filled with a heterogeneous medium of low density, which is created dynamically by accelerated motion of the layer dispersed substance or liquid layer, while in a closed volume there is a container with a shell destroyed by explosion filled with condensed substance, and the container is made in the form of a layer placed at a distance from the wall of the housing.

Closest to the claimed device is an explosion-proof push-button control post device (US Pat. RF No. 48229, IPC G05B 7/00, published September 27, 2005), comprising a housing with a lid connected by screws, inside of which there is a cable entry, a panel of button elements , a control handle, while the case with the cover, connected by screws, form an explosion-proof shell in which normally sparkling parts are enclosed, the case is made of AG - 4 NS press material, and the panel of button elements is configured to perform functions and the switching compartment, the passage clamps and simultaneously performing the function of the wall separating the cable entry from the switching compartment with the formation of a cylindrical flameproof connection.

A common disadvantage of the above method and flameproof enclosure is the lack of reliability due to the low efficiency of reducing the impact of the shock wave.

The main objective of the proposed group of inventions is to create a method of limiting explosive impacts and flameproof enclosures with high reliability, improved overall dimensions and the ability to use equipment at lower temperatures.

The technical result is to increase reliability by providing high efficiency to reduce the impact of the shock wave and expand the temperature range of equipment use, reducing the weight and dimensions of the flameproof enclosure.

The specified technical result is achieved by the fact that in the claimed method of limiting explosive impacts, based on the localization of equipment in an explosion-proof enclosure in which a protective layer is created, the formation of the protective layer is made of ballistic material made with damping layers, while the outer layers are applied to the damping layers, made of metal foil.

As ballistic material, you can use fabrics or hybrid materials or mesh materials that do not support combustion.

Plasticine that does not support combustion can also be used as a ballistic material.

As ballistic material can also be used materials based on glass or carbon fibers, or polymers or composites that do not support combustion.

Preferably, a high pressure polyethylene film made with a bubble coating can be used as a ballistic material.

It is optimal to make a bubble coating by welding to a substrate made of a flat film material, a layer of polyethylene with bubbles.

The problem is also solved by the fact that in a flameproof enclosure containing a housing with a lid, inside which the equipment is installed, ballistic material made with damping layers is applied to the inner surface of the housing and lid, while the outer layers are made of metal foil.

Optimally, the housing and cover are made of metal or alloys, for example, aluminum, cast iron, aluminum-silicon alloy, steel or polyester, or polypropylene.

The housing and the cover of the flameproof enclosure can be reinforced.

The housing and the cover of the flameproof enclosure can be connected by screws, and the holes provided with gaskets can be optimally made in the housing.

The flameproof enclosure may be provided with a mounting panel configured to mount equipment.

High reliability of the claimed group of inventions is ensured by the fact that the inner surface of the housing and the cover is covered with ballistic material with damping layers, made with the possibility of reducing the pressure created by the shock wave during the explosion of an explosive mixture inside the shell.

Improving the overall dimensions is achieved by coating the surface of the body and lid with ballistic material, which reduces the pressure created by the shock wave, which eliminates the need to increase the thickness of the shell, the use of reinforcing stiffeners and lodgements.

The invention is illustrated in the drawing, which schematically shows a flameproof enclosure in section.

The inventive method and device are implemented as follows.

In the manufacture of a flameproof enclosure, a ballistic material 3 made of damping layers is applied, for example by gluing, to the inner surface of the housing 1. The housing 1 and the cover (not shown in the drawing) can be made of a material having high strength and ductility, for example, of metal or alloys or of polyester or polypropylene.

The ballistic material may be made of fabrics or hybrid materials, or mesh materials, or glass or carbon fibers, or polymers or composites, or plasticine, not supporting combustion.

Most preferably, to reduce costs and improve manufacturability, use a bubble film of high pressure polyethylene.

The bubble coating is carried out by welding to a substrate made of a flat film material, for example a layer of polyethylene with bubbles, which is obtained by molding heated polyethylene in the form of bubbles on the extrusion line of production. The implementation of the damping layers in plasticine is possible by adding soft inclusions, for example, foam or foam, to its structure. In fabric materials for the implementation of damping, you can use different structures of the threads for the production of the outer and inner layers of the material, as well as different methods of winding or weaving the material, or the threads themselves.

In this case, the ballistic material in the preferred embodiment of the invention may consist of several layers of air-bubble film, protected by a metal foil. By varying the density of the polyethylene bubble film used and the size of the bubbles, a different degree of damping of the ballistic material can be achieved. The aluminum protective foil may also have a different density, which affects the degree of damping of the material as a whole.

Ballistic material in the form of an air bubble film is created from high pressure polyethylene. The bubble wrap is covered with bubbles that are filled with dry air. The technology for creating a bubble coating consists in welding onto a substrate (flat film) a layer of polyethylene, which is obtained by molding heated polyethylene in the form of bubbles on an extrusion production line. This method provides the strength of the connection of each bubble with the substrate, while the bubbles are at a certain distance from each other. The structure of the film allows you to maintain the overall damping properties of the coating even when some bubbles are damaged.

The value of permissible pressure and load on the material is determined by grammar, an indicator measured in grams. Grammar is the amount of film needed to produce a square meter of bubble film. The higher the grammar index, and therefore the density index, the stronger the material.

The composition of the air-bubble film may include an antifog modifier that eliminates the condensation that forms on the inner surface of the film.

An air bubble film can be given antistatic properties. As part of such a specialized antistatic film, modifiers are introduced to prevent the accumulation of static electricity.

When additives are added to the primary raw materials that can extinguish the flame, a low-combustible ballistic material is obtained. The additives used to obtain the necessary properties also include an antioxidant. Such an additive protects metal products from the process of oxygen oxidation, which is important for the use of ballistic material inside metal cases.

In the flameproof enclosure, both electrical equipment 2 and non-electrical equipment (pneumatics, mechanical drives, etc.) can be installed. The method and the flameproof enclosure can preferably be used in conditions where there is an increased explosion hazard, for example, in underground workings of mines, mines and in their ground structures that are hazardous to mine gas and / or combustible dust for explosion-proof electrical equipment. In this case, explosion-proof electrical equipment according to GOST is divided into the following groups:

I - mine explosion-proof electrical equipment intended for use in underground workings of mines, mines and in their ground structures, dangerous for mine gas and / or combustible dust;

II - explosion-proof electrical equipment for indoor and outdoor installation, designed for potentially explosive atmospheres, except for underground workings of mines and mines and their ground structures, dangerous for mine gas and / or dust.

The distribution of explosive mixtures by categories and groups in which the method of limiting explosive influences and the flameproof enclosure can be used are given in table 1

Table 1 Mixture Category Mixture group Substances forming an explosive mixture with air I T1 Methane (mine) * IIA T1 Ammonia, allyl chloride, acetone, acetonitrile, benzene, benzotrifluoride, vinyl chloride, vinylidene chloride, 1,2-dichloropropane, dichloroethane, diethylamine, diisopropyl ether, blast furnace gas, isobutylene, isobutane, isopropylbenzene, acetic acid, xylene, xylene **, methyl acetate, a-methyl styrene, methyl chloride, methyl isocyanate, methyl chloroformate, methyl cyclopropyl ketone, methyl ethyl ketone, carbon monoxide, propane, pyridine, solvents R-4, R-5 and PC-1, diluent RE-1, solvent petroleum, styrene, diacetone alcohol, toluene, trifluorochloropropane, trif torpropene, trifluoroethane, trifluorochlorethylene, triethylamine, chlorobenzene, cyclopentadiene, ethane, ethyl chloride. T2 Alkylbenzene, amyl acetate, acetic anhydride, acetylacetone, acetyl chloride, acetopropyl chloride, gasoline B95 / 130, butane, butyl acetate, butyl propionate, vinyl acetate, vinylidene fluoride, diatol, diisopropylamine, isopropylamine, isopropylamine, isopropylamine, isopropylamine, isopentane , methyl isobutyl ketone, methyl methacrylate, methyl mercaptan, methyl trichlorosilane, 2-methylthiophene, methylfuran, monoisobutylamine, methyl chloromethyldichlorosilane, mesityl oxide, pentadiene-1,3, propylamine, propylene. Solvents: No. 646, 647, 648, 649, PC-2, BEF and AE. Thinners: RDV, RKB-1, RKB-2. Alcohols: normal butyl, butyl tertiary, isoamyl, isobutyl, isopropyl, methyl, ethyl. Trifluoropropylmethyldichlorosilane, trifluoroethylene, trichlorethylene, isobutyl chloride, ethylamine, ethyl acetate, ethyl butyrate, ethylenediamine, ethylene chlorohydrin, ethyl isobutyrate, ethylbenzene, cyclohexanol, cyclohexanone. IIA T3 Gasolines: A-66, A-72, A-76, "galosh", B-70, extraction according to TU 38.101.303-72, extraction according to MRTU12N-20-63. Butyl methacrylate, hexane, heptane, diisobutylamine, dipropylamine, isovalerianic aldehyde, isooctylene, camphene, kerosene, morpholine, oil, petroleum ether, TGM-3 polyester, pentane, solvent No. 651, turpentine, amyl alcohol, T-1, trimethyl, trimethyl -1, white spirit, cyclohexane, cyclohexylamine, ethyl dichlorothiophosphate, ethyl mercaptan. IIA T4 Acetaldehyde, isobutyric aldehyde, butyraldehyde, propionic aldehyde, decane, tetramethyldiaminomethane, 1,1,3-triethoxybutane T5 - T6 - IIB T1 Coke oven gas, hydrocyanic acid T2 Civinyl, 4,4-dimethyldioxane, dimethyldichlorosilane, dioxane, diethyl dichlorosilane, camphor oil, acrylic acid, methyl acrylate, methyl vinyl dichlorosilane, acryl nitrile, nitrocyclohexane, propylene oxide, 2-methylbutene-2 oxide, ethylene oxide, 3-ethylene oxide, solvent , trimethylchlorosilane, formaldehyde, furan, furfural, epichlorohydrin, ethyl trichlorosilane, ethylene. IIB T3 Acrolein, vinyl trichlorosilane, hydrogen sulfide, tetrahydrofuran, tetraethoxylan, triethoxysilane, diesel fuel, formalglycol, ethyl dichlorosilane, ethyl cellosolve. T4 Dibutyl ether, diethyl ether, ethylene glycol diethyl ether T5 - T6 - IIC T1 Hydrogen, water gas, luminous gas, hydrogen 75% + nitrogen 25% T2 Acetylene, methyldichlorosilane T3 Trichlorosilane T4 - T5 Carbon disulphide T6 -

During operation, in the event of explosion of the mixture resulting from sparking, pressure acts on the walls of the housing 1 of the flameproof enclosure, the value of which, depending on the geometric parameters of the enclosure, ranges from 5 to 20 atm. Such pressure can lead to a violation of the integrity of the housing 1, covers, hatches and the spread of the explosion outside the flameproof enclosure. When applying the ballistic layer 3, part of the explosion energy is absorbed, which can significantly reduce the pressure inside the flameproof enclosure.

When installing explosion-proof equipment in an area with an operating temperature below -20 ° C, an increase in pressure occurs. So, for example, according to GOST

- at -20 ° С≥t≥ -30 ° С the pressure increases by 37%;

- at -30 ° С≥t≥ -40 ° С the pressure increases by 45%;

- at -40 ° С≥t≥ -50 ° С the pressure increases by 53%;

- at -50 ° C≥t≥ -60 ° C the pressure increases by 62%.

For the manufacture of enclosures of flameproof enclosures, injection molding technology is used. After casting, the body is cleaned of ebbs, its surfaces are processed.

After drilling the holes on the inner surface of the housing and the cover, a pre-prepared ballistic material made with damping layers is applied. After the completion of the process of its application, including curing of the material and drying of the glue, cuts are made in the ballistic material for holes for cables and cable entries. Then, a mounting panel is installed in the housing 1 of the flameproof enclosure, if necessary, and, for example, electrical equipment 2 is mounted on it, which can be intrinsically safe with a high degree of protection, or with parts that sparkle during normal operation. In the holes drilled in the flameproof enclosure, controls are installed, such as buttons, pens, machines, etc., and cable or pipe entries. After the installation of equipment 2 in the internal cavity of the flameproof enclosure, all electrical wires are connected to the connectors, clamps and terminals and laid through sealed inlets / outlets equipped with sealing elements. Further, the covers and hatches, also equipped with sealing devices, are closed and pulled together with bolts with the housing 1.

The reduction of explosive effects, in particular the determination of the pressure of the explosion inside the flameproof enclosure using the claimed invention, is illustrated by the following experimental tests. The experimental tests consisted of spark ignition with a voltage of 24 V and a current of 0.5 A of explosive mixtures - hydrogen (IIC) and ethylene (IIB), inside a flameproof enclosure at atmospheric pressure and ambient temperature, and in the subsequent measurement of the pressure arising from the explosion. The width of the flameproof slots was chosen within the tolerances, while the slit length was 12.5 mm and the maximum gap was 0.15 mm.

Combustible gases used to produce explosive mixtures in experimental tests, their content in a mixture with air and the corresponding number of experiments are shown in Table 2. The experiments were carried out with groups (subgroups) of electrical equipment established by the relevant GOSTs.

table 2 Group or subgroup of electrical equipment
niya Explosion Pressure The number of experiments Flammable gas and its content in an explosive mixture I 3 Methane (9.8 ± 0.5)% IIA 3 Propane (4.6 ± 0.3)% IIB 3 Ethylene (8.0 ± 0.5)% IIC 5 Hydrogen (31.0 ± 1.0)% 5 Acetylene (14.0 ± 1.0)%

An explosive mixture inside the shell was ignited by one or more high-voltage spark plugs or other low-energy ignition sources.

Explosion pressure was measured and recorded during each test, the test results are shown in table 3.

Table 3 Flammable gas and its content in an explosive mixture Experience Number Explosion pressure, bar Ambient temperature, ° С Atmosphere pressure Hydrogen (31.0 ± 1.0)% one 3.61 + 21 ° С 743 mmHg 2 3.3 3 3.35 Ethylene (8.0 ± 0.5)% four 3.33 5 3.31 6 3.28 Explosion pressure without ballistic material 7.9 bar

As can be seen from the test results, the use of ballistic material reduces the explosion pressure by more than 2 times.

The location of the spark plug or spark plugs and the instrument or instruments for measuring pressure was determined by the test organization. As the calculated explosion pressure, the maximum value set using pressure sensors located in several places of the housing was taken. For testing used samples from a typical batch of equipment. If the internal volume of the shell was less than 30% filled with electrical equipment, then in this case the enclosure of the flameproof enclosure was completely freed from internal filling (electrical equipment). If the internal volume of the flameproof enclosure was filled with electrical equipment by 30% or more, then tests were carried out together with the electrical equipment installed in it, since the process of explosion and shock wave formation in this case is different. The localization of the explosion in the shell with the electrical equipment tightly installed in it is not always predictable, and it is possible to superimpose the shock waves arising and reflected from the walls of the enclosure of the flameproof enclosure and the appearance of resonance phenomena in wave formation, as a result of which the effect of the explosion pressure on the walls of the shell increases.

The use of the claimed group of inventions allows you to create a flameproof enclosure with high reliability, improved overall dimensions and the ability to use equipment installed inside it at low temperatures.

Claims (12)

1. The method of limiting explosive effects, based on the localization of equipment in a flameproof enclosure, in which a protective layer is created, characterized in that the protective layer is formed on the inner surface of the flameproof enclosure from ballistic material made with damping layers, while the outer layers are applied to the damping layers made of metal foil. 2. The method according to claim 1, characterized in that as the ballistic material used fabrics or hybrid materials or mesh materials that do not support combustion. 3. The method according to claim 1, characterized in that the plasticine that does not support combustion is used as a ballistic material. 4. The method according to claim 1, characterized in that as the ballistic material using materials based on glass or carbon fibers, or polymers or composites that do not support combustion. 5. The method according to claim 1, characterized in that as a ballistic material using a film of high pressure polyethylene, made with a bubble coating. 6. The method according to claim 5, characterized in that the bubble coating is created by welding to a substrate made of a flat film material, a layer of polyethylene with bubbles. 7. An explosion-proof enclosure containing a housing with a lid, inside of which equipment is installed, characterized in that ballistic material made with damping layers is applied to the inner surface of the housing and lid, while the outer layers of the ballistic material are made of metal foil. 8. The flameproof enclosure according to claim 7, characterized in that the housing and cover are made of metal or alloys, or of polyester or polypropylene. 9. The flameproof shell according to claim 7, characterized in that the housing and the cover are made with reinforcement. 10. Flameproof enclosure according to claim 7, characterized in that the housing and the cover are connected by screws. 11. Explosion-proof casing according to claim 7, characterized in that the housing has openings provided with seals. 12. Explosion-proof shell according to claim 7, characterized in that it is equipped with a mounting panel made with the possibility of mounting equipment.

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