Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/32—Liquid carbonaceous fuels consisting of coal-oil suspensions or aqueous emulsions or oil emulsions
  • C10L1/326—Coal-water suspensions

Definitions

• This invention relates to a process for preparing coal-water mixtures.
• ALFRED UNIVERSITY patent 4,282,006 relates to a process for grinding coal in the presence of an anionic surfactant in a ball mill.
• a particular particle size distribution makes it possible to directly obtain highly concentrated coal-water mixtures.
• additives are necessary to prevent the agglomeration of the carbon particles of these concentrated mixtures.
• These additives can be of ionic or nonionic nature. In both cases the additives must coat the carbon particles.
• the non-ionic additives act simply by their steric film-forming effect while the ionic additives confer an electrical charge on the carbon particles. Identical charges repelling prevent AggLomeration of particles.
• the uneven distribution is due to the presence at the start of grinding of large quantities of additives relative to the available surface.
• the specific surface of the carbon grains is still very small, The additive accumulates in several layers on the carbon particles.
• This process consists in gradually adding during grinding the exact quantity of additives corresponding to the specific surface available.
• the effectiveness of the additive is thus greatly increased.
• the viscosity of the coal-water mixture is much lower.
• the quantity of additive required can be halved by adopting the method according to the invention.
• the rate of addition depends on the quality of the coal treated and the conditions of grinding. It is necessary to determine for each quality of coal the evolution of the specific surface as a function of time and to adjust the rate of addition and the amount of the additive to this evolution.
• the amount of additive needed can be reduced. tioned in two, three or more equal or possibly unequal parts, to follow as closely as possible the evolution of the specific surface available. It is also possible to add the additive continuously during the grinding operation.
• the additives can be of ionic or nonionic nature.
• the most effective ionic additives are organic compounds of an anionic nature, and especially polyelectrolytes.
• Polynaphthalene-methane-sulfonates in the form of sodium sets such as LOMAR D by DIAMOND SHAMROCK, SURFARON 1520-N-100, 1540-N-100, 1552-N-100 from PROTEX, STEPANTAN NP 80 from STEPAN or ammonium salts such as SURFARON 1521-A-100 from STEPAN.
• Sodium lignosulfonates such as VANISPERSE CB from BORREGAARD or Ammonium lignosulfonates are also very effective polyLectroLytes.
• sodium salts are more effective than ammonium salts in reducing the viscosity of coal-water mixtures, however sodium will be found after combustion in the ashes, making them more fusible and possibly leading to clinker formation. From this point of view we will prefer to use Ammonium sets.
• Non-ionic additives are polymers having sequentially hydrophobic and hydrophilic parts. They are formed from oxyalkylated chains condensed on alcohols, phenols, or nitrogen compounds. Long chains being more active, they must contain around 100 oxyalkyl units.
• Non-ionic Some of these additives in particular Non-ionic are foaming.
• the foam makes the mixture too thick and disturbs the grinding.
• an anti-foaming additive such as RHODORSIL 426 R, of RHONE-POULENC, a nonionic emulsion of silicone oil.
• ionic or non-ionic additives themselves are used in the concentrations which can vary between 0.01 and 5% by weight.
• the optimum pH of the medium is between 7 and 12. It is adjusted by adding a base in general of sodium hydroxide or ammonia.
• Coal-water mixtures must also be in the form of pseudo-plastic gels with thixotropic behavior. These gels must be viscous enough to keep the carbon particles in suspension but break easily during flow. Their rheological behavior curve must be such that their fluidity increases with time.
• the properties of the gels can be improved by the addition of gelling agents such as xanthan gums, agaragar, hydroxyalkylcelluloses and carboxyalkylcelluloses. 0.02 to 0.04% by weight of these additives are used.
• the process for obtaining coal-water mixtures generally comprises a crushing step and a grinding step.
• coal particles are obtained whose diameters are less than 2 mm.
• This crushed coal is introduced into a ball mill.
• 60 to 85% of charcoal, 15 to 40% of water are introduced, then the additive gradually or continuously or discontinuously.
• the granulometry of the ground coal is between 1 and 200 ⁇ m. Particles larger than 200 ⁇ m are unstable and sediment quickly.
• Particles smaller than 1 ⁇ m are colloidal and give the mixture too high a viscosity.
• the ball mill with a capacity of 5 Liters contains: 1.5 kg of balls with a diameter of 20 mm 0.9 kg of balls with a diameter of 30 mm 1.3 kg of balls with a diameter of 40 mm Grinder and balls are made of porcelain.
• 500 g of coal previously crushed to a particle size of less than 2 mm, 200 g of water and 4.9 g (expressed as active material) of polynaphthalene methane ammonium sulfonate (SURFARON 1521 A 100 from PROTEX) are introduced into the mill .
• the total grinding time is 3 hours at a speed of 65 revolutions / minute.
• the viscosity of the coal-water mixture is measured using a rotary viscometer with coaxial cyclinders - HAAKE RV 100 fitted with a mobile MV.
• the viscosity is 3800 cP at 100 sec -1 .
• a coal-water mixture is prepared according to the same operating mode as in Example 1.
• a coal-water mixture is prepared according to the same procedure as in Example 1, but only 1.225 g of additive is added (SURFARON 1521 A 100 from PROTEX)
• the viscosity is 4100 cP at 100 sec -1 .
• a coal-water mixture is prepared according to the same procedure as in Example 1, but 4.9 g are added.
• sodium polynaphthalene methanesulfonate (SURFARON 1540 N-100 from PROTEX).
• the viscosity is 1430 cP at 100 sec -1 .
• a coal-water mixture is prepared according to the same procedure as in Example 1 but only 1.225 g of the same additive as in Example 4 (SURFARON 1540 N 100 of PROTEX) is added at the start of grinding and 0.612 g of this same additive after 1.5 hours of grinding.
• the total weight of additive added is 1.837 g.
• the viscosity is 1580 cP at 100 sec -1 .

Landscapes

• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Solid Fuels And Fuel-Associated Substances (AREA)
• Liquid Carbonaceous Fuels (AREA)
• Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=9299828

Family Applications (1)

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Cited By (2)

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• 1984
  • 1984-01-04 FR FR8400074A patent/FR2557588B1/fr not_active Expired
  • 1984-12-20 EP EP84402685A patent/EP0148081A3/de not_active Withdrawn
  • 1984-12-21 AU AU37057/84A patent/AU3705784A/en not_active Abandoned
  • 1984-12-21 IT IT24206/84A patent/IT1178790B/it active
• 1985
  • 1985-01-02 GR GR850008A patent/GR850008B/el unknown
  • 1985-01-03 BE BE0/214285A patent/BE901437A/fr not_active IP Right Cessation

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