The Works Of Messrs. Schneider And Co.

THE BLAST-FURNACE DEPARTMENT: BOILERS AND COKE OVENS. ing of the blast-furnaces, will not be suitable for granu- lating. Gas Fired Tubulär Boilers.—All the coal-fired bollers 1 at one time in use, have been replace«! by tubular generators, which are illustrated in Figs. 58 to 61, Plate XII.; they are heated entirely by the waste gases from the blast-furnaces. In order, however, that a sufficient supply of steam might be obtained, in the event of the furnaces being stopped ’ four of these boilers are fitted with auxiliary coal-burning | grates. These four generators, coinbined with those heated by means of the waste gases from the coke ovens, the production of which is always constant, would be sufficient to meet all demands conséquent upoxi even a prolongée! stoppage of the blast-furnaces. As will be seen from the illustration (Plate XIL), the boilers are of the tubular in- ternal firebox type. In front there is a combustion chamber of refractory brick, which can be maintained at a red heat for a sufficient length of time to light the gases in the event of any moderate interruption to their admission. lf it should happen that a prolonged delay occurs, the gases are ignited by means of lighted grease fuses that are thrown into the combustion chamber. Tho air necessary for combustion is admitted into the bottom of the chamber, above the gas inlet, after it has been raised to a sufficiently high temperature by circulating round the sides of the chamber. The adoption of this boiler was decided on experimentally, and with considérable doubt as to its successful working ; fears being entertained that the tubes would become rapidly obstructed with the dust deposited by the circulating gases, but experience has shown that no <lifficulty arises from this cause. The tubes require clear- ing only twice every twenty-four hours, and the operation can be completed in twenty minutes as a maximum. They are swept by means of an ordinary long Hue brush, and the dust thrown down on the internal fire-grate by the brush, is collected with a rake, and drawn into the combustion chamber, from the bottom of which it can be removed from time to time through a side door. Sonie interesting experi- ments have lately been made, having for their object the employment of conipressed air instead of brushes for clean- ing the tubes. These experiments have given excellent results, both as regards efficiency in cleaning and saving of time. In addition, the dust is so etfeetually dispersed that there is no necessity for collecting it in the combustion chamber. This method of cleaning is about to be universally adopted at Creusot. Experiments having the same object were also made with steam jets instead of conipressed air, but the results obtained were not satis- factory. The steam caused the dust to become damp, and it tben formed a paste that adhered to the inner sules of the tubes, with the result that the transmission of heat was considerably checked, and the safety of the tubes themselves was endangered. All the boilers in this departinent are fed by pumps which deliver water at 90 deg. to 95 deg. Cent. (194 deg. to 203 deg. Fahr.), the temperature being obtained by feed heaters, through which the exhaust steam is discharged from the blower engines. The steam which is cleansed by going through a special separator, circulâtes through the feed heaters in a direction opposite to that of the feed water. Fig. 62, Plate XIII., gives an admirable idea of a Lattery of tiiese boilers heated by the waste gases of the blast-furnaces. The following are sonie of the principal particulars oi these boilers : Heatiiig surface of firebox ... ,, tubes ,, return flue Total heating surface....... Volume of water space ,, steam space Registered working pressure Number of tubes ............ Interior diameter of tubes ... Thickness of tubes 25 m2. 269.10 sq. ft. 108 m2. 1162.Ö4 sq. ft. 30 m2. 322.95 sq. ft. 163 m2. 1754.59 sq. ft. 23.150 m3. 817.57 cub. ft. 7.700 m3. 271-D4 cub. ft. 7 kg. 99.56 1b. per sq. in. 100 100 73.5 mm. 2.88 in. 3.5 mm. .138 in. bollers, ascertained from a long • be suuimarised as follows : The efficiency of the 1 series of experiments, may Water evaporated per hour ... Consumptionof gas per minute Temperature of escaping gases feed water ... 1800 kilos. 30 m3. 250 deg. Cent. 90 deg. Cent. 36 cwt. 1059 cub. ft. 482 deg. Fahr. 194 deg. Fahr. Coke Ovens.—For many years, vertical coke ovens, of the Appolt and Bauer types, were used at Creusot, together with a large number of horizontal ovens ; but, taking into considération the quahty of the coal employed, it was found that the vertical ovens gave results far inferior to those obtained with the horizontal type, and the former have been definitely abandoned. Until a comparatively recent date, the horizontal ovens, of the so-called Belgian type, were constructed after the original designs, in which each’ oven was provided with a separate chimney for the discharge of heated gases. In order, however, to utilise the waste heat, which was sufficient to maintain a constant steam supply, important changes were made in the arrange- ments, with the view of economising this heat; these changés were adopted only after a long series of careful experiments, which gave very satisfactory results. Messrs. Schneider and Co. had no inducement to seek for the utilisation ofby-products from the coke ovens, because the mixtures o£ coal employed are very poor in volatile residues, on account of a large proportion of Creusot anthracite being introduced. On the other hånd, an economy of the waste heat for generating steam, was an important object to be attained. The transformation of the ovens was carried out under very special conditions and considérable difficulties ; all of them being in good condition, it was désirable that the change to be etfeeted should interféré as little as possible with their construction. Moreover, it was not possible to reduce the volume of coke production beyond a very limited estent ; and for this reason it was necessary to proceed with the varions alterations gradually, by changing a few ovens at a time. Under tlie special conditions that existed, it was found more convenient to construct a waste-heat collecter above the ovens, instead