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

• the present invention relates to a method for producing a combustible mixture of coal and water, it relates in particular to a mixture of finely ground coal, water, a wetting or dispersing agent and a suspending agent.
• the additive consists of a suitable surface treatment agent in combination with a gel-forming clay as a suspending agent.
• DE-A-29 42 122 describes a suspension of coal dust in heating oil, the suspension also being stabilized using gel-forming clay as a suspension medium.
• US Pat. No. 4,062,694 describes the use of attapulgite clay as a suspending agent for coal dust in combustible liquid hydrocarbons for the formation of heating materials which facilitate the removal of fly ash from the combustion device after combustion.
• U.S. Patent 239,859 also describes an attempt to partially replace oil with coal to create a composite fuel.
• the problem with the oil-coal mixtures is that they still contain heating oil in as large a proportion as 50 to 70%.
• the invention seeks to remedy this.
• the invention as characterized in the claims, achieves the object of specifying a method for producing a fuel which enables the use of powdered coal without the addition of heating oil, while at the same time creating a stable and cost-saving fuel composition.
• the fuel composition created according to the method according to the present invention consists of a mixture of coal, water, wetting or dispersing agent for the coal and a suspending agent for stabilizing the sludge.
• the coal is present in the mixture in an amount of 65 to 70%, the wetting or dispersing agent is used in smaller, functional percentages.
• the suspending agents used are colloidal clays which show gel-forming properties in the water which forms the rest of the composition.
• the method according to the invention describes the composition of a new fuel with the above-mentioned components.
• the upper limit of the particle size is determined by what burns in the flame (approximately a grain size with a clear mesh size of 0.18).
• the amount of coal that can be incorporated into a slurry of coal in water depends on the grain size distribution, the structure of the particles and the dispersant used. Grain size distribution and particle shape can be accomplished during dry processing or by post processing the slurry with one of the conventional wet grinders to achieve a change in grain size distribution and grinding of the particle shapes.
• a gel-forming agent that imparts gel-forming properties to the water phase is required for any medium or long-term stability.
• the dispersing or wetting agents which are effective in the context of the invention foam little or not at all in water, have a structure which consists of an organic half which absorbs the surface of the coal more than water and a charged hydrophilic part which is lyophilic in relation to the water phase is. These agents are used in low concentrations and accumulate at the coal-water interface. They displace air and water, allow the carbon agglomerates to flocculate with gentle stirring and charge the carbon particles so that the viscosities are low.
• Stabilizing agents by means of which the carbon powder is kept in suspension in the water phase, act through the gelation thereof.
• the water phase transformed into a gel plus the suspended coal should have a gel strength which reversibly breaks up under shear, so that the coal / water mixture, also referred to below as C / WM, can be pressed through a burner nozzle to form a combustible spray .
• the yellowing agents used are colloidal clays such as bentonite, attapulgite, sepiolite montmorrilonite.
• the resulting predispersion is thin and pourable and can be added to the water of the coal / water mixture before the coal is added.
• montmorillonite can be used up to 30% by weight.
• Sepiolite can be prepared in a mixture in a similar way to the predispersed attapulgite.
• Bentonite is predispersed using 0.5% TSPP in an amount of 10% by weight.
• the coal / water mixtures containing flocculated pre-dispersed clays are very stable and have a higher gel strength than those containing pseudoplastic gels made from dry clays.
• hydrocolloids are used as stabilizers, they are introduced in the conventional manner known to the person skilled in the art.
• Typical spinning compositions are:
• Pregele are added to the coal / water slurry in the form of the desired aliquot to the water or to the finished mixture.
• the predispersions are prepared by dissolving TSPP in water in a mixing tank, adding the clay while stirring and continuing the stirring process until it is dispersed.
• the predispersions can be added early or late in the course of the C / WM process, but are generally added before the coal.
• Common dispersants are tetrasodium pyrophosphate, sodium tripolyphosphate, condensed phosphate-containing dispersants, and other polyanionic organic dispersants that act as dispersants in clays.
• Aluminum, magnesium and calcium montmorillonites of the non-swelling types can be used as stabilizers in the context of the invention. They cannot be added dry or pre-gelled because they develop a low viscosity, but they form gel structures and therefore a certain viscosity if they are added predispersed.
• a typical predispersion has the following composition:
• This predispersion is prepared and added in the same way as the other predispersions.
• All pre-dispersed clay-stabilized coal / water mixtures should be checked whether a neutralizer is required for the dispersant. If very clean coal is used and the viscosity and gel strength of the finished C / WM is low, neutralizers such as hydrated lime, ammonium nitrate, aluminum sulfate etc. can be added to the finished mixture to thicken it by flocculating the clay component.
• neutralizers such as hydrated lime, ammonium nitrate, aluminum sulfate etc. can be added to the finished mixture to thicken it by flocculating the clay component.
• the efficiency of the use of clay for stabilizing the suspension is usually: predispersed> pre-gelled>> dry additive.
• Example 2 If attapulgite is added, as shown in Example 2, the slurries become thicker (2A, 2B and 2C), but the clay stabilizes lower coal concentrations in water according to approach 2D.
• Example 5 Since usually predispersed attapulgite as a suspending agent is far more effective than dry clay, a 25% predispersion was prepared and examined in conjunction with a 70% coal slurry, shown in Example 5. The amounts of clay are based on predispersed clay and must therefore be divided by 4 to get the dry clay content.
• Example 5 If one looks at the batches and the results according to Example 5, it is found that the amount of predispersed clay required to stabilize a 70% coal slurry is substantially reduced compared to the values shown in Example 4, the 0.75% predispersed clay of the Approach 5A actually corresponds to 0.19% dry clay.
• Raylig 260 LR plus pre-dispersed clay produce batches that thicken when stored. Batches with Lomar D, Lomar PW and Darvan 1, all sodium sulfonate salts of condensed naphatlin formaldehydes, plus predispersed clay show good viscosities and stabilities.
• Example 6 In order to show the effect of the finishing of these slurries, a larger amount of batch F from example 5 was produced. It was then worked for 5, 10 and 15 minutes in a ball mill as in Example 6.
• Montmorillonite of the non-gelling type can also be used to stabilize the coal / water mixture. To show this, a 30% predispersion of montmorillonite was made in the known manner. The predispersion was applied to a 70% coal slurry.
• a stable 70% coal in water slurry is used by using dispersants based on lignin sulfonate in the amount of 1 to 5% or sodium salts of sulfonated naphthalene formaldehyde condensates in the amount of 0 , 5 to 2% plus attapulgite in dry, predispersed form or non-gel-forming montmorillonite can be produced as a stabilizer.

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)
• Liquid Carbonaceous Fuels (AREA)
• Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)

Applications Claiming Priority (2)

Publications (3)

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• 1981
  • 1981-05-15 US US06/263,810 patent/US4432771A/en not_active Expired - Lifetime
• 1982
  • 1982-05-11 DE DE8282104067T patent/DE3269578D1/de not_active Expired
  • 1982-05-11 EP EP82104067A patent/EP0065259B1/de not_active Expired
  • 1982-05-14 CA CA000403001A patent/CA1190742A/en not_active Expired
  • 1982-05-14 JP JP57081364A patent/JPS5823890A/ja active Granted

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