Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D1/00—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62C—FIRE-FIGHTING
  • A62C3/00—Fire prevention, containment or extinguishing specially adapted for particular objects or places
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D1/00—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires
  • A62D1/0028—Liquid extinguishing substances
  • A62D1/005—Dispersions; Emulsions
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
  • E21F15/00—Methods or devices for placing filling-up materials in underground workings
  • E21F15/005—Methods or devices for placing filling-up materials in underground workings characterised by the kind or composition of the backfilling material

Definitions

• Coal mines have always been a security problem. Some unexploited mines have burned for centuries. However, the number of fires has risen sharply since coal mining for steel or energy production.
• coal fires are also common on the surface: heaps of fines or silos, especially in the presence of high sulfur coal.
• the third country is India where fires began in the 18th century.
• the Jharia mine is the world's largest mine fire where the fire began in 1916.
• Water in the bottom of the mine can also vaporize and create explosions due to pressure.
• the dense foam filled with inert gas has a relatively high flow slope and allows by injection, to plug horizontal galleries reducing horizontal transfers of oxygen. But the foam has no extinguishing effect because it does not contain enough water to cool the walls. The foam actually disappears at relatively low temperatures (50 to 80 ° C). In the case of sludge injection, for example bentonites, the sludge tends to flow like water and to separate at the bottom of the wells. In addition, their flow slope, very low, does not allow the closure of horizontal galleries.
• the polymers have been used as binders and water maintainers for the production of gels or mineral pastes containing silica, kaolin, bentonite, fly ash, various sludge, ... which serve to seal the air in the burning coal mines.
• the objective of the invention is therefore to develop a method of extinguishing coal mine fires combining the following characteristics:
• Injection fluid flow slope to obstruct horizontal galleries
• the Applicant has developed a method to solve all of these problems by using superabsorbent (SAP) or (co) polymers with a high rate of swelling in water.
• SAP superabsorbent
• these polymers are crosslinked.
• the polymers according to the invention are injected in the form of partially or totally swollen superabsorbents, contrary to the prior art.
• water-soluble, cross-linked, or cross-linked, natural or synthetic polymers polyvinyl alcohol, guar, alginates, carboxymethyl cellulose, dextran, xanthan, polyethylene oxide, etc.
• Superabsorbents are polymers well known in specialty chemistry. They are usually in the form of powder. Their structure based on a three-dimensional network assimilable to a multitude of small cavities each having the ability to deform and absorb water gives them the property of absorbing very large quantities of water and thus inflating .
• Such polymers are described, for example, in patent FR 2 559 158 in which crosslinked polymers of acrylic or methacrylic acid, crosslinked graft copolymers of polysaccharide type / acrylic or methacrylic acid, crosslinked terpolymers of the acrylic or methacrylic acid / acrylamide / sulfonated acrylamide type and their alkaline earth or alkaline metal salts.
• these polymers have for their main characteristic a high capacity to swell in an aqueous medium. They can absorb and retain large amounts of water up to 100 times or more their mass. They are used especially in agriculture to retain water in the soil, in baby hygiene products intended to contain urine and similar applications.
• the subject of the invention is therefore a method for extinguishing fires of coal mine wells consisting of:
• the polymers are chosen from the group comprising:
• crosslinked copolymers obtained by polymerization of acrylamide and partially or totally salified acrylic acid, preferably in the form of a sodium salt,
• crosslinked polyacrylic acids partially or totally salified, preferably in the form of a sodium salt, which is more sensitive to the salinity of water and in particular to Ca 2+ and Mg 2+ .
• the polymers are crosslinked copolymers of acrylamide and partially or totally salified acrylic acid and contain between 40 and 90 mol% of acrylamide and between 10 and 60 mol% of acrylic acid partially or totally salified.
• the SAP is a crosslinked terpolymer obtained by polymerization of acrylamide and / or partially or totally salified acrylic acid and / or partially or completely salified ATBS (acrylamido tert-butylsufonate) and / or NVP. (N vinylpyrrolidone).
• SAP is partially or fully inflated.
• a fully inflated SAP is characterized by the fact that all the small cavities of the three-dimensional network are filled with saturation water, ie at a level such that by adding additional water, the SAP no longer absorbs water additional.
• the polymers are crosslinked with 100 to 6000 ppm of at least one crosslinking agent chosen from the group comprising acrylic compounds, for example methylenebisacrylamide, allylic compounds such as, for example, tertraalylammonium chloride, vinylic compounds, for example divinylbenzene, diepoxy, metal salts ...
• a crosslinking agent chosen from the group comprising acrylic compounds, for example methylenebisacrylamide, allylic compounds such as, for example, tertraalylammonium chloride, vinylic compounds, for example divinylbenzene, diepoxy, metal salts ...
• Polyacrylamides have the ability to produce swollen SAPs that are stiffer and less sensitive to divalent metals than polyacrylates.
• the water used to swell the polymer is the least saline possible, and this, to obtain the maximum swelling of the SAP for a given amount.
• the water preferably contains less than 200 g / l, very preferably less than 100 g / l of salts, for example NaCl, CaCl 2 or MgCl 2. For this purpose, it can be treated by reverse osmosis.
• SAPs When SAPs are inflated, the SAP flow slope varies depending on the initial particle size of the SAP. With a particle size less than 1 mm (less than about 5 mm inflated), the flow slope is of the order of 10 °. With a particle size less than 4 mm (less than 1.5 cm inflated), the slope can reach 15-20 °. It is therefore possible to plug galleries simply by injection.
• the stored water evaporates and the polymer is burned. But for 1 gr of polymer, 100 g of water were evaporated, ie an energy absorption of 226 KJ to which it is necessary to add the temperature rise heat of the water vapor generated at 400-600 ° C. For example, with a flow rate of 1000 1 / minute, 4000 MJ / min can be eliminated compared to the heat of combustion of 1 liter of gas oil of 36 MJ.
• the inflated superabsorbent therefore has both a mechanical effect like a rigid foam, and a thermal effect such as water which has a formation of water vapor of 1.7 m 3 per liter of evaporated water, and whose vapor does not dissociate in oxygen and dihydrogen, explosively, not before 1600 ° C. In addition, it can deform according to the movements of ground maintaining their shutter function.
• the inflated SAP is prepared in a fire-free zone thus avoiding any dangerous handling near the flames.
• the inflated SAP is then transported and then injected by pressure or pipeline truck.
• the partially or fully inflated SAP can be formed continuously or batchwise.
• SAP is injected at the wellhead, horizontal or vertical vertical or surface cracks.
• the invention also relates to an installation implementing the method described above and comprising:
• the means for mixing the water and the superabsorbent (co) polymer is in the form of two successive tanks allowing continuous and homogeneous swelling of the superabsorbent.
• Figure 1 is a representation of an installation implementing the method of the invention according to a first embodiment.
• FIG. 2 is a representation of an installation implementing the method of the invention according to a second embodiment.
• the superabsorbent is delivered in big bags of 750 to 1000 kg, in containers of 2 to 5 tons (1) (see figure 1) or in tanker truck (1) (see figure 2) then stored in a hopper or a silo ( 2). It is dosed by a screw feeder (3) in a continuous system with 2 tanks (4, 5) equipped with a powerful agitator (6, 7) propeller or spiral.
• the superabsorbent (1) and the water (8) are dosed in the first swelling chamber (4), the water being in excess of the swelling of the (co) polymer (eg 1200 liters per hour for 10 kg swelling 100 times), which allows more efficient agitation.
• the required residence time depends on the particle size and is between 1 hour (less than 1 mm) and 3 hours (less than 4 mm).
• the second tank (5) works with a high level low level stopping the screw feeder (3) and the water inlet (8) high point.
• the inflated SAP is pumped either by means of a Moineau type pump (9) up to pressures of about 10 bar and by means of a piston pump up to 200 bar.
• the inflated SAP is then injected by means of an injection nozzle (10) at the wellhead or in horizontal or vertical vertical or surface fissures.

Landscapes

• Emergency Management (AREA)
• Business, Economics & Management (AREA)
• Chemical & Material Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Dispersion Chemistry (AREA)
• Geology (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Public Health (AREA)
• Fire-Extinguishing Compositions (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Fireproofing Substances (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=45688171

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (5)

Family Cites Families (4)

• 2012
  • 2012-01-09 EP EP12704516.9A patent/EP2802385A2/de not_active Withdrawn
  • 2012-01-09 RU RU2014125244A patent/RU2014125244A/ru unknown
  • 2012-01-09 AU AU2012202891A patent/AU2012202891A1/en not_active Abandoned
  • 2012-01-09 WO PCT/FR2012/050050 patent/WO2012063009A2/fr not_active Ceased
  • 2012-01-09 CN CN201280061971.6A patent/CN104428038A/zh active Pending
  • 2012-01-09 CA CA2858655A patent/CA2858655A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events