RU2197620C1 - Method of inert medium formation in mine workings - Google Patents

Abstract

FIELD: fire fighting, making insert and cleaning of atmospheric in blind gassy and dusty mine workings. SUBSTANCE: method includes preliminarily conversion of cryogenic fluid in heat exchanger into vapor-liquid state. Then one part of mixture is evaporated in evaporator and supplied in the form of gas to special labyrinth of cyclone swirler to swirl it, and aerosol of its other vapor-liquid part is injected from header to swirling mass. At the same time, cooled water is dispersed into finely divided vapor-drop mist with the help of gas flow from pipe and capillary-perforated head. Formed finely divided suspension is introduced into zone of low pressure of swirl flow where suspended particles are instantly frozen to form snow crystals. EFFECT: increased labor safety in mine workings, reduced material and labor expenditures in performance of mine rescue operations. 2 cl, 1 dwg

Description

 The invention relates to mining and can be used to extinguish underground fires and inertize mine deadlock workings, dangerous for gas and dust.

 A known method of producing an inert foam for extinguishing a fire, comprising introducing liquid nitrogen into a foaming solution together with a fire extinguishing powder and distributing the powder in the central part of the liquid nitrogen stream (ed. Certificate USSR 1180005, class A 62 C 1/12, 1984).

 The disadvantage of this method is associated with high economic costs, especially in conditions where there is no need to use expensive powder.

 There is also a method of creating an inert environment in mine workings, including preliminary cooling of the bottomhole space of the mine by feeding cryogenic liquid into it and subsequent spraying of water in the bottomhole space to form a snow mass (RF patent 2001284, class E 21 P 5/00, 1991).

 The disadvantage of this method is the low efficiency of snow formation. This is due to the fact that such a method - first, cooling the bottom-hole space, and then spraying water into it, does not provide for the rapid freezing of suspended drops due to the high heat capacity of the water. In this case, the bulk of the dispersed water in suspension is frozen into an ice hail without the formation of snow crystals. The city, falling on the soil of a mine in places where water is sprayed, freezes into ice, which, due to its less developed surface compared to the snow mass, adsorb and bind explosive dust and gas particles contained in the atmosphere of a mine much worse. All this leads to a rapid decrease in the efficiency of inertization.

 The purpose of the invention is to increase the efficiency and reliability of the inertization of the atmosphere of the bottomhole space of a dead end mine.

 The essence of the method of creating an inert atmosphere in mine workings hazardous for gas and dust, including the formation of a snow mass in the bottomhole space by feeding cryogenic liquid and dispersed water into the bottomhole space, is that before feeding into the bottomhole space a cryogenic liquid is transferred to a vapor-liquid aerosol state and untwist in a vortex cyclone with the formation at its center of the zone of reduced pressure, which serves dispersed water to bring it into a state of vapor-droplet fog. In this case, liquid nitrogen is used as a cryogenic liquid.

 Using the proposed method will make it possible to obtain a large mass of snow crystals. Introducing into the atmosphere of mining, they gradually settle, adsorbing and collecting coal dust and methane molecules on their surface. This leads to the purification and inertization of the air environment of the bottomhole space and a quick reduction in the risk of fire and explosion.

 The drawing shows a schematic diagram of a device for implementing the proposed method.

 The device comprises a tank 1, for example, of the type RCV-0.5 / 1.6 for transporting and storing cryogenic liquid, mainly liquid nitrogen, a control valve 2, a heat exchanger 3 for converting the cryogenic liquid into a vapor-liquid state, shut-off valves 4 and 5 and a water evaporator 6. Water is supplied to the sealed housing 7 of the evaporator 6 through the valve 8 from the main water supply 9. The main part of the device is a cyclone swirler 10, which contains ring collectors 11 and 12 with tangentially located and oriented in one side by nozzles 13. Inside the wide cylindrical part of the cyclone swirler 10, a spiral labyrinth 14 is placed, and on its central axis there is a water pipe 15 with a capillary-perforated tip 16. In this case, the pipe 15 is placed coaxially inside the pipe 17 which is muffled from the outer end.

 The method is implemented as follows.

Liquid nitrogen from the tank 1 is fed into the heat exchanger 3. In this case, by means of the control valve 2, the required flow rate of liquid nitrogen is established. In the heat exchanger 3 due to heat exchange with the air, the liquid nitrogen is heated to a temperature of 100-150 ^o C and its partial evaporation with the transition to the vapor-liquid state. Next, the vapor-liquid nitrogen stream is separated. One part of it enters the evaporator 6, and the other through the valve 5 is fed into the annular collector 12. In the evaporator 6, due to the heat of water, which is supplied to the housing 7 through the valve 8 from the main water supply 9, liquid nitrogen completely evaporates and passes into a gaseous state, and the water cools. At the outlet of the evaporator 6, cold nitrogen gas is directed to the annular collector 11 and flows through the tangentially located nozzles 13 under pressure into the channels of the spiral labyrinth 14, where it is unwound into a vortex stream, while shifting along the labyrinth spirals 14 to exit the cyclone swirler 10. At the same time, a vapor-liquid mixture of nitrogen is sprayed as an aerosol from the collector 12 into an untwisted nitrogen gas stream. In the narrowed part of the cyclone swirler body 10, the resulting gas-vapor mixture acquires even greater kinetic energy of vortex rotation.

 In this case, due to centrifugal forces, a zone with a reduced pressure (rarefaction zone) is formed in the central part of the vortex, which leads to a more intensive evaporation of drops of liquid nitrogen and a sharp decrease in the temperature of the central part of the vortex. The end of the pipe 17 is introduced into the rarefaction zone, into which gaseous nitrogen is supplied under pressure through a branch pipe with a valve 4. In the center of the pipe 17, a water pipe 15 is coaxially placed therein. Chilled water enters from the casing 7, which is sprayed through the capillary-perforated tip 16 into the end of the pipe 17. Here the fine-dispersed suspension of water is picked up by the gas stream existing in the pipe 17, crushed by it to the smallest droplets and is carried out into the central rarefied and coldest part of the vortex flow. At the outlet of the pipe 17, the water-gas stream is cooled even more due to adiabatic expansion. In this case, the suspended fine particles of water in the zone of reduced pressure turn into a state of droplet fog and instantly freeze with the formation of ice crystals in the form of snowflakes. The resulting snow is ejected from the cyclone swirler 10 by a common gas-vapor flow of nitrogen into the air of a mine. The resulting mass of snow crystals, due to a well-developed surface, captures and binds suspended coal dust and adsorbs methane molecules, converting it to a bound crystalline hydrate state. Falling out onto the soil of a mine, the snow mass cleans the atmosphere of explosive dust and gas particles well and can be removed from the bottom hole by conventional mechanical means.

 The proposed technical solution allows to increase labor safety in mining, characterized by a large output of gas and dust, and to reduce material and labor costs for mining operations.

Claims (2)

 1. A method of creating an inert atmosphere in mine workings hazardous for gas and dust, including the formation of a snow mass in the bottomhole space by feeding cryogenic liquid and dispersed water into the bottomhole space, characterized in that before feeding into the bottomhole space, the cryogenic liquid is transferred to a vapor-liquid aerosol state and untwist in a vortex cyclone with the formation at its center of the zone of reduced pressure, which serves dispersed water to bring it into a state of vapor-droplet umana.  2. The method according to p. 1, characterized in that liquid nitrogen is used as a cryogenic liquid.