PRODUCTION OF POWER BY GAS PRODUCERS AND ITS RATIONAL DISTRIBUTION. (From The Colliery Guardian, [London, England], February 11, 1898.) Power may be obtained in a simple manner by the producer gas apparatus, a thick layer of fuel being charged into a cylindrical generator, and a steam jet introducing under the grate the air required, previously heated, observed Herr Johann Korting at the Hanover Miners' Congress. The gases thus obtained, which are rich in hydrogen and carbonic oxide, are cooled and washed before entering a receiver, that chiefly serves as regulator, the most suitable classes of fuel being slighly bituminous. coals, such as anthracitous coal, anthracite, coke and charcoal. The utilization of 82 per cent of the combustible matters in the Korting power-gas constitutes a very favorable result, even when the gas used for raising the steam necessary for insufflation be taken into account. Gas engines of 100 horse power consume 2 cubic metres (70 cubic feet) of power gas, corresponding with a useful effect of 23.6 per cent.; those of 50 horse power, 21⁄2 cubic metres (88 cubic feet), corresponding with 18.7 per cent; and those of 10 horse power, 3% cubic metres (123 cubic feet), with 13.3 per cent of useful effect. Deducting from the above percentages 20 per cent for loss in production and what corresponds with raising steam, they become respectively 19, 13.5 and 11 per cent.far more favorable than those in the case of steam. The old method of transmitting power by belt and pulley, or spur gear, entails for each transmission a loss of about 15 per cent, so that with four successive transmissions the loss amounts to about 50 per cent; and in many cases only 25 per cent of the power is utilized, rope gear being subject to similar conditions. Transmission of power by compressed air is costly, but in mines this high cost is compensated by the advantages obtained. While the advantages of electromotors are generally recognized, the total loss by this method, including that of the conductors, is about 30 per cent, which is increased to 40 per cent in small installations. When power has to be transmitted to separate groups of motors or machines by means of steam, there are the disadvantages of condensation and leakage in the pipes; and, if a 500 horse steam engine be superseded by ten 50 horse engines, double the coal will be burnt, entailing a loss of 50 per cent. the use of gas engines, on the contrary, the above-named disadvantages are avoided, and the use of small gas engines is comparatively less costly than that of small steam engines as regards the consumption. If in a 500 horse gas engine nearly 0.45 kilog. (1 lb.) of fuel be burnt per horse power per hour, ten 50 horse gas engines will consume 0.55 kilog. (1.2 lb.) of fuel per hour, showing a loss of only about 20 per cent. The distribution of power by gas engines is, therefore, the most economical, and the plant is not more costly than of an electric central station for power. In many cases it is advisable to actuate the various groups of motors and machines by gas engines, and to subdivide the power by electricity. THE STORAGE OF EXPLOSIVES. By ROBERT HUNTER. (From The Colliery Guardian, [London, England], February 11, 1898.) One of the consequences of the Explosives in Coal Mines Order 1897, is that proprietors of collieries, who until lately allowed their miners and contractors to buy blasting powder and other explosives from local dealers, have now to make provision for supplying to their own workmen the permitted explosives which they adopt for use in their mines. In districts where blasting powder was used almost exclusively, many grocers, ironmongers, and co-operative stores had their premises registered and, according to facilities they possessed, could keep from 50 to 200 lbs. of blasting powder, which they retailed to miners in quantities as required, and such sales formed an important item in their turnover. But as the Orders in Council, under the Explosives Act 1875, do not permit dealers to keep more than 15 lbs. of any permitted explosive, unless they have specially constructed buildings in which 60 lbs. may be kept, it is quite impossible for one in a hundred of such dealers to supply the wants of even a small mining district. More especially is this the case since all permitted explosives must be fired with a detonator or electric. detonator fuse, as these require to be stored apart from other explosives and so reduce the quantity of the latter, which may be kept on registered permises to, say, 10 lbs. and a small stock of detonators. Colliery proprietors must therefore erect suitable buildings in which to store explosives, and fortunately there are few coal mines so situated that a site for such a building cannot be easily got. Anyone proposing to erect a store should endeavor to find a site which will entitle it to be licensed for the maximum quantity, as although a small one may suffice for present needs, these may expand and involve the erection of a larger store at a later date, the necessity for which might have been obviated by a little foresight. It is also important to select a site alongside, or not distant from, a private road, as the cost of making a good road is considerable and keeping it in order costs something yearly, even when there is little traffic on it. The quantity of explosives which may be kept in a store varies according to the distance which the building is from what are known as "protected works," licenses being granted under four divisions, A 300 lbs., B 1,000 lbs., C 2,000 lbs., and D 4,000 lbs. The more important "protected works" are these in the following table, and in the columns headed A, B, C and D are shown the number of yards an explosives store must be distant from them, to qualify it for 300, 1,000, 2,000 or 4,000 lbs. license. to.... A. 50 25 From a dwelling house, shop, room, or successors... 25 50 2 The building must be substantially constructed of brick, stone or concrete, or excavated in solid rock, earth, or mine refuse, not liable to ignition. It would not be permissible to have bare brick or stone walls inside. A coating of cement on the inside walls is not much better, as, unless great care is exercised, the cement is apt to scale off and become a source of danger. If the cement is painted it may keep in fairly good condition, but the best plan of all is to have the building lined with wood and have a wood floor, all fastened with copper, brass, or zinc nails, or iron nails countersunk and puttied, and apply two or more coats of paint or varnish to walls and ceiling. If the store is to be licensed for more than 300 lbs., double doors are advisable, both of which should open outwards, be fitted with strong locks, and with hinges inaccessible from the outside. It is very necessary that the building will be ventilated, as a store is generally in such a situation that it is exposed to sun and rain, and, unless free ingress and egress of air is provided for, many explosives will deteriorate in the moist atmosphere which such influences generate and maintain. The woodwork of the store is also likely to rot and require frequent renewal. The ventilators should be so constructed that access cannot be obtained by them to the contents of the store, and that malicious persons cannot insert combustibles through them which might cause fire or explosion. Precautions must also be taken to prevent water getting into the store, as it has injurious effects on every explosive. Having supplied plans and selected sites for many such building in England, Scotland and Ireland, which have met with the approval of inspectors of explosives, the writer thinks that the accompanying sets of plans and specifications may be of service to colliery proprietors, relieving them from doubt as to what kind. of building is required and possibly saving unnecessary expense. SPECIFICATIONS OF THE SEVERAL WORKS REQUIRED IN THE ERECTION OF A STORE FOR EXPLOSIVES. Foundation. The site of the building to be levelled, and the subsoil sufficiently removed in order that a firm bottom be obtained, and the foundation to consist of hard-burned bricks or rubble well grouted with mortar. Walls. The walls to be of the best hard-burned bricks 9 inches thick, and every fifth course to be headers. Gable ends to be carried up to top of roof and circled as shown on plan, and the outside walls to be neatly pointed. Roof. The roof to be covered with galvanized corrugated iron 22 B. W. G., screwed to purlins, which are to be laid from gable to gable as shown in plans, and bedded in cement at gables and wall plates, and joints filled with white lead, also screw or rivet holes. Door Frames. Door frame to be 9 in. by 2 in., fastened to dooks built into wall and lintel 9 in. by 41⁄2 in. Doors. Outside door to be 6 ft. 1 in. by 3 ft. by 2 in. and inside 6 ft. by 2 ft. 8 in. by 11⁄2 in., framed and lined, and moveable block inside inner door 9 in. by 2 in. with fillets on each side so that it can easily be lifted out. Flooring. Sleeper joists to be 6 in. by 2 in., and flooring 1% in. tongued and grooved. Lining. The inside walls and ceiling to be lined with 5% in. plain white lining, fastened to fillets as shown in plans, but not touching walls, and with breaks in fillets at intervals to allow air to pass all around, and nailed to wall plates at top and flooring at bottom, with a fillet at top and botton on all four sides. Lightning Conductor. Lightning conductor to be of 3/4 in. round. iron, terminating 4 ft. above roof in three points, nailed against wall by iron holdfasts and carried 6 ft. into the ground at an angle of 45 degrees away from the building. Ventilators. One cast iron ventilating air brick 9 in. by 4 1⁄2in, to be inserted on each side, with a dwarf wall 18 in. long opposite each, and a slate or slab same length on top just under flooring, all as shown in plans. Locks. All locks, hinges, and nails where exposed, to be of brass or copper, or counter-sunk and puttied.. Woodwork. Outer and inner doors with their frames to be of best red pine, and the remainder of woodwork of white pine. All to be thoroughly well seasoned and perfectly free from knots, shakes or bluewood. Painting. Outside door and all exposed woodwork to receive three coats of good oil paint. |