Classifications

• • 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
  • A62C3/02—Fire prevention, containment or extinguishing specially adapted for particular objects or places for area conflagrations, e.g. forest fires, subterranean fires
  • A62C3/0278—Fire prevention, containment or extinguishing specially adapted for particular objects or places for area conflagrations, e.g. forest fires, subterranean fires by creating zones devoid of flammable material
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F5/00—Dredgers or soil-shifting machines for special purposes
  • E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F5/00—Dredgers or soil-shifting machines for special purposes
  • E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
  • E02F5/14—Component parts for trench excavators, e.g. indicating devices travelling gear chassis, supports, skids

Definitions

• Underground peat fires are very common in some countries such as Russia, Indonesia, Finland, Canada, Sweden, Norway.
• peat very important surfaces are covered with peat. For example: 1.1 million km 2 in Canada, 750,000 km 2 in the Soviet Union, 263,000 km 2 in Indonesia.
• peat fires are common from late summer to early autumn, especially in very dry years (eg 1972 in Russia).
• the surface peat dries up and, by fermentation and auto oxidation, rises in temperature.
• Peat in soil can have very different thicknesses with the following layers:
• Peat fires are very difficult to fight. Most often, trenches are built with shovels and fire is extinguished in these trenches with fire hoses. However, often these trenches are not deep enough and the fire goes under the trench.
• pressurized water of 2 to 6 bar is injected by rods of 1 to 1 m 50 by moving these injection tubes. This only works on low surface and shallow fires.
• the problem is therefore to develop a method to stop the spread of peat fires either as a cure in the event of a fire, or as a preventive measure for the protection of towns or houses. This operation must be fast and cost as low as possible or implemented permanently.
• SAP superabsorbent polymers
• SAP superabsorbent polymers
• these polymers are crosslinked. These are copolymers, terpolymers ... or their mixture and their main characteristic is a high capacity to swell in an aqueous medium.
• Superabsorbents are polymers well known in fine 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 the polysaccharide / acrylic or methacrylic acid type, crosslinked terpolymers of the acrylic acid type are described. or methacrylic / acrylamide / sulfonated acrylamide 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 store large quantities of water up to 100 times or more of their mass in liquid. They are used especially in agriculture to retain water in the soil, in baby hygiene products intended to contain urine and similar applications.
• cross-linked polyacrylamide-type SAPs absorbing 100 to 250 times their volume of water depending on the salinity, are extremely efficient thermal barriers.
• the invention relates to a method for stopping and / or preventing the spread of peat fires comprising:
• the SAPs are partially or totally inflated, that is to say that they are premixed with water and then partially or totally inflated with said water before filling the trench.
• 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 invention therefore consists in using a superabsorbent as a thermal barrier by filling a partially or totally inflated SAP trench.
• This partially or fully inflated SAP is referred to as "solid water” since it can contain up to 99% water.
• the trenches can be dug at high speed using a slicer especially in loose material at a speed of 5 km / hour depending on the width and depth.
• These slicers are of several types:
• Wheeled trenchers (Figure 1) that allow maximum depths of lm 20 / lm 50 with a very narrow passage: 10 to 20 cm.
• Chain slicers ( Figure 2, 3 and 4) can be 8 meters deep on soft ground.
• the width of the trench is dictated by the rigidity of the arm and is at a minimum of 20 to 40 cm, some slicers up to 1 meter and more.
• the width of the trench is between 20 to 40 cm. This width must be minimal to reduce the consumption of superabsorbent. The width can be determined by specific tests.
• the slicers are very different constructions and powers from 50 to 1500 HP depending on the type of soil (soil, rocky soil, limestone, rock, ...), the depth and width of the trench. They are often used in agriculture to bury irrigation pipes. These trenches could be filled with water. Unfortunately in this case, the water percolates and disappears and the walls collapse.
• a thickness of 20 - 40cm superabsorbent partially or fully inflated is sufficient to stop the spread of fire.
• the SAP is not inflated prior to the filling of the trench but is deposited independently of the water. It is then drowned with water that has been added either before or after SAP deposition, which causes partial or total swelling directly in the trench.
• water that has been added either before or after SAP deposition, which causes partial or total swelling directly in the trench.
• it is possible to deposit the polymer at the bottom of the trench and drown it in water.
• it is preferable to have larger particle sizes (less than 4 mm) which allow a better diffusion of the water but with a high swelling time.
• 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.
• the polymers are crosslinked copolymers of acrylamide and partially or totally salified acrylic acid and will 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 terpolymer derived from the polymerization of acrylamide and / or partially or totally salified acrylic acid and / or partially or totally salified ATBS (acrylamido tert-butylsufonate) and / or NVP. (N vinylpyrrolidone).
• ATBS acrylamido tert-butylsufonate
• NVP N vinylpyrrolidone
• the content of ATBS and / or NVP is of the order of 10 mol%.
• Other hydrophilic monomers, but also monomers with hydrophobic characters, may be used to produce the polymers.
• the copolymers are crosslinked with 100 to 6000 ppm of at least one crosslinking agent chosen from the group comprising acrylic (methylenebisacrylamide), allyl (tertra allylamine chloride), vinyl (divinylbenzene), diepoxy and metal salts. .
• the stability of these polymers is several years in the soil. It can be improved by carrying out a double crosslinking with an acrylic crosslinking agent, preferably at a level of 100 to 1000 ppm and an allyl crosslinking agent, preferably at a level of 1000 to 5000 ppm, for example MBA (methylene bis). acrylamide) and tetrallylammonium chloride, which extends the stability of SAP to more than 5 years. Beyond, the swelling decreases as well as the volume occupied by the polymer in the trench. For very acidic media, it is also possible to mix the superabsorbent before swelling with 10 to 20% of calcium carbonate or sodium carbonate. Calcium carbonate is preferred because it does not decrease the swelling of SAP.
• the superabsorbent (co) polymer is inflated in a treatment center and transported by tanker truck to the treatment site.
• the invention also relates to an installation implementing the method described above and comprising:
• the SAPs are partially or fully inflated before filling the trench.
• the installation also contains:
• the means for mixing the water and the polymer is in the form of two successive tanks allowing continuous and homogeneous swelling of the superabsorbent.
• Figure 1 is a representation of a wheeled slicer.
• Figures 2, 3 and 4 are representations of chain slicers according to different embodiments.
• Figure 5 is a representation of the installation of the invention according to a preferred embodiment.
• Figure 1 is a representation of a trencher with wheels for forming trenches of a maximum depth of 1m 20 / lm 50 with a very narrow passage, of the order of 10 to 20 cm.
• Figures 2, 3 and 4 show chain slicers to form trenches up to 8 meters deep on soft ground.
• the width of the trench is dictated by the rigidity of the arm and is at a minimum of 20 to 40 cm, some slicers up to 1 meter and more.
• Figure 5 is a representation of an installation implementing the method of the invention according to a particular embodiment.
• a trencher forms the trench and discharges the embankments into a truck (2).
• a truck (3) injects the swollen SAPs into the trench with a sparrow type volumetric pump (4).
• This truck contains a hopper (5) containing the polymer, a screw feeder (6), two swelling tanks equipped with stirrers (7) for bringing the SAP into contact with water.
• a third truck (8) provides water through a valve and a pipe (9) connecting the truck (8) to the swelling tanks (7).
• a train of trailers towed by a powerful tractor can be put into service, including a swelling trailer, a polymer trailer and a water trailer which will be filled by a large number of trucks.
• the construction of this equipment obviously depends on the service requested.
• the amounts of (co) polymer to be trenched with a width of 20 cm to a depth of 4 meters are 800 liters per meter usually include (moderately hard water) 782 liters of water and 8 kg of polymer.
• the swelling time depends on the particle size of the polymer. For a polymer of particle size less than 1 mm, it is about 1 hour. Larger particle sizes smaller than 4 mm are sometimes preferred with a longer deflation time (about 3 hours). It is possible to inject non-fully swollen copolymers which end up swelling in the trench with an excess of water.

Landscapes

• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Structural Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Civil Engineering (AREA)
• Mechanical Engineering (AREA)
• Public Health (AREA)
• Biodiversity & Conservation Biology (AREA)
• Business, Economics & Management (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Forests & Forestry (AREA)
• Ecology (AREA)
• Emergency Management (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Fire-Extinguishing Compositions (AREA)
• Soil Conditioners And Soil-Stabilizing Materials (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Cultivation Of Plants (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Applications Claiming Priority (1)

Publications (2)

Family

ID=45592743

Family Applications (1)

Country Status (7)

Families Citing this family (5)

Family Cites Families (23)

• 2012
  • 2012-01-09 CN CN201280064620.0A patent/CN104010700B/zh active Active
  • 2012-01-09 WO PCT/FR2012/050048 patent/WO2012063008A2/fr not_active Ceased
  • 2012-01-09 AU AU2012202890A patent/AU2012202890B2/en active Active
  • 2012-01-09 CA CA2859477A patent/CA2859477C/en active Active
  • 2012-01-09 US US14/369,131 patent/US10188883B2/en active Active
  • 2012-01-09 EP EP12703862.8A patent/EP2802386B1/de active Active
• 2014
  • 2014-06-13 IN IN1205MUN2014 patent/IN2014MN01205A/en unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events