October 18, 1918. THE COLLIERY GUARDIAN. 809 Pittsburg coal (heating value 14,157 B.T.U.) of the following analysis: — Per cent. Volatile ... .... ... ... 35-4 Fixed carbon ... ... ... 58*5 Ash .........................-.. 61 We find that a cubic foot of a correctly proportioned mixture of coal dust and air has available 107 B.T.U., while a mixture of pure methane and the proper amount of air has available per cu. ft. 62-3 B.T.U. Factors Influencing Combustion. The rapidity of combustion and the completeness of combustion of a mixture of coal dust and air depend upon a number of factors; for example, they are dependent upon the velocity and pressure at which it is passed into the combustion chamber. If the velocity of the incoming stream of powdered coal and air is above the velocity of flame propagation, com- bustion will not take place until the mixture has slowed down to a point that it does not exceed the velocity of flame propagation. When a powdered coal is fired at high pressure and high velocity, combustion frequently does not begin until a point 4 ft. to 6 ft. from the mouth of the burner. A similar example is found in the plumber’s blow torch when too much air is used, or in the Bunsen burner when the gas pressure is too high. High pressure firing not only slows down combustion, thus .increasing the size of the chamber necessary, but has a destructive action on the furnace. It has been well established that high velocities in the combustion chamber or a blow torch effect due to firing at high pressure (whether oil or gas be used as a fuel) are always destructive of the brickwork. This action is increased in high- pressure firing of powdered coal, since, in addition to the erosional effect of gases at high temperature travelling at high velocity, there is a fluxing action by the melted ash. Furthermore, the slagged ash will be carried along mechanically, leading to further furnace troubles. In one case this resulted in a deposit of slag on the mud drum of a vertical waste heat boiler at th,e end of a long reverberatory furnace. Slowing the velocity not only hastens combustion, but makes it possible to eliminate much of the slag. When the velocity is low, the coalesced particles of slagged ash are- either larger than will be carried by the velocity of the gas or this condition is so nearly approached that a slight change in direction of the flame will result in dropping out the- slag. Thus, in addition to being correct combustion and necessary in order to avoid excessive furnace maintenance costs, low velocity combustion, by a slight change in flame direction, permits the dropping out of a large quan- tity of the slagged ash in the early part of combustion, . where it can be removed and will not interfere seriously with efficient metallurgical operations. Velocity of Combustion. The velocity of combustion is not only dependent upon the fineness of the particles of coal, the intimacy of the mixture, and the velocity of the stream of combustible and air, but is affected by the tempera- ture of the combustion chamber. The kindling tem- perature of a mixture of powdered coal and air is higher than that of either oil or gas; consequently, for successful and complete combustion it is«iecessary that the combustion chamber be maintained above a certain minimum temperature, and that the combus- tion be practically completed before the products of combustion pass over the heat-absorbing surface. Just as you can extinguish a gas flame by passing over it a piece of wire gauze, so the effect of a chilling surface will be even more marked with this com- bustible material than ‘with burning gas, since the particle of coal is infinitely larger than a molecule of gas, and the kindling temperature is also higher. This has a direct application to the successful firing of locomotive boilers, water-tube boilers, and return tubular boilers. If the combustion of powdered coal be not sufficiently developed before the flame enters the tubes of the locomotive boiler, combustion will be checked and coked coal settle out in the tubes. If, on the other hand, combustion be sufficiently de- veloped before the flame is brought .in contact with the heat-absorbing surface, complete combustion and high efficiency are obtained. A study of the flame developed at a low pressure by an intimate mixture of coal dust and air shows that combustion is extremely rapid. In a copper reverberatory furnace at Florence, Colorado, where this type of combustion is used, coal burned at the rate of approximately one ton an houf develops a flame that vanishes within 6 ft. of the burner, com- bustion being complete at that point. Let us translate this into terms of natural gas, in which case the fuel consumption would be approximately 26,000 cu. ft. per hour, or 433 cu. ft. per minute. You can.picture, to yourself -this quantity of' gas being burned at low pressure and developing a flame only 6 ft. long. Samples of gas taken in the flame show a content of CO2 as high as 16 per cent, only 5 ft. from the mouth of the burner. This will give an example of the rapidity with which combustion can be obtained and the possibilities of shortening the flame. With proper equipment it is equally practicable to lengthen the flame until it will spindle out a distance as great as 100 or 120 ft. However, with an intimate mixture under control this must be done by supplying in- sufficient air. Under such conditions combustion is incomplete and the flame spindles out because com- bustion continues to develop throughout the length of the furnace as air leakage supplies additional oxygen. This is proof of the statement that the length of flame is an actual measure of efficiency of mixing and the adjustment of the fuel air ratio. Thus it is seen that we have changed entirely the characteristics of coal as commonly known. Powdered coal is a fuel of extreme flexibility, in that the amount burned can be varied within wide limits. It is a fuel that develops a flame whose length can be adjusted. The character of the flame can be altered to suit the metallurgical operation. In short, the basic fuel, coal, has acquired the characteristics of oil or gas, but with better and closer control. Furthermore, the possibilities of this fuel are not only capable of reali- sation, but are actually being utilised in commercial practice to-day. To the flame characteristics of a rich fuel developing a flame-like oil or gas is added a degree of control not yet obtainable in burning either oil or gas. This statement is made advisedly. The possibilities of such combustion for the improve- ment of processes, for fuel economy, for increasing output, through its ease of control and elimination of heavy labour, are realised by few. Owing to the attitude of labour and the scarcity of skilled opera- tives, it is far more difficult than ever before to secure high efficiency and good operation in hand firing, stoker firing, or in producers; in short, when- ever such efficiency depends upon constant watchful- ness and hot, heavy, disagreeable work. For these conditions powdered coal substitutes an ease of con- trol such that the equipment can be handled by an old man or a boy, while it is so simple that a man of ordinary intelligence can soon be taught all that is necessary for good efficiency in operation. The possibilities of such control in the place of present-day combustion methods, which permit high efficiency only by the most strenuous effort, through substituting for these a type of combustion whereby high efficiency is easily obtained, are certainly of great importance to us at the present time. BELGIUM’S PROBABLE FOREIGN COAL REQUIREMENTS AFTER THE WAR. By E. Cornand, Paris. In a previous article* I dealt with the reasons why the control of the Belgian market in imported coal •had been acquired by Germany, and it is now proposed to foreshadow the probable future of that market and the prospects the business offers to British coal owners. The imports of coal into Belgium during the year 1913 were: — Shipped by £oaL £oke- Briquettes. ~ Tons Tons. Tons. Tons. Germany...... 5/210,687 ... 1,002,190 ... 458,300 6,671 177 England .... 2,281,344 .... — . — 2 281 314 France....... 828,675 ... 51,350 ... 1,502 881’527 Holland ..... •— ... 74,307 ... 6,959 ... 80,866 Various ..... 1,639 ... — ... — ... 1^39 10,450,878 These imports may be classified as follows, as far as the item ‘‘ Coals ’ ’ is concerned : — Germany.—(1) Coking coals for coke ovens and blast furnaces; (2) gas coals for gas and glass works; (3) steam coals for boilers in various industries; Antwerp used to receive a great quantity of German steam coals for the bunkering of steamers; (4) house coals. England.—(1) Coking coals as above, in competi- tion with German and Belgian coals; (2) gas coals as above, in competition with German and Belgian coals; (3) steam coals, most’ of which went to the Belgian State Railways, and about 150,000 tons Welsh to the Zeebrugge Patent Fuel Works; (4) house coals in small quantity, imported via Bruges and Ghent. France.—(1) Special bituminous coals; (2) special long flame coals; (3) coking coals. It is, of course, out of the question to rely on equiva- lent imports for the first year following peace. The greatest consumer of coals in Belgium was the iron industry. Next came the transport (railways, steam trams, steamers), glass works, textile factories, gas and electricity plants, etc. Few of these will be able to start right away, after peace is restored, under pre-war conditions, especially on account of the enemy’s destructions, which will require a considerable time to restore. On the other hand, will Belgium after the war be in a position to export the various products she prin- cipally manufactured with that object? Will her industries be able to produce at sufficiently low cost to regain her former position on the world’s markets, seeing that the reconstruction of blast furnaces, rolling mills, etc., will most probably involve an out- lay of twice pre-war costs? This as compared with her competitors, who all have been able during the war to considerably improve and perhaps almost totally write off their plants. To take a rapid view of the probable position, I will only examine the principal industries in Belgium which consumed foreign coals, i.e., coke ovens; glass and gas works; the railways. Coke Ovens. The production of the coke ovens, about 4,000,000 tons per annum, went mostly to the blast furnaces, and was used in smaller quantities by steel and iron foundries. (1) Blast Furnaces.—Will there still be any blast furnaces in Belgium by the end of the war? This is most difficult to say. Before the war 60 blast fur- naces were operated in Belgium. We know that nearly all of them have already been destroyed by the Germans, and this destruction appears to have been carried on systematically. If the Germans in their retreat continue their organised destructions there may be not a single blast furnace left in working condition. (2) Foundries.—Belgium possessed numerous iron and steel foundries. They burned a special washed coke which required first grade coals and was generally manufactured in Belgium. The foundries could be rapidly re-started if they could be supplied with Middlesbrough No. 3. Taking a general view of the situation, I conclude that there will be no requirements for foreign coking coals in Belgium for about the first six months follow- ing peace, unless the Germans destroyed the mines producing these coals and the coke ovens before leaving the country. * Colliery Guardian, October 4, 1918, p. 703. So far the destruction of the mines does not tally with Germany’s interest, seeing that she commandeers 75 per cent, of the total coal production; but if military events compelled her to give up Belgium, we might expect the same treatment for the mines as that inflicted upon the metallurgical industry. As regards the coke ovens, if these were destroyed to any extent the 400 ovens belonging to the Societe Fran^aise de Terneuzen (Holland) could be used to produce coke for Belgium. These ovens belong to a combine of French ironworks at Longwy, whose blast furnaces have been destroyed by the Germans. In consequence, this combine will not require the Ter- neuzen ovens for months, perhaps years, after the sig- nature of peace. In that case the supply of English coals c.i.f. Terneuzen might perhaps compare economi- cally with other coals brought there by rail or barges. Assuming that the mines and coke ovens are in work- ing order, I calculate that Belgium’s requirements for imported coals (coking) will be, roughly, 3,000,000 tons per annum after the first six months following peace. If Luxemburg were economically attached to Belgium, there would be room for a further importa- tion of about 1,300,000 tons of coking coals, repre- senting about 1,000,000 tons of coke, put of the 2,250,000 tons required annually by her 30 blast furnaces, the balance being covered by contracts ahead made with German coke manufacturers. If these contracts were broken, the requirements for Luxemburg would be about 3,000,000 tons of coking coals per annum. Glass Works. These include the works producing any kind of glass ware. The annual consumption was approximately: By window glass works, 520,000 tons of coal; plate glass works, 200,000; crystal glass works, 250,000; and bottle works, 35,000—all gas coals. The total quantity for this industry was therefore about 1,000,000 tons per annum. Before the war these coals were supplied by the Mons district (Belgium), the Bruay and Maries (France), and by England and Germany. I think that on account of heavy requirements in France (and possibly owing to . destruction at the mines) the Bruay and Maries mines will not be able to sell anything for the first years following the end of the war. Germany will be cut out by English coals, as it is not unreasonable to suppose that the favourable conditions offered them by the Belgian market will not prevail after the war. If the Mons district mines are not destroyed, they will be able to supply about 500,000 tons, leaving an equal quantity open for English coals. Gas Coals. The total quantity used was just over 4,000,000 tons, and was chiefly supplied by Germany and England, the share of France and Belgium in this trade being only very small. There would therefore be a market in Belgium for, say, about 3,000,000 tons foreign gas coals; and seeing that the English gas coals were already greatly appreciated in Belgium on account of their quality, they will find it very easy to cut out the German coals. Railways. The total quantity required was about 2,000,000 tons per annum of coal and patent fuel, mostly sup- plied by Belgian mines, except some special Durham coals and first-class Cardiff steams. As probably traffic on the railways, on account of destruction and lack of goods to carry, will for a ' certain time represent only about 30 per cent, of pre-war activity, there will be no room here for imported coals. However, as soon as traffic is restored to normal conditions there will most certainly be a fairly im- portant opening for foreign steam and coking coals for the Belgian State Railways. Various Industries, Having no figures at hand, it is hardly possible for me to give in detail the quantities used in other industries and for domestic purposes (the latter, how- ever, representing only a relatively small tonnage), but the large total* of Belgium’s imports for the year 1913, i.e., 10,450,000 tons, clearly illustrates the important market which English coals, both steam or bituminous and coking or gas, could find after the war. This would possibly be something nearing 3,000,000 tons per annum. En resume, such business as would be realisable within a fairly short period after the end of the war would be— * m Tons. Coking coals (coke ovens, blastfurnaces) .. 3,000,000 Gas coals (for glass works) ............ 522’222 ,, (for gas works) .............. 3,000,000 Steam or bituminous or coking or gas (for various industries) ................. 3,000,000 State railways ........................... ? Partnership Dissolved.—The London Gazette announces dissolution of the partnership of W. E. Pinnock and H. Ballard, trading as W. E. Pinnock and Company, coal merchants, Chartham. Italian Brown Coal Industry.—The Giornale d’Italia states that as the best kinds of fuel do not exist in Italy brown coal is used. The heating quality is comparatively * low. As regards quantity, there is no fear of any shortage of brown coal, as there is said to be 100 to 150 million tons available. The distribution of the brown coal fields is, however, unfortunate, there being none near the prin- cipal manufacturing centres of the north. In consequence of the war and the lack of Cardiff coal the demand for this brown fuel has forced the price up to £100 per ton. The industry is not properly organised. . In 1917 the hands employed numbered 18,000. If the price, of Cardiff coal were to come down to the pre-war level, it is doubtful if brown coal could compete, owing to the expense of trans- port. It is, however, not probable that the price will fall below £70 to £80 per ton, in which case brown coal will no doubt have a future even in Northern Italy.