家庭燃料の着火温度に就て(昭和二年七月九日燃料協會第五三囘例會講演)

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Wood charcoal is the popular domestic fuel in this country, and not less than two million tons of it are being consumed every year. Most Japanese houses use this fuel in a furnace, with or without grate, under a very slow draft, and as these furnances have no chimney, the ignition temperature and the burning rate are both equally important factors for the qualification of charcoal, as well as the briquetted fuels to be substituted for the former. Owing to the increasing high price of charcoal during these ten years, many proposals and plannings were carried out to manufacture proper substitutes, but none of them has yet been satisfactorily used, chiefly because of lack of consideration for the two points cited above. In connection with the investigations on the manufacture of a new and cheaper domestic briquette, employing peat or carbonised saw-dust and powdered bituminous caking coal without a binder, author studied these two factors of domestic fuels now widely used in Japan. The ignition temperature was measured with an apparatus shown in the Japanese section of this issue. A silica tube, 1.9cm. inner diameter, was vertically fixed in an electrically heated furnace. The lower part of the tube was filled with firebrick of pea size and the latter was covered with a thin layer of asbestos, on which 2gr. of samples of 0.1-0.35cm. size were placed. Two thermo-couples were inserted, one in the sample with its point of junction at a point 0.4cm. above the asbestos, while the other along the tube at the same level. The temperature of the oven was then slowly raised at a constant rate, and the temperature rises indicated by the thermocouples were recorded every minute during the test, while the lower part of the tube was heated at a constant temperature in order to preheat the air passing into the tube. In all the experiments, a current of air, free from moisture and carbon dioxide, was passed through the tube at a rate of approximately 10 liters per hour; this is comparatively slow as compared with those figures published by many experimenters, but it was proper to keep this rate to attain the object of the investigation, as the actual condition of fuels burning in a furnance without chimney is nearly under the same draft. The temperature rise of the oven was as follows : Temp. intervals. 200-300 300-400 400-500 500-600 Mean rise per minute. 6.5 5.2 5.0 6.8 The ignition temperatures were determined by the following three observations and the results were compared : A. The crossing point of the two temperature curves, inside and outside. B. The point of sudden temperature rise of the inner thermocouple. C. The point of sudden increase of carbon dioxide in the exhaust gas. The results according to B and C invariably coincided, while those according to A were always lower than B, namely : Fuel. Ignition temperature. Remarks. A. B. 1. White charcoal. 245° Same. Carb'n temp. over 1000℃. 2. " " (Bincho) 302° " " " " " Superior quality, obtained from oak. 3. Black charcoal. 240° " Carb'n temp. about 600℃. 4. Carbonised peat. 285° " Peat mined in Hokkaido. 5. Carbonized lignite. 330° 355° Lignite mined in Kidomo, woody structure. 6. Semi-coke A. 330° 360° Coal from Fushun Colliery, vol. matter 23%. 7. " " B. 408° 420° Same raw matterial as A, vol. matter 9.8%. 8. Gas coke. 576° Same. From Toho Gas Co. 9. Heijo Anthracite. 446° Same Mined in Heijo, Chosen. 10. Omine " 450° " " " Omine, Yamaguchi-prefecture. 11. Special China anthracite. 273° 298° Mined in Shan-si, China. 12. Bee-hive shape Briquette. 270° 375° Chief component; anthracite and clay as binder. 13. Oval briquette. 348° Same Chief component; anthracite and molasses as binder. Carbonized after briquetted. 14. Carbonized briquette. 349° " Bituminous coal, pitch as binder. Among the results, the difference between A and B is particularly large in the case of sample 12. This is due to the presence of certain readily ignitable materials in the briquette in order to lower the high ignition temperature of anthracite. In such a case, the ignition takes place at a lower temperature, but if those materials are insufficiently added or the air current is slow, it will maintain a slow burning until it reaches the ignition temperature of the chief component, i. e. carbonaceous material. The burning rate was roughly estimated by the time between two points of intersection on the temperature curves, i. e., the first intersection, at the beginning, and the second, at the end of the combustion of the sample. The new briquette prepared by the author does not show any inferiority to charcoal, and the cost is estimated to be very cheap. Further experiments are reserved for the future.
一般社団法人日本エネルギー学会の論文

家庭燃料の着火温度に就て(昭和二年七月九日燃料協會第五三囘例會講演)

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