296 THE COLLIERY GUARDIAN. February 6, 1914. On the whole, it is to be observed that no great change in the methods of factory driving has taken place during the period referred to. Textile factories are still mainly driven by steam boilers and engines with a separate power installation at each works, but in later years a large number of industrial establishments, mainly small ones, have found it to their advantage to buy their power rather than to generate it separately. In 1903, the power stations for the production and distribution of electricity were not in so strong a position as at present. In later years their importance has steadily grown, as is shown by the figures of fig. 3. In most cases, as in those of ordinary town supplies of TOTAL ENGINE POWER IN FHE UNITED KINGDOM IN 1907 DIVISION OF 10.578.475 IMP AMONGST INDUSTRIES -DIVISION OF 10 578.475 IHPJWONCST VARIOUS KINDS OF POWER STEAM BOILERS & ENGINES IHP 9 649710 RECIPROCATING STEAM ENGINES IHP 9118818 IRON & STEEu ENGINEERING & SHIPBUILDING TRADES I H P 2 437 441 TEXTILE TRADES I H P I 978 528 337.573 1 [LESTKE.f CANVAS S iriaWBuaBEA I JLEtlEU___IHJ’-M.JJL .Mi5C[.'..I.AMc_0US> 3UBLIC UTILITY SERVICE 'LARGELY SUPPLY OF ELECTRIC) POWER GAS WATER IHP I 892 840 Fig. 3.—Division of Total Engine Power amongst different Industries and different kinds of Engines. electricity, coal-fired boilers and steam engines or steam turbos are used for the generation of electricity, but in some districts, as on the north-east coast, much of the . energy which was previously thrown to waste is now being utilised in the form of blastfurnace gas engines or exhaust steam turbos, used to produce electricity for sale. In the power production in factories, changes toward greater economy are slowly and continuously taking place. The use of steam for small independent units of power is probably decreasing, particularly in large towns where gas or electric supply is available, small steam engines for power production being frequently replaced by electric motors or small gas engines, except in those cases where steam is also used for manufacturing purposes. Larger factories show a general advance in economy, the standard plant in the larger textile factories consisting of Lancashire or similar boilers combined with superheaters, fuel economisers, and Corliss or drop valve steam engines. Some few of the larger factories are driven by turbos and some by gas engines, but a number of large factories are driven by electric power from electric stations. As regards economies generally, it is to be observed that great economies cannot come at once. Old plants must generally work out their time before replacement. A comparison of the cost of modern plant with old plant seldom shows that the savings of the modern plant are sufficiently great to justify financially the pulling out of an old plant which is in good condition. As a rule, the economic changes are effected when old plants are worn out or when new factories are started; consequently, changes in economy of power are slow in taking general effect, and at any period the mass of power producers include:—Some old wasteful plants; a large number of middle-aged plants, with moderate economy ; and a proportion of new plants, with the best economy available up to date. The first two factors, of course, affect the average of economy, and while there- fore the total economy improves, the average economy necessarily is always materially below the best. Mines.—In past years a low economy of fuel was observable in connection with colliery practice generally, the exhaust steam from all engines blowing away and the power being developed about the pits by wasteful small engines for hauling, pumping and venti- lation, either connected by long steam pipes which lost heat by condensation, or provided with independent and somewhat wasteful boilers. In many old coalpits, considerable economy has been effected by installing exhaust or mixed pressure turbines to utilise the exhaust steam, and by putting down central stations, distributing the power electrically,' and driving the power station by either steam plant or by gas engines. It is to be noted in this connection that the increasing adoption of modern forms of coke ovens is generally being accom- panied by a more efficient utilisation of .the coke oven gas in the production of power. The coke oven gas is of a high calorific value, and, when properly purified, lends itself to use in gas engines. Iron and Steel Industries.—Under this heading are included both blastfurnaces and all iron and steelworks, and the estimate of the fuel covers that for heating and for the production of power. In past years this industry has not been one of the centres of highest economy in power production, the use of non-condensing engines being common, accompanied by low efficiency economi- cally in the auxiliary steam plant; also in some cases boilers of the oldest types were retained in use. Thus, up to a few years ago, the cylindrical externally-fired boiler still continued in use in ironworks long after it had become obsolete in textile factories and the like. In British ironworks to-day a strong movement towards economy of fuel is to be noted. This movement is generally on the lines of higher steam pressures, together with the use of - compound engines and condensing wherever possible. The movement is combined with a more efficient utilisation of the heat of blastfurnace gas. In old ironworks, economy has been more generally sought for on the lines of low-pressure turbines, utilising the exhaust steam of the engines, combined with central electric stations for driving the auxiliaries, the central stations in some cases being driven by blast- furnace or other available gas, and in other cases by steam. Total Power Capacity. In past years there was no information of a definite character available in reference to the total power production of this country. This condition of affairs does not now obtain, as information of a definite character was obtained by the Census of Production (1907), and is now available. Another census of a similar nature is being carried through in relation to the year 1912. The figures given in the Final Report of the First Census of Production of the United Kingdom (1907) show a total horse-power of 10,578,475. (See fig. 3.) These figures relate to the capacity of the engines measured by the horse-power which the engines were built to produce, or in those cases where the engines were indicated, the indicated horse-power at full load. It would appear that of the total horse- power stated, about one-quarter of this capacity is used for driving dynamos for the production of electrical energy, and about three-quarters of the total for driving machinery directly. Of the electricity generated, about two-thirds was generated in electric light and power stations, the remainder being produced by the users, the largest output being that of the iron and steel trades, which generated rather less than a quarter of the total. Total Power of Different Prime Movers.—Recipro- cating steam engines in 1907 produced about nine-tenths of the power—namely, 9,118,818-horse power out of a otal of 10,578,475-horse power steam turbines at that time generated, or were installed, of a capacity equal to 530,892, say half-a-million horse-power. The bulk of these turbines were in works included under the heading “ Public Utility Service,’" mainly electric supply undertakings. Internal combustion engines, including both oil and gas engines, accounted for a total of 680,177-horse power. The trades utilising these engines to the greatest extent were the iron and steel, engi- neering and shipbuilding trades. No doubt the large gas engines, using blastfurnace gas and the like, constitute a large proportion of this power. Apparently in the iron and steel and similar trades the total power capacity of internal combustion engines is about 10 per cent, of the total steam engine power capacity in those trades. The total water power returned amounts to 177,907 horse power, or about 1 per cent, of the total power capacity. Coal Consumption for Power Purposes.—From the estimates illustrated by fig. 2 and a comparison of the figures with those on fig. 3, an approximate idea may be obtained of the total amount of coal used in the United Kingdom for power purposes. The total steam power of industry in the United Kingdom for 1907 is shown at 9,649,710 indicated horse-power. Probably for the year 1911, referred to on fig. 2, 10,000,000 indicated horse-power for the United Kingdom will be a fair estimate of the capacity of steam power in use. On the assumption that this coal is utilised in steam engines using on the average 6 lb. of coal per indicated horse-power per hour and working 2,500 hours a year, this would be equal to 6’7 tons per indicated horse- power per annum,and for 10,000,000-horse power at this rate, 67,000,000 tons would be absorbed. On the basis of this approximate calculation it would appear that of this 1201 million tons of coal, from 60,000,000 to 70,000,000 tons per annum, or rather more than half, was used for the production of power in the principal industries of the country. Proportion of Cost of Power in Industry.—Power is one of the most discussed elements of the various industries. This is probably because mechanical power is one feature which the industries have in common. Mechanical power is indeed important to each industry, but in particular industries the efficiency of the processes or machines peculiar to the industry in question is often of more importance financially. The cash importance of the economies of power production varies in different industries. If mechanical power costs 10 per cent, of the total cost of production in any industry, then a saving of 10 per cent, in the cost of power will amount to 1 per cent, of the total cost of production. The value of the output of industry in the United Kingdom Census of Production (1907) was 1,574 million pounds. The power used for this was about 10 million horse-power. On the basis of 6’7 tons of coal per horse- power per annum, and 12s. per ton of coa], this would cost £4 per horse-power per annum, or 40 million pounds per annum for the 10 million horse-power. Forty million pounds is 2 J per cent, of the total production of 1,574 million pounds, so that between 2 and 3 per cent, would appear to be the approximate average importance to industry of the fuel cost of power production. Boilers. As shown on fig. 3, the great bulk of the power in the United Kingdom is generated by steam boilers and steam engines of various kinds. No official figures are available giving the total number of boilers in this country. From a consideration of the various estimates which have been made from time to time, and from his own experience, the author estimates that there are in the United Kingdom 160,000 steam-gencrating boilers, apart from railway locomotives, of which in 1911 there were 22,874. As the industries of the country steadily increase in output and in power requirements, so the total power developed tends to increase. This naturally would call for an increased number of steam boilers, but this tendency to increase is, to some extent, checked by the fact that part of the increase of power is provided by gas engines, oil engines, and the like; also by the PERCENTAGES 1895 1902 1913 l-l RASTRICK bl 16-5- -I8-S CORNISH 695 1902 1913 Fig. 4.—Comparison of the numbers of different types of boilers in the United Kingdom, based on the number of boi'ers insured in 1895, 1902, 1913, with the National Boiler and General Insurance Company Ltd. fact that new boilers when put down are generally of greater power than the old ones, so that a less number of boilers do the same amount of work. Further, by increased economies in the utilisation of fuel, a smaller number of boilers will do the same work. On the whole, therefore, even with an increasing industrial output, the tendency to increase in the total number of boilers will be materially checked. Different Types.—Fig. 4 shows an estimate of the proportion of different types of boilers in use in the United Kingdom. The figures there shown have been obtained from a classification of the types of boilers insured with the National Boiler and General Insurance Company Limited at the periods marked at the head of each column. The types of steam generating boilers in use in this country are generally less varied than is the case in some foreign countries. The general tendency in the United Kingdom has been towards a simplification of type; thus the Lancashire boiler in earlier years was varied with all kinds of arrangements of cross tubes and the like in the flue tubes, and provided with contri- vances for circulation, and in the course of years, many experiments of variation of form were made. These variations have been dropped, and the present tendency is to adopt a simple form of boiler as indicated at (a) on fig. 4, with plain flue tubes, but no cross tubes, any additional heating surface required being supplied by a superheater in the downtake, together with an economiser.