306 __________________________________________________________________________________________________________ THE COLLIERY GUARDIAN August 18, 1916. British thermal unit coal. This of itself is not a serious matter. This applies only to the moisture which is in the coal at the time of its being weighed. It must be remembered that the percentage of moisture as shown by the usual analysis does not include all of the water or H2O compound present in the fuel, for there is a consider- able amount of water that cannot be dried from the coal even at 220 degs. Fahr., but remains in chemical com- bination probably as a carbohydrate, and can only be driven off with the volatile. Therefore, a considerable percentage of impurities is included in the volatile. The following tabulated data of a typical West Virginia gas coal give the division of the volatile matter into its different elements, hydrogen, oxygen, carbon, nitrogen, and sulphur. It is noted that in the volatile there is a total of 5-38 per cent, of the total coal, or about 13 per cent, of the volatile, that is water, besides some nitrogen and sulphur as non-combustibles. Analysis of a Typical West Virginia Coal. Heating Calcu- value lated per lb. B.T.U. Moisture... 2’01 q 2*01 water _____None... — TH 4'86) 5 38 water _____None... — |O 4 78) 4’25availableH...62,000... 2,641 Volatile ... 37’31<{ C 26’65...................14,500 .. 3,464 ................... I N 0’23...................None .. — IS 0’79................... 4,050... 32 Fixed ......... carbon 52'13 Ash ..... 8’55 .................................None... — (C 49’18 .....................14,500... 7,131 ............................... ]N 1’20......................None... — CS 1’75 ...................... 4,050... 71 * 13,811 B.T.U. by calorimeter. 13,339* Analysis of a Typical Illinois Coal. Moisture... Volatile ... Fixed carbon Ash ..... . Heating Calcu- value lated per lb. B.T.U. 12’39 £ q ] 12’39 water ......None ... — fH 4’47) 9’01 water ......None... — | O. 8-01J 3’47availableH...62,000... 2,150 36’89s C 23’19 .....................14,500... 3,363 ..................... ..................... I N OTO.......................None ... — IS 1’12..................... 4,050... 46 (C 38'10.....................14,500... 5,525 ....................... 0'90.....................None... — 4i8U(.S 2’80 ..................... 4,050... 113.......... 8’92 ....None ... —.... ll,197f f 11,399 B.T.U. by calorimeter. Making a similar division of the proximate analysis of a typical Illinois coal, we find that 9 per cent, of the total coal occurs in the volatile in the form of water, or 25 per cent, of the volatile itself is non-combustible. In the case of lignite and peat, the percentage of volatile which is n on-combustible proportionately increases. So that in this we see that volatile itself is not an indication of rich locomotive fuel, for much depends upon the nature of the volatile, and how much of it is impurities and how much combustible. Then in the combustible itself there is considerable variation, depending upon the relative per- centages of available hydrogen and carbon. The Moisture Element. The percentage of moisture retained in coals varies widely with the characteristics of the coal. Lignite and sub-bituminous coals carry a much higher percentage of moisture than do the bituminous and semi-bituminous. Anthracite coal, on the other hand, carries a slightly higher percentage of moisture than does the semi- bituminous. Many people have considered that the percentage of moisture was such a variable quantity, depending upon weather conditions, etc., that the only true com- parison was on a dry basis. This is likely to lead to very erroneous conclusions. For instance, take Illinois coal, which may run normally with, say, 12 per cent, moisture, and a bituminous coal from the Pittsburg or West Virginia district, which would run normally 3 per cent, of moisture. If these are both reduced to a dry basis, the Illinois coal will show an apparent advantage of about 9 per cent, better than it should. In order to get a more uniform basis of comparison it is all right to compare different shipments of coal from the same region on a dry basis, but it is not right to com- pare coal of one character with another coal from another region of different character on any other basis except with their normal moisture content. A coal which normally has a high moisture content usually has a relatively large percentage of its volatile matter in the form of combined water. Influence of Ash. The impurity which is of the greatest importance is the ash. The ash is not only inert and non-productive of heat, but it may have very marked effect upon both the rate and efficiency of combustion. If the ash in all different kinds of coal were similar in its composition and characteristics, it would be possible to make comparisons on a British thermal unit basis alone with much greater certainty. The composition of ash varies widely. In all cases it is a very complex compound, consisting of alumina, silica, iron, lime, magnesia, titanium, alkalies, etc. The relative percentages of each varies widely, and the effect of them upon the action of the coal in the firebox varies according to such a complicated law that it is practically impossible for this analysis to be used as a reliable means of determining the character of the ash for comparative purposes. An ash w’hich does not clinker gives very little trouble. It is merely an inert substance that does not produce heat. But an ash which melts into a clinker is more difficult to get rid of, and while remaining on the grates it obstructs the flow of air to a serious extent, and often- times it adheres tightly to the grates and obstructs the air so completely that the heat of the fuel bed is conducted bo the grate bars and causes them to burn. The question of clinkers is one of the very vital problems in locomotive practice, and heretofore practi- cally the only means of getting any line upon this impor- tant characteristic of fuel was the actual trial. At the same time, it has always been realised that some firemen would make more clinkers than another, both using the same coal. A very thorough study into this phase of the fuel problem some years ago led the writer to conclude that the whole question of clinkers could be summed up in the fusing temperature of the ash and the temperature to which this ash is subjected. Some ash has such a high fusing temperature that there are practically no fuel bed conditions that will produce troublesome clinker from it. Another ash with a little lower fusing temperature will form a porous, spongy clinker which does not prove a serious obstruction to the flow of air, nor is it difficult to remove. The ash with a still lower fusing tempera- ture, say, 2,100 degs., will not only become melted in the average firebox, but it will be heated several hundred degrees above its melting temperature, in which case it runs down like overheated iron until it spreads out in a thin sheet over the grate bars. To a certain extent the action of a clinker depends upon its fusing temperature, but equally important is the temperature to which the ash is subjected. When a coal is burned, the ash is not entirely liberated until it reaches the lower part of the fuel bed, where the incoming air keeps a lower temperature than in the zone 4’ bo 6 in. above the grates. So it is often possible bo get satisfactory results from a coal having a fusing temperature of 2,300degs., and yet carrying a fuel bed temperature of 2,500 degs. Some clinker, of course, will be formed, but it is not of the extremely objection- able character if the firing is properly done. Clinker accumulates gradually, and is more or less open and does not obstruct the air beyond the critical limit. But if another fireman should handle the same coal differently, slicing or working the fire, and causing the ash, which has already been liberated from the coal in the lower and cooler part of the fuel bed, to be again thrown up into the hotter zone, it will melt into a very fluid mass, and spread out over the grates in a thin sheet, and obstruct the air flow to a serious extent. Sulphur and Clinker. Many people have considered that the percentage of sulphur wras a true indication of the clinkering property of a coal. The sulphur determination, however, is one of the ideas that has been passed on from the steel chemist. In his case, sulphur was extremely detri- mental, but in the case of steam coal it is of minor importance. It is true that in some coal fields the vari- ation in the clinkering property of coal received from different mines does follow the percentage of sulphur to a certain extent. Sulphur is an indirect cause, how- ever, for it is really the iron which has the effect upon the fusing temperature, and the percentage of iron usually increases or decreases with the sulphur. There are so many exceptions to the relation between sulphur, or even iron, and the clinkering property of coal, how- ever, that a dependence upon either is apt to lead to erroneous conclusions. One of the very lowest sulphur coals in the United States is found in Rhode Island, w’here the percentage of sulphur will run less than one-quarter of 1 per cent., yet the fusing temperature and the clinkering property of this coal class it among the very worst in this respect. In many respects the clinker problem is of more serious consequence in railroad practice than it is in stationary boilers. The matter of fusing temperature determination has not as yet been standardised from a laboratory standpoint to the extent that the regular analysis and British thermal units determination have been. The value of this determination has been demon- strated so conclusively that there is now under way a definite movement to work out the fundamentals of this problem, and decide upon a method which can be adopted as standard for comparison. It is the writer’s opinion that the method which will ultimately prove most valuable for this determination is the one which stays closest to practice, so far as duplicating the actual fuel bed conditions is concerned. One of the big difficulties with the whole question of coal analysis has been that the chemist was carried away with the idea of getting scientifically accurate results. The percentages of the various constituents, and the determinations which he made, were largely a matter of tradition, passed on to him from the needs of an entirely different line of work, and he has left the inter- pretation of these results to the person interested in the purchase or use of the coal. The original form of analysis did not fill the bill, and the next step was to include other factors, such as the British thermal units, and later on the fusing temperature of the ash, in an effort to strike the key to the situation that would give the factor essential for comparing the relative values of different coals. It is doubtful if there ever will be found any one factor that can be depended upon in drawing conclusions regarding a substance so complex as coal that is used under the severe conditions that exist in a locomotive firebox. It is therefore essential that the most important factor be taken as a basis of comparison, and consider the other factors as having modifying influence. While the heating value of a coal may be considered the essential element, it means very little unless the percentage and character of the impurities existing in the coal are fully considered. It is therefore necessary to determine the amount and nature of these impurities. After they have been determined and allowed for, it is found that the heating value per pound of combustible is practically uniform for all coals from any one district. Therefore it would seem, in comparing one shipment of coal with another from the same district, that the determination of the heating value was the least impor- tant; the percentage of moisture is often beyond control, and it is very difficult to determine accurately at the time the coal is weighed. So the question resolves itself largely into the percentage of ash, and its clinkering property, as being the critical factor to be considered in comparing the commercial value of different fuels of the same character. When it comes to comparing coals of different character, taking lignite and semi-bituminous coals as extremes, it is practically impossible for a safe conclu- sion to be drawn from any chemical analysis, no matter how complete. In such cases practical tests are the only reliable means of arriving at comparative results, and then comparative information regarding different shipments of coal from any one region can best be obtained from the percentage of ash and its fusing temperature. ___________________________ FRENCH MAXIMUM PRICES FOR IMPORTED COALS. The following list of maximum prices for coals imported into France came into force on the 10th inst. by a Decree of the Minister of Public Works, dated August 8. The considerations which have led to the modifications are set forth in a letter from the president of the Commission which is dealing with the question of coal prices and freights. The chief alteration is an enlargement of the classification; and for the first time prices have been fixed for coals which are screened, mixed, or otherwise treated, subsequent to importation, the English nomenclature applying to the coals .as imported, so that buyers may know the difference in price between the coal as imported and after treatment and re-classification. The Minister of Public Works, by Decree of August 8, has also fixed the maximum prices of French coals at the pit head, under the Law of April 22 last, these prices likewise coming into force from the 19th inst. The Decree legalises contracts for forward delivery based on the maximum prices in force at the time of delivery, instead of at a fixed rate. The prices given below are for prime coals of each class, the usual deductions being made for those of inferior quality, and are pit head prices, on wagon or barge. They are net, and include the remuneration of representatives or commission agents. The only additions allowed are proper freight charges, and a commission of 3 fr. per ton where the sale is made by a merchant not being the agent of the colliery. All contracts must specify the name of the colliery supplying the coal. The prices do not apply to coals supplied for the public services. The Coal Commission states that the new prices, for the Pas-de-Calais mines, represent a difference of 8 to 20 fr. per ton, as compared with pre-war rates, and are the rates at present ruling, their insertion in the list being merely confirmatory. In other French districts the rise has not been so considerable, only about 4 to 10 fr. per ton, and has been mainly due to the advance in the price of materials, and in wages to meet the increased cost of living. This rise the Commission proposes to sanction, at least for the time being. The whole question of the cost of raising coal is being inves- tigated, and further proposals will be made in due course. The chief difficulty the Commission has encountered so far is due to the difference between the prices of the large mining concerns, which furnish almost the whole supply, and those of the small pro- ducers, who would be compelled to shut down if they had to compete with large owners in neighbouring dis- tricts. In order to prevent this, in view of the neces- sity for maintaining the output, the Commission has established a general list, which modifies the most striking of these differences. In the case of certain coals, re-classified for distribution, and in some cases mixed with imported coals, it has been found necessary to specify that the Government-controlled organisa- tions which already deal with this trade may sell at a mean price, calculated from the composition of their supplies, as known to the public authorities. Maximum Pit Head Prices for French Coals. (All prices in francs per ton.) Pas-de-Calais. Small : 0-15 mm., 25; 0-30 mm., 26; 0-50 mm., 27. Thro' and thro' : 20-25 per cent., 28; 30-35 per cent., 30; 35-40 per cent., 32; 50 per cent., 34; sugar works coal, 36; gas, 32. Screened : 10-15 mm., long flame 41-50, other kinds 40; 20-30 mm., long flame 42-50, other kinds, 41; 40-50 mm., long flame 45, other kinds 43; cobbles, semi- coking and lean, 50-80 mm., 45; 80-160 mm., 44. Large, hand-picked, long flame 50, other kinds 48. Washed : smalls, 9-10-12 mm., 32; peas, semi-coking and lean, 9-20 mm., 35; 9-25 mm., 38; smithy, 40; peas, 20-50 mm., 42; beans, semi-coking and lean, 20-50 mm., 43; cobbles, semi-coking and lean, 30-50mm., 47. Briquettes, ovoid, 40. Haute-Saone. Ronchamp coal, 42. Saone-et-Loire. Blanzy coals : Best screened, over 55 mm. : long flame 41, anthracite 34; screened seconds, over 55 mm. : long flame 37, anthracite 31; large washed beans, 25-55 mm. : long flame 40, anthracite 41; small washed beans, 10-25 mm. : long flame 34-50, anthracite 36; small washed smithy coal, 35-50; washed small, 0-22 mm. : long flame 31-50, gas 32; washed small, 0-10 mm. : long flame 29-50, gas 31, anthra- cite 28; small, 0-22 mm. : long flame 27, gas 29. Thro' and thro'; unwashed, 25 per cent, cobbles, long flame or gas 31-50, anthracite 26-50; briquettes, 45. Perrecy-les-Forges Coals: House: Grelasse, 60-80 mm., 43; Grelasson, 30-60 mm., 42; Chatille, 20-30 mm., 39. Manufactu-ring Coals : Thro’ and thro’, with 50 per cent, of small cobbles, 25; Gresil, 18-24 mm., 25; beans, 5-18 mm., 2; small, 0-18 mm., 21; dust, 0-5 mm., 16. Epinac Coals : House Coals : “ Grele garenne ” (below 60mm.), 43; “Grelasson” (mixture of “grele,” 2nd quality, and nuts), 38; large washed beans. 20-60 mm., 45; nuts, 15-30 mm., 39; Thro’ and thro’, free from dust (above 15 mm., 32. Manufacturing Coals : Thro' and thro’,