SE436285B - WAYS TO PREVENT SELF-IGNITION AND DAMAGE EXPLOSIONS WHEN HANDLING A POWDER-SHEET POWDER FUEL - Google Patents

Description

8207128 -3 het. Most such known treatment processes relate to the manufacture of briquettes and the like for combustion and examples of such processes can be found in DE-B-103,509 (de Faucheux d'Humy), US-A-1,546,785 (Illemann), DE-B- 972,171 (Zdralek) and GB-B-352,542 (Rudeman).

As an example, DE-B-972,171 (Zdralek) describes a method of converting peat into a carbonaceous product by atomization and addition of an electrolyte and other coagulants.

DE-B-22 54 150 (Sebreg) describes a method of making fiber granules from natural or synthetic, non-moistened fibers in the form of fiber aggregates with low cohesion by applying a liquid to the upper side of the aggregate, so that between fibers, liquid membranes are formed which, after evaporation or evaporation of the liquid, provide enhanced cohesion between the fibers.

SE-B-45,474 (Torfoleum GmbH) describes a method of producing a building material from dy or peat by adding chlorides of polyvalent metals. None of these publications, which thus describe known methods, deal with the above-mentioned problem, namely to eliminate the risk of self-ignition and dust explosions in the case of a powdered peat fuel.

SU-A-28620 D / 16 (Belo Peat Inst) describes a method for determining the risk of self-ignition of powdered peat by heating a sample under anaerobic conditions to 900 ° C and then performing observations on these samples. Accuracy is improved by treating the peat powder with a mixture of different acids at 80-90 ° C. This procedure only allows a calculation of the risk of self-ignition after different lengths of storage. However, no solution to the problem of avoiding self-ignition and dust explosions is proposed.

Addition of oil to peat, coal and other fuels has also previously occurred with e.g. the following purposes: 1. To facilitate dewatering of raw peat, the peat 8207128-3 can first be treated with various acidic or basic materials, so that the oleophilic properties of the peat are strengthened. By then adding oil or tar, which is absorbed into the peat, the water is displaced and the dewatering is facilitated. This oil preparation is done on dewatered peat with non-decomposed particles, cf. SE-B-110,996 (Engel et al.). Substances other than oil can also be added to peat to facilitate drainage and finishing such as. briquetting, cf. SE-B-59,991 (Society for Mechanical Pressure Dispensing) and SEwB-103,674 (Separator). 2. Heavier oils and tar can be used as binders when briquetting e.g. turf, cf. BE-B-103,509 (de Faucheux d'Humy). In this case, oil or tar is added in such a large amount that the heated mass becomes viscous; the mass is then poured into molds and cooled into briquettes.

Each briquette then consists of a definite solid mass, where the original particles are fixed to each other.

A similar briquetting process is also described in UK-B-352,542 (Rudeman). In both cases, the oil or tar acts as a form-retaining and bonding agent in the cold, solidified state. 3. Fuels with a low content of volatile constituents are often difficult to ignite, which can cause problems during combustion.

By adding oil, preferably a lighter oil such as diesel oil or kerosene, the content of volatile constituents is increased, and the flammability is improved. DE-B-27 11 082 (Shell) describes an example of this. 4. When handling briquettes, pellets, etc., dust may come loose from the briquette or pellet surface, since the surface particles are less bound than the particles inside the briquette or pellet mass. Briquettes and pellets can then be treated with oil that settles over the surface of the fuel piece, cf.

DE-B-301,138 (Stechele). Dust is then bound to the briquettes by the briquette surface being shrouded in oil. However, no treatment of the internal particles of the briquettes takes place. 5. GB-B-842.711 (Simon-Carves) discloses a method in which carbon powder dust is bound by oil and formed into a lumpy piece. Larger pieces of caked carbon powder are obtained, which thus means that it is not a question of treating a fine powder with an inherent risk of self-ignition.

An object of the invention is to provide a method of preventing self-ignition and dust explosions in the handling of a powdered peat fuel which, during its manufacture, is decomposed by drying into very small particles with a water content of less than 30%, which method is simple and inexpensive to apply and avoids the disadvantages of prior art methods.

The method according to the invention is essentially characterized in that a liquid or powdered substance is mixed into the peat powder, the weight of which does not exceed 20% of the weight of the peat powder, which substance affects individual peat particles, so that they flocculate to larger non-dusting, relatively weak agglomerate.

The substance that is added is evenly mixed into the entire peat powder mass. The substance can be in the form of powder or in liquid form. If a liquid substance is added, the amount should be so small that the mixture of the peat powder and the substance is still in powder form. The amount of substance involved must then, as stated, be limited to a maximum of 20% by weight, but can be considerably less.

If the substance involved is in liquid form, it is suitably composed of an oil such as a petroleum product or a vegetable oil. The substance may possibly be liquid and e.g. consist of diesel oil.

When the substance is powdered, it preferably consists of a substance which can be melted at limited heating, e.g. sugar I or paraffin. 1 Oil wets peat better than water, i.a. because the oil í has a chemical structure that is more similar to peat than water | has. Oil and peat thus consist of long particles of hydrocarbon atoms, whose shape and state of equilibrium are favorable for achieving the intended effect. The peat particles are thus easily enclosed in an oil film and small dust particles of peat easily adhere to the surface of the oil film and are also enclosed in the oil, where they are well bound.

A powdery, meltable substance with limited heating, such as e.g. sugar or paraffin, has similar properties and is therefore also suitable for the purpose in question.

Laboratory tests show that an addition of 2-10% by weight of waste oil, diesel oil (fuel oil 1) or kerosene is sufficient for dust formation to cease completely and an oil film is formed, which encloses most of even the smallest peat particles.

The desired effect increases with increased addition of the substance up to a certain limit, as further improved effect can not be ascertained.

As regards the lower limit for the added substance, the effect of the tests taken so far has been ascertained at a quantity as small as 2% by weight. It is probable, however, that in some substances acceptable effects can be obtained even with a lesser amount involved, e.g. 1% or so. gëempel Experiments are carried out on dried peat with a moisture content of about 20%. The peat is finely divided into a powder.

The powder dusts heavily when stirred or shaken.

Experiments are being carried out for three different petroleum products, namely waste oil (0), diesel oil, E01 (D) and kerosene (F) and a vegetable oil, corn oil (M). Substances are added with 50 g of powder, after which vigorous stirring is carried out. The substances are mixed with the powder and if the dusting decreases or ceases, it is registered. The consistency of the peat powder is observed. The following table of tests taken is established. 8207128-3 6 Sample Additive Additive Observation no. grams weight% 01 0,5 1 The oil clumps It is difficult to mix The lumps disappear during heavy processing I 02 2,5 5 - “- 02 5 10 -“ - 04 10 20 - “- D1 0,5 1 'Diesel oil absorbs quickly and mixes lightly with the powder No lumps D2 2,5 5 - “- D3 10 -“ - D4 10 20 - “- D5 2,5 2,5 -“ - (100 g powder) F1 0,5 1 The kerosene absorbs quickly and mixes lightly with the powder No lumps H2 2,5 5 - “- F3 10 -" - F4 10 20 - “- M1 2,5 5 The oil lumps Difficult to mix The lumps disappear with heavy processing M2 5 10 - “- M3 10 20 -“ - Results Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams Dams tendency to remain in vessels and funnels with increased addition, but does not stick at all.

A similar effect is expected if a heavy fuel oil is involved instead. However, this requires heating. Admixture of a powdery, after limited heating fusible substance such as, for example, sugar or paraffin is also expected to offer a corresponding result.

Thus, when using a powdered substance, a heating is required to bring the substance into such a form that the finely divided peat particles can be enclosed. Other, more difficult-to-digest powdered substances are of course also conceivable for the intended purpose. However, such substances require increased costs for the heating itself, so they appear less interesting in the practice of the invention.

Within the scope of the invention is also the possibility of adding one or more additives which stabilize the effect obtained. An example of such a stabilizer is a substance that prevents the evaporation of oil.

Claims (4)

«....-_...._..__._._...___-, _., Qâ fl wâíëšeš Patentkrav Ways to prevent self-ignition and dust explosions when handling a powdered peat fuel, which during its production is decomposed by drying into very small particles with a water content of less than 30%, characterized in that a liquid or powdered mixture is mixed into the peat powder. substance, the weight of which does not exceed 20% of the weight of the peat powder, which substance affects individual peat particles, so that they bind to each other by flocculation into larger non-dusting, relatively weak agglomerates. 2. A method according to claim 1, characterized in that a petroleum product or a vegetable oil is mixed in. 3. A method according to claim 2, characterized in that a light-liquid petroleum product such as light fuel oil, diesel oil or kerosene is mixed in. 4. A method according to claim 1, characterized in that a powdery substance, with limited heating, fusible substance, e.g. sugar or paraffin, are mixed. 8207128-3 Summary The risk of self-ignition and dust explosions in a powdered peat fuel with a water content of less than 30% is significantly reduced or completely eliminated by causing individual peat particles to agglomerate into larger easily degradable peat particles, by mixing a liquid or powder form. does not exceed 20% of the weight of the peat powder. The substance may consist of a petroleum product or a vegetable oil or a powdery substance which, on heating, can be melted, e.g. sugar or paraffin.