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
  • C10L5/00—Solid fuels
  • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
  • C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
  • C10L5/10—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders
  • C10L5/14—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders with organic binders
• • 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
  • C10L5/00—Solid fuels
  • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
  • C10L5/04—Raw material of mineral origin to be used; Pretreatment thereof

Definitions

• the common binders for hard coal briquettes are pitch and bitumen. Because briquettes with these binders do not burn without smoke and soot and break down too quickly due to softening of the binder, so that unburned coal falls through the grate, there has been no lack of attempts to improve hard coal briquettes by choosing other binders.
• a new briquette that meets the requirements of the home fire market from a comfort fuel must have good loading, weather resistance and fire resistance, it should burn free of smoke and soot and the combustion tax must be free of pollutants.
• Loading strength means that the briquettes are so strong about 20 minutes after being pressed that they can withstand the mechanical stresses when loading them into wagons, buckets, trucks and the like. have grown without breaking.
• This strength in the cold state should increase with a greater time interval from the pressing, but in no case should it drop noticeably again, in order to ensure that briquettes are resistant to trade and consumers.
• the weather resistance indicates whether and to what extent the briquette strength can decrease due to the influence of air humidity and precipitation when stored outdoors. If it also increases again due to drying, for example due to solar radiation, it should not, however, fall below a point pressure resistance according to DIN 23081 of 50 kg.
• the stability of the briquettes in the fire is ultimately the goal of any briquetting. Since fine-grained materials such as washed anthracite fine coal, fine coal of any kind and similar fine-grained fuels cannot be burned in domestic furnaces, they are made into pieces by pressing with a binder and are therefore ready for use like nut coal. It would make no sense for the briquettes to fall apart at the start of the combustion and to pass through the grate into the ash pan as unburned material.
• the cold strength is checked by randomly removing 10 to 50 briquettes from production. Each briquette is loaded according to DIN 23081 between two stamps of at least 15 mm diameter with a stamp feed of at least 8 mm / min until it breaks.
• the breaking load in N is given as the cold strength, the mean of the individual values being formed.
• the stability of the briquettes in water is checked as a measure of the weather resistance.
• 10 briquettes are placed in a water bath. After a dwell time of 15 minutes, they are removed and their strength is immediately tested using the cold strength method. The start of water bathing is the time of the water resistance.
• the heat resistance of the briquettes is examined to determine their stability in the fire. 5 briquettes are used in a muffle furnace heated to 800 ° C and removed after certain time intervals. Then they are loaded on the test press immediately after the cold strength process until they break.
• combustion tests are carried out in the house furnace in accordance with the test regulations of DIN 18 890.
• the ash content is determined using the grate diarrhea.
• the soot-tar number is also identified as an indication of the emission.
• the measurement of the pollutants in the exhaust gases takes place according to the method described by Ahland / Merten in VDI reports No. 358/1980.
• the starch types are the native, but above all the fully gelatinized starches. These are expediently modified by calcium or ammonium sulfamate, as is known from DE-A-33 21 960.
• the starch can be mixed in powder form with the coal and this is then conveniently done before adding the solution of the fully hydrolyzed polyvinyl alcohol.
• the starch is preferably added as an aqueous solution or aqueous suspension before homogenization.
• the use of a hot solution of starch and polyvinyl alcohol is particularly preferred.
• the fully saponified polyvinyl alcohol used in the context of the invention preferably has a viscosity of 8 to 70 mPas, measured in a 4% strength aqueous solution at 20 ° C.
• Fully hydrolyzed is understood to mean a polyvinyl alcohol with a degree of hydrolysis of over 90%, in particular over 95%.
• the combination of polyvinyl alcohol and starch can reduce the proportion of polyvinyl alcohol to amounts of 0.2 to 1.5% without the briquette quality deteriorating.
• the proportion of starch can be reduced to 0.3 to 2%, preferably 0.5 to 1% and that of polyvinyl alcohol to 0.2 to 0.8% if the fine-grained fuel is treated with 5 to 15% before treatment with the binders. , preferably 7 to 13% of a powdered baking coal is added.
• Their grain size is appropriately such that 80% are less than 500 microns.
• the coal has a degree of grinding of d90 below 250 ⁇ m.
• the content of volatile constituents (waf) in the baking coal should expediently be 22 to 29%, even though the baking of the hard coal begins above 15% in volatile constituents (waf).
• the required grain size can be produced by fine grinding or fine screening. It is also possible to use special treatment products such as Use flotation concentrate or dust from filters or screening without further treatment.
• the pulverulent baking coal should be distributed as evenly as possible in the briquetting coal, which is done in particular by mixing the fine-grained fuels dry before adding the binder solution. If, for reasons of environmental protection and due to legal requirements, sulfur incorporation is required, up to 5% calcium oxide, hydroxide or carbonate can be added to the fuel mixture before homogenization.
• Washed anthracite charcoal which was obtained at 100 ° C., was mixed with the amount of powdered native starch given in Table 1 and mixed dry for 3 minutes. When the specified amount of pregelatinized starch was added, it was mixed into the briquetted material in a 13% solution. Independently of this, 1.2 kg of a fully saponified polyvinyl alcohol with a degree of hydrolysis of 98.4 mol% and a viscosity of 56 mPas (commercial product Mowiol 56-98) were dissolved in 8.8 l of water at 95 ° C. This aqueous binder solution was then injected in an amount of 8.35 l / 100 kg of coal at a temperature of 90 ° C. onto the washed anthracite coal, to which the starch had already been added dry or as a solution.
• the loading strength 20 minutes after pressing, was 370 to 620 N, clearly above the minimum value of 300 N to be demanded.
• the final strength was excellent with more than 1300 N. With a soot-tar number of less than 50, the emission value when burning the briquettes fell well below the upper limit of low-smoke fuels of 200.
• the weather resistance was 530 - 910 N (24 hours after pressing), which is quite good.
• a baking coal namely fat coal
• the fat coal was mixed into the intended fine grain size of d90 below 250 ⁇ m in an amount of 10% before the binding agent was added to the briquette coal.
• the results of the tests are shown in Table 2.
• the loading strength 20 minutes after pressing, was significantly above the minimum value of 300 N to be demanded.
• the final strengths were less than 950 N.
• the starch was in suspension form with a solids concentration of approximately 29.5% and was modified with the additive ammonium sulfamate (see patent application DE-A-33 21 960).
• the binder solution consisting of polyvinyl alcohol, starch and water was prepared in such a way that polyvinyl alcohol was first firmly introduced into the starch suspension and then the aqueous mixture was transferred to a common mixed solution in a conventional starch boiling process under pressure and temperature. After the binder solution had been introduced into the briquetting coal, the coal and binder were thoroughly mixed for about 1 minute. The briquetting mixture was dewatered to a water content of about 4.7% and then pressed in a double roller press. The briquetting results are shown in Table 3.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Geology (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Solid Fuels And Fuel-Associated Substances (AREA)

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Publications (3)

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Cited By (8)

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• 1986
  • 1986-07-11 DE DE3623325A patent/DE3623325C2/de not_active Expired - Fee Related
• 1987
  • 1987-06-12 DE DE8787108523T patent/DE3778073D1/de not_active Expired - Lifetime
  • 1987-06-12 EP EP87108523A patent/EP0252332B1/fr not_active Expired - Lifetime

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